Showing papers on "Flyback transformer published in 1978"

Transformer and inductor design handbook

Abstract: Fundamentals of Magnetics. Magnetic Materials and Their Characteristics. Magnetic Cores, Iron Alloy and Ferrites. Window Utilization and Magnet Wire. Transformer-Inductor Design. Transformer-Inductor Efficiency, Regulation, and Temperature Rise. Power Transformer Design. DC Inductor Design Gap Core. DC Inductor Design Powder Core. AC Inductor Design. Constant Voltage Transformer Design (CVT). Three Phase Transformer Design. Flyback Converter Design. Forward Converter Transformer and Inductor Design. Input Filter Design. Current Transformer Design. Winding Capacitance and Leakage Inductance. Quiet Converter Design. Rotary Transformer Design. Planar Transformers. Derivation for the Design Equations. Index.

Self-referencing power converter

Abstract: A self-referencing power converter operates at a high frequency with a low loss, light weight ferrite core transformer. The transformer primary is selectively connected across a DC source of rectified AC power to provide energy storage followed by a predetermined time period of disconnect to provide energy transfer by way of transformer flyback. The energy storage cycle begins when the voltage across the primary winding of the transformer does not exceed a predetermined value and the predetermined time period of disconnect has ended. A current sensing circuit senses the current flowing through the primary winding, permitting such current to flow until a power reference is reached. A comparison circuit in the transformer secondary compares a reference voltage with an operating voltage and returns any error voltage to the primary circuit, the error voltage then being used to set the power reference.

Regulated switching mode power supply

Abstract: A switching mode power supply characterized by an output in the forward conversion mode and a separate output in the flyback mode whereby a device having variable power requirements in one aspect of its operation, and a stable power requirement another aspect of its operation may be powered without interference as between the two sources of power. The flyback power output is monitored for voltage regulation, regulation being achieved by a constant-off-time variable-on-time switch. The power supply likewise includes novel protective circuitry to shut it down in the event of excessive voltage or current therein.

Isolation and multiple output extensions of a new optimum topology switching DC-to-DC converter

Abstract: The recently introduced new optimum topology dc-todc converter is extended in a simple and elegant manner to provide dc isolation and multiple outputs. In comparison with the sinle-transistor isolated forward and flyback converters operated under the same conditions, the single-transistor isolated new converter is shown to have equal or lower stress levels on the transistor, diode, and capacitor ripple current, and can utilize an isolation transformer with lower core and copper losses. Measurements of cross- and self-regulation properties of a two-output 45 W test converter are presented.

Apparatus and method of phase shift compensation of an active terminated current transformer

Abstract: Apparatus and method of compensating for a shift in the phase of the current applied to a current transformer terminated in a low impedance operational amplifier. The operational amplifier phase response is altered to minimize the phase angle between the transformer current and the amplifier output voltage to thus provide an output voltage directly proportional to the transformer current.

DC Power supply

Abstract: A direct current (DC) power supply of the single-ended flyback type particularly suited for providing power for integrated circuits is described. The power supply is self-exciting and thus does not employ an auxiliary drive or oscillator. The starting/restarting circuitry provides protection against faults. Because of this fault protection, a relatively simple over-voltage circuit is employed at the output of the supply. An additional primary winding is used to provide protection for no-load conditions.

Device for energizing a D.C. motor, comprising an accumulator battery

Abstract: A small lightweight power-supply device a d.c. motor powered either by the a.c. supply voltage or by an accumulator battery which dissipates little power and has a well-defined output characteristic for a wide range of input voltages. The device comprises a flyback converter, the forward sweep time being a function of the output voltage and the current through the primary winding of the transformer of the flyback converter. The forward sweep time is controlled by a control circuit which is integrated for the greater part. There is provided a starting circuit. A level detector in the control circuit ensures that this circuit is activated only when its supply voltage, which is applied via the secondary winding of the transformer, is sufficiently high.

Solid state transformer differential relay

Abstract: A transformer differential relay monitors the current flowing through the primary and secondary windings of a power transformer and disconnects the transformer from a power source feeding the transformer whenever the magnitudes of these currents indicate a fault condition in the transformer. First and second current transformer generate primary and secondary winding voltage signals representative of the magnitude of the current flowing through the power transformer primary and secondary windings, respectively. A solid state restraint signal generator is responsive to the primary and secondary winding voltage signals and generates a restraint signal representative of the magnitude of the larger of the primary and secondary winding currents, respectively, at each measurement instant. An operate signal generator is responsive to the primary and secondary winding voltage signals and generates an operate signal representative of the magnitude of the vector sum of the currents flowing through the power transformer primary and secondary windings. Finally, means are provided for disconnecting the power transformer from the power source when the magnitude of the operate signal operates above a predetermined percentage of the restraint signal.

Interleaved High-Voltage Transformer Windings

Abstract: Interleaved-turn high-voltage transformer windings are a useful alternative to continuous disc and layer windings for a wide range of transformer output and voltage ratings. Many configurations have been devised to meet different requirements. This paper reports the discovery that the original and most- commonly-used form of interleaved winding has an unexpectedly large internal oscillatory response to chopped-wave or front-of-wave impulse (lightning surge) voltages. It describes the subsequent development of a less-oscillatory winding which allows smaller insulation clearances for equivalent reliability.

Defibrillator charging current regulator

Abstract: The capacitor of a defibrillator is charged to a high D.C. voltage from a low voltage D.C. source of small capacity by an inverter, a transformer, and a rectifier coupled in sequence. The turns ratio of the transformer is changed as the voltage across the capacitor reaches predetermined levels and the current in the primary of the transformer is regulated by comparing the voltage drop across a small resistor with the voltage of the source.

Test fixture having switching means for facilitating transformer turns ratio testing

Abstract: This disclosure relates to a transformer terminal switching unit or fixture with specially designed output terminals and transformer attachment cables. The disclosed transformer terminal switching unit is especially useful as an accessory to the BIDDLE Transformer Turn Ratio (TTR), tester, catalogue number 55003. The design of the transformer terminal switching test fixture is especially useful to test delta-star connected, three phase utility transformers with subtractively connected winding polarity. A transformer with additive windings can also be tested with the disclosed testing fixture.

Power saving circuit

Abstract: A circuit for selectively supplying current to the horizontal oscillator from one of two voltage sources. The first voltage source is primarily used to supply current to the horizontal output stage and supplies the oscillator only during startup of the horizontal deflection system. The second source is derived from a winding on the flyback transformer and supplies current to the oscillator after the startup period, that is, after its voltage or another or other voltages developed by sources derived from flyback windings have reached values sufficient to assure sustained operation of the horizontal deflection system. A startup detector responsive to a flyback-derived voltage determines which of the two voltage sources provides current at the output of the starting network, that is, at the power supply terminal of the horizontal oscillator.

Pulse transformer technique for optical switch

Abstract: Optical communication apparatus is disclosed whereby the voltage controlled load device typically requiring a relatively high energizing voltage is operated by means of a wide band step-up pulse transformer and a low voltage power source. The step-up transformer permits operation of the fiber optic communication system from a power source as low as 5 volts D.C. to obtain the necessary modulation potential required by the electro-optic and piezoelectric load device.

Flyback type power supply

Abstract: A flyback type power supply in which dissipation losses associated with switch transition time are substantially eliminated by performing all switching operations at or near zero current by the use of a plurality of resonant circuits. In a first resonant circuit an intermediate storage capacitor is resonantly charged through an inductor and a first switch until, after a half sinewave of charging current, the voltage on the capacitor is twice the input supply voltage. The capacitor is then discharged through a second switch and the primary inductance of a flyback transformer having rectifiers on the secondary that are back-biased initially so as to provide a resonant current buildup in the primary winding with an amplitude that follows a sinewave function, the primary voltage following a cosine function. At the peak of the sinewave of current in the primary, the voltage across the transformer reverses in polarity, continuing to follow a cosinewave shape until the secondary voltage exceeds the voltage on the network to be charged. The primary current is then discontinued and the remaining energy stored in the transformer inductance is transferred to the circuit to be charged.

Input transformer arrangement for use in a television receiver

Abstract: An input transformer arrangement includes an unbalanced signal suppress transformer for suppressing unbalanced signal carried in a feeder line extending between a television receiver and an antenna therefor, and an impedance transformer for dropping the impedance. These two transformers are arranged on one core for unifying and simplifying the arrangement.

Startup circuit for a television receiver

Abstract: In a television receiver containing both circuitry returned to the AC line and circuitry returned to an isolated chassis ground, a voltage supply isolated from the AC line for a horizontal oscillator returned to the chassis ground. The supply is developed by a winding magnetically coupled to an inductor in a switching regulator that is coupled to the AC line and operates at a frequency substantially equivalent to the horizontal oscillator frequency. With the horizontal oscillator operative, supply voltages for the remainder of the receiver's line-isolated circuitry can then be derived from windings on the flyback transformer.

Isolated B+ voltage sensing, high-voltage shutdown

Abstract: A shutdown circuit both electrically and magnetically isolated from the horizontal deflection circuit and the flyback transformer. The voltage across a winding magnetically coupled to an inductive element carrying the current required by the deflection circuit and the flyback transformer is detected. The horizontal deflection circuit is disabled in response to voltages above a predetermined value. In an Iso-Hot type receiver having an oscillator coupled to the deflection circuit by an optically operating drive circuit, the drive circuit is rendered optically non-transmitting.

Flyback transformer having terminal pins for connection to printed circuit boards

Abstract: A flyback transformer which has a coil bobbin provided with a low voltage coil and high voltage coil and a plurality of terminal pins to which the lead wires of these coils are to be connected and attached to the leg of the core, a hollow cylindrical housing which houses the coil bobbin and a housing cap provided with a through hole into which the leg of a core is inserted and contains a rectifier circuit which rectifies high voltage generated by the high voltage coil, wherein the terminal pins are projected from one end of the housing and the leg of the core is inserted into it and the housing cap is mounted on the other end of the housing and a space formed between the housing and the housing cap is filled with an insulating resin.

Push-pull inverter including starter circuit

Abstract: In a push-pull inverter (including a transformer) for changing direct current into alternating current, a circuit is disclosed for starting the inverter in which the first pulse of a rectangular pulse train applied to the transformer has a duration of one half that of the subsequent pulses. This aids in reducing the initial magnitude of the flux excursion in the transformer core.

Fluxbucking line transformer with electronic equivalent line terminating impedance

Abstract: A fluxbucking line transformer is disclosed in which fluxbucking primary windings in the line transformer compensate for the DC flux generated by the passing of DC currents by the primary windings. No feed-back circuitry is required for sensing the DC components of the magnetic field in the transformer core or to sense the DC current through the transformer to provide adjustment of the fluxbucking current. The disclosed transformer circuit is a bridge configuration which cancels the DC flux independently in separate primary windings, and is advantageously employed in telephone line circuits in which large DC currents are passed through the line transformer while smaller ac signals are coupled to the secondary without distortion of the ac signals due to saturation of the transformer core.

Device comprising a transformer for step-wise varying voltages

Abstract: A device comprising a transformer for step-wise varying voltages in which, in order to prevent undesired oscillations in the transformer, a circuit is included in the connection lead thereof, said circuit comprising at least one inductive element and at least one rectifying element. The inductance of the inductive element is a number of times higher than the leakage inductance of the transformer. The circuit has the property that the current through the inductive element (elements) does not change its direction when the sign of the voltage between its connection terminals is reversed.

Zero sequence current source for transformer having a nonwound tertiary

Abstract: A three-phase electrical transformer utilizes a conductor independent of the transformer windings for sensing zero sequence current upon the occurrence of a ground fault. A current transformer coupled with the independent conductor provides polarization to protective relay devices. One embodiment utilizes the transformer internal tank shield in combination with the current transformer for providing zero sequence current.

Switching regulator for a television apparatus

Abstract: A controllable switch is coupled to a source of unregulated direct voltage and in a closed loop with a filter inductor and a storage capacitor and has its on-off state controlled at the horizontal deflection rate to control the voltage across the capacitor and regulate a voltage. A diode is coupled with the filter inductor and storage capacitor to form a second series circuit through which current can continue to flow in the inductor when the controllable switch is opened. The controllable switch is opened abruptly by application of a reverse biasing flyback pulse to its main current conducting path. The flow of current in the filter inductor is smoothed and may extend over the entire horizontal cycle.

X-ray voltage supply

Abstract: A voltage supply for an X-ray tube provides both high and low voltages to the tube. A high voltage transformer using split primary and secondary windings is employed. The high voltage is switched on and off by selectively phasing the voltage across the transformer's secondary coils. Low voltage is coupled from one of two primary windings.

Apparatus for manufacturing flyback transformer

Abstract: PURPOSE:To ensure safety of operators by always surrounding the coil of the flyback transformer such as to practically perfectly isolate the gas produced from the synthetic resin injected into the coil in vacuo fron atmosphere.

Variable segmented ramp voltage synthesizer

Abstract: A variable segmented ramp voltage synthesizer is disclosed as including a ster pulse generator and a plurality of series connected one-shot multivibrators connected to the output thereof for producing a like plurality of gating signals. In response to said gating signals, a like plurality of successively increasing voltages, effected by a given positive direct current voltage source and appropriately different resistances, are gated into a constant current generator. The output signal from said constant current generator is substantially stair-step in waveform, and it is supplied to a predetermined, relatively large capacitance for the charging thereof with respect to another direct current voltage that is more negative than the aforementioned positive direct current voltage. The charging thereof occurs as serially connected substantially linear segments, the ramp-like slopes of which are proportional to the RC time constants effected by the aforesaid resistances in successive combinations with said capacitance, respectively. An electronic switch timely discharges said capacitance in response to the master timing pulses produced by said master pulse generator, so as to produce flyback in preparation for synthesizing another sawtooth signal cycle. A circuit isolation buffer amplifier is optionally connected to the effective output of the aforesaid capacitance.

Manufacturing method of flyback transformer

Abstract: PURPOSE:To produce inexpensive FBT having insulation performance as good as that of encased one, by finishing filler resin surface smoothly.

Television deflection circuit

Abstract: A television horizontal deflection circuit is provided with a flyback transformer and a switching regulator transformer which are substantially magnetically independent of each other and which are connected with their primaries in series with a switching device and a source of input voltage. The secondary winding of the switching regulator transformer supplies power to a regulated D.C. voltage supply, which in turn supplies power to a resonant circuit. The resonant circuit is connected to a reference potential through the switching device and includes a damper diode, a resonant capacitor, a deflection coil and a series connected capacitor. A secondary winding of the flyback transformer is used to derive a high voltage for use in the high voltage anode of a television picture tube. In a preferred embodiment, the flyback transformer contains an additional winding which is connected between the regulated D.C. voltage supply and the resonant circuit. This additional or feedback winding is inductively coupled with the primary winding of the flyback transformer so that the flow of current through that primary winding while the switching means is conductive will impede the flow of current from the regulated D.C. voltage supply to the resonant circuit.

Horizontal output device

Abstract: PURPOSE:To protect the horizontal output transistor and to ensure a stabilized operation for the vertical deflection circuit in case the load of the flyback transformer has a short circuit, by securing the non-earth for the secondary side of the flyback transformer by means of a transformer.

High voltage limiting circuit for a television receiver

Abstract: A high voltage limiting circuit for a television receiver employs a negative pulse sample from a tertiary winding on a flyback transformer as a measure of high voltage. When the amplitude of the negative pulse sample exceeds a predetermined value, indicating excessive high voltage, a limiting circuit applies a voltage to an automatic frequency control input of a horizontal oscillator to increase the frequency of the horizontal oscillator. The increased frequency limits further increase in high voltage.