Research On Shielding Technology Of Wireless Power Transfer System With Proximity Coupling

Wireless power transfer technology has developed rapidly,and has been widely used in electric vehicles,large-scale internet of things,and biomedical equipment,its application scenarios have become increasingly complex and diverse.In the practical application,multiple wireless power transfer systems which are close in distance,can work simultaneously as a normal application scenario.However,proximity coupling caused by mutual coupling of leakage magnetic field from adjacent systems will affect the surrounding biological electromagnetic environment and bring disturbances to resonant parameters.These parameter fluctuations will reduce the system transmission efficiency and system working stability.Therefore,it is urgent to design high-efficiency and low-cost magnetic shielding method to adapt to the further expansion of wireless power transfer application scenarios.According to the research background and significance,this paper introduces the harm of leakage magnetic field between wireless power transfer systems,the research status on the shielding of leakage magnetic field between wireless power transfer systems by scholars at home and abroad is reviewed.Then,the research significance and direction of this topic are expounded by analyzing and summarizing the shortcomings of the existing research.Based on the theory of magnetically-coupled resonant wireless power transfer technology,a resonant shielding mechanism suitable for multi wireless power transfer systems is proposed.The shielding mechanism using the leakage magnetic field itself as a power source,and the induced magnetic field which is opposite to the direction of the leakage magnetic field can be generated by adjusting the parameters.Therefore,the shielding mechanism can cancel the leakage magnetic field and eliminate the proximity coupling between systems.Then,the influence of the shielding mechanism on the wireless power transfer system parameters is studied.Expressions of transmission efficiency,difference of frequency-splitting and mutual inductance between coils are derived.Theoretical research shows that the shielding mechanism can effectively weaken the proximity coupling,inhibit the frequency-splitting,and improve the transmission efficiency of wireless power transfer systems.The wireless power transfer system model is built in the simulation software subsequently,and the parameters of wireless power transfer systems and the shielding mechanism are set according to the theoretical research.At the same time,the optimization method and process of the shielding mechanism are proposed by use the mutual inductance between coils in different systems as a reference quantity.Finally,experiment platform is set up.The selection of high frequency power supplies and the manufacture of wireless power transfer systems are completed.According to the parameters of different optimization schemes in the simulation model,the corresponding shielding mechanism is made.The effects of the shielding mechanism on transmission efficiency of wireless power transfer systems,mutual inductance and coupling coefficient between coils under different optimization schemes were tested.The experimental result shows that the shielding mechanism proposed in this paper can improve the transmission efficiency of the wireless power transfer system by up to 17.4%,and the coupling coefficient between different system coils can be reduced by up to 46.7%.The shielding mechanism with square close wound structure has the best performance.The effectiveness of the proposed shielding mechanism and its optimization method is verified.