Enhancing Lifetime of Power Electronic Modules via Thermal Buffers

Abstract

This paper investigates how thermal buffers in power electronic modules can reduce thermal cycles and thus mitigate fatigue and improve the lifetime of power modules. Safe and reliable power module operation over an extended lifetime is crucial for many power electronic applications, e.g. automated driving, aerospace and energy supply. To address this objective, this works adds passive thermal buffer elements made of copper to the power module to extend its lifetime. For the analysis of different thermal buffer geometries, detailed 3-D thermal models are derived. The junction temperature responses of the power module geometries are simulated with the 3-D thermal models rover typical mission profiles from electric vehicles. Consequently, the occurring thermal cycles are extracted by a rainflow-counting algorithm and used to compute the lifetime of the power modules on the basis of empirical models. The results show a significant influence of thermal buffers on the lifetime of the modules, as they mitigate thermal cycles that drive thermally-induced degradation. It could be demonstrated that this technology can increase the lifetime of the power modules up to a factor of six in electric vehicles. Thus, thermal buffers provide a simple, effective and cost-efficient way to increase the lifetime and thus reliability of power electronics modules.