Research On 5kW Triple Bidirectional Storage DC/DC Converter

With the extensive use of fossil energy,environmental pollution problems and energy shortage crisis have intensified.New energy power generation technologies represented by wind and solar energy have received widespread attention,but their power output is intermittent,which is an constraint on the development of new energy.Utilizing the energy storage characteristics of the energy storage medium,combining the energy storage system with new energy sources can smooth out fluctuations in the power generation of new energy sources and improve the adverse effects of new energy fluctuations on the grid and load.The bidirectional DC/DC converter can realize the bidirectional flow of electric energy and is a key power electronic equipment in the energy storage system.Therefore,the research on the DC/DC converter is of great significance.The main work of the paper is as follows:(1)Modeling and simulation analysis of the main circuit of the DC/DC converter is the basis for the study of converter control.Traditional modeling and simulation analysis is based on ideal components.Because the actual components and the main circuit have many parasitic parameters,the model based on ideal components is quite different from the actual circuit,so the control device based on ideal model is not suitable for the control of the actual circuit.In order to verify the specific impact of non-ideal factors on DC/DC converter modeling and provide a basis for the design of control links,this paper considers the parasitic parameters of non-ideal components in the actual circuit,and models the Buck converter and Boost converter respectively.The transfer functions of non-ideal and ideal triplet Buck converter and Boost converter are obtained.By comparing the transfer function and simulating by Matlab,and analyzing the influence of non-ideal factors on the modeling and control of the converter.(2)In order to reduce the charging current ripple,this paper chooses a triple bidirectional DC/DC converter as the energy storage converter,and adopts a control strategy that combines a voltage outer loop and a three current inner loop to achieve the purpose that parallel three-way current sharing and output current ripple reduced.Based on the established non-ideal converter model,this paper uses control theory to design voltage loop and current loop controllers,builds a closed-loop control system in Matlab/Simulink,and conducts simulation research on Buck mode and Boost mode respectively.(3)On this basis,a control system based on DSP and CPLD is designed,circuits are designed according to functional modules,completing PCB drawing,welding and debugging of the control board.According to the parameter requirements of the 5k W experimental prototype,the electrical parameters of power inductors,capacitors,IGBTs and other components are calculated,and the experimental device is developed.Finally,the feasibility of the control system and corresponding control strategies are verified through the experiments.