Research On Control Strategy For Output-parallel Dual Cuk Inverter

In recent years, solar photovoltaic power system has been extensively developed andapplied. In this system, the photovoltaic cell’s output voltage level is lower and itsvariation range is wider. However, the traditional voltage full-bridge inverter can nolonger meet the requirements. So this thesis presents an output-parallel dual Cuk inverter.It can not only boost or buck the input voltage, but also has a good adaptability for the DCside power supply voltage variation, so it can be applied to the photovoltaic power system.Based on a great number of related literature at home and abroad, the author connectstwo Cuk converters according to the input-series and output-parallel, and adds in twooption switches of the convertor. Then a single-stage structure of dual Cuk inverter isproposed. This thesis analyzes the working principle of the inverter separately when it isinputted by the two power supply and single power supply. Based on this analysis, asingle-stage structure of dual Sepic inverter is proposed in this thesis. Besides, the authormakes its principle analysis and simulation studies.The thesis analyses small-single Modeling to the Cuk converter, and then completethe simulation study of the inverter combining both the two power supply and singlepower supply through voltage closed-loop and current closed-loop control. In order tosolve the problem of uneven distribution of capacitor voltage, this thesis proposes twocontrol schemes: a redundant switch method of voltage sharing between input-capacitorand the modulation wave corrected method of voltage sharing between input-capacitor.The working principle of the two schemes has been analyzed by theory and simulation,and the results proved the effectiveness of the two methods.At last, on the basis of theory research and simulation results, a prototype is built inlab. The experimental results are given to verify the effectiveness of the theoreticalanalysis and control strategy.