Rotational Core Loss and Permeability Measurements in Machine Laminations with Reference to Permeability Asymmetry

Rotational core loss and vector magnetization in electrical steel laminations are investigated under the circular 2D rotating field. The loss under a rotating field is compared with the loss under a pulsating field, and the behavior of the dynamic hysteresis loops in both cases are explained with reference to permeability asymmetry. The permeability of the magnetic material under the rotating field tends to change based on the flux direction. Experimental data is obtained using a new test fixture based on an electromagnetic Halbach array, which is capable of measuring rotational and pulsating losses in circular steel laminations. The measurements were performed for M15 gauge 29 electrical steel material at three typical frequencies of industrial interest (60 Hz, 400 Hz, and 1 kHz), and results are presented and discussed. It is found that there is a relation between the direction of applied field and the permeability, in addition to a strong effect on the permeability in the case of rotational flux when compared to pulsating flux.