Anomalous eddy current loss in soft magnetic materials via Maxwell equations-coupled multiscale micromagnetic simulations

Abstract

Unveiling the underlying mechanism of iron loss in soft magnetic materials is crucial for advancing power electronics. Despite its significance, anomalous eddy current loss, a part of iron loss, remains insufficiently understood due to the complexity of magnetic domain dynamics. In this study, we performed multiscale micromagnetic simulations, coupling Maxwell equations with the Landau-Lifshitz-Gilbert equation, to investigate how the operating frequency and defect size affect iron losses. Our results revealed that as the frequency increases, localized eddy currents are intensified, leading to increased overall energy dissipation. This frequency-driven transition reflects a shift from domain wall movement to magnetization rotation and is accompanied by an increase in magnetostatic energy. Additionally, the presence of larger defects increases exchange energy and eddy current density, which, in turn, amplifies the total iron loss by promoting domain wall movement. These findings offer valuable insights into the transition in magnetization reversal modes and the associated energy loss mechanisms, providing a foundation for designing low-loss soft magnetic materials.