Analytical Magnetic Field Calculation of Coaxial Magnetic Gear With Flux Concentrating Rotor

In this paper, the analytical model for coaxial magnetic gear (CMG) having a flux concentrating rotor is presented using 2-D space harmonic analysis (SHA). Comparing the conventional CMG with surface-mounted permanent magnet (SPM) on both rotors, the differences are described in terms of governing equations, magnetizations of PMs, general solutions, and boundary conditions. To apply the superposition principle, the analytical model is divided into two cases, such as model for SPM rotor and model for flux concentrating rotor with inset PM. Based on the proposed SHA, the radial and tangential components of flux densities at both air-gap regions are calculated, and the pull-out torques of both rotors are also determined by the Maxwell stress tensor. The results of SHA are in good agreement with the results obtained from finite-element analysis.