Research On 3KW Single-phase Nonisolated Grid-connected Photovoltaic Inverter

With an increasingly serious problem of environmental pollution and energy shortage, the development and use of renewable energy has been put on the worldcountries most important agenda. Solar energy is one of the most clean, practical and large scale regeneration energy resources. The whole world focuses on the use of photovoltaic (PV). There are many ways to make use of solar energy, and photovoltaic grid-connected power generation can represent the development direction the best, becomes the mainstream of solar energy application. Grid-connected inverter as the core component of photovoltaic grid-connected system also has been extensively studied. With the whole single-phase photovoltaic grid power system as the research object, the paper focuses on the analysis of photovoltaic inverter link, and presents implementation scheme based on DSP control of the non-isolated grid-connected photovoltaic inverter.Firstly, the paper summarizes the background significance and development prospects of photovoltaic power generation, analyzes the photovoltaic industry and the status of the distribution at home and abroad, then introduces the work principle and classification of photovoltaic power generation, discusses the topology structure of povoltaic grid power system. Designing system software and hardware (including the main circuit design and its main components, control protection and auxiliary circuit, software development environment and software control process) is introduced.During the proeesses of developing PV energy generation system, power transformation technology, anti-islanding equipment, photovoltaic grid control technology are researehed. And on that basis, SPWM power transformation method of asynchronous single polarity rules sampling, the aetive frequeney drift with Periodieal disturbance and Positive feed baek method is Provided to detect islanding based on the aetive frequency drift(AFD) anti- islanding method, the deadbeat current control algorithm are putted forward.Then once more, Studying the special key problems-- Problems of Common-mode Current, Dc Component and EMC-- of nonisolated grid-connected photovoltaic inverter. The paper puts forward the design method of common mode filter based on common mode system; The causes of DC current injection into the grid from grid-connected PV inverter are analyzed, and the corresponding hardware and software solutions are putted forward.Base on this methods, A 3KW single-Phase Photovoltaic grid-conneeted inverter is designed. Experiments show the correctness and feasibility of the methods this paper proposed.