Research The Modeling Of Bidirectional DC/DC Converter And Parallel Control Method

This paper is based on the study of the operational characteristics of the bi-directional DC converter(BDC)with energy storage medium,the method of improving the capacitive characteristic of the BDC branch is explored from the point of view of digital control of the BDC,and researches on the energy management methods about the parallel system,to improve the dynamic and static characteristics of the system operation.Firstly,based on the study of the AC small signal model of the BDC system,the equivalent impedance model of the branch system is explored by combining the traditional control means with the state of charge(SoC)of the storage medium.Secondly,the AC disturbance is on the DC bus and introduced by the unbalance between power supply branch and the energy consumption of the load.Based on the impedance analysis of the equivalent model of the system,a virtual capacitance control technique is proposed to realize the DC bus capacitance of the virtual expansion,thereby suppressing the DC bus voltage fluctuations.In this paper,the allowable range of virtual capacitance is obtained by using mathematical analysis,and the problem of high frequency interference caused by virtual capacitance control is analyzed.Simulation analysis is carried out by using simulation tool.In addition,in order to realize the energy management and optimization of the system under the condition of paralleled BDCs,the control method of master-slave control and droop control is studied.In the droop control,the power coordination droop control and the voltage loop coefficient droop control are deeply analyzed,and the operation characteristics of the droop control and voltage loop coefficient droop control method are analyzed.The above methods are verified by simulation and the advantages and disadvantages are noticed.Finally,the experimental platform is designed based on Infineon XE164FN as the control core and the non-isolated bidirectional half-bridge DC converter as the main circuit.The correctness of the model and the effectiveness and feasibility of control of the proposed virtual capacitor are verified in the signal BDC experiment.The feasibility of the research method in all application systems is proved by parallel BDCs experiments.