Week-6 Challenge: EV Drivetrain

1. Which types of power converter circuits are employed in electric and hybrid electric vehicle?  

Ans:

The followig are the converters circuits used in HEV and EV:

power electronics circuits in ev and HEV

Mainly there are  three types of converts used in the vehicle

i-AC-DC

ii-DC-AC

iii-DC-DC

i-AC -  DC converts are mailny used in the charging circuits ,where we give AC input to the vehicle butthe vehicle converts it to the DC , so that this power can be stored in the vehicle battery.This converts are also called as the RECTIFIERS converter.

ii-DC-AC converts are mialy used when the electric vehicle have an 3 pahse induction motor ase its main engine ,so this converts converts the DC voltage from the battery and give the AC supply input to the battery.DC-AC converts are called as INVERTERS.

iii-DC-DC this converts are used in electic vehicle which have an BLDC Motor as an primary engine motor,This converts give variable dc output.This converts are also called as CHOPPERS.

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

Duty cycle=70%

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

Ans:

we know   
`T=V.(kɸ)/(Ra)-w.(kɸ)^2/(Ra)`......(i)

We need to calculate the volatge at 70% duty cycle

V=72*0.7

so volatge(V)=50.4V

Putting the voltage value in the above equation(i)

`T=50.4*(0.7/0.5)-w*(0.7)^2/0.5`

So ,now

T=70.56-0.98w....(ii)

Tv=24.7+(0.0051)w^2.....(iii)

solving the equation (ii)&(iii)

70.56-0.98w=24.7+0.0051w^2

solving this equation we get +38.85 and -38.85

Therefore the spped(w)=38.85rad/sec

3. Develop a mathematical model of a DC Motor for the below equation using Simulink.   

      ω">ω=   V/Kϕ">ϕ -Ra/Kϕ">ϕ^2    .T

4.   Refer to the blog on below topic: 

            Induction Versus DC brushless motors by Wally Rippel, Tesla

            Explain in brief about author’s perspective. 

Ans:

i-During this years the lead acid battery is are rplaced by the lithium ion battery.

ii-author discribes about the two types of motors-1)BLDC and the 2) induction motor

iii-He says both this motors have there own advantage and limitations.

iv-Both DC brushless and induction drives use motors having similar stators. Both drives use 3-phase modulating inverters. The only differences are the rotors and the inverter controls. And with digital controllers, the only control differences are with control code. (DC brushless drives require an absolute position sensor, while induction drives require only a speed sensor; these differences are relatively small.

v-Heconclude  that DC brushless drives will likely continue to dominate in the hybrid and coming plug-in hybrid markets, and that induction drives will likely maintain dominance for the high-performance pure electrics