| Many governments take more and more attention on the solar energy generating systems because of its sustainability and cleanliness. Thereinto the grid-connected photovoltaic generating has the most significant value in both theory and practice. Grid-connected inverter is the crucial part of the generating and its hardware design and control algorithm is the cutting-edge of the field. Based on the research results of thease years, this paper proposes a design of 5kW photovoltaic grid-connedted inverter, and takes much effort in the inverter hardware design, control algorithm research and simulation.The three-phase grid-connected photovoltaic inverter is consisting of a DC-DC converter and a DC-AC three-phase inverter. As to DC-DC converter, it uses multi-string structure and unattached MPPT control method which realize independent control in branches and solve the problem of power miss-matching between branches. As to DC-AC inverter, it uses three-phase PWM rectifier structure and space vector pulse width modulation (SVPWM) pattern, which increase the utilization of DC voltage and decrease the harmonic injected into the grid. Based on analyzing the theory of the inverter, simulation results are given to validate the feasibility of control algorithm, and the characteristics and control algorithm of the inverter with different input voltages are discussed also.This paper carries out the details in the hardware design of the inverter in the aspects of detecting and protecting circuit, power circuit, main circuit and so on which can give some suggestions for the hardware design of inverter with similar structures.
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