Research On CLLLC Resonant Bidirectional DCDC Converter

With the increasing maturity of power electronic converter technology,traditional LLC resonant converters,as a representative of DC/DC converters,is important such as DC microgrids,electric vehicles,energy routers and so on.However,traditional LLC resonant converters have some problems in terms of soft switching characteristics,bidirectional energy flow,voltage input range,which require more in-depth research.To aim the problems of unidirectional energy flow and narrow voltage input in the traditional LLC resonant converter,a CLLLC resonant bidirectional DC/DC converter based on new control strategy was proposed.First,the structure was designed.The left and right ends of the isolation transformer were symmetrical structures.When the converter worked in forward mode,the left side of the transformer was network circuit,the right side was network circuit,its' structure realized bidirectional conversion of highlow voltage side energy of the DC bus.Secondly,the working process was analyzed,and the model of it was built by using the basic wave analysis method,and got the voltage gain transfer function when the input voltage was 700?750V,VF control was used,and when 750 V switched to PS control,the input voltage range was widened.Finally,the parameters of the converter,the hard-software program of the converter were designed,and the simulation of converter was carried out.The experimental results verified that the converter achieved a bidirectional flow of energy under the premise of meeting the soft switching characteristics,and a stable voltage output in a wide voltage input.It can find through research,experimental analysis that the proposed resonant converter realized the bidirectional flow of energy from the structure,and solved the problem of unidirectional energy transfer in the converter.And the input voltage was widened,and the problem of output voltage instability caused by input-side voltage fluctuations in the DC micro grid was solved.And the soft switching feature of the traditional LLC resonant converter and the efficiency of the converter were improved.Figure48;Table2;Reference 45.