Study Of The Metamaterial Enhanced Distant Wireless Power Transfer System

Wireless Power Transfer(WPT)has became a promising technology along with many astonishing breakthroughs made by researchers recently.However,if consider some of the most important properties which are required in practical application,i.e.safety for human body,distant transfer distance,large transfer efficiency,and insensitiveness to external load,we find it is usually hard for current WPT technologies to satisfy all these requirements simultaneously.On the other hand,over last decade,researchers has made great progress in the study of metamaterial,which is an artificial material that possessed many special properties,most of these properties cannot be presented by natural material.Moreover,metamaterial provided the physical foundation for transformation optics(TO).Based on TO,the construction of metamaterial can easily bind with the manipulation of the propagation of electromagnetic(EM)wave.As the WPT can be viewed as an EM radiation and scattering problem of current-carrying conductors,and after rigorous analysis we find it is possible to use metamaterial to improve the WPT systems.There are few methods or theories for analyzing the metamaterial-modified WPT system,some traditional theories or methods that established in the studies of WPT or metamaterial cannot be well applied in the interdisciplinary subject.Therefore,we analytically extend the scope of TO to metamaterial-modified WPT systems,and demonstrate that the extended TO can help design the highly efficient WPT.The methodology is based on rigorous scattering theory,enabling an equivalent model under certain circumstances to be established,that can significantly simplify investigating metamaterial-enhanced WPT.More important,from the analytical study on the equivalent model,we prove that TO is still applicable,even when the conditions of complementary media are not satisfied.Our findings are verified numerically using our methodology as well as COMSOL simulations(based on Finite Element Method(FEM)).Moreover,a further study also indicates the extended TO explanation as well as the analysis of the equivalent model could help improve the transfer efficiency of WPT significantly.Based on the abovementioned results,a model of superscatterer enhanced distant WPT device has designed and analyzed with the concept of extended TO.The numerical results obtained through a series expansion method reveal that a properly designed ss-WPT has high efficiency for long transfer distances as well as a wide transfer range.The transfer distance can be further enlarged by fine tuning of the design.These effects can be explained qualitatively through the study of magnetic flux.Futher analyzing also denotes that the value of the external load can be varied in a relatively wide range,among which the change of the value will not have a significant impact on the high efficiency and long transfer distance.Besides of the establishing of ss-WPT,we also provide an analytical framework for analyzing the mismatched case of Complementary media(CM)interacting with arbitrarily situated obstacles,which will be encountered in many metamaterial-modified WPT systems and CM-based illusion optics.The CM-based devices of a superlens and superscatterer are discussed,these two special metamaterials are also applied in many other area not only WPT systems.The cancellation mechanism of the mismatched CM is studied.In addition,numerical results are provided for illustration.Detailed analysis shows that optical cancellation effects relies on specific conditions.Specifically,we studied the mismatched CM with perfect electrical conductor(PEC)objects,and presented its equivalent models.In conclusion,based on the aforementioned results,we are able to analyze the metamaterial enhanced WPT by applying the extended TO and multiple scattering theory,at the same time we can understand the effects made by surrounding objects near the WPT systems through analyzing its mismatched CM-based systems.More important,we give a promising WPT system,the ss-WPT,which might be a better approach for establishing safer WPT that has long transfer distance large transfer range and is less sensitive to external load.The approach from multiple scattering theory has revealed some special properties,however there are still many other unkown properties remained to be discovered and explained in metamaterial enhanced WPT.