Verification of a Simple Calculation Method of Fringing Loss

Abstract

A current flowing through a smoothing inductor in power converter usually contains the DC component. Hence, an air gap is inserted to the magnetic core in order to prevent magnetic saturation. In this case, the magnetic flux which spreads out from the core causes eddy current loss at windings placed close to the air gap. The fringing loss calculation is valuable for the increase in the power density and power conversion efficiency of converter, but it is very complex due to the heavy simulation required for calculating the eddy current. In this paper, a simple method to calculate the fringing loss is introduced and is used for design of the gapped inductor used in DC/DC converter. Subsequently, the proposed method has been verified based on the experiments with three different cores. The experimental results clarify the relation between inductor structure and efficiency.