Core Loss in Toroidal Cores Based on Fe-Based Amorphous Metglas 2605HB1 Alloy

Amorphous ribbon exhibits low power loss. However, core loss of amorphous ribbon based toroidal cores is about twice as large as that of the ribbon even after field annealing under an optimum condition. In the present work, effects of residual strain and inter-laminar eddy-current loss on loss increase were examined for toroidal cores based on recently developed Metglas 2605 HB1 alloy which has a high saturation induction B_s of 1.64 T. The results show that: 1) with increase in residual strain, core loss and hysteresis loss are increased and no significant change in excess eddy-current loss was observed, and 2) there is no significant difference for frequency dependence of eddy-current loss by varying packing factor from 83% to 87%. This implies that there is no loss increase due to inter-laminar eddy current.