Design And Implementation Of The3KW Photovoltaic Grid-Connected Inverter System

With the development of the social and the growing demand of the people, thetraditional energy is increasingly scary. The solar energy is non-pollution, widedistribution, abundant. So it is paid more attention. In this thesis, through the research ofphotovoltaic grid-connected inverter system, a3KW photovoltaic grid-connected invertersystem is designed. Through the experiment, proves that it meets all the demand.The principle of solar cell is analyzed. Establish a mathematical model of solar cell,then give out the I-V and P-V curves; pointing out the necessity of maximum powerpoint tracking (MPPT) of the solar cell. After comparing different maximum power pointtracking algorithms, select the improvement of perturbation and observation method.Through the comparison of the structure of photovoltaic inverter system, we usetwo-class inverter structure, and DC/DC converter and DC/AC converter structure havebeen analyzed; Through analyzing the advantages and disadvantages of current controlmethod, using repeated PI control. By simulation on Saber software, verify the validityof maximum power point tracking and repeated PI control algorithm.Based on the theory above, the hardware and software of entire system are designed.Finally complete the entire experimental platform. The efficiency of maximum powerpoint tracking and the grid-connected inverter efficiency in different power stage aretested. The maximum power point tracking efficiency, the machine efficiency and thegrid current’s total harmonic distortion of the whole system are given in this thesis. Theresults show that the system meets all the demand and the system has good performance.