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A novel battery energy storage system (BESS) based on an enhanced modular multilevel converter (M2C) with the ability to switch its modules in parallel is being presented. Compared to a full-bridge M2C equipped with batteries as energy storage elements on its submodules, the losses are reduced by 20%. The raise in efficiency is thoroughly explained as well as its reliability. Its high efficiency,...
Multilevel converters (MCs) are utilized in medium voltage (MV) high power applications due to its higher efficiency than two level converters. On the other hand, modular multilevel converters (MMCs) provide several advantages with regard to other MCs, such as higher scalability, reliability and no requirement of a common DC capacitor. Particularly, low switching frequency modulations, such as (2N+1)...
The use of a model predictive control algorithm to reduce the losses in a 3L-NPC inverter with SiC neutral point diodes was investigated. It considers the reduced switching losses associated with the commutations that involve a SiC diode. A loss reduction of 5% is achieved compared to a standard sine-triangle modulation.
Efficient HV DC-DC converters are one key component of a future HVDC backbone grid. In this paper three promising MMC based HV DC-DC converter topologies, namely the front-to-front converter, the HVDC auto transformer and the modular multilevel DC converter are compared in terms of functionality, conversion efficiency and topology effort.
Recent studies show that Silicon Carbide and Gallium Nitride based power semiconductors promise better performance over conventional Silicon based devices. In this study, the performance analysis of a three level inverter based on SiC and GaN is discussed for photovoltaic applications. The converter can achieve 99.2% efficiency at 16kHz switching frequency and 1.4kW output power, and operate with...
In this work different three-level topologies suitable for PV systems are analyzed. First the basic operation principles of the Neutral Point Clamped (NPC), Active Neutral Point Clamped (ANPC) and Mixed Voltage Neutral Point Clamped (MNPC) topologies are explained and the used PWM strategies are presented. All three topologies are realized in hardware on a modular test setup, so that it is possible...
For the upcoming need to transfer bulk power over long onshore distances, HVDC power transmission is the preferred choice. However, components like HVDC-DC converters and a protection concept for DC line faults present challenges, that still have to be solved. As up today, the sections of a segmented DC transmission corridor would still be linked via an AC connection, leading to high transformation...
Presented here is a three level voltage source inverter for electric drives, uninterruptable power supplies and for mains feeds. Unlike the usual hard switching topologies, it is implemented as completely soft switching. A novel patented snubber circuit is added, which is structured very simply and consists of only a few passive components. This snubber circuit works in principle without any losses;...
In this paper an efficiency optimized variable speed drive is presented. It consists of the alternative 3-level T-type converter topology which is very efficient for low switching frequencies and a standard induction machine. The total system efficiency is optimized concerning the converter losses as well as fundamental and harmonic induction machine losses.
The paper presents a new modulation strategy for cascaded H-bridge inverters which allows easy integration of device specific safety features like IGCT burst capability monitoring. It is compared to PWM using a simulation model of an unusual configuration for a 10 kV medium voltage inverter using just three cascaded cells per phase. The general structure of the cascaded H-bridge inverter and key data...
The grid-connected photovoltaic (PV) systems are an important part of renewable energy sources and their integration is getting more and more widespread. In order to improve the efficiency, practicality and reliability of the PV systems, many kinds of new inverter topologies have been proposed to avoid using a grid isolation transformer. The NPC topology and two other derived topologies are presented...
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