Week-6 Challenge: EV Drivetrain
1. Which types of power converter circuits are employed in electric and hybrid electric vehicle?
Ans:-1 Power converter circuit is used to convert nature of electricity and to control the supply voltage. Many type of power circuits are used in EV and HEV such as Inverter, rectifier and Chopper (DC to DC). The controller control the frequency of motor to vary speed of vheicle by switching of electronic circuits. The switches are turned on/off by pulse width modulation and operate at very high frequency.
The power converter circuit consist of fast switching device such as semi-conductor and transistor. There are other transistor such as IGBT, MOSFET, SCR. These device have input as gate signals which turn on and off as per controller.
Ans:-2
T = Torque
V = Armature Voltage
R = Resistance
w = rad/sec
Speed-Torque characteristic
Tv=24.7+(0.0051)w^2
Formula,
T= (V*k/R)-(k^2*w/R)
24.7+0.0051*w^2 = ((V*k)/R)-((k^2*w/R)
24.7 +0.0051*w^2 = (72*0.7*0.7)/0.5-(0.7^2/0.5)^w
70.56-0.98*w = 24.7+0.0051*w^2
w^2+192.15*w- 8992.15 = 0
By using quadrativ equation
ax^2+bx+c=0
w= 38.95 rad/sec
Ans:-3
Ans:-4 In the blog the author has highlighted the positive and negative part of both the machines and construction of both Dc and Ac machine is explained. In DC motor permanent magnet are used which produces rotating magnetic field. This magnetic field induces forces on conductor which in turn rotated the rotor. Where as in AC motor AC supply is given to the stator winding and with electro magnetic induction principle the rotating magnetic field is generated which rotates the rotor and the speed of rotor is less than RMF speed. the difference between slip and synchronous speed is called slip. Induction motor is usually suitable for higher load in industries.
In DC motor less heat is generated in rotor and cooling is easier and peak point is higher. power factor of dc motor can be unity but for induction motor is 0.85. The speed of dc motor can be adjusted with strength of magnetic field. In case of induction motor there is no such adjustment.
The losses in dc motor is more as machine size is bigger, magetic losses increases and load efficiency drops. in Induction motor machine sizes grows, losses does not grow mormally.