Online Monitoring Method for SiC MOSFET Gate Oxide Degradation Based on Gate Voltage Filtering

Gate oxide degradation has been recognized as a critical reliability problem for SiC MOSFETs, which severely hinders the widespread adoption of SiC MOSFETs. Online monitoring of the gate oxide is essential for the lifetime extension and periodic maintenance of SiC devices. This paper introduces a novel online monitoring technique for SiC MOSFET gate oxide degradation without impacting the normal operation of the power converters, based on frequency spectrum characteristics extraction of transient gate voltage during the turn-ON process. By leveraging the original output of the driving IC as the trigger signal, our method automates the monitoring function, irrespective of the switching duty cycle or frequency. The monitoring circuit is sampling-friendly and cost-effective, eliminating the need for additional isolation barriers and offering compatibility with commercial drive ICs. The experimental validation shows that the significantly increased output voltage (25.6%) can accurately monitor the degradation of the gate oxide. Additionally, the practical applicability of this method is demonstrated through the testing in a single-phase inverter.