A Transient 3-D Thermal Modeling Method for IGBT Modules Considering Uneven Power Losses and Cooling Conditions

Junction temperature is a key parameter for the safe operation of power semiconductor devices in power electronic systems. However, it is difficult to forecast the accurate thermal stress of the device in field use. Consequently, engineers tend to use higher rated devices to maintain excessive margin, resulting in a higher cost. In this article, a transient 3-D thermal modeling method for insulated gate bipolar transistor (IGBT) modules is proposed to obtain accurate temperature distribution considering uneven power losses and cooling conditions. The analytical model of uneven switching energy losses among the parallel IGBT chips in modules is built according to the analysis of device simulation results. The effect of uneven cooling conditions on temperature distribution in IGBT modules is considered by thermal-fluid cosimulation. Furthermore, a hybrid simulation strategy is proposed to obtain the transient thermal behavior in three dimensions. Through appropriate interface design, the power loss model is connected with the finite element model to achieve field-circuit cosimulation with multiple time steps, which takes full consideration of the multiphysical coupling effects among power loss, temperature, and flow fields. Finally, the thermal stresses of IGBT modules under different operating conditions are forecast by the proposed method.