Performance analysis of a modified reduce component count multilevel inverter

Abstract

Reducing component in circuitry is desirable in many innovations. In multilevel inverter (MLI) perspective, the increasing of switching devices for a higher-level output will significantly increase power losses, thus affected the output harmonic distortion. In this paper, an extended and simplified three-phase reduce component count multilevel inverter (RCCMLI) structure adapted from S. S. Lee, Cascaded Compact-Module Multilevel Inverter (CCM-MLI) is demonstrated and analysed. Symmetrical reduce component structure with H-bridge inverter is considered in this work. For simplification purpose, the current path conduction for reverse current is not demonstrated in this paper. A simulation-based result is presented to observe the performance of RCCMLI with regards to its output voltage harmonic content. Related predetermined parameter values are included in this report. Particularly, this paper verified the aforementioned RCCMLI, but in higher level and three-phase application, which will further improve the pseudo-sinusoidal inverter output as it eliminates the triplens harmonic component compare to single-phase environment. As for the lower order odd harmonics elimination, computational algorithm namely Particle Swarm Optimization (PSO) has been implemented in the RCCMLI control strategy. In comparison to the traditional Cascaded H bridge (CHB), this work finds that employing the switching angle optimization in the proposed RCCMLI produce comparable improvement in minimizing the output voltage harmonic and able to bring the output quality closer to comply with IEEE 519 distortion limit with fewer components and compact size inverter.