Research On Several Characteristics Of Dual-LCC Type Inductive Coupled Power Transfer System

Wireless power transmission technology can solve the problems of wearing and aging wire,poor contact in traditional wired transmission,which has become a hot topic in recent years.Owing to the advantages of wide frequency range and high power level,inductive coupling power transfer system is widely used in wireless power transmission.The presence of large leakage inductance in circuits lead to low coupling coefficient of the system.Therefore,chosing appropriate compensation topology to improve the power factor has become an integral part of inductive coupled power transfer system.Research on the choice of compensation topology and the characteristics of the compensated system has become a hot research topic in academia.The selection elements of compensation topology is summarized,and the advantages and disadvantages of the commonly compensation topologies is summed up in this thesis.And the dual LCC type compensation system is determined as the research object.Firstly,a fundamental equivalent model of the system is established in the study of the characteristics of main circuit in this paper.The resonant frequency of the system is found when determining resonant conditions.The characteristics of power factor and primary side coil current are analyzed based on mutual inductance model.The output characteristics of system is analyzed based on leakage inductance model.In the meanwhile,an equivalent model is proposed to solute frequency where output voltage is constant in the frequency domain.Secondly,two optimization methods to achieve zero voltage opened(ZVS)of full bridge inverter are proposed in this paper.Taking compensate capacitance for adjusting object,turn-off current as an intermediate variable,and finding the relationship among the compensation capacitor,turn-off current and ZVS are the core of the methods.In this process,an equivalent model approximation method is used to calculate the high frequency components of the turn-off current.Finally,the design and optimization of system are completed,and a detailed analysis of optimization method's effects on the output characteristics of system is studied.In this thesis,the characteristics of the main circuit and soft switching performanceon double LCC system,meet the demand of compensation topology,which can improve the power transmission capacity and efficiency.The harmonics of the inverter output current are taken into account in the proposed optimization method to achieve ZVS.It has reference significance to the system which has similar LC type compensation topology.The research content can be extended due to study on the output characteristics and the analysis of optimization method's effects on the output characteristics.Finally,the model of double LCC compensation system is built in the Simulink,and a prototype of 3.3 kW double LCC resonant converter is completed.Simulation and experimental results are in accordance with the topological analysis and optimization method.