Research On Wireless Charging Compensation And Primary Feedback Control Strategy For Electric Vehicles

New energy vehicles,mainly electric vehicles,are gradually replacing traditional fuel vehicles.Currently,electric vehicles have made significant progress and development.Charging devices are an important component of the electric vehicle industry,and improving charging quality and experience is very important for electric vehicle users.Charging devices are an important component of the electric vehicle industry.Due to its greater safety,convenience and practicality,WPT(Wireless Power Transmission)technology has been widely applied in many fields and has profoundly changed people’s lives.It has also gained increasing attention and research in the field of electric vehicles.However,the output of a magnetically-coupled wireless power transmission system is sensitive to output loads.When using an electric car’s lithium-ion battery as a load during charging,changes occur in the terminal voltage and equivalent impedance of the battery which can affect the output of the wireless power transmission system.To address this issue,this paper proposes two control strategies to achieve constant current /constant voltage(CC/CV)control without communication between transmitter and receiver ends during outputting.The main contents are as follows:Firstly,by comparing efficiency and ZPA(zero-power angle)conditions for different topologies we determine that LCC-S compensation topology will be studied further;Analyzing in detail,the LCC-S compensation network input impedance angle characteristics are studied with respect to system switching frequency and load relationship under two switching frequencies where input impedance angles satisfy ZPA conditions enabling soft-switching completion along with system parameter configuration completed accordingly.Based on network gain analysis and output characteristic analysis determine working frequencies for both CC mode and CV mode while verifying converter topology and dual-frequency switch strategy through simulation software.Secondly mathematical modeling is done via switch model method followed by proposing a load identification method based on reflection impedance theory along with implementing primary feedback closed-loop control strategy using state observer;simulation software verifies observer observation accuracy while phase-shift control enables stable operation when there is change in load without communication or cascading transformer at receiving side.Thirdly hardware platform design for wireless charging experiment based on LCC-S compensation network is carried out including selection of main circuit switches,design considerations for resonant inductor and capacitor components along with designing loosely coupled coil structure after comparative analysis on coil structure and magnetic core selection;finally introducing designs for driving circuitry,sampling circuits and phase detector circuits within experimental platform controlling circuitry.Finally through experimentation using LCC-S wireless charging converter platform300 V input/output voltage and 3.6k W power transfer was achieved successfully validating basic operating modes and soft-switching characteristics.