Showing papers on "Magnetic circuit published in 1981"

Novel hybrid electric vehicle

Abstract: By utilizing, in a hybrid (electrical-heat engine) vehicle an alternator which is totally free of elemental iron in its magnetic circuit, the alternator (with appropriate rectification means) can be connected, selectively, in series, parallel or in lieu of the storage battery pack for activating the electrical motor which drives the wheels of the vehicle or any other load mechanically coupled to the electrical motor. Quick surges of power can thus be delivered to the load to achieve, for example, rapid acceleration of a vehicle.

Desegmentation Method for Analysis of Two-Dimensional Microwave Circuits

Abstract: A new method for the analysis of two-dimensional planar circuits called the "desegmentation" method is proposed. This method is applicable to configurations which can be converted into regular shapes (for which Green's functions are known) by adding one or more regular shaped segments to them. Two examples of planar circuits, chosen such that the results could be verified by the previously known segmentation technique, illustrate the validity of the method.

Coupling losses in finite length of superconducting cables and in long cables partially in magnetic field

Abstract: The coupling losses between strands in cables of LCT conductor type in changing transverse magnetic fields were calculated for two situations envisaged in a. c. loss measurements: a) magnetic field applied on finite length of an infinite cable (infinite as well as finite short circuited cables were considered); b) finite length of cable in spatially independent magnetic field. It is found that in the first case the losses per length are enhanced considerably above loss generation e. g. in a magnet. If one cabling length l o is exposed to the field, the losses are enhanced by a factor about 2. This factor decreases only very slowly towards 1, if the field region increases. The results are explained by considering short circuited cables of different length with one cabling length in applied magnetic field. On the other side, the coupling losses of a finite piece of cable with length l \geq l_{o} are close to those in an infinite cable in magnetlc fleld, being identical with them for l = nl o (n-integer). The results for both cases mentioned above are discussed in the view of different loss measurement arrengements for cables.

Direct current motor

Abstract: A direct current motor comprising a field magnet provided with 2 mn magnetic poles which are magnetized with the same angular intervals as those of the magnetic poles N and S, where m is an integer of 1 or more, and n is an integer of 3 or more; a magnetic member for closing the magnetic circuit of the magnetic poles of the field magnet; an armature in which m(2n±1) armature coils are arranged with an equal pitch, the armature being directed towards the magnetic poles in the magnetic circuit; electric power supply control device capable of performing the switching of armature current 2 mn (2n±1) times per revolution of the armature; and a rotating shaft for rotatably supporting the armature and one of the magnetic poles, the rotating shaft supported by a bearing disposed in an outer casing of the direct current motor.

Relationship among eddy current loss, frequency, maximum flux density and a new parameter concerning the number of domain walls in polycrystalline and amorphous soft magnetic materials

Abstract: A new approach is presented for understanding the frequency and flux density dependence of eddy current losses in polycrystalline and amorphous soft magnetic materials by introducing an experimentally derived parameter which is thought to be proportional to the number of active domain walls. The relationship among eddy current loss, frequency, flux density and the new parameter is described by simple formulas and the result derived from these formulas agrees well with the Pry and Bean equation qualitatively and will offer an effective way to appreciate the mechanism governing eddy current loss.

Magnetic domains in thin-film recording heads as observed in the SEM by a lock-in technique

Abstract: In a thin-film magnetic recording head, a magnetic circuit made from two Permalloy thin films, one above the other, is magnetized by a spixally plated thin-film copper coil which is located (together with insulating layers) between those two films. The magnetic domains in a thin Permalloy film can be studied by type-2 magnetic constrast using backscattered electrons (BSE) in the scanning electron microscope (SEM) provided that the film has a smooth surface and is deposited on a flat substrate. In practice, the upper Permalloy film follows the contours of the underlying layers. This gives a topographic signal which is large enough to mask the type-2 magnetic contrast signal in its simple form. The domain walls can, however, be seen if the magnetic recording head is excited with a sinusoidal current and if the video waveform is processed with a lock-in amplifier referenced either to the fundamental or to the second harmonic of the excitation frequency. This lock-in image processing technique has now been applied to obtain images of the magnetic domains both from the upper Permalloy film of an incompletely fabricated head and also from the exposed cross sections of the Permalloy films in an operational thin-film head.

Push-button operated electrical power source for an optical communication link

Abstract: In the present invention, a novel magnetic circuit maximizes the electrical power generated upon manual actuation of a push-button switch while minimizing the required weight of the magnetic materials In particular, the magnetic circuit of the power supply of the present invention includes the following magnetic materials: an unmagnetized core (comprising iron) around which a coil is wound, the coil being connected to supply power to the transmitter; a permanent magnet (comprising iron having a permanent magnetic moment) mounted on a vibrating reed, at least one pole of the permanent magnet facing at least one end of the core Actuation of the push-button switch induces oscillatory motion of the reed and of the permanent magnet An advantage of this novel magnetic circuit is that, in at least one embodiment, the oscillatory motion of the permanent magnet causes a complete flux reversal through the coil during each cycle of the mechanical oscillation of the reed, a significant advantage

New M-H loop phenomena by locking ac electric core-current to the drive

Abstract: A method of control of magnetic flux, by using locked oscillators for the drive- and core-currents, is reported. Here, the same core-current wave-form is present in every cycle of the drive current.

Controlled flux contactor

Abstract: Apparatus disclosed for regulating a substantially constant magnetic flux level in an electromagnetic contactor. In one form a flux sensing device mounted in the contactor magnetic circuit provides a linear signal indicative of the level of magnetic flux in the contactor. A linear amplifier utilizes the flux signal to regulate contactor excitation to maintain flux at a desired value. In another form digital flux sensing device switches between first and second states as the level of magnetic flux varies between first and second values. A contactor excitation circuit "chops" the contactor excitation in response to the sensing device to thereby maintain magnetic flux at a value varying between the first and second values.

Contactor with flux sensor

Abstract: An electromagnetic contactor is provided with a flux sensing device, preferably a Hall effect sensor, mounted in its magnetic circuit. The magnetic circuit includes an air gap within which the flux sensing device is mounted. The air gap can be adjusted to control the percent of magnetic flux impinging on the flux sensing device whereby a signal can be taken from the device indicative of the magnitude of flux in the magnetic circuit. The signal can be used to control electrical excitation of the contactor at a predetermined flux level.

Pickup assembly for disc player

Abstract: A pickup assembly for a disc player includes a magnetic circuit for generating magnetic fluxes perpendicular to each other, a first coil group through which a current flows in a direction perpendicular to the magnetic fluxes, a second coil group through which a current flows in a direction perpendicular to one of the magnetic fluxes, a third coil group through which a current flows in a direction perpendicular to the other of the magnetic fluxes, a bobbin on which the first, second and third coil groups are wound, and a supporting member for supporting the bobbin so as to be movable in the three ways as along X-, Y- and Z axes.

Gas flow rate control system

Abstract: A gas flow rate control system designed to control the gas flow rate by continuously controlling the opening of an electromagnetic valve, wherein the magnetic hysteresis of a plunger and a yoke which are magnetic material forming the magnetic circuit is removed by alternately passing current pulses through two energizing coils, so as to continuously reverse the direction of magnetization of the magnetic circuit and wherein the static friction between the plunger and the yoke is removed by oscillating the plunger.

Integrated magnetic transducer

Abstract: A magnetic transducer for reading magnetic information from a magnetic support such as a disc or tape which moves before it, comprises a magnetic circuit formed of two thin layer polar pieces having a gap at one end and means coupled magnetically to the circuit for transformation of magnetic flux loss of information into an electric signal. The pole pieces comprise at the level of the gap a central part bounded by two lateral parts spaced such that the magnetic coupling between the central parts is very much less than the magnetic coupling between the corresponding lateral parts of the pieces. The gap disposed between the central parts is larger than the gap of the lateral parts. There is a substantial reduction in Barkhausen noise and parasitic edge effects over conventional transducer constructions which is obtained by making the thickness of the pole pieces of the transducer substantially greater in the area of the geometric path Lpm than at the lateral portions beyond Lpm.

Solenoid actuator for electromagnetic valve

Abstract: A solenoid actuator for use with an electromagnetic valve which includes a magnetic frame for establishing a magnetic circuit around an energizing coil, which is formed by bending a sheet-like magnetic frame constituent plate with an eddy current eliminating slit being defined therein, thereby enabling simplification in structure of the magnetic frame, effective utilization of electric power and reduction in the magnetic resistance, and attaining inexpensive fabrication, great electromagnetic force with electrical power-saving and small magnetic loss.

The Calculation of Magnetic Coupling from Overhead Transmission Lines

Abstract: Magnetic coupling to buried conductors, such as pipelines, on the right-of-way is a function of the transmission line's longitudinal electrical field (LEF) which is proportional to the phase current A rigorous solution for the LEF uses Carson's series and requires the use of a computer or programmable calculator

Speed detector for sewing machines

Abstract: A speed detector comprises a rotary shaft for rotation with a sewing machine, a ring-shaped permanent magnet uniformly magnetized in a direction parallel to the axis of the rotary shaft, at least one ring-shaped, internally toothed ferromagnetic member or stator and an externally toothed ferromagnetic circular member or rotor which is secured to the rotary shaft inside the stator to form a varying air gap between the opposing teeth. The permanent magnet and the two ferromagnetic members are disposed to form a closed loop magnetic circuit in which a ring-shaped coil is disposed. The air gap and hence the reluctance of the magnetic circuit changes periodically with the revolution of the rotary shaft so that a voltage is generated in the coil which varies at a frequency proportional to the operational speed of the sewing machine.

A new frequency modulator using ferrite orthogonal cores

Abstract: A new frequency modulator circuit is presented, which is a new application of small size orthogonal cores The circuit proposed here has a number of excellent operating characteristics and an extremely simplified construction The wide variable frequency range is obtained by a small input power Furthermore, large output voltage, high reliability, isolation characteristic, and low input impedance can be expected from this device The proposed circuit can be used as a power controlled device and a power telemeter The operation and circuit configuration of the new frequency modulator are described The flux behavior of the circuit under frequency modulated condition is examined

Particle beam instrumentation ion pump

Abstract: In particle beam optical instrumentation, an array of conventional sputter ion pump cells distributed in a ring shaped array about the circumference of the volume (optical column) to be pumped. An axially symmetrical, hollow, toroid magnetic circuit, formed by axially symmetrical magnets, either of the permanent type or of the electromagnetic type (or a combination of both), is used and the pumping action is outward from the central throughbore in the column so that the bore space could be occupied by other instrumentation. The magnetic circit may be used for particle beam focusing (optical lens) as well as for the pumping action by introducing magnetic gaps in either a series or parallel configuration.

Magnetic transducer comprising a gap of variable larger dimension for reading and writing data present on a magnetic carrier

Abstract: Transducer intended for read/write functions on a magnetic data carrier wherein the data is contained within a plurality of tracks The transducer includes a magnetic circuit formed by two pole pieces separated by a gap parallel to the carrier, having its larger dimensions perpendicular to the direction of travel of the data of a track and a winding coupled magnetically to this circuit The larger dimension of the gap varies depending on the nature of the function performed by the transducer At least one thin layer of magnetic material is deposited across the pole pieces at each outer edge thereof and spaced from each other The magnetic layers may be deposited in recesses formed in the pole pieces The pole pieces may be constricted and include thin magnetic layers deposited on the lateral surfaces to channel magnetic flux lines

Magnetic transducer for reading and/or recording of data contained on a magnetic carrier

Abstract: Transducer intended for read and/or write functions on a magnetic data carrier wherein the data is contained within a plurality of tracks. The transducer includes a magnetic circuit formed by two pole pieces separated by a gap parallel to the carrier, having its larger dimension perpendicular to the direction of travel of data on a track and a winding coupled magnetically to this circuit. The transducer is characterized in that it comprises means associated with the pole pieces situated at either side of the gap as seen in the direction of its larger dimension, for channelling the magnetic flux emitted by the immediate magnetic surroundings of the track of the carrier read by the transducer.

Current controlled variable reactor

Abstract: A variable reactor having main windings wound on one set of legs of a magnetic core and control windings mounted on another set of legs. The core provides common paths for the control flux resulting from the control windings and the main windings, but the magnetic circuit for the flux caused by the control windings does not include the legs on which the main windings are wound.

Dynamic Responses of DC Chopper-Controlled Series Motor

Abstract: This paper uses a computer-based piece-wise linear technique to analyze the dynamic performances of an armature voltage-controlled chopper circuit with a low-pass input filter taking the account of nonlinearities such as the magnetic saturation and the product of variable terms. The performances in the transient conditions which occur in practical situations are predicted by a computer model and are compared with the practical measurements.

Application of higher order boundary integral equations of two-dimensional magnetic head problems

Abstract: Two-dimensional boundary integral equations with sources having linear or quadratic variation over each element are introduced to analyze three different magnetic head configurations. 1) The harmonic response of a symmetric thin film head is computed and compared with earlier superposition theory. Also, the amplitude and phase of the harmonic response is deduced for a nonsymmetric thin film head. 2) The computed harmonic response of a shielded magneto-resistive head demonstrates that there is no true gap null (i.e., the response never goes through a zero) even if the head is symmetrically disposed between the shields. 3) The flux pattern of a conventional inductive head is mapped. It is shown that the output of a flux sensing loop just above the surface of the head can be used as a measure of head efficiency provided loop dimensions are small enough.

High energy overcurrent protective device

Abstract: Electrical loads connected to capacitance elements in high voltage direct current systems are protected from damage by capacitance discharge overcurrents by connecting between the capacitance element and the load, a longitudinal inductor comprising a bifilar winding wound about a magnetic core, which forms an incomplete magnetic circuit. A diode is connected across a portion of the bifilar winding which conducts a unidirectional current only. Energy discharged from the capacitance element is stored in the inductor and then dissipated in an L-R circuit including the diode and the coil winding. Multiple high voltage circuits having capacitance elements may be connected to loads through bifilar windings all wound about the aforementioned magnetic core.

Armature winding for a DC multi-pole motor

Abstract: This invention provides a DC multi-pole electrodynamic device, specifically a cup type DC multi-pole coreless motor having fixed field magnets, a magnetic material for closing the magnetic circuits of the field magnets, an armature composed of armature coils constructed of a plurality of loops, each having successive active armature portions adjacent to successive ones of said fixed magnetic field poles, respectively, the armature coils being formed by winding a conductor in substantially the same circumferential direction a predetermined number of times, the armature coils being formed by winding said conductor periodically in opposite axial directions with respect to magnetic poles without forming adjacent physically closed coils, the armature having coil taps equal to half the number of magnetic pole pieces, a commutator having commutator segments electrically connected to said coils, and a set of two fixed brushes.

A Practical Approach to Inclusion of Electromagnetic Field Nonlinearities in Dynamic Modeling of Large Turbogenerators-Part (I): Basic Principles for Inclusion of Instantaneous Magnetic Saturation

Abstract: This paper details the salient features of an approach to include the influence of magnetic field saturation, on an instantaneous basis in large turbogenerators, on the values of machine inductances. This is done by means of numerical analysis of two dimentional magnetic fields coupled with a concept of ampere turn drop functions. This method is applied to the determinationof dynamic characteristics of an existing 659 MVA 4-pole turbogenerator, including the instantaneous saturation effect on the inductances, and the effects of instantaneous rotor speed variation coupled with saturation on equivalent damping resistances. Details of this development are given in a set of three companion papers, of which this is Part (I)

Inductive displacement sensor with an air coil and a core plunging into the air coil, the in each case instantaneous length of engagement of which is to be sensed

Abstract: The invention relates to an inductive displacement sensor having two magnetic circuits which are largely decoupled from one another, of which a core controlling the in each case electromagnetically effective length of displacement determines the ratio of inductances of the magnetic circuits in at least one circuit and the ratio of inductances is preferably determined by measuring the frequency ratio between two oscillator frequencies, the inductances of the magnetic circuits in each case being connected, largely decoupled from one another, in a frequency determining manner in an oscillator. The sensor according to the invention senses in a directly integrating manner and the core to be sensed must not be tightly enclosed by the coil. The sensor is therefore particularly suitable for directly sensing floating bodies.

Ribbon type speaker and method of assembling magnetic circuit thereof

Abstract: An improved ribbon-type speaker having an independent magnetic circuit unit and vibration system assembly to thereby reduce second harmonic wave distortion and to provide a speaker which is easy to assemble and disassemble. The case of the magnetic circuit unit can be used as a jig in assembling the magnetic circuit thereby largely reducing the number of steps and the number of tools needed in assembly. The ribbon-type speaker further incorporates advantageously recess portions in a supporting frame of the vibration system assembly together with semicircular cut-out portions provided at both ends of long sides of the opening in the supporting frame. The rigidity of the vibrating plate is thus enhanced and the deformation and elongation of the damper member of the vibration system assembly is reduced.

A magnetic circuit analysis of the iron-cored homopolar linear synchronous motor

Abstract: An analysis of the iron-cored homopolar linear synchronous motor (LSM) is presented using tooth-by-tooth magnetic circuit theory and field dependent relative permeabilities. Sophisticated iterative procedures are used to obtain numerical solutions to the resulting set of simultaneous nonlinear equations. The analysis is validated by comparison between calculated and reported experimental tests results.