Incipient Stator Winding Short-Circuit Diagnosis in Seven-Phase Electrical Machines Using Phase Currents

This work proposes a simple method for detecting incipient short circuits in a seven-phase electrical machine based on an analytical model of the phase currents operated in speed-control conditions. The method assumes that an electrical fault will affect the amplitude, phase shift, and mean value of the phase currents (fundamental components and harmonics). The proposal is validated with experimental data collected from a seven-phase Permanent Magnet Synchronous Machine (PMSM) in speed-control under different fault scenarios: Inter-Turn or Inter-Phase Short-Circuit (ITSC, IPSC) faults at low speeds (50, 100rpm) for a fault severity varying from 3 to 19%. The results show that the analytical model of the phase currents using the change in parameters (amplitude, phase shift) is relevant and accurate, with an average Normalized Root Mean Square Error (NRMSE) lower than 0.08 and 0.14 for ITSC and IPSC detection, respectively.