Research On High Gain DC/DC Converter

In recent years,the rapid development of science and technology has promoted the tremendous progress of human society,but the cost is the huge consumption of traditional fossil energy and serious environmental pollution.Therefore,the development and utilization of clean,renewable,safe,and cost-acceptable new energy sources has become particularly important.However,in the new energy power generation system,there are problems such as low output voltage and susceptibility to environmental impacts,which cannot meet the needs of photovoltaic power generation grid-connected.Therefore,design of the DC/DC converter with high gain,wide input and easy control is an important key to solve the new energy generation grid connected system.At the same time,with the increase of installed capacity of new energy power generation,photovoltaic power generation system,wind power generation system,fuel cell system and other new energy power generation systems are more and more popular for DC/DC converters with special performance.Traditional step-up DC/DC converters such as traditional Boost,quadratic Boost,switched inductor Boost and switched capacitor Boost converters,have made great contributions solve the problems of low output voltage,high switching stress and low conversion efficiency of power generation system,and have the characteristics of power factor correction(PFC).This thesis first analyzes the working principle of the existing step-up DC/DC converter.The study shows that the voltage gain of the converter can be effectively improved by introducing the switched inductor/capacitor structure and making use of the working characteristics of the switched inductor/capacitor charging in parallel and discharging in series.At the same time,the design of the filter structure has the characteristics of reducing the stress of the components and improving the conversion efficiency of the converter.Based on this research idea,three types of DC/DC converters are proposed,they are non-isolated modified quadratic Boost converter(Chapter 2),non-isolated switched inductor/capacitor converter(NSI/C)(Chapter 3),and high gain DC/DC converter(Chapter 4).In Chapter 2,3 and 4,the voltage gain,switch voltage/current stress,diode voltage/current stress,inductor parameter design,capacitor parameter design,component losses and efficiency of the proposed converters are derived,and the boundary conditions of Continuous conduction mode/Discontinuous conduction mode(CCM/DCM)are given.And in Chapter 4,the mode analysis of the high-gain DC/DC converter working in DCM is analyzed,and the voltage gain of the converter working in DCM is derived.Then,the small signal model of the system is established,and the system transfer function is derived.At the same time,each chapter compares the performance of the proposed converter with the current existing converters.It is verified that the proposed converters have features of high gain and low stress the simulation and experimental results.Finally,the number of components,voltage gain,switch stress,and efficiency are compared among the proposed converters.The three types of converters have their own advantages and disadvantages,which provide people with more choices when facing complex work situations.