An Open-Circuit Fault Diagnosis Method for H-Bridge Semi-Controlled Rectifier in DSEG System Based on Bus Current and Forward Freewheeling Diode Current

Fault diagnosis is a key technology to improve the reliability of electrical machine systems. However, no previous research has addressed open-circuit (OC) faults in the power switches of doubly salient electromagnetic generator (DSEG) systems with H-bridge semi-controlled rectifier (HBSCR), and the existing methods cannot be applied to these systems. To solve the problem, this article proposes an OC fault diagnosis method for power switches based on bus current and forward freewheeling diode current. Fault location is achieved by detecting the direction of the bus current and the forward freewheeling diode current before and after the switch-offangle, and analyzing relationships between them. The proposed method does not change the rectifier topology and has low diagnosis cost. It is independent of the fault position and operating conditions. Meanwhile, it can locate OC faults of single switch and dual switches in one sector at the same or different moments. Finally, experiments on a 12/8-pole DSEG platform validate the effectiveness of the proposed method.