Showing papers on "Inductor published in 1990"

Modern Ferrite Technology

Abstract: Basics of Magnetism-Source of Magnetic Effect.- The Magnetization in Domains and Bulk Materials.- AC Properties of Ferrites.- Crystal Structure of Ferrites.- Chemical Aspects of Ferrites.- Microstructural Aspects of Ferrites.- Ferrite Processing.- Applications and Functions of Ferrites.- Ferrites for Permanent Magnet Applications.- Ferrite Inductors and Transformers for Low Power Applications.- Ferrites for EMI Suppression.- Ferrites for Entertainment Applications-Radio and TV.- Ferrite Transformers and Inductors at High Power.- Ferrites for Magnetic Recording.- Ferrites for Microwave Applications.- Miscellaneous Ferrite Application.- Physical, Mechanical and Thermal Aspects of Ferrites.- Magnetic Measurements on Ferrite Materials and Components.

Average current mode control of switching power supplies

Abstract: Current mode control as usually implemented in switching power supplies actually senses and controls peak inductor current. This gives rise to many serious problems, including poor noise immunity, a need for slope compensation, and peak-to-average current errors which the inherently low current loop gain cannot correct. Average current mode control eliminates these problems and may be used effectively to control currents other than inductor current, allowing a much broader range of topological application.

Transformers as equivalent circuits for switches: general proofs and D-Q transformation-based analyses

Abstract: The equivalent circuits for the switches in DC-DC, DC-AC, AC-DC, and AC-AC converters are proved to be time-varying transformers. This result is used in the analyses of DC-DC converters, an eight-order current source rectifier-inverter, and a buck-boost inverter. The circuit D-Q transformation is proposed for the analyses of the AC converters such as inverters, rectifiers, and cycloconverters which include the time-varying transformers. Gyrators appear in the D-Q transformed inductors and capacitors of the AC converters. Few equational manipulations are required to determine the steady-state operating points and the small signal gains of the converters. The analysis result for the rectifier-inverter shows that the circuit has self-short-circuit protection capability and strong immunity in the parasitic inductor resistance. >

Introductory Circuit Analysis

Abstract: From the Publisher: THE most widely acclaimed introduction to circuit analysis for more than three decades. Features exceptionally clear explanations and descriptions, step-by-step examples, more than 50 practical applications, over 2000 easy-to-challenging practice problems, and comprehensive coverage of essentials. PSpice, OrCAd version 9.2 Lite Edition, Multisims 2001 version of Electronics Workbench, and MathCad software references and examples are used throughout. Computer programs (C++, BASIC and PSpice) are printed in color, as they run, at the point in the book where they are discussed. Current and Voltage. Resistance. Ohm's Law, Power, and Energy. Series Circuits. Parallel Circuits. Series-Parallel Networks. Methods of Analysis & Selected Topics. Network Theorems. Capacitors. Magnetic Circuits. Inductors. Sinusodial Alternating Waveforms. The Basic Elements and Phasors. Series and Parallel ac Circuits. Series-Parallel ac Networks. Methods of Analysis and Related Topics. Network Theorems (ac). Power (ac). Resonance. Transformers. Polyphase Systems. Decibels, Filters, and Bode Points. Pulse Waveforms and the R-C Response. Nonsinusodial Circuits. System Analysis: An Introduction. For those working in electronic technology.

Inductive power transfer to an electric vehicle-analytical model

Abstract: The roadway powered electric vehicle (RPEV) system is a unique electric vehicle system that receives electric power by inductive coupling from an inductor buried beneath the road surface. The analytical model of the system that transfers power from the wayside to the vehicle battery and DC traction motor is analyzed. This model includes the roadway inductor, the vehicle-mounted pick up inductor, and the onboard circuitry for control/conditioning of the coupled power. The equivalent circuit model of the inductive power coupling system is derived. Based on this model, the electrical characteristics of the system are explained. Trade-offs in selecting system parameters are discussed. All test results have tended to confirm simulation results obtained using the analytical model. >

Effect of finite thickness of magnetic substrate on planar inductors

Abstract: The effect of finite thickness of magnetic substrate or film on the inductance of planar inductors is studied using the method of current images. The results obtained reduce to previous results in the limit of infinite thickness. It is found that the thickness and permeability play complementary roles in the enhancement of inductance, with the normalized inductance determined roughly by the product of permeability and thickness in the most interesting region of parameter space. The results derived allow determination of the required minimum thickness of the substrate which will produce maximum inductance enhancement for a given permeability of the substrate material. The same results can also be used to determine the permeability of a magnetic film or substrate quickly and are directly applicable to the design of planar inductors in cofireable ceramic, hybrid, and thin-film technologies. >

Electrical capacitance clearanceometer

Abstract: A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap

Inductor shunt, output voltage regulation system for a power supply

Abstract: High efficiency, post regulation of auxiliary outputs in multiple output-power supplies is provided by connecting a regulating switching device in parallel with a filter inductor connected in the current path from the rectifiers to the output terminal. For minimum output power for that auxiliary output, the switching device is held off at all times. When increased power is required, the switching device is turned on for a short period during each cycle of the inductor voltage. The switching system may be configured to conduct current from the output end of the inductor to the input end of the inductor or vice versa or either one selectively, in accordance with the particular regulation scheme chosen. Efficiency is maximized since current flows in the switching device for only a small portion of the cycle of the inductor voltage.

Application of magnetic energy storage unit as continuous VAr controller

Abstract: It is shown that magnetic energy storage units can simultaneously operate as continuous VAr (volt-ampere reactive) controllers while performing the role of load-frequency stabilizers in electrical power systems. This is achieved by operating the converter in the buck-boost mode with a switched capacitor bank placed across its terminals. The P versus Q modulation ranges of the 12-pulse converter depend on the source inductance, secondary voltage of the input transformers, and output current. Once the input transformer is chosen, the Q modulation range depends on the active power transfer and the current through the inductor at any instant of time. The actual reactive power consumption of the converter is varied continuously, depending on the requirements of the power system, while keeping within the Q-modulation range. Switching of the capacitor bank keeps the required Q consumption of the converter within the available range. It is shown that this mode of control improves the overall performance of the power system in P-f and Q-V loops and obviates the use of any additional VAr compensator in the power area where the SMES (superconducting magnetic energy storage) unit is located. >

Consistent initial conditions of linear switched networks

Abstract: The analysis of switched networks encounters a major difficulty due to the discontinuity of network variables and the presence of impulsive voltages and currents at the switching instants. The problem of obtaining consistent initial conditions for linear networks with ideal switched is addressed. The method used is based on numerical Laplace transform theory and is applicable to any circuit configuration. Capacitor loops, inductor cutsets, ideal switches with zero impedance or admittance, and impulsive sources do not present problems. Although initial conditions are normally required for time-domain analysis, an even more important application is in the frequency-domain analysis of general periodically switched linear networks. The algorithms are easily implemented in a computer program. >

Thin film cloth-structured inductor for magnetic integrated circuit

Abstract: A thin-film cloth-structured inductor for MAGIC (magnetic integrated circuit) operation in the high-frequency range is described. To achieve high inductance in a small area, magnetic core arrays with low demagnetizing factor are utilized. To increase the frequency, which is limited by the resonant frequency, the magnetic-strip core arrays are divided into three parts and each core array is excited out of phase; that is, the inductor is composed of three unit inductors connected in series with low mutual coupling. Thus, the resonant frequency of the integrated inductor is high, and high-frequency operation is possible. The experimental inductor is 3*3 mm/sup 2/ in size. The inductance is about 300 nH at 100 MHz, which is about eight times as large as that of the air-core inductor. High inductance can be easily achieved by increasing the number of strip cores with high permeability. >

Patient monitoring apparatus and method

Abstract: A respiration transducer apparatus for monitoring respiratory movement in patients is disclosed which includes a transducer for detecting respiratory movement in the patient's body. The transducer includes a first inductor adapted to be positioned adjacent a portion of the patient's body and a second inductor adapted to be positioned adjacent the same portion of the body. The transducers are disposed in a substantially fixed geometric relation as an integrally fixed coil with the first and second inductors inductively reacting with each other and a forming a continuous transducing area.

Analysis of planar sandwich inductors by current images

Abstract: Inductors with spiral windings sandwiched between top- and bottom-plane thick magnetic plates are investigated theoretically using the method of current images. Expressions are obtained for the inductances, and magnetic fields of these planar structures assuming infinite plane thicknesses. The dependence of the inductance on the permeability and the distances between the spiral windings and the top and bottom plates is studied by numerically evaluating the inductance expressions. It is shown that, except for some limiting cases, the inductance depends only on the net distance between the top and bottom magnetic plates and is independent of the position of the spiral windings within the gap. Furthermore, it is found that, in contrast to open planar structures, the sandwich inductor can yield large values of inductances with the enhancement over air-core values limited only by the permeability of the magnetic plates. Numerical evaluation of the formulas for magnetic fields both inside the magnetic plates and in the gap are used to calculate energy density variation in the device, to estimate lateral dimensions of these sandwich inductors, to discuss construction of multiple devices in a single-sandwich structure, and to discuss calculation of losses in the sandwich inductors. >

An exact analysis of class E amplifiers with finite DC-feed inductance at any output Q

Abstract: Previous analyses of class E amplifiers have required infinite output network Q and/or infinite DC-feed inductance. A Laplace-transform technique is applied to class E circuits with neither of these restrictions. The analysis presented is shown to have excellent agreement with observed circuit performance. >

Device for electromagnetic static and voltage suppression

Abstract: A device for suppressing electromagnetic static and voltage surges induced on radio frequency transmission cables is disclosed. The device comprises a blocking capacitor connected to prevent the conduction of DC currents but to permit the transmission of radio frequency signals. An inductor coil is connected between one side of the capacitor and ground. The inductor coil is of a value that blocks conduction of radio frequency signals but allows static and low frequency DC voltage surges to be conducted to ground. A gas discharge unit is also connected from the same side of the capacitor to ground. The discharge unit is a secondary discharge device that only operates when the transient speed and magnitude of the surge is sufficient to cause a back emf to develop across the inductor coil above a predetermined limit. The gas discharge unit assures that the capacitor is not damaged by the back emf. A resistor is connected between the other side of the capacitor and ground to discharge any DC voltage developed on the other side of said capacitor.

A multilayer hybrid circuit

Abstract: A multilayer hybrid circuit having a laminated body having at least one of a plurality of dielectric layers, dielectric magnetic layers, and conductive patterns on said dielectric layers and said magnetic layers, is produced through printing process and sintering process, and composes capacitors, inductors, and resistors. An external connection is effected by side terminals positioned on side walls of the laminated body. A coupling conductor which is perpendicular to a dielectric plane is provided for coupling elements on different planes. Said coupling conductor is a succession of essentially S-shaped conductor chips or lines with the ends connected to adjacent conductor chips on different planes. That coupling conductor functions via a through hole conductor in a prior printed circuit board, and has high operational reliability in a component which is produced through sintering process. In one embodiment, an inductor is produced by a pair of coils connected in series with each other to reduce the thickness of the laminated body while providing high inductance.

Integrated electromagnetic interference filter

Abstract: An integrated electromagnetic interference filter (20) includes an inductor assembly (22) for attenuating both common mode and differential mode electromagnetic interference conducted emissions from electronic equipment. The inductor assembly (22) includes an outer core (28) of permeable material defining an outer window (30), and an inner core (32) of permeable material disposed in the outer window and defining an inner window (34). A first power lead (36) for connecting the equipment to a source of electrical power includes a portion wound in one direction about only the outer core. The inductor assembly includes a second power lead (38) for connecting the equipment to the source of electrical power with a portion of the second lead wound about both the inner and outer cores in the opposite direction to the winding of the portion of the first power lead. The outer core (28) provides a magnetic path for the attenuation of common mode emissions and the inner core (32) provides a magnetic path for the attenuation of differential mode noise. The filter can also include a multiple function capacitor (62) including three capacitive elements.

Zero-voltage resonant transition switching power converter

Abstract: A single-ended DC-to-DC power converter which is operative at very high switching frequencies with zero-voltage resonant transition switching. A single magnetic element functions as both a storage inductor and a transformer. A charging capacitor is switched to induce a reversal current through the inductor for providing the zero-voltage switching function. Control to output characteristics are identical to those of conventional buck and buck-boost converters. The invention provides efficient, high-frequency operation and isolation of the output from the input power source with minimal component volume. The control system is adaptable to constant frequency pulse width modulation for voltage regulation.

Electronic ballast and power controller

Abstract: A relatively high efficiency, relatively light weight, relatively small electronic ballast or AC power controller for use in aircraft and elsewhere for controlling a fluorescent lamp load or other load includes an EMI filter, a multi-purpose transformer, a power conversion stage and a control circuitry stage. The ballast or controller operates to increase or decrease the voltage of the incoming sine wave AC voltage through a charging path for an energy storage inductor choke cooperating with an energy storage capacitor wherein the charging path for the capacitor is different from the discharge path of the capacitor to isolate the load from the charging of the capacitor and thus to provide an output to the load which is independent of the charging path and which is out of phase with the incoming waveform. This is achieved through conversion of the incoming AC power to a higher frequency and to a higher or lower voltage, under the control of a switching system and reconversion to the input frequency, followed by filtering to remove the high frequency components. The system includes various novel feedback loops for the lamp current and the like for control of lamp current and dimming control. Various forms are described including a high efficiency form in which the incoming power is added to the ballast output for operation of the lamp load.

Switched capacitor interleaved forward power converter

Abstract: A DC-to-DC power converter topology utilizing parallel connected transformers in a buck switching configuration with each stage operated 180° out-of-phase, with the primary windings of the transformers sequentially feeding into a common filter capacitor. On each transformer, a secondary winding is switched to a load at the time the primary winding is shunted across the filter capacitor. The circuit provides dual inductor buck power stage operation while maintaining input-output isolation. Interleaved power processing provides continuous capacitance support for the output voltage produced by the power supply.

Switching circuit employing electronic devices in series with an inductor to avoid commutation breakdown and extending the current range of switching circuits by using igbt devices in place of mosfets

Abstract: A switching circuit is provided which is to be connected to a power source. The circuit includes a first device, an inductor and a second device, all connected in series. Either a single inductor or a pair of series-connected inductors is connected in series between the first and second devices. One or both of the first and second devices are switched on and off to supply a load with an output voltage. The circuit can also include diodes to prevent harmful reverse current flow and to provide bypasses around the first and second devices. The first and second devices can be semiconductor elements, such as FETs, and particularly MOSFETs. The first device can be an IGBT.

Alternating current ignition system

Abstract: An ignition system for a spark ignited internal combustion engine. The system can apply alternating current to the electrodes of a spark plug to maintain an arc at the electrodes for the desired length of time. The amplitude of the arc current can be varied. The alternating current is developed by a DC to AC inverter that is comprised of a transformer that has a center tapped primary and a secondary that is connected to the spark plug. An arc is initiated at the spark plug by discharging a capacitor through one of the winding portions of the center-tapped primary. Alternatively, the energy stored in an inductor can be supplied to a primary winding portion to initiate an arc. The ignition system is powered by a controlled current source that receives input power from a source of direct voltage such as a battery on a motor vehicle.

Fabrication and basic characteristics of dyr-etched micro inductions

Abstract: Thin-film meander inductors having 10/sup -6/-m-range coil spacing were fabricated successfully by a dry-etching technique. The inductance measured with a microstrip line increased with coil spacing due to dielectric coupling between the meander lines. The maximum value of the applicable current density was examined, and it was clarified that magnetic thin films are required to provide high saturation magnetization in order to remain in the undersaturated region in case of high current density applications. It is concluded that these results provide a basis for developing thin-film micro inductors and transformers. >

Apparatus employing a welding power supply for powering a plasma cutting torch

Abstract: A boosting circuit is used to boost the voltage output of a DC selding power supply to a higher voltage output adequate for powering a plasma cutting torch. The boosting circuit includes a first inductive stage including an inductor receiving energy from a DC welding power supply. The boosting circuit also includes a capacitive second stage receiving energy from the inductor in the first stage where the two stages together boost the output of the boosting circuit to a voltage output higher than that supplied by the welding power supply.

Bifilar planar inductor

Abstract: A planar microstrip inductor formed from a spiral shaped conductive path of material on a dielectric uses a bifilar spiral by which both the connection nodes of the inductor can be brought out to the edge of the substrate. The bifilar winding by which both connection nodes are available from the exterior of the spiral shape includes the use of a jumper wire to connect the inner node of the inductor to a circuit.

Spikeless motor starting circuit

Abstract: A capacitor-start capacitor-run single phase AC induction motor control starting circuit is provided which minimizes first cycle current spiking magnitude, and also minimizes cycle to cycle current spiking magnitude, without a choke or inductor in the loop containing the run capacitor, start capacitor and start switch. The first cycle current spiking problem is solved by controlling when the start switch may be turned on at initiation of the starting mode in relation to the AC cycle, to permit turn-on of the start switch only within a known or predictable range of voltage differential between the run and start capacitors. The cycle to cycle current spiking problem is solved by proper phasing of gate current, and supplying gate current to the start switch in phase with the voltage across the run capacitor and out of phase with the current through the series connected start switch and start capacitor.

Inductance and capacitance noise filter

Abstract: A distributed constant type LC noise filter includes a dielectric formed into an insulating plate or cylinder, a first conductor spirally formed on the dielectric at one side to function as an inductor, a second conductor spirally formed on the other side of the dielectric at a location opposite to the first conductor to form a distributed constant type capacitor between the first and second conductors, and a shield conductor located on the dielectric between each adjacent lines in the first conductor to prevent a short-circuit therebetween, whereby noise components in signals on the first conductor can be eliminated without any short-circuit between each adjacent lines in the first conductor.

Coupled inductor type dc to dc converter with single magnetic component

Abstract: A coupled inductor type boost DC to DC converter with a single multipurpose magnetic component. The invention includes a conventional switch for converting an input DC voltage to a signal having a time varying waveform. The switch Q1 has a pole terminal connected to a source of input voltage, a control terminal and first and second throw terminals. The single inductive element includes a first winding LN1 connected between an output terminal of the switch and an input terminal of the converter and a second winding LN2 connected between the second throw terminal of the switch and an output terminal of the converter. In a first embodiment, the invention further includes a winding LN3 of the inductive element connected at a first end to the control terminal of the switch which provides a level shifting circuit for shifting the level of a drive signal applied to the control terminal of the switch.

Balancing and shunt magnetics for gaseous discharge lamps

Abstract: In accordance with the present invention, a control device for energizing a lamp circuit including gaseous discharge lamps includes a power source having a variable amplitude varying in time A control circuit is provided for producing a variable pulse width control signal A switch is responsive to the variable pulse width control signal for providing a switched output from the power source The switched output has a pulse width proportional to the variable pulse width control signal for supplying power to the lamp circuit An inductor is interconnected between the switch and the lamp circuit The inductor includes a first winding with a center tap for receiving the switched output from the switch for balancing the voltage and current applied to the lamps within the lamp circuit The inductor further includes a second winding connected to the lamp circuit for providing constant lamp brightness regardless of amplitude variations in the source voltage

Power control circuit for inductively coupled plasma atomic emission spectroscopy

Abstract: A multiple frequency plasma torch activation circuit includes a system driver circuit with a pair of different frequency sources and a selector switch which allows one of the sources to be coupled to a splitter assembly which applies signals to a pair of independent power amplifiers having their outputs applied to a combiner assembly and to the plasma torch inductor. A detector circuit provides signals to a power control circuit which includes forward and reflected power monitoring and an impedance matching circuit for optimum coupling of the frequencies to the inductive load.