A study on irreversible permanent magnet demagnetization in flux-reversal machines

Shin, Heung-Kyo; Kim, Tae Heoung; Kim, Cherl-Jin

doi:10.1109/icems.2011.6073679

Cited by 8 publications

(8 citation statements)

References 4 publications

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“…Many studies have recently been published on the dem agnetization risks of permanent magnets in different types of machines [4][5][6][7][8][9][10]. In [4][5][6][7][8], the behavior of the magnet material is represented by an idealized BH curve, meaning that the magnetic field density of the magnet is considered to decrease linearly with an increasing opposing external magnetic field, until a certain knee point is reached. If the opposing field exceeds the knee point, some irreversible losses will occur.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Behavior of Sintered NdFeB Magnets on a Long-Term Timescale

Haavisto¹,

Tuominen

Santa-Nokki³

et al. 2014

Advances in Materials Science and Engineering

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Stable polarization of permanent magnets over the lifetime of the application is an important aspect in electrical machine design. Specification of the long-term stability of magnet material is difficult, since knowledge of the phenomenon is incomplete. To be able to optimize magnet material selection, the long-term magnetic behavior of the material must also be understood. This study shows that material with a very squareJHcurve is stable until a certain critical operating temperature is reached. Major losses are detected as the critical temperature is exceeded. Material with a rounderJHcurve does not show a well-defined critical temperature, but increasing losses over a large temperature range. The critical temperature of a material is also dependent on the field conditions. Results differ whether the tests are performed in an open or closed magnetic circuit. In open-circuit tests, the opposing field is not homogeneously distributed throughout the volume of the magnet and thus the long-term behavior is different than that in closed-circuit conditions. Open-circuit tests seem to give bigger losses than closed-circuit tests in cases where the permeance coefficient of the open-circuit sample is considered to be the average permeance coefficient, calculated according to the dimensions of the magnet.

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Section: Introductionmentioning

confidence: 99%

Magnetic Behavior of Sintered NdFeB Magnets on a Long-Term Timescale

Haavisto¹,

Tuominen

Santa-Nokki³

et al. 2014

Advances in Materials Science and Engineering

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“…(9) where B 1r and B 1 are the radial and tangential component of flux density in the air gap, A z1 is the magnetic vector potential in the air gap. (11) where is the rotor angular velocity.…”

Section: The Electromagnetic Performance Calculation and Comparison Omentioning

confidence: 99%

“…1, and the main difference is the PM poles on one stator tooth. In the traditional configuration, two PMs with opposite polarities are placed at the surface of each stator tooth, and the two PMs at the both sides of the slot opening have the same polarity [1][2][3][4][5][6][7][8][9][10][11]. As proposed in [12], there are four PMs on the stator tooth in the new configuration, and the distributed winding is also proposed to improve the power density.…”

Section: Introductionmentioning

confidence: 99%

“…The FEM can consider the effect of magnetic saturation, it is well suitable for the analysis of FRM [1][2][3][4][5][6][7][8][9][10][11]. Despite its excellent accuracy, the FEM is a time consuming method and it is not suitable for the initial design and optimal design, in which the models with different topologies and dimensions should be analyzed.…”

Section: Introductionmentioning

confidence: 99%

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The electromagnetic performance calculation and comparison of flux reversal machine with different winding topologies

Yang

Zhang

et al. 2014

2014 17th International Conference on Electrical Machines and Systems (ICEMS)

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In this paper, the analytical model of flux reversal machine with four permanent magnets on one stator tooth and different winding topologies including the concentrated winding and the distributed windings are presented. The electromagnetic performance such as the flux density, flux linkage, back-EMF and the electromagnetic torque are compared. It is found that the power density of flux reversal machine with the distributed windings is greatly improved than that with the concentrated windings. At last, the conclusions are verified with the finite element methods(FEM).

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“…Dy free anisotropic bonded NdFeB PM in particular shows nonlinear property at all temperature ranges. Recently, several papers, whose subjects are the determination of the operating point in consideration of the nonlinear property of PM, have been presented [11]- [13]. The methods presented in the papers simplify B-H curve of PM by two straight lines to estimate the operating point.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of IPMSM According to Rotor Design Considering Nonlinearity of Permanent Magnet

Park¹,

Kim²,

Choi³

et al. 2016

IEEE Trans. Magn.

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As materials with various properties have been developed for the improvement of performance and lowering material cost of Permanent Magnet (PM) motors, the properties of the materials have become major factors in determining the motor performance. As such a material, the recently-developed anisotropic bonded NdFeB PM showed a nonlinear demagnetization curve. Thus in this paper, by considering the nonlinear property of the PM, a process to calculate the operating point, coupled with a nonlinear analysis of the core, is proposed, and by applying this process, the characteristics of Interior Permanent Magnet Synchronous Motor according to different rotor designs are investigated.Index Terms-Demagnetization, finite element analysis, nonlinear magnetics, operating point, permanent magnet motors.

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A study on irreversible permanent magnet demagnetization in flux-reversal machines

Cited by 8 publications

References 4 publications

Magnetic Behavior of Sintered NdFeB Magnets on a Long-Term Timescale

Magnetic Behavior of Sintered NdFeB Magnets on a Long-Term Timescale

The electromagnetic performance calculation and comparison of flux reversal machine with different winding topologies

Characteristics of IPMSM According to Rotor Design Considering Nonlinearity of Permanent Magnet

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