Surface Impedance Boundary Condition With Circuit Coupling for the 3-D Finite-Element Modeling of Wireless Power Transfer

A light 3-D finite-element magnetodynamic a-v model of resonant wireless power transfer (WPT) coils using a 3-D surface impedance boundary condition (SIBC) strongly coupled with an external circuit is proposed, reflecting the importance of external circuit elements (notably capacitances) in the resonance phenomena at circuit and field levels. The computational gain ensuing from the use of SIBC instead of massive conductor formulations is demonstrated on an academic example. The method is validated by comparing the simulated and experimentally measured input impedance of a complete resonant WPT system, attesting the correct behavior of the model while saving important computational resources.