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International audience; The isotropic properties of Soft Magnetic Composites (SMC) favor the design of new machine topologies and their granular structure can induce a potential decrease of the dynamic loss component at high frequencies. This paper is devoted to the characterization of the broadband magnetic losses of different SMC types under alternating and circular induction. The investigated materials differ by their grain size, heat treatment, compaction rate and binder type. It is shown that, up to peak polarization Jp = 1.25 T, the ratios between the rotational and the alternating loss components (classical, hysteresis, and excess) are quite independent of the material structural details, quite analogous to the known behavior of nonoriented steel laminations. At higher inductions, however, this is no more the case. It is observed, in particular, that the Jp value at which the rotational hysteresis loss attains its maximum, related to the progressive disappearance of the domain walls under increasing rotational fields, decreases with the material susceptibility.

International audience; Granular soft magnetic materials, such as ferrites or Soft Magnetic Composites, are widely spread in modern electrical engineering applications. An important loss contribution is the classical one. It is known that in these materials, two kinds of classical loss must be distinguished: eddy currents flowing at the scale of the whole sample (therefore called macroscopic), and current lines inside the grains (called microscopic). For the macroscopic eddy currents computation, the sample cross sections are often square or rectangular. For eddy currents prediction inside the grains, two cases can be distinguished: the case of low density materials, for which circular or elliptical grain shapes are often realistic, and the case of high density materials. In this last class of granular materials, it is more difficult to identify a precise grain shape, because the deformations occurring during the compaction process often give to the grains a random shape. For carrying out the eddy current computation, rectangular shapes are often considered, because they allow a complete filling of the available space. To our knowledge, analytical eddy current formulae only exist for cylindrical or spherical regions. For other shapes such as squares, rectangles, or ellipses, the finite element method must be used to compute the eddy current distribution, which can be time consuming. This paper overcomes this difficulty by proposing respectively a semi-analytical formula for classical loss in rectangular geometries, and an analytical formula for elliptical cases.