Thermal Impedance Measurement Utilizing Optical Measurement and Thermal Impedance Model for Multichip SiC MOSFET Module with Anti-Parallel Diodes

This paper presents a method of extracting thermal impedance for multi-chip SiC MOSFET power modules with anti-parallel diodes. This method co-utilizes thermal optical measurement and thermal impedance model. Thermo-sensitive electrical parameter(TSEP) is commonly employed but becomes relatively inaccurate, especially in multichip applications. Our proposed method directly measures the junction temperature(Tj) using a fiber optic temperature sensor. Though the fiber optic has a relatively slow response than TSEP, the undetected regions are compensated by an estimation approach using a thermal model and analyzed. The proposed method can accurately measure thermal resistance. Additional circuits and calibrations are not required.