Active thermal control (ATC) is becoming a popular solution to improve the reliability of power semiconductor devices in electric machine drive systems. Conventional ATCs mostly focus on the extension of a lifetime under common mission profiles in relatively long-term timescale, but the ATCs under abnormal conditions, such as extreme overstress in relatively short-term timescale, still need further investigation. This letter proposes a novel ATC method by optimal phase angle to redistribute the electrothermal stress under the stall condition of the machine drive inverter. During the normal operation, the proposed method will not disturb the original drive control structure. During the stall condition, the maximum electrothermal stress in power semiconductor devices can be relieved significantly. With no extra fluctuating electromagnetic torque, mechanical stability can also be guaranteed. Simulations and experimental results are provided to validate the effectiveness of the proposed method.

Published in: IEEE Transactions on Power Electronics ( Volume: 37, Issue: 9, Sept. 2022)