Research On Bidirectional DC-DC Converter In Independent Photovoltaic System

In today’s society with increasingly natural resources and increasingly worsening of the earth’s environment,increasing the development and utilization of renewable and clean energy is not only a response to resource scarcity,but also a remedy for environmental pollution.Photovoltaic power generation,as a representative of renewable clean energy,has received strong support from government policies and positive response from all walks of life.So the bidirectional DC-DC converters,which are widely used in photovoltaic power generation,have attracted much attention.Based on the independent photovoltaic power generation system with energy storage device taking the bidirectional DC-DC converter,which can transmit the energy bidirectional,as the research object.The working mode of independent photovoltaic power generation system is introduced,and the modes are summarized and classified.The bidirectional DC-DC converter and its research status are introduced.The working principle of Buck/Boost type bidirectional DC-DC converter is introduced,and the accurate modeling under non ideal condition is carried out.The influence of inductance,capacitance parameters and working frequency of switch tube on its frequency domain characteristics is discussed.This paper focuses on improving the performance of converter by optimizing inductance and capacitance parameters,and proposed a bidirectional DC-DC converter parameter optimization design method.When the inductance parameters are selected,the constraint conditions of the current ripple rate in the full dynamic range of the Buck mode and the constraint conditions of the continuous inductance current in the full dynamic working range of the Boost mode are satisfied.Selecting low voltage side capacitance,the voltage ripple rate of battery is satisfied under the full dynamic working mode of Buck mode.Selecting high voltage side capacitance,we can meet the constraint condition of load voltage ripple rate in the full dynamic working range of Boost mode.Combined with the design example,a simulation model is built in the PSIM software environment.The experimental results verify the reasonableness of the parameter optimization design.Finally,according to the working mode of the independent photovoltaic power generation system and the charging and discharging characteristics of the battery,the parameters of the lag-lead controller are designed under three modes of constant current charge,constant voltage charge and constant voltage discharge.A double closed loop system model of bidirectional DC-DC converter is built in the PSIM software environment.The experimental results verify the rationality of the controller parameter design.The experimental platform is built,and the rationality of parameter optimization design and controller parameter design is verified through experimental results.