Research On Wireless Power Transfer System With High Misalignment Tolerance Based On PT Symmetry

Wireless Power Transfer(WPT)technology can help electrical equipment get rid of the shackles of charging cables and improve charging flexibility.However,most of the traditional researches are based on Magnetically Coupled Resonant(MCR)technology and a single transmitting coil,which have the defects of small offset transmission range and high sensitivity of coupling coefficient.This problem greatly restricts the improvement of the misalignment transmission capability of the WPT system,and is an urgent problem to be solved at present.To this end,combined with the current research situation,this paper focuses on improving the offset transmission range and enhancing system transmission stability,and explores three aspects of dual-load WPT transmission technology,distributed coupler design,and flexible configuration methods for charging areas.And the actual effect is verified by building a prototype.1)For the high sensitivity of the coupling coefficient of the traditional MCR technology,which is not suitable for misaligned transmission systems,the research on the dual-load WPT system based on the parity-time(Parity-time,PT)symmetry theory is introduced.Two modeling methods are adopted,namely coupled mode theory explained from the perspective of energy and circuit theory explained from the perspective of impedance.The load energy distribution characteristics,frequency characteristics,gain characteristics,output power and efficiency of the three-harmonic oscillator system are explored,and a preliminary theoretical verification is carried out in combination with the MATLAB/Simulink simulation system.It is found that in the strong coupling region,the total transmitted power and efficiency of the system remain constant regardless of the adjustment of the coupling coefficient of the dual-load coils.2)Aiming at the problem of unstable coupling performance when the coupler is offset,the design and optimization of distributed couplers with quasi-uniform coupling characteristics are studied.Aiming at the problem of unstable coupling performance when the coupler is offset,the design and optimization of distributed couplers with quasi-uniform coupling characteristics are studied.First,a scalable transmitting unit and receiving coil structure are proposed,and a fast calculation model of mutual inductance under misalignment conditions is derived as the basis for an efficient optimization algorithm.Secondly,using the prior knowledge of the relationship between coil parameters and coupling performance,a step-by-step multi-objective optimization algorithm is designed to obtain the optimal coupler design parameters and improve the optimization efficiency.Finally,the performance of the proposed coupler is preliminarily verified in finite element software Ansys.3)Aiming at the problem of magnetic flux leakage and charging flexibility limitation in the current distributed coupler with a fixed number of units activated or without control activation,the research on the diversified configuration method of the charging area of the proposed system is carried out.Based on the characteristics of the PT system,a load coil position detection method that only needs to measure the operating frequency of the primary side is designed.And based on this,a multi-units combination activation strategy supporting dual loads is proposed,which achieves a balance between the charging area and unnecessary electromagnetic radiation.The topology of modular resonance compensation is analyzed and designed to solve the problem of frequency mismatch caused by cross-coupling between transmitting units.4)Prototype construction and experimental verification were carried out.According to the design parameters of the coupler,the experimental coil was fabricated.Combined with the principle of the PT system,the implementation method of the nonlinear negative resistance of the self-resonance controlled full-bridge inverter is described,and the key circuit design is analyzed.The experimental results of the prototype show that when the independent unit and the adjacent double units work,the uniform coupling allowable offset of 12 cm and 37 cm can be provided respectively,and the misalignment transmission ratio reaches 1.2 and 3.7.When working with dual loads,the generalized allowable offset ranges of the PT system are expanded to 23 cm and 45 cm respectively.In addition,when the dual-load coil coupling coefficient is adjusted within a certain range,the prototype maintains a constant 42 W total power output,and the efficiency is not lower than 80%.The experimental results verify the effectiveness of the proposed distributed anti-offset coupler design method,and reflect the practicability of PT technology in solving the problem of output interference caused by uneven coupling coefficients in offset transmission systems.