Analytical Modeling of Axial-Flux Permanent Magnet Eddy Current Couplings With a Slotted Conductor Topology

In this paper, a 2-D analytical model for the prediction of the magnetic field in permanent magnet (PM) eddy current couplings with a slotted conductor topology is proposed. The originality of this paper lies in the fact that the influences of both the slots and the iron-core protrusions on the eddy currents induced in the slotted conductor are considered in the analytical computation, and the interactions between adjacent conducting spokes are considered. The magnetic field distribution is obtained by taking account of the eddy current reaction caused by the induced eddy currents in the slotted conductor. The moving PM field is treated as the source of a time-varying magnetic field, and both the effects of the time harmonics and spatial harmonics on the torque computation are analyzed. The results from this analytical model and nonlinear finite-element models are compared, and the effectiveness of the analytical method is demonstrated. The reason for the discrepancies between the results is discussed, and an eddy current clustering phenomenon is observed. The 2-D analytical method has the advantage of taking less computational time for a parametric study than the 3-D finite-element method, and can be a useful tool for design optimization.