Eddy-Current Loss Analysis of Noncontact Magnetic Device With Permanent Magnets Based on Analytical Field Calculations

This paper reports on the analysis of eddy-current loss of a magnetic coupling (MC) that uses a Halbach array permanent magnet (PM). A MC is a kind of noncontact magnetic device (NCMD). When the conductive materials of NCMDs are exposed to time-varying magnetic fields, eddy currents are induced in the conductive materials, leading to losses. An analysis of the eddy-current loss is therefore required, and for MCs, the analysis of eddy-current loss is particularly more important. We obtain the magnetic field solutions of the Halbach magnetized PM based on the magnetic vector potential and 2-D polar-coordinate system. In addition, using the derived magnetic field solutions, we derive analytical solutions for eddy-current loss using the equivalent electrical resistance that is calculated from the magnet volume and conductivity. A 2-D finite-element analysis is employed to confirm the validity of the analytical results of the eddy-current density and eddy-current loss. Finally, we investigate the influence of the number of Halbach segments on the eddy-current loss induced on the MC.