Week-6 Challenge: EV Drivetrain

Ans.to qno.- 2:

Given,

Source Voltage, Vs=72V & Duty Cycle(D)=0.7, k_fi = 0.7 Volt-sec

Thus, I/P voltage of the dc motor, Vin= 0.7*72V = 50.4V.

Now, A/q the vehicle Speed-torque characteristic is given as, Tv= 24.71 + (0.0051)W² ……(i)

But Motor speed-torque characteristic is givem by,

W= (Vin/k_fi)- ((Ra/(k_fi)² )*Tm) …… (ii)

Thus, putting the values of Vin, k_fi & Ra in (ii) we get,

Tm = 70.56 – 0.98W

Now, for steady state operation, Tv = Tm

24.7 + 0.0051W² = 70.56 – 0.98W

Solving this quadratic equation we get,

W = 38.82 rad/s = steady state speed of the motor

^{Ans.to qno.- 3}

I have attached the simulink file named as- "torquespeed.slx" which contains my solution. Here I have used:-

V=50.4Volts, K_Fi=0.7 & Armature Resistance=0.5 ohm alongwith the torque input as a step variable.

Finally, I have plotted the Torque vs Speed graph in XYPlot. Kindly find the attached File.

Ans. to qno.-1:

The Converters used in EV and HEV are- Inverters, Buck Choppers and Boost Choppers whichever is neccesary as per required.

Ans.to qno.-4:

According to the author both Induction Machine and Brushless DC machine have their pros and cons. The brushless DC machine in terms of cost of manufaturing is more costlier than Induction Machine. But for lower range of performance Brushless DC machine will have higher efficiency than Induction Machine whose efficiency of performance is highly commendable in pure electrics. Moreover in terms of heat generation and cooling too, brushless DC machine dominates Induction Machine. So overall, as of untill there's further advancement in brushless DC Machine for higher perfomance activities both the machines are going to work parallely. The brushless DC machine is going to dominate EV sector while Induction machine is going dominate other Higher Performamnce Electric Demands.