Precise Modeling of Inductive Wireless Power Transfer With Lossy Magnetic Sheets

Accurately analyzing power losses in inductive wireless power transfer (WPT) including lossy magnetic sheet is challenging, as coils have mutual influences on each other's power dissipation. This article proposes a precise analytic model for inductive WPT with lossy magnetic sheets. Combining a partial element equivalent circuit (PEEC) with a two–port network, both self– and mutual-impedances of coupled coils are accurately calculated considering eddy current effects. Furthermore, the proposed PEEC–based model incorporates the complex permeabilities of lossy magnetic sheets, thus addressing a critical gap in previous studies that have not considered magnetic sheets with losses in their analysis. The suggested model is verified with finite element method (FEM) simulations and measurements. Compared with an FEM simulator, the proposed model calculates impedances about 31 times faster, substantially reducing the number of meshes. Finally, the ohmic and magnetic losses in coil windings and magnetic sheets are investigated with the proposed model, demonstrating that the phase adjustment of currents using the compensation capacitor is effective to reduce the losses caused by eddy currents and lossy magnetic sheets. The proposed model offers more detailed and accurate loss analysis, compared to conventional methods based on circuit analysis.