A Stator Turn Fault Indicator Based on Saturation Saliency for Online Inter-Turn Short Circuit Faults Detection in IPMSM Drives

This paper deals with the design and real-time implementation of a stator turn fault (STF) indicator for online detection of inter-turn short circuit (ITSC) faults in interior permanent magnet synchronous motor (IPMSM) drives. First an evaluation function is defined based on the average value of the spatial saturation harmonic of the machine over an observation window during the online operation of the drive. Then, based on the value of the load current, a correction factor is set for each condition using a look-up table (LUT) to eliminate the dependency of the saturation saliency on the load current. Finally the STF indicator is obtained by dividing the evaluation function by the correction factor for each load condition. A developped hardware FFT processor is used to extract the saturation saliency from the transient inductance of the machine, estimated online by applying an excitation with voltage pulses using the switching of the inverter and then measuring the resulting current slope. The model is embedded into a field programmable gate array (FPGA) and experimental testing is used to evaluate the performance of the proposed STF indicator on a dedicated designed IPMSM with modified stator windings.