Magnetic Field Analysis And Optimization Design Of Wireless Power Transfer System Based On Metamaterials

Magnetic resonant coupling wireless power transfer（MRC-WPT）and near-field metamaterials are among the frontier technologies in the 21^st century,which show significant potential for development and application in both scientific and industrial communities.These technologies are effective solutions for powering devices with the advantages of high efficiency,stability,and safety.In view of the problems of poor space capability,low transmission efficiency,and electromagnetic leakage of MRC-WPT systems,this paper starts from the deep research on the control mechanism of magnetic couplers and near-field metamaterials.The main contents are as follows:（1）Aiming at the problem that the current multidirectional MRC-WPT system only charges the devices of a single frequency,a dual-band multidirectional MRC-WPT system is designed.The equivalent circuit model of the proposed dual-band multidirectional MRC-WPT system is constructed.Furthermore,the expression for the transmission efficiency of the system is derived.The physical and electrical parameters of the magnetic coupler are designed by the numerical analysis method and optimization algorithm.And,the system efficiency is 61.6%at 13.56 MHz and it is 65.4%at 27.12 MHz when the receivers are rotated around the transmitter.（2）To solve the problem of low efficiency and high leakage magnetic field of the dual-band MRC-WPT system,the dual-band mu-negative（DB-MNG）and mu-near-zero（DB-MNZ）near-field metamaterials are introduced.And the magnetic responses of the designed near-field metamaterials are characterized by the retrieved effective permeability.The efficiency and magnetic field distribution with the two near-field metamaterials are analyzed.When the MRC-WPT system is combined with the DB-MNG and DB-MNZ near-field metamaterials,the results show that the efficiency is enhanced and the leakage magnetic field is reduced at different frequency systems.（3）Due to the incomplete research on the magnetic field control outside the charging region of the MRC-WPT system,the side-placed mu-negative（MNG）and mu-near-zero（MNZ）near-field metamaterials in the MRC-WPT system are proposed.The relationship between the effective permeability and the structural parameters of the near-field metamaterial is clarified.The effects of different combinations of MNG and MNZ near-field metamaterials on the system efficiency and leakage magnetic fields are analyzed by simulation and experiment.The system with two MNZ slabs,and the combination of one MNG slab and one MNZ slab both can restrict the outside leakage magnetic field,and the high efficiency is acquired at the distance below 40 cm and above40 cm,respectively.（4）Aiming at the problem of leakage magnetic field in high-power MRC-WPT systems,a model of matrix metamaterial shield slab（M-MTMSS）is established.The equivalent circuit model is built by considering the integration system.And the influence of M-MTMSS on the efficiency and magnetic field of the system is evaluated.Besides,the physical structure of the M-MTMSS is determined by a multi-objective optimization algorithm,where the optimization objectives are the maximum efficiency and minimum leakage field.The simulation and experiment results demonstrated that the M-MTMSS can effectively reduce the leakage magnetic field at the fundamental wave of 85 kHz and the harmonic wave of 255 kHz,while the system efficiency remains above 87.29%.This paper focuses on the study of magnetic optimization,it proposes dual-band multidirectional magnetic couplers and near-field metamaterials.These methods can solve the problem of limited freedom and incompatibility when charging devices with different frequencies,and improve the efficiency and electromagnetic safety of MRC-WPT systems.These research results will improve the overall performance of the MRC-WPT system and promote the further application and development of these two technologies.