Online Monitoring Method for Junction Temperature of SiC MOSFETs based on Temperature Sensitive Electrical Parameter

Compared to Si devices, the junction temperature of SiC devices is more critical due to the reliability concern introduced by immature packaging technology applied to new material. This paper proposes a practical SiC MOSFET junction temperature monitoring method based on the on-state voltage $\boldsymbol{V}_{\mathbf{ds}(\mathbf{on})}$ measurement. In Section II of the paper, the temperature sensitivity of the on-state voltage $\boldsymbol{V}_{\mathbf{ds}(\mathbf{on})}$ is characterized. The hardware of the measurement system is set up in Section III, which consists of an On-state Voltage Measurement Circuit (OVMC), the sampling and isolation circuit. Next, a calibration method based on the self-heating of the SiC MOSFET chip is presented in Section IV. In the final Section, the junction temperature is monitored synchronously according to the calibration results. The proposed method is applied to a Buck converter and verified by both an Infrared Radiation (IR) camera and a Finite Element Analysis (FEA) tool.