A New Method for Determining the Magnetic Properties of Solid Materials Employed in Unconventional Magnetic Circuits

To evaluate the quality of magnetic materials used in electrical machines, accurate material characterization is required. For common, solid (nonlaminated) ferromagnetic materials, characterization procedures such as the toroidal ring sample test method are capable of mapping electromagnetic properties with reasonable accuracy. This is true when the investigation is for solid materials to be used in conventional magnetic circuits, i.e., where the flux paths and induced eddy currents follow the more common 'radial' characteristics, as in a standard rotating machine. When solid ferromagnetic materials are employed in unconventional machine structures, such as for transverse flux machines or tubular linear machines, classical methods are not capable of achieving an accurate representation of the flux conditions in the machine, thus resulting in inaccurate characterization data that usually underestimate the total loss prediction. In this paper, a new testing method is proposed to impose the correct flux conditions for solid materials (used in tubular linear machines) and accurately map the eddy current losses in the solid parts. The proposed method uses a simple experimental test setup to characterize the power loss of solid, ferromagnetic material. The basic experimental results from the new setup are compared to results from three-dimensional finite element analysis.