Analysis of Dual Flying Capacitor Active-Neutral-Point-Clamped Multilevel Inverter Induction Motor Drives

Abstract

This thesis aims to extend the knowledge about the performance of different multilevel inverter induction motor drives through harmonic analysis. Large electric drives and utility applications require advanced power electronics converter to meet the high power demands. As a result, multilevel power converter structure has been introduced as an alternative in high power and medium voltage situations. Hybrid multilevel converters combine features of conventional multilevel topologies to provide an acceptable tradeoff between the advantages and disadvantages of these converters. For many industrial applications, common dc link is a requirement that limits the choice of topologies to neutral point clamped (NPC) and flying capacitor multicell (FCM) hybrid types. This paper investigates the operation of a hybrid five-level topology and proposes a modulation method that takes the advantage of the combined features of NPC and FCM. The dual flying capacitor (FC) active-neutral-point-clamped (DFC-ANPC) converter provides certain advantages such as natural soft switching of line frequency switches, elimination of the transient voltage balancing snubbers, and a more even loss distribution. Simulation results and verification of the five-level DFC-ANPC converter are presented to validate the performance of the converter as well as the applied modulation technique.. In particular, aspects of total harmonic distortion (THD) and modulation which are required or desirable for multilevel converters are discussed.