Maximum Junction Temperature Simulation and Validation for the Hot Spot in Multi-Chip SiC Power Module

Abstract:
Thermal impedance (Z (th)) of the power module derived by the relation of virtual junction temperature (T (vj)) and corresponding power loss reflects the average junction t emperature (T(j,avg)) of the power semicon- ductor switch if multiple devices compose a single function al switch. However, the actual temperature across the individual device devices can vary from the value represented in T(vj) of the switch due to uneven distribution of the temperature over the chips chips. This paper proposes localized Z(th) referred from the hot spot temperature of the switch and the use of proposed Z (th) for the inverter simulation to estimate the maximum allowable output power within the allowable range of the junction temperature (Tj). By applying localized Z (th) , simulated T(j) shows ~10 °C higher temperature compared with the result using the conventional Z (th) method in 250 kW automotive traction inverter simulation and empirical measurement measurement, which can provide more practical feasibility analysis in the early stage of the system development.