Condition Monitoring of IGBT Modules Based on Changes of Thermal Characteristics

Condition monitoring (CM) of insulated-gate bipolar transistor (IGBT) modules is significant for improving power converter reliability and reducing the loss caused by IGBT failure. In this paper, we present an advanced method to evaluate the aging condition of an IGBT based on the changes of thermal characteristics in the module, which can be described by the junction and case temperatures. The variation of the case temperature distribution is used to monitor the solder fatigue. The estimated level of solder fatigue is used to update the parameters in the electrical-thermal model. Then, the junction temperature can be accurately estimated by the updated electrical-thermal model. The difference between junction temperatures estimated from the updated model and temperature-sensitive electrical parameter (TSEP) is utilized to monitor the aging of bond wires. The proposed CM method permits both of health level evaluation and accurate junction temperature estimation of IGBT in real time to prevent catastrophic failure caused by defective modules. The experimental results on a commercialized IGBT product have validated the feasibility of the proposed method.