Calculation improvement of 3D linear magnetostatic field based on fictitious magnetic surface charge

2009

PIER

Abstract-This paper presents a three-dimensional analytical expressions for studying the static magnetic field produced by Magnetic Resonance Imaging structures. This medical imaging technique uses a very high and uniform magnetic field produced by ring permanent magnets with rotating polarizations. However, the manufacturing of such ring permanent magnets is difficult to realize. Consequently, such ring permanent magnets are replaced by assemblies of tile permanent magnets uniformly magnetized. Unfortunately, the magnetic field produced by these tile permanent magnets uniformly magnetized is both less important and less uniform than the one produced by an idealized ring permanent magnet. We propose in this paper to study the influence of the number of tile permanent magnets used on the magnetic field properties.

Section: Introductionmentioning

confidence: 99%

Magnetic Field in Mri Yokeless Devices: Analytical Approach

Ravaud¹,

2009

PIER

“…Many authors have studied the field created by ring [1][2][3][4][5][6][7], cylinder [8][9][10], tile permanent magnets [11][12][13] or by disk conductors [14][15][16]. All these analytical methods have enabled authors to study the stiffness or the force between permanent magnets for magnetic bearings [17,18] or couplings [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Modelling an Ironless Loudspeaker by Using Three-Dimensional Analytical Approaches

Ravaud¹,

2009

PIER

Abstract-This paper presents some improved three-dimensional expressions of the magnetic field created by tile permanent magnets uniformly and radially magnetized for the design of ironless loudspeaker structures. All the expressions determined have been reduced to compact forms.We use these expressions for the optimization of ironless loudspeaker structures in which the radial field must be radially uniform. Indeed, as ring permanent magnets radially magnetized are rather difficult to manufacture, these magnets are replaced by assemblies of tile permanent magnets radially and uniformly magnetized. We present an example of ironless loudspeaker structure that has been optimized with our threedimensional approaches.

“…Besides, this wall can be either a plane or a cylinder and so the airgap type determines two couplings families. Moreover, the study of magnetic couplings relies on the analytical expressions of the magnetic field created by permanent magnets of various shapes [12][13][14][15][16], and especially parallelepipeds [17,18], tiles [19][20][21][22], rings [23,24] and cylinders [25,26]. The first analytical formulations for the forces between cuboidal magnets was given by Akoun and Yonnet [27].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Couplings With Cylindrical and Plane Air Gaps: Influence of the Magnet Polarization Direction.

Ravaud¹,

2009

PIER B

Abstract-This paper presents a comparison of cylindrical and plane air gap magnetic couplings in which the tile permanent magnet polarizations can be either radial or tangential or axial.The expressions of the torque transmitted between the two rotors of each coupling are determined by using the colombian approach. All the calculations are performed without any simplifying assumptions. Consequently, the expressions obtained are accurate and enable a fast comparison between the structures presented in this paper.