Junction Temperature Estimation for a High Power SiC Traction Inverter

Abstract:
This paper presents a real-time estimation method of the junction temperature in an SiC power module during three- phase traction inverter operation in order to ensure maximal inverter performance for every operating point. In order to accurately estimate the junction temperature in the semiconductor, the power losses in each inverter half-bridge are approximated on the basis of the respective phase current, switching frequency, duty cycle, and the DC link voltage. A runtime optimized thermal impedance model from the SiC junction to the water of the heat sink is applied to the losses calculated by the control unit. With this method, the junction temperature and its ripple are tracked over time.