Core losses under DC bias condition based on Steinmetz parameters

When designing inductive components, calculating core losses is a difficult and not yet entirely solved problem. In particular it is impossible to predict the influence of a DC premagnetization on the losses without performing extensive measurements. For this work, different materials have been tested to gain information how core losses are influenced by a premagnetization. Measurements on molypermalloy powder, silicon steel, nanocrystalline material, and ferrite cores have been performed. Of the tested materials, a premagnetization mainly influences losses in ferrites and nanocrystalline materials, whereas the influence of a premagnetization in molypermalloy powder cores, and cores of silicon steel is negligible. The Steinmetz Premag-netization Graph (SPG) that shows the dependency of the Steinmetz parameters (α, β and k) on premagnetization is introduced. This permits the calculation of core losses under DC bias conditions. Such graphs are given for different materials and different operating temperatures. In addition, a detailed description of the test system is given, as high accuracy is crucial.