Research And Design Of Photovoltaic Grid-connected Inverter

Since entering the 21 st century, the limited fossil energy is accelerated consumption, forcing human being in a serious energy crisis. To achieve sustainable development, green renewable energy has been widely used, and the solar energy has been favored because of its unique advantages. Solar power has short construction period, no pollution, no noise, high stability, etc. The solar power has become a new trend of energy utilization.The single-phase grid connected inverter is designed according to the basic principle of the photovoltaic power generation. The inverter main circuit selects two levels of structure, the former level DC- DC converter uses a push-pull circuit, after level DC- AC converter adopts full bridge inverter circuit. In accordance with the requirements of technical indicators to design the main circuit, including the selection of the power switch tube, the design of high-frequency transformer, filter circuit and absorption circuit design, etc. Based on the comparison of several common MPPT control algorithms, such as disturbance observation method, conductance increment method and fuzzy control method, uses fuzzy control disturbance observation to achieve maximum power point tracking. Through the Simulink simulation analysis, the results show that the algorithm can effectively track the maximum power point of photovoltaic system, and has advantages of fast response speed, low power consumption. Inverter using current inner loop and voltage outer loop double closed loop control strategy, the current inner loop consists of no beat control, the voltage loop consists of PI regulator and digital phase-locked loop. And under the environment of simulink simulation analysis, the results showed that no beat frequency closed loop control of the output waveform is stable, it can achieve grid connected current and grid voltage synchronization. Finally, chooses TMS320F2812 as main control chip to design grid inverter control system, the hardware design mainly including push-pull driving circuit, sampling circuit and inverter drive circuit, software design including the SPWM procedures, AD conversion program and PID, etc.The paper using TMS320F2812 as main control chip to build experimental platform, the design of 1 k W photovoltaic grid inverter for experiment, the experimental results show that the design can achieve the desired effect.