Design and Investigation of a High-Torque-Performance Spoke-Type Flux-Modulated Permanent Magnet Motor

In this paper, a spoke-type flux-modulated permanent magnet in-wheel (SFM-PMIW) motor is taken as the research object. A design and optimization method for field-modulated motors guided by multi-air-gap harmonics is proposed. In the research, the requirements for high torque and low torque ripple are integrated into the motor design, leading to the implementation of rotor slotting. Subsequently, the influence of rotor slotting on rotor permanent magnet magnetomotive force and rotor permeance is analyzed. Then, by designing the unique modulation behavior after rotor slotting, the air-gap harmonics are altered to improve motor performance, including cogging torque. Guided by this concept, the air-gap harmonics related to cogging torque are analyzed, and these harmonics are used as a design link for motor parameter optimization, resulting in the final motor structure. Finally, a comparative analysis of the no-load and load performance before and after harmonic design is conducted, demonstrating the effectiveness of the proposed design and optimization approach.