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Publications (10 of 88) Show all publications
Bessman, A., Soares, R., Wallmark, O., Svens, P. & Lindbergh, G. (2019). Aging effects of AC harmonics on lithium-ion cells. Journal of Energy Storage, 21, 741-749
Open this publication in new window or tab >>Aging effects of AC harmonics on lithium-ion cells
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2019 (English)In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 21, p. 741-749Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Lithium-ion, ripple-current, harmonics, aging
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Other Chemical Engineering
Research subject
Electrical Engineering; Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-241643 (URN)10.1016/j.est.2018.12.016 (DOI)000459203100066 ()2-s2.0-85060290744 (Scopus ID)
Note

QC 20190125

Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-05-17Bibliographically approved
Du-Bar, C., Mann, A., Wallmark, O. & Werke, M. (2019). Comparison of Performance and Manufacturing Aspects of an Insert Winding and a Hairpin Winding for an Automotive Machine Application. In: 2018 8th International Electric Drives Production Conference, EDPC 2018 - Proceedings: . Paper presented at 8th International Electric Drives Production Conference, EDPC 2018, 4 December 2018 through 5 December 2018. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Comparison of Performance and Manufacturing Aspects of an Insert Winding and a Hairpin Winding for an Automotive Machine Application
2019 (English)In: 2018 8th International Electric Drives Production Conference, EDPC 2018 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, two stators with different winding concepts but with the same rotor of an interior permanent magnet synchronous machine (IPMSM) type are presented. Both concepts are investigated based on their performance and their respectively stator cost and stator manufacturing aspects for a yearly production rate of 1 million units.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Costs, Eddy currents, Electric drives, Manufacture, Permanent magnets, Production control, Rotors (windings), Skin effect, Stators, Winding, Automotive, Hairpin windings, Mass production, Production Planning, Proximity effects, Electric windings
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-252030 (URN)10.1109/EDPC.2018.8658331 (DOI)2-s2.0-85063505311 (Scopus ID)
Conference
8th International Electric Drives Production Conference, EDPC 2018, 4 December 2018 through 5 December 2018
Note

QC 20190625

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2019-06-25Bibliographically approved
Acquaviva, A., Wallmark, O., Grunditz, E. A., Lundmark, S. T. & Thiringer, T. (2019). Computationally Efficient Modeling of Electrical Machines With Cooling Jacket. IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION, 5(3), 618-629
Open this publication in new window or tab >>Computationally Efficient Modeling of Electrical Machines With Cooling Jacket
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2019 (English)In: IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION, ISSN 2332-7782, Vol. 5, no 3, p. 618-629Article in journal (Refereed) Published
Abstract [en]

Modeling of electrical machines is a multiphysics problem. Depending on the phenomena of interest and the computational time constraint, this can be done at different levels of detail. In this article, the main approaches to model the thermal behavior of electrical machines with a liquid cooled casing around the stator (often referred to as cooling jacket) are analyzed and a novel approach is presented. The proposed method aims at creating computationally efficient 3-D multiphysics models of electrical machines with liquid cooled jacket. This model is based on the assumption of a fully developed flow in the cooling jacket which allows to scale the computational fluid dynamics (CFD) simulation to 1-D. The slot with a two layer concentrated winding and potting material is modeled using a composite material comprising of both the conductors and slot filler. Similarly, a unified material is used to model the end-windings. Experimental results on a traction machine for vehicle applications are presented showing good agreement with the simulations. Also, a comparison with a 3-D CFD is presented to verify the pressure drop in the pipe bend. Finally, the model is used to simulate a dynamic load cycle, which would be computationally extremely demanding with combined 3-D CFD and thermal FEA of the machine and its cooling.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
Computational fluid dynamics (CFD), cooling, electrical machines, thermal analysis, traction motors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-261972 (URN)10.1109/TTE.2019.2936122 (DOI)000487201100003 ()
Note

QC 20191014

Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2019-10-14Bibliographically approved
Millinger, J., Bacco, G., Manzolini, V., Wallmark, O. & Bianchi, N. (2019). Design and Evaluation of a Short-Circuit Rotor-Ring for Enhanced Self-Sensing Capability in a Slotless PM Motor. IEEE transactions on industrial electronics (1982. Print)
Open this publication in new window or tab >>Design and Evaluation of a Short-Circuit Rotor-Ring for Enhanced Self-Sensing Capability in a Slotless PM Motor
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2019 (English)In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948Article in journal (Refereed) Epub ahead of print
Abstract [en]

This paper deals with the design and evaluation of a short-circuit rotor-ring for enhanced self-sensing capability in a 2-pole slotless permanent-magnet motor. High-frequency rotor anisotropy is enabled by adding as hort-circuited rotor-ring. Optimal ring-dimensions are determined by parametric numerical studies. An effective high-frequency saliency of up to 1.8 is demonstrated. The steady-state estimation error is within ±2◦, practically unaffected by current level (in contrast to slotted self-sensing electrical machinery) due to the large effective air-gap. The proposed observer performs properly also during dynamic load changes. Fall-times from 3000 to 0 rpm in less than 50 ms with negligible overshoot are demonstrated. Also parasitic effects such as power losses, heating and torque ripple are analyzed.

Keywords
Rotor position estimation, saliency-based sensorless control, self-sensing, slotless permanent magnet motor.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-253269 (URN)10.1109/TIE.2019.2921266 (DOI)
Funder
StandUpSwedish Energy Agency, 44162-1
Note

QC 20190802

Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2019-08-02Bibliographically approved
Millinger, J., Wallmark, O. & Soulard, J. (2019). Investigation of Harmonic Losses in a 2-PoleSlotless Permanent-Magnet Motor due to WideBand-Gap Inverter Supply. IEEE transactions on industrial electronics (1982. Print)
Open this publication in new window or tab >>Investigation of Harmonic Losses in a 2-PoleSlotless Permanent-Magnet Motor due to WideBand-Gap Inverter Supply
2019 (English)In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948Article in journal (Refereed) Accepted
Abstract [en]

The recent emerge of wide band-gap powerdevices enables higher switching frequencies in electric motor drives. The subsequent possibility for higher efficiencyand smaller size requires accurate prediction of harmonic losses in motors. Therefore this paper presents an original analysis of harmonic losses arising in inverter-fed 2-pole slotless permanent-magnet machines with axially segmented ring magnets. The developed three-dimensional time-efficient numerical model is successfully validated under high-speed no-load operation using a silicon-carbide based three-phase inverter and rotors carrying a broad range of magnet segment thicknesses (3–12.6 mm). The model enables harmonic loss prediction capability (including loss separation) with an accuracy of 15 % over a wide frequency range (8–120 kHz), which is a unique contribution. The sensitivity analysis primarily emphasizes the importance of taking into account the axial segmentation, and secondarily the rotor-shaft magneto-elasticity effects for accurate modeling of harmonic losses. The conducted case-study demonstrates that wide band-gap transistors effectively can contribute to eliminating the need for inductive filters in motor drives.

Keywords
Time-harmonic losses, permanent-magnet machines, wide band-gap semiconductors
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-259945 (URN)10.1109/TIE.2019.2939985 (DOI)
Note

QC 20190925

Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-10-09Bibliographically approved
Bitsi, K., Wallmark, O. & Bosga, S. (2019). Many-objective Optimization of IPM and Induction Motors for Automotive Application. In: : . Paper presented at 2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe).
Open this publication in new window or tab >>Many-objective Optimization of IPM and Induction Motors for Automotive Application
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a Pareto-optimality-based optimization methodology suitable for the design of electrical motors in automotive applications. The proposed many-objective evolutionary algorithm is utilized in this study case for the optimization of an interior permanent-magnet (IPM) synchronous motor and an induction motor (IM), considering as criteria the motors' torque capability, efficiency as well as torque density. Finite-element (FE) models of the investigated motor topologies are developed and incorporated in the optimization process in order to ensure an accurate estimation of their electromagnetic performance. The attainment of the targeted specifications by the final optimal designs validates the efficacy of the implemented optimization algorithm.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-264770 (URN)
Conference
2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe)
Note

QC 20191203

Available from: 2019-12-03 Created: 2019-12-03 Last updated: 2019-12-03Bibliographically approved
Nikouie, M., Zhang, H., Wallmark, O. & Nee, H.-P. (2018). A highly integrated electric drive system for tomorrow's EVs and HEVs. In: Proceedings - 2017 IEEE Southern Power Electronics Conference, SPEC 2017: . Paper presented at 2017 IEEE Southern Power Electronics Conference, SPEC 2017, Hotel Enjoy Puerto VarasPuerto Varas, Chile, 4 December 2017 through 7 December 2017 (pp. 1-5). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>A highly integrated electric drive system for tomorrow's EVs and HEVs
2018 (English)In: Proceedings - 2017 IEEE Southern Power Electronics Conference, SPEC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1-5Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents an ultra-compact integrated electric drive prototype. The prototype illustrates the integration of a fractional slot concentrated winding (FSCW) electric motor, a stacked polyphase bridges (SPB) converter, the control boards, and the water cooling plates into a common housing. This integrated prototype offers a high potential of compactness and cost reduction for electric and hybrid electric vehicles.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-238250 (URN)10.1109/SPEC.2017.8333555 (DOI)2-s2.0-85049217902 (Scopus ID)9781509064250 (ISBN)
Conference
2017 IEEE Southern Power Electronics Conference, SPEC 2017, Hotel Enjoy Puerto VarasPuerto Varas, Chile, 4 December 2017 through 7 December 2017
Note

QC 20181120

Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2019-04-11Bibliographically approved
Soares, R., Bessman, A., Wallmark, O., Lindbergh, G. & Svens, P. (2018). An Experimental Setup with Alternating Current Capability for Evaluating Large Lithium-Ion Battery Cells. Batteries-Basel, 4(3), Article ID 38.
Open this publication in new window or tab >>An Experimental Setup with Alternating Current Capability for Evaluating Large Lithium-Ion Battery Cells
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2018 (English)In: Batteries-Basel, ISSN 2313-0105, Vol. 4, no 3, article id 38Article in journal (Refereed) Published
Abstract [en]

In the majority of applications using lithium-ion batteries, batteries are exposed to some harmonic content apart from the main charging/discharging current. The understanding of the effects that alternating currents have on batteries requires specific characterization methods and accurate measurement equipment. The lack of commercial battery testers with high alternating current capability simultaneously to the ability of operating at frequencies above 200 Hz, led to the design of the presented experimental setup. Additionally, the experimental setup expands the state-of-the-art of lithium-ion batteries testers by incorporating relevant lithium-ion battery cell characterization routines, namely hybrid pulse power current, incremental capacity analysis and galvanic intermittent titration technique. In this paper the hardware and the measurement capabilities of the experimental setup are presented. Moreover, the measurements errors due to the setup’s instruments were analysed to ensure lithium-ion batteries cell characterization quality. Finally, this paper presents preliminary results of capacity fade tests where 28 Ah cells were cycled with and without the injection of 21 A alternating at 1 kHz. Up to 300 cycles, no significant fade in cell capacity may be measured, meaning that alternating currents may not be as harmful for lithium-ion batteries as considered so far.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
alternating current, aging, battery testing, electric vehicles, GITT, HPPC, life cycle, lithium-ion batteries, ripple, SOC
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-233339 (URN)10.3390/batteries4030038 (DOI)000445206100009 ()
Note

QC 20180816

Available from: 2018-08-15 Created: 2018-08-15 Last updated: 2018-10-12Bibliographically approved
Bessman, A., Soares, R., Vadivelu, S., Wallmark, O., Svens, P., Ekström, H. & Lindbergh, G. (2018). Challenging Sinusoidal Ripple-Current Charging of Lithium-Ion Batteries. IEEE transactions on industrial electronics (1982. Print), 65(6), 4750-4757
Open this publication in new window or tab >>Challenging Sinusoidal Ripple-Current Charging of Lithium-Ion Batteries
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2018 (English)In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 65, no 6, p. 4750-4757Article in journal (Refereed) Published
Abstract [en]

Sinusoidal ripple-current charging has previously been reported to increase both charging efficiency and energy efficiency and decrease charging time when used to charge lithium-ion battery cells. In this paper, we show that no such effect exists in lithium-ion battery cells, based on an experimental study of large-size prismatic cells. Additionally, we use a physics-based model to show that no such effect should exist, based on the underlying electrochemical principles.

Place, publisher, year, edition, pages
IEEE Press, 2018
Keywords
Fast charging, lithium-ion (Li-ion) battery, sinusoidal ripple charging
National Category
Other Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-223315 (URN)10.1109/TIE.2017.2772160 (DOI)000425618900031 ()2-s2.0-85034238750 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180222

Available from: 2018-02-16 Created: 2018-02-16 Last updated: 2019-05-17Bibliographically approved
Jin, L., Norrga, S., Wallmark, O. & Apostolopoulos, N. (2018). Communication-Based Distributed Control of the Stacked Polyphase Bridges Converter. IEEE transactions on industrial electronics (1982. Print), 65(2), 1011-1020
Open this publication in new window or tab >>Communication-Based Distributed Control of the Stacked Polyphase Bridges Converter
2018 (English)In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 65, no 2, p. 1011-1020Article in journal (Refereed) Published
Abstract [en]

The stacked polyphase bridges converter has gained increasing interest in recent years due to its modular design and easy adaption to different power levels. The real-time control and dynamic data transmission of a stacked polyphase bridges converter consisting of a number of submodules are challenging tasks. For the reason that the distributed control architecture can maintain the benefit of modularity, such an approach dedicated for the stacked polyphase bridges converter is presented in this paper. Suitable communication techniques and synchronization techniques for the presented architecture are discussed. In addition, based on a dynamic model of the converter, the sensitiveness of the distributed control system to communication bandwidth and delay is studied on an experimental prototype.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Distributed control, modular converter, serial peripheral interface, stacked polyphase bridges (SPB) converter
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-220805 (URN)10.1109/TIE.2017.2723874 (DOI)000418415200006 ()2-s2.0-85023182137 (Scopus ID)
Note

QC 20180116

Available from: 2018-01-16 Created: 2018-01-16 Last updated: 2018-03-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6283-7661

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