Development of a Magnetic-Geared Permanent-Magnet Brushless Motor

TLDR

High‑torque, low‑speed electrical drives are used when mechanical gearing is impractical, and permanent‑magnet gear has attracted attention for its low noise, maintenance‑free operation, reliability, precise peak‑torque transmission, and overload protection. In this paper, a magnetic‑geared permanent‑magnet brushless motor is presented. The motor merges conventional PM brushless design with a PM gear, and its topology and operating principle are described, with performance‑optimizing techniques validated by finite‑element analysis. Finite‑element analysis confirms that the proposed optimization techniques improve performance, and an alternative operating condition that further reduces speed while increasing output torque is also demonstrated.

Abstract

High-torque and low-speed electrical drives are often employed for applications where mechanical gearing cannot be accommodated. On the other hand, permanent-magnet (PM) gear has drawn significant attention from both academies and industries due to the conspicuous merits, such as reduced acoustic noise, maintenance free, improved reliability, precise peak torque transmission capability, and inherent overload protection. In this paper, a magnetic-geared PM brushless motor is presented. It is a novel low-speed and high-torque motor which merges the advantages of conventional PM brushless motor and PM gear. Its topology and operation principle are introduced. Some techniques are employed to optimize and improve the motor performance, while the validity of the proposed techniques is verified with finite-element analysis. Moreover, an alternative operation condition, which can further reduce the motor speed and increase its output torque, is proposed and analyzed.