Design and Investigation of Flux-Reversal Permanent-Magnet Motor with Less Rare-Earth Magnet for Low-Cost Application

Stator-permanent-magnet (stator-PM) motor has garnered significant attention due to its high robustness, making it more suitable for operation in textile industry, small conveyor belt, tracked robot etc. However, the use of rare-earth permanent magnets (PM) in such motors, while possessing desirable properties, comes with a high cost, limiting its widespread industrial application. In this paper, a less rare-earth flux reversal permanent magnet (FRPM) motor with integer slot distributed winding is proposed, which can significantly improve the utilization ratio of PM material. An orthogonal modulation analysis method is proposed to clarify the operation principle of the proposed FRPM motor. Utilizing this method, the harmonic distributions of radial and tangential magnetic fields generated by PM material and armature current can both be derived. Additionally, employing maxwell tensor method, the torque generated by each harmonic is calculated, which verifies that the static fundamental harmonic can also generate the main output torque. Furthermore, the multi-objective genetic algorithm method is applied to optimize the parameters. Three existing PM motors, namely one flux-switching PM motor and two conventional FRPM motors, are used to compare with the proposed motor. The results indicate that the proposed motor can reach higher torque with less PM consumption. Finally, a prototype is processed and tested to validate the correctness of the design and analysis.