Frequency-domain transient temperature estimation and aging analysis for weak points of IGBT modules

The information of the remaining useful lifetime (RUL) of insulated-gate bipolar transistors (IGBTs) is useful for effective maintenance of a power converter before the failure of a device. Thermo-mechanical stresses are the major cause to the aging of the weak points of the packaging that determines the lifetime of an IGBT module. Traditionally, the RUL of an IGBT module is simply predicted based on the cyclic excursion of the junction temperature and case temperature, which are usually estimated by using a resistor-capacitor circuit thermal model. This method might not correctly predict the lifetime of an IGBT module when the device is operated under complex conditions. This paper proposes a frequency domain analysis method to analyze the aging modes of a device and estimate the temperatures at the weak points under different working conditions. Compared to the traditional method, the proposed method is superior in terms of simplicity and accuracy. The temperatures at the weak points estimated by the proposed method can provide a better RUL prediction.