Variable inductors can control the inductance of ac winding by dc excitation from a control circuit. For a large-capacity variable inductor, an EIE core is suitable because it is made of laminated iron and has no gaps for harmonic current reduction. EIE cores are expected to have practical applications to power control apparatuses in electric power systems. For optimum design of an EIE core, we previously proposed a reluctance network analysis (RNA). However, it is necessary to improve the accuracy of the iron loss calculation. This paper presents a method for modeling the eddy current caused by leakage flux in the laminated direction. We predict the paths of the eddy current, and express them in an electric circuit model. The eddy current circuit model is combined with the RNA model of an EIE core. We calculate the iron loss characteristics of the EIE core variable inductor, and evaluate the validity of the proposed method by comparing the calculated results with measured values.
