Showing papers on "Magnetic core published in 1992"

Non-contact data and power connector for computer based modules

Abstract: The invention discloses a non-contact way to provide electrical power and two-way digital communications between a host computer and its peripheral modules, such as IC memory cards, modems, and A/D converters. A special magnetic core is employed to provide efficient transfer of both large amounts of electrical power and high speed digital communications through transformer action. Peripheral modules requiring different power supply voltages or different data voltage levels can be accommodated and intermixed with modules of other types in the same host system. The mechanical design of the connector includes detent structure to align the assembly in three dimensions, both upon mating, and under mechanical environmental stress conditions during operation. The magnetic core has both power supply and data windings; the data winding has sections of opposite polarity so that the power supply signal imposed on the data winding cancels itself.

Equilibrium analysis of iron core tokamaks using a full domain method

Abstract: An efficient full domain method for plasma equilibrium construction in iron core tokamaks is described. Illustrative calculations and comparison with results obtained from a finite domain method using JET data are given. The results show that the two methods are in agreement with respect to global plasma parameters such as stored energy, internal inductance, volume, and edge safety factor. However, when there is an uncertainty in the magnetic flux loop measurement, the full domain method yields a more accurate separatrix location

Three coil bridge transformer

Abstract: The magnetic core of the transformer is an E--E shaped core. The primary winding of the transformer is divided into three substantially identical planar coils, each coil being wound on one of the three separate core posts. The coils are wired in series such that a current in the primary winding will induce substantially identical magnetic fluxes in the two outer core posts, and an opposite flux in the center post. The secondary of the transformer is formed by a contact plate and a conductor frame which provide conducting paths through the window regions of the E--E core. The bottom of the core is mounted in a recess in the conductor frame. Positioned within in the conductor frame are four rectifiers which make electrical connections to the secondary contact plate. When the transformer delivers power, the voltage on the primary winding will be divided 1/4 on each of the outer coils and 1/2 on the center coil post. During this time only two of the rectifiers will be conducting current. During freewheel times, with no primary voltage, the load current will divide evenly among the four rectifiers. During commutate intervals, between freewheel and on times, the voltage on the primary winding will divide evenly among the three coils. This novel transformer permits a switch mode power supply to supply more power while providing more even cooling.

Characteristics and analysis of a thin film inductor with closed magnetic circuit structure

Abstract: A spiral inductor with closed magnetic circuit was fabricated by an RF sputtering machine and photolithography techniques. The inductance was twice as large as that of a reference sandwiched inductor. The authors analyzed the frequency characteristics of the proposed inductor from three points of view: inner current distribution, flux distribution, and eddy current in the magnetic film. The calculated results agree with the measured ones. It is demonstrated that the current distribution inside the inductors is mostly limited to within the area of the conductor up to several hundred megahertz. The frequency characteristics are influenced by the eddy current loss in the Permalloy film and the stray capacitance between the inductor and the ground plane. The permeability of the Permalloy film is less than that of its as-deposited state, but the closed magnetic circuit structure helps to reduce the influence of the demagnetizing field. >

Magnetic field generating device

Abstract: There is disclosed a magnetic field generating device for use in a magnetooptical recording apparatus of a magnetic field modulation method. The device includes a planar spiral coil, of which coil pitch is smaller in the peripheral area than that in the central area thereof, thus realizing a relatively wide area of magnetic field of uniform intensity, with a low inductance. Because of the planar structure, the device can be positioned very close to the recording medium, and can achieve the high speed switching required in the magnetic field modulation method, without a large power source.

A non-linear coupled 3D model for magnetic field and electric circuit equations

Abstract: The authors propose a 3-D numerical model in which the magnetic field and electric circuit equations in the absence of eddy currents are solved simultaneously. To consider the magnetic equations, use is made of a magnetic vector potential formulation with the gauge condition (A.w=0) which makes it possible to reduce the number of unknowns. To take into account the magnetic and electric nonlinearities, the Newton-Raphson algorithm has been used. Two applications have been considered: an iron core coil fed by sinusoidal voltage through a diode and a current transformer. For the latter example the results obtained from the simulation are compared with experimental ones. >

A fully integrated micromagnetic actuator with a multilevel meander magnetic core

Abstract: To generate and to confine a magnetic flux in the magnetic core and at the same time minimize coil series resistance, low-resistance meander conductors located in a single plane were interwoven with multilevel meander magnetic cores. This 'wrapped' solenoid (with the core wrapped around the conductor) was fabricated in a fully integrated fashion. A micromagnetic actuator was realized by incorporating a surface micromachined nickel-iron cantilever beam as part of the magnetic circuit of the core. The nickel-iron cantilever beam was 2.5 mu m thick, 25 mu m wide and 780 mu m long, and the magnetic circuit contained 17 turns of meander type solenoid coils. Tip deflection of 4 mu m in the vertical direction was achieved when a DC voltage less than 1 V (and resulting drive current of 600 mA) was applied to the coils. This fully integrated multilevel topology offers a variety of micromagnetic applications, which can be fabricated on the same substrate with an integrated circuit and actuated with low voltages. >

Soft magnetic alloy, method for making, magnetic core, magnetic shield and compressed powder core using the same

Abstract: A soft magnetic alloy having a composition of general formula: (Fe.sub.1-a Ni.sub.a).sub.100-x-y-z-p-q Cu.sub.x Si.sub.y B.sub.z Cr.sub.p M 1 q (I) wherein M 1 is V or Mn or a mixture of V and Mn, 0≦a≦0.5, 0.1≦x≦5, 6≦y≦20, 6≦z≦20, 15≦y+z≦30, 0.5≦p≦10, and 0.5≦q≦10 and possessing a fine crystalline phase is suitable as a core, especially a wound core and a compressed powder core.

Digital model for transient studies of a three-phase five-legged transformer

Abstract: A flux linkage model for a three-phase five-legged transformer is derived for the first time. The effects of mutual and leakage inductances, saturation, eddy current loss, hysteresis and residual fluxes of the nonlinear iron core are included. A straightforward and novel method for determining both the apparent and incremental inductance matrices for a loaded two-winding five-legged transformer is derived. Simulations presented in this study are based on apparent inductance (λ/i) rather than incremental inductance (dλ/di) because this approach was found to be preferable for predicting the behaviour of the laboratory transformer used. Eddy current and hysteresis losses are combined into one core loss term which is accounted for by a voltage-dependent resistance load on the secondary. The flux in each segment of the iron core and in the air gaps and tank are computed at each step. The model thus yields a completely detailed description of the transformer's behaviour. A predictor-corrector algorithm written in FORTRAN is used to solve the set of nonlinear differential equations that describe the transformer. A 386-based computer has been used to generate voltage and current waveforms faithful to laboratory data. Transformer inrush current and ferroresonance are selected as test cases because of the extreme computational demands that these transients place on the computer model. The model can be implemented using only nameplate and conventional test data along with the B-H curve of the core material. The method is thus well suited to the practical needs of engineers in industry.

AC/DC current detecting method

Abstract: An AC/DC current detection method that can detect small and large changes in current, by employing a high-frequency excitation current applied to a coil wrapped around an annular iron core. The change in this value is determined for operation in the region of the coercive force of the iron core or as the change in an extreme value thereof.

Process for making microcomponents integrated circuits

Abstract: A process for fabricating discrete electrical microcomponents, such as microtransformers, microautotransformers and microinductors, on a semiconductor substrate in which two patterned layers of electrically conductive material are electrically connected through vias in two interposed layers of electrically insulating material to form electrically conductive coils around a magnetic core formed by a patterned layer of magnetic material interposed between the two insulating layers. Laminated magnetic cores may be formed by patterning multiple layers of magnetic material. The microcomponents can also be formed without magnetic cores and can be formed on insulating substrates.

High speed miniature solenoid

Abstract: A high speed solenoid valve that has a housing with an inlet and outlet that are typically connected to a pneumatic system to control the flow of air across the valve. The solenoid has a first magnetic core coaxial with an armature. Wrapped around the first core is a coil that is connected to a source of power. The coil emits a magnetic flux when current flows through the coil. Adjacent to the coil is a second magnetic core that is attached at one end to the first core and spaced from the opposite end of the first core by a first bushing. Attached to the armature is a magnetic plate that is adjacent to the spaced apart ends of the first and second cores. When the coil is energized, the magnetic flux flows through the magnetic cores and plate, pulling the plate toward the cores and moving the armature from a first to a second position. The solenoid valve has a rod that is adjacent to the armature, such that the rod is moved from a first position to a second position by the armature, when the plate is pulled by the magnetic field of the coil. A spring is attached to the rod to push the rod and armature into the first position when the coil is deenergized. The rod has a first spool at one end which is seated on a second bushing, such that the first spool prevents fluid communication between the housing inlet and outlet when the rod is in the first position. When the coil is energized and the rod is moved into the second position, the first spool is unseated from the second bushing to allow air to flow through the valve.

Heat resistant and explosion-proof type permanent magnetic synchronous motor

Abstract: A heat resistant and explosion-proof permanent magnetic synchronous motor having a stator which includes an armature iron core made by piling up steel plates with surface covered with a mineral insulation material and disposed on an inner peripheral surface of a pressure case, an armature coil made by winding a wire covered with a mineral insulation material around a slot of the armature iron core, a can hermetically sealing the armature iron core, a back-up sleeve supporting the can at a portion where the armature iron core is not provided, and a slot piece of a mineral insulation material supporting the can at an opening portion of the slot. The motor also includes a rotor including a magnetic yoke connected to an outer peripheral surface of an actuating shaft provided to penetrate the pressure case and rotatably supported thereon, a plurality of rotor magnetic poles disposed on an outer peripheral surface of the magnetic yoke, and a non-metallic case covering an outer peripheral surface of the rotor magnetic pole.

High speed motor

Abstract: A motor of a high speed, high torque and high efficiency. In a motor of a reluctance type, etc., according to the present invention, when the current application to an armature coil (32a) is stopped via a switching device in connection with a negative voltage side, the magnetic energy stored in a magnetic core is prevented from flowing back to the power supply by a diode (21a) for blocking a reverse current, and flows into a capacitor of a small capacitance, charging the capacitor and holding the voltage at a high value. Therefore, the current in the armature coil decreases rapidly. After the lapse of a predetermined time, the next armature coil (32e) is energized. The high voltage of the capacitor is applied to the coil (32e) at this time. Therefore, the current of the coil (32e) increases rapidly. Since the rise and fall of the current applied to the armature coil are made sharp, the motor can rotate at several tens of thousands r.p.m. Another means is adopted. While the current is applied to the armature coil, an inductance coil is energized too. When the currents in both coils are stopped, the magnetic energy stored in both the coils is made to flow into the capacitor and charge it. By this stored energy, the next armature coil is energized. The means compensates the energy loss due to the copper and iron loss.

Magnetic reproducing head having a distributed-constant circuit type magnetic field detector

Abstract: A distributed-constant circuit type magnetic field detector which includes a magnetic member whose permeability varies with changes in a magnetic field applied thereto disposed at a point where a magnetic field is produced in a distributed-constant circuit excited with an electromagnetic wave and a detector for detecting a change in electromagnetic field distribution in the distributed-constant circuit produced by a variation in permeability of the magnetic member upon application thereto of a magnetic field to be detected.

Tandem field alternator having an improved coil and slip ring connection and method of making the same

Abstract: A tandem Coil armature in which a pair of spaced-apart field coils [91,92] are wound on bobbins [12,14] mounted within a set of magnetic core pieces [16,18,20,22]. Two L-shaped conductors [27,28] pass through passageways through the core pieces and connect the windings to slip-rings [72,74]. Insulated conductor carriers [31,32,37,38] sized to mate with passageways and recesses in the core pieces support the L-shaped conductors and electrically insulate them from the magnetic core piece material. The core pieces are mounted for rotation with the rotor shaft [10] and include interleaved claws at their periphery which form the rotors magnetic poles.

Numerical calculation of 3D eddy current field and short circuit electromagnetic force in large transformers

Abstract: The improved T- Omega method is employed to calculate the three-dimensional transient eddy current field in large transformers, as well as the short-circuit electromagnetic forces acting on the transformer windings. The effects of the magnetic shielding and initial angles of currents are studied, and the nonuniform distribution of ampere-turn along the height of the windings is taken into account. Thus, a common software package is developed. Two different transformers are analyzed, and the computed results show agreement with measured ones. >

Permanent magnet rotor

Abstract: PURPOSE:To improve motor efficiency and output by specifying the circuit constitution of a rotor and further the ring magnet. CONSTITUTION:According to the basic constitution of a magnetic path, a conductive member 13 is buried in the circumferential slot 11a of a circular magnet 11, and also a short-circuit ring 14 is arranged to make a cage-type conductor 15, and a laminated iron core 12 made of soft magnetic material is arranged on the inside of that magnet 11. The magnet 11 is not square but circular, and a circumferential slot 11a is provided. It is of such constitution that one laminated iron core is not provided with a circumferential slot, a magnetic slot, and a magnetic resistance barrier slot. Accordingly, by putting it in such constitution that the magnetic fluxes from the ring magnet 11 can be focused directly on the side of a stator through only the space required for rotation, the efficiency of a permanent magnet type synchronous motor can be improved, and by making the ring magnet 11 a rare earth-iron magnet wherein ultraquenching powder of rare-earth-iron alloy is directly compacted in the shape of a bulk, the output can be improved without marring the resistance to demagnetization of the permanent magnet type synchronous motor.

3D eddy current losses calculation in transformer tanks using the finite element method

Abstract: The authors discuss the 3-D electromagnetic modeling of a transformer to evaluate eddy current losses in the tank. To achieve this, several numerical methods are used with two 3-D field computation packages. Conventional volume elements and shell elements are used for the modeling of thin conducting regions. Surface elements are used for the modeling of conducting regions with a reduced skin depth. The results, along with several characteristics of the tank and magnetic core, are compared. The influence of the characteristics of these two components is investigated. >

Method for manufacturing amorphous magnetic core

Abstract: An amorphous magnetic core is arranged to be obtained by cutting a plurality of amorphous sheets to have a predetermined cut length by a cutter device and supplying the cut sheets to a rectangularly forming device, the sheets being supplied from an uncoiler device including a plurality of reels around which the sheets are wound, by winding the sheets of a predetermined number around a forming mandrel successively to form them into a rectangular shape, thereby forming the magnetic core, and by subjecting the magnetic core to magnetic annealing in an annealing device.

Cooling of electromagnetic apparatus

Abstract: An electromagnetic apparatus such as a transformer or a single winding inductor is provided with a cooling arrangement. The apparatus has a magnetic core and a coil winding disposed about and carried by a leg of the core. The magnetic core has legs connected to the leg that carries the coil winding and these legs have flat surfaces that directly contact a flat surface of a metallic heat sink to thereby provide a direct heat conductive path from the legs to the heat sink. Heat generated in the coil winding is transferred to the heat sink via the leg that carries the coil winding and then to the heat sink via the legs that directly engage the heat sink. Heat generated in the magnetic core due to hysteresis or eddy current loss is also transferred to the heat sink.

Force calculation in transformer windings under unbalanced MMFs by a non-linear finite element code

Abstract: The author considers the computation of the electromagnetic axial forces on the windings of a step-up-generator transformer under unbalanced MMFs of the same phase by means of a finite element code. The unbalance between the MMFs of the same phase, which might be on the order of the nominal MMF, is caused by the high saturation of the iron core, which occurs during the transient due to a wrong parallel of the transformer with a network having a very low impedance. The evaluation of these MMFs is made by a nonlinear circuit model of a three-phase five-limb transformer. With the peak values of MMFs, the magnetic field in the transformer window is computed by a two-dimensional nonlinear code, and then the Lorentz forces on the windings are evaluated. The result of the computation is expressed as the ratio between axial forces with and without MMF unbalance as a function of the impedance of the network with which the wrong parallel occurs. >

Method for making multilayer magnetic components

Abstract: Multilayer magnetic components can be made with reduced cracking and magnetic degradation by forming layers having patterns of magnetic and insulating regions separated by regions that are removable during sintering. Advantageously, when the layers are stacked, layers of removable material are also disposed between magnetic regions and insulating regions so as to produce upon sintering a magnetic core within an insulating body wherein the core is substantially completely surrounded by a thin layer of free space.

Magnetic head having a thin film conductor coil assembly formed separate from a magnetic head core

Abstract: A magnetic head which can be miniaturized while maintaining the performance thereof includes a thin film conductor coil assembly having a magnetic core connected magnetically to magnetic substances and stepping across a non-magnetic substance located between the magnetic substances of a substrate and a thin film conductor coil formed with the magnetic core as a thin film magnetic core. This thin film conductor coil assembly is attached to a slider provided with a magnetic head core. The magnetic head core includes an I-core in which magnetic substances are formed on both sides of a non-magnetic substance, and a U-shaped core composed of a magnetic substance, formed together in one integral body with a magnetic gap provided therein. This magnetic head core is fitted into a slit in the slider, and the thin film conductor coil assembly is attached thereon. With this construction, it is possible to form the thin film conductor coil into a thin film and to enlarge the magnetic path area, thereby to miniaturize the magnetic head while maintaining the performance thereof.

Development of a large-capacity superconducting cable for 1000 kVA-class power transformers

Abstract: A large-capacity superconducting cable for 1000-kVA-class power transformers has been designed and fabricated. The cable is a triply stacked multistrand (6*6*6) type. The elementary strand has 19050 NbTi filaments 0.63-mm thick in a CuNi matrix. The test cable is installed as the secondary winding in a superconducting transformer with iron core in a room-temperature space. The primary winding is the second-level subcable of the secondary one and the turn ratio is nearly 14. The designed capacity of the test cable is 4.545 kA at the secondary voltage of 220 V. The peak value of the current, 6.43 kA, is 78% of the critical current on the load line. The maximum current of the cable at 60-Hz operation was 3.78 kA (peak). The experimental results suggest that the degradation in maximum current of the test cable is related to current transfer between the cable and the copper terminal plate. >

Thin Film Inductor with Multilayer Magnetic Core.

Abstract: In this paper, thin film micro inductor was investigated from the stand point of increased quality factor (Q) and inductance (L). To obtain a high Q, it is important to use a magnetic core in which iron loss is small in high frequency. The thin micro film inductor was prepared using multi-layered CoNbZr/ AIN film. The best condition for high Q was investigated by changing the size of magnetic core and structure of multilayer and exciting coil. The Q and L are increased with decreasing thickness of one magnetic layer and increasing one interlayer. The demagnetization of open magnetic circuit of inductor is decreased by using multi-layered magnetic core. The stray capacitance between coil and magnetic core is dominant in these thin film inductors. It was found that multi-layered magnetic core is useful to increase the Q value and L of thin film inductors in high frequency. The experimental inductor in which iron and copper loss are decreased by multi-layered core and thick coil shows L= 120 nH, Q= 18 at 50 MHz in its size of 0.5 mm×2.5 mm×35μm

New type micro cloth-inductor and transformer with thin amorphous wires and multi-thin coils

Abstract: The authors report miniaturization along with high resonant frequency and high quality factor in a wide frequency range of a cloth-inductor and high coupling coefficient and current capacity in a cloth-transformer. To reduce the eddy current loss of the magnetic core, ultrathin amorphous wires are made by chemical etching. These wires are bounded by multithin exciting copper wires 15-50 mu m in diameter. The number of cores and windings of coils are varied in the range of 3 to 5 and 7 to 30, respectively. A piece of core is a bundle of 100 or 400 Co-base amorphous wires 30 mu m and 5 mu m in diameter, respectively. The cloth-inductor with three cores is a bundle of 400 amorphous wires 5 mu m in diameter, and the coil is a bundle of six copper wires 20 mu m in diameter, showing an inductance of 1.2 mu H. The Q is higher than 20 in the frequency range from 1 to 20 MHz. The maximum Q is 40 at 5 MHz. These multithin coil inductor are easily modified to make a transformer. The coupling coefficient and current capacity are 0.95 at 8 MHz and 190 mA, respectively. >

Variable reluctance sensor for electromagnetically sensing the rate of movement of an object

Abstract: A variable reluctance sensor is disclosed as adapted for sensing the rate of revolution of a toothed wheel of magnetic material. The sensor has at least two magnets disposed side by side. One of the magnet has a first pole (e.g. S pole) disposed opposite the toothed wheel, and the other magnet has a second pole (e.g. N pole) disposed opposite the toothed wheel. The second pole of the first mentioned magnet and the first pole of the second magnet are both held against a magnetic core around which a coil is wound. As the teeth of the magnetic wheel successively travel past the magnets, they create magnetic fluxes oriented in opposite directions, which counteract each other in the core. Consequently, the total magnetic flux in the magnetic member varies more greatly than heretofore depending upon whether each magnet is opposed to any one tooth, or to the space between any two neighboring teeth, of the magnetic wheel. Such great variations in magnetic flux are translated into a correspondingly large amplitude signal as by the coil around the core.

Magnetic head for stable pole tip to tape contact pressure despite head wear and tape tension variation

Abstract: A magnetic head which contacts the magnetic tape (11) comprises a ferromagnetic body (12). A recess (26) is provided in this ferromagnetic body (12). A ferromagnetic core (9) has pole tips (9a,9b) which are located in the recess and which are arranged for contact with the magnetic tape. A non-magnetic material (18,20,21,22) is arranged along each side of the magnetic core pole tips in the recess. Relative hardnesses of the ferromagnetic body, ferromagnetic core pole tips, and non-magnetic material are chosen so that as the tape (11) wears away on contact surfaces of the magnetic core pole tips, non-magnetic material, and ferromagnetic body, the core pole tips (9a,9b) protrude relative to adjacent portions of the ferromagnetic body and the non-magnetic material so that the tape rides on the protruding pole tips of the core. A radius of curvature at the contact surface of the magnetic core pole tips prior to wearing of the pole tips is chosen such that it is smaller than a natural radius of bending of the tape.