VII.High-Efficiency Magnetic Gear and Developing Magnetic-Geared Motor

Magnetic gears can transmit torque without any mechanical contacts. Hence, they have low vibration, no wear and fatigue, which offer maintenance-free operation. Various kinds of magnetic gears have been introduced in previous papers and patents. Among them, a flux-modulated type magnetic gear, which consists of an inner and outer rotor with surface-mounted permanent magnets, and ferromagnetic stationary parts which are called pole-pieces, is attracting interest since the torque density is higher than the other magnetic gears [1].