General formulation of core loss in soft magnetic materials including effects of eddy current and magnetostriction

A general formulation of the energy dissipation in soft magnetic materials was established, and the contributions from both eddy currents and magnetostriction were compared using this formulation. The energy dissipation of soft magnetic materials has been discussed based on the Steinmetz equation, considering contributions from coercivity and eddy current. However, recently, it was reported that magnetostriction can also generate energy dissipation due to changes in strain corresponding to the domain-wall motion. Hence, a modification of the Steinmetz equation is indispensable for better understanding the mechanism of energy dissipation in soft magnetic materials. Our general formulation elucidates the origin of magnetic energy dissipation across various soft magnetic materials. The results provide a novel explanation for the mechanisms underlying the damping of the domain-wall motion. • The general equation of the energy loss of the soft magnetic materials was formulated considering the effects of coercivity, eddy current, and magnetostriction. • Our general formulation reproduced experimental energy losses. • Prediction of the dominant loss mechanisms in practical materials can develop efficient magnetic cores. • Excess losses are significantly decreased by the increase in the number of domain walls in the soft magnetic materials with the small magnetostriction. • The results provide design criteria for soft magnetic materials considering the effects of magnetostriction and eddy current.