Open-Circuit Fault Diagnosis Method for Inverters Based on Critical Characteristics of Half-Wave Current

Diagnosing power switch open-circuit faults quickly and accurately is very important for reliable operation of voltage source inverters (VSI). In this paper, an open-circuit fault diagnosis method of power switch for inverter is proposed, which is suitable for various speed operating conditions. First, detailed models of three-phase currents under normal and faulty conditions are established. Then, the dependence of fault characteristics on control parameters and acceleration is eliminated by designing the critical region. On this basis, the variation trends of characteristic quantity after different faults are quantitatively analyzed, which provides a theoretical basis for the design of diagnostic threshold. Finally, the effectiveness of the proposed method is verified by a lab-constructed hardware test benches. Experimental results show that the proposed method can identify various open-circuit faults, and has good generalization ability and robustness under constant speed, variable speed and different control parameters.