Showing papers on "Forward converter published in 1970"

Improved a-d/d-a converter system

Abstract: A system for transmitting digital representations of analog signals which increases resolution without a corresponding increase in the number of bits in the digital data which is transmitted. In one embodiment, the analog input signal is applied to a level change circuit and summed with a square wave having peak-to-peak voltage equal to one-half the magnitude of the value of the least significant bit of the digital representation. The square wave pattern output of the level change circuit is applied to an analog-to-digital converter and the digital output is transmitted to a digital-to-analog converter. The output of the digital-to-analog converter is filtered to provide the analog output signal. During the time that the square wave pattern crosses an analog-to-digital converter threshold value, the resultant digital-to-analog output is a square wave with an average value between the normal discrete analog output levels. This results in twice as many levels at the analog output which is equivalent to the addition of one bit of resolution.

Brushless dc adjustable speed drive with static regenerative dc motor control

Abstract: For a brushless direct current motor there is provided a static adjustable speed control circuit including an SCR converter for controlling the average voltage applied to the motor windings by phase control of current flowing directly from a multi-phase power source and for commutating the current through the motor winding to maintain the proper current flow direction and torque. The SCR converter is controlled as a function of rotor position, a-c line input conditions, phase advance and SCR converter voltage output. A voltage feedback signal from the converter output is compared to a reference voltage to derive a comparison signal used to adjust the phase advance and thereby control the average voltage applied to the motor terminals. The polarity of the comparison signal determines whether motoring action or regeneration is to occur. Current feedback from the input lines is used to prevent combinations of SCRs from ''''turning on'''' and short circuiting the load.

Self-commutated thyristor DC-to-DC converter

Abstract: This paper describes an analysis of a thyristor dc-to-dc converter employing self-commutating circuitry. Energy is transferred between the input and output terminals by means of resonant networks. Circuit techniques are described which reduce the acoustical noise and minimize the RF voltage spikes at the output terminal.

Body organ stimulator with voltage converter

Abstract: An organ stimulator is provided having a power supply, a pulse generating circuit, a voltage converter and output terminals. The voltage converter includes at least one capacitor which is arranged such that, during the interpulse interval between pulses from the pulse generator, the capacitor charges to approximately the voltage of the power supply and upon application of a pulse to the voltage converter, the combined voltages of the power supply and the charged capacitor are supplied to the output terminals. A novel current limiting circuit is also provided which regulates the output pulse current of the pacer.

Dc voltage conversion apparatus

Abstract: A plurality of DC to DC converter circuits are coupled to respond to pulses occurring at substantially different points in time, each circuit producing a high level DC voltage from a low level DC voltage. The high level DC voltage from each of the converter circuits are coupled to a filter which provides a transient free waveform at an output terminal. The duty cycle provided for each of the converter circuits allows minimal size components to be used while obtaining a high power output.

Regulating converter circuit

Abstract: An improved high-efficiency D.C.-to-D.C. converter circuit uses a single transistor to provide both D.C. level conversion and output regulation. A control winding on a saturable core inductor alters the recycle time of the converter to control the level of magnetic flux in an output transformer per cycle of operation.

Power converter with self-synchronization and bias

Abstract: A power converter having a self-synchronized commutator that causes the power pass transistor in the converter to very rapidly assume its completely turned off state when converter power output is no longer desired. Also provided is apparatus for the converter which supplies base drive to the power pass transistor in response to a triggering pulse. The base drive apparatus has a feed back transistor bias circuit which includes a starting gate that allows the converter to operate during the first several cycles until bias by the bias circuit is provided.

Self-regulated dc to dc converter

Abstract: A regulated power supply using square wave generator the pulse width of which is governed by an impedance controlled by the converter output. The impedance is impressed on the square wave generator through an insulating transformer with two separate secondary windings, one connected to the diode bridge output of an output voltage error detector and the other connected to the diode bridge output of an overcurrent and overvoltage protecting device; in this manner physical isolation is provided between the error detector, as well as the protecting device, and the square wave generator and thus between the output and input of the power supply. The square wave generator output operates on the control input of a separate power inverter which is also used to provide a regulated, but isolated, output for normally powering the square wave generator. Initially the square wave generator is powdered by a preregulator associated with the DC input to the converter. In addition to the conventional output pulses the square wave generator also furnishes quenching pulses to minimize the switching losses in the switching transistors of the power inverter.

Sub-synchronous static converter cascade

Abstract: A sub-synchronous static converter cascade with a slip-ring motor and a static frequency converter connected to the rotor of the motor in which the converter comprises a diode rectifier and a static converter operating as a mains-controlled static converter. A resistor and a voltage-controlled thyristor switch forming a series circuit is connected in parallel with the static converter, and a high-speed circuit breaker bridged by a second resistor is connected between the diode rectifier and the junction of the thyristor switch with the static converter.

Converter arrangement for feeding variable ac motor

Abstract: A regulable and controllable inverter or converter for feeding alternating current motors with a regulated current and frequency in which adjustment of the converter output voltage per phase is effected by the voltage output of a slip ring armatureasynchronous machine driven by the motor, means being provided to rotate the winding axis of the asynchronous machine relative to that of the motor.

A 100-kV thyristor converter for high-voltage dc transmission

Abstract: This paper discusses the design features and test results of a thyristor power converter for high-voltage dc (HVDC) transmission for study of its practicability. It consists of a thyristor valve (which represents one arm of a bridge) with a bridge output of 100-kV dc. This valve features series use of 120 2.5-kV, 500-ampere thyristors and application of optoelectronics technology where luminous diodes and a light-sensitive device are employed for gate firing, overvoltage protection, and measurement of device-distributed voltage. The tests have confirmed the estimated usability of the thyristor for dc transmission, as well as the superiority and reliability of the optoelectronics. It has been found that the valve performs as designed. With thyristor voltage ratings of over 4 kV already developed in Japan, it is expected that the HVDC power converter will be extensively utilized in the very near future.

Random flashing circuit including a voltage step-up converter

Abstract: An electrical circuit for periodically and essentially randomly flashing a plurality of gas discharge tubes, particularly for decorative effect. A plurality of gas discharge tubes are connected with associated resistor and capacitor combinations in a relaxation oscillator configuration. A sufficiently high voltage to operate the parallel relaxation oscillators is derived from a low-voltage source and a DC to DC voltage step-up converter. The converter comprises a transistor oscillator of the Hartly type with the main frequency determining coil and the feedback coil being the primary winding of a step-up transformer. The oscillator is powered by the low-voltage DC source and the stepped-up AC voltage appearing at the secondary of the transformer is rectified and filtered to supply the sufficiently high voltage to operate the plurality of flashing circuits.

Regulated DC-to-DC converter

Abstract: A DC-DC converter includes first and second switches to be opened and closed at mutually exclusive times at a predetermined frequency. The first switch is connected to an inductor and a transformer primary winding so that a first current component from a DC input supply flows through it via the inductor. A second current component having a sinusoid component flows through the first switch in response to discharge of energy stored in a resonant circuit coupled to the transformer. The second component begins approximately simultaneously with closure of the first switch. The second switch, when closed, is connected so that a bidirectional current component flows through it in response to energy stored in the inductor. The rectifier is connected between the secondary winding and the load so the secondary winding supplies substantial current to the load.

Harmonic-insensitive ac-to-dc converter

Abstract: A system for converting a time-varying periodic, complex electrical input wave to DC with reduced response to selected harmonic distortion components of the wave, the system including a conventional AC-DC converter and means for selectively altering the gain of the converter between predetermined phase angles with respect to the fundamental of the wave. Gain alteration is typically effected by a second AC-DC converter having a different characteristic sensitivity to the distortion components than the first converter. The outputs of the two converters are scaled and then summed, the scaling factors being dependent on the harmonics the effect of which is intended to be reduced. One converter is an average-sensing device, the other being a peak-To-peak or peak-averaging sensing device.

Two-way electronic frequency converter

Abstract: A two-way electronic frequency converter is operable in forward or reverse modes without switching.

Pulse train to digital converter

Abstract: A pulse train to digital converter including improved frequency multiplying means whereby the multiplication is virtually unrestricted in magnitude and is a closed loop function for improving accuracy and stability of the converter.

Constant frequency dc to dc converter with oscillation sustaining voltage regulation feedback loop

Abstract: A self-oscillating DC to DC power converter establishes oscillations in the inverter through the voltage regulating feedback circuit. Its frequency of oscillation is regulated by a frequency regulation feedback circuit which controls the hysteresis response of the voltage regulating feedback circuit.

Arrangement in converter stations for ultrahigh voltages

Abstract: In converter stations in DC networks for ultrahigh voltages there is at least one chain of converter bridges. The converter bridges in each chain are series connected on the DC side and connected over transformers to an alternating current network on the AC side. When there are two or more chains all chains are connected in parallel between earth and the transmission line in the DC network. At least some of the apparatus connected to high potential, such as transformers, reactors and the like, have their tanks connected to the DC side of the converter chain at a point where the potential in relation to earth is at least half the voltage in the DC network.

Current or voltage-to-frequency converter using negative feedback

Abstract: A current or voltage-to-frequency converter is provided for converting a DC current or voltage to a proportionate frequency of electrical pulses of predetermined width. The converter includes an integrator coupled to control the frequency of a voltage-controlled oscillator, and negative feedback is provided to the input of the integrator during the occurrence of pulses from the oscillator to provide high linearity and stability.

Linearity error compensation circuit

Abstract: The linearity error compensation circuit for a meter converter includes a monostable multivibrator for receiving an output frequency signal from the meter converter which varies in response to a function being metered. The multivibrator controls a switch which passes either a reference input to a function transformer or a level regulator which are connected between a voltage blocking circuit connected to the multivibrator output and a voltage-frequency converter. The output of the voltagefrequency converter is connected to an arithmetic unit which is also connected to the output of the meter converter.

Bidirectional dc signal detector with transformer isolation

Abstract: A system for detecting a direct current (DC) signal in magnitude and direction, when electrical isolation is required between the DC signal being detected and the stage producing the output signal, employing an oscillator whose mark and space time durations are modulated according to the magnitude and direction of the DC signal being detected and wherein the so-modulated output of the oscillator is symmetrically amplitude limited to provide signals having a DC component corresponding to the DC signals being detected and the DC components are extracted to provide an output indication of the magnitude and direction of the DC signal being detected.

Dc power controller with static switching elements and common current feedback transformer between direct voltage source and load

Abstract: Apparatus to control the application of DC power from a source to a load with static (transistor) switching elements driven by a highly efficient drive circuit. A common current feedback transformer is used to drive the switch from the DC load current. This provides base drive current that is proportional to the DC load current and is insensitive to supply voltage variations.