Study of eddy-current loss reduction by slit in reactor core

Air-gapped iron-cores are widely used for power reactors. Eddy currents are induced in silicon steel sheets due to fringing flux, and this causes local overheating. In order to avoid local heating and to design reactors with high efficiency, the analysis and experiments for evaluating local losses in the core block of the reactor are necessary. In this paper, the modeling of laminated core for practical and accurate analysis is investigated. The number of elements can be reduced by classifying the analyzed region in terms of the amount of fringing flux penetration. The eddy-current losses due to fringing flux are examined using three-dimensional finite-element method and experiments. New concepts for optimal designing of slits are shown.