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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. [ABSTRACT FROM AUTHOR]

A novel design method for the primary structure of a double-sided long-primary fractional-slot concentrated winding permanent magnet linear synchronous motor (DSLP-FSCW-PMLSM) is proposed in this article. Different from the traditional symmetric primary structure, the primary structure obtained by the proposed design method has two asymmetric primary cores and two asymmetric primary windings. This unique structure can reduce the variation of the flux density caused by the primary core slotting, and can effectively reduce the slot harmonic contents of the armature reaction magnetic field; thus, it can significantly reduce secondary eddy current losses. First, the basic structure is introduced. The air-gap magnetic field of permanent magnet and armature reaction are analyzed in detail. Second, the performance of the proposed motor is analyzed by means of three dimensional finite element method and compared with the traditional motor. The focus is on secondary materials, secondary eddy current losses, thrust, pole arc coefficient, magnet skew angle, and efficiency. Last, experiments are conducted on two prototypes of DSLP-FSCW-PMLSM. The validity of the proposed topology is verified by the test results of static thrust, back electromotive force, and armature reaction air-gap magnetic field. [ABSTRACT FROM AUTHOR]