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Millinger, J., Wallmark, O. & Soulard, J. (2018). High Frequency Characterization of Losses in FullyAssembled Stators of Slotless PM Motors. IEEE transactions on industry applications
Open this publication in new window or tab >>High Frequency Characterization of Losses in FullyAssembled Stators of Slotless PM Motors
2018 (English)In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367Article in journal (Refereed) Accepted
Abstract [en]

Abstract—The recent emerge of wide band-gap (WBG) powertransistors enables higher switching frequencies in electricalmotor drives. Their full utilization from a system point ofview requires quantification of the corresponding time-harmonicmotor losses. As an initial step, this paper presents a uniquestudy of stator losses for three different commercially availablenon-oriented silicon-iron (SiFe) steel grades (with laminationthicknesses 0.1, 0.2 and 0.3 mm). The investigations cover awide frequency range (10-100 kHz) at different levels of DC-bias(up to 1.6 T). Iron losses are identified from measurements onfully assembled stators, deploying a novel technique. By utilizingfully assembled stators, no additional samples are required.Manufacturing influence is inherently incorporated. Results showthat measured iron losses are twice as high at 10 kHz comparedto Epstein test results, which emphasizes the need to incorporatemanufacturing influence on iron losses at high frequencies. Thelevel of DC-bias is also observed to have a significant impacton iron losses (up to 30 %). Even though thinner laminationsare known for reducing iron losses, the reduction is much lowerthan anticipated in the studied frequency range due to skin effect.Using 0.1 mm lamination gauge instead of 0.3 mm reduces lossesby 50 % at 10 kHz, while the same substitution at 100 kHz onlyreduces losses by 30 %. Future work includes loss separation incomplete converter-fed machines.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018
Keywords
Permanent magnet machines, magnetic losses, harmonic analysis, wide band gap semiconductors.
National Category
Energy Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-221831 (URN)10.1109/TIA.2018.2806883 (DOI)000433089200032 ()2-s2.0-85042198389 (Scopus ID)
Note

QC 20180201

Available from: 2018-01-26 Created: 2018-01-26 Last updated: 2018-06-18Bibliographically approved
Krings, A., Cossale, M., Tenconi, A., Soulard, J., Cavagnino, A. & Boglietti, A. (2015). Characteristics comparison and selection guide for magnetic materials used in electrical machines. In: 2015 IEEE International Electric Machines Drives Conference (IEMDC): . Paper presented at 2015 IEEE International Electric Machines Drives Conference (IEMDC) (pp. 1152-1157). IEEE
Open this publication in new window or tab >>Characteristics comparison and selection guide for magnetic materials used in electrical machines
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2015 (English)In: 2015 IEEE International Electric Machines Drives Conference (IEMDC), IEEE , 2015, p. 1152-1157Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents an up-to-date magnetic materialinvestigation and overview on magnetic materials used in rotatingelectrical machines. The focus is on small to medium-sizedhigh-performance and high-efficiency permanent-magnet andinduction motors for different application scenarios. The inves-tigated materials include silicon-iron, nickel-iron, and cobalt-iron lamination steels, as well as soft magnetic composites andamorphous magnetic materials. The technical focus is on themagnetic properties and iron losses as well as the manufacturinginfluence and required thermal treatments during the manufac-turing process. A new loss to flux density factor is introducedto compare theBHmagnetization curve and the iron losses ofdifferent materials in the same diagram. The aim of the paper isto give the machine designer an efficient material overview andselection guide during the early machine design process.

Place, publisher, year, edition, pages
IEEE, 2015
Keywords
AC machines, amorphous magnetic materials, cobalt-iron, iron alloys, iron loss measurement, machine design, magnetic materials, nickel-iron, permanent magnet machines, silicon-iron, soft magnetic composites
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-185810 (URN)10.1109/IEMDC.2015.7409206 (DOI)000380534300169 ()
Conference
2015 IEEE International Electric Machines Drives Conference (IEMDC)
Note

QC 20160510

Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2016-10-05Bibliographically approved
Krings, A. & Soulard, J. (2015). Experimental characterization of magnetic materials for electrical machine applications. In: 2015 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD): . Paper presented at 2015 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD) (pp. 85-89). IEEE
Open this publication in new window or tab >>Experimental characterization of magnetic materials for electrical machine applications
2015 (English)In: 2015 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD), IEEE , 2015, p. 85-89Conference paper, Published paper (Refereed)
Abstract [en]

Most of the volume in classical electrical machinesis occupied by magnetic materials for creating an as good as possible magnetic path. In machines with planar flux paths (2Dgeometries) the material is laminated to reduce eddy current losses in the core. Manufacturers typically supply reference values from Epstein frame measurements as a material performance specification and an easy way for comparison. However, the magnetic flux path in electrical machines is more complex due to rotating magnetic fields passing through the stator (with or without teeth), the rotor, and the airgap. Therefore, other material characterization methods, such as ring core measurements, are more suitable to characterize the magnetic materials for electricalnmachines. This paper gives a short introduction on different methods to characterize magnetic materials and a detailed de-scription of building up a measurement system for characterizingring core samples or electrical machine stator cores. The system isdeveloped with regard to the IEC standard for measurements on magnetic ring core samples and can easily be build up in any lab with a power amplifier and a standard industrial control system equipped with analog input/output interfaces. Finally, reference measurements demonstrate the performance of the system.

Place, publisher, year, edition, pages
IEEE, 2015
Keywords
AC machine, iron alloys, loss measurement, machine design, magnetic hysteresis, magnetic losses, magnetic materials, nickel-iron, silicon-iron.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-185812 (URN)10.1109/WEMDCD.2015.7194514 (DOI)000380435600012 ()2-s2.0-84954550838 (Scopus ID)978-147998900-3 (ISBN)
External cooperation:
Conference
2015 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD)
Note

QC 20160502

Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2016-09-05Bibliographically approved
Cossale, M., Krings, A., Soulard, J., Boglietti, A. & Cavagnino, A. (2015). Practical Investigations on Cobalt–Iron Laminations for Electrical Machines. IEEE transactions on industry applications, 51(4), 2933-2939
Open this publication in new window or tab >>Practical Investigations on Cobalt–Iron Laminations for Electrical Machines
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2015 (English)In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 51, no 4, p. 2933-2939Article in journal (Refereed) Published
Abstract [en]

The adoption of high-performance soft magnetic material can be considered a possible way to respect the challenging design specifications for aerospace and automotive electrical machines. This paper presents an accurate noninvasive investigation of magnetic and energetic properties of cobalt–iron stator cores. In particular, the focus lies on the annealing processes aimed to maximize the magnetic saturation and the mechanical strength. Three cobalt–iron stator core samples coming from different annealing processes have been analyzed, both from the BH characteristics and losses viewpoints. Stator slot effects on the magnetic measurements have been investigated by finite-element method. A fringing effect correction factor to be applied on the measured BH curves is as well reported. In order to complete the experimental campaign analysis, micrographic analysis of the material structure is presented, as well as the iron losses separation coefficients.

Place, publisher, year, edition, pages
IEEE: , 2015
Keywords
BH characteristic, cobalt–iron laminations, electric machines, finite-element method (FEM), iron losses, magnetic material, micrographic structure, punching process, stator cores.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-172103 (URN)10.1109/TIA.2015.2394404 (DOI)000358255700024 ()2-s2.0-84937939405 (Scopus ID)
Note

QC 20150814

Available from: 2015-08-12 Created: 2015-08-12 Last updated: 2017-12-04Bibliographically approved
Krings, A., Soulard, J. & Wallmark, O. (2015). PWM Influence on the Iron Losses and Characteristics of a Slot-less Permanent Magnet Motor with SiFe and NiFe Stator Cores. IEEE transactions on industry applications, 51(2), Article ID 6891228.
Open this publication in new window or tab >>PWM Influence on the Iron Losses and Characteristics of a Slot-less Permanent Magnet Motor with SiFe and NiFe Stator Cores
2015 (English)In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 51, no 2, article id 6891228Article in journal (Refereed) Published
Abstract [en]

This paper investigates the influence of switching frequency and modulation index combined with welding on the iron losses in thin silicon-iron and nickel-iron lamination sheets of a small slot-less permanent magnet synchronous machine. First, measurements are conducted on welded and non-welded stator ring cores for switching frequencies between 1 kHz and 20 kHz and modulation indices of 0.4, 0.7, and 0.9, keeping constant fundamental flux density peak values. This is possible by changing the DC link voltage of the inverter. The obtained measurement data is afterwards used in finite element method (FEM) simulations to investigate the inverter influence on the performance of the permanent magnet synchronous machine.

Keywords
AC machines, iron alloys, loss measurement, nickel-iron, machine design, magnetic materials, permanent mag- net machines, PWM, silicon-iron
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-151259 (URN)10.1109/TIA.2014.2354735 (DOI)000351760400041 ()2-s2.0-84926388696 (Scopus ID)
Note

QC 20150429

Available from: 2014-09-16 Created: 2014-09-16 Last updated: 2017-12-05Bibliographically approved
Berglund, A., Havtun, H., Johansson, H. B., Jerbrant, A., Andersson, M., Hedin, B., . . . Kjellgren, B. (2015). The Pedagogical Developers Initiative – Changing Educational Practices and Strengthening CDIO skills. In: Proceedings of the 11th International CDIO Conference, Chengdu, China, June 8-11 2015: . Paper presented at 11th International CDIO Conference, Chengdu, China, June 8-11 2015.
Open this publication in new window or tab >>The Pedagogical Developers Initiative – Changing Educational Practices and Strengthening CDIO skills
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2015 (English)In: Proceedings of the 11th International CDIO Conference, Chengdu, China, June 8-11 2015, 2015Conference paper, Published paper (Refereed)
Abstract [en]

This paper put emphasis on change agents within the universities and how local initiatives can be systematically approached and ramped up. Rooted in the challenges and constraints that have been addressed in past educational program initiatives, the case consists of specific focus areas to leverage impact. Universities continuously strives to provide the best conditions for an inspiring and prosperous learning environment, and to provide educational programs with teaching of excellent educational quality. KTH is no exception and therefore the university management has initiated a pedagogical program starting in 2014. One of the first thing initiated within the framework of this pedagogical program is the creation of a group of 24 pedagogical developers.

The focus for the pedagogical developers is to facilitate the opportunities for KTHs faculty to work together and create consensus on educational development in different teaching teams. This paper presents the University's pedagogical developers' initiative as a whole and how this has been outlined in detail to reach specific redesign targets. The School of Industrial Engineering and Management pedagogical group consists of five practicing teachers that besides this new role also engage heavily in various courses of the School's departments. Since the pedagogical initiative is aligned with several important CDIO aspects, e.g. the learning environment, formats of formative feedback, assessment and examination there is also importance to reassure this in the existing Master level programs.

At KTH the five-year comprehensive Master of Science in Engineering programs concern distinct vocational educations in which the CDIO aspects are very important. At the same time the programs has been divided in a basic level (B.Sc. in Engineering) of three years and a advanced level (M.Sc.) of two years. This has for instance made it harder to align the progression between first cycle level and second cycle level regarding for instance the CDIO efforts (e.g. oral and written communication, teamwork). This paper will therefore discuss and enhance how the pedagogical programme, we as pedagogical developers, can support and strengthen the initiation and implementation of the CDIO aspects in the education.

National Category
Educational Sciences
Identifiers
urn:nbn:se:kth:diva-177787 (URN)
Conference
11th International CDIO Conference, Chengdu, China, June 8-11 2015
Note

QC 20151210

Available from: 2015-11-26 Created: 2015-11-26 Last updated: 2016-07-04Bibliographically approved
Antonopoulos, A., Mörée, G., Soulard, J., Ängquist, L. & Nee, H.-P. (2014). Experimental evaluation of the impact of harmonics on induction motors fed by modular multilevel converters. In: Proceedings - 2014 International Conference on Electrical Machines, ICEM 2014: . Paper presented at 21st International Conference on Electrical Machines, ICEM 2014, 2 September 2014 through 5 September 2014 (pp. 768-775).
Open this publication in new window or tab >>Experimental evaluation of the impact of harmonics on induction motors fed by modular multilevel converters
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2014 (English)In: Proceedings - 2014 International Conference on Electrical Machines, ICEM 2014, 2014, p. 768-775Conference paper, Published paper (Refereed)
Abstract [en]

Inverter-based electrical-machine drives suffer from significantly higher losses compared to sinusoidal-supply-based alternatives, fed directly from the grid. Using multilevel inverters it becomes possible to partially mitigate the effects of the switched supply waveform, while keeping the advantages of variable-speed operation. This paper aims to evaluate the increase of the losses occurring in an induction motor (IM) fed by a modular multilevel converter (M2C), when compared to grid-connected operation, in order to evaluate the impact of the inverter-generated harmonics in the machine. It is confirmed that the losses created in the motor due to the harmonic content of the inverter-generated waveforms are very low, and almost equivalent to a purely sinusoidal supply. The investigation includes an analysis of the harmonic content from experimental waveforms obtained by an 11-kW IM laboratory setup, and it is further supported by measurements of the temperature rise in the IM-stator windings. It is concluded that the M2C could create the conditions even for high-power motors to be operated without any derating.

Keywords
Harmonic Distortion, Harmonic Losses, Induction Machines, Inverter, Modular Multilevel Converters, Temperature Measurements, Winding Resistance, Electric inverters, Electric machinery, Electric resistance, Harmonic analysis, Machine windings, Temperature measurement, Winding, Harmonic loss, Winding resistances, Induction motors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-168852 (URN)10.1109/ICELMACH.2014.6960268 (DOI)000358567800113 ()2-s2.0-84916197075 (Scopus ID)9781479943890 (ISBN)
Conference
21st International Conference on Electrical Machines, ICEM 2014, 2 September 2014 through 5 September 2014
Note

QC 20150612

Available from: 2015-06-12 Created: 2015-06-09 Last updated: 2015-09-11Bibliographically approved
Krings, A., Nategh, S., Wallmark, O. & Soulard, J. (2014). Influence of the Welding Process on the Performance of Slotless PM Motors With SiFe and NiFe Stator Laminations. IEEE transactions on industry applications, 50(1), 296-306
Open this publication in new window or tab >>Influence of the Welding Process on the Performance of Slotless PM Motors With SiFe and NiFe Stator Laminations
2014 (English)In: IEEE transactions on industry applications, ISSN 0093-9994, E-ISSN 1939-9367, Vol. 50, no 1, p. 296-306Article in journal (Refereed) Published
Abstract [en]

The influence of the welding process during the manufacturing of small slotless permanent-magnet synchronous machines (PMSMs) is studied in this paper. The focus lies on the change of the magnetic properties in high-quality silicon-iron (SiFe) and nickel-iron (NiFe) electrical steel sheets with thicknesses of 0.1 and 0.2 mm. It is shown that the welding process changes the magnetic material properties significantly and increases the specific iron losses. Experimental results are provided for magnetic flux densities up to 1.5 T and frequencies from quasi-static to 200 Hz. The obtained measurement data is afterward used in finite-element method (FEM) simulations to investigate the influence of the magnetic property changes on the motor performance, particularly with regard to stator core losses.

Place, publisher, year, edition, pages
IEEE Press, 2014
Keywords
Magnetic hysteresis, magnetic losses, magnetic materials, nickel-iron alloys, permanent magnet machines, siliconiron alloys, slot-less machines
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-122210 (URN)10.1109/TIA.2013.2270972 (DOI)000330228100036 ()2-s2.0-84893329891 (Scopus ID)
Projects
HPD
Funder
StandUp
Note

QC 20130710

Available from: 2013-05-14 Created: 2013-05-14 Last updated: 2017-12-06Bibliographically approved
Krings, A., Cossale, M., Tenconi, A. & Soulard, J. (2014). Magnetic Materials for Electrical Machines: a Selection Guide from the Engineering Application Point of View. In: : . Paper presented at IEEE International Magnetics Conference (INTERMAG); Dresden, Germany, May 4-8, 2014.
Open this publication in new window or tab >>Magnetic Materials for Electrical Machines: a Selection Guide from the Engineering Application Point of View
2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
Keywords
AC machines, cobalt-iron, iron alloys, iron loss measurement, machine design, magnetic materials, nickel-iron, permanent magnet machines, silicon-iron, soft magnetic composites
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-145241 (URN)
Conference
IEEE International Magnetics Conference (INTERMAG); Dresden, Germany, May 4-8, 2014
Note

QC 20150409

Available from: 2014-05-14 Created: 2014-05-14 Last updated: 2015-04-09Bibliographically approved
Krings, A., Cossale, M., Soulard, J., Boglietti, A. & Cavagnino, A. (2014). Manufacturing influence on the magnetic properties and iron losses in cobalt-iron stator cores for electrical machines. In: IEEE Conference Publications (Ed.), Proceedings - Energy Conversion Congress and Exposition (ECCE), 2014 IEEE: . Paper presented at 6th Annual IEEE Energy Conversion Congress and Exhibition, ECCE 2014; David L. Lawrence Convention CenterPittsburgh; United States; 14 September 2014 through 18 September 2014 (pp. 5595-5601).
Open this publication in new window or tab >>Manufacturing influence on the magnetic properties and iron losses in cobalt-iron stator cores for electrical machines
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2014 (English)In: Proceedings - Energy Conversion Congress and Exposition (ECCE), 2014 IEEE / [ed] IEEE Conference Publications, 2014, p. 5595-5601Conference paper, Published paper (Refereed)
Abstract [en]

The manufacturing influence on the magnetic properties and iron losses in stator cores made of cobalt-iron is investigated in this study, with a focus on the annealing and stacking process. Hysteresis and iron loss curves from measurements as well as a microscopic structure analysis are presented. FEM simulations are used to investigate the fringing effect in the stator cores due to the stator slots and others geometrical effects. A correction factor is derived and applied to the measurements. Furthermore, it is shown, that for cobalt-iron lamination sheets, the annealing process with an exact temperature and duration is absolutely essential to achieve expected magnetic and mechanical properties in the material.

Keywords
electric machines, magnetic materials, iron losses, cobalt iron, electromagnetic measurements, finite-element simulations, annealing, thermal treatment
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-172105 (URN)10.1109/ECCE.2014.6954167 (DOI)2-s2.0-84934343986 (Scopus ID)9781479956982 (ISBN)
Conference
6th Annual IEEE Energy Conversion Congress and Exhibition, ECCE 2014; David L. Lawrence Convention CenterPittsburgh; United States; 14 September 2014 through 18 September 2014
Note

QC 20150813

Available from: 2015-08-12 Created: 2015-08-12 Last updated: 2015-10-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8990-3745

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