Showing papers on "Boost converter published in 1986"

FET power converter with reduced switching loss

Abstract: A DC to DC power converter having reduced switching loss for operation at high frequencies. As disclosed, a buck, or forward, converter includes a first FET as the switching device in series with an inductor and a second FET as the flywheel device. At the common node to which the two FET's and the inductor are connected, there is sufficient capacitance that the FET's may be turned off without appreciable voltage change across the FET's. The value of the inductor is chosen, with respect to the input and output voltages and frequencies of operation involved, to insure that the inductor current polarity reverses each cycle, raising the node voltage to the level of the input voltage, substantially eliminating turn-on losses of the first FET. Control circuitry is provided for regulation of the power converter to control the peak-to-peak current in the inductor and to insure that at least a selected minimum value of the inductor current is present for each cycle of operation of the converter. An over-voltage protection circuit for the output of the converter is also provided.

Near-Optimum Dynamic Regulation of DC-DC Converters Using Feed-Forward of Output Current and Input Voltage with Current-Mode Control

Abstract: Near-optimum dynamic regulation of a dc-dc converter is obtained by adding feed-forward of output current and input voltage to a current-mode controller. The results are a) near zero output impedance and audio susceptibility, from dc to nearly the switching frequency, b) much reduced magnitude, duration, and energy content of the output-voltage transient after a transient change of output current or input voltage, and c) smaller size and lower cost for the output filter capacitor. Feed-forward is applicable to both forward and flyback types of converters and to all types of current-mode control. The cost of feed-forward for a forward-type converter is a low-power resistor and a current sensor; a flyback-type converter needs also an analog multiplier-divider integrated circuit (IC). A description is given of the control loop, conditions to achieve extremely good transient response, calculation of the peak deviation of the output voltage for a step load change, practical methods for current feed-forward, and experimental results. The theoretical predictions are in excellent agreement with the experimental results. In the experiments, adding output-current feed-forward reduced the transient deviations of output voltage by factors of 6.7 in magnitude, 50 in duration, and 335 in energy content. The added components were a 1/4-W resistor and a 12-mm ferrite toroid with a 10-turn winding.

Bi-directional buck/boost DC/DC converter

Abstract: A bi-directonal DC/DC converter includes a first power switch coupled to a first input/output of the converter, an energy storage element coupled to the first power switch, a second power switch coupled between the energy storage element and a second input/output of the converter and means for controlling the first and second power switches so that one of the power switches is opened while the other power switch is alternately opened and closed to transfer power from one input/output to the other input/output.

Boost/buck DC/DC converter

Abstract: A bi-directional DC/DC converter includes a first switch coupled to a first input/output of the converter, a first input/output energy storage element coupled to the first input/output of the converter, a second input/output energy storage element coupled to a second input/output of the converter, an intermediate energy storage element coupled between the second input/output and the first switch and a second switch coupled to the intermediate energy storage element and to the first switch. A pulse width modulator operates the first switch between on and off states while the second switch is maintained in an off state to operate the converter as a buck converter, during which time the power is transferrred from the first input/output to the second input/output. A further pulse width modulator operates the second switch between on and off states while the first switch is maintained in the off state to operate the converter as a boost converter, during which time power is transferred from the second input/output to the first input/output.

An AC-to-DC Converter with Improved Input Power Factor and High Power Density

Abstract: A novel single-phase switch-mode rectifier (SMR) structure is proposed and analyzed. The proposed converter structure employs a synchronous front-end rectifier (SFER) stage which provides high-quality input characteristics with small input filtering. Consequently the proposed converter structure exhibits high power density and has low implementation cost.

Automatic transfer switch for a wide range of source voltage

Abstract: An automatic transfer switch is taught which includes as part thereof a voltage sensing device which is interconnected with one of the lines to be monitored and controlled by the automatic transfer switch and neutral. This voltage may vary over a wide range and it is desired to provide a universal transfer switch control for operation over the wide range. The output analog voltage is provided to an analog-to-digital converter which has a maximum number of output bits. In order to keep the resolution of the output digital signal from the analog converter as high as possible, it is necessary to range the input voltage according to a menu of potential ranging values which are stored in the memory of a microprocessor. A programming device is utilized to input the line voltage and the microprocessor determines the maximum value for the ranging constant as a function thereof. The output analog voltage is reduced by this factor then provided to the analog-to-digital converter. The greater the reduction, the lower the sensitivity. However, the microprocessor chooses only that amount of discrete reduction necessary to prevent the expected input line voltage from exceeding the maximum digital output capacity of the A-to-D converter. The output of the A-to-D converter is then supplied to the microprocessor for processing and the amount of reduction is compensated for by multiplying the output signal by the increase of the conversion factor.

High resolution pipelined digital-to-analog converter

Abstract: A high resolution pipelined digital-to-analog converter is disclosed having at least one switching circuit for conveying charge to at least one conversion capacitor upon receipt of a digital signal during the first half of a clock cycle. Additional switching circuits are provided for transferring the charge from the conversion capacitors to a feedback capacitor during the second half of the clock cycle. Also provided is a circuit for discharging an analog output from, and preventing the charging of, the feedback capacitor during the first half of a succeeding clock cycle. In a preferred embodiment, the pipelined digital-to-analog converter comprises a first plurality of electrical circuits having at least one feedback capacitor and a plurality of conversion capacitors adapted for accepting digital and analog inputs, wherein the ratio of the feedback capacitance to each of the conversion capacitances is substantially independent of the resolution of the converter. A second plurality of electrical circuits is also provided which is operable to delay at least one bit of the digital signal to one of the first plurality of electrical circuits. The digital-to-analog converter is operable to allow the number of n-bit digital words converted by the converter to be independent of the resolution of the converter.

Partial shunt switching limiter for a spacecraft solar-panel or like power-source array

Abstract: This regulating system for an array of solar panels or the like consists of a tap connection into the array, and a boost switching regulator connected to the tapped array. The tap connection divides the array into first and second portions, and the switching regulator is connected so that its power-input terminals are across only one of the two portions of the array. The power-output terminals of the switching regulator are connected across the load (i.e., across the entire array), and the sensing or feedback terminals of the regulator receive a signal which acts as a measure of voltage or current at the load. Boost regulators do not dump overvoltage into a dissipative load; hence the invention prevents local heat generation and resulting spacecraft heat-balance problems of conventional dissipative regulators. Furthermore, in the circuit of the present invention, negligible power flows through the regulator at the end of the solar-panel useful life; hence efficiency losses in the boost regulator itself are avoided when power is at its greatest premium.

A Three-Phase Off-Line Switching Power Supply with Unity Power Factor and Low TIF

Abstract: A new three-phase off-line switching AC/DC converter is described, one which draws essentially sinusoidal AC currents from the input line and therefore generates a very low TIF (Telephone Influence Factor) in the three-phase line currents. The converter consists of three two-stage power processors, the first stage of each performing the unity power factor conversion and the second stage providing isolation and combining the power to a single DC output. The converter easily can be reconfigured to operate from either a single-phase or three-phase (wye or delta) input line. In addition to providing the benefits of unity power factor operation (i.e., good power utilization of source volt-ampere capacity, negligible harmonic currents and low TIF), the converter can operate from a wide range of input voltages because it minimizes voltage stresses to which power switches are exposed. The power stages and control circuits used in a 2 KW implementation of the converter are described and modeled. Some measurements demonstrating the operation of the converter are presented.

Current fed regulated voltage supply

Abstract: The invention is a locally isolated regulated power supply providing a regulated dc power output from an ac current source having a large dynamic range. The power supply comprises an ac-to-dc converter for providing a rectified dc output from an ac current input. The converter includes a current transformer in combination with a rectifier. The current transformer has a saturable magnetic core for receiving primary and secondary windings. The current transfomer produces a reduced secondary output voltage that is a function of the ac system current characterized by the decreased coupling between the core and secondary winding as the core approaches saturation during substantial increases in the ac system current. One or more secondary windings and associated circuitry can be provided. In addition, an electronically controlled switch or shunt having as inputs a predetermined reference voltage and the dc output voltage of the rectifier or a signal equivalent thereto is connected across the converter. The switch provides for the continual shunting of the converter whenever the dc output voltage is equal to or greater than the predetermined reference voltage. A voltage support capacitor is connected across the output of the converter for maintaining the output voltage proportional to the selected reference voltage. An isolation diode is used to isolate the voltage support capacitor from the converter during those periods of time when the converter is being shunted by the electronically controlled switch. This prevents the discharge of the capacitor.

Power circuit with high input power factor and a regulated output

Abstract: A single power converter is capable of drawing low distortion current from an AC line and delivering DC or AC power to a load. The single power converter is used to independently control the input current and the output current. The power converter transformer has an output winding which is controlled by pulse-width modulation (PWM) and a frequency controlled boost winding for controlling input current.

Power failure stop circuit for a converter

Abstract: The voltage in a converter 20 is compared with a reference voltage to detect an input power failure, in response to which a motor driven by the converter is automatically decelerated in accordance with a stored signal pattern/speed reduction curve such that the energy regenerated by the motor is equal to its power consumption. The DC bus voltage of the converter is thus maintained substantially constant during the regenerative braking of the motor, and it is promptly halted without resort to any mechanical braking unit.

Buck-boost parallel resonant converter with inductive energy recovery circuit

Abstract: A DC-AC converter circuit for a power supply contains a parallel resonant circuit topology. Accordingly, stray capacitance associated with the converter forms a part of the resonant circuit and assists in setting the resonant frequency thereof. The energy in the stray capacitance which is normally lost is recovered by the resonant circuitry. A coupled inductor is connected in series with a primary winding of an output transformer of the converter. The coupled inductor includes a resonating inductor winding and an energy recovery winding which are tightly wound out of phase with one another. Energy from the resonant inductor winding is coupled to the recovery winding when the switching elements of the converter are switched on and off. Therefore, energy otherwise dissipated in switching operation is conserved by being returned to its source. Further, the switching elements of the converter are connected in series through diodes to the return line. Consequently the converter is capable of operating either in a buck or boost mode and to switch from one mode of operation to the other.

Closed loop x-ray tube current control

Abstract: Between scans, a stand-by control (40) causes a filament current power supply (44) to supply a low level of power to a tube filament (46). When x-rays are to be generated, a non-linear digital to analog converter (50) supplies a filament current control signal which is estimated to provide a selected tube current. A space charge compensation circuit adds an offset to the selected filament signal to compensate for the selected voltage at which the tube is to be operated. A current boost circuit (70) adds an incremental current boost (26) of a magnitude in accordance with a function of the difference between the actual filament temperature and the normal operating temperature in order to bring the filament up to operating temperature more quickly. A feedback loop (90 to 98) adjusts the selected filament current signal in accordance with any difference between the selected tube current and the actual tube current. A damping circuit (110) reduces the rate of change of the error signal such that the filament current changes at a rate commensurate with the heating rate of the filament.

A 150-mW, 8-bit video-frequency A/D converter

Abstract: The authors describe an 8-bit, extremely low-power, flash A/D converter LSI for video-frequency image signal processing. This converter uses a shallow-groove-isolated bipolar VLSI technology. It consumes only 150 mW, which is half the amount of the lowest power consumption so far reported. This low level of power consumption is achieved by the use of a comparator circuit, which is newly designed. This converter can digitize video signals of up to 10 MHz at a conversion rate of 30 MHz. A differential gain (DG) error of 1% and a differential phase (DP) error of less than 0.5/spl deg/ were observed.

Digital power converter input current control circuit

Abstract: A digital power converter input current control circuit is connected between a power converter and a power source. This circuit monitors, and controls if necessary, the current that flows between the power source and the power converter in a manner that protects the power source, the input current control circuit, and the power converter from the catastrophic effects of excessive current flow. The input current control circuit operates similar to an electronic circuit breaker with an automatic reset feature, in that the power delivered to the power converter is maintained low during fault conditions. Thus, if a power transistor in the power converter should fail, a current limit circuit in the input current control circuit will prevent additional damage to the power converter. The operation of the input current control circuit, however, is different than that of a circuit breaker in that a control circuit in the current limit circuit allows for current limiting during start-up, transient conditions which prevents the generation of "gliches" or voltage spikes on energized input power lines when the power converter is suddenly activated.

Regulator circuit for converting alternating input to a constant direct output

Abstract: A high efficiency integrated power converter adapted for direct connection to line voltage and having on chip protection from overcurrent may be implemented utilizing a GTO-SCR as the switch element in a switching power converter such that the converter requires no external transformer or inductor based voltage reducing circuitry. The input voltage may vary over a wide dynamic range without deterioration in circuit performance due to the extremely high anode to cathode breakdown voltage of the switching element and further due to the on chip protection from excess current flow through the switching element.

Three-phase-to-three-phase power converter

Abstract: A 3-phase-to-3-phase power converter is intended to control the output voltage and current so as to provide a 3-phase sinusoidal wave which is controlled in compliance with the input voltage. The main circuit has a switching period shorter than 30° of the power voltage waveform and it is controlled so that switching of lines takes place in alternate fashion, whereby the input power factor is improved.

A protection circuit for a power converter apparatus

Abstract: A circuit for a power converter is disclosed which is made up of at least one fuse connected in series with a semiconductor element, such as a thyristor, and a non-linear resistor con- ected in parallel at least with the fuse. In this way. fuses can be employed in a power converter apparatus of high voltage and current capacity. The unit circuits can be connected in series or in parallel or both to increase the current and/or voltage capacity of the power converter. Trigger fuses can be employed to halt operation of the unit in the event of fusing of one or more of the fuses.

Apparatus for controlling the parallel operation of an A-C output converter for a commercial power source including a circuit for simulating output current for test purposes

Abstract: An apparatus for controlling the parallel operation of a commercial power source and an A-C output converter in which the A-C output converter of a variable voltage and a variable frequency is connected and operated in parallel with the commercial power source; an impedance element is provided between said commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, the impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter, and the voltage and frequency of the A-C output converter being controlled so that a current that flows through said impedance element assumes a predetermined value.

Clocked direct voltage converter

Abstract: A clocked direct voltage converter with potential separation includes a control circuit for controlling the switching times of a switching transistor arranged on the primary side of the voltage converter, in which voltage converter voltage proportional to an output quantity is chopped by a controllable switch. The chopped voltage is transmitted by a transformer to the primary side of the converter, is then rectified, filtered and supplied to the control circuit. In order to obtain the largest possible control range for the converter, a further transformer is provided which transmits oscillation signal of an oscillator of the control circuit to the controllable switch on the secondary side voltage converter. By means of this oscillation signal, the controllable switch is controlled.

Controller for power converter

Abstract: PROBLEM TO BE SOLVED: To provide a power converter that seldom produces trouble in a main circuit, wherein deterioration in a main circuit element, a smoothing capacitor, and a smoothing reactor due to thermal stress is determined from accumulated information on the state of inverter operation. SOLUTION: A device is for controlling the power converter 1 that drives an induction motor by an inverter having a main circuit element. This device includes means 14 for detecting the temperature of the main circuit element of the inverter; means 20 for computing a first coefficient normalized from a switching frequency; means 21 for computing a second coefficient normalized from an output voltage command; means 22 for multiplying the first coefficient, second coefficient, and detected temperature to compute an amount of thermal stress; means 23 for determining the states of gate start and stop of the inverter; means 25 for adding and storing the amounts of thermal stress during the operating time of the inverter; means 26 for accumulating added values to compute an accumulated value; and means 27 that, when the computed accumulated value becomes equal to or higher than a predetermined value, determines that the main circuit element has been deteriorated. COPYRIGHT: (C)2007,JPO&INPIT

Power supply device comprising means for modulating the output thereof

Abstract: There is disclosed a power supply device capable of providing stable AC and DC output voltages. For this purpose an input voltage is chopped by a controlled switching device and supplied to a converter transformer to obtain a high output voltage at the secondary side, and the output voltage is separated in two portions for supply to two loads.

Low dissipation capacitor voltage sharing circuit for a static AC/DC converter

Abstract: In an AC/DC converter, the dissipation voltage sharing resistors commonly placed in parallel with the series capacitors are replaced by a resistor balancing path derived from the capacitor junction point to a symmetrically disposed voltage reference point belonging to the AC input vectorial system.

Transformer-coupled two-inductor buck converter

Abstract: A transformer-coupled two-inductor buck converter is provided which comprises a series input circuit including an input inductor, a capacitor and a grounded inductor. The input and grounded inductors are wound so that a source of d.c. input voltage can be connected across positive polarity outer ends thereof. A transformer is provided for coupled the input and output circuits of the converter. When a switching transistor in the input circuit turns on, input current conducting through the input inductor joins with current being dragged out of the grounded inductor and through the capacitor to conduct through the primary winding of the transformer and couple to the secondary winding for delivery as output current to the load. An output winding coupled to the grounded inductor is connected by a switching diode to the load. When the switching transistor turns off, stored current energy in the input inductor conducts through the capacitor into the grounded inductor and joins with stored current energy in the grounded inductor in commutating to the output winding and conducting through the switching diode for delivery as output current to the load. The input and output currents are continuous with a ripple. The ripple on the input current can be reduced to zero by coupling the input inductor and the grounded inductor together on a common core along with the output winding.

Filter capacitor discharge circuit for a DC-DC converter

Abstract: A power supply circuit includes a battery power source connected by a switch to the input of a DC to DC converter. The output of the DC to DC converter is connected to a filter capacitor and a load. A crow-bar is connected to the input and the output of the DC to DC converter. The crow-bar shorts the output to ground to discharge the capacitor when the voltage at the input drops to a predetermined value.

A Multifunction DC-DC Converter as Versatile Power Conditioner

Abstract: A multifunction dc-dc converter that can be used as a single power conditioner connecting the source, the storage, and the load in solar or wind energy systems is presented Operation of the converter in four configurations is analyzed and simulated Application of the converter is discussed, and experimental results obtained with a prototype circuit are given

Power-factor-corrected AC/DC converter

Abstract: An AC/DC converter comprises a half-bridge electronic self-oscillating inverter powered from the non-filtered full-wave-rectified 120 Volt/60 Hz power line voltage, and its resulting amplitude-modulted 30 kHz output voltage is applied to a series-resonant L-C circuit. The 30 kHz voltage developing across the tank capacitor of this L-C circuit is rectified and applied as DC to an energy-storing capacitor, from which the AC/DC converter's output is supplied. Trigger pulses are provided to trigger the inverter into self-oscillation at the beginning of each pulse of DC voltage provided by the unfiltered rectified power line voltage. As soon as the magnitude of the DC voltage across the energy-storing capacitor exceeds a first level, the trigger pulses cease to be provided. As soon as the magnitude of the DC voltage on the energy-storing capacitor falls below a second level, the trigger pulses are again provided. As long as the inverter is in operation, the current pulled from the power line is essentially of constant magnitude and therefore providing for a power factor of about 90%.

Floating battery feed circuit using multifilar transformer.

Abstract: A substantial reduction in the common-mode noise generated by a switching-mode power converter is achieved by incorporating a multifilar-wound transformer (410) into the converter in such manner that the inter-winding capacitances cause a cancellation of common-mode, noise components at the converter output.