Evaluation of Soft Magnetic Composites for Inductive Wireless Power Transfer

Synthetic polymer-bonded soft magnetic composites can implement an additional magnetic path control in high-power inductive charging systems. This paper presents a material analysis and evaluates the impact of soft magnetic composites. We focus on low ferrite-volume fraction material which has low permeability and can be shaped by injection molding. It must be combined with sintered ferrite plates for effective shielding on the back side of the coil. From a mathematical analysis, we derive shaping guidelines to increase coupling and reduce eddy current loss. Simulation of a receiver coil including soft magnetic composites shows that low permeability is sufficient if it complements a ferrite shielding. To verify the modeling approach and analyze magnetic loss, we present measurement data of a coil provided with a soft magnetic composite material.