Study of pulse width modulation techniques for two level three-phase voltage source inverters

Abstract

This thesis contains a very organized study on the pulse width modulation techniques applied to two-level, three-phase voltage source inverters. It begins by showing and explaining the operating principles of a two-level inverter topology together with basic concepts of pulse width modulation which include the modulation index, switching frequency, and harmonics generated. The main discussion is detailed carrier-based PWM techniques as well as space vector-based modulation methods.

The classical sinusoidal PWM and third-harmonic injection PWM will be analyzed in terms of their output voltage characteristics and harmonics performance. Output voltage characteristics comparison between advanced modulation techniques comprising space vector PWM, discontinuous PWM with emphasis on switching behavior besides loss reduction through minimum conduction losses is also brought out. A comparative study among different strategies based on aspects like output voltage quality (THD), switching losses together with complexity involved for realization concludes this thesis.