An Axial-Field Flux-Modulated Magnetic Gear

This paper proposes an axial-field flux-modulated magnetic gear (AF-FMMG), in which the rotations with different speeds of the inner rotor and the outer rotor can be achieved based on the modulation function of two stationary modulation rings. Due to the axial-flux configuration, the proposed AF-FMMG offers the advantages of a simpler mechanical structure and a theoretically limitless gap length between two rotors. Hence, the proposed magnetic gear is very suitable for applications that require a hermetic isolation between input and output shafts, such as pumps used in the food, agriculture, and aerospace industries. First, the configuration and operation principle of the AF-FMMG is described. Then, by using finite-element analysis, several dimensions are optimized to obtain the maximum torque output. Finally, the output performances of the proposed AF-FMMG are calculated, and a torque density in excess of 77 kNm/m
³
can be achieved.