Rotational loss separation in grain-oriented Fe-Si

Rotational and alternating magnetic losses have been investigated in high p ermeability grain-oriented laminations as a function of frequency (2.5 Hz l ess than or equal to f less than or equal to 150 Hz) and peak magnetization (0.15 T less than or equal to I(p)less than or equal to 1.7 T). The result s have been analyzed according to the concept of loss separation. The rotat ional hysteresis W-h(rot) and excess W-exc(rot) energy loss components exhi bit a similar increasing behavior with the magnetization I-p and reach a ma ximum value around 1.5-1.6 T. W-exc(rot) shows, in particular, a definite f (1/2) dependence. The ratios between rotational and alternating hysteresis and excess losses (R-h=W-h(rot)/W-h(alt), R-exc=W-exc(rot)/W-exc(alt)) foll ow similar trends with I-p, with their values depending, however, on the te sting configuration adopted for the alternating loss measurements (single s trip versus X-stacked strips). The 90 degrees domain wall transitions betwe en the in-plane [001] and the out-of-plane [100] and [0 (1) over bar 0] dir ections are the basic loss producing mechanism under rotational fields, but , on approaching the saturation, the magnetization can eventually rotate on ly through coherent spin rotations and the classical loss term W-cl(rot) al one survives. (C) 2000 American Institute of Physics. [S0021-8979(00)76808- 3].