Detecting Eccentricity Fault in Dual Three-Phase Permanent Magnet Machines by Means of Zero-Sequence Voltage Component

Eccentricity is a critical fault in permanent magnet (PM) machines. In this article, an eccentricity diagnosis method is proposed for dual three-phase PM (DTPPM) machines based on detecting the difference of zero-sequence voltage component (ZSVC) between two sets of three-phase windings. The research is carried out by finite-element method, and 10-pole/12-slot surface-mounted DTPPM machines with different winding configurations are modeled. Eccentricity significantly affects the ZSVC difference in DTPPM machines where a single set of three-phase windings is rotationally asymmetric. The fundamental component and fractional harmonics dominate in the ZSVC difference under static eccentricity (SE) and dynamic eccentricity (DE), respectively. Both the fault characteristic components appear under mixed eccentricity (ME). Moreover, the ZSVC in a single set of three-phase windings is analyzed for comparison. It shows that detecting ZSVC difference has better sensitivity to eccentricity. Furthermore, the effectiveness of the proposed method is verified under different load conditions and eccentricity conditions.