Showing papers on "Forward converter published in 1973"

System oscillations from negative input resistance at power input port of switching-mode regulator, amplifier, DC/DC converter, or DC/DC inverter

Abstract: A switching regulator or a switching-mode amplifier, dc/dc converter, or dc/ac inverter can have a negative dynamic input resistance at the dc power input port. Frequently an LC decoupling filter is inserted in the dc power line between this equipment and the prime dc power source, to keep switching transients off the dc power buss. The negative input resistance of the equipment can exceed the positive output resistance of the LC filter and the power source. Then the system as a whole can oscillate. This oscillation can cause malfunction of the negative-resistance equipnent or of other types of equipment which may also be operated from the prime source. The conditions required for oscillation to take place are defined, and ways are shown to prevent the oscillation. The predicted oscillations have been observed experimentally.

Capacitance-voltage converter

Abstract: A capacitance-voltage converter, in which an unknown capacitance of a measured capacitor is converted to an output dc voltage indicative of the unknown capacitance. The measured capacitor is charged by a reference dc voltage. All the charge of the measured capacitor is transferred to a reference capacitor, after discharging the reference capacitor, by connecting the terminals of the measured capacitor to the input and the output of an impedance converter, which has a high-impedance input and a lowimpedance output. The reference capacitor is connected to the high-impedance input of the impedance converter. The output dc voltage is derived from the output of the impedance converter.

High dc voltage generating circuit

Abstract: A high DC voltage generating circuit is provided with an impedance element connecting a switching element with the primary winding of a fly-back transformer, and a capacitive element is connected to the primary winding of the fly-back transformer to form a resonance circuit therewith, so that the fly-back transformer delivers, as its output, a sinusoidal high voltage which is subjected to a voltage doubler rectification to provide a high DC voltage with improved regulation.

Converter circuit with correction circuitry to maintain signal symmetry in the switching devices

Abstract: A DC to DC converter regulated by pulse width modulation techniques includes correction circuitry to maintain balanced current conduction in the converter switching devices. The correction circuitry monitors the current conduction in each switching device and varies the duty cycle thereof to restore the current balance if a current unbalance therein is detected.

Means for generating reactive power

Abstract: An arrangement for generating reactive power includes first and second line-commutated converters, the AC terminals of which are connected to an alternating voltage network to which a capacitor bank is also connected. Two branchless connections connect the converters in anti-parallel relation on the DC side and constitute an unloaded DC intermediate line, each DC terminal of each converter being connected by a branchless reactor connection to a DC terminal of the other converter.

The application of standardized control and interface circuits to three DC to DC power converters

Abstract: Standardized.control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the seriesswitching buck regulator, and the pulse-modulated paral1el inverter. The two-loop ASDTIC regulation control concept was implemented by using a common Analog Control Signal Processor (ACSP) and a novel Digital Control Signal Processor (DCSP). This resulted in control circuit standardization and superior static and dynamic performance of the three dc to dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

High voltage shutdown protection circuit with bias arrangement to decrease the voltage shutdown point with increasing load

Abstract: A current and voltage regulated DC to DC converter is designed with protection features to permit its operation in parallel with like DC to DC converters. The features are designed to assure shutdown protection against overcurrent and overvoltage conditions and to assure that each converter will contribute a current to the common load. The protection features include a selective high voltage shutdown to shut down only the converter causing an overvoltage and an overcurrent protection circuit to supersede the normal current regulation in response to a fault condition. A reverse current shutdown circuit protects the common load from faults and short circuits internal to the converter circuit. These protection features permit the converters to operate in parallel without shutting down the entire system should an individual converter malfunction.

Bias transformer for dual voltage input off-line converters

Abstract: In a dual voltage input AC to DC converter, the main DC voltage output is generated by a dual mode rectifier circuit, and an auxiliary AC voltage output is generated by a bias transformer circuit connected to the dual mode rectifier circuit. Though the AC to DC converter is capable of operating from dual input line voltages, both the main DC output voltage and the auxiliary AC output voltage remain constant and are independent of which one of the line voltages is input to the circuit.

Current limit circuit with superseding characteristic to activate overcurrent protection circuit

Abstract: A current and voltage regulated DC to DC converter is designed with protection features to permit its operation in parallel with like DC to DC converters. The features are designed to assure shutdown protection against overcurrent and overvoltage conditions and to assure that each converter will contribute a current to the common load. The protection features include a selective high voltage shutdown to shut down only the converter causing an overvoltage and an overcurrent protection circuit to supersede the normal current regulation in response to a fault condition. A reverse current shutdown circuit protects the common load from faults and short circuits internal to the converter circuit. These protection features permit the converters to operate in parallel without shutting down the entire system should an individual converter malfunction.

Converter control system with tapped transformer providing constant no-load secondary voltage

Abstract: A tapped transformer is inserted between an inverter connected to a DC transmission line and an AC system, the transformer being so controlled as to maintain a constant no-load secondary voltage. An inverter is so controlled that if DC current therein is below a rated value thereof, the DC voltage is maintained constant, whereas the extinction angle is maintained constant in the event of the DC current exceeding the rated value. It is further so controlled that in the event that a sudden change in the voltage in the AC system is detected, the extinction angle of the inverter is increased.

Digital-to-analog converter having common-mode isolation and differential output

Abstract: A digital-to-analog converter (DAC) is described that has transformer-coupled isolation for both power and data inputs and provides a true differential output. The DAC provides a 10-bit, 10.23-V unipolar output of either polarity, depending on which of the two output lines is used as the load reference potential. The common-mode potential may be as large as 250 V, and below 120 Hz the common-mode rejection typically exceeds 100 dB. The isolated, balanced circuit eliminates environmental noise problems and permits long cabling lengths without loss of dc accuracy. The DAC is an analog output feature available on the IBM System/7, a small computer designed for data acquisition and real-time automation applications.

Cable converter with phase lock loop techniques

Abstract: A cable television converter is used with a cable system that transmits a pilot signal, which is harmonically related to the desired converter IF signal, along with the video and sound frequency carriers for each TV channel. The converter includes phase locked loop means connected to the converter input for producing an output signal locked to the carrier frequency of the particular selected channel. The converter also includes pilot signal conversion means which produces as an output signal the difference between the IF frequency and the output signal of the phase locked loop means. A mixer combines the output signal from the pilot signal conversion means with the modulated carrier frequency to provide the desired converter IF signal.

Voltage-to-current converter and function generator

Abstract: A voltage-to-current converter serving as a function generator or an essential element thereof and producing various output voltages in accordance with an input signal. It comprises a voltage-to-current converter circuit including at least two transistors, one of these transistors being an output transistor carrying current proportional to the potential difference between two input terminals respectively connected to the emitters of the two transistors, and a current-to-current converter providing at an output terminal a current proportional to the current through the afore-mentioned output transistor. With this voltage-tocurrent converter a function generator of a simple circuit construction may be produced inexpensively. Also, it may be readily made as a semiconductor integrated circuit.

Safety circuit for rapidly switching off oscillators, particularly transistor DC-DC converters, when the output voltages or output current exceed or full below the required values

Abstract: In a dc-dc converter using a transformer coupled oscillator a threshold switch connected to the dc output of the converter provides a control signal when the voltage and current output parameters exceed predetermined ranges A thyristor and a resistor connected in series with the main current path of the thyristor are connected across the dc input to the converter and normally provide a high impedance path for an additional coil magnetically coupled to the transformer The control signal from the threshold switch turns on the thyristor, providing a low impedance path for the coil and thereby interferring with the operation of the oscillator

Dc power converter

Abstract: A DC to DC converter having a transformer with a primary winding, driven by an inverter circuit, and a tapped secondary winding, allowing a circuit to switch the secondary taps in accordance with the magnitude of the input voltage so that the voltage across the active part of the secondary is approximately constant irrespective of the magnitude of the input. An auxiliary secondary winding is used to provide the switching circuit a voltage proportional to the input voltage and silicon controlled rectifiers are used for switching the taps of the tapped secondary winding and for simultaneously rectifying the voltage thereacross.

A Three-Phase Inverter with Reactive Power Control

Abstract: A new type of self-commutated inverter for fixed or moderately variable frequency has been developed. The inverter is characterized by an extremely uncomplicated main circuit. In its basic form the inverter contains two converter circuits: a principal converter circuit and an auxiliary converter circuit. The principal converter circuit transfers power from the input dc side to the output ac side, and the auxiliary converter circuit generates an inductive current to balance the reactive current of a three-phase capacitor on the ac side. This capacitor has the combined function of a phase compensator, a filter capacitor, and is also the source of the commutating voltage. Both converter circuits are of the line commutated type, meaning that at power frequencies normal converter thyristors can be employed. This makes it possible to build high-power inverters without series or parallel connected thyristors. All filter reactors are smoothing reactors placed on the dc side of the converter circuits. Thus the inverter has a very good efficiency even at the higher frequencies. The ability of a converter circuit to generate a negative sequence current when unsymmetrically controlled makes the inverter insensitive to unbalanced loads. The transient behavior of the inverter is similar to that obtained from a conventional self-commutated inverter with an output filter.

Dc signal translator with a variable amplitude oscillator

Abstract: A DC signal translator having an output DC isolated from the input comprises a variable amplitude oscillator generating an oscillating output signal having an amplitude directly related to the magnitude of the DC supply voltage for the oscillator. A DC isolating transformer is associated with the oscillator. A feedback rectifying circuit is coupled between the DC isolating transformer and the input of an amplifier so that the oscillator''s DC supply voltage, and hence, AC amplitude, is continuously adjusted so as to maintain a portion of the rectified DC feedback signal very nearly equal to the input signal. An output rectifying circuit which is matched with the feedback rectifying circuit is coupled to the isolating transformer so as to produce a DC output signal corresponding to the DC input signal while maintaining DC isolation between the input and the output of the DC signal translator.

A Pulse Amplitude to dc Voltage Converter

Abstract: A simple instrument is described which provides a dc voltage corresponding to the amplitude of a pulse train. The instrument permits measurements of input pulse amplitudes with an accuracy of [inverted lazy s] 0.1%.

Efficient dc/dc converter for a solid state fuze

Abstract: A DC/DC converter for transforming a high voltage to a lower voltage level for use in a solid state electrical time fuze. It comprises a constant charging network to charge a capacitor, which when charged, closes a switch in a series resonant circuit until a second switch closes forming a second resonant circuit.

Converter Transients Caused by Switching Type Surges on the DC Line

Abstract: A complete model of a typical H.V.D.C. converter station suitable for fast transient studies is used to irivestigate the effect of the converter termination on switching-type surges coming from the dc-line. The surge transfer to the converter side of the dc-reactor and the surge distribution within the converter plint are also investigated. Finally, a dynamic model is used to calculate the surge transfer stresses during current extinction followirng a switching surge.

High-efficiency converter and battery charger for an RTG power source

Abstract: Spacecraft power systems utilizing radioisotope thermoelectric generators CRTGs) as primary power sources present an uncommon set of require ments and limitations for interfacing dc-to-dc converters. A converter configuration is presented that complements these RTG characteristics. The circuit is a variation of the basic flyback regulator modified to provide input regulation. The converter has two isolated outputs. One output provides power directly to the spacecraft equipment, while the second is used for battery charging. Design problems addressed are noise generation in long cable lengths between the RTG source and the converter, regulation of the converter input to obtain maximum power transfer from the RTG to the equipment, and provision for two converter outputs while maintaining high efficiency with a simple design implementation. The design of a converter and battery charger used on the Viking Lander Capsule* is presented as an illustration.