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Karwatzki D.,Leibniz University of Hanover | Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Mertens A.,Leibniz University of Hanover
9th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2015-ECCE Asia | Year: 2015

The Hexverter modular multilevel converter topology has been recently proposed for three-phase to three-phase AC/AC conversion. This paper outlines the current state of the art of the Hexverter. The basic working principle is explained and the control concept is introduced. The differences to alternative topologies are discussed and possible applications are pointed out. © 2015 Korean Institute of Power Electronics.


Karwatzki D.,Leibniz University of Hanover | Von Hofen M.,Leibniz University of Hanover | Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Mertens A.,Leibniz University of Hanover
Proceedings, IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society | Year: 2014

Modular Multilevel Converters have a large number of advantages at high voltage and power levels. Due to their modular structure, they offer easy scalability, high quality output waveforms, and superior availability, to name a few. This paper aims at further increasing the availability of the Modular Multilevel Matrix Converter. A new method allows to operate the converter even in the case that a complete branch is lost. This is achieved by a new control method to operate six of the remaining branches as a reduced matrix converter. Smooth transition from full matrix to reduced matrix operation is achieved without shutdown of the system. © 2014 IEEE.


Kucka J.,Leibniz University of Hanover | Karwatzki D.,Leibniz University of Hanover | Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Mertens A.,Leibniz University of Hanover
2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015 | Year: 2015

The Modular Multilevel Converter (M2LC) is a well-known modular multilevel topology. This paper proposes a novel branch inductor coupling and compares it to the center-tapped inductor and the standard non-coupled inductor topology. The proposed coupling has a significant influence on the inductor and converter dimensioning. Its properties make it especially well-suited for use in M2LC single-to-three-phase AC/AC converter applications. © 2015 IEEE.


Karwatzki D.,Leibniz University of Hanover | Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Kucka J.,Leibniz University of Hanover | Mertens A.,Leibniz University of Hanover
2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015 | Year: 2015

This paper presents an alternative approach for analysing and controlling the Modular Multilevel Matrix Converter. After a system description, the proposed current control and branch energy balancing methods are introduced. As distinguished from previous approaches, the presented method is more general and easier applicable to other modular topologies. Its functionality is verified by simulation and an experimental test setup. © 2015 IEEE.


Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Mertens A.,Leibniz University of Hanover
IEEE Transactions on Industry Applications | Year: 2013

A new ac/ac modular multilevel topology for connecting two three-phase systems is introduced. The operating principle is explained, and characteristic waveforms are given. It is shown that the converter system offers superior performance for applications like low-frequency wind turbines. The analytic results are verified by a laboratory setup. © 1972-2012 IEEE.


Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Karwatzki D.,Leibniz University of Hanover | Von Hofen M.,Leibniz University of Hanover | Mertens A.,Leibniz University of Hanover
2014 16th European Conference on Power Electronics and Applications, EPE-ECCE Europe 2014 | Year: 2014

With the rising demand for energy harvesting from regenerative power sources, increasing power and voltage ratings are required of power electronic converter systems. For high-power conversion systems, modular multilevel converters proved to be superior to conventional topologies. This paper introduces a reduced variant of the well-known modular multilevel converter (M2LC) topology suitable for AC/DC conversion. It is compared to the original M2LC topology and examined for its usability in a DC/DC converter application. Results from a detailed simulation model prove the topology's expected functionality. © 2014 IEEE.


Karwatzki D.,Leibniz University of Hanover | Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Kucka J.,Leibniz University of Hanover | And 2 more authors.
2014 16th European Conference on Power Electronics and Applications, EPE-ECCE Europe 2014 | Year: 2014

The recently proposed modular multilevel converter 'Hexverter' offers many advantages in high-voltage and high-power applications. This paper presents an improved Hexverter topology by introducing magnetically coupled branch inductors. These lead to a simplified system behaviour and a reduced amount of material for the branch inductors. © 2014 IEEE.


Karwatzki D.,Leibniz University of Hanover | Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Von Hofen M.,Leibniz University of Hanover | Mertens A.,Leibniz University of Hanover
2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014 | Year: 2014

Modular multilevel converters offer many advantages for high-voltage and high-power applications. A recently proposed modular multilevel direct AC/AC converter is the so-called Hexverter. This paper presents a method to control the energy stored in the branches of the Hexverter topology. The control concept is described and possible degrees of freedom for the branch energy control are analysed analytically for different operating points. The findings are verified using a simulation and a laboratory test setup. © 2014 IEEE.


Baruschka L.,Leibniz University of Hanover | Baruschka L.,Protolar GmbH | Karwatzki D.,Leibniz University of Hanover | Von Hofen M.,Leibniz University of Hanover | Mertens A.,Leibniz University of Hanover
2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014 | Year: 2014

Modular multilevel converters (MMCs) have become an increasingly popular alternative to conventional frequency converters. However, operating at low speed is a challenging topic due to voltage deviations in the modules. This paper presents a way to allow low-speed operation for the recently introduced Hexverter topology. The findings are confirmed by simulation and experiment. © 2014 IEEE.


Kucka J.,PROTOLAR GMBH | Baruschka L.,PROTOLAR GMBH
2015 17th European Conference on Power Electronics and Applications, EPE-ECCE Europe 2015 | Year: 2015

This paper presents a hybrid modular multilevel topology for medium voltage drives requiring low frequencies and a high start-up torque. It operates from a DC supply which makes it easy to connect several drives to a single active front end converter, optionally also enabling galvanic isolation. The topology is compared to the modular multilevel matrix converter (MMMC) and to the modular multilevel converter (M2LC). © 2015 EPE Association and IEEE.

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