Multi‐Objective Optimization Design of a Stator Coreless Multidisc Axial Flux Permanent Magnet Motor

The stator coreless axial flux permanent magnet (AFPM) motor with a compact structure, low torque ripple, and high efficiency is particularly suitable as a motor for electric propulsion systems. However, it still requires great effort to design an AFPM motor with higher torque density and lower torque ripple. In this paper, a stator coreless multidisc AFPM (SCM‐AFPM) motor with a three‐rotor and two‐stator topology is proposed. To reduce rotor mass and increase torque density, the proposed SCM‐AFPM motor adopts the hybrid permanent magnets (PMs) array with Halbach PMs in the two‐terminal rotor and the conventional PMs array in the middle rotor. In addition, a multi‐objective optimization model combining response surface method (RSM) and genetic algorithm (GA) is proposed and applied to the proposed SCM‐AFPM motor. With the help of the three-dimensional finite‐element analysis (3‐D FEA), it is found that the torque ripple of the optimized SCM‐AFPM motor is 4.73%, while it is 6.21% for the initial motor. Its torque ripple is reduced by 23.8%. Therefore, the proposed multi‐objective optimization design method can quickly and reliably obtain the optimal design of the SCM‐AFPM motor.