Figure 1: An EV requires a three-phase voltage source inverter (traction inverter) to convert high- voltage (HV) DC battery power into the AC power required by the vehicle’s electric motor(s). The HV system, including the traction inverter, is isolated from the vehicle’s conventional 12-volt system. (Image source: ON Semiconductor)
The switches in the example shown in Figure 1 are IGBTs. These have been a popular choice for a traction inverter because they are capable of handling high voltages, switch rapidly, offer good efficiency, and are relatively inexpensive. However, as the cost of SiC power MOSFETs has fallen and they have become more commercially available, engineers are turning to these components because of their notable advantages over IGBTs.
the WBG transistor can withstand much higher breakdown voltages than Si devices, as well as a resultant breakdown field voltage about ten times greater than Si. The high breakdown field voltage allows a reduction in device thickness for a given voltage, lowering the “on” resistance (R DS(ON) ) and thus reducing switching losses and enhancing current-carrying capability.
Advantage of SiC MOSFETs for high- efficiency gate drivers The key performance advantages of SiC power MOSFETs over conventional silicon (Si) MOSFETs and IGBTs derive from the devices’ WBG semiconductor substrate. Si MOSFETs have a bandgap energy of 1.12 electron- volts (eV) compared to SiC MOSFETs’ 3.26 eV. That means
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