Power Switch Short-Circuit Fault Diagnosis for SRM Drives With Cross-Branch Current Sensors Connection

In this article, a short fault diagnosis scheme for the power converter of switched reluctance motor drives system is proposed. To extract the current waveform and the short-circuit fault characteristic, a cross-branch current sensor connection structure and the current reconstruction scheme are proposed. Based on the new current measurement method, the short-circuit faults of power switch are classified systematically. To address the issue of a sudden rise in current waveforms in the conduction region, a dual current limiting based switch test method is developed. For the issue of abnormal demagnetization in the nonconduction region, the fault type and faulty switch are determined by monitoring the mutation of reconstructed current and comparing signs of the measured values. Furthermore, the division of diagnosis region is analyzed to locate the faulty switch. Then, an optimization method is proposed to solve the problem of inability to diagnose short-circuit faults due to small changes in reconstructed current values, and to eliminate the influence of noise spikes. The proposed method does not require additional hardware and complex calculations, thus exhibiting good robustness and reliability. Experiments under different operating modes verify the feasibility and effectiveness of the proposed fault diagnosis method.