Quantitative Comparison of Distinct Dual-Stator Permanent Magnet Vernier Machines for Direct-Drive Applications

This paper proposes dual-stator permanent magnet Vernier (DS-PMV) machines for direct-drive applications. Also, the quantitative comparison of DS-PMV machines is carried out in terms of no-load performance and output torque characteristic. First, the operation principle is elaborated. Then, the theoretical expressions of air-gap magnetic fields are derived through the magnetic circuit approach. Moreover, the basic machine performances with different pole-slot configurations are quantitatively compared. The corresponding demonstration results are given, which verify that the designs without auxiliary teeth tend to have lower amplitudes of back electromotive force (EMF) harmonics, higher rated average torque, and lower torque ripple.