The Analysis And Design On The Fault Diagnosis For Power Converter Of Switched Reluctance Motor

Switched reluctance motor has advantages of simple structure, reliable operation, high efficiency and low cost. Switched reluctance motor drive system is widely used in electric vehicle drive, servo application, aviation industry and other fields. The power converter is a key part of switched reluctance motor drive system, and also the weakest part of the whole system. The power switches often appear short and open faults. Therefore, the diagnosis for power converter of switched reluctance motor has important research value.In this thesis, a three-phase symmetric half-bridge power converter based on a 12/8 switched reluctance motor is used as research object. The influence of the power switches on the phase current is analysized and a bus current and freewheeling current method for fault diagnose is proposed. Firstly, the power switches fault types are analysized, the impact of power switches faults on the excitation current and freewheeling current loop is summed up and the traditional power switches fault model is given. Secondly, the influence of the power switches on the phase current is analysized combining with the phase current linear model, the traditional position of the current sensor is changed, the relationship between bus current or freewheeling current and power switches fault is illustrated. Combined with the open stage of the phase winding, a bus current and freewheeling current method for fault diagnose is proposed. Finally, the fault diagnosis system is implemented based on STM32F103RBT6 and the short and open faults of the power switches are tested.The test results show that fault diagnosis method can accurately diagnose the short and open faults of the power switches, and locate the short fault of the power switches. And the fault diagnosis time is 0.38 phase current cycle. The fault diagnosis system meets the design specifications.