Impact of Operating a SiC-MOSFETs Body Diode Beyond its SOA

Inhalt:
To lower the switching-losses of SiC-Power-MOSFETs in a half-bridge setup, the switching speed can be maximized by using dead-time-optimization. Due to a short dead-time, the reverse recovery current after the interlock period between both switches is minimized, and therefore, the overvoltage during the diode turn-off is lowered. However, if the driver fails to meet the required dead-time, the overvoltage across the diode increases. In the worst case, the body diode will be operated under avalanche conditions due to high switching stress. This paper investigates the influence of repetitive avalanche stress on a SiC-Power-MOSFET’s body diode concerning possible degradation of the semiconductor.