Showing papers on "Rectifier published in 1992"

Novel zero-voltage-transition PWM converters

Abstract: A class of zero voltage transition (ZVT) power converters is proposed in which both the transistor and the rectifier operate with zero voltage switching and are subjected to minimum voltage and current stresses. The boost ZVT-PWM converter is used as an example to illustrate the operation of these converters. A 300 kHz, 600 W ZVT-PWM boost, DC-DC converter, and a 100 kHz, 600 W power factor correction circuit using the ZVT-PWM technique and an insulated gate bipolar transistor (IGBT) device were breadboarded to show the operation of the proposed converters. It is shown that the circuit technology greatly improves the converter performance in terms of efficiency, switching noise, and circuit reliability. >

Characteristics of load resonant converters operated in a high-power factor mode

Abstract: The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained. >

Assembly for testing rectifiers and regulators of automotive alternators

Abstract: A test assembly for testing regulators and rectifiers. The assembly includes two main components: a modified alternator and a test board. The test board has a regulator test station, which is electrically connected to the rotor of the modified alternator, and it has a rectifier test station, which is electrically connected to the stator of the modified alternator. The modified alternator is run on a conventional alternator tester and its meter observed. This testing assembly allows regulators and rectifiers to be tested individually at a high amperage (full load) before they are assembled into an alternator.

A single transistor three phase resonant switch for high quality rectification

Abstract: Three new classes of low-cost 3 phi AC-DC high-power-factor/low-harmonic controlled rectifiers are derived from parent DC-DC power converter topologies containing boost-type inputs, buck-type inputs, and quasi-resonant zero-current-switch (ZCS) buck-type inputs. With a single active switch in addition to the diode bridge rectifier, the converters are capable of drawing a high-quality input-current waveform naturally at nearly unity power factor. Thus a simple 3 phi AC-DC high power factor rectifier is obtained. Simulation and experimental results are supplied to demonstrate the validity of the concept. >

Full-wave precision rectification that is performed in current domain and very suitable for CMOS implementation

Abstract: An approach for implementation of full-wave precision rectifiers in CMOS technology is presented, in which the rectification is performed in current domain while both input and output signals are voltages. The rectifier has a very simple structure and both noninverting and inverting circuits can be realized with one op-amp, two current mirrors, and six MOS transistors. The performances of the proposed rectifiers are analyzed and discussed. Extensive computer simulation and experimental results obtained with this and other types of precision rectifiers, which demonstrate many advantages of the proposed techniques over others, are presented. >

Method and apparatus for testing an auxiliary power system

Abstract: A load test system for testing an engine/generator (12) and battery set (14) of a backup power system by simulating a load with desired linear, non-linear and/or reactive load characteristics. The load test system also recharges the battery set (14) after testing. Battery imbalance circuit (40) is connected to battery set (14) to determine whether bad cells are present therein. Controller (110) uses signals from current monitors (24, 125) to monitor the current, and isolation transformer (47) to monitor the AC line voltage. The controller (110) simulates a desired load by causing a rectifier (200) comprising thyristors to turn on at a selected point on the AC waveform and/or by causing a load bank (300) to draw a predetermined load current when a predetermined load voltage is present. Capacitive load circuit (28) selectively places a large capacitance across the DC bus (203). When the capacitance is present, surge current at thyristor turn-on simulates a non-linear or reactive load. The amount of surge current is determined by the turn-on point of the thyristors, the value of the capacitance, and the degree of discharge caused by the load bank (300).

Ignition system for combustion-powered tool

Abstract: For a combustion-powered tool, an ignition system is powered by a battery and is arranged so that a sudden discharge of a capacitor, as charged via an oscillator, produces a spark at a spark gap of a spark plug, so that the oscillator is enabled if a trigger switch is closed while a head switch is closed, but not if the trigger switch is closed while the head switch is opened, and if a battery voltage, as monitored, is not less than a reference voltage, and so that a silicon-controlled rectifier, which is arranged to produce a sudden discharge of the capacitor, is switched to a conductive state if the capacitor voltage, as monitored, and is not less than a reference voltage. The head and trigger switches, which are photoelectric, are polled intermittently to determine whether they are closed. Predominantly, solid-state components are used.

Class E resonant low dv/dt rectifier

Abstract: A class-E resonant low dv/dt rectifier is analyzed and experimentally tested. All major parasitic reactive components are included in the rectifier topology. The diode capacitance and the leakage inductance of the isolation transformer and lead inductances are absorbed into the resonant inductance. Therefore, the rectifier is suitable for high-frequency applications such as resonant DC-to-DC converters. The rectifier is driven by a sinusoidal voltage source. Equations governing the circuit operation are derived using Fourier techniques. Experimental results are obtained at 1 MHz and an output voltage of 5 V. The design equations show good agreement with the measured circuit performance. >

Calculation of harmonic currents in a three-phase convertor with unbalanced power supply conditions

Abstract: The paper proposes a practical new method for calculating the harmonic currents of a three-phase bridge controlled rectifier under unbalanced supply conditions. Analytical equations for the harmonic currents are derived, taking into account the effects of DC current ripple and overlap angle. The proposed method is based on the frequency domain method and the rectifier switching functions. All the calculations are conducted only by algebraic calculations, and the accuracy is within 1.1% and 2.6% for the DC and AC side harmonics, respectively. The validity of the proposed method is demonstrated by comparison with the results of digital simulation.

Signal transmission and tag power consumption measurement circuit for an inductive reader

Abstract: A field coil signal transmission and tag power consumption measurement circuit is disclosed for use in an inductive tag reader system. The circuit is coupled to an oscillator (20) which provides a drive signal to a differential driver (27). The driver (27) transforms the clock signal into first and second complementary drive signals (23 and 25). The drive signals are coupled to a field coil (50) through a plurality of capacitors (16 and 18) for inductively producing an output power signal. The capacitors are differentially coupled to the coil (50), so that each input of the coil is coupled to one of the clock signals through a separate capacitor. A bridge rectifier (52) is coupled to the field coil (50) opposite the capacitors (16 and 18) for producing an output comprising a direct current (DC) element and an alternating current (AC) element superimposed on the DC element. A resistance-capacitance (R-C) filter (62), coupled to the bridge rectifier (52), provides a filtered rectifier output signal. The output signal can be decoded downstream of the R-C filter using several different decoding schemes known in the art.

Semiconductor rectifier having high breakdown voltage and high speed operation

Abstract: A semiconductor rectifier having a high breakdown voltage and a high speed operation is provided, which comprises a semiconductor substrate including a first semiconductor layer of one conductivity type and a second semiconductor layer of one conductivity type provided on the first semiconductor layer, a third semiconductor layer of an opposite conductivity type having a depth D and formed in the second semiconductor layer to provide a pn junction therebetween, the third semiconductor layer defining a plurality of exposed regions of the second semiconductor layer, each of the plurality of exposed regions of the second semiconductor layer having a width W, a relation between the depth D and the width W being given by D≧0.5W, and a metal electrode provided on the substrate surface.

Real-time multi-DSP control of three-phase current-source unity power factor PWM rectifier

Abstract: The design of a real-time multi-DSP controller for a high-quality, six-valve, three-phase, current-source, unity power factor, PWM rectifier is discussed. With the decoupler preprocessor and the dynamic trilogic PWM trigger scheme, each of the three input currents can be controlled independently. Based on the a-b-c frame system control and the fast parallel computer control, the pole placement control method is implemented successfully to achieve fast response in the AC currents. The low frequency resonance in the AC filter LC networks has been damped effectively. The experimental results are obtained from a 1 kVA bipolar transistor current-source PWM rectifier with a real-time controller using three TMS320C25 DSPs. >

High frequency low voltage CMOS diode

Abstract: A CMOS class AB rectifier is presented. It can operate at 100MHz for 2μm CMOS technology and with ±1.5V supplies. Simulations and experimental results from a CMOS test chip are shown that verify the proposed circuit.

Signal transmission and tag reading circuit for an inductive reader

Abstract: A field coil signal transmission and tag reading circuit is disclosed for use in an inductive tag reader system. The circuit is coupled to an oscillator which provides a drive signal to a differential driver. The driver transforms the clock signal into first and second complementary drive signals. The drive signals are coupled to a field coil through a plurality of capacitors for inductively producing an output power signal. The capacitors are differentially coupled to the coil, so that each input of the coil is coupled to one of the clock signals through a separate capacitor. A bridge rectifier is coupled to the field coil opposite the capacitors for producing an output comprising a direct current element and an alternating current element superimposed on the DC element. A resistance-capacitance (R-C) filter, coupled to the bridge rectifier, provides a filtered rectifier output signal. The output signal can be decoded downstream of the R-C filter using several different decoding schemes known in the art.

Power generation system having induction generator and controlled bridge rectifier

Abstract: A power generation system is constituted by an induction generator and a converter. An output current waveform of the induction generator is determined by the magnetic flux, speed, winding impedance, DC output voltage, and load of the induction generator. In particular, the output current waveform is changed in accordance with a change in speed (i.e., change in slip). Switching elements in the converter are ON/OFF-controlled in accordance with changes in current waveform, thereby controlling power generation of the induction generator.

Miniature rotating rectifier assembly

Abstract: A modular rotating rectifier assembly for use with a brushless self-excited, liquid cooled, dynamo electric device such as a generator. The rotating rectifier assembly is positioned in a rotating hollow shaft of the generator and is coupled with a coolant circulating system for transferring heat from the rectifier assembly to the coolant flowing therethrough. The rotating rectifier assembly is positioned inside the shaft in close proximity to a central axis, longitudinally extending through the shaft, thereby minimizing the centrifugal forces induced on the diode components of the rotating rectifier assembly.

Integrable CMOS sinusoidal frequency doubler and full-wave rectifier

Abstract: A CMOS integrable circuit technique for the realization of both a sinusoidal frequency doubler and a full-wave rectifier is described in this paper. The realization method makes use of the characteristic of a simple CMOS class AB amplifier configuration. Simulation and experimental results demonstrating the circuit performance are also included.

Power source apparatus for vehicles

Abstract: A power source apparatus for vehicles comprises first and second switch means respectively for controlling charging currents flowing from a rectifier of a generator to first and second batteries having equal open terminal voltages, and third switch means for controlling a current flowing through a field winding of the generator. The third switch means is controlled to be turned on/off in response to whichever of the voltages generated respectively by the first and second batteries is lower. The first and second switch means are controlled to be turned on/off on the basis of a duty factor set based on a voltage difference between the first and second batteries. When the voltage of the first battery becomes equal to or less than a predetermined voltage, that voltage being the lowest voltage that a starter motor needs to satisfactorily start an engine, the duty factor of the first switch means is made larger to charge the first battery with priority irrespective of whether the voltage of the first battery is larger than the voltage of the second battery or not.

Unity power factor control for dual active bridge converter

Abstract: A dual active bridge converter, including high-frequency transformer-coupled input and output bridge converters, receives a rectified ac line voltage via a rectifier acting in a resistive mode and a small, high-frequency filter capacitor. A phase angle controller controls a phase shift between the voltages across the transformer windings such that high-efficiency dc-to-dc conversion is achieved, while maintaining unity power factor at the ac input, using high-density circuitry with small filter components and without adding additional front-end power factor correction circuitry.

Modelling and design of a single phase AC to DC convertor

Abstract: In this paper, a single phase AC to DC convertor consisting of a front end diode rectifier, an active switch and without a current sensor is proposed to achieve high performance and simple control logic. The familiar state-space averaging technique for discontinuous operation mode DC to DC convertors is extended to model the proposed AC to DC convertor with excellent accuracy. Unlike the existing model, which is valid only for very low frequency range(i.e. below line frequency), the proposed model is applicable up to half switching frequency theoretically. Design of the convertor is detailed and some selected experimental results are presented to verify the theory.

Predictive instantaneous value controlled PWM inverter for UPS

Abstract: A microprocessor-based pulse-width modulation (PWM) inverter (UPS) that obtains high-quality sinusoidal output voltage even under a rectifier load is proposed for uninterruptible power supplies. The proposed PWM inverter system uses a closed-loop digital feedback with a sinusoidal reference, and the PWM pattern is determined at every sampling instant. A modification that increases the maximum pulse width, which is limited by the computation time in conventional digital approaches, to provide larger output voltage and a repetitive control technique are applied to the proposed control system. A larger maximum pulse width, stable operation, high output voltage accuracy, very low output voltage distortion, and very fast response are realized. >

Ribbon tension control with dynamic braking and variable current sink

Abstract: A pair of ribbon spools are independently operated by respective motors to rotate in one direction until the ribbon end and then in the opposite direction, and so forth. Spools alternately function as feed and take-up spools and motors as a drive and drag motors, respectively To eliminate excess drag motor cogging, a ribbon tension control system uses dynamic braking of the drag motor, and includes drag circuitry with rectifier bridge circuitry and a constant current sink settable for drawing predefined selectable levels of current from the windings of the drag motor. The motors are polyphase, permanent magnet, stepper motors which, when turned by the ribbon, generate alternating back emf signals in their windings. A full-wave rectifier bridge is connected to each winding of the drag motor with bridge outputs connected to a common sink which is an emitter follower circuit whose current level is set and maintained by an operational amplifier. The current level of the emitter follower circuit is set by adjusting the reference voltage of the amplifier using a resistive voltage divider network connected to a binary switch controlled by a microprocessor with a memory. The microprocessor monitors the back emf signals, periodically adjusts the rotational speed of the drive motor depending on distribution of ribbon, and adjusts the sink based on drag value tables stored in memory.

Electrical power generation system

Abstract: An electrical power generation system for generating controlled AC output including a generator for converting mechanical input into variable frequency AC, a rectifier for rectifying the AC into DC having a variable magnitude, an inverter for inverting the DC into controlled AC output, a feedforward sensor for sensing the rate of change of the DC, a feedback AC sensor for sensing the controlled output AC, and an inverter controller responsive to the rate of change of the DC and to the controlled AC output for regulating the magnitude of the controlled AC output.

A low ripple power supply for high current magnet load

Abstract: The magnet power supplies provide precisely controlled current to the magnets in particle accelerators. As the research in high-energy physics progresses, the required precision of the magnet current is increasing rapidly. Existing magnet power supplies for high-current applications cannot meet the present and future demands. This paper proposes a new magnet power supply for high-current magnets. The proposed system integrates a switch-mode ripple regulator with a phase-controlled rectifier. The results from this paper indicate that the proposed system can provide a magnet current with less than 10 ppm harmonic content and can be expected to have fast dynamic response. In this paper, the general description of the power circuit and system control configuration is presented. Fourier analysis is applied to investigate the harmonic content of the magnet current. The theoretical analysis is verified experimentally. A design example is given. >

Power feed-back during controller failure in inverter fed permanent magnet synchronous motor drives with flux weakening

Abstract: When permanent magnet synchronous motors are operated in the flux weakening region, the internal voltage can be much larger than the DC link voltage. If the switching signals are blocked, the freewheeling diodes act as a rectifier, and the motor will feed power back into the inverter. The magnitude of the feedback power during such controller failure is investigated. Simulations and approximate analyses are used to obtain descriptive and comparative curves. Measurements verify the computer results but also show that nonlinear effects could have significant influence. >

Development of a high-speed elevator controlled by current source inverter system with sinusoidal input and output

Abstract: An inverter elevator (2.5-4 m/s rated speed) which is controlled by a current source inverter system with sinusoidal input and output is developed. In comparison with a conventional DC elevator controlled by the thyristor Leonard system, it has the following features: (1) a reduction of higher harmonic currents to less than 5%; (2) more than a 30% reduction of power source capacity; (3) more than a 10% reduction of energy consumption, and (4) a 40% reduction of traction machine weight. The sinusoidal pulsewidth modulation control of the converter and inverter, performed by one-chip microprocessors, is described along with a detection and protection system for abnormal overvoltage. A general description of the elevator's performance is given. >

A unity power factor current-regulated SPWM rectifier with a notch feedback for stabilization and active filtering

Abstract: A stand-alone, unity power factor, current-regulated sinusoidal pulsewidth modulated (SPWM) rectifier is described. The topology is based on the series connection of three four-valve single-phase bridges, which allows the conventional two-stage logic SPWM strategy to be used without interphase interference. The problems of stability and low harmonic waveform distortion are identified. Solutions are found by using a simple local notch filter feedback circuit that fulfils the dual function of stabilizing and active filtering. From the clarification given by this more expensive but less constrained topology, the stage is set for the next step in incorporating the lessons learned to the more economical topology based on the six-valve, three phase parallel bridge, which requires a tristate logic for PWM control when operating in the current-source configuration. >

Rectifier circuit including FETs of the same conductivity type

Abstract: A rectifier circuit is constructed entirely with field-effect transistors of the same conductivity type and which provides rectification with a small voltage drop and hence a high efficiency. A normally-off FET is coupled between an alternating voltage input and a direct voltage output. A bias circuit biases the gate of this FET so as to reduce the effective threshold voltage of the FET substantially to zero. Bridge rectifier circuits, based on this principle make it possible to obtain both half-wave and full-wave rectification with a very small voltage drop. Various circuits for generating the gate bias are disclosed.

AC to DC converter system with ripple feedback circuit

Abstract: A ripple feedback circuit for use with a current-sourced rectifier system with a resonant load balancing filter. The ripple feedback circuit eliminates the oscillation of the rectifiers and improves the line-current waveform by sensing the low frequency AC components of the output current and by combining such AC components with the control voltage at the input to the multiplier of the pulse width modulator of the rectifier system. A sample of the rectified line voltage is multiplied by the control voltage less ripple feedback to form the input to the pulse-width modulator which produces the gating waveform for the converter of the rectifier system.