Condition Monitoring of SiC MOSFETs Based on Gate-Leakage Current Estimation

Silicon carbide (SiC) MOSFETs have a lower loss, faster switching, and better thermal conductivity compared to silicon MOSFETs; however, their reliability remains a major concern hindering their widespread adoption. In situ, low-cost condition monitoring of the devices within the power converter can alleviate this concern. Gate-leakage current has been shown to be one of the most consistent failure precursors of degraded SiC MOSFETs. This article presents an approach to monitor the condition of SiC MOSFETs by an in situ estimation of the gate-leakage current using an add-on circuit. A prototype converter along with the extended monitoring circuit is used to experimentally validate the proposed approach. The proposed strategy ensures that the gate-leakage current estimation approach is solely dependent on the gate-oxide degradation and has a minimum dependence on the converter's operating conditions, including duty ratio, dc-link voltage, switching frequency, and output power, opening opportunity to device-level prognostics using sophisticated algorithms.