High-Frequency Carrier-Signal Voltage Selection for Stator Winding Fault Diagnosis in Inverter-Fed AC Machines

The diagnosis of stator winding faults in inverter-fed ac machines using an injected high-frequency carrier-signal voltage is analyzed in this paper. Measurement of the resulting carrier signals (either the negative-sequence carrier-signal current or the zero-sequence components) is used to detect turn faults at an incipient stage. The carrier frequency and magnitude are shown to have significant impact on the performance of the method, with the criteria for their selection being presented. The proposed technique shows low sensitivity to the working condition of the machine, i.e., torque level, flux levels, and fundamental excitation frequency.