Research On Transmission Characteristics In Magnetically Coupled Resonant Wireless Power Transfer System

As the massive use of fossil energy has caused serious pollution to the environment,now people are more and more inclined to use clean energy.In the field of urban transportation,electric vehicles have been vigorously promoted in urban transportation due to their advantages of using clean energy and low energy consumption and low pollution.In view of the charging problem of electric vehicles,the traditional wired charging is prone to leakage of electricity and the generation of plug sparks in the humid dust and other bad environment.Compared with wired charging,wireless charging has the advantages of convenience,flexibility and high security.Compared with other radio energy transmission methods,magnetic coupling resonant wireless power transfer has the advantages of longer transmission distance,higher transmission efficiency and lower radiation.In recent years,magnetic coupling resonant wireless power transfer has attracted extensive attention and research from all circles.In this paper,a series of studies on the transmission characteristics of magnetically coupled resonant radio energy transmission system are carried out By calculating and analyzing the factors affecting the transmission performance of the system,a simulation model is established for verification,and the optimization design is carried out to improve the output power and transmission efficiency of the system.The main research work of this paper is as follows:(1)The basic working principle of magnetically coupled resonant radio energy transmission system is studied,and the system is modeled and analyzed respectively based on coupled mode theory and equivalent circuit theory.(2)The influence of coil mutual inductance and equivalent load on the transmission characteristics of the system is analyzed,and the phenomenon of frequency splitting and its causes are analyzed.When frequency splitting occurs in the output power of the system,impedance matching circuit can be added to the load to increase the equivalent load and suppress the frequency splitting phenomenon.(3)The inductance and mutual inductance parameters of the coupling coil are calculated and the structure of the coupling coil is designed.The system detuning problem caused by the change of the coupling coil position is calculated and analyzed by electromagnetic simulation.It is analyzed that the coupling coefficient between coils can be greatly increased by adding magnetic core structure to the coupling coils,which can effectively offset the effect of coil offset on the coupling coefficient.(4)The wireless charging system model of electric vehicle was established based on MATLAB.The transmission efficiency of the system can reach 86.4% by using the calculated and designed coil parameters.It is verified that the design of coil and system scheme can meet the demand of electric vehicle wireless charging.