Mechanism of dynamic domain size variation and iron losses in grain-oriented Si-Fe cores

Computer analysis for dynamic domain size variation in grain-oriented 3% Si-Fe tape-wound cores is, first, presented by using a principle of minimization of total free energy, the sum of magnetostatic energy at grain boundaries and dynamic bowing domain-wall energy, and by using quasi-static permeability as a function of peak flux density. Second, iron losses per cycle, Wi/f, in the cores are calculated and compared with experimental results: the origin of ´anomalous loss´ is quantitatively clarified; Wi/f becomes minimum at certain value of tape thickness; Wi/f is smaller at ´voltage excitation´; and instantaneous domain-wall profiles and energy loss are illustrated. An experimental result for reduction of iron losses by scratching method is also shown.