Condition Monitoring the Inhomogeneous Thermal Fatigue of Multichip IGBT Module Based on the Thermal Attenuation Coefficient

The multichip insulated gate bipolar transistor (IGBT) module has been widely used in the converter with high-power capacity. However, multichip IGBT module usually suffers from inhomogeneous thermal fatigue, which undermines the reliability of the whole assemble. This article proposed to use the multipoint temperature of radiator to monitor the health status of parallel chips in the IGBT module simultaneously. We show that the thermal attenuation coefficient of radiator temperature increases during the aging of device. Furthermore, this method enables quantifying the uneven degree of solder layer degradation, which is beneficial for the analysis of current distribution and thermal imbalance. Simulations in COMSOL and experimental tests on a pulsewidth modulation bridge were performed to verify the proposed approach. The influence of operating current, operating mode, cooling condition, sensor position and chip layout were also analyzed.