Threshold Voltage Monitoring Method of SiC MOSFET Considering the Influence of Thermoelectric Coupling

Silicon carbide has a wider band gap and higher interface trap density. The threshold voltage shift caused by bias temperature instability is a challenge to the reliability of SiC MOSFET. In practical applications, the threshold voltage will change in real time with the change of power loss and junction temperature caused by the cooling system. Therefore, it is necessary to monitor the threshold voltage shift considering BTI and junction temperature, which is of great significance to the reliability research of SiC MOSFET. In this paper, we first analyze the components and temperature sensitivity of SiC MOSFET on-state drain-source resistance, then study the influence mechanism of bias temperature instability on chip resistance, and finally propose to use SiC MOSFET chip drain-source on-state resistance to monitor the threshold voltage shift caused by the coupling of junction temperature and bias temperature instability. This method can directly obtain the shift threshold voltage through the chip drain source on state resistance. It is also suitable for SiC MOSFET modules with anti-parallel diodes. Considering the influence of temperature, this method can realize the accurate monitoring of threshold voltage under complex working conditions.