High Frequency Power Cycling of Three-Phase Inverters for Aircraft Applications

Accurate thermal cycle measurement is essential for estimating the lifetime of power modules, particularly those employing SiC MOSFETs characterized by extremely low thermal capacitance. This work presents a rigorous method for estimating the die temperature variation of SiC components within power modules utilized in three-phase inverters. The approach leverages high-speed thermal imaging to accurately characterize the individual thermal impedance of each die. The resulting thermal impedance model is coupled with high-fidelity loss calculations to predict dynamic SiC die temperatures during inverter operation. Experimental results obtained under conditions representative of a 540 V / 7.5 kW aeronautical inverter demonstrate the model's accuracy in tracking dynamic SiC die temperature variations.