Effects of different switching algorithms on the thermal behavior of IGBT modules under pulse-load conditions

In this paper the impact of pulse-loads on a six-pack IGBT power module is presented using Finite Element (FE) computations. The FE model solves the heat transfer equations which determine the thermal behavior of the six-pack IGBT module. The approach is such that the IGBT switching loss is calculated using a time domain circuit simulation model, then the results are used as input data for the FE computations. It is assumed that the IGBT module is operating as a three-phase voltage source inverter under pulse-load condition. With this model, the temperature of each chip can be directly derived from the losses of the silicon chips. The FE results can be used in order to verify the accuracy of the NTC sensor (Negative Temperature coefficient) included in the chip. The FE computational results have been verified for some identified conditions which have been tested by the manufacturer.