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In many power electronic applications ferrite cores of magnetic components are biased with a DC or low-frequency premagnetization. Usually however, the influence of t h e bias on t h e losses and permeability is not considered in t h e component design. This paper describes a precise measurement setup t o determine t h e power losses and t h e magnetization curve of premagnetized ferrites. The measurements on typical ferrites of two major manufacturers prove that the influence of a DC-bias on t h e material properties can not be neglected. The utilization of a ferrite is if a DC-bias is applied to the component.

Ferrite cores of magnetic components used in power electronics are often biased with a DC or low frequency premagnetization. Recent work has shown that a bias field may have significant influence on the remagnetization losses and therefore has to be considered in the component design. Using a precise measurement setup this paper investigates the frequency dependence of the power loss increase due to premagnetization. The measurements are performed on typical ferrites of two major manufacturers. The experimental results show that there are two major contributions to the total remagnetization losses of softferrites whereas only one contribution is influenced by premagnetization. Finally the paper discusses some aspects of a mathematical description for the bias problem and leads to an improved understanding that might be useful for the designer of magnetic components. 0-7803-3704-2/97 $1 0.00 0 1 997 IEEE