Wireless power transfer across a metal barrier by combined capacitive and inductive coupling

This paper proposes a method to transfer power across a metal barrier wirelessly by combined capacitive and inductive coupling. At the primary side of the power transfer system a two plate coupling interface is designed to allow for a current flow in the metal barrier, which generates a magnetic field for transferring power via an inductive coil at the secondary side. The current distribution in the metal barrier is analyzed by taking the skin effect into consideration, based on which the magnetic field distribution around the metal surfaces is determined. A three-dimensional (3-D) model is established using a computer simulation technology (CST) package to simulate the magnetic field distribution, which gives consistent results compared to theoretical analysis. Finally, a wireless power transfer system is constructed, and practical measurements show that the magnetic flux density near the edges of the metal barrier is higher than that in the middle region. The output power around the edge is also higher although it is more sensitive to the variation of the distance and positioning of the receiving coil. It has demonstrated that more than 11 W of power can be transferred across an aluminum plate with a thickness of 2 mm when the power pickup is placed at an edge of the plate along the current path.