鉄損の直流磁界バイアス特性を考慮した降圧チョッパ回路用インダクタの低損失設計

Abstract

In order to increase the power density of power converters, reduction of both the loss and the volume of the inductor is essential. However, it is difficult to calculate the iron loss of the inductor with the Steimetz equation or the improved generalized Steinmetz equation (iGSE) because those calculation methods do not consider the loss dependency of pre-magnetization. Hence, we have to repeat the re-design process in order to reduce the inductor loss or the inductor volume. In this paper, the authors propose an accurate loss calculation method for the inductor used in the buck-chopper circuit that is based on the iron loss characteristic considering pre-magnetization. In addition, the overall loss of the inductor is compared among three typical magnetic materials, such as iron powder, sendust, and ferrite, which have different iron loss characteristics for pre-magnetization. As a result, the sendust-based inductor achieves both the same loss reduction and a smaller volume compared with the ferrite-based inductor. From these studies, it is concluded that the proposed loss calculation method, which takes into account the loss dependency of pre-magnetization, is useful for optimum design of the inductors.