Showing papers on "Magnetic core published in 1978"

High power density brushless dc motor

Abstract: A multiple disk, pancake, self-fed brushless dc motor characterized by high power density has a variable number of interleaved, axially spaced rotor and stator disks. The annular rotor disks are made of high coercive force permanent magnets such as cobalt-samarium and ferrites which do not demagnetize easily. The annular stator disks are yokeless and include a spirally wound laminated magnetic core made of steel strip or amorphous metal ribbon with opposing sets of stator slots and windings on both sides of the core. The permanent magnet machine can be operated as a generator.

Treatment of amorphous magnetic alloys to produce a wide range of magnetic properties

Abstract: Amorphous magnetic metal alloys are processed by annealing at temperatures sufficient to achieve stress relief and cooling in directed magnetic fields or in zero magnetic fields. The ac and dc properties of magnetic cores produced in accordance with the processes of the invention may be tailored to match those of a wide range of magnetic alloys. Alloys processed in accordance with the invention provide improved performance in inductors, transformers, magnetometers, and electrodeless lamps.

Analysis of the efficiency and inductance of multiturn thin film magnetic recording head

Abstract: Expressions for the flux in a multiturn thin film head are derived and used to obtain equations for the efficiency and inductance as a function of film structure and permeabilities.

Variable leakage transformer

Abstract: A variable leakage transformer or a variable voltage transformer comprising a magnetic core with a main-magnetic path and a sub-magnetic path, the main magnetic path having at least a common magnetic path with the submagnetic path, a primary winding wound on said common magnetic path of the core, a secondary winding wound on said main magnetic path of the core, means for controlling the magnetic flux in said sub-magnetic path, and said main-magnetic path having a thin air gap. By controlling the magnetic flux in the sub-magnetic path, the leakage of the flux induced by the primary winding from the main-magnetic path to the sub-magnetic path can be controlled. Thus the coupling between the primary and secondary windings, and conduction period in each cycle of the AC output voltage are controlled. The control of the conduction period in each cycle provides the control of the power transmitted from the primary winding to the secondary winding. Because of the presence of the air gap provided in the main-magnetic path, excellent control of the output voltage is obtained even when a load is small.

Inductive device having orthogonal windings

Abstract: An inductive device comprising a magnetic core and windings for producing two or three substantially orthogonal magnetic fields at all points within the core The device may be utilized as an inductor or transformer in a variety of applications

Comparisons of high frequency magnetic core losses under two different driving conditions: A sinusoidal voltage and a square-wave voltage

Abstract: It is observed that for the same peak flux density and the same operating frequency, the core loss induced by a square-wave voltage drive is less than the loss induced by a sinusoidal voltage drive, which is contrary to what one would normally anticipate. To the best of the author's knowledge, there Is no theory that predicts the loss difference observed.

Transformer with parallel magnetic circuits of unequal mean lengths and loss characteristics

Abstract: An electrical transformer having an electrical winding and a magnetic core having two parallel magnetic circuits having unequal mean lengths. The shorter of the parallel magnetic circuits is constructed of a magnetic material which exhibits a lower loss characteristic than the magnetic material used in the longer of the parallel magnetic circuits, at like levels of induction.

Welding transformer with drooping voltage-current characteristics

Abstract: A welding transformer with drooping voltage-current characteristic comprising a split magnetic core wound from transformer plate, and separated primary and secondary windings. In the core window, a moving shunt of the magnetic flux is provided between the secondary and primary windings. Where the magnetic flux passes from the core into the magnetic flux shunt, the core is provided with spacing blocks made from transformer plate. Laminations of these spacing blocks are so arranged in relation to the core plate that the magnetic flux does not cross the plane of the core plates but flows towards the magnetic shunt.

Reflective coating for external core electrodeless fluorescent lamp

Abstract: The header and tunnel of an external core, solenoidal electric field, fluorescent lamp are coated with a thin ultraviolet light-reflective layer; for example, aluminum or magnesium oxide. Radiative heat transfer from the lamp plasma to the magnetic core is thus reduced to permit high operating power levels and good lumen maintenance.

Protective circuit for a switching regulator

Abstract: A protective circuit for a switching regulator includes a DC voltage source having a pair of terminals, a transformer having primary, secondary windings and a magnetic core, a switching transistor having first, second and third electrodes, a circuit for connecting the second and third electrodes between the pair of terminals through the primary winding, a DC output circuit connected across the secondary winding to produce a DC signal in response to the ON/OFF operation of the switching transistor, a control circuit connected to the first electrode of the switching transistor so as to ON/OFF-control the switching transistor in response to the DC signal, a detecting circuit for detecting an over-current flowing through the primary winding of the transformer and for producing a control signal in accordance with a change of the saturated magnetic flux density of the magnetic core when the temperature thereof is increased to a predetermined value, and a protective circuit for stopping the ON/OFF operation of the switching transistor in response to the control signal from the detecting circuit.

Variable Microelectronic Inductors

Abstract: A thin-film microelectronic inductor is proposed. It is suitable for use in the frequency range from 5 to 20 MHz. The inductor is in the shape of a square spiral and is surrounded by patterned permalloy thin films. The pattern allows these films to be driven in their easy axes of magnetization by the high-frequency signal current. In the presence of a small dc magnetic field applied in the hard direction and equal to the anisotropy field, the resulting permeability is very high, and thus the inductance of the pattern is greatly increased. Since the inductance is a function of the dc magnetic field applied in the hard direction, variable inductors and tunable planar resonant circuits are readily implemented using the proposed device. The design considerations of the device are described, and the significance of the theoretical results is discussed. Experimental work is being carried out to verify the above results.

Harmonic losses in a three phase transformer core

Abstract: The iron loss of laminated cores is always greater than the nominal loss of the steel as measured in an Epstein Square or single strip tester. The extra loss is due to a number of factors. Flux harmonics have been measured locally in individual laminations of grain-oriented silicon-iron in a 3 phase transformer core and the loss associated with the harmonic components has been estimated. For the experimental core used, the loss associated with the harmonics in the yokes and limbs was 15% of the total loss, and corner loss accounted for 17% of the total. The calculated loss in the core accounted for over 80% of the measured loss, the difference being due to the effect of mechanical stress and also the errors in estimating the losses.

Electrodeless fluorescent lamp with reduced spurious electromagnetic radiation

Abstract: Spurious electromagnetic radiation from an electrodeless fluorescent lamp having a phosphor-coated, globular glass envelope containing an ionizable gas surrounding at least a portion of a toroidal magnetic core is reduced by situating a conductive loop about the envelope such that the loop and core planes are normal to each other. The loop also acts as the harp for a lampshade. Radio frequency energy, coupled into the gas from the core to ionize and excite the gas to emit ultraviolet radiation and thus stimulate visible radiation from the phosphor, also radiates from the lamp. The loop, driven by the radiated radio frequency energy, creates an opposing electromagnetic field. Cancellation of the radiated radio frequency energy thus tends to occur at a distance from the lamp, sharply reducing electromagnetic interference from the lamp.

Modulated AC ignition system

Abstract: An ignition system includes an alternating current power source which feeds a transformer having a primary winding, the primary winding being coupled to an electronic switch. The electronic switch intermittently interrupts current flowing in the primary winding and in the output circuit of the power source. Such electronic switch is made operable by virtue of the peak excursions of the alternating current thus supplying the necessary collector or emitter potential, depending upon the manner in which the electronic switch is connected, for the entire igniter firing cycle. A capacitor in series with the output circuit of the power source and with the primary winding enables current to be transferred out of the power source to such primary winding. Such electronic switch also provides discrete separation between successive output waveforms of successive ignition firing cycles. The system employs a temporary change accumulator inductor in the output circuit in series with the primary winding. Such charge accumulator inductor is an alternative fix for the deficiencies in the output transformer core of the alternating current power source conventionally used by transformer manufacturers for such power souces, so that when an appropriate magnetic core is utilized the output winding of the output transformer will provide sufficient temporary charge storage to obviate the need of such charge accumulator inductor.

Method for forming a magnetic core for a linear compressor

Abstract: A method for forming a magnetic core for the magnetic circuit of a linear-motor compressor suitable for use in a refrigerant system. The compressor includes a conical armature which reciprocates in a complementary air-gap under the influence of an electromagnetic circuit and a pair of linear complementary return springs connected to the armature between the compressor piston and outboard bearing. The electromagnetic circuit includes a pair of abutting convoluted loops of spirally wound magnetic strip material with a conical air-gap fabricated in the area of abutment. The magnetic core is formed by forming a pair of stacks of magnetic strips having diverse lengths, bending each stack to form a generally C-shaped core section having a generally semi-circular air-gap space defined by the ends of the strips, fastening the C-shaped stacks in opposed abutment to form a generally cylindrical air-gap, and then machining the air-gap into the desired conical shape.

Production of magnetic fields in megagauss region and related measuring techniques

Abstract: Using the "Cnare effect" or the electromagnetic compression of magnetic flux with a metal liner, very high magnetic fields up to 2.8 MG (or 280 T) have been successfully produced in a pulse form with a rise time of several μs. Observation of a motion of the liner and a process of field generation were in good agreement with computer simulation. Measurement of field intensity was performed by integrating a pulse signal induced in a few turn pickup coil and also by observing Faraday rotation for CdS crystal. Direct measurement of magnetization was performed in submegagauss region by integrating a voltage induced in a search coil by means of a cascade integrator, which ensures a high fidelity amplification. In megagauss region, where B \gg I , magnetization process was observed by measuring reversible susceptibility by a high-frequency pulse technique. Some magnetooptical observation is also described. Significance of megagauss fields in solid state physics is discussed. A future project aiming the production of 10 MG (or 1000 T) is also discussed.

A new high permeability grain oriented Fe-3%Si steel

Abstract: The metallurgy of a new high permeability magnetic steel with Goss texture is shortly described. Some details are given on the magnetic properties obtained and on the magnetic losses measured in transformers built with this steel.

A new bridge-connected magnetic circuit using amorphous magnetic core and its applications

Abstract: This paper is a description of the operating principle and the circuit configuration of a new bridge-connected magnetic circuit proposed by the authors. This magnetic circuit is constructed by a toroidal amorphous magnetic core with high permeability and a usual magnetic core with low permeability and has a number of excellent characteristics in the operation. Using this circuit the authors made various interesting devices used as the instrument and the control.

Hook shaped magnetic pole generator

Abstract: PURPOSE: To reduce magnetic flux leaked between magnetic poles with an adhesive containing hard magnetic material filled between the poles and a space formed by the pole and a field coil to fasten thereof. CONSTITUTION: A thermosetting adhesive 15 containing powdered ferrite or the like is filled into a space 13 between hook-shaped magnetic poles 4 forming a main magnetic circuit of leaked magnetic flux and a space 14 formed by the poles and a field coil 5 and olidified by heating. In the hard magnetic material power, magnetism is generated by flowing current through the field coil 5 in the opposite direction of the normal field current. With such an arrangement, the magnetic material is magnetized in the direction as indicated by H1 and H2. This works so as to offset the leaked magnetic fluxes ϕ1 and ϕ2 whereby the leakage thereof can be reduced. COPYRIGHT: (C)1979,JPO&Japio

Magnetic core formed from laminations

Abstract: A method of bonding laminations of a magnetic core is disclosed in which photo-resist material consisting of a co-polymer is applied as a film to a sheet of magnetic material to define lamination shapes to enable the laminations to be formed by etching. The film of photo-resist material on the laminations is then utilized to bond the laminations together in a stack. In order to permit the core to operate at temperatures higher than the softening temperature of the photo-resist material, the bonded stack is irradiated to cause changes to the bonding material such that the material does not soften at the operating temperature of the core.

Method of making pressed magnetic core components

Abstract: A method of making pressed magnetic core components having a low core loss property for use in electrical apparatus characterized by reannealing and repressing said components after initial annealing and pressing.

Prevention device of electric shock

Abstract: PURPOSE:To form not to current in a human body, even though the human body would touch a box body, by forming multiple layered insulating structure that a metal body and a insulating body are piled on in the insulation of the secondary winding and the iron core of a boosting transformer, and at the same time, short-circuiting the metal body to the box body.

High speed generator

Abstract: PURPOSE: To maintain the output voltage of a high speed generator constant by providing a control widning for exciting an iron core in one direction along the circumferential direction between the slot and the outer periphery of the stator side iron core of the generator having a permanent magnet rotor. CONSTITUTION: A stator side iron core 6 formed with slots 7 is provided on the inner periphery oppositely to a rotor having rotating field poles 5 of permanent magnet. There are inserted a control winding 10 for exciting an iron core 6 in predetermined direction b along the circumferential direction into the upper layer of a slot 7 and an armature winding 8 into the lower layer thereof. When the rotating field poles 5 are for example, formed by four poles, the magnetic flux produced by the magnetomotive force of the winding 10 is increased with respect to the two poles of the field poles 5 and decrease with respect to the other two poles thereof. Since the increase output voltage by the increase of the flux is larger in magnitude than the decreased output voltage by the decrease of the flux by the affection of the magnetic saturation of the core, the winding 10 is energized to control to lower saturation of the core, the winding 10 is energized to control to lower the output the output voltage so as to maintain the output voltage constant. COPYRIGHT: (C)1980,JPO&Japio

Magnetic modulator for magnetic field detection differentially outputting magnetic core noise

Abstract: A magnetic modulator for detection of a very small magnetic field and current, comprising a rectangular or annular one-piece magnetic core divided into a plurality of core legs which are adapted to be provided with exciting inputs in opposite directions to each other and with signal inputs in parallel thereto, and detecting coils wound around each leg so as to function differentially with respect to the core noise and the exciting input and cumulatively with respect to the signal input, thereby adequately reducing the core noise and well improving the signal-noise ratio.

Robust polyphase transformer

Abstract: A polyphase sector type transformer includes one magnetic core ring per phase, each of which has two rectilinear sides which are adjacent to each other. Each rectilinear side of one magnetic core ring is disposed contiguously with one of the rectilinear sides of an adjacent core ring whereby each magnetic core ring occupies a sector of the magnetic circuit of the transformer. Each pair of contiguous rectilinear sides is threaded through a coil of the transformer said coils comprising a high tension winding of trapezoidal cross-section and a low tension winding of rectangular cross-section. Each magnetic core ring is symmetrical about the plane of symmetry of the two coils which it threads; comprises an assembly of two generally arcuate parts arranged to facilitate threading of the coils on the rectilinear sides before the said core parts are joined by adhesive, the parts being separated along a plane perpendicular to the said plane of symmetry by sawing and; is made of a binder-impregnated, laminar stack of magnetic sheets of at least two different widths such that two contiguous rectilinear sides of two adjacent cores threading a single coil combine to give a magnetic circuit within the coil having a right cross-section which includes steps at the changes from one thickness of sheet to another and thereby forms a closer approximation to an ellipse than would a rectangular made from magnetic sheets all of the same width.

Electrical inductive apparatus having non-magnetic flux shields

Abstract: The electrical inductive apparatus including non-magnetic flux shields constructed of strips of highly electrically conductive material which are arranged to form a continuous loop around the core window. The shields are disposed parallel to the laminations of the magnetic core and adjacent the top and bottom surfaces of the core. Current induced in the shields by the leakage flux from the windings produces an opposing flux which prevents substantially all of the winding leakage flux from entering the magnetic core.

Self-excited inverter with suppressed current spikes

Abstract: A free-running inverter preventing excessive current spikes comprises a transformer and a switch means for alternately connecting, and then disconnecting, a DC voltage to a transformer primary winding which encloses a parallel combination of a saturating magnetic core and a non-saturating magnetic core. A transformer feedback winding enclosing only the saturating core drives the switch means during and between switch states. Switching between states is accomplished prior to saturation of the composite core.

Magnetic field impressing device

Abstract: PURPOSE: To make it possible to measure a magnetic member having a high magnetic reserving power without cutting a test piece by arranging two pairs of magnets in a manner to face one another so that a magnetic field may be established in their intermediate region and by forming a portion of an iron core with a slit. CONSTITUTION: The core 1 of an electromagnet is formed at its portion with a slit 6, and such electromagnets are paired and arranged such that the same polarities face each other. An energizing coil 5 is arranged in a vertically symmetrical position. A laser beam or an incandescent light 12 is made to illuminate a test piece 12 through the slit 6 so that the mehaviour of the test piece 4 is measured from a relatively weaker magnetic field to a strong magnetic field with the use of the color or Farady effects. The magnetic flux from the N pole toward the S pole is horizontally uniform at the facing intermediate regions. Thus, the magneticity of a magnetic disk or the like can be beasured continuously without any breakage. COPYRIGHT: (C)1979,JPO&Japio

Stress-relieved amorphous metal toroid-shaped magnetic core

Abstract: An improved magnetic core of an amorphous metal alloy is provided for electrodeless fluorescent lamps.