Design And Research On Resonant Coils Of A Three-Coil-Structure For Wireless Power Transmission System

Compared with wired charging technology,the technology of wireless power transfer?WPT?is promising and has the advantages of safe operation,smart charging,and flexible configuration.Therefore,it is widely used in industrial automation,mobile phones and electric vehicle industries.The improvement of power transmission efficiency of WPT technology has always been a major challenge in the field of wireless energy transmission.In this paper,the transmission efficiency of a wireless energy transmission system is studied and demonstrated from the perspective of the coil body?coil parameters?and the coil resonance structure?spatial structure?.Firstly,the system structure and working mechanism of the wireless energy transmission technology are analyzed,and the simulation models of the wireless energy transmission system are established by employing the two simulation softwares of both Matlab and Magnet in this paper.Based on the theory and simulation,the hardware platform is built,and the circuit module and electrical material selection are analyzed and introduced,which provides an experimental platform for following research work of the coil and resonant structure.Secondly,using the simulation software of Magnet,the basic parameters of the coil,such as material,wire diameter,turn spacing of coil,outer radius of the coil and quality factor,are simulated and experimentally verified,and the optimal selection of each coil parameter is obtained.Based on the research of coil parameters,a coil parameter S which can measure the transmission efficiency of the coil is proposed.Through theoretical analysis,the optimized parameters S₁ and S₂ of the transmitting coil and the receiving coil are compared.The results show that the larger the coil optimization parameters S₁ and S₂ are,the higher the system power transmission efficiency is.In the further study of the theory,it is found that the transmission distance that maximizes the transmission efficiency between the transmitting coil and the receiving coil is related to the size of the outer radius of the transmitting coil,regardless of the outer radius of the receiving coil.The experimental results are consistent in the theoretical derivation.Finally,a spatial and three-coil structure is employed to analyze the transmission efficiency of the system from the perspective of the resonant structure of the coil.The transmission efficiency of the resonant coils with both two-coil structure and three-coil structure are analyzed and compared by using the circuit theory.The experimental results show that the transmission efficiency of the three-coil structure can reach 81%at a transmission distance of 14cm,which is 1.9 times than that of the two-coil structure;As for a transmission distance of 18cm,the transmission efficiency of the three-coil structure can reach 60.3%,which is 2.7 times than that of the two-coil structure;As for a transmission distance of 22cm,the system efficiency of the three-coil structure can reach 32%,which is 4.7 times that of the two-coil structure.The experiment verifies the correctness of the theoretical analysis.In this paper,the research on the wireless energy transmission coil and the resonant structure can effectively improve the power transmission efficiency between the coils,and provide a basis for the later research and production application of the wireless power transmission efficiency.