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Showing papers on "Forward converter published in 1969"


Patent
Roland E. Andrews1
24 Jul 1969
TL;DR: In this article, an LC resonant circuit is alternately connected from DC input terminals to a winding on an output transformer via a pair of alternately operating switching transistors which turn on in synchronism with the resonant frequency of the LC circuit.
Abstract: An LC resonant circuit is alternately connected from DC input terminals to a winding on an output transformer via a pair of alternately operating switching transistors which turn on in synchronism with the resonant frequency of the LC circuit. Switching is accomplished when current flow through each transistor is substantially zero. The transistors are kept off for a selected period of time during each cycle of the LC circuit waveform, dependent upon a DC output voltage derived via rectification means from another winding on the output transformer. The frequency of operation of the circuit is responsive to the DC output voltage level for regulating the same.

65 citations


Patent
06 Jun 1969

18 citations


Patent
21 Apr 1969

17 citations


Patent
27 Aug 1969
TL;DR: In this article, a first controllable converter is connected to an electrical power supply source, and a second converter is attached to a three-phase electric motor having stator windings impressed by preenergizing current.
Abstract: A first controllable converter is connected to an electrical power supply source. A second controllable converter is connected to a three-phase electric motor having stator windings impressed by preenergizing current. At least one smoothing choke for controlling the speed of the motor is connected at one end to the first converter and at the other end to the second converter. A control circuit causes the voltage at the one end of the choke to follow the voltage at the other end of the choke.

17 citations


Patent
01 Jul 1969
TL;DR: In this paper, a feedback regulated DC/DC converter is disclosed, where an unregulated master oscillator feeds square waves into one core of a dual-core transformer, and a slave oscillator (whose output amplitude is a predetermined fraction of the master oscillators output amplitude) also feeds squares waves into the other core of the transformer.
Abstract: A feedback regulated DC/DC converter is disclosed. More particularly, an unregulated master oscillator feeds square waves into one core of a dual-core transformer, and a slave oscillator (whose output amplitude is a predetermined fraction of the master oscillator''s output amplitude) also feeds square waves into the other core of the transformer. A sample of the transformer output after it has been rectified and filtered is compared against a reference value and the difference between the output value and the reference value produces an error current which is fed into a delay circuit. The delay circuit will then synchronously adjust the output phase of the slave oscillator. Thus, the average voltage appearing across the secondary of the dual-core transformer is varied by adjusting the relative phase between the master and the slave oscillator. Since the slave oscillator operates at only a small percent of the master oscillator''s output, step-width modulation, rather than the standard pulse width modulation, results.

14 citations


Patent
14 Oct 1969
TL;DR: In this paper, a DC converter for transforming a DC voltage to an AC voltage of high frequency and including one or several switching means to effect this operation is described. But the authors focus on the use of premagnetization means for magnetizing the transformer core to increase the efficiency of the converter.
Abstract: The invention relates to a DC converter for transforming a DC voltage to an AC voltage of high frequency and including one or several switching means to effect this operation. The invention is specifically related to the use of premagnetization means for magnetizing the transformer core in order to increase the efficiency of the converter. This is effected by premagnetizing the core into saturation with a magnetic field which is opposite to the field generated by the current through the corresponding switching means. The transformer core will consequently operate in its saturated state from the point when the switching means is rendered conductive and the current through said switching means is increasing up to a certain value above which the core will operate in its nonsaturated state. This arrangement will provide a converter operating with substantially rectangular waveforms of the current supplied to the load, which means that the switching means can operate just below their maximum permissible current when energy is transferred from the current source to the load. The switching means will thus be utilized at a maximum thereby improving the efficiency of the converter.

13 citations


Patent
31 Dec 1969
TL;DR: In this paper, the duty cycle of the switching transistor in a DC to DC converter is controlled by an astable multivibrator whose alternate switching states are respectively responsive to the line and load voltages.
Abstract: The duty cycle of the switching transistor in a DC to DC converter is controlled by an astable multivibrator whose alternate switching states are respectively responsive to the line and load voltages. Feedback of the output voltage to control the duration of one state of the multivibrator is obtained from the primary of the converter output transformer whose magnetic energy level is not allowed to fully dissipate in any one operating cycle. A balancing circuit arrangement is utilized to minimize variations in the base drive signal of the switching transistor and to prevent it from saturating to eliminate variations in the duration of the conducting state of the transistor due to charge storage.

13 citations


Patent
20 May 1969

8 citations


Patent
24 Jan 1969
TL;DR: In this paper, an analog to digital converter is described having a differential analog input and a plurality of parallel digital outputs which includes a multiplicity of comparator circuits, each including a pair of emitter coupled transistors.
Abstract: An analog to digital converter is described having a differential analog input and a plurality of parallel digital outputs which includes a plurality of comparator circuits, each including a pair of emitter coupled transistors having a pair of inputs and a pair of outputs The inputs formed by the bases of one transistor in each of the comparator circuits are connected in sequence through a voltage divider to one input terminal of the converter and the outputs at the collectors of such one transistors are connected by internal logic in common with the outputs at the collectors of the other transistors in the next preceding comparator circuit so that only when both transistors are nonconducting is an output pulse transmitted to an output terminal of the converter The converter may have 10 parallel outputs and be used to provide a decimal readout for a 10position rotary switch by applying a stairstep voltage whose steps correspond to the positions of such switch, as the analog input signal of the converter

7 citations


Patent
24 Dec 1969
TL;DR: In this article, a bypass control system for highvoltage DC power transmission, DC interconnecting frequency changer and so forth is presented, where the semiconductor controlled rectifiers constituting two arms in series of the converter can be fired simultaneously if necessary, thereby eliminating bypass valves required for removing the conventional converter.
Abstract: A bypass control system wherein the rectifiers or inverters in high-voltage DC power transmission, DC interconnecting frequency changer and so forth are constituted by semiconductor controlled rectifiers, and the design is made such that the semiconductor controlled rectifiers constituting two arms in series of the converter can be fired simultaneously if necessary, thereby eliminating bypass valves required for removing the conventional converter. The removal of the converter can be achieved in a short time in case that one arm has brought about commutation failure and the other arm connected in series therewith is fired.

6 citations


Patent
14 Apr 1969
TL;DR: A DC to DC converter for producing a constant voltage DC output signal which includes an unbalanced square-loop magnetic core inverter, a single silicon controlled rectifier for initiating a single complete cycle of said inverter upon the receipt of an input pulse signal, and a constant frequency pulse oscillator coupled to a control input of the silicon controlled output signal, which is subsequently half-wave rectified and filtered, each cycle of which having a constant average voltage amplitude as discussed by the authors.
Abstract: A DC to DC converter for producing a constant voltage DC output signal which includes an unbalanced square-loop magnetic core inverter, a single silicon controlled rectifier for initiating a single complete cycle of said inverter upon the receipt of an input pulse signal, and a constant frequency pulse oscillator coupled to a control input of the silicon controlled output signal, which is subsequently half-wave rectified and filtered, each cycle of which having a constant average voltage amplitude The frequency of the pulse oscillator is lower than the freerunning frequency of the inverter, thereby producing an output pulse train having a constant average amplitude regardless of input voltage

Patent
12 May 1969
TL;DR: In this article, a static DC to DC converter with an output converter stage comprising a full-wave bridge with an SCR in each of two adjacent legs of the bridge is controlled by a variable phase synchronous pulse generator.
Abstract: A static DC to DC converter having an output converter stage comprising a full-wave bridge with an SCR in each of two adjacent legs of the bridge. The firing times of the SCR''s are controlled by a variable phase synchronous pulse generator controlled by an operational amplifier having one input connected to a reference voltage source and another input connected to feedback means across the converter''s output so that the converter''s output voltage is regulated. Means are provided for delaying, during start-up, the application of voltage to the pulse generator to prevent heavy current surges through the SCR''s. An overshoot voltage clipper is connected across the output of the operational amplifier.

Patent
27 Oct 1969
TL;DR: In this article, a transmitter controls the flow of DC load current through two wires in accordance with the magnitude of a DC voltage representative of a variable condition, where a thermocouple is employed, where the variable condition is temperature, and to be freely grounded without adversely affecting output or load current.
Abstract: A transmitter controls the flow of DC load current through two wires in accordance with the magnitude of a DC voltage representative of a variable condition. Transformer coupling is used to isolate the load side from the sensing side. This permits a thermocouple to be employed, where the variable condition is temperature, and to be freely grounded without adversely affecting the output or load current. Special DC/AC and AC/DC circuitry is included.

Patent
04 Aug 1969
TL;DR: In this paper, a static converter with a delay angle control device, a control amplifier for controlling the delay angle, and an arrangement for blocking the converter is presented. But the converter does not have the ability to control the output of the blocking device over a switch delaying circuit.
Abstract: In a static converter which includes a delay angle control device, a control amplifier for controlling the delay angle control device, and an arrangement for blocking the converter. In order to provide for rapid starting of the converter a limiting member for limiting the delay angle of the converter so as to limit the direct voltage of the converter is controlled by the output signal of the blocking device over a switch delaying circuit. A transient order device is also connected to the input side of the control amplifier to increase the input signal of the amplifier and the transient order device is actuated by the blocking means for the DC transmission line connected to the converter. An under-voltage sensitive device actuated by the voltage in an AC network connected to the converter is connected in parallel to the blocking device, and the two parallel devices are connected to the limiting member and the transient order device by an OR gate.

Patent
22 Aug 1969
TL;DR: In this article, an electrical detector that can detect holidays or defects in insulating coatings or mastic coatings generally applied to pipelines has been proposed to detect defects in pipelines.
Abstract: An electrical detector operable to detect holidays or defects in insulating coatings or mastic coatings generally applied to pipelines has a portable DC power supply, a DC to DC converter, an energy storing means operable to store energy from the DC converter, and SCR interconnected with the energy storing means, an oscillator means for gating the SCR on to discharge the energy storing means through a double primary pulse transformer to produce a high voltage, fast time pulse on an exploring electrode, and an alarm circuit capable of audibly and/or visually indicating that a high voltage has arced through the pipeline coating at a holiday point.

Patent
20 Jun 1969
TL;DR: In this paper, a power converter system utilizing a control converter operated during both the positive and negative current half cycles of the output voltage to initiate firing pulses for a power converter which can be operated in either a noncirculating current mode or a circulating current mode is described.
Abstract: A converter system utilizing a control converter operated during both the positive and negative current half cycles of the output voltage to initiate firing pulses for a power converter which can be operated in either a noncirculating current mode or a circulating current mode.


Patent
22 Aug 1969
TL;DR: In this article, a self-oscillating voltage converter including a pair of complementary transistors connected in single-ended push-pull configuration without the use of a transformer is presented.
Abstract: A self-oscillating voltage converter including a pair of complementary transistors connected in single-ended push-pull configuration without the use of a transformer. The first transistor is shunted by a piezo-electric two-terminal device in series with a relatively large capacitor, across which an output alternating voltage at the resonant frequency of the device is produced and fed back to both transistors through an R-C network.

Patent
22 Jan 1969
TL;DR: In this paper, an improved high-speed AC to DC converters has been presented, which has a response time superior to that of existing AC-to-DC converters.
Abstract: AN IMPROVED HIGH-SPEED AC TO DC CONVERTER IS DISCLOSED WHICH HAS A RESPONSE TIME SUPERIOR TO THAT OF EXISTING CONVERTERS. THAT IS, THE DC OUTPUT OF THE CONVERTER REACHES ITS STEADY STATE VALUE IN A SHORTER TIME PERIOD THAN IS POSSIBLE WITH EXISTING AC TO DC CONVERTERS. THE IMPROVEMENT IN RESPONSE TIME IS ACHIEVED BY A UNIQUE CIRCUIT ARRANGEMENT INCLUDING A PLURALITY OF OPERATIONAL AMPLIFIERS. BY MEANS OF THE UNIQUE ARRANGEMENT, A COMPARATIVELY LARGE VOLTAGE PROPORTIONAL TO THE INPUT VOLTAGE IS ADDED TO THE DC OUTPUT INITIALLY AND UNTIL THE DC OUTPUT REACHES ITS STEADY STATE VALUE. THE LARGE VOLTAGE ALLOWS A CAPACITOR IN FILTER CIRCUIT TO CHARGE MORE RAPIDLY THEREBY SIGNIFICANTLY DECREASING THE TIME REQUIRED FOR THE DC OUTPUT VOLTAGE TO REACH A STEADY STATE VALUE. FURTHERMORE, THE CONVERTER OF THE PRESENT INVENTION FEATURES INCREASED ACCURACY AND PRECISION.

Patent
11 Sep 1969
TL;DR: In this paper, a method and apparatus for testing an A-to-D converter by applying to the AtoD converter a DC test signal whose amplitude is varied and which is modulated by an AC signal is presented.
Abstract: A method and apparatus for testing an A-to-D converter by applying to the A-to-D converter a DC test signal whose amplitude is varied and which is modulated by an AC signal. The output digital data from the A-to-D converter is applied to a D-to-A converter and then displayed for monitoring the distortions of the A-to-D converter.

Patent
06 Aug 1969
TL;DR: An electrical switching circuit utilizing transistorized components in contact controlled high voltage pulse generation which is applied to a high-ratio transformer through a diode which prevents reverse current is described in this article.
Abstract: An electrical switching circuit utilizing transistorized components in contact controlled high voltage pulse generation which is applied to a high-ratio transformer through a diode which prevents reverse current. A parallel inductance provides for storage of energy pulses is incorporated directly with the transistor amplifier circuit. In addition a capacitor is connected in parallel across the output of the diode and a silicon controlled rectifier may be serially connected between the capacitor and step-up transformer to provide a capacitordischarge or high voltage converter. A half-wave as well as full wave contact controlled DC converter together with trigger pulse delay means and any combination thereof using the inductive energy storage principles are disclosed.

Patent
03 Jun 1969
TL;DR: In this paper, a converter arrangement is provided which can be set to operate both as an inverter and as a rectifier and wherein the converter elements are constituted by thyristors which are liable to damage by sharply rising voltages thereon brought about by overcurrent conditions when the converter is operating as a Rectifier.
Abstract: A converter arrangement is provided which can be set to operate both as an inverter and as a rectifier and wherein the converter elements are constituted by thyristors which are liable to damage by sharply rising voltages thereon brought about by overcurrent conditions when the converter is operating as a rectifier. To protect the converter elements against damage in such event, means are provided for changing over the operating mode of the converter from rectifier to inverter operation and to also cut off the converter operation completely after a predetermined time delay if the overcurrent condition persists.

Patent
01 Dec 1969
TL;DR: In this article, the authors present an approach for regulating direct current power from an UNregulated direct Ccurrent power source to a PILOT OSCILLATOR and at least one STABILIZING UNIT.
Abstract: APPARATUS FOR REGULATING DIRECT CURRENT POWER FROM AN UNREGULATED DIRECT CURRENT POWER SOURCE COMPRISING A CONSTANT FREQUENCY PILOT OSCILLATOR AND AT LEAST ONE STABILIZING UNIT. EACH STABILIZING UNIT INCLUDES SWITCHING MEANS FOR INTERRUPTING THE CURRENT FROM THE DIRECT CURRENT POWER SOURCE DURING A PORTION OF EACH CYCLE WHICH IS CONTROLLED BY THE PILOT OSCILLATOR, AND INCLUDING A RECTIFYING CIRCUIT AND A FILTERING CIRCUIT FOR REFINING THE REGULATED OUTPUT FROM THE SWITCHING MEANS. THE OUTPUT OF THE FILTERING CIRCUIT IS MONITORED BY A COMPARISON DEVICE, WHICH GENERATES A SIGNAL, REPRESENTATIVE OF THE VARIATIONS OF THE OUTPUT VOLTAGE FROM A PREDETERMINED LEVEL AND, WHICH SIGNAL IS COUPLED TO AN ERROR SIGNAL GENERATOR TO PRODUCE AN ERROR SIGNAL. THE ERROR SIGNAL, WHICH IS REPRESENTATIVE OF THE OUTPUT OF THE COMPARISON DEVICE, AND THUS THE OUTPUT FROM THE FILTERING CIRCUIT IS THEN FED FROM THE ERROR SIGNAL GENERATOR TO AN ENAB LING DEVICE. THE ENABLING DEVICE GENERATES A SIGNAL TO CONTROL THE CONDUCTION AND NONCONDUCTION INTERVALS OF THE SWITCHING DEVICE, AS A FUNCTION OF THE VARIATION OF THE OUTPUT VOLTAGE FROM A PREDETERMINED VALUE.