Research On Electromagnetic Environment Analysis And Control Method Of Wireless Power Transfer System Via Coupled Magnetic Resonances

As the world enters the 21 st century,the economy has been developing rapidly and the country is changing with each passing day.As the economic development leads to the increasingly depletion of fossil energy and the deterioration of the environment,people show great enthusiasm for clean and renewable energy.Electric energy as a clean and renewable energy has an indispensable unique advantage,and it is playing an increasingly important role in various industries and fields.In the field of transportation,countries have made many efforts to promote the development of electric vehicles,and new energy vehicles have gradually replaced fossil energy vehicles.In the consumer electronics industry,smart phones,computers,wearable devices and other devices have rapidly occupied every aspect of daily life in recent years,changing people's lifestyle.In the medical field,implantable medical electronic devices,such as cochlear implant,artificial heart and vision correction device,have gradually replaced portable medical devices and become a hot spot of medical research and development,and have been widely used in clinical practice.In the field of communications,broadcasting,global positioning systems,mobile phones,etc.,are making people's lives more convenient.The intelligent and interconnected world is more and more dependent on electric energy.People's daily life is gradually changing from fossil energy to electric energy,and electric energy is quietly changing the interaction between human beings and the world.However,for a long time,the way to use electric energy is always around the problems of "plug and pull","contact wear","discharge","spark","convenience" and so on.As a novel,non-contact,non-wear,convenient and beautiful charging method,wireless power transfer(WPT)technology has attracted extensive attention from academia and industry.At present,the technology has been widely used in all lifestyles,but the strong magnetic coupling characteristic of the technology itself is always the focus of attention.At the same time,with the complexity and diversity of WPT technology application scenarios,the presence of ferromagnetic metals and non-ferromagnetic metals in the scene itself.On the one hand,these materials will affect the electromagnetic environment around the system,on the other hand,it will change the performance of the system,and the system will not work in serious cases.At present in view of the different topologies of electromagnetic environment and system performance remains to be strengthen the study of coupling relationship,in the environment can guide magnetic conductance material of WPT system work parameters fluctuation influence still need further research,applicable situation and the influence mechanism of the electromagnetic control methods also remains to be further clarified.Aiming at the above problems,this dissertation starts from the analysis of the coupling relationship between the electromagnetic environment and the working performance of the system.The key influencing factors of electromagnetic environment and performance are explored.The parameter variation model of resonator coil with low and medium frequency magnetic field regulation method is established.The influence of substrate size on resonator parameters are analyzed.A novel electromagnetic metamaterial resonant pattern based on high frequency magnetic field regulation is proposed and introduced into medium and long distance WPT system.An efficient,reliable and safe resonator device for practical application is developed.This dissertation focuses on the coupling relationship between electromagnetic environment and working performance,the regulation method of medium and low frequency magnetic field,the regulation method of high frequency magnetic field,and the prototype design combined with the regulation method of magnetic field.The main contents include:(1)Research on coupling relationship between electromagnetic environment and performance of WPT system.The space electromagnetic environment calculation models of resonators based on square and circular plane coils are established.The calculation formulas of eight basic topologies considering the resistance of transceivers and receivers and the inductive resistance of hybrid topologies are derived.Taking self-developed coils and SAE WPT2/Z3 coils as examples,the performance of the system with the same resonator parameters and different topologies is studied.By defining the magnetic induction structure factor,the electromagnetic environment around the resonator is compared under the same working performance and different topologies.The sensitivity of different topological performance and electromagnetic environment to parameter changes is analyzed,and the key influencing factors are screened.(2)The calculation models of coil parameters loaded with non-ferromagnetic metal and ferrite substrate are established respectively,and the results are verified by comparison with the simulation and experiment.The equivalent resistance of the coil is studied when the thickness and area of the two materials change and the weight is constant,and the control scheme of the medium and low frequency magnetic field is proposed by combining the two different substrate materials.The changes of transmission performance and electromagnetic environment of the system are analyzed and optimized by experiments.(3)An electromagnetic metamaterial resonance pattern is proposed.Based on ANSYS finite element simulation software,a simulation model of electromagnetic metamaterial cell resonant pattern containing wave excitation ports is established.The equivalent electromagnetic parameters of the resonant pattern of the cell are obtained by S-parameter inversion method,and the magnetic field of negative permeability is controlled at 6.78 MHz.Combined with the medium and long distance wireless power supply system of transmission line sensors,it is verified that the power and efficiency of the above system can be improved by introducing the designed electromagnetic metamaterials.In order to ensure the stable and reliable power supply of medium and long distance wireless power supply system of transmission line sensor,the Class-E amplifier circuit with zero voltage switching state and the method of constant voltage power supply of secondary side are designed.(4)The resonator design process based on the magnetic field control method is proposed.Through the specification design of multi-resonator scheme,considering the evaluation and analysis of coil resistance and transmission performance,combined with the engineering package design,the electric vehicle WPT system is developed.In order to meet the wireless charging requirements of the smart grid inspection robot,a resonator scheme including secondary coils access identification is designed,and a complete wireless charging system of the inspection robot is developed.