Investigation of Magnetically Near-Field Metamaterials in Wireless Power Transfer System

With the development of wireless power transfer (WPT) technology, short transfer distance and electromagnetic (EM) leakage are still two major limitations. Generally, the minimum safe values are required to meet the demand of International Commission on Non-ionizing Radiation Protection (ICNIRP). Recently, near-field metamaterials (NF-MMs) have exhibited a potential to not only improve the transfer efficiency and but also reduce the magnetic flux leakage because of their unique EM properties including negative and zero permeability. In this work, we mainly study the impact of all kinds of NF-MMs on the magnetically resonant WPT. In the WPT system, negative-permeability and zero-permeability XY-MMs are respectively analyzed by using HFSS software. Firstly, the four-coil WPT is optimized and given. We analyze the influence of zero-permeability XY-MMs on the magnetic flux leakage outside the WPT. Secondly, a negative-permeability XY-MM is inserted between the transmitter (Tx) coil and receiving (Rx) coil, which is compared to Z- and isotropic (XYZ) negative-permeability MM. The magnetic field distributions are obtained by numerical simulation. Moreover, The comparison of XY-, Z- and XYZ (isotropic) zero-permeability MMs reveals that the zero-permeability Z-MM would perform the best and the zero-XY MM perform the worst. Finally, we also investigate XY-zero and Z-negative permeability MM in the WPT system. Their magnetic field intensity is observed.