BAHIA, F. A. C.; DA C. BAHIA, FILIPE A.; BAHIA, FILIPE A. DA C.; http://lattes.cnpq.br/9798218730942618; BAHIA, Antônio da Costa.
Resumen:
This work is focused on the study of multilevel CC-CA converters capable of produces a
high number of output levels using a small number of isolated DC sources and, in gen-
eral, number of components. In this context, three topologies based on the Neutral-Point
Clamped (NPC) converter employing a single isolated DC source and two other structures
based on the Modular Multilevel Cascaded Converter (MMCC). Systems based on NPC
converter consist of multilevel inverters with cascaded transformers coupled only to three-
level NPC legs or associated with three-level NPC legs and two-level legs, where one of
them is shared between transformers. These conĄgurations are analyzed considering two
scenarios of transformers, one symmetric and another one asymmetric. Systems based on
MMCC converter consist of asymmetric cascaded multilevel inverters, where each phase
is composed of a three-level H-bridge and a nine-level H-bridge connected in series. The
nine-level H-bridges are constructed from the MMCC, while the three-level H-bridges are
operated in two ways, or using DC source and or using Ćoating capacitor. These conĄgu-
rations are investigated using the asymmetric DC voltage ratios of 1:8 and 1:12 between
the H-bridges. For one of these topologies, an operation analysis of the converter and
the stress equations that describe the system model are presented. From the analysis of
possible combinations of swicthing states, modulation strategies are also developed. In
addition, are used to compare and evaluate the performance of the topologies investi-
gated the following main criteria: number of components and levels; nominal power of the
transformers; voltage, current and rated frequency of the power switches, total harmonic
distortion (THD); losses in semiconductor devices and transformers; and common mode
voltage. Finally, the simulation and experimental results are presented and discussed for
the validation of the topologies studied.