Demagnetization Assessment for Three-Phase Tubular Brushless Permanent-Magnet Machines

Wang, J.; Wang, W.; Atallah, K.; Howe, D.

doi:10.1109/tmag.2008.2001074

Cited by 72 publications

(27 citation statements)

References 21 publications

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“…Thus, if phase windings A1 and A2 are connected in series or parallel with the opposite polarity, and the similar connections are made for B1 and B2, and C1 and C2, respectively, the resultant 5 th order mmf space harmonic produced by the first 3-phase windings and that by the second 3-phase windings are in phase with respect to each other. The 5 th order space harmonic has the same number of pole-pairs as that of the active part of the mover, and its interaction with the 5 pole-pair mover magnetic field produces the electromagnetic force. For all even (n = 2, 4, 8,…) space harmonics, the phase shift between the harmonics produced by the first 3-phase windings and those by the second 3-phase windings is (n + 1)π.…”

Section: Fractional Slot Winding Configurations With Low Space Harmonicsmentioning

confidence: 99%

“…The most common approach is to segment the mover magnets both axially and circumferentially in order to reduce the eddy current loss in the mover. Without this, the heat generated by the eddy current loss in the mover magnets may be exces sive and may result in irreversible demagneti-zation [5]. However, this significantly increases the manufacturing cost and material usage (materials being wasted during segmentation process), and does not address the other undesirable effects.…”

Section: Introductionmentioning

confidence: 99%

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Performance evaluation of fractional-slot tubular permanent magnet machines with low space harmonics

Wang

2015

Archives of Electrical Engineering

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This paper evaluates the perforamnce of fractional-slot per pole winding configurations for tubular permanent magnet (PM) machines that can effectively eliminate the most undesirable space harmonics in a simple and cost-effective manner. The benefits of the proposed machine topology winding configurations are illustrated through comparison with 9-slot, 10-pole tubular PM machine developed for a free piston energy converter under the same specification and volumetric constraints. It has been shown that the proposed machine topology results in more than 7 times reduction in the eddy current loss in the mover magnets and supporting tube, and hence avoids potential problem of excessive mover temperature and risk of demagnetization.

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Section: Fractional Slot Winding Configurations With Low Space Harmonicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance evaluation of fractional-slot tubular permanent magnet machines with low space harmonics

Wang

2015

Archives of Electrical Engineering

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“…i) The temperature distribution in the magnet segments will not be uniform, and the temperature will be higher in the segment with greater loss. Consequently, demagnetization risk will be increased [22]. ii) When the resistance limited model is employed to quantify 3-D eddy-current loss in PM brushless machines via magnetostatic analogy [23], the total loss cannot be determined by calculating loss in one magnet segment and multiplying the result by the number of segments.…”

Section: Eddy-current Loss In Rotor Magnetsmentioning

confidence: 99%

“…To rectify this problem, the rotor eddy-current distribution is formulated in this paper as a sum of space and time harmonics for each frequency and the eddy-current loss is calculated by summing the losses of all frequency components. It is shown that when the magnets in each pole are segmented into more than two pieces, the eddy loss in each equally segmented piece may differ by a large margin, which implies that the temperature distribution in the magnets will be uneven and the risk of demagnetization has to be carefully assessed [22]. The theoretical 0018-9464/$26.00 © 2010 IEEE derivation is validated by time-stepped transient finite-element analysis.…”

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confidence: 99%

Rotor Eddy-Current Loss in Permanent-Magnet Brushless AC Machines

et al. 2010

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Article:Wang, J., Atallah, K., Chin, R. et al. (2 more ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. This paper analyzes rotor eddy-current loss in permanent-magnet brushless ac machines. It is shown that analytical or finite-element techniques published in literature for predicting rotor eddy-current loss using space harmonic based approaches may not yield correct results in each magnet segment when one magnet-pole is circumferentially segmented into more than two pieces. It is also shown that the eddy-current loss in each equally segmented piece may differ by a large margin, which implies that the temperature distribution in the magnets will be uneven and the risk of demagnetization has to be carefully assessed. The theoretical derivation is validated by time-stepped transient finite-element analysis.Index Terms-Eddy-current loss, permanent-magnet brushless machines.

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“…Without this, the heat generated by the eddy current loss in the rotor magnets may be excessive and may result in irreversible demagnetization [17]. However, this significantly increases the manufacturing cost and material usage (materials being wasted during segmentation process), and does not address the other undesirable effects.…”

Section: Introductionmentioning

confidence: 99%

Six-Phase Fractional-Slot-per-Pole-per-Phase Permanent-Magnet Machines With Low Space Harmonics for Electric Vehicle Application

Patel

Wang

et al. 2014

IEEE Trans. on Ind. Applicat.

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Abstract-The paper discusses the development of new winding configurations for 6-phase permanent magnet (PM) machines with 18-slot, 8-pole, that eliminates and/or reduces undesirable space harmonics in the stator magneto motive force (MMF). The proposed configuration improves power/torque density and efficiency with a reduction in eddy current losses in the rotor permanent magnets and copper losses in end windings. To improve drive train availability for applications in electric vehicles, the paper proposes the design of 6-phase permanent magnet machine as two independent 3-phase windings. A number of possible phase shifts between two sets of 3-phase windings due to their slot-pole combination and winding configuration is investigated and the optimum phase shift is selected by analyzing the harmonic distributions and their effect on machine performance including the rotor eddy current losses. The machine design is optimized for a given set of specifications for electric vehicle (EV), under electrical, thermal and volumetric constraints, and demonstrated by the experimental measurements on a prototype machine.Index Terms-Design methodology, Design optimization Electric vehicles, Permanent magnet machines. I. INTRODUCTIONECENTLY, the development of fault tolerant motor drives employing permanent magnet (PM) machines for electric vehicles (EV) has received increasing attention due to the emphasis on passenger comfort and safety by the automotive industries around the world [1]- [4]. Although electric vehicles are hailed as fuel economic and low-or no-emissions, their ability to tolerate fault is very critical as a fault in the electric drive will result in a complete loss of power and may lead to an accident [2]. Due to their high torque/power density and higher efficiency compared to other machine technologies, PM brushless machines are preferred technology in traction applications [5], [6], provided they could continue to operate following isolated failures in power train drive.For traction applications, it is an attractive option to employ Manuscript received August 10, 2013; revised October 12, 2013. This work was supported in part by the European Commission for CASTOR project under European Green Cars Initiative through Grant No. 260176.V. I. Patel, J. Wang, W. Wang, and X. Chen are with the Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, S13JD, United Kingdom (e-mail: vip.iitd@outlook.com, j.b.wang@sheffield.ac.uk).relatively newer winding configurations of PM brushless machines often referred to as fractional-slot concentrated winding or modular winding [6]- [9], because of their numerous advantages over the overlapped distributed windings in the conventional brushless AC machines, such as high winding factor, high copper packing factor [10], short end-windings, and hence, high efficiency [11], reduction in the likelihood of an inter-phase fault and extremely low cogging torque [12].However, fractional-slot windings produce a large number of space harmonics in the...

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Demagnetization Assessment for Three-Phase Tubular Brushless Permanent-Magnet Machines

Cited by 72 publications

References 21 publications

Performance evaluation of fractional-slot tubular permanent magnet machines with low space harmonics

Performance evaluation of fractional-slot tubular permanent magnet machines with low space harmonics

Rotor Eddy-Current Loss in Permanent-Magnet Brushless AC Machines

Six-Phase Fractional-Slot-per-Pole-per-Phase Permanent-Magnet Machines With Low Space Harmonics for Electric Vehicle Application

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