Showing papers on "Flyback converter published in 1983"

A new zero-ripple switching DC-to-DC converter and integrated magnetics

Abstract: A new switching dc-to-dc converter is synthesized which consist of the least number of storage elements (inductive and capacitive) and switches, and yet truly emulates the ideally desired dc-to-dc transformer having both input and output currents as pure dc quantities with no ripple. This result was facilitated by implementation of a new concept termed integrated magnetics, which leads in some special switching structures to the integration of otherwise independent and separate magnetic components (inductors and transformers) into a single magnetic circuit.

Advances in Switched-Mode Power Conversion Part II

Abstract: A number of important practical extensions to the basic ?uk converter are presented. They include dc isolation, multiple-output power sources, and a physical realization of the sought for hypothetical dc-to-dc transformer, a device which converts from pure dc (no voltage or current ripple) at one terminal, to pure dc (at a different voltage) at the other terminal. The application of the circuit in a highly efficient amplifier for the servo control of a dc motor or other loads is also presented.

Electronic switching power supply

Abstract: An electronic switching power supply for supplying power to a load from an input voltage source, including a flyback converter with a transformer having its primary coil connected in series with the collector-emitter circuit of a first transistor in parallel arrangement with the input voltage source, while its secondary coil is connected in series with the load and a first diode, with the emitter of the first transistor being connected to chassis or reference potential through a first resistor while the base of the first transistor is connected to a control circuit (St), with a capacitor in parallel arrangement with the load, with the voltage across the junction (B) of the capacitor at the side remote from reference potential being of the same polarity as the voltage across the junction (A) of the first resistor and the first transistor. The power supply also includes a first circuit, including a second resistor, that is placed between the junction (A) of the first resistor (8) and the first transistor and the junction (B) of the capacitor at the side remote from reference potential, the first circuit serving to reduce a total effective resistance between the emitter of the first transistor and the reference or chassis potential when a voltage across said capacitor is below a predetermined value.

DC/AC Converter with voltage dependent timing circuit for discharge lamps

Abstract: A DC/AC converter provided with two transistors (11 and 20) alternately conductive to supply current to an inductively stabilized discharge lamp (16, 15) to be connected to the converter. The lamp is connected in series with a primary winding (12) of a current transformer. A secondary winding (30, 31) of the transformer is connected to a timing circuit (32 to 35; 32' to 35') of a control device of the transistors. The timing circuit is provided with voltage-dependent elements, i.e. Zener diodes (35, 35'). The combination of the current transformer and the Zener diodes causes the frequency of the converter, during starting of the lamp, to be larger than during the operating condition of the lamp. This insures that the lamp electrodes are properly heated before the lamp ignites.

Converter with lossless snubbing components

Abstract: The inverter includes a DC to AC converter circuit including a plurality of transistors which are switched on and off to convert a DC signal into an AC signal. The converter circuit also includes diodes which are alternately forward and reverse biased during the operation of the converter circuit, the diode having a reverse recovery period whenever the diode is switched from a forward to a reverse biased condition during which the reverse resistance of the diode is substantially zero. An inductor is connected to the diode for limiting the current through the diode during the reverse recovery period such that shoot through currents which pass through both the diode and the inductor are limited to desired levels.

Start-up transient control for a DC-to-DC converter powered by a current-limited source

Abstract: The start-up trajectory of the operating point of a DC-to-DC converter normally includes a high current locus which must be traversed to reach the steady-state operating point. In the case of a converter powered by a current-limited source, such as a power supply system where one converter powers a plurality of subsequent converters, the subsequent converters may be unable to turn on due to inadequate current drive. By using a control circuit adapted to control the start-up trajectory of a DC-to-DC converter as a continuous function of the input voltage applied to it by the current-limited source, the start-up characteristics are constrained to be compatible to both source and load permitting the converter to proceed to its steady-state operating point.

Power supply unit for electronic flash

Abstract: A power supply unit for electronic flash includes a converter drive circuit which is activated when a main switch is turned on or in response to the completion of a shutter operation or the completion of a film winding operation, thereby driving a converter for oscillation. The converter charges a main discharge capacitor to a given voltage, and when the given voltage is reached, the converter drive circuit is deactivated, thereby automatically ceasing the oscillation of the converter.

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.

Buck-boost converter with dual-mode control for battery charging

Abstract: A voltage controlled flyback converter used as a battery charging circuit avoids the power dissipation of the more conventional series-type regulator-type charging circuits but cannot be readily utilized because of the high gain in the feedback loop due to the battery voltage, which causes instabilities therein when it is operated in a continuous current mode. These instabilities are avoided in a flyback converter used for battery charging by using current control techniques to control current on the primary side of the converter during high-rate battery charging. During low-rate charging, normal voltage feedback from an output current sensing resistor is used as long as the converter operates in a discontinuous mode.

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).

Dc/ac converter for the ignition and the supply with alternating current of a gas and/or vapour discharge lamp

Abstract: PHN. 10.337 12 ABSTRACT: The invention relates to a DC/AC converter provided with two transistors (11 and 20), the current through an inductively stabilized discharge lamp (16, 15) to be connected to the converter alternately flow-ing through one and the other transistor According to the invention, the lamp (15) has connected in series with it a primary winding (12) of a current transformer, a secondary winding (30, 31) of this transformer being connected to a timing circuit (32 to 35; 32' to 35' ) of a control device of the transistors. The timing circuit is provided with voltage-dependent elements, i.e. Zener diodes (35, 35') The combination of the current trans-former and the Zener diodes causes the frequency of the converter during starting of the lamp (15) to be larger than during the operating condition of this lamp. As a result, it is avoided that this lamp ignites at too cold electrodes.

Apparatus for the current supply of a subscriber set from an exchange.

Abstract: An apparatus for applying current to a subscriber line telephone set (RL) with associated two-wire line connected to a telephone exchange. The apparatus includes two analogue amplifiers (5, 6) each with its output connected to one of the two wires of the line, and feeding out on the line the combined DC current and current representing the speech signal. A DC/DC converter supplies voltage to a at least one of the amplifiers. To form a control voltage to the DC/DC converter, a cascade connection of a differential amplifier (1), a lowpass filter (2) and an adding circuit (3) are arranged between the line connection terminals and the control signal input of the DC/DC converter.

Circuit arrangement for A/D and/or D/A conversion with nonlinear D/A conversion

Abstract: In an analog-to-digital (A/D) converter or a digital-to-analog (D/A) converter, a nonlinear D/A converter is employed. The nonlinear D/A converter comprises an absolute value circuit, a D/A converter, and another D/A converter having a function of multiplication. The latter D/A converter is responsive to a digital signal and to an analog signal from the former D/A converter so as to produce an analog signal indicative of the square of the digital signal. In an A/D converter, the nonlinear D/A converter is put in a negative feedback loop following an output of a successive approximation register so as to produce a reference signal with which an input analog signal to be converted will be compared by a comparator. The invention enables A/D conversion of a wide dynamic range signal by using a small number of bits, while quantization noise with respect to a low level signal is maintained low.

Self-oscillating inverter including a DC to DC converter and method for control thereof

Abstract: A self oscillating inverter including a DC to DC converter and method for control thereof which senses the onset of a transformer core saturation to control its operation without dependence thereon. Linearizing inductors in the transformer secondary function to maintain a ramp shaped collector current waveform under full load conditions to allow control of output voltage by varying the oscillator frequency.

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.

Synchronously detected DC/DC converter for regulated power supply

Abstract: A regulated power supply has a synchronous detector in a voltage regulator feedback loop. The detector is coupled to a secondary of a transformer to detect the AC voltage. The result is faster response time to a step change in the primary voltage and all DC output voltages are constant.

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.

DC Static switch with phase commutation

Abstract: An apparatus for the interruption of DC transmission lines without substantial arcing utilizing in combination a DC circuit breaker, a DC-to-AC current converter, converter control and an AC power sink. Upon command from the converter control, DC current is converted to AC current in the current converter and is then magnetically coupled via a transformer into the AC power sink; thus, drawing power out of the DC transmission line and reducing the DC current toward a zero value at which point the DC breaker can be opened without substantial arcing. Various single and multi-phase converter circuits utilizing thyristors are employed. A bypass switch in parallel with the converter can be provided to pass the DC current around the converter during normal operation of the DC transmission line to minimize electrical losses. Alternatively in multi-phase converters, normal DC current can be multiplexed among the phases of the current converter in order to distribute the heating caused by the conduction of DC current therethrough. Interruption of DC transmission lines having bidirectional DC current flow is accomplished with alternate embodiments of the invention including current converters in a back-to-back parallel arrangement, or a current converter full wave bridge rectifier combination or a current converter connected to the DC transmission line via polarity reversing switches.

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).

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.

Switched-mode power supply

Abstract: The invention relates to a switched-mode power supply having a storage capacitor and having a storage inductance. It is based on the principle of the flyback converter with a variable clock sequence (pulse sequence). The parallel circuit comprising a suitably dimensioned series-resonant circuit and the semiconductor switch or the storage inductance makes it possible for the semiconductor switch to be opened at a time at which both the current flowing through it and its instantaneous rate of rise assume the value zero. Transistors and, without additional self-commutated circuits, thyristors can also be used as the semiconductor switches. In conjunction with a tuned-circuit monitoring circuit, a control circuit (regulating circuit) changes the semiconductor switch into the conductive state when required. If a transistor is used as a semiconductor switch, a protection circuit ensures that the base current or the gate voltage is not disconnected until the current minimum is reached. The replacement of the storage inductance and the series-resonant circuit inductance by a suitable transformer allows potential isolation of the input and output voltages.

Characteristics of superconducting magnetic energy storage (SMES) energized by a high-voltage SCR converter

Abstract: A small-scale Superconducting Magnetic Energy Storage(SMES) unit was constructed using small magnets and a high-voltage converter, and the characteristics of this unit were examined. The high output voltage of the converter makes it possible for even a small magnet to charge and discharge large power. Moreover, converter control provides adequate protection during quenching. AC and DC filters can be eliminated from the converter system, and ripple voltage does not harm the superconducting magnet. These features demonstrated the potential of an SMES unit as a power system stabilizer and a peak load power supply.

Single-ended DC converter

Abstract: The invention relates to a single-ended DC converter using the forward converter principle and having a current transformer and a flyback converter inductor, whose primary windings are connected in series. The transformation ratios of the current transformer and the flyback converter inductor are selected to be of equal magnitude. The rectifier elements on the secondary side are connected to the secondary windings of the current transformer and of the flyback converter inductor, and to one another, in such a manner that a continuous load current flows.

Flyback converter switched-mode power supply having an expanded control range

Abstract: The control range of a flyback converter switched-mode power supply is limited, inter alia, by the limiting resistor in the base circuit, which limiting resistor is provided to protect the power switching transistor, since the control current which is required for full switching-through is no longer reached when the supply voltage is below a specific threshold. According to the teaching of the invention, a significant expansion of the control range is achieved in such a manner that a constant-current source is connected in the base circuit of the power switching transistor instead of a fixed current-limiting resistor. The power switching transistor thus remains completely switched through, even at a very low supply voltage, down to the residual voltage of the constant-current source, which is in general designed as a transistor, that is to say down to a voltage drop of only a few tenths of a volt. At the same time, there is no risk whatsoever of current overloading in the base circuit at a very high supply voltage, because the constant-current source limits the control current even better than the otherwise normal fixed resistor.

Pulse pneumatic pressure converter

Abstract: PURPOSE: To obtain a pulse pneumatic pressure converter storing an output pneumatic pressure even at power failure with high service life by using a piezoelectric flapper for a pneumatic-electric transducer, dividing a power supply into two systems and backing up only the circuit relating to the piezoelectric element flapper. CONSTITUTION: An output voltage of a DC-DC converter 37 or a voltage of a battery 38 is inputted to a DC-DC converter 39, where the voltage is converted into around DC24V. the voltage V 2 is applied to an input electric circuit comprising an up-down counter 22, a D/A converter 23 and a comparator 24 or the like and a circuit element required minimum for holding an output pneumatic pressure such as a pneumatic-electric transducer 32 or the like. Since the voltage of the battery 38 is used as a backup power supply at power failure although no voltage is inputted to the converter 39 from the converter 37, the converter 39 generates the voltage V 2 . Thus, the piezoelectric element flapper 26 holds a potential corresponding to that at power failure and the output voltage is held to a value at power failure. COPYRIGHT: (C)1985,JPO&Japio