Single-phase Single-stage Photovoltaic Inverter Design

Energy is the source of the survival and development of human society . Today, a variety of energy science and technology are developing rapidly. The pace of development and utilization of solar energy is also developing rapidly in this trend. Solar photovoltaic power generation is one kinds of the use in solar energy.Solar radiation energy is the main use of Solar photovoltaic power generation, which collected by solar photovoltaic array. The radiation energy is converted to electrical energy, and then stored by energy collection device or through the inverter converted to electrical energy fed to Grid directly. The main idea of this paper is that using an effective maximum power point tracking (MPPT) outer loop and a proportional-resonant (PR) inner current loop in the single phase Grid PV inverter. The algorithm ensured that the output of the grid inverter is the sine wave with zero static error, and guaranteed the quality of the sine wave (THD). This paper analyzed the circuit topology of the system, control method, sinusoidal current in the process of grid and anti-islanding protection.First, the paper analyzed the status of the solar photovoltaic power generation, and showed the key technology of it, summarized the basic principles of the single-phase grid-connected inverter and the topology of inverter power system. It pointed out that the conversion efficiency of the solar array can be fully improved, and its key technology is the maximum power point tracking (MPPT) algorithms. The efficiency of solar energy can be considerably increased in the entire solar power system through this method.Second, the algorithm of the Controller is the key of the solar inverters. The paper compared the various control algorithms in the current loop, and then proposed the control algorithm named proportional-resonant (PR) in the inverter. Using the PR controllers, the inverter reference tracking performance, compared with conventional PI controllers, can be enhanced. Base on automatic control theory, setting parameters of PR controllers is easy. In order to get a ideal control performance, it is only asked to follow a few basic principles. The proportional-resonant (PR) control algorithm is very appropriated in the object of study in this paper (sine wave optimization problem). The algorithm compared with the conventional proportional-integral(PI) algorithm, its parameters can be adjusted easily. Particularly, PR algorithms can provide a large gain on the frequency for a given sine wave object. It can deal with the harsh demands of generating sine wave (50Hz). Thus, this paper started with the proportional-resonant(PR) control algorithm, and analyzed the characteristics of the algorithm and the setting step of its parameters, then verified it through the simulation in the MATLAB.Finally, with the optimization problem for the sine wave, the paper made some discussions in the factor of the specific hardware, such as electromagnetic compatibility, signal detection circuit, the bridge driver problems in the inverter. With analyzing the composition of the regional hardware, the paper compared various features of similar but different hardware components in the circuit structure, and showed that the approach in the hardware architecture is to maximize the quality of the output current waveform. Although there is a simple circuit structure, and also had a more complex one, But the circuit structure is correct and reasonable since the actual current waveform is very well.