A Test Bench for Thermal Characterization of IGBT Power Modules Over Mission Profiles

The thermal characterization of power electronics modules over realistic mission profiles is crucial for a reliability oriented stress evaluation of electric drives. Therefore, this paper presents safe laboratory environment methods to create and monitor normal as well as extreme thermal loadings of a power module that can occur during real operation. An electric load emulator test bench is introduced that applies realistic loads to an IGBT power module occurring for example during a mission profile of an electric vehicle. The resulting surface temperature distribution of a decapsulated power module is monitored using an infra-red (IR) camera and IR sensors. To improve this state-of-the-art thermal characterization, a thermal observer is presented. It enhances the limited bandwidth of the IR sensors and extracts additional information on the 3-D temperature distribution within the power module during operation. Furthermore, the observer is ideally suited to calibrate electro-thermal real time models, that are employed in a commercial system for open loop temperature monitoring. The methods that are presented in this work are experimentally evaluated based on a state-of-the-art inverter module for automotive applications.