The Design Of Photovoltaic Inverter Power Supply With Double Close Loop Control Based On Fuzzy Self Tuning PI

The inverter is the only one power converter stage of grid-connected PV station, whose efficiency and reliability will influence the performance of the whole system.This paper research on an integrated scheme of design photovoltaic independent system, and mainly research on the design method of software and hardware system of inverter power supply.The hardware system include push-pull topology frame, full-bridge inverter, output voltage compensation methods and driving units of SPWM signals. Achieved the true maxim power point trace of solar array by adapting an improved MPPT control,which trace the current resistance.The power switch VMOSFET transforms the input voltage DC into PWM, the AC voltage is raised by push pull topology frame and high frequency transformer, then rectified into 310V high voltage DC, and at last the high voltage DC is inverted into AC by full bridge converter. The high perfermance DSP microcontroller TMS320F2812 is used to implement of the producing of SPWM signals, the sample of output voltage signals, the fuzzy control algorithm. Through testing this equipment, it could be proved that this topology has really satisfied with the request of efficiency and reliability for grid-connected PV station.The software system includes the algorithm of double close loop based on fuzzy self tuning PI. First, with the theory analysis of the output characteristic of inverter, the paper set up complete MATLAB simulation model of single phase SPWM inverter basing on the mathematic model of inverter. Second, in order to get high capability inverter, the paper combine intelligent control with conventional control and summarizes the new designing scheme of single phase inverter basing on the mathematic madel and simulation model: designing scheme of double close loop control based on fuzzy self-tuning PI. The paper makes experimental research for its designing scheme of double close loop based on fuzzy self tuning PI. The simulation results show low THD of output voltage waveform and the system achieves good dynamic and static characteristic. This control schemes can satisfy the controlling require of inverter.