Week-6 Challenge: EV Drivetrain

Question 1

There are 4 types of power converters based on the input voltage and output voltage.

AC to AC converter also called as cycloconverter or frequency converter.

DC to DC converter , DC to DC voltage converter or DC to DC current converter. also called as DC choppers .

DC to AC converter ,also called as inverter because its inverting the voltage ( for example an inverter ,gets 12V , 24V or 48V DC converts into 230 V AC )

AC to DC also called as retifiers.

From the above 4 coverters, AC to AC coverters are not employed in electric and hybrid electric vehicle.

question 2

Given parameters

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

we have to find the speed for 70% duty cycle ?

solution=

actual voltage for 70% duty cycle

Voutput=Duty cycle * Vinput

= 0.7*72=50.4

we know the formula for calculating the speed of the motor

`Wm=V/kΦ-(Ra/(kΦ)^2*Tm)`

now wirting the equation W.r.t (Tm)

we get,

Tm=-Wm*(kΦ)^2/Ra+Voutput*kΦ/Ra

subsitute the vales we get

=Wm*(0.7)^2/0.5+50.4*0.7/0.5

Tm=-0.98Wm+70.56..........................................equation 1

................................equation 2 (Tv=Tm , Wm=W^2)

-0.98Wm+70.56=24.7+(0.0051)W^2

by solving the equation in calsi 991 ES ( slove for X)

we get the answer

Wm= 38.91 rad/sec.

this is the speed of the vehicle at 70% dudty cycle.

Question 4

Here the autor explains about the the Dc brushless motor and induction motor

he explains the working of both the motors and tells about the pros and cons of both the motors.

DC Brushless motor

Permenent magnet are very impotant in this motor.

this motor is made of thin stacked lamintions in which the currents flows and torque is produce.

inverter is very important for this motor without inverter this mortor is useless.

heat generated in very less in this motor as compare to induction motor.

due to magnent present if the size is increse the magnetic losses are also increases.

dc motor are expensive and high maintainence .

Induction motor.

induction motor work on currents flowing through stator windings producing a rotating magnetic field.

this motor does not have permenent magnet

this motor requies Ac supply to work .

the torque generated in this motor is low as compare to dc brushless motor

this motor are less expensive . and low maintainence cost

this motor does not reqire inverter.

Queston 3

assume data.

V= 72

K_fi=0.7

Ra=0.016

T= ramp block for increamental/decrease with respect to speed.

SOLUTION.