Research On Design And Control Strategy Of Dynamic Wireless Charging System For Electric Vehicles

Under the background of global warming,energy crisis,and air pollution,traditional motor vehicles are in urgent need of transformation due to their high pollution and high emissions,and electric vehicles have attracted much attention due to the use of clean energy.However,electric vehicles still cannot shake the market position of traditional motor vehicles,for we cannot find an ideal solution to the two major technical difficulties of charging and energy storage.Dynamic wireless charging technology charges electric vehicles during use,which can effectively reduce parking charging time and battery capacity,so it has broad application prospects.However,the mutual inductance changes in real time during the driving process of the car,which leads to drastic fluctuations in output power and complicated control strategies.In this paper,electric vehicle dynamic wireless charging technology based on the magnetic coupling resonance is taken as the research object,in order to address the above problems,we start from the aspects of system modeling,compensation network,overall design,etc.,and seek the method of real-time detection of mutual inductance through the algebraic relationship between electrical signals.Based on this,the control strategy of the system is designed to achieve constant output power and timely switching between transmitting coils.In the process,this article focuses on the following:1 The four basic compensation topologies and two improved compensation topologies are studied.By comparing their advantages,disadvantages,and parameter characteristics,it is found that the LCL compensation topology can achieve constant transmission coil current without being affected by mutual inductance and load changes,and is more suitable for complex dynamic wireless charging scenarios because it can effectively reduce the system dimension.2 Investigate the relationship between the structure of the dual-transmitting coils and the coupling coefficient,and use the Newman formula to quantitatively analyze the influence of the coil length,width,height and spacing on the mutual inductance,and draw an equal scale model of the system based on the actual size of the electric vehicle,Tesla S,to achieve a compromise between electrical performance and economic benefits of the system.3 The algebraic relationship between the electrical signals of the system is studied.Through theoretical analysis and simplification of the formula,a method that can detect the mutual inductance coefficient in real time is found.Under the premise that the mutualinductance is known,the input voltage can be adjusted by phase shift control to control the output power.Also,we found the role of mutual inductance detection in switching control between coils.4 Study the harmonic components in the system,verify the impact of the harmonic components on the stability of the system by fast Fourier transform,and optimize the system by adding a passive filtering link.Aiming at the gradually-established dual-transmitting coil dynamic wireless charging system based on the LCL-S compensation topology,this paper uses the Simulink simulation platform to achieve constant voltage control with an output power of 35 W,and by designing and building an experimental platform,the control target of the output power of the receiving coil when the position of the coil has a limited offset is about 34 W is achieved.The error of the experimental results is less than 3%,which verifies the correctness and effectiveness of the theoretical analysis of the full text.