Rotor Slot Harmonics in the Alpha-Beta Current Modulus Signature of Symmetrical Six-Phase Induction Motors Fed by Unbalanced Voltages and With Stator and Eccentricity Faults

Diagnosing inter-turn short-circuit faults (ITSCFs) in induction motors under unbalanced supply voltage conditions has been a challenging task since both conditions impact the machine in the same manner. Additionally, discriminating ITSCFs from eccentricity faults is also complex, as both affect the same harmonic components presented in the motor currents. In response to these issues, two fault indicators, based on the assessment of three harmonic components (related to the rotor slot harmonics (RSHs)) of the alpha-beta plane current modulus signature, are proposed to perform the discrimination of stator faults and eccentricity faults in symmetrical six-phase induction motors (S6PIMs) fed by unbalanced voltages. Experimental results, including different load torques, motor supply methods, fault severities, unbalanced supply voltage (USV) levels, and static eccentricity levels, demonstrate that the proposed approach offers a reliable fault diagnostic without adding complexity to the diagnostic methodology.