Design And Beam Regulation Of Wireless Power Transfer Based On Metasurface

With the rapid development of electronic information technology,wireless power transfer has received widespread attention in recent years.Wireless power transfer technology has been widely used in smart terminals,electric vehicles and other fields,and we have gradually put forward higher requirements for the transmission distance and transmission efficiency of wireless power transfer.For medium and long distance microwave power transfer system,specific beam mode will be used for power transfer,among which directional high-gain beam and near-field focused beam are commonly used.Near-field focused beam can concentrate the electromagnetic power at the designated position,and can obtain higher transmission efficiency in a small receiving aperture.It has been widely used in point-topoint wireless power transfer system.Bessel beam has great potential in the field of wireless power transfer due to its characteristics of concentrated beam power and small beam divergence effect.Metasurface is a kind of artificially designed structures to realize special electromagnetic function.Through reasonable design,the characteristics of polarization,amplitude and phase of electromagnetic wave can be adjusted flexibly.Its development also provides a more convenient and flexible method for the design of wireless power transfer system.In this thesis,the research content is based on the transmit metasurface,and in-depth study of efficient wireless power transfer based on near-field focusing.By analyzing the parameters of the feed horn antenna and combining the focal diameter ratio to optimize the focusing transmission efficiency on a specified aperture.In addition,we combined the designed receiving metasurface to carry out wireless power transfer experiments in an indoor environment.Aiming at the multi-target wireless power transfer system,the zero-order Bezier beam’s non-diffraction characteristics are analyzed and studied,and the multi-target wireless power transfer system on the one path is constructed by using the characteristics of its large focal depth and beam power concentration.Finally,the beam transmission characteristics of directional beam,near-field focused beam and zero-order Bessel beam are compared,and designed and analyzed a miniaturized receiving metasurface.The specific research contents of this thesis include the following aspects:1.Research and design of a near-field focusing high-efficiency wireless power transfer system based on the transmit electromagnetic metasurface.We analyzed and optimized the design of the single-focus transmission focusing electromagnetic metasurface.For the focused wireless power transfer of different receiving apertures,we analyzed a transmit metasurface element and studied the aperture illumination efficiency and aperture utilization rate of the feed illuminating the metasurface.And according to the required receiving aperture analysis and selection of the appropriate feed horn antenna parameters and focaldiameter ratio,so that the highest transmission efficiency can be obtained under the current receiving aperture.We also analyzed the power transfer of the near-field focused beam under the occlusion of the medium.A transmit electromagnetic metasurface with an aperture of450mm×450mm and working at 10 GHz was processed.An efficient focused wireless power transfer system was constructed in the experiment.It is also shown that the transmission efficiency of the focused beam can be improved to a certain extent by selecting the feedhorn parameters and focal diameter ratio according to the receiving aperture.2.Research and design of multi-objective wireless power transfer based on the zero-order Bessel beam of the transmissive electromagnetic metasurface.For the multi-objective transfer system on the one path,the Bessel beam is designed with the characteristics of long focal depth and beam power concentration.This thesis proposes a two area change the zero order Bessel beam conic half angle design methods,this method can make the beam power distribution more uniform in the transmission path,at the same time,analyze the energy transmission of the zero-order Bessel beam under different receiving apertures,different receiving distances,different receiving positions,different beam transmission distances and the power transfer under different receiving positions.A 360mm×360mm transmissive electromagnetic metasurface working at 10 GHz was processed.Power transfer experiment carried out in a multi-objective receiving microwave anechoic chamber.The experiments show that under the appropriate receiving aperture and receiving distance,multiple receiving objective placed on the transmission path of the Bessel beam can obtain almost the same transmission efficiency.3.Comparative study on the transmission characteristics of directional beam,near-field focused beam and zero-order Bessel beam.For commonly used three kinds beam in wireless power transfer: directional high-gain beam,the near-field focusing beam and zero order Bessel beam,and the simulation contrast of near-field beam electric field distribution,the far field pattern and in receiving the power transmission condition of objective,analysis the transmission properties of three kinds of beam and its suitable for the application of wireless power transfer scenario.4.Research and design of miniaturization and high-efficiency receiving electromagnetic metasurface.Aiming at the miniaturized and high-efficiency receiving metasurface required by the wireless power transfer system for small-aperture reception,a miniaturized receiving metasurface with a working frequency of 10 GHz and an aperture of 25mm×25mm was designed,and its surface electric field and current distribution were simulated and analyzed.