Sistemas de conversão estáticos multiníveis monofásicos e trifásicos.

Abstract

Static converters with reduced number of controlled switches have very relevant advantages, such as less complexity, higher reliability and cost savings. Looking for simpler topologies, without losing the amount of voltage levels synthesized, this work proposes eight topologies composed by multilevel static converters, which were separated into three groups. The Ąrst group comprises three unidirectional AC-DC open-end conĄgurations arising from the use of Vienna rectiĄers, which are formed by semi-controlled legs. The second set of topologies consists of series-connected structures resulting from the mixing of two-level legs with three-level NPC legs, and the use of Vienna rectiĄers. Among these conĄgurations, only one is bidirectional. The last part consists of a unidirectional single-phase AC-DC-AC converter comprising three three-level legs, two of which are conventional NPCs. One leg of these two is shared between the grid and load sides. The third leg has reduced number of controlled switches. The analyses of the systems and PWM techniques are presented, as well as, simulation and experimental results to verify the feasibility of the topologies. Semi-controlled converters operate in closed loop so that the voltage and current of the converter are synchronized, avoiding zero crossover current distortions due to the uncontrolled switches. The need for syncronization is due to the synthesis of the switched voltages being dependent not only on the switches states but also on the direction of the converter currents.