A fast forecasting model of electrothermal distribution for parallelled SiC MOSFETs

Abstract

Parameter dispersion of SiC MOSFETs causes unbalanced current distribution in parallelled devices, which could increase voltage and current stresses of power devices, and lead to thermal imbalance between the devices, and thus affecting the working life and the safe operation of the converter. In order to accurately forecast the thermal balance of SiC MOSFETs, this paper investigates the problem of predicting their electrothermal models. Firstly, the operating mode of the two parallelled MOSFETs is analysed, and the influencing factors affecting the current balance are derived. Then the losses of the power devices in parallel are analysed, and the forecasting model of the electrothermal distribution is derived. Finally, the electrothermal model is verified on the experimental platform. The experimental results show that the thermal distribution are basically similar to the prediction results of the mathematical model, which largely solves the inaccuracy of forecasting model of the electrothermal distribution.

Keywords

• SiC MOSFET
• Parallelled switches
• Forecasting model of electrothermal distribution