A Comparative Study of Ferrite and Powder Core Filter Inductor Designs in Power Converters for Unified Battery Charging Applications

In this paper, a comparative study of ferrite and powder core based filter inductors for a unified battery charging power conversion system is presented. The focus of this paper is to explore an improved inductor design procedure for powder core inductors and benchmark it against ferrite core based inductor designs. The well-known area-product approach is used as a starting point for the process of inductor design. The impact of fringing has been incorporated in the ferrite core-based design and the impact of DC bias has been incorporated in the powder core-based design. A 400 W buck converter-based unified battery charger hardware prototype is developed in the laboratory. Three candidate filter inductor designs are considered and implemented, and the performance of the designed filter inductors have been evaluated using small-signal and large signal measurements. The inductor losses are quantified and their performance under varying DC bias conditions is evaluated.