Simplified Multi-time Scale Thermal Model Considering Thermal Coupling in IGBT Modules

In the reliability evaluation of power electronic systems, one of the challenges is to model the thermal profiles across multiple time scales, i.e., from switching cycles at nano- or micro-seconds to annual or even longer-time mission profiles. Without consideration of the dissimilarity of thermal behaviors under different time scales, a single thermal model usually leads to either considerable modeling errors or heavy computational burden. Based on the frequency response of thermal impedances, this paper proposes a novel and simplified thermal model to analyze mission profiles with multiple time scales. It enables a computational-efficient thermal stress analysis for power semiconductors, including the thermal coupling in device packages. The theoretical results are verified by experimental testing.