Week-6 Challenge: EV Drivetrain

Aim:- To Study on EV Drivetrain.

Quetion:- 1] Which types of power converter circuits are employed in electric and hybrid electric vehicle?

Ans:-

Power Converter Circuits for EV( Electric Vehicle) and HEV(Hybrid Electric Vehicle):-

1. AC-DC Converter( rectifier)
2. DC-AC Converter(Inverter)
3. DC-DC Converter(DC Chopper)

1] AC-DC Converter:-

An AC- DC converter is a device that Convert an AC Voltage to DC voltage. AC-DC Converter used in On Board Changer and in fast charging Station.

Alternating Current:-

In alternating current the current changes direction and flows forward and backward. The current whose direction changes periodically is called an alternating current (AC). It has non-zero frequency. It is produced by AC generator, dynamo.

Direct Current:-

In direct current the current doesn’t change its magnitude and polarity. If the current always flows in the same direction in a conductor then it is called direct current. It has zero frequency. It is produced by cells, battery, DC generator

2] DC-AC Converter:-

DC to AC converter are one of the most important element in power electronic.this is because there are a lot of real life application.The electronic circut that Convert Direct current(DC) input into alternative current(AC) output is known as DC to AC Converter. In this DC to 3 phase AC inverter used. The traction (Induction motor) required AC input.

3] DC to DC Converter:-

The DC to DC converter convert one level of DC voltage to another level is known as DC to DC converter. Benefits of this Converter- It is a available as a Hybrid Cuircut with all element in a single chip and The is also used in the redulation and control of DC voltage. A DC chopper is a static device that convert fixed DC input voltage to a variable DC output voltage directly. It is used for control AC series motor in traction system and it can be used to control the speed of induction motor.

Type of DC to DC Converter are following:-

1) Buck Converter

2) Boost Converter

3) Buck and Boost Converter

1) Buck Converter:- In Buck Converter the voltage depend on the input voltage and the duety cycle of the Switch.

2) Boost Converter:- In Boost Converter it is Used to reduce the DC of Low voltage and High voltage.

3) Buck and Boost Converter:- In this converter is used for Buck Converter and Boost Converter of DC voltage and it is more efficient because of using less component.

Quetion:- 2] An Electric Vehicle's powertrain with 72V battery pack in shown in the diagram below. The duty ratio for acceleration operation is 'd1' and for the braking operation the duty ratio is 'd2'.

The other parameters of the electric vehicle is given below,

Motor and Controller Parameters:

Rated Armature voltage= 72 V

Rated armature current= 400 A

Ra= 0.5Ω, KΦ= 0.7 Volt second

Chopper Switching frequency= 400 Hz

The vehicle speed-torque characteristics are given by the below equation

What is EV steady state speed if duty cycle is 70%?

Ans:-

Given input parameter of EV:-

Armature voltage=72 volt

Armature current= 400 A

Ra= 0.5 Ohm

KΦ=0.7 volt sec

Chopper switching frequency=400 Hz

Duty Cycle = 70%

The equation for Vehicle Speed- Torque characteristics= Tv=24.7+0.0051w^2.

Find Steady Stage Speed (rpm)

Question:- 3] Develop a mathematical model of a DC Motor for the below equation using Simulink.

ω= V/Kϕ -Ra/Kϕ^2 .T

Ans:-

Given value:- Voltage = 50.40 Volt

Constant Kphi= 0.7 Volt Sec

Ra (Resistance of armature)= 0.5 Ohm

Find value of T=24.7+(0.0051*38.92^2)

Torque (T)= 32.42 N-m

We can see value of Omega in Display= 38.92 rad/sec.

Quetion- 4] Explain in brief about author’s perspective

Ans:- Induction Vs BLDC motor-

The Wally Ripple, write to the different between the two motor drive used in HEV and EV Vehicle. Which is motor Drive name as DC Brushless motor drive Vs Induction motor drive.

Brushless Direct Current Motor(BLDC):- BLDC motor consist of a rotor that includes multiple permanent magnet to generate a DC magnetic field.this magnetic field enter the stator core made up of stacked lamination. while interactings with the current flowing withing the winding.It produce torque interration between the stator and the rotor. the rotor rotate.it becomes essential for the magnitude and the polarity of the stator current to very to ensure that the torque remain constant. thus it enhances the efficiency of the conversion of mechanical energy to electric energy.The device providing the necessary current control is known a s inverter, BLDC motor are useless without this inverter. Efficiency of BLDC motor is high because, No losses in the brushes, stator is on the outer periphery and thus, able to dissipable more heat and produce more torque.It give high speed range because in this motor no used brushes. BLDC motor is commanly used in EV.

3- Phase Induction Motor:- The structure of the stators of the BLDC motor and the 3- Phase induction motor is same.a rotating element machine that designed to operate on a 3-phase supply.The principle of operation of this this motor is based on the production of a rotating magnetic field.These 3- phase Induction consist of a stator and a rotor and There stator and rotor are constructed with the use of high magnetic core materials in order to reduces hysteresis and eddy current losses.Efficiency of Induction motor is low beacuse,Heat and current loses in both stator and rotor.