Sensorless evaluation of asymmetric hysteresis loops of ferromagnetic materials

The sensorless determination of the dynamic hysteresis loop of magnetic materials, and in particular those of magnetic plates, can be obtained under ac symmetric conditions in a relatively simple way. This paper proposes a new digital method and instrument for the sensorless evaluation of the dynamic hysteresis loop under ac asymmetric conditions, in the presence of a dc polarization of the magnetic flux. The method is based on the determination of the parameters of a simplified linear model of the magnetic circuit, which preserve the energy equivalence. The results of some experimental work are given in order to validate the proposed method.