Impacts of SiC-MOSFET Gate Oxide Degradation on Three-Phase Voltage and Current Source Inverters

In this paper, the performance variations of SiC MOSFET-based voltage and current source inverters under gate oxide degradation are studied. It is confirmed that the turn-on and turn-off delays of SiC MOSFETs change significantly by high electric field stress, which accelerates the gate oxide degradation. Variations in the turn-on and turn-off delays of switching devices extend or reduce the duty error of voltage source inverters and current source inverters. The performance variations of the voltage and current source inverter due to the duty error changes caused by the gate oxide degradation are analyzed through simulations. As a result, the gate oxide degradation worsens the performance of the voltage source inverter. Furthermore, the negative gate oxide degradation, which lowers the threshold voltage, decreases the performance of the current source inverter.