Research On An Improved Z-Source DC-AC Converter

In recent years,countries around the world are paying more and more attention to environmental issues.People have greatly increased their demand for green energy.DC-AC converters play a particularly important role in the field of green energy power generation,and higher requirements are constantly being put on DC-AC converters.Due to the inherent defects of traditional converters,it is unable to play a good performance in new energy and other fields,but Z-source converters make up for these defects due to their unique performance.The Z-source converter has a simple circuit topology,excellent performance,and good economy.It has always been a research hotspot in the field of converters.With the continuous exploration and improvement of many scholars at home and abroad,the application of Z-source converters in many fields is becoming more and more extensive.Therefore,the improvement of the Z-source DC-AC converter has important theoretical significance and considerable practical value.Firstly,this thesis analyzes the research status of traditional Z-source converters and their derived topologies,and summarizes that most of them have problems such as insufficient boosting capacity,excessive device voltage stress,intermittent input current and the existence of starting shock loops.In view of its shortcomings.the Z-source converter is improved from the aspect of circuit topology.A detailed theoretical analysis is performed on the improved Z-source converter in different modes,and the performance parameters such as output voltage gain,capacitor voltage stress,and diode voltage stress are derived and compared horizontally.Secondly,through analysis of the improved Z-source converter in-depth,the state space averaging method is used to model and analyze the small signal,the transfer function of the converter is derived,and the impact of parameter changes on the dynamic performance of the converter is analyzed according to the pole-zero distribution,In order to make reasonable parameter design to improve economy.Thirdly,the influence of the four control strategies on the performance of the proposed converter is analyzed,the relevant parameter expressions such as output voltage gain and capacitor voltage stress under different control strategies are obtained,make the derivation and analysis of the shoot-through power loss caused by different control strategies.Through comparative analysis,the advantages and disadvantages of the converter under different control strategies and its applicable range are obtained.The DC link voltage is analyzed theoretically and controlled indirectly to improve the stability of the system.Finally,the simulation model of the proposed converter is built using Matlab,and its simulation study is carried out to verify the correctness of the previous theoretical analysis.On this basis,a physical prototype is built.By combining experimental data,the theoretical correctness and feasibility of the experiment are further verified.Through theoretical and experimental analysis,it is concluded that the improved Z-source converter not only reduces the voltage stress of the capacitor in steady state,but also avoids the formation of the start-up surge circuit,overcomes the shortcomings of the input current interruption,and also has the advantage of higher voltage gain.