Loss Simulation by Finite-Element Magnetic Field Analysis Considering Dielectric Effect and Magnetic Hysteresis in EI-Shaped Mn–Zn Ferrite Core

This paper proposes a calculation method for the core loss in magnetic devices with a Mn-Zn ferrite core at high frequencies (order of several megahertz). An increase in the effective dielectric constant and a decrease in the effective resistivity with increasing frequency are caused by the thin highly resistive layer at the grain boundary. A modeling method that calculates the eddy current and the displacement current in a simplified microstructure using an equivalent circuit can express a frequency-dependent large effective dielectric constant. The magnetic field equations with the modeling of the dielectric effect can reproduce the dimensional resonance well. The modeling of the dielectric effect and the play model for the magnetic hysteresis make it possible to calculate the core loss in complex-shaped magnetic devices accurately over a wide frequency range by the finite-element magnetic field analysis. This loss is calculated as the sum of the magnetic hysteresis loss, classical eddy current loss, and residual loss. To confirm the accuracy of the simulation method, we used an EI-shaped Mn-Zn ferrite core, and the frequency-dependent impedance and loss were compared with experimental results, and good agreement between them was confirmed.