The Wireless Power Transfer System Based On The Printed Sprial Coils

Recently,wireless power transfer technology has been developed significantly.The re-search of this technology is in its infancy and many theoretical and experimental studies are still lacking,and the related theoretical research is not perfect enough.In this paper,the coils on printed circuit boards(PCB)are studied at first and a complete design process is estab-lished.The feasibility of the wireless power transfer system based on printed spiral coils(PSCs)is verified from the aspects of system modeling,performance optimization,circuit simulation and experiment results.As an important part of the wireless power transfer system,the receiving and transmit-ting coil is an important part of the wireless power transfer system.Its performance directly determines the key factors,such as the transmission efficiency and power transmission ca-pacity of the whole system.Firstly,the resonant coil is designed based on the printed circuit board.In order to enhance the magnetic field strength between coils,a series printed spiral coil structure for resonant wireless power transfer system is proposed.The series coil can sig-nificantly enhance its inductance and mutual inductance strength to meet the requirements of system for transmission power and transmission distance.Considering that it is difficult to modify the parameters of the printed spiral coil,it is particularly important to determine the inductance parameters of the coil in advance.For this reason,a set of methods for calculating the inductance of coils are studied in this paper,and the reliability of the method is verified by comparing with the simulation results of finite element simulation model and the actual coil measurement results,and this method can provide a reference for the system design.In order to extend the transmission distance,this paper focuses on the research of three-coil wireless power transfer system,and it analyses and compares the existing common modeling methods of the wireless energy system,proposing a new equivalent model deriving from traditional T-type equivalent model of two-coil systemBased on the input-output model of three-coil system circuit,which is deduced from the system basic equations,it can accurately reflect the relationship between input and output of the system and can be used as a reference for design.Based on this model,the harmonic problem in the input current of three-coil system can also be studied.The system performance may be decreased because of the harmonic problems.As for the transmission efficiency,the three-coil system is not superior to traditional system all the time.By contrast,if the system design is inappropriate,the transmission effi-ciency of the three-coil system may be worse.Therefore,in order to ensure that the transmis-sion efficiency of the three-coil system is better than that of the traditional two-coil system,a set of system design criteria is proposed in this paper.The system design based on this crite-rion can ensure that the efficiency of the three-coil system is better than that of the two-coil system.In addition,the relationship between system efficiency and system parameters is also studied,and the validity of three-coil wireless power transfer system based on printed helical coil is demonstrated.Finally,the GaN device is used to design the converter for the system,and the experi-ment device is built based on the FPGA.The experiment results verify that the wireless power transmission system based on PSCs designed in this paper can be applied in wireless transmission field.The simulation and experiment results further verify the correctness of the proposed model and theoretical analysis.