A novel magnetic-geared tubular linear machine with halbach permanent-magnet arrays for tidal energy conversion

This paper proposes a novel magnetic-geared tubular linear machine for tidal and wave energy conversion. By embedding the armature windings into the air slots adjacent to the modulating segments of the linear magnetic gear, a compact component which can simultaneously serve both as the modulating segment and the armature stator is realized. Therefore, the proposed machine can enjoy the magnetic gearing effect with improved force density and simpler mechanical structure when compared to its existing counterparts. Moreover, Halbach permanent-magnet (PM) array is used to constitute the PM poles in both the inner mover and outer mover, aiming to increase the thrust force density, reduce the cogging force and enhance the machine efficiency. Design optimization of the proposed machine is described. The machine performances are analytically studied and quantitatively assessed using finite element method (FEM).