Research On Wireless Charging Control System For Dual LCC Electric Vehicles

Wireless Power Transfer(WPT)technology,as a new power supply method,has the advantages of safety,convenience and reliability,and is used in transportation,aerospace,medical and other fields.In the field of transportation,with the promotion and application of electric vehicles,its wireless charging technology has developed rapidly and has gradually become a research hotspot in this field.At present,the power batteries of electric vehicles are mainly lithium batteries.According to the charging characteristics of lithium batteries,a two-stage charging mode of constant current and constant voltage can be used.In order to meet the needs of wireless charging of electric vehicles,the main research contents of this paper are as follows:(1)The transmission characteristics of the LCC compensation network are studied,and the dual LCC main circuit structure of the electric vehicle wireless charging system is determined.The constant-current and constant-voltage output characteristics and resonance conditions of the LCC are analyzed first,and then the dual constant-current operation mode and the transmitter-stage constant-current and receiver-stage constantvoltage operation modes of the dual LCC topology are investigated,and the transmission power and transmission efficiency under the two operation modes are derived and sensitivity analysis is performed to find the key parameters affecting the system and provide a certain theoretical basis for the selection of devices in practical engineering applications.The results show that both modes of operation have good transmission performance at light load.(2)In order to adapt to the change of load and meet the charging demand of electric vehicle power lithium battery,a simple PI control method is proposed.The circuit before the rectifier stage is processed by Thevenin equivalent and reduced order,the control model is simplified,the input voltage and current fundamental wave of the rectifier stage are identified by the least square method with forgetting factor,and the equivalent load is determined;the constant current output and constant current are designed respectively.The PI controller when the voltage is output;and the simulation model is built in MATLAB/Simulink.The results show that the control strategy can meet the charging requirements of "constant current first and then constant voltage" for electric vehicle power lithium batteries.(3)A control method based on dynamic phasor is proposed to improve the dynamic response speed of the system while meeting the charging requirements of electric vehicle power lithium batteries.Based on the dynamic phasor method,the sine component and cosine component of the fundamental wave are decomposed,and the amplitude is determined by the charging mode.After PI control,the communication is sent to the transmitter stage for determining the phase shift amount,and the transmitter stage determines the PWM wave according to the phase shift amount.,to achieve the charging requirement of "constant current first and then constant voltage" of electric vehicle power lithium battery,and based on the phase relationship between output current and input voltage in LCC constant current mode,the frequency tracking controller of the transmitter stage is designed to ensure that the transmitter stage works at Under the condition of resonance,the simulation model is built in MATLAB/Simulink finally to verify the correctness of theoretical analysis and control strategy.This paper has 42 figures,5 tables and 72 references.