| Resonant wireless power transmission technology is suitable for wireless power supply for load devices of various power levels.The advantages of this technology are that it has a longer transmission distance,larger transmission power,and non-radiation.However,in practical application and research process,such as load changes,the system transmission will change,so the system is not easy to keep in the best working condition;the parameters of the transmission coil are not optimized in the design,resulting in a higher quality factor Low and so on.Aiming at the problems existing in this technology,this paper aims to optimize the efficiency and takes the load characteristics as the starting point to study the relationship between load and system transmission characteristics.The transmission coil design is optimized and the design method of the maximum efficiency load point is given.In order to keep the system transmission performance in the best condition when different loads are connected,the equivalent load size can be changed by adding an appropriate impedance transformation network,Improve system load adaptability.The paper analyzes the principle of magnetic coupling wireless power transmission,as well as the main components of the system,the key technologies.The two compensating topologies with the input series resonance are compared and the series-series compensation scheme is determine(d)Based on the circuit theory,the influence of three kinds of load access on the transmission efficiency of the system is analyze(d)A detailed analysis of the factors affecting the system's maximum efficiency load point is given.In view of the decrease of transmission efficiency due to the highest efficiency point of load access bias,By improvingthe mutual inductance,resonant frequency and reduce the resistance of the coil,the system can essentially improve the load adaptability and transmission efficiency of the conclusion,and gives the L-impedance network maximum efficiency load matching strategy to make up for the lack of design.The design of the coil coupling part determines the mutual inductance and the resistance of the coil.In the practical application and the output power are in line with the Maxwell finite element simulation software simulation analysis of the characteristics of the three coil shapes,and select the combination of coil shape,The aspect ratio,the number of turns of the coil and the turn spacing are optimized for the purpose of improving the system transmission efficiency and load adaptability.Through the design of inverter circuit,rectifier circuit,coupling mechanism and buck circuit,a set of experimental platform with a transmission distance of 15 mm,output power of800 W and transmission efficiency of 81% has been set up.The experimental results show that the composite coil with integrated optimization design can effectively improve the transmission efficiency of the system and verify the existence of the highest efficiency load point,the efficiency of the highest efficiency load matching design and the correctness of the load impedance matching network. |
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