Open-Circuit Fault Diagnosis for Active Rectifiers in Doubly Salient Electromagnetic Generator Systems

The performance of the double salient electromagnetic generator (DSEG) system is improved by replacing diode rectifiers with active rectifiers. However, the fault rate of power switches is higher than that of diodes. Thus, diagnosing faults in active rectifiers is necessary. This article proposes a fault diagnosis method for power switch open-circuit faults of active rectifiers in DSEG systems. First, power switch open-circuit faults are divided into two types. Fault type I: the insulate-gate bipolar transistor (IGBT) is an open-circuit, and its freewheeling diode (FWD) can work normally. Fault type II: the IGBT and its FWD are open-circuits. The causes and effects of the two fault types are analyzed. Second, the IGBT open-circuit is common to both types. The rapid diagnosis of the IGBT open-circuit is achieved by utilizing the changes in the dc-link current before and after faults as fault features. The overlap areas of fault features are analyzed to avoid missed diagnosis and misdiagnosis. Moreover, if the IGBT open-circuit fault is diagnosed in a certain sector, then the two fault types are distinguished by the phase current features of the two other sectors. Finally, experiments are conducted on a 12/8-pole DSEG experimental platform to validate the effectiveness of the proposed method.