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Aging effects of AC harmonics on lithium-ion cells
KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.ORCID-id: 0000-0002-0108-1872
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik. (EMaDLab)ORCID-id: 0000-0002-9481-7366
KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik. (EMaDLab)ORCID-id: 0000-0002-6283-7661
KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.ORCID-id: 0000-0001-9559-0004
Visa övriga samt affilieringar
2019 (Engelska)Ingår i: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 21, s. 741-749Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

With the vehicle industry poised to take the step into the era of electric vehicles, concerns have been raised that AC harmonics arising from switching of power electronics and harmonics in electric machinery may damage the battery. In light of this, we have studied the effect of several different frequencies on the aging of 28 Ah commercial NMC/graphite prismatic lithium-ion battery cells. The tested frequencies are 1 Hz, 100 Hz, and 1 kHz, all with a peak amplitude of 21 A. Both the effect on cycled cells and calendar aged cells is tested. The cycled cells are cycled at a rate of 1C:1C, i.e., 28 A during both charging and discharging, with the exception of a period of constant voltage at the end of every charge. After running for one year, the cycled cells have completed approximately 2000 cycles. The cells are characterized periodically to follow how their capacities and power capabilities evolve. After completion of the test about 80% of the initial capacity remained and no increase in resistance was observed. No negative effect on either capacity fade or power fade is observed in this study, and no difference in aging mechanism is detected when using non-invasive electrochemical methods of post mortem investigation.

Ort, förlag, år, upplaga, sidor
Elsevier, 2019. Vol. 21, s. 741-749
Nyckelord [en]
Lithium-ion, ripple-current, harmonics, aging
Nationell ämneskategori
Annan elektroteknik och elektronik Annan kemiteknik
Forskningsämne
Elektro- och systemteknik; Kemiteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-241643DOI: 10.1016/j.est.2018.12.016ISI: 000459203100066Scopus ID: 2-s2.0-85060290744OAI: oai:DiVA.org:kth-241643DiVA, id: diva2:1282270
Anmärkning

QC 20190125

Tillgänglig från: 2019-01-24 Skapad: 2019-01-24 Senast uppdaterad: 2019-05-17Bibliografiskt granskad
Ingår i avhandling
1. Modeling and Analysis of the Interaction of Batteries and Power Electronic Converters
Öppna denna publikation i ny flik eller fönster >>Modeling and Analysis of the Interaction of Batteries and Power Electronic Converters
2019 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis deals with the interaction of batteries and power electronic converters in automotive applications. Even if the additional heating caused by (unwanted) alternating currents is disregarded, there has been a concern that alternating currents can be harmful for batteries. For that reason, alternating currents can be filtered using capacitors and/or by sophisticated hardware. In this work, the concern whether alternating currents are harmful to batteries is studied particular focus on large, lithium-ion cells for use in automotive applications.First, the harmonic content in the battery current of two, commercial hybrid-electric busses were measured and analysed. The most prominent harmonic had a peak magnitude higher than 10% of the maximum direct current level (160 A) arising at frequencies below 150 Hz. The maximum amplitude detected of a harmonic caused by the voltage source converter’s switching action was around 10 A and occurred at a frequency of 2 kHz. An experimental setup with alternating current capability for evaluating large lithium-ion cells has been designed and built. Twelve lithium-ion cells were cycled at a rate if 1 C during approximately 2000 cycles (corresponding to approximately one year). The cells were cycled with an superimposed alternating current of 1 Hz, 100 Hz, or 1 kHz while the rest of the cells were cycled with direct current (only), injected with alternating current (only), or no current at all (calendar aging). No negative effects caused by the alternating current was identified in terms of capacity fade and power fade for the tested lithium-ion cells. A comparison between sinusoidal current-ripple charging and conventional constant-current constant-voltage charging was also carried out. Three lithium-ion cells were cycled (ten times) with different ac currents superimposed during charge. The results were analyzed statistically and no significant improvements in terms of charging time or charging efficiency were observed in any of the charging tests using an superimposed ac current. The injection of alternating currents into batteries for heating purposes has also been studied and a control method for battery heating using an ac current was proposed. The proposed controller is applicable regardless of the LIB’s subsequent impedance nature (capacitive, inductive or resistive). Further, a design process for the generation of magnified alternating currents in dc-dc converters was presented. By matching the switching frequency with the frequency where the LCL filter and the battery resonate, the current flowing in the semiconductors and the switching frequency could be reduced. In a small experimental setup using a single lithium-ion cell, using an LCL-resonant circuit and a full bridges witch arrangement, magnifications of up to 15.7 were reached. This allowed for a loss reduction in the semiconductors of up to 75%, when compared to an equivalent dc-dc converter enabled to produce anon-magnified ac current. 

Ort, förlag, år, upplaga, sidor
Stockholm, Sweden: KTH Royal Institute of Technology, 2019. s. 184
Serie
TRITA-EECS-AVL ; 2019:45
Nyckelord
Alternating current, aging, electric vehicles, harmonics, lithium-ion batteries, power converter, resonant filters, ripple, temperature control.
Nationell ämneskategori
Annan elektroteknik och elektronik
Forskningsämne
Elektro- och systemteknik
Identifikatorer
urn:nbn:se:kth:diva-251665 (URN)978-91-7873-187-9 (ISBN)
Disputation
2019-06-05, Kollegiesalen, Brinellvägen 8, Kungliga Tekniska högskolan, Stockholm, 14:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20190517

Tillgänglig från: 2019-05-17 Skapad: 2019-05-17 Senast uppdaterad: 2019-06-17Bibliografiskt granskad

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Av författaren/redaktören
Bessman, AlexanderSoares, RúdiWallmark, OskarSvens, PontusLindbergh, Göran
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Tillämpad elektrokemiElkraftteknik
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Journal of Energy Storage
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