Comparison of junction temperature variations of IGBT modules under DC and PWM power cycling test conditions

This paper presents an experimental investigation and a finite element (FE) analysis study on the thermal and mechanical behaviors of insulated-gate bipolar transistor (IGBT) power modules under various operating conditions. The power cycling test conditions are provided by two test benches, a direct current (DC) test bench and a pulse width modulation (PWM) test bench. Infrared (IR) camera acquisition methods are suggested as an approach for transient temperature measurements to estimate the effects of operating conditions and switching frequency on the thermal performance of an IGBT module. An electrical-thermal-mechanical FE model of an IGBT module is employed to determine the stress in the interconnections of an IGBT module induced by junction temperature fluctuations. Results indicate that the operating conditions significantly impact the maximum junction temperature, the junction temperature increase rate, and the junction temperature distribution of an IGBT chip and the thermally induced stress in the interconnections. The switching frequency strongly impacts the junction temperature of an IGBT chip, and the maximum junction temperature increases when the switching frequency increases due to the increasing switching loss. Furthermore, the junction temperature variation induced by the instantaneous switching loss is estimated by the proposed IR camera measurement method.