@phdthesis{Ziegler, author = {Ziegler, Andreas Rainer}, title = {Possibilities and limitations of active battery management systems for lithium-ion batteries}, editor = {Montesinos Miracle, Daniel and Ackva, Ansgar}, publisher = {Universitat Polit{\`e}cnica de Catalunya}, doi = {10.5821/dissertation-2117-380367}, abstract = {(English) Lithium-Ion Batteries (LIBs) are being used in more and more areas of application. At the same time, their chemical composition and their designs are constantly evolving. Major developments are also taking place in the field of Battery Management Systems (BMSs), which are essential for the safe operation of LIBs. The focus is on intelligent charge redistribution between individual cells, called Active Balancing (AB). This thesis deals with the possibilities and limitations of AB. An empirical long-term experiment provides new insights into the ageing behaviour of batteries that are actively balanced during their entire service life. The main objective of this work is to to demonstrate influences on the ageing behaviour of batteries that are still unknown at present. A literature study shows that previous work in this area is often based on theoretical approaches and rarely has a functional proof through measurement results. Most significant statements from literature are examined. These include the increase in discharge capacity, energy efficiency and service life associated with AB, as well as lower parameter variation of the individual cells installed in the battery. Before starting the empirical experiment, the current state of the art is captured and a universal AB topology is selected from a large number of known systems. The operating behaviour as well as the balancing algorithms are explained in detail in order to be able to understand the influences occurring during the ageing of the batteries. The ageing experiment itself is a comparison test between commercial Passive Balancing (PB) and the novel AB. Two identical battery packs are aged under uniform conditions, but with the two different BMSs mentioned above. At the end of the ageing process, the battery packs are disassembled and the parameters of all individual cells are determined for further investigation. The main contribution of this work is the proof of effects through AB, especially with large battery loads. Both the increase in discharge capacity and the service life are demonstrated. The work shows how parameter variation of individual cells can be made visible during operation. It also presents diagnosis and calculation methods. The energetic efficiency of the batteries cannot be increased, since the self-consumption of the power electronics of the AB system is always higher than with PB. However, the overall efficiency of the battery increases due to an increase in capacity and an extension of the service life. The thesis also shows that with lower battery loads, the use of AB is not beneficial any more or may lead to negative effects. In such applications conventional PB is sufficient. The results obtained during pack ageing are additionally substantiated and extended by the measurement results of the individual cells. At the end of the thesis, all results and contributions are summarised. Suggestions for optimisation as well as further research ideas are presented as a possible starting point for further scientific studies. (Catal{\`a}) Les bateries d'ions de liti (Lithium Ion Batteries, en angl{\`e}s) s'usen en m{\´e}s aplicacions. Al mateix temps, la seva composici{\´o} qu{\´i}mica i dissenys estan en evoluci{\´o} constant. Els sistemes de gesti{\´o} del bateries (Battery Management Systems, en angl{\`e}s), que s{\´o}n essencials per l'operaci{\´o} de les LIB, tamb{\´e} estan en constant evoluci{\´o}. El focus principal est{\`a} en la distribuci{\´o} intel·ligent de c{\`a}rrega el{\`e}ctrica entre cel·les individuals, l'anomenat balanceig actiu (Active Balancing, en angl{\`e}s). Un assaig emp{\´i}ric, de llarga durada, com el dut a terme en aquest treball, dona molt informaci{\´o} en el proc{\´e}s d'envelliment de les cel·les durant tota la seva vida. El principal objectiu d'aquest treball {\´e}s demostrar les influ{\`e}ncies encara desconegudes en el proc{\´e}s d'envelliment de les cel·les. L'estudi de la literatura mostra que el treball previ en aquesta {\`a}rea est{\`a} sovint basat en aproximacions te{\`o}riques i estranyament ensenya resultats emp{\´i}rics que ho corroborin. En aquest treball s'examinen la majoria de presumpcions que es poden trobar a la literatura. Aquestes inclouen l'increment en la capacitat, l'efici{\`e}ncia energ{\`e}tica i la vida {\´u}til associada a un balanceig actiu de les cel·les, aix{\´i} com la reducci{\´o} de la variaci{\´o} dels par{\`a}metres de cada cel·la en una bateria. Abans de procedir amb l'experiment emp{\´i}ric, es revisa l'estat de l'art en els aspectes fonamentals per aquest estudi. Tamb{\´e} se selecciona una tipologia de sistema de balanceig actiu per tal de realitzar l'experiment. El treball detalla el procediment d'operaci{\´o} aix{\´i} com l'algoritme de balanceig actiu implementat per tal d'entendre els fen{\`o}mens que influencien la degradaci{\´o} de les cel·les durant la seva vida. L'experiment d'envelliment {\´e}s una comparaci{\´o} entre un sistema de balanceig passiu (Passive Balancing, en angl{\`e}s) i un de balanceig actiu. Per aix{\`o} s'escullen dues bateries id{\`e}ntiques, per{\`o} gestionades diferentment per dos sistemes de gesti{\´o} diferents. Al final de l'assaig, les bateries es desmunten i s'analitza cada cel·la de forma individual per tal de determinar-ne els seus par{\`a}metres i el seu envelliment. La principal contribuci{\´o} d'aquest treball es el demostrar els efectes del balanceig actiu , sobretot en bateries amb una c{\`a}rrega elevada. El treball demostra que el balanceig actiu millor gla capacitat de la bateria i la vida {\´u}til. El treball tamb{\´e} mostra com la variaci{\´o} dels par{\`a}metres de les cel·les es pot fer visible durant la seva operaci{\´o}. Tamb{\´e} presenta nous m{\`e}todes de diagnosi i c{\`a}lcul d'aquests par{\`a}metres. L'efici{\`e}ncia energ{\`e}tica de les bateries no es pot augmentar degut al consum propi i les p{\`e}rdues del sistema de balanceig actiu basat en electr{\`o}nica de potencia. Si que augmenta l'efici{\`e}ncia global de la bateria, ja que augmenta la seva capacitat i la vida {\´u}til. El treball tamb{\´e} mostra que en bateries sotmeses a baixa c{\`a}rrega, el balanceig actiu no aporta cap avantatge respecte el balanceig passiu. Fins i tot en algunes situacions, els efectes del balanceig actiu s{\´o}n negatius. En aquestes aplicacions, es recomana l'{\´u}s d'un sistema de balanceig passiu. Els resultats obtinguts durant l'assaig de la bateria queden refor{\c{c}}ats quan es fa l'an{\`a}lisi de cada cel·la de forma individual. Al final del treball, es resumeixen tots els resultats a m{\´e}s de proporcionar suggereixes per la optimitzaci{\´o} aix{\´i} com possibles l{\´i}nies de futures investigacions}, language = {en} } @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} } @phdthesis{Ziegler, author = {Ziegler, Andreas}, title = {Possibilities and limitations of active battery management systems for lithium-ion batteries}, editor = {Montesinos-Miracle, Daniel and Ackva, Ansgar}, pages = {213}, abstract = {Lithium-Ion Batteries (LIBs) are being used in more and more areas of application. At the same time, their chemical composition and their designs are constantly evolving. Major developments are also taking place in the field of Battery Management Systems (BMSs), which are essential for the safe operation of LIBs. The focus is on intelligent charge redistribution between individual cells, called Active Balancing (AB). This thesis deals with the possibilities and limitations of AB. An empirical long-term experiment provides new insights into the ageing behaviour of batteries that are actively balanced during their entire service life. The main objective of this work is to to demonstrate influences on the ageing behaviour of batteries that are still unknown at present. A literature study shows that previous work in this area is often based on theoretical approaches and rarely has a functional proof through measurement results. Most significant statements from literature are examined. These include the increase in discharge capacity, energy efficiency and service life associated with AB, as well as lower parameter variation of the individual cells installed in the battery. Before starting the empirical experiment, the current state of the art is captured and a universal AB topology is selected from a large number of known systems. The operating behaviour as well as the balancing algorithms are explained in detail in order to be able to understand the influences occurring during the ageing of the batteries. The ageing experiment itself is a comparison test between commercial Passive Balancing (PB) and the novel AB. Two identical battery packs are aged under uniform conditions, but with the two different BMSs mentioned above. At the end of the ageing process, the battery packs are disassembled and the parameters of all individual cells are determined for further investigation. The main contribution of this work is the proof of effects through AB, especially with large battery loads. Both the increase in discharge capacity and the service life are demonstrated. The work shows how parameter variation of individual cells can be made visible during operation. It also presents diagnosis and calculation methods. The energetic efficiency of the batteries cannot be increased, since the self-consumption of the power electronics of the AB system is always higher than with PB. However, the overall efficiency of the battery increases due to an increase in capacity and an extension of the service life. The thesis also shows that with lower battery loads, the use of AB is not beneficial any more or may lead to negative effects. In such applications conventional PB is sufficient. The results obtained during pack ageing are additionally substantiated and extended by the measurement results of the individual cells. At the end of the thesis, all results and contributions are summarised. Suggestions for optimisation as well as further research ideas are presented as a possible starting point for further scientific studies.}, language = {en} } @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} } @article{GielingerHeinZiegleretal., author = {Gielinger, Sebastian and Hein, Thiemo and Ziegler, Andreas and Oeser, David and Breitfelder, Sebastian and Bohn, Gunther}, title = {A Short Time Expansion Measurement Method for the Detection of Aging Effect of Lithium Ion Cells Using a High Resolution Laser Interfometric Setup}, series = {IEEE Access}, volume = {11}, journal = {IEEE Access}, publisher = {IEEE}, doi = {10.1109/ACCESS.2023.3341505}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:863-opus-53654}, pages = {11}, abstract = {In this work a new expansion measurement methodology for the detection of ageing mechanisms in lithium ion cells is described and evaluated. For this purpose, a polarization-optical homodyne Michelson interferometer with a resolution of approx. 10 nm was set up to allow measurements of different cell types, cell sizes, and cell chemistry within a Memmert IP55 climate chamber. The used interferometric measurement setup is ten times more accurate than measurement systems commonly used for battery measurements in the literature. The better spatial resolution of an interferometer setup enables the recording of the expansion response to short current pulses with low transferred charge. This offers the possibility to detect ageing mechanisms such as lithium plating within short measuring times. With this measurement setup, a lithium iron phosphate pouch cell from the company A123, with the model identification AMP20M1HD-A, is measured. First, an expansion measurement over a full charge and discharge cycle with a constant load of ± C 20 (b=1 A) is performed. Here, the cell undergoes an expansion of about 42 μm. Subsequently, the in this work proposed measurement methodology is presented to show the influence of effects such as the formation of overshooting graphite stages or lithium plating on cell expansion. For this purpose, at a residual capacitance of 50\%, the cell is pulsed with current of different intensity I ∈ {±20A,±80A} for t = {240 s, 60 s}, at T = {10 ◦C, 20 ◦C, 30 ◦C}, respectively, and the mechanical response is recorded using the high accuracy interferometer setup. A mechanical relaxation of the cell after the pulses with a time constant in the range between 10 s and 20 s can be observed. It is shown that this relaxation behavior can be associated with effects of the anode known from the literature, such as the formation of overshooting graphite stages or lithium plating. These effects can be recorded by the very high-resolution measurement already with little transferred charge and within a short measurement time.}, language = {en} } @article{HeinZieglerOeseretal., author = {Hein, Thiemo and Ziegler, Andreas and Oeser, David and Ackva, Ansgar}, title = {A capacity-based equalization method for aged lithium-ion batteries in electric vehicles}, series = {Electric power systems research}, volume = {191}, journal = {Electric power systems research}, issn = {0378-7796}, doi = {10.1016/j.epsr.2020.106898}, language = {en} } @inproceedings{ZieglerOeserHeinetal., author = {Ziegler, Andreas and Oeser, David and Hein, Thiemo and Ackva, Ansgar}, title = {Development and Application of an Active Balancing System for Lithium-Ion Cells}, series = {2019 IEEE Vehicle Power and Propulsion Conference (VPPC)}, booktitle = {2019 IEEE Vehicle Power and Propulsion Conference (VPPC)}, isbn = {978-1-7281-1249-7}, doi = {10.1109/VPPC46532.2019.8952317}, pages = {1 -- 6}, language = {en} } @inproceedings{ZieglerOeserArndtetal., author = {Ziegler, Andreas and Oeser, David and Arndt, Bernhard and Ackva, Ansgar}, title = {A Universal, Modular and Bidirectional Active Balancing System for Lithium-Ion Cells}, series = {Proceedings of the 10th International Scientific Symposium on Electrical Power Engineering}, booktitle = {Proceedings of the 10th International Scientific Symposium on Electrical Power Engineering}, editor = {University of Košice, Technical}, isbn = {978-80-553-3324-3}, pages = {400 -- 405}, language = {en} } @inproceedings{ZieglerOeserArndtetal., author = {Ziegler, Andreas and Oeser, David and Arndt, Bernhard and Ackva, Ansgar}, title = {Comparison of Active and Passive Balancing by a Long Term Test Including a Post-Mortem Analysis of all Single Battery Cells}, series = {2018 International IEEE Conference and Workshop in {\´O}buda on Electrical and Power Engineering (CANDO-EPE)}, booktitle = {2018 International IEEE Conference and Workshop in {\´O}buda on Electrical and Power Engineering (CANDO-EPE)}, isbn = {978-1-7281-1154-4}, doi = {10.1109/CANDO-EPE.2018.8601165}, pages = {15 -- 20}, language = {en} } @inproceedings{OeserZieglerArndtetal., author = {Oeser, David and Ziegler, Andreas and Arndt, Bernhard and Ackva, Ansgar}, title = {Effectiveness of Active Balancing on High Dispersion Batteries}, series = {2018 International IEEE Conference and Workshop in {\´O}buda on Electrical and Power Engineering (CANDO-EPE)}, booktitle = {2018 International IEEE Conference and Workshop in {\´O}buda on Electrical and Power Engineering (CANDO-EPE)}, isbn = {978-1-7281-1154-4}, doi = {10.1109/CANDO-EPE.2018.8601129}, pages = {21 -- 26}, language = {en} } @article{OeserZieglerAckva, author = {Oeser, David and Ziegler, Andreas and Ackva, Ansgar}, title = {Single cell analysis of lithium-ion e-bike batteries aged under various conditions}, series = {Journal of power sources}, volume = {397}, journal = {Journal of power sources}, issn = {0378-7753}, doi = {10.1016/j.jpowsour.2018.06.101}, pages = {25 -- 31}, language = {en} } @masterthesis{Ziegler, type = {Bachelor Thesis}, author = {Ziegler, Andreas}, title = {Erweiterung und Optimierung eines aktiven Batteriemanagementsystems f{\"u}r Fahrzeuge}, language = {en} } @misc{Ziegler, type = {Master Thesis}, author = {Ziegler, Andreas}, title = {Leistungselektronische Schaltungen f{\"u}r das aktive Batteriemanagement in Hybrid- und Elektrofahrzeugen in Verbindung mit deren Ladesystemen}, language = {en} }