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This paper proposes a multilevel open-end six-phase motor drive. The system is composed of six isolated three-leg inverters and is adequate for high-power systems with voltage rating restrictions. The system model and a simple space vector pulse-width modulation (PWM) based on three similar individual planes are presented. Specific voltage vector application sequences that reduce the stator voltages...
This paper proposes two hybrid asymmetric cascaded multilevel inverters. Both inverters consist of the series connection of a three-level (3L) H-bridge cell and a nine-level (9L) H-bridge cell with an unequal dc voltage ratio of 1:8. The topologies of the 9L H-bridge cell are based on modular multilevel cascade converter (MMCC) with double-star chopper cells (DSCC). Both the proposed inverters can...
This paper proposes possibilities of Y-connected three-leg topologies, that are built from combinations of two-level and three-level legs (hybrid structures). Therefore, four topologies are studied and compared in aspects such as harmonic distortion of output voltages and rating of power switches. Additionally, semiconductor losses comparisons in different scenarios of load (either high current or...
This paper investigates two converters composed of a five-level H-bridge cell cascaded with a three-level one. Two types of 5-level H-bridges are used, the first one is composed of a NPC leg and a 2-level leg (in the first topology), and the second one is composed of NPC legs only (in the second configuration). In both topologies the 5-level cell is cascaded with a 3-level H-bridge. Both converters...
This paper discusses a power rectifier based on a cascaded topology composed of a three-leg cell and three H-bridge cells. Each leg of the three-leg cell is cascaded connected to an H-bridge cell. Since different types of converter are series-connected, the topology is assumed to be hybrid. The capacitors of the H-bridge cells operate as floating capacitors. It is shown that the discussed topology...
In this work an ac-dc-ac multilevel power converter is investigated. The developed configuration is composed of one single-phase ac-dc-ac three-leg module and two H-bridges, one of them connected in the shared part of the system to employ multilevel voltages to input and output converter, and the other one connected on the grid side for input overvoltage. The converter is employed in applications...
This paper proposes a single-phase ac-dc-ac converter composed of two three-leg converters connected in series with an H-bridge on its grid side. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental overvoltage...
This paper proposes a single-phase ac-dc-ac converter composed of a transformer and two three-leg converters connected in series. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental over-voltage and voltage...
This paper proposes two universal active power filters (UAPFs) configurations for single-phase systems using four-legs ac/ac converters. The proposed configurations are used for disturbances compensation in grid voltage and current. The proposed topologies are compared to the conventional structure. For this comparison, harmonic distortions, semiconductor losses and average switching frequency are...
In this paper, a new topology of three-phase series voltage source converter is proposed, which is cascaded with the three-phase system by means of only two single-phase or one two-phase transformer. The proposed cascaded converter is presented as a DVR, which compensates for voltage sags and swells on the main power supplier. In this scenario, it is compared to the conventional three-phase DVR, which...
In this paper, three configurations of three-phase ac-dc cascaded converters are presented. They are referred as basic configurations, and are composed by two three-phase bridges, where the second bridge is cascaded to the first by means of a three-phase injection transformer. Basic configurations have one bidirectional option (composed only by IGBT switches), and two unidirectional ones (composed...
This work studies three-phase four-wire dynamic voltage restorers (DVRs) based on a cascade of open-end winding transformers. The possible proposed topologies can be observed if each transformer set is connected to the conventional two-level (2L) three-phase four leg converters and two dc-links per stage. However, in this paper particular/intermediate solutions are also considered by means of the...
This paper investigates a multilevel inverter composed of series/parallel-connected H-bridges. The presented structure can be used for applications in which is intended to use semiconductor switches with low voltage and low current rating. A comprehensive system model to control the circulating current, an overall control strategy to adjust the output voltage with constant magnitude and frequency,...
In this paper, a new hybrid multilevel six-phase machine drive system topology is proposed and investigated. Such topology is composed of two three-level three-phase neutral-point-clamped (NPC) inverters and a traditional two-level three-phase voltage source inverter (VSI) with isolated DC-links feeding the open-end windings (OEW) of a six-phase induction motor (SPIM). The system model, operating...
This paper presents a universal active power filter (UAPF) based on single-phase ac/dc/ac converters with five legs. The proposed topology has multilevel voltage, reduced total harmonic distortion (THD) in current, and low weighted total harmonic distortion (WTHD) in voltage, when compared to conventional four-leg structure. The proposed UAPF is feasible to compensate reactive power, swells in grid...
This paper investigates an ac-dc-ac multilevel power converter. The studied configuration is composed of two single-phase ac-dc-ac three-leg modules and series-connected H-bridges in the shared part of system. The converter is employed in applications with same input and output frequency, such as uninterrupted power supply (UPS) and unified power quality conditioner (UPQC) without isolation transformer...
This paper presents three three-phase AC-DC configurations in which two are unidirectional and have reduced switch count. The investigated topologies have one DC-link and are composed by two converters in series connection through transformers, that process part of the total power, while the conventional converters have two DC-links and a transformer processing all the power. The replacement of switches...
Four unidirectional AC-DC-AC three-level and two-level three-leg converters are proposed in this paper. This converters are composed of an unidirectional rectifier and a bidirectional inverter, using three-level and two-level legs and an unidirectional NPC leg at rectifier side. When compared with the two-level leg, the three-level leg presents voltage stress reduction on switches for the same DC-link...
This paper introduces an asymmetric cascaded multilevel inverter consisting of series-connected two nine-level (9L) H-bridge cells, which are based on modular multilevel cascade converter (MMCC) with double-star chopper cells (DSCC). An unequal dc voltage ratio of 1:2 is used, so that the proposed topology can generate 25 output voltage levels. A modulation strategy for the inverter is proposed. A...
An unidirectional AC-DC-AC three-level three-leg converter is proposed in this paper. This converter is composed of an unidirectional rectifier and a bidirectional inverter, using two bidirectional NPC legs and an unidirectional NPC leg. A bidirectional NPC leg is shared between rectifier and inverter. When compared with the two-level leg, the three-level leg presents voltage stress reduction on switches...
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