Torque-to-Weight Ratio Improvement of Large-Scale Magnetic Gears for Offshore Wind Power Generation

Magnetic gears, which can transmit power without mechanical contact, offer lower vibration and acoustic noise than conventional mechanical gears. A flux-modulated-type magnetic gear stands out due to its high efficiency and torque density since all the permanent magnets consistently contribute to power transmission. This paper discusses the torque-to-weight ratio improvement of large-scale flux-modulated-type magnetic gears, with the aim of constructing 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 to that with conventional parallel array magnets. Next, applying the ideas of the Halbach array and the multi-polarization into large-scale magnetic gears, improvement in torque-to-weight ratio demonstrated using finite element method (FEM).