Current fed multilevel converters for high current power applications

Abstract

The majority of the worldwide installed power inverters today are voltage source inverters followed by current source inverters where the concluding decision lies with the performance of the applications besides the usual economic reasons. Recent active development in the current source inverter areas has seen the emerging of various generalized multilevel current source inverter topologies analogous to the existing multilevel voltage source inverter families. To date, the multilevel current source inverter families have been classified principally by the physical appearance of their basic structures and also by the number of current sources employed. The existing multilevel current source inverter topologies are unpopular for present applications due to reasons such as big sizes, high control complexity and low reliability; which circumstances are often associated to massive component counts and multiple requirements of current sources. Therefore, this research has been focused on the single-phase single-source generalized multilevel current source inverter for this apparent advantage; where this thesis proposed a novel generalized multilevel current-source inverter topology with the lowest component utilization while employing just a single current source. In addition, the proposed topology can conveniently achieved dc current balance with a simple low frequency switching strategy for the five- and nine-level current outputs. From comparison analysis, the proposed topology has significantly less number of components employed compared to the nearest topology, which implies low implementation cost. The experimental results verify the characteristics and performances of the proposed topology acquired by computer simulations.