| In recent years,driven by government policies and consumer demand,the number of electric vehicles is growing.With the increasing use of electric vehicles,the higher requirements of their endurance and safety are put forward by consumers.Dynamic wireless charging technology is an important way to address the problems of big battery,limited battery life,and challenging charging.The paper outlines the research and development trends in dynamic wireless charging technology for electric vehicles,and briefly presents the working theory about dynamic wireless charging systems for electric vehicles.The basic structure of dynamic wireless charging system for electric vehicles is introduced from the aspects of high frequency inverter circuit,resonant compensation topology,electric energy conversion circuit,magnetic coupling mechanism and system controller.Based on the equivalent circuit theory,the system is modeled and solved to analyze the transmission characteristics of the system.The circuit is built in MATLAB software for simulation analysis,and the circuit parameters of the transmitter and receiver are determined based on the simulation results.Multiple transmitting coils at the transmitting end are used to wirelessly charge the running electric vehicle,several current positioning detection techniques are investigated,the advantages and disadvantages of various technologies are compared synthetically,and the optical positioning detection technology based on diffuse reflection is selected.A positioning detection module and a transmitting coil switching control strategy are designed,and the magnetic field distribution of the system using positioning control is determined through simulation analysis,which proves the feasibility of the positioning control method.Not only the fast and accurate positioning of electric vehicles is effectively realized,but also the continuity and stability of dynamic wireless charging are guaranteed.The receiver DC-DC conversion circuit is used to charge and adjust the load.First,the operating concept of the DC-DC converter circuit is introduced.The driving signal of the receiving end charging circuit is determined by using the small signal modeling method and the state space average method.With the dynamic characteristics of output current,a slip-loop modulation sliding mode controller is built.Simulink simulation software is used to model the wireless charging device for testing,and the reliability of the control loop is evaluated.The simulation results show that the designed controller has the characteristics of small charge current error,small charge fluctuation,load adaptability and offset adaptability.The preliminary theory and simulation results are used to establish the static wireless charging system of electric vehicle.The frequency characteristics,lateral offset characteristics,and load characteristics experiments were performed.The basic reference for the establishment of an electric vehicle dynamic wireless charging system was used.The experimental results show that when the resonance frequency is 85 k Hz,when the lateral offset is less than 10 cm,the load is 14Ω,and the transmission distance is 0.2m,it not only accords with the distance between the electric vehicle chassis and the ground,but also makes the transmission power and efficiency of the system higher.Subsequently,the controller was designed to adjust the load power to ensure that the receiving end received power smoothly to charge the load.A dynamic wireless charging experimental platform was established to verify the feasibility of the transmitting and receiving end controllers,and variable load adaptability and variable speed adaptation were performed to verify the universality of the controller.The experimental results show that the transmitter controller ensures the continuity of charging during the driving process of the electric vehicle,and the receiver controller can quickly adjust the load end,so that the load receives a steady current voltage,with the characteristics of small overshoot,fast control speed and good adaptability to variable load and variable speed. |
