Research of Asymmetrical Bidirectional Magnet Skewing Technique in Modular Multi-Stage Axial Flux Permanent Magnet Synchronous Motor

In this paper, a new modular multi-stage axial flux permanent magnet synchronous motor is proposed for the traction motor applications, which has the features of slotted north-south-pole topology, segmented and yokeless stator, ellipsoidal similar Somaloy teeth, and flexible power circuits. To minimize the cogging torque, a cost-effective asymmetrical bidirectional magnet skewing (ABMS) technique is adopted in the motor. Various ABMS combinations are studied with different skew angles and cross positions. Both the theoretical analysis and finite-element method (FEM) illustrate that ABMS has both the skewing and phase shifting effects. Based on a 2 kW-1000 r/min, 10-pole 12-open-slot prototype, the experiments are developed. The results measured by experiments agree well with the ones predicated by 3-D FEM, which verifies the conclusions and design.