A Comparison on PSO Variants in Calculating HEPWM Switching Angles for a Cascaded H-Bridge Multilevel Inverter Norkharziana Mohd Nayan, Naziha Ahmad Azli and Shahrin Md. Ayob Abstract This paper presents a comparison study on the application of various PSO algorithms in calculating the Pulse Width Modulation (PWM) switching angles of a cascaded H-bridge multilevel inverter. It aims to investigate the behavior of the PSO algorithm in three different variants. The results are compared to determine the most suitable algorithm for optimizing the multilevel inverter output voltage through Harmonic Elimination PWM (HEPWM) switching technique. Keywords Particle Swarm Optimization  Harmonic Elimination PWM  Inverter 1 Introduction Multilevel inverter plays an important role in medium to high power conversion application. The applications include active power filters, static var compensator, unified power flow controller (UPFC), electric vehicles, and industrial motor drives [1–4]. Harmonic Elimination Pulse Width Modulation (HEPWM) offers N. M. Nayan (&) School of Electrical System Engineering, Universiti Malaysia Perlis, 02000 Kuala Perlis, Perlis, Malaysia e-mail: iana@ieee.org N. A. Azli  S. Md. Ayob Department of Energy Conversion (ENCON), Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia e-mail: naziha@fke.utm.my S. Md. Ayob e-mail: shahrin@fke.utm.my James J. (Jong Hyuk) Park et al. (eds.), Computer Science and Convergence, Lecture Notes in Electrical Engineering 114, DOI: 10.1007/978-94-007-2792-2_30, Ó Springer Science+Business Media B.V. 2012 315