Study On Topoliges Of The High Step-up ZVS Bidirectional DC/DC Converter

Today,with the global energy resources being scarce and the deterioration of the ecological environment becoming increasingly serious,the development and utilization of solar energy and other clean and renewable energy sources have attracted worldwide attention.The output of photovoltaic cells is unstable,so an energy storage system is introduced to enhance the stability and reliability of the entire system.In order to complete the bidirectional transmission of energy between the energy storage system and the high-voltage bus,this paper proposed a high-gain soft-switching bidirectional DC/DC converter.The converter has the advantages of lower duty cycle,lower switching loss and lower voltage stress under the same voltage conversion ratio.Based on this,the converter formed by two parallel combination methods is deduced,which improves the original converter power processing capability.The main research content of the thesis and the research results obtained are as follows:First of all,this paper summarized the types and characteristics of existing high-gain converters,Analyzed the voltage gain,switching mode and voltage stress,the converter obtained by combining the switched capacitor and the boost converter is selected for further study.Aiming at the hard switching problem of the converter,an improvement method is proposed to form a new type of high-gain soft-switching bidirectional DC/DC converter.Secondly,in order to improve the power handling capacity of the converter,the high-gain converter in Chapter 2 is expanded with the input parallel and output parallel connection.Through circuit analysis,the auxiliary inductance of the expanded circuit is functionally reused to further simplify the circuit and obtain a high-gain soft-switching bidirectional DC converter.Finally,the conversion unit is equivalently converted to a floating type unit and a non-floating type unit,which were applied to the input parallel and output series combination method to obtain a floating type high gain soft switching bidirectional DC/DC converter that can further improve the voltage gain.