Magnetic circuit

About: Magnetic circuit is a research topic. Over the lifetime, 15707 publications have been published within this topic receiving 118099 citations.

A disk drive in which magnetic head-to-disk capacitive coupling is eliminated

Abstract: A thin film magnetic data transducer which prevents capacitive coupling between the transducer and the disk of a disk drive system, has a magnetic circuit which is maintained at the same potential as the disk, usually ground potential. With the disk and the magnetic pole tips of the magnetic circuit at the same potential, capacitive charging and consequent current flow or arcing or discharge noise between the two are prevented. Noise from current due to the variable capacitive coupling of the coil to the disk during disk rotation is also eliminated. The thin film magnetic transducer is fabricated by depositing successive layers of an electrical insulating material, a magnetic material, insulating material, electrical conducting material for a planar coil, insulating material and magnetic material, in the order named on a substrate. The planar coil comprises spiral turns and the magnetic material layers are joined with each other within the spiral turns of the coil and encircle the coil, providing a magnetic gap between pole tips outside the of the coil. A thin film extension of the magnetic circuit is part of a circuit which connects the magnetic circuit to the frame of the disk drive as are the disks, which is usually ground potential.

A system for controllable magnetic measurements of hysteresis and Barkhausen noise

Abstract: A specially developed setup for precise measurement of the magnetic hysteresis and Barkhausen noise is presented in this work. A novelty of the setup consists in a unique combination of two main features: an accurate local determination of the magnetic field and an improved feedback control of the magnetization process. Firstly, the magnetic field is measured by two Hall sensors at different distances above the sample. Linear extrapolation of this measured profile of the tangential fields to the sample surface gives the true local values of the magnetic field. Secondly, a digital feedback loop for precise control of the ac magnetization process is proposed. The system combines two known methods of magnetizing signal adjustment: linear corrections of the magnetizing voltage amplitude and phase. The presented system is able to adjust the waveform of the magnetic induction or field to the prescribed sinusoidal or triangular shape. This provides stable and physically accurate results, which are independent of a specific experimental configuration.

A method for reduction of cogging torque in brushless DC motor considering the distribution of magnetization by 3DEMCN

Abstract: A method of reducing cogging torque and improving average torque has been studied by changing the dead zone angle of trapezoidal magnetization distribution of the ring type rotor magnet in a brushless DC motor (BLDCM). Because the BLDCM has a 3-D shape of its overhang, 3-D analysis should be used for exact computation of its magnetic field. A 3-D equivalent magnetic circuit network method (3-D EMCN) which can analyze an accurate 3-D magnetic field has been introduced. The analysis results of cogging torque using this 3-D EMCN are compared with those of the 3-D finite element method (3-D FEM) and experimental data.

Push-button operated electrical power source for an optical communication link

Abstract: In the present invention, a novel magnetic circuit maximizes the electrical power generated upon manual actuation of a push-button switch while minimizing the required weight of the magnetic materials In particular, the magnetic circuit of the power supply of the present invention includes the following magnetic materials: an unmagnetized core (comprising iron) around which a coil is wound, the coil being connected to supply power to the transmitter; a permanent magnet (comprising iron having a permanent magnetic moment) mounted on a vibrating reed, at least one pole of the permanent magnet facing at least one end of the core Actuation of the push-button switch induces oscillatory motion of the reed and of the permanent magnet An advantage of this novel magnetic circuit is that, in at least one embodiment, the oscillatory motion of the permanent magnet causes a complete flux reversal through the coil during each cycle of the mechanical oscillation of the reed, a significant advantage

Carbonyl-Iron/Epoxy Composite Magnetic Core for Planar Power Inductor Used in Package-Level Power Grid

Abstract: Our research objective is to realize the basic technology for a next generation package-level power grid (PLPG) for plural application large scale integrated circuits (LSIs). In this study, a carbonyl-iron powder (CIP)/epoxy composite magnetic core, for large-current power inductor used for the main dc-dc converter in the PLPG, has been fabricated and evaluated. 54 vol.%-CIP/epoxy composite core made by screen-printing had a relative permeability of 7.5 and loss tangent of about 0.03 at 100 MHz. The planar power inductor using composite core was fabricated and evaluated, which had a quasi closed magnetic circuit consisting of low permeability composite core and embedded 35-μm-thick, two-turn copper spiral coil. The fabricated inductor with a 1-mm-square in size had 5.5 nH inductance, Q-factor of 15 at 100 MHz, and 18 mΩ dc coil resistance. Inductance was constant even when the superimposed dc current increased up to around 5.5 A.