Implementing selective harmonic elimination in multilevel inverters with optimal dc source

Abstract

In this paper, the bird swarm algorithm (BSA) is proposed for selective harmonic elimination (SHE) implementation in seven-level inverters. The SHE technique reduces switching frequency and, as a result, inverter losses, by using BSA to expedite the process of identifying optimal switching angles. The computational load is substantially reduced by BSA-based SHE-pulse width modulation (SHE-PWM), in contrast to conventional techniques that require solving transcendental nonlinear trigonometric equations. Furthermore, SHE-pulse amplitude modulation (SHE-PAM) removes additional harmonics from the output voltage of inverter by optimizing both the switching angles and the amplitude of the dc source voltage. This improved technique allows for more flexibility, eventually leading to a decrease in total harmonic distortion. SHE-PWM and SHE-PAM are shown to be effective for a seven-level inverter through a simulation study in the MATLAB/Simulink environment and an experimental study on a laboratory prototype.

Keywords

• Multilevel inverter (MLI)
• Pulse-amplitude modulation (PAM)
• Pulse-width modulation (PWM)
• Selective harmonic elimination (SHE)
• Total harmonic distortion (THD)