Showing papers on "Magnetic core published in 1976"

Magnetic inductively-coupled connector

Abstract: An electrical connector for applications where reliability and safety are needed uses transformer couplings made in two separable sections. Upon clamping together the surrounding metal housing halves, each inductively coupled pair of transformer windings is enclosed by the associated cup-type ferrite magnetic core to minimize undesired interference and result in good magnetic coupling.

Hysteresis models for system studies

Abstract: This paper presents a methodology for constructing high fidelity models of magnetic hysteresis that can be used in digital studies of network transients. An illustrative example is included.

Power inductor and transformer with low acoustic noise air gap

Abstract: A ferrite magnetic core includes a one-piece rectangular outer member with aligned circular apertures in which the ends of a cylindrical center member are retained to thus establish a radial air gap. Radial magnetic forces acting on the core members are summed to zero to theoretically eliminate movement and result in low acoustic noise in high operating frequency power inductors and transformers. A magnetic bridge is added to reduce air gap fringing flux outside the core. Other modifications and a "C" core configuration are described.

Method and apparatus for measuring the current flowing in a workpiece

Abstract: Magnetic cores of clamp-on type current measuring devices having a Hall-effect device for measurement of D.C. currents are provided with stabilizing coils which are periodically energized to substantially eliminate the characteristic hysteresis effect of the core material. A magnetic core of the type which is split to permit opening and subsequent clamping onto a conductor, has one section thereof provided with an air gap in which the Hall-effect device is positioned. A stabilizing coil is positioned on one section of the magnetic core and the coil and is periodically energized with a damped oscillatory current. This damped oscillatory current is at least applied immediately prior to the taking of any current measurement and is preferably applied periodically to maintain the stability of the magnetic core.

Thin film magnetic head with a center tap

Abstract: A narrow track width magnetic head can be formed using an integrated circuit formation techniques such as evaporation plating, chemical etching, etc. But, there has been such a problem that it is difficult to provide a center tap in a conventional thin film magnetic head structure including coils of four or more turns. A magnetic head according to the present invention comprising a coil divided into two sections by the center tap, the electrostatic capacitance of each section being substantially the same. The coil may be formed into a precise pattern with ease by photoetching technique. A plurality of sets of conductive films insulated from one another are provided crossing a magnetic core, each set consisting of two conductive films of the same pattern. The alternating layers of the conductive films are connected on the backward of a magnetic gap to provide the two sections of the coil. A center tap is derived from a connection portion of the two sections of the coil and a coil terminal is provided at each of the opposite free ends of the coil. Thus, the thin film magnetic head having a multi-turn coil with a center tap is provided.

Ferroresonant transformer structure

Abstract: A ferroresonant transformer includes a transformer core, primary and secondary windings A secondary core section of the transformer core is formed at least in part of a first magnetic material which saturates at a relatively small magnetizing force The remainder of the transformer core is formed of a second magnetic material which saturates at a magnetizing force greater than that of the first magnetic material The transformer also includes a ferroresonant capacitor which is responsive to the magnetic flux generated by current in the primary winding for generating a magnetic flux for saturating the secondary core

Current-limiting devices

Abstract: A current-limiting device for an alternating current system has for each phase a pair of saturable reactors each with an iron core, an alternating current winding and a superconducting direct current bias winding which is common to the reactor cores and biases them both to saturation. The two alternating current windings in each phase are connected in series opposition such that under fault conditions they are driven out of saturation on alternate half-cycles and thus limit the overload current. The superconducting winding has a surrounding magnetic flux screen which also forms a loop for shunting alternating current under fault conditions and which may be used as a direct current control circuit for varying the bias level. The screen serves as the outer vessel of an evacuated enclosure for the superconducting winding and a suppot system for the inner vessel is also described.

Electro-magnetic valve

Abstract: An electro-magnetic valve having a very fast response and a favorable temperature-gradient characteristic. The valve includes an iron core which carries a stationary magnetic winding within a valve housing, and a plunger coaxially oriented relative to the iron core and separated from the core by an air gap. The magnetic winding is made of a metal having a specific resistance greater than 20 milli-ohms per square millimeter of cross-sectional area per meter length at 20 degrees centigrade. The valve may also include a temperature compensating resistor connected in series with the magnetic winding. When used in an electronic fuel-injection system for an engine having an even number of cylinders, in which one of these valves is used for each cylinder, these valves can be electrically paired, with one valve of each pair connected in series with the other valve of that pair, and connected to a power source without requiring the use of a compensating resistor in series with the magnetic winding of each valve, due to the identical short response time of each valve.

Coil-system design for production of uniform magnetic fields

Abstract: A method is described for designing coil systems producing Chebyshev equal-ripple variation of the axial magnetic field. The off-axis fields of such systems are investigated, and they are found to have advantages over the usual systems for generating uniform fields when a field is required that is uniform within an ellipsoidal, rather than a spherical, volume.

Some experiments and considerations on the behavior of a new magnetic frequency tripler with bridge-connected reactor circuit

Abstract: Some magnetic frequency triplers using the saturation characteristics of an iron core have been reported. In this paper a new frequency tripler which is based on the bridge-connected reactor circuit is proposed. The features of this tripler are that an applied source is single phase and ferro-resonance circuits are formed in both the output and input side. Consequently, the circuit becomes very simple, the power factor is greatly improved and the triple frequency output voltage holds constant. This paper presents some experiments and considerations on a new tripler. Moreover, various circuits which have equivalent operating characteristics are proposed.

Dual-function magnetic structure for toroidal plasma devices

Abstract: This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring.

Self generating electrical pickup for musical instruments

Abstract: The following specification describes a self-generating electrical pickup to be applied to percussion type musical instruments with vibrating elements of steel or containing ferromagnetic material. The pickup is used in conjunction with an amplifier and loudspeaker to amplify the instrument sound. The pickup makes use of a plurality of pick off coils, one of each is used in proximity to each vibrating element of the musical instrument. Each pick off coil consists of a coil of many turns of fine wire within which is placed an iron core to which is bonded a ceramic permanent magnet. The large surface area of the ceramic magnet adjacent to the musical instrument vibrating element causes large magnetic flux changes in the coil and consequently a large signal voltage which is amplified to drive the loudspeaker. The large signal available, in this design, reduces the effect of 60 Hz hum induced by stray electromagnetic fields. The use of a ceramic magnet provides for a cost effective design. In this design, the plane surface of the ceramic magnet is placed in proximity to the surface of the vibrating element. The length of the iron core, to which the ceramic magnet is attached, exceeds the length of ceramic magnet and said longer iron core acts to extend the magnetic flux into the long solenoidal coil of copper wire, thus allowing for large induced electrical signals when the ceramic magnet surface is adjacent to the vibrating element.

A theory of eddy current limited heads

Abstract: Many video recording heads are fabricated from electrically conductive, magnetic alloys and are operated at frequencies where the skin depth is small compared with head dimensions. We present a novel theory wherein it is assumed that flux flows only in a skin layer which covers all the surfaces of the head. The gap regions are treated as magnetic transmission lines. Computations of the head inductance compare well with experiment. This model is simple enough to be readily applied to the design of other heads made from conductive materials.

Recent advances in the design of large magnetic frequency changers

Abstract: The design of the magnetic frequency changer, or multiductor, has advanced to the extent that units having a rating of 6.6 MW have recently been designed and built. This paper treats several of the problems and consequent solutions encountered in the design of these large units. Specifically, problems associated with the effective utilization of available conductor in a sheet wound coil are discussed, and methods of reducing the losses to acceptable levels are described. It is shown that excessive losses can occur when the winding geometry is improperly chosen. Secondly, methods of estimating the core losses at the high and distorted flux densities encountered in the frequency changer are described. The load dependent core losses are required when determining the efficiency of the device as well as in assessing the overall system stability. Finally, an efficient method of simulating the behaviour of the multiductor on load is outlined. The simulation includes the input filter network, line characteristics, losses, etc. It is such that sets of design curves or alternatively, specific design configurations, can each be treated with ease and economy.

Flexibility and economics of implementation of the finite element and difference techniques in nonlinear magnetic fields of power devices

Abstract: This paper presents a comparison between the finite element and difference methods applied to two dimensional nonlinear magnetic field problems. The comparison is based on the determination of the magnetic field distribution in a shell-type single phase transformer with substantial magnetic core saturation. The comparison between the two discretization schemes is based on an equal number of finite element and finite difference domains. The finite element mesh is superimposed on the finite difference grid, to assure an equitable basis of comparison. Aspects of flexibility of implementation and economics (computer execution time and storage requirements) for the two techniques are compared. In addition, the degree of agreement between numerical results of the two methods and corresponding experimental test data is given.

Electromagnetic sonic generator for an alarm

Abstract: An electro-acoustic transducer of electromagnetic type is composed of an exciting part having a magnetic core wound with an exciting coil, a vibrating plate provided opposite to the magnetic core at an interval and a ferromagnetic thin plate mounted to the vibrating plate. The thin plate is provided on the surface of the vibrating plate on the side of the magnetic core, so that the thin plate is not exposed to the open air. Furthermore, the thin plate is connected to the vibrating plate at plural points more than three or at a part with some area. Such connection restrains undesirable vibration of the thin plate.

Dynamo electric machine permanent magnet flux test apparatus which simulates actual flux conditions of the motor

Abstract: To test the flux of circular segmental permanent magnets for assembly in permanent magnet dynamo electric machines, typically electric motors, a gauge is made of soft iron having an inner segmentally circular soft iron core, on it a layer of non-magnetic material to simulate the air gap of the motor, space for the permanent magnet to be inserted, and a return soft iron yoke in magnetic circuit with the core. A measuring coil which is chorded is located on the gauge to sense the magnetic flux, and so placed on the core that it conforms, at least approximately, to the pitch angle of the armature winding of the dynamo electric machine with which the magnet is to be used. To simulate cross fields, a demagnetization widing can be placed in the space adjacent the layer of nonmagnetic material adjacent the ends of the space for the permanent magnets to be tested, or the core can be cut with grooves similar to the coil slots of the armature, with current being passed therethrough in a direction to simulate the armature cross field. The test apparatus can be combined with a magnetizing yoke carrying magnetization coils to magnetize the segments, test them, and then demagnetize the segments, and reversely magnetize them for test of uniformity. Magnetic sensors can be placed on the core to sense the localized flux distribution of the magnetized magnet elements.

Inductive displacement sensor

Abstract: A variable inductor having a U-shaped magnetic core with a short-circuiting plate providing a short-circuiting ring for both legs of the core movable along the core legs in response to a displacement to be measured is connected in an electronic circuit to generate oscillation of a frequency that is either directly or inversely proportional to the displacement. For the inversely proportional case, the variable inductance component can be combined with an integrator function and connected to an operational amplifier, for generation of the output frequency with a small number of electrical components. The thickness and spacing of the core legs are varied along their length to produce a highly linear inductive transducer characteristic. The core legs are bent in a circle when it is desired to measure an angular displacement.

High power and high speed linear motor

Abstract: An electric linear motor of the axial type comprising a fixed armature formed by an elongate rail of U-shaped cross section comprising magnetic and electrically conductive material, and a mobile, elongate inductor disposed between the arms of the U. The inductor comprises an elongate magnetic core of square cross section surrounded along its length by a plurality of successive, coaxial, electrically energizable coils without magnetic components interposed between the ends of adjacent coils. Between these ends are air gaps communicating with air passages extending through each coil for cooling air to be propelled therethrough.

Magnetic field probe which measures switching current of magnetic element at moment the element switches as measure of external field

Abstract: A probe for sensing the strength of the magnetic field that surrounds a current-carrying conductor has a square-loop magnetic material wrapped about a conductor which is placed in the magnetic field to be sensed. An alternating signal is applied to the conductor, of sufficient intensity to cause successive reversals of the polarity of the magnetic material. A sense winding around the magnetic material issues a switch signal every time the magnetic material reverses polarity. The switch signal is used to sample the alternating drive signal current in order to store the amplitude of the drive signal at the instant at which the magnetic material reverses polarity. The sampled signal amplitude is averaged over a period of time, and the resultant amplitude is a linear function of the strength of the magnetic field. A second conductor, magnetic material and sense winding are arranged in a position remote from the magnetic field in order to sense the effect of the Earth's magnetic field. The averaged output signal resulting from the measurement of the Earth's magnetic field is then subtracted from the averaged output signal derived from the measurement of the magnetic field that surrounds the current-carrying conductor. The difference signal is displayed as an indication of the current-produced magnetic intensity or the magnitude of the electric current which produces it.

Rotor of permanent magnet synchronous motor

Abstract: PURPOSE: To prevent a crack of a permanent magnet at a high speed ro tation time by inserting mounting plates composed of a magnetic material between interior and exterior surfaces of a permanent magnet and a rotor iron core in case of containing a permanent magnet within a rotor iron core. COPYRIGHT: (C)1978,JPO&Japio

Design of air-gapped magnetic-core inductors for superimposed direct and alternating currents

Abstract: Using data readily available from manufacturers on standard magnetic-material properties and standard core sizes for air gap type cores, an algorithm designed for a computer solution is developed which optimally determines the air gap length and locates the quiescent point on the normal magnetization curve so as to yield an inductor design with the minimum number of turns for a given ac voltage and frequency and with a given dc bias current superimposed in the same winding. Magnetic-material data used in the design are the normal magnetization curve and a family of incremental permeability curves. A second procedure, which requires a simpler set of calculations, starts from an assigned quiescent point on the normal magnetization curve and first screens candidate core sizes for suitability, then determines the required turns and air gap length.

Magnetic transducer head core manufacturing method

Abstract: A method for manufacturing a magnetic core for use in data transducing, characterized by having the depth of the shallower flux gap face precisely equal to a predetermined value. The method involves machining a notch in the flux gap face of one element at a precise distance from a reference surface before bonding of the two elements of the core together. The transducing surface can then be machined after assembly to an exact distance from the reference surface to automatically determine the desired flux gap depth.

Inserting device of coil into electric motor

Abstract: PURPOSE:Insertion of coil utilizing compression air in slot of soft iron core in a electric motor prevents damage on film of isolation membrane in conductor and short-circuiting between the layer of coil.

Inductor with plurality of magnet pieces in air gap

Abstract: There is provided a gap in a magnetic circuit of an iron core inductor, and a plurality of small size permanent magnet pieces are placed in the aforesaid gap, with the magnetizing directions thereof being provided in side-by-side relation. If the magnetizing direction of the permanent magnet pieces is opposed to that of a D.C. magnetic field which is produced in a magnetic circuit, yet in case D.C. and A.C. overlapping currents flow through the inductor, then the D.C. magnetic field produced in the magnetic circuit will be off-set thereby, providing a high inductance value, while eddy currents produced within the permanent magnet pieces due to the A.C. magnetic field will be reduced to a considerable amount, because the permanent magnet pieces are small in size, thus minimizing the heat to be produced in the permanent magnet pieces.

Electromagnetic brake or clutch - reduces stray magnetic flux with concentric coils with adjacent like poles

Abstract: The electro-magnetic brake or clutch carries a number of clutch plates (50) with teeth sliding in splines in the housing (49) and clutch plates (51) sliding in splines on the hub (53). The magnetic core (43) houses two concentric coils (57) and (58) with the electric current arranged to flow such that ajoining surfaces are of like polarity. This arrangement of the coils concentrates the magnetic flux wholly within the core (43) and keeper plate (54) and the space between core and keeper plate which is occupied by the clutch plates. The magnetisation of surrounding steel parts is avoided and a greater clutch torque or braking effort is achieved.

Direction responsive flux gate unit

Abstract: A flux gate unit for producing an output representing the directional orientation of the unit with respect to the horizontal component of the earth's magnetic field, and in which a saturable flux gate magnetic core structure is mounted for leveling movement relative to associated flux gate coil means, in a manner enabling maintenance of the core structure substantially continuously in level condition while avoiding the necessity for leveling movement of the flux gate coils, and thereby avoiding the necessity for connection of electrical leads to a movable part.

A new frequency multiplier made of a magnetic core with multiple holes

Abstract: This paper is a brief description of the operating principle and the circuit configuration of a new frequency multiplier This device uses a magnetic core of unusual shape having multiple holes An AC voltage of a frequency f Hz can easily be converted to a sine wave voltage at an optional multiplied frequency In addition, this device has a number of excellent operating characteristics

Design of air-gapped magnetic-core inductors for superimposed direct and alternating currents

Abstract: Using data readily available from manufacturers on standard magnetic-material properties and standard core sizes for air gap type cores, an algorithm designed for a computer solution is developed which optimally determines the air gap length and locates the quiescent point on the normal magnetization curve so as to yield an inductor design with the minimum number of turns for a given ac voltage and frequency and with a given dc bias current superimposed in the same winding. Magnetic-material data used in the design are the normal magnetization curve and a family of incremental permeability curves. A second procedure, which requires a simpler set of calculations, starts from an assigned quiescent point on the normal magnetization curve and first screens candidate core sizes for suitability, then determines the required turns and air gap length.

Electromagnetic communication method using open magnetic coupler

Abstract: PURPOSE:To employ electromagnetic coupler (open magnetic coupler) containing magnetic material with no selflclosed loop (open magnetic path element) as magnetic core, in electromagnetic communication.