Showing papers on "Inductor published in 1992"

High efficiency power factor correction using interleaving techniques

Abstract: A highly efficient 1.5 kW power factor correction converter for computer applications is presented. Eight boost-topology switching cells are interleaved to meet stringent EMI input ripple specifications while operating at a very low switching frequency (25 kHz per cell) to minimize switching losses. The result is a system with very high conversion efficiency (94%-97%, including input bridge, bias supply, and EMI filter losses) over the 93-264 VAC input range. Key implementation details, including discontinuous inductor current operation, a combination of linear and bang-bang control algorithms for fast dynamic load response, and extended (100 ms) power outage ride-through capability, are described. >

Robust OP Amp realization of Chua's circuit

Abstract: Chua's circuit is a simple electronic network which exhibits a variety of bifurcation phenomena and attractors. The circuit consists of two capacitors, an inductor, a linear resistor, and a nonlinear resistor. This paper describes the design methodology for a robust practical op amp implementation of Chua's circuit. In addition, we present experimental results and SPICE simulations for a working circuit using o -the-shelf components.

Integrated high quality rectifier-regulators

Abstract: A family of AC-to-DC converters which integrate the functions of low harmonic rectification, low frequency energy storage, and wide bandwidth output voltage control into a single converter containing one, two, or four active switches is presented. These converters utilize a discontinuous conduction mode input inductor, an internal energy storage capacitor, and transformer secondary circuits which resemble the bridge, forward, flyback, or Cuk DC-DC converters. A large-signal equivalent circuit model for this family which uses the loss-free resistor concept is presented. Design strategies and experimental results are given. High performance regulation with satisfactory line current harmonics is demonstrated with conventional duty ratio control. Further improvements in line current are possible by simultaneous duty ratio and switching frequency control. >

A simple analysis of an inductive RF discharge

Abstract: The electrical properties of an inductive low pressure RF discharge have been analysed by considering the discharge to be a one-turn secondary of an air-core transformer. Expressions for spatially averaged quantities representing familiar discharge parameters such as the voltage, current and electric field have been determined as functions of measured electrical parameters of the primary circuit. Based on an analytical expression relating the coupling between the electrical characteristics of the primary coil and the plasma load, scaling laws for plasma parameters and the RF power distribution between the inductor coil and the discharge have been determined. The analysis developed here was applied to a collisionally dominated inductive RF discharge in a mercury-rare gas mixture. It may also be applied as a practical design and optimization tool for a plasma processing source based on an inductive discharge.

Input current shaper using Cuk converter

Abstract: The Cuk converter with integrated magnetics when used for input current shaping exhibits advantages over other topologies. When the 'ripple steering' mechanism is employed, essentially zero input and output current ripples are obtained for all operating conditions, and the size of the magnetics can be significantly reduced. The discontinuous inductor current mode (DICM) with no current feedback loop is analyzed. Current shaping takes place automatically by keeping the duty cycle and switching frequency constant when the converter operates in DICM. The high input power factor and high overall conversion efficiency suggest operation in DICM for low-power applications. Experimental results obtained on a 200-W prototype are presented. >

Charge control: modeling, analysis and design

Abstract: There are many ways to use the inductor current of a PWM converter as part of its feedback control mechanism. A simple and widely used method is peak current-mode control which uses the instantaneous inductor current as part of the control signals. Charge control is a special type of current-mode control. It uses the integration of the on-time inductor current as the feedback control signal. The characteristics of charge control are studied. A complete small-signal analysis is performed for the control scheme. Subharmonic oscillation similar to that of peak current-mode control is found, and the relationship between subharmonic oscillation and the line/load condition of charge control is defined. Based on the analysis, design guidelines which guarantee the stability of the control system under given line and load ranges are proposed. The small-signal model was confirmed experimentally. >

Resonant power supplies

Abstract: This resonant power supply produces a varying magnetic field from a resonant inductor. Two active switches drive, but remain outside, a resonant circuit, also including resonant capacitor. A phase-splitting transformer provides, via a decoupling inductor, one connection for a power supply; the return is through the active switches, which are either off or are from time to time driven alternately by the controller so as to maintain the resonant current in the resonant circuit. Applications include induction heating and induction hobs for cooking, and also a power source for inductively powered vehicles (or other inductively powered devices) adjacent to an inductive pathway.

H-driver DC-to-DC converter utilizing mutual inductance

Abstract: Improved conversion efficiency and lower output ripple are achieved by a DC-to-DC converter that uses an H-bridge driver to alternately energize first and second inductors. By alternately energizing the first and second inductors, a higher switching frequency can be maintained allowing for the use of smaller inductors while reducing ripple in the output voltage. The reduced ripple in turn reduces the need for filtering. Additionally, the first and second inductors are wound about a common core such that a mutual inductance exists therebetween. The mutual inductance results in trapezoidal currents in each inductor instead of the typical sawtooth waveforms. This results in still lower ripple in the output voltage.

Small-signal modeling of average current-mode control

Abstract: A recently proposed average current-mode control is analyzed. A complete small-signal model for the control scheme is developed. The model is accurate up to half the switching frequency. By closing the current loop, a flat control-to-inductor current transfer function, up to half the switching frequency, can be achieved. This control scheme enables the converter to behave as an ideal current source. The subharmonic oscillation, as frequently reported in peak current-mode control, also exists in this control. This subharmonic oscillation can be eliminated by choosing a proper gain of the compensation network in the current loop. Model predictions are confirmed experimentally. >

Soft-switching full-bridge dc/dc converting

Abstract: The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM full-bridge dc/dc converter substantially reduces the switching losses of the transistors and the rectifier diodes, under all loading conditions. We give analyses, practical design considerations, and experimental results for a 1.5-kW converter with 60-V, 25-A output, operating at 100-kHz clock frequency and 95% efficiency.

Zero voltage switching pulse width modulated power converters

Abstract: The power converter of this invention accomplishes zero voltage switching at both turn on and turn off transitions of a primary switch (206). A transformer (218) serves as both energy storage device and isolation mechanism. Inductance (216) placed in series with transformer (218) provides energy to drive the turn on resonant switching transition of switch (206). Additional energy storage is provided by a required primary side filter capacitor (220) and an output filter capacitor (224). During a first operational state in which switch (206) conducts, energy is transferred from power source (202) to transformer (218) and capacitor (220). During the first state, capacitor (224) supports a load (226). During a second operational state, a second primary switch (212) and a secondary switch (234) conduct and energy is transferred from capacitor (220) and transformer (218) to series inductance (216), capacitor (224) and load (226). The resonant transition from the first state to the second state is driven by some combination of stored energy in transformer (218) and inductor (216). The AC magnetizing currents and AC magnetic fields of transformer (218) can be made smaller than the average magnetizing current and the average magnetic field, respectively, and the converter can accomplish zero voltage switching at all line and load conditions.

Soft-switching PWM converters

Abstract: A full-bridge zero-voltage-switching pulse-width-modulated converter employs a saturable reactor in place of the linear inductor in order to reduce current stress on the active switches, reduce voltage stress on the rectifier diodes, and reduce secondary parasitic ringing. The zero-current-switching full-bridge pulse-width-modulated converter embodiment of the invention contemplates the provision of active switches that are zero-current-switched and passive switches, such as diode switches, that are zero-voltage-switched.

High frequency resonant gate drive for a power MOSFET

Abstract: An efficient power MOSFET resonant gate drive circuit having a large coupled inductor between and in series with two switching transistors. The inductor prevents cross-conduction from the power bus through the drive transistors as may be caused by simultaneous turn-on due either to switching delays or single-event-upset-radiation from energetic cosmic rays. In either case, the inductor presents a high impedance for current that tries to flow through both transistors simultaneously. A center tap on the inductor is connected to the gate of the power MOSFET. An equivalent inductance resonates with the equivalent capacitance of the gate of the power MOSFET providing fast turn-on of the power MOSFET. During turn-off of the power MOSFET, one drive transistor is switched-off and the other drive transistor is switched-on. The voltage generated by the coupled inductor exceeds the magnitude of the input voltage causing a diode within the off-transistor to turn-on and return energy back to the power source, thereby further increasing the circuit efficiency.

RMS, DC, peak, and harmonic currents in high-frequency power-factor correctors with capacitive energy storage

Abstract: The RMS, DC, and peak currents for five important power factor correctors with capacitive energy storage are presented. The correctors are a boost power converter with average current control and hysteretic control, a buck-boost power converter with automatic control, and a buck power converter with pulse width modulation (PWM) sinewave line current and modified sinewave line current. In the calculation of the current in the storage capacitor of the boost corrector with average current control, the effect of switched load is taken into account and a simple solution is recommended to reduce that current. For those correctors where fully sinusoidal line current is not achievable the line harmonics are also determined. >

Dimmer with reduced filtering losses

Abstract: A dimmer with reduced filtering losses is connected into a conductor supplying power to a load from a mains power supply. It conventionally comprises a triac in series with a filter inductor between an input terminal and an output terminal and a circuit generating triggering signals for the triac. To reduce the losses in the inductor, which conventionally is in series with the load at all times but is active only during moments following triggering of the triac, to reduce the amplitude of the transient currents, a second triac triggered by a circuit with a time-delay greater than the time constant defined by the filter capacitor and inductor diverts the load current. An auxiliary low-value inductor attenuates transients due to triggering of the second triac.

Tapped inductor slave regulating circuit

Abstract: A tapped inductor slave regulating circuit provides a second slave output voltage derived from a tapped connection to the filter storage inductor of a first output voltage of a switching power supply converter. In the converter, an unregulated voltage is provided through a switching circuit to a storage inductor to develop a first output. The switching circuit is turned off and a synchronous rectifier is turned on to freewheel the current through the storage inductor and the load. The storage inductor is center-tapped and coupled to a switching circuit to provide a second slaved output. The location of the center tap is chosen to provide the proper voltage of the second output. In one embodiment, the switching circuit for the slaved output is turned on during the freewheel portion of each cycle to provide a proper voltage level for the second output. In another embodiment, a separate local feedback circuit is provided to further regulate the second output voltage level.

Integration of high frequency current shunts in power electronic circuits

Abstract: The principles that determine the high frequency behavior of current shunts are identified and applied to broaden the concept of shunt construction by viewing the shunt as an integrated part of the power electronic circuit. It is demonstrated that a shunt constructed from discrete components, like a number of resistors in parallel, can have bandwidth performance on a par with shunts constructed from foil. The prerequisite is that the layout and spatial orientation of the elements provide the correct field distributions. Such structures often permit easy integration as a permanent part of the power converter layout. A flat structure constructed in this way demonstrates the principles, which can readily be extended to more complex geometries. Some examples of such complex geometries are given in the form of a high-dissipation load impedance with the shunt as an integral part and a snubber inductance with a shunt integrated into its structure. The necessity for electromagnetic field analysis of the layout or component structure is demonstrated. Examples of integrated shunts are presented with analysis and experimental results. >

Characteristics and analysis of a thin film inductor with closed magnetic circuit structure

Abstract: A spiral inductor with closed magnetic circuit was fabricated by an RF sputtering machine and photolithography techniques. The inductance was twice as large as that of a reference sandwiched inductor. The authors analyzed the frequency characteristics of the proposed inductor from three points of view: inner current distribution, flux distribution, and eddy current in the magnetic film. The calculated results agree with the measured ones. It is demonstrated that the current distribution inside the inductors is mostly limited to within the area of the conductor up to several hundred megahertz. The frequency characteristics are influenced by the eddy current loss in the Permalloy film and the stray capacitance between the inductor and the ground plane. The permeability of the Permalloy film is less than that of its as-deposited state, but the closed magnetic circuit structure helps to reduce the influence of the demagnetizing field. >

Monolythic surge suppressor

Abstract: A monolythic surge suppressor includes a power source, an inductor coil, and a load in series with one another and in parallel with at least a first varistor. The first varistor and the inductance coil are formed into a single unitary laminated assembly having at least first and second terminations connected thereto. A second varistor can be connected in parallel with the first varistor and is connected to a third termination.

Zero-voltage-switching quasi-resonant converters with multi-resonant bipolar switch

Abstract: A compact, high frequency, zero voltage switching quasi-resonant converter with a multi-resonant, bi-polar switch includes a resonant switch (S), a first diode (Dp) in parallel with the switch (S), a second diode (Ds)in series with the switch (S), first (Cr1) and second (Cr2) resonant capacitors and a resonant inductor (Lr). The first resonant capacitor (Cr1) is operatively connected to the resonant switch (S) such that any voltage change across the first resonant capacitor (Cr1) necessitates a corresponding voltage change across the resonant switch (S). The second resonant capacitor (Cr2)is operatively connected to the second diode (Ds) such that any voltage change across the second resonant capacitor (Cr2) necessitates a corresponding voltage change across the second diode (Dp). The resonant inductor (Lr) is operatively connected in series with the resonant switch (S) such that any current change through the resonant inductor (Lr) necessitates corresponding changes in the sum of currents flowing through the first resonant capacitor (Cr1), first diode (Dp), and the resonant switch (S), and the sum of currents flowing through the second resonant capacitor (Cr2) and the second diode (Ds).

Ultrasonic vibration generator and use of same for cleaning objects in a volume of liquid

Abstract: An apparatus and method for ultrasonic cleaning is disclosed in which a transducer (35) in a liquid bath is driven by electronic circuitry causing rapid change of frequency to limit development of high concentration for any significant period of time. The electronic circuitry uses two field effect transistors (19 and 20) driving a square wave into an inductor (31) and capacitor (32) in series with a transformer inductor (33) which is coupled in parallel to the transducer (35) the inductor (31) and capacitor (32) and the transformer inductor (33) which is coupled in parallel to the transducer (35) being selected to be resonant at a mean driving frequency.

Planar magnetic component technology-a review

Abstract: The materials and the fabrication of planar magnetic components for switch mode power supplies (SMPSs) and other applications are reviewed. The advantages and the disadvantages of such devices are introduced. The magnetic materials used in the devices, such as ferrite, amorphous metallic glass, and thin and thick magnetic films, are detailed. The devices have varying degrees of planarization-partially planar devices with magnetic cores and planar windings and truly planar devices for integrated magnetic circuits with planar windings and planar magnetics. Devices of both types reported in the literature since 1979 are reviewed. The design of the planar magnetic components must be optimized with respect to losses, and design issues which relate to electrical, thermal, and mechanical performance are discussed. >

Starting and operating circuit for arc discharge lamp

Abstract: A circuit for starting and operating a discharge lamp, such as a compact fluorescent lamp, at high frequency from an 60 Hz AC supply. The circuit includes a DC power supply coupled to a pair of AC input terminals for generating a DC voltage. An oscillator coupled to the DC power supply includes a drive transformers having a primary winding. A load coupled to the output of the oscillator comprises a series combination of the primary winding of the drive transformer and a tank circuit including a tank inductor and a tank capacitor. Suitable means for connecting a discharge lamp in parallel with the tank capacitor is provided. A voltage sensing circuit responsive to failure of the lamp, is coupled to an oscillator controlling circuit which reduces the output of the oscillator after a predetermined time delay by shunting the drive transformer. Upon replacement of the failed lamp, normal operation of the oscillator is resumed without having to disconnect the AC supply.

Integrated converter high power CD ignition

Abstract: A high power high energy capacitive discharge (CD) ignition system for internal combustion engines using a separate resonating inductor (7) in the discharge circuit which is constructed and arranged to provide suitable operation of the discharge circuit and to allow coupling of energy from a voltage source (13a) for storage in the inductor (7) for delivery to the CD system discharge capacitor (4) during the operation of the ignition to help maintain energy during the preferred mode of multiple spark pulse firings of an ignition spark in a preferred large toroidal gap spark plug and to recharge the capacitor (4) between firings.

Microwave characterisation of microstrip lines and spiral inductors in MCM-D technology

Abstract: MCM-D (multichip module-D) technology comprising a four-level metallization, aluminum-polyimide structure defined on a silicon substrate is considered. A dedicated microwave characterization layout was designed and implemented, which included a series of microstrip lines, spiral inductors, microstrip coupling structures, ring resonators, and microwave calibration structures. Analog measurements of these structures were then carried out using RF-on-wafer methods at frequencies from 0.5 to 20 GHz. Equivalent circuit models were derived which gave a close fit to the experimental measurements, and a range of transmission line and spiral inductor components was characterized. Useful analog transmission line behavior was indicated for 10-mm line lengths to 10 GHz, while inductors were measured with primary inductances approaching 10 nH with useful Q values in the 1 -3-GHz region. Layout rules for low crosstalk were also devised. The lower metallization resistance and increased dielectric separation from the silicon substrate resulted in improved performance for these MCM-D inductors in comparison with on-chip inductors of comparable inductance. >

CuK DC-to-DC switching converter with input current shaping for unity power factor operation

Abstract: A DC voltage to a load is provided from a rectified AC power line source with unity power factor using Cuk dc-to-dc switching converter, either unisolated or isolated extensions, operated as an automatic current shaper with unity power factor performance. This is obtained by operating the Cuk converter in a discontinuous inductor current mode (DICM) at a constant switching frequency and constant duty ratio without input current feedback control customarily used, but operating in an open-loop fashion. Even though the Cuk converter is operated in DICM, its input current is nonpulsating and flowing throughout the switching cycle, unlike other converters having pulsating input current in DICM, thus reducing input harmonic currents due to switching frequency and its harmonics. Further improvement is obtained and even the remaining ripple in the input current is entirely eliminated to result in ideal, clean, harmonic-free input current waveform with unity power factor performance, when the coupled-inductor and/or integrated magnetics extensions of the Cuk converter conditions are implemented. They could be operated at low to moderate switching frequency, thus providing high efficiency and without the need for additional input filtering customarily used in other converters.

Acoustic resonator filter with electrically variable center frequency and bandwidth

Abstract: An acoustic resonator filter having at least one of electronically variable center frequency and bandwidth has a shunt coupling consisting of an inductor and voltage variable capacitor matrix. A pair of acoustic resonators each having a parallel inductor are connected to each other and to the shunt coupling network. One of a pair of voltage variable capacitor matrixes each having a center frequency command input voltage is connected to each acoustic resonator and an associated inductor. This circuit can be extended to provide more selectivity and attenuation.

Method and apparatus for tuning and aligning an FM receiver

Abstract: A method for tuning and aligning an electronically tuned FM broadcast receiver is described. The system described compensates for the mismatch of component values between the antenna and RF amplifier tuned circuits, and the IF offset between the local oscillator frequency and the center frequencies of the antenna and RF resonant circuits by developing independent tuning signals for the circuits. The system also provides temperature compensation, and can be aligned without mechanically adjusting inductors and/or capacitors in the tuned circuits.

Snubber circuit for power converter

Abstract: PURPOSE:To obtain a snubber circuit for realizing a highly efficient power converter wherein recovery current flowing through a switching element and a diode is limited and switching loss of the switching element is suppressed. CONSTITUTION:In a power converter comprising a switching element 4, a DC reactor 7 and a load 8 connected in series between power supply terminals 2, 3, and a diode 5 connected in parallel with the DC reactor 7 and the load 8, an inductor 46 is connected between the switching element 4 and the diode 5, a series circuit of a diode 44, an inductor 42 and a diode 44 is connected between the power supply terminals 2, 3, and a capacitor 43 is connected between the joint 48 of the inductor 42 and the diode 44 and the joint 46 of the switching element 4 and the inductor 46.

Integrated common mode and differential mode inductor device

Abstract: An integrated EMI/RFI Filter Magnetic has differential and common mode inductors wound about an I-Core. The I-Core is juxtaposed with an E-Core, with the end surfaces of the E-Core legs facing the I-Core. The magnetic has a substantially closed magnetic path for the differential inductors and the common mode inductors.