2.5.1
Abstract
Pressed powdered iron has been used in motor applications for many years. The use has been limited to mechanical parts or to magnetic circuit components where the flux is not changing. Attempts to use these parts as primary alternating flux carriers resulted in high core loss in turn resulting from eddy currents, which usually made them unsuitable. Some companies have developed methods of manufacturing these kinds of parts that keep eddy current losses within reason. Although the electrical and mechanical characteristics are not identical to those of lamination steels, they are comparable. The following section describes this type of material.A new soft magnetic material has been developed for ac and dc motor applications. The motor components are made by a powder metallurgical process, in contrast to the traditional method of stacking punched laminations. This new material not only offers many manufacturing advantages but exhibits a core loss that is comparable to that of many grades of motor lamination steels at 60 Hz. Because of its low eddy current loss, the material has excellent high-frequency magnetic properties, making it an ideal material for brushless dc motors operating in the high-frequency range.