Step-up Transformerless Seven-level DC-AC Hybrid Topology for Interconnection of Renewable-based DC Sources to Microgrids

Abstract

This article introduces a new step-up transformerless multi-level DC-AC hybrid topology for interconnecting renewable DC sources to loads or microgrids. This enabling technology incorporates the best characteristics of three modified basic topologies—a DC-DC multi-level boost converter, a DC-DC multi-level buck converter, and an H-bridge—to obtain a seven-level step-up DC-AC hybrid structure using only one DC input and nine power switches for a single-phase output with field-programmable gate array based control. The advantages of the step-up seven-level structure compared to other proposals are higher efficiency, a reduced number of power switches, and high power density associated with transformerless characteristic. Furthermore, in contrast to conventional topologies, the proposed design does not require voltage/current monitoring of the capacitors or a capacitor-balancing control scheme, and only one DC source input is used. Consequently, a high-performance configuration is obtained. The laboratory results demonstrate the validity of the design and the performance of the prototype.

Keywords:

• DC-DC converter
• DC-AC converter
• multi-level boost converter
• multi-level buck converter
• transformerless
• microgrids
• field-programmable gate array

Additional information

Notes on contributors

Juan Ramón Rodríguez

Juan Ramón Rodríguez received his B.Eng. in electronics engineering from the Instituto Tecnológico de Morelia, Michoacán, México, in 2010. He specialized in digital design in the PADTS at the CINVESTAV-IPN. He is currently working toward his Ph.D. in electrical power systems at the Instituto Tecnológico de Morelia. His areas of interest are power electronics converters, power quality, and FPGA programming.

Edgar Lenimirko Moreno-Goytia

Edgar Lenimirko Moreno received his Ph.D. from the University of Glasgow, Glasgow, Scotland, UK, in 2003. He joined the Department of Electric and Electronics Engineering at the Instituto Tecnológico de Morelia, Morelia, Michoacán, México, in 1993 where he is now a reader. His fields of interest are VSC-based DC links, power electronics transformers for medium and high voltages, and multi-terminal HVDC systems.

Vicente Venegas Rebollar

Vicente Venegas Rebollar obtained his B.Eng. and M.Sc. in electrical engineering from the Instituto Tecnológico de Morelia in 1992 and 1996, respectively. He received his Ph.D. in electrical engineering from the ESIME-Zacatenco, IPN, México, in 2004. He joined the Postgraduate Studies Program in Electrical Engineering at the Instituto Tecnológico de Morelia, Morelia, Michoacán, México, in 1995. His areas of interest are electromagnetic transients and fields and power electronics.

Luis Eduardo Ugalde

Luis Eduardo Ugalde received his B.Eng. and M.Sc. from the Instituto Tecnológico de Morelia (ITM) and his Ph.D. from Universidad Michoacana de San Nicolás de Hidalgo in México (UMSNH). In 2003, he joined the Postgraduate Studies Program in Electrical Engineering at the ITM. His current research interests include control systems, power electronics, renewable energy sources, and HVDC systems.

Nadia María Salgado-Herrera

Nadia María Salgado-Herrera received her B.Eng. and M.Sc. in electronics engineering and electrical engineering, respectively, from Instituto Tecnológico de Morelia, Michoacán, México, in 2009 and 2011. She is currently pursuing her Ph.D. in electrical engineering at the Universidad Michoacana de San Nicolás de Hidalgo. Her research interests include power electronics and power quality.