Study on the Cauer Thermal Network Model of Press Pack IGBTs

Abstract

Press Pack IGBTs (PP IGBTs) has been gradually applied in the high voltage and high current areas, for its high power density, double side cooling and high reliability. The cauer thermal network model of PP IGBTs is proposed based on the boundary effect according to heat spreading angle in this paper, and the difference between the IGBT and FRD chips is considered in this model. The thermal contact resistance among multi-layers within PP IGBTs, which is calculated and corrected by the experiment, is also included in this model. The finite element method (FEM) model is used to verify the accuracy of the cauer model, because the accurate measurement of the junction to case thermal resistance of PP IGBTs is extremely difficult. The thermal characteristic of PP IGBTs under different clamping force can be acquired through the cauer thermal model. It has significant influence on the thermal resistance optimization, as the thermal resistance percentage of the components in PP IGBTs can be obtained from the cauer thermal model.