Research On Multi-level Inverter Based On Zeta

Compared with the two-level inverter,multi-level inverter has many advantages such as low voltage stress on power switches,small harmonic content of output voltage and good electromagnetic compatibility and so on.However,traditional voltage-source multilevel inverters almost can achieve buck converter only,which has a strong limitation in practical applications.Especially in the high-power new energy generation field such as solar and wind power generation,the multilevel inverter is required to have a wide range of input voltage.In order to meet this requirement,this paper presents a single-stage non-isolated buck-boost multi-level inverter topology which is studied in this paper.Firstly,this paper presents a multilevel inverter topology based on Zeta circuit by reading and analyzing a large number of domestic and foreign literatures.The topology is simple,the control is flexible,it can realize the single-stage buck-boost inverter,and has the ability of resisting the disturbance of input side.And then,this paper analyzes the principle of the three-level inverter topology based on Zeta in detail,and the basic relation of the circuit is deduced and the parameters are designed according to the working principle of the topology.The unipolar carrier phase-shift is used for the the multilevel inverter with three-level inverter,which can increase the equivalent switching frequency of the inverter without increasing the carrier frequency.Through this modulation the working principle of the five-level inverter based on Zeta and the self-balance of capacitor voltage are analyzed in detail.Finally,the mathematical model of multilevel inverter is designed,and the closed loop controller is designed by analyzing the mathematical model.And the closed-loop simulation of input disturbance and output disturbance is carried out,which show that the multi-level inverter has a strong ability to resist the disturbance of input and output.In order to verify the correctness of theoretical analysis and simulation results,a1000 W experimental prototype is built based on Zeta three-level inverter and five-level inverter in this paper.The experimental results prove the correctness of the theoretical analysis and simulation results.