A Cogging Torque Reduction Method for Yokeless and Segmented Armature Axial Flux Motors Based on Stator Module Offset

The yokeless and segmented armature (YASA) axial flux motor offers advantages such as a high radial-to-length ratio, compact size, high power density, and high efficiency. It holds significant application potential in fields including hub drives, industrial robots, and new energy power generation. To meet the smooth output torque requirements of YASA motors, a cogging torque suppression method based on stator module offset is proposed. Compared to traditional methods, this approach only alters the installation angle of the stator module without increasing its manufacturing complexity. This paper first derives the stator module offset angle from the cogging torque expression and analyzes its impact on motor back EMF. Using 3D finite element analysis software, the method’s effects on cogging torque, back EMF harmonics, and output torque are investigated, validating its effectiveness. Through stator module offset, torque ripple was reduced by 39.9% with negligible impact on output torque, thereby enhancing the motor’s stable operating performance.