Magnetic field analysis of a coaxial magnetic gear mechanism by two-dimensional equivalent magnetic circuit network method and finite-element method

Non-contact magnetic gears offer unique features: no mechanical loss, no mechanical fatigue, overload protection, high efficiency, precise peak torque transmission, tolerance of misalignment, isolation of vibration and low acoustic noise, which overcome the inherent disadvantages of existing mechanical gears. Among the various types of magnetic gear mechanisms, the coaxial magnetic gear mechanism improves the utilization of permanent magnets to generate a high transmitted torque, which has been receiving more and more attention in recent years. This paper presents a two-dimensional (2-D) equivalent magnetic circuit network method to predict the magnetic field distribution of a coaxial magnetic gear mechanism. The topological structure, working principle and speed reduction ratio of an existing coaxial magnetic gear mechanism are introduced first. A 2-D equivalent magnetic circuit network method is then proposed to calculate the radial components of the magnetic flux densities within the inner and outer rotors. 2-D finite-element analysis (FEA), undertaken by applying commercial FEA software Ansoft/Maxwell, confirms the validity and effectiveness of the proposed analytical model. A 2-D equivalent magnetic circuit network method can be provided as an effective tool for the magnetic field analysis and optimal design of coaxial magnetic gear mechanisms.