Modelling Dynamic Losses Under Rotational Magnetic Flux

The flux density waveform in the stator of a rotational electrical machine or three-phase transformer is typically bidirectional in many regions of the core. However, rotational magnetic flux can be observed in some parts of their magnetic circuits. The iron core under rotational flux presents magnetic losses, usually, greater than the alternating ones, for a same flux magnitude. The magnetic behavior of materials under rotating flux is extremely complex and can not be represented with hysteresis or conventional magnetic losses models. The vector hysteresis model of Jiles-Atherton has been shown effective in modeling rotating flux for isotropic and anisotropic materials. It is observed that the rotational losses increase with the increase of excitation frequencies. In this work, the iron losses behavior is investigated under rotational flux by combining the Jiles-Atherton vector hysteresis, eddy currents and excess losses models. Experimental curves are obtained from a rotational single sheet tester and the losses components are analyzed.