Enlarging the Standard Permeability Set of Powder E-Cores by Combination of Different Perm Core-Halves

Powder cores are widely used in the design of storage chokes and coupled inductors. Their main advantage is the absence of a discrete air gap. Sendust E-cores are available from different producers in standardized sizes and permeabilities. These cores can be combined to get a set of new permeabilities, without inserting any air gap or the creation of new materials. In this paper we show the new permeability levels derived by combination. The iterative calculation of a choke based on mixed cores is explained as well as the influence of fringing for those chokes. We present the mixed core saturation behavior and the H-field distribution in the two different core halves, derived by Finite Element analysis.