動的磁気損失パラメータによるフェライト磁心の鉄損評価

抄録

Iron loss measurement of Ni-Zn ferrite cores up to MHz range is carried out. In order to obtain the frequency characteristics of the hysteresis and eddy current losses in the cores, the electromagnetic fields at different frequencies are analyzed with the medium parameters, such as the complex permeability expressing the DC hysteresis, the conductivity and the pennittivity of the ferrites. The residual loss obtained by subtracting these computed losses from the measured iron loss increases in proportion to the square of the exciting frequency in MHz range. By introducing the dynamic magnetic loss parameter, it is clarified that the residual loss is directly produced by the magnetic field, but not directly caused by the electric field. As a result, it is assumed that the residual loss corresponds to the frictional loss of magnetic domain wall motion. Moreover, the dynamic magnetic loss parameter is expected to be a loss evaluation index for future ferrites because its value is peculiar to each ferrite material, independent of exciting conditions and core size.