Study on Cogging Torque Reduction in a Hybrid-Type Magnetic Gear

Magnetic gears have some advantages such as low mechanical loss and maintenance-free operation that are not observed in conventional mechanical gears, and various kinds of magnetic gears have been proposed; however, they also have demerits: low torque and a complex structure involving multipole magnets. We have previously proposed a hybrid-type magnetic gear with a simple structure that can generate large torques; however, it was found that the high-speed rotor in the gear developed a large cogging torque, causing vibrations and generating noise. In this paper, a method for reducing the cogging torque is presented, and it is verified by a 3D FEM and carrying out measurements on a prototype.