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20 records found

Bipolar DC Power Conversion

State-of-the-Art and Emerging Technologies

This article provides a detailed analysis of the power electronics solutions enabling bipolar dc grids. The bipolar dc grid concept has proven to be more efficient, flexible, and higher in quality than the conventional unipolar one. However, despite its many features, these syste ...
Unspecific peroxygenases (UPOs) represent an emerging class of catalysts for the selective oxyfunctionalisation of C–H- and C = C groups. Until now, only a few UPOs have been characterised. In this study, we report a new peroxygenase identified from the Unspecific Peroxygenase Da ...
Alcohol oxidases (AOxs) catalyze the aerobic oxidation of alcohols to the corresponding carbonyl products (aldehydes or ketones), producing only H2O2 as the byproduct. The majority of known AOxs, however, have a strong preference for small, primary alcohols, limiting their broad ...
In the present work we propose a bienzymatic cascade for the oxyfunctionalisation of cycloalkanes to cyclic alcohols/cyclic ketones. By combining a H2O2-dependent peroxygenase with a O2-consuming and H2O2-producing alcohol oxidase an overall aerobic oxidation system was establish ...
With the increasing popularity of electric vehicles, there is an urgent demand to shorten the charging time, so the development of high-power charging stations with fast chargers is necessary to alleviate range anxiety for drivers. The charging station based on the neutral-point- ...
The development of high-power charging stations with fast chargers is a promising solution to shorten the charging time for electric vehicles (EVs). The neutral-point-clamped (NPC) converter-based bipolar-dc-bus-fed charging station brings many merits, but it has inherent voltage ...
This paper proposes a novel balancing approach for an electric vehicle bipolar dc charging station at the megawatt level, enabled by a grid-tied neutral-point-clamped converter. The study uses the presence of an energy storage stage with access to both of the dc buses to perform ...
This paper presents a generalized multilevel direct power control (ML-DPC) scheme for grid-connected multilevel power converters. The proposed method extends the original DPC operating principle by considering only the closest subset of two-level voltage vectors to the present sw ...
This paper presents a grid-connected seven-level cascaded H-bridge converter operating as photovoltaic inverter. The main issue with this topology are the natural power imbalances between the power cells and the phases of the converter. The control problem is addressed with a Mul ...
This paper proposes a novel architecture for plug-in electric vehicles (PEVs) dc charging station at the megawatt level, through the use of a grid-tied neutral point clamped (NPC) converter. The proposed bipolar dc structure reduces the step-down effort on the dc-dc fast chargers ...
This paper presents a generalized direct power control (DPC) scheme for grid connected multilevel converters. The proposed method extends the original DPC operating principle by considering only for selection the closest vectors to the present switching state. This approach requi ...
This chapter provides an overview of the different charging architectures available for electric vehicles and plug-in hybrid electric vehicles. The charging architectures are addressed following two main categories: onboard chargers, used mainly for slow and semi-fast charging (g ...
During the last decades, AC systems dominated the power transmission and distribution applications almost exclusively. However, a recent convergence of needs originated in different sectors (renewable energy conversion, information technology and transportation) have accelerated ...
This investigation presents a grid-connected five-level H-bridge neutral-point-clamped converter operating with a single dc-link as photovoltaic power source. The operation with a single dc-bus is enabled by adding a transformer with open-end winding secondary, where each power c ...
Large scale grid connected photovoltaic (PV) energy conversion systems have reached the megawatt level. This imposes new challenges on existing grid interface converter topologies and opens new opportunities to be explored. In this paper a new medium voltage multilevel-multistrin ...
This paper presents a new grid connected photovoltaic energy conversion system configuration for large scale power plants. The grid-tied converter is based on a modular multilevel converter using voltage source H-bridge cells. The proposed converter is capable of concentrating a ...
This paper proposes a novel architecture for Plugin Electric Vehicles (PEVs) dc charging stations, through the use of a single dc-link 3-level h-bridge (HB) converter as the grid interface. This feature is achieved by the use of an open-ended secondary windings transformer at the ...
This paper proposes an effective voltage balance control (VBC) together with a new modulation technique for a high-power bidirectional three-level dc-dc converter based fast charger. The proposed VBC method can assist charging stations in balancing the dc-bus voltages so that add ...
The increase in the power levels of photovoltaic (PV) energy conversion systems has resulted in new large-scale grid connected configurations that have reached the megawatt level. This substantial increment in the power levels imposes new challenges to the grid interfacing conver ...
This paper proposes a bipolar-dc-bus Electric Vehicle (EV) charging station without a line-frequency transformer at the medium-voltage grid side. It is mainly composed of the Neutral Point Clamped (NPC) converter based central ac-dc station and the parallel isolated three-level D ...