Two-dimensional analytical model for eddy-current rotor loss calculation of PMS machines with concentrated stator windings and a conductive shield for the magnets

This paper presents a two-dimensional analytical calculation method for the eddy-current problem in the rotors of permanent magnet synchronous machines and investigates especially the case of the application of a conductive shield to protect the magnets from the MMF harmonics. The method takes into account the reaction field of the induced eddy-currents and is, therefore, not restricted to cases where the skin depth is large compared to the geometrical dimensions of the shield, the magnets, and the rotor yoke if that is a solid one. We apply the method to a typical machine with a concentrated stator winding and discuss the results concerning those design aspects, which influence the rotor loss in a relevant manner. The method can also be used for the investigation of the loss behavior of a retaining sleeve for the magnets.