Research On The Characteristics Of Constant Current/Constant Voltage Of Reconfigurable T-Topology-Based WPT Network Topology

As a significant guarantee for the green travel of electric vehicle(EV)users,the development of charging technology provides potent support for the boom of new energy vehicle industry and realization of carbon peaking and carbon neutrality goals.Thus,the variety and accessibility of charging modes are inevitably required with the widespread of EVs.To provided a safer and more effective charging condition for power battery and accelerate the promotion of EVs,the study of constant current(CC)and constant voltage(CV)output characteristics for EV wireless power transfer(WPT)is in urgent demand.More often than not,the output characteristic is bound up with its network topology.Therefore,in order to simplify the charging control of WPT system,this article embarks on network topology to explore the nature of passive network,and implement the CC and CV output characteristics of WPT system.Based on the variable structure compensation network topology,two variable structure circuits which are appropriate for transmitter and receiver are proposed respectively,and verify the validity of variable structure network construction method theory.The specific research is as follows:First and foremost,three application structures are acquired based on the analysis of T type topology by mesh current method.On account of the above structures,two variable structure elements which suitable for different occasions are obtained.To meet the restraints of constant output and zero phase angle(ZPA)characteristics,the cascade static network of variable structure element is divided into a series of typical lower order network topologies via two port network cascading theory.Hence,two variable structure network construction schemes which apply to transmitter and receiver respectively are presented and proved in this article.Secondly,aiming at automated guided vehicle(AGV)application which owns precision navigation,a transmitter-based variable structure WPT system which could achieve CC/CV mode switching is proposed according to the variable structure network construction schemes.With the superiority of high degree of freedom in parameter design,the output current and voltage of this circuit could be configured.Meanwhile,through the switches multiplex technology,the switching elements could be saved,which enhances the cost reduction of the system.In addition,a method of natural current cutoff with unidirectional switch-off is studied,and a transmitter-based switching control strategy without additional sampling circuit is proposed to solve the energy impact of branch cutting in variable structure circuit.Furthermore,a 1k W prototype is constructed to verify the validity of the transmitter-based variable structure network construction schemes and switching control strategy.Finally,according to the variable structure network construction schemes,a receiver-based CC/CV variable structure WPT system which inherently possesses closed-loop regulation is presented to meet the application of static WPT of EVs.On account of switches multiplex technology,this circuit not only possesses closed-loop regulation ability,but also has the advantage of less passive components and power switches usage.Meanwhile,to solve the output fluctuation caused by offset,a novel time-division phase-shift control strategy which consists of CC as well as CV phase-shift control modes and owns wide regulation range is proposed.And the experiment results eventually verify the validity of the receiver-based variable structure network construction schemes and closed-loop control strategy.