三电平变流器多载波PWM控制技术研究

Carrier-PWM Control Strategies of Three-Level Converters

摘要:

对二极管箝位型和飞跨电容型两种三电平变流器拓扑的多载波PWM(脉冲宽度调制)控制策略进行研究，重点对这两种拓扑结构中存在的中点电位不平衡问题,以及不同拓扑结构所适用的多载波PWM方法,进行了理论分析和论证;通过 Matlab/Simulink软件的仿真研究，分析了在不同调制度下输出电压的谐波分布和谐波畸变率，确定了载波层叠法与载波移相法的拓扑结构实用类型，论证了多载波PWM控制策略的实用性和可行性.

关键词:三电平变流器; 多载波PWM控制; 中点电位偏离; 谐波分布

Abstract:

This paper presents researches on the pulse width modulation(PWM) strategies and the principal for three-level diode-clamped and flying-capacitor converters,especially,the neutral-point unbalanced problem and the control strategies for different topological structures.An investigation was made of the harmonic wave distribution and the aberration rate of the line-voltage in different modulation rates on the basis of the Matlab/Simulink software,which determines the practical topology types in two different modulation strategies(phase disposition and phase shift).Both the theoretical and experimental results prove its practicability and feasibility.

Key words:three-level inverters; carrier-PWM strategies; neutral-point departure; harmonic-wave distribution