A Novel Diagnostic Method for Multiple Open-Circuit Faults of Voltage-Source Inverters Based on Output Line Voltage Residuals Analysis

A novel diagnostic method for multiple open-circuit faults of voltage-source inverters (VSIs) is proposed based on output line voltage residuals (OLVRs) analysis. Possible OLVRs are characterized for single-phase and double-phase faulty operations. By analyzing the OLVRs, it is found that the OLVRs show different characteristics under different open-circuit (OC) fault conditions, and the positive and negative polarities of the line current residuals are deduced to be consistent with the corresponding OLVRs. Therefore, the fault can be located by line current residuals to avoid the use of extra sensors and meanwhile improve the diagnostic speed. In addition, the presented method has the features of simple structure, robustness against false alarms and being easily inserted to the existing control algorithms. Simulation and experimental results confirm the effectiveness of the proposed algorithm, and additional tests show that the diagnostic speed can be as fast as 5% and as slow as 83% of the current period.