A Converter-Level Health Monitoring Method for Traction Inverter Application

This article proposes a converter-level health monitoring method for detecting critical degradation in either dc-link capacitors or power semiconductor modules in traction inverters. The outcome can be used for condition-based maintenance decisions to determine whether the inverter or its power stage as a whole needs to be replaced. The proposed method is based on the dc-link voltage profile during the capacitor discharge operation mode after a traction system is already shut down, which is a standard operation mode for safety reasons. Therefore, the method relies only on existing resources from traction inverters without the need for additional hardware or software. The theoretical foundation of the method and practical considerations for implementation are discussed. Proof-of-concept experiments are performed to validate its effectiveness and feasibility for practical application.