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

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