Magnetic Design Method for Multi-Material Inductor to Flatten Efficiency Curve of Power Converters Within Wide Load Ranges

This article proposes a novel magnetic design method for multi-material inductor which combines multiple powder cores with different magnetic characteristics. The purpose of this work is to flatten the power conversion efficiency curve over wide load ranges of power converters using the multi-material inductor. For the purpose of simplicity, the multi-material inductor which consists of two powder cores with different characteristics is taken as an example. A design method of multi-material inductor is proposed and demonstrated with a modeling method considering the non-linear relative permeability. The experimental results show that the multi-material inductor using two powder cores can improve the power conversion efficiency of the bidirectional converter over wide load ranges compared with other two single-material inductors. The proposed inductor succeeded to flatten the efficiency curve of the converter and realize a higher power conversion efficiency at the full-load condition. The validity and effectiveness of the proposed magnetic design method are confirmed from theoretical analysis and experimental results.

I. Introduction

The importance of realizing high-efficiency power converters is growing along with the growth of the market in many industrial applications, especially, in power converters for renewable energies and battery energy storage systems (BESSs) as shown in Fig. 1 [1]. In these applications, power converters realizing high power conversion efficiency within wide load ranges are necessary to efficiently use renewable energy sources and BESS. Fig. 1.

Bidirectional converter interfacing BESS with PV arrays.