Design Of Wireless Charging System For Electric Vehicle Based On Flexible Coil

With the development of driverless technology,the intelligent and convenient charging method of electric vehicles is the future development trend.Therefore,it is of great significance to study the wireless charging of electric vehicles.However,due to the long distance and difficult alignment between the transmitting coil and the receiving coil of the traditional wireless transmission system,the charging efficiency is often unsatisfactory,which hinders the popularization of the vehicle wireless charging technology.In view of the above problems,the following researches are carried out in this paper:(1)A scheme of roof-mounted wireless charging is proposed,the receiving coil is installed on the roof,and the transmitting coil is suspended above the roof.When wireless charging is performed,wireless power transmission can be performed by attaching the transmitter coil to the roof of the vehicle.The flexible charging coil is designed based on the flexibility and stretchability of the serpentine wire,which can ensure the tight fit of the coil and the curved roof.Reduce the distance between coils,thereby improving the efficiency of wireless power transmission.(2)The composition of the wireless charging system and the function of each functional circuit are introduced.In order to improve the efficiency of wireless charging,the transmission performance of four basic compensation networks of SS type,SP type,PS type and PP type are studied respectively.The transmission characteristics of the four compensation networks are analyzed.According to the application scenario of wireless charging of electric vehicles,the PP type is selected as the compensation network for the wireless charging system.The influence of parameters on the transmission performance of PP compensation network is studied by circuit simulation.(3)In order to make the coil have good ductility,the ductility of the serpentine wire is analyzed and studied.According to the beam bending deformation theory and the plane bending rod deformation theory in the mechanics of materials,the tensile deformation of the serpentine wire is theoretically deduced.By comparing the results of finite element simulation and theoretical calculation,the accuracy of the theoretical calculation is proved.And the influence of the geometric parameters of the serpentine wire on the deformation of the serpentine wire is explored.(4)Flexible coils are used in roof-mounted wireless charging systems,which require high ductility and conductivity.Since the flexible coil is composed of periodic serpentine wires,the geometric parameters of the serpentine wires are analyzed and optimized.Response surface methods can analyze the effect of multiple variables and their interactions on the response.The response surface method was used to explore the influence of geometric parameters on the elastic elongation and resistance,and a set of optimal parameters was obtained through optimization.Under the condition that the elastic elongation of the serpentine wire remained basically unchanged,the resistance was reduced by 31.65%.(5)According to the above theoretical analysis,three wireless charging chips are selected first,and the circuit of the wireless charging system is built according to their pin functions.The resonance compensation capacitor and load are selected according to the parameters of the coil and the wireless charging system.Through experiments,combined with finite element simulation experiments,the efficiency of the wireless charging system before and after optimization is compared.The results prove that the charging efficiency of the optimized wireless charging system is improved by about 10%.