Designed Of Staggered Parallel Flyback Photovoltaic Grid-connected Micro Inverter

As a pollution-free renewable energy,solar energy which is characterized by each piece of photovoltaic panels connected to a miniature inverter is being widely developed and applied around the world.Photovoltaic power generation is one of the hot spots of solar energy.The micro inverter is the core equipment of the photovoltaic power generation system,which can convert the DC output from the photovoltaic panel into the same phase AC power into the grid.The power quality of the PV grid-connected inverter will directly affect the stability of the grid,so it is very important to improve the conversion efficiency and power generation quality of the inverter.Based on the simulation model of photovoltaic cells,the characteristic curves of different temperature and light intensity are analyzed.This paper proposes the improved variable step perturbation observation method which solves the contradiction between the traditional disturbance observation method and the tracking speed and the control precision and achive the maximum power point tracking of the power generation system.The pre-stage of the designed PV grid-connected micro inverter is the structure of interleaved flyback.The characteristics of the flyback micro-inverter are analyzed,and the characteristics of the fly-back miniature inverter in the working CCM mode and the stress of the components are analyzed.The results show that the system control strategy for the continuous current mode is more stable and reliable.The active clamp circuit added in the flyback converter can not only improve the DC-DC conversion efficiency,but also to achieve MOSFEF tube zero voltage switch.The inverter uses the initiative frequency detection method which can effectively detect the islanding effect of PV grid-connected inverter.In Matlab / Simulink,the simulation model of interleaved flyback photovoltaic power generation system is established,and the selected topology and control algorithm can meet the performance requirements of PV grid micro inverter.Finally,the appropriate component models are selected by the calculation of components parameters of the system circuit.Then micro-inverter inverter prototype is designed by Microchip’s dsPIC33FJ16GS504 digital signal controller for the control of the core of the interleaved flyback inverter.The 200 W photovoltaic grid-connected micro-inverter experimental platform is set up in the laboratory.Then grid-connected experiments is carried out,and island detection and inverter conversion efficiency are counted.The total current harmonic and island detection reaction time are in line with the relevant provisions of the national standards,and inverter power conversion efficiency is also more ideal.In this paper,the simulation of the waveform and the experimental waveform fully verify the feasibility of the designed photovoltaic grid-connected inverter.