@inproceedings{SchmittAckva, author = {Schmitt, Maximilian and Ackva, Ansgar}, title = {A Novel Control Strategy for Reducing Common-Mode Currents in Bidirectional Drive Systems}, series = {20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe)}, booktitle = {20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe)}, publisher = {IEEE}, isbn = {9781538641453}, pages = {1 -- 9}, language = {en} } @article{ZieglerOeserHeinetal., author = {Ziegler, Andreas and Oeser, David and Hein, Thiemo and Montesinos Miracle, Daniel and Ackva, Ansgar}, title = {Reducing Cell to Cell Variation of Lithium-Ion Battery Packs During Operation}, volume = {9}, doi = {10.1109/ACCESS.2021.3057125}, pages = {24994 -- 25001}, language = {en} } @article{ZieglerOeserHeinetal., author = {Ziegler, Andreas and Oeser, David and Hein, Thiemo and Montesinos Miracle, Daniel and Ackva, Ansgar}, title = {Run to Failure: Aging of Commercial Battery Cells beyond Their End of Life}, series = {Energies}, volume = {13}, journal = {Energies}, number = {8}, doi = {10.3390/en13081858}, language = {en} } @inproceedings{RaabHofmannKastenetal., author = {Raab, Sebastian and Hofmann, Martin and Kasten, Henning and Ackva, Ansgar}, title = {High Bandwidth PWM-based Amplifier for Non-Linear Hybrid Filter in Electric Vehicle DC Grids}, series = {25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe)}, booktitle = {25th European Conference on Power Electronics and Applications (EPE'23 ECCE Europe)}, publisher = {IEEE}, isbn = {978-9-0758-1541-2}, doi = {10.23919/EPE23ECCEEurope58414.2023.10264683}, pages = {1 -- 9}, abstract = {The paper presents design and modulation strategy for a high bandwidth PWM-based amplifier. It consists of multiple H-bridges connected in parallel and switched sequentially. As the effective switching frequency is a multiple of the switching frequency of each single switch, the bandwidth is scaled by the number of H-bridges in parallel. The prototype presented supports a maximum number of eight H-bridges in parallel.}, language = {en} } @inproceedings{RaabAckva, author = {Raab, Sebastian and Ackva, Ansgar}, title = {Non-linear hybrid filter for the DC-side ripple current of voltage source converters}, series = {2022 International Symposium on Electromagnetic Compatibility - EMC Europe}, booktitle = {2022 International Symposium on Electromagnetic Compatibility - EMC Europe}, publisher = {IEEE}, isbn = {978-1-6654-0788-5}, issn = {2325-0364}, doi = {10.1109/emceurope51680.2022.9901278}, abstract = {The paper deals with the design of DC-side filters for three-phase voltage source converters of drives connected to an industrial or automotive DC-grid. It points out the problem of designing a filter if the DC-grid impedance and structure are unknown. Therefore, it presents a new non-linear hybrid filter whose filter effect is less dependent on the impedance of the downstream DC-grid and with better immunity against external interferences. The analytical and simulation based design process is explained with help of a concrete example. Results are validated by measurements on an experimental set-up.}, language = {en} } @incollection{KempkesWolzAckvaetal., author = {Kempkes, Joachim and Wolz, Christoph and Ackva, Ansgar and Sch{\"a}fer, Uwe}, title = {Nichtlineare Berechnung von permanentmagneterregten Gleichstrommotoren mit konzentrierten Wicklungen}, series = {Vortr{\"a}ge der 4. VDE/VDI-Tagung vom 17. bis 18. September 2013 in N{\"u}rtingen}, booktitle = {Vortr{\"a}ge der 4. VDE/VDI-Tagung vom 17. bis 18. September 2013 in N{\"u}rtingen}, publisher = {VDE}, address = {Berlin}, language = {de} } @article{OeserHeinZiegleretal., author = {Oeser, David and Hein, Thiemo and Ziegler, Andreas and Seefried, Michael and Gielinger, Sebastian and Montesinos-Miracle, Daniel and Bohn, Gunther and Ackva, Ansgar}, title = {Age-related development of cell-to-cell variation under various operating conditions in commercial NMC/graphite lithium-ion cells}, series = {Journal of Energy Storage}, volume = {101}, journal = {Journal of Energy Storage}, publisher = {Elsevier}, doi = {10.1016/j.est.2024.113787}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:863-opus-57585}, pages = {10}, abstract = {In real applications, lithium-ion cells are usually used in individual interconnections, with the worst cell determining capacity, performance and service life. Due to different ageing rates of the assembled cells, cell-to-cell variation changes over lifetime. In literature, cell-to-cell variation is usually investigated near room temperature under one operating condition. Data regarding cell-to-cell variation above and below room temperature under different operating conditions are hard to find. To fill the gap in literature, this study considers cell-to-cell variation as a function of different charge/discharge currents at ambient temperatures between 0 °C and 40 °C on commercial NMC/graphite cells (Samsung SDI ICR18650-26J). The results demonstrate that cell-to-cell variation strongly depends on the selected operating conditions. In particular, operating conditions near the lithium plating boundary at the beginning of the ageing process have a particularly high risk of developing a pronounced variation. Fast charging or charging at lower temperatures should therefore be avoided. Operation at moderate temperatures and currents, on the other hand, only leads to a slight increase in cell-to-cell variation in the tests carried out. A 24-month storage during the testing period at 30\% SOC and room temperature of the same cells shows even a slight reduction in cell-to-cell variation.}, language = {en} } @article{AckvaDresselEndres, author = {Ackva, Ansgar and Dreßel, Bernd and Endres, Julian}, title = {Umrichter in Hybridstruktur als Entwicklungswerkzeug und Pr{\"u}fsystem f{\"u}r elektrische Antriebe}, series = {FHWS Science Journal}, volume = {1}, journal = {FHWS Science Journal}, number = {2}, address = {W{\"u}rzburg}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:863-opus-484}, pages = {25 -- 36}, abstract = {Die Entwicklung, Applikation und der Test von Wechselrichtern, insbesondere f{\"u}r Traktionsantriebe, ist mit einem hohen Aufwand f{\"u}r die Bereitstellung einer passenden Testumgebung verbunden. F{\"u}r gew{\"o}hnlich werden diese Tests in der Entwicklung als auch in der Fertigung mit Hilfe von Motor-Generator Pr{\"u}fst{\"a}nden durchgef{\"u}hrt, die wiederum f{\"u}r unterschiedliche Leistungsklassen vorgehalten werden m{\"u}ssen. In diesem Beitrag wird eine neuartige hochdynamische Umrichtertopologie vorgestellt, die als universelles Entwicklungs-, Applikations- und Pr{\"u}fsystem f{\"u}r Umrichter eingesetzt werden kann. Derzeit wird dieser Umrichter in Hybridstruktur im Rahmen eines Forschungsprojektes an der FHWS realisiert.}, language = {de} } @article{HeinOeserZiegleretal., author = {Hein, Thiemo and Oeser, David and Ziegler, Andreas and Montesinos-Miracle, Daniel and Ackva, Ansgar}, title = {Aging Determination of Series-Connected Lithium-Ion Cells Independent of Module Design}, series = {Batteries}, volume = {9}, journal = {Batteries}, number = {3}, doi = {10.3390/batteries9030172}, abstract = {In this work, a battery consisting of eight commercial NMC/graphite cells connected in series was cycled to 60\% of its initial capacity. During the test, special care was taken to ensure that the results were not influenced by either the module assembly or the module design. For this purpose, the cells were virtually connected in a laboratory environment with the help of the test device as if they were operated together in a battery. Extrinsic influences that affect cell aging were thus reduced to a minimum. Differential Voltage Analysis (DVA), Electrochemical Impedance Spectrum (EIS), and relaxation measurements were performed to analyze the aging behavior of each cell. The results show that despite a theoretically perfect module design, Cell-to-Cell Variations (CtCV) occurred during aging. The shifting Depth of Discharge (DoD) values among the cells further amplify CtCV. Lithium plating was also observed in the faster aging cells after cyclic aging, suggesting that this aging effect contributes significantly to the development of CtCV. After the aging test, the battery was equipped with an active balancing system that maximizes capacity utilization. More important, the balancing charges which are calculated iteratively within the used balancing algorithm show a strong correlation to the pure capacity losses and thus provide a new way to determine the capacity values of each cell individually without disassembling the battery.}, language = {en} } @techreport{Ackva, author = {Ackva, Ansgar}, title = {Hochdynamischer Umrichter in Hybridstruktur : Schlussbericht im F{\"o}rderprogramm FHprofUnt : Laufzeit des Vorhabens: 01.10.2012 bis 30.09.3015}, publisher = {Hochschule f{\"u}r angewandte Wissenschaften W{\"u}rzburg-Schweinfurt}, address = {Schweinfurt}, doi = {10.2314/gbv:876282885}, pages = {21}, language = {de} } @techreport{AckvaKuechler, author = {Ackva, Ansgar and K{\"u}chler, Andreas}, title = {Konvergenz elektrischer Energietechnologien : Akronym: KEE-TECH : Schlussbericht zur Erstellung des Strategiekonzepts}, publisher = {Hochschule f{\"u}r angewandte Wissenschaften W{\"u}rzburg-Schweinfurt}, address = {W{\"u}rzburg}, doi = {10.2314/GBV:883086484}, pages = {7}, language = {de} }