Research On Capacitor Voltage Self-balance Of PUC5 Multilevel Inverter

In the 21 st century,environmental protection and energy are the main themes,and it is based on the coordination of energy development,resource utilization,and environmental protection.Medium and high-voltage large-capacity variable frequency speed governor is the direction of development in the 21 st century.Its utilization in life can achieve 20% energy saving and emission reduction,it can improve system performance and conversion efficiency in industry,and it can be used as a comprehensive power flow controller in the national power grid.Can reduce potential safety hazards and improve the reliability of large power grids.In the context of medium-and high-voltage large-capacity variable-frequency speed governors,multilevel inverters have become an important research hotspot worthy of attention.Multi-level inverters used in medium of high-voltage and large-capacity environments can achieve level doubling,reduce switching stress,and improve output waveforms.Clamped multilevel inverters are widely used and the technology is mature,but the inherent voltage balance/balance problem of their topology has always restricted their development.Research and solution of the voltage balance problem of multilevel inverter capacitor/clamping devices have Significant.This paper summarizes the research status of multi-level inverters.Because the clamped PUC inverter derives more levels,the topology is simple,the voltage change rate(du/dt)is lower,and the harmonic distortion is smaller,so it has a good Prospects for development,select the PUC inverter as the research goal of this paper;establish the state space model of the inverter topology and the mathematical function of the switching mode,and establish the coupling relationship between the two;analyze the switching mode of the PUC inverter,by improving Clamp the amplitude of the capacitor,use redundant switches to couple the capacitor's balance control strategy to the inverter control link,and then achieve self-balancing control;for the dynamic and static characteristics of the self-balancing PUC-5 inverter,by establishing s Control strategy model under the domain and z-domain models,analyze and improve the prototype repetitive controller,make compound improvements to the RC controller,and analyze the inherent self-coupling of its parallel compound control,and finally realize the fast response of the zero self-difference tracking effect.Construction of a balanced 5-level inverter;finally,the main circuit and peripheral circuits of the inverter were designed.Using TI's TMS320F28335 chip as the control part,a capacitor self-balancing inverter system of the PUC-5 inverter was built.