High Torque Density and Lightweight Design of Permanent Magnet In-Wheel Motor Based on Magnetic Field Modulation Effect

In this article, by incorporating the magnetic field modulation effect into the in-wheel motor design, a spoke-type permanent magnet in-wheel (SPM-IW) motor is proposed for the potential low-speed direct-drive applications. The key to utilizing the flux-modulated technology is to introduce the permeance modulation function into both the stator and rotor sides. Thereupon, the waveform of the permeance modulation function is analyzed, where the contained harmonics are further investigated. It aims at differentiating which one possesses a positive or negative influence on motor performances. By enhancing the positive harmonics or suppressing the negative harmonics, the output torque of the SPM-IW motor is improved effectively. Meanwhile, with the optimization design of the permeance modulation function in the stator and rotor, the weight of the motor is also reduced to some extent. And then, the electromagnetic performances of the SPM-IW motor are investigated in detail. Finally, a prototype motor is built for experimental validation. The study results show that the proposed SPM-IW motor realizes the performance design demands for high torque density and lightweight.