Research On Non-bridge Switched-capacitor Boost Multilevel Inverter

The inverter is an important part of the microgrid,so research on the inverter is very important.Multilevel inverters have the advantages of high output power quality,small total harmonic distortion,and need smaller output filters.Therefore,they are widely used in research and application such as microgrids.This paper introduces the switched-capacitor structure into the research of multilevel inverters,and proposes several scalable switched-capacitor multilevel inverters without H-bridge,which have the advantages of high efficiency,high voltage gain,small size,and high filtering efficiency.It is of great significance to make the inverter structure smaller,easier to integrate,reduce the voltage stress of switch tubes and improve efficiency.The main research contents of the paper are as follows:(1)Aiming at the problem of excessive voltage stress on the switch tubes in the existing switched-capacitor multilevel inverter structure with H-bridge structure,a non-bridge switched-capacitor multilevel inverter is proposed.The inverter can realize the inversion process without the H-bridge structure,and the maximum voltage stress on the switch tube is low and remains unchanged,which solves the above problems.(2)Aiming at the problem that the above inverter cannot work under inductive load,a hybrid T-type non-bridge switched-capacitor multilevel inverter is proposed.The inverter has a low maximum voltage stress on the switch tubes and remains unchanged.It can also work under inductive load conditions and increase the number of output levels,which improve the application range of the inverter.(3)There are many switch tubes for the above two inverters.To solve this problem,an X-type non-bridge switched-capacitor inverter is proposed.Compared with the above two inverters,the number of switch tubes is reduced on the basis of the original advantages,which greatly reduces the cost of the inverter.(4)To improve the structure of the inverter in(3),an improved X-type non-bridge switched-capacitor multilevel inverter is proposed,which further reduces the number of components and the cost of the inverter.This paper analyzes the working principles,modulation strategies,and related parameter analysis of the proposed non-bridge switched-capacitor multilevel inverters,and verify the correctness and feasibility of the proposed inverters through MATLAB/SIMULINK simulation and experiment of constructing small power proto-type.