Analysis, design and experimental verification of a coaxial magnetic gear using stationary permanent-magnet ring

Abstract

This study presents the analysis and experimental verification of a coaxial magnetic gear (CMG) for speed-change transmission. The key design of this CMG is to adopt a stationary permanent-magnet (PM) ring between the inner and outer rotors, aiming at removing the PMs and only retaining the salient-pole-iron on the outer rotor to improve its mechanical reliability. Meanwhile, due to a large equivalent magnetic clearance promoting low torque ripples, the proposed CMG can offer the advantages of achieving a consistent speed ratio and stable transmission within the entire pull-out torque range. By using the two-dimensional finite element method, the detailed parametric analysis and static characteristics of the proposed CMG are performed to set up its design criteria. Moreover, a quantitative comparison with a conventional CMG is conducted, and a prototype is also fabricated for experimentation to verify the validity of the proposed CMG.