A Fast and Effective Open-Circuit-Fault Diagnosis Approach for Three-Level Power Converters

Three-level neutral-point-clamped (3L-NPC) converters find extensive application in renewable energy systems, energy storage systems, transportation electrification, etc. Rapid and accurate fault diagnosis is important to enhance the reliability of these converters. In this work, we propose a fast and effective open-circuit fault diagnosis method for all semiconductor devices including IGBTs and diodes in 3L-NPC converters. The switching state residuals are calculated from the mismatches between the actual and estimated current path, requiring solely the existing current measurement of the system. By integrating anticipated switching states and a specific switching state injection method, the proposal can locate the faulty switch within several sampling periods. Simulation results demonstrate the effectiveness of the proposed diagnosis technique.