Showing papers on "Magnetic core published in 2003"

Synthesis and magnetic characterization of Mn and Co spinel ferrite-silica nanoparticles with tunable magnetic core

Abstract: A method for coating silica on CoFe2O4 and MnFe2O4 spinel ferrite nanoparticles has been developed by using a reverse micelle microemulsion approach. The ability to controllably synthesize magnetic nanoparticulate cores independent of encapsulation provides great flexibility in tuning the magnetic properties of this magnetic nanocomposite system by controlling the magnetic properties of nanoparticulate cores. For these spinel ferrite nanoparticles, the saturation and remnant magnetizations decrease upon silica coating. The coercivity of silica-coated CoFe2O4 nanoparticles does not show any change after coating, while the coercivity of MnFe2O4 nanoparticles decreases by 10% after they have been coated with silica.

High current inductive coupler and current transformer for power lines

Abstract: There is provided an inductive power line data coupler (10). The coupler (10) includes (a) a magnetic core (105) having a high magnetic permeability at a data communication frequency and being configured to allow a power line (100) to serve as a primary winding, (b) a data signaling circuit that provides a secondary winding (115) through the magnetic core (105) for coupling a data signal between the power line (100) and a communication device (130), and (c) a choke coil (135) coupled to the data signaling circuit for creating a flux-canceling power frequency current opposite in direction and comparable in magnitude to a power frequency current. The coupler (10) may also include a circuit for sensing a level of current in the power line (100).

Improvements relating to the transfer of electromagnetic power

Abstract: There is disclosed a magnetic core component for receiving electrical power by induction. The core component includes a thin sheet of amorphous magnetic material in a substantially amorphous or non-annealed state. In contrast to known core components, which use annealed amorphous magnetic materials, the non-annealed material of the present invention is flexible and non-brittle. This means that it has significant advantages including resistance to physical shocks. This is of importance when the core component is used in portable electronic devices such as mobile telephones and the like which may be subject to physical shocks, for example by being accidentally dropped.

Integrated circuit inductor with a magnetic core

Abstract: An inductor is fabricated on a substrate having a top surface and a bottom surface. The inductor includes a plurality of holes extending through the substrate, wherein the plurality of holes interconnect the top surface and the bottom surface of the substrate. The inductor also includes a plurality of conductive posts formed in the plurality of holes and a plurality of conductive segments formed on the top surface and on the bottom surface that interconnect the conductive posts such that a continuous conductive coil is formed. The inductor also includes a magnetic core that occupies substantially the entire volume enclosed by the conductive coil.

Integrated current sensor

Abstract: An integrated current sensor includes a magnetic field transducer such as a Hall effect sensor, a magnetic core, and an electrical conductor The conductor includes features for receiving portions of the Hall effect sensor and the core and the elements are dimensioned such that little or no relative movement among the elements is possible

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.

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.

Magnetic integration for interleaved converters

Abstract: In this paper several techniques for integration of magnetic components in interleaved converters are analyzed Magnetic components define the way the energy is transformed Several opposite approaches can be considered: from decoupled integrated inductors to tightly coupled inductors The integration of inductors in the same core for multiphase converters is especially analyzed from the point of view of size, losses and coupling

Design of large air-gap transformers for wireless power supplies

Abstract: This paper addresses the design of two-dimensional large air gap transformers for wireless power transmission. A theoretical analysis of the optimum shape and arrangement of the primary coils is presented. The magnetic field created by such a system is discussed and optimised. The effects of shielding of the secondary coils are discussed. The optimum coil arrangement for one example design is derived.

Bulk amorphous metal inductive device

Abstract: A bulk amorphous metal inductive device comprises a magnetic core having plurality of low-loss bulk ferromagnetic amorphous metal magnetic components assembled in juxtaposed relationship to form at least one magnetic circuit and secured in position, e.g. by banding or potting. The device has one or more electrical windings and may be used as a transformer or inductor in an electronic circuit. Each component comprises a plurality of similarly shaped layers of amorphous metal strips bonded together to form a polyhedrally shaped part. The low core losses of the device, e.g. a loss of at most about 12 W/kg when excited at a frequency of 5 kHz to a peak induction level of 0.3 T, make it especially useful for application in power conditioning circuits operating in switched mode at frequencies of 1 kHz or more. Air gaps are optionally interposed between the mating faces of the constituent components of the device to enhance its energy storage capacity for inductor applications. The inductive device is easily customized for specialized magnetic applications, e.g. for use as a transformer or inductor in power conditioning electronic circuitry employing switch-mode circuit topologies and switching frequencies ranging from 1 kHz to 200 kHz or more.

Ultralow-profile micromachined power inductors with highly laminated Ni/Fe cores: application to low-megahertz DC-DC converters

Abstract: Micromachined inductors with submillimeter profiles and comparable electrical performance to thicker, commercially-available surface-mount devices, have been fabricated and characterized for low-megahertz dc-dc converters. The fabrication approach involves micron-scale lamination of Ni/Fe cores, combined with three-dimensional micromachined copper windings. The magnetic core of the fabricated inductor has 72 laminations of 1-/spl mu/m-thick Ni/Fe films. The inductor dimension is 11.5 /spl times/ 5.7 /spl times/ 0.7 mm, and the dc resistance is 150 m/spl Omega/. A maximum Q of 9.2 at 3 MHz with an inductance value of 2.3 /spl mu/H and a dc saturation current (I80) of 0.2 A were obtained. Use of this inductor in a regulated dc-dc boost converter circuit (7-12 V) operating at 2.2 MHz yielded 1.9-W power output at 71% efficiency.

Plasma Response Models for Current, Shape and Position Control in Jet

Abstract: This paper presents the features and the performance of the Joint European Torus (JET) plasma response models based on an upgraded version of the CREATE-L code. It takes into account a number of aspects, including an equivalent axisymmetric model of the iron core and the eddy currents induced in the passive structures. The input quantities are the poloidal field circuit currents (or voltages) and two parameters related to the plasma current density profile. The output quantities include the signals provided by the magnetic diagnostic system of JET (fields, fluxes and flux differences) as well as plasma current and shape. The equivalent axisymmetric model of JET and the plasma response models have been assessed on a set of JET pulses, by comparing the simulated open loop response of the magnetic measurements and the plasma shape to the experimental measurements. The electromagnetic analysis shows that the axisymmetric model of the iron is satisfactory. The linearized plasma response model provides a reliable base for the design and the assessment of a new current, shape and position control system in JET, and accurately predicts the growth rate of the vertical instability of an elongated JET plasma.

Thin-film inductor for gigahertz band with CoFeSiO-SiO/sub 2/ multilayer granular films and its application for power amplifier module

Abstract: The thin-film power amplifier module for wide-band code division multiple access was designed and fabricated using the magnetic thin film as magnetic core of choke inductors. CoFeSiO-SiO/sub 2/ multilayer granular films showing high resistivity and good magnetic properties were applied to the module. Inductance value increased about 30% by application of magnetic films, and occupation area and series resistance were also reduced by 20%. The obtained module size was 3.0 mm /spl times/ 3.5 mm, which was much smaller than the conventional power amplifier module, since the bias circuit was formed on the same silicon substrate.

Effect of radio-frequency noise suppression on the coplanar transmission line using soft magnetic thin films

Abstract: We demonstrated the radio-frequency (rf) noise suppressor using soft magnetic films on a coplanar transmission line from 0.1 to 20 GHz. The coplanar transmission line is composed of magnetic film/polyimide/Cu transmission line/seed layer (Cu/Ti)/glass substrate with the dimension of 50 μm width of the signal line and 3 μm thickness (characteristic impedance: 50 Ω). The magnetic films (CoPdAlO, CoZrO, and CoNbZr) as a noise suppressor are prepared by rf sputtering. The saturation magnetization of each magnetic film is about 10 kG. The magnetic anisotropy field and the ferromagnetic resonance frequency are 230, 89, and 6 Oe and 4.2, 2.5, and 0.7 GHz, respectively. The power loss of the coplanar line with magnetic films is significantly larger than without magnetic and nonmagnetic films due to ferromagnetic resonance losses.

Integrated magnetic full wave converter with flexible output inductor

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.

Low-frequency magnetic fields from electrical appliances and power lines

Abstract: The relationship between magnetic fields and the health of people is increasingly being investigated. International organizations have proposed bylaws that put limits on the value of the generated magnetic field. In this work, we measure the magnetic field created by electrical appliances and high voltage lines and we analyze the degree of compliance with recent applicable European regulation. The simulation of the magnetic field generated by electrical lines through a simple model accurately predicts the measured values. The model is used to simulate the behavior of the lines under given conditions. In both cases, an FFT analysis of the magnetic field waveform was performed to study the frequency and amplitude of the possible induced currents.

Low-loss magnetic powder core, and switching power supply, active filter, filter, and amplifying device using the same

Abstract: A magnetic powder core comprises a molded article of a mixture of a glassy alloy powder and an insulating material. The glassy alloy comprises Fe and at least one element selected from Al, P, C, Si, and B, and has a texture primarily composed of an amorphous phase. The glassy alloy exhibits a temperature difference ΔTx, which is represented by the equation ΔTx=Tx−Tg, of at least 20 K in a supercooled liquid, wherein Tx indicates the crystallization temperature and Tg indicates the glass transition temperature. The magnetic core precursor is produced mixing the glassy alloy powder with the insulating material, compacting the mixture to form a magnetic core precursor, and annealing the magnetic core precursor at a temperature in the range between (Tg−170) K and Tg K to relieve the internal stress of the magnetic core precursor. The glassy alloy exhibits low coercive force and low core loss.

Magnetic field sensor and method for operating the magnetic field sensor

Abstract: A magnetic field sensor for the measurement of at least one component of a magnetic field comprises a ferromagnetic core that serves as a magnetic field concentrator, an excitation coil and a read-out sensor The read-out sensor preferably comprises two sensors arranged in the vicinity of the outer edge of the ferromagnetic core and measures the at least one component of the magnetic field The ferromagnetic core is ring-shaped or disc-shaped On operation of the magnetic field sensor, a current is temporarily applied to the excitation coil in order to bring the ferromagnetic core into a state of predetermined magnetization in which the magnetization of the ferromagnetic core produces no signal in the read-out sensor

Antenna coil and communication equipment

Abstract: PROBLEM TO BE SOLVED: To provide an antenna coil capable of more improving a communication range. SOLUTION: A sealing part 17 covers an antenna substrate 11 and a magnetic core member 12 while the flat plate-shaped magnetic core member 12 is laminated in parallel with the antenna substrate 11 with an air core coil formed therein. The magnetic core member 12 is made of sintered ferrite. In this configuration, the antenna coil 10 excellent in a communication characteristic in a high frequency band can be obtained, and the sintered ferrite apt to be broken and insufficient in handleability can easily applied as the magnetic core member 12. COPYRIGHT: (C)2005,JPO&NCIPI

Printed microinductors on flexible substrates for power applications

Abstract: A low-profile microinductor was fabricated on a copper-clad polyimide substrate where the current carrying coils were patterned from the existing metallization layer and the magnetic core was printed using a magnetic ceramic-polymer composite material. Highly loaded ferrite-polymer composite materials were formulated, yielding adherent films with 4/spl pi/M/sub s//spl ap/3900 G at +5000 Oe applied DC field. These composite magnetic films combine many of the superior properties of high temperature ceramic magnetic materials with the inherent processibility of polymer thick films. Processing temperatures for the printed films were between 100/spl deg/C and 130/spl deg/C, facilitating integration with a wide range of substrates and components. The quality factor of the microinductor was found to peak at Q=18.5 near 10 MHz, within the optimal frequency range for power applications. A flat, nearly frequency independent inductance of 1.33 /spl mu/H was measured throughout this frequency range for a 5 mm/spl times/5 mm component, with a DC resistance of 2.6 /spl Omega/ and a resonant frequency of 124 MHz. The combination of printed ceramic composites with organic/polymer substrates enables new methods for embedding passive components and ultimately the integration of high Q inductors with standard integrated circuits for low profile power electronics.

Bulk laminated amorphous metal inductive device

Abstract: A bulk amorphous metal inductive device (1) comprises a magnetic core having at least low-loss bulk ferromagnetic amorphous metal magnetic components (2, 3) forming a magnetic circuit having an air gap therein. The device has one or more electrical windings (25, 27) and may be used as a transformer or inductor in an electronic circuit. The component (2, 3) comprises a plurality of similarly shaped layers of amorphous metal strips bonded together (102) to form a polyhedrally shaped part. The low core losses of the device. e.g. a loss of at most about 12 W/kg when excited at a frequency of 5 kHz to a peak induction level of 0.3 T, make it especially useful for application in power conditioning circuits operating in switched mode at frequencies of 1 kHz or more. The component is fabricated by a process comprising cutting, stacking, registering, and bonding the laminations together by an adhesive agent.

Power supply packaging system

Abstract: A packaging system for a high current, low voltage power supply. The power supply uses bare die power FETs which are directly mounted to a thermally conductive substrate by a solder attachment made to the drain electrode metallization on the back side of the FETs. The source electrode and gate electrode of each FET are coupled to the circuitry on an overhanging printed circuit board, using CSP solder balls affixed to the front side of the FET die. The heat generated by the FETs is effectively dissipated by the close coupling of the FETs to the thermally conductive underlying substrate. High interconnect densities are achieved through the use of a multilayer printed circuit board. This high interconnect density, with the addition of a magnetic core element, allows the power supply packaging system to incorporate transformer windings for an isolation transformer or an inductor.

Microconverter and laminated magnetic-core inductor

Abstract: A surface-mount microconverter is formed by mounting a microinductor chip and a semiconductor integrated circuit chip on a circuit board. Stud terminals are arranged on the circuit board and the microinductor chip is supported on the stud terminals, and the microinductor chip and the semiconductor integrated circuit chip are superposed on the circuit board. The microconverter has an improved ability and is small and thin. The microconverter includes an effective laminated magnetic-core inductor. The inductor comprises a helical coil formed by uniting alternately superposed insulating magnetic layers and conductive pattern layers, and an annular closed magnetic path formed by the insulating magnetic layers and defining a magnetic field created by the coil. The inductor can be miniaturized in a thin chip, and a wide range in which magnetic flux density varies linearly can be secured by balancing a closed magnetic path for a magnetic field created by the coil.

Single layer iron powder core inductor model and its effect on boost PFC EMI noise

Abstract: In this paper, the single layer iron powder inductor's general math model is studied and the model equations are derived. The simulations and measurements are processed to verify the model. The relations of the boost inductor impedance and DM noise spectrum are addressed in detail. Some suggestions on boost inductors are given to reduce the DM noise.

Magnetic nanoparticle supports

Abstract: Coated magnetic nanoparticles and their compositions used for labeling, detecting, sorting, and isolating biological, organic and inorganic molecules, and for medical therapies, and as a platform for organic, biological and physical transformations. An oxidation approach for fabricating iron oxide nanoparticles, methods for the synthesis of magnetic compositions comprising a magnetic core associated with a functional molecule or molecular complexes, and methods for the synthesis of water-soluble magnetic particles/compositions.

Construction of medium voltage power line data couplers

Abstract: There is provided an inductive coupler (180) for coupling a data signal to a phase line (105) of a power line. The inductive coupler (180) includes a split magnetic core (100) having an aperture (120) formed by an upper magnetic core and a lower magnetic core. The aperture (120) permits the phase line (105) to pass therethrough as a primary winding, the upper magnetic core is for making electrical contact with an outer surface of the phase line (105), and the lower magnetic core makes electrical contact with the upper magnetic core.

Optimal core dimensional ratios for minimizing winding loss in high-frequency gapped-inductor windings

Abstract: Numerical techniques are used to find the inductor core dimensional ratios that minimize winding loss. It is shown that common core shapes result in significant excess losses, even if the shape of the wire winding is optimized. A design example demonstrates the practical implications of this technique for choosing cores-a standard core with dimensional ratios close to optimum provides a 32 % savings in power loss compared to another popular core shape. Further improvements in power loss could be achieved by using optimized core shapes. Improvements to software for shape-optimization of windings are described, including accounting for different turn lengths at different radii, the ability to select gaps in different core legs, and better approximations of three-dimensional field geometry.

Method of continuous casting non-oriented electrical steel strip

Abstract: Non-oriented electrical steels are widely used as the magnetic core material in a variety of electrical machinery and devices, particularly in motors where low core loss and high magnetic permeability in all directions of the strip are desired. A method for producing a non-oriented electrical steel with low core loss and high magnetic permeability provides a steel that is produced from a steel melt which is cast as a thin strip or sheet, cooled, hot rolled and/or cold rolled into a finished strip. The finished strip is further subjected to at least one annealing treatment wherein the magnetic properties are developed, making the steel strip suitable for use in electrical machinery such as motors or transformers.

Filters with inductance cancellation using printed circuit board transformers

Abstract: Capacitor parasitic inductance often limits the high-frequency performance of filters for power applications. However, these limitations can be overcome through the use of specially-coupled magnetic windings that effectively nullify the capacitor parasitic inductance. This paper explores the use of printed circuit board (PCB) transformers to realize parasitic inductance cancellation of filter capacitors. Design of such inductance cancellation transformers is explored, and applicable design rules are established and experimentally validated. The high performance of the proposed inductance cancellation technology is demonstrated in an EMI filter design.