| In the grid connected power system of renewable energy,such as solar energy and biomass energy,the voltages of photovoltaic(PV)array and fuel cell are far lower than that of the grid-connected inverter.Therefore,the high step-up high efficiency DC/DC converter is required to realize voltage matching.The high step-up DC/DC converter with coupled inductor uses the turn ratio of coupled inductor to realize high-gain transformation,and it has the advantages of simple topology and high reliability,which is the focus of the current study.In order to further improve voltage gain and efficiency,different kinds of the high step-up DC/DC converter with coupled inductor have been researched,however,the interconnection between them is not clear,therefore,the study of these converters is not systematic and comprehensive enough.Because of the existence of coupled inductor,the input current ripple of the high step-up DC/DC converter with coupled inductor is very large,which leads to a low power generation efficiency,meanwhile,shortens lifespan of photovoltaic(PV)array and fuel cell.So it is significant to implement research on how to reduce the input current ripple.In this paper,based on the existing high step-up DC/DC converters with coupled inductor,the interconnection between them is revealed at the first time,and the converter which has better performance is determined by analyzing the merits and demerits of these converters.According to the study of the methods to realize zero input current ripple,and in combination with the converter which is determined,zero input current ripple high step-up DC/DC converter with coupled inductor is obtained.The main research contents and research achievements of this paper are as follows:Firstly,the advantages and disadvantages of the basic coupled inductor DC/DC converters are analyzed;according to its deficiencies and based on the existing literatures,a solution method is deduced and proposed,and the deduction of different kinds of coupled inductor DC/DC converter's topology is obtained systematically,more importantly,the merits and demerits of each converter is also clarified,the interconnection between them is further illustrated.Next,a relatively outstanding high step-up DC/DC converter with coupled inductor is obtained.Secondly,based on the outstanding high step-up DC/DC converter with coupled inductor,a zero input current ripple construction is added,and the passive zero input current ripple high step-up DC/DC converter with coupled inductor is obtained.The working principle and performance characteristics of the converter are analyzed,ultimately,an experimental prototype is built to verify the correctness of the theoretical analysis.Finally,by further analyzing the circuit features of the passive zero input current ripple high step-up DC/DC converter with coupled inductor,a three winding zero input current ripple DC/DC converter with coupled inductor is obtained.The three winding coupled inductor realizes the function of high voltage gain and zero input current ripple at the same time,therefore,the topology configuration is simplified and the power density is improved.And an experimental prototype is built to verify the correctness of the theoretical analysis. |
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