Showing papers on "Inductor published in 1993"

Large suspended inductors on silicon and their use in a 2- mu m CMOS RF amplifier

Abstract: Large spiral inductors encased in oxide over silicon are shown to operate beyond the UHF band when the capacitance and loss resistance are greatly reduced by selective removal of the underlying substrate. Using a 100-nH inductor whose self-resonance lies at 3 GHz, a balanced tuned amplifier with a gain of 14 dB centered at 770 MHz has been implemented in a standard digital 2- mu m CMOS IC process. The core amplifier noise figure is 6 dB, and the power dissipation is 7 mW for a 3-V supply. >

Small-signal modeling of average current-mode control

Abstract: A recently proposed average current-mode control method is analyzed. A complete small-signal model for the control scheme is developed. The model is accurate up to half the switching frequency. This control scheme is suitable for applications where the average inductor current needs to be controlled, as in power factor correction circuits and battery charger dischargers. The subharmonic oscillation, commonly found in peak current-mode control, also exists in this method. This subharmonic oscillation can be eliminated by properly choosing the proper gain of the compensation network in the current loop. Model predictions are confirmed experimentally. >

Power-factor correction with interleaved boost converters in continuous-inductor-current mode

Abstract: The operation and design trade-offs of the interleaved boost converter in continuous inductor-current mode in a high-power-factor preregulator circuit are investigated. By using interleaved converters, an overall reduction of boost inductor and electromagnetic interference (EMI) filter volume can be achieved, together with reduced switching losses. The problem of unequal load sharing between the interleaved power stages with average current control is pointed out, and a practical solution is recommended. EMI filter design considerations and experimental data taken from a 3 kW converter are presented. >

Energy-conservation approach to modeling PWM DC-DC converters

Abstract: A systematic method is presented for including parasitic resistances and offset voltage sources of power switches in averaged dynamic large-signal, DC, and small-signal circuit models of pulse-width modulated (PWM) converters operating in continuous conduction mode (CCM). This method is based on the principle of energy conservation. The approach takes into account the inductor current ripple. For zero-ripple current, the method gives the same results as the state-space averaging method. Reflection rules are introduced and used to simplify the models. As an example, a modeling procedure for the PWM buck converter is detailed. >

An improved full-bridge zero-voltage-switched PWM converter using a saturable inductor

Abstract: The saturable inductor is employed in the full-bridge (FB) zero voltage switched (ZVS) pulse width modulated (PWM) power converter to improve its performance. The current and voltage stresses of the switches as well as parasitic oscillations are significantly reduced compared to those of the conventional FB-ZVS-PWM power converter. The qualitative analysis is presented and is verified on a 500 kHz, 5 V/40 A converter. >

Copper laser modulator driving assembly including a magnetic compression laser

Abstract: A laser modulator (10) having a low voltage assembly (12) with a plurality of low voltage modules (14) with first stage magnetic compression circuits (20) and magnetic assist inductors (28) with a common core (91), such that timing of the first stage magnetic switches (30b) is thereby synchronized. A bipolar second stage of magnetic compression (42) is coupled to the low voltage modules (14) through a bipolar pulse transformer (36) and a third stage of magnetic compression (44) is directly coupled to the second stage of magnetic compression (42). The low voltage assembly (12) includes pressurized boxes (117) for improving voltage standoff between the primary winding assemblies (34) and secondary winding (40) contained therein.

Lightweight high power electromotive device

Abstract: An electromotive device (10) is disclosed which utilizes stacks of oriented magnetic material as stator bars (40). Electrical conductors (38) are wound about the stator bars (40) to create a stator inductor (36). The stator bars (40) are generally configured to shield the electrical conductor winding (38) from electromagnetic forces and further, to provide a first flux return path for the magnetic flux created by magnets (34) fixed to a rotor (32) formovement with respect to the stator inductor (36).

Single stage, high power factor, gas discharge lamp ballast

Abstract: A gas discharge lamp ballast provides near unity power factor simultaneously with high-frequency lamp ballasting in a single switching power conversion stage resulting in efficiency improvements, reduction in size and weight and reduced component count and cost. The single conversion stage comprises a fast-recovery diode connecting in series the input inductor, energy transfer capacitor and the resonant matching network, and switching means alternately connecting the first junction between the input inductor and energy transfer capacitor, or the second junction between the matching network and the other side of said capacitor to the return current path. The switching means comprises two current bidirectional switches driven out of phase, thus producing a square-wave high frequency voltage source, which is in turn converted by the resonant matching network into a sine-wave ac current source required by the gas discharge lamp. The fast-recovery input diode in conjunction with the input inductance chosen to be less than the critical inductance value forces the input inductor current into a new discontinuous inductor current mode (DICM). The average input inductor current is shown to closely follow the rectified line voltage when the ballast is operated at the constant duty ratio and at the constant switching frequency either open-loop or with the slow feedback loop of conventional PWM control. Zero voltage switching for the two current bidirectional switches is achieved by introducing two transition intervals during which both switches are OFF and utilizing the negative value of the lagging current of the matching network above resonance.

Superconducting magnetic resonance probe coil

Abstract: A magnetic resonance probe coil (20) is made of a spiral inductor (22) consisting of several turns of a superconducting film (24). Distributed throughout the inductor are interdigital capacitive elements (26). The turns of superconducting film (24) may be literally a spiral, or they may be concentric circles, slit over short parts of their circumference, and connected with primarily radial segments joined to effect a functional spiral.

A comprehensive design approach for a three-phase high-frequency single-switch discontinuous-mode boost power factor corrector based on analytically derived normalized converter component ratings

Abstract: In this paper the peak, mean, and RMS values of the component currents of a three-phase single-switch discontinuous inductor current mode boost rectifier are calculated analytically. The values are given in rated form in dependency on the output power and on the ratio of output voltage to the amplitude of the mains voltage. Furthermore, the influence of the voltage transfer ratio on the shape of the mains currents and on the power factor of the system is analyzed. The theoretical analysis is verified by digital simulation and a good consistency is achieved. Finally, the approach of the converter dimensioning based on the graphical representation of the calculation results is described and illustrated using a specific example. The correctness of the dimensioning is verified by measurements on a laboratory model. >

Methods for fabrication of thin film inductors, inductor networks and integration with other passive and active devices

Abstract: The fabrication of thin film inductors on a substrate, which may include thin film resistors, thin film capacitors, and semiconductor devices. In one embodiment an inductor is fabricated initially on a substrate and then integrated with other devices subsequently formed on the substrate. In this embodiment, process steps used to fabricate such other devices utilize temperatures sufficiently low to prevent damaging or destroying the characteristics of the inductor. In another embodiment the fabrication of an inductor is achieved through photoresist masking and plating techniques. In alternative embodiments, fabrication of an inductor is achieved by sputtering, photoresist processes and etching/ion-milling techniques. A combination of various individual process steps from various embodiments are suitable for use to fabricate the individual layers to achieve a structure of this invention. The inductor fabricated in accordance with this invention is connected to other passive or active components through metal interconnections in order to improve the frequency performance of the inductor. In certain embodiments, parasitic capacitance of the inductor is significantly reduced by fabricating inductor coils on dielectric bridges. In certain embodiments, a magnetic core of ferromagnetic material is used to improve the performance of the inductor at frequencies below about 100 MHz.

Single-switch three-phase power factor preregulator under variable switching frequency and discontinuous input current

Abstract: A three-phase power factor preregulator with input inductor, diode bridge, and a single switch is analyzed. Operation with discontinuous input current and variable switching frequency is considered. Equations for average input current are presented, showing that quasi-sinusoidal waveforms are obtained. Also, the switching frequency equation shows an almost constant frequency operation. A design procedure is presented, where simulation and practical results show the good performance of the approach. Comparison with constant frequency operation also shows that a better harmonic distortion is obtained if the voltage in the switch (with switch off) is not far from the input voltage. Also, in this case, the high-order harmonic content is easily filtered. >

Automatic current shaper with fast output regulation and soft-switching

Abstract: A new utility-to-DC, harmonic-free interface combines the functions of automatic input current shaping, fast output voltage regulation, and lossless, soft switching in a single power converter. This was made possible through internal energy storage and the discovery of new modes of operation, which together, effectively decoupled the input boost-like part of the Cuk converter from its buck-like output. Experimental results obtained on a 50 W-12 V prototype confirm the fast output regulation (30 kHz bandwidth for 100 kHz switching frequency) simultaneously with low-harmonic line current waveforms. >

A primary inductive pathway

Abstract: A primary inductive track or path (450) for a resonant inductive power distribution system is made up from a number of modules (453), each supplied as a pre-built and substantially pre-tuned segment of the track. These modules have more than one capacitor (456, 457) and more than one inductance (458, 459) (generally, the inductance is the intrinsic inductance of the length of track) and each capacitor and adjacent inductor is capable of resonating at its own native frequency. A zero-inductance cable (452) carries a small fraction of the circulating resonant current (comprising a mismatch or an error current), directly connects the capacitors at poles having equal polarity and tends to constrain the system limiting possible frequencies of resonance.

Average simulation of PWM converters by direct implementation of behavioral relationships

Abstract: Average modeling of PWM power converters is reexamined in the light of the behavioral dependent sources now included in modern versions of electronic circuit simulators. A topology independent behavioral model is developed to emulate the operation of PWM converters in voltage and current modes, for continuous and discontinuous inductor current cases. It is shown that, in general, the operation of the switching part involves three behavioral blocks, i.e., the generic switched inductor model (GSIM), the duty cycle generator (DCG), and the inductor current generator (ICG). Explicit expressions and equivalent circuits are developed for all possible modes of operation. >

Optimized high power high energy ignition system

Abstract: A high power high energy ignition system for internal combustion engines using an energy storage capacitor (4), resonating inductor (3) and one or more coils Ti with switches Si for each coil Ti. The system is designed and optimized according to the transient voltage doubling formulation and certain coil magnetic flux formulations to produce a very high power, very high energy, high efficiency ignition powered and controlled by a power converter (14) and controller (15) to produce an initial high frequency spark pulse followed by moderate firing longer duration spark pulses or continuously firing spark oscillations for delivery to the air-fuel mixture of an engine with total spark energy approximately independent of engine speed. The energy is delivered by means of a toroidal gapped spark plug (46) with extended electrodes (48a) to maximize ignition kernel size and minimize spark plug erosion and fouling.

Current-sourcing push-pull parallel-resonance inverter (CS-PPRI): theory and application as a fluorescent lamp driver

Abstract: A novel topology, current-sourcing push-pull parallel-resonance inverter (CS-PPRI), is investigated theoretically and experimentally. The proposed power stage is built around a current fed push-pull inverter. The main features of the proposed inverter are a load-independent output current and zero voltage switching (ZVS). It is suggested that the proposed CS-PPRI is a viable alternative for realizing electronic ballasts for low and high intensity discharge lamps. >

Unipolar series resonant converter.

Abstract: A high efficiency static series resonant converter (22, 100, 200, 300) and method for converting power between two electric AC and/or DC circuits (24, 25; 124, 125; 224, 25; 24, 325) includes a resonant tank (60, 160) coupled to a link current synthesizer (70) for generating a train of unipolar link current pulses (Fig. 7) with controllable duration zero and nonzero current segments. A blocking switch (80) deactivates oscillation of the resonant tank (60, 160) in initiating each link current pulse, which is subsequently clamped by a buffer inductor (95). Each pulse is terminated by natural commutation through resonant oscillation. The pulses are substantially squarewave and have a high duty cycle leading to minimal peak current values. Minimal switching losses are incurred by switching at substantially zero voltage and zero current. Other features include blackout ride-through capability, bi-directional four quadrant operation, unbalanced load operation, voltage step-up without transformers, and input and output switch assemblies (40, 50; 40, 150; 240, 50; 340, 50) constructed from unidirectional switches, such as low-cost and robust single thyristors.

Constant frequency, zero-voltage-switching converters with resonant switching bridge

Abstract: A novel, compact, converter structure utilizes a switching bridge configuration to provide a low voltage stress, constant frequency controlled converter whose switches and diodes all turn-on and turn-off with zero-voltage-switching. The novel converter configuration uses a full-bridge switching circuit comprising four diodes D1 -D4 and, in one embodiment, four active semiconductor switches S1 -S4. A resonant inductor Lr is connected across the bridge nodes a and b, and parasitic capacitance of the diodes and active switches S1 -S4 are incorporated in an L-C circuit. Connected in parallel with the bridge is a voltage source or sink, depending on the direction that power will flow; and connected to node a or b is a current source or sink, again depending upon the direction of power flow. The present invention stores sufficient energy in the resonant inductor Lr so that prior to each switch or diode commutation, charge present on the corresponding parasitic capacitance of that semiconductor may be removed by the current drawing action of the resonant inductor Lr. In this way, all diodes D1 -D4 and active switches S1 -S4 operate with zero-voltage-switching. The novel bridge configuration directs the power flow from the source to the load, while passively guaranteeing voltage limitation across each diode and switch, and providing volts-seconds balance for the resonant inductor Lr.

A simple and efficient synchronous rectifier for forward DC-DC converters

Abstract: A simple and efficient MOSFET synchronous rectification circuit suitable for forward DC-DC power converters is proposed. The main feature of this circuit is the addition of a capacitor in parallel with the drain source of the MOSFET used as a rectifying device. This capacitor extends the conduction period of the MOSFET used as a freewheeling device. As a result, a 92% efficiency at 5 V for 10 A output is achieved. >

Power supply circuit with power factor correction

Abstract: A power supply circuit for powering a load with bi-directional current comprises means for supplying d.c. power from an a.c. voltage, a series half-bridge converter, and a boost converter. The series half-bridge converter alternately impresses a d.c. bus voltage from a bus conductor across a load circuit first with one polarity and then with the opposite polarity. The series half-bridge converter includes a first switch interposed between the bus conductor and a bridge-switch end of the load circuit; a second switch interposed between ground and the bridge-switch end of the load circuit; and a switching control circuit for alternately switching on the first and second switches. The boost converter comprises a boost capacitor connected between the bus conductor and ground and whose level of charge determines the bus voltage on the bus conductor; a boost inductor for storing energy from the means for supplying d.c. power, the boost inductor being connected by a one-way valve to the boost capacitor for discharging its energy into the boost capacitor; and means for periodically connecting a load end of the boost inductor through a low impedance path to ground, such path including a boost switch. A condensed power supply circuit results from making the second switch of the series half-bridge converter additionally serve as the boost switch. An alternative circuit simplification results from making constant the ratio of on time to switching repetition period of the boost switch.

A planar micromachined spiral inductor for integrated magnetic microactuator applications

Abstract: In this work, planar micromachined spiral inductive structures with relatively high inductance at low (Hz-kHz) frequencies are designed and fabricated for integrated magnetic microactuator applications and other purposes. Two types of multilayer micromachined inductors have been investigated. The first structure is a standard planar inductor spiral. To this structure we have added an electroplated high-permeability nickel-iron (Ni/Fe) magnetic core, which forms a central core to concentrate flux and completely encapsulates the windings, thus minimizing magnetic interference. For a typical 36-turn device 3 mm*3 mm in area, an inductance of approximately 20 mu H was obtained. The structure with a magnetic core has an inductance four to five times greater than a similar structure without a magnetic core. The specific inductance of our structure (inductance per unit area) is 2.2 mu H mm-2 at 10 kHz, which is one of the highest inductance values ever achieved in an integrated planar inductive component at low frequency. Since the structure of the spiral-type inductor is similar to those of planar magnetic microactuators such as micropumps, microvalves and microrelays, several low-frequency microactuator applications are expected to be possible with this inductor.

Series resonant converter having a resonant snubber

Abstract: A fixed frequency, series resonant converter having a resonant snubber comprising an inductor and capacitor connected across a tank circuit of the converter. An optimum amount of inductance in the resonant snubber minimizes the degree of "shoot-thru," or conduction through a body-diode within a transistor switch of the converter caused by ringing, which allows for nearly sinusoidal current to be provided to a full bridge high voltage rectifier enabling the power converter to operate at a higher frequency. An alternate embodiment applies the resonant snubber only across a selected transistor switch.

Forward converter with two active switches and unity power factor capability

Abstract: A power converter integrates an input boost converter and an output forward converter into a single power stage utilizing only two active switches. AC input power is provided through a rectifier to an input inductor which supplies current to a main node. The diode is connected from a main node to a DC bus supply line and current is returned to the rectifier by DC bus return line. An energy storage capacitor and a series connected switching device and diode are connected across the DC bus lines. A second control switching device is connected from the main node to the DC bus return line. The primary of a high frequency transformer is connected between the main node and the junction between the first switching device and diode, and the secondary of the transformer is connected to an output circuit which includes a rectifier and an inductor and capacitor filter to provide a DC output voltage to a load. When both switching devices are turned off, current from the input inductor is supplied to charge up the energy storage capacitor and to drive the transformer magnetizing current to zero. Turn on of both switching devices causes the capacitor to be discharged via the switching devices through the primary of the transformer to supply power to the load. Intermediate modes in which one or the other of the switching devices is on while the other is off are available. By proper selection of the time of turn on of the devices and the modes of switching of the devices, the AC input current can be controlled to be substantially sinusoidal, or the output voltage can be controlled to a selected level, and in either event the power factor as seen at the AC input lines is substantially unity.

Power converters with improved switching efficiency

Abstract: A Circuit for reversing the direction of current flow in a rectifying device of a power converter during a time interval just prior to when the rectifying device is to be rendered non-conductive is described. The current reversal substantially reduces or eliminates reverse-recovery currents in the rectifying device, which may cause short circuits and needlessly dissipates power. The circuit comprises an energy source, a magnetic storage device, and a switch for coupling the magnetic storage device to the energy source. The magnetic storage device may comprise an inductor or a transformer. The energy source may include a voltage source, the converter's input voltage, the output voltage, or a winding magnetically coupled to another magnetic storage device of the converter. The reversal circuit includes a circuit for coupling the reversing current to the rectifying device such that it partially or completely reverses the flow of current in the rectifying device.

Low-power-dissipation CMOS oscillator circuits

Abstract: Low-power-dissipation CMOS oscillator circuits include inductors (16,18) and capacitors (26,28,30) forming tank circuitry. Cross-connected MOS devices (10-12) provide positive feedback to replenish losses in the tank circuitry and thereby sustain oscillations. Each such oscillator circuit simultaneously generates complementary output sine-wave signals (at 22,24).

A comparison between hysteretic and fixed frequency boost converters used for power factor correction

Abstract: A hysteretic controlled boost power converter is compared to a fixed frequency boost converter. The decision of which circuit to be used in electronic products is often based upon cost, size, heat rise, availability of components, and complexity of the design. The advantages and disadvantages of the hysteretic control and fixed frequency boost converter using 400 W as a load operating from 90 VAC to 270 VAC are providing 450 V to the output electrolytic capacitor are presented. >

The effects of series inductors for flicker reduction in electric power systems supplying arc furnaces

Abstract: The effect of a series inductor on the reduction of voltage flicker in electric power systems supplying arc furnaces is assessed. The arc furnace is simulated as a voltage generator with variable amplitude during the melting process. The design of the inductor hinges on the fact that, when connected into the electric power system, it should not interfere with the production capacity of the plant itself. The use of a powerful simulation program (EMTP) makes it possible to study a large number of cases and therefore to determine the appropriate size of the series inductor for the purpose of reducing voltage flicker. The simultaneous presence of the series inductor with capacitors and/or filters, with the purpose of limiting harmonic pollution and improving the power factor, is also discussed. >

A nonlinear transmission line model for superconducting stripline resonators

Abstract: A nonlinear transmission line model is used to explain the nonlinear frequency response at high input power levels of stripline resonators fabricated with superconducting NbN and YBa/sub 2/Cu/sub 3/O/sub 7-x/ thin films. The resonator is modeled as a transmission line with a nonlinear inductance and resistance. The inductor flux and resistor voltage drop are assumed to be odd polynomial functions of the transmission line current, and the polynomial coefficients are adjusted to match the measured data. Excellent agreement is found between the measured and calculated results. >

A novel ZCS-ZVS-PWM DC-DC buck converter for high power and high switching frequency: analysis, simulation and experimental results

Abstract: A DC-to-DC power converter using a zero current switching zero voltage switching PWM (ZCS-ZVS-PWM) cell for high switching frequency and high power operation is presented. The proposed cell consists of only one main switch, plus an auxilliary switch, with ZVS and ZCS switching characteristics, respectively. These switches, associated with a resonant inductor and capacitor, yield zero voltage and zero current switching, providing highly efficient operating conditions for a wide range of power at high switching frequency. Converter control is accomplished by using the PWM technique, with constant frequency operation. A complete analysis of the operating principles, including output characteristics, relevant equations, state space phase, simulation, and experimental results for the buck power converter, is presented. >