An Improved Thermal Network Model of Press-Pack IGBT Modules Considering Contact Surface Damage

As the power density of press-pack insulated gate bipolar transistor (PP-IGBT) modules increases, establishing a thermal analysis model to provide thermodynamic information for PP-IGBT modules under service conditions is crucial for reliability design and thermal management. Existing thermal models, such as one-dimensional (1D) lumped RC thermal network models, have limitations in terms of accurately predicting the thermal behavior of PP-IGBT modules; i.e., the effect of thermal contact resistance degradation resulting from contact surface damage on the junction temperature is not considered. This study proposes an improved 1D lumped RC thermal network model for PP-IGBT modules. Following different numbers of power cycles, the transient PP-IGBT module thermal impedances were measured, and the evolution of the thermal contact resistances at each contact surface was obtained. Then, thermal contact resistance degradation was introduced into the RC thermal network model. We compared the calculated junction temperature results with the measured results to verify the proposed model. The model enables a more accurate prediction of the junction temperature of PP-IGBT modules under long-term service conditions.