Transient Thermal Modeling of a Power Module: An N-Layer Fourier Approach

A transient model of a rectangular N-layer structure with an arbitrary number of rectangular heat sources on the top surface is obtained by Fourier series solution. As power modules can be closely approximated by this type of structure, the model may be used to accurately estimate the temperature field occurring in such modules. The Fourier-based method developed in this work is compared with a finite-element model and an excellent matching (under 2% error) in the transient region is found. An experimental validation is performed using a half-bridge silicon carbide power module monitored by a high frame-rate thermal camera. After the model outputs have been compensated to match the limited frequency response of the camera, a good matching is found between model and experiment (under 6% error).