Condition Monitoring of Thermal Fatigue of IGBT Module Using Turning Point of Preheating Stage of Case Temperature

This letter utilizes the turning point of preheating stage of case temperature
T_c
as an efficient indicator for condition monitoring of insulated gate bipolar transistor modules, which could be extracted from dynamic response of
T_c
. Theoretical analysis shows that the turning point will increase with aging process, and its effectiveness is experimentally verified. This method only requires temperature sensor to measure
T_c
without strict measurement requirements. Thus, it brings negligible hardware burden, which is low cost and has more flexibility in online application. Besides, the installation of case temperature sensor does not cause intrusive change to the original system, and the measurement does not affect the normal operation of converter. These features make it more practical for noninvasive and real-time monitoring.