Fundamental frequency region-based thermal control of power electronics modules in high power motor drive

The reliability of power modules in motor drive is closely related to its thermal cycling. Especially in low speed and high output power condition, the thermal performance can be even worse. In this paper, a fundamental frequency region-based thermal control strategy is presented. Firstly, the model for high power drive thermal cycling calculation is established. With the electro-thermal model, power switch junction temperature and its number of power cycles can be mapped with fundamental frequency. Then, the fundamental frequency region can be divided by the junction temperature fluctuation. Based on the obtained frequency region, a switching frequency control method is proposed to improve the thermal fluctuation and reliability. A comparison results with and without the proposed control method are given to validate the switching frequency hysteresis control strategy and the improvement on system power cycling capability.