Showing papers on "Rectifier published in 1991"
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01 Jan 1991
TL;DR: In this paper, the authors present a review of semiconductor devices and their properties, including gate and base drives, and power transistors, as well as feedback control design and an overview of ancillary issues.
Abstract: 1. Introduction. 2. Form and Function: An Overview. 3. Introduction to Rectifier Circuits. 4. Bridge and Polyphase Rectifier Circuits. 5. Phase-Controlled Converters. 6. High-Frequency Switching dc/dc Converters. 7. Isolated High-Frequency dc/dc Converters. 8. Variable-Frequency dc/ac Converters. 9. Resonant Converters. 10. ac/ac Converters. 11. Dynamics and Control: An Overview. 12. State-Space Models. 13. Linear and Piecewise Linear Models. 14. Feedback Control Design. 15. Components: An Overview. 16. Review of Semiconductor Devices. 17. Power Diodes. 18. Power Transistors. 19. Thyristors. 20. Magnetic Components. 21. Ancillary Issues: An Overview. 22. Gate and Base Drives. 23. Thyristor Commutation Circuits. 24. Snubber Circuits and Clamps. 25. Thermal Modeling and Heat Sinking.
1,104 citations
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05 Nov 1991
TL;DR: In this article, a snubber circuit for the constant frequency PWM boost converter is presented to provide soft switching transitions for the power switches and thus to reduce the power losses, component stresses, and noise generation.
Abstract: A novel snubber circuit for the constant frequency pulsewidth-modulation (PWM) boost converter is presented to provide soft-switching transitions for the power switches and thus to reduce the power losses, component stresses, and noise generation. The proposed topology is very useful for the input current shapers in AC-AC applications. The operation of the circuit including its control block is explained and illustrated for a 1.5 kW, 100 kHz high-performance power-factor-corrected telecommunication rectifier. >
190 citations
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24 Jun 1991TL;DR: In this article, a new control strategy is presented to selectively cancel the generated lower-order abnormal harmonics at the output and input terminals and thereby to preserve the high-performance features of a PWM AC-to-DC power converter.
Abstract: Abnormal harmonics of significant magnitude are generated at the output and input terminals of a PWM (pulse-width-modulated) AC-to-DC power converter under unbalanced operating conditions. A new control strategy is presented to selectively cancel the generated lower-order abnormal harmonics at the output and input terminals and thereby to preserve the high-performance features of a PWM AC-to-DC power converter. The proposed technique essentially involves computing the sequence components of the unbalanced input supply and suitably counter-unbalances the PWM gating signals of the power converter switches to cancel the generated abnormal harmonics. The technique is essentially a feedforward approach and is suitable for higher-power GTO (gate turn-off thyristor) type PWM AC-to-DC power converters. A procedure for implementing this technique in real time is discussed. Selected results are verified experimentally on a prototype PWM AC-to-DC power converter. >
155 citations
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01 Jan 1991
TL;DR: In this article, the output rectifier is replaced by an active switch to eliminate the undesirable variable switching frequency of CF-QR converters, which is applicable to all classes of converters.
Abstract: An additional independent control needed to eliminate the undesirable variable switching frequency of quasi-resonant (QR) converters is obtained by replacing the output rectifier by an active switch. The concept is applicable to all classes of converters. Compared to QR converters with conventional switch realization, constant-frequency quasi-resonant (CF-QR) converters exhibit the same type of switching transitions and similar switch voltage and current stresses. Advantages of CF-QR converters are not restricted to the constant-frequency control. In all classes, operation at zero load is possible, so that the available load range is unlimited. The range of attainable, conversion ratios is significantly extended in the classes of zero-voltage quasi-square-wave (CF-ZV-QSW) and zero-voltage multiresonant (CF-ZV-MR) topologies. A practical design example of a 25 W CF-ZV-MR buck converter is constructed and evaluated. The converter operates at 2 MHz from zero load to full load, with a full-load efficiency of 83%. Simple duty ratio control is used to maintain the output voltage constant for all loads. The circuit is inherently immune to the short-circuit condition at the output. Disadvantages of CF-QR converters are the increased gate-drive losses and increased complexity of the power stage and the control circuitry. >
129 citations
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10 Mar 1991TL;DR: In this article, the performance of the parallel resonant converter and the combination series/parallel resonant converters when operated above resonance in a high power factor mode is determined and compared for single-phase applications.
Abstract: The performance of the parallel resonant converter and the combination series/parallel resonant converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single-phase applications. When the DC voltage applied to the input of these converters is obtained from a single-phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behaviour is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near unity power factor and low input harmonic currents can be obtained. >
107 citations
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01 Sep 1991TL;DR: In this article, a novel semicontrolled switch mode rectifier (SMR) topology is proposed and analyzed, and its advantages when compared with other existing SMR topologies are high true power factor at the AC source (almost unity), high displacement power factors at the input of the SMR unit, high efficiency, low implementation cost and high power density.
Abstract: A novel semicontrolled switch mode rectifier (SMR) topology is proposed and analysed. Its advantages when compared with other existing SMR topologies are high true power factor at the AC source (almost unity), high displacement power factor at the input of the SMR unit (almost unity), high efficiency, low implementation cost and high power density.
97 citations
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10 Jun 1991TL;DR: A voltage-doubler rectifier as mentioned in this paper includes an ac full-bridge diode rectifier and a dc-to-dc converter having two output boost circuits, one of which is coupled between the rectifiers and the dc link, and the other one is coupled, with opposite polarity, between the Rectifier and the circuit common.
Abstract: A voltage-doubler rectifier includes an ac fullbridge diode rectifier and a dc-to-dc converter having two output boost circuits. One of the output boost circuits is coupled between the rectifier and a dc link, and the other output boost circuit is coupled, with opposite polarity, between the rectifier and the circuit common. Two series-connected filter capacitors are also coupled between the dc link and the circuit common. In a preferred embodiment, the two output boost circuits each comprise either a series, parallel, or combination series/parallel resonant circuit and a rectifier. A switch is coupled between the junction joining one pair of diodes of the rectifier and the junction joining the two filter capacitors. For a relatively high ac line voltage, the switch is open, and the circuit operates in a low boost mode. For a relatively low ac line voltage, the switch is closed, and the circuit operates in a high boost, or voltage-doubling, mode.
81 citations
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05 Nov 1991TL;DR: In this article, the authors present a current waveform improvement method, based on the dither effect normally used in the linearization of nonlinear functions, which utilizes this principle to linearize the dead-zone characteristic which is present in the input of capacitor input rectifiers.
Abstract: The authors present a current waveform improvement method, based on the dither effect normally used in the linearization of nonlinear functions. The proposed circuit utilizes this principle to linearize the dead-zone characteristic which is present in the input of capacitor input rectifiers. The principal characteristics of this method are its simple composition and, more importantly, that it avoids the need for current control. The same switching device realizes the input current waveform improvement and the high frequency inverting output. The experimental circuit achieved over 99% input power factor and current distortion below 9%. >
79 citations
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TL;DR: In this article, the performance of the clampedmode series resonant converters (CMSRC) is studied for an offline application, and two prototypes are designed and tested experimentally, one to operate below resonant frequency (mode B) and the other to operate above resonant frequencies (mode A).
Abstract: The performance of the clamped-mode series resonant converters (CMSRC) is studied for an offline application. The CMSRC has the advantage of fixed-frequency operation, resulting in an easier design of magnetic components for resonant tank and filtering. Two prototypes were designed and tested experimentally, one to operate below resonant frequency (mode B) and the other to operate above resonant frequency (mode A). The efficiency is mainly determined by the rectifier losses and the switching losses. Where mode-B operation is implemented (below resonant frequency), the recovery of the diodes greatly increases the turn-on losses of the devices. The operation mode with four switches turned on at zero voltage, mode A' at above resonant frequency, shows better efficiency. Therefore, if higher frequencies of operation are desired, mode A' is the better choice among the four modes of operation discussed. >
74 citations
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28 Sep 1991TL;DR: In this article, a control method for current-type PWM AC-to-DC converters that realizes a sinusoidal AC input current and unity power factor is discussed in detail.
Abstract: A control method for current-type PWM AC-to-DC converters that realizes a sinusoidal AC input current and unity power factor is discussed in detail. In such converters, an LC filter placed on the AC side may cause a resonant problem, especially in the transient condition. To overcome this problem, state feedback control is introduced, and a control strategy suitable for DC-output current control as well as AC-side current control is proposed. Circuit parameters and feedback coefficients in the AC-side current control system are optimized on the basis of an analysis in which the system is treated as a sampled-data system. A method of investigating parameters in the DC-side current control system is shown. To confirm the effectiveness of the control strategy and the validity of the analytical results, an experimental investigation of the basic characteristics of the system is made. As an example, this system is applied to controlling the current waveform in the reactor. The experimental results for this application are also included. >
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04 Apr 1991TL;DR: In this paper, a single-phase, soft-switching, ac-to-dc power converter comprises a rectifier for receiving and rectifying an ac voltage and providing the rectified ac voltage to a boost dc-todc converter, which in turn is coupled to an active clamped resonant dc link (ACRDCL).
Abstract: A single-phase, soft-switching, ac-to-dc power converter comprises a rectifier for receiving and rectifying an ac voltage and providing the rectified ac voltage to a boost dc-to-dc converter, which in turn is coupled to an active clamped resonant dc link (ACRDCL). Resonant oscillations of the resonant dc link circuit comprising an inductor and a capacitor are maintained via control of an active clamp switching device. Soft-switching in a discrete pulse modulation scheme is achieved by controlling the switching instants of a boost switching device to occur at zero voltage instants of the resonant dc link. Alternatively, if a pair of snubber capacitors are added to the boost converter, soft-switching may be achieved in a pulse width modulation mode, resulting in reduced subharmonics even at higher frequencies and with smaller filter components.
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05 Nov 1991
TL;DR: In this paper, the theoretical minimum losses of synchronous rectifiers for a forward power converter with resonant reset were analyzed under the assumption of ideal gate-drive waveforms. But the analysis showed that the gate charge and on-resistance of the current generation of power MOSFETs are low enough to yield a significant increase in rectifier efficiency, and the effects of parasitic circuit inductances on the gate voltage waveforms were shown.
Abstract: The application of MOSFET synchronous rectifiers (SRs) to a forward power converter with resonant reset is analyzed. Under the assumptions of ideal gate-drive waveforms, the theoretical minimum losses are determined. The analysis shows that the gate charge and on-resistance of the current generation of power MOSFETs are low enough to yield a significant increase in rectifier efficiency. Two simple gate drive circuits are presented, and the effects of parasitic circuit inductances on the gate voltage waveforms are shown. The measured converter losses for these SR drive circuits are compared to the losses for the Schottky rectifiers, as well as to the theoretical minimum losses. For the 3.3 V output at load currents between 5 and 10 A, the losses approach the theoretical minimum. For higher load currents, the MOSFET body-drain diode causes losses during its reverse recovery, due to the nonideal timing of gate drive voltages. >
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18 Jan 1991
TL;DR: In this article, a bi-directional transmission of data between a master system and a slave system using a single transmission antenna and a single reception antenna each tuned to the same frequency is considered.
Abstract: A device for the bi-directional transmission of data between a master system and a slave system uses a single transmission antenna and a single reception antenna each tuned to the same frequency; the master system comprises first data transmission circuits for transmitting first data to the slave system by modulating an electromagnetic signal at the frequency; detection circuits for detecting, during the transmission of the electromagnetic signal, variations in electrical characteristics of the master system induced by a modulation of the impedance of the slave system as a function of second data to be transmitted from the slave system to the master system; and restoring circuits for restoring the second data on the basis of the detected variations; and the slave system comprises reception circuits connected to the reception antenna for restoring the first data; a rectifier circuit connected across the reception antenna for rectifying an electrical signal induced in the reception antenna by the electromagnetic signal; a power supply circuit connected to the rectifier circuit for powering the circuits and the loads of the slave system with a DC voltage on the basis of energy from the rectified electrical signal; and a switching circuit connected in series between the rectifier circuit and the power supply circuit to modulate the real part of the impedance of the slave system between a high value and a low value when the switching circuit is driven in its opened and closed position by a control signal representative of the second data.
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01 May 1991TL;DR: In this paper, a three-phase flyback AC-DC convertor with step-up and stepdown characteristics of output voltage is described, which has a near unity power factor.
Abstract: A three-phase flyback AC-DC convertor which has the step-up and step-down characteristics of output voltage, is described. The introduction of pulsewidth modulation makes it possible to obtain the sinusoidal supply currents with a near unity power factor. Three gate-turn-off thyristors provide the necessary control over the currents for unidirectional power flow. To improve upon the oscillatory transient operations, the tested system includes the digital PID controller using a microcomputer for output voltage regulations. The experimental results and state-space simulations confirm the usefulness of the presented convertor. >
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04 Dec 1991TL;DR: In this article, a voltage regulating system for a permanent magnet alternating current generator that has a rotor and a three phase Y-connected output winding is presented. But the system has only two rectifiers, a first and a second full wave bridge rectifier, each comprised of a plurality of controlled rectifiers.
Abstract: A voltage regulating system for a permanent magnet alternating current generator that has a rotor and a three phase Y-connected output winding. The system has first and second three phase full wave bridge rectifiers each comprised of a plurality of controlled rectifiers. The ends of the phase windings of the output winding are connected to the AC input terminals of the first bridge rectifier. The phase windings are connected to taps and these taps are located between the neutral and the ends of the phase windings. The taps are connected to the AC input terminals of the second bridge rectifier. The first bridge rectifier is enabled and the second bridge rectifier is disabled at speeds of rotation of the rotor below a predetermined speed. At rotor speeds above the predetermined speed, the first bridge rectifier is disabled and the second bridge rectifier is enabled.
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01 Nov 1991
TL;DR: In this article, a detailed rectifier model based on a piecewise linear digital simulation is presented, particularly suitable for prediction of fault current profiles owing to closeup faults, and the accuracy is demonstrated by comparison with a case study of a practically measured fault current profile.
Abstract: Short circuits applied close to substations cause large transient peak fault currents, but remote faults are difficult to detect because the fault current may be less than a normal train load. It is important to be able to predict the form of both closeup and remote fault currents for design of new protection systems and to assess the suitability of particular protection arrangements for specific railways sites. The model of the substation rectifier is an essential part of any means of predicting the current profiles. A detailed rectifier model based on a piecewise linear digital simulation, particularly suitable for prediction of fault current profiles owing to closeup faults is presented. The accuracy is demonstrated by comparison with a case study of a practically measured fault current profile. It is shown that commonly used models based on simpler equivalent circuits can not match the accuracy of the detailed model. It is also shown that a simple DC power source model of a rectifier is appropriate for remote fault calculations because the profile is not significantly affected by the switching action of the rectifier. The validity of the simpler model is demonstrated by comparing the simple model with the more detailed one.
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01 Jan 1991TL;DR: In this paper, a DC ripple reinjection technique was used to convert the standard 12-pulse HVDC convertor group into a 24-pulses configuration, which is shown to eliminate the 12pulse related harmonics.
Abstract: A technique known as DC ripple reinjection, which has already been shown capable of operating a six-pulse rectifier effectively as a twelve-pulse convertor, is extended in the paper to convert the standard twelve-pulse HVDC convertor group into a 24-pulse configuration. Theoretical and experimental results are provided to demonstrate that the modified convertor configuration eliminates the 12-pulse related harmonics on both sides of the convertor.
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TL;DR: In this article, the effect of voltage unbalance on the rectifier output voltage is examined, and a specific practical solution for the elimination of the triplen input current harmonics is proposed.
Abstract: The authors analyze the effect of input voltage unbalances on the rectifier input current and on the filter kilovoltampere rating. The effect of voltage unbalance on the rectifier output voltage is examined, and a specific practical solution for the elimination of the triplen input current harmonics is proposed. The authors conclusively demonstrate that the elimination of these noncharacteristic harmonics can be accomplished by using a firing scheme that results in equal and equally spaced thyristor conduction periods, irrespective of the degree of unbalance in input voltages. However, the scheme has a drawback: the amplification of the ripple voltage at the rectifier output. These conclusions are verified experimentally using a 5 kVA setup. >
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30 Jul 1991TL;DR: In this article, a fault tolerant power supply consisting of a first rectifier and a second rectifier with a boost circuit for correcting line current harmonics is presented, where the boost circuit and output diodes are connected in parallel with the first rectifiers.
Abstract: A fault tolerant power supply comprises a first rectifier and a second rectifier with a boost circuit for correcting line current harmonics. The second rectifier, the boost circuit and output diodes are connected in parallel with the first rectifier. A capacitor circuit is charged through the second rectifier and boost converter when a 240 volt line input is present, but the circuit is charged through the first rectifier when a 120 volt line input is present. With failure of the boost converter circuit or with removal of the boost converter circuit from the system, the capacitor circuit is charged through the first rectifier.
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20 Sep 1991TL;DR: In this paper, a semiconductor integrated circuit comprises a chip (TIP), an oscillator (200) provided on the chip for producing an alternate current with a controlled amplitude that is determined by the drive voltage, a rectifier (300), and a voltage detector (100), which is supplied with the detection signal from the voltage detector for controlling the oscillator such that the amplitude of the alternate current is changed in response to the voltage signal.
Abstract: A semiconductor integrated circuit comprises a chip (TIP), an oscillator (200) provided on the for producing an alternate current with a controlled amplitude that is determined by the drive voltage, a rectifier (300) provided on the chip for receiving and converting the alternate current into a direct current, a voltage detector (100) provided on the chip for detecting a voltage level of the direct current, and a controller (600) provided on the chip and supplied with the detection signal from the voltage detector for controlling the oscillator such that the amplitude of the alternate current is changed in response to the detection signal. The controller increases the amplitude of the alternate current when the voltage level of the direct current has decreased below a predetermined level and decreases the amplitude of the alternate current when the voltage level of the direct current has increased above the predetermined level.
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08 Jul 1991TL;DR: In this article, a process and a device are disclosed for operating as on-board charging set the inverse rectifier (4) of the threephase current drive (2) of an electric car.
Abstract: A process and a device are disclosed for operating as on-board charging set the inverse rectifier (4) of the threephase current drive (2) of an electric car. In the charging mode of operation two bridge arms (18, 22) of the inverse rectifier (4) are set as boos regulator, so that a direct voltage (Ud) is supplied to an intermediate capacitor (16) of the inverse rectifier (4) depending on a mains-friendly supply, whereas a further bridge arm (20) of the inverse rectifier (4) is set as a buck regulator, so that a charging current from the intermediate capacitor (16) is supplied to the driving battery (10) of the electric car depending on a charging characteristic thereof. By adding simple elements, the inverse rectifier (4) of the threephase current drive (2) of an electric car can thus be used as an on-board charging set, saving volume and weight in relation to known electric cars.
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30 Sep 1991
TL;DR: In this article, a universal dimmer is proposed for both fluorescent lamps having a ballast and for incandescent lamps connected to either an alternating or direct current power supply. But it is not suitable for the use of a light switch.
Abstract: A universal dimmer which can be used for both fluorescent lamps having a ballast and for incandescent lamps connected to either an alternating or direct current power supply. The dimmer can be installed in place of a standard wall-mounted light switch and connected to the existing wiring. The dimmer circuitry has a fullwave diode rectifier bridge connected in series with the lamp for converting the alternating current power into direct current. A variable current limiting circuit is connected in series with the DC output of the rectifier bridge and is powered by direct current to control the amount of current supplied through the lamp and ballast. The current limiting circuit includes a power transistor which acts as a variable resistor and controls the lamp current and an operational amplifier coupled with a voltage divider network that establishes a selectively variable reference voltage which controls the amount of current through the lamp. The fullwave rectifier bridge supplies a small amount of power to the control circuitry. The current limiting circuit allows continuous dimming control from full light output to zero output of both arc discharge lamps and incandescent lamps by limiting the current through the lamp without significantly reducing the electrical conduction angle of the alternating current power supply below 360 degrees and will also control dimming of systems powered by direct current.
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22 May 1991
TL;DR: In this article, a half-bridge series-resonance-type inverter circuit is powered from a substantially constant-magnitude DC supply voltage derived from ordinary 60 Hz power line voltage by way of a bridge rectifier and a single-transistor DC-to-DC converter using an energy-storing inductor with an isolated secondary winding.
Abstract: In an electronic ballast for powering three series-connected fluorescent lamps with a 30 kHz lamp current, a half-bridge series-resonance-type inverter circuit is powered from a substantially constant-magnitude DC supply voltage derived from ordinary 60 Hz power line voltage by way of a bridge rectifier and a single-transistor DC-to-DC converter using an energy-storing inductor with an isolated secondary winding from which the DC supply voltage is derived. Thus, the DC supply voltage is electrically isolated from the power line, as is also the inverter circuit itself as well as the ballast's output terminals. Lamp dimming is accomplished via a dimming control directly connected with the inverter circuit.
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31 Jan 1991TL;DR: In this paper, a discharge lamp lighting apparatus is described, where an AC voltage of a commercial AC power source is smoothed by a smoothing circuit (16) connected to the output terminal of the rectifier (14).
Abstract: In a discharge lamp lighting apparatus of this invention, an AC voltage of a commercial AC power source (12) is full-wave-rectified by a rectifier (14), and this full-wave-rectified AC is smoothed by a smoothing circuit (16) connected to the output terminal of the rectifier (14). An inverter (38) is operated by a series resonance circuit constituted by a resonant choke coil (58) and a capacitor (60) and connected to the output terminal of the rectifier (14) and field-effect transistors (38, 40) connected to this series resonance circuit. By the operation of the inverter (36), a high-frequency AC is induced in an output winding (70) of a boosting transformer (66) having an input winding (68) connected in parallel with the capacitor (60) of the series resonance circuit, and discharge lamps (72₁, 72₂) are turned on.
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19 Jul 1991
TL;DR: In this paper, a driving circuit for an inverter microwave oven which includes a push-pull voltage type inverter circuit having two sets of switching element groups each provided with more than two switching elements connected in parallel to each other for switching the D.C. power source, is described.
Abstract: A driving circuit for an inverter microwave oven which includes a push-pull voltage type inverter circuit having two sets of switching element groups each provided with more than two switching elements connected in parallel to each other for switching the D.C. current supplied from a D.C. power source, a control device arranged to set a period for simultaneously turning OFF the two sets of switching element groups and to alternately turn ON the switching element groups by the same duty cycle, a step up transformer supplied, at its primary winding having a center tap, with A.C. current from the inverter circuit, and a voltage doubler rectifier circuit connected to a secondary winding of the step-up transformer for supplying electric power to a magnetron through a capacitor. The driving circuit is set so that one half period of a waveform of current flowing through the switching elements becomes equal to the duty cycle by adjusting the leakage inductance of the step-up transformer, the capacitance value of the capacitor and the circuit resistance of the voltage doubler rectifier circuit or the duty cycle of the switching elements.
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28 Sep 1991
TL;DR: In this article, a soft-switching AC to DC converter that employs a continuously resonating L-C circuit in a single-phase single-switch boost rectifier circuit is presented.
Abstract: A soft-switching AC to DC converter that employs a continuously resonating L-C circuit in a single-phase single-switch boost rectifier circuit is presented. The phase of the resonant tank when the switch is turned on is used as the controlling variable for shaping the rectifier input current. This phase control technique, when used together with a current estimator, is demonstrated as an effective means for generating sinusoidal AC-line currents in phase with the AC-line voltage. The quality of the control scheme is assessed, and experimental results are obtained for an 800 W, 20 kHz rectifier using an IGBT switch. >
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05 Mar 1991
TL;DR: In this paper, a rectifier power supply automatically adjusts to operate over either of two separate ranges of AC line voltages by reconfiguring filter capacitors so as to charge the capacitor serially when operated over the higher range of voltages and separately over each half cycle when operated on the lower voltage range.
Abstract: A rectifier power supply automatically adjusts to operate over either of two separate ranges of AC line voltages by reconfiguring filter capacitors so as to charge the capacitor serially when operated over the higher range of voltages and to charge the capacitors separately over each half cycle when operated over the lower voltage range. A triac device, used to control charging of the capacitors, is selectively activated only during a small portion of each half cycle to minimize power consumption. The device includes a bridge rectifier circuit receiving an AC line voltage and supplying pulsating DC to the serially connected two filter capacitors. The triac is used as a switch and is connected between one input terminal of the diode bridge and a node point between the two capacitors. An AC line voltage range detector and triac control circuit responsive to the range detector causes the triac to conduct when the AC line voltage is detected within the lower range. In particular, the control circuit causes the triac to conduct after a first time interval after a zero crossing of the AC line voltage and to cease conducting after a second time interval.
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08 Jan 1991
TL;DR: In this article, a circuit suitable for the instantaneous starting, continuation, and interruption of current through one or more gasfilled discharge tubes, in particular fluorescent lamps, is described, and the circuit and lamp heaters are energized before instantaneous control can occur.
Abstract: A circuit suitable for the instantaneous starting, continuation, and interruption of current through one or more gasfilled discharge tubes, in particular fluorescent lamps, is described. The circuit and lamp heaters are energized before instantaneous control can occur. One preferred silicon controlled rectifier (SCR) is used with a bridge rectifier. The SCR has the dual role of causing the capacitor to discharge through the pulse transformer, the secondary pulse voltage of which thereby causes the arc to strike immediately upon application of gate current, and then maintianing the lamp current as long as a supply of SCR gate current is provided. A second preferred control device, a TRIAC, is used without a bridge rectifier and again has a dual role of pulse-starting and maintaining current. This type of device is more conveniently arranged to provide for a dimming function as well. Applications include "flashing" advertising signs, general illumination, and signals.
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01 Nov 1991TL;DR: In this paper, single-phase rectifiers that employ capacitive and inductive energy storage/transfer mechanisms are derived from the Cuk convertor and single-ended primary inductor convertors, so that the step-up and stepdown characteristics of the output voltage can be easily obtained.
Abstract: The paper presents single-phase rectifiers that employ capacitive and inductive energy storage/transfer mechanisms. These are derived from the Cuk convertor and single-ended primary inductor convertors, so that the step-up and step-down characteristics of the output voltage can be easily obtained. The supply current can be sinusoidally waveshaped with a near-unity power factor by means of current reference hysteresis control. To predict their steady-state and transient characteristics successfully the approximate state-space averaging method is introduced with a digital PID controller. The experimental and predicted results confirm the usefulness of the rectifiers prsented.