| With the development of human society and the improvement of people's living standards, the human's demand for energy is increasing, while the traditional non-renewable energy sources are depleted day by day, and serious environmental pollution is caused in the application process, so green energy came into being. Solar energy, as one of the representatives, wins people's attention. photovoltaic power generation is a very important way for the full use of photovoltaic energy. Inverter is the core of grid-connected PV system, in this paper, in-depth study is made towards the inverter circuit, network control technology, the achievement of maximum power tracking circuit, and the maximum power tracking method of the two-stage photovoltaic inverter system.Firstly, we analyzed the types of photovoltaic cells, principle, equivalent circuit, and the output characteristics; At the same time, we studied the working principle of the single-phase full-bridge inverter circuit, and improved the grid control technology based on deadbeat control algorithm.Secondly, in this paper, we analyzed several DC-DC circuit which can achieve the function of MPPT, then built the DC-DC circuit model in the Matlab/Simulink simulation environment. By comparing, Boost step-up chopper was used as the front-end circuit. Taking the 2.5kW Photovoltaic Inverter for example, we analyzed how to determine the main parameters in this circuit.Again, basing on researching the various traditional maximum power point tracking methods, a improved method, combining the advantage of both P&O and Hysteresis Comparison, is proposed to solve the drawbacks of traditional methods.Finally, three models, which include the photovoltaic cells model, the Grid-connected inverter model, and the corresponding control system model ,are built in the Matlab/simulink simulation environment. The simulation results verified the feasibility of both PWM deadbeat control algorithm and the improved MPPT. |
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