| At present,power electronics technology is widely used in renewable energy power generation.Inverter as a key power electronic converter,its performance directly determines the quality of renewable energy power generation.Traditional inverters show good application performance in conventional inverter applications such as motor drive,induction heating,and automotive lighting.However,due to its own shortcomings,traditional inverters cannot effectively play an important role in renewable energy power generation.The Z-source inverter can suit to a wide range of input voltage changes,eliminate dead time and achieve single-stage buck-boost conversion,so it is widely used in new energy power generation.However,the Z-source inverter also has some shortcomings,such as high voltage stress of passive devices,discontinuous input current,the presence of start-up inrush circuit and limited boost ability.In order to overcome the above-mentioned shortcomings,various improvements are needed.First of all,this thesis conducts an in-depth study on the new topology based on Z-source network,two basic evolution principles are proposed and named as combination principle and power supply embedded principle.Each evolution principle is given a detailed introduction and its future application is prospected.Inspired by two principles,a new topology structure--improved power supply embedded Z-source inverter is proposed.Compared with the existing topology,this new topology has the advantages of strong boost capability,continuous input current,low voltage stress of passive devices,and fault tolerance of single power supply.Secondly,the relationship among the shoot-through duty cycle,boost factor,voltage gain and modulation index under different control strategies is calculated.By comparison,the advantages and disadvantages of the new topology under various modulation strategies are analyzed.Thirdly,the state-space averaging method is used to establish small-signal model,combined with the requirement of the ripple coefficient of passive device,to provide a theoretical basis for its selection.Finally,this thesis uses MATLAB/Simulink and experimental prototype to simulate and verify the new Z-source inverter.Simulation and experimental results show that the topology improves the boosting capability,widens the value range of the modulation index,ensures the fault tolerance of single power supply failure,and reduces the voltage stress of passive devices.The feasibility and accuracy of the new topology are verified. |
