Condition Monitoring in a Power Module Using On-State Resistance and Case Temperature

Abstract

Power electronics are widely used in energy conversion systems due to their high efficiency. Finding and replacing the defective power electronic modules timely by monitoring the ageing state of devices can greatly improve the security of power converters and reduce the loss caused by the device failure. Packaging-related fatigue has been identified as one of the main causes of the failures of power electronic modules. This paper proposes a method to monitor the fatigue inside a module by identifying the increase of internal on-state resistance under a certain operation conditions due to the device packaging-related fatigue. Multiple physical field model results show that the junction temperature increases with the thermal resistance, which causes an increase in the on-state resistance. Therefore, the healthy state of power modules can be diagnosed by comparing the difference of the on-state resistance before and after ageing in the same case temperature, which can be measured directly. Experiments and simulations are conducted to demonstrate the concept and verify the method.