Research And Application Of Reconfigurable Metamaterials In Magnetic Resonance-Coupled Wireless Power Transfer

With the rapid development of science and technology,the application of electronic equipment is almost ubiquitous in our works and lives.However,traditional energy supply methods can no longer fully satisfy production and life due to aging wires,intricate wiring,and safety hazards caused by plugging and unplugging sparks.According to the needs,magnetic resonance-coupled wireless power transfer（MRCWPT）has good deflection resistance and is relatively friendly to the surrounding environment and the human body.It can solve the mid-range non-contact energy transmission obvious superiority.When the transmitter and the receiver generate the same frequency,and the maximum energy is coupled from the transmitter to the receiver.However,as the transmission distance increases,the MRC-WPT technology still exhibits exponential decay of the magnetic field because the system is in a detuned state,which significantly affects the application of wireless power transfer.In order to solve this problem,the evanescent wave amplification effect of metamaterials can effectively enhance the transmission efficiency of the WPT system.However,the single-frequency point metamaterials can only satisfy the single-frequency MRC-WPT system.As result,when the distance increases,the system will still be under-coupled,where the transmission efficiency still decreases accordingly.In order to solve those problems,this paper uses different via adjustment methods to design two reconfigurrable metamaterials,single-slab three-frequencies metamaterials and dual-slabs threefrequencies metamaterials,which are not only suitable for different frequencies of the MRC-WPT system,but also improve the transmission efficiency,by adjusting the frequency response of the metamaterial,The system continues to resonate over an extensive distance range,and the transmission efficiency of MRC-WPT is greatly increased.The single-slab triple-frequency metamaterial adopts a double-sided spiral structure.By controlling the positions of the via holes at the ends of the printed copper wires on both sides of the substrate,the structure of the metamaterial changes and its response frequency changes,realizing that the metamaterial is at 15 MHz-35 MHz Multi-frequency response in the low MHz band.According to the triple-frequencies responses of the metamaterial,in the series compensation system,the series compensation capacitance of the transmitting end and the receiving end is adjusted.The triple-frequency metamaterial selects different frequency responses at different distances of the resonance system to achieve the maximum transmission of energy.The application of triple-frequency metamaterials to the MRC-WPT system has been studied through simulation and experimental methods.The results show that the transmission efficiency of the system based on triple-frequency metamaterials is stabilized above 60% within a certain distance,which improve by 37% than that of system based on single-frequency metamaterials.Aiming at the problem that metamaterials and transmission distance affect the system’s resonance frequency in wireless power transfer systems,this paper uses frequency tracking to determine the frequency change of the wireless power transfer system with metamaterials,so as to further improve the reconfigurable metamaterial the transmission efficiency of the wireless power transfer system.Noting that the frequency splitting will occure at short distance because of the single-slab triple-frequency metamaterials with higher applicable frequencies,which will lead to instability.A double-slabs triple-spiral triple-frequency metamaterial is designed,which is composed of a three-sided spiral copper wire and two substrates to form a sandwich-like structure.The metamaterial is changed by controlling the depth of the via hole.The structure,thus obtains the three frequency response in the 10 MHz-25 MHz frequency range.This paper analyzes the triple-frequency response of the triple-frequency metamaterial with via adjustment depth in the single-coil series compensation circuit through data simulation.As a relay,the system maintains a nearly constant transmission efficiency of more than 60% through frequency selection.Aiming at the problem of metamaterials and transmission distance affecting the system’s resonance frequency in the wireless energy transmission system,this paper uses frequency tracking to determine the frequency change of the wireless energy transmission system added to the metamaterial,so as to further integrate the multifrequency metamaterial wireless energy transmission system The efficiency is increased to 65%.The structure of reconfigurable metamaterial is simple,which avoids the complexity of installing lumped components and the resulting lumped loss.It is not only suitable for MRC-WPT systems with different frequencies,but also increased by tuning the frequency in the same system.The corresponding resonance frequency of the MRC-WPT system at different distances can be adjust by selecting the lowfrequency response at short distances and the high-frequency response at long distances to achieve high efficient and stable transmission efficiency.The multi-frequency characteristics of metamaterials can effectively increase the application frequency of the system,and the transmission efficiency of the system can be optimized within a certain distance by selecting the resonance frequency.