Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion

The modular multilevel ac/ac converter (M2AC) is a recently proposed partial power processing topology for direct ac/ac conversion that can adjust voltage magnitudes and phase angles in single-frequency ac power systems, analogous to a power electronic autotransformer. However, prior studies have be...

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Main Authors: Anjana Wijesekera, Gregory J. Kish
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Open Journal of Power Electronics
Subjects:
Online Access:https://ieeexplore.ieee.org/document/11078915/
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author Anjana Wijesekera
Gregory J. Kish
author_facet Anjana Wijesekera
Gregory J. Kish
author_sort Anjana Wijesekera
collection DOAJ
description The modular multilevel ac/ac converter (M2AC) is a recently proposed partial power processing topology for direct ac/ac conversion that can adjust voltage magnitudes and phase angles in single-frequency ac power systems, analogous to a power electronic autotransformer. However, prior studies have been limited to investigating only active power transfers and basic operating features. This article addresses this gap by proposing three operating flexibility enhancements for the M2AC: 1) accommodating practical power flow scenarios where independent control of active and reactive powers is needed, 2) eliminating large dc-link capacitors to realize a fully modular and scalable architecture, and 3) incorporating full fault blocking akin to ac circuit breaker functionality. The fundamental operating principles and fault-blocking characteristics are thoroughly studied for different M2AC design variants, and a comparative analysis is conducted to quantify potential semiconductor savings in comparison to the back-to-back modular multilevel converter as a benchmark. Converter controls incorporating active and reactive power flow management and internal capacitor voltage cell balancing are developed. The M2AC&#x2019;s steady-state and transient operation and fault-blocking capabilities are validated through simulation studies and further confirmed by experimental tests using a laboratory-scale 250 V<sub>pk</sub>, 1 kVA prototype.
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spelling doaj-art-bfb276bd5c6a402b9d898b76a60a82ce2025-08-20T03:13:38ZengIEEEIEEE Open Journal of Power Electronics2644-13142025-01-0161269128110.1109/OJPEL.2025.358878511078915Improved Operational Flexibility of the M2AC for Direct AC/AC ConversionAnjana Wijesekera0https://orcid.org/0000-0003-0447-8776Gregory J. Kish1https://orcid.org/0000-0002-3186-9812Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, CanadaDepartment of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, CanadaThe modular multilevel ac/ac converter (M2AC) is a recently proposed partial power processing topology for direct ac/ac conversion that can adjust voltage magnitudes and phase angles in single-frequency ac power systems, analogous to a power electronic autotransformer. However, prior studies have been limited to investigating only active power transfers and basic operating features. This article addresses this gap by proposing three operating flexibility enhancements for the M2AC: 1) accommodating practical power flow scenarios where independent control of active and reactive powers is needed, 2) eliminating large dc-link capacitors to realize a fully modular and scalable architecture, and 3) incorporating full fault blocking akin to ac circuit breaker functionality. The fundamental operating principles and fault-blocking characteristics are thoroughly studied for different M2AC design variants, and a comparative analysis is conducted to quantify potential semiconductor savings in comparison to the back-to-back modular multilevel converter as a benchmark. Converter controls incorporating active and reactive power flow management and internal capacitor voltage cell balancing are developed. The M2AC&#x2019;s steady-state and transient operation and fault-blocking capabilities are validated through simulation studies and further confirmed by experimental tests using a laboratory-scale 250 V<sub>pk</sub>, 1 kVA prototype.https://ieeexplore.ieee.org/document/11078915/Modular-multilevelac/ac conversionactive and reactive power controlfault blocking
spellingShingle Anjana Wijesekera
Gregory J. Kish
Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion
IEEE Open Journal of Power Electronics
Modular-multilevel
ac/ac conversion
active and reactive power control
fault blocking
title Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion
title_full Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion
title_fullStr Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion
title_full_unstemmed Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion
title_short Improved Operational Flexibility of the M2AC for Direct AC/AC Conversion
title_sort improved operational flexibility of the m2ac for direct ac ac conversion
topic Modular-multilevel
ac/ac conversion
active and reactive power control
fault blocking
url https://ieeexplore.ieee.org/document/11078915/
work_keys_str_mv AT anjanawijesekera improvedoperationalflexibilityofthem2acfordirectacacconversion
AT gregoryjkish improvedoperationalflexibilityofthem2acfordirectacacconversion