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The B-H loop is the representation of the relationship between ﬂux density B and magnetic ﬁeld H at any instant in time. Pe is the classical eddy current loss calculated from Maxwell’s theory (7) on the assumption that the B-H characteristic is linear (permeability constant) and the ﬂux density varies sinusoidally with time, it ignores the presence of magnetic domains. Pa represents the remainder of the loss which is attributed to the rapid motion of domain walls. All three components increase with increasing peak ﬂux density and with frequency (hysteresis loss per cycle is assumed to be independent of frequency).
The grid is a two-dimensional array of square air sections cut into a ferrite-tile matrix. This structure is modeled with an averaging technique known as homogenization and the transverse material properties are ap- Table 1. 69 (7) µt = µa + 1−g 1 g + µ0 − µa 2µa The longitudinal permittivity and permeability are known exactly (17) as z = (1 − g) 0 +g a (8) and µz = (1 − g)µ0 + gµa In these expressions, g ϭ a2 /p2 is the fraction of space occupied by the absorber, and ⑀a and Ȑa are complex parameters of the bulk ferrite.
Typical permeability and loss characteristics are shown in Fig. 3. Grain-oriented siliconiron is often referred to as (110) oriented silicon steel or Goss textured silicon steel (named after the inventor J. ), Wiley Encyclopedia of Electrical and Electronics Engineering. Copyright © 2007 John Wiley & Sons, Inc. 2 Eddy Current Losses Figure 3. Deterioration of power loss and permeability of grainoriented silicon steel with direction of magnetization relative to the rolling direction. Figure 1.
33.Magnetics by John G. Webster (Editor)