Carrier-PWM Control Strategies of Three-Level Converters

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