Real-Time Power Switch Short-Circuit Fault Diagnosis for the Power Converter in SRM Drives

In this article, a real-time power switch short-circuit fault diagnosis strategy is proposed for the power converter system in switched reluctance motor (SRM) drives. The key steps of the strategy are as follows: 1) based on the difference in phase current characteristics after the power switch short fault occurs in the conduction and nonconduction regions, the faults are divided into eight categories; 2) a new current sensor connection method is utilized to facilitate the detection of phase currents and characterize the fault currents; 3) a comprehensive power switch short-circuit faults diagnosis strategy is proposed based on the five diagnostic elements, such as sensor connection, current waveform characteristics, switch test with current threshold, current translation compensation, and two-step testing of motor restart; and 4) two fault diagnosis optimization schemes are proposed to solve the situation of diagnosis lag and false diagnosis. In the experiments, the fault diagnosis strategies under the eight possible power switch short faults are tested in detail. The experimental results indicate that this method can rapidly diagnose one or two power switch short-circuit faults in a single-phase branch. Furthermore, the fault diagnosis optimization schemes are also tested, which shows that the system can ensure rapid fault response and good fault-tolerant operation.