As the most important part of photovoltaic power generation system, the PV inverter will be hardto control and cost more when connected to the grid as single generation. So some scholars proposeda conception of distributed power supply system (micro-grid, or nanogrid). With the advancing studiesof distributed power supply system, the DC distributed power supply system has drew more attentionto the research institutes all over the world. The DC distributed system brings a lot of advantages: lessenergy connections, higher efficiency and easier to control. On the other hand, it can also be benefit tothe development of distributed power supply system.It has been mainly researched on the PV interface converter based on the DC distributed powersupply system in this paper. In consideration of wide range of input voltage and high efficiency,thetopology has been chosed as Boost-Buck converter,which brings the characteristics such as allowingflexible control, having same level of input and output voltage, continuous input and output current.Choices are made on the working modes of the Boost-Buck converter,regarding decreasing theswitching loss.The operation principle is analysed, and the parameter design for the main componentsare presented.In order to meet the demand of the DC micro-grid, the total control strategy for the converter isnoted.The same compensatior is used in different modes to reduce complexity.Based on the model ofPV cell and small signal model of Boost-Buck converter, the compensator is designed to insure thestability, fast response and the smooth transition of all the modes and loops. Simulation results basedon saber simulator are provided to demonstrate the right design of the components and theeffectiveness of the compensator.According to the proposed requirements, finally, this paper gives a design prototype of3kW,including its main power circuit and control circuit. The experiment result shows the correctness ofthe PV interface in topology and its control theory. |