The Topology And Modulation Of A Buck-boost Three-phase Five-level Inverter

With the intensification of the global energy crisis and the use of fossil fuel energy,humankind's demand for clean renewable energy is increasing.As the most promising clean energy in the world,wind energy has gradually attracted the attention of countries in the world.As one of the major countries in the world wind power industry,China has achieved remarkable results in the field of wind power generation.In recent years,the total installed capacity of wind power or newly installed capacity ranks first in the world.With the increase of installed capacity of wind power,the rise in voltage level causes the converter switch to withstand an increase in voltage.Therefore,a multi-level converter emerges.Based on the background of the research,this paper proposes the structure of a three-phase system based on a single-phase buck-boost five-level inverter.Based on MATLAB,it was modeled and simulated.The work characteristics of the inverter are analyzed and verified by setting up the hardware platform of the inverter.The main work of this article is as follows:(1)First,aiming at the complex structure of traditional five-level inverters and the deficiencies of excessive power devices,this paper proposes a five-level inverter topological structure with buck-boost and its working principle detailed analysis.Through the comparison with the three classical topological structures and functions,this paper shows that the structure is simple and has the superiority of buck-boost capability.(2)Secondly,two modulation strategies,carrier pulse width modulation and space vector pulse width modulation,are introduced.Since the SVPWM modulation strategy is applied to three-level or higher levels,the switching control of the system is too complicated to control.This paper uses the carrier stacking method to achieve Inverter modulation.The mathematical model of the system is established using Model Predictive Control(MPC)and PI control respectively.Three-phase five-level inverter with buck-boost pressure was used to generate the MATLAB/Simulink.The simulator and its grid-connected control strategy are simulated to verify the correctness and effectiveness of the system structure,parameter design and control strategy.(3)Finally,a hardware experimental platform with a three-phase five-level inverter system for buck-boost was built.The system program was designed based on DSP and FPGA of TMS320F2812.The buck pressure performance of the new topology proposed in this paper was verified through experiments.