Showing papers on "Forward 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.

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.

Method of digital temperature compensation and a digital data handling system utilizing the same

Abstract: A method of digital temperature compensation uses a digital temperature compensation word to produce a digital word modification of a digital input to a temperature sensitive digital to analog converter hereinafter converter. The method includes the steps of sensing the temperature affecting the converter to produce a digital temperature representation which is used by a digital computer to produce an output in accordance with a characterization equation in the form of Output=f(D, M) where D=digital data and M=f(temperature). The temperature stability of the converter is affected by the temperature stability of a reference voltage circuit used in the converter and having a voltage reference diode. A compensation circuit uses a temperature sensor in the form of a second diode, which is thermally coupled to the reference diode, and a tracking type analog-to-digital converter for converting an analog signal. The output of the analog-to-digital converter is supplied as a digital word to a digital computer system which uses the digital word to modify a digital input to the converter. The computer system includes a non-volatile memory in which is stored a characterization equation which describes the performance of the converter as a function of the digital output signal from the computer and the digital representation of temperature from the analog-to-digital converter. Thus, the output from the digital-to-analog converter is compensated for the effect of temperature on the converter.

New magnetic structures for switching converters

Abstract: In the past the majority of power processing applications have been centered around a very few standard switching converter topologies. Recently, a number of new converter topologies have been proposed in order to find the best possible electrical inter connection of power processing elements: switches, storage components, and transformers, that would yield the highest efficiency and best performance. However the equally important and complementary problem of their best magnetic interconnection has been completely overlooked. In some new converter structures, the nature of the switching process and existing waveforms allows integration of previously separate inductors and transformers into a single magnetic structure. Several such magnetic core structures are proposed and analyzed, which lead to further converter simplifications and performance improvements.

Single transistor forward converter with lossless magnetic core reset and snubber network

Abstract: A switching isolated single transistor forward converter which performs demagnetization and snubbing functions with the same network The transformer stored energy and the energy stored during snubbing are transferred to the load by the network during the dead time of the switching cycle

Reactive-power compensation

Abstract: For reactive-power compensation in hydroelectric generators (1), a loss reduction is achieved by connecting a fixed compensation circuit (6) to the secondary side of a mains transformer (5, 5'), which is connected via a converter (4, 7) to the generator (1) and is switchable in steps on the converter side, and the converter is adjustable over a wide voltage range.

Multi-phase DC-to-AC and DC-to-DC boost converter

Abstract: A multi-phase DC-to-AC voltage boosting converter suitable for use as the primary stage of power isolated, high output voltage DC-to-DC voltage converters. The converter is comprised of a plurality of transformer primary windings electrically interconnected in a single loop mesh configuration and a plurality of voltage boosting channels operatively associated with the respective primary windings and commonly connected to a low voltage power source. The phase channels are operated so as to periodically provide a boosted voltage potential to the primary windings in a continuously cycling, multi-phase synchronous relation to one another so that a corresponding multi-phase, high-voltage AC potential is provided across each of said primary windings. Various conventional AC-to-DC converters and voltage multiplier circuits may be inductively coupled to the transformer primary windings to provide a wide variety of highly efficient low-to-high voltage DC-to-DC boost converters.

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.

A water-level sensor using a capacitance to frequency converter

Abstract: A capacitive water-level sensor using PTFE-insulated wire and a capacitance to frequency converter is described. Construction is simple, yet overall linearity is 0.1%. Temperature drift of the sensor is -0.05%K-1 and that of the converter is <0.01%K-1. Long-term stability of the sensor appears excellent. The converter draws only 150 mu A from a 5 V supply and is insensitive to supply voltage variations.

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.

Modelling and Analysis of Cuk Converter Using Current Injected Equivalent Circuit Approach

Abstract: The current-injected equivalent-circuit approach has been developed for modelling and analysis of switching dc-dc converters and is very versatile. This approach can also be applied for modelling and analysis of complex converters or cascaded converters. To demonstrate the ability of the current-injected equivalent-circuit approach, the modelling and analysis of a Cuk converter is carried out. A small signal equivalent-circuit model is obtained which represents both input and output properties of the nonlinear converter. The results are presented in the form of linear equivalent-circuit models, as well as transfer functions.

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.

High frequency x-ray generator power supply

Abstract: A resonant dc-dc converter employing power transistors as the switching elements generates a high dc output voltage (150 kilovolts) to drive an x-ray tube. The converter is configured such that the resonating circuit elements can be realized using the transformer parasitic elements. Voltage step up is achieved due to the transformer turns ratio as well as the resonant rise of voltage across the energy storage elements of a series resonant circuit.

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).

Control arrangement for a static converter

Abstract: A control arrangement for a static converter of the type which supplies a DC machine. A pilot signal is produced, the pilot signal being responsive to the actual speed value and the desired current value of the DC machine. The pilot signal is then combined with a control signal of the converter so as to improve the dynamic characteristic of the control arrangement.

Electrical power source for resistance welding apparatus

Abstract: An electrical energy source with a static inverter and a welding transformer (12) for a resistance welding machine comprises a first static frequency converter (10) made up of semiconductor elements, the alternating output voltage of which has a frequency and pulse shape which differ from the frequency and pulse shape of the supply voltage fed to the inverter. In this connection, the pulse shape, the amplitude, and the pulse to space ratio are to be variable within wide limits. This is attained by at least one second frequency converter (11) connected in parallel to the first frequency converter (10), wherein the alternating output voltage of the second frequency converter (11) is adapted to be added in phase synchronism to the alternating output voltage of the first frequency converter (10) in the primary circuit of the welding transformer (12).

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.

D.C. voltage converter including a pulse width controlled semiconductor switch

Abstract: A d.c. voltage converter having alternating energy intake and energy discharge phases. The converter includes a power transformer having a core and at least primary, secondary and tertiary windings associated with the core. A primary circuit including a pulse width controlled semiconductor switch connected in series with the primary winding conducts an energy intake current during the energy intake phase of the converter. A secondary circuit including a smoothing capacitor and at least one rectifier element connecting the smoothing capacitor to the secondary winding conducts an energy discharge current during the energy discharge phase on the converter. Circuit means are provided for connecting the tertiary winding to the smoothing capacitor so that, following the energy discharge phase of the converter, excess energy of the smoothing capacitor in the form of an energy feedback current is fed back into the core until the start of the next energy intake phase of the converter.

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.

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.

Filter circuit for digital-to-analog converter

Abstract: A filter circuit smooths the output signal of a digital-to-analog converter by providing linear ramps between adjacent steps of the signal. The circuit measures the voltage difference between two adjacent step levels, amplifies the difference voltage by a predetermined gain, 10 in the present example, then applies the amplified signal to an integrating network having a time constant which is determined by the amplifier gain and the sampling time of the D/A converter. The integrator output signal is summed over the sample period with the converter output signal level of the next preceding sample time period, thereby providing a waveform which has substantially linear transitions between adjacent D/A output levels.

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.

Charge control device in a flash device for a camera

Abstract: A flash device for photography includes a DC/DC converter for boosting a DC power source voltage and applying a voltage to a main capacitor for supplying an energy for driving a flashlight tube. The converter has control means operative in response to the trigger operation by a start operating switch to detect any reduction in the charging current of the main capacitor and stop said operation. The flash device is provided with another switch means for enabling the operation of the converter independently of the start operating switch. Said another switch means is operative to operate the converter until the charging voltage of the main capacitor reaches a sufficient value to drive the flashlight tube.

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.

Static phase converter

Abstract: Single-speed, three-phase motors and two-speed, three-phase motors are started and run by a static phase converter which comprises a timing circuit, adjustable for a starting interval, and a switching device which configures a plurality of capacitors, with respect to motor windings, so that a starting capacitance and a running capacitance are connected during a starting mode for a high-torque condition, and, thereafter, the run capacitance is connected for running the motor.