Abstract: The power converter linking controller to switched reluctance generator are becoming the important part in energy transmission. However, the open-circuit failure of the switch transistor will lead to phase-deficient operation of the system and low power output of the generator;Short circuit fault also results in the high current during the operation and even leads to the burning of the devices.Therefore,a fault diagnosis method based on the freewheeling current and phase current is proposed in this paper.Through logical judgment of the characteristic valuesextracted by the freewheeling current and phase current,the fault detection of power converter switching devices can be achieved,the fault components even can be located,and the logical judgment part of the threshold formula will be given as well.The feasibility and effectiveness of the proposed fault diagnosis algorithm are verified by the simulation experiments on Simulink platform and physical experiments.