IJSRP, Volume 3, Issue 6, June 2013 Edition [ISSN 2250-3153]
Conventional two-level pulse width modulation (PWM) inverters generate high dv/dt, high frequency common mode voltages and introduces harmonics which is very harmful in electric drives applications. It may damage motor bearings, conducted electromagnetic interferences, and malfunctioning of electronic equipments. Multilevel inverter (MLI) technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. Neutral-point-clamped (NPC) inverters are the most widely used topology of multilevel inverters in high-power applications (several megawatts). This paper presents the most relevant control and modulation method developed for inverters to reduce total harmonic distortion (THD): multilevel sinusoidal pulse width modulation (SPWM). More relevant applications of these converters are laminators, conveyor belts, and unified power-flow controllers. Simulation results obtained in Matlab/Simulink confirms the effectiveness with negligible THD.