| The traditional cable power transfer mode of electric vehicle has some disadvantages,such as personal safety problems caused by the wear and aging of charger devices,and the charging process cannot be operated automatically.Wireless Power Transfer(WPT)as an ideal power supply mode,has the advantages of security,convenience and unity,and can meet the needs of the future development of intelligence cars and intelligence power grid.This paper focuses on improving the stability of wireless power transfer system.The output characteristics of series-series resonant topology are analyzed by using circuit coupling theory.The duty cycle D of the SEPIC circuit is adjusted by the perturbation and observation(P&O)algorithm to realize the maximum power point tracking(MPPT)of the system.The topology of double-sided LCC is proposed and the structural parameters of the system are optimized by particle swarm optimization.Finally,MATLAB simulation software is used to analyze the transmission characteristics of the system.The main work of this paper includes the following points.Firstly,this paper introduces the four basic resonant topologies of the two-coil WPT system.In order to decrease the influence of load impedance on system charging performance,the series-series topology is selected for research,and its output characteristics are studied by using circuit coupling theory.The coupling coefficient variation on the output power and efficiency of the system curves are obtained by MATLAB simulation software.Secondly,the equivalent circuit design of the series-series WPT system is studied out.The power output characteristics of the system are analyzed by simplifying the circuit structure,and the maximum power point of the system is found.The SEPIC circuit is introduced to cascade at the receiving side to realize the constant current output of the system under the same input voltage.The duty cycle D of the SEPIC circuit is adjusted by the P&O algorithm based on the MPPT to achieve the maximum power point tracking of the system.The closed-loop control strategy with MPPT is verified to reduce the sensitivity of transmission power to varying spatial scales by MATLAB software.Thirdly,based on the series-series topology,the double-sided LCC topology is introduced,and its constant current output characteristic is analyzed and studied.The parameters of the double-sided LCC topology are optimized from the aspects of improving the system performance and reducing the power consumption,and the particle swarm optimization algorithm is proposed to optimize the system structure parameters,so as to achieve the purpose of improving the system transmission performance.The conclusion that the output power of the load increases with the optimization process is obtained by MATLAB software simulation,and then the correctness of the theoretical analysis is verified.Finally,the whole circuit of the WPT system of electric vehicle is designed and studied.The functions of each module of the system are analyzed and the advantages and disadvantages of each circuit are compared.The single-phase bridge rectifier filter circuit,the series adjustable voltage stabilizing circuit,the full bridge high frequency inverter circuit,the SEPIC circuit are selected as the transmission circuit of the static constant current output WPT system.The circuit model is built by Simulink software,and the simulation results agree with the output characteristics of main circuit. |
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