Research On Topology Of High-gain Inverter

With the rapid development of science and technology,energy shortage has become the primary problem.Therefore,to maintain rapid economic and technological development,the energy crisis must be resolved.As a representative of new clean energy,solar energy is favored by all countries.Solar photovoltaic power generation technology is an important measure for people to exploit solar energy.It has the characteristics of clean and pollution-free.In the sustainable development strategy,photovoltaic power generation has broad application prospects.The inverter is an important part of the photovoltaic power generation system,and the inverter can transfer and convert energy.Traditional inverters contain voltage source/current source inverters,but both of these inverters have some defects,such as low voltage gain,which requires adding devices in the front stage to achieve the purpose of boosting.In order to solve this problem,Professor Peng Fangzheng has proposed a new type of inverter-"Z-source inverter".Compared with the traditional inverters,the Z-source inverter has a greatly improved boosting capability,and allows the upper and lower arms of the inverter bridge to be turned on at the same time.However,the Z-source inverter still has the problem of discontinuous input current and high voltage stress.Therefore,on the basis of Z-source inverter,scholars have developed series inverters: quasi-Z-source inverter,switching Boost inverter and so on.The traditional Z-source inverter,the quasi-Z-source inverter and the switching Boost inverter are studied,and the topology and working principle of these three inverters are also analyzed.On the basis of traditional inverters,three types of high-gain inverters are proposed in combination with switching inductor and capacitor structures,namely "High-gain Switching Boost Inverter","Input Current Continuity High-gain Quasi-Z Source Inverter" and "Improved High-boost Quasi-Z Source Inverter".The High-gain Switching Boost Inverter is based on the Improved Switching Boost Inverter adding a switching inductor structure.This structure not only improves the inverter’s boost capacity but also makes the input current continuous;the Input Current Continuity High-gain Quasi-Z source Inverter is based on the quasi-Z-source inverter,which introduces an improved high-gain Boost three-terminal boost structure in the front stage.The output gain of the proposed inverter has been effectively improved,the advantage of continuous input current is retained,and the voltage stresses on the diodes are reduced.The front stage of the Improved High-boost Quasi-Z Source Inverter is a boost structure composed of switching inductors,switching capacitors and switching tubes.Under the same duty ratio condition,the inverter of proposed has a higher output voltage,and the component voltage stress is lower.Compared with traditional Boost inverters,these three inverters have the advantages of high gain and low voltage stress.The topology and working principle of the proposed inverters are analyzed in detail,and the modal equations under different working conditions are derived.According to the volt-second balance principle of inductor and the principle of capacitor ampere-second balance,the DC output voltage and the voltage stresses and current stresses on the device are calculated.The detailed calculation process of capacitor and inductor device parameters is given.The performances of the inverters are compared with other inverters with similar topologies.The proposed inverters have the characteristics of high boost and low voltage stresses which are proved by the comparison and analysis.The simulations are conducted based on the modulation methods for the proposed inverters.The simulation results and theoretical calculation results are compared and analyzed,which proves the correctness of the theoretical analysis and the feasibility of the proposed inverter.