Research On Parameter Estimation And Optimal Position Of Intermediate Coils Of Magnetic Coupled Resonant Wireless Power Transfer System

Due to the rise and popularity of electric vehicles and the rapid development of portable electronic products,the convenience and security of wireless energy transmission technology have made people’s requirements for wireless energy transmission technology more and more high.MCR-WPT(Magnetically Coupled Resonant Wireless Power Transfer,MCR-WPT)technology stands out among many wireless charging technologies.This technology has high transmission efficiency,small influence by non-magnetic obstacles,and small electromagnetic radiation to the human body.The transmission distance is long and can meet the needs of various occasions.Based on the above advantages,this technology has been widely studied and developed rapidly in recent years.In order to further improve the transmission power of MCRWPT system,based on the research of MCR-WPT system topology,two parameter estimation methods without communication are proposed,and the coil mutual inductance and load resistance are estimated respectively.In order to increase the transfer distance of the system and improve the transmission characteristics,the intermediate coils are added,and the method of optimal position of coil is given for the coaxial single and double intermediate coil MCR-WPT system,so that the transmission power of the system is maximized.The main work of the thesis is as follows:Firstly,the modules of the system are analyzed separately,and then for the four classic resonant compensation topologies(Series-Series,Series-Parallel,Parallel-Series,ParallelParallel).The calculation method of the compensation capacitance parameters and the transmission power expression are given.The Series-Series type structure is selected by comparison to facilitate the research.Finally,the equivalent model and calculation method of the planar spiral coil and the selection method of the compensation capacitor are given respectively.The parameters of the coil and capacitor used are measured by the network analyzer,and the correctness of the method is verified,which provides the experimental basis for the subsequent research.At present,the MCR-WPT system needs communication method to estimate the mutual inductance and the load parameters to ensure the transmission efficiency of the system.Based on this problem,this paper proposes two parameter estimation methods without communication,one is the offline estimation method,and the other is an online estimation method.According to the circuit topology,the physical quantities required by the two methods are obtained,the relationship between the parameters and the current and voltage harmonic components is constructed,and the parameter estimation method is given.The simulation models are established for the two methods.The two methods are verified by experiments.The simulation and experimental results verify the feasibility and effectiveness of the estimation method.When the transmission distance of the Series-Series wireless charging system increased,the transfer power becomes worse,which is not suitable for high-power and long-distance wireless power transfer.This paper proposes a system transmission power optimization method based on intermediate coil position adjustment.The topology of the intermediate coil system is analyzed and the transmission power of the system is solved.By studying the relationship between the position of the intermediate coil and the transmission power,the distance coefficient is introduced to simplify the power optimization process,making the power optimization method simpler.Finally,Through the simulation analysis and experiments verify the effectiveness and accuracy of the proposed method.