Influence of the IGBT Module Thermal Model Form on the Accuracy of Electrothermal Computations

The paper presents the results of investigations illustrating the influence of the form of a compact thermal model of the IGBT module on the accuracy of computing the non-isothermal characteristics of the components of this module. The tests are carried out for a module containing 2 IGBTs, 2 diodes and a thermistor. Three degrees of complexity of the thermal model are considered. The first one takes into account only self-heating in each component of the module. The second - additionally takes into account mutual thermal couplings between the components of the module. The third - additionally takes into account the dependence of thermal parameters on the power dissipated in the components of the module. The form of the considered models as well as the results of computations and measurements of the characteristics of the module components obtained for various cooling conditions of the module and the supply conditions of these components are presented. The obtained results are discussed.