Torque Ripple Optimization of a Novel Cylindrical Arc Permanent Magnet Synchronous Motor Used in a Large Telescope

Abstract

This paper proposes the use of a novel cylindrical arc permanent magnet synchronous motor (CAPMSM) in a large telescope, which requires high positioning accuracy and low torque ripple. A 2D finite element method was used to analyze the cogging torque of the CAPMSM. The CAPMSM can be an alternative for a rotating motor to realize direct drive. A new method is proposed to separate the cogging torque, Tcog, into the torque, Tslot, generated by the slotted effect and the end torque, Tend, generated by the end effect. The average torque and the torque ripple are optimized considering stator center angle, the angle between two adjacent stators and the unequal thickness of a Halbach permanent magnet. The torque ripple decreased from 31.73% to 1.17%, which can satisfy the requirement of tracking accuracy for large telescopes.

Keywords

• cylindrical arc permanent magnet synchronous motor
• Halbach permanent magnet
• torque ripple