Comparison of Magnetic-Geared Permanent-Magnet Machines

With the advent of magnetic gears, researchers have developed a new breed of permanent-magnet machines. These magnetic-geared permanent-magnet machines artfully incorporate the concept of magnetic gearing into the permanent-magnet machines, leading to achieve low-speed high-torque direct-drive operation. In this paper, a quantitative comparison of three viable magnetic-geared permanent-magnet machines is firstly performed, hence revealing their key features, merits, demerits and applications. Initially, the development of the magnetic gears, including the converted topologies and field-modulated topologies, is reviewed. Then, three viable magnetic-geared permanent-magnet machines are identified and discussed. Consequently, the corresponding performances are analyzed and quantitatively compared. The results and discussions form an important foundation for research in low-speed high-torque direct-drive systems.