Investigation of Negative and Near-Zero Permeability Metamaterials for Increased Efficiency and Reduced Electromagnetic Field Leakage in a Wireless Power Transfer System

In order to meet both safety and efficiency requirements of wireless power transfer (WPT) systems, reducing electromagnetic field (EMF) leakage and improving efficiency are critical factors in the implementation of systems. Recently, metamaterials have exhibited the ability to control the electromagnetic wave propagation. In this paper, the WPT system integrating with near-field mu-near-zero (NF-MNZ) and mu-negative permeability (MNG) metamaterials is proposed to control EMF leakage below a certain level and improve transfer efficiency. The NF-MNZ and the MNG metamaterials are placed on both sides and in the middle of the WPT system, respectively. In addition, the property of the NF-MNZ metamaterial slab and its working principle on the WPT system are analyzed. The shielding performance of the NF-MNZ metamaterial are evaluated via numerical simulation and experimental investigation. Finally, the efficiency and the magnetic field strength of the WPT system with two different types of metamaterials have been investigated by the experimental measurements. At the transfer distance of 40 cm, the experimental results show that the efficiency of the WPT system is increased by 12.06% and the magnetic field strength is reduced by 62.09%.