Week-6 Challenge: EV Drivetrain
EV LIVE BATCH 21
1)
AC TO DC Converter
The battery in plug-in hybrid electric vehicle and battery electric vehicles are needed to charge using dc supply.But if the charging station is providing only ac power, then we are needed to convert them into dc using converter
DC TO DC Converter
The battery in electric vehicle is of particular voltage, but we need different voltage for different equipment like headlight infotainment system etc. So we use dc to dc converter to get desired voltage.
DC TO AC Converter
The battery gives output as dc source, but we need AC source to drive the motor, so we use inverter to convert dc into ac supply.
4)
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.)
One of the main differences is that much less rotor heat is generated with the DC brushless drive. Rotor cooling is easier and peak point efficiency is generally higher for this drive. The DC brushless drive can also operate at unity power factor, whereas the best power factor for the induction drive is about 85 percent. This means that the peak point energy efficiency for a DC brushless drive will typically be a few percentage points higher than for an induction drive.
In contrast, induction machines have no magnets and B fields are “adjustable,” since B is proportionate to V/f (voltage to frequency). This means that at light loads the inverter can reduce voltage such that magnetic losses are reduced and efficiency is maximized. Thus, the induction machine when operated with a smart inverter has an advantage over a DC brushless machine – magnetic and conduction losses can be traded such that efficiency is optimized. This advantage becomes increasingly important as performance is increased. With DC brushless, as machine size grows, the magnetic losses increase proportionately and part load efficiency drops. With induction, as machine size grows, losses do not necessarily grow. Thus, induction drives may be the favored approach where high-performance is desired; peak efficiency will be a little less than with DC brushless, but average efficiency may actually be better.