Showing papers on "Flyback transformer published in 1983"

X-ray tube bias supply

Abstract: 57 A power supply is switchable to apply a low kilovoltage and a relatively higher kilovoltage alternately to the anode of an x-ray tube that includes a filament and a control grid. A grid bias voltage generator uses an inverter driven in the kilohertz frequency range to feed the primary winding of a first transformer whose parasitic capacitance and inductance are used to produce a peak ac output voltage from the secondary of the first transformer at resonant frequency. The secondary output voltage is rectified and the resulting negative bias voltage is applied to the control grid synchronously with the high kilovoltage being applied to the anode so the x-ray tube current is then relatively low. A less negative or zero bias voltage is applied to the grid synchronously with the lower kilovoltage being applied to the anode so the x-ray tube current is then relatively high and substantially limited by the temperature and emissivity of the filament. A second transformer identical to the first one is used to sense the ac output voltage of the first one. A voltage-to-frequency converter switches the inverter. The resonant circuit ac output voltage sensed by the second transformer is rectified and compared with a selectable dc control signal and any resulting error signal is used to adjust the converter frequency and, hence, the inverter frequency so the bias on the x-ray tube grid voltage is proportional to the dc control signal level.

Method of and apparatus for efficient high voltage generation by resonant flyback

Abstract: This disclosure is concerned with adapting very high-voltage, low-current, high impedance power source circuits, such as CRT anode supplies and the like, to employ the efficiency over wide input voltage ranges and other advantages, including small size, of switching-mode operation through combining variable frequency (or period) output control circuitry with resonant high-voltage transformers, wherein the transformer resonant frequency is rendered comparable to the desired range of conversion frequencies; and in which resonant flyback circuit operation drives a voltage multiplier such as to accommodate the resonance caused by the stray capacitance shunting its storage inductance.

Current transformer for measuring instruments

Abstract: The current transformer for instruments for measuring electric currents includes a magnetic core that has two cores and an inductive current divider with three parallel current paths. The current dividers form, together with cores, two current transformer stages whose magnetic fluxes mutually cancel one another. In a current transformer for AC currents having a DC component, the ratio of the ohmic resistances of the individual current paths is in direct relation to their transformation ratio.

Electronic transformer system for neon lamps

Abstract: An electronic transformer system for illuminating neon lamps includes a counterphase oscillator coupled to a leakage reactance power transference transformer. The power transference transformer has a secondary wound on a multiple section bobbin in which adjacent sections are separated from each other by a dielectric material. The leakage reactance power transference transformer has a feedback winding which is coupled in series to the primary winding of a pulse generator base driving transformer. The pulse generator base driving transformer in turn provides periodic pulses to the counterphase oscillator to reverse current flow in the primary of the leakage reactance power transference transformer. The electronic transformer system may be powered by commercial alternating current through a full wave rectifier, or by a direct current power supply.

A realization of low‐power supplies using switched‐capacitor transformers and its analysis

Abstract: A switched-capacitor transformer is a coil-less transformer in which stepping-up and -down of voltage is handled by switching the connections between capacitors alternately into series and parallel. This paper demonstrates that a low-power coil-less power supply can be created with these transformers. the proposed circuit has the following features: (1) High efficiency, comparable to that of a switching regulator, can be obtained easily. (2) Because of its coil-less construction, it can be made small and light. Hybrid integration is also possible. (3) Coil-less construction significantly reduces generation of magnetic fields. the operating principle is first shown for the circuit with ideal elements. State equations are then derived in which the on-resistance of the switch element is considered, and these are numerically analyzed. an SC transformer with a transformer ratio of 1/2 and an SC dc-dc converter with an output voltage regulator already have been constructed with discrete components. Results of the average output voltage and efficiency have been confirmed numerically by experiments on constructed circuits. A comparison of the above two circuits demonstrates that although the latter has an efficiency of about 80% (which is lower than that of the former), both have less than ±0.06% in input-output variation. the voltage variation is at most -0.16% for the temperature variation of −20° ∼ 80°.

A new flyback DC-to -three-phase converter with sinusoidal outputs

Abstract: Systematic extension of any dc-to-dc converter leads to its dc-to-three-phase equivalent characterized by sinusoidal output voltages and fast dynamic responses. This genralization principle is illustrated for the special case of the flyback topology. State-space averaging has modeled with a high degree of accuracy the performance of dc-to-dc converters. Here it is combined with the stationary-to-rotating coordinate transformation, customarily used in plyphase ac systems, to results in an effective analysis method for switched-mode dc-to-polyphase converters.

Flyback transformer with high voltage variable resistor built therein

Abstract: A high voltage variable resistor section (8) for deriving the focusing voltage and screen is attached to an open portion formed on one surface of a first case (47) which receives primary and secondary windings (2, 3) included in a flyback transformer section (1). An insulating substrate (16) on which resistor elements (9-13) included in the high voltage variable resistor section are formed in housed in a second case (15). An opening is formed in one surface of the second insulating cases (15). With this opening communicating with the opening in the first insulating case, the two insulating cases are integrated. These insulating case define insulating case means, in which a high voltage capacitor (14) for compensating cathode ray tube capacity is housed. The high voltage capacitor is disposed between the secondary winding (3) and the resistor elements (9-13) in such a manner that the surfaces of the electrodes (38, 39) of the high voltage capacitor are opposed to the secondary winding (3) and the resistor elements (9-13). This arrangement prevents unnecessary radiation components due to ringing noise induced in the secondary winding from being transferred to the resistor elements and superposed on the focusing voltage.

Solid state regulated power supply system for cold cathode luminescent tube

Abstract: A solid state power supply and light emission controller for a cold cathode luminous tube which converts standard alternating current line voltage, or direct current voltage, into a variable repetition rate pulse alternating current voltage for energizing the tube and for controlling the light emission thereof. The power supply and controller provides for essentially constant light emission from the tube in the presence of variations in the load presented by the tube, ambient temperature and line voltage. The power supply and controller includes a flyback transformer circuit which, in turn, includes circuitry for monitoring the line voltage and the load presented by the tube, and for providing an automatic cut-off when the line voltage decreases below a predetermined level. The power supply and controller finds use, for example, with cold cathode luminescent tubes such as fluorescent-mercury-argon-neon, fluorescent neon, clear mercury-argon-neon, and clear neon.

Low leakage transformers for efficient line isolation in VHF switching power supplies

Abstract: A transformer assembly suitable for use in very high frequency (VHF) switching power supplies that maintains a low leakage inductance between critical transformer windings while complying with the physical and electrical requirements imposed by standards for primary to secondary isolation. The transformer includes a telescopic bobbin assembly with an inner and an outer section that telescope together to form an interior clearance space or chamber between the two sections. The interior chamber has a narrow conduit exiting to the exterior of the bobbin assembly. Described are two embodiments for a transformer used in a forward-averaging type converter and a third embodiment for a transformer used in a frequency modulated converter.

Variable transformer and voltage control system

Abstract: A system for automatically controlling output voltage to correct for varying input voltage utilizes a transformer having a movable core structure. The output voltage from the transformer is sensed and made to conform to a predetermined standard by moving the movable core structure, which is then locked in position after its adjustment. Voltage changes are step-free, and linear voltage control with respect to time is achieved through non-linear movement of the core structure over a range of variation of the output voltage.

Floating battery feed circuit

Abstract: A floating battery feed circuit (10) comprising a switching-mode, flyback power converter (200) wherein a capacitor (C3) connected to a converter transformer winding (201) develops a relatively low voltage used to energize the converter control circuitry (100). The converter control circuitry prevents the operation of the battery feed circuit unless the voltage developed by the capacitor is above a predetermined magnitude. The power converter advantageously operates in only a constant-power mode regardless of loop impedance.

Flyback DC/DC converter with low ripple in the output capacitor

Abstract: A flyback type DC/DC converter includes an input filter with input capacitor (C₁), an inductance (L) in series with a power transistor (T) and an output filter with an output capa­ citor (C₂). The input capacitor (C₁) is connected in series with the output capacitor (C₂) and to the input terminals of the converter to compensate the ripple current in the output capacitor (C₂).

Switching regulator current limit circuit

Abstract: A series flyback switching regulator, having a transformer with a primary coil for receiving an unregulated input voltage and a secondary coil for providing a regulated output voltage, includes a circuit for limiting the magnitude of a substantial overload or short circuit current. The current limiting circuit senses the magnitude of current flowing through the primary coil and sets a current limit level which is based upon a predetermined maximum current allowed in the primary coil. The current limiting circuit also senses the magnitude of the voltage present at the secondary coil of the transformer and reduces the current limit level, based upon a sensed reduction in the secondary coil voltage. The input voltage is removed from the primary coil when the magnitude of the current through the primary coil exceeds the current limit level as reduced by the sensed reduction of the voltage appearing across the secondary coil.

Control circuit for a flyback stepcharger

Abstract: A control circuit for a flyback stepcharger comprising a source producing aurrent proportional to a power supply output in order to charge a capacitor. When the capacitor reaches a predetermined level the charging stops and switching transistors to the primary of the transformer of the stepcharger are turned on. When the primary current reaches another predetermined level the switching transistors are turned off. The source charging the capacitor is restarted a set time after the switching transistors are turned on. The stepcharging is terminated when the DC voltage of the power supply output reaches its set value as measured when the switching transistors are on.

Operating characteristics of coupling-decoupling transformer

Abstract: This paper describes a new dc-ac converter called coupling-decoupling transformer. The coupling-decoupling transformer is constructed with an orthogonal core and a thyristor inverter. Using the coupling-decoupling transformer, we can easily control the power transferred from a dc source to an ac distribution line. Useful operating characteristics are obtained in the trial coupling-decoupling transformer.

Flyback transformer with variable resistor

Abstract: PURPOSE:To facilitate the connection of the secondary coil of a transformer with a variable resistor and case sealing work by pressing a seal made of conductive rubber into a through hole on the side of the transformer and mounting the variable resistor on the outside of a case so as to cover the seal CONSTITUTION:A flyback transformer 20 with a variable resistor is composed of a flyback transformer 21, a variable resistor 22, and a transformer case 30 Each of primary and secondary coils 23 and 24 is wound on the transformer 21 surrounded by the case 30 A resistor case 31 is provided on the side of the case 30 on which the resistor 22 is mounted, in which a case 32 made of an insulator is arranged A film resistive layer is formed on the base 32 The case 31 is connected by a resistor case connecting frame 43 provided on the side of the case 30 On the side of the case 30 surrounded by the connecting frame 43 is formed a through hole 44, into which a seal as an input terminal 46 made of conductive rubber is provided The seal is connected with an output terminal 45 to facilitate sealing work

Low-power acoustic injector drive circuit with enhanced turn-on

Abstract: An acoustic fuel injector system comprises a DC-to-DC converter (14) for supplying a regulated voltage to a frequency controlled oscillator (16) which drives the injector valve (18) or valves. The converter comprises a flyback oscillator (28) including a switching transistor (32) and a transformer (34, 36) for applying rectified current pulses of variable amplitude and occurrence rate to an output capacitor (42). A variable impedance device (50) in the input circuit to the flyback oscillator is controlled by a feedback signal (68) from the output circuit (30) to vary the cycle rate of the flyback oscillator to maintain output voltage at a desired value. The feedback signal is coupled to the oscillator control circuit input to effect a variable regulated output voltage which is relatively high upon injector turn-on but decays to a lower operating level thereafter.

A Combined Transformer Bridge for Precise Comparison of Inductance with Capacitance

Abstract: A combined transformer bridge, composed of two alternately balanced transformer bridges, designed for precise comparison of inductance with capacitance standards has been analyzed. A number of possible sources of error have been studied and experimentally examined in a constructed model of the combined bridge. The experimental results confirmed an ability to measure inductance in reference to capacitance with an accuracy up to 10 parts per million (ppm) in the frequency band 0.16-2 kHz.

Current limit circuit in single-ended forward converter utilizing core reset to initiate power switch conduction

Abstract: Current limit protection against current overload is obtained in a core-reset, forward-type converter by inserting a properly selected impedance in the flyback current path. The voltage developed across the impedance is impressed against the secondary winding of the power transformer. During current overload, the voltage drop across the impedance maintains a voltage drop across the secondary winding delaying a zero crossing of the voltage and, hence, delaying the initialization of conduction in the converter power switch. The time delay in conduction initiation in the power switch reduces current output and effectively counteracts the overload current.

Detector for television signal

Abstract: PURPOSE:To surely discriminate the presence/absence of a signal even at a weak electric field for TV signals, by eliminating noise components included in the TV signals with a resonance circuit and selecting only a signal coincident with a flyback pulse. CONSTITUTION:A horizontal synchronizing signal is applied to a resonance circuit 2 via a resistor 1. Only a horizontal synchronizing signal frequency component and noise component coincident with the resonance frequency of the circuit 2 are picked up from this signal at the circuit 2. This output voltage is applied to a base of a transistor (TR) 7 of a detection circuit 6, and from the output voltage noise during the absence of flyback pulse applied to a terminal 25 is eliminated through the operation of a TR15 in a block circuit 20 and the horizontal synchronizing signal component and noise remain only during the presence of flyback pulse. When an output of the circuit 6 is higher than a voltage of a constant voltage power supply 13, a TR 11 is turned off and the audio signals are normally transmitted without being erased.

Flyback switching power supply

Abstract: A control device (IC) for driving a semiconductor switch element (V11) provided in the fly back switching power supply is connected to a starter circuit (AS) for the voltage supply. This starter circuit (AS) is connected between two output terminals of a bridge rectifier (V1, V2, V3, V4) which provides a rectified and essentially unsmoothed mains AC voltage (UN), and an input terminal (6), as well as a reference potential terminal (4) of the control device (IC). The starter circuit (AS) has a resistive device (R) via which a capacitive device (C) connected in parallel on the output side can be charged by the rectified and essentially unsmoothed mains AC voltage (UN).

Magnetic deflection sweep amplifier with intelligent flyback

Abstract: The magnetic deflection sweep amplifier includes a first switch, such as a MOSFET in series with a deflection yoke. The switch is controlled by a second switch, such as a bipolar transistor, and the second switch is able to selectively control the first switch, whereby the yoke current can be reversed, to provide complete flyback, or can be truncated part way through flyback to stop the retrace at an intermediate position. The flyback amplifier also has provision for linear operation without flyback. The present invention accomplishes the foregoing with very few parts and with very little power consumption (Fig. 1).

Auxiliary-voltage source for supplying electric circuits which are at a high potential

Abstract: In an auxiliary-voltage DC source for supplying an electric circuit and, more particularly, one at a high potential in an electron gun without an isolation transformer, the primary winding of a current transformer is located in an alternating-current section of the electric circuit. The current transformer has at least one secondary winding which is connected through a rectifier to a parallel regulator for providing the auxiliary-voltage.

Auto range horizontal automatic phase control

Abstract: A circuit for phase locking the flyback pulse to a reference signal. A phase detector receives the flyback pulse (to be phase locked) and receives the reference signal. It outputs an error signal to a control circuit including first and second differential amplifiers having differing operational characteristics, one being linear in a narrower range than the other. The differential amplifier having the larger linearity range provides control signals to a coarse delay adjust circuit in the form of a programmable divider which also receives clock pulses at a high multiple of the horizontal frequency fH. The output of the coarse delay adjust circuit is applied to a fine delay adjust circuit responsively connected to the output of the first differential amplifier, which is linear over the narrower range. The output of the fine delay adjust circuit is coupled to the horizontal system. Large changes in the phase of the flyback signal are achieved by recognizing large deviations in the wider range differential amplifier and causing the coarse delay adjust circuit to make a relatively large adjustment in the phase of the output signals thereof. Thereafter, fine adjustments are made by the fine delay adjustment circuit in response to control signals from the narrower range differential amplifier.

Protecting circuit of dc/dc converter

Abstract: PURPOSE:To prevent the secondary damage due to a shortcircuit defect of a switching element by detecting the defect of a flyback voltage at the switching OFF time in the tertiary winding of a main transformer and suppressing a drive signal transmission of a drive circuit. CONSTITUTION:A variation in a magnetic flux of a main transformer T1a is detected by the tertiary winding w13, the output is rectified, inputted to a comparator 12, and compared with a reference voltage. The output of the comparator 12 and a negative signal of the drive signal from a drive circuit 11a are applied to an AND circuit AND to obtain logic product of both, the output is held by a latch circuit 13, supplied to the drive circuit 11a, thereby suppressing the transmission of the drive signal when a flyback voltage to be induced at the OFF time of switching transistors Q1, Q2 is defective.

Voltage regulator for pulsed voltage power supplies

Abstract: A voltage regulator for flyback-type high voltage supplies having a supplementary energy storage transformer with its secondary interconnected in series with the primary of the conventional flyback transformer, a control circuit for sensing (a) the generation of the conventional flyback pulse, (b) a reference voltage, and (c) a feedback voltage signal appearing at the output of the conventional flyback transformer and a switch for selectively applying energy to the primary of the supplemental energy storage transformer. The aforesaid switch being activated whenever the feedback voltage is less than the reference voltage and said switch being activated earlier in time as the aforesaid difference becomes greater. Just after the occurrence of the flyback pulse, the switch is opened to permit energy in the energy storage transformer to be placed on the primary of the flyback transformer so that it is added with the flyback pulse to maintain the resultant voltage at the output of the secondary conventional flyback transformer at a regulated value.

Cathode ray tube display horizontal deflection system with delay compensation

Abstract: The initiation of the flyback interval of a variable format CRT display system is controlled by a frequency independent closed loop compensation circuit. The termination point of a sawtooth pulse, which is initiated at the start of the horizontal sync for the CRT display system, determines the point for the initiation of the flyback interval. The termination point of the sawtooth is compared with the center of the flyback interval. So long as the flyback pulse is perfectly centered on the termination point, the timing is proper. However, if it is off-centered, circuitry results in delaying or advancing the turning off of the horizontal yoke driver to modify the initiation of the flyback interval in a manner to compensate for the change in delay.

Combined transformer set for electronic trip devices

Abstract: The described transformer set (1) contains a measurement transformer (5) for obtaining a current signal for tripping purposes, and a power transformer (6) for supplying an evaluation circuit and further auxiliary apparatuses which are required for tripping a power circuit breaker. The measurement transformer (5) has two partial windings (7 and 10) which are arranged on either side of a through-opening (3) through which, in the assembled state of the transformer set (1), a conductor (4) of the main current path of a power circuit breaker (8) extends. The winding (15) of the power transformer (6) is located on only one side of the through-opening (3) and is offset radially and axially with respect to the partial winding (10) of the measurement transformer (5) located on the same side of the through-opening (3). Connecting elements (16) for the various windings are arranged in a recess which remains on the side of the winding (15) of the power transformer (6). In particular, a space is provided there for a connecting plug (17) which contains a matching resistor (35) for the measurement transformer (5).

Methods and apparatus for supplying electrical power for proximity effect heat-tracing

Abstract: A proximity effect heat-tracing system in which proximity effect heat-tracing circuits are fed in either direction from a plurality of feed points connected to a single main transformer to increase the length of pipeline supplied by a single main transformer. A secondary transformer interposed between a main transformer and a plurality of feed points reduces the voltage required to be applied to a proximity effect heat-tracing system of a given length. Two or more proximity effect heat-tracing systems used along the same length of pipeline, employ neutral conductors having approximately the same diameter as "hot" conductors where the secondary of the main transformer in each system is 180° electrically out of phase with the secondary of the main transformer in the other system. A center-tap secondary in each subsidiary transformer is connected to a heat tube so that each proximity effect heat-tracing circuit is connected between an end of a secondary winding of a subsidiary transformer and a center tap of a secondary winding of a subsidiary transformer in order to minimize current in the transformers secondaries. Selection of the turns ratios of subsidiary transformer remote from the main transformer compensates for the voltage drop along a transmission line connecting the main transformer with subsidiary transformers.

Driving circuit for brushless motor

Abstract: PURPOSE:To suppress generation of flyback pulses to be generated by inductance of driving coils for a brushless motor by a method wherein capacitors are connected respectively between bases and collectors of transistors for energization of the respective driving coils of the brushless motor CONSTITUTION:The capacitors C1a-C1c connected respectively between the bases and the collectors of the transistors T3a-T3c make transferring time of the transistors T3a-T3c from ON to OFF to elongate by the what is called Miller effect when the transistors T3a-T3c transfer from ON to OFF, and mitigate variation of conducting currents of the driving coils MCa-MCc Resistors R2a-R2c are for the bypaths of currents intending to make the transistors T3a-T3c to ON flowing into the bases of the transistors T3a-T3c through the capacitors C1a-C1c, and resistors R1a-R1c are for protection of output circuits of voltage comparators CPa-CPc