A Method for SiC-Mosfet Junction Temperature Estimation in Traction Inverters

This paper presents an approach to estimating the junction temperature of SiC MOSFETs in three-phase inverters, crucial for electric vehicle applications. This study carries out the conversion process from Foster to Cauer thermal networks, which enables a space-state representation with intermediate temperature states, such as: internal module and module case temperatures. A Luenberger-type state observer is used to estimate the switch junction temperature. The proposed method demonstrates enhanced robustness and accuracy compared to conventional open-loop thermal models. Simulation results, validated through PSIM software, illustrate the effectiveness of the observer in maintaining temperature estimates within safe operational limits even with incorrect initial states. The findings underscore the potential for improved reliability and lifespan prediction of semiconductor devices in harsh operating conditions.