Comparison of 2-, 3-, and 5-Level Topologies for Medium-Voltage Grid-Tied Converters: Trade-offs in Efficiency, Cost, and Power Density

Magno O. Schneider; Gustavo V. Barbosa; Gabriel A. Fogli; Thiago R. de Oliveira; Lenin M. F. Morais

doi:10.18618/REP.e202633

Authors

Magno O. Schneider Universidade Federal de Minas Gerais https://orcid.org/0000-0002-4442-4265
Gustavo V. Barbosa Universidade Federal de Minas Gerais https://orcid.org/0009-0001-9152-1391
Gabriel A. Fogli Universidade Federal de Minas Gerais https://orcid.org/0000-0003-1940-4630
Thiago R. de Oliveira Universidade Federal de Minas Gerais https://orcid.org/0000-0003-1027-418X
Lenin M. F. Morais Universidade Federal de Minas Gerais https://orcid.org/0000-0003-1680-0400

DOI:

https://doi.org/10.18618/REP.e202633

Keywords:

Multiobjective Converter Design, Bidirectional Interlinking Converter, DC-Link Voltage

Abstract

The increasing integration of distributed energy resources, renewable generation, and electric vehicles is reshaping modern distribution networks, introducing challenges such as voltage regulation issues, bidirectional power flows, and reduced system inertia. In this context, microgrids and clustered microgrids rely on bidirectional interlinking converters (BICs) to enable controlled power exchange, provide ancillary services, and improve system flexibility. This paper presents a multiobjective design methodology for BICs based on transformer-coupled back-to-back converter architectures. The proposed framework evaluates two-, three-, and five-level topologies under low- and medium-voltage DC-link configurations using SiC and IGBT semiconductor technologies. The solution space is analyzed in terms of efficiency, power density, and cost, enabling a comparison of competing solutions. The results demonstrate that the optimal design is strongly dependent on voltage level and semiconductor selection. For low-voltage DC-link, two-level converter topologies using SiC devices at 10 kHz switching frequency provide the best trade-off among the considered figures of merit. For medium-voltage systems, three-level NPC topologies with hybrid SiC/IGBT implementations achieve higher efficiency and power density while maintaining low cost levels.

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Author Biographies

Magno O. Schneider, Universidade Federal de Minas Gerais

received the B.Sc. degree in electrical engineering from the Federal University of São João del-Rei (UFSJ) in 2021 and the M.Sc. degree in electrical engineering from the Federal University of Minas Gerais (UFMG) in 2023, where he is currently pursuing the Ph.D. degree. He is also a member of the Power Electronics Research Group (GEP/UFMG). His research interests include multi-objective design of power converters and active power decoupling techniques.

Gustavo V. Barbosa, Universidade Federal de Minas Gerais

received the B.Sc. degree in Control and Automation Engineering from the Federal University of Minas Gerais (UFMG) in 2025, graduating with the gold medal of his class. He is currently pursuing the M.Sc. degree in electrical engineering at UFMG and is a member of the Power Electronics Research Group (GEP/UFMG). His research interests include microgrids, with emphasis on control structures, state observers applied to microgrid systems, and communication architectures for microgrids.

Gabriel A. Fogli, Universidade Federal de Minas Gerais

received the B.S. degree in electronics and telecommunication engineering from Pontifícia Universidade Católica of Minas Gerais, Brazil, in 2011, and the M.Sc. and Ph.D. degrees in electrical engineering from the Universidade Federal de Juiz de Fora, Brazil, in 2014 and 2018, respectively. Since 2019, he has been a Professor with the Universidade Federal de Minas Gerais, Brazil. His research interests include modeling and control of power electronic converters and distributed generation applications.

Thiago R. de Oliveira, Universidade Federal de Minas Gerais

received the Ph.D. degree in electrical engineering from the Federal University of Minas Gerais (UFMG) in 2016. He is currently an Assistant Professor with the Electronic Engineering Department, UFMG, and a member of the Power Electronics Research Group (GEP/UFMG). His research interests include power electronics application in hybrid AC/DC microgrids, distributed energy storage, uninterruptible power supply (UPS), and optimized design of power converters.

Lenin M. F. Morais, Universidade Federal de Minas Gerais

received the bachelor’s degree, the master’s degree, and the doctor’s degree, all in electrical engineering from the Federal University of Minas Gerais, Belo Horizonte, Brazil, in 2000, 2002, and 2007, respectively. He is currently a Full Professor with the Electronics Engineering Department, Federal University of Minas Gerais. He was a Postdoctoral Intern with the Laboratoire Plasma et Conversion d’Energie - LAPLACE, Université Toulouse III Paul Sabatier, Toulouse, France, and with the Institut de Recherche Technologique - IRT Saint Exupéry, Toulouse, France. He has experience in the field of electrical engineering, with emphasis on power electronics, industrial electronics, and electronic systems and controls. His research interests mainly include the following: projects of converters with high density of power/high performance, electronic reactors for high intensity discharge lamps, power LEDs, circuits for power factor correction, repetitive control, control based on passivity, PWM methods. IEEE Senior Member and member of the IEEE Power Electronics Society, and Member of SOBRAEP (Brazilian Power Electronics Society) since 2005.

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