Research On Self-starting Design And Optimal Control Strategy Of Wireless Charging-discharging System For Electric Vehicles

The demands of energiewende and sustainable economic growth promote the rapid development of the electric vehicle(EV)industry.There are greater prospects for the wireless charge-discharge technologies for EVs.In recent years,Bidirectional wireless power transmission(BD-WPT)technology has received more attention in this field,whose combination with V2G(Vehicle to Grid,V2G)technology can further realize the energy interaction between cluster EVs and the power grid.Aiming at the wireless charge-discharge system for Es based on BD-WPT technology,this dissertation focuses on the optimization and control of its circuit model,interoperability evaluation and collaborative control for cluster EVs.The main tasks are as follows:Firstly,as the basis for the application and promotion,the circuit model of BD-WPT system was established to analyze the energy flow mechanism.The power-efficiency coordinated control method for BD-WPT system were provided and the loss were explained based on the circuit model.In view of the interoperability issues,we focous on the passability requirements firstly.The interoperability test methods based on the magnetic flux method and the impedance method were analyzed and compared.We established the interoperability test method based on the impedance method and gived the specific operation steps and instructions.An interoperability passability evaluation method was presented based on the passability requirements index system.The proposed use scenarios are given for the EV wireless charge and discharge systems with different evaluation results.Two resonance judgment methods were proposed to optimize the specific BD-WPT system structure,and the one based on unilateral detection of the current phase change was applied.A new power-efficiency collaborative optimization control method was further proposed,which introduced resonance judgment and phase synchronization(RJ&PS)circuit on EV side,solving the problem of system resonance discrimination and bilateral control signal synchronization.The stable synchronous anto-start of the secondary side without communication was realized and the specified power transfer was achieved with maximum efficiency in zero reactive state.Thus coordinated and optimized control of power and efficiency can be realized and the accuracy and effectiveness of the method was approved by the expertiment.Finally,a comprehensive energy control system is designed for the cluster EV wireless chargedischarge system,which contains the energy unit as the basic unit,the sub-console as the command issuings and the master console as the control center.This dissertation analyzed the energy loss,battery loss and control complexity after cluster EVs connected to the grid.Taking the overall power loss,battery loss and control complexity of the system as the goal,determining the constraints of electricity demand,power and grid capacity,the collaborative optimization control model of the system was established.The model was further abstracted as a complete dichotomous graph matching problem with variable weights,as a coupling of nonlinear optimization problem and dichotomous graph optimal matching problem,a genetic algorithm based on graph optimization can be designed according to the characteristics of the problem.The effectiveness and correctness of the optimization model and the algorithm are verified by a numerical example with 16 EV nodes and 4 energy units.