An Extended Multilayer Thermal Model for Multichip IGBT Modules Considering Thermal Aging

An accurate and real-time knowledge of temperatures in insulated-gate bipolar transistor modules is crucial for reliability analysis and thermal management of power electronic converters. For this purpose, this paper establishes an integrated thermal equivalent circuit model comprising self-heating thermal impedances and cross-heating thermal impedances to provide a temperature profile of the junction and solder joints during various operations and in the case of thermal aging. The thermal resistance and capacitance parameters of the thermal impedances are characterized in terms of different electro-thermal operating conditions and solder joints aging conditions with the help of three-dimensional finite element simulations. Also, the effect of the heatsink, which brings an uneven heat transfer coefficient distribution at the module baseplate, is investigated and modeled into the thermal impedances. The introduced thermal model can work even if the conditions change simultaneously. The accuracy of the model is verified by experiments and finite element simulations, all of which agree with negligible error unlike thermal models given in the datasheet and fixed-parameter thermal models.