EPE Association: EPE 2018 - LS1b: Multi-Level Converters

EPE 2018 - LS1b: Multi-Level Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 02: Power Converter Topologies and Design > EPE 2018 - LS1b: Multi-Level Converters

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   Back-to-Back Modular Multilevel Converter for drive applications under unbalanced grid conditions
By Felipe DONOSO [View]
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Abstract: In this paper, a control system for a Back-to-Back Modular Multilevel Converter based drive is proposed.The control system is able to operate either in balanced and unbalanced grid-conditions by regulating thepower oscillations choosing an appropriate circulating current reference. Unity power factor operation(for balanced grid), reduced harmonic distortion, capacitor voltage balance and bidirectional power floware feasible with the proposed methodology. Simulations and experimental results obtained with a 7.5-kW 30 power cells prototype are presented to validate the effectiveness of the proposed control system.

   Control Strategy for an AC/DC Asymmetric Alternate Arm Converter
By Diego SOTO [View]
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Abstract: The Modular Multilevel Converter (MMC) is nowadays an attractive technology. However, due to the power pulsation in each MMC single phase unit it requires big DC capacitors. This work presents a control strategy for a 3-phase AC/DC Asymmetric Alternate Arm Converter with MMC arms in the lower side and only standard ON-OFF valves in the upper side. The topology operation principle is explained, a control strategy to demonstrate its operation is developed and a preliminary evaluation of the topology losses is carried out. Results confirm good operation of the suggested topology. Moreover, a sort of interleaved operation is proposed in order to reduce the DC link ripple current resulting from the converter control strategy.

   Hex-Y - A New Modular Multilevel Converter Topology for a Direct AC-AC Power Conversion
By Pawel BLASZCZYK [View]
[Download]

Abstract: For Modular Multilevel Converter (MMC) systems, following 3 phase to 3 phase topologies are identified:indirect MMC, direct matrix converter (M3C) and a Hexverter. Following paper presents a newtopology in the ac-ac family called Hex-Y.This paper presents a topology overview and required feed-forward control references for a given operationpoint. Degrees of freedom are identified and used for steady-state balancing. Proposed topologyis compared with existing ac-ac systems to show its advantages and disadvantages for given workingconditions as output frequency or reactive power compensation ability.

   Reduction of Switching Frequency for the Semi-Full-Bridge Submodule Using Alternative Bypass States
By Stefanie HEINIG [View]
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Abstract: As regards modular multilevel converter submodules, a different number of switches may be involved in the transitions between voltage levels depending on the submodule type and choice of switching states. In this paper, an investigation of the average switching frequency associated with different choices of bypass states is performed for the semi-full-bridge submodule. Theoretical considerations and simulation results show that the average switching frequency per device can be halved by using the proposed alternative bypass state. Moreover, the switching losses can be reduced by up to 60\%. Finally, a comparative study with the full-bridge submodule has been conducted.

EPE 2018 - LS1b: Multi-Level Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 02: Power Converter Topologies and Design > EPE 2018 - LS1b: Multi-Level Converters
	[return to parent folder]

	Back-to-Back Modular Multilevel Converter for drive applications under unbalanced grid conditions By Felipe DONOSO	[View] [Download]
Abstract: In this paper, a control system for a Back-to-Back Modular Multilevel Converter based drive is proposed.The control system is able to operate either in balanced and unbalanced grid-conditions by regulating thepower oscillations choosing an appropriate circulating current reference. Unity power factor operation(for balanced grid), reduced harmonic distortion, capacitor voltage balance and bidirectional power floware feasible with the proposed methodology. Simulations and experimental results obtained with a 7.5-kW 30 power cells prototype are presented to validate the effectiveness of the proposed control system.

	Control Strategy for an AC/DC Asymmetric Alternate Arm Converter By Diego SOTO	[View] [Download]
Abstract: The Modular Multilevel Converter (MMC) is nowadays an attractive technology. However, due to the power pulsation in each MMC single phase unit it requires big DC capacitors. This work presents a control strategy for a 3-phase AC/DC Asymmetric Alternate Arm Converter with MMC arms in the lower side and only standard ON-OFF valves in the upper side. The topology operation principle is explained, a control strategy to demonstrate its operation is developed and a preliminary evaluation of the topology losses is carried out. Results confirm good operation of the suggested topology. Moreover, a sort of interleaved operation is proposed in order to reduce the DC link ripple current resulting from the converter control strategy.

	Hex-Y - A New Modular Multilevel Converter Topology for a Direct AC-AC Power Conversion By Pawel BLASZCZYK	[View] [Download]
Abstract: For Modular Multilevel Converter (MMC) systems, following 3 phase to 3 phase topologies are identified:indirect MMC, direct matrix converter (M3C) and a Hexverter. Following paper presents a newtopology in the ac-ac family called Hex-Y.This paper presents a topology overview and required feed-forward control references for a given operationpoint. Degrees of freedom are identified and used for steady-state balancing. Proposed topologyis compared with existing ac-ac systems to show its advantages and disadvantages for given workingconditions as output frequency or reactive power compensation ability.

	Reduction of Switching Frequency for the Semi-Full-Bridge Submodule Using Alternative Bypass States By Stefanie HEINIG	[View] [Download]
Abstract: As regards modular multilevel converter submodules, a different number of switches may be involved in the transitions between voltage levels depending on the submodule type and choice of switching states. In this paper, an investigation of the average switching frequency associated with different choices of bypass states is performed for the semi-full-bridge submodule. Theoretical considerations and simulation results show that the average switching frequency per device can be halved by using the proposed alternative bypass state. Moreover, the switching losses can be reduced by up to 60\%. Finally, a comparative study with the full-bridge submodule has been conducted.