Importance of Wide Band Gap Semiconductors in Electric Vehicles
The Plug-in Hybrid Electric Vehicle (PHEV) and Battery Electric Vehicle (BEV) are based on high-voltage battery systems such as 400V for EVs and 48V for PHEVs. The incorporation of high voltage makes system wiring less complex and lighter. The drivers and passengers must be protected from potentially lethal voltages and currents that are produced by the high power electronics. Potential hazards include overvoltage, overcurrent, power spikes, and electromagnetic interference. The required levels of safety can be achieved by setting up an isolation barrier at the die, package, or board level.
Diamond has the widest bandgap as compared to other semiconductors. In addition, diamond has highest electric breakdown field. But employing diamond is not cost efficient and the material is harder and require higher temperature to process. As of now, there are no diamond power devices available in the market. Similarly, Silicon Carbide (SiC) and Gallium Nitride (GaN) have similar and higher electric field and bandgap values. Semiconductors with wider bandgap can operate efficiently at higher temperature.
Silicon power devices can also operate at high frequencies, and is a wide bandgap material. A wider bandgap translates to a higher critical field. The high voltage capability of wide bandgap silicon carbide devices allow them to achieve lower on-state resistances, leading to faster switching speeds and unipolar operation in part because its carriers need to be accelerated to a much higher speed to overcome that wider gap.
During vehicle battery charging, the wide band gap materials are expected to reduce the electricity losses by approximately 70%. The material offers greater efficiency while operating the electric traction drive during vehicle usage, and while converting AC to DC power. The capability of wideband semiconductors to operate at higher temperature will lead to reduction in the size of other power electronic devices and cooling systems. The weight, size and cost of an EV, as well as drivable distance on a single charge, is directly related to the efficiency of its electronic power conversion system. One typical way to lower weight, cost and size of a power conversion system is to raise the switching frequency in switching regulators. At higher frequencies, active elements such as inductors, capacitors and transformers will shrink down in size and weight. Thus, wide band gap semiconductors are crucial components in modern electric vehicles.