Compensation of anisotropy effects in flux-confining permanent-magnet structures

Marinescu, M.; Marinescu, N.

doi:10.1109/20.42470

Cited by 15 publications

(13 citation statements)

References 1 publication

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“…This difference is consistent with the assumptions taken for determining (3). We also see that the accuracy of the magnetic field expression with (3) remains questionable when the distance between the observation point and the inner face of the magnet equals three times the x-length of the magnet (we incur an error of at least 4 per cent in this case).…”

Section: Accuracy Of the Dipole Moment Representation In The Near-fieldsupporting

confidence: 64%

“…3. We note H exact x , the exact expression of this component and H dipole x its simplifying analytical expression that is determined by (3). By using the notations shown in Fig.…”

Section: Accuracy Of the Dipole Moment Representation In The Near-fieldmentioning

confidence: 99%

“…In addition, their coercive field and magnetic polarization allow one to use them in Halbach structures [1,2]. As a consequence, some judicious assemblies of magnets have been studied in order to create either intense magnetic fields in the air gap or to optimize the radial field shape in electrical machines [3][4][5]. More generally, we can say that such structures allow us to obtain intense magnetic fields that are required for creating great torques in magnetic couplings.…”

Section: Introductionmentioning

confidence: 99%

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Discussion About the Magnetic Field Produced by Cylindrical Halbach Structures

Ravaud¹,

Lemarquand²

2009

PIER B

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Abstract-This paper uses a three-dimensional analytical approach based on the Coulombian model for studying the magnetic field produced by cylindrical Halbach structures.Such structures, commonly used in magnetic couplings or in electrical machines, are composed of tile permanent magnets with rotating magnetizations. Such assemblies of tile permanent magnets allow one to easily optimize the radial field shape in the air gap of electrical machines. In addition, Halbach structures can be used in magnetic couplings for improving the torque transmitted between the two rotors. Analytical studies dealing with the optimization of such structures generally use a twodimensional analytical approach for calculating either the magnetic field produced by tile permanent magnets or the forces exerted between them. These two-dimensional expressions are useful because they have a very low computational cost. However, their accuracy depends greatly on the structure dimensions. We propose in this paper to use a three-dimensional analytical model based on the Coulombian model for determining the exact shape of the magnetic field produced by a Halbach structure. Such an approach also allows one to determine the demagnetizing magnetic field inside the tile permanent magnets. This element of information is important for the design of tile permanent magnets. In addition, we show that some effects cannot be predicted with the linearized analytical model. This implies that a linearized dimensional optimization is not accurate. This study has been carried out without any simplifying assumptions. Therefore, the calculations of the three magnetic field components are exact for all points in space, whatever the magnet dimensions. We can say that such a three-dimensional analytical approach is a good alternative to a finite element one because it has a lower computational cost and is more accurate.

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Section: Accuracy Of the Dipole Moment Representation In The Near-fieldsupporting

confidence: 64%

“…3. We note H exact x , the exact expression of this component and H dipole x its simplifying analytical expression that is determined by (3). By using the notations shown in Fig.…”

Section: Accuracy Of the Dipole Moment Representation In The Near-fieldmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discussion About the Magnetic Field Produced by Cylindrical Halbach Structures

Ravaud¹,

Lemarquand²

2009

PIER B

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“…Analytical approaches were proposed by Marinescu [11] and analytical 2-D and 3-D solutions were given by Yonnet [12] and by Bancel [13] for the field created by parallelepipedic magnets. These calculations were applied to the study of devices such as loudspeaker motors with no leakage [14], [15], guitar pickups [16], magnetic couplings, and bearings [17].…”

mentioning

confidence: 99%

Analytical Calculation of the Magnetic Field Created by Permanent-Magnet Rings

et al. 2008

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We present analytical formulations, based on a coulombian approach, of the magnetic field created by permanent-magnet rings. For axially magnetized magnets, we establish the expressions for the three components. We also give the analytical 3-D formulation of the created magnetic field for radially magnetized rings. We compare the results determined by a 2-D analytical approximation to those for the 3-D analytical formulation, in order to determine the range of validity of the 2-D approximation.

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“…Ring permanent magnets axially or radially magnetized are commonly used for creating magnetic fields in magnetic bearings [3,4], in flux confining devices [5][6][7][8][9], in sensors [10][11][12], in electrical machines [13][14][15][16] and in loudspeakers [17][18][19]. The calculation of the magnetic field created by such structures can be done by using numerical methods or analytical methods.…”

Section: Introductionmentioning

confidence: 99%

Discussion About the Analytical Calculation of the Magnetic Field Created by Permanent Magnets

Ravaud¹,

Lemarquand²,

Lemarquand³

et al. 2009

PIER B

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Abstract-This paper presents an improvement of the calculation of the magnetic field components created by ring permanent magnets. The three-dimensional approach taken is based on the Coulombian Model. Moreover, the magnetic field components are calculated without using the vector potential or the scalar potential. It is noted that all the expressions given in this paper take into account the magnetic pole volume density for ring permanent magnets radially magnetized. We show that this volume density must be taken into account for calculating precisely the magnetic field components in the near-field or the far-field. Then, this paper presents the component switch theorem that can be used between infinite parallelepiped magnets whose cross-section is a square. This theorem implies that the magnetic field components created by an infinite parallelepiped magnet can be deducted from the ones created by the same parallelepiped magnet with a perpendicular magnetization. Then, we discuss the validity of this theorem for axisymmetric problems (ring permanent magnets). Indeed, axisymmetric problems dealing with ring permanent magnets are often treated with a 2D approach. The results presented in this paper clearly show that the two-dimensional studies dealing with the optimization of ring permanent magnet dimensions cannot be treated with the same precisions as 3D studies.

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Compensation of anisotropy effects in flux-confining permanent-magnet structures

Cited by 15 publications

References 1 publication

Discussion About the Magnetic Field Produced by Cylindrical Halbach Structures

Discussion About the Magnetic Field Produced by Cylindrical Halbach Structures

Analytical Calculation of the Magnetic Field Created by Permanent-Magnet Rings

Discussion About the Analytical Calculation of the Magnetic Field Created by Permanent Magnets

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