Design On Micro Independent Photovoltaic Power System

With development of economy, human demand for energy has increased quickly, while the energy crisis and environment pollution have become two serious problems. The development and utilization of new energy has become the consensus of the world.Therefore,the value of natural and unlimited use of solar energy makes it the focus of world’s attention.Among them, the independent PV power generation system is an important form of utilization of solar energy. Device research and system design are mainly involved for independent PV power generation system in this thesis.First of all, through the understanding of the current situation of domestic and overseas,then lead into the composed of the photovoltaic power generation system and analyze the working principle of the photovoltaic cells. Simulation model is established.Under different environmental conditions, tested by experiment and the output characteristics are got. The nonlinear of photovoltaic cells is verified, and parameters change with environment. It also shows that it is necessary to study maximum power tracking.The boost circuit is used to implement MPPT.Several control schemes of MPPT are summarized and compared, and the variable step disturbance observer method is selected as the control method in this paper.Push-pull Forward convertor as the main circuit of the step-up module and Full-bridge inverter as the main circuit of the inverter module. The principle of push-pull circuit structure is analysised first.Then calculate the parameters of MOSFET, rectifier diode and output filter to select the appropriate devices. Design the isolated voltage feedback circuit based on TL431 and PC817. In the high frequency transformer design part,through formula calculated we can derivate the maximum power capacity of the core,first-class turns ratio and winding specifications.In the part of DC-AC, including hardware design and software design. In the hardware design, we described the principle of full-bridge DC-AC inverter topology and design RCD Uptake buffer circuit, after class output filter, over-current protection circuit.The software part using C language to give the system with a modular program design plan in DSP2812 development environment CCS3.3, that contains the main program module,the interrupt subroutine modules, AD sampling module, battery charging module with MPPT,PWM flow chart of the subroutine modules.Simultaneously, the paper verify the whole system by experiments, design a 400 W prototype. Experimental results show that the system meets the design requirements,and feasibility of control methods and strategies.