Research On High Efficiency Magnetic Coupled Resonant Wireless Energy Transfer Technology Based On Electromagnetic Metamaterials

At present,most of the charging methods in life are wired charging.While wired charging is widely used,it also has some disadvantages,such as complex lines and easy aging wires.In order to find a safer and more convenient way to charge,wireless power transfer technology has emerged.Wireless power transfer gets rid of the control of wires,improves the safety of charging,and also makes charging more flexible.It is widely used in the power supply of special equipment and some smart products.Tesla was the first to put forward the concept of wireless charging.Since then,more and more researchers have devoted themselves to wireless charging technology,making it a hot research field in the world at present.Among them,magnetic coupling resonant wireless power transfer,as a new wireless energy transmission mode,makes use of the high intensity electromagnetic coupling near the field,through resonant at the same frequency of the transmitting and receiving coil to achieve effective and safe transmission of electric energy.Because it can realize medium and long distance,high power and high efficiency power transmission,it has far-reaching research value.But so far,there are still many technical bottlenecks to be solved.For example,magnetically coupled resonant wireless power transfer technology uses air as the medium to carry out energy transmission by means of electromagnetic field coupling.Due to the limitation of the coil topological structure,the coupling degree between the coils is low in the long-distance transmission,which leads to the low transmission efficiency and poor stability of the system.In addition,magnetic coupling resonant wireless power transmission technology uses near-field energy transmission,which has high electromagnetic intensity.Once leakage occurs,it will pose a threat to human health and the normal work of other electronic equipment.In terms of application,the magnetic resonance wireless power transfer mode can be used for the power supply of implantable electronic devices in biomedicine,but the energy transfer efficiency is low due to the high dielectric loss of organisms.This thesis mainly conducts in-depth research on how to improve magnetic field coupling and how to shield magnetic field leakage.The following aspects are mainly studied:1.Research on the improvement of system power transfer effect by means of relay coil and metasurface.The transmission effect of magnetic resonance wireless energy transmission is more sensitive to the change of distance.Once the distance exceeds the critical coupling distance,the efficiency will drop rapidly.In recent years,with the deepening of research,relay coils and metasurfaces have become effective means to enhance magnetic field coupling.This article first studies the effect of the relay coil on the enhancement of magnetic field coupling,and quantitatively analyzes the influence of the position of the relay coil on the transmission performance.At the same time,the focusing metasurface with negative magnetic permeability is also an effective means to improve the coupling effect.The focusing metamaterial can effectively focus and control the magnetic field to greatly increase the coupling magnetic field density of the receiving coil and increase the electromagnetic energy received by the load.Based on the analysis of its working principle,this paper has gradually gone through the steps of analyzing the working principle,carrying out electromagnetic simulation,and doing actual experimental verification.It is proposed that the focusing metasurface with negative magnetic permeability can be used in the wireless power transfer system.So as to improve the transmission efficiency of the magnetic resonance wireless power transmission system.2.Research on the shielding effect of metasurfaces on magnetic fields.Magnetic coupling resonant wireless power transfer technology uses near-field energy transfer,and its high field strength characteristics cause serious electromagnetic leakage of energy during the transmission process,which poses potential threats to the human body and electronic equipment.This paper analyzes the working principle of a shielded metamaterial with zero magnetic permeability.When the incident wave is incident on the surface of the metamaterial,the electromagnetic wave transmission coefficient is approximately zero,which means that when the magnetic field is incident obliquely,it will be reflected and absorbed by the metamaterial.Instead of transmitting the past,this clarifies the shielding effect of metamaterials,and theoretically proves that metamaterials can improve the interference of magnetic field leakage on humans and the environment.Finally,it is verified by simulation that when the near-zero magnetic permeability metamaterial is placed in the transmitting and receiving coil,because it blocks the propagation of the magnetic field,the magnetic field of the receiving coil is greatly weakened,which verifies the shielding effect of the near-zero magnetic metamaterial.3.Research on high-efficiency magnetic resonance wireless power transmission technology for biomedical applications.At present,magnetic resonance wireless power transfer is also used in power supply for implanted devices in biomedicine.In this paper,a dual-band ultrawideband miniaturized receiving antenna and an external transmitting coil working at430 MHz are designed to build a wireless power transfer system that works in a human implanted environment.After the feasibility of the whole system was verified by simulation,the actual measurement was carried out,and the actual measurement results are basically consistent with the simulation results.Finally,a metasurface array with negative magnetic permeability with 2×2 units working at 430 MHz was designed,and reasonable adjustments were made.The loading position of the metasurface array can significantly improve the efficiency of the entire wireless power transfer system.