Investigation of Eccentricity Characteristics in a Dual-Stator Single-Rotor Axial Flux Permanent Magnet Synchronous Motor

Dual-stator single-rotor (DSSR) axial flux permanent magnet synchronous motors (AFPMSMs) offer high torque density but face reliability challenges due to unbalanced magnetic forces (UMF) and bending moments caused by eccentricity faults. This study investigates the electromagnetic performance of a DSSR AFPMSM under static, dynamic, axial, and radial eccentricities to reveal specific fault signatures and physical mechanisms. The methodology relies on three-dimensional transient finite element analysis (3-D FEA) and is validated by experimental tests on a 500 W prototype. Results indicate that while static and dynamic eccentricities have negligible effects on average torque, they induce significant bending moments where static eccentricity generates a constant moment and dynamic eccentricity produces an alternating one, both proportional to the eccentricity severity. Crucially, axial eccentricity disrupts magnetic symmetry, causing a 17.6% no-load back-EMF imbalance between stators and increasing net axial UMF to 53.2 N at a 40% eccentricity factor. Conversely, radial eccentricity shows minimal impact, confirming the topology’s robustness against radial misalignments. These findings provide essential baseline data for the vibration analysis and condition monitoring of DSSR AFPMSMs.