Improved Temperature Estimation Model of 4H-SiC MOSFET under Avalanche Condition

Silicon Carbide (SiC) Metallic Oxide Semiconductor Field Effect Transistor (MOSFET) has fast switching speed and under unclamped inductive switching (UIS) environment, the device may suffer from avalanche breakdown. In this occasion, it is necessary to estimate the temperature inside SiC MOSFET accurately. However, current models rarely consider the effect of temperature-dependent parameters, leading to inaccuracy estimation. In this paper, a Cauer thermal network considering the temperature-dependent property of material thermal characteristics under avalanche state is proposed. First, the relationship between temperature and material parameters is illustrated. Then, according to the scanning electron microscope (SEM) analysis, the geometric parameters of the chip are obtained, and the cell model of SiC MOSFET is built using Technology Computer Aided Design (TCAD). Next, a transient Cauer thermal network is proposed with temperature-dependent parameters considered. Finally, the junction temperature of the proposed model is extracted and verified. Compared with the thermal network using constant parameters, the accuracy is significantly improved. Also, the model saves computation time and resource in contrast with the TCAD model.