Research On Parameter Optimization And Coordinated Control Method Of Wireless Charging And Discharging System For Electric Vehicle

Bidirectional Wireless Power Transfer(BD-WPT)is an important branch of wireless power transfer technology.This technology can further play the role of Vehicle to Grid(V2G)and realize intelligent bidirectional charging and discharging in real sense in addition to the advantages of safe,convenient and high degree of automation.BD-WPT is an effective energy interaction networking interface technology.The existing research focuses on one-way power transfer technology.There are few researches on BD-WPT technology,mainly focusing on steady-state modeling,power stability control strategy,etc.,lacking of transmission characteristics analysis,compensation network parameter design,dynamic modeling,power efficiency coordinated control strategy.In view of the above problems,this thesis has carried out the following aspects of research on BD-WPT technology and obtained corresponding conclusions:Firstly,this thesis studies the control scheme of BD-WPT system,analyzes and compares the working principle,advantages and disadvantages of three control schemes.Considering that the phase shift control scheme has advantages of small volume,simple circuit and high efficiency,phase shift control scheme is selected as the control scheme of the BD-WPT system described in this thesis.Based on the mutual inductance theory,the equivalent circuit models of S-S compensation network BD-WPT system,LCL-LCL compensation network BD-WPT system and LCC-LCC compensation network BD-WPT system are established.The comparative analysis shows that the LCC-LCC compensation network has advantages of flexible design,good misalignment tolerance and working safely under all working conditions.In order to optimize the voltage and current stress of compensation components,the compensation network parameters are designed.The research shows that for a certain power demand,if the compensation parameters of the primary and secondary sides are completely consistent,the compensation components will work at a relatively close load level,which is conducive to long-term stable operation of the system.Secondly,this thesis analyzes the common modeling methods of wireless power transfer system,and establishes the generalized state space averaging model of BD-WPT system.After verifying the feasibility and accuracy of the model,the transfer function matrix is deduced and the bode diagram is drawn based on the model.The characteristics of BD-WPT system are analyzed.Based on the analysis of the transmission characteristics,a segmented power-efficiency coordinated control strategy is proposed.This control strategy can operate the BD-WPT system at different resonant frequencies according to specific power requirements,thereby enabling the system to achieve higher transmission efficiency.Finally,the simulation and experimental platform of BD-WPT system is built to verify the feasibility and effectiveness of the theory or method proposed in the thesis.