Electromagnetic performance analysis of the umbrella shaping inner rotor coaxial magnetic gear with dual modulation rings

Abstract

Abstract The coaxial magnetic gear is a new type of noncontact transmission mechanism, which avoids the inherent defects of the mechanical gearbox due to gear meshing transmission. To study a coaxial magnetic gear (CMG) with high torque density and low torque ripple to replace the mechanical gear in the semidirect drive wind turbine, a novel umbrella shaping inner rotor CMG (US‐CMG) with an auxiliary modulation ring is proposed in this paper. The novel structure adopts a CMG with a dual modulated ring to increase the electromagnetic torque. In addition, the magnetic block of the poled inner rotor is divided into three pieces magnetized by Halbach arrays, and the middle piece is umbrella‐shaped to reduce torque ripple. Based on the topology of the US‐CMG and the principle of the magnetic field modulation, the operation mechanism of the US‐CMG is analyzed. A contrastive analysis among the US‐CMG, Halbach magnetized dual‐modulator CMG (HM‐CMG), and surface‐mounted CMG (SM‐CMG) is established to identify the performance of the US‐CMG. Compared with the SM‐CMG, the results show that the electromagnetic torque of the US‐CMG has increased by 65.46%, and the torque ripple of the US‐CMG is 57.6% of that of the SM‐CMG.

Keywords

• auxiliary modulation ring
• electromagnetic torque
• torque ripple
• umbrella shaping