| With the inconvenience and danger brought by the traditional contact power supply,people pay more and more attention to the more convenient and safer power supply mode,and the wireless power transfer technology emerges as the times require.Wireless power transfer can well overcome the defects of traditional power supply,solve the problem of frequent using socket in the process of charging,and improve the frequency of interaction between electrical equipment and power grid,which has high practical value.As the most popular direction of wireless power transfer technology,inductive power transfer has achieved fruitful research results,especially in the field of electric vehicle charging.But in the engineering application,the wireless charging system of electric vehicle has the problems of small charging area and poor charging compatibility of different kinds of vehicles.Therefore,based on the wireless charging technology of electric vehicle,this paper studies the above defects.Firstly,this paper introduces the background and main classification of wireless power transfer technology,and introduces the research status of inductive power transfer technology in the field of electric vehicle wireless charging,including circuit topology analysis,system control,and magnetic coupling mechanism design.it expounds the purpose and significance of this study.Then,this paper analyzes the basic principle of inductive power transfer,including compensation,power conversion,and magnetic coupling mechanism,in which the working principle and modeling solution method of magnetic coupling mechanism is emphasized.Then,based on the circular coil,the misalignment performance of symmetrical and asymmetric magnetic coupling mechanism is analyzed,and the influence of the number of winding turns,the degree of asymmetry of magnetic core and coil on the misalignment performance of magnetic coupling mechanism is studied.It is found that the misalignment performance of the asymmetric magnetic coupling mechanism is better than that of the symmetrical magnetic coupling mechanism,and with the increase of the degree of asymmetry,the misalignment tolerance performance is better.When the number of turns is about half of the maximum number of turns,both high coupling coefficient and low cost can be satisfied.The use of magnetic core in a certain range of air gap can effectively enhance the coupling of primary and secondary coils.Finally,this paper studies the asymmetric magnetic coupling mechanism with a reversed coil,gives the design process,and makes a detailed analysis.This structure has a strong ability of misalignment tolerance performance.The mutual inductance of the traditional asymmetric magnetic coupling mechanism decreases by 30% in the specified range,while the new structure mutual inductance can keep constant in the specified range.The transmission power of the dual LCC compensated inductive power transfer system designed with the final optimized magnetic coupling mechanism decreases by about 5% when the misalignment distance reaches 1/3 of the diameter of the secondary coil,while the transmission power of the asymmetric magnetic coupling mechanism without the reversed coil decreases by about 30% when the misalignment distance is the same.The experimental platform of the system is built and compared with the simulation analysis to verify the results.Besides,this paper also studies the compatibility of electric vehicle charging,mainly the problem of air gap matching of primary and secondary coils.Firstly,it explains the concept and analyzes the principle,and then designs additional secondary coils based on the misalignment tolerance magnetic coupling mechanism with a reversed coil.The working air gap of the two secondary coils is different,but the same power is transmitted based on the same primary side.Finally,the actual system is carried out.The validity of the theory is verified by building and comparing it with simulation analysis. |
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