Showing papers on "Forward converter published in 1982"

Forward converter switching at zero current.

Abstract: In a forward DC to DC converter (Fig. 4), switching losses are virtually eliminated by exploiting a controlled amount of leakage inductance of a transformer (10) in combination with a capacitor (15) to allow a switch (12) to turn on and off essentially at zero current. The combination of the secondary leakage inductance of the transformer (10) and the capacitor (15) defines an effective LC circuit having a characteristic time scale for the rise and fall of the current drawn from a voltage source (11). Power is converted by cyclically transferring a quantum of energy from the voltage source (11) to a current sink (load) via the effective LC circuit. The sink current is cyclically carried by a rectifier (16) which prevents the LC circuit from becoming a resonant circuit and leads to a unidirectional flow of energy from source to load.

A Regulated DC-DC Voltage Source Converter Using a High Frequency Link

Abstract: Power converters which employ a high frequency (HF) link possess several attractive features such as reduced size of reactive components, fast response, and ease of commutation. Either series or parallel connection of the load to the link capacitor can be employed by such converters. Converters that have a series link capacitor-load configuration are seen by the load as a current source. A dc-dc converter which uses a parallel link capacitor-load configuration is investigated. The output dc voltage is regulated by varying the link frequency. Such a converter behaves as a voltage source and is suitable for voltage source inverter applications. The converter is analyzed. Based on the analysis, a design procedure is given. A control scheme is outlined. Results from a prototype converter are presented.

Regulated dc-dc converter using a resonating transformer

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.

Modeling the Full-Bridge Series-Resonant Power Converter

Abstract: A steady state model is derived for the full-bridge series-resonant power converter. Normalized parametric curves for various currents and voltages are then plotted versus the triggering angle of the switching devices. The calculations are compared with experimental measurements made on a 50 kHz converter and a discussion of certain operating problems is presented.

Supply for providing uninterruptible d-c power to a load

Abstract: A system for supplying uninterruptible d-c power to a load. When the system operates in its normal mode, d-c load power is provided by the combination of a rectifier and a power switch. The d-c output of the rectifier may be used by a d-c to d-c down converter to recharge and maintain a battery if a separately powered source is not available for that purpose. A d-c to d-c up converter provides a relatively high amplitude d-c voltage from the battery voltage. The amplitude of this voltage is lower than the amplitude of the d-c output of the rectifier in the normal mode. When the amplitude of the rectifier output falls below the d-c to d-c up converter output voltage, the system changes to its failure mode and the battery provides d-c power to the load. The operation of the down converter if it is included in the system is inhibited.

Cascade-comparator A/D converter

Abstract: In an A/D converter in which a first comparator A/D converter for providing the most significant bits of a digital output and a second comparator A/D converter for providing the least significant bits of the digital output are cascaded, a switching circuit is provided between the first A/D converter and the second AID converter This switching circuit is responsive to the comparison between an analog input voltage and first comparison reference voltages in the first AID converter to apply two adjacent first reference voltages between which the analog input voltages lies to both ends of a voltage dividing circuit network of the second A/D converter to thereby provide second comparison reference voltages In the second A/D converter, the second comparison reference voltages are compared with the analog input voltage by comparators, to provide the least significant bits of a digital output

A dual mode forward/flyback converter

Abstract: This paper presents a single transistor dc-dc converter that combines both forward and flyback action. The resulting circuit is ohmically isolated and can operate over a wide range of input-to-output voltage ratios. An analysis of the circuit indicates that the forward and flyback portions of the circuit interact to produce three distinct regions of operation. With the design information presented, the circuit can be tailored to utilize the desirable characteristics of either converter action for a specific application. The dynamics of the dual mode circuit are modeled by means of the state-space averaging technique. An ac-dc regulator that takes advantage of the wide operating range of the dual mode circuit operating off the ac line, with only a small input filter, is described.

DC to DC switching regulator with temperature compensated isolated feedback circuitry

Abstract: A DC to DC switching regulator includes a first pulse width modulator (PWM) (26) and two switching transistors (48) and (50) that are coupled to a transformer (18) to generate an output signal that has pulse widths variable in response to the PWM (26). The output of the transformer (18) is rectified to provide a regulated DC output. A second PWM (78) is provided to convert the amplitude of the regulated DC output to a stream of pulses that are input to an isolation transformer (112) by a push-pull arrangement of transistors (118) and (120). The pulse width of the pulses input to the isolation transformer (112) is variable as a function of the level of the regulated DC and the amplitude thereof is a constant referenced to the internal reference of the PWM (78). The output of the isolation transformer (112) is rectified and filtered to provide an error signal that varies in response to the pulse width of the output pulses from the PWM (78). The constant amplitude, variable width pulses output by the PWM (78) provides a signal that does not vary in response to noise on the regulated DC output and the error signal derived therefrom is input to the PWM (26) to vary the pulse width thereof to maintain regulation on the regulated DC output.

DC Light dimmer control system

Abstract: A light dimmer control system for controlling the current supplied from a DC power source to high power illuminating lamps. The current fed to the lamp is controlled by manually setting the width of the pulsed output of a pulse width modulator by means of a potentiometer or the like appropriately connected to the pulse width modulator. The output of the pulse width modulator drives an output driver circuit which is connected in series with the current path to the lamp. The lamp power is provided from a DC source which is controlled by the output driver circuit in series with the lamp. The power for the semiconductor components of the DC controller, which includes the pulse width modulator, is provided from the same DC source and stepped down by a DC-DC converter. A logical control circuit is employed which enables the energization of the system only when both the polarity of the DC input supply is correct and the low voltage DC is on, thereby minimizing the possibility of damaging system components.

Converter control apparatus for parallel connected multi-terminal direct current system

Abstract: Two rectifiers and two inverters are operated under the state under which they are connected in parallel by common transmission lines. These rectifiers and inverters are controlled an independent control apparatus respectively which can selectively apply either the constant current control or the constant voltage control. The control apparatus of each converter has bestowed thereon the reference value of a current to flow through the particular converter and the reference value of a terminal voltage of the particular converter. A signal for lowering the current reference value is added to the control apparatus of one or all of the converters which are to be operated as the inverters. On the other hand, a signal for essentially rendering the terminal voltage of the converter smaller than the voltage reference value is added to the control apparatus of the converter which is to be operated as the converter for determining the voltage of a direct current system.

Microprocessor supervised analog-to-digital converter

Abstract: An analog-to-digital converter which is supervised by a microprocessor and includes means for digitally compensating for initial gain and offset errors and gain and offset drift errors due to temperature variations. An analog input voltage is applied to a first analog-to-digital converter, the output of which is both stored in the microprocessor and applied to a linear digital-to-analog converter. The output of the linear converter is summed with the original analog input voltage and the difference applied to the conversion apparatus as an unknown input signal. This process is continued to achieve a desired resolution. The output of a differential temperature sensor is similarly processed to determine the proper amount of compensation for gain and offset drift. The microprocessor provides both control and computation capabilities.

Current limiter for a load commutated inverter

Abstract: A current limiter for a load commutated inverter-synchronous motor drive including a source side AC to DC converter (12) and a load side DC to AC converter (14) coupled via a DC link circuit including an inductor (16) wherein a torque reference signal (TORQUE REF) generated for controlling both the converters is limited in response to the peak value ψ MAX of the pseudo flux waveform (ψ ab , ψ bc , ψ ca ) which is derived from the integral (∫) of the motor terminal voltage (v ab , v bc , v ca ) in order to limit the motor stator current I s to a value corresponding to the region of peak output torque T MAX obtainable for the motor field current I f applied. Control of both the source side converter (12) and the load side converter (14) by the torque reference signal operates to control the magnitude of the current I L in a DC link circuit which corresponds to the motor stator current I s as well as the frequency of the AC power applied to the motor.

Power converter symmetry correction circuit

Abstract: A pulse width modulated power converter having a single time multiplexed symmetry correction circuit operative to vary the pulse width of output drive pulses applied to an output transformer. As a result, the average current and thus the volt second product seen by each half of the transformer primary winding will be equal under steady state conditions. The transformer drive remains balanced over the entire dynamic range to prevent unwanted saturation of the transformer core.

Fluorescent lamp safety lighting

Abstract: 1. Fluorescent-lamp-type safety light, in which the fluorescent lamp, in normal operation, can be operated via a bridge rectifier (6) which is followed by a supporting capacitor (8) and a DC/AC converter (9) from an alternating-voltage supply system (L', N) and, in emergency operation, can be operated via a DC/AC converter (9) from a battery (3) and the battery can be charged by means of a charging device (1) from the alternating voltage supply system (L, N), characterised by the following features : - the alternating-voltage side of the bridge rectifier (6) is connected via a filter (7) to the alternating-voltage supply system (L', N), - the direct-voltage side of the bridge rectifier (6) is connected to the supporting capacitor (8), to the input of the DC/AC converter (9) and, via a blocking diode (5), to the output of a direct-current converter (4), - the input of the direct-current converter (4) is connected to the battery (3).

High voltage converter

Abstract: A high voltage converter converts an incoming high frequency pulse voltage to a direct voltage at a level which can be varied by varying the pulse width. The converter contains a transformer (T) with its primary side (p) connected to a pulse source (U) and to a controllable switch (K). The secondary side of the transformer is divided into two sections (s 1 , s 2 ). One section (s 1 ) is connected to a rectifier in the form of a conventional voltage doubler circuit (D1, D2, Cd1, Cd2) with capacitors in parallel with the secondary winding sections (s 1 , s 2 ). The other section (s 2 ) is connected to a rectifier bridge (D3-D6) and a smoothing filer (L f , C f ). The converter output is the doubler circuit output in series with the smoothing filter output.

Power indicator apparatus for a DC to DC flyback converter

Abstract: A battery power indicator for a DC to DC flyback converter is responsive to the current flowing in the secondary winding of the converter's transformer. In one embodiment the power indicator is lighted when the battery is weak but not dead. If the battery is good, the indicator is bypassed and remains off. In a second embodiment, the indicator is lighted to indicate a good battery and when the power capability of the battery drops below a predetermined level, the indicator turns off.

Emergency AC power unit - has voltage regulator which stabilises voltage using pulse-width modulation and battery voltage regulator (SE 5.4.82)

Abstract: In the emergency power unit for an alternating current load (1), there are connections for an AC generator (10) and a battery (5), which can be charged by rectified current from the generator and a controllable bidirectional converter (6) between the battery and the load. An alternating voltage regulator (13) stabilises the voltage on the AC side (3) of the converter (6) by means of pulse-width modulation, and a battery of voltage regulator (12) operating by phase-shifting on the AC side of the converter (6). The generator (10) can be connected in parallel to the AC side of the converter and a current-limiting device (8) is located between the AC side of the converter (6) and the generator. In order to provide metallic isolation between the converter and the generator, and between the load (1) and the generator, the current-limiting device (8) may be a leakage reactance transformer which has three windings. The leakage-reactance transformer effects not only metallic isolation, but at the same time effects the required current limitation as a consequence of its leakage inductance.

A four-quadrant current regulated converter with a high-frequency link

Abstract: A novel and highly versatile four-quadrant static converter is discussed. A resonant high frequency link is employed which provides an extremely fast response to external commands and a wide frequency range of converter operations. This converter is therefore very suitable for four-quadrant DC chopper and constant or variable frequency inverter applications.

Characteristics of a New Series Resonant Converter

Abstract: This paper describes a new series resonant converter for a 150-volt dc power supply system. This converter has been studied in order to overcome the disadvantage of conventional series resonant converters which must widely vary the conversion frequency to keep the output voltage constant, thus causing audible noise under light-load conditions. A series resonsnt circuit is added parallel to the output circuit of the conventional converter. By utilizing the impedance characteristics of the additional circuit, the output voltage can be regulated with less conversion frequency variation than in conventional circuits. From experimental results, the conversion frequency variation necessary to keep the output voltage constant in a 0-to-100 ampere output current range was found to be only about 30% of that of conventional circuits. The conversion efficiency of this converter is about 85% at 100 ampere output current.

A controllable power source

Abstract: A controllable power source is suitable for driving one or more electric motors from a low voltage battery. A converter steps up the d.c. voltage to a higher level at which the motors are designed to operate and a power regulator placed between the converter and each motor regulates the power which is drawn at the higher voltage by the motors. A current limit is imposed on the converter which is significantly less than the maximum current handling capabilities of the motors, so that when a motor attempts to draw an excessive current the output voltage of the converter drops accordingly. This enables the overall power handling capability of the converter to be minimize, while still allowing a motor to draw maximum current or maximum voltage, but not both simultaneously.

Controlling method for induction motor

Abstract: PURPOSE: To enable slip frequency to be controlled to always come to a proper value even if a primary resistance is fluctuated, by taking a signal in relation to a secondary resistance fluctuation of a motor from a voltage fluctuation quantity, and by controlling converter output frequency according to said signal CONSTITUTION: The output of current detectors 3U∼3W is fed to a coordinate converter 5 via a three-phase/two-phase converter 4 The outputs of the coordinate converter 5 and current regulators 15, 16 is fed to an arithmetic circuit 18 Output voltage fluctuation component due to the change of a secondary resistance of a motor 2 from the arithmetic unit 18 is applied to an adder 23, and the frequency of the motor 2 from an adder 26 is sent to a coordinate reference generator 13 and a voltage command arithmetic circuit 14 From the voltage command arithmetic circuit 14, the voltage component command of a revolving-field coordinate system is applied to adders 21, 22 and the output is sent to a coordinate converter 17 By the voltage command of a stator coordinate system from the coordinate converter 17, via a PWM controlling circuit 19, a power converter 1 is controlled COPYRIGHT: (C)1989,JPO&Japio

DC to DC converter with self-starting flyback oscillator

Abstract: A power supply for an acoustic fuel injector (18) comprises a DC to DC converter (14) for supplying a regulated voltage to a frequency-controlled oscillator (16) which drives the injector valve or valves. The converter (14) 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 transistor (50) in the input circuit to the flyback oscillator (28) is controlled by a feedback signal (68) from the output circuit (30) to vary the cycle rate of the flyback oscillator (28) to maintain output voltage at a desired value. Start up of oscillations in flyback oscillator (28) is assisted by a resistive feedback connection (56) and oscillations are maintained by a tertiary transformer winding (38).

An improved switching converter model

Abstract: The nonlinear modeling and analysis of dc-dc converters in the continuous mode and discontinuous mode was done by averaging and discrete sampling techniques A model was developed by combining these two techniques This model, the discrete average model, accurately predicts the envelope of the output voltage and is easy to implement in circuit and state variable forms The proposed model is shown to be dependent on the type of duty cycle control The proper selection of the power stage model, between average and discrete average, is largely a function of the error processor in the feedback loop The accuracy of the measurement data taken by a conventional technique is affected by the conditions at which the data is collected

Method and apparatus for controlling a pulsed frequency converter

Abstract: A system for forming addressing signals for addressing respective converter switches of a frequency converter; the frequency converter being of the type which is provided with DC input terminals for receiving electrical energy which is conducted to phase output terminals when the converter switches are operated in response to the addressing signals. Each of the combinations of converter switches is associated with a discrete space vector, and a load voltage vector is determined. In operation, two of the discrete space vectors which are adjacent to the voltage space vector are addressed for respective dwell times which correspond to the components of the voltage space vector as impressed upon the adjacent discrete space vectors. Either prior to or after the addressing of the adjacent discrete space vectors within a switching cycle, a short circuit state is addressed. In one embodiment, the order in which the adjacent discrete space vectors are addressed is reversed for each subsequent switching cycle. Also, the DC input terminals to which the phase outputs are short circuited are alternated.

Subscriber line circuit comprising a controllable DC/DC converter as a battery feed circuit

Abstract: A subscriber line circuit comprises a controllable DC to DC converter (41) for producing a converter output signal which becomes a loop signal comprising a DC signal and/or a communication signal of a communication frequency band. First and second voltage signals are dependent (51, 69) on the current and the voltage of the loop signal, respectively. One of the voltage signals is amplified (71) with different transfer functions at DC and in the communication frequency band. The converter is controlled (85-86) by an error between a first sum (81) of the amplified signal and the other voltage signal and a second sum (82) of a reference voltage (E O ) and a signal supplied from an output (27) of an exchange. A subtractor (92) supplies a difference between the exchange output signal and the second voltage signal to an input (25) of the exchange. Preferably, terminals (16, 17) for connection to a subscriber substation are isolated at DC from terminals (18, 19) for connection to the exchange input and output.

Compensation of nonlinearities of transmission members in a radio relay system

Abstract: A method for compensating nonlinearities of a transmission member in a radio relay transmission system by means of a linear converter having a linear gain characteristic and a harmonic generator converter having a nonlinear characteristic, in which an intermediate frequency signal modulated a useful signal is converted by a local oscillator signal into a radio frequency signal and the output signals of the two converters are linked together by a network. The method further includes: setting the operating point of the harmonic generator converter in a manner to cause its output signal to be essentially composed of components corresponding to the useful signal and to third order intermodulation products thereof; modifying the harmonic generator converter output signal by substantially suppressing the useful signal component from that output signal and setting the amplitude of the remaining third order intermodulation products component of that output signal; setting a relative phase position between the modified output signal of the harmonic generator converter and the output signal of the linear converter; and combining the modified output signal of the harmonic generator converter and the output signal of the linear converter subsequent to setting the relative phase position.

Charging system for power storage battery of carriage truck

Abstract: PURPOSE:To effectively charge a storage battery by using a converter for supplying a DC load power source also as a DC converter for charging the battery, and controlling the converted voltage in response to the battery charging current and the load current. CONSTITUTION:The output voltage of a storage battery 6 is supplied to a drive motor 4 through a chopper controller 5 in a non-trolley zone. The voltage converted to DC from 3-phase AC collected through a current collector 1 from a 3-phase trolley from an AC/DC converter 2 is supplied to the controller 5 and the battery 6 in a trolley zone. At this time a gate control circuit 3 controls so that the sum of the load current and the battery charging current does not exceed the prescribed value, and controls the DC output voltage of the converter 2 so that the battery charging current becomes a set value.

Power supply apparatus

Abstract: A forward converter circuit (FIG. 1) is provided with a transformer reset sensing circuit (FIG. 2) whereby base drive to the switching transistor TR1 is inhibited until after reset of the transformer T1. The reset sensing circuit includes a sensing winding T1d provided on the transformer for sensing the waveform at the primary winding T1a, a comparator IC1 and diodes D5, D4 connected in such a way that one input of the comparator is high when the waveform changes in one direction, and the other input of the comparator is high when the waveform changes in the other direction. The output of the comparator inhibits switching of the transistor before reset and thus allows the use of a maximum switching duty cycle of 50% without risk of transformer saturation.

Control circuit for a dc-ac converter

Abstract: For a d.c.-a.c. converter a control circuit is proposed which improves the efficiency of the converter and enables it to operate at a higherfrequency using the same semiconductor switches. For this purpose the residual voltage across the currently conductive switch (9, 10) is compared with a reference voltage (23) via an analog OR-gate (26) and the control signal for the conductive switch is controlled in such a way that the residual voltage is set to a desired value (19, 20, 21, 11, 13, 14). The converter with the control circuit is extremely suitable for use as a high-efficiency power-supply for fluorescent lamps and occupies the smallest possible volume.