Extended induction range analysis of rotational losses in soft magnetic materials

The main features are described of a novel set-up for the determination of rotational hysteresis and power losses in soft magnetic materials, based on the systematic application and comparison of two independent measuring techniques. Typical results, obtained on soft Fe, 3% nonoriented SiFe and 3% grain-oriented SiFe in a very large induction range, extending fully into the Rayleigh region, are reported. 50-Hz power-loss measurements show the relatively poor technical performance of grain-oriented materials, which do not appear particularly suited for use in electrical rotating machines. The ratio between the hysteresis rotational loss W_rh and the corresponding alternating loss W_ah, measured in soft Fe, exhibits a monotonic dependence on induction and attains a maximum value W_rh/W_ah-4 T.