Showing papers on "Forward converter published in 1976"

A Controllable Secondary Multikilowatt DC Current Source With Constant Maximum Power Factor in its Three-Phase Supply Line

Abstract: A type of industrial size dc converter for submegawatt applications is described and illustrated with the characteristics of a small scale 10 kW model. High conversion efficiency near 97 percent is maintained at full power and with an internal frequency of operation near 10 kHz. The system is characterized by the behavior of a true current source with inherent short circuit capability of its output terminals. All power is processed via a firmly controlled high Q series resonant circuit. Feasibility of power densities in excess of 1 kW/kg component weight is demonstrated. This high power density reflects itself in low quantities of material needed for construction of these systems. Operation of the dc converter as part of a rectifier-filter converter system, powered from a three-phase supply line is described. Test data demonstrate a high power factor PF?0.95 for all conditions of converter loading. Data obtained from a thyristor bridge-filter system are presented and subjected to comparative analysis.

Cooperative primary and secondary current limiting to selectively limit aggregate and individual current outputs of a multi output converter

Abstract: A single-ended converter circuit operating in a transformer coupled mode is disclosed having multiple outputs. A current limiting circuit is included on the primary side of the power transformer to limit the total aggregate current output of the converter. Secondary current limiting circuitry is included in selected ones of the multiple outputs to individually limit current outputs of the converter. A similar current limiting arrangement is disclosed for application to double-ended type converter circuits.

Integrated circuit high voltage DC converter

Abstract: A step-up DC converter suitable for construction as an integrated circuit chip provides a separate rectangular wave oscillator using a silicon transistor and a power amplifier driven thereby which supplies current to the primary winding of a two-winding step-up transformer matched to the constant duty cycle of the oscillator thereby simplifying construction of the transformer and permitting the oscillator and power amplifier voltage step-up transformer functions to be individually optimized for overall high efficiency operation. A hysteresis switching voltage comparator senses the rectified value of the high voltage output from the transformer relative to a stable reference voltage and switches both the oscillator and the amplifier to their standby current condition when a predetermined high output voltage level is obtained and switches both oscillator and amplifier into conduction when the output voltage falls to a predetermined level. A second comparator operates an LED indicator when the output voltage is above a certain level.

Voltage boost circuit for DC power supply

Abstract: A typical "stand alone" precision power DC to AC solid state converter reres a higher DC supply voltage than is usually available from its utility power sources. The disclosed invention is a voltage boost circuit that provides the DC-bus voltage amplitude for precision power DC to AC solid state converters by transforming only the difference between the available raw power DC voltage bus and the required precision DC voltage amplitude. This DC voltage difference obtained by the circuitry of this invention is boot-strapped to the available DC bus to obtain the required precision DC voltage.

DC to AC switching converter

Abstract: A regulated DC to AC power converter of the switching type for providing AC power at a selected output frequency, e.g., 50 Hz, is disclosed. The converter, which eliminates the need for an inverter transformer, is switched at a switching frequency which is considerably higher than the output frequency, e.g., 10 KHz. Due to the high switching rate the converter filter can be designed with small and lightweight components to provide a desired pass band, which includes the output frequency and harmonics thereof, and provides sufficient attenuation for the switching frequency and its higher harmonics, so as to produce an output with very low ripple or waveform distortion. Due to the high switching frequency the output waveform can be regulated with a response time of a fraction of a cycle. The converter includes a modulator section with a unique arrangement to control the switching of the switches between their On and Off states. In preferred embodiments of the converter the switches are implemented with transistors to form AC power at high power levels. Each switch includes a plurality of relatively inexpensive transistors which are connected in parallel with each transistor drawing only a small portion of the total current through the switch. A novel arrangement is employed to increase switch reliability by preventing its failure even though one or more of its transistors may fail in a short-circuit state. For switches implemented with transistors the extended turn-off time of the transistors, due to their saturated states, is accommodated by controlling the turning On of each switch to occur only after the transistors of the previously turned On switch returned to their Off state.

High speed digital switch

Abstract: A switching system for rapidly configuring transmission paths between comer equipments for high speed digital information in parallel form couples the input of a parallel-to-serial (P/S) converter to the output of each equipment providing information and the output of a serial-to-parallel (S/P) converter to the input of each equipment receiving information. A digital switch rapidly configures information transmission channels between its inputs and outputs in response to instructions from a configuration control. Each switch input is coupled to the output of a P/S converter, and each switch output is coupled through a switch output lead to the input of an S/P converter. A clock provides a periodic clock signal to each P/S converter through an adjustable delay control and to each S/P converter through a clock lead, wherein the electrical lengths of the switch output lead and clock lead coupled to the same S/P converter are equal. Each transmission path through the system is coupled between a P/S converter and an S/P converter which are synchronously operated.

Communication system interface circuit

Abstract: A communication system includes a mobile station, a plurality of base stations and a central terminal. Each base station converts RF signals from the mobile station to AF signals. The AF signals are carried over a balanced line to the central terminal. Each base station generates a DC voltage signal whose level is representative of the level of its received RF signal. The central terminal includes means to monitor DC current levels, from each base station, on the balanced line and select that base station producing the highest DC current. The unique interface circuit senses the base station generated DC voltage, which is referenced to a fixed ground potential, and produces a corresponding current which is referenced to a floating ground potential. This current is then coupled to the balanced line for transmission to the central terminal. The interface circuitry includes a DC to AC converter which converts the DC signal voltage to an AC signal. This AC signal is capacitively coupled to an AC to DC converter which generates a corresponding DC voltage. The final stage is a transconductance circuit which produces an output current presenting the DC voltage level generated by the AC to DC converter. In this manner, a ground referenced voltage is transformed to a floating ground reference current suitable for transmission down a balanced line.

The venable converter: a new approach to power processing

Abstract: A regulating DC-to-DC converter is described which utilizes a new circuit configuration to achieve several desirable features including higher efficiency, a single circuit for regulation and conversion, minimized output filter requirements and simplified control system applications. The DC operating characteristics are derived and the efficiency of the new ocnverter is shown to compare favorably with the conventional boost regulator. An AC model is derived and a comparison is made between analytical and experimental results.

Naturally commutated voltage-fed converter for linking a DC source to an AC system

Abstract: A naturally-commutated, voltage-fed direct-current (DC) to alternating-current (AC) power converter employing thyristor elements couples a DC power system with an AC power system without the requirement to force commutation. To effect natural commutation, the fundamental component of current flowing between the DC system and the AC system must lead the DC system switching voltage.

Dc voltage converter and shock-type high voltage utilization

Abstract: A DC voltage converter includes an oscillator that converts a DC battery voltage to an oscillating voltage, a low voltage transformer that increases the oscillating voltage to a higher oscillating voltage, and a voltage rectifying-capacitor charging network that increases the higher oscillating voltage to yet a higher DC voltage at an output terminal for DC high voltage utilization devices and the like An electric switch portion is selectively actuated by the user to apply the battery voltage to the oscillator, resulting in the generation of the stepped-up DC voltage at the output terminal Utilization devices for the voltage developed by the converter shown are a miniature animal training device and a cattle prod device The miniature animal training device has a pair of outwardly projecting electrodes mounted on a side at one end of the housing that is sized and shaped to fit within and conform to the palm of a hand The batteries, converter and electric switch portion are contained in the housing whereby the device produces a stepped-up DC voltage at said output terminal upon the depression of one of the electrodes as both electrodes are pressed against an object to be electrically shocked The cattle prod device has a pair of electrodes mounted on the end of a housing assembly made up of telescoping tubular housing sections with one housing section containing the batteries, converter and electric switch portion whereby the pressing of the electrodes against an object to be shocked causes a shock of the object The housing assembly is releasably supported by a rigid handle or an extensible handle assembly

Emission standards and design techniques for EMI control of multiple DC-DC converter systems

Abstract: Radiated and conducted emission standards are derived for each converter in a multiple DC-DC converter system, allocated as a function of power rating. Analytical methods of predicting the emission and design techniques for achieving the standards are described. Recommended procedures and test equipment used to determine the actual emission level of each converter are also described.

Laser power supply

Abstract: A laser power supply includes a dc to dc converter which feeds a multiplier-rectifier circuit to provide a high dc voltage output. The converter includes a power transistor which is subject to a control of its on time to provide constant current regulation. A smooth regulation is provided by a proper timing of the turn off signal to the power transistor by sampling the emitter signal of a transistor which is included in a synthesized thyristor, the thyristor being operable to hog base current from the power transistor. The converter is coupled to the output multiplier-rectifier by a transformer which has a feedback winding connected in series with the base of the power transistor.

Unipolar wide-range current-to-frequency converter

Abstract: In a unipolar version of an analog-to-digital converter of low-level signals involving a self-zeroing current-to-frequency converter, which virtually eliminates the effects of voltage offsets at the input to the converter while avoiding large leakage currents, improved circuitry is provided in order to avoid paralysis of the converter which could be caused by small input currents or charges of polarity opposite to that of the normal signal current or by drifts in the converter input voltage which produce a negative-charge offset. The circuitry includes provision for the automatic introduction at the converter input of a relatively-large restoration current with the same polarity as the signal current, and this current can also be used for converter checking and calibration. One version of this circuitry involves exposing a junction diode at the converter input to light, causing it to act as a photodiode. One easily controlled source of such light may be a light-emitting diode conducting a suitable current placed in close proximity to the junction diode within the same enclosure. When the junction diode forms a part of a secondary feedback loop used during the discharge period of a primary capacitive feedback, then exposing it to light speeds up the secondary feedback, thereby reducing converter dead time. Other devices may be used for current introduction at the converter input, including a mechanical switch, but they are less preferable from the standpoint of leakage current, size and speed of response.

A frequency-stabilized free-running DC-DC converter circuit employing pulse-width control regulation

Abstract: A dc-to-dc converter circuit in the power range of 10 to 50 watts is described. While comparable to ringing choke converters or self-oscillating switching regulators in simplicity, small size, and low cost, this circuit offers many of the features usually found only in larger, more-complex driven converters.

Efficient AC energy converter - has internal resistance of DC energy converter connected into AC circuit

Abstract: The ac energy converter has improved energy conversion efficiency compared with direct conversion systems such as thermocouples, thermionic valve diodes, photovoltaic cells, fuel cells, magnetohydrodynamic converters etc. To this end, the electrical internal resistance of a direct energy converter is connected into an a.c. circuit, and means are provided to ensure that the current flows through the internal resistance of the direct energy converter as rectified current, and that an impedance is provided in the a.c. circuit so as to limit the current. The impedance value is greater than the value or magnitude of the internal resistance of the direct energy converter, which is a laser diode.

Switching regulator with feedback system for regulating output current

Abstract: A switching regulator includes a chopper circuit and a DC-DC converter. A switching signal for use with the chopper circuit is derived from an inverter portion of the DC-DC converter so as not to use an external pulse oscillator. A DC voltage feeback circuit is provided from the output of the DC-DC converter to the chopper circuit so as to stabilize the DC output signal of the DC-DC converter.

The use of voltage feedback in HVDC converter control

Abstract: The use of combined voltage and current feedback for converter control was investigated. A simplified linear model for a monopolar dc link was developed for analysis of large and small disturbances. Using parameters from the proposed EPRI - Consolidated Edison 100 MW dc link, an eigenvalue analysis was performed, in which a compensated current feedback control was compared with the system using voltage feedback. Results of the linearized analysis showed that the use of voltage feedback appears to offer greater damping of system oscillations and considerably faster large-signal response than the use of a conventional current regulator. A detailed hybrid computer simulation of the 100 MW dc link was also used in the investigation. The ac system, individual converter valves, converter controls, and the dc line are fully represented in the simulation. Computer studies were made for various operations and disturbances, in which the current control was compared with the system using voltage feedback. Generally the results of the simulation agree with the basic conclusions reached from the linear analysis, however, the use of the simplified linear model for selecting optimum control parameters was in several cases shown to be somewhat inaccurate.

Digital-to-analog converter having transient suppressor system

Abstract: A digital-to-analog converter having means to suppress the transient signals present at the output of the converter in response to a clock pulse synchronized with the transient signal. The clock pulse applies a forward bias to a pair of series-connected diodes which clamp the digital-to-analog converter output to ground. An integrator is connected to the converter output terminal to stabilize and filter the output signal while the terminal is clamped to ground.

DC to AC voltage converter with automatic start-stop control of motor-generator set

Abstract: The converter includes a dc. motor energizable from a battery and adapted to drive an alternator which produces an ac. output voltage for powering a load device. When the switch of the load device is closed or opened to start and stop the latter, the motor of the converter is automatically energized or de-energized. A unique system for controlling automatic energization and de-energization of the motor is constituted by low cost and reliable components and is characterized by a voltage divider and a diode circuit which (1) cause battery current to flow through a pick-up resistor to effect starting of the motor when the load device switch is first closed, and (2) limit the current through the resistor to small values when the alternator is operating.

Control arrangement for converter

Abstract: A control arrangement for a converter of the type including a direct current motor driving a three-phase generator with at least one exciter coil of the generator and/or of the motor being fed from the three-phase mains of the generator via a series connected transformer and a rectifier. At least one secondary winding of the transformer is connected in a closed series circuit which further includes a controlled thyristor, and two other secondary windings of the transformer which other windings are connected in parallel. In dependence on the parameter of the converter to be regulated, the control current of the thyristor is varied to provide a two-point regulation of the saturation current for the transformer flowing through the closed series circuit.

Power saving circuit for use with a converter circuit in a telephone switching installation

Abstract: Power saving means is shown for use with a converter circuit in a telephone switching installation. The converter circuit comprises an analog-to-digital converter and a digital-to-analog converter. The voltage supply for the converter circuit is switched on only upon the appearance of analog signals to be converted into digital signals or digital signals to be converted into analog signals.

Power transformer with infinitely variable output voltage - primary and secondary on common limbs with cut-outs for DC excited windings

Abstract: Transformer with continuous adjustment of the output alternating voltage. The primary and secondary windings are both wound around the same transformer limbs. Each limb has cut-outs for a pair of control windings which are connected in the same sense and are excited by direct current. This ensures that the magnetic core is always saturated. The cut-outs for the control windings are on the core limbs with both primary and secondary windings. The transformer is designed for three-phase operation and the magnetic core has six limbs of which pairs have common axes and to which there are three yokes.

The biased transformer DC-to-DC converter

Abstract: A dc-to-dc converter design based on the constant-current flux-reset principle is presented. Such converters use a mulitude of separate individual half-wave switching sections. Each section consists of a power transistor and a transformer which is reset through an external bias current source. The transformer typically contains a square-loop core without an airgap. Center tap, SCR, and bridge-type configurations are presented attendant to single-phase full-wave, and polyphase operation. Transformer-core saturation dc ratcheting and cross conduction problems, which frequently plague dc/dc converters, are eliminated. As a result, considerable differences in conduction times between power transistors can be tolerated, as well as some overlap resulting from storage and recovery lags. Typical approaches, circuit variations, and tradeoffs are being presented. Detailed schematic diagrams of actual units for aerospace applications and for industrial uses are discussed in the Appendix.