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The wireless sensor node makes use of energy harvesters in order to power its modules. However, by nature of these nodes being placed in diverse locations and fluctuating conditions, their energy harvesters obtain unregulated DC voltage. Regulators undertake this problem by appropriately handling the voltage being harvested to power the node. Most regulators today use analog control methods which...
The paper presents a new four-level voltage source converter (VSC). Compared to conventional four-level converters, this proposed converter has fewer components and can be used for a higher power density system in low and medium voltage applications. Its principles and advantages are studied in this paper. The effect of various redundant switching states on the voltages of flying capacitors is analyzed...
Modular multilevel converter (MMC) is a promising topology of Voltage Source Converter based High voltage Direct Current (VSC-HVDC) system with many outstanding advantages such as low switching frequency, low voltage distortion and harmonics. Pre-charge process is one of the core issues of MMC based system, especially for the MMC with DC fault blocking capability. In this paper, considering a novel...
The multilevel converter is a prospective topology for both Medium Voltage and High Voltage Direct Current (HVDC) applications. In high power application, the forward topology is applied to increase the power region. In this paper, a novel forward-mode five-level inverter is presented which combines the features of the conventional multilevel converters and forward topology. The converters can transfer...
With the continuous development of high frequency inverter technology and multilevel inverter technology, all kinds of novel high frequency multilevel inverter are put forward and studied. And among them, the interleaved flyback three-level inverter (IFTLI) has a better work performance. In this paper, the control methods of single-phase IFTLI will be studied in-depth. Firstly, the instantaneous voltage...
Cascaded multilevel inverter (MLI) topologies have received an attractive solution for grid connected PV system. In this paper, two-cascaded MLI topologies are presented for grid connected PV system. These are seven level cascaded H-bridge multilevel inverter and three phase cascaded voltage source multilevel inverter. In both presented MLI configurations, each PV module is connected to one DC-DC...
The paper proposes a three phase nine level T-type neutral point clamped (9L-T-NPC) inverter for medium voltage induction motor drive. The primary objective of the proposed inverter is to improve the output voltage quality with reduced number of devices and passive components. The generation of nine levels in the output pole voltage is achieved using only ten switches per phase. Although the similar...
Performance analysis and output voltage regulation of a cascaded step-up switched-capacitor converter (SCC) under zero voltage switching (ZVS) condition is analyzed in this paper. The ZVS condition (converter operation above its resonant frequency) provides 1) zero-voltage switching, which leads to a relatively higher efficiency compared to zero current switching (ZCS) under the resonant frequency...
DC capacitor voltage imbalance is an inherent problem limited the further development of multi-level Neutral Point Clamped (NPC). In this paper, a new hybrid control method based on Space Vector Pulse Width Modulation (SVPWM) for five-level NPC at high modulation index and high power factor is presented. By choosing appropriate switching pattern in lower modulation index sectors and collocating different...
A capacitor voltage-balancing control strategy based on switching state redundancies is proposed for the hybrid stacked five-level converter. In order to obtain the balancing properties for flying capacitors, a hybrid model in state-space representation is established by considering the continuous and discrete variables. The proposed balancing strategy can control the flying capacitor voltages to...
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...
The modular multilevel converter (MMC) has become the most promising converter technology for high power applications. However, to get more number of levels in the output voltage, a conventional MMC requires large number of submodules. The main technical challenges of an MMC, with a large number of submodules, are the requirement of large number of semiconductor switches, submodule capacitors and...
In this paper, an asymmetric mixed MMC topology of multilevel converter for bipolar HVDC transmission systems is introduced. Among the existing MMC topologies for the bipolar HVDC systems, the asymmetric mixed MMC topology provides the benefits of: a lower number of submodule cells, fewer switching devices and lower conduction losses. Furthermore, the HVDC based on asymmetric mixed MMC can be flexibly...
Owing to economic aspects, Central inverter is the dominating candidate in large scale PV installations despite its lower energy harvest compared to other topologies like string inverters especially under partial shading conditions. In this paper a new voltage balancing topology is introduced to enable better energy yield from central inverters. The proposed topology is characterized by its fractional...
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...
This paper proposes a single-phase AC converter with an active power decoupling circuit operated in DCM (discontinuous current mode) for PV (photovoltaic) systems. The proposed converter consists of an H-bridge single-phase AC converter and a boost converter, and a compensation circuit employed with a small capacitor for the power ripple. In many active power decoupling topologies that have been studied,...
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...
To improve light load efficiency, a three-phase photovoltaic (PV) based microinverter may operate in single-phase, two-phase or three-phase mode depending on the available input power. Therefore, its DC link capacitor may be subjected to large peak-to-peak voltage ripple when operating in phase skipping mode. This paper determines the minimum value of the DC link capacitor by allowing the maximum...
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...
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