| Nowadays, the problem of environmental pollution and energy shortage become more serious, make people pay more and more attention on the development and utilization of new energy sources. As one of the many new energy, solar energy is accepted commonly for its clean, economic and other advantages, photovoltaic (pv) grid generation as the main form of solar energy use draw the worldwide attention. Photovoltaic grid-connected inverter is the core component of grid-connected photovoltaic system, whose efficiency and reliability will have a significant impact on the performance of the power generation system.This paper gives a detailed theory analysis and simulation about the problem of common-mode current based on the single-phase full bridge topology in non-isolated grid-connected photovoltaic system, choose the full bridge with ac bypass topology as inverter main circuit, and timing of work is analyzed. Summarized and compared several common output current control mode, and gives the voltage, current instantaneous feedback two-ring control scheme.According to theoretical analysis and research, for a given index, completed the design of the experimental prototype’s hardware and software. In the hardware, the method of choose switch tube, the design of control circuit based on TMS320F2812, the design of drive circuit and sampling and protection circuit are expounded; In the software, the main program of control system, the interrupt service program and the design of digital PI adjuster is discussed in detail, and emphatically introduces the implementation method of digital phase locked loop.Based on the above analysis and research, a3kw single-phase non-isolated photovoltaic grid-connected inverter DC-AC transform prototype is developed, completed the experimental debugging, got the experimental results. By analyzing the test waveforms, verify that the work performance of inverter DC-AC transform prototype is reliable, control strategy is practical and feasible. |
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