Research On Radio Energy Transmission Of Electric Vehicle Based On Optimization Of Impedance Matching Efficiency

With the continuous development of electric vehicle technology,the core technology,charging technology,has also attracted much attention and become a research hotspot.Under the promotion of continuous progress of science and technology,the charging mode of electric vehicles is no longer limited to the traditional wired charging.Wireless power transmission(WPT),a new technology direction,has also been improved and realized.In order to improve the transmission power of WPT,this thesis studies the impedance matching method and the Resonance compensation structureFirstly,DC-DC converter is used to realize impedance matching,and the optimal efficiency point of the system is maintained by adjusting duty cycle to achieve efficiency optimization.Based on the modules and characteristics of lithium battery,the impedance matching method and its related control strategy are analyzed.In order to achieve the maximum transmission efficiency,DC-DC converter is used to achieve impedance matching.For different DC-DC converters,through correlation analysis,appropriate structure is selected to facilitate wide range adjustment,On this basis,adjust the duty cycle is determined to achieve efficiency optimization,so that the system can maintain at the relative best efficiency point.The control method of double closed-loop PI is proposed to complete the regulation and control the whole system.Secondly,LCC-S-DC-DC charging system is designed.This thesis mainly focuses on the power transmission mode of magnetic coupling resonance type,especially in the design of resonance topology.This thesis analyzes the most representative S-S resonance compensation structure in the traditional topology,on this basis expounds the defects and introduces the transmission system of LCC-S structure.In order to realize the efficiency optimization of impedance matching network and improved performance of LCC-S topology,the analysis and research of the new LCC-S-DC-DC system are carried out from two aspects of theory and simulation.The equivalent circuit method is used to analyze the theoretical basis of its topology network,and then the MATLAB simulation is used to analyze its output characteristics,load and coupling coefficient.At last the feasibility of the impedance matching method is verified by MATLAB,which can optimize the efficiency and achieve the best efficiency.Finally,according to the impedance matching transmission system and related control strategies based on LCC-S structure,the corresponding experimental platform is designed.It is mainly divided into two parts,the main circuit and the control system.This thesis respectively describes the selection and design of each module and component.Based on the experimental platform research and analysis of the relevant characteristics of the whole system,verify the theoretical research of impedance matching for the new LCC-S-DC-DC circuit system.Through the experimental comparison and verification of the impedance matching method can achieve the adjustment of the equivalent load impedance,achieve the optimization of transmission efficiency.