Onboard condition monitoring of solder fatigue in IGBT power modules

This paper proposes a novel on-board condition monitoring of the aging of solder layers in IGBTs for electric vehicle applications. The diagnostic technique makes use of the chip itself as a temperature sensor while current sensors are already in place for control purposes. An auxiliary power supply unit which can be created from the 12V battery and an in situ data-logger circuit is developed for condition monitoring. The novel aspect of the proposed technique relates to monitoring IGBTs in situ when the electric vehicle is operating during stop-and-go traffic conditions or at routine services. The accelerated aging tests are performed on the test vehicles and the condition monitoring system is validated using simulation and thermo-electrical experimentation. The thermal performance of the thermal resistance/impedance and junction temperature of the IGBTs demonstrates the effectiveness of the proposed technique for IGBT health monitoring.