Shifting Technique for Cogging Torque Suppression in Yokeless and Segmented Armature Machines

This paper proposed the shifting technique for cogging torque suppression in yokeless and segmented armature (YASA) machines. This shifting technique includes the rotor, stator, and hybrid shifting. The bilateral cogging torques produced from the lower and upper air gaps can be compensated by regulating the rotor and stator shifting values. Subsequently, an analytical model is formulated based on the superstition principle, which yields the optimal shifting value for cogging torque minimization. The impact of the rotor, stator, and hybrid shifting techniques on cogging torque suppression is analyzed, respectively. In addition, comprehensive comparisons of electromagnetic performance are conducted, in terms of the air-gap flux density, back-EMF, cogging torque, and electromagnetic torque. The comparative results demonstrate a reduction in cogging torque by 15.8%, 17.1%, and 11.1% with the rotor, stator, and hybrid shifting, respectively, without compromising output performance.