Magnetic core

About: Magnetic core is a research topic. Over the lifetime, 30011 publications have been published within this topic receiving 155247 citations.

Analysis of irreversible magnet demagnetization in line-start motors based on the finite-element method

Abstract: This paper deals with the analysis for the irreversible demagnetization characteristics of a ferrite-type permanent magnet in the line-start motor using the two-dimensional finite-element method (2-D FEM). The demagnetizing currents are calculated from the transient analysis in the combination voltage equation with mechanical dynamic equation, and peak currents are applied to the irreversible demagnetization analysis computed by 2-D FEM. The nonlinear characteristic of the magnetic core is considered as well as that of a permanent magnet on the B-H curve in the analysis of irreversible demagnetization.

Power transfer apparatus

Abstract: A power transfer apparatus includes: a magnetic resonance coil for transferring magnetic energy by magnetically resonating with an external coil; a power receiving unit for picking up, as electrical power, the magnetic energy that the magnetic resonance coil receives from the external coil; and a magnetic body arranged on a side of the magnetic resonance coil opposite a transfer side of the magnetic energy of the magnetic resonance coil.

Inductive write head having high magnetic moment poles and low magnetic moment thin layer in the back gap, and methods for making

Abstract: The present invention provides a write element for use in magnetic data recording system such as a computer disk drive. The write head utilizes the advantageous properties of high magnetic moments while overcoming the corrosion problems engendered by such materials. The write element includes a magnetic yoke constructed of first and second magnetic poles joined to one another at a back gap. While the majority of the poles are constructed of a high magnetic moment material a layer of relatively low magnetic moment material is provided on the first pole at the back gap portion of the first pole. The relatively low magnetic moment material prevents corrosion of the first pole during subsequent manufacturing of the write head. An electrically conductive coil passes through the magnetic yoke and is insulated there from. By passing an electrical current through the electrical coil, a magnetic flux is generated in the yoke. This magnetic flux then generates a magnetic fringing field in at a write gap of the yoke. The fringing field imparts magnetic data onto a recording medium passing thereby.

Composite magnetic core for switch-mode power converters

Abstract: A composite magnetic core formed of a high permeability material and a lower permeability, high saturation flux density material prevents core saturation without an air gap and reduces eddy current losses and loss of inductance. The composite core is configured such that the low permeability, high saturation material is located where the flux accumulates from the high permeability sections. The presence of magnetic material having a relatively high permeability keeps the flux confined within the core thereby preventing fringing flux from spilling out into the winding arrangement. This composite core configuration balances the requirements of preventing core saturation and minimizing eddy current losses without increasing either the height or width of the core or the number of windings.

Magnetic attachment device for insertion and removal of hearing aid

Abstract: A direct contact hearing aid apparatus adapted to be mounted deep within the ear canal is disclosed, including an output electromechanical transducer for converting audio output signals into mechanical movement of an output coupling element without the production of discernible sound waves to prevent acoustic feedback. The coupling element is supported for magnetic engagement with a contact element mounted on the tympanic membrane by a metal clip attached to the malleus bone to provide direct electromechanical coupling to the ossicles through the tympanic membrane. Alternatively, the contact element may be attached to the malleus bone by a clamp whose jaws are lined with bioactive ceramic. A pair of magnetic switches is provided within the hearing aid housing for mechanically switching the connections of the battery and a volume control while the hearing aid is mounted in the ear canal in response to changes in the polarity of a remote external magnetic actuator located outside of the housing. An external magnetic attachment device is used for insertion and removal of the hearing aid, radio or other electronic apparatus into and from the ear canal by magnetic engagement with a magnetic holder member on the electronic apparatus. The magnetic attachment device may be unipolar or bipolar and has a permanent magnet which is rotated between an attraction position and a release position by a selection knob. The output transducer of the hearing aid may be a piezoelectric plastic film transducer in the form of a flexible diaphragm or a folded sheet bender of the bimorph type, or it may be an electromagnetic transducer. The electromagnetic transducer may have an external magnetic coupling element mounted outside the hearing aid housing and spaced from the magnetic core of such transducer but coupled to the contact element. Also, a reverse bias permanent magnet may be provided at the end of such core to repel a movable permanent magnet which is mounted on a resilient coupling member to form the external magnetic coupling element.