Optimization of a Magnetic Field Modulated Magnetic Lead Screw for Wave Energy Conversion Based on Axial Flux-Concentrating PMs

This article proposes an axial flux-concentrating segmented field-modulated magnetic lead screw (AFCS-MFMLS) designed for wave energy conversion applications. The composite rotor of the AFCS-MFMLS incorporates segmented helical permanent magnets (PMs), which enable simultaneous torque transmission and energy conversion, and the inner stator utilizes ring-shaped axially magnetized PMs, effectively reducing the overall quantity of PM material required. This configuration offers several distinct advantages, including high thrust density, superior energy transmission efficiency, and reduced manufacturing complexity. The AFCS-MFMLS is analyzed based on 3-D helical magnetic field modulation principle. Then, the electromagnetic performance of the AFCS-MFMLS, including thrust, torque, peak thrust density, and peak torque density under different pole pair combinations and geometric parameters, is analyzed by the finite element method to finally determine the structural parameters. The optimized AFCS-MFMLS achieves a peak thrust of 1.15 kN, a peak torque of 1.41 N·m, a peak thrust density of 8.46 MN/m3, and a peak torque density of 10.36 kN·m/m3, corresponding to improvements of 45.57%, 45.36%, 76.25%, and 75.59% over the conventional segmented field-modulated magnetic lead screw, respectively. Finally, one of the prototypes is fabricated and tested to validate simulation results.