Performance Potential of High Gear Ratio Coaxial Magnetic Gears

It has been traditionally thought that a coaxial magnetic gear (MG) can only have a high volumetric torque density at a low gear ratio. This paper points out that by using the right sized radius and utilizing judicious radial parameter sweep analysis a high torque density can be created that also operates with a high gear ratio. An example design is presented that has a 33:1 gear ratio and a 3-D finite element analysis calculated torque density in excess of 300 Nm/L. The paper also provides a direct torque density comparison of the Halbach rotor MG relative to the surface mounted permanent magnet MG.