Torque Modeling and Verification of Permanent Magnet Toroidal Motor with Air Gap Deformation

Permanent magnet toroidal motor (PMTM) is a novel spatial motor which integrates permanent magnet motor and worm-planet transmission. The planet eccentricity (PE) and planet carrier rotor eccentricity (PCRE) are two main causes of air gap deformation in PMTM, which results in abnormal rotation of planet and electromagnetic torque fluctuation. In this paper, the air gap deformation in PMTM is classified and analyzed with its mechanism. Based on spatial force analysis for planet, the electromagnetic torque model of PMTM with PE and PCRE are established. The rotation torque with PE is studied from different eccentric distances and angles, which is verified by finite element model (FEM). Simultaneously, the cogging torque of planet rotation with PE is discussed. In addition, the torque experiments are conducted for testing output torque and cogging torque of planet carrier rotor rotation. The variation tendency reflected from proposed torque model is verified by prototype experiment. (c) 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.