Estudo e comparação de sistemas de acionamento para aplicações de alta potência e média tensão

Abstract

This Ph.D. Thesis proposes a comparison of modulation techniques, semiconductors devices technologies and topologies for multilevel inverters, in order to point out the multilevel drive system that presents the best performance for a given application. Initially, a comparison methodology is proposed which is based on selecting the switching frequency where all systems present 99% efficiency. The performance indeces included in this analysis are: semiconductor devices power losses, heat-sink volume, THD, DF1, DF2, common mode voltage and harmonic spectrum. For each topology of multilevel inverter it is made a comparison among the modulation techniques and semiconductor devices to obtain the set (modulation + semiconductor) that presents better overall performance. After, the comparisons for each topology, a comparison among the sets that present better results is made, leading to the choice of the best system for a given specific application. The modulation techniques that present the best performance for each multilevel inverter are implemented on an FPGA. Experimental results, such as inverters efficiency and output voltage waveform, are presented for a reduced scale prototype, with the intention of validating the models employed in this Phd Thesis.