| The bidirectional DC converter in the energy storage system is the key to maintaining energy balance.However,the different topological structures of the bidirectional DC converter are suitable for different voltage levels and power levels.Therefore,this paper combines the actual indicators to perform a variety of bidirectional DC converters.Parameter design and simulation analysis show the advantages and disadvantages of each DC converter in the application.Based on this,the topology structure of the bi-directional LLCL resonant converter and the bi-directional Buck / Boost converter is determined,and the in-depth research is performed on it..Under the control of the synchronous rectification method,the bidirectional LLLC resonant converter will lose the soft switching performance due to the large parasitic capacitance of the secondary-side switching tube.Therefore,this paper uses a synchronous control method to deal with the secondary-side parasitic capacitance.The article explains the principle and effect of the control method in detail,and obtains the transient expression of the converter in each working mode based on the time domain analysis method.Based on this,the characteristics and parameter design method of the converter are obtained.In the design of the bidirectional converter,the article points out that the traditionally controlled bidirectional Buck / Boost converter cannot maintain the stability of the bus voltage.By establishing a small-signal model of the bidirectional Buck / Boost converter,the factors affecting the output voltage stability are analyzed,and the voltage is proposed.Feedforward solution.The parameters of the key components of the converter are obtained according to the design method,and the loss analysis of the converter is performed.A 5kW bi-directional DC / DC converter prototype was built,and the typical working waveform,gain curve and efficiency curve of the converter in forward and reverse operation were given to verify the correctness of the principle and the feasibility of the scheme. |
