Examining Magnetic Property Variation: A Look at Specification-Acceptable Electrical Steel

One of the key strategies of electrical machine design is the optimization of the performance of the machine through careful attention to the properties of the materials and systems that will be incorporated in the manufacturing of the machine. An important component of this strategy is the characterization of the magnetic properties of the lamination materials that will be used if the machine is to have a laminated core structure. The nearly universal use of computerized simulation and analysis software in the machine design community has exposed the need for much more precise data on the magnetic properties of these steels. As a result, there has been considerable research into these properties, both within the academic community as well as among material producers and corporate research centers. Yet, as these studies have begun to deliver a more robust body of theoretical and practical knowledge pertaining to the performance of lamination materials, not only under the traditional parameters of mains frequencies and sinusoidal excitation but also such contemporary operating conditions as higher frequency and nonsinusoidal excitation, the practical limitations of commercially produced electrical steels have often been overlooked. As a result, electrical machines that have been optimally designed will, at times, fail to consistently perform as expected. This article examines a narrow range of fully processed, nonoriented silicon steels and their properties to develop an understanding of the potential variation in magnetic properties of lamination steels that are acceptable under current international standards and to present possible strategies for the accommodation of these variations in the manufacture of electrical machines.