Showing papers on "Magnetic core published in 2006"

Ferromagnetic powder for dust core

Abstract: A particle (10) of ferromagnetic powder for use in preparation of soft magnetic core components has a core-shell structure. The particle includes a central core (12) and a shell (14) coated on the central core. The central core is made of magnetic material and is used for providing the necessary magnetic property for the magnetic core components made from the ferromagnetic powder. The shell has a higher electrical resistance than the central core so as to reduce an eddy current loss of the magnetic core component. The shell also functions to provide an excellent bonding strength between particles of the powder.

Inductively-coupled toroidal plasma source

Abstract: Apparatus for dissociating gases includes a plasma chamber comprising a gas. A first transformer having a first magnetic core surrounds a first portion of the plasma chamber and has a first primary winding. A second transformer having a second magnetic core surrounds a second portion of the plasma chamber and has a second primary winding. A first solid state AC switching power supply including one or more switching semiconductor devices is coupled to a first voltage supply and has a first output that is coupled to the first primary winding. A second solid state AC switching power supply including one or more switching semiconductor devices is coupled to a second voltage supply and has a second output that is coupled to the second primary winding. The first solid state AC switching power supply drives a first AC current in the first primary winding. The second solid state AC switching power supply drives a second AC current in the second primary winding. The first AC current and the second AC current induce a combined AC potential inside the plasma chamber that directly forms a toroidal plasma that completes a secondary circuit of the transformer and that dissociates the gas.

High-efficiency Voltage-clamped DC-DC converter with reduced reverse-recovery current and switch-Voltage stress

Abstract: This paper investigates a high-efficiency clamped-voltage dc-dc converter with reduced reverse-recovery current and switch-voltage stress. In the circuit topology, it is designed by way of the combination of inductor and transformer to increase the corresponding voltage gain. Moreover, one additional inductor provides the reverse-current path of the transformer to enhance the utility rate of magnetic core. In addition, the voltage-clamped technology is used to reduce the switch-voltage stress so that it can select the Schottky diode in the output terminal for alleviating the reverse-recovery current and decreasing the switching and conduction losses. Furthermore, the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage-drift problem of power source under the variation of loads. Thus, the proposed converter topology has a favorable voltage-clamped effect and superior conversion efficiency. Some experimental results via an example of a proton-exchange-membrane fuel cell (PEMFC) power source with a 250-W nominal rating are given to demonstrate the effectiveness of the proposed power-conversion strategy.

FEM Computation of Magnetic Field and Iron Loss in Laminated Iron Core Using Homogenization Method

Abstract: This paper presents a novel method for analyzing transient magnetic fields in laminated iron cores. It is based on the finite-element method and a newly developed homogenization method is applied to model the lamination effectively. The homogenized constitutive relations, of which the approximation is only applicable to low-frequency problems, are derived analytically, neglecting eddy currents induced by time-varying magnetic fluxes parallel to the lamination. The loss due to the neglected eddy currents is estimated in the postprocessing state utilizing the obtained magnetic field variation. The calculated magnetic field is in good agreement with the measurement for a benchmark problem. It is demonstrated that the homogenized relations can be applied to the low-frequency problems

Multiphase voltage regulator having coupled inductors with reduced winding resistance

Abstract: A multiple phase buck converter or boost converter, or buck-boost converter has an inductor in each phase. The inductors are inversely coupled. In a first embodiment, the converter includes a toroidal magnetic core with inductors extending under and over opposite sides of the toroidal magnetic core. The coupled inductors are thereby inversely coupled and have a relatively low ohmic resistance. In a second embodiment, the converter comprises a ladder-shaped magnetic core (i.e. having parallel sides, and connecting rungs). In this case, the inductors extend under the sides, and over the rungs. Each inductor is disposed over a separate rung. The ladder-shaped magnetic core is preferably disposed flat on a circuit board. Inverse coupling and low ohmic resistance are also provided in the second embodiment having the ladder structure.

Highly magnetic silica-coated iron nanoparticles prepared by the arc-discharge method

Abstract: In spite of encouraging progress in recent years, the development of magnetic nanoparticles that can be used as drug delivery vectors remains a significant challenge for materials scientists. Among the multiple hurdles that must be overcome are the provision of a sufficiently high magnetic response, a high loading capacity for therapeutic or diagnosis materials and a sufficient degree of biocompatibility. In this work we describe the preparation of encapsulated magnetic nanoparticles consisting of a metallic iron core and an amorphous silica shell by using a modification of the arc-discharge method. This is a simple and inexpensive way to produce well-coated iron nanoparticles. The particles thus obtained present a much stronger magnetic response than any composite material produced up to now involving magnetic nanoparticles encapsulated in inorganic matrices, and the rich chemistry and easy functionalization of the silica outer surface make them promising materials for their application as magnetic carriers.

Integrated On-Chip Inductors with Magnetic Films

Abstract: On-chip inductors with 2 levels of magnetic material were integrated into an advanced 130 nm CMOS process to obtain over an order of magnitude (>14times) increase in inductance and Q-factor, significantly greater than prior values of 2.3times for high frequency inductors. The magnetic material is shown to operate at frequencies beyond 6.4 GHz for 1 nH inductors. An amorphous CoZrTa alloy exhibiting high permeability, good high-temperature stability (>250degC), high saturation magnetization, low magnetostriction, high resistivity, minimal hysteretic loss, and compatible with silicon technology was used in combination with magnetic vias and elongated structures that take advantage of the uniaxial magnetic anisotropy

Finite Element Analysis of Field Distribution and Characteristic Performance of Squirrel Cage Induction Motor with Broken Bars

Abstract: This paper develops the foundations of a technique for diagnosis and characterization of effects of broken bars in squirrel-cage induction motors based on the time-stepping coupled finite-element approach. These studies are performed by using the model to compute healthy case, one-broken-bar fault, and two adjacent broken bars fault performance data, which contains stator starting current waveforms, the current density on the bars, the magnetic force distribution on the rotor bars, and the distribution of magnetic field. Meanwhile, the iron core loss distributions on the rotor tooth adjacent to broken bars are computed, and the harmonic component of air-gap flux density is analyzed. From this data, the faulty signatures are extracted. Theoretical approach together with experimental results derived from a two-pole 1.1 kW induction motor confirms the validity of the proposed method. Furthermore, this method, which could help to develop diagnostics of broken bars and performance evaluation of induction motors, has great potential in future applications

Noncontact power supply device

Abstract: PROBLEM TO BE SOLVED: To provide a noncontact power supply device capable of first improving charging efficiency, secondly expanding a gap to enhance usability and thirdly reducing a size and weight SOLUTION: This noncontact power supply device 6 is, for example, used for the battery charging of an electric automobile, and supplies electric power from a primary coil 7 at a primary and power supply side to a secondary coil 8 at a secondary and power reception side based on the mutual dielectric action of electromagnetic induction The primary coil 7 and the secondary coil 8 have structures in each of which a plurality of parallel conductors used as one set are flatly and spirally wound on the identical face and twisted at constant pitches A primary magnetic core 13 and a secondary magnetic core 14 in which the primary coil 7 and secondary coil 8 are arranged are made of ferrite etc, and formed to have flat plate shapes Surfaces of the primary coil 7 and primary magnetic core 13 and surfaces of the secondary coil 8 and the secondary magnetic core 14 are covered with mold resin 17 and fixed, respectively A foamed material 18 is mixed in the mold resin 17 COPYRIGHT: (C)2008,JPO&INPIT

Magnetic core for medical procedures

Abstract: The inventive technique include a system, method and device for treating a patient. The inventive system includes a magnetic field generating device created using a powdered ferromagnetic. The system further includes a circuit in electrical communication with the magnetic core, and a power source in electrical communication with the circuit. The ferromagnetic powder core may be manufactured by at least one of the following: machining, pressing, molding, gluing, and extruding. Also, the ferromagnetic powder core may have a distributed gap structure, where the gap structure operates to focus the magnetic field between pole faces of the magnetic device.

Magnetic circuit for a controllable reactor

Abstract: Reactive power compensation is vital for obtaining efficient operation of long transmission power lines or cables. A controllable shunt reactor that controls the transmission of power by continuous reactive power compensation will reduce the transmission losses and increase the transmission capacity of active power. We show that the saturation phenomena of iron and the high current density of a high-temperature superconductor can be utilized to design controllable reactors with large dynamic range, low losses, and limited harmonic distortion. We have designed and constructed a small-scale prototype of a controllable shunt reactor with a high-temperature superconductor control winding. We present a simple model of the magnetic circuit of the controllable reactor and we compare calculations from the model to experimental measurements on the controllable reactor

Inductively-driven plasma light source

Abstract: An electromagnetic radiation source includes a toroidal chamber that contains an ionizable medium. The electromagnetic radiation source also includes a magnetic core that surrounds a portion of the toroidal chamber. The electromagnetic radiation source also includes a pulse power system for providing pulses of energy to the magnetic core for delivering power to a plasma formed in the toroidal chamber to produce electromagnetic radiation that radiates radially through walls of the toroidal chamber.

A Novel Inductor Loss Calculation Method on Power Converters Based on Dynamic Minor Loop

Abstract: This paper proposes a novel iron loss calculation method based on the loss-map of the magnetic materials. The distinctive feature of this method is that the iron loss on the inductors in many kinds of converters can easily be calculated even if the magnetizing conditions of the inductors are different. In this paper, the dynamic minor loop characteristics of the magnetic core on the condition of the switching converter are defined. Then, the dynamic measuring method of the dynamic minor loop by using the chopper circuit is presented. Next, some typical loss characteristics derived from the dynamic minor loop measurement is discussed. Also, a novel loss calculation method of the ac filter inductor on the PWM inverter by using the modified loss-map method is proposed.

Mixed fault diagnosis in three-phase squirrel-cage induction motor using analysis of air-gap magnetic field

Abstract: In this paper fault diagnosis of induction motor under mixed fault is carried out using precise analysis of the air-gap magnetic field based on time stepping finite element method. By feeding voltage instead of current density to the finite element computation part, the drawbacks of the application of finite element method in fault diagnosis of induction motor are overcome. Normally static eccentricity and broken rotor bars faults have been individually diagnosed in the published papers. Here diagnosis of the mixed fault,including static eccentricity and broken rotor bars,is introduced which is considered as a novel part of the present work. Precise analysis of magnetic field in the air-gap of a faulty induction motor is carried and performance of the motor is predicted. Taking into account the magnetic core saturation is another advantage of the present work. This is required in the transient analysis of a faulty motor.

Permanent magnet polarized external rotor radial magnetic bearing

Abstract: The invention is a permanent magnet biasing inner rotor radial magnetic bearing, comprising inner magnetic conductor rings, stator iron cores, rotor iron cores, outer magnetic conductor rings, outer magnetic isolation rings, permanent magnet, excitation coils, and air gaps, where the stator iron cores I and II compose 8 magnetic poles in the positive and negative directions of X and Y axes at the left and right ends, each magnetic pole is wound with excitation coil, the inner magnetic conductor ring is inside the stator iron core, the rotor iron cores I and IV are outside the stator iron cores I and II, respectively; the rotor iron core II, the outer magnetic isolation ring, and the rotor iron core III are outside in the stator iron core III; the rotor iron cores I and II are interconnected through the outer magnetic conductor ring I; the rotor iron cores III and IV are interconnected through the outer magnetic conductor ring II; the outer magnetic conductor rings I and II are connected with the rotor iron cores II and III through the outer magnetic isolation ring, respectively; the air gaps are between the rotor iron cores and the stator iron cores; the inner magnetic conductor rings II and III are interconnected through the permanent magnet I, and the inner magnetic conductor rings III and I are interconnected through the permanent magnet II. And the invention can replace the existing magnetic bearings used in pairs, largely shortening axial distance.

A tunable magnetic inductor

Abstract: For integrated radio-frequency applications, tunable magnetic inductors are expected. A tunable magnetic inductor, based on magnetoimpedance effect, is presented in this paper. The proposed inductor is constructed with a magnetic inductor body, wound by an insulated coil, inducing a longitudinal dc bias magnetic field when a dc control current is flowing through. Formed by a conductive core coated by a high-permeability magnetic layer, the magnetic inductor body can be realized by either a thin-film structure or a composite wire. The reluctance models for both thin-film and composite wire structures are studied. A prototype tunable magnetic inductor, using a composite wire element, has been characterized. The results show that by varying the dc control current, the inductance L of the magnetic inductor can be tuned. The tunable range depends on the frequency of the current flowing through the inductor. A relative variation of inductance /spl Delta/L/L/sub 0/, up to 18% at low frequency (around 5 MHz), is achieved by applying a bias current of magnitude merely up to 15 mA. The quality factor varies from 5 to 17 in the measured frequency range. The proposed tunable inductor may be further optimized for high-frequency applications and has the potential to be realized in micro-electromechanical systems technology.

Amorphous alloy ribbon, nanocrystalline soft magnetic alloy and magnetic core consisting of nanocrystalline soft magnetic alloy

Abstract: Even if produced from a broad amorphous alloy ribbon, a nano crystal soft magnetic alloy, a magnetic core made of a nano crystal soft magnetic alloy, and the amorphous alloy ribbon for a nano crystal soft magnetic alloys which has the excellent alternate magnetic property, the small dispersion, the excellent temporal stability in high temperature, the excellent mass productivity can be provided. An amorphous alloy ribbon, wherein the alloy composition is represented by Fe 100-a-b-c-d M a Si b B c C d (atomic %), 0

Power transformer core fault diagnosis using frequency response analysis

Abstract: Power transformers are main devices in the performance of energy supply systems. Therefore, there is a great interest in its health state. Frequency response analysis (FRA) is nowadays an appreciated preventive technique used for transformer maintenance in order to detect winding displacements. But, in spite of the advantages of FRA, a systematic diagnosis procedure has not been still developed due to the physical meaning of the frequency response is not really obtained. Our research group has developed a three phase magnetic core model that provides the relations among the raw frequency response and the different parts inside the three phase transformer. Different effects of the magnetic core are recognized through different parameters of this model. A diagnosis procedure is available taking into account these parameters because the internal parts of the transformer are distinguished.

Flat magnetic element and power ic package using the same

Abstract: A flat magnetic element (1) includes a flat coil (4) arranged between a first magnetic layer (3) and a second magnetic layer (5). A gap (W) between coil wires of the flat coil (4) is filled with magnetic particles (7) having shape ratio S/L in the range of 0.7 to 1, wherein L represents the long axis length and S represents the short axis length. By using micro particles capable of effectively obtaining a high inductance value, it is possible to realize a flat magnetic element such a inductor having a reduced height.

Development of Measuring Equipment of DC-Biased Magnetic Properties Using of Open Type Single Sheet Tester

Abstract: The use of an iron core under dc-biased magnetization generates distorted asymmetrical hysteresis loop, and the iron loss is increased compared with that under sinusoidal excitation. Although the accurate measurement of magnetic properties under dc-biased magnetization is important for the estimation of iron loss of apparatuses, such as a reactor for an inverter which is operated under dc-biased condition, the reports of measurement of such magnetic properties are few. This is mainly because the measuring method of such magnetic properties and the method for accurate evaluation of dc-biased magnetization are not established yet. In this paper, a measuring system of magnetic properties of electrical steel sheet under dc-biased magnetization using an open-type single-sheet tester (SST) and a Helmholtz coil is developed. The newly developed system has an advantage that the interaction between ac and dc excitations is negligible, then the control is easy compared with the usual technique using a ring core or SST having both ac and dc exciting windings. It is shown that the increase of iron loss of 6.5% Si-Fe sheet due to the dc bias is larger than that of usual nonoriented silicon steel sheet

CMOS magnetic sensors with integrated ferromagnetic parts

Abstract: The paper deals with Hall and flux-gate magnetic field sensors consisting of integrated combination of CMOS ASICs and planar ferromagnetic components. Ferromagnetic parts are made of a soft amorphous alloy, integrated at the CMOS wafer in a post-processing production phase. When the sensors are exposed to an in-plane magnetic field, under the peripheries of ferromagnetic parts appears a strong magnetic induction perpendicular to the wafer surface. This perpendicular field is sensed either by Hall plates or planar coils. In the case of Hall magnetic sensors, such ferromagnetic parts give a magnetic gain of 2–10. Compared to conventional integrated Hall magnetic sensors, the new sensors have up to 10 times higher magnetic resolution and they respond to a magnetic field parallel with the surface of the chip. They are used as current sensors or angular position sensors. In the case of flux-gate sensors, both the saturation-forcing coil and the pick-up coils are realized as planar coils, using metallization layers that exist in the CMOS process. The integrated flux-gate technology is illustrated by a low-power two-axis magnetic field sensor suitable for a portable electronic compass.

FE-based Modeling of Single Phase Distribution Transformers With Internal Winding Short Circuit Faults

Abstract: This paper presents a fast and accurate phase variable model of single-phase distribution transformers with internal winding short circuit faults. The flux linkages of windings (including the winding formed with the shorted winding turns) are used as the phase variables. Their variation with the winding currents is used to represent the nonlinear magnetization of the iron core. The flux linkage variation is obtained from the solutions of a series of FE computation, covering the full operation range of the transformer with short circuit faults. It is described using tables and utilized by table look up in the developed model. An equivalent magnetizing current is defined to reduce the number of the FE computations for building the flux linkage tables. The implementation of the proposed FE-based model is studied and the verification is performed. Also, the application examples are presented

Control of eddy currents in magnetic vias for inductors and transformers in integrated circuits

Abstract: An embodiment is a magnetic via. More specifically, an embodiment is a magnetic via that increases the inductance of, for example, an integrated inductor or transformer while mitigating eddy currents therein that may limit the operation of the inductor or transformer at high frequency.

Effects of magnetic substrates on ac losses of YBa2Cu3O7 films in perpendicular ac magnetic fields

Abstract: Effects of a magnetic substrate on the ac losses of superconducting films were investigated by measuring the losses for octagonal disks of an YBa2Cu3O7 layer on a magnetic Ni–5at.% W substrate in perpendicular ac magnetic fields at 20Hz and 77K. At low fields, the losses depended on ac magnetic field amplitude B and film thickness t as ∝B3∕t instead of ∝B4∕t3 for a superconducting film on a nonmagnetic substrate. These results are described by considering the formation of a virtual infinite stack of superconducting films due to the magnetic mirror effect.

Real-time monitoring of iron-core and copper losses of transformers Under(Non)Sinusoidal operation

Abstract: The online monitoring of iron-core and copper losses of single- and three-phase transformers is important, particularly for transformers feeding nonlinear loads. This paper devises a new digital data acquisition method for the separate online measurement of iron-core and copper losses of three-phase transformers under any full or partial-load conditions. The accuracy requirements of the instruments (voltage and current sensors, voltmeters, and ammeters) employed are addressed. The measurement uncertainties are acceptably low if voltage and current sensors with 0.1%-0.5% accuracy are used.

Planar magnetic device and power supply IC package using same

Abstract: Disclosed is a planar magnetic device (1) having a planar coil (4) between a first magnetic layer (3) and a second magnetic layer (5) each composed of a mixture of a magnetic powder (7) and a resin. This planar magnetic device (1) satisfies the following relationship: W > L, when W is the distance between coil wires (4c, 4c) of the planar coil (4) and L is the maximum diameter of the magnetic powder (7). This planar magnetic device (1) makes a thin inductor having excellent characteristics or the like, since the planar magnetic device has such a structure wherein spaces between coil wires are filled with a fine magnetic powder which enables to effectively obtain a high inductance.