Additional losses in permanent magnet brushless machines

Maga, Dušan; Zagirnyak, Мykhaylo; Miljavec, Damijan

doi:10.1109/epepemc.2010.5606520

Cited by 39 publications

(18 citation statements)

References 2 publications

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“…It set equal to zero if there is no current in the stator slots winding v, s and B r are the magnetic reluctivity, electric conductivity and magnet remanent magnetizing vector, respectively. In our 2-D finite-element analyses, permanent magnets are described as massive conductors (Benabou et al, 2008) meaning that the source condition on current density J is (Maga et al, 2010):…”

Section: Eddy Current Losses Analysismentioning

confidence: 99%

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Investigation of magnet segmentation techniques for eddy current losses reduction in permanent magnets electrical machines

Belli

Mékidèche

2015

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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Purpose -Reducing eddy current losses in magnets of electrical machines can be obtained by means of several techniques. The magnet segmentation is the most popular one. It imposes the least restrictions on machine performances. This paper investigates the effectiveness of the magnet circumferential segmentation technique to reduce these undesirable losses. The full and partial magnet segmentation are both studied for a frequency range from few Hz to a dozen of kHz. To increase the efficiency of these techniques to reduce losses for any working frequency, an optimization strategy based on coupling of finite elements analysis and genetic algorithm is applied. The purpose of this paper is to define the parameters of the total and partial segmentation that can ensure the best reduction of eddy current losses. Design/methodology/approach -First, a model to analyze eddy current losses is presented. Second, the effectiveness of full and partial magnet circumferential segmentation to reduce eddy loss is studied for a range of frequencies from few Hz to a dozen of kHz. To achieve these purposes a 2-D finite element model is developed under MATLAB environment. In a third step of the work, an optimization process is applied to adjust the segmentation design parameters for best reduction of eddy current losses in case of surface mounted permanent magnets synchronous machine. Findings -In case of the skin effect operating, both full and partial magnet segmentations can lead to eddy current losses increases. Such deviations of magnet segmentation techniques can be avoided by an appropriate choice of their design parameters. Originality/value -Few works are dedicated to investigate partial magnet segmentation for eddy current losses reduction. This paper studied the effectiveness and behaviour of partial segmentation for different frequency ranges. To avoid eventual anomalies related to the skin effect an optimization process based on the association of the finite elements analysis to genetic algorithm method is adopted.

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Section: Eddy Current Losses Analysismentioning

confidence: 99%

“…Any kind of magnetic flux density changes always induce eddy currents and the consequent power losses (Maga et al, 2010). These losses may become a problem for overheating the conductive magnets.…”

Section: Introductionmentioning

confidence: 99%

Investigation of magnet segmentation techniques for eddy current losses reduction in permanent magnets electrical machines

Belli

Mékidèche

2015

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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“…However, the parasitic eddy current losses within magnets can be a serious problem especially for high-speed permanent magnet motors. Although these losses are mostly neglected in the design step, some authors have presented analytical [1][2][3][4] and numerical approaches [5][6][7][8][9] to analyze them and show their importance. The eddy current losses in the conductive rotor magnets may become a problem for overheating.…”

Section: Introductionmentioning

confidence: 99%

Investigation of eddy current losses reduction in permanent magnets machines with slots skew optimization and demagnetization effect analysis

Belli

Mékidèche

2013

JAE

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The aim of this study is to analyze and investigate some techniques to reduce eddy current losses in permanent magnets. First, a model using Maxwell's equations to analyze eddy current in permanent magnets is presented. Second, the effect of magnet circumferential segmentation on the eddy current losses in case of a surface mounted permanent magnets synchronous machine is investigated. A simple analysis of magnet demagnetization due to its eddy current losses is also studied. In a third step, second technique for reducing eddy current losses is presented. It relates to the stator slots skew, where the best skewing angle is obtained by means of an optimization process using genetic algorithm. A 2D nonlinear finite elements code is developed to achieve the purposes of the presented work.

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“…For these applications an annulus machine shape is typically imposed by the available volume, favoring the FSCW solution for its shorter endwinding connections. However, the main drawback of the FSCW layout is the relevant rotor losses due to the high spatial harmonic content of the rotating stator Magneto Motive Force (MMF), and large slot openings [4]. In particular, each MMF harmonic component which is not synchronous with the rotor induces eddy-currents circulating in the rotor material, contributing to the overall rotor losses [5]- [10].…”

Section: Introductionmentioning

confidence: 99%

Impact of the rotor back-iron resistivity on the rotor eddy-current losses in fractional-slot concentrated windings PM machines

Cavagnino

Lazzari

Miotto

et al. 2011

2011 IEEE Energy Conversion Congress and Exposition

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It is well known that in fractional-slot concentrated windings the eddy-current losses in the permanent magnets can be relevant and, for this reason, they must be evaluated in the machine design procedure. The paper investigates the influence of the rotor back-iron resistivity on the rotor eddy-current losses in this machine typology. In particular, a external rotor annulus shape PM machine with fractional-slot non-overlapping concentrated windings is considered. The machine is a scaled representative prototype of starters/generators embedded in aircraft engines. Both the rotor back-iron and permanent magnet eddy-currents are simultaneously considered by means of bidimensional transient FEM simulations, including effects of stator slotting, rotor motion and material saturation. The analysis is conducted increasing the rotor back-iron resistivity from an ideal situation of a high-conducting material up to the opposite ideal condition of a non-conducting material. Adjusting the rotor backiron resistivity, the space MMF harmonic components influence on the machine torque is qualitatively investigated and discussed too.

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Additional losses in permanent magnet brushless machines

Cited by 39 publications

References 2 publications

Investigation of magnet segmentation techniques for eddy current losses reduction in permanent magnets electrical machines

Investigation of magnet segmentation techniques for eddy current losses reduction in permanent magnets electrical machines

Investigation of eddy current losses reduction in permanent magnets machines with slots skew optimization and demagnetization effect analysis

Impact of the rotor back-iron resistivity on the rotor eddy-current losses in fractional-slot concentrated windings PM machines

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