Exact Analytical Method for Magnetic Field Computation in the Concentric Magnetic Gear with Halbach Permanent-Magnet Arrays

This paper deals with an exact analytical method for magnetic field calculation in the concentric magnetic gear with Halbach permanent-magnet arrays. The analytical method is based on the resolution of Laplace's and Poisson's equations by the separation of variables technique. The key is to newly employ a Halbach permanent-magnet (PM) array to constitute the PM poles in the inner rotor and outer rotor. The corresponding magnetic field distributions and torque transmission are analytically discussed. Compared air-gap magnetic field distributions and electromagnetic torque computed by the analytical method with those obtained from the 2-dimensional finite element method (FEM), the waveform shows good agreement with the measured waveform which proves the proposed method is correct and effective.