Week-6 Challenge: EV Drivetrain
1.Which types of power converter circuits are employed in electric and hybrid electric vehicle?
ans- AC TO DC convertor- thes convertors convert ac signal to dc signal. it supply electrical power from commecial system to on board electrical battery. we can charge EV using electrical source. they are also known as rectifier. in this we connect pn junction diode to a battery.when ac supply pass through a pn diode during positive cycle current pass through it and during negative cycle current does not pass through. only dc cuurent comes out from a diode.
DC TO AC CONVERTOR- they convet dc signal to ac signal.they convert from signal of battery to ac signal to use. it is done by switching devices which continuosly turned on or off. stepping up is done by using transformer.it is done by powertransistor.
AC TO AC CONVERTOR- IT CHANGES MAGNITUDE and frequency of ac current.
DC DC CONVERTOR- it changes level of voltage of dc power by releasing and storing dc power. it uses inductor,transformer and capacitor. dc can be bidirectional.
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'.
ans- rated armature voltage is 72v duty cycle of 0.7 is given so output voltage is 72x0.7.
rated armature current = 400A,Ra=0.5 ohm, k*fi=0.7 volt second.
chopper switching frequency=400Hz,
vegicle torque speed characteristics is
motor torque speed characteristics is given
putting value and solving-
w=38.91,231.22 rad/sec,
N(rpm)=371.6 rpm;
4. Refer to the blog on below topic:
Induction Versus DC brushless motors by Wally Rippel, Tesla
Explain in brief about author’s perspective.
ripple explain how teechnogy moved from lead acid battery to lithium ion battery and dc brushed moror to brushless motor. he explin both motors and advatanges and disadvantages of both motors.
he explains induction motor has low starting torque and limited peak torque ability. but less heat dissipated. dc motor has torque greater torque.induction motor has less losses. and efficiency is optimized.
dc brushless motor less rotor heat is generated. peak point efficiency is higher. it can operate at unity power factor.here adjustable magnetic field is important.