A Stator Yokeless Radial Flux Dual Rotor Permanent Magnet Synchronous Motor

A stator yokeless radial flux dual-rotor permanent magnet synchronous motor (SYRFDR-PMSM) with NS type magnetic circuit is proposed and studied. Based on the equivalent magnetic circuit and Ohm’s law of magnetic circuit, the coupling characteristic of the inner and outer flux of SYRFDR-PMSM is analyzed, and the design method for SYRFDR-PMSM is proposed. Besides, the electromagnetic performance of SYRFDRPMSM is analyzed based on the finite element model (FEM). Moreover, the influence of the pole arc coefficient of inner and outer permanent magnets on torque is investigated. It is found that a reasonable pole arc coefficient design can increase the average torque and weaken the torque ripple. Finally, the principle prototype of SYRFDR-PMSM is tested and the correctness of design theory and FEM results of SYRFDR-PMSM are verified through no-load back electromotive force (EMF) and torque experiment.