Showing papers on "Flyback transformer published in 1971"

The Thyristor Electronic Transformer: a Power Converter Using a High-Frequency Link

Abstract: The electronic transformer is a device which behaves in the same manner as a conventional power transformer in that it steps voltage levels up or down while providing isolation and can accommodate load current of any power factor. It contains thyristor power switches which convert the low-frequency (dc to 400-Hz) voltage wave to a high-frequency (in the order of 10 000 Hz) wave. A comparatively small magnetic transformer then provides the voltage level transformation and isolation functions. Similar thyristor power switches then reconstruct the original low-frequency wave at the desired output voltage level. This device can incorporate additional features not found in a conventional transformer, such as current limiting and current interruption. The theory of operation is presented and confirmed by experimental data.

Constant voltage transformer three-phase ferro resonant

Abstract: A constant voltage transformer apparatus having two magnetic cores with an input winding linking both cores and an output winding linked to only one of the cores. A resonant circuit is liked to the core having the output winding which core has a flux therein which is the sum of the flux from the input winding and the flux generated by the resonant circuit winding so that this core may be saturated for a constant output in the output winding while the second core is unsaturated and acts to absorb a rise of the input voltage. The symmetry arrangement of the cores and coils makes it especially useful for a multiphase constant voltage transformer. The transformer has an inherent current limiting characteristic and removal of the resonant circuit renders the transformer to be used as a conventional transformer with the added advantage of current limiting.

Regulating and filtering transformer having a magnetic core constructed to facilitate adjustment of non-magnetic gaps therein

Abstract: A parametric regulating and filtering transformer including a magnetic core having input, output and saturating regions, input and output windings disposed in inductive relation with the input and output regions, and a capacitor connected to the output winding to provide a tank circuit. Different embodiments of the parametric transformer develop a non-magnetic gap or gaps, in the output region of the magnetic core, required to provide the desired waveform and electrical performance of the transformer, while facilitating the manufacture and assembly of the transformer.

A Kilowatt Rotary Power Transformer

Abstract: Many future satellite configurations will require the transfer of signals and power across rotating interfaces. Satellite systems are particularly cost effective for both commercial and military communications applications if their useful lifetime can be demonstrated to be greater than five years. The rotary transformer has the desireable characteristics of high reliability and low noise which qualify it as a potential replacement for slip rings. This paper describes the development of a rotary transformer for typical spacecraft applications. The transformer is built in modular sections, each capable of transferring 500 watts across a gap at efficiencies greater than 88 percent, dc to dc. The design effort included a study of pertinent electrical characteristics required for typical spacecraft configurations, electrical design and analyses of the overall dc-dc converter, mechanical design of the transformer cores and their assembly, and a study of transformer core and winding characteristics. Breadboard test results have demonstrated the desired level of efficiency, satisfactory operation over temperature, and satisfactory electrical characteristics.

Power inverter oscillator circuit

Abstract: A power inverter oscillator circuit including an output transformer with a primary winding, the opposite end of which are connected to the load terminals of a pair of power transistors and to the center-tap of which is connected a source of D.C. voltage. The transformer is provided with a feed-back secondary winding connected to the base terminals of the transistors. The oscillator circuit is provided with output transformer saturation and current overlap prevention means operable at least under load conditions and comprising resonant circuit-forming means coupled to a secondary winding of the transformer and inductance means coupled between the bases of the transistors for producing a sinusoidal-like waveform of voltage in the transformer windings, effecting the alternate switching of said transistors into conduction without the saturation of said output transformer, and effecting the complete cessation of flow of current through one of the transistors before current begins to flow in the other switch device.

Dc to dc converter with voltage regulation through pulse width modulation by control of the distribution of flux variations in a dual core transformer

Abstract: A DC to DC converter regulates its voltage output by controlling the distribution of flux variations in a dual core transformer included in the converter''s inverter circuit. The inverter output is coupled to a rectifier and the output load, via one core of the transformer. A voltage regulation control circuit includes the other core of the transformer and pulse width modulates the inverter output by controlling the flux variations in the two cores of the transformer. The second core included in the voltage regulation control circuit advantageously permits complete isolation between the input and output circuits of the converter.

Cathode ray tube dual mode horizontal deflection control amplifier

Abstract: A dual mode cathode ray tube horizontal deflection amplifier normally operable in a linear mode for horizontal forward scanning and/or symbol writing during the vertical re-trace period and controllably switchable to a non-linear resonant flyback mode for horizontal re-trace The amplifier comprises a differential input stage cascaded with a push-pull output stage which couples to both the horizontal defection coil of the cathode ray tube and a parallel connected capacitor, forming a resonant circuit The differential input stage compares the input deflection signal with a feedback signal proportional to the beam deflection to assure linear control Switch-over to the resonant flyback mode is accomplished by actuating the push-pull stage so as to present a high impedance to the resonant circuit whereupon a half-cycle of oscillation commences to produce the horizontal retrace

Self-tuned vibratory feeder

Abstract: A driver for a vibratory feeder employs a D.C. field structure with an annular air gap in which is disposed concentrically both a stationary coil and a moving coil. The latter coil is mechanically coupled to drive the flexure supported tray. Both coils are connected in series opposition and have substantially zero resultant inductance. The coils, in series, are connected to both the output and input of an amplifier having a single-ended output to provide a self-excited oscillatory loop. A servo amplifier responding to the flyback voltage generated by the moving coil controls the gain of the main amplifier so as to provide for automatic velocity control. An A.C. shunt is selectably applicable to the main amplifier to suppress oscillation while the amplifier is maintained conductive for dynamic braking when a stop command is executed. The oscillatory wave shape is controlled to avoid high frequency components which give rise to acoustic noise.

Cycle converter power supply for microwave heating

Abstract: A cycle converter power supply circuit comprising four silicon controlled rectifiers (SCR''s), electronic semiconductor switches, used to program current flow through four separate legs of a transformer in a manner to produce an alternating current at a frequency considerably in excess of the prime power. A bridge rectifier circuit in the secondary of the transformer permits the power to be converted to a direct current flow similar in character to what would be achieved through rectification of the prime power. Since the voltage conversion is accomplished at a higher frequency than the prime power, the core area of the transformer can be reduced roughly by the square root of the switching frequency.

Surge generator for transformer testing

Abstract: Apparatus and method for testing short-circuited power transformers A capacitor, which has been charged to a predetermined voltage, is connected in parallel with an inductor When the voltage of the discharging capacitor goes through zero, the shorted transformer being tested is connected across the inductor A matching transformer may be used between the transformer being tested and the inductor for adjusting the surge generator voltage and impedance to match that of the shortcircuited power transformer

Upright type bushing current transformer

Abstract: A bushing current transformer is provided and includes an auxiliary current transformer mounted on the top of a bushing. The primary and secondary coils of the auxiliary current transformer are connected parallel to each other and in series to an electrical power line having a high voltage and carrying a high current therethrough. A conductive lead is connected to the secondary coil of the auxiliary current transformer and is conducted to the bottom of the bushing to thereby form a primary coil of a main current transformer which is positioned on the bottom of the bushing and then conducted upwards again through the bushing. With such an arrangement the size of the line conductor being introduced into the bottom of the bushing can be made smaller, since the current transformation ratio between the primary and secondary coils of the auxiliary current transformer can be adjusted. Also, the current transformer can be standardized and thereby adapted for mass production due to the ability to fix the secondary current of the auxiliary current transformer at a constant amplitude.

Direct current to direct current chopper inverter

Abstract: Circuitry for converting direct current at one voltage level to direct current at another voltage level by the use of alternately fired transistor switches or the like feeding into a transformer, and incorporating flyback transformer means to prevent large current spikes and dissipated energy when the ON times of the transistors overlap, when the transistor switches are driven with pulses of unequal widths, or when the transformer primary turns on either side of a center tap are unequal. The basic concept of the invention is to connect a winding of an inductive energy storing flyback transformer in series with one or more chopper switches so that when the switch or switches are closed, the switch current is limited by the presence of the energy storing flyback transformer. When the switches are open, the stored energy of the flyback transformer is allowed to transfer current to a load through a diode.

An Electronic Self-Balancing Instrument Transformer Testing Device

Abstract: A self-balancing instrument transformer testing device is described by which the voltage and current errors and phase displacements of instrument transformers can be read off or recorded directly with a printer or digital instrument. The circuitry correr sponds to the usual difference circuit in which the test transforme- is compared with a standard transformer. The voltage difference between the secondary voltages of the test and the standard transformer is balanced by a voltage that is separated into two components, one being in phase with the voltage of the standard transformer (reference voltage) and the other in quadrature. The direct voltages with which the reference voltages are multiplied to generate the balancing voltage are a measure of the errors and the phase displacements of the instrument transformers. The circuits generating the reference voltages, the zero voltage amplifier, the phase-selective rectifier, and the multiplier circuit are described. The device is designed for measuring the errors of current transformers between 1 and 200 percent of rated current and the errors of voltage transformers between 40 and 120 percent of the rated voltage, to an accuracy of about 1 percent of full scale. It may also be used to measure the impedance of resistors, inductors, and capacitors.

Inverter oscillator with voltage feedback

Abstract: An oscillator is disclosed for use in an inverter for a wide range of load using two transistors connected in a push-pull amplifier configuration having current feedback through primary windings of a saturable transformer connected in series with an output transformer between collectors of the transistors. Voltage feedback is provided through a third primary winding of the saturable transformer connected in series with a resistor between the collector of one transistor and a center tap in the primary winding of the output transformer.

High voltage accelerator power supply

Abstract: A high voltage accelerator power supply for providing a substantial current flow at a high D.C. voltage level including a step-up transformer mounted on an upright insulating frame at an intermediate level approximately midway between bottom and top of the power supply with the transformer being horizontally positioned and corona rings encircling the upper and lower edges of its core. One capacitor is below the level of the transformer core and another is above that level in a voltage-doubling arrangement while the core is electrically connected to a junction intermediate the two capacitors to be at an intermediate voltage level. A modular, flexible snake-like electrical device containing a plurality of series-connected rectifier cartridges positioned end-to-end, or similar components, enclosed within a plastic sheath enables connection with substantially uniform voltage stress distribution between a low voltage and a high voltage terminal by conveniently arranging the device in a helical or snake-like path. An isolation transformer system includes first and second widely separated cores one at ground potential and the other at the high D.C. output voltage of the supply, with an endless loop coupling winding at intermediate D.C. level and encased in a heavy insulation covering wound a few turns on each core.

Voltage control sawtooth oscillator with flyback time independent of frequency

Abstract: This invention involves an electrically frequency-variable oscillator of the type which can be adjusted to vary the characteristics of both the sawtooth wave and rectangular wave generated.

Circuit for determining the state of a dc isolated switch

Abstract: A switch and a device for monitoring the open or closed state of the switch are conneted by a DC isolation circuit including an isolating transformer, a capacitor in the transformer primary circuit with the switch connected across the capacitor, and, in the transformer secondary circuit, an alternating pulse signal source to charge the capacitor through the transformer. In this circuit, the impedance reflected into the transformer secondary winding varies in accordance with the open or closed state of the switch. To permit the state of the switch to be accurately determined, the circuit disconnects the alternating signal pulse source from the transformer secondary while applying a read signal pulse to the transformer secondary to determine the reflected impedance, thereby eliminating errors arising from superposition of the read signal on the alternating signal without necessitating synchronization of the two pulse signals.

Deflection driver control circuit for a television receiver

Abstract: A monolithic integrated vertical deflection coil driver circuit for a television receiver is disclosed. To permit driving of a vertical deflection coil directly from output transistors located on the monolithic integrated circuit chip, a flyback control circuit using an energy storage capacitor is employed to obtain a voltage pulse in excess of the voltage of the power supply and having sufficient energy to provide proper vertical deflection flyback. The voltage necessary to initiate flyback is low enough to be compatible with monolithic integrated circuit technology.

Phantom burden arrangement for current transformer calibration

Abstract: The power and reactive volt-amperes normally dissipated to furnish a burden are returned to the power supply either through a current comparator or an auxiliary current transformer. This effect is achieved by the use of an amplifier connected to generate a voltage that is an adjustable complex function of the secondary current of the calibration circuit, such voltage being applied across the secondary of the transformer undergoing calibration in order to furnish an effective burden therefor.

High voltage hold down circuit for horizontal deflection circuit

Abstract: In a horizontal deflection circuit including a voltage supply for developing the kinescope high voltage, a switching diode is coupled from a capacitor in series with the flyback transformer to a control element of a voltage controlled horizontal oscillator to disable the oscillator or change its frequency to prevent the high voltage from increasing to an excessive level in the event the damper diode becomes open circuited.

Horizontal convergence circuit

Abstract: A horizontal convergence circuit for a color television receiver having at least first and second coils for magnetically converging a plurality of electron beams in a cathode-ray tube. The convergence circuit has a transformer which is coupled intermediate the two coils. This convergence transformer is coupled to the flyback transformer and is energized therefrom at the horizontal deflection rate. The two convergence coils are coupled in series with the secondary of the convergence transformer and have their polarities arranged in such a way so that the transformer produces series adding voltages across the coils. The convergence transformer has a movable core which allows the transformer to be adjusted to control the spacing between vertical test lines on the screen of the cathode-ray tube. A resistor is connected in parallel with the convergence coils and a variable tap on the resistor is coupled directly to a center tap on the secondary of the convergence transformer. This arrangement provides a differential amplitude control for the parabolic current in the coils. Further parallel connected resistors provide a differential tilt control and a master tilt control for the coils. The differential tilt control regulates the proportion of sawtooth current delivered to each coil, while the master tilt control regulates the amount of sawtooth delivered to both coils simultaneously. A single diode is coupled across both the coils and restores DC to allow the center of the parabola to be fixed at a given DC reference.

Series-multiple transformer

Abstract: AN ELECTRICAL TRANSFORMER HAVING A PLURALITY OF UNTAPPED PRIMARY WINDING SECTIONS CONNECTABLE IN EITHER SERIES OR IN PARALLEL FOR ALTERNATIVELY EITHER A HIGHER PRIMARY VOLTAGE RATING OR A LOWER PRIMARY VOLTAGE RATING, A TAPPED PRIMARY WINDING SECTION CONNECTED IN SERIES WITH THE PLURALITY OF UNTAPPED WINDING SECTIONS IN BOTH THE SERIES AND IN THE PARALLEL CONNECTION THEREOF AND PERMITTING ADJUSTMENT BY A TAP CHANGER SWITCH OF THE EFFECTIVE NUMBER OF PRIMARY TURNS, WHEREBY TO ADJUST ALTERNATIVELY EITHER THE HIGHER PRIMARY VOLTAGE RATING OR THE LOWER PRIMARY VOLTAGE RATING OF THE TRANSFORMER

Telephone set with transmission by microphone and amplifier and reception by loudspeaker

Abstract: A telephone set has sound transmission by a microphone and amplifier over a transmission circuit, and sound reception by loudspeaker over a reception circuit. Each circuit includes an input transformer and an output transformer, and both circuits are connected, through a telephone transformer, to the line. The telephone set includes an arrangement for preventing the Larsen effect and other interference between the two circuits. This arrangement includes respective sets of four diodes or transistors, connected as a Wheatstone bridge, each connected between an input transformer and the associated output transformer. A square wave multi-vibrator is connected in parallel to the output transformer of the transmission circuit and to the input transformer of the reception circuit, and is connected, through respective diodes or transistors to the input transformer of the transmission circuit and to the output transformer of the reception circuit. The multi-vibrator supplies alternating positive and negative square wave pulses, at a frequency very substantially higher than the frequency of the sound waves, to the two Wheatstone bridges, with one Wheatstone bridge receiving a positive square wave pulse at the same time the other Wheatstone bridge receives a negative square wave pulse. The multi-vibrator is continuously operative, and, in effect, chops the modulated currents in the two circuits at a very high frequency of the order of 0.5 MHz.

Flyback transformer device

Abstract: A flyback transformer device wherein a flyback transformer and diode are accommodated in a hermetically sealed metal container which is filled with insulating oil whose amount of charge resulting from corona discharge is less than a predetermined value.

High voltage hold-down circuit

Abstract: Loss of the flyback pulse which regulates the bias applied to the control grid of the horizontal output tube of a television receiver can cause the high voltage developed for its picture tube to increase to a value at which X-radiations can be produced. Use of a dropping resistor to reduce the screen grid bias on the horizontal output tube in response to the increase in screen current which results when this negative voltage control is lost offsets this increase-and, with the further use of a clamping diode for the screen grid, maintains normal high voltage operation during non-fault conditions.

A Complete Monolithic Vertical-Deflection System for Television

Abstract: A one-chip TV vertical deflection system is now possible through recent advances in power IC technology. This paper describes the new integrated circuit which includes the vertical oscillator, output stage, and a special flyback generator. The temperature stable sawtooth oscillator has independent hold and height controls and is capable of excellent interlace. A current drive output stage precludes the need for a linearity control or yoke thermistor while providing the versatility to directly drive black and white through large screen color yokes. The advanced output flyback system provides excellent flyback and blanking from low supply voltages.

Circuit to prevent a transformer from presenting a low impedance upon core saturation

Abstract: An externally driven saturating transformer inverter is provided with an auxiliary commutating transformer whose windings are connected with those of a power transformer and diode members such that upon saturation of the power transformer core, a high-reflected load impedance is presented. High-current spike generation is obviated while the regulation advantages of pulse width modulation is retained.

A hybrid thermoelectric-thermomagnetic transformer

Abstract: A direct-current transformer has been constructed in which the primary consists of a thermocouple and the secondary consists of a thermomagnetic element. It is shown that this arrangement can be operated as a variable transformer, the voltage multiplication being controlled by the applied magnetic field.

Voltage transformer with removable high voltage fuses

Abstract: A high voltage transformer has a fuse with high cutoff power which can be directly extracted so that all measurements from the transformer can be carried out without shutting off voltage.

Adjustable focus voltage supply for television receivers

Abstract: An improved adjustable focus voltage supply for television receivers comprising a variable differential capacitor having at least two fixed plates and a movable plate. The fixed plates are coupled across a portion of the primary winding of the horizontal flyback transformer of the receiver. A diode rectifier has one terminal connected to the movable plate of the differential capacitor and a remaining terminal connected to a point on the winding which, during operation, normally generates pulses of greater amplitude than the points to which the fixed plates of the differential capacitor are connected. An output terminal for deriving the desired variably controlled DC focus voltage is connected to the juncture of the diode rectifier and the movable plate of the differential capacitor. The fixed plates of the differential capacitor are connected to spaced points on the primary winding and, in the illustrated embodiment, the connections straddle the point on the winding which is maintained at alternating current ground reference potential during normal operation. Additionally, the output terminal is connected through a load resistor to a source of alternating current ground reference potential.