Research On The Control Method Of Single-phase PV Inverter

With the development of human society, the demand for energy is growing, but the traditional non-renewable energy is reducing. According to the storage report of the twenty-first Century petrochemical energy, the world energy has entered a statement of crisis. The energy situation of China is not optimistic, so seeking new alternative energy sources has become a hot point in every country. The reserve of solar energy is rich, without geographical restrictions and pollution, which is the human’s ideal new clean energy. Now the biggest obstacle of restricting the development of solar energy is the cost of power generation is too high, among which the main factor is the cost of solar cell too high, at the same time efficiency photovoltaic inverter is lo. Thus improving the efficiency of inverter power inverter is one of methods to reduce the cost of photovoltaic power generation.Firstly, this paper introduces the structure of single-phase photovoltaic inverter power firstly, through the analysis and compare the structures of DC step-up link and AC inverter link. The DC/DC part adopts BOOST step-up circuit, and the DC/AC part adopts the single-phase full bridge inversion structure. According to the inverse structure, it establishes the mathematical model of a single phase photovoltaic inverter;Secondly, it introduces the PID double-loop control, fuzzy control and double closed-loop control of fuzzy self-tuning, which are always used in the single phase photovoltaic inverter power supply, but when these control algorithms connected rectifier load, the steady state and robustness of the control system is poor. Repetitive control with high control accuracy, can be perfectly track the control signal, the output error can reach0in principle, so this article adopts the repetitive control to solve this problem. The output of Repetitive control with a cycle of delay, which inevitably makes the system dynamic response slower, for this problem, the article proposed a kind composite control method which combine fuzzy tuning of combining PI dual closed-loop control with repeat control composite control, using fuzzy self-tuning PI control improve system dynamic performance, repetitive control improve steady-state performance of the system. Based on the established mathematic model of single phase photovoltaic inverter power, we establish the simulation model of the single phase photovoltaic inverter power source control system with the use of MATLAB, and the PID double closed loop control, fuzzy self-tuning PI double loop control, repetitive control and composite control are simulated,simulation results show that the steady-state and dynamic performance of the composite control is the most excellent, and its anti-interference is strong, and have a high precision control, the maximum output voltage error is3.4V, THD1.06%, so this method reaches the expected requirements. finally, the paper uses DSPLF2407A of TI company as the main control chip, and designs the software of the single-phase photovoltaic inverter power supply system. Through the experiments, it verifies the complex control based on repetitive control.