Comparative Study between Different Modulation Strategies for Five Levels NPC Topology Inverter

Abstract

The object of this paper is the study of various modulation strategies applied to the five-level inverter neutral-point-clamped NPC topology. Firstly we presented the structure of the voltage inverter three-phase five-level NPC topology. After that we model the inverter and the inverter are controlled by different strategies and then we made a comparative study between the results given by different strategies

Application of Firefly Algorithm on the SHEPWM strategy for the multilevel inverters

“…-to replace in the system (8) the values of S i by +1 for the angle where there is a jump of lower level to the upper level and -1 for the contrary case [4].…”

“…. In this study we were interested to eliminate the first harmonic (5, 7, 11, 13 ...) in the case of three-phase inverters, which are the most troublesome for voltage and therefore embarrassing for the ideal operation loads such as electric motors [4]. Because of the characteristic of the wave, which is, symmetrical compared to the half and the quarter of period, the Fourier series will be simplified and the study will be limited only to the first quarter of the period of this wave.…”

“…The system (8) must be solved by a numerical method (Newton-Raphson) [4,6,10] or Genetic Algorithms [7,8]. In this work the Firefly Algorithm (FA) will be used to solve the system (8).…”

“…The decomposition in Fourier series, who only show the existence of harmonics of odd natures [4,7,8,10], is given by:…”

“…among the best known strategies we find the Selective Harmonic Eliminated PWM strategy [4,8] (SHEPWM) which is the subject of this work. This strategy consists in calculating the instants of switching of the switches of the inverter to have a shape nearest sinusoidal.…”