Study On Improved Y-Source Inverter With The Capability Of Absorbing Bus Voltage Spike

With the serious problems of climate and environment caused by the excessive use of fossil energy,the renewable energy represented by solar energy and wind energy has been valued and developed.Among them,take the photovoltaic distributed generation system as an example,since the direct output energy is unstable DC energy,if a conventional inverter is used to transform the electrical energy,the grid connection may fail.Moreover,in order to prevent the upper and lower arms of the inverter bridge from turning on at the same time,the dead time needs to be added,which will cause the quality of the AC power output by the inverter to decrease.In addition,due to the low DC voltage output by photovoltaic power generation equipment,if it use a traditional inverter,it need to add a multi-stage DC boost circuit before,which will make the control of the energy conversion system more difficult and bring risks to the stable operation of the system.In order to solve the above problems,high-gain inverters represented by Z-source and Y-source inverters came into being.First of all,this paper introduces the research status of Z-source inverter(ZSI),Y-source inverter(YSI)and their improved topology,and briefly analyzes their characteristics and discusses several common voltage spike absorption circuits.Then,the relationship between voltage and current of the improved Y-source inverter(I-YSI)is analyzed,and the influence of leakage inductance on the working state and the conditions to avoid intermittent working state are discussed.In addition,the small signal model of the I-YSI is built,and the influence of the change of inductance and capacitor in the Y-source network on the dynamic performance of the system is analyzed through the zero-pole diagram.The closed-loop control strategy of bus voltage based on capacitor voltage feedback is designed.In order to avoid the bus voltage spikes caused by leakage inductance endangering the normal operation of the inverter,based on the I-YSI,combined with the traditional voltage spike absorption circuit,an improved Y-source inverter with the capability of absorbing bus voltage spike(SI-YSI)is proposed.This topology makes full use of the structural characteristics of the I-YSI,and further improves the DC voltage gain on the basis of ensuring the bus voltage spike absorption capacity.Through the analysis of the relationship between voltage and current,we can understand its working principle,and improve the universality of the voltage spike absorption circuit,so that it can be more widely used.Finally,the circuit parameters are designed and I-YSI and SI-YSI are simulated,and then do experiments to verify the correctness of the previous analysis of the inverter’s working principle and the effectiveness of its ability to absorb bus voltage spikes.