Research On Magnetically Coupled Resonance Wireless Power Transfer System Based On Stacked Coils

The magnetic resonant wireless power transfer technology is widely used due to its high transfer efficiency,long transfer distance and no radiation to living organisms.The magnetic resonant wireless power transfer technology in implanted medical system provides safe,reliable and comfortable medical services for human beings so that it has a good industry prospect.Coupling coil as the core part of wireless power transfer system,and its coupling performance directly affects the transfer efficiency and load power of the system.In implanted applications,there is a large difference in the physical size of the primary and secondary coils due to the small size of the implanted part,resulting in low transfer efficiency and the shallow implant depth.Therefore,this thesis studies a high-quality factor,strongly coupled coil structure for solving the problems such as the small size of secondary coils and the poor performance in implanted medical system,aiming to improve a high transfer efficiency and the depth of implantation.This thesis carries out the research by combining theoretical analysis,simulation and experimental verification,and the main research work of this thesis includes:Firstly,according to the circuit theory,the transfer efficiency and output power of the series-series resonant magnetic coupling system are deduced,and the relationship between transfer efficiency and coil’s quality factor and coupling coefficient are analyzed,also the effects of load,operating frequency and coupling coefficient on system performance are discussed.In order to increase the load flow of the coil,a multi-layer stacked coil structure is proposed based on the PCB plane spiral coil,while the equivalent circuit model of a multi-layer stacked coil is established.The relationship between the electrical characteristics of coils and structural parameters are analyzed,which provides a theoretical basis for the design and optimization of coil structure.Secondly,the high efficiency wireless power transfer system is constructed based on multilayer stacked coil.The coupling coils are simulated and optimized by HFSS finite element simulation software,through building simulation circuit with optimized coil parameters,studying the effect of operating frequency and load on the transfer efficiency of the system.In this process,the coil design method of magnetic coupled resonant system is summarized,and the construction method of the optimal coupling system is proposed.Finally,in order to verify the correctness of the research work,this thesis build the experimental platform of the magnetic coupled resonant system to verify the performance of the system by using the designed coupling coil in the laboratory.The experimental data and simulation analysis are well matched,which shows the correctness of the work of this thesis;and in order to verify the validity of the research work,the thesis also carried out the comparative test of the designed system and the wireless power transfer system of the plane spiral coil as a coupling element under the same volume constraint.The experimental results show that under the same conditions as the system parameter configuration and the receiving coil volume,the coupling efficiency of the receiving coil with the stacked structure can be improved 23.9% and the transfer efficiency can be improved by 19.56%.This illustrates the effectiveness of the work in this thesis.