Torque-to-weight Ratio Improvement and Permanent Magnet Usage Reduction in Large-Scale Magnetic Gears for Offshore Wind Power Generation

Magnetic gears, which can transmit power without mechanical contact, offer lower vibration and acoustic noise compared with conventional mechanical gears. A flux-modulated-type magnetic gear stands out due to its high efficiency and torque density because all the permanent magnets consistently contribute to power transmission. This paper discusses the torque-to-weight ratio improvement and permanent magnet usage reduction of large-scale flux-modulated-type magnetic gears, aiming to construct highly reliable, lightweight, and resource-saving offshore wind power generation systems with magnetic gears. First, to demonstrate the effect of the Halbach array on the torque, an air gap flux density waveform in a prototype magnetic gear with Halbach array magnets is directly measured and compared with that using conventional parallel array magnets. Next, by applying the ideas of the Halbach array and multi-polarization into large-scale magnetic gears, improvements in the torque-to-weight ratio and reductions in permanent magnet usage are demonstrated using the finite element method (FEM).