Study Of Efficiency Enhancement Of Wireless Power Transfer Based On Electromagnetic Metamaterial

The electromagnetic metamaterial(EMM) as a kind of composite material owns the originality artificial structure and the unnormal physical characteristics which most materials do not have. The character is not depending on the intrinsic properties but is determined by the artificial structure. The EMM has drawn much attention in the physical and the electromagnetic field. Since the EMM has the negative refraction and the focusing effect for electromagnetic wave, it makes the fabrication of the EMM be applied to the study of electromagnetic property and the utilization of manufacture and livelihood. Owing to the specific electromagnetic property and the principle of wireless power transfer(WPT), in this thesis, base on the numerical simulations and the principle of the EMM design, a magnetic anisotropy EMM, especially the sub-wavelength structure, has been designed for the magnetic coupling resonance in the WPT system. Through the study and numerical simulations for the electromagnetic properties, the experimental results show that the magnetic field of WPT system has been enhanced by the use of the EMM. The meaningful results are as follows.Starting from the theory make an explaination about the principle and method for the WPT system. Making an analysis about the categorization of EMM and special electromagnetic properties.This paper designs a spiral resonance coil with the resonant frequency at 15.46 MHz for the WPT system. Through the CST simulation software shows that the polarization between two coils can be used to change the resonant frequency and quality factor(QF) in transfer system combined by two spiral coils. Because of the cross coupling effect, both transformation resonant frequency and frequency split happened when the third same spiral coil was added to the other two coils.The variation and distribution in the magnetic and electron field which cross the isotropic and anisotropic EMM by the Comsol Multiphysics software. The result shows that there have the obviously different focusing effect for electromagnetic wave which respectively cross the isotropic and anisotropic EMM.Designed an EMM which have double-faced spirals with sub-wavelength structure based on FR4 substrate. The ratio of the structure size and wavelength reached 737. By CST simulation, extract the scattering parameters of vertical incidence of a magnetic field, and ues the Smith backstepping calculated to obtain the permeability, studies have shown that near 13.56 MHz can realize the anisotropic metamaterial which normal direction permeability is-1. By Maxwell’s simulation and the brassboard for use of WPT, get the magnetic field contrast figure and transmission effect comparison chart show that the EMMs can effectively improve the efficiency of magnetic coupling resonant WPT system.