The Study Of Three Port Resonant Converter Based On Photovoltaic MPPT

With the development of science and technology,the consumption of fossil fuels such as coal and petroleum is increasing.However,this kind of energy resource is limited.Therefore,how to develop and utilize it efficiently has brought severe challenges to us.In all kinds of renewable energy,solar energy occupies an extremely important position.Research on various types of photovoltaic power generation system has also been carried out in full swing.Among them,the independent photovoltaic power generation system is a typical type of photovoltaic power generation system.In the stand-alone PV system,many researchers have combined energy storage devices with power generation systems.How to efficiently transfer energy between three ports of energy storage devices,power generation devices and load devices has become a valuable research direction.In addition,in order to improve the efficiency of solar energy utilization,many scholars have applied the LLC resonant soft switching technology to the stand-alone PV system,which greatly improves the energy transmission efficiency of the system,while achieving maximum power point tracking.In this paper,the working principle of LLC resonant converter is studied,and the simulation and experimental verification are carried out.The simulation and experimental results show that the LLC resonant circuit can achieve high energy transmission efficiency.Secondly,the full bridge LLC resonant circuit integrated three port bidirectional Buck/Boost converter(Three-Port Converter TPC)is the research object of this paper,and a circuit model is established.Then the synthesis process of the full bridge LLC resonant converter TPC topology integrated bidirectional Buck/Boost,the analysis of the power flow between three ports and the analysis of the specific working process are given.According to the different resonant states of the converter,there are four different working modes.In this paper,the focus of one of the work mode is analyzed.The gain characteristics,the input current ripple characteristics and the soft switching characteristics of the converter are analyzed and compared in detail.Then,a simulated PWM+PFM hybrid modulation control strategy is proposed,and the control principle of the control strategy is analyzed.Finally,the paper selected the appropriate parameters to verify the application of the proposed PWM+PFM hybrid modulation control strategy in full bridge LLC resonant converter integrated bi-directional Buck/Boost circuit.The simulation results verifed the correctness and superiority of the operation principle,the working characteristics and the system control.