Eddy current loss analysis in permanent magnets of synchronous machines

Abstract

When designing permanent magnet synchronous machines (PMSM) the losses in the permanent magnets may not be neglected. Especially in high-speed applications these losses contribute a proportion of the total losses which can be significant. In literature existing analytical loss calculation approaches are generally validated by numerical Finite Element Method (FEM) simulations and, however, have hardly been verified by experimental measurements. In this paper the eddy current losses of permanent magnets are investigated by an analytical loss calculation approach which is verified by FEM computations. Furthermore, the results are validated by a measuring setup which determines the AC loss in permanent magnets by a double coil measuring arrangement. The relative conductivity of the permanent magnet is an uncertain parameter for eddy current loss calculations. Therefore it is determined metrologically. The measuring arrangement which is used for this purpose is introduced. As a result important conclusions regarding the calculation and measurement of AC losses in permanent magnets are achieved.