Eccentricity Fault Diagnostic in Hexagon- and Double-Delta-Connected Symmetrical Six-Phase Induction Motors

This paper presents a diagnostic approach for detecting eccentricity faults in hexagon- and double-delta-connected symmetrical six-phase induction motors fed by an inverter. Due to the existence of circulating currents inherent in these connection types, fault-related harmonic components may be either enhanced or suppressed from the line currents, making fault diagnosis more challenging. To address this issue, the proposed fault diagnostic technique relies on the evaluation of the positive sequence of both the lower and upper sideband harmonics of the fundamental component. Based on this analysis, a fault indicator is established by assessing the contribution of the positive sequence of these harmonic components. The effectiveness of the proposed diagnostic technique under different load torques and fault severities is validated through experimental results.