mechatronic system design - tu delft ocw · 3 delft wb2414-mechatronic system design 2013-2014 5...

40
1 WB2414-Mechatronic System Design 2013-2014 1 Delft University of Technology Mechatronic system design Mechatronic system design wb24142013/2014 Course part 6 Prof.ir. R.H.Munnig Schmidt Mechatronic System Design Power electronics WB2414-Mechatronic System Design 2013-2014 2 Delft University of Technology Amplifiers for electromagnetic actuators 2 Contents Power electronics, what’s so special about it? Passive (power) electronic filters Why so many inductors? Current or voltage source amplifier output Actuator determined spec. Linear, dissipative power amplifiers Dynamic impact of power amplifiers Stability and frequency dependent characteristics Switched mode power conversion 4 quadrant power delivery PWM Amplifiers 3phase amplifiers

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Page 1: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

1

WB2414-Mechatronic System Design 2013-2014 1DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 6

Profir RHMunnig SchmidtMechatronic System Design

Power electronics

WB2414-Mechatronic System Design 2013-2014 2DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 2

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

2

WB2414-Mechatronic System Design 2013-2014 3DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 3

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 4DelftUniversity ofTechnology

Electronics in mechatronics

Analogue control Sensing

Power conversionADDA

3

WB2414-Mechatronic System Design 2013-2014 5DelftUniversity ofTechnology

The amplifier and actuator have to deliver a real force F at best equal to the control force

F

WB2414-Mechatronic System Design 2013-2014 6DelftUniversity ofTechnology

The task of the power amplifier is that of a controller

bullControlling the characteristics of an electromagnetic actuatormotor by controlling the actuator‐input signal the voltage and current

bullDistinguishing items

bull Power capability (Voltage Current)

bull Dynamic properties like stability and control bandwidth

bull Low or high output impedance (voltage or current source output)

bull Efficiency (Power dissipation)

bull Linearity full range proportional output value (freedom of distortion)

4

WB2414-Mechatronic System Design 2013-2014 7DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 7

Power Capability is directly visible

bullHigh voltage and current levels limit small size (solid‐state) integration

bull Discrete Components

bull Switching relays

bull Thermal Control

bull Risk of interference by strong magnetic and electric fields (EMC)

WB2414-Mechatronic System Design 2013-2014 8DelftUniversity ofTechnology

Dynamic Properties in two directions

bull Amplifiers are part of the position feedback loop

bull Delay for instance from latency in a digitally controlled amplifier will reduce

stability

bull Also the bandwidth how quickly can the current follow a setpoint change

(HF behaviour) is related to a negative impact on the phase

bull The dynamic load from the actuator(LRC) will impact stability of the

amplifier

Amplifier

Actuator

5

WB2414-Mechatronic System Design 2013-2014 9DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 9

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

WB2414-Mechatronic System Design 2013-2014 10DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 10

Efficiency

bull An amplifier converts a supply voltage current into a motor

voltagecurrentbull A difference of voltage means power loss unlesshellipbull A difference in current requires energy buffering in capacitors or

batteries

bull Switched modePWM amplifiers reduce dissipation but have other

special properties that have to be known

6

WB2414-Mechatronic System Design 2013-2014 11DelftUniversity ofTechnology

out

in

VV

Amplifiers for electromagnetic actuators 11

Linearity distortion

Momentary gaindepends on value of output

outV

inV

maxV

maxVClipping example

WB2414-Mechatronic System Design 2013-2014 12DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 12

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 2: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

2

WB2414-Mechatronic System Design 2013-2014 3DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 3

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 4DelftUniversity ofTechnology

Electronics in mechatronics

Analogue control Sensing

Power conversionADDA

3

WB2414-Mechatronic System Design 2013-2014 5DelftUniversity ofTechnology

The amplifier and actuator have to deliver a real force F at best equal to the control force

F

WB2414-Mechatronic System Design 2013-2014 6DelftUniversity ofTechnology

The task of the power amplifier is that of a controller

bullControlling the characteristics of an electromagnetic actuatormotor by controlling the actuator‐input signal the voltage and current

bullDistinguishing items

bull Power capability (Voltage Current)

bull Dynamic properties like stability and control bandwidth

bull Low or high output impedance (voltage or current source output)

bull Efficiency (Power dissipation)

bull Linearity full range proportional output value (freedom of distortion)

4

WB2414-Mechatronic System Design 2013-2014 7DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 7

Power Capability is directly visible

bullHigh voltage and current levels limit small size (solid‐state) integration

bull Discrete Components

bull Switching relays

bull Thermal Control

bull Risk of interference by strong magnetic and electric fields (EMC)

WB2414-Mechatronic System Design 2013-2014 8DelftUniversity ofTechnology

Dynamic Properties in two directions

bull Amplifiers are part of the position feedback loop

bull Delay for instance from latency in a digitally controlled amplifier will reduce

stability

bull Also the bandwidth how quickly can the current follow a setpoint change

(HF behaviour) is related to a negative impact on the phase

bull The dynamic load from the actuator(LRC) will impact stability of the

amplifier

Amplifier

Actuator

5

WB2414-Mechatronic System Design 2013-2014 9DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 9

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

WB2414-Mechatronic System Design 2013-2014 10DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 10

Efficiency

bull An amplifier converts a supply voltage current into a motor

voltagecurrentbull A difference of voltage means power loss unlesshellipbull A difference in current requires energy buffering in capacitors or

batteries

bull Switched modePWM amplifiers reduce dissipation but have other

special properties that have to be known

6

WB2414-Mechatronic System Design 2013-2014 11DelftUniversity ofTechnology

out

in

VV

Amplifiers for electromagnetic actuators 11

Linearity distortion

Momentary gaindepends on value of output

outV

inV

maxV

maxVClipping example

WB2414-Mechatronic System Design 2013-2014 12DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 12

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 3: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

3

WB2414-Mechatronic System Design 2013-2014 5DelftUniversity ofTechnology

The amplifier and actuator have to deliver a real force F at best equal to the control force

F

WB2414-Mechatronic System Design 2013-2014 6DelftUniversity ofTechnology

The task of the power amplifier is that of a controller

bullControlling the characteristics of an electromagnetic actuatormotor by controlling the actuator‐input signal the voltage and current

bullDistinguishing items

bull Power capability (Voltage Current)

bull Dynamic properties like stability and control bandwidth

bull Low or high output impedance (voltage or current source output)

bull Efficiency (Power dissipation)

bull Linearity full range proportional output value (freedom of distortion)

4

WB2414-Mechatronic System Design 2013-2014 7DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 7

Power Capability is directly visible

bullHigh voltage and current levels limit small size (solid‐state) integration

bull Discrete Components

bull Switching relays

bull Thermal Control

bull Risk of interference by strong magnetic and electric fields (EMC)

WB2414-Mechatronic System Design 2013-2014 8DelftUniversity ofTechnology

Dynamic Properties in two directions

bull Amplifiers are part of the position feedback loop

bull Delay for instance from latency in a digitally controlled amplifier will reduce

stability

bull Also the bandwidth how quickly can the current follow a setpoint change

(HF behaviour) is related to a negative impact on the phase

bull The dynamic load from the actuator(LRC) will impact stability of the

amplifier

Amplifier

Actuator

5

WB2414-Mechatronic System Design 2013-2014 9DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 9

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

WB2414-Mechatronic System Design 2013-2014 10DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 10

Efficiency

bull An amplifier converts a supply voltage current into a motor

voltagecurrentbull A difference of voltage means power loss unlesshellipbull A difference in current requires energy buffering in capacitors or

batteries

bull Switched modePWM amplifiers reduce dissipation but have other

special properties that have to be known

6

WB2414-Mechatronic System Design 2013-2014 11DelftUniversity ofTechnology

out

in

VV

Amplifiers for electromagnetic actuators 11

Linearity distortion

Momentary gaindepends on value of output

outV

inV

maxV

maxVClipping example

WB2414-Mechatronic System Design 2013-2014 12DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 12

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 4: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

4

WB2414-Mechatronic System Design 2013-2014 7DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 7

Power Capability is directly visible

bullHigh voltage and current levels limit small size (solid‐state) integration

bull Discrete Components

bull Switching relays

bull Thermal Control

bull Risk of interference by strong magnetic and electric fields (EMC)

WB2414-Mechatronic System Design 2013-2014 8DelftUniversity ofTechnology

Dynamic Properties in two directions

bull Amplifiers are part of the position feedback loop

bull Delay for instance from latency in a digitally controlled amplifier will reduce

stability

bull Also the bandwidth how quickly can the current follow a setpoint change

(HF behaviour) is related to a negative impact on the phase

bull The dynamic load from the actuator(LRC) will impact stability of the

amplifier

Amplifier

Actuator

5

WB2414-Mechatronic System Design 2013-2014 9DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 9

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

WB2414-Mechatronic System Design 2013-2014 10DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 10

Efficiency

bull An amplifier converts a supply voltage current into a motor

voltagecurrentbull A difference of voltage means power loss unlesshellipbull A difference in current requires energy buffering in capacitors or

batteries

bull Switched modePWM amplifiers reduce dissipation but have other

special properties that have to be known

6

WB2414-Mechatronic System Design 2013-2014 11DelftUniversity ofTechnology

out

in

VV

Amplifiers for electromagnetic actuators 11

Linearity distortion

Momentary gaindepends on value of output

outV

inV

maxV

maxVClipping example

WB2414-Mechatronic System Design 2013-2014 12DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 12

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 5: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

5

WB2414-Mechatronic System Design 2013-2014 9DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 9

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

WB2414-Mechatronic System Design 2013-2014 10DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 10

Efficiency

bull An amplifier converts a supply voltage current into a motor

voltagecurrentbull A difference of voltage means power loss unlesshellipbull A difference in current requires energy buffering in capacitors or

batteries

bull Switched modePWM amplifiers reduce dissipation but have other

special properties that have to be known

6

WB2414-Mechatronic System Design 2013-2014 11DelftUniversity ofTechnology

out

in

VV

Amplifiers for electromagnetic actuators 11

Linearity distortion

Momentary gaindepends on value of output

outV

inV

maxV

maxVClipping example

WB2414-Mechatronic System Design 2013-2014 12DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 12

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 6: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

6

WB2414-Mechatronic System Design 2013-2014 11DelftUniversity ofTechnology

out

in

VV

Amplifiers for electromagnetic actuators 11

Linearity distortion

Momentary gaindepends on value of output

outV

inV

maxV

maxVClipping example

WB2414-Mechatronic System Design 2013-2014 12DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 12

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 7: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

7

WB2414-Mechatronic System Design 2013-2014 13DelftUniversity ofTechnology

First a few definitions while keepingldquorealrdquoelectronics to the bare minimum

bullVoltage and current sourcebullOhmrsquos lawbullResistorsbullCapacitorsbullInductors

WB2414-Mechatronic System Design 2013-2014 14DelftUniversity ofTechnology

bull An ideal voltage source is a circuit element where the voltage across it is independent of the load (current) It has a zero source impedance It can be replaced by a short circuit when the influence of another electric source in the circuit is to be determined

bull An ideal current source is a circuit element where the current through it is independent of the load (voltage) It has an infinite source impedance It can be replaced by an open circuit when the influence of another electric source in the circuit is to be determined

bull Both do not exist in reality but only in physical models of circuits In reality one can only approximate its behaviour

Ideal voltage and current sources

+- +- +-

+- +- +-

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 8: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

8

WB2414-Mechatronic System Design 2013-2014 15DelftUniversity ofTechnology

Ohmrsquos law the definition of impedance

Source

Impedance (Z)

+

-

Current (I)

Voltage(V)

V

V IR IR

22 V

P IV I RR

Power in Watt (W)

( )( ) ( ) ( ) ( )

( )

V fV f I f Z f I f

Z f

Dynamic impedance Z(f)

WB2414-Mechatronic System Design 2013-2014 16DelftUniversity ofTechnology

Practical resistors

bull Resistor size is determined by the power dissipationbull (Wirewound) resistors have parasitic self inductance and

capacitancebull Range from mΩ to GΩ

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 9: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

9

WB2414-Mechatronic System Design 2013-2014 17DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

Self‐inductance of windings is related to induced magnetic field

Induced voltage by a changing magnetic field (Faraday)

wtwL e

2wt

d d

d d

d

d

w

IV n L

t

nI nL n n

I I

t

I

t

IwF

wf

d

d

t

Fmicro-E

+

_

L

2

d

d

IV L

t

nL

=

=Acirc

Inductor L with n windings

WB2414-Mechatronic System Design 2013-2014 18DelftUniversity ofTechnology

First dynamic impedance the coil or Inductor (symbol L from Lenz)

w( )

( ) ( )

( ) ( )c

d dIV t n L

dt dtV t V j LI

VZ j L

I

bull For AC the voltage leads the current

with 90degI

V+

_

L

Fourier transform d

dj

t

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 10: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

10

WB2414-Mechatronic System Design 2013-2014 19DelftUniversity ofTechnology

Power and energy in an inductor

1 1 1

0 0

pp p p

p p p p

2L L 10

sp

( )) )

( )) cos ) sin

sin cos ) average 0

d 1( )d ( )

( ) ( (

d ( )dd 2

( (

05 sin(2

(compare

t t I

t t

V

j L

VVt t I

j L L

t t

V j LI I

V V I I

P t

IE P t t I t L t L I t I LI

I V I V

E

t

2

ring 05 )kF

I

V+

_

L

bull The current as function of the voltage equals

bull The power equals

bull And the momentary energy equals

WB2414-Mechatronic System Design 2013-2014 20DelftUniversity ofTechnology

Practical Inductorsbull Inductor size is determined by the selfinductance and the

currentbull Inductors have parasitic capacitance resistance and eddy

current lossesbull Range from microH to several mH

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 11: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

11

WB2414-Mechatronic System Design 2013-2014 21DelftUniversity ofTechnology

A capacitor is storing electrical energy in charge on two separated plates with distance D and surface A

bull The capacitance is

bull In vacuum the permittivity ε0 is

bull The charge is

bull With AC the current leads the voltage by 90deg

Second dynamic impedance the Capacitor

-120 2

0

1885 10

c

q CV

2 2

p p p p kinsi

1( ) ( ) ( ) ( ) =

05 sin(2 (comn cos ) averag pe 0 05 0e 5ar )

dQ dV VI t C I t I j CV Z

dt dt I j C

P V I V It t t E CV mE v

CA

d

WB2414-Mechatronic System Design 2013-2014 22DelftUniversity ofTechnology

Practical Capacitorsbull Capacitor size is determined by the Capacitance and currentbull Capacitors have parasitic self inductance and resistancebull Range from 1pF (ceramic) to ~ gt 1 F (electrolytic super caps)

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 12: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

12

WB2414-Mechatronic System Design 2013-2014 23DelftUniversity ofTechnology

So do you recognise these elements

WB2414-Mechatronic System Design 2013-2014 24DelftUniversity ofTechnology

These parts are used to make filters forthe output of switching-mode amplifiers

bullVoltage dividers or attenuators

bull1st order low‐pass filters

bull2nd order low‐pass filters

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 13: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

13

WB2414-Mechatronic System Design 2013-2014 25DelftUniversity ofTechnology

A voltage divider

i

1 2

i 2o 2

1 2

VI

Z Z

V ZV I Z

Z Z

WB2414-Mechatronic System Design 2013-2014 26DelftUniversity ofTechnology

Discussion

bullDesign a first‐order low pass filter for 1000Hz

bull Use voltage dividerbull Choose best suitable components

bull Determine frequency response

bull Determine component values

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 14: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

14

WB2414-Mechatronic System Design 2013-2014 27DelftUniversity ofTechnology

1st order low-pass with capacitor

o 2

i 1 2

V Z

V Z Z

o

i

1

( ) ( )1

1 1

1 1

f

V j CG

V Rj C

j RC j

1 2

1 and Z R Z RC

j C

Corner frequency

0 0

1 12 f

RC

WB2414-Mechatronic System Design 2013-2014 28DelftUniversity ofTechnology

Questione prosciutto

bull Will this work with power transfer

from input to output

bull So what must be avoided

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 15: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

15

WB2414-Mechatronic System Design 2013-2014 29DelftUniversity ofTechnology

1st order low-pass with inductor without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

( ) ( )

1 1

11

f

V RG

V R j

jj

L

L

R

1 2 and ZL

L RZR

j

Corner frequency

0 0

12

Rf

L

Z2 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 30DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 30

A second order passive low pass filter without series resistor

o 2

i 1 2

V Z

V Z Z

o

i

22

20

1

( ) ( )1

1 1

1)

( 1

f

V j CG

V j Lj C

j LC

1 2 0

1 1 Z j L Z

j C LC

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 16: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

16

WB2414-Mechatronic System Design 2013-2014 31DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 31

A second order low pass filter with parallel damping

o 2 3

1i 1 2 31

2 3 2 3

1 1

1 11 1

V Z ZZV Z Z Z

ZZ Z Z Z

o

i

2 22

2 20 0 0 0

1( ( )

11

1 1 1

2( 1) 1

)

1

f

VG

Vj L j C

R

L j jj LC jR Q

1 2 3

0

1 Z

1 1 1

2 2

Z j L Z Rj C

L CQ R

R C LLC

Z3 represents the power in the load

WB2414-Mechatronic System Design 2013-2014 32DelftUniversity ofTechnology

Mechatronic system design WB2414 R Munnig Schmidt 32

A second order low pass filter with parallel damping

2

20 0

1( )

1fG

jQ

Q=1

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 17: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

17

WB2414-Mechatronic System Design 2013-2014 33DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 33

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 34DelftUniversity ofTechnology

Group discussion

bull Discuss difference of voltage and current control to drive an

actuator in mechatronic systems

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 18: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

18

WB2414-Mechatronic System Design 2013-2014 35DelftUniversity ofTechnology

A current source output will cancel effects of the self inductance and motion EMF

a ma m LR

ddI

VV V tR

IR

V LVV

R

With a voltage source the current is

With a Lorentz actuator a current source will create a direct conversion from the setpoint(control force) to actuator force

WB2414-Mechatronic System Design 2013-2014 36DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 36

Low or high output impedance of an Amplifier

bull Low impedance (voltage source output)

bull When damping is necessary

bull Loudspeakers

bull Feedforward (no feedback)

bull High impedance (current source output)bull When the currentforce has to be independent of the movement

(Lorentz actuators)

bull When the currentforce has to be independent of the self inductance

(servo systems)

Actuator

Ra

La

Ua

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 19: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

19

WB2414-Mechatronic System Design 2013-2014 37DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 37

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 38DelftUniversity ofTechnology

Linear power amplifiers

bull A linear power amplifier is nothing else than a powerful version of

a small signal amplifier

bull It is often designed like an operational amplifier with high‐power

output stage

bull So it starts with the basic Op‐amp

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 20: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

20

WB2414-Mechatronic System Design 2013-2014 39DelftUniversity ofTechnology

The analogue (operational) amplifier is an integrated feedback-controlled system

Complementary sensitivity

a oaoo

i ao af a fa f

a o

1 1

1 1GGV

V G G GGG

WB2414-Mechatronic System Design 2013-2014 40DelftUniversity ofTechnology

1 Input currents in the Op‐amp are zero

2 With negative feedback the output will do whatever it can to keep the negative input voltage equal to the positive input voltage

Modelling1 Verify that there is Negative Feedback

2 Calculate the voltage on the positive input3 Calculate the voltage at the output by applying rule 1 and 2 which means that

it generates the same voltage over the feedback path at the negative input as

was calculated in step 2

Main guidelines of determining the behaviour of an ideal Op-Amp circuit

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 21: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

21

WB2414-Mechatronic System Design 2013-2014 41DelftUniversity ofTechnology

What source is the output of this amplifier

Voltage or Current source What is controlled

WB2414-Mechatronic System Design 2013-2014 42DelftUniversity ofTechnology

Transconductance amplifier has a current source output

bull Converts an input setpoint

voltage into an output current by measuring the current through the load and controlling

the output of the amplifier to keep the current proportional to the setpoint

bull Used for driving electromagnetic actuators

bull Rcs measures current but thereis a better way without voltage

drop

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 22: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

22

WB2414-Mechatronic System Design 2013-2014 43DelftUniversity ofTechnology

Lossless current sensing for high current levels and improved efficiency

Amplifiers for electromagnetic actuators 43Hall sensor for magnetic field

Active compensation of magnetic field generated by current Ip

magnetic field

WB2414-Mechatronic System Design 2013-2014 44DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 44

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 23: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

23

WB2414-Mechatronic System Design 2013-2014 45DelftUniversity ofTechnology

Ideal and real properties of regular (non-power) operational amplifiers

Parameter Ideal Op Amp

OPA27 Unit

DC Open loop Gain (G0) infin 120 (=106) dB

Input impedance (Zin) infin 6106 Ω

Output impedance (Zout) 0 70 Ω

Input offset voltage (Vos) 0 lt 25 μV

Temp coeumlff of Vos (γ) 0 06 μVoC

Input bias current (Ib) 0 40 nA

Input offset current (Ios) 0 10 nA

Gain bandwidth product infin 5106 Hz

Common mode rejection ratio (CMRR)

infin 120 (=106) dB

WB2414-Mechatronic System Design 2013-2014 46DelftUniversity ofTechnology

Dynamic limitations of standard Op-Amp

Many capacitors

And with a power amplifier they are large

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 24: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

24

WB2414-Mechatronic System Design 2013-2014 47DelftUniversity ofTechnology

Often a dominant pole is applied ~1 Hz to compensate several poles

Gain‐bandwidth product is constant over this line

WB2414-Mechatronic System Design 2013-2014 48DelftUniversity ofTechnology

Discussion

What is the bandwidth of this amplifier

bull Gain BW product = 106

bull R1=100

bull R2=10000

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 25: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

25

WB2414-Mechatronic System Design 2013-2014 49DelftUniversity ofTechnology

What is the impact of the dominant pole on the current source output impedance

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull Cut the loop just before the minus input

cfbl a

o a cfb a o

oo l

o

G

G G

VG

V

V V I

V

IZ G

AmplifierinV

oVcfb 0V I

oISimplified

V

V

I to V

aG

WB2414-Mechatronic System Design 2013-2014 50DelftUniversity ofTechnology

bull The higher the loop‐gain the

better the current is controlled so the higher is the output impedance

bull The loopgain and output impedance is inverse

proportional to the frequency

bull So what is the character of the

output impedance

What is the impact of the dominant pole on the current source output impedance

inV

oV

oIo lZ G

cfb 0V II to V

AmplifierV

V aG

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 26: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

26

WB2414-Mechatronic System Design 2013-2014 51DelftUniversity ofTechnology

51

The actuator inductance creates an additional pole (RL)

This creates stability issues and a potential resonance

WB2414-Mechatronic System Design 2013-2014 52DelftUniversity ofTechnology

52

The actuator inductance creates an additional pole (RL)

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 27: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

27

WB2414-Mechatronic System Design 2013-2014 53DelftUniversity ofTechnology

WB2414 Mechatronic system design 53

Phase compensation can help the stability

But that changes the closed loop response which can be OK for rejection of resonances

Conclusion One has to ldquoshaperdquo the feedback loop inside the amplifier towards the application

WB2414-Mechatronic System Design 2013-2014 54DelftUniversity ofTechnology

Extreme example of loopshaping voltage source audio amplifier

Two internal poles

Two external poles (output filter)

Four internal zeros plus one pole

‐2

‐4

‐1

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 28: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

28

WB2414-Mechatronic System Design 2013-2014 55DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 55

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 56DelftUniversity ofTechnology

Main drawback of a linear non-switchingpower output stage is dissipation of energy

Issue 1 High supply voltage is needed with an inductive load

a R m L m

3

3

max mmax

d

dJerk

d

d

d dd

d

IV V V

t

x I

t

V V IR L

I

tI

V V LRt

=

=

I x

V x

x

Jerk

Snap

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 29: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

29

WB2414-Mechatronic System Design 2013-2014 57DelftUniversity ofTechnology

Issue 2 Current and voltage are not in phase

bull In case of pure inductor

d

dˆsin

ˆd( sin ) d(sin )ˆ ˆ ˆ ˆcos d d

I

t

I I t

I t tV I V t V LI

t t

V L

L L

WB2414-Mechatronic System Design 2013-2014 58DelftUniversity ofTechnology

Discussion

What happens at t1

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 30: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

30

WB2414-Mechatronic System Design 2013-2014 59DelftUniversity ofTechnology

Negative current with positive voltage

lloss p oo oP VII V V

4 quadrant operation any combination of +-V and I

fi t1

V

I +

+

_

_

WB2414-Mechatronic System Design 2013-2014 60DelftUniversity ofTechnology

4 Quadrant power delivery

4 quadrant operation Any combination of +-V and I

V

I +

+

_

_

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 31: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

31

WB2414-Mechatronic System Design 2013-2014 61DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 61

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

WB2414-Mechatronic System Design 2013-2014 62DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier) depending on duty cycle

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 32: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

32

WB2414-Mechatronic System Design 2013-2014 63DelftUniversity ofTechnology

PWM or switched mode power conversion

bullA switch does not dissipate energybull Switches can only create squarewave signals (onoff) when switching fast

bull Low pass filtering gives the average value (Fourier)bull L‐C filtering is non‐dissipative

WB2414-Mechatronic System Design 2013-2014 64DelftUniversity ofTechnology

Pulse width (duty cycle) modulation

Amplifiers for electromagnetic actuators 64

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 33: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

33

WB2414-Mechatronic System Design 2013-2014 65DelftUniversity ofTechnology

Power switches the MOSFET

Amplifiers for electromagnetic actuators 65

N-channelElectrons as charge carriers

WB2414-Mechatronic System Design 2013-2014 66DelftUniversity ofTechnology

Switching cycle step 1

Amplifiers for electromagnetic actuators 66

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 34: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

34

WB2414-Mechatronic System Design 2013-2014 67DelftUniversity ofTechnology

Switching cycle step 2

Amplifiers for electromagnetic actuators 67

WB2414-Mechatronic System Design 2013-2014 68DelftUniversity ofTechnology

Switching cycle step 3

Amplifiers for electromagnetic actuators 68

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 35: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

35

WB2414-Mechatronic System Design 2013-2014 69DelftUniversity ofTechnology

Switching cycle step 4

Amplifiers for electromagnetic actuators 69

WB2414-Mechatronic System Design 2013-2014 70DelftUniversity ofTechnology

Change of duty cycle Rload=5 Ω

Amplifiers for electromagnetic actuators 70

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 36: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

36

WB2414-Mechatronic System Design 2013-2014 71DelftUniversity ofTechnology

Charge pumping with unipolar output voltage

Amplifiers for electromagnetic actuators 71

Io flows from positive supply and from negative supplyPositive supply delivers power Negative supply receives power

WB2414-Mechatronic System Design 2013-2014 72DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 72

In a bridge configuration these currents are balanced

Power supply to load and inductors

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 37: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

37

WB2414-Mechatronic System Design 2013-2014 73DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 73

In a bridge configuration these currents are balanced

Power recovery from inductors

WB2414-Mechatronic System Design 2013-2014 74DelftUniversity ofTechnology

Amplifiers for electromagnetic actuators 74

Contents

bullPower electronics whatrsquos so special about it

bullPassive (power) electronic filters

bull Why so many inductors

bullCurrent or voltage source amplifier output

bull Actuator determined spec

bull Linear dissipative power amplifiers

bullDynamic impact of power amplifiers

bull Stability and frequency dependent characteristics

bull Switched mode power conversion

bull 4 quadrant power delivery

bull PWM Amplifiers

bull 3‐phase amplifiers

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 38: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

38

WB2414-Mechatronic System Design 2013-2014 75DelftUniversity ofTechnology

Three phase actuators need threecurrents

Sum of currents is zero

WB2414-Mechatronic System Design 2013-2014 76DelftUniversity ofTechnology

Three phase amplifier concept

Question What goes wrong when all three amplifiers have a current‐source output

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 39: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

39

WB2414-Mechatronic System Design 2013-2014 77DelftUniversity ofTechnology

Three phase amplifier output stage

No charge pumping and three phase with three MOSFET pairsOne of the amplifiers is voltage controlled to keep the average voltage at zero

WB2414-Mechatronic System Design 2013-2014 78DelftUniversity ofTechnology

Mechatronic system design

Mechatronic system design wb2414‐20132014

Course part 7

Profir RHMunnig SchmidtMechatronic System Design

How to connect

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)

Page 40: Mechatronic system design - TU Delft OCW · 3 Delft WB2414-Mechatronic System Design 2013-2014 5 University of Technology The amplifier and actuator have to deliver a real force F,

40

WB2414-Mechatronic System Design 2013-2014 79DelftUniversity ofTechnology

The V-model of Systems EngineeringFunctional requirements Realized functions

Detailed design Timeline

System design

Subsystem design

Feedback loops

WB2414-Mechatronic System Design 2013-2014 80DelftUniversity ofTechnology

Main items to keep in mind

bull ldquoNestingrdquo

bull Lower parts are nested inside higher parts in the V model

bull Many nested control systems (amplifier current motion)

bull All influence eachother in two directions

bull Mechanical dynamics determine the final performancebull Bandwidth limited by eigenmodes

bull Power Amplifier and actuator are one

bull Control force to real force

bull Optimal tuning in dynamics and electrical properties

bull Motion Control is both the connecting lead as the polishing layer

bull Model based feedforward to almost perfection

bull All physical systems (plant=ADDA amplifier actuator mechanics

sensor) to be included in model

bull Feedback for robustness (to be minimised by feedforward)