Showing papers on "Magnetic core published in 2000"

Properties of a new soft magnetic material

Abstract: The development of advanced electromagnetic devices has been constrained by a lack of soft magnetic materials with a suitably high saturation magnetization (over 20 kilogauss) and a large permeability roll-off frequency (greater than 1 gigaherz). For example, magnetic hard-disk-drive technology is rapidly approaching the perceived superparamagnetic limit at which the stored bits become thermally unstable1 — disks with higher anisotropy are more stable but are not usable because magnetic write heads become saturated. Here we describe a new soft magnetic material with a saturation magnetization of 24 kilogauss and a large permeability of 1,000–1,400 in a wide frequency range of up to about 1.2 gigaherz. This new material promises to have wide application in devices such as magnetic recording heads and integrated inductors.

Mathematical Models for Current, Voltage, and Coupling Capacitor Voltage Transformers Working Group C-5 of the Systems Protection Subcommittee of the IEEE Power System Relaying Committee,

Abstract: This paper reviews a number of mathematical models used to represent the nonlinear behavior of the magnetic core of in- strument transformers. Models of instrument transformers using these core representations are presented. The transient response of the instrument transformer is compared to actual test results recorded in the laboratory. The paper provides practical guidelines as to which of the physical elements of instrument transformers are important to model during transient studies and which elements could be ignored without sacrificing the accuracy of the simulation results. The electromagnetic transients program (EMTP) data files used to generate the models are also provided in the appendix to help new EMTP users model instrument transformers for evalua- tion of high-speed protective relaying systems.

Mathematical models for current, voltage, and coupling capacitor voltage transformers

Abstract: This paper reviews a number of mathematical models used to represent the nonlinear behavior of the magnetic core of instrument transformers. Models of instrument transformers using these core representations are presented. The transient response of the instrument transformer is compared to actual test results recorded in the laboratory. The paper provides practical guidelines as to which of the physical elements of instrument transformers are important to model during transient studies and which elements could be ignored without sacrificing the accuracy of the simulation results. The electromagnetic transients program (EMTP) data files used to generate the models are also provided in the appendix to help new EMTP users model instrument transformers for evaluation of high-speed protective relaying systems.

Multi-phase and multi-module power supplies with balanced current between phases and modules

Abstract: A multi-phase power supply utilizes a current sensor including a sensor inductor winding connected in parallel with a filter inductor winding at the output of each phase for sensing the phase currents and balancing the current by adjusting the duty cycle of each phase through feedback control. In addition, in a multi-module power supply configuration, current between power supply modules is balanced through use of the same current sensor and current sharing technique. Each phase of the power supply includes at least one input power source and a current sensor. The sensor inductor winding and the filter inductor winding have the same number of turns and are wound about a magnetic core also present at each phase. A differential amplifier at each phase senses and amplifies any voltage difference between the outputs of the sensor inductor winding and the corresponding filter inductor winding. A current-sharing bus is formed between each of the phases, carrying the summed and averaged outputs from all the differential amplifiers. A feedback correction circuit at each phase utilizes the voltage on the current-sharing bus as a reference to control a pulse width modulator in adjusting the duty cycle of the corresponding phase, thereby balancing the load current among the phases. In a multi-module, multi-phase power supply, the current-sharing bus and a voltage-sharing bus are extended between each module and the phases of each module to achieve the same current balancing between all phases and modules.

Power electronic transformers for utility applications

Abstract: The concept of realizing a small size "solid-state" transformer has been discussed for some time. A fairly straightforward approach to accomplish size reduction in a transformer feeding a conventional rectifier-inverter system is to introduce an isolated DC-DC converter in the DC link, isolation being provided by a high frequency transformer. So also, several topologies that employ AC-AC converters connected on primary and secondary sides of a high frequency transformer to reduce the size and weight of the magnetic core have been reported in literature. Such AC-AC converters need switches with bi-directional voltage blocking and current carrying capability, which are commonly realized with pairs of gate turn-off devices such as insulated gate bipolar transistors (IGBT). This paper explores the possibilities of employing AC-AC switched mode power converters in combination with reactive elements to realize a chopped AC link, thereby decreasing the required magnetic core size for voltage transformation and isolation. A primary advantage of this approach is that, the static power converter needs only six devices to implement a three-phase electronic transformer, which makes it an economical solution. Operating principles, magnetic design and other practical issues are discussed. Detailed computer simulations accompanied with experimental verification are presented in the paper.

Permanent magnet dynamo-electric machine

Abstract: In order to realize a permanent magnet dynamo electric machine which permits a high speed of rotation, the permanent magnet dynamo electric machine includes a stator 20 having a stator iron core 22 in which a stator winding 24 is wound, and a rotor 30 facing the inner circumference of the stator 20 and rotatably supported thereby, the rotor 30 having a rotor iron core 32 and a plurality of permanent magnets 36 arranged inside the rotor iron core 32 so as to face the stator iron core 22, wherein the rotor iron core 32 is provided with the same number of permanent magnet insertion holes 34 as the number of permanent magnets 36 for receiving the same at positions where the ratio R1/R0 is equal to or more than 0.85, wherein R0 is the radius of the rotor 30 and R1 is the radius of an imaginary circle drawn by inscribing the faces of the plurality of permanent magnets 36 at the side remote from the stator 20.

Motor having stator with insulator of high heat-conductivity

Abstract: A motor has a stator formed by assembling stator members in an annular shape. The stator member includes a core segment formed of laminated electromagnetic steel sheets, an electrical insulator covering the core segment, and a coil wound on a tooth of the core segment via the insulator. At least parts of the insulator contacting the coil is made of highly heat-conductive insulating resin. A motor has a stator iron core formed of laminated electromagnetic steel sheets, and the motor includes a highly heat-conductive insulating sheet disposed on the laminated face of a slot of the stator iron core and a coil wound in a slot via the sheet. These structures allow the heat generated by the coil to travel to the core segment with ease, because of the resin or the sheet disposed between the core segment and the coil, thereby cooling the motor efficiently. As a result, a continuous output rating is improved, and a highly efficient motor with long service life, free from shortening its service life due to the heat, can be realized.

Printed circuit board integrated fluxgate sensor

Abstract: We have developed a cheap and simple trilayer printed circuit board (PCB)-based technology, adapted for the fabrication of fluxgate magnetic sensors. The two outer layers of the PCB stack comprise the electrical windings of the fluxgate, while the inner layer is made of patterned amorphous magnetic core with extremely high relative magnetic permeability (µr100,000). The output voltage and the sensitivity of the fluxgate devices have been studied as a function of the external field and of the geometry of the magnetic core. We have found a relatively high sensitivity of 18 V/T at an excitation current frequency of 10 kHz. The results obtained clearly show the potential of this miniaturised fluxgate device for application as a magnetic field sensor. Keywords: Fluxgate sensor; Sensitivity; High permeability; Compass; Vitrovac®; Printed circuit board (PCB)

Multi-layer transformer apparatus and method

Abstract: A multi-layer transformer includes a plurality of tapes having a magnetic core area disposed on at least one of the layers forming a magnetic core of the transformer. A primary winding is disposed on at least one of the layers. A secondary winding is disposed on at least one of the layers. A thin layer made of a lower permeability dielectric material is disposed proximate at least one of the windings. A first plurality of interconnecting vias connect the primary winding between the tapes. A second plurality of interconnecting vias connect the secondary winding between the tapes. Magnetic flux is induced to primarily flow into the core area. Magnetic coupling and dielectric breakdown between the windings are improved. A lower cost and smaller sized transformer can be obtained.

Tag for rfid

Abstract: PROBLEM TO BE SOLVED: To prevent an antenna coil from coming into contact with a things around it during the conveyance of an article by forming the antenna coil extremely thin. SOLUTION: An IC chip 13 fitted to the article 11 with different information unique to the article 11 stored in it and the antenna coil 14 fitted to the article 11 is electrically connected to the IC chip 13. The antenna coil 14 has a magnetic core member 14a which is formed of a magnetic material in a flat plate shape and a coil main body 14b which is wound spirally around the magnetic core member 14a on an axis extending in the plane of the magnetic core member 14a. The magnetic core member 14a is formed of a composite material of magnetic powder and plastic or a laminated material of amorphous foil and the IC chip 13 is adhered to the top surface of the magnetic core member 14a.

Multi-layer transformer having electrical connection in a magnetic core

Abstract: A method, apparatus, and article of manufacture for a multi-layer transformer (132) includes a plurality of layers (168-174) having a magnetic core area (114) disposed on each of the layers forming a magnetic core of the transformer having a primary winding (126, 128) disposed on at least one of the layers, and a secondary winding (178, 180) disposed on at least one of the layers A plurality of interconnecting vias (130) connect the primary winding between the layers, and a second plurality of interconnecting vias (130) connect the secondary winding between the layers The interconnecting vias are disposed proximate a center of the magnetic core of the transformer, thus, reducing the overall volume, size, weight, and cost of a transformer while meeting regulatory isolation safety requirements

Two-dimensional calculation of winding losses in transformers

Abstract: In this report, the two-dimensional calculation of the winding losses occurring in magnetic devices like chokes and transformers used in switch mode power supplies is presented. Based on the field distribution in the winding area including the fringing fields of the arbitrarily positioned air gaps, the skin and proximity losses in each turn are analytically calculated.

Method of fabricating a miniaturized integrated circuit inductor and transformer fabrication

Abstract: A method for fabricating inductors and transformers on integrated circuits. A magnetic material is formed on the semiconductor substrate. The magnetic material comprises a suspension of magnetic material in an insulator. A metal film is formed that forms at least one coil around the magnetic material forming an inductor structure. Two adjacent coils can be linked with the magnetic material to form a transformer.

Advanced model of laminated magnetic cores for two-dimensional field analysis

Abstract: A numerical model for the analysis of laminated ferromagnetic cores of electromechanical devices is presented. The model is based on the finite-element solution of the two-dimensional (2-D) electromagnetic field problem in the lamination plane; a dynamical relation between local magnetic flux density and magnetic field strength is obtained by solving for the one-dimensional (1-D) eddy-current field developed in the lamination depth. The hysteresis of the magnetic material is accounted for by the Preisach approach. The model is first validated by comparison with an alternative held formulation available for axis-symmetric structures; finally, an application to a more complex 2-D laminated core is presented and the numerical results are confirmed by comparison with measured waveforms of electrical and magnetic quantities.

Common mode choke coil

Abstract: A common mode choke coil is realized in which countermeasures against leakage flux are taken so as to reduce adverse effects on an external apparatus. Coils 291, 292 are wound around a toroidal magnetic core 22 and sandwich a partition plate 27 provided within an inner circumference of the magnetic core so as to cancel out respective magnetic fluxes produced by the coils relative to a normal mode current. A belt-like magnetic shield plate 24 is provided in a direction along leakage fluxes from the coils and attached closely to a substantially U-shaped insulating protection plate 23 having side walls 25, 25 and the insulating protection plate 23 is then detachably attached to a base 21 with catches 26 provided at both ends of the plate 23.

Improvement of T-joint part constructions in three-phase transformer cores by using direct loss analysis with E&S model

Abstract: This paper presents the effects of the joint method in the T-joint of three-phase transformer cores on iron losses. The effects of joints on the decrease of core loss have been analyzed by using FEM with E&S model, considering the hysteresis of vector magnetic properties. As a result, we can improve the T-joint part constructions to reduce iron losses in the three-phase transformer cores.

Integrated electroplated micromachined magnetic devices using low temperature fabrication processes

Abstract: Micromachining techniques are used to realize inductors and transformers integrated with a multichip package, allowing compact integration with chips, sensors, and other components. The processing steps chosen are all low-temperature, which allows the use of low cost substrates such as MCM-L compatible materials. A variety of micromachined inductors and transformers with different geometries and magnetic core materials are designed, fabricated, tested, and compared. Integrated permalloy and orthonol core inductors (15 /spl mu/m thick) with nominally identical geometries of 4 mm/spl times/1.0 mm/spl times/0.13 mm and 30 turns of multilevel copper coils (40 /spl mu/m thick) show differences in performance due to differences in core behavior. The permalloy core inductor has a slightly higher inductance, but it has much lower dc saturation current than the orthonol core inductor. The effect of insertion of a core air gap was also studied, Although inductors with no air gap having dimensions of 4 mm/spl times/4 mm/spl times/0.145 mm and 156 turns of multilevel electroplated copper coils (40 /spl mu/m thick) and electroplated permalloy magnetic core (35 /spl mu/m thick) have slightly higher inductance (about 1.5 /spl mu/H), air gap inductors have much higher saturation current (180=250 mA). These devices have high current capability (up to 3 A steady dc current) and are suitable for low power converter applications.

Measurements of mechanical vibrations at magnetic cores of power transformers with fiber-optic interferometric intrinsic sensor

Abstract: A fiber-optic interferometric sensor with intrinsic transducer along a length of the fiber is presented for vibration measurements of the magnetic core inside an oil-filled power transformer. The sensor is designed for high sensitivity measurements into the harsh environment of electromagnetic fields, wide temperature change, and in oil immersing. This sensor allows enough sensitivity for the application, for which vibrations amplitudes are due to submicron displacements at frequencies of 100 Hz and its harmonics, in addition, the accessibility to the sensing region is guaranteed by low size immune fiber-optic cables as well as optical phase-based transducer/carrier of the sensor output. Thus, it is ideal for the requirements of the remote operation. The transducer size is a few mm in length, and is compact and rugged. Our results show that the vibrations of the elements constituting a power transformer are directly measured, improving the indirect techniques actually available. Finally, the measurements inside a medium power transformer at site are obtained for its application in electric plants.

A universal electromagnetic microactuator using magnetic interconnection concepts

Abstract: This paper describes a new universal electromagnetic microactuator that makes use of novel magnetic interconnection concepts. In order to realize the universal actuator, planar microinductors are fabricated on a substrate which already contains anisotropically etched Ni/Fe permalloy-electroplated magnetic vias or through-holes. The inductor, which acts as a flux generator, is physically located on one side of the wafer, but is magnetically connected to the opposite side of the wafer where actuation occurs. This approach to actuator design provides for maximum flexibility in the range of applications. In addition, it allows the actuator to be readily connected to driving circuitry without interfering with the actuating device. Multi-layer 3D inductive components are fabricated using a LIGA-like thick photoresist lithography process. The fabricated coils consist of a horseshoe-shaped permalloy-electroplated magnetic core and electroplated copper conductor lines that form the windings around the core. Initial testing using a prototype cantilever beam structure has proven functionality and indicates that the new device has much potential as a low power magnetic microactuator. Many magnetic MEMS applications require an electromagnetic actuator with high efficiency, and some areas which this device is expected to impact include microfluidics, micromotors, optics, and resonating devices.

Fabricated components of transverse flux electric motors

Abstract: Transverse flux electric motors are made using a unique process where individual components are premade and then assembled together. A stator portion is made by nesting a coil between two stator core portions. The stator core portions are made from laminations or sintered powder materials. A separate rotor portion is provided with a core and two permanent magnets that interact with projections on the stator core portions. In one example, the stator includes support members that support additional magnetic core portions to magnify the magnet flux density in the air gap between the stator and the rotor.

Magnetic field analysis of stator core end region of large turbogenerators

Abstract: In order to estimate the losses and temperature rise at the end of electrical machines, it is important to clarify electromagnetic behavior in the core end region. In this paper, the method of evaluating the leakage flux of the stator end region of large turbogenerators, combining three-dimensional magnetic field analysis and phasor diagram analysis of the end leakage flux is described. Moreover, the result of applying this method to a 60 Hz-1000 MW turbogenerator is also described.

High inductance planar transformers

Abstract: We have developed a new printed circuit board PCB technology adapted for the fabrication of ultra-flat microtransformers. The two outer layers of the PCB stack comprise the electrical windings of the inductive devices, while the inner layer is made of a micro-patterned . amorphous magnetic ribbon with extremely high relative magnetic permeability m f 100,000 . The electrical properties of the toroidal r microtransformers have been studied as a function of frequency. Inductances were found to be as much as 30 mH at 1 kHz, a relatively high value compared to microtransformers of similar size. Despite a relatively high leakage flux, the voltage transformation efficiency is measured at 89%. The high performance of these devices is primarily due to the use of the high permeability magnetic core. q 2000 Elsevier Science S.A. All rights reserved.

Ignition device for internal combustion engine

Abstract: PROBLEM TO BE SOLVED: To provide an ignition device for an internal combustion engine, which not only prevents shorting between winding layers by insulating resin which is filled, easily permeating to the central part of a secondary coil, but also effectively prevents expanding of a separating wall caused by the secondary coil which is wound. SOLUTION: Separating walls 24a and 24b are provided on an outer surface of a bobbin cylinder part 23 of a bobbin 22, and a primary coil 15 and a second coil 16 are provided in each space separated by each separating wall 24a and 24b. Rib projecting parts 27 which expand to the outsides of axial directions are formed at four positions, avoiding cross iron core parts 30 and 31 in a separating wall part 24b of the outside of axis core direction of the bobbin 22, which separates the secondary coil part 16, toward the bobbin cylinder 23 from the outer peripheral. The cross iron cores 30 and 31 are so equipped as to attach the bobbin 22 sandwiched between both upper and lower sides, are provided in a case unit 13 under this condition and are solidified by filling thermally cured resin in the case unit 13.

Inductor type electric machine having magnet equipped armature

Abstract: PROBLEM TO BE SOLVED: To provide an inductor type electric machine having a magnet equipped armature capable of output increase of a high rotating area by the reduction of armature inductance. SOLUTION: Protrusion 51-55 making the magnetic salient part of an inductor iron core 50 are opposed to provide soft magnetic pole 11-16 on an armature iron core, each winding part 41-46 of a three-phase armature winding is individually collectively wound on the magnetic poles 11-16, one magnet 31-36 is provided on the circumferential center part of the magnet poles 11-16, respectively, each magnet 31-36 is magnetized in the substantially circumferential direction, and at least a pair of the magnets 31-36 adjacent to the mutually circumferential direction are magnetized in the reverse direction to the circumferential direction. Thereby unique magnetic field distribution is formed to improve torque per a skeleton.

Inductor core-coil assembly and manufacturing thereof

Abstract: Disclosed are a gapped magnetic core which may be coated or uncoated with an insulating layer or housed in an insulting box (1) having a physical gap (10) whose dimension is close to that of the gapped magnetic core and automated or semi-automated methods of applying copper wire (21) on the gapped core or the core assembly and filling the gap with a spacer in the core or core assembly. The disclosed processes allow various combinations of core and spacer materials and gap configurations, resulting in a wide variety of core-coil assemblies which are useful as inductive components in electric and electronic circuits. Also disclosed is a core-coil assembly wherein a magnetic core with a gap directed off the conventional radial direction of a toroidally-wound core.

Electromagnetic operating device

Abstract: Disclosed is a solenoid type electromagnetic operating device which needs a relatively large current only for a limited short period at an excitation start initial stage and is adapted to achieve the speeding up at an excitation start stage and an improvement in responsiveness as well as power saving without increasing a power load on each of a drive circuit and power supply. The device is used for exerting a mechanical output on a valve element against a spring force, and comprises a solenoid coil composed of a plurality of split coils mutually electrically independent, an iron core structure including a fixed core, a movable core and a yoke and assembled with the solenoid coil so as to form a magnetic path loop through which magnetic fluxes from the split coils pass in common, an excitation controller for selectively switching/controlling the excitation current to each split coil, and a transmission mechanism for transmitting the mechanical output based on the displacement of the movable core magnetically attracted to the fixed core to the valve element when one or more of the split coils are excited.

Induction-heating fusion device

Abstract: The present invention has an object to provide an induction-heating fusion device which is capable of stabilizing the fusing temperature over the entire width of a sheet therethrough by inhibiting an excessive temperature rise in a sheet-nonpassing zone defined when a small-size sheet is subjected to fusion. The induction-heating fusion device according to the present invention includes an iron core 17 forming a closed magnetic circuit, a main induction coil 14 a wound around the iron core 17 for generating a magnetic flux which causes an electrically conductive member to generate an induction current circumferentially thereof, and at least one induction sub-coil 14 b provided on an end portion of the main coil for generating a magnetic flux which causes the electrically conductive member to generate an induction current circumferentially thereof.

A simplified method for the iron losses prediction in soft magnetic materials with arbitrary voltage supply

Abstract: The aim of this work is to propose a new approach for the iron losses prediction, in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with sinusoidal supply. The model is based on the separation of the loss contributions due to hysteresis, eddy currents and excess losses with sinusoidal supply. Since any contribution depends on the voltage supply characteristics, it is possible to find a direct mathematical relationship between the iron loss contribution and the voltage supply characteristics. As a consequence, an iron loss prediction can be obtained with any voltage supply, which does not produce hysteresis minor loop. The energetic model is based on coefficients that depend on the material characteristic. An accurate analysis of the model on eight magnetic materials, of different thickness and alloy, has been made, so the main coefficients for a large spread of magnetic materials, used for the electrical machines construction, have been found. The paper can be a useful support for electrical machine designers when the energetic performances of magnetic material, have to be predicted with the voltage supply different from the sinusoidal one.

Magnetic recording head including background magnetic field generator

Abstract: A perpendicular recording head (10) for use with magnetic recording media (30) includes a main pole (14) and a magnetic field source which is positioned sufficiently close to the main pole tip to generate a background magnetic field in the recording media. A conductive magnetizing coil (20) surrounding the main pole is preferably used as the magnetic field source. The background magnetic field generated by the magnetizing coil effectively reduces the coercivity of the magnetic recording media in the region affected by the background field. The recording head enables writing on high coercivity/high anisotropy magnetic media, thereby achieving extremely high recording densities.

Composite magnetic core

Abstract: PROBLEM TO BE SOLVED: To provide a magnetic core which has low permeability and high saturation magnetic flux density and is decreased in eddy current loss induced in a winding SOLUTION: Soft magnetic metal powder and a binder are mixed together and molded into a bar-shaped magnetic core 14, the magnetic core 14 is made to serve as the middle leg of a squarish eight-shaped core 13 of ferrite or a composite magnetic core, where the bar-shaped magnetic core 14 is fabricated through a potting method, an injection molding method, or a press molding method