Showing papers on "Precision rectifier published in 2002"

Reduced-parts-count multilevel rectifiers

Abstract: Multilevel power converters have gained much attention in recent years due to their high power quality, low switching losses, and high-voltage capability. These advantages make the multilevel converter a candidate topology for the next generation of naval ship prolusion systems. The primary disadvantage of these systems is the large number of semiconductors involved. This paper presents a reduced-parts-count rectifier which is well suited for naval rectifier applications where bidirectional power flow is not required. The proposed converter is analyzed and experimentally verified on an 18-kW four-level rectifier/inverter system.

Analog CMOS peak detect and hold circuits. Part 2. The two-phase offset-free and derandomizing configuration

Abstract: An analog CMOS peak detect and hold (PDH) circuit, which combines high speed and accuracy, rail-to-rail sensing and driving, low power, and buffering is presented. It is based on a configuration that cancels the major error sources of the classical CMOS PDH, including offset and common mode gain, by re-using the same amplifier for tracking, peak sensing, and output buffering. By virtue of its high absolute accuracy, two or more PDHs can be used in parallel to serve as a data-driven analog memory for derandomization. The first experimental results on the new peak detector and derandomizer (PDD) circuit, fabricated in 0.35mm CMOS technology, include a 0.2% absolute accuracy for pulses with 500 ns peaking time, 2.7 V linear input range, 3.3 mW power dissipation, 250 mV/s droop rate, and negligible dead time. The use of such a high performance analog PDD can greatly relax the requirements on the digitization in multi-channel systems. r 2002 Elsevier Science B.V. All rights reserved.

Integrated magnetic converter circuit and method with improved filtering

Abstract: A converter and rectifier circuit comprises a magnetic core, a first secondary winding, a second secondary winding, a third secondary winding, a first rectifier, a second rectifier and an output capacitor. The first, second and third secondary windings are wound around the magnetic core and are connected to each other. The first rectifier is connected to the first secondary winding and the second rectifier is connected to the second secondary winding. The output capacitor is connected to the first and second rectifiers and is connected in series with the third secondary winding.

Digitally controlled low-harmonic rectifier having fast dynamic responses

Abstract: This paper describes a completely digitally controlled low-harmonic rectifier. It is shown that the dynamics of the outer voltage loop can be significantly improved using a digital notch filter. Low input current harmonics and fast voltage response are experimentally verified using a 200 W universal-input boost power supply operating at the switching frequency of 200 kHz.

Circuit for converting AC voltage into DC voltage

Abstract: The invention relates to a circuit for converting AC voltage into DC voltage for one or two consumers (Rm, Ra), in which circuit a first part of the current is fed to the input side via a large induction coil (L 50 ) and a first rectifier (Gm) and a second part of the current via a second rectifier (Ga) upstream of the large induction coil On the output side, behind the second rectifier (Ga), a switched-mode power supply is arranged, preferably in the form of an up-converter or a flyback converter ( 10 ) The division of the applied current for smoothing the output voltage provides that the induction coil (L 50 ) can be accordingly dimensioned smaller and, despite this, the circuit can also satisfy relevant standard specifications

D-Q modeling and control of a single-phase three-level boost rectifier with power factor correction and neutral-point voltage balancing

Abstract: This paper deals with the analysis, design and operation of a control system for a single-phase three-level rectifier with a neutral-point-clamped (NPC) topology. Usually the desired operating conditions for this type of converter are: unity displacement factor, output DC voltage regulation and neutral point voltage balancing. A d-q reference frame has been used in this work to model the rectifier behaviour in order to exploit the results obtained in the field of three-phase converters. In this way, a space vector modulation PWM method has been used, with the possibility of using redundant switching states to achieve charge balancing of the capacitors. The time assignment of each redundant switching state is accomplished by utilizing a closed-loop control system. Validity of the modeling and control strategies are confirmed by the transient and steady state simulation and experimental results.

Multiple input single-stage inductive charger

Abstract: An inductive charger includes a rectifier that can be connected to both single- and three-phase power sources. The rectifier includes first, second and third legs that include first and second diodes. Alternately, the third leg includes first and second silicon-controlled rectifiers. A capacitor is connected across an output of the rectifier. An inverter is connected to the rectifier and the capacitor and includes a plurality of switching circuits. A series resonant tank circuit is connected to an output of the inverter. A charge coupler and an inductive inlet include a transformer and a parallel resonant tank circuit for coupling energy to a load. A controller is connected to the rectifier and the inverter. The controller generates drive signals for controlling the switching circuits. The inductive charger is capable of providing approximately 0.99 power factor from single-phase and 0.91 power factor at twice the output power from three-phase power sources.

Sensing methods and systems for hall and/or mr sensors

Abstract: Magnetic sensing methods and systems are disclosed. A minimum magnetic signal output and a maximum magnetic signal output can be detected utilizing a sensor comprising a peak detector circuit associated with a filter averaging circuit and one or more magnetic elements (e.g., a Hall element and/or magnetoresistive bridge). An average magnetic signal output can then be determined utilizing the filter averaging circuit when a target begins to rotate in front of the sensor. A minimum magnetic signal output and a maximum magnetic signal output can be detected utilizing a sensor that includes a peak detector circuit associated with a filter averaging circuit and one or more magnetic elements (e.g., a Hall element and/or magnetoresistive bridge). An average magnetic signal output can then be determined utilizing the filter averaging circuit when a target begins to rotate in front of the sensor.

Direct power control of three-phase PWM rectifier using space vector modulation-simulation study

Abstract: This paper proposes a novel and simple direct power control of three-phase PWM rectifiers with constant switching frequency using space vector modulation (DPC-SVM). The active and reactive power is used as the pulse width modulated (PWM) control variables instead of the three-phase line currents usually used. Moreover, line voltage sensors are replaced by a virtual flux (VF) estimator. The theoretical principle of this method is discussed. The steady state and dynamic results of DPC-SVM that illustrate the operation and performance of the proposed system are presented. It is shown that DPC-SVM exhibits several features as: simple algorithm, good dynamic response, constant switching frequency and particularly provide sinusoidal line current when supply voltage is not ideal. Results have proven excellent performances and verify the validity of the proposed system.

Soft start for a synchronous rectifier in a power converter

Abstract: Circuit and method for controlling circuitry in a power converter device during a soft-start process is provided. Synchronous rectifier control circuitry is adapted to gradually apply a gate drive signal derived from the main switch of the power converter device to a freewheeling synchronous rectifier of the switching circuitry during the soft-start process. The control circuitry gradually releases the amplitude or the pulse-width of the gate drive signal to the freewheeling synchronous rectifier to avoid a large duty ratio in the synchronous rectifier during start-up so that a negative current does not build up in the output inductor.

A new, soft-switched, high-power-factor boost converter with IGBTs

Abstract: A new soft-switching technique that improves performance of the high-power-factor boost rectifier by reducing switching losses is introduced. The losses are reduced by an active snubber which consists of an inductor, a capacitor, a rectifier, and an auxiliary switch. Since the boost switch turns off with zero current, this technique is well suited for implementations with insulated-gate bipolar transistors. The reverse-recovery-related losses of the rectifier are also reduced by the snubber inductor which is connected in series with the boost switch and the boost rectifier. In addition, the auxiliary switch operates with zero-voltage switching. A complete design procedure and extensive performance evaluation of the proposed active snubber using a 1.2 kW high-power-factor boost rectifier operating from a 90 V/sub rms/-256 V/sub rms/ input are also presented.

Analog power detection for gain control operations

Abstract: A method and apparatus for dynamically controlling a programmable gain amplifier (PGA) in a radio receiver to provide a plurality of gain steps thereby providing automatic gain control (AGC) in a receiver intermediate frequency (IF) stage comprises an analogy peak detector formed to including a constant current source and a plurality of MOSFETs all configured to produce an output voltage (DC) whose value reflects a peak amplitude of a received differential quadrature phase shift keyed (QPSK) signal. A first circuit portion generates currents that are proportional to the square of the magnitude of the gate to source voltage for each of a plurality of MOSFETs coupled to receive the differential QPSK signal and a second circuit portion produces a voltage that is equal to the square root of the sum of the squares of the currents produced (drawn) by the MOSFETs of the first circuit portion.

Inverter control method of IPM motor to improve power factor of diode rectifier

Abstract: This paper proposes a novel control strategy to improve input power factor of the single phase diode rectifier. The proposed power converter doesn't need energy storage units such as an electrolytic capacitor or a reactor. So there are many ripples across the DC-bus voltage and then, the input power factor can be improved. The proposed system consists of an only diode rectifier, a small film DC capacitor, a three phase inverter and an interior permanent magnet (IPM) synchronous motor. The basic ideas are based on two following operations. First, the inverter's controlled synchronous with the DC-bus ripple voltage by field-weakening method. The other is direct active power control from the source to the motor without smoothing the DC-bus voltage. This paper shows that the proposed method can obtain the input power factor over 97% by experimental tests, and realize the small size and the long life of the system.

A low-voltage wide-band CMOS precision full-wave rectifier

Abstract: A simple integrable circuit for implementing a precision full-wave rectifier circuit in CMOS technology, which can be operated from a low-voltage power supply, is described. The realization method is based on the use of a MOS class AB configuration to improve the high frequency performance. The circuit exhibits a very sharp corner in the dc transfer characteristic. Simulation results showing the performance of the proposed circuit are also presented.

Low power mode detection circuit for a DC/DC converter

Abstract: A DC/DC converter has a semiconductor switch coupled to an inductor, a capacitor and a rectifier. A comparator is coupled to across the rectifier to detect a polarity reversal during the second portion of converter operation to place the converter in a low power mode if the voltage across the rectifier is of an appropriate polarity for reverse current flow. In some embodiments of the invention, the rectifier is a synchronous rectifier transistor and the voltage converter is placed in a low power mode when the polarity across the synchronous rectifier indicates that reverse current flow is possible. A timing circuit delays the generation of the control signal to place the converter in a low power mode until the steady state current is below a predetermined threshold for a predetermined amount of time. The synchronous rectifier may be turned OFF when the current through the converter falls below another predetermined threshold value and the voltage across the synchronous rectifier will become the voltage across the parasitic diode of the FET synchronous rectifier.

Fully integrated power supply design for wireless biomedical implants

Abstract: Describes the implementation of several fully integrated on-chip rectifier designs in BiCMOS technology for rectifying the externally generated RF magnetic power and data carrier signal in wireless biomedical implants to generate an unregulated DC supply. It also presents application of these rectifiers in an integrated dual /spl plusmn/5 V output supply capable of providing up to 50 mW for wireless biomedical implants. New full-wave rectifier topologies and low power circuit design techniques have been employed to decrease substrate leakage current and parasitic components, reduce the possibility of latch-up, and improve power transfer efficiency and high frequency performance of the rectifier block. These circuits have been designed to be used in a wireless neural stimulating microsystem and fabricated in the University of Michigan's single-metal, dual-poly 3-/spl mu/m BiCMOS process. The rectifier areas are in the range of 0.12 to 0.48 mm/sup 2/ and they are capable of delivering more than 100 mW from the receiver coil to the regulator circuitry. The performance of all rectifier designs has been tested and compared using up to 4 MHz carrier.

High performance automatic gain control circuit using a S/H peak-detector for ASK receiver

Abstract: A high performance automatic gain control (AGC) circuit is proposed in this paper. The proposed AGC incorporates a modified sample and hold peak-detector. Circuit operation of this new peak-detector demonstrates superior performance to the conventional one, by keeping and tracking the peak of the input signal at the same time. In addition, the design complexity of the proposed AGC is reduced in both the low pass filter and the demodulator due to the modified peak-detector. Based on simulation results, the complete AGC loop shows very satisfactory circuit operation. Therefore, it is suitable for high performance communication applications such as ASK (amplitude shift keyed) receivers.

Method and apparatus for controlling synchronous rectifiers of a power converter

Abstract: For use in a power converter having a power switch and a synchronous rectifier (301) device coupled between input and output thereof, a control circuit, method of disabling a synchronous rectifier (301) device and a power converter employing the control circuit and method In one embodiment, the control circuit includes a synchronous rectifier (301) controller, coupled to the output of the converter and the synchronous rectifier (301) device, that senses time derivative of the output voltage and disables the synchronous rectifier (301) when the derivative is negative and greater than a predetermined magnitude

AC-to-DC converter

Abstract: A voltage at a capacitor included in a peak detector is equal to a peak output voltage of a full-wave rectifier. A comparator included in a monitor circuit compares an output voltage of the peak detector with a voltage appearing at the capacitor. The comparator inputs a voltage signal corresponding to a compared result, to a switching controller. The switching controller controls a switching operation of a switching device. A power-factor control circuit controls a charge/discharge operation of the capacitor in accordance with a switching operation of the switching device, in a case where an output voltage of a DC-to-DC converter is equal to or less than reference power Pstd [W]. In the case where the output voltage of the DC-to-DC converter is greater than the reference power, the power-factor control circuit controls the charge/discharge operation by directly supplying the capacitor with a current output from a full-wave rectifier.

A multilevel buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications

Abstract: A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multi-level diode rectifier and a modified multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier features reliable operation and low manufacturing cost. In this paper, the operating principle of the proposed rectifier is introduced. A number of design issues are investigated, which include PWM switching patterns, input power factor and line current harmonic distortion. Some design considerations such as the effect of the line inductance discrepancy on system performance are addressed. Experiments on a 5 kVA/208V four-level prototype are carried out for verification.

An improved precision full-wave rectifier

Abstract: A circuit that provides improved precision rectification over a wide frequency band and a wide input voltage range is described. It utilizes an operational amplifier-current-conveyor-hybrid arrangement that results in greater accuracy than the current conveyor-based circuit presented by Khan, El-Ela and Al-Turaigi (International Journal of Electronics, 79, 1995, 853-859).

Three-phase PWM-current-source type PFC rectifier (theory and practical evaluation of 12kW real product)

Abstract: A new 3-phase-bridge PWM current-source-type (CST) (or buck-mode) PFC rectifier for telecommunications energy systems is introduced. The necessity, the advantages and disadvantages of this type PWM rectifier in the application are discussed. Then, a new power circuit topology and modulation scheme to eliminate or mitigate the disadvantages and obtain further new advantages of the PWM-current-source-type PFC rectifier are introduced. The features of the new rectifier obtained by the new PWM scheme have been confirmed through experimental results obtained from a 12 kW real product. Furthermore, variation of the efficiency and total-harmonic-distortion of the input line current for several DC-inductor arrangements are evaluated.

Current driven synchronous rectifier with energy recovery using hysteresis driver

Abstract: A synchronous rectifier using current driven approach is disclosed which can replace diode rectifier in most of the power converter topologies to enable low rectification loss. The present invention comprises a low loss switch and essentially a transformer with at lease one current sensing winding, windings for current sense energy recovery and one driving winding connected to a hysteresis driver which provides driving signal and power for the synchronous rectifier. A hysteresis driver is introduced which can reduce the noise interference to the driving signal, increase the operating frequency range, eliminate the saturation problem of the current sensing transformer and hence provide more flexibility to the transformer design. This synchronous rectifier is self-driven and the driving signal is independent of the input voltage of the converter which enhances its application to wide input range converter. Current sense energy recovery enables power converters to operate at high efficiency and high frequency.

A wide input range active multi-pulse three-phase rectifier for utility interface of power electronic converters

Abstract: In this paper, a wide input range active multipulse rectifier for utility interface of power electronic converters is proposed. The scheme combines a multi-pulse method using a Y-/spl Delta/ transformer and boost rectifier modules. A current control scheme for the rectifier modules is proposed to achieve sinusoidal line currents in the utility input over a wide input range of input voltage and output load conditions. A design example is included for a 208 V to 460 V input, 750 V/sub dc/, 10 kW output rectifier system. Input current THD is less than 5% for almost no load to full load conditions. Simulation results are shown.

PSPICE and MATLAB for Electronics

Abstract: ORCAD PSPICE Capture Fundamentals Introduction PSPICE Schematics DC Analysis PROBE Transient Analysis AC Analysis PSPICE Fundamentals Introduction DC Analysis Transient Analysis AC Analysis Printing and Plotting Transfer Function Command DC Sensitivity Analysis Temperature Analysis PROBE Statement PSPICE Advanced Features Device Model Library File Component Values (.PARAM, .STEP) Function Definition (.FUNC, .INC) Subcircuit (.SUBCKT, .ENDS) Analog Behavioral Model Monte Carlo Analysis (.MS) Sensitivity and Worst Case Analysis (.WCASE) Fourier Series (.FOUR) MATLAB Fundamentals MATLAB Basic Operations Matrix Operations Array Operations Complex Numbers The Colon Symbol FOR Loops IF Statements Graph Functions Input/Output Commands MATLAB Functions M-Files Mathematical Functions Data Analysis Functions Derivative Function (diff) Integration Function (quad, quad8, trapz) Curve Fitting (polyfit, polyval) Polynomial Functions (roots, poly, polyval, and fzero) Save, Load, and Textread Functions Interfacing SPICE to MATLAB Diode Circuits Diode Rectification Schematic Capture of Diode Circuits Zener Diode Voltage Regulator Peak Detector Diode Limiters Operational Amplifier Inverting and Noninverting Configurations Slew Rate and Full-Power Bandwidth Schematic Capture of Operational Amplifier Circuits Active Filter Circuits Transistor Characteristics and Circuits Characteristics of Bipolar Junction Transistors MOSFET Characteristics Biasing of BJT Circuits MOSFET Bias Circuit Frequency Response of Transistor Amplifiers Schematic Capture of Transistor Circuits Feedback Amplifiers Each chapter contains a Bibliography at the end.

Semiconductor converter circuit and circuit module

Abstract: A diode ( 4 ) is a reverse blocking rectifier diode and connected in series to an IGBT ( 3 ) in a direction where a forward current flows in the diode ( 4 ) when the IGBT ( 3 ) comes into an ON state. Further, a diode ( 6 ) is a reverse blocking rectifier diode and connected in series to an IGBT ( 5 ) in a direction where a forward current flows in the diode ( 6 ) when the IGBT ( 5 ) comes into an ON state. A cathode of the diode ( 4 ) and a collector of the IGBT ( 5 ) are connected to each other through a node ( 7 ). A load ( 8 ) is connected to the node ( 7 ). The diodes ( 4, 6 ) are made of silicon carbide (SiC). With such a configuration achieved is a semiconductor converter circuit using a reverse blocking diode in which the forward voltage drop and the amount of reverse recovery electric charges are reduced as compared with a high-speed diode made of silicon.

A single-phase three-level boost type rectifier

Abstract: A novel single-phase rectifier is proposed to draw a sinusoidal line current with nearly unity power factor, achieve a balanced neutral point voltage and regulate the DC bus voltage. With the aid of a neutral point clamping scheme, a three-level PWM driven voltage pattern is generated on the AC side of the proposed rectifier. To track the line current command derived from a DSP based voltage controller and a phase-locked loop circuit, a hysteresis current control scheme is used in the inner control loop. A capacitor voltage compensator is employed to achieve the balanced neutral point voltage. The experimental results based on a laboratory prototype circuit are performed to investigate the effectiveness of the proposed control scheme.

Self-powered synchronous rectifiers

Abstract: A two-terminal self-powered synchronous rectifier (ASR) is provided, together with two-terminal or three-terminal packaged devices that can replace an output diode rectifier (D) in a switched mode power supply. The synchronous rectifier comprises a field-effect transistor (M) having its source-drain path in a first arm ( 11 ) between the two rectifier terminals (A,K), normally a parallel diode (BD) in a second arm ( 12 ), a gate-control circuit (GC) connected to a gate electrode (g) of the transistor (M) for switching the transistor (M) synchronously on and off in accordance with voltage reversal at the two rectifier terminals (A,K), and a charge pump (C,R; C,R,C 2 ,R 2 ) in a third parallel arm for powering the control circuit from the power signal being rectified by the rectifier.

Frequency doubler circuit arrangement

Abstract: A frequency doubler circuit arrangement comprises a full wave rectifier circuit having an input and a first terminal, the first terminal being connected to a first supply terminal via a first current source, and the input forming an input of the frequency doubler circuit arrangement. A biased transistor circuit is also provided, having a first terminal connected to the first supply terminal via a second current source and being connected to the first terminal of the rectifier circuit. Output terminals of the rectifier circuit and the biased transistor circuit form differential output terminals of the frequency doubler circuit arrangement. The respective outputs of the rectifier circuit and the biased transistor circuit may be connected to a second supply terminal via either an active filter load or a passive filter load, such as an inductance-capacitance-resistance filter. Such a frequency doubler circuit may be employed in a radiotelephone device such that a single voltage controlled oscillator may be utilized to provide signal sources at more than one operating frequency.