Showing papers on "Precision rectifier published in 1996"

A high-performance single-phase rectifier with input power factor correction

Abstract: In this paper, a high-performance single-phase AC-to-DC rectifier with input power factor correction is proposed. The proposed approach has many advantages, including fewer semiconductor components, simplified control, and high-performance features, and satisfies IEC 555 harmonic current standards. Simulation and experimental results obtained on a laboratory prototype are discussed. A hybrid power module of the proposed approach is also shown.

Regulation of a PWM rectifier in the unbalanced network state using a generalized model

Abstract: This study concerns the modeling and control of a pulse-width-modulated (PWM) rectifier in the case of network variations. The aim is to limit and stabilize variations of DC output voltage and line currents in such circumstances. Network variations can result in costly damage to power converters and their loads but a power converter such as the PWM rectifier, using cascade digital control, offers many capabilities to stabilize the system with optimized control. A generalized model of the PWM rectifier is first presented using the Clarke notation in order to separate the positive and negative sequences. The model is also extended to the harmonics. The cases of harmonic disturbance and an unbalanced network are then analyzed and an optimized regulation is presented for the latter case, validating the generalized model. Experimental results are proposed. The line current compensation loop method coupled with identification of network parameters offers a good solution to stabilize the PWM rectifier in an unbalanced network.

Novel reduced-order small-signal model of a three-phase PWM rectifier and its application in control design and system analysis

Abstract: A reduced-order (RO) small-signal model of three-phase pulse-width-modulation (PWM) rectifiers is proposed. By combining the PWM switch model and equivalent multimodule model techniques in DC-DC converters, a three-phase rectifier can be modeled as a DC-DC converter with equivalent power capability and small-signal characteristics. This model reduces the system order to two and greatly simplifies the control design and system analysis of three-phase converters. In this paper, the proposed model is also used for control design and for system interaction analysis on the three-phase interface of a boost rectifier. The RO model is verified with the d-q model, switching-model simulation, and experimental results.

Battery impedance monitor

Abstract: A battery impedance monitor includes a driver section having an oscillator which produces a pulsating loading signal which controls periodic loading of the battery to produce at its output terminals a pulsating voltage component having a peak-to-peak amplitude superimposed on the DC output voltage of the battery. This pulsating voltage component is detected in a measuring section, which applies the battery output through a voltage divider to a peak detector which outputs an indicating voltage level proportional to the peak-to-peak amplitude of the pulsating output signal, this indicating level being held on a storage capacitor. The voltage divider includes a Zener diode which shifts the DC level of the battery output without affecting the amplitude of the pulsating component. The measuring section is electrically connected to the driver section only through the battery terminals, but the storage capacitor is coupled to the oscillator through a load resistor and an opto-isolator which provides a discharge path for the storage capacitor during each loading pulse, so that the detector can follow decreasing as well as increasing indicator voltage levels. A delay circuit delays application of the loading pulses to the battery so that the discharge path is removed before the end of each pulse of the battery output voltage.

Technique for reducing rectifier reverse-recovery-related losses in high-voltage high power converters

Abstract: A circuit technique that substantially reduces the boost-converter losses caused by the reverse-recovery characteristics of the rectifier is described The losses are reduced by inserting an inductor in the series path of the boost switch and the 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 The same technique can be extended to any member of the PWM-converter family

An approach to harmonic current-free AC/DC power conversion for large industrial loads: the integration of a series active filter with a double-series diode rectifier

Abstract: This paper proposes a new harmonic-free AC/DC power converter characterized by the integration of a small-rated series active filter with a large-rated double-series diode rectifier. The DC terminals of the series active filter are directly connected in parallel with those of the double-series diode rectifier, thereby forming a common DC bus. The series active filter enables the diode rectifier to draw three-phase sinusoidal currents from the utility. In addition, it can provide the supplementary value-added function of regulating the common DC bus voltage to a limited extent of /spl plusmn/5%, with slightly increased RMS voltage rating but without increasing peak voltage rating. Experimental results obtained from a 5 kW laboratory system verify the practical viability and cost-effectiveness of the proposed AC/DC power converter.

Operating a three-phase diode rectifier with a low-input current distortion using a series-connected dual boost converter

Abstract: This paper describes a technique for shaping the input current to a three-phase diode rectifier using a two-switch series-connected dual boost converter and a three-phase bidirectional switch circuit. Circuits are described for generating a single voltage DC output, "single DC-rail", or a dual output DC voltage using center-tapped capacitors, "split DC-rail". Both rectifier types can be operated with the boost inductors located either on the DC or the AC side of the rectifier. The resultant rectifier circuit configurations have an excellent immunity to the "shoot-through" fault condition and use active switching elements with low per-unit current ratings and low switching losses. These features increase the reliability factor and lower the cost penalty associated with unity fundamental power factor three-phase rectifiers. Test results are presented for the rectifiers using simulation and experimental results.

Design considerations for 12-pulse diode rectifier systems operating under voltage unbalance and pre-existing voltage distortion with some corrective measures

Abstract: In this paper, design considerations for twelve-pulse diode rectifier systems operating under utility voltage unbalance and pre-existing harmonic voltage distortion are discussed. For a twelve-pulse diode rectifier system connected in parallel to feed a common DC link via an interphase transformer, it is shown that a small amount of impedance mismatch, utility voltage unbalance or pre-existing voltage distortion drastically affects the current sharing capability of the rectifier bridges. This, in turn, generates additional uncharacteristic and characteristic harmonics thereby increasing the THD. In order to mitigate these effects and ensure proper operation of diode rectifiers, specially designed line reactors termed harmonic blocking reactors (HBRs) are introduced. Analysis and design procedures for HBRs are discussed. Simulation results illustrate improved performance. Experimental results from a laboratory prototype system show close agreement with theory.

Synchronous rectifier type DC-to-DC converter in which a saturable inductive device is connected in series with a secondary-side switching device

Abstract: Disclosed is a synchronous rectifier type DC-to-DC converter capable of preventing an increase in losses occurring when a rectifier synchronous rectification switch and a flywheel synchronous rectification switch, which are responsible for rectification on the side of a secondary winding of a transformer, are turned on simultaneously, and the destruction of FETs or windings due to large currents. The DC-to-DC converter comprises a transformer, a primary switching device connected in series with a primary winding of the transformer, a control circuit for controlling turning on or off of the primary switching device, a rectifier synchronous rectification switching device, and a flywheel synchronous rectification switching device, and converts a voltage of a DC power source into another voltage. The DC-to-DC converter further comprises a rectifier rise delay inductive device connected in series with the rectifier synchronous rectification switching device and a flywheel rise delay inductive device connected in series with the flywheel synchronous rectification switching device.

Electronic power supply device

Abstract: A power factor correction circuit (3) has a first rectifier diode (D4) for controlling the serial charging of two capacitors (C1, C2), two rectifier diodes (D5, D6) for controlling the parallel discharging of the two capacitors, and a resistor (R) connected in series with the first diode (D4) in order to enhance the power factor and reduce the power-on current. An electronic current-controlled switch (T1) is used, and the parallel discharge diodes (D6, D5) are Zener diodes for protecting the load circuit against over-voltages just above the peak line voltage value.

Variable structure control of voltage sourced reversible rectifiers

Abstract: The principal result of the paper is a novel control scheme for the voltage sourced reversible rectifier based on variable structure control (VSC) techniques. A time-scale separation property of the rectifier dynamics is identified. This is exploited by using singular perturbation methods to reduce the model order. Conditions are given for global stability. Simulation results are presented for the reversible rectifier operating with a simple type of VSC. These demonstrate an excellent dynamic performance. The design process and experimental results for a conventional space vector modulated control scheme are included for comparison.

Receiver and transceiver for a digital signal of an arbitrary pattern

Abstract: An optical receiving circuit comprises a photo-detector (1), a differential transimpedance amplifier (2), a peak detector (6), a resistor network (4) circuit and a discriminator (3). The transimpedance amplifier (2) receives a current pulse converted by the photo-detector (1) and outputs a non-inverting voltage signal and an inverting voltage signal of the same level. A peak detector (6) for detecting a peak value of the non-inverting voltage signal. A resistor network circuit (4) make an additional operations between an output signal from the peak detector (6) and the inverted voltage signal, and between the non-inverting voltage signal and the non-inverting voltage signal, thereby generating two complemental voltage signals, which have the same amplitude and cross each other at a middle point of the amplitude. The discriminator (3) discriminates a crossing potential at which the two complemental voltage signals generated by the resistor network circuit (4) and generates a pulse-shaped signal with a logical level whose state is changed to another logical state at the crossing potential.

Generating apparatus for providing different rated output voltages to a plurality of electric loads

Abstract: A generating apparatus includes a generator, a first and a second rectifiers, and a voltage regulator. The generator has three-phase star-connected armature windings which generate three-phase high-output voltage at phase-terminals and low-output voltage at a neutral point. The first rectifier is a three-phase full-wave rectifier connected between the phase-winding and a high-voltage load, and the second rectifier is a diode connected between the neutral point and a low-voltage load with a battery. The regulator regulates the high output voltage to energize the high-voltage load and, at the same time, the low-output voltage to become an optimum voltage level for charging battery. MOSFETs may be used for the first rectifier to short-circuit the armature windings thereby supplying them with leading currents which are respectively ahead of the high-output voltages, so as to increase the generator output power.

New 24-pulse diode rectifier systems for utility interface of high power AC motor drives

Abstract: This paper proposes two new passive 24-pulse diode rectifier systems for utility interface of PWM AC motor drives. The first approach employs an extended delta transformer arrangement which results in near equal leakage inductance in series with each diode rectifier bridge. This promotes equal current sharing and improved performance. A specially tapped interphase reactor is then introduced with two additional diodes to extend the conventional 12-pulse operation to 24-pulse operation from the input current point of view. The proposed system exhibits clean power characteristics with 5th, 7th, 11th, 13th, 17th and 19th harmonics eliminated from the utility line currents. The second scheme is a reduced kVA approach employing autotransformers to obtain 24-pulse operation. The kVA rating of the polyphase transformer in the second scheme is 0.18 P/sub o/ (PU). Detailed analysis and simulations verify the proposed concept and experimental results from a 208 V, 10 kVA rectifier system are provided.

Analysis and design of constant-frequency peak-current-controlled high-power-factor boost rectifier with slope compensation

Abstract: This paper presents the analysis and the design of a peak-current-controlled high-power-factor boost rectifier, with slope compensation, operating at constant frequency. The input current shaping is achieved, with continuous inductor current mode, with no multiplier to generate a current reference. The resulting overall circuitry is very simple, in comparison with the average-current-controlled boost rectifier. Experimental results are presented, taken from a laboratory prototype rated at 370 W and operating at 67 kHz. The measured power factor was 0.99, with a input current THD equal to 5.6%, for an input voltage THD equal to 2.26%.

DV/DT limiting of inverter output voltage

Abstract: A voltage rise limiting circuit (10) for use in conjunction with an inverter-driven induction motor (14). The circuit (10) includes capacitors (C4, C5, C6) connected in a delta configuration, with each node (64, 66, 68) coupled between an inductor (L7, L8, L9) and an input line of a diode bridge rectifier. The rectifier clamps positive voltage levels, putting trapped energy back into the do inverter bus.

Multilevel three-phase rectifier with sinusoidal input currents

Abstract: A multilevel three-phase PWM rectifier absorbing sinusoidal and in phase mains currents is proposed in this paper. The article deals with this new structure, its control and the way to balance the voltage of the output capacitors in order to optimize its characteristics without disturbing the current waveform.

Active rectification and battery protection circuit

Abstract: An active rectifier circuit for automatically selecting a pathway for reversible current to move. The rectifier circuit includes a transistor element that is preferably a MOSFET controlled by an amplifier. The amplifier is coupled to a reference voltage source that regulates operation of the transistor element at a potential much lower than is currently available with diode devices. In one application, the rectifier is a battery protection circuit for use within rechargeable battery packs. The battery protection circuit employs the amplifier to drive a pair of discrete MOSFETs having their sources coupled together. In this application, the amplifier functions as a sensitive current detector. The battery protection circuit automatically detects when any battery cell is over-charged or under-charged thereby opening and protecting the MOSFETs. The battery protection circuit determines the direction of current flow within the battery pack. It also automatically detects safe conditions for recovery from an over/under discharge or overcurrent conditions. Optional digital switches may be employed to regulate on, off, and direction of current flow permitted through the MOSFET pair, which effectively is a low-turn-on-threshold reversible diode.

Method of making a high voltage rectifier for an integrated circuit chip

Abstract: A high voltage alternating current rectifier circuit for an NMOS or CMOS transistor environment in which four N-channel transistors are simultaneously fabricated distant from a utilization circuit, such as one or more EEPROM transistors. The four N-channel transistors have lightly doped sources and drains formed prior to the time gates are formed, the doping concentrations and the thickness of oxide overlying the gates selected to establish breakdown voltages exceeding 20 volt peaks. This allows an input spiral antenna or other inductor to be used for coupling radio frequency energy and signals from a remote source to a chip having a utilization circuit employing the rectifier circuit as a source of power.

Class D current-driven transformer center-tapped controllable synchronous rectifier

Abstract: We present analysis and experimental results for a phase-controlled, synchronous, transformer center-tapped rectifier. The rectifier is driven by a resonant inverter. A digital control adjusts the phase in the driver of the rectifier MOSFET's. The output voltage is regulated while maintaining a 94% maximum and a 80% minimum efficiency for a 30% line swing, and 50% efficiency for a load swing of 400% from full power. Experimental results are presented for a 10 W rectifier with an output voltage of 3.3 V. Theoretical calculations agreed well with the experimental results, with certain deviations due to the nonidealities of the transformer. The center-tapped topology allows for high efficiency even at 3.3 V and simplifies the control design, providing simple regulation.

Device for generating a control signal dependent on a variable resistance value and apparatus comprising such device

Abstract: A device for generating a control signal voltage which is dependent on a resistance value of a variable resistor (8) includes a transformer (24) having a first winding (22) which is in series with the variable resistor and a rectifier diode (20). A current generator (32) coupled to a power source is coupled to a second winding (26) of the transformer and supplies it with a periodically interrupted current (I2). Upon each such interruption an exponentially decreasing current will flow through the first winding and also through the variable resistor (8). The peak value of the voltage drop produced by such current across that resistor is proportional to the resistance value thereof. It is also produced across the first winding (22) and is detected by the peak detector (62). That constitutes the control voltage (Uc). Since the variable resistor is fully electrically isolated from the power source, it can be safely touched without shock hazard.

Three-phase rectifier circuit having capacitors which are switched into the circuit dependent on the rectifier output voltage

Abstract: A three-phase rectifier circuit for a capacitive load wherein only small current harmonics occur has, at the rectifier input, an inductance and a capacitor arrangement that compensates the reactive power of the inductance. The capacitors can be individually switchable, for the regulation of the rectifier output voltage.

Burst optical signal receiver

Abstract: A burst optical signal receiver receives optical signals produced in a burst form from a predetermined subscribers. This burst optical signal receiver comprises an identifying circuit for comparing the input level of an input optical signal with a predetermined threshold value to identify the input level; a peak detector for detecting and holding the peak value of the input optical signal; a DC feedback circuit for acquiring the DC level of an output of the identifying circuit; and a circuit for producing the predetermined threshold value from the DC level from the DC feedback circuit and the peak value held in the peak detector and supplying the predetermined threshold value to the identifying circuit. The peak detector has a plurality of peak detection sections having different gains and operational dynamic ranges and causes those peak detection sections to operate in accordance with the input level of the input optical signal.

A simple three-phase boost-mode PFC rectifier

Abstract: A simple and economical three-phase boost-mode PFC rectifier is proposed in this paper. The new rectifier is obtained by simplifying the power-circuit of the previously proposed third-harmonic-current modulation scheme and employing a newly developed current-synthesis and modulation technique. Unlike the conventional third-harmonic-current modulation rectifier consisting of a split output-circuit, the proposed rectifier employs a unified output-circuit to simplify the power-circuit and output-voltage control. Further, a unique input-current synthesis is developed to improve the current-waveform. Comparing with the conventional rectifier, the new rectifier obtains a simpler power-circuit, higher-quality of the input-current and a wider DC-voltage regulation-range (or lower minimum output-voltage). In the following, theories of the proposed current-synthesis and the modulation are described. Then experimental waveforms are shown to confirm the validity of the theories and applicability of the rectifier in practice.

Three-phase diode rectifier with low harmonic distortion to feed capacitive loads

Abstract: In this paper, a new technique for shaping the line current and reducing the total harmonic distortion in a three-phase bridge rectifier, feeding a capacitive load, is presented. Using the topology proposed by Ewaldo et al. (1995), a new control technique has been implemented. The main objective here is to minimise the THD of the line current under different load conditions (20% to 100% of full load). A review of the problems inherent in a bridge rectifier feeding a capacitive load and the possible solutions are first presented. Subsequently, the analysis of the new circuit, and the control technique used are described along with simulation results. Finally the experimental results on a 1.6 kW prototype are presented.

Control circuit and system for a switched reluctance machine and method of operating

Abstract: A control circuit for a switched reluctance machine comprises a switch connected with the machine winding across a rectified ac power supply. The switch controls the flow of current through the winding in a primary current path. A silicon controlled rectifier and a capacitor are serially connected across the power supply and a diode is connected from a point between the winding and the switch to a point between the silicon controlled rectifier and the capacitor. In the steady state, the capacitor is charged each time the switch is opened. The switch and the silicon controlled rectifier are actuated together so that the capacitor discharges through the silicon controlled rectifier and the winding until the capacitor is discharged below the supply voltage. Thereafter, the silicon controlled rectifier ceases conduction and energy is drawn from the supply. The circuit avoids the need for a dc link capacitor across the power supply to smooth the supply voltage.

Current mode amplifier, rectifier and multi-function circuit

Abstract: A balanced current amplifier mirrors either a fully differential or single ended input signal into common output circuits in a manner to generate a fully differential output signal without any d.c. bias. Input signal nodes are maintained at a desired voltage by circuit elements other than those of the current mirror circuits, thus freeing the current mirroring elements from having to be sized for this purpose. The sizes of the output transistors are adjustable in order to set the gain of the circuit. In addition to amplifier circuits, a full-wave rectifier, a comparator, and a filter, all operating with current signals, are described. A single circuit module may include all of these circuits with a user provided the capability to program the module to perform any one or more of these functions.

Analysis and simulation of a six-phase generator/rectifier system

Abstract: A 6-phase synchronous machine connected to a rectifier is being used as the power source in many DC systems. In order to investigate power system behavior, it is necessary to simulate the generator/rectifier system accurately and in detail. A method of simulating this system and a comparison with laboratory tests are given in this paper including operation with and without a generator neutral connection.

Discharge lamp control circuit with feedback loop to lower harmonic distortion

Abstract: A circuit arrangement for operating a discharge lamp with a high frequency current comprising input terminals for connection to a source of low frequency supply voltage, a rectifier bridge coupled to the input terminals for rectifying the low frequency supply voltage, and an inverter shunting a first capacitor for generating the high frequency current. The circuit arrangement incorporates two power feedback loops to feed power back to an output terminal of the rectifier bridge. As a result the circuit arrangement has a relatively simple configuration, causes only a very limited amount of harmonic distortion and can be realized with relatively cheap and simple components.

Analysis and design of a current-driven two-inductor ZCS low di/sub D//dt full-wave rectifier

Abstract: An analysis and experimental verification of a current-driven two-inductor zero-current-switching (ZCS) low di/sub D//dt full-wave rectifier are given. The design equations are derived using the time-domain analysis and Fourier series technique. The rectifier operates as a full-wave rectifier with two diodes and a one-secondary winding transformer overcoming the limitations of class D current-driven full-bridge and center-tapped rectifiers and preserving their advantages. The rectifier operates with lower conduction losses than the center tapped rectifier. Moreover, the diodes turn on at zero di/sub D//dt, low d/spl nu//sub D//dt, and turn off at low di/sub D//dt. As a consequence, switching losses are reduced and this rectifier is suitable for a high-frequency and high-efficiency operation. Integrated inductors can be used to reduce the size, volume, and cost of the circuit. A breadboard of the rectifier was designed and tested for a constant output voltage V/sub 0/=12 V, and an output current I/sub 0/ ranging from no-load to 12 A. The rectifier was driven by an off-line AC-AC converter operated at an input r.m.s. voltage varying from 176-270 V and a minimum frequency of 550 kHz. The predicted results are in good agreement with those measured. A full-load efficiency of 89.4% was achieved for the entire AC-DC converter.