Introduction to High-Performance Contactless Magnetic Gears and Magnetic-Geared Machines

In recent years, magnetic gears have attracted considerable attention because they can transmit torque without any mechanical contact. Thus, they are free from wear and particle generation—problems inherent to mechanical gears—resulting in superior maintainability and reliability. Among various types, flux-modulated magnetic gears exhibit excellent torque density and efficiency. Furthermore, magnetic-geared motors that integrate a flux-modulated magnetic gear with an electric motor have also attracted considerable attention, as they enable size and weight reduction by sharing the same torque generation principle. This paper provides an overview of the development of ultra-high-speed magnetic gears, as well as two development examples of magnetic-geared motors: one integrating a magnetic gear with a permanent magnet motor, and the other with a switched reluctance motor.