Electrothermal Cosimulation for Predicting the Power Loss and Temperature of SiC MOSFET Dies Assembled in a Power Module

The electrothermal cosimulation proposed in this paper accurately reproduces the power loss and the temperature of the silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (mosfet) dies assembled in a power module comprising a buck converter. The current-voltage characteristic of the body diode embedded in a SiC mosfet is not like that of an ideal diode because this characteristic depends on the negative gate-source voltage of the transistor. Our device model was, therefore, created to reflect this unique feature and the temperature dependence of the drain current for predicting the power loss of the mosfet. The simulation uses a look-up table to reduce the computation time. This yields accurate results for the power loss in a buck converter operating at switching frequencies (fsw) ranging from 50 to 350 kHz. The fsw-dependent steady-state temperature of the SiC mosfet was reproduced well; it ranged from 60 °C to 140 °C. The maximum deviation between the measured and the simulated results was less than 3.0 W and 8 °C, respectively, for the power loss and the temperature of the dies.