Research On Grid-Connected Characteristics Of Photovoltaic Flyback Micro-Inverter Based On PI Quasi Resonant Control

At present, due to the energy crisis, making one-off energy shortage in large quantities. Development of renewable energy will be the main way to solve the energy crisis. Solar power as a renewable energy had become one of the large-scale development and utilization of renewable energy technologies, and photovoltaic grid power generation was the main use forms of solar energy. The main architecture of grid-connected photovoltaic power generation were centralized, string-based, multi-branch and communication module type. And the ac module type structure was proposed by foreign expert, it was a module with photovoltaic module and micro-inverters were integration directly grid-connected power generation. The communication modular structure could realize the modular design, had a strong ability to resist shadow and the characteristics of plug and play.The modular structure of studied the micro-inverter in the ac module chose to work in the flyback inverter topology under continuous mode (CCM). The topology had a simple structure, the characteristics of high efficiency, especially suitable for small power occasion. But in CCM mode, it was difficult to implement parallel output with the method of direct control grid output current; it was a indirect control method by operating transformer primary side current control connected-grid output current, it was simple, but it made the THD increase of connected-grid output current.Under the condition of the inverter output power changing, the THD of inverter output current may can not meet the requirement of the connected-grid. This paper adopts PI quasi resonant controller to indirect control flyback grid inverter under CCM. The main work and achievements in this paper is as follows:(1) Photovoltaic flyback grid-connected micro-inverter model and features was carried out thorough research. As photovoltaic battery output power changing continuously with the external environment, it made to expand the inverter’s output power range of meeting grid-connected requirements by designing controller.(2) the mathematical model of photovoltaic flyback grid-connected micro-inverter was set up by using the state space averaging method. And the mathematical model of the PI controller and PI quasi resonant controller were set up based on this mathematical model. And the two controllers respectively optimized for the parameters by established the system simulation model on the simulation platform.(3) Using PI controller of the optimizating parameters could only made the grid-connected inverter output the power of meeting the grid-connected requirement under the shine intensity changing from800W/s2to1000W/s2, and using PI controller of the optimizating parameters could made the grid-connected inverter output the power of meeting the grid-connected requirement under the shine intensity changing from200W/s2to1000W/s2.(4) By the PI quasi resonant controller of optimization parameters compared with the PI controller, could be concluded that the PI quasi resonant controller made to expand the inverter’s output power range of meeting grid-connected requirements...