Study Of Micro-inverter Without Electrolytic Capacitor In Photovoltaic Generation System

At present,photovoltaic is the main application mode of solar energy.Comparing with the other inverter structure,the ac modules system that is composed of photovoltaic cell and micro-inverter has the advantage of high power expandability,less shading effect,and easy monitoring.But the electrolytic capacitor affects the lifetime of the whole micro-inverter,which restricts its large-scale use.Therefore,it is necessary to improve the topology of micro-inverter so as to reduce the decoupling capacitance,thus allowing for long lifetime film capacitor to be used.This paper introduced the development and the present research results of the micro-inverter,and selected the flyback inverter as the basic object of study.The working principle of the flyback inverter described in detail.The simulation results indicate that the power ripple with twice power frequency will reduce the efficiency of photovoltaic cell.So it is necessary to add active power decoupling circuit to suppress ripple.By analyzing the principle of power decoupling,a novel three-port micro-inverter is proposed in this paper.The proposed topology is based on three-port flyback inverter with one port dedicated to power decoupling function so as to reduce the decoupling capacitance.The working principle and control policy is described in detail.The theoretical analyses are studied in MATLAB/SIMLINK simulation platform,including the photovoltaic cell model.The simulation results indicate that the proposed topology only need 50?F decoupling capacitance in 305 W photovoltaic power generation system,so that we can use the film capacitor to replace electrolytic capacitor as the decoupling capacitor,and improve the reliability of the whole system.