Graph-Based Optimization of Magnetic Cores for Lightweight and Low-Leakage Inductive Power Transfer Systems

Laminated nanocrystalline cores are considered a promising replacement for ferrites in compact and safe inductive power transfer (IPT) systems due to their high-saturation flux density and superior shielding capability. However, their inherent anisotropy and high conductivity introduce challenges such as flux discontinuity and eddy current loss, particularly with unipolar coils. Inspired by magnetic core memory structure and leveraging the duality between electric and magnetic circuits, this article proposes a graph-based evaluation and optimization method to quickly identify critical locations within laminated core plates that hinder flux continuity. By selectively replacing regions that obstruct magnetic flux linkage, eddy current loss is effectively mitigated. Experimental validation on a 3.3 kW IPT prototype demonstrates that the optimized nanocrystalline core configuration achieves 95.71% dc–dc transfer efficiency. The proposed design also reduces weight by 16.3%, leakage flux by 27%, and manufacturing cost by 39.1% compared to a state-of-the-art ferrite core configuration.