Stator Turn Fault Detection by Second Harmonic in Instantaneous Power for a Triple-Redundant Fault-Tolerant PM Drive

Fast and reliable detection of stator faults is of key importance for fail-safe and fault-tolerant machine drives in order to immediately trigger appropriate fault mitigation actions. The paper presents a detailed analytical and experimental analysis of the behavior of a closed-loop controlled permanent magnet machine drive under interturn fault conditions. It is shown that significant second harmonic components in the dq voltages, currents, instantaneous active power (IAP), and instantaneous reactive power (IRP) are generated during turn fault conditions. The analyses further show that the increase of the second harmonic in IAP and IRP during fault conditions is comparatively higher than that of voltage and current, making them ideal candidates as turn fault indicators. A turn fault detection technique based on second harmonic in IAP and IRP is implemented and demonstrated for a triple-redundant, fault-tolerant permanent magnet assisted synchronous reluctance machine drive. The effectiveness of the proposed detection technique over the whole operation region is assessed, demonstrating fast and reliable detection over most of the operating region under both motoring and generating mode.