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Dr. Gunnar Rohde
Danish Center for Energy Storage

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Research Keywords & Expertise

0 Thermodynamics
0 Energy efficiency and energy savings
0 Electrochemistry (for energy storage application)
0 Energy storage and energy conversion systems
0 Electrochemical Energy Storage and Conversion Devices/Technologies

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Short Biography

Gunnar Rohde is Chief Technical Consultant at the Danish Center for Energy Storage (DaCES) under the national Academy of Technical Sciences (ATV). He holds M.Sc. degrees in both physics (2007) and mathematics (2013) as well as a Ph.D. in mathematical physics (2014) from the Technical University of Braunschweig and Hamburg University, respectively. Previously, Gunnar held positions in academic and industry of energy conversion and storage technologies, in particular fuel cell and battery systems research for aerospace and marine applications at the German Aerospace Center (DLR) and as Lead Scientist at Nerve Smart Systems (NSS) for the development of variable topology batteries. His research interests include first-principle analyses of energy conversion and storage technologies as cyber-physical systems for optimal system architectures and control strategies. Gunnar is a member of DPG and DMV in Germany, DEF and IDA in Denmark, and a member of the board of the Danish Battery Society (DBS).

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Journal article
Published: 23 April 2021 in Energies
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This paper introduces a novel design of an electric vehicle (EV) fast charging station, consisting of a battery energy storage system (BESS) with reconfigurable cell topology. The BESS comprises two battery strings that decouple the power flow between EV and grid, to enable charging powers above the grid capacity. The reconfigurable design is achieved by equipping the battery cells with semiconductor switches and serves two main purposes. First, it aims at solving cell unbalance issues to increase safety, reliability, and lifetime of the battery. Second, it enables the BESS to actively control the EV charging process by changing its cell configuration in a real-time fashion, making a DC-DC converter redundant. The paper presents a modelling approach that captures the reconfigurable design including the controlling algorithm used for cell engagement. The simulation results show that the BESS is able to fulfil the EV request with sufficient accuracy for most of the fast charging process. However, the switching of cells leads to variations in the charging current that can potentially exceed the tolerance band defined in IEC61851-23. Therefore, complementary measures are suggested to achieve a suitable current control during all phases of the charging process. The estimated BESS efficiency during the EV fast charging process is 93.3%. The losses caused by the reconfigurable design amount to 1.2% of the provided energy. It is demonstrated that the proposed design has a competitive efficiency compared to a battery buffered fast charging station with DC-DC converter.

ACS Style

Jan Engelhardt; Jan Zepter; Tatiana Gabderakhmanova; Gunnar Rohde; Mattia Marinelli. Double-String Battery System with Reconfigurable Cell Topology Operated as a Fast Charging Station for Electric Vehicles. Energies 2021, 14, 2414 .

AMA Style

Jan Engelhardt, Jan Zepter, Tatiana Gabderakhmanova, Gunnar Rohde, Mattia Marinelli. Double-String Battery System with Reconfigurable Cell Topology Operated as a Fast Charging Station for Electric Vehicles. Energies. 2021; 14 (9):2414.

Chicago/Turabian Style

Jan Engelhardt; Jan Zepter; Tatiana Gabderakhmanova; Gunnar Rohde; Mattia Marinelli. 2021. "Double-String Battery System with Reconfigurable Cell Topology Operated as a Fast Charging Station for Electric Vehicles." Energies 14, no. 9: 2414.