Showing papers on "Flyback transformer published in 1980"

Solid State Transformer Concept Development.

Abstract: : This report describes an effort made to determine the feasibility of developing a circuit using power semiconductor devices to duplicate the function of the power transformer A circuit concept has been developed which duplicates the primary function of voltage stepup/stepdown but does not demonstrate the DC isolation characteristic of normal transformers Several characteristics of the circuit appear very attractive, such as increased voltage regulation and relatively high efficiency (Author)

Power supply for electrostatic apparatus

Abstract: A power supply for electrostatic apparatus provides a high voltage output. The high voltage output is provided by the half wave rectification and filtering of a pulse signal from a secondary winding of a high voltage pulse transformer. The primary winding side of the high voltage pulse transformer is connected in a series loop circuit with a capacitor and a switching device. The capacitor is charged through an input choke connected to a DC supply source. The switching device is triggered after the capacitor is charged such that the capacitor is discharged through the primary winding of the high voltage transformer. The inductive collapse of the high voltage output transformer provides for the turnoff of the switching device and also serves to partially recharge the capacitor. The half wave rectified high voltage output of the power supply is obtained from the recovery pulse of the high voltage pulse transformer. The efficiency of the power supply is improved since ringing in the transformer is dampened due to the extraction of energy from the recovery pulse. The recovery pulse is much higher in amplitude than the firing pulse during which the switching device discharges the capacitor through the primary winding of the pulse transformer. During each repetitive period, the capacitor is charged, the switching device discharges the capacitor, and a short durational recovery pulse is generated. Several independent outputs of the power supply are obtained by providing respective, independent series combinations of transformers and capacitors with the series combinations being connected in parallel across the switching device.

Resonant-flyback power supply with filament winding for magnetron and the like loads

Abstract: A filament winding forms a part of the step-up transformer in a flyback-type high-frequency, high-voltage power supply for supplying filament heating energy, in addition to the anode potential supplied by a secondary winding of the transformer, to a magnetron microwave power generator, which is a self-rectifying load. The voltage across the transformer primary winding, and the current flowing through a controllable current path in a switching device connecting the series with that primary winding, are both monitored and compared to reference voltage and current values for establishing the conduction time interval of the switching device to provide active control of the power input to the load.

Wide input range, transient-immune regulated flyback switching power supply

Abstract: A low cost switching mode power supply particularly adapted for use in an electric vehicle is characterized by an extreme input voltage range, immunity to high input voltage transients, and stable operation. A negative voltage feedback arrangement applied to a controllable voltage clamp serves to continuously vary oscillation pulse width and frequency. The power supply includes an output filter capacitor, and, to compensate for phase lag introduced by the output filter capacitor, the negative feedback arrangement includes elements for introducing phase lead compensation. Preferably, the oscillation period is less than the duration of expected input voltage transients, and the power supply regulates right through such transients.

Free-running flyback DC power supply

Abstract: A free-running flyback DC power supply includes a transformer having at least one primary and one secondary winding, a transistor switch in series with the primary winding for controlling when current from a source of DC power is coupled through said winding, and a rectifier circuit attached to the secondary winding for generating a DC output voltage. A conventional regulator circuit causes the transistor switch to turn off primary winding current as a function of the present value of DC output voltage. A second circuit senses excessive current in the primary winding and causes the transistor switch to turn off independently of said regulator circuit, to protect against damage to the transistor switch or transformer. A third circuit detects when the DC source voltage is below a predetermined minimum and causes the transistor switch to turn off independently of said regulator circuit. Regulation of the output DC voltage is also maintained as a function of the present value of DC source voltage. An additional circuit causes the regulator circuit to turn off the transistor switch early if the DC output voltage drops below a predetermined minimum.

Transformer coupled isolation amplifier

Abstract: A transformer-coupled isolation amplifier which has a minimally sized transformer, high common mode rejection, and a highly linear response over a wide dynamic range. A first chopper periodically alternates by 180° the connection of the input through a high resistance to the primary of a small square loop pulse transformer. The secondary, with the end of the winding closest to the primary grounded, has the inputs of an operational amplifier placed across it. Negative feedback is provided around the amplifier to provide an apparent very low impedance across the secondary of the transformer. The negative feedback induces a current in the transformer secondary which cancels the flux produced by current flowing in the primary, thereby allowing usage of the transformer normally suitable only for high speed pulses. The output of the amplifier connects to a second chopper synchronous with the first to generate the amplified analog signal. A unique isolated power supply supplies power and switching signals for the first chopper.

Rectifier-converter power supply with multi-channel flyback inverter

Abstract: An AC to DC power supply having a multi-channel, flyback inverter output section regulated via a fixed frequency, pulse width modulation controller. The controller indirectly regulates each channel by regulating an auxiliary channel, whereby the duty cycle of a switching transistor in the flyback inverter section is varied to maintain a constant DC voltage on the auxiliary channel and correspondingly on each output channel.

X-ray diagnostic generator

Abstract: An inverter, with a frequency lying in the medium frequency range, and a mains rectifier are connected with the high-voltage transformer Between the X-ray tube and the high voltage transformer there is disposed a high-voltage rectifier with a high-voltage filter member There is likewise connected with the filament transformer an inverter with a frequency lying in the medium frequency range and a mains rectifier Filter members are connected between the mains rectifiers and the inverters Plural inverters with different phase may supply respective high voltage transformers, and each transformer may have a voltage doubler high voltage rectifier contributing to X-ray tube anode voltage

Ultrasonic fluid-atomizing cooled power transformer

Abstract: A vapor-cooled power transformer characterized by a transformer within a sealed housing, and means for applying ultrasonic vibrations to a dielectric liquid within the housing in order to vaporize the fluid and to apply it to the exposed surfaces of the transformer.

Power supply and deflection circuit with raster size compensation

Abstract: A deflection generator periodically applies a trace voltage to a deflection winding to produce scanning current and periodically generates a retrace pulse voltage across the deflection winding. A supply voltage source develops the trace voltage and also provides energy to circuits, such as a high voltage circuit, coupled to windings of a flyback transformer. The high voltage circuit develops an ultor accelerating potential from the retrace pulse voltage developed across the high voltage winding of the flyback transformer. A controllable switch such as an SCR is coupled to the source and to a secondary winding of the flyback transformer. The trace voltage and energy transfer is regulated by controlling the conduction time of the SCR. The high voltage and other load circuits draw load current from the source through the flyback transformer secondary winding during retrace, resulting in high voltage retrace pulse duration and amplitude variation with variations in load current. To maintain a constant raster width, the conduction time of the SCR is varied such that the trace voltage magnitude varies in the same sense as the retrace pulse voltage amplitude variations.

High voltage winding for dry type transformer

Abstract: A compact air cooled transformer employs multisection, multilayered high voltage coils in a wye connection to substantially reduce the spacing required between the high voltage coil and low voltage coil and between the ends of the high voltage coil and the transformer core yokes and coil support structure.

Ferrite core type transformer

Abstract: A ferrite core type transformer, such as a flyback transformer used in a television receiver, includes a ferrite core unit and a coil unit mounted on the core unit. The ferrite core unit is constituted by a pair of U-shaped core members which are arranged to assume a figure "O" with a suitable spacer members held between each of the matching ends. A first bonding agent of quick hardening type is applied between the matching ends of the U-shaped core member, and a second bonding agent having resiliency is deposited in a contacting area between the core unit and the coil unit.

Electrodeless lamp operating circuit and method

Abstract: An operating circuit and method for efficiently operating and starting an electrodeless lamp having a magnetic core operated at radio frequencies. The circuit generates a current which flows through the winding of an electric field inducing means in the lamp in a reverse-bias direction, with respect to a drive current, to operate the core of the inducing means in all quadrants of the B-H curve, with the time average of all current through the lamp winding equaling approximately zero in order to avoid or minimize heat energy losses and sharp current peaks caused by saturation. This also allows use of lower current-capacity less-expensive components. The circuit repetitively applies constant-current DC drive pulses to the lamp winding for a small percentage of an interval during which energy is stored, which is used to generate the reverse-bias current. Additionally, energy of flyback associated with turning-off of current in the lamp-winding-and-core is maximally limited to the winding itself for facilitating faster starts.

Flyback voltage control

Abstract: Flyback power supply with secondary circuit damping during primary charging. This reduces the induced or reflected oscillations into the primary circuit and superimposition onto the primary current so that the latter becomes a monotonically increasing function, permitting and facilitating feedback control.

Over stress sense circuit for flyback power supply

Abstract: An overload protective circuit for direct current switching or flyback power supplies which senses for build up of internal transistor stress during operation of the main power transistor output stage. Normally, setting an internal overload limit for the main power transistor dissipation is difficult to achieve because the load current to be sensed is out of phase with input driver current. The invention provides for sensing a change in base drive input voltage during a departure from normal operating saturation of Baker clamped main power transistors and initiating a reduction in the width of the drive pulses to reduce internal transistor stress and to reduce power input prior to transistor damage.

Plasma display with direct transformer drive apparatus

Abstract: A system for driving a plasma display panel is disclosed in which a transformer operated at a system clock frequency supplies voltage pulses to both the electrodes in the cells of the display device. Switching members operated by control signals generated by a control member select the cells to be discharged. A circuit for regulating the transformer output voltage in accordance with the number of cells discharged is also disclosed.

Television receiver high voltage protection circuit

Abstract: The retrace pulse voltage developed across a television receiver flyback transformer winding is rectified and filtered to develop a voltage representative of picture tube ultor voltage. This representative voltage is applied to an input terminal of a comparator. A beam current representative voltage, obtainable, for example, at the input of a beam limiter circuit, is applied to a filter. The filter output voltage, which is the time integration voltage of the beam current representative voltage, is applied to another input terminal of the comparator. The comparator develops a disabling signal that is utilized to disable normal television operation when the ultor voltage exceeds a magnitude which differs with different values of the filter output voltage. The beam current information from the filter output increases the comparator sensitivity to ultor voltage increases at the higher beam current levels where greater amounts of X-radiation may be produced while avoiding unnecessary disabling of television operation at the lower beam current levels where greater increases in ultor voltage may be tolerated. The time constant associated with the filter is relatively short for relatively light beam current loading conditions and is changed to a relatively long time constant value under severe beam current loading conditions in order to ascertain whether a permanent current overload condition exists that requires disabling of the television receiver.

Television receiver focus voltage circuit

Abstract: The retrace pulse voltage developed by a horizontal deflection generator is applied to the primary winding of a flyback transformer. The voltage at an intermediate point of the flyback transformer high voltage winding is rectified and filtered to produce an intermediate, DC high voltage. A pulse forming circuit is coupled to a secondary winding of the flyback transformer to produce voltage pulses repeating at the horizontal deflection frequency. The amplitude of the pulses is parabolically modulated at a vertical rate. The amplitude modulated pulses are rectified and filtered to produce a parabolically shaped vertical frequency voltage. The voltage developed across another flyback transformer secondary winding is waveshaped by an LC resonant circuit to produce a sinusoidal or a substantially parabolically shaped horizontal frequency voltage. The intermediate DC high voltage and the parabolically shaped vertical and horizontal frequency voltages are summed to produce the focus voltage.

Half-wave signal isolator with means for controlling flux in the coupling transformer

Abstract: A signal isolator including a coupling transformer with modulate/demodulate switches in series with the primary and secondary windings. The switches are driven in synchronism by an oscillator. Resonating capacitors are connected in parallel with the transformer windings to form an LC tank circuit tuned approximately to the operating frequency of the switch-drive oscillator. When the switches are closed, the current in the transformer windings ramps in a linear fashion in response to application of the input voltage, and when the switches are opened, the current varies in a cosine curve to provide smooth transitions at both ends to the ramp current, thus controlling the flux in the transformer core so as to minimize instability effects.

Ignition apparatus for a burner

Abstract: A compact ignition apparatus for a burner, which rectifies the commercial power source and energizes a high-voltage transformer via a transistor blocking oscillator circuit, and in which the high-voltage transformer is provided with a control circuit for controlling the output of the transformer to a constant value against any fluctuation of the input to the transformer, whereby a secure ignition is provided.

Commutated scr regulator for a horizontal deflection circuit

Abstract: A retrace pulse voltage is applied to a first flyback transformer winding of a horizontal deflection circuit to develop retrace pulse voltages across other flyback transformer windings. Second and third windings of the flyback transformer are coupled in a series arrangement with a controllable switch across a source of input voltage. A regulator control circuit turns on the SCR at a controllable instant within the trace interval of each deflection cycle to generate input current in the series arrangement. When the retrace pulse voltage is applied to the flyback transformer first winding, the input current begins to decrease in magnitude, commutating off the SCR within the retrace interval. The leakage inductance associated with the series arrangement of flyback transformer second and third windings and the total reflected retrace pulse voltage developed by the two windings determine the instant within retrace that the SCR is commutated off. The third winding is loosely coupled with the first winding, whereas the second winding is tightly coupled with the first winding. By varying the second to third winding turns ratio, the amount of leakage inductance in the series arrangement may be varied without significantly altering the magnitude of the total reflected retrace pulse voltage.

Flyback power supply booster circuit

Abstract: A booster circuit is disclosed for enabling a flyback power supply having a power transformer normally operative in a free running mode to have an increased power output at high loads, comprising a clock circuit including a first transistor that is turned on whenever a resistor-capacitor network times out before the end of the flyback interval of the power supply, with the result that the flyback interval is caused to terminate early, and the power transformer to begin recharging. A second transistor acts to disable the operation of this first transistor whenever the output voltage of the power supply is found to not be in regulation.

Colour cathode ray tube display apparatus with compensation for errors due to interfering magnetic fields

Abstract: A color cathode ray tube display apparatus is provided with compensation for errors due to interfering magnetic fields in which a deflection yoke causes the electron beams to raster scan across the tube, a convergence assembly on the neck of the cathode ray tube adjusting the beam convergence. Errors in the waveforms suppied to the radial convergence assembly are caused by high frequency magnetic field coupling between the yoke and the convergence assembly via the internal magnetic structure 7 of the cathode ray tube. A compensating coil 11, placed adjacent the convergence coil unit 12, 16 supplies compensating current through resistor 20 to the amplifier 15 driving the convergence coil unit, thus avoiding a fringe on the left-hand side of the screen. Alternatively, compensating current can be derived from the line flyback pulse or the logic signal initiating line flyback.

Horizontal scanning circuit

Abstract: A horizontal scanning circuit constituting a self-oscillation circuit, by providing a winding for feedback in a flyback transformer, and by positively feeding back the output signal from said winding to the base of horizontal power transistor. Since this constitution does not require transformer for impedance conversion, the circuitry is simplified.

Combined fault current and applied voltage tripping for solid state trip circuit and particular current transformer construction

Abstract: A solid state trip circuit is disclosed which uses a shunt path saturable transformer comprised of a current transformer having a relatively high resistance shunt which serves to apply input voltage to the transformer primary winding. The larger the input current the higher the voltage drop across the shunt and the more quickly the transformer iron will become saturated. The saturation time during each half cycle then produces a measure of the current flow in the primary line. The output of the secondary winding of the transformer as well as a direct but resistive connection from the input circuit lines are applied to a solid state trip circuit which operates a circuit breaker trip latch. Energy for tripping at lower overload current is derived directly from the applied voltage from the line. At high overload conditions however, direct tripping occurs through energy derived from the transformer rather than directly from the line voltage.

Color picture display device with a circuit for generating a screen grid voltage

Abstract: A color picture display device having a circuit for generating a screen grid voltage derived from the line deflection generator, while the high tension generator is separated. Via a resistance element, the screen grid is coupled to a source which generates a parabolic voltage of the field frequency with a curvature opposite to that obtained by rectifying the line flyback pulses owing to the east-west modulation, the resistance element, for example a voltage-dependent resistor, having in operation, a dynamic resistance which is many times lower than the static resistance thereof.

Voltage stabilizing transformer

Abstract: An improved magnetic core transformer for use as a voltage stabilizer in gas discharge lamps and tube circuits. The transformer has a magnetic stack length greater than either side of the magnetic cross-section and a floating shunt assembly constructed from stacks of magnetic strips. The stack length is optimized technically and as a function of the cost of iron and copper utilized in the transformer and when conformed with an optimum shunt a greater leakage inductance variation is achieved.

Regulated deflection circuit

Abstract: To regulate the DC input voltage to a deflection circuit, a saturable reactor winding is series coupled with an unregulated DC voltage, a diode, a flyback transformer winding and an input terminal of the deflection circuit. During retrace, the diode is forward biased and conducts input current to the input terminal. During trace, the opposite polarity trace voltage commutates off the diode and decouples the input terminal from the unregulated DC voltage at a varied instant within trace in accordance with the impedance of the saturable reactor winding. The average DC voltage across the diode fluctuates with diode conduction angle variations and maintains a regulated input voltage at the input terminal despite fluctuations in the unregulated DC voltage.

Ghost eliminating circuit

Abstract: PURPOSE:To realize the high-speed and high-accuracy elimination of the ghost by using the horizontal synchronous signal or the vertical synchronous pulse part within the vertical flyback time which is contained actually in the TV signal for the reference signal for eliminator of the ghost. CONSTITUTION:Compensation signal generation circuit 2 generates the compensation signal to offset the ghost component contained in the output of video detection circuit 1, and the waveform of the signal can be controlled over a wide range with the coefficient value of several units of the coefficient circuit. Scan sampling circuit 5 actuates sample pulse generation circuit 6 via the vertical and horizontal synchronous signals contained in the output signal and only for the scanning line period including the vertical synchronous signal part within the vertical flyback time in order to generate the sample pulse for the fixed scanning line period. And the 2nd adder circuit 10 generates the difference signal between the signal of output terminal 4 and the output signal of delay circuit 9. The output of circuit 10 is sampled by sampling circuit 7 and based on the output of circuit 6, and then the error signal is extracted. With use of the sample series of this error signal, control circuit 8 gives the control to the coefficient groups of circuit 2.

Power control circuit for television picture receiver

Abstract: PURPOSE:To reduce the power loss as well as to ensure the steady operation of the load by turning off the switch circuit through detection of the fact that the charge voltage of the capacitor becomes lower than the rectification output voltage of the flyback transformer. CONSTITUTION:Output voltage V11 obtained through rectification of the commercial AC power source is charged by capacitor C1, and the change voltage detection circuit in control circuit 25 detects the fact that the charge voltage has reached the fixed level. With the detection signal of the charge detection circuit, switch circuit 22 supplies the charge voltage of C1 to the load. Here in case the charge voltage of C1 becomes lower than voltage V22 of terminal 24 which rectified the output horizontal pulse supplied from the flyback transformer, the detection circuit in circuit 25 detects this to turn off circuit 22 as well as supply voltage V22 to the load via output terminal 23. Thus the power loss can be reduced, ensuring the steady operation of the load.