The Research And Realization Of The Control Method Of The Single-phase Photovoltaic Grid-connected Inverter Based On DSP

Energy crisis and environmental pollution have accelerated the research on regenerative energy. Solar energy is most general of the renewable energy. The photovoltaic grid-connected is one important study direction of the use of solar energy. Grid-connected inverter is the key device of photovoltaic grid-connected system. This paper researches the control method of the single-phase grid-connected inverter, and design 3kW single-phase grid-connected inverter based on DSP.Firstly, through the compare and analysis, the paper delivers the conclusion that the current control model is more reasonabe for the grid-connected inverter. Based on the transfer function of the single-phase photovoltaic grid-connected inverter, which is built by using state-space techniques and small-signal analysis, this paper presented an improved SPWM current control method for grid-connected control. The Simulink simulation model of single-phase current control photovoltaic grid-connected inverter is built based on the above control method.Secondly, because the characteristics of solar cell are strong nonlinear, two usual methods of maximum power point tracking (MPPT) are studied in this paper. This paper adopted an improved perturbation and observation method based on the above research to track the MPP of the solar cell. And the amplitude is controlled by this method.Thirdly, this paper adopted the digital phase lock technique based on asynchronous varying-Frequency modulation algorithm to control the phase and frequency of the refrence current, and the power factor of the grid-connected inverter. Fourthly, this paper presented the design alternative based on TMS320LF2407A aimed at the main technology parameter of 3kW single-phase photovoltaic grid-connected inverter. This paper made a detailed analysis of the hardware and software of the main control part based on digital signal processer (DSP), and built the simulink simulation model which can be realized by DSP. Acording to the requirement of the main control part, this paper made a detailed analysis of the circuit of signal detection.Finally, this paper experimented on the signal detection board and built the hardware platform of the 3kW single-phase photovoltaic grid-connected inverter. The experiments are carried out to validate the control method of this paper.The control method of the single-phase photovoltaic grid-connected inverter researched in this paper effectively solved problems to control of the single-phase photovoltaic grid-connected inverter. The experiment indicates that the power factor, inverter efficiency and the THD of the grid-connected current of the single-phase grid-connected inverter attained or bettered than design standard requests. The system can work stably and attained the anticipated object.