A Simplified Frequency-Domain Thermal Coupling Model Combining Heat Flow Paths

For the reliability of IGBT power module, it is crucial to analyze its thermal behavior, of which case temperature description is an important part. To precisely predict case temperature, the frequency-domain thermal coupling model with heat flow paths is proposed. However, for every group of coupling chips there is a corresponding case-toambient thermal impedance in heat flow path, which makes modelling complicated. In this paper, thermal coupling model with simplified heat flow paths is proposed. By extracting modification factors from each case-to-ambient thermal impedance and combing heat flow paths, the case temperature is determined by the summation of heat flow over only one single case-to-ambient thermal impedance, which makes parameters extraction much easier. Furthermore, by analyzing the relationship between modification factors and coupling distance, modification factors can be easily obtained from fitted relationship function. The model is verified by finite-element method simulation.