The dependence of permeability and losses on direction of magnetization in anisotropic ferromagnetic laminations

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Abstract
The permeability and power loss during cyclic magnetization of anisotropic ferromagnetic laminations depend strongly on the angle between the texture axis and the applied field. This paper puts forward a simple macroscopic tensor theory which enables the angular dependence of these and other related magnetic properties to be predicted from measurements made in the symmetry directions alone. The essential feature of the theory is the assumption that, in the absence of any shape anisotropy, magnetization in each of these orthogonal symmetry directions proceeds independently. Experiments designed to test the theory are described. Very good agreement is found in the initial permeability region for Goss-textured (110) [001] silicon iron. The angular dependence of the peak field required for sinusoidal magnetization is also shown to be predicted accurately for inductions up to some 10 kG; losses at these inductions tend to be underestimated by up to 15%. The analysis also reveals the importance of transverse flux closure, via neighbouring laminations, on the behaviour of skew-magnetized grain-oriented silicon iron at flux densities up to 15 kG.