Showing papers on "Flyback transformer published in 1986"

Flat matrix transformer

Abstract: A flat matrix transformer or inductor is made of a plurality of interdependant magnetic circuits, arranged in a matrix, between and among which electrical conductors are interwired, the whole cooperating to behave as a transformer or inductor. The flat matrix transformer or inductor has several advantageous features, among them compact size, good heat dissipation and high current capability. A flat matrix transformer or inductor can be very flat indeed, nearly planar, and can be built using printed circuit board techniques. A flat matrix transformer can insure current sharing between parallel power sources, and/or between parallel loads. The flat matrix transformer can be configured to have a variable equivalent turns ratio.

Transformer Computer Design Aid for Higher Frequency Switching Power Supplies

Abstract: A transformer computer design aid is presented that was developed for use at switching frequencies above 100 kHz where the classical method of using the saturation constraint results in an over-heated transformer due to excessive core loss. Flux density is selected instead by an optimization procedure that minimizes total transformer losses. Key equations used in the design procedure are developed. Emphasis is placed on the algorithm used in the transformer design procedure.

Ac/dc power mosfet reversing h-drive system

Abstract: A power MOSFET reversing H-drive system having a first pair of N-channel and P-channel MOSFETs (Q1, Q2) connected in series with a load (LD1, LD2) to a power supply source (T 1) and a second like pair of N-channel and P-channel MOSFETs (Q3, Q4) connected in series with the load (LD1, LD2) to the source (T1), each pair having a resistance voltage divider (R1-R2, R5-R6) for providing the P-channel MOSFET (Q1, Q3) with a different voltage level gate signal from the logic level input signal by which the N-channel MOSFET (Q2, Q4) is gated, an overvoltage protector (Z1, Z2) allowing extension of the supply voltage (T1) range under which the system is operable, and the on-state resistances and the flyback current capability of the intrinsic diodes (ID1, ID4) being matched to the size of the load to be driven

Flyback power supply

Abstract: A flyback power supply is disclosed which includes a sample and hold feedback path. A pulse width modulation circuit provides control signals for a drive device that determines current excitation pulses for a primary winding of a transformer. A secondary winding of the transformer is connected to a rectifier circuit and provides a DC voltage signal at an output terminal. A selective feedback path is provided between the output terminal and a sense input terminal of the pulse width modulation circuit. The selective feedback path comprises a sample and hold circuit which provides for effectively coupling the output terminal to the sense input terminal at times during the storage of energy in the transformer, corresponding to an increase in transformer flux, and wherein at other times when the transformer flux is decreasing and energy is being transferred from the transformer to the rectifier circuit the feedback path effectively disconnects the output terminal from the sense input. The sample and hold circuit comprises a series pass transistor and a holding capacitor. The series pass transistor is selectively turned on and off in accordance with the control output signal of the pulse width modulation circuit that determines the primary winding current pulses.

High voltage measurement transformer for suspension from a high voltage switching apparatus

Abstract: The current converter or transformer component of a high voltage measurement transformer comprises a primary lead or conductor which is surrounded by secondary windings or optical conducting elements. The primary and secondary components of the current converter or transformer component are housed in a casing having an integrally formed entry duct for the secondary leads. The secondary components of the current converter or transformer component are surrounded by plastic or synthetic insulation material. This insulation material or insulation also surrounds a channel for the secondary leads extending completely through the entry duct. The primary lead or conductor is provided with connecting flanges at both ends for mechanically or electrically connecting the high voltage measurement transformer to a high voltage or high power circuit breaker or similar device. The high voltage measurement transformer is suspended from the circuit breaker by this connection such that no further support is necessary for the high voltage measurement transformer.

AC voltage regulator with split primary switching

Abstract: An apparatus for AC line voltage regulation has an input port for connection to an AC source, an output port for connection to a load, and a transformer assembly connected between the input and output ports The transformer assembly comprises a buck/boost winding and a primary winding wound about a common transformer core, and a switch arrangement for controlling the connection of the primary winding in circuit with the buck/boost winding The switch arrangement is controlled by switch actuators responsive to a voltage sensor assembly to connect the primary winding in either of two possible conditions when the voltage is outside predetermined limits The transformer assembly comprises either a step down transformer for reducing or bucking the output voltage or a step up transformer for boosting the output voltage according to the condition of the switch arrangement The primary may comprise separate windings controlled by the switching assembly for connection in different configurations

Transformer protection system

Abstract: In a transformer protection system, data of voltages and currents detected at individual terminals of a transformer connected to an electric power system are supplied to a computer. The computer computes driving point admittances or shunt admittances of the transformer on the basis of the voltage and current data and predetermined transfer admittances of the transformer and decides that an internal fault has occurred in the transformer when the values of the driving point admittances or shunt admittances deviate from pre-set reference values, thereby disconnecting the transformer from the electric power system.

Electrical power supplies

Abstract: A switched-mode power supply having a main output (O/P1) and one or more other outputs (0/P2, O/P3 and O/P4), wherein the outputs are regulated both by flyback control and forward control and wherein the power supply includes a transformer (T) having a primary winding, a main output winding (L2) and one or more other output windings (L3, L4 and L5), a primary converter (1) associated with the primary winding, a forward conversion circuit (S1, T, D2, D3, LH and C1) associated with the main output winding (L2) for supplying the main output (O/P1), one or more flyback conversion circuits associated with the other output winding or windings (L3, L4 and L5) for supplying the other output or outputs (O/P2, O/P3 and O/P4), a forward control circuit (4) connected to the forward conversion circuit and arranged to control the main output (O/P1) in response to a signal derived from one or more of the other outputs (O/P2, 0/P3 and 0/P4), and a flyback control circuit (2) connected to the primary converter (1) and arranged to control the other output or outputs (O/P2, O/P3 and O/P4) in response to a signal derived from the main output (O/P1). In an alternative arrangement, a further main output winding (L1) is provided in a flyback conversion circuit arranged to control the forward control circuit (4).

Power supply operable on varying inputs

Abstract: A power supply provides the stable DC voltages needed for a computer terminal from a wide range of line voltages and frequencies. The line is rectified and fed to a flyback transformer wherein primary current is controlled in duration for providing the desired energy transfer to the secondary winding. The outputs from the flyback transformer are rectified and filtered. A separate start-up circuit uses a transformer across the line voltage, and a positive coefficient resistor provides a time limit to allow the use of a small transformer even though the line voltage may be high. The start-up circuit must produce a minimum voltage for the switching transistor in the flyback arrangement to allow operation of the power supply, and the start-up transformer is disconnected from the circuit after operation to prevent electromagnetic interference within the terminal. The output from the power supply is used in the control of the switching transistor so that, once the start-up circuit has achieved the needed voltage level, the power supply can assist in maintaining the operation.

Circuit arrangement with differential transformer

Abstract: A circuit arrangement with a differential transformer is proposed, the transformer core (8) of which is used as a distance sensor. To eliminate temperature influences and other influences impairing the measurement result, it is provided that the aggregate voltage of the two secondary coils (4, 5) is kept constant by regulating the primary voltage (Up). This, at the same time, results in a linearisation of the distance signal.

Method for attenuating at least one electric harmonic of the system frequency in a multi-phase alternating-current system

Abstract: A method for attenuating at least one unwanted harmonic, particularly the second harmonic, with respect to the system frequency in a multi-phase alternating current system, wherein an additional stabilizing circuit is installed into a conventional current/voltage controller including a current/voltage controller and a three-phase firing pulse generator in a reactive-power compensator connected via a reactive-power transformer and a current transformer to a 50 Hz three-phase system. The reactive power compensator has for each phase of the three-phase current at least one air choke, which is connected via a current transformer and via an alternating-current switch via another sum-current transformer to a secondary winding of the reactive-power transformer. In addition, the reactive-power compensator has for each phase of the three-phase current at least one capacitor bank or a capacitor, which is connected via a current transformer and an alternating-current switch (13) to the sum-current transformer (20). The stabilizing circuit measures a harmonic-containing magnetising current as the difference between compensator current (iK) and sum current (iSu) on the primary and secondary side of the reactive-power transformer, and by means of a voltage transformer a system-frequency voltage signal, which is proportional to the system frequency. These two three-phase current and voltage signals are converted into a single direct-voltage signal in a reactive-power meter. An input harmonic of 100 Hz occurs on the output side as a 50 Hz signal which is filtered out in a bandpass filter and, after a +90° phase shift, is added in an adding section to the conventional output signal of the current/voltage controller via a double-sided limiter.

Power supply for a.c. corotrons

Abstract: A circuit for supplying power to the a.c. corotrons of copying or printing machines using a high leakage inductance type transformer both as a power transformer and as a low pass filter; a d.c. power source coupled to the transformer primary winding center tap; a push-pull amplifier having a MOSFET gate pair controlling energization of the transformer primary winding halves by the d.c. power source; a pulse width modulator for supplying alternating signal pulses to the MOSFET pair at a fixed frequency; a voltage doubler network for monitoring corotron current, the modulator adjusting the pulse width of the signal pulses in response to the network control signal to thereby adjust the power output of the circuit and maintain a constant corotron current; and a capacitor at the transformer output cooperable with the transformer to form said low pass filter.

In-line safing and arming apparatus

Abstract: An air driven electrical generator, carried by a weapon, supplies low voltage electrical energy to a storage capacitor which in turn supplies reoccurring constant amounts of electrical energy to the primary of a flyback transformer The secondary of the flyback transformer supplies relatively high voltage electrical energy to a slapper detonator capacitor

High voltage resonant DC/DC converter

Abstract: A high voltage DC/DC converter including a voltage resonance switching circuit formed by a coreless transformer, a GTO thyristor switching element connected between the primary winding of the transformer and a D.C. source, and a voltage resonance capacitor connected in parallel to the switching element. A rectifier circuit is connected to the secondary winding of the transformer to rectify an output current from the transformer circuit. The resonance frequency of the parallel resonance circuit made of the resonance capacitor and the coreless transformer is selected to be the frequency of that component of the current supplied to the circuit through the switching element, which has a greater amplitude than any other component of the current (including the fundamental frequency and other harmonic).

Ac current sensing circuit

Abstract: An alternating current sensing circuit for sensing the current supplied by a power supply of an electronic instrument includes an isolation transformer and at least one transistor connected across the secondary winding of the transformer. The isolation transformer provides galvanic isolation between the power supply and internal feedback circuitry that controls the power supply located within the instrument. The transistor clamps the secondary voltage on the transformer to a constant magnitude when the base-emitter junction is forward biased. In response to the sensed current, the secondary current of the transformer flows through the transistor when the base-emitter junction is forward biased to produce the constant secondary voltage. The secondary current provides a current sensing signal which is transmitted to the feedback circuitry. The low, constant secondary voltage enables the transformer to maintain its range of frequency response and thereby accurately transform the sensed current to a secondary current that provides the current sensing signal to the feedback circuitry.

Line output circuit for generating a line frequency sawtooth current.

Abstract: A line output circuit has a transistor (TR) whose collector is connected through the primary winding (P) of a transformer (T) to a direct voltage supply terminal (2), the secondary winding (S) of the transformer (T) being connected through a diode (D1) to a terminal (3) at which an EHT supply appears. A diode (D2) shunts the collector-emitter path of transistor (TR) to provide a path for negative going sawtooth current. Two serially connected flyback capacitors (Cf1, Cf2) also shunt the transistor (TR), one capacitor (Cf2) being shunted by a switch (S1). The series arrangement of a linearity correction inductor (Ll), a deflection coil (Ly), a further inductor (L2) and a trace capacitor (Ct1) also shunt the transistor (TR), the inductor (L2) and trace capacitor (Ct1) also being shunted by the series arrangement of a further trace capacitor (Ct2), a linearity correction resistor (R) and a switch (S2). With the switches (S1, S2) in the condition as shown the circuit operates at a high line frequency but in the conditions opposite to that shown, the circuit operates at a lower line frequency, with subsequent change to line drive pulses applied to a terminal (2). The values of the circuit components are chosen such that the ratio of the flyback period to the line period of the sawtooth current generated is the same at both line frequencies whilst the supply voltage to the deflection coil (Ly) is in part present across the inductor (L2) at the lower frequency to ensure the same scan current at both frequencies. This ensures that with the same supply voltage at terminal (2) the EHT supply voltage and the magnitude of the deflection current through the deflection coil (Ly) are the same at both line frequencies.

Current transformer circuit tester

Abstract: Apparatus for determining the size adequacy of a current transformer in an electrical power distribution system. The apparatus includes a voltage generating source for connection in series with a current transformer secondary circuit, which source saturates the current transformer. A first signal is provided which is indicative of the voltage required to cause the current transformer to enter saturation. A second signal is provided which is indicative of the resistance of the secondary circuit of the current transformer after saturation. A third signal is then provided which is responsive to the product of the second signal and predetermined constant value. A ratio of the first to the third signals which exceeds unity indicates adequacy of the current transformer for a given system.

Scanning CRT control system

Abstract: A scanning CRT control system is disclosed in which horizontal sync pulses are used to develop a pulse signal that provides an input to a transformer circuit also receiving a relatively low DC power supply input signal. The transformer circuit develops a very high DC voltage connected to a CRT screen while also providing a relatively lower voltage power supply signal that is utilized to develop the power supply signal provided to a video driver that controls beam excitation for the CRT. A compensation circuit is provided between the transformer circuit and a power supply terminal of the video driver such that a compensating signal is provided at the transformer circuit in accordance with each horizontal video scan line. The compensating signal has a frequency corresponding to the horizontal sweep frequency and a magnitude that varies in accordance with the average current loading of each individual horizontal scan line. In this manner the compensating signal will cause a variation in horizontal beam positioning so as to maintain horizontal orientation between different sequential horizontal scan lines regardless of the average beam current intensity of each of the horizontal scan lines. Preferably, the compensation circuit comprises a parallel resistor and capacitor connected in series between an output terminal of the transformer and the power supply terminal of the video driver.

Low-noise transformer

Abstract: A low-noise transformer, particularly for the use as an output transformer of an inverter, comprising a sound-proof envelope surrounding at least one of the windings for absorbing or screening noise originating from vibration due to electromagnetic force.

Flyback transformer circuit with a noise cancelling circuit

Abstract: In a flyback transformer circuit for a cathode-ray tube of the type arranged such that secondary windings of the flyback transformer are isolated from an a.c. power source, a positive terminal of at least one secondary winding of the flyback transformer is connected via a capacitor or a series circuit of a capacitor and a parallel circuit of a resistor and a coil to a terminal which is coupled with the commercial a.c. power source via low impedance in connection with high frequency. With the provision of the capacitor or the series circuit including the capacitor, the potential at the positive terminal of the secondary winding is made equal to that at the commercial a.c. power source in connection with high frequency components, and thus the flyback pulse appearing at the positive terminal of the secondary winding has the same polarity and substantially the same peak value as that appearing at the above-mentioned terminal. As a result noise caused from flyback pulses is effectively prevented from entering the ground line or earth to avoid undesirable phenomena caused from such noise.

Regulated voltage converter which has substantially fewer parts than prior art devices

Abstract: An improved switching power source in which the output of the DC input power source is switched off and on under control of switching elements of an oscillating drive circuit which is supplied to the primary side of a power source transformer and from which a constant voltage output is supplied from the secondary of the transformer. A saturable reactor transformer supplies an input to the control terminals of the switching elements of the oscillating drive circuit and the inductance of the saturable reactor transformer is controlled with the output voltage from the secondary of the power source transformer so as to control the oscillating frequency of the oscillating drive circuit and, thus, stabilize the output voltage at the secondary of the power source transformer so as to obtain an increased conversion efficiency, reduce the size and weight of the transformer, reduce the leakage flux, improve the control range and reduce the cost of production.

Linearity correction circuit

Abstract: A linearity correction circuit for high speed horizontal scanning is disclosed. The correction circuit uses high speed, fast recovery components capable of operating in the fifty to one hundred kilohertz range. A variable inductor is tapped directly to the flyback transformer, the variable nature of the inductor giving a range of correction for linearity. The inductor is connected to a capacitor and a damper diode with a diode so that the voltage built up across the capacitor, which is connected to the deflection coil, causes the damper diode to conduct early, thus correcting linearity of the circuit. Using a minimum number of components a highly efficient circuit is provided both in operation and cost of construction.

Voltage Jump at Transformer Terminals Due to Non-Simultaneous Switching

Abstract: This paper gives an analytical explanation of a voltage jump phenomenon noticed at the transformer terminal. In particular, it is proven that as a consequence of certain non-synchronous switching conditions, the voltage of the last disconnected transformer terminal will suddenly increase. Overvoltages as a consequence of non-synchronous switching are calculated and compared with measured voltage waveforms.

Circuit arrangement for the realization of a stand-by working mode in a flyback switching power supply

Abstract: In a flyback switching power supply of the transformants has formator (Tr) is a fixed manner to the primary winding (Wp) and loose with one of the power supply of the normal load (RL) of an el ektrischen device serving Sekundwarwicklung (WI) coupled winding (W3) for generating a control signal for the standby load supply.

Television receiver load compensation circuit

Abstract: A deflection circuit is coupled to a horizontal deflection winding for generating scanning current in the winding. A retrace pulse voltage is developed across the deflection winding during the retrace interval. A flyback transformer is coupled to the deflection circuit and has retraced pulse voltages developed across windings thereof. A source of supply energy is coupled to a first winding of the flyback transformer and a load circuit, such as a high power audio circuit, is coupled to a second winding of the transformer and draws load current therefrom. A switched mode power supply is coupled to the source of supply energy and to the flyback transformer for controlling the transfer of energy between the source and the load circuit. A compensation circuit responsive to the operation of the switched mode power supply produces variations in current in an inductance coupled to the flyback transformer. These variations are indicative of variations in load current drawn by the load circuit. The flyback transformer couples the inductance to the retrace resonant circuit for a variable amount of time during retrace to control the transformer trace-retrace duty cycle in a manner that compensates for retrace time modulation due to loading variations.

Transient voltage protection for toroidal transformer

Abstract: An apparatus and method for protecting a toroidal transformer from damage due to voltage oscillations and dielectric stresses caused by applied voltage transients is disclosed. Two conductive sheilds are each electrically coupled to a line lead of the primary windings of the toroidal transformer and are disposed around and insulated from the periphery of one semitoroidal segment of the primary windings. A conductive grounding plate is strapped to the outside of the transformer adjacent to and insulated from each conductive shield.

Field effect transistor drive circuit

Abstract: PURPOSE:To obtain an FET drive circuit with high efficiency, light weight and small size and mis-operation by connecting a 3-terminal switch element between a gate and source of the FET and discharging an electric charge stored in an input capacitor of the FET through the element. CONSTITUTION:When the switch element Q2 is turned on by a drive pulse from a signal source 1, a voltage produce in a winding N2 of a transformer T1 is applied between a gate G and a source S of an FETQ1 through a diode D3. As a result, a gate current flows and an input capacitor Cin is charged and the FET Q1 is turned on. When the element Q2 is turned off, a flyback voltage of the winding N2 is subject to discharge operation through a resistor R3 and a diode D2, a potential difference between a point B of the D3 and a point A of the D3 by the charged charge of the Cin is caused, a current flows to a bias circuit 3 by the potential difference and a 3-terminal switch element Q3 is conducted. The electric charge in the Cin is discharged through the element Q3 by the conduction. Thus, the switching speed is quickened and high efficiency is attained.

CRT horizontal deflection circuit enabling horizontal sweep width adjustment with stabilized EHT output

Abstract: A horizontal deflection circuit for performing horizontal sweep operation of a CRT includes a saturable reactor having controlled windings connected through the primary winding of a flyback transformer to the CRT horizontal deflection coil, to supply deflection current thereto from a voltage supply produced from a voltage control circuit The level of this supply voltage is controlled by feedback operation in accordance with the amplitude of pulses produced from an output winding of the flyback transformer such as to maintain this pulse amplitude at a fixed value, and hence maintain an EHT voltage derived from pulses from a secondary winding of the transformer at a fixed value These fixed values are held constant when a DC current passed through the reactor control winding is varied to adjust the inductance of the controlled windings, and thereby adjust the horizontal sweep width produced on the CRT screen

High voltage stabilizing circuit

Abstract: PURPOSE:To increase the response speed of control while a stable action is maintained with a high voltage stabilizing circuit, by reducing the capacity of a reverse current absorbing capacitor down to such a level where the terminal voltage of the capacitor does not exceed the base voltage level of a control transistor. CONSTITUTION:A high voltage output current flows through a voltage output terminal 7 and the high output voltage level is reduced. Thus the base voltage level of a transistor TR10 is reduced and therefore the emitter current of the TR10 is reduced. Thus the base voltage level of an error amplifying differential TR12'' is reduced and the collector current of a TR12' increases. Then the base voltage level of a control TR15' is reduced to increase the collector voltage level. This increases the high output voltage level at the secondary side of a flyback transformer 5. In this case, a common emitter type TR15' is used. At the same time, the capacity of a reverse current absorbing capacitor 14 is reduced down to such a level where the terminal voltage of the capacitor 14 does not exceed the base voltage level of the TR15'. Thus the response speed of control is increased.