Single-Phase Converter With Shared Leg and Generalizations

In this paper, a single-phase shared leg converter is proposed along with two generalizations. The basic configuration has three two-level insulated gate bipolar transistor (IGBT) legs and is cascaded on the main power system by means of two injection transformers, such that one of these legs is shared between the transformers. The generalizations are expanded cases in which the converter has N_leg legs. The first generalization is the cascaded shared leg (CSL), where the converter is cascaded by N_leg - 1 transformers, and one of the N_leg legs is shared between all transformers. The second is the modular CSL, where N_mod modules, each one similar to the basic configuration, are cascaded by 2Nmod transformers. The conventional configurations considered for general comparisons are the cascaded h-bridge (CHB) and the cascaded half-bridge (CHfB). In this paper, we show that proposed configurations provide multilevel ac voltages with greater levelsper-switch ratio compared to the CHB. We also show that proposed CSL generalization has practically the same levels-per-switch than conventional CHfB and saves one transformer. Simulations and experimental results are shown to demonstrate proposed configurations performance and feasibility.