In Situ Diagnosis for IGBT Chip Failure in Multichip IGBT Modules Based on a Newly Defined Characteristic Parameter Low-Sensitive to Operation Conditions

To achieve the desired current capability, insulated gate bipolar transistor (IGBT) modules are normally composed of parallel chips. The bond wires fatigue on a certain chip will gradually cause the performance of the power module to degrade, and eventually lead to an unexpected catastrophic failure of the entire system. Therefore, this article proposes an in situ diagnosis method for bond wires fatigue in multichip IGBT modules based on a newly defined characteristic parameter. By sensitivity analysis, horizontal comparison, and experimental test, the parameter was proven to have the advantages of being safe, low-sensitive to operation conditions, and easy to extract. Correspondingly, the online monitoring circuit was designed on the basis of the voltage clamping technology, and further applied on an inverter prototype with 100 A peak current and 10 kHz switching frequency. The results showed that although with large change of junction temperature and load current, the proposed method can accurately diagnose IGBT chip failure by the sudden increase in the amplitude of the parameter. Moreover, the monitoring circuit can be both plug-and-play in the existing inverters and integrated in the gate drive circuit owing to the compact design, which is expected to avoid catastrophic failures of the inverter in field application.