Three-phase Photovoltaic Grid Inverter System Research

Solar energy is the most important renewable energy in the world; the most widely used is solar energy photovoltaic power generation technology, which has become the main trend of the development of photovoltaic grid. In this paper, it studies three-phase photovoltaic grid connected inverter mainly on the mathematical model, maximum power point tracking and control methods, also makes use of TMS320F2812 as the control chip, builds and controls the hardware and software of the experiment model, and verify theory and the correctness of the control method through the operation of the experimental. The main research contents of the paper are as follows:First, the article research background and significance of the brief introduction, the development of domestic and international situation, future prospects, and then PV inverter is introduced, depending on the structure of the classification, and the whole process runs as PV a brief introduction, including some of the major functions module.Secondly, it gives a detailed introduction of the mathematical model of the main circuit topology of three-phase photovoltaic grid connected inverter and the working characteristics of photovoltaic cells. It establishes the boost circuit, uses the DC boosted as the output of the inverter, and the control uses fuzzy control method to achieve the maximum power point tracking to ensure that the photovoltaic battery can work in the maximum power point.And then it sets up the photovoltaic inverter model in different coordinate systems and derives the coordinate transformation of Clark and park. At the same time, it introduces the principle of inverter and the modulation mode, and introduces the control method of SVPWM in detail.Next is the introduction of control strategy of the whole system, it adopts the double loop control of voltage loop and current loop in this paper, uses the method of the combination of repetitive control and PI control in the current control,and establishes related model to implement simulation verification in MATLAB.The final step is the design of hardware and software system, including the further presentation of the TMS320F2812, the introduction of the DSP development environment CCS, selection of parameters of the components, designation of related circuits, software control processes and so on. At last, the control of the hardware system is realized by programming, and then the relevant waveforms of the experiment are analyzed.Through the above description, this design will use the voltage full-bridge inverter circuit as the main circuit, the first stage after boost circuit as the input of the inverter circuit, the use of SVPWM modulation strategy as an inverter, closed-loop control, in order to improve the stability and accuracy of the system will be used to control repetitive control method combining PI control to the completion of the design, through experiments to verify the text used in the control method is effective and feasible.