Research On Bidirectional LLC Resonant Converter In Photovoltaic System With Energy Storage

Nowadays,energy resource is transforming from fossil energy into renewable energy.With the rapid development of photovoltaic power generation technology,the application of solar energy undoubtedly provides a powerful driving force for energy transformation.Photovoltaic power generation system is to convert solar energy into electricity which supplies the load for use,or Accesses the power grid.However,the electric energy generated by photovoltaic power generation system is significantly affected by environmental factors such as illumination intensity and temperature.Because the electric energy generated is unstable,energy storage devices need to be added to the photovoltaic power generation system.The purpose of this paper is to study the electrical characteristics of photovoltaic power generation system with energy storage device.The whole system mainly includes: photovoltaic cell,boost converter,two-way LLC resonant converter,control circuit,detection circuit,battery,etc.The photovoltaic power supply model is established.The output characteristic curve have one and only one maximum power point.Thus,Maximum Power Point Tracking(MPPT)technology is adopted to make full use of solar energy in photovoltaic Power.An efficient bi-directional LLC resonant converter is designed for the energy storage photovoltaic system,which realizes the bi-directional flow of energy and effectively improves the energy storage efficiency of the photovoltaic system.By using Simulink simulation module in MATLAB,the simulation model of photovoltaic power supply is established,and the output characteristics of photovoltaic power supply are obtained.MPPT is realized by applying conductance increment method,and a model based on control Boost circuit is established for the analysis of MPPT.The modal analysis of bi-directional LLC resonant converter is carried out,and the simulation model is established.Saber software is used to conduct the simulation study of bi-directional LLC resonant converter.The conclusion is that the soft switching can be achieved at both forward operation and reverse operation.The accuracy of the design is verified.The energy management strategy is proposed,and the operation status of the bi-directional LLC resonant converter is determined by detecting the photovoltaic output voltage and the voltage of the battery.The simulation verification is carried out.