| The increasing environmental problems promote more applications ofbidirectional DC/DC converter in the field of electric vehicle systems andphotovoltaic generation system. Due to the rapid development of Power ElectronicsTechnology in recent years, there have greater improvement of bidirectional DC/DCconverter in efficiency and property.First of all, a topology structure of bidirectional DC/DC converter is proposed inthis paper, which consists of the Cuk circuit unit and Buck-Boost circuit unit. TheWorking Principles of bidirectional DC/DC converter and a commutation process of aswitching cycle are elaborated on the basis of Boost operating mode. The steady-stateof the system and the range of soft-switching are described with the mathematicalformulas, it is concluded that the system has the characteristics of the ZVS switchrange with a full load, low voltage and low current stress, high voltage conversionratio, and so on.The design of dynamic modeling control system of the improved bidirectionalDC/DC converter is elaborated. The analysis of bidirectional DC/DC converter takesadvantage of the method of the state-space averaging, and the state space equation ofsystem is obtained. A small disturbance signal is given to the steady system, andthrough the linear processing, the Small signal AC circuit equations and the outputvariable with respect to the transfer function of the two control variables are gained.According to the double closed loop control of bidirectional DC/DC converter withcurrent inner loop and outer voltage double-loop, the adjustment and design of thecurrent inner loop and the outer voltage loop is made through bode diagram, whichachieved good dynamic characteristics of bi-directional DC/DC converter.Finally, a prototype of bidirectional DC/DC converter (100W) has been designed.The design of prototype consists of the main circuit (transformer design, inputinductor design, switch selection), the drive circuit design and the sampling circuitdesign. The results of simulation show that the topology structure of the improvedbidirectional DC/DC converter is suitable and the control strategy is feasible. |
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