Showing papers on "Inductor published in 1994"

Improved analytical modeling of conductive losses in magnetic components

Abstract: The one well-known one-dimensional method for calculating the AC resistance of multilayer transformer windings contains a built-in orthogonality which has not been reported previously. Orthogonality between skin effect and proximity effect makes a more generalized approach for the analytical solution of AC resistance in windings possible. This includes a method to calculate the AC resistance of round conductor windings which is not only convenient to use, but gives more accurate answers than the basic one-dimensional method because the exact analytical equations for round conductors can be used. >

Zero-voltage and zero-current-switching full bridge PWM converter for high power applications

Abstract: A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse-width modulated (PWM) converter is proposed. The new converter overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and limited ZVS load range for the lagging-leg switches. By using the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging-leg switches to be operated with zero-current-switching (ZCS). Meanwhile, the leading-leg switches are still operated with ZVS. The new converter is attractive for high-voltage (400-800 V), high-power (2-10 kW) applications where IGBTs are predominantly used as the power switches. The principle of operation, features, and design considerations of the new converter are described and verified on a 2-kW, 100-kHz, IGBT-based experimental circuit.

Method for designing high-Q inductors in silicon technology without expensive metalization

Abstract: A method of designing a high Q inductor for implementation in multiple metalization levels in conventional integrated circuit technology uses a software assisted iterative technique to achieve a design Q factor. The inductor turns utilize the multiple metalization levels to reduce inductor resistance.

High-Q inductors in silicon technology without expensive metalization

Abstract: A monolithic high-Q inductor structure is formed with multiple metalization levels in a conventional integrated circuit technology in which inductor turns utilize these multiple levels to reduce the inductor resistance. Inductors with Q values above five can be integrated with this approach at radio and microwave frequencies.

Inductor/antenna for a recognition system

Abstract: An improved inductor/antenna (100)improves the selectivity of a recognition system (10) by ensuring that only the transponder (14) closest to the inductor/antenna (100) of an interrogator (12) receives therefrom, and reacts to, an interrogation signal (S1). The improved inductor/antenna (100) also receives the resulting recognition signal (S2) from the transponder (14)for analysis by the interrogator (12). The inductor/antenna (100) includes two or more coils (102,104; 124,126,128,130; 132,134) which may be wound on ferromagnetic cores (108), spaced around a metal mass (46,48) such as a lock cylinder (46) of an ignition switch (24). The shape, number, location and relative winding sense of the coils are selected to shape and locate the energy field (F; 118,122) radiated by the inductor/antenna (100) so that only the transponder (14) in a key (26) which is inserted into or operating the ignition switch (24) responds to the interrogation signal (S1) radiated by the inductor/antenna (100).

A current-controlled variable-inductor for high frequency resonant power circuits

Abstract: The practicality of designing a bias-controlled inductor, suitable for high frequency resonant mode inverters and converters, was investigated theoretically and experimentally. The proposed variable inductor is built around a double 'E' core structure with zero mutual coupling between the main inductor windings and the bias windings. The theoretical analysis of this study lead to a simple equivalent circuit and closed form equations that express the relationship between the inductance and the controlling bias current. Excellent agreement was found between model predictions and experimental results. >

Radio frequency identification tag and method

Abstract: A method of and apparatus for identifying an item to or with which a radio frequency identification tag is attached or associated is provided. The tag is made of a nonconductive material to have a flat surface on which a plurality of circuits are pressed, stamped, etched or otherwise positioned. Each circuit has a capacitance and an inductance. The capacitance is formed from the capacitive value of a single capacitor. The inductance is formed from the inductive value of a single inductor coil having two conductive ends each connected to the capacitor. Each tag is associated with a binary number established from a pattern of binary ones and zeros which depend on the resonance or nonresonance of each circuit, respectively and the circuits position with respect to the binary table. The binary number may be converted to a decimal number using the binary table for conversion.

Single stage, high power factor, lamp ballast

Abstract: Unlike conventional ballasts requiring two cascaded stages, a new lamp ballast achieves near unity input power factor and high frequency sinusoidal lamp current in a single power conversion stage. A new discontinuous inductor current mode (DICM) of input inductor makes this possible by separating the input current shaping from high frequency output lamp ballasting function. The high efficiency is further enhanced by soft switching improvement, which is provided naturally through lagging current of the output resonant matching network. Design equations and experimental results verify all the advantages of the new lamp ballast. >

Annular circuit components coupled with printed circuit board through-hole

Abstract: A circuit component assembly and a method for forming the assembly as an annular body in a laminate, preferably between a trough-hole or via and a surrounding conductive layer in a PCB are disclosed, the circuit component assembly including one or more resistors/conductors, inductors and dielectrics/capacitors or combinations thereof, outer and inner peripheries of the circuit component preferably having substantially constant radii permitting simple determination of operative electrical characteristics for the circuit component from (a) the inner and outer radii, (b) an effective thickness for the circuit component and (c) its electrical characteristics determined by the material formed in the annular recess, the circuit component body preferably being formed from a liquid precursor forming conductive interconnections for the circuit component assembly at its outer and inner perimeters.

Investigations of an advanced form of series compensation

Abstract: This paper provides a comprehensive investigation of an advanced form of series compensation (ASC). The basic model consists of a series capacitor connected in parallel with a thyristor-controlled reactor (TCR). Proper selection of the thyristor firing angle increases the equivalent series compensation by developing a "loop flow" current through the series capacitor. The mathematical equations describing the voltages and currents through the capacitor, inductor, and thyristors are developed, analyzed, and later verified using the EMTP analysis program. Additionally, a model circuit was constructed to verify the analytical and computer results. The analysis revealed that the ASC circuit approaches its steady state compensation level gradually, approximately 8-10 cycles at higher levels. The analysis also revealed the significant effect of the reactor size on the ASC operating characteristics and on component sizing. >

A magnetic thin film inductor and its application to a MHz switching dc-dc converter

Abstract: The authors propose a novel structured magnetic thin film inductor using rotation magnetization only. The thin film inductor has a sandwich structure, which consists of a double-rectangular spiral coil between top and bottom CoZrNb amorphous thin films. The sputtered CoZrNb amorphous magnetic thin films have uniaxial magnetic anisotropy induced by direct current field annealing. The easy magnetization axis is directed to the main axis of the rectangular spiral coil. Hence, only the rotation magnetization process dominates in this device. The typical specifications are as follows; 3.5/spl times/5.5 mm in size, inductance of 1 /spl mu/H constant up to 10 MHz, and a quality factor of 10 at 10 MHz. A MHz switching chopper dc-dc converter has been developed by using this thin film inductor, bare-chip semiconductor devices (a power MOSFET and a Schottky barrier diode), and a multilayer ceramic capacitor. This converter with a 0.1 cc volume has an output power over 1 W at 5 MHz switching, and the power density exceeds 10 W/cc (160 W/in/sup 3/). >

A new toroidal-meander type integrated inductor with a multilevel meander magnetic core

Abstract: A novel toroidal-meander type integrated (TMTI) inductor with a multilevel meander magnetic core has been designed, fabricated, and integrated onto a silicon wafer. In a conventional inductor, conductor wires are wound around magnetic cores. By switching the roles of conductor wire and magnetic core, i.e., by 'wrapping' a magnetic core around a conductor wire, the same effect can be realized in a planar geometry. This geometry has been implemented using multilevel metal interconnection schemes, by interlacing a meander planar conductor with a multilevel meander magnetic core. The total inductor size is 4 mm/spl times/1.0 mm, the coil has 30 turns, and the magnetic material used was electroplated nickel(81%)-iron(19%) Permalloy. An inductance of 30 nH/mm/sup 2/ was achieved at a frequency of 5 MHz. The fabrication sequence of this inductor structure is entirely compatible with post-processing of standard bipolar and CMOS circuitry, as well as the fabrication of multichip module substrates, thus enabling the integration of the inductor structure with control circuitry for applications such as filters, sensors, magnetic microactuators, and low-power voltage converters. >

Lamp bulb having integrated RFI suppression and method of restricting RFI to selected level

Abstract: An incandescent lamp bulb which is driven by an electronic control module (ECM) and method of manufacture characterized in that an inductor comprising a magnetic element and a winding thereon is disposed within a screw shell base of the lamp bulb and surrounds the lamp exhaust tube therein. One end of the winding on the magnetic element is connected to a filament wire within the screw shell base and the other end of the inductive winding is connected to an output terminal of the ECM control module. In this manner, the inductor significantly reduces the di/dt rise time of voltage and current when a triac within the ECM module is driven to conduction on each one half cycle of the applied AC line voltage. This operation in turn produces a substantial reduction in radio frequency interference, both of radiation transmitted into space from the lamp bulb and by direct DC coupling back into the AC line voltage source. In a preferred embodiment, the di/dt rise time is calculated mathematically based on a Fourier series transformation of the current conducted through the filament by the triac.

Planar RF induction plasma coupling efficiency

Abstract: The radiofrequency power coupling efficiency of a planar induction source is determined by measurement of the power dissipated in the matching network and inductive coupler. Typically one finds the radiofrequency current to vary between 20 and 60 A (root mean square). The equivalent resistance of the coupling network is determined to be 0.09 Omega , and power coupling efficiency to the plasma is therefore found to be 70-90% with the remaining power lost to ohmic heating of the circuit elements. The efficiency is highest when the plasma-to-inductor distance is least since the increased mutual inductance reduces the radiofrequency inductor current and, hence, ohmic losses. Efficiency of power coupling is nearly constant as a function of radiofrequency power between 200 and 2000 W. Somewhat larger currents are required to sustain a discharge at lower pressures (about 1 mTorr) or when the plasma is not magnetically confined, giving rise to lower coupling efficiencies.

Modeling the dynamics of nonlinear inductor circuits

Abstract: The Jiles-Atherton (J-A) model is applied to the problem of describing the dynamics of a nonlinear circuit driven by a square wave voltage source and comprising a linear resistor and capacitor in series with a nonlinear inductor, whose core displays saturation and hysteresis. The presence of hysteresis is shown to increase the order of the circuit by one. Period-multiplication and chaos are observed and excellent agreement is obtained between experiment and simulation. >

Maximum frequency and optimum performance of class E power amplifiers

Abstract: An analytical method is proposed to discuss class E RF power amplifiers with finite choke inductors. All parameters in these amplifiers can be expressed in terms of circuit-component values and amplifier specifications. The component values of class E amplifiers required to achieve optimum amplification can be directly obtained after the amplifier specifications are fixed. An obvious relationship between the parameters of class E amplifiers with finite choke inductors in optimum performance can be obtained. Hence, the key function of each component in the circuit can be indicated clearly, especially in the case of a finite choke inductor. The finite choke inductor can also be used to compensate for the high intrinsic output capacitance of the active power device to extend operation frequency. To assure optimum performance and safe operation, a criterion is assigned. Based on this criterion and the optimum conditions, a maximum frequency for a transistor safely operating in class E amplifiers can also be obtained.< >

Calculation of winding losses in high-frequency toroidal inductors using single strand conductors

Abstract: The paper is concerned with the optimisation of inductor design to improve the design capability for these large, expensive and heat-producing magnetic components in power electronic circuits. The work focuses on toroidal inductors which consist of uniformly distributed, solid conductor windings on low permeability toroidal cores. It develops methods of calculating the eddy current losses in the windings. The basic analytical equations for losses in the windings are evolved and the problem of variable turn pitch that arises in the toroidal geometry is dealt with by means of an effective core diameter concept. Effective core diameters are presented graphically in terms of normalised parameters. The theoretical and graphical results given in the paper enable toroidal inductor designs to be optimised, and losses to be calculated in a rapid and convenient way. Experimental results are shown to agree well with the theoretical results presented in the paper.

Monolithic narrow-band filter using ultrahigh-Q tunable active inductors

Abstract: A tunable active inductor is presented where the novel topology enables both the inductance and series resistance to be varied. With a discrete MMIC realization of this active inductor, Q-factors in excess of 15000 have been measured over a wide range of inductance values. Applications for these active inductors include high-performance narrow-band filters, voltage controlled oscillators, and analog phase shifters. Analytical equations for the novel active inductor and a 3-resonator filter are given. The measured performance for a monolithic 2 GHz filter achieves a mean insertion loss of 0.9 dB, passband ripple of /spl plusmn/0.7 dB, with a 3 dB bandwidth of 70 MHz, and an excellent out-of-band rejection which exceeds 50 dB up to 18 GHz. >

Modelling iron-powder inductors at high frequencies

Abstract: A high-frequency model of iron-powder core inductors is studied. The skin and proximity effects that cause the winding parasitic resistance to increase with the operating frequency are considered. The inductor self-resonance due to the parasitic capacitances is also taken into account. The frequency response of the inductor model is compared to that of an experimentally tested iron-powder core inductor. The first self-resonant frequency is determined from the plot of the measured reactance and allows for the calculation of the parasitic capacitance. Equations for the inductor parasitic resistance are derived in a closed form. Expressions giving the AC resistance as a function of the operating frequency are given. These expressions allow for an accurate prediction of the inductor power loss over a wide frequency range. The measured and calculated values of the inductor impedance magnitude end phase, the real and imaginary parts of the inductor impedance, the inductance, and the inductor quality factor are plotted versus frequency and compared. Theoretical results were in good agreement with those experimentally measured. Therefore, it is demonstrated that the discussed equivalent circuit has a frequency response matching that of the real inductor. Moreover, the circuit model is simple, it allows for an immediate understanding of iron-powder core inductor behavior and can be easily used in computer simulations of electronic circuits. >

Integrated air coil and capacitor and method of making the same

Abstract: In one aspect, the present invention provides an integrated inductor and capacitor 20 which can be used as the inductive portion of a resonant circuit and the energy accumulator for a identification system transponder. In a first embodiment, the integrated inductor and capacitor component 20 may include first and second strips of electrically conductive material 22 and 26, for example aluminum. The first and second strips 22 and 26 are wound in a coil 20 to form a plurality of windings. Each winding is electrically insulated from adjacent ones of the windings by insulators 24 and 28. The component can be bonded to a transponder chip.

Monolithic narrow-band filter using ultrahigh-Q tunable active inductors

Abstract: A tunable active inductor is presented where the novel topology enables both the inductance and series resistance to be varied. With a discrete MMIC realization of this active inductor, Q-factors in excess of 15 000 have been measured over a wide range of inductance values. Applications for these active inductors include high-performance narrow-band filters, voltage controlled oscillators, and analog phase shifters. Analytical equations for the novel active inductor and a 3-resonator filter are given. The measured performance for a monolithic 2 GHz filter achieves a mean insertion loss of 0.9 dB, passband ripple of ±0.7 dB, with a 3 dB bandwidth of 70 MHz, and an excellent out-of-band rejection which exceeds 50 dB up to 18 GHz

A fully integrated planar toroidal inductor with a micromachined nickel-iron magnetic bar

Abstract: A fully integrated toroidal inductor is realized on a silicon wafer by using a multilevel metallization technique to fabricate a wrapped coil wound around a micromachined bar of high-permeability magnetic material. In particular, efforts are made to minimize the coil resistance by using thick conductor lines and electroplated vias. In this structure, a 30 /spl mu/m thick nickel-iron permalloy magnetic core is wrapped with 40 /spl mu/m thick multilevel copper conductor lines, constructing a conventional toroidal inductor in planar shape. A closed magnetic circuit (i.e., toroidal) in this inductive component is adopted, where magnetic core bar and wrapped conductor lines are tightly interlinked, so that leakage flux and electromagnetic interference are minimized. For an inductor size of 4 mm/spl times/1 mm/spl times/130 /spl mu/m thickness having 33 turns of multilevel coils, the achieved inductance is approximately 0.4-0.1 /spl mu/H at 1 kHz-1 MHz, corresponding to a core permeability of approximately 800. The measured dc resistance of the conductor lines is approximately 0.3 /spl Omega/. Since this inductive component shows favorable magnetic characteristics as well as electrical properties, it is potentially very useful as a basic inductive component in applications for magnetic microsensors, microactuators, and micromagnetic power devices such as a dc/dc converter. >

High-quality rectifier based on coupled-inductor Sepic topology

Abstract: A high-quality rectifier employing a coupled-inductor Sepic topology is described, featuring high-frequency insulation and low input current ripple. Moreover, sinusoidal and in-phase input current is obtained even with constant duty-cycle. The magnetic structure is simple and cheap, allowing considerable size and cost reduction. Converter analysis, design criteria of both power and control sections and experimental results are reported in the paper. >

Transformer and inductor modules having directly bonded terminals and heat-sink fins

Abstract: A matrix transformer and/or inductor module has its terminations bonded rigidly to the ferrite core of which it is made. Because the ferrite core is strong and dimensionally stable, the terminations are rugged and precisely located, important criteria for assembly to printed circuit boards and the like, especially if automated assembly methods are used. In another embodiment, the module has top and bottom metal plates which are the high current output terminals. This module can be mounted sandwiched between live heat sinks. In another embodiment, deep grooves are made into the core material, and fins are bonded into the grooves. The grooves reduce core losses by reducing eddy currents and dimensional resonance effects, and the fins remove heat from within the core allowing operation at much higher flux density and frequency.

High Q integrated inductor

Abstract: An inductive structure is provided which displays an increased self-inductance and improved Q at high frequencies. The improvement resides in the disposition proximate the inductive structure an amount of magnetic material to increase mutual inductance between adjacent portions of the inductor's conductive path with current flow.

Digitally controlled switchmode power supply

Abstract: A digitally controlled switchmode power supply by the use of a pulse width modulated (PWM) controlled field effect transistor, switches an inductor between input and output sides to provide a controllable DC output voltage. The digital processor receives and digitizes the input and output voltages and also the current through the associated inductor and derives a PWM control loop signal driving the associated field effect switching device to switch the inductor. The foregoing compensates for nonlinear changes in the value of the inductance due to changes in inductor currents and also avoids resonance at pole points of the LC circuit in the power supply. In addition a change in buck to boost modes may be accomplished automatically depending on input voltage operating conditions.

Zero-voltage-transition converters using an inductor feedback technique

Abstract: A technique using inductor feedback is presented for achieving zero-voltage switching (ZVS) in PWM controlled topologies. These converters exhibit low voltage and current stresses characteristic of hard-switched PWM converters, yet achieve ZVS with minimal current and voltage rating of the auxiliary soft-switching circuitry. Based on this technique, an experimental 730 W, 300 kHz boost converter is designed for universal off-line power factor correction. A complete analysis and a design procedure are also presented. >

Fast computer-aided simulation of switching power regulators based on progressive analysis of the switches' state

Abstract: A new method for time-domain analysis of power electronics circuits is developed based on the following principles: (a) at each instant, the switching topology is a linear time-invariant circuit; (b) at each instant, the voltage across a capacitor and the current through an inductor have a certain value, like an independent voltage- or current source, respectively; (c) generally, no switching relationship between the externally and internally controlled switches may be assumed; (d) prior knowledge of the internally controlled switches' operation is not available; and (e) the switching action may change the response of the circuit immediately after the switching moment, implying that some constraints may be in violation of the presumed switches' states. The algorithm is based on solving a system of algebraical modified nodal equations at each integration step. The number of systems to be solved equals the number of topologies the converter goes through in a cycle. This feature, and the fact that no solutions of time-differential equations or Laplace transform inverses are required, cause the algorithm to be a fast one. At each step, the presumed state of all the switches is checked, and if some constraints are violated, the program looks for another valid topology. An example, with parasitic effects taken into account, is presented; the experimental results, as well as the simulation results obtained by using other available algorithms, confirmed the accuracy of the results achieved with the presented approach. >

Inductor-controlled current-sourcing resonant inverter and its application as a high pressure discharge lamp driver

Abstract: The practicality of designing a fixed-frequency resonant inverter that is controlled by a variable inductor was investigated theoretically and experimentally. The proposed approach was studied by considering the design of current source resonant inverter. The theoretical analysis yielded closed form (albeit implicit) relationships between the inductance and the transfer function of the inverter. Excellent agreement was found between model predictions and experimental results. An experimental inverter was designed and tested as an electronic ballast for a discharge lamp (metal halide lamp). The inverter was operated at 200 kHz and included ignition circuitry and dimming capability. >