Fault Diagnosis for Power Transistors in a Converter of Switched Reluctance Motors Based on Current Features

Fault diagnosis technique is necessary for high reliability system. For switched reluctance motor, asymmetric half bridge converter is the most commonly used. The transistor is the most fragile component in converters. To the transistor in asymmetric half bridge converter, a fault diagnosis method is proposed in this paper. When faults of transistors occur, the conducting loop will be changed. The current slope can reflect the change of the conducting loop. Through reconfiguring current sensors, the sign of the measurements will reverse with the change of the conducting loop. By the current slope and the sign of the measurements, present conducting loop is determined. The changes and the fault types are one-to-one correspondence. Therefore, the fault type is known. Conditions that may lead to misdiagnosis are illustrated and avoided in online execution. Comparisons of the proposed fault diagnosis method and relevant existing methods are made according to the cost, the response speed, the application scope and so on. The proposed fault diagnosis method is demonstrated under all possible fault types of the transistor by simulations and experiments, which validates effectiveness of it.