A Novel Single-Helix Magnetic Lead Screw for Wave Energy Converter

Magnetic lead screw (MLS) owns many merits for wave energy generation system applications. However, to resist the huge, instantaneous impact of the waves, the radius of the mover and rotor of the MLS should be large to obtain sufficient stiffness. And the length of the mover needs to match the height of the wave to transfer as much power as possible. Therefore, a great many of permanent magnets (PMs) will be consumed when size of the traditional MLS is huge, and the maximum thrust force would be much greater than the wave excitation force. This will lead to the waste of PMs and poor starting performance. Also, the ideal spiral PMs are quite difficult to manufacture. Therefore, in this paper, a novel type single-helix MLS, which adopt single spiral PMs on the surface of the rotor and translator, is proposed to save PM consumption on the premise of meeting the demand of wave power generation system. The new structure provides a new choice for the application of magnetic screw in wave power system. The performance and the design features of the proposed novel MLS is analyzed through the three-dimensional finite-element method and compared with the traditional MLS and reluctance-based MLS. In addition, a simple spiral PM installation method based on discretized PMs for the proposed MLS is also proposed in this paper.