pe lab mannual

8/10/2019 PE Lab Mannual

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Power Electronics Lab Manual 1

TABLE OF LAB EXPERIMENTS

Sr.

No.

Experiment PageNo.

1 Single Phase uncontrolled Rectifier

i) Practically analyze the working and performance of singlephase rectifier.

4

2 Single Phase uncontrolled Rectifieri) Observe the effect of inductive load on working of a rectifier.ii) Use of a free wheeling diode.

8

3 Single Phase uncontrolled Rectifieri) Analysis of a full-wave bridge rectifier with RL load.

13

4 Half wave rectifier using R-Triggeringi) To analyze the resistive firing/triggering of silicon controlled

rectifier.

16

5 Half wave rectifier using RC Triggering

i) To analyze RC-firing Triggering network of silicon controlledrectifier.

23

6 Half wave rectifier using RC Triggering(Part Two)

i) To analyze RC-firing Triggering network of silicon controlledrectifier.

33

7 Full wave rectifier using resistive Triggering

i)

To analyze full wave R-firing network os SCR.

43

8 Full wave rectifier using RC Triggering.i) To analyze full wave RC-firing network os SCR.

51

9 TRIAC Characteristicsi) To study the V-I characteristics of a TRIAC in both directions

59

10 MOSFET Characteristicsi) To study the characteristics of MOSFET.

67

11 IGBT Characteristicsi)To study the characteristics of IGBT.

73

12 PWM generation for inverter circuits using 555 timers and 741 operationalamplifier-Natural Sampling Technique.

i)

To become familiar with pulse width modulation for operatingInverter circuits.

ii) Variation of duty cycle by comparing saw tooth waveform withConstant value.

iii)To study the operation of N-channel MOSFET operated usingPWM train.

77


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PREFACE

The laboratory of each and every subject taught in the degree of Bachelors in Electrical

Engineering is of very much importance in every University. Fully equipped laboratory meeting

the industrial demands under the supervision of qualified, talented and practically motivated lab

assistants and lab engineers is also a basic criterion of the Pakistan Engineering Council. This

Manual has been formulated considering all these above mentioned points.

With Regards

Engr. Hafiz Sikandar

.


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General Lab Instructions

Each student group consists of a maximum of 2-4 students. Each group member is

responsible in submitting lab report upon completion of each experiment on their

practical Note book.

Students are to wear proper attire i.e shoe or sandal instead of slipper. Excessive

jewelleries are not advisable as they might cause electrical shock.

A permanent record in ink of observations as well as results should be maintained by

each student and enclosed with the report.

The commands and observations from the simulator need to be approvedand signed

by the lab instructorupon completion of each experiment.


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Name

Reg. No

Marks / Grade

Experiment No.1

Single Phase uncontrolled Rectifier

Objective :

i) Practically analyze the networking and the performance of a single phase rectifier

Equipment :

AC supply ,a diode(1N4007) ,resistor(1k),Oscilloscope, DMM, connecting wires

Arrange the circuit as shown in figure 1.

Procedure:

1. Adjust the supply voltage as used in design procedure. Recommended is 10 peak voltage

at frequency of 50 HZ.

2. Arrange the circuit as shown in figure.

3. Record your observations and calculations in tabular form and also plot the waveforms

observed on oscilloscope.

4. Compare the practical output voltage with theoretical output voltage.

V1

Vp

50 Hz

0

D1

1N4007

R1


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Performance parameters :

1. Peak output voltage =Vm=------------

2. Average value of output voltage =Vdc=0.318*Vm=--------------

3. RMS value of output voltage =Vrms=0.5* Vm=---------------

4.

RMS value of output current =Irms=Vrms/R=------------------

5. Output DC power =Pdc=Vdc*Idc=--------------------

6. Output AC power =Pac =Vrms*Irms=-----------------

7. Secondary RMS voltage of Transformer or the Source=Vs=--------------

8. Secondary RMS current of Transformer or the Source=Irms=--------------

9.

Secondary AC power supplied by Transformer or the Source=Ps= Irms*Vs=--------------

10.Peak Secondary current of Transformer or the Source=Im=Vm/R=--------------

Evaluate the following parameter (also write down the required formulae) :

1. Rectifier efficiency = =-----------------------

2. Form factor=-------------------

3.

Ripple factor=------------------4. Transformer or source utilization factor(TUF)=--------------

5. Crest factor(CF) of input current i=---------------

6. Input power factor=--------------


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Observe V0 on the oscilloscope and sketch it on a graph paper

Sketched input voltage:

Sketched output voltage:

Sketched voltage across the diode:


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Comment :

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Name

Reg. No

Marks / Grade

Experiment No.2


Objective :

i) Observe the effect of inductive load on working of a rectifier.

ii) Use of a free wheeling diode.

Equipment :

AC supply ,a diode(1N4007) , a bridge ,resistors(1k), inductor coil(10mH)Oscilloscope, DMM, connecting wires.

Arrange the circuit as shown in figure 2.an inductive load is added to circuit .

Procedure:

1.

Adjust the supply voltage as used in design procedure. Recommended is peak voltage at

frequency of 50 HZ.





V1

Vp

50 Hz

0

D1

1N4007R1

L1


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4.






9.

Secondary AC power supplied by Transformer or the Source=Ps= Irms*Vs=--------------



1. Rectifier efficiency = =-----------------------

2. Form factor=-------------------

3.

Ripple factor=------------------4. Transformer or source utilization factor(TUF)=--------------

5. Crest factor(CF) of input current i=---------------



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Section ii:

Use of a free-wheeling diode:

Arrange the circuit as shown in figure 3.a free-wheeling diode is added to circuit .

Observe V0and I on the oscilloscope and sketch them on a graph.

Sketch the output voltage:

Sketch voltage with RL load:

V1

Vp

50 Hz

0

D1

1N4007R1

L1

Dm1N4007


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Sketch voltage across free-wheeling diode:

Comment :

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Using signal generator supply apply the voltage at high frequency to a half wave diode rectifier

and observe the response with resistive load and sketch output voltage.

Comment on the response at high frequency.

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Name

Reg. No

Marks / Grade

Experiment No.3


Objective :

i) Analysis of a full-wave bridge rectifier with RL load

Equipment :

AC supply , a bridge ,resistors(1k), inductor coil.(10mH) Oscilloscope, DMM,

connecting wires

Arrange the circuit as shown in figure 4.an inductive load is added to circuit .

Procedure:

1. Adjust the supply voltage as used in design procedure. Recommended is peak voltage at

frequency of 50 HZ.


3.

Record your observations and calculations in tabular form and also plot the waveforms



R1

L1

V1

Vp

50 Hz

0

D11N4007

D21N4007

D31N4007

D41N4007


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4.






9.

Secondary AC power supplied by Transformer or the Source=Ps= Irms*Vs=-------------



1. Rectifier efficiency = -----------------------

2. Form factor=-------------------

3. Ripple factor=------------------

4. Transformer or source utilization factor(TUF)=--------------

5.

Crest factor(CF) of input current i=---------------



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Observe V0and I on the oscilloscope and sketch them on a graph.

Sketch the output voltage with resistive load:

Sketch voltage with RL load:

Comment :

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Name

Reg. No

Marks / Grade

Experiment No.4

Half wave rectifier using R-Triggering

Objective:

i)

To analyze resistive firing/triggerimg silicon controlled rectifier(SCR).

Equipment :

AC Supply, SCR(MCR100-6),a diode, load resistor of designed value, variable gate

resistance(0-100K).

Half wave Rectifier using R-triggering:

Design problems:

Minimum resistance (Rmin):


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the minimum resistance Rmin should be such that when Rg=0,the gate current does not exceed

the maximum allowable value,

Rmin=Vs/Ig(max) ----------------(1)

Vs(max)= -------------(It is equal to max. voltage supplied by the Ac supply)

Ig(max)= --------------(the max. gate current is usually given by Igt in the datasheet)

Using equation (1):Rmin= ------------(choose the nearest standard resistor)

The value of selected standard resistor =Rmin= --------------------

Gate Resistance (Rg):

The min.value of gate triggering current is selected as specified in datasheet(80uAin case of

MCR 100-6)the SCR will turn on when instantaneous value of supply voltage Vs becomes equal

to:

Vs>- to Ig (min.)[Rg+Rmin]+Vg(min.)+VD -----------------(2)

Rg+Rmin.


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Procedure:

1. Adjust the supply voltage as used in design procedure. Recommended is 15Vpeak at

frequency of 50 HZ.


3.

Keep the potentiometer resistance Rg to its max. value so Ig is very small and SCR isnot triggered. Measure and observe the voltage across load and SCR.

4. Decrease the resistance of potentiometer Rg such that SCr is now fired and almost all

the input voltage appears across the load. Measure and observe the change in voltage

across the SCR.

5. Record your observations for at least ten different firing angles over the entire range

of observations.

6. Record your observations and calculations in tabular form and also plot the

waveforms observed on oscilloscope.


Observation set No.1:

No. Firing angle (a) V0(dc)

(practically using

DMM)

Vo(dc)

(theoretically

using calculations)

1

2

3

4

5

6

7

8

9


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Sketch voltage waveform across load resistance for firing angle in reading 2

Sketch voltage waveform across load thyristor for firing angle used above



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Show your calculations in firing angle in reading 3


Sketch variations of output voltage with firing angle


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Name

Reg. No

Marks / Grade

Experiment No.5

Half Wave Rectifier using RC-Triggering

Objective:

i) To analyze RC-firing/triggering network of silicon controlled rectifier

Equipment:

AC-supply, SCR(MCR 100-6),a diode, load resistor of designed value, variable gate

resistance(0-100kohm)

And capacitance of designed value.

HALF WAVE RECTIFIER USING R-TRIGGERING

Section 1:Half Wave rectifier using RC-Triggering


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Design Procedure:

Minimum Resistance(Rmin):

The minmum resistance Rmin shoule be such that when RG=0,the gate current does not exceed

the maximum allowable value,

Rmin=Vs(max)/ig(min)

Vs(max)=_______________(it is equal to the maximum voltage supplied by the AC supply)

Ig(max)=_______________(This maximum gate current is usually given by IGT in the

datasheet)

Using Equation (1):Rmin=_____________(choose the nearest standard resistor)

The value of the selected standard resistor=Rmin=_____________

An empirical relation for the product RC is

RC>=0.65T

T=1/f=time period of supply voltage

Gate Resitance(RG):

The minimum value of gate triggering current is selected as specifies in the datasheet(80_A in

case of MCR 100-6).The SCR will turn on when instantneous value of supply voltage Vsbecomes equal to

Vs>=IG(min)R+VG(min)+VD

R


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VD=_____________(it is equal to the forward voltage drop across the diode)

IG=______________(it is the minimum value of gate current at which SCR fires)

VG=_____________(it is the gate-cathode voltage corresponding to IG(min))

Using equation (2):RG=_____________(choose the nearest standard resistor)

The value of the selected standard resistor=RG=_____________

Selction of load resistance:

Maximum value of anode to cathode from datasheet=_____________A

Latching current from datasheet=___________A

Holding current from datasheet=____________A

Choose a value of laod resitance such that anode to gate current does not exceed the rated current

and is not less than the latching current when SCR is conducting.it is recommended to selected

laod resistance such that of the rated current or less flows when SCR is conducting.(Latching

current IL is the minimum anode current required to maintain the thyristor in the On-state

immediately)after the thyristor has been turned ON and the gate signal has been removed.

Procedure:

1. Adjust the supply voltage as used in design procedure. Recommended is 15V peak at

frequency of 50Hz.


3. Keep the potentiometer resistance RG to its maximum value so IG is very small and SCR

is not triggered. Measure and observe the voltage across load and SCR.

4.

Describe the resistance of potentiometer RG such that SCR is now fired and almost all

the input voltage appears across the load. Measure and observe the change in voltage

across load and SCR.

5. Record your observation for at least ten different firing angles over the entire range of

observation.


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6. Record your observation and calculations in tabular form and also plot the waveform



Observations Set

o. Firing Angle Vo(dc)

(Practically Using DMM)

Vo(dc)

(TheoraticallyUsing

DMM)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.


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Sketch voltage waveform across thyristor for firing angle used above

0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms

Time



Time



Time


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Time



Time



Time


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Time



Sketch the variation of output voltage with firing angle.

Comments:

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0ms 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50m



Time

Compare two RC circuits in terms of performance

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_____________________________________________________________________________________________

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Name

Reg. No

Marks / Grade

Experiment No.6

Half Wave Rectifier using RC-Triggering Part Two)

Objectives:

i) To analyze RC-firing/triggering network of silicon controlled rectifier.

Equipment:

AC-supply, SCR (MCR 100-6), a diode, load resistor of designed value, variable gate

Resistance (0-750k) and capacitors of designed value.

Half Wave Rectifier using RC-Triggering


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Design Procedure:

Minimum Resistance (R min):

The minimum resistance R min should be such that when RG=0, that gate current doesnot exceed the maximum allowable value,

R min =Vs (max) / Ig (max) (1)

Vs (max) = ________________(It is equal to the maximum voltage supplied by the AC

Supply)

Ig (max) = _________________(This maximum gate current is usually given by IGT in

The datasheet.)

Using Equation (1): R min =________________(choose the nearest standard resistor)

The value of the selected standard resistor = Rmin

=____________________

An empirical relation for the product RC is

RC 0.65T

T=1/f=time period of supply voltage

Gate Resistance (RG):

The minimum value of gate triggering current is selected as specified in the datasheet

(80A

In case of MCR 100-6).The SCR will turn on when instantaneous value of supply

voltage Vs


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Becomes equal to

Vs IG (min) R + VG (min) + VD (2)

R Vs VG (min) VD / IG (min) (3)

R = RG + R min

VD =________________________ (It is equal to the forward voltage drop across the diode).

IG (min) = __________________ (It is the minimum value of gate current at which SCR fires).

VG (min) = ________________ (It is the gate-cathode voltage corresponding to IG (min)

Using Equation (2): RG = _______________________ (choose the nearest standard resistor)

The value of the selected standard resistor = RG=_____________________________

Selection of load resistance:

Maximum value of anode to cathode current from data sheet = _____________ A

Latching current from data sheet = _____________________ A

Holding current from data sheet = _______________________ A

Choose a value of load resistance such that anode to cathode current does not exceed the rated

current and is not less than the latching current when SCR is conducting. It is recommended to

Use 820 ohm as load resistance.


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Procedure:

1.Adjust the supply voltage as used in design procedure. Recommended is 10V peak at

frequencyof 50HZ.

2. Arrange the circuit as shown in figure 4a.

3. Keep the potentiometer resistance RG to its maximum value so IG is very small and SCR is

not trigged. Measure and observe the voltage across load and SCR.

4. Decrease the resistance of potentiometer RG such that SCR is now fired and almost all the

input Voltage appears across the load .Measure and observes the change in voltage across load

and SCR.

5. Record your observations for at least ten different firing angles over the entire range of

observation.

6. Record your observations and calculations in tabular form and also plot the waveform




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Observation Table:

NO Firing Angle Vo(dc)

(Practically using DMM)

Vo(dc)

(Theoretically using

calculations)

1.

2.

3.

4.

5.

6.

7.

8.

9.


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Sketch voltage waveform across thyristor for firing angle used above:

Sketch voltage waveform across load resistance for firing angle in reading 6:



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Show your calculations for voltage with firing angle in reading 3:

Show your calculations for voltage with firing angle in reading 7:


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Sketch the variation of output voltage with firing angle:

Comments:

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Name

Reg. No

Marks / Grade

Experiment No. 7

Full Wave Rectifier Using Resistive Triggering

Objectives:

i) To analyze full wave R - firing network of SCR.

Equipment:

Ac supply, oscilloscope, SCR (MCR 100-6), single phase Diode Bridge, load resistor of

designed value, virile gate rsistance, connecting wires and breadboard.

Circuit diagram:

Task:

Vary the firing angle by the gate resistance from 0 to 90 degree and observe load voltage and

voltage across thyristor on the oscilloscope .sketch waveforms for selected value of firing angle.


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Design Procedure:

The design equations are same as used in experiment no 2 for half wave R-triggering.

1. Load Resistance =_____________ohms.

2. Rmin= __________ohms.

3. Gate resistance= ______________ohms.

Procedure:

1. Adjust the supply voltage as used in design procedure .recommended is 10 V peak at

frequency of 50 HZ.

2. Arrange the circuit as shown in Figure 4a.

3. Keep the potentiometer resistance Rg to its maximum value so Ig Is very small and SCR will

not triggered .Measure and observe the voltage across load and SCR.

4. Decrease the resistance of potentiometer Rg such that scr is now fired and almost all the input

voltage appears across the load .measure and observe the change in voltage across load and SCR.

5. Record your observations for at least 10 different firing angles over the entire range of

observations.





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0s 5 ms 10 ms 15 ms 20 ms 25 ms 30 ms 35 ms 40 ms 45 ms

Time



Time



Time


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Sketch voltage waveform across thyristor for angle used above:


Time



Time

Sketch voltage waveform across thyristor for firing angle above:


Time


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Time



Time



Time


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Comments:

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________

Performance Parameters:

Evaluate the following parameters by consulting the suggested pre-lab reading .Also consult thelab manual handout of experiment no.1 (use a separatepaper sheet if required, to record the

required observations and details of calculations):

Rectifier Efficiency= _______________________

Form Factor= __________________________

Ripple Factor= ______________________________

Transformer or Source Utilization Factor (TUF) = ___________________

Epress the output voltage (at firing angle of 30 degree) with Fourier series.


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Name

Reg. No

Marks / Grade

Experiment No.8

Full Wave Rectifier Using RC-Triggering

Objectives:

i)

To analyze full wave RC-firing network of SCR.

Equipment:

AC supply,oscilloscope,SCR(MCR-100-6),single phase diode bridge,load resistors,

variable gate resistance,capacitors,connecting wires, breadboard.

Circuit Diagram:

Task:


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Verify the firing angle (90 to 180 degree) by changing the gate resistance and observe load

voltage and voltage across thyristor on the oscilloscope.Sketch for selected values of firing

angle.

Load resistance=--------------------ohms

Gate resistance= --------------------ohms

R min=--------------------------------ohms

Capacitor=---------------------------

Procedure:

1. Adjust the supply voltages as used in design procedure.

2. Arrange the circuit as in figure.

3. Keep the potentiometer resistance RGto its maximum value so IGis very small and

SCR is not triggered.Measure and observe the voltage across load and SCR.

4. Decrease the resistance of potentiometer RGsuch that SCR is now fired and almost

All the input voltage appears across the load.Measure and observe the change in

The voltage across load and SCR.

5. Record your observations for at least ten different firing angles over the entire range

of observations.

6. Record your observations and calculations in tabular form and also plot the

Waveforms observed on oscilloscope.

7. Compare the practical output with theoretical output voltage.


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Observations Table:

V0 (DC)

Theoretically

Calculations

V0 (dc)

Using DMM

Firing Angleo.


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Sketch voltage waveform across load resistance for firing angle in reading 2.

0s 5ms 10ms 15ms 20ms 25ms 30ms 35ms 40ms 45ms 50ms

Sketch voltage waveform across thyristor for firing angle used above.





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Sketch waveform across thyristor for firing angle used above.



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Show your calculations for voltage with firing angle in reading 3.

Show your calculations for voltage with firing angle in reading 7.

Sketch the variation of output voltage with firing angle.


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Comments:

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-----------------------------------------------------------------------------

Performance Parameters:

Rectifier Efficiency =----------------------

Form Factor =-------------------------------

Ripple Factor =-----------------------------

Transform or source utilization factor(TUF) =------------------------


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II -mode:

1. Connections are made as shown in the circuit diagram (b)

2. The gate current is set as same value as in i-mode

3. Repeat the step no. s 3, 4, 5, 6, & 7 of I-mode

Circuit Diagram II-Mode:


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Characteristics curve:

Normal method:


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III-mode:

1. Connections are mode as shown in the circuit diagram (c).

2.

Step no. s 2, 3, 4, 5, 6, & 7 are to be repeated as in i-mode.

IV-mode:

1. Connections are mode as shown in the circuit diagram (d)

2. Repeat the step no. s2,3, 4, 5, 6, & 7 of i-mode.

Circuit Diagram For III & IV mode:


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Observations and Calculations:

I-Mode

Ig= mA

Sr.no. VTRIAC(V) ITRIAC(mA)

II-Mode

Ig= mA



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III-Mode

Ig= mA


IV-Mode

Ig= mA



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Comment :

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Name

Reg. No

Marks / Grade

Experiment no.10

MO SFET C harac ter is t ics

Objective:

To study the characteristics of MOSFET.

Equipment:

MOSFET-IRF840, Power Supplies, Wattage Resistors, Ammeter, Voltmeter, etc.

Circuit Diagram:


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Procedure:

Drain Characteristics

1.

Connections are made as shown in the circuit diagram.

2. Adjust the value of VGSslightly more than threshold voltage Vth

3. By varying VI , note clown ID& VDSand are tabulated in the tabular column

4. Repeat the experiment for different values of VGSand note down IDv/s VDs

5. Draw the graph of IDv/s VDSfor different values of VGS.

Transconductance Characteristics

1. Connections are made as shown in the circuit diagram.

2. Initially keep VI and V2 zero.

3. Set VDS= say 0.6 V

4. Slowly vary V2 (VGE) with a step of 0.5 volts, note clown corresponding and VDS

readings for every 0.5v and are tabulated in the tabular column.

5.

Repeat the experiment for different values of VDS& draw the graph of IDv/s VGS.

6. Plot the graph of VGSv/s ID


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Observations and Calculations.

VGS=

VDS(V) ID(mA)

VGS=

VDS(V) ID(mA)

VGS=

VDS(V) ID(mA)

VGS=

VDS(V) ID(mA)


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Comment :

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Name

Reg. No

Marks / Grade

Experiment No.11

IGBT Charac ter i s ti cs

Objective:

To study the characteristics of IGBT

Equipment:

IGBT-IRGBC 20S, Power Supplies, Wattage Resistors, Ammeter, Voltmeter, etc.

Circuit Diagram:


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Procedure:

Collector Characteristics

1.

Connections are mode as shown in the circuit diagram.

2.

Initially setV2 toVGEI= 5v (slightly more than threshold voltage)

3. Slowly vary VI and note clown Icand VCE

4. For particular value of VGEthere is pinch off voltage (VP) between collector

and emitter.

5. Repeat the experiment for different values of VGEand note down Icv/s VCE

6. Draw the graph of Icv/s VCEfor different values of VGE.

Transconductance Characteristics

1. Connections are mode as shown in the circuit diagram.

2. Initially keep VI and V2 at zero.

3. Set VCEI= say 0.8 v

4. Slowly vary V2(VGE) and note downICandVGEreadings for every 0.5v and

enter tabular column

5.

Repeat the experiment for different values of VCEand draw the graph of Ic v/s

vot


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Observations and Calculations.

VGE=

VCE(V) IC(mA)

VGE=

VCE(V) IC(mA)

VGE=

VCE(V) IC(mA)

VGE=

VCE(V) IC(mA)


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Comment :

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Name

Reg. No

Marks / Grade

Experiment No. 12

PWM generation for inverter circuit using 555 timer and 741

Operational Amplifier Natural Sampling Technique

Objective:

1.

To become familiar with pulse width modulation for operating inverter circuits2. Variation of duty cycle by comparing sawtooth waveform with constant value.

3. to study the operation of N-channel MOSFET operated using PWM train.

Equipment:

A DC power supply, bread board, N-channel MOSFET (IRF540), two general purposesswitching transistors (2N3904 and 2N396), Operational Amplifier 741, 555 timer IC,

two variable resistors (50K-ohm), resistors of required values (4.7K,10K,1K) and

capacitors (1 uF and 47 PF)

Datasheet information:

Carefully study the datasheet of different components and find out the following parameters

N-Channel MOSFET (IRF540)

Drain source voltage = __________________


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Drain Current = _______________________

Gate-Source voltage = __________________

Turn ON time = ______________________

Turn OFF time = ______________________

Transistor 2N3904

Turn ON time = ______________________

Turn OFF time = _____________________

Rated Voltage = ______________________

Rated Current = ______________________

Transistor 2N3906:

Turn ON time = __________________

Turn OFF time = _________________

Rated Voltage = __________________

Rated Current = __________________

PIN configuration of 555 timers:


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4.

Now connect 741 in comparator mode as shown in figure below

5.

Check the output voltage waveform at pin 6 of 741 and sketch the waveforms below


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6. With the help of variable resistance connected at pin 2 of 741 adjust the duty of the

output waveform equal to 50% and sketch two cycles of waveform

7.

Now sketch the waveform of step 3 and voltage at pin 2 of Op-Amp and voltagewaveform at pin 6 of 741 at same scale. (Three waveforms)

8.

What do you observe from the above waveform?

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9. Does above waveform explain pulse width modulation ? which waveform is modulating

waveform in above waveform?

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10.

Now connect N-Channel MOSFET circuit as shown in figure below

11.connect oscilloscope across the load resistance and sketch waveform


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12.Vary the resistance controlling the duty cycle and record different reading in ascending

order of duty cycle.

No. ON Time Duty Cycle

Ratio

Voltage at

pin 2 of

Op-Amp

Vo (dc)

(Practically

using DMM)

Vo(dc)

(Theoretically

using

Calculations)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.


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For observations 9 from table:

Represent the Load waveform in terms of Fourier series. (Show details)

Sketch the spectrum up to 20th

order harmonic


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What do you mean by natural sampling?

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Comments:

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How we can remove the 3rd

harmonic and its multiples from the spectrum?

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Note: On each graph clearly mention your time scale and magnitude; Plot at least two complete

cycles of waveforms else there will be zero credit. All the readings should be in sequence. Make

sure your roll number is written on each and every page of this handout. Please check the website

pe lab mannual

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