新能源stem世代 new energy stem generationengineering.vtc.edu.hk/downloads/nesg2019 ws3... ·...

新能源STEM世代

Inspiring Young Minds,

striving for a Greener Hong Kong

New Energy STEM Generation

”可載人太陽能車”工作坊(三) 電力驅動技術

22June2019

2

Key dates

Time to start!

1. Pre-registration 13th April 2. Workshops

27th April - 13th July

3. Technical submission 22th June - 27th July

4. Technical webcast 28th August

5. Submission of all documents 22th July – 27th July

6. Scrutineering day 21tst September

8. Event day 30th November

7. Semi-final

28th September

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1) Power train exploration2) Energy storage and motor system3) E-mobility 4) Typical questions

Contents

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Power train exploration

Hub motor

Battery pack

Solar panels

3 wheels:Solar Energy

Mechanical EnergyElectrical Energy

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Hub motorMPPT

Battery pack

Solar panels

3 wheels:Solar Energy

Mechanical EnergyElectrical Energy

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MotorMPPTBattery pack

Solar panels

4 wheels: Solar Energy

Mechanical Energy

Electrical Energy

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MPPTBattery pack

Solar panels

Solar Energy

Mechanical Energy

Electrical Energy Motor

Motor

Bad example:

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MPPTBattery pack

Solar panels

Solar Energy

Mechanical Energy

Electrical Energy

Motor

Motor

Working

Not Working

If one motor is not working:Car crash accidents

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Lets go through the electrical system calculation!

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Energy storage and motor system

Input

Power

Output

Power

Solar cells →Battery pack →motor

Rolling resistance

Wind resistance

Acceleration

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Power Sources:

1. Solar cell array giving 9 A, 120 V, (standard conditions);

2. 20, series-connected, 6-V, Ag-Zn batteries.

Power System Schematic

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Major Batteries developed for EVs

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Storing Electric Energy (1):

Storage Methods. All autonomous cars must use propulsive energy stored in the car.Vehicles using chemical storage run on the energy stored in gasoline or otherhydrocarbon fuels.

Solar energy can be stored in several ways: by sensible storage (heating a mass), byphase change storage (melting a substance) by electrochemical storage or capacitivestorage (conversion to electric energy and storage in a battery or capacitor,respectively), or by flywheel inertial storage (converting electric energy to rotationalkinetic energy and storing it in a spinning flywheel).

Note that inertial storage is intrinsic to all vehicles because each stores kinetic energyin its own mass and the rotating masses of its wheels and drive.

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Battery connection:

Example:

3.7 Volts x 10 in serial = 37 VBattery is 2600 mAhFor 3 sets in parallel = 2600mAh x 3 = 7.8AhBattery pack capacity(Wh) = 37 x 7.8 = 288.6 Wh

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4.17. Energy Source / storage

4.17.1. Any energy storage device, must not exceed a nominal voltage of 48 VDC.

4.17.2. The energy storage device, must be installed outside of the driver’scompartment.

Nominal voltage of battery will be referred to battery specification.

According to 4.18.2. The circuit drawing must contain batteries, fuses, circuit breakers, power switchers, solar generator, power trackers, capacitors, motor-controller or chopper, motor(s) and junctioncables.All components (including Battery) in the circuit drawing must be labelled with their detailed electrical specifications.

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4.17.3. Only one propulsion battery and one accessory battery per vehicle areallowed.

Propulsion battery

provide power to the power train

Li-ion battery pack need a Battery Management System (BMS)

Accessory battery

provide power to all safety devices such as, E-stop relay, Horn, lighting

cannot be used for cooling systems, electric motors

only one unit

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4.14.4. The energy storage device, including fuel cell, must be equipped withprotective measures to automatically isolate the said device in the event ofovervoltage, overcurrent, short-circuit, thermal overload and other abnormaloperation of the said device without the need for power other than from the saiddevice.

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Principle of DC machine rotation• Electric Current• Magnetic Field

• Force (Rotation)

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• Electric controller(ESC) is required to keep the motor running which is sometimes more expensive than the motor.

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Parameter:1. N (r/min): Revolution(s) Per

Minute2. Pout(W): Power output3. U(V): Motor voltage4. I(A): Motor current5. Pin(W): Power input6. η (%): Motor power

efficiency

Motor characteristic curve:

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Parameter:1. N (r/min): Revolution(s) Per

Minute2. Pout(W): Power output3. U(V): Motor voltage4. I(A): Motor current5. Pin(W): Power input6. η (%): Motor power

efficiency7. T(N.m.) Torque

𝑃 = 𝑉 𝑥 𝐼 = 𝑇 𝑥 𝑟𝑝𝑚𝑃in= V x I = 358.2 W

Pout= Pin x η= 358.2 x 0.772=276.5 W

Recall Lesson 1:

I = 9.95 A, V= 36V, and η = 77.2 %

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Why in-wheel motor?

• high torque

• fast response

• gearless operation

• zero transmission loss

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Motor control example:

On/Off Forward/

Reverse Speed control Stop Light & horn Meter display

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新能源STEM世代



New Energy STEM Generation 2019

小休

27

E-mobility

• What is your designed external dimension?

• Which type of chassis do you choose?

– Monocoque

– Space frame/ I beam

• Hand-made or purchase

• Delivery date of the key component?

How about your project progress?

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E-mobility (I)

Flat SurfaceSheet metal?Thin Balsa wood?

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E-mobility (II)

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E-mobility (III)

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E-mobility (IV)

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E-mobility (V)

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Typical Questions

1. Any allowance for the limit of external dimension?

Dimension Limits

Max. Height 1300mm

Max. Width 1300mm

Max. Length 3500mm

Track width 50% of Width

Wheelbase >1000mm

Ground clearance >100mm

Max. vehicle weight (without driver)

225 kg

Driver compartment

Height >880mm

Width >700mm

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Typical Questions

2. Solar Panel limitation:4.15.2. Maximum allowable solar collector with Silicon solar cells is 1.0 𝑚2.

GaAs solar cells, the maximum solar collector array will be reduced to 50 per cent of the maximum solar collector area specified for Silicon solar cells

Examples: A-300 solar cell mono crystalline silicon:Dimension: 0.125m x 0.125 m = 0.015625 m2

Solar cells allowed: 1/ 0.015625 = 64

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Typical Questions

MPPT converter

Example:

We have 2 set of 50 W 18V,

2 set of 150W 24V.

At least 2 set of MPPT converter need.

The converter can only work under same voltage level.

Most efficient way is series the solar panels/ separate with converter.

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Typical Questions

4.14.3. All electrical enclosures, junction boxes, etc. containing harnesses orcomponents with nominal operating voltage over 50 VDC or VAC RMS must havehigh voltage warning labels on the enclosure.

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Typical Questions

IndependentBraking System

2Primary Braking

Parking Braking

Ensure the car can STOPmoving! Even one of them FAIL!

3. Brake:4.11.1. Two independently triggered braking systems commanded by one single command unit, e.g. a foot pedal or lever, must be installed onto the vehicle.

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Typical Questions

4.11.3. Each braking system must NOT act on only one side of wheels.

Caution: Each system must NOT act only one side of wheels

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Typical Questions

4. Light fitting

Headlights in white color

Front and rear turn indicators

In amber color

Stoplights in red color

Head light

Front indicatorBrake light

Rear indicator

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Typical Questions

Bracket Installation

5. Seat belt installation (at least 4-points)

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Typical Questions

6. Type of steering wheel

(must be in close-loop)

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Typical Questions

7. Steering rack

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Typical Questions

8. Wheels dimension

(can choose different sizes of wheels)

4.13.3. The dimension of all wheels must be identical, and

designed for the intended application, loads, and forces.

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Typical Questions

9. Fire extinguishermust be fitted with a 1kg fire extinguisher within the cockpit and be accessible to thedriver.

Securely mounted to prevent movement while driving/ braking

All drivers must be trained in using

Pressurised at least 8 bar to 13.5 bar

Info:– Capacity

– Type of fire extinguisher

– Weight

– Date: no more than 2 years

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Review: Bulkheads and Partitions

Driver Compartment (w/ Fire Extinguisher)

Wheel Compartment

Battery Compartment

Wheel Bulkhead

Joule meter Compartment

Bulkhead

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Review: Dimensions

Total Width

Track Width

650

1300

700

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完

新能源STEM世代

New Energy STEM Generation 2019

新能源stem世代 new energy stem generationengineering.vtc.edu.hk/downloads/nesg2019 ws3... ·...

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