Showing papers on "Precision rectifier published in 1991"

High efficiency telecom rectifier using a novel soft-switched boost-based input current shaper

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. >

High power factor, voltage-doubler rectifier

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.

Optimized, 18-pulse type AC/DC, or DC/AC, converter system

Abstract: A 18-pulse converter system operates without interphase transformer and neutral point on the DC side by providing three rectifier bridges across the DC terminals, one rectifier bridge being coupled with the AC terminals and the two other rectifier bridges being operated at + and -40 degress phase shift, while the rectifier devices are controlled for 40-degree current conduction.

Class E low dv/dt synchronous rectifier with controlled duty ratio and output voltage

Abstract: A class-E high-frequency low-dv/dt synchronous rectifier/DC regulator is analyzed. The circuit is derived from a class-E rectifier by replacing a diode with a controllable switch. It can then both rectify and regulate the rectified output against variations in DC load and amplitude of the AC input voltage. The switch consists of a transistor and an antiparallel diode or a series diode. The DC output voltage of the rectifier is regulated by varying the ON duty ratio of the switch. The AC input voltage can be at a constant or varying frequency. The controllable switch turns on and off at zero voltage with low dv/dt, reducing switching losses, stresses, and noise. Equations governing the circuit operation are derived. Experimental results at 0.5 MHz were in good agreement with the theoretical predictions. The rectifier can be used in high-frequency-power-density multiple-output power supplies, all of whose outputs are regulated. The frequency need not be varied to regulate the DC output. >

Voltage regulator for variable speed permanent magnet alternators

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.

Low harmonic current and fault tolerant power supply

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.

Process and device for operating as on-board charging set the inverse rectifier of the threephase current drive 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.

Uninterruptible power supply having improved battery charger

Abstract: An UPS apparatus with a back-up battery and successively coupled rectifier, inverter and output filter circuits, having an improved battery charging circuit. The charging circuit has a transformer with its primary winding being part of the output filter, and its secondary winding driving a second rectifier circuit which produces the charging current. The charging circuit contains an impedance preferably connected between the transformer secondary winding and the second rectifier circuit, for capturing only a high frequency portion of the signal from the inverter stage, thereby enabling the utilization of smaller charger circuit elements.

A single-phase, unity power factor, soft-switching, resonant tank boost rectifier

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. >

Current sensing synchronous rectifier apparatus

Abstract: A current-sensing rectifier for current rectification and measurement applications is described. The current-sensing rectifier comprises a current-sensing device for rectifying the current in a selected circuit branch and an active-sense comparison circuit to measure the sense current provided by the current-sensing device. The current-sensing device and active measurement circuit are operated such that the current-sensing device rectifies the current of a selected circuit branch. No negative voltage supplies are required for rectification or for the measurement of the branch current. Further embodiments of the present invention include sample-and-hold circuits which sample the value of the rectified current during an ON-period of operation and maintain the sampled value during a subsequent OFF-period.

Analysis and design of an unusual unity-power-factor rectifier

Abstract: A unity-power-factor rectifier that has a parallel-resonant tank tuned to the second harmonic of the line frequency is analyzed for two filter configurations. A unidirectional-power-flow version of the current-sourced rectifier can operate stably open loop or can be current limited down to zero output voltage. The large inductor normally required is an outstanding disadvantage which can be partially overcome using a resonant filter. The design-oriented analysis includes variable-frequency operation and key component ratings. A design procedure is suggested, and complete experimental verification is obtained using a 120 V, 500 W. 60 Hz rectifier switching at 50 kHz. >

Crankshaft angular position voltage developing apparatus having adaptive control and diode control

Abstract: Apparatus for developing a series of square-wave pulses from an alternating voltage that is generated in the pick-up coil of a variable reluctance sensor that is associated with a slotted wheel that is driven by the crankshaft of an internal combustion engine. The system has an adaptive control which comprises a peak detector, a capacitor and a voltage comparator. The capacitor is charged to a peak voltage that corresponds to the peak value fo the positive half-cycles of the alternating voltage. The comparator is connected to compare the peak voltage and a voltage that corresponds to the magnitude of the positive half-cycles. A diode is connected between the pick-up coil and the peak detector which prevents charging of the capacitor and accordingly prevents adaptive control until the voltage induced in the pick-up coil is high enough to cause the diode to conduct in the forward direction.

Operating limits of the current-regulated delta-modulated current-source PWM rectifier

Abstract: A stand alone, three-phase, delta-modulated, current-source PWM rectifier has been built and has been shown to be capable of operating with near sinusoidal current waveforms, unity power factor. and good DC current regulation. A mathematical model that has been justified against experimental measurements and results from digital simulations is presented. The current waveform distortion limit and the asymptotic stability limit are established. It is shown that the rectifier can operate safely within these limits in the entire range of its power ratings. >

High voltage majority carrier rectifier

Abstract: A rectifier circuit is provided including a MOSFET having a gate, a drain, and a source terminal. A Schottky diode is connected in series with the MOSFET. The cathode of the Schottky diode is connected to the source of the MOSFET. A zener diode is connected in parallel with a capacitor. A recharging diode has its anode connected to the junction between the MOSFET and the Schottky diode and its cathode connected to the cathode of the zener diode, with the drain serving as the cathode of rectifier circuit and the anode of the Schottky diode serving as the anode of the rectifier circuit. The rectifier circuit has a fast recovery time and is suitable for both high frequency and high voltage, power conversion applications. The rectifier circuit can be used in place of P-N junction fast recovery diodes with less complex snubbers and switch aiding circuits.

Rectifier commutation current spike suppressor

Abstract: A circuit for reducing the commutation transient in a switch-driven (12) free-wheeling rectifier (20) applied to a load (10) via a continuously conducting energy conducting inductor (28), in which a further inductor (34) and diodes (32, 38) are interconnected with the switch-driven rectifier (20) to free-wheel recovered commutation energy from rectifier (20) when the switch is non-conducting. In other circuit variations temporary energy storage is aided by one or more capacitors (72) and additional diodes (52, 54, 80, 107, 122) during turn-on of rectifier (20), which energy recycled back into the circuit to minimize power dissipation and reduce circuit component heating.

Switched peak detector

Abstract: A peak detector circuit includes a switch for charging and discharging a capacitor at predetermined rates. In a first mode of operation, the switch is open and the peak detector functions to provide an output voltage that is indicative of the peak voltage level occurring at its input by charging a capacitor at a first predetermined rate. In a second mode of operation, the switch is closed and the peak detector functions to discharge the capacitor at a second predetermined rate and to a predetermined voltage. Subsequently in the second mode of operation, the peak detector then functions to provide an output voltage that follows its input voltage.

Modeling and simulation of a digitally controlled active rectifier for power conditioning

Abstract: The authors describe a single-phase active rectifier that provides an input AC current with unity displacement power factor and 3% total harmonic distortion (THD). The goal is to devise a rectifier to compensate for current harmonics and to improve the power factor of the line current. A closed-loop current control is proposed which will force the AC line current to be nearly sinusoidal and in phase with the input source voltage. Thus average DC output voltage is controlled to the desired value. Two topologies for the rectifier are investigated-a standard boost topology and a modified boost topology with the inductor moved to the AC side of the rectifier. Computer simulations that implement closed-loop control of the models are presented. Simulation programs and results are discussed. >

Development of a thermally switched superconducting rectifier for 100 kA

Abstract: A full-wave superconducting rectifier for 100 kA has been developed. Typical design values of this device are: a secondary current of 100 kA, a primary amplitude of 20 A, an operating frequency of 0.5 Hz, and an average power on the order of 100 W. The rectification is achieved by means of thermally controlled superconducting switches with recovery times of 150 to 300 ms. A description of the rectifier system is given. The first experiments, in which the rectifier was tested at up to 25 kA demonstrate reliable and fail-safe operation of the rectifier at lower current levels. It was, for example, successfully used to load and unload a 25-kA coil at a rectifier frequency of 0.4 Hz and an average power of 30 W. During tests without any load, it was found that the secondary circuit of the transformer quenches at about 60 kA. Therefore, it is unlikely that the rectifier in its present configuration will attain 100 kA.

Design of current source using 12-pulse phase-controlled rectifier

Abstract: A method for designing a current source using the 12-pulse phase-controlled rectifier (PCR) is investigated. The PCR system is analysed and filter parameters are designed from this analysis. A phase-locked voltage control circuit with a fast dynamic characteristic is analysed and an optimal constant proportional-integral and measurable feedback plus feedforward (PIMF) current controller is designed using a time-weighted quadratic performance index. It is also shown from experimental results that the proposed design method gives good performance.

Class D synchronous rectifiers

Abstract: A current-driven synchronous regulated class D rectifier is presented. An analysis of the rectifier is presented, and parameters are given. An advantage of the proposed circuit is that peak values of voltages across its elements are relatively low if compared with its output voltage. A symmetry between the rectifier and the voltage-switching half-bridge resonant class D amplifier is shown. Due to its simplicity, the rectifier can find applications in resonant DC/DC converters operating at a constant frequency. Experimental results were in good agreement with those predicted theoretically. >

Crest factor measurement device

Abstract: The crest value and RMS value of a signal are measured The ratio of the two values, the crest factor, is calculated to provide a measure of the signal wave shape The frequency range and accuracy of a commercially available RMS converter is improved by providing an improved rectifier ahead of the converter's internal rectifier This improved rectifier is also used to form the absolute value of the input signal A peak detector then provides the crest value (absolute peak value) The crest value and RMS value are multiplexed to a computer having an A/D converter The RMS value, crest value and crest factor can be calculated and displayed and/or stored by the computer

Interactive analysis and design program for phase-controlled rectifiers

Abstract: The authors describe an interactive computer program that accurately determines rectifier time waveforms in the periodic steady-state condition without the need for many of the previously used simplifying assumptions. The program provides important input data for the design of components associated with the rectifier. The DC, RMS, and peak currents through the output filter inductor and the DC voltage across and the RMS current through the output filter capacitor are sufficient for the selection and design of these components. The rectifier time waveforms are analysed for line-current harmonics, rectifier power factor, and other important rectifier performance data providing the user with a complete and accurate description of rectifier performance as a function of rectifier design. >

Supply circuit or power supply unit for supplying electronic devices or the like with current or voltage

Abstract: A supply circuit for supplying electronic devices with current or voltage and mountable as a module has input and output connections, a rectifier cirucit, a transformer having a primary winding coupled with the inputs of the supply circuit and a secondary winding coupled with the rectifier circuit and at least one high-capacity capacitor. The capacitor is coupled with an output of the rectifier circuit for smoothing generated direct current or direct voltage. The capacitor has a housing which housesd the capacitor, the rectifier circuit and the transformer in or on the housing. The input and output connections are arranged on the housing so as to be accessible from outside of the housing. At least a parat of the housing consists of a magnetizable material and carries the primary and secondary windings in the manner of a winding body.

Monitor for a polyphase rectifier which detects open diodes by sensing a signal below a predetermined threshold

Abstract: An electronic circuit senses that at least one circuit of rectifying diodes has been opened and response initiates an alarm To sense one of the diode circuits being opened, the electronic circuit detects a temporary crossing of a low threshold by a DC voltage supplied at the rectifier output The circuit is particularly applicable to high-power transformer-rectifiers aboard aircraft

Precision rectifier system with differential input and differential output

Abstract: A precision rectifier system with differential input and differential output includes an input differential V/I converter responsive to a bipolar input signal voltage with respect to an input reference potential for providing a differential current representative of the magnitude of the input signal; a matching output differential V/I converter responsive to an output voltage signal with respect to an output reference potential for providing a differential current representative of the magnitude of the output voltage signal; amplifier means, responsive to a difference between the differential currents of the input and output V/I converters for adjusting the output voltage signal to null the differences between the differential currents; and switching means, responsive to the polarity of the bipolar input signal, for switching the polarity of the differential current representative of the magnitude of the input signal for maintaining a single polarity rectified output voltage signal.

Inductive inrush current control for off-line battery charger plant.

Abstract: Magnetic start up inrush current to a ferro-transformer (305) of an off-line rectifier circuit is limited by controlling the phase angle of the input voltage (90 degrees for a single phase input and a standard three phase input) at which the input is connected to the ac source (300). The input voltage to the off-line rectifier circuit is monitored for zero crossing points (312). In one arrangement the input voltage is directly monitored and a switch triggering pulse is time delayed for a time interval equal to 90 degrees of the input voltage waveform at which point the switch is enabled to connect the input AC voltage to the rectifier. In another arrangement the input voltage is integrated (311) and the zero crossing (312) of the waveform as integrated is used to define a trigger pulse to activate a switch (306) connecting the input voltage to the rectifier.

Power active filter for controlled three-phase rectifier

Abstract: This paper presents a power active filter with inductive storage that permits a very good compensation of the higher current harmonics generated in the mains by a controlled or uncontrolled three-phase rectifier.

Controlled power-factor-corrected ballast

Abstract: Subject electronic ballast draws power from the power line with a power factor higher than 90%. The ballast consists of a power-factor-correcting rectifier circuit and an inverter circuit that provides a high-frequency squarewave voltage across a series-resonant L-C circuit to which a fluorescent lamp is connected. The rectifier circuit consists of a full-bridge rectifier connected with its AC input terminals to the power line and with its positive/negative output terminals across: i) the inverter circuit; ii) a series-combination of a first rectifier and a first electrolytic capacitor, the first rectifier being connected with its cathode to the positive output terminal and with its anode to a first junction, the first capacitor being connected between this first junction and the negative output terminal; and iii) a series-combination of a second rectifier and a second electrolytic capacitor, the second rectifier being connected with its anode to the negative output terminal and with its cathode to a second junction, the second capacitor being connected between this second junction and the positive output terminal. A separate rectifier means is connected between the two junctions in such manner as to permit current to flow freely from the second junction to the first junction.

Ripple feedback for the resonant-filter rectifier

Abstract: An unusual buck-like unity-power-factor rectifier with a resonant load-balancing network permits current-limited operation down to zero output voltage in a single-stage topology. However, this rectifier has been found to be sensitive to AC-line voltage distortion, and potentially unstable with realistic values of AC-line impedance. A ripple feedback which solves both problems is proposed. A large-signal time-varying analysis is given along with incremental, quasi-static and low-frequency approximations. Experimental verification is provided by a 500 W, 50 kHz rectifier operating from the 120 V, 60 Hz distribution system. >

Tracking peak detector

Abstract: A peak detector circuit employs a line receiver of the ECL type, with the analog input signal to be tracked as a receiver input. The other receiver input is connected to the circuit output. A capacitor connects the output node of the circuit to threshold reference voltage input. The capacitor is charged through a resistor from the output of the line receiver when the input signal exceeds the voltage on the output node, and the capacitor discharges to the reference input through this resistor and another resistor connecting the receiver output to the reference input. The output voltage tracks the peaks of the input signal. Oscillation of the receiver is avoided by using a threshold reference greater than zero. The dynamic range of the output can be extended to a level higher than that of ECL levels by summing the thresholds of a number of these detectors, using an operational amplifier.