Research On Double-sided LCC System For Wireless Power Transfer Based On Two-port Network

Since the concept of wireless power transfer(WPT)was proposed by Nicholas Tesla,scholars at home and abroad have done a lot of research on it.With the application of wireless power transfer technology to energy storage loads such as mobile phones,tablet computers,electric vehicles and implanted human medical devices,various requirements are put forward for the wireless power transfer system,such as constant current and constant voltage output characteristics,reducing loss to increase the efficient of the system,etc.In order to meet the requirements of energy storage load on WPT system,scholars proposed a variety of methods,such as control technology of output,switching compensation network and high-order compensation network.Because of the advantages of high-order compensation network,such as reducing the complexity of the control system and no additional transmitting procedure,it has become a research hotspot of scholars at home and abroad.But the traditional impedance analysis has many problems in the analysis of high-order compensation network.Based on this,this paper focuses on the constant current and constant voltage output characteristics,zero phase angle of input voltage and current,and soft switch of switching device in the power transfer equipment.Therefore,this paper first studies the constant current and voltage characteristics of the third-order two port network,integrates them according to their different characteristics and analyzes the characteristics of their combined network.Due to the advantages of the double-sided LCC compensation network,such as the large number of compensation elements,the high degree of freedom of system design and the ability of anti offset,this paper selects this network to construct its constant current and constant voltage resonance network,and deduces the ZPA conditions and soft switch design expressions for constant current and voltage output.Also the harmonic problem of input current is analyzed.Finally,in order to reduce the influence of harmonics on the input current,achieve the single frequency switching of constant current and constant voltage output modes and avoid step of load current and voltage after switching,the parameters of each compensation element are designed.Also a simulation and a small power experiment are built to verify the theoretical analysis,and the efficiency meets GB / T38775-2020.