The Research Of Sine-Wave Power Inverter For Photovoltaic System

The energy of sun is a huge self-born resource, is one of the main substitute of petrifaction resource largely used at present,is one of cleanly resource available by human. Therefore, the exploiture of the energy of sun has a great strategic meaning.This thesis has designed a unattached photovoltaic inverter. The inverter is low cost,high-efficiency, has a simple structure. The output voltage has a high quality and the speed of dynamic response is quickly.The traditional inverter's output come from power frequency transformer commonly. Although the technology is very reliable, but it still has some shortcoming. For example, the volume and weight of the system is huge, the power density is low, it is difficult to carry. And it's price is high with the rise of price of copper.In accordance with the shortcoming of traditional inverter, the article adopt high frequency inverter technology. With DC/DC converter replace power frequency; the main circuit of inverter is Full-Bridge topology; the main job of this article is followed:Use the paralleled MOSFET to driver the push-pull circuit as the DC/DC on the compare with full-bridge, half-bridge and push-pull topology. All kinds of protection are realized. The voltage and frequency precision is under the control tactic with feedforward and feedback. The dynamic of the system is satisfiting.The inverter uses single polarity SPWM to modulate the sine wave signal, devises double closed loops of voltage and current feedback to control the output voltage steadily. The thesis introduces the principle and configuration of double closed loops of voltage and current feedback detailedly, and sets up the mathematics former of full bridge converter's status space, also uses the MATLAB/Simulink to simulate and analyze the control system. Combining the simulation result, the output voltage of the inverter is close to pure sine wave and has high stability, the dynamic response's speed of the whole system heighten greatly when the load varies suddenly, the result accords with the aim of this research.The important operation of inverter power supply is thoroughly analyzed and some formula are deduced. Finally, the principle of operation is illustrated and verified on emulation.