how the electric car works

8/19/2019 How the Electric Car Works

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HOW THE ELECTRIC CAR WORKS ?

BY : Freddy Kurniawan/131-13-027Mechanical Engineering 2013

Basic Principle

-The Car is powered by electric motor rather by gasoline engine.-The motor gets it power from a controller.-The controller is powered from an array of rechargeable batteries.

This is the schematics from the block diagram how the electric car works.

I would like to introduce the working system of electric car through thecomponent or their parts itself.



1. MOTOR

• Electric cars can use AC as well as DC motors.

• The ranging voltage for the motor itself around 96 till 192 voltsand most of the come from forklift industry.

• Installation for the DC motor is much simpler than AC.

• But the limitation of the DC motor is that they can be self

heating and can be destruction for itself.

• So due to the limitation and other advantages by AC motors (like torque and speed output for the same weight and size ),ACmotors are more preferable for electric cars.

2. CONTROLLERS

• The main function for controller is to controlled voltage to the

motor , and depending upon potentiometer output.• It is circular in shape and it is hooked to the accelerator pedal.

The potentiometer, also called the variable resistor, provides thesignal that tells the controller how much power is it supposed todeliver.

• PWM controls the speed

DC Controller



Output of the signal

•

An AC controller creates 3 pseudo sine wave which are 120degrees apart (3-phase AC)

• Using six sets of power transistors, the controller is takes in 300volts DC and produces 240 volts AC, 3-phase.

3. BATTERIES

• Lead acid batteries used , until recently.-A weak link in the electric cars.-Heavy, Bulky , limited capacity (only give 12-15 Kwh), slowcharging rate , short life and expensive.

• NiMH batteries give double the range and last 10 years , butexpensive.

• Li-ion and NiMH batteries likely to used because the price iscompetitive



This is some of the batteries advantages and disadvantages basedon their type:

4. BRAKING

• Regenerative breaking along with conventional friction braking

• Motor as a generator

• Recaptures car’s kinetic energy and converts it to electricity torecharge the batteries



Theory of Operation for EV

When the driver steps on the pedal the potentiometer activates and provides thesignal that tells the controller how much power it is supposed to deliver. Thereare two potentiometers for safety. The controller reads the setting of the

accelerator pedal from the potentiometers, regulates the power accordingly,takes the power from the batteries and delivers it to the motor. The motorreceives the power (voltage) from the controller and uses this power to rotate thetransmission. The transmission then turns the wheels and causes the car tomove forward or backward.

If the driver floors the accelerator pedal, the controller delivers the full batteryvoltage to the motor. If the driver takes his/her foot off the accelerator, thecontroller delivers zero volts to the motor. For any setting in between, thecontroller chops the battery voltage, thousands of times per second to create anaverage voltage somewhere between 0 and full battery pack voltage.

CONCLUSION

• Electric Vehicle per charge still limited the battery.

• Usually 100km is common , Higher range needs more intelligent andmaterial. That includes : higher energy density , higher current battery ,lighter material , higher efficiency of machines , driver and powerconverter.



Reference

• http://en.wikipedia.org/

• www.howstuffworks.com

• “Build you own electric vehicle”,Seth Leitman and Bob Brant,

second edition , McGraw Hill , 2009. • Oregon Electric Vehicle Association.

how the electric car works

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