Magnetic losses at high flux densities in nonoriented Fe–Si alloys

We present and discuss power loss measurements performed in Fe–(3.5 wt%)Si nonoriented laminations up to very high flux densities. The results are obtained on disk samples using a 1D/2D single-sheet tester, where the fieldmetric and the thermometric methods are applied upon overlapping polarization ranges. The power loss in the highest polarization regimes (e.g. Jp>1.8 T) is measured, in particular, by the rate of rise of temperature method, both under controlled and uncontrolled flux density waveform, the latter case emulating the conditions met in practical unsophisticated experiments. Lack of control at such extreme Jp levels is conducive to strong flux distortion, but the correspondingly measured loss figure can eventually be converted to the one pertaining to sinusoidal induction at the same Jp values. This is demonstrated as a specific application of the statistical theory of magnetic losses, where the usual formulation for the energy losses in magnetic sheets under distorted induction is exploited in reverse fashion.