MEASUREMENT AND PREDICTION OF DYNAMIC LOOP SHAPES AND POWER LOSSES IN SOFT-MAGNETIC MATERIALS

Measurements of dynamic hysteresis loops on Fe78B13Si9 amorphous ribbons, in the range 0.5 Hz less than or equal to f less than or equal to 10 kHz and 0.1 T less than or equal to B less than or equal to 0.9 T are presented. It is found that the dynamic loop width increases, at each loop point, according to a(dI/dt)(1/2) law, where dI/dt is the instantaneous magnetization rate. Experiments are interpreted through a dynamic generalization of the Preisach model. The model correctly predicts the frequency and induction dependence of measured loops. In addition, it permits to evaluate the decay with frequency of longitudinal domain wall interactions driven by magnetostatic fields.