The Design Of Grid-connected Photovoltaic Inverter

It is known that photovoltaic system is one of the cleanest, most practicable, most promising resource in all kinds of renewable energy resources nowadays. The research on the basal theory and the experiments on solar power generation should be carried out. The photovoltaic system is highlighted in this paper to transform solar energy into electrical energy maximum.In the paper, by analyzing photovoltaic array model and its output characteristics, the method for maximum photovoltaic power tracking is proposed. Based on the characteristic of photovoltaic array and further research on photovoltaic system and its control strategy, a control scheme based on DSP is designed. There are two stages in the control system that can realize maximum photovoltaic power tracking (MPPT) and produce sine wave current that is in-phase with grid. At the same time, the islanding protection for photovoltaic system is analyzed. The solving scheme for islanding for the scheme is given in the paper.By deep analysis and research, the system is designed. Based on the scheme of the control system, the design thought of the system's main circuit and its parameters are introduced. This paper also includes the control circuits whose core cell is TI's digital signal processor TMS320F2812. The design of drive and protection circuit and system's EMC are introduced in detail. In addition, the software and hardware of improved SPWM current tracking control and unity power factor control are given.The experiment results demonstrate that the system can implement the control scheme proposed in this paper perfectly and obtain the required performance of supplying power to grid perfectly.