Showing papers on "Precision rectifier published in 1998"

An economical single-phase passive power-factor-corrected rectifier: topology, operation, extensions, and design for compliance

Abstract: This paper describes a novel passive power-factor correction circuit that ensures the compliance of the capacitively filtered single-phase rectifier with the EN61000-3-2 norm at a cost much lower than the known solutions The circuit can be used to about 300 W The additional components are a small inductor, a small capacitor and a diode

Harmonic cancellation by mixing nonlinear single-phase and three-phase loads

Abstract: The voltage on the distribution line is, in most cases, distorted even at no load of the transformer. This is due to the "background" distortion on the medium-voltage line caused by the large number of single-phase nonlinear loads, such as PCs, TVs, VCRs, etc. This paper proposes a method to mix single-phase and three-phase nonlinear loads and reduce the harmonic currents significantly. The dependence of the phase angle of the harmonic currents as a function of the short-circuit impedance is investigated using SABER for the three-phase and the single-phase diode rectifier both with and without DC-link inductance. The phase angle of the fifth harmonic current of a three-phase diode rectifier is always in counterphase with the fifth harmonic current of a single-phase diode rectifier. This leads to the conclusion that adding three-phase rectifier load can actually improve the power quality at the transformer. This is also validated by a number of on-site measurements in several applications of three-phase adjustable-speed drives.

Coupled-inductor current-doubler topology in phase-shifted full-bridge DC-DC converter

Abstract: The paper proposes and analyses the coupled-inductor version of the current-doubler rectifier. The analysis shows that coupling of the inductors can reduce losses both in transformer and inductor windings. Practical design procedure of the coupled-inductor and experimental results for a 1900 W telecom rectifier are included.

Controller for a synchronous rectifier and power converter employing the same

Abstract: For use in a power converter having a power switch and a synchronous rectifier device coupled between an input and an output thereof, a transient response network, method of disabling a synchronous rectifier device and power converter employing the network and method In one embodiment, the transient response network includes a synchronous rectifier controller, coupled to the power switch and the synchronous rectifier device, that senses a state of the power switch and disables the synchronous rectifier device when the power switch has remained in a nonconducting state for at least a specified period of time

Precision bandgap reference circuit

Abstract: A precision bandgap reference circuit which uses an operational amplifier (34) that has the positive and negative input terminals connected to a diode/resistor combination (52A and 52B) and a diode (50) respectively. The circuit also comprises an output stage (64 and 66) driven by the operational amplifier to be biased with a PTAT current.

VIENNA rectifier II-a novel single-stage high-frequency isolated three-phase PWM rectifier system

Abstract: Based on an analysis of basic realization possibilities, the structure of the power circuit of a new single-stage three-phase boost-type PWM rectifier system (VIENNA Rectifier II) is developed. This system has continuous sinusoidal time behavior of the input currents and high-frequency isolation of the output voltage which is controlled in a highly dynamic manner. As compared to a conventional two-stage realization, this system has substantially lower complexity and allows to realize several isolated output circuits with minimum effort. The basic function of the new PWM rectifier system is described based on the conducting states occurring within a pulse period. Furthermore, a straightforward space vector oriented method for the system control is proposed which guarantees a symmetric magnetization of the transformer. Also, it makes possible a sinusoidal control of the mains phase currents in phase with the associated phase voltages. By digital simulation the theoretical considerations, the stresses on the power semiconductors of the new converter system are determined. Finally, problems of a practical realization of the system are discussed, as well as the direct start-up and the short circuit protection of the converter. Also, the advantages and disadvantages of the new converter system are compiled in the form of an overview.

Step-up/step-down voltage regulator using an MOS synchronous rectifier

Abstract: A circuit and method for providing a voltage regulation despite variations in the supply voltage and/or the load utilize a MOS synchronous rectifier in a flyback topology to perform both step-up and step-down operations. The circuit operates in a boost-type operation until the voltage at an output terminal exceeds a predetermined shut-off voltage. At such time, a duty cycle of the circuit is suspended until the voltage at the output terminal falls below the predetermined shut-off voltage. Triggering the duty cycle and the suspension of the duty cycle are dependent solely upon the voltage at the output terminal. The circuit includes a steering device that connects the body of MOS synchronous rectifier to either its source or its drain to consistently configure the MOS synchronous rectifier in a reverse-biased condition. Preferably, the steering device is comprised of two PMOS transistors that are controlled by the voltages at the source and drain of MOS synchronous rectifier.

Soft strat bridge rectifier circuit

Abstract: A soft start bridge rectifier circuit is described for controlling the operation of the bridge rectifier in order to ramp up the DC output upon connection with the AC input in order to limit in-rush current Additionally, short-circuit/overload protection, temporary line loss protection and undervoltage checking circuitry is provided

A technique for reducing rectifier reverse-recovery-related losses in high-power boost converters

Abstract: A circuit technique that reduces the boost power converter losses caused by the reverse-recovery current of the rectifier is described. The losses are reduced by inserting an inductor in the series path of the boost switch and a rectifier to control the di/dt rate of the rectifier during its turn off. The energy from the inductor after the boost switch turn off is returned to the input or delivered to the output via an active snubber.

Process and device for the detection of the rectifier effect appearing in a gas discharge lamp

Abstract: Process for the recognition of the rectifier effect appearing in a gas discharge lamp (G 1 , G 2 ) and an electronic ballast, for the operation of gas discharge lamps (G 1 , G 2 ), with which such a process finds employment. The electronic ballast includes a monitoring or control circuit (IC 2 ) which monitors an operating parameter of a load circuit (E) of the electronic ballast, whereby this operating parameter corresponds to the lamp voltage or is dependent thereon. The monitoring circuit (IC 2 ) integrates this monitored operating parameter over a full period and determines upon the presence of a rectifier effect if the integration result deviates from a predetermined integration desired value. Further, for the recognition of the rectifier effect, the duration of the positive and negative half-waves of the monitored parameter can be compared.

Predictive threshold synchronous rectifier control

Abstract: A method and apparatus are disclosed for controlling the operation of a synchronous rectifier used in power conversion circuitry. The disclosed method and apparatus senses the voltage across the synchronous rectifier, and turns the synchronous rectifier OFF when the voltage across the rectifier is about to change direction. Preferably, the synchronous rectifier is commanded OFF at the approximate instant when the voltage across the rectifier reaches approximately zero, which also corresponds to a current of approximately zero. Accordingly, currents are prevented from flowing in the reverse direction in the synchronous rectifier. This results in approximately zero voltage and zero current switching when the rectifier is turned OFF, thereby minimizing switching losses.

A new ZVS-PWM active-clamping high power factor rectifier: analysis, design, and experimentation

Abstract: In this paper a new single-phase rectifier is introduced, which features high power factor, regulation by conventional PWM technique, ZVS commutation and clamping action in both switches, and instantaneous average line current control. This rectifier consists of a front-end full-bridge diode rectifier followed by a ZVS-PWM, buck-boost active-clamping, boost converter. Experimental results are presented, taken from a laboratory prototype rated at 1.6 kW, input AC voltage of 220 V rms, output DC voltage of 400 V, and operating at 100 kHz. The measured efficiency at full load was 95%.

Esd protection circuit immune to latch-up during circuit operation

Abstract: An ESD protection circuit of the present invention comprises a semiconductor controlled rectifier and at least one diode connected in series. The series-connected semiconductor controlled rectifier and diode are electrically coupled between a pair of circuit nodes. Even though the semiconductor controlled rectifier enters snapback during circuit operation the diode can be utilized to increase a holding voltage between the pair of circuit nodes. The required number of diodes is based upon the design consideration so that proper trigger voltage and holding voltage can be acquired. The semiconductor controlled rectifier can be a lateral semiconductor controlled rectifier, a low voltage triggering semiconductor controlled rectifier, or a floating-well semiconductor controlled rectifier.

Active rectifier utilizing a fixed switching pattern

Abstract: An active rectifier circuit includes a rectifier bridge having a plurality of passive rectifiers and a switching element coupled across each passive rectifier A control circuit is coupled to the switching elements and senses reactive current flow and includes a phase-locked loop responsive to the reactive current flow and a circuit for developing switching patterns for the switching elements

Uninterruptible power supply having solid state transfer switch and method of operation thereof

Abstract: An uninterruptible power supply (UPS) for supplying DC power to a load and a method of providing uninterruptible DC power to a load. In one embodiment, the UPS includes: (1) a first stage rectifier that rectifies AC input power received from a primary power source into DC power at an intermediate voltage, (2) a second stage rectifier, coupled to the first stage rectifier, that converts the DC power at the intermediate voltage into DC power for the load at an output voltage that is lower than the intermediate voltage and (3) a solid state transfer switch, coupled between the first stage rectifier and the second stage rectifier, that transfers secondary input power received from a secondary power source to the second stage rectifier only when a voltage of the secondary input power exceeds the intermediate voltage.

A new space-vector-modulated control for a unidirectional three-phase switch-mode rectifier

Abstract: A unidirectional three-phase switch-mode rectifier that delivers sinusoidal input currents in phase with the corresponding input phase voltages is proposed and analyzed in this paper. In the proposed topology, three AC switches are placed before the bridge rectifier and, respectively, across two power lines. A simple control scheme combing space-vector modulation and hysteresis current control is presented. Sinusoidal input line currents are observed in experimental results.

Integrated synchronous rectifier for power supplies

Abstract: A timing circuit generates timing signals for a synchronous rectifier directly from the transformer power output winding. A phase detector detects the phase of the voltage on the output winding. A switched current source generates a digital timing signal responsive to the phase detector. The output from the current source is applied to the gate of the rectifier to control the on/off condition of the rectifier.

Adaptive threshold controlled decision circuit immune to ringing components of digital signals

Abstract: In an optical receiver, a photodiode converts an optical digital input signal to an electrical signal which is fed into a differential amplifier to produce a pair of true and complementary output signals. The true output signal is received by a peak detector and the output of this peak detector is summed in a first adder with the complementary output of the differential amplifier. The true output of the amplifier is summed in a second adder with a predetermined constant voltage. Difference between the output signals of the first and second adders is detected and compared with a decision threshold to produce an output signal at one of two logical levels depending on whether the difference is higher or lower than the decision threshold. Preferably, a second peak detector having a substantially similar operating characteristic to that of the first peak detector is connected between the source of the predetermined constant voltage and the second adder.

A method and device for power conversion

Abstract: As a front end power factor correction circuit in a rectifier a boost conversion topology is often used. A great problem with this topology is the rectifier diode. This diode must be of a high voltage type in a boost application and will therefore have a large reverse-recovery current before it will block the voltage. This current may cause large losses. With the solution according to the invention care will be taken to the recovery current in a more effective way than any earlier solution has obtained. The proposed circuit comprises essentially a boost circuit, where a main and first inductor L1 (3) and a main and first diode D1 (4) are connected in series from an input to an output and a main and first capacitor C1 (5) from an output to ground. A main and first transistor M1 (1) is connected from between the first inductor L1 (3) and the first diode D1 (4) to ground. An auxiliary and second inductor L11 (6), a second diode D11 (7) and a second transistor M11 (2) are connected in series from between the first inductor L1 (3) and the first diode D1 (4) to ground. Two other diodes a third and fourth diode D12 (10), D13 (9) are connected in series from between the second diode D11 (7) and the second transistor M11 (2) to the output.

Constant polarity input device including synchronous bridge rectifier

Abstract: A circuit including bridge rectifier, switches across one or more of the diodes of the bridge rectifier, and a comparator providing control signals to the switch or switches can be constructed to apply a constant polarity voltage to an electrical load, regardless of the polarity of the input power applied to the circuit. The comparator produces a control signal depending upon a comparison of the input power voltages, and the control signal activates one or more of the switches to allow current flow through an appropriate path in the circuit to yield the constant polarity across the electrical load. Thus, the circuit can protect the electrical load from an inappropriately applied voltage by switching the applied voltage's polarity. Because an activated switch can short a diode in the bridge rectifier, power loss associated with current flow through the diode is reduced. Additionally, the circuit can provide constant polarity across the electrical load with either AC or DC input power.

Power factor improving circuit

Abstract: A power factor improving circuit for reducing a harmonic current component contained in an AC input current and for achieving an excellent power factor and efficiency in a circuit having a rectifier circuit, provided between a rectifier circuit and a half-bridge-type inverter, including a discharging diode and a smoothing capacitor connected in series to each other and in parallel between output terminals of the rectifier circuit, a charging half-bridge rectifier connected to the smoothing capacitor, and a high-frequency capacitor and high-frequency inductor connected in series to each other and between an input terminal of the charging half-bridge rectifier and a connecting point of two transistors of the half-bridge-type inverter.

Circuit for reducing switching losses of a power converter and method of operation thereof

Abstract: In a power converter having a power train that includes a power switch and a rectifier for conducting forward currents from the power switch, a circuit for, and method of, reducing switching losses associated with the power train. The circuit includes: (1) an auxiliary switch and an inductor coupled to the power train that reduce a switching loss associated with the power switch and (2) an impedance element series-coupled to the rectifier that reduces a change in current through the rectifier thereby decreasing a reverse recovery current flowing therethrough.

Peak to peak signal detector for audio system

Abstract: A peak to peak detector circuit for use in an audio system comprises a first amplifier having an input terminal for receiving an L+R AC audio signal and an output terminal which is serially coupled to a resistor in series with a capacitor for generating a variable dc voltage having a time vs. amplitude relationship corresponding to the input L+R AC audio signal. A clamping diode having a cathode electrode coupled to a reference potential and having an anode electrode coupled to the capacitor operates to limit negative amplitude excursions associated with the variable dc voltage to a predetermined minimal value. A rectifying diode having a cathode electrode coupled to the anode electrode of the clamping diode, and an anode electrode coupled to a second capacitor to charge the second capacitor responsive to the amplitude of said variable dc voltage operates to produce a dc output signal proportional to the peak amplitude of said L+R audio signal.

Switching-type DC power source apparatus

Abstract: In a switching-type DC power source apparatus which uses a booster-chopper type active filter circuit as its rectifier circuit, even at zero-crossing timing of an AC voltage to be input in the rectifier circuit, a current supply source for making a current as if it is flowing is added to a current detection circuit for detecting the current flowing in the active filter circuit, thereby preventing a prickle-like input current including a number of harmonic components from flowing in the apparatus.

Synchronous rectifier circuit

Abstract: In a switching power circuit adopting the synchronous rectifying system, when a first switch is cut-off, current I L of an inducing element is maintained by a commutating diode, and the inducing element releases an energy which was stored in a conduction period of the first switch. A second switch connected in parallel to the commutating diode is conducted so as not to be overlapped with the conduction period of the first switch. In the conduction period of the second switch, the current I L does not flow through the commutating diode, and it is possible to prevent lowering of efficiency caused by forward voltage drop. An inducing element current detecting circuit monitors the current I L and, when the current I L is reversing its direction, instructs a control circuit to cut-off the second switch. As a result, no reverse current flows through the inducing element even when the load is small, thus realizing a switching power circuit always having high efficiency.

DC bus voltage controller

Abstract: An apparatus for use with a switch-mode rectifier for minimizing DC bus voltage without causing current distortion, the apparatus monitoring rectifier saturation and decreasing DC bus voltage until the rectifier is near a saturation point and then maintaining the DC bus voltage at that point.

A capacitor-fed, voltage-step-down, single-phase, nonisolated rectifier

Abstract: A simple rectifier, little documented in the literature, provides a low-voltage output from an AC-mains supply, with inherent short-circuit protection. We present waveforms, a theoretical analysis, simulation results (within /spl plusmn/2% of theoretical predictions over a 512:1 range of the principal design parameter) and experimental confirmation, and propose variants with improved regulation. The line-harmonic characteristics comply with IEC 1000-3-2, Class A, at power levels up to 250 W. This rectifier finds application in equipment requiring a low-voltage, nonisolated DC supply.

Harmonic analysis of parallel-connected 12-pulse uncontrolled rectifier without an interphase transformer

Abstract: The author presents a harmonic analysis of a parallel-connected 12-pulse uncontrolled bridge rectifier without an interphase transformer (IPT). Five normal operating modes of the specific rectifier circuit are classified, using an analytical method by deriving instantaneous AC current and DC voltage waveform equations. The discrete Fourier transformation algorithm is then carried out to obtain both current and voltage harmonic contents. Both the AC current and DC voltage harmonics for rectifiers with and without an IPT have been investigated to discuss the influence of the IPT on rectifier harmonics. Simulation results reveal that discrepancies in harmonic contents of both AC current and DC voltage of the two rectifier circuits are marked. It is noted that, for extremely light load up to rated load conditions, the total harmonic distortion (THD) of line-supply current is reduced, while the THD of DC output voltage is increased when the IPT is deleted from rectifier circuit.

Voltage, efficiency calculation and measurement of low power rectenna rectifying circuit

Abstract: In this paper, we present zero-bias Schottky diode and rectifier circuit models for a low power (/spl les/ 0 dBm) rectenna rectifying circuit. These models rely primarily on data obtained from the diode characteristic curve measurement. The zero-bias Schottky diode model provides diode parameters at the desired output DC current level to be matched with the antenna so that optimum power transfer from the antenna to the diode takes place. The rectifier circuit model provides an equivalent circuit model for the rectenna rectifying circuit to calculate RF to DC conversion efficiency at the desired output DC current level.

Peak detector circuit

Abstract: A peak detector circuit (100) includes an output transconductance amplifier (102), a current rectifier (104) and an averaging circuit (108). The current rectifier includes an amplifier (115) which reduces input impedance of the current rectifier to increase the operating frequency of the peak detector circuit. An isolator (106) employs a current mirror (509) with a cascode transistor (512) having a bias potential which is dynamically adjusted to achieve accurate mirroring. An amplifier of a common mode feedback circuit (110) has improved linearity.