Fast Detection of Power Transistor Faults in SRM Drives Based on Transient Pulse Injection

Switched reluctance motors (SRMs) have been widely used in reliability-critical applications due to their robust rotor structure and fault-tolerance characteristics. However, power transistors in the SRM drives still suffer from various faults, such as open-circuit and short-circuit faults, which may cause unexpected shutdowns. Therefore, detection and localization of the power transistor faults in the earliest stage is of extreme importance to ensure uninterrupted operations. This article proposes a fast fault diagnostic technique for power transistor faults in the SRM drive system. When a fault-caused abnormal current pattern is observed in the fundamental current, two complementary high-frequency (HF) pulses are injected into both power switches of the affected phase for a transient period. Through analyzing the relationship between the induced phase currents due to the injected HF pulses and the failure cases, two fault variables are introduced for faulty switch localization. Diagnosis of open-circuit and short-circuit faults in a single switch and dual switches is achieved within one period of the injected HF pulses. The fast diagnostic speed and feasibility of the proposed method for real-time implementation is verified through simulation studies and experiments based on a three-phase 12/8-pole SRM drive system.