Digital simulation of multicarrier PWM strategy for multi-level inverter

Abstract

This paper presents a design of a Multi-Carrier Pulse Width Modulation (MCPWM) Strategy for an eleven level inverter. The emergence of multilevel inverters (MLI) has increased since the last decade. They are suitable for high voltage and high power applications, due to their ability to synthesize waveforms with a better harmonic spectrum. Numerous topologies have been introduced and widely studied, for utility and drive applications. Multi-level inverters are commonly modulated, by using multicarrier pulse width modulation techniques, such as phase-shifted multicarrier modulation, and level-shifted multicarrier modulation. Amongst these, the level-shifted multicarrier modulation technique produces the best harmonic performance. This work studies a multilevel inverter with equal DC sources, using the level shifting MCPWM technique. By applying this concept, harmonics can be eliminated, and in the output voltage, the Total Harmonic Distortion (THD) can be improved. A procedure to achieve the appropriate level shifting is presented in this paper.