Showing papers on "Magnetic core published in 1989"

Miniature inductor for integrated circuits and devices

Abstract: Spaced apart conductive strips are provided in a first and third of three layers covering a semiconductor substrate. Magnetic core material is included in the second layer so as to be interposed between the conductive strips of the first and second layers. The first and second layers are joined at suitable points so that their respective conductive strips combine to form a helical electrical path which spirals about a core portion of the magnetic material in the second layer. The second layer can be patterned to define a toroidal magnetic path and/or to define a path including a magnetic gap. The armature of an electromechanical relay can be formed within the optional gap by depositing magnetic armature material to partially overlap a sacrificial support base. When the sacrificial support base is etched away, it leaves the overlying armature material free to move.

Power line communication system

Abstract: A power line communication system which includes an electrical power line having one or more loads which feed objectionable electrical noise back into the power line. The electrical noise is attenuated across a broad frequency range to enable effective communication over the power line by a directional common mode trap located between the point where the communication signals are applied to the power line and the source of the electrical noise. The trap requires only a capacitor for each electrical phase and a 1:1 transformer having a magnetic core and single turn, straight through windings. The trap is connected to provide a low impedance path to ground for the electrical noise, while providing a high impedance to ground for the communication signals.

High voltage high power DC power supply

Abstract: A high voltage, high power DC power supply includes a single turn primary winding driven through a resonating capacitor by an AC source having a frequency in excess of about 100 kHz The primary winding includes a pair of concentric cylindrical metal walls having opposite ends electrically connected to each other A volume between the walls includes plural secondary winding assemblies, having different axial positions along the walls Each of the assemblies includes an annular magnetic core surrounding the interior wall, a winding on the core and a voltage doubler rectifier DC voltages developed across each secondary winding assembly by the rectifier are added together to provide the high voltage, high power output The power supply energizes an X-ray tube having a grounded anode and a cathode at a DC voltage of approximately -150 kV, with a power requirement of between 15 and 60 kW The power supply and X-ray tube are mounted on a rotatable gantry including a slip ring assembly for coupling a relatively low voltage excitation source to the power supply

Power transfer circuit including a sympathetic resonator

Abstract: A power transfer circuit includes first and second windings (L1,L2) sharing a common magnetic core (101). Each winding (L1,L2) has associated with it a parallel capacitor (C1,C2) to thus form a pair of "tank" circuits. The first winding (L1) is connected at one end to a voltage supply and, at the other end, to ground through an FET switch (100,200). The switch (100,200) is turned on and off at a predetermined frequency and at a 50% duty cycle. The second winding (L2) and associated capacitor (C2) achieves parallel resonance at the predetermined frequency. Similarly the combined first and second windings (L1,L2) and associated capacitors (C1,C2) achieve parallel resonance at said predetermined frequency. The second winding (L2) need not be electrically connected to the first winding (L1) which transfers energy to it through the magnetic core (101). The transfer circuit efficiently couples power across a dielectric interface to a pickup coil (L3). One particularly good application of the power taansfer circuit is in connection with a contactless Smart Card.

Multiple turn low profile magnetic component using sheet windings

Abstract: A magnetic component (i.e. inductor or transformer) utilizes sheet winding patterns designed to enhance component assembly and maximize utilization of the core window areas. The windings are obtained from a copper sheet from which sheet winding patterns are obtained by etching, stamping or cutting the copper sheet. These winding patterns are contoured to fit precisely into the window area of the core of the magnetic component so that the window area is fully utilized. Basic symmetrical copper sheet patterns are used and these are sequentially stacked and combined to achieve multiple turn windings. These assembled winding components are connected to a bobbin which includes pins at its periphery to interconnect the copper sheet winding patterns to obtain the desired number of turns of the windings. The bobbin structure supports the component on a circuit board with the magnetic core of the component protruding through an aperture in the printed circuit board in order to permit a low profile mounting for the component.

Inductor transformer cooling apparatus

Abstract: Plate fin heat exchangers (11, 12 or 34, 35, 36) for transformers (10) and inductors (30) made of laminated iron cores (16 or 44) and insulated wire coils (13, 14, 15 or 45, 46, 47, 48) placed around the legs of the cores (16 or 44) are provided in the form of a plate fin between the coils of wire. The wire coils (13, 14, 15 or 45, 46, 47, 48) and respective heat exchangers (11, 12 or 34, 35, 36) are sandwiched together with the leg of the iron core (16 or 44) passing through the sandwich. The heat generated in the coils is in direct contact with the surface of the heat exchangers (11, 12 or 34, 35, 36). A narrow air gap (28 or 49) is incorporated in each of the plate fin heat exchangers (11, 12 or 34, 35, 36) at the core leg of each coil (13, 14, 15 or 45, 46, 47, 48) to reduce the path eddy currents can travel and thereby reduce eddy current losses which reduce the power of the transformer (10) or inductor (30).

Demagnetising factor and noise in the fluxgate ring-core sensor

Abstract: A method for measuring the demagnetisation of fluxgate sensors is introduced and used to evaluate the demagnetising factors for four ring-core sensors having 5, 10, 15 and 20 wraps of magnetic core ribbon. The demagnetising factor is proportional to the number of wraps, and the noise is also proportional to the number of wraps except for the more noisy 5-wrap core. The estimated internal core noise was 1 pT RMS taking into consideration the demagnetising factor and the relative permeability of the core material.

Method of manufacturing ultra small track width thin film transducers

Abstract: An ultra small track width magnetic transducer and manufacturing method. The transducer has two coplanar confronting magnetic poles provided by a thin film layer of magnetic material. The thickness of the layer defines a track width. A transducing gap is etched in the magnetic layer by utilizing focused ion beam milling technology. The thusly obtained gap has a predetermined length and depth and it separates the magnetic layer into two confronting coplaner magnetic poles. A layer of non-magnetic material is deposited over the magnetic layer to fill the transducing gap. The transducing gap may be etched in a plane extending orthogonally to the plane of the magnetic core layer. Alternatively, the transducing gap plane may extend at an oblique angle to the magnetic core layer to obtain a transducing gap useful in aszimuth recording/playback.

Electrical Machines and Drive Systems

Abstract: Current and power flow in electrical circuits - electrical machines, what they are and what they do, types, current flow in electric circuits, review of electric circuit power basic electrostatic and electromagnetic field theory - the electrostatic field, energy storage and force development in the electrostatic field, the electromagnetic field, electromagnetic induction, energy storage and flow in the electromagnetic field force and torque development in magnetic circuits, properties of magnetic materials - force on current-carrying conductor located in magnetic field, force and torque development on current-carrying loops placed in magnetic field, properties of magnetic materials, the hysteresis loop, Eddy current loss, boundary relationships for the magnetic field, energy stored in the magnetic field, fringing, Maxwell's stresses in the magnetic field, force development at iron/air boundaries appropriate to a linear actuator, rotary motion actuators, torque development, torque development in rotating machines with cylindrical or salient iron/airgap surfaces, effects of slotting, rotary actuator with permanent magnet polarization, DC moving-coil actuator, Faraday's rotator and disc, permanent magnetism voltage and current relationships in an ideal two-winding transformer - effect of core saturation, leakage flux, equivalent circuit and phasar diagram of two-winding iron-cored transformer, voltage regulation of a transformer, magnetizing current requirements and energy losses in transformer cores, transformer efficiency and testing, equivalence of winding resistance and leakage reactance values referred to the same number of turns, power transfers across primary and secondary windings of two-winding transformer, autotransformers, high frequency and current transformers windings for rotating machines - the magnetic field of an armature winding, the radial magnetic field of ac armature windings, the tangential magnetic field of armature windings, practical winding considerations, resultant magnetic field of polyphase winding (rotating field), principal magnetic field properties of armature windings, emf induction in armature windings, power flows relating to rotating machine windings direct current machines - general arrangement, performance, commutation and torque development of a dc machine synchronous machines induction machines. (Part contents)

Thin film magnetic head

Abstract: PURPOSE:To prevent the movement of magnetic domain walls and to obtain a thin film magnetic head, which has a stable output, by obtaining >=one non-magnetic part in an island shape in the middle of a magnetic thin film pattern to constitute a magnetic circuit. CONSTITUTION:A magnetic core 1 is composed of the upper and lower layers of the magnetic thin film patterns to be interposed between a coil 2 and these patterns are connected by a back gap part 3 and further exposed to an external part in a slider floating surface 4. In a gap part 5, the patterns are faced each other with a non- magnetic film to be formed by the alumina film, etc., whose thickness is 0.1-1.0mum around, between. For the magnetic core 1, in order to prevent the lowering of magnetic efficiency in the middle of a way from the gap part 5 toward the back gap part 3, patterning is executed so that the width of the magnetic core can be wide from a place to be separated from the gap part 5 by 10-20mum. Further, in the place where the magnetic core 1 is extended, an island-shaped part 6 of non-magnetism, whose length and width are 2-6mum around, is formed and this island-shaped part 6 is formed simultaneously with the patterning of the magnetic core 1. This non-magnetic island- shaped part 6 prevents the large movement of the magnetic domain walls at the time of head operation and presents the thin film magnetic head to have the stable output.

Analysis of permanent magnet synchronous motors

Abstract: A detailed representation of buried permanent magnet synchronous motors at steady state is presented. An equivalent circuit is proposed that accounts for the saliency of the machine and for the particular influence of iron core losses on the machine operations. Both no-load and loaded conditions are analyzed and experimentally tested in order to describe the influence of the armature current on the rotor flux distribution. Experimental tests on a 2 HP buried permanent magnet machine are presented to validate the proposed approach. >

Magnetic recording medium and magnetic storage

Abstract: A magnetic recording medium that uses, as a protective coating layer provided on a magnetic layer for magnetically recording signals, a layer made of a nonmagnetic material consisting of two ore more elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and one or more elements of N, C, O, and B, or made of a magnetic material consisting of one or more elements of Co, Fe, Ni, and Gd, one or more elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and one or more elements of N, C, O, B, and Si is excellent in sliding endurance. When the protective coating layer is made of the nonmagnetic material, the magnetic recording medium is also excellent in corrosion resistance, and when the protective coating layer is made of the magnetic material, the spacing between a magnetic head and the magnetic recording medium can advantageously be made large. Both the cases are high in reliability, and suitable for high density magnetic recording. The magnetic recording medium can be used in combination with a magnetic head that uses a metal magnetic alloy as at least part of the magnetic core to provide an excellent magnetic storage.

Core loss in amorphous cut cores with air gaps

Abstract: The effects of air gaps on the high-frequency core loss in cut cores made of amorphous ribbons are discussed and methods to reduce the core loss in them are proposed. It has been found that the high-frequency core loss in amorphous cut cores with air gaps increases strikingly with increasing air-gap length. The increase in the core loss due to air gaps is remarkable in high-frequency and low-induction range. Measurement of leakage magnetic flux as well as analysis of the flux distribution and the eddy current in an amorphous core with the finite-element method suggests that the increase in the core loss due to air gaps observed in the amorphous cores can be attributed to the in-plane eddy current loss generated by the leakage flux perpendicular to ribbon surfaces. Suppression of the leakage flux normal to ribbon surfaces by using semicircular cores and reduction in width of ribbons of which cores are made decreases the high-frequency core loss in amorphous cut cores with air gaps. >

Induced electric fields by magnetic stimulation in non-homogeneous conducting media

Abstract: The electric fields and current densities induced by a magnetic field have been calculated using the concept of mutual inductance. The spatial derivative of the electrical field generated by a coil located below and parallel to a semi-infinite conducting medium has been evaluated along lines parallel to the coil. The results have been verified experimentally and are important for the understanding of the mechanisms of peripheral axonal excitation. >

Equilibrium and stability studies for an iron core tokamak with a poloidal divertor

Abstract: A study of plasma equilibrium and stability in a tokamak with an unsaturated iron cpre is presented. A spool model is developed for the iron core. Both a simplified force balance code and a Grad-Shafranov solver are used to study the plasma equilibrium. It is observed that the iron can strongly modify the conditions for equilibrium and stability, and in some cases an infinite cylinder model for the iron core is not adequate. Corrected criteria for plasma position stability in the presence of an iron core are introduced.

Fe-based soft magnetic alloy

Abstract: An Fe-based soft magnetic alloy essentially consisting of an Fe-based alloy including fine crystal grains used for such as a magnetic core. An average size of the fine crystal grains is controlled to 300 Å or less. Each of the fine crystal grains is composed of a body-centered cubic phase at least partially including a super lattice. This alloy has a high saturation flux density and excellent soft magnetic characteristics such as a low iron loss and a high magnetic permeability.

Very thin soft magnetic Fe-based alloy strip and magnetic core and electromagnetic apparatus made therefrom

Abstract: In the production by the single-roll technique of a thin amorphous strip as the matrix for the manufacture of a thin Co-based amorphous alloy strip or a thin Fe-based microcrystalline alloy strip, the conditions for the production are controlled to those specified by the invention The production conditions thus controlled concern the atmosphere and the pressure to be used for ejecting a molten metal onto a rotating cooling member, the shape of a nozzle, the distance between the nozzle and the rotary cooling member, the material for the rotary cooling member and peripheral speed of the rotary cooling member, etc The individual numerical values of these conditions are severally important The thin strip which has an extremely small thickness and few pinholes thus is obtained In the thin Co-based amorphous alloy strip, the extreme decrease of thickness to below 48 μm notably enhances the soft magnetic properties such as permeability and core loss in the high frequency range In the thin Fe-based microcrystalline alloy strip, the extreme decrease of thickness not more than 10 μm permits improvement of resistance to embrittlement in addition to the improvement in the soft magnetic properties

Geometrical factors affecting magnetic properties of wound toroidal cores

Abstract: Although toroidal cores wound from grain-oriented silicon iron strip are basically simple devices used in many applications, their magnetic properties are known to vary in a complex manner with core dimensions. The theoretical effects of radial magnetic field and flux density variation, interlamina normal flux, and winding stress on the real and apparent power loss and the permeability of a range of toroids with typical commercial dimensions are discussed. Comparisons are made with actual performance. It is shown that the radial variation of flux densities has a very small effect on the power loss and permeability but the interlamina normal flux has an influential effect, particularly in small-diameter toroids. It is shown that to obtain low losses and magnetizing currents, toroids should be designed using wide strips having large internal diameter and low buildup. >

A current and/or voltage detector for a distribution system

Abstract: A current and voltage detector (1) for a distribution system is provided with a lower section (2), an upper section (3) and a fastening means for combining the lower and upper sections into one body. The lower section comprises: a first groove for receiving an electric wire of the distribution system; an optical type current sensor (4); an optical type voltage sensor (5); and a potential divider for supplying a voltage to the voltage sensor. The upper section comprises: a second groove for receiving the electric wire; and a U-shaped magnetic core (6) for applying a magnetic field to the current sensor.

Ignition coil with permanent magnet

Abstract: In an ignition coil in which an air gap portion is provided at a portion of an iron core forming a closed magnetic circuit, which includes an exciting part iron core having a primary coil and a secondary coil wound therearound, and a strong permanent magnet is inserted in the air gap portion, the closed magnetic circuit is constructed to have the iron core and permanent magnet provided with respective suitable shapes, dimensions, properties, etc. so as to make most of the characteristics of the strong permanent magnet, thereby drastically reducing the size and weight of the ignition coil. Further, a concrete improvement of the construction of the closed magnetic circuit of the ignition coil is attained to assure excellent magnetoelectric conversion performance of the ignition coil.

Brushless DC motor

Abstract: A brushless DC motor includes a rotor assembly and a stator assembly. The rotor assembly includes a plurality of rotor permanent magnets of a first polarity. The stator assembly includes a plurality of stator magnetic field assemblies facing the rotor assembly. Each stator magnetic field assembly includes a box-like magnetic core having an opening facing the rotor assembly. A permanent magnetic core is disposed within the box-like magnetic core having a surface facing the rotor assembly and possessing a second polarity at this surface. A field coil is wound in proximity to the box-like magnetic core for energizing the stator magnetic field assembly. A boosting permanent magnet is provided along an outer surface of the box-like magnetic core.

Audio current pick-up device

Abstract: An audio current pick-up device for use with an electric wire 6 carrying an electric current containing audio information comprises a pair of substantially identical magnetic induction coil assemblies 26, 27 disposed in parallel to each other with an axial deviation and orthogonally to the wire, each coil means including a magnetic core in the form of rod 30, 38 and a pair of induction coils 32A, 32B, 39A, 39B wound in opposite directions on respective halves of its core rod. An output of either of the induction coils is phase-shifted by a preset amount and composited with an output of the other magnetic induction coil to form a sound pick-up signal from which a sound output signal is derived.

The power transfer mechanism of MMIC spiral transformers and adjacent spiral inductors

Abstract: The WATMIC-EMsim software is currently being used to analyze the coupling between the two coils of an MMIC (monolithic microwave integrated circuit) transformer and between two adjacent MMIC square spiral inductors. For the transformer it is found that the simple magnetic coupling in power transfer between the two coils only occurs at the low frequency end of the microwave range. For the adjacent inductors, it is found that the coupling S/sub 21/ is very small. It starts at -26 dB when the two spirals nearly touch and rapidly drops off a function of 1/d/sup 7/, where d is the center-to-center separation between the two spirals. >

Non-saturating magnetic amplifier controller

Abstract: A magnetic amplifier including a magnetic core (11) having a primary leg (15), a secondary leg (17), and a control leg (13). A primary winding (21) is wound about the primary leg (15) of the magnetic core for generating a non-saturating magnetic AC flux in the magnetic core, and a secondary winding (23) is wound about the secondary leg (17) of the magnetic core. A control winding (19) for conducting DC current is wound about the control leg (13) of the magnetic core for controlling as a function of the DC current, without saturating the magnetic core, the reluctance of the control leg (13) relative to the reluctance of the secondary leg (17). By controlling the relative reluctance, the amount of magnetic AC flux coupled to the secondary winding (23) is controlled, thereby controlling the output voltage provided by the secondary winding (23).

Magnetic device for high-voltage pulse generating apparatuses

Abstract: A magnetic device for high-voltage pulse generating apparatuses including (a) at least one cylindrical conductor for defining a cavity, the cylindrical conductor being provided with input and output terminals and an inlet and an outlet for a coolant; (b) at least one sealing member fixed to the cylindrical conductor; (c) a plurality of wound magnetic cores each composed of a magnetic ribbon laminated with an insulating layer, the wound magnetic cores being fixed to the cylindrical conductor with such an interval as to provide a certain space between the adjacent wound magnetic cores; and (d) an outer ring member disposed between each of the magnetic cores and the cylindrical conductor and having at least one path for permitting the coolant to flow therethrough, whereby the coolant flows in a radial or circumferential direction of each wound magnetic core in each space between the adjacent wound magnetic cores.

Investigation of the inrush phenomenon: a quasi-stationary approach in the harmonic domain

Abstract: A novel approach for the investigation of the inrush phenomenon in single and three-phase transformers is presented. It consists of the calculation of a sequence of quasi-steady-state images using harmonic domain computation. Thus, lengthy-time domain simulations with the related round-off and truncation errors are avoided. The advantage of the method is its robustness compared to a time-domain simulation with sufficiently small time steps to represent the wave shapes of currents and voltages accurately over a relatively long time span. An important result of the analysis is the fact that the attenuation of inrush currents is not affected by the eddy current and hysteresis losses in the iron. Therefore, no discretization of the laminations is needed, which considerably simplifies the computations without any loss of accuracy. The attenuation is solely determined by the resistance of the external circuit and the total inductance of the circuit, including also that of the iron core. It is shown how remanence and off-peak switching combine to establish the initial bias which determines the magnitude of the inrush current. >

Bar magnet for construction of a magnetic roller core

Abstract: An improved bar magnet and method of construction, and an improved magnetic core comprising an assembly of such magnets, for use in a processing station of an electrostatographic printing machine. The improved bar magnet is formed of permanent magnet material having magnetic domains therein that are magnetized along epicycloidal curve segments. The external magnetic flux density is improved over that of a conventionally-magnetized magnet. An injection mold for inducing the particular epicycloidal alignment of magnetic domains in the improved bar magnet is provided.

Compressed powder magnetic core and method for fabricating same

Abstract: A compressed powder magnetic corer is disclosed in which the mixing ratio (vol %) of the parts occupied by binder resin, ferromagnetic powder and void formed therebetween is set for a specified value so as to obtain desired magnetic characteristics.

Magnetic head and method of manufacturing the same

Abstract: A magnetic head comprises a pair of magnetic core halves (1a, 1b), which are abutted with each other through a nonmagnetic material to define a magnetic gap (2), and ferromagnetic thin films (3a, 3b). The magnetic core halves (1a, 1b), which are formed of ferromagnetic oxide, have gap forming surfaces to be abutted with each other. The ferromagnetic metal thin films (3a, 3b) are selectively formed on the gap forming surfaces of the pair of magnetic core halves (1a, 1b). A ferromagnetic thin film (3b) is so formed that portion (12b, 12c, 12d) to be provided with a track width regulating groove (13b), a coil groove (13c) or a joining member receiving groove (13d) is exposed within a gap forming surface of one magnetic core half member (7b). Another ferromagnetic thin film (3a) is so formed that, in a gap forming surface of another magnetic core half member (7a), a portion (12e, 12f) opposite to the coil groove (13c) or the joining member receiving groove (13d) to be provided in the gap forming surface of the magnetic core half member (7b) is exposed. These ferromagnetic thin films (3a, 3b) are selectively formed by ion beam etching. Grooves (13b, 13c, 13d) are provided in one magnetic core half (1b) by mechanical working through a dicing saw or the like.

Inverter output circuit

Abstract: There is provided an improvement in an inverter power supply of the type including an output transformer of the type having a high permeability magnetic core, input winding means for applying input current pulses to the core; a first output winding wound on the core; and a second output winding wound on the core. The power supply further includes first and second output terminals and output circuit means for connecting the individual output windings to the terminals in a fashion that opposite polarity output current pulses induced in the output windings by the input current pulses are applied across the terminals in a preselected first polarity. The improvement in this power supply comprises forming the output transformer with the two output windings having essentially the same number of turns and being wound in a selected direction so that current flow caused by freewheeling from an output inductor will flow simultaneously through the two output windings in a direction to cause opposite polarity magnetizing flux in the transformer core and providing means for mounting the two output windings of the transformer adjacent to each other on the core in a tight overlapping relationship with a coefficient of coupling greater than 0.950 and preferably greater than 0.980. The best results are obtained with the coefficient greater than 0.990.