Carrier-based PWM Modulation Method for Evaluation of Multi-Level Inverters

This paper describes a simple carrier-based approach for developing and evaluating some of the key performance characteristics of a multi-level inverters. Three types of carrier-based modulation schemes are used to develop variants of a three-level inverter, and are compared in terms of inverter output current, total harmonic distortion, and harmonic components. It is shown that the Space Vector Pulse Width Modulation method increases the inverter output, but with an increase in the total harmonic distortion over that of the Sinusoidal Pulse Width Modulation method. Analysis of simulation results show that the inverter output waveform quality is greatly influenced by the inverter modulation index, frequency ratio, switching frequency, and the filtering action of the connected load. The three-level inverters, nevertheless, show better results than the two-level and six-step inverters.