The Research Of Push-pull Miniature Photovoltaic Grid-connected Inverter

With the development of economy and society, the demand for energy in human societyis growing, while traditional fossil energy reserves are limited and will pollute theenvironment, so look for clean and non-polluting energy is a new agenda on the world.Theadvantages of widespread distribution, clean,non-polluting, inexhaustible, etc make solarenergy become attention by various countries.Grid-connected PV echnology is the maindirection of solar power. This article studies the topology and control methods of thelow-power photovoltaic grid-connected system, and elaborates the design of hardware andsoftware in200w photovoltaic grid-connected system.Firstly,This article analyzes the output characteristics of photovoltaic cells and proposedseveral photovoltaic maximum power point tracking technology (MPPT),and select thevariable step hysteresis law as a front-end circuit control and simulation its in Matlab.Then this article compare the advantages and disadvantages of the various topologies indifferent parts of the photovoltaic grid-connected system and choice a suitable for the microinverter design.The topology is to tier architecture, through the grid current control level afterthe full bridge inverter circuit output, to realize the control of grid-connected photovoltaicsystem. The network control strategy of later class divide into the grid-voltage control and thegrid-current control grid, here use the latter method to achieve photovoltaic grid inverters andnetwork operation, through compare of several current control strategies, then chosedouble-loop current control strategies and simulate the entire system.Finally, the design of the hardware and software to micro-grid PV system in detailed andgives the design of system structure, the main circuit component selection, the control circuit,the sampling circuit and the system software design process. To make the output current ofinverter with the same frequency and phase to grid voltage, here use a software PLL to lock-inphase of the grid voltage and described the principle and software processes in detail.The simulation and experimental results showed that: the system can implement the required performance of supplying power to grid perfectly. The system works stabilization andhas good performances.