Comparison of Radial Forces between Double-Rotor Planetary and Coaxial Magnetic Gears

This paper presents a comparison study between coaxial and double-rotor planetary magnetic gears with regard to unbalanced radial magnetic forces. Several designs with the same overall dimensions and magnetic materials but having different combinations of pole-pairs numbers are analyzed by numerical simulation. It was shown that, unlike coaxial topology, unbalanced magnetic forces in the double-rotor planetary scheme are highly dependent on load. The magnitude of the radial forces in double-rotor planetary topology is much higher than in coaxial gear even if manufacturing intolerance of coaxial magnetic gear is taken into account. It was found that unbalanced radial forces in double-rotor planetary topology can be greatly reduced by proper selection of pole-pairs combination. Despite relatively high values of unbalanced radial forces, it is concluded that they can still be withstood by the widely available roller bearings.