Showing papers on "Boost converter published in 1979"

A Pulsewidth Controlled AC-to-DC Converter to Improve Power Factor and Waveform of AC Line Current

Abstract: As a method for improving power factor and waveform of ac line current drawn by an ac-to-dc converter a new pulsewidth controlled converter is proposed, its commutation mechanism is described, and experimental results are given which show a good power factor, a good waveform of the line current, and a wide adjustable range of dc output voltage.

Power source system

Abstract: A power source system, which comprises a converter for converting AC power on an AC bus into DC power, a damped filter connected between the AC bus and ground and including a capacitor and an inductor, a diode-rectifying circuit for taking out and rectifying fundamental and harmonic waves produced across the inductor in the damped filter and a circuit for connecting a DC output circuit in the diode-rectifying circuit in series with a DC output circuit in said converter, and in which the rectified output is regeneratively added to the output of the converter.

Buck/boost regulator

Abstract: A voltage regulated DC to DC converter is disclosed which is operable over a wide range of input voltage including voltages greater or less than the desired output voltage The converter uses an inductor and a capacitor as storage elements, the inductor being composed of two windings having a common junction A transformer having a center tap connected to the common junction of the two windings of the inductor is connected at either end of its winding to ground through controlled switches One winding of the inductor and either end of the transformer winding are connected by respective power diodes to the capacitor which supplies the output voltage to a load The other winding of the inductor is connected to a fourth power diode as a clamping diode Input voltage is supplied to the inductor through a third controlled switch A pulse width modulator connected to the output of the converter alternately closes and opens the switches connected to either end of the transformer winding and also closes the switch supplying input voltage to the inductor each time either of the switches connected to the ends of the transformer winding are closed The duty cycle of the closing and opening of the several switches is adjusted by the pulse modulator to regulate the output voltage

A Controllable 45-kW Current Source for DC Machines

Abstract: A new type of dc converter for the drive and control of a 45-kW traction motor in single quadrant operation with an efficiency of 96 percent is presented. An improvement of the converter's reliability is due to the natural termination of thyristor currents, the positive confinement of the maximum momentary current and voltage stresses in the components below preset levels, and the low power dissipation in these components, supported by a definite protection philosophy. The high converter efficiency is attained at full power operation with an internal frequency of 10 kHz. The input impedance maintains its resistive character for all conditions of operation. The output port is characterized as a voltage-limited current source. Test data of an experimental model conclude the presentation of the converter's functional philosophy.

Battery package with dc to dc converter

Abstract: A battery package having a casing which contains at least one electrochemical cell electrically connected to a DC to DC converter. A pair of electrical connections are located on the casing to electrically connect the battery package to a load. The converter conducts and the cell discharges only when a load is present across the electrical connection.

DC-DC Converter for charging a battery by means of a solar cell

Abstract: A DC-DC converter is described of the blocking oscillator type, for charging a battery from a solar cell. The use of a field effect transistor enables the oscillation to be started by the voltage from a single solar cell, even if the battery is fully exhausted. The overall efficiency of the circuit is improved by the use of the base-emitter junction of the switching transistor of the converter as rectifying element for the battery charging current.

Power Factor Improvement with a Modified Phase-Controlled Converter

Abstract: A modified phase-commutated converter with an improved power factor (PF) is presented and is analyzed for both rectifying and inverting modes. The optimal power factor firing control is formulated while taking into account commutation overlaps. Different modes of converter operation are identified and are analyzed in terms of reactive power requirements, power factor, and harmonic distortion on both ac and dc sides. The results are used to compare critically the new converter with a conventional six-pulse bridge.

Dc power transmission control

Abstract: OF THE DISCLOSURE A pair of thyristor converters are connected by a DC power transmission line, and their AC terminals are connected through tapped transformers to AC systems respectively. The output signal of a constant-current circuit in a converter control unit associated with the forward converter is selected to control the gate of the forward converter, while the output signal of a constant-voltage circuit in a converter control unit associated with the reverse converter is selected to control the gate of the reverse converter. When the reactive power is to be controlled, a reactive power signal is applied for the gate control. A voltage limit indication circuit in each control unit receives the AC terminal voltage e2 of the transformer and the DC current Id so as to increase the control angle limit with a decrease in the values of e2 and Id. When the control advance angle or control delay angle determined by the output signals of the control circuits is larger than the control angle limit, this angle is limited to the control angle limit. When the reactive power is to be controlled, the tap position of either transformer is lowered to decrease e2 and to increase the control angle limit thereby widening the controllable range of the reactive power. During the start-stop stage or during the protective operation, the output of the voltage limit indication circuit in each control unit is inhibited to permit free variations of the control angle.

High voltage control of an electrostatic precipitator system

Abstract: There is provided a precipitator system including a voltage controller which produces from an alternating power source a variable output. This variable output drives a high voltage converter which applies a high voltage to a precipitator. This variable output is controlled by a control signal from a command subsystem. Preferably, the command subsystem is operative to repress the drive to the high voltage converter in response to its loading exceeding a predetermined limit during a corresponding limit interval. After this limit interval, the command subsystem is operative to rapidly restore productive drive to the high voltage converter, preferably by the next half cycle of the power source that has a polarity opposite to that existing at the beginning of the limit interval. In this fashion stablized operation is quickly achieved. Also included, preferably, is a conductive element that is coupled to the high voltage converter. This conductive element conducts in response to variations in the extent to which the high voltage converter is being driven. The command system may store successive values of the voltage across the conductive element, using such values to adjust the control signal according to a predetermined relationship. Such an arrangement can be used to adjust the control signal when a spark is imminent, thereby avoiding it.

Push-pull converter with energy saving circuit for protecting switching transistors from peak power stress

Abstract: In a push-pull converter, switching transistors are protected from peak power stresses by a separate snubber circuit in parallel with each comprising a capacitor and an inductor in series, and a diode in parallel with the inductor. The diode is connected to conduct current of the same polarity as the base-emitter junction of the transistor so that energy stored in the capacitor while the transistor is switched off, to protect it against peak power stress, discharges through the inductor when the transistor is turned on, and after the capacitor is discharged the energy now stored in the inductor discharges through the diode. To return this energy to the power supply, or to utilize this energy in some external circuit, the inductor may be replaced by a transformer having its secondary winding connected to the power supply or to the external circuit.

Rotary phase converter

Abstract: A rotary phase converter for connection to a single-phase a.c. power source and adapted to supply polyphase current to a polyphase electrical load. The converter includes a dynamoelectric machine having at least three stator windings and at least first, second and third output terminals, an autotransformer and at least one capacitor. The stator windings of the dynamoelectric machine are oriented symmetrically with respect to each other both physically and electrically and each has a substantially equal number of active turns. The first and second terminals of the dynamoelectric machine are adapted to be connected to the single-phase a.c. power source and they are also outputs of the converter. The autotransformer is connected across the second and third terminals and has at least one tap positioned intermediate the ends thereof to serve as an output of the converter. The capacitor is connected between the first output terminal and the autotransformer tap serving as a converter output. The currents supplied from the converter outputs to the phases of the polyphase load are maintained substantially balanced at full load.

Regulated variable frequency DC/DC converter

Abstract: This circuit converts a DC voltage of one value to a regulated DC voltage of another value. The circuitry includes a variable frequency clock controlled by an error voltage derived from the converter output. A pulse of constant length is produced for each cycle of the clock. Logic circuitry is arranged to alternately feed these constant length pulses to opposite sides of a push-pull power amplifier, the output of which is rectified and filtered to form the converter output.

Comparison of multiρle-output DC-DC converters using cross regulation

Abstract: A new multiple-output dc-dc converter is analyzed, in which the cross regulation is performed by the energy-storage reactor as well as the transformer. The steady state and the dynamic characteristics of this converter is compared both theoretically and experimentally with those of the conventional one composed of the step-up-down type circuit. As the results of comparative analysis, it is revealed that this new converter is superior to the conventional one in the steady state and the dynamic performances. Further, it is demonstrated experimentally that the cross regulation performance of this new multiple-output converter is less affected by the leakage flux in the energy-storage reactor, and also that this converter is very useful as a preregulator for the continuous series regulator in cases requiring a high degree of regulation of the multiple-output voltages.

Control method and system for an high voltage direct current system

Abstract: A HVDC system has two converter stations, each of which has two converters connected in cascade to operate as a rectifier or an inverter and the stations are connected through a d.c. power transmission line to each other and are connected to respective a.c. power sources through the a.c. power transmission lines. Each converter is controlled depending on the difference between a current reference for the HVDC system and an actual current flowing in the HVDC system when the converter operates as a rectifier, and controlled depending on the output of the constant margin angle control circuit when the converter operates as an inverter. When the converter operation condition is changed, i.e. another converter operates in addition to the converters in operation or the direction of power transmission in the HVDC system is changed, the current reference for the HVDC system is reduced depending on the d.c. voltage during a predetermined period.

Electrically variable impedance circuit

Abstract: An electrically variable impedance circuit in which a voltage-current converter circuit (3) is provided to produce a current (I') having a megnitude corresponding to an instantaneous input signal potential (v) applied to an input terminal (1) and a current variation of the vottage-current converter circuit is fed back to the input terminal (1), the current variation being controlled by a control signal (Vc) to vary the circuit impedance seen from the Input terminal (1). In order to expand the range of linesrity in impedance, the voltage-current converter is so arranged that the varying component of its output current is linsariy proportional to the inatan- taneous input signal potendial (v). and a current converter circuit (4) is provided which linearly converts the output current of the voltage-current converter circuit and whose output is coupled to the input terminal (1). The current converter circuit (4) is comprised of a PN junction (51) which develops a voltage which is the logarithm of the output current of the voltage-current converter (3) and a transistor (81) between the base and emitter of which is spplied the voltage developed by the PN junction (5 1 ) to produce a current which is the exponential of the voltage developed by the PN junction. (Fig. 1)

On the precise regulation of multiple outputs in a DC-DC converter with an energy-storage reactor

Abstract: In order to regulate multiple output voltages in a dc-dc converter, the crossregulation technique is usually used. However, due to the leakage inductances of transformer and the resistance components of the circuit, there appear the regulation errors in the cross-regulated outputs. This paper presents a new method to compensate the cross-regulation errors and regulate all of the multiple output voltages precisely. This precise regulation is performed by making use of an auxiliary switch in each output circuit, and therefore the additional power loss is not wasted in principle. Further, from the analysis of this new converter circuit, two different operation modes are clarified.

High voltage insulation testing system

Abstract: The high voltage testing system contains a series resonant circuit connected to a voltage source with a continuously variable frequency, whereby the insulation, connected in series with the inductor, which is being tested, either exclusively or at least partly, forms a part of the capacitance. The inductance may consist of several high voltage inductors constructed of modular elements. It is advantageous to use bar-core chokes. Preferably, the bar-core choke is suspended in the mass center by means of a mounting plate. Suitably, the coil of the inductor consists of two windings, each having a trapezoidal cross section. A static frequency converter would be suitable as a voltage source with variable frequency; the converter could be a direct converter built to act as an oscillating circuit converter, operating within the resonance frequency and with pulse-width control. At least one high-voltage capacitor may be connected in parallel to the insulation for the adjustment of the desired frequency. The advantage of this testing system for the testing of an insulation lies in the fact that this system permits testing with frequencies which are lower or higher than the line frequency. The testing system is small and very light-weight and contains elements which are more economical than was heretofore known.

Frequency converter and its controlling method

Abstract: PURPOSE: To enhance the power factor of a power supply by regenerative control employing a voltage-type pulse-width modulation converting means as a converter on the power-supply side with converts AC voltages to DC and as an inverter on the motor side which supplies variable-voltage variable-frequency voltage to a motor. CONSTITUTION: A DC input current of an inverter 2 flows from a converter 5 to an inverter 2 in the case of a reverse-conversion operation, and from the inverter 2 to the converter 5 in the case of forward-conversion operation. In both cases, the voltage of a capacitor 15 is controlled at a constant value, and the DC output current from the converter 5 is always balanced with the DC input current of the inverter 2. That is, the operation of the inverter 2 and that of the converter 5 are opposite each other. Since both the converter and the inverter are sonstituted by a PWM converting means, the motor current forms a sinusoidal wave, torque ripples are not generated, and the harmonic waves of the power supply are not generated either. COPYRIGHT: (C)1980,JPO&Japio

Instrument for use with an electrochemical cell

Abstract: An improved instrument for use with an electrochemical cell that provides a system having enhanced stability and increased bandwidth. The instrument includes a voltage to current converter which drives the cell. The current output of the voltage to current converter is linearly proportional to the differential voltage input. The voltage to current converter drives the cell in both the potentiostatic mode and in the galvanostatic mode of operation.

Combined current and voltage converter for a compressed-gas insulated metal-enclosed high voltage installation

Abstract: The invention relates to a combined current and voltage converter for metal-enclosed high-voltage installations with compressed-gas filling. In order to be able to avoid any passages for the connecting leads through the housing (1, 2), the electrode of the capacitive voltage converter part consists of an intermediate element (3) inserted into the housing in an insulated and gas pressure-tight manner. The intermediate element (3) has on its outside a layer of insulating material (9) and on top of this a metal layer (10). The whole (3, 9, 10) forms a support body for current converter cores (11) surrounded by secondary windings. The low-voltage capacity between the intermediate element (3) and the metal layer (10) is fed to an electronic measuring amplifier (14) via a screened measuring cable (12/12a). The current converter cores (11) are protected mechanically by a sheath tube (16), the latter simultaneously conducting housing currents. FIG. 1.

A high repetition rate power pulse generator

Abstract: Disclosed is a class of power converters which extract electric energy from a source of A.C. or D.C. power and transform this energy to a desired and closely controlled voltage level for use by a pulse demanding load such as a pulsed radar or laser system. The converter eliminates the need for a D.C. link anywhere in the converter system and the need for low frequency power filters. The invention includes a transformerless circuit with galvanic isolation between system input and output terminals and controlled voltage scaling.

High-efficiency single-ended inverter circuit

Abstract: A simple single-ended inverter circuit efficiently converts a DC input voltage to an AC output voltage. The circuit, which functions as a self-contained Class C oscillator, comprises an energy-storing inductor and an energy-storing tank capacitor in circuit with a saturable core feedback transformer operable to provide intermittent feedback current to effect periodic conduction of a single power transistor. When this transistor is non-conductive, resonant interchange of energy occurs between the inductor and tank capacitor; periodic energy transfer from the inductor both charges the capacitor and also supplies a load, and energy transfer from the capacitor to the inductor provides reset current to the saturable transformer.

DC/DC Stabilized voltage converter unit

Abstract: In a DC/DC stabilized voltage converting unit having a series circuit including an input filter, a converter stage having a control input and an output filter, the improvement comprising: a control stage having an output connected to the control input; a voltage regulating circuit receptive of an output of the output filter and having an output applied to the control stage; an anti-overvoltage and anti-overcurrent stage receptive of an output of the converter stage and having an output applied to the control stage; a voltage converter chain coupling circuit for effecting the linking of units in a chain; an internal monitoring and commutating circuit connected between the voltage regulating circuit and the control stage for surveying the outputs of the converter stage; a visually and electrically signalling alarm circuit receptive of the outputs of the output filter and having the outputs thereof applied to the chain coupling circuit; and wherein the chain coupling circuit includes a first input for linking to one pole of a power supply source, a coupling terminal connectable to said one pole of the power supply source, a third input for connecting to the coupling terminal of the next chain coupling circuit in the chain, first and second outputs connected to the input filter and a third output connected to the control stage.

Process of pulse duration modulation of a multi-phase converter

Abstract: A process of pulse duration modulation for improved voltage and frequency efficiency of a multi-phase converter. The sum of the time dependent voltage of a load phase and of an auxiliary time dependent voltage is formed, wherein the auxiliary time dependent voltage is the same for all converter phases. The pulse duration of the output voltage of each converter phase is modulated with said voltage sum.

Modeling and analysis of switching dc-to-dc converter in constant-frequency current-programmed mode

Abstract: An analysis of dc-to-dc switching converters in constant-frequency current-programmed continous conduction mode is performed, and leads to two significant resuslts. The first is that a ramp function, used to eliminate a potential instability, can be chosen uniquely to assure both stability and the fastest possible transient response of the programmed current. The second is the development of an extension of the state-space averaging technique by means of which both the input and output small-signal properties of any such converter may be accurately represented by a linear small-signal equivalent-circuit model. The model is presented and experimentally verified for the cuk converter and for the conventional buck, boost, and buck-boost converters. All models exhibit basically a one-pole control-to-output transfer fuction response.

Practical design considerations of a multi-output CUK converter

Abstract: An experimental high frequency three output dc-dc converter design is presented in circuit detail, emphasizing the practical design needs of its contemporaty optimum topology ('CUK) output stages. Power component selection criteria are also given along with suitable load protection methods against output voltage reversals at turn-on. Inductor coupling criteria for ripple current reductions at input/output ports are develop including an alternate method for external tuning inductance insertion. Results of corresponding empirical evaluations of a 200KHz, 55-W representative design are discussed.

Recirculating RMS AC conversion method and apparatus

Abstract: RECIRCULATING RMS AC CONVERSION METHOD AND APPARATUS Abstract of the Disclosure A signal whose RMS value is to be accurately determined is first converted into DC form by a relatively inaccurate RMS converter, such as a thermal RMS converter. The result is a first converter signal (Y1), which is stored for recirculation in a suitable storage device, such as a sample and hold circuit. The first converter signal is also doubled (2Y1) and stored. Thereafter the first converter signal stored in the storage device is recirculated to the converter to create a second converter signal (Y2). Then, the second converter signal is subtracted from the doubled first converter signal (2Y1 - Y2) to produce a highly accurate RMS output signal.

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

Abstract: Small signal low frequency linear average model is derived for a multi-loop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multi-loop 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 quidelines are formulated to optimize regulator-loop dependent characteristics.

Digital sample and hold circuit

Abstract: A sample and hold circuit for an automotive speed control system is disclosed which includes a non-monotonic digital-to-analog converter suitable for fabrication as a highly dense monolithic circuit. The non-monotonic digital-to-analog converter precludes the occurrence of large positive errors in the analog output value, which might be caused by tolerance errors in the ratio of binary-weighted currents within the digital-to-analog converter, by including offsetting negative errors within the design of the digital-to-analog converter.