Online Detection of SiC MOSFET Gate Oxide Degradation by Drain-Source Voltage Surge in Inverter

Gate oxide layer degradation has become one of the key issues in the reliability of SiC MOSFETs, which seriously restricts the broad application of SiC MOSFETs. Existing research is primarily based on the threshold voltage or gate leakage current, as well as other parameters, to indicate the degradation of the gate oxide layer. However, these methods generally have limitations, including high hardware requirements and difficulties with online experiments, which make it challenging to implement online detection under inverter operating conditions. In this paper, a novel online detection method of gate oxide layer degradation based on the drain-source surge voltage (V_surge) is proposed. Moreover, this paper analyses the relationship between the V_surge and the mechanism of gate-oxide layer degradation and designs a V_surge extraction circuit. Combined with the HTGB experiment, the effectiveness of the dynamic monitoring strategy is verified in the inverter system. The experimental results show that the proposed method can accurately online identify the ageing state of the gate oxide layer under a 300 V inverter.