Design and Analysis of Coaxial Magnetic Gears Considering Rotor Losses

This paper investigates the rotor losses of coaxial magnetic gears (CMGs) with surface-mounted permanent magnets. The iron losses and PM eddy current losses that occurred in the two rotors of an existing gear are calculated and analyzed by the finite-element method. Using magnetic flux barriers in the outer rotor, a novel rotor structure for CMGs is proposed to reduce the rotor losses, in which subharmonics are considered. A 1-D magnetic permeability model is also introduced to understand the principle of reducing the main subharmonics. Then the outer rotor losses of the existing gear and proposed gear are compared. The proposed model and the results presented in this paper will give useful guidelines for a reliable design and design optimization of the CMGs.