Reliability Analysis of SiC-MOSFET-based Integrated Motor Drives for High-speed Applications

The lifetime of a high-speed Integrated Motor Drive (IMD) is highly dependent on its power converter, where power devices are the most prone to failures. This paper studies the reliability of SiC-MOSFET-based high-speed IMDs, highlighting its critical role in determining the overall lifetime of the system. The proposed reliability model estimates the End of Life (EoL) of power devices by analyzing the junction temperature, which is influenced by the load conditions based on the applied mission profile. The applied mission profile, which covers all operating conditions and a wide speed range, including maximum torque per ampere and field weakening strategies, is translated into the motor current and voltage. Then, the power losses of power devices and electrical motor are obtained through three-phase currents and voltages and applied to the thermal model of the IMD. In addition to the self-thermal effect of power devices, the mutual thermal effect of the electrical motor must be considered in the IMD’s thermal model. To handle a long mission profile, the average loss model is adopted instead of using a heavy simulation. The proposed reliability model can help in designing heatsink and electrical motor cooling methods, contributing to enhanced thermal management in order to meet the lifetime requirements of specific applications for IMDs.