Research On Constant Current Constant Voltage Wireless Charging Topology And Control Technology Of Electric Vehicle

With the increasingly serious pollution and emission issues of traditional fuel vehicles,electric vehicles have received widespread attention from society because of their zero-carbon emissions,energy-saving,and high-cost performance characteristics.Wired charging method of Electrical Vehicles has drawbacks such as limited number of charging stations,large space requirement,long charging duration,safety issue and so on.Consequently,many researchers tend to focus on wireless charging due to its high ratio of space utilization,convenience and low maintenance cost.This thesis researches on wireless charging technology of electrical vehicles and studies each component of wireless charging system as well as puts forward the design procedure of wireless charger.Effectiveness and practicality of the designed wireless charging device are proven through simulation and hardware experiments.Firstly,this thesis studies design of compensation network,comparing four typical topology(S-S,S-P,P-S,P-P)as well as studying characteristics of LCC and LCL topologies.Then it researches on power converters and control methods of wireless charging system.Secondly,this thesis proposed a closed-loop control strategy based on load identification unit and PI controlled phase shift H-bridge inverter.It can realize the CC/CV charging for WPT system.This method needs no measurements of current and voltage of secondary-side,so secondary-side controller is eliminated,which reduces cost of the whole device.Finally,this thesis puts forward design procedure of wireless charging devices.This paper designs a wireless charging device composed of a 75cm×75cm primary coil and a 50cm×50cm secondary coil(gap is 200mm),operating frequency of which is 85 k Hz.Proposed control strategy is utilized.Effectiveness and practicality of the designed wireless charging device and proposed control strategy are proven through simulation in MATLAB/Simulink and hardware experiment.Outcome shows this device can realize power transfer rating at 3.7kW and efficiency of 96.9%.