Loss decomposition in non-oriented steel sheets: the role of the classical losses

The concept of loss separation based on the Statistical Theory of Losses (STL) provides complete and accurate description of the frequency dependence of the energy losses in non-oriented soft magnetic sheets under the assumption of uniform magnetization reversal through the sheet cross-section. This assumption, implying a simple standard formulation for the classical loss component, has been recently challenged in the literature, in favor of a non-uniform reversal mechanism, expected to prevail in highly non-linear materials, where saturation magnetization wavefronts are deemed to symmetrically propagate across the sheet thickness (Saturation Wave Model, SWM). Different conclusions regarding the dynamic loss analysis and its decomposition into the classical and excess loss components correspondingly emerge. In this paper we discuss detailed investigations on the broadband energy loss versus frequency behavior in different non-oriented Fe-Si and low-carbon steel sheets. The experiments can be fully and consistently described by the STL. This occurs, in particular, for high-induction values and near-squared hysteresis loops, a predictable condition for adopting the SWM, which fails instead to account for the experiments.