The Design And Simulation Research On Transformerless Single-phase Photovoltaic Grid-connected Inverter

With an increasingly serious problem of environmental pollution and energy shortage, the development and use of renewable energy has been put on the world countries'most important agenda. With its advantages, such as large reserves, pollution-free, easy access , solar energy has always been global concerned. 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.This paper, based on the analysis and study of different topologies of photovoltaic power generation photovoltaic, design a transformerless inverter system applied to low frequency and small power PV grid system. And by analyzing the reason of common mode current produce , an improved three-level diode clamped inverter structure has been proposed to be main circuit topology.With various PV maximum power point tracking methods analysed, the paper adopts incremental conductance method as the control algorithm. By analysing the features of traditional incremental conductance algorithm,the improved variable step incremental conductance algorithm was presented ,which is based on power detection. Finally, build the circuit simulation model and the simulation results confirmed the correctness of the design.By using MATLAB/Simulink simulation software, the photovoltaic cells, voltage transformation, PWM and other sectors were well designed. Through making use of these modules, it can be convenient and efficient realization of the inverter and the network simulation session. Finally set up a complete simulation system and obtain simulation results.The results verified the good characteristics of theoretical study of the system.