Abstract
Multilevel converters are usually used in high power applications to reduce the voltage and current stress of the active switches and meanwhile to achieve better output waveform quality. Recent researches are basically focused on the voltage source multilevel dc to ac converters. Concerning the multilevel current source dc to ac converters, only very few papers are available in the literature. In view of this, the main purpose of this thesis is focused to the study of single-phase current source dc to ac converters. The contributions of this thesis may be summarized as follows. First, a novel configuration of single-phase multilevel current source dc to ac converter is proposed to achieve better performance as compared with that of the existing literature. Second, operation principles of both five-level and seven-level configurations are presented. It turns out that the proposed multilevel configuration can be extended to ( ) level as well as three-phase system easily. Third, a simple carrier signal synthesis technique is proposed to obviate using many logic gates for getting the desired carrier signal. Hence, by comparing the modulating signal with the carrier signal, one can obtain the switching signal easily and more reliably. Fourth, the proposed multilevel converter cannot only be used to generate clean sinusoidal output current but also can be used to track other nonsinusoidal command signals. In other words, it can be used as a low frequency power amplifier. Finally, a prototype is also constructed and experimental results are presented to verify the feasibility of the proposed converter.