Influence of Rotor Magnet Step Shifting on Torque Ripple of Multiphase Axial Flux Permanent Magnet Machines

The aim of this study is to predict the torque quality performance of multiphase axial flux permanent magnet (AFPM) machine when magnet shifting and stepping are applied. Three, five and seven phase machines are investigated and design options such as two-step, three-step are compared analytically. It was found that torque ripple is reduced in all multiphase machines with three-step and two-step shifting. As far as the average torque is concerned, step shifting of the magnet has more influence on high-phase number machine when compared with low-phase number machine.