Research And Application Of High Step-up DC/DC Converter

At present,renewable energy sources which have already been used such as photovoltaic,fuel cell and a variety of energy storage unit naturally have the characteristic of low voltage DC output,therefore,as the interface device between renewable energy sources and energy systems,high step-up DC/DC converter plays an important role in micro grid system and renewable energy distributed power generation system and has already been widely applied in the photovoltaic power generation system,fuel cell power generation system,uninterrupted power supply system,the energy storage system and many other fields.With reasonable design of the turn ratio of coupled-inductors,the high step-up DC/DC converter based on coupled-inductors can achieve high voltage gain transformation easily.Compared with other high step-up converters,converter with coupled-inductors has the characteristics of simple structure,high efficiency and convenient control.Besides,Zero Voltage Switching could be realized with the active clamp circuit and reasonable parameter design,thus the switching loss is reduced and switching frequency is improved.Therefore,the research mainly focus on the active clamp high step-up DC/DC converter with coupled-inductors.Specifically,the main work is as follows:(1)The working principle,basic types and the evolution process of topology of the coupled-inductor-based high step-up converter are introduced.Then,the working principle and performance characteristics of the Boost type coupled-inductor-based high step-up converter,including Boost-flyback converter and Boost-forward converter,are analyzed and also verified by the simulation results.(2)On the basis of the converters described above,a novel active clamp high stepup DC/DC converter with double coupling inductances is proposed in this paper.The working principle,voltage gain,stress of components and soft switching conditions of the converter are analyzed and simulation model has been built on Matlab/Simulink.Finally,the converter prototype is built to further validate the theoretical analysis and the contrast experiments and analysis have also been made with the Boost-flyback converter and the Boost-forward converter prototype.(3)The coupled-inductor-based high step-up DC/DC converter is applied to the project ‘design of solar energy street lamps controller based on single lithium battery’,both hardware and software of the system are completed and the basic functions of the controller are realized.