| Photovoltaic (PV) grid-connected generator is more convenient than the other renewable sources in transforming green energy into electric energy, which is convenience to use. So, the research on the grid connected photovoltaic generator has an important meaning in nowadays especially the electric energy is widely used.Photovoltaic grid-connected inverter control and solar array maximum power point tracking (MPPT) control are the two core part of PV grid-connected system. In the photovoltaic grid-connected control aspect, an improved fixed-switching frequency current control strategy is adopted, after analyzed the control model of the system, a simulation with MATLAB is carried out, and a high quality injected sinusoidal current as well as unity power factor at the grid interface is realized.In the maximum power point tracking aspect, by analyzing photovoltaic array model and its output characteristics, a new approach for tracking the maximum power point is presented. The single parameter output current is used for control purposes for MPPT, rather than double parameters-its input voltage and current. Then the development course of MPPT control method of the inverter with two stages transform structure is introduced in this thesis, and the simulation result for the photovoltaic system and its solving scheme is given in the paper. It is shown that using single parameter method avoid the complex operation and simplify the maximum power point tracker controller for only one output parameters needs to be sensed by this approach.By deep analysis and research, the system is designed. Based on the scheme of the control system, the main circuit and parameters of the system are introduced, a sample of 700W grid-connected photovoltaic generator is designed based on the control chip TMS320F2407A.The experimental result proves the system can implement the control scheme proposed in this paper perfectly which solves two key techniques, and set up groundwork for the future research. |
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