Showing papers on "Buck–boost converter published in 1982"

A Regulated DC-DC Voltage Source Converter Using a High Frequency Link

Abstract: Power converters which employ a high frequency (HF) link possess several attractive features such as reduced size of reactive components, fast response, and ease of commutation. Either series or parallel connection of the load to the link capacitor can be employed by such converters. Converters that have a series link capacitor-load configuration are seen by the load as a current source. A dc-dc converter which uses a parallel link capacitor-load configuration is investigated. The output dc voltage is regulated by varying the link frequency. Such a converter behaves as a voltage source and is suitable for voltage source inverter applications. The converter is analyzed. Based on the analysis, a design procedure is given. A control scheme is outlined. Results from a prototype converter are presented.

Regulated dc-dc converter using a resonating transformer

Abstract: A resonant dc-dc converter employing power transistors as the switching elements generates a high dc output voltage (150 kilovolts) to drive an X-ray tube. The converter is configured such that the resonating circuit elements can be realized using the transformer parasitic elements. Voltage step up is achieved due to the transformer turns ratio as well as the resonant rise of voltage across the energy storage elements of a series resonant circuit.

Modeling the Full-Bridge Series-Resonant Power Converter

Abstract: A steady state model is derived for the full-bridge series-resonant power converter. Normalized parametric curves for various currents and voltages are then plotted versus the triggering angle of the switching devices. The calculations are compared with experimental measurements made on a 50 kHz converter and a discussion of certain operating problems is presented.

Cascade-comparator A/D converter

Abstract: In an A/D converter in which a first comparator A/D converter for providing the most significant bits of a digital output and a second comparator A/D converter for providing the least significant bits of the digital output are cascaded, a switching circuit is provided between the first A/D converter and the second AID converter This switching circuit is responsive to the comparison between an analog input voltage and first comparison reference voltages in the first AID converter to apply two adjacent first reference voltages between which the analog input voltages lies to both ends of a voltage dividing circuit network of the second A/D converter to thereby provide second comparison reference voltages In the second A/D converter, the second comparison reference voltages are compared with the analog input voltage by comparators, to provide the least significant bits of a digital output

A dual mode forward/flyback converter

Abstract: This paper presents a single transistor dc-dc converter that combines both forward and flyback action. The resulting circuit is ohmically isolated and can operate over a wide range of input-to-output voltage ratios. An analysis of the circuit indicates that the forward and flyback portions of the circuit interact to produce three distinct regions of operation. With the design information presented, the circuit can be tailored to utilize the desirable characteristics of either converter action for a specific application. The dynamics of the dual mode circuit are modeled by means of the state-space averaging technique. An ac-dc regulator that takes advantage of the wide operating range of the dual mode circuit operating off the ac line, with only a small input filter, is described.

Core reset for single-ended dc-to-dc converter

Abstract: Saturation is avoided in the core of the transformer used for direct conversion in a single-ended dc-to-dc converter of the type using auxiliary flyback conversion through a plural-winding inductor. This is done by resetting the core with a winding threading the core, through which winding the secondary current of the plural-winding inductor passes.

Converter control apparatus for parallel connected multi-terminal direct current system

Abstract: Two rectifiers and two inverters are operated under the state under which they are connected in parallel by common transmission lines. These rectifiers and inverters are controlled an independent control apparatus respectively which can selectively apply either the constant current control or the constant voltage control. The control apparatus of each converter has bestowed thereon the reference value of a current to flow through the particular converter and the reference value of a terminal voltage of the particular converter. A signal for lowering the current reference value is added to the control apparatus of one or all of the converters which are to be operated as the inverters. On the other hand, a signal for essentially rendering the terminal voltage of the converter smaller than the voltage reference value is added to the control apparatus of the converter which is to be operated as the converter for determining the voltage of a direct current system.

High voltage converter

Abstract: A high voltage converter converts an incoming high frequency pulse voltage to a direct voltage at a level which can be varied by varying the pulse width. The converter contains a transformer (T) with its primary side (p) connected to a pulse source (U) and to a controllable switch (K). The secondary side of the transformer is divided into two sections (s 1 , s 2 ). One section (s 1 ) is connected to a rectifier in the form of a conventional voltage doubler circuit (D1, D2, Cd1, Cd2) with capacitors in parallel with the secondary winding sections (s 1 , s 2 ). The other section (s 2 ) is connected to a rectifier bridge (D3-D6) and a smoothing filer (L f , C f ). The converter output is the doubler circuit output in series with the smoothing filter output.

Evaluation and implementation of the optimum magnetics design of the cuk converter in comparison to the conventional buck-boost converter

Abstract: Magnetic components such as inductors and transformers constitute one of the major ingredients of a switching power processing system. This paper presents a detailed comparison and implementation of the magnetic component designs of two functionally similar switching power converters, i.e. the conventional Buck-Boost converter and the new topology Cuk converter, both of which are capable of either stepping up or stepping down the input voltage. A cost effective, computer-aided design approach using the nonlinear programming (NLP) technique is employed to design the magnetic components of these two converters such that the total weight of each converter is minimized respectively.

A four-quadrant current regulated converter with a high-frequency link

Abstract: A novel and highly versatile four-quadrant static converter is discussed. A resonant high frequency link is employed which provides an extremely fast response to external commands and a wide frequency range of converter operations. This converter is therefore very suitable for four-quadrant DC chopper and constant or variable frequency inverter applications.

Characteristics of a New Series Resonant Converter

Abstract: This paper describes a new series resonant converter for a 150-volt dc power supply system. This converter has been studied in order to overcome the disadvantage of conventional series resonant converters which must widely vary the conversion frequency to keep the output voltage constant, thus causing audible noise under light-load conditions. A series resonsnt circuit is added parallel to the output circuit of the conventional converter. By utilizing the impedance characteristics of the additional circuit, the output voltage can be regulated with less conversion frequency variation than in conventional circuits. From experimental results, the conversion frequency variation necessary to keep the output voltage constant in a 0-to-100 ampere output current range was found to be only about 30% of that of conventional circuits. The conversion efficiency of this converter is about 85% at 100 ampere output current.

A controllable power source

Abstract: A controllable power source is suitable for driving one or more electric motors from a low voltage battery. A converter steps up the d.c. voltage to a higher level at which the motors are designed to operate and a power regulator placed between the converter and each motor regulates the power which is drawn at the higher voltage by the motors. A current limit is imposed on the converter which is significantly less than the maximum current handling capabilities of the motors, so that when a motor attempts to draw an excessive current the output voltage of the converter drops accordingly. This enables the overall power handling capability of the converter to be minimize, while still allowing a motor to draw maximum current or maximum voltage, but not both simultaneously.

Analogue to digital converter

Abstract: An analogue to digital converter using several flash converter units to convert successively the increasingly lower orders of resolution, wherein the transition from a stage of lower magnitude of resolution to that stage of successively higher magnitude of resolution is obtained by physically isolating the resistor element of the resistor ladder of the first flash converter wherein the unresolved portion of the input voltage falls, and substituting a second flash converter comprising a resistor ladder of same total resistance as the resistor element it replaces but of higher resolution by one order of magnitude; then repeating the same with each successive flash converter.

Controlling method for induction motor

Abstract: PURPOSE: To enable slip frequency to be controlled to always come to a proper value even if a primary resistance is fluctuated, by taking a signal in relation to a secondary resistance fluctuation of a motor from a voltage fluctuation quantity, and by controlling converter output frequency according to said signal CONSTITUTION: The output of current detectors 3U∼3W is fed to a coordinate converter 5 via a three-phase/two-phase converter 4 The outputs of the coordinate converter 5 and current regulators 15, 16 is fed to an arithmetic circuit 18 Output voltage fluctuation component due to the change of a secondary resistance of a motor 2 from the arithmetic unit 18 is applied to an adder 23, and the frequency of the motor 2 from an adder 26 is sent to a coordinate reference generator 13 and a voltage command arithmetic circuit 14 From the voltage command arithmetic circuit 14, the voltage component command of a revolving-field coordinate system is applied to adders 21, 22 and the output is sent to a coordinate converter 17 By the voltage command of a stator coordinate system from the coordinate converter 17, via a PWM controlling circuit 19, a power converter 1 is controlled COPYRIGHT: (C)1989,JPO&Japio

DC to DC converter with self-starting flyback oscillator

Abstract: A power supply for an acoustic fuel injector (18) comprises a DC to DC converter (14) for supplying a regulated voltage to a frequency-controlled oscillator (16) which drives the injector valve or valves. The converter (14) comprises a flyback oscillator (28) including a switching transistor (32) and a transformer (34, 36) for applying rectified current pulses of variable amplitude and occurrence rate to an output capacitor (42). A variable impedance transistor (50) in the input circuit to the flyback oscillator (28) is controlled by a feedback signal (68) from the output circuit (30) to vary the cycle rate of the flyback oscillator (28) to maintain output voltage at a desired value. Start up of oscillations in flyback oscillator (28) is assisted by a resistive feedback connection (56) and oscillations are maintained by a tertiary transformer winding (38).

J.N. Park General Electric Corporate Research and Development Schenectady, NY and

Abstract: This paper presents a single transistor dc-dc converter that combines both forward and flyback action. The resulting circuit is ohmically isolated and can operate over a wide range of input-to-outp ut voltage ratios. An analysis of the circuit indicates that the forward and flyback portions of the circuit interact to produce three distinct regions of operation. With the design information presented, the circuit can be tailored to utilize the desirable characteristics of either con­ verter action for a specific application. The dynamics of the dual mode circuit are modeled by means of the state-space averaging technique. An ac-dc regulator that takes advantage of the wide operating range of the dual mode circuit operat­ ing off the ac line, with only a small input filter, is described. The intended application of a power supply generally determines what parameters (size, cost, weight, reliability, etc.) are most carefully controlled in its design. These dom­ inant parameters, along with the electrical specifications, will determine the approach taken. In regulated supplies where high efficiency is desired, the dc-dc switching converter is well suited. Within this category, the designer still has several choices. Each of the various types of high frequency dc-dc converters has its own distinct advantages and disad­ vantages for each application. Often, a compromise is neces­ sary because no single converter topology incorporates all the desired characteristics. The standard single transistor switching topologies are the buck (forward), the boost, and the buck/boost (flyback) cir­ cuits. As the name implies, the transistor in each of these circuits operates as a switch, ideally being either fully on or fully off. The duty cycle D represents the percentage of time the switch is closed. This controls the ratio of charging time to discharging time for the inductor. Since the average volt­ age on the inductor must be zero in the steady state, the ra­ tio V0I Vs is thus constrained by D. Notice that in the buck and boost converters, there is a period when energy flows directly from the source to the load, while in the flyback cir­ cuit the charging interval and the discharging interval do not overlap. If ohmic isolation and step-down capability are required, which is true of the majority of line operated dc supplies, the choice narrows to the isolated forward or flyback circuits shown in Figure 1. Note that the isolated flyback converter 1:N 2 :N 1

Computer Simulations of Optimum Boost and Buck-Boost Converters

Abstract: The development of mathematical models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight and loss profiles of various semiconductor components and magnetics as a function of the switching frequency.

Variable electronic impedance circuit

Abstract: A variable electronic impedance circuit contains a voltage-current converter having an input terminal which is supplied with an input signal voltage, and a variable-gain current amplifier having an input terminal which is supplied with an output current of the voltage-current converter. The output signal current of the amplifier is fed back to the input terminal of the voltage-current converter. In order to prevent undesirable oscillation immediately after the closure of a power supply switch, the variable electronic impedance circuit includes a control circuit which substantially inhibits the operation of the voltage-current converter for a predetermined time after the closure of the power supply switch.

Control circuit for a dc-ac converter

Abstract: For a d.c.-a.c. converter a control circuit is proposed which improves the efficiency of the converter and enables it to operate at a higherfrequency using the same semiconductor switches. For this purpose the residual voltage across the currently conductive switch (9, 10) is compared with a reference voltage (23) via an analog OR-gate (26) and the control signal for the conductive switch is controlled in such a way that the residual voltage is set to a desired value (19, 20, 21, 11, 13, 14). The converter with the control circuit is extremely suitable for use as a high-efficiency power-supply for fluorescent lamps and occupies the smallest possible volume.

The stability of DC/DC converters in current programmed mode

Abstract: Recent work on current programmed DC/DC converters has indicated.that these systems are unstable for duty cycles greater than 0–5 and this is independent of the precise configuration (boost, buck or buck-boost.) used in the converter. The purpose of this note is to show that the above result is incorrect ; the- boost and bunk-boost are always stable and the buck is stable for all duty cycles less than an amount determined by tin; circuit parameters and the switching frequency. In addition explicit expressions are obtained for the small-signal linearized model describing a converter in current programmed mode and an alternative method for stabilizing the buck converter is proposed.

Overcurrent protecting circuit for dc/dc converter

Abstract: PURPOSE:To effectively operate a DC/DC converter even when a load is abruptly shortcircuited by protecting the primary or secondary coil current of a main transformer by utilizing the average value and the maximum value of the DC current corresponding to the primary or secondary coil current. CONSTITUTION:The input current of a DC/DC converter 1 is removed, a pulse width control circuit 2 is operated by the average current corresponding to the input current, thereby protecting the converter 1. The voltage corresponding to the maximum value of the input current of the converter is produced form a resistor RV2, and the difference between the voltage and the reference voltage E2 is obtained by a comparator 4. When the voltage corresponding to the maximum value of the input current of the converter 1 is larger than the reference voltage E2, a stop signal is immediately fed to a half-cycle stop circuit 5, and the vibration is stopped only during the half period.

Stable wideband ac–dc converter

Abstract: This paper describes improvements on a stable wideband ac–dc converter, which is basically composed of a dual junction field effect transistor and a low drift operational amplifier. This converter has a stable square‐law transfer characteristic up to 200 MHz for 0–0.5 V output with a drift of less than 0.1 mV/h. Its input capacitance is 6–10 pF and input conductance is negligibly small. It can also be used as a well‐balanced differential converter for two ac inputs. With the combination of several temperature compensation techniques, the temperature dependence of the output level is reduced to −0.1%/ °C.

Analysis and Design of an Adaptive Multiloop Controlled Two-Winding Buck/Boost Regulator

Abstract: Small-signal low-frequency linear average model is derived for a multiloop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multiloop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle modulation. It also can provide stabilization effect by shifting the positive zero to the left-half S-plane. Design guidelines are formulated to optimize regulator-loop dependent characteristics.

Circuitry and method of operation for an intermediate-like converter

Abstract: Circuitry for, and method of operating, an intermediate-link converter of the type wherein two controlled antiparallel-connected converters are connected via an intermediate link having an impressed voltage to an inverter having a plurality of addressable switches in a three-phase bridge circuit. The polarity of the intermediate-link current is interrogated 30° after every change of the addressing combination of the switches of the inverter. If the interrogated polarity of the intermediate-link voltage is larger than a desired value by a predetermined amount, the converter which is arranged in the feeding-in direction is switched off and the other converter, which is arranged in the feedback direction is switched on. In this manner, a load connected to the inverter can feedback energy into a supply network via the intermediate link and a converter operating as an inverter.

Simplified Isolated Forward Converter

Abstract: This thesis pertains to a forward converter consisting only of primary-side control circuits for regulating the output voltage. Control circuits in a conventional forward converter for regulating the output voltage control the on and off times of primary-side switching transistor by comparing the output voltage directly with the reference voltage. To isolate the primary from the secondary, the converter must contain not only the main transformer but also insulated transformers in control circuit power supply and transistor driver circuits. Since the forward converter described in this thesis converts output voltage to primary-side voltage proportioned to the output voltage by the main transformer, all control circuits in the converter can be configured on the primary side; to isolate the primary side from the secondary side, only the main transformer need be insulated. The converter generates a fly-back voltage from energy stored in the main transformer by turning a transistor on and cramps the voltage at a level proportional to the output voltage. This thesis describes how this forward converter produces stable output.

Direct voltage converter with a pulse width controlled semiconductor switch

Abstract: Der Gleichspannungswandler weist einen pulsbreitengesteuerten Halbleiterschalter auf, der in Serie zur Primarwicklung w1 eines Leistungstransformators (Tr) liegt. Die Sekundarwicklung (w2) dieses Leistungstransformators (Tr) ist uber ein Gleichrichterelement (Gr1) mit dem Giattungskondensator (Cg) und dem Lastwiderstand (RL) verbunden. Eine Tertiarwicklung (w3) des Leistungstransformators (Tr) ist derart mit dem Glattungskondensator (Cg) verbunden, das dessen uberflussige Energie im Anschlus an die Energieabgabephase des Gleichspannungswandlers bis zur nachsten Energieaufnahmephase in den Kern des Leistungstransformators (Tr) zuruckgespeist wird.

Synchronous electric converter motor

Abstract: An electric converter motor of synchronous design is used as a hoist by supplying two legs of the stator winding with DC current from a frequency converter to maintain the field during standstill. The converter is connected to the power network.

Arrangement for setting the rotation speed of asynchronous machines

Abstract: The invention relates to an indirect converter for setting the rotation speed of asynchronous machines. The aim of the invention is to be able to keep low the cost of smoothing means which are required in the design of a DC voltage or direct-current intermediate circuit for voltage stabilisation and for impressing a current. The invention is based on the object of creating an indirect converter for setting the rotation speed of asynchronous machines, in order to implement an unlimited rotation-speed control range, of varying the magnitude of the mean value of the intermediate-circuit voltage impressed on the machine-side converter or of the intermediate-circuit current impressed on the machine-side converter over a likewise unlimited control range, without influencing the magnitude of the voltage of the commutation capacitors of the machine-side converter and thus its commutation capability by the magnitude of the mean value of the intermediate-circuit voltage impressed on the machine-side converter or of the intermediate-circuit current impressed on the machine-side converter. According to the invention, an intermediate-circuit voltage is impressed on the machine-side converter, which intermediate-circuit voltage varies cyclically in time, whose peak value is essentially constant and whose mean value is adjustable.