A Novel Open-Circuit Fault Diagnosis Method for Voltage Source Inverter

Aiming at the open-circuit fault detection for the voltage source inverter (VSI), a novel diagnosis method based on three-phase currents detection is proposed. By using conventional fault diagnosis method based on the normalized current average of absolute value, the values of diagnostic variables are tiny in some fault types, which are invalid for the fault diagnosis, and false alarm may generated when the speed reference changes. In order to solve these problems, a near-zero flag is introduced as a new diagnostic variable, which expands the diagnostic variable distinction and avoids false alarms caused by speed disturbance. As a result, the failure criterion is simplified correspondingly. The simulation and experimental results show that the each double IGBT open-circuit fault can be detected and determined correctly by using the novel fault diagnosis method.