Research On Node Role Switching Method And Power Transfer Route Optimization For Multiple Node Wireless Power Transfer System

Wireless power transfer(WPT)technology based on magnetic coupling realizes the non-contact power transmission with magnetic field as the power transfer medium,and under the principle of electromagnetic induction.The wireless power transfer technology has been widely concerned by experts at home and abroad for its advantages of safety,reliability,flexibility,convenience and simple installation.In the traditional WPT system,there is usually only one power transmitting unit and one power receiving unit.However,in more and more WPT application scenarios,there are multiple power transmission devices,such as robot arm,rail transit,group robot and so on.The limitations of the traditional one-to-one wireless power transfer mode in such scenarios make people begin to study the multiple node wireless power transfer technology.At present,the research of multiple node WPT system are mainly focused on extending the power transfer distance,improving the transfer power and efficiency,and improving the system performance.However,there are few researches on the node role switching and power transfer route.Therefore,to fill the research gap,the multiple node WPT system will be studied from the above two aspects in this paper.The control of power flow including the amounts and directions is always studied in the various multiple node WPT systems.With the increase of the node numbers,the design of controller becomes more complex.Aiming at the above problems,this paper focuses on the node role switching and power transfer route optimization in multiple node WPT system,which provides method reference and theoretical support for the design of multiple node WPT system in practical application.Specifically,this dissertation has done the following research work:(1)Research on wireless power transfer mode with multiple node parallel output capabilityAiming at the problem that the parallel output power of multiple node WPT system is limited due to many parameters and mutual constraints between parameters,this paper designs a wireless power transfer system with parallel output capability of nodes based on the impedance analysis method around the application of WPT technology in multiple node robot.In view of the fact that the multiple node WPT system is a multiple degree of freedom electromagnetic induction system under mutual inductance and load disturbance,this paper comprehensively considers the influence of the above two factors on the system,establishes the mathematical model of the multiple node WPT system under two operating modes,and designs the LCC-S topology structure meeting the constant voltage output characteristics of each node.In addition,the role of node can be flexibly switched between transmitting,relaying and receiving,and the effectiveness and feasibility of the system are verified by experiments,which lays a theoretical foundation for the subsequent research of multiple node WPT system.(2)Research on enhanced wireless power transfer mode based on node reverse power injectionAiming at the problem of low power transmission capacity in multiple node WPT system due to the large number of nodes and different power demand of nodes,a method based on reverse power injection of nodes is proposed to improve the power transmission capacity of the system.Based on the system mathematical model,by quantifying the internal relationship between the output voltage of the power receiving node and the system parameters,the key factor to improve the system power output capability is revealed,that is,to ensure the synchronization of multiple AC power supply phases when multiple nodes inject power at the same time.By deeply analyzing the output characteristics of the system,a synchronization control method suitable for multiple node WPT system is proposed,which can quickly and accurately adjust the phase synchronization of multiple AC power sources.Then,taking the model parameters of the system in strengthening mode as the trajectory,the evolution process of power reverse injection is deeply analyzed,and the boundary conditions of power reverse injection are determined to ensure that the role of node can be flexibly and dynamically switched between transmitting and receiving.(3)Research on node role dynamic switching method based on topology switchingAiming at the problem of different power requirements of each node in the current multiple node WPT system,the role of the node is changed online by changing the topology of the node to meet different power requirements.By constructing the circuit model of the multiple node WPT system,the initial topology of the node and the switching method of the node topology are determined.Because there are many inductors and capacitors in the system,this paper analyzes the dynamic model of the system,shows the stability of the system transition process under the change of operating mode,and forms a complete node role transformation method based on topology switching,which lays the foundation for the subsequent design of multiple node WPT system.In addition,through the analysis of the output performance of the system in different operating modes,it is proved that the system has the characteristics of constant voltage or constant current output in some operating modes.(4)Research on power transfer route optimization method for multiple node WPT systemAiming at the multiple node WPT system,a power transmission path optimization method is proposed to improve the power transmission capacity of the system.Considering the cross coupling between nodes,the mathematical relationship between the parameters of the multiple node WPT system is established,and the internal relationship between all the parameters that affect the output capability of the system is deeply analyzed,it provides a systematic design process for multiple node WPT system to work on the optimal power transmission path.By analyzing the relationship between the output voltage and the parameters of the system,the conclusion is drawn that the system has constant voltage or constant current output characteristics.Finally,the effectiveness and feasibility of the system are verified by experiments.