Topic
Magnetic core
About: Magnetic core is a research topic. Over the lifetime, 30011 publications have been published within this topic receiving 155247 citations.
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Book•
30 Sep 1996
TL;DR: In this article, the authors present a method for approximating the time-harmonic Maxwell Equations in anisotropic Inhomogeneous Media. But the method is not suitable for the design of electrical devices.
Abstract: Glossary of Symbols. Foreword. 1. Introduction. 2. Mathematical Modelling of Physical Phenomena. 3. Mathematical Background. 4. Finite Elements. 5. Conjugate Gradients. 6. Magnetic Potential of Transformer Window. 7. Calculation of Nonlinear Stationary Magnetic Fields. 8. Steady-State Radiation Heat Transfer Problem. 9. Nonlinear Anisotropic Heat Conduction in a Transformer Magnetic Core. 10. Stationary Semiconductor Equations. 11. Nonstationary Heat Conduction in a Stator. 12. The Time-Harmonic Maxwell Equations. 13. Approximation of the Maxwell Equations in Anisotropic Inhomogeneous Media. 14. Methods for Optimal Shape Design of Electrical Devices. References. Author index. Subject index.
65 citations
Patent•
15 Apr 1998
TL;DR: In this article, the stator magnetic poles have a straight shape having a width which is made constant over a whole length, small grooves are formed in each of the stators magnetic poles in symmetrical positions on opposite sides and near a top end portion of a stator magnet, a bottom portion of each slot portion defined by adjacent ones of the magnet poles and the yoke is formed triangularly.
Abstract: A permanent-magnet electric rotating machine with a concentrated winding stator, including a stator having a plurality of stator magnetic poles formed so as to extend radially from an annular yoke portion of a stator iron core, and windings mounted on the stator magnetic poles; and a rotor having a permanent magnet with a plurality of magnetic poles and rotatably held so as to face the stator through an air gap; wherein each of the stator magnetic poles has a straight shape having a width which is made constant over a whole length, small grooves are formed in each of the stator magnetic poles in symmetrical positions on opposite sides and near a top end portion of the stator magnetic pole, a bottom portion of each slot portion defined by adjacent ones of the stator magnetic poles and the yoke is formed triangularly, each of the stator winding is constituted so that a winding having a predetermined number of turns and winding being formed so as to be fittable to each of the stator magnetic poles is mounted on the stator magnetic pole through an insulator, and wedges are fitted to the small grooves formed in the stator magnetic poles.
65 citations
TL;DR: The results suggest that magnetic relaxation is a significant and unsolved barrier to achieving the high spatial resolutions predicted by the Langevin model for large core size SPIOs.
Abstract: Magnetic particle imaging (MPI) is a promising new tracer modality with zero attenuation in tissue, high contrast and sensitivity, and an excellent safety profile. However, the spatial resolution of MPI is currently around 1 mm in small animal scanners. Especially considering tradeoffs when scaling up MPI scanning systems to human size, this resolution needs to be improved for clinical applications such as angiography and brain perfusion. One method to improve spatial resolution is to increase the magnetic core size of the superparamagnetic nanoparticle tracers. The Langevin model of superparamagnetism predicts a cubic improvement of spatial resolution with magnetic core diameter. However, prior work has shown that the finite temporal response, or magnetic relaxation, of the tracer increases with magnetic core diameter and eventually leads to blurring in the MPI image. Here we perform the first wide ranging study of 5 core sizes between 18 and 32 nm with experimental quantification of the spatial resolution of each. Our results show that increasing magnetic relaxation with core size eventually opposes the expected Langevin behavior, causing spatial resolution to stop improving after 25 nm. Different MPI excitation strategies were experimentally investigated to mitigate the effect of magnetic relaxation. The results show that magnetic relaxation could not be fully mitigated for the larger core sizes and the cubic resolution improvement predicted by the Langevin was not achieved. This suggests that magnetic relaxation is a significant and unsolved barrier to achieving the high spatial resolutions predicted by the Langevin model for large core size superparamagnetic iron oxides.
65 citations
TL;DR: In this article, the PFM of two Ag-containing Gd-Ba-Cu-O samples is carried out using two types of magnetizing coils: (1) a solenoid coil and (2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field.
Abstract: Investigating and predicting the magnetization of bulk superconducting materials and developing practical magnetizing techniques is crucial to using them as trapped field magnets in engineering applications. The pulsed field magnetization (PFM) technique is considered to be a compact, mobile and relative inexpensive way to magnetize bulk samples, requiring shorter magnetization times (on the order of milliseconds) and a smaller and less complicated magnetization fixture; however, the trapped field produced by PFM is generally much smaller than that of slower zero field cooling or field cooling techniques, particularly at lower operating temperatures. In this paper, the PFM of two, standard Ag-containing Gd–Ba–Cu–O samples is carried out using two types of magnetizing coils: (1) a solenoid coil, and (2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field. It is shown that a significantly higher trapped field can be achieved using a split coil with an iron yoke, and in order to explain these how this arrangement works in detail, numerical simulations using a 2D axisymmetric finite element method based on the H -formulation are carried to qualitatively reproduce and analyze the magnetization process from both electromagnetic and thermal points of view. It is observed that after the pulse peak significantly less flux exits the bulk when the iron core is present, resulting in a higher peak trapped field, as well as more overall trapped flux, after the magnetization process is complete. The results have important implications for practical applications of bulk superconductors as such a split coil arrangement with an iron yoke could be incorporated into the design of a portable, high magnetic field source/magnet to enhance the available magnetic field or in an axial gap-type bulk superconducting electric machine, where iron can be incorporated into the stator windings to (1) improve the trapped field from the magnetization process, and (2) increase the effective air-gap magnetic field.
65 citations
TL;DR: A new integrated magnetic full wave DC/DC power converter that provides flexible transformer design by incorporating an independent output inductor winding is introduced, implemented on a traditional three-leg magnetic core.
Abstract: A new integrated magnetic full wave DC/DC power converter that provides flexible transformer design by incorporating an independent output inductor winding is introduced. The transformer is implemented on a traditional three-leg magnetic core. The inductor winding can be separately designed to control the output current ripple. The cross-sectional area of the inductor core leg can be reduced dramatically. The operation and performance of the proposed circuit are verified on a 100 W prototype converter.
64 citations