Showing papers on "Forward converter published in 1984"

High-Frequency Resonant Transistor DC-DC Converters

Abstract: Transistor dc-dc converters which employ a resonant circuit are described. A resonant circuit is driven with square waves of current or voltage, and by adjusting the frequency around the resonant point, the voltage on the resonant components can be adjusted to any practical voltage level. By rectifying the voltage across the resonant elements, a dc voltage is obtained which can be either higher or lower than the input dc voltage to the converter. Thus, the converter can operate in either the step-up or step-down mode. In addition, the switching losses in the inverter devices and rectifiers are extremely low due to the sine waves that occur from the use of a resonant circuit (as opposed to square waves in a conventional converter); also, easier EMI filtering should result. In the voltage input version, the converter is able to use the parasitic diode associated with an FET or monolithic Darlington, while in the current input version, the converter needs the inverse blocking capability which can be obtained with an IGT or GTO device. A low-power breadboard operating at 200-300 kHz has been built. Two typical application areas are switching power supplies and battery chargers. The converter circuits offer improvements over conventional circuits due to their high efficiency (low switching losses), small reactive components (high-frequency operation), and their step-up/stepdown ability.

Transformerless DC-to-DC Converters with Large Conversion Ratios

Abstract: A new switching dc-to-dc converter is introduced in which large voltage step-down ratios can be achieved without a very small duty ratio and without a transformer. The circuit is an extension of the ?uk converter to incorporate a multistage capacitor divider. A particularly suitable application would be a 50V to 5V converter in which dc isolation is not required. The absense of a transformer and a larger duty ratio permits operation at very high switching frequency, and makes the circuit amenable to partial integration and hybrid construction techniques. An experimental three-stage voltage divider ?uk converter converts 50V to 5V at 50W with an efficiency of 77% at 500 kHz and 71% at 1 MHz, higher than for a basic ?uk converter operated at the same conditions.

Class E high-frequency high-efficiency dc/dc power converter

Abstract: A Class E switching-mode dc/dc power converter is obtained by adding a rectifier circuit at the output of a Class E dc/ac power inverter. It can operate at high efficiency at high switching frequencies. Further, the power switch is not subjected to high power dissipation or high second-breakdown stress while it is switching between the "on" and "off" states, even if the dc load on the power converter varies over a very wide range, e.g., from open-circuit to short-circuit. The high efficiency is achieved by shaping the waveforms of switch voltage and switch current so that the transitions of those two waveforms are displaced in time from each other. Then the power switch does not experience simultaneously high voltage and high current while switching. High efficiency and low stress on the switch are achieved under all load conditions by interposing a matching network between the output of the Class E dc/ac inverter and the input of the rectifier circuit. That matching network transforms the rectifier input impedance in such a way that the impedance presented to the output of the Class E dc/ac inverter is always in the range which generates switch voltage and current waveforms that yield low power dissipation and low second-breakdown stress during switching, for any value of dc load resistance at the output of the rectifier.

Accumulation time adjusting device for photo-electric converter

Abstract: There is disclosed a device for correcting the accumulation time of a photoelectric converter composed of self-scanning charge-accumulation elements of plural bits on the basis of the average intensity to the incident light to the converter. The charge accumulation time is controlled by determining a reference value according to the maximum value of the output signals obtained from the photoelectric converter and comparing this reference value with the average intensity.

Fuel injection apparatus employing electric power converter

Abstract: Fuel injection apparatus including a power converter for generating a stable, high voltage DC signal for powering the fuel injectors. The power converter is connected to a voltage source such as a vehicle battery. The power converter includes a DC-DC converter and a feedback-stabilized converter control circuit. The converter control circuit adjusts the operation of the DC-DC converter in a direction to counteract changes in output voltage caused by battery voltage variations. The high voltage DC signal is applied to each injector through one or more solid state switches. Since the signal used to power the fuel injectors is substantially constant regardless of normal battery voltage variations, the injector pull-in time is substantially constant. Moreover, the use of a high voltage power signal enables low current injectors to be used. The low injector current results in low power dissipation by the solid state switches which operate the injectors. The output voltage generated by the converter is also used to bootstrap the power signal applied to the converter control circuit.

Systematic Derivation of Two-State Switching DC-DC Converter Structures

Abstract: The new method of derivation of two-state dc-dc converter structures is proposed. In contrast to the available techniques this method originates from the set of general requirements concerning both structure and operation of a switching converter. These requirements coupled with an adopted definition of a minimal number of elements, are converted into the form of topological graph properties and applied in the proposed synthesis procedure. As a result, twelve basic two-state converter structures, including four new topologies, are obtained.

C-R type D/A converter

Abstract: A C-R type D/A converter which comprises a C-array type D/A converter used to convert the upper bit data of a digital input data on a digital-to-analog basis, an R type D/A converter used to convert the lower bit data of the digital input data, and a coupling capacitor connected between an output terminal of the C-array type D/A converter and an output terminal of the R type D/A converter.

A New Integral Pulse Module for the Series-Resonant Converter

Abstract: A method to apply the principle of integral pulse modulation to the series-resonant converter is proposed, analyzed, and tested. The proposed control module facilitates combining the favorable properties of the series-resonant power converter (reliability, low weight, high efficiency) with those of the pulse integral control system (accuracy, fast response).

Combination low-pass filter and high frequency transient suppressor

Abstract: Spikes occurring on an AC line and coupled through an AC to DC converter are substantially decoupled from a DC load of the converter even though the converter includes a supply transformer and a shunt electrolytic filter capacitor, by a circuit comprising a shunt network including a bidirectional breakdown means having a predetermined threshold conduction level with a dead band series connected with a capacitor. The capacitor is a low impedance capacitive reactance to high frequency components in pulses developed by the converter in response to the spikes, and a high impedance to ripple of the line derived by the converter. The high frequency components are supplied by the breakdown means to and through the capacitor to momentarily interrupt the flow of current from the converter to the load when the pulses are derived. A low pass filter connected in series with the shunt network and the load has a cut-off frequency lower than the ripple frequency.

Converter/line driver circuit for a line repeater

Abstract: A converter circuit receives N-rail logic signals and converts them into a precision N-level signal. A pair of line drivers (47, 48) is connected in a balanced output arrangement with the primary winding (52) of an output transformer (55). In response to the N-rail logic signals, weighted currents are conducted through an input impedance, connected with the line drivers, to a ground reference. As a result the line drivers conduct various levels and polarities of current through the entire primary winding of the output transformer. Thereby a precision N-level signal is produced in a secondary winding of the output transformer and at the converter output terminals.

Adaptive analog-to-digital converter

Abstract: The converter system includes a conventional N bit analog-to-digital (A/D) converter and also includes an automatic gain control circuit and DC offset circuit to alter the input analog signal to utilize the full N bit capacity of the A/D converter regardless of the amplitude of the input signal, within the range of the calibration of the system.

New Integrated-Magnetic Power Converter Circuits for Telecommunication Systems

Abstract: Novel integrated-magnetic alternatives to conventional DC-to-DC power converter circuits are discussed together with principles behind the integration process, typical electrical waveforms observed within such topologies, and ideal voltage transfer functions that can be achieved Guidelines in the modeling, analysis, and practical design of these unique converters are also given

Design and operating experience of an ac-dc power converter for a superconducting magnetic energy storage unit

Abstract: The design philosophy and the operating behavior of a 5.5 kA, +-2.5 kV converter, being the electrical interface between a high voltage transmission system and a 30 MJ superconducting coil, are documented in this paper. Converter short circuit tests, load tests under various control conditions, dc breaker tests for magnet current interruption, and converter failure modes are described.

Magnetically modulated d-c to d-c forward converter power supply

Abstract: A d-c to d-c forward converter power supply has a magnetic modulator in the timing circuit which operates between its residual magnetic flux density and its saturation flux density to deliver a fixed number of volt seconds during sequential clock interval periods. The clock period is fixed so that the output voltage averaged over each clock period will be constant and independent of input voltage over a given design range. A bias current is applied to the magnetic modulating transformer to controllably modify volt second capability of the device. In one embodiment, two transformers are employed, one of which is non-saturating and the other of which is a control transformer and saturates during its operation. In a second embodiment of the invention, only a single transformer, which is a saturating transformer, is employed.

Steady-State Characteristics of the Push-Pull DC-to-DC Converter

Abstract: Six modes of operation for the push-pull 4c-to-dc converter are presented by taking into account the magnetizing current of the transformer If the inductance of the transformer is decreased, the region where the output voltage is abnormally high is expanded in the load characteristics

High-energy ignition device

Abstract: An high-energy ignition device having an igniter coil adapted to produce a high voltage for allowing an electric discharge between electrodes of a sparking plug in accordance with the output from an ignition circuit, and a DC-DC converter adapted to produce a voltage high enough to maintain the electric discharge in the sparking plug. The DC-DC converter is connected such that the output thereof is superposed to the discharge current produced by the igniter coil. The igniter coil and the transformer of the DC-DC converter are integrated with a forming resin. Consequently, the electrical insulation between the parts is improved and the mounting of the ignition device on vehicles is facilitated.

Converter control system having stable power transfer in the presence of decreased input AC voltage

Abstract: A converter control system for DC power transmission line performs the following operation. When the DC current flowing through an inverter decreases to a value being smaller than a rated current value by a value in excess of a predetermined value, a reference voltage value determining the DC voltage of the inverter decreases. The decrease of this reference voltage value is limited to a given extent, so that a partial constant current characteristic portion appears at the voltage decreased portion in the DC voltage/current characteristic of the inverter. Then, an automatic voltage regulator of the inverter is rendered always active.

Direct current voltage converter apparatus

Abstract: A DC voltage converter apparatus is provided to convert a fluctuating input DC voltage into an isolated and regulated output DC voltage by operation of a first switch device for charging a capacitor through one primary winding of a transformer and a second switch device for discharging the capacitor through a second primary winding of that transformer. A load is energized by an output voltage from a first secondary winding when the first switch is conducting and is energized by an output voltage from a second secondary winding when the second switch is conducting. The first and second switching devices are controlled in response to the voltage change across the capacitor.

A Pulse-Width Controlled DC-DC Converter Powered by a Constant-Current Source

Abstract: A pulse-width control method is used to regulate output voltage for a DC-DC converter powered by a constant-current source. In a constant-current input converter, the output voltage rises as the transistor switching duty ratio is decreased and falls when the duty ratio is increased. Regulation is achieved by increasing the duty ratio when the output current decreases and decreasing the duty ratio when output current increases. This is the reverse of the technique used with constant-voltage input.

Converter control system

Abstract: A converter control system for DC power transmission line performs the following operation. When the DC current flowing through an inverter (1B) decreases to a value being smaller than a rated current value by a value in excess of a predetermined value (E35), a reference voltage value (E14B) determining the DC voltage of the inverter (1 B) decreases. The decrease of this reference voltage value (E14B) is limited to a given extent, so that a partial constant current characteristic portion (j, k in Figure 6) appears at the voltage decreased portion in the DC voltage/current characteristic of the inverter (1B). Then, an automatic voltage regulator of the inverter (1 B) is rendered always active.

Direct current tight coupling

Abstract: A direct current tight coupling is provided for connecting two asynchronous high-voltage three-phase power systems which includes a three-phase full-wave static converter assembly assigned to each of the power systems to be connected, with static converter transformers and controllable semiconductors, which are controlled by a central electronic control unit so that the input-side static converter assembly functions as a rectifier and the output-side static converter assembly as an inverter. The controllable semiconductors of a functional group are mounted atop each other forming identical static converter towers. The towers are connected together at the same pole on the d.c. side and on the three-phase side with the assigned Wye- and Delta-connected secondary sides of the static converter transformers. Each of the full-wave semiconductor subassemblies assigned to the four secondary sides of the static converter transformers form a static converter tower.

Testing circuit of ad converter

Abstract: PURPOSE: To check the accuracy of an AD converter through digital signal processing by providing a digital-analog (DA) converter which outputs the input voltage of an AD converter to be tested, a counter circuit which outputs the input value of the DA converter, and the 1st and the 2nd arithmetic circuits which calculate an error CONSTITUTION: The output value of the counter circuit 1 is latched by latch circuits 4 and 5 successively every time the output value of the AD converter 8 increases by one LSB, and a subtracting circuit 6 calculates the difference between output values of the latch circuits 4 and 5 to find the quantity of variation in the output value of the counter circuit 1 corresponding to one LSB variation in the output value of the AD converter 8 The output value of the subtracting circuit 6 is compared with that of a comparator A which is set previously by a comparing circuit 7 to compare the quantity of variation in input voltage value with the one LSB variation in the output value at each input voltage point of the AD converter 8, thereby checking a differential nonlinear error COPYRIGHT: (C)1986,JPO&Japio

Current mode control of switching regulators

Abstract: By adapting the forward converter range of switching regulators to include an additional current-controlled feedback loop, derived from either the secondary or primary power circuit, an improvement in the closed-loop performance of the switching regulator can be obtained. The basic analysis work examines the simple single-ended forward converter, with d.c. plus a.c. current control, derived from the secondary power circuit. An additional fixed voltage ramp is also included in the control loop to provide `feedforward? compensation for input voltage disturbances, and also to extend the maximum duty cycle from 50% up to 100%. Using this circuit configuration a simple small signal equivalent circuit for the current-controlled switching regulator can be obtained, enabling the performance of practical designs to be predicted. Practical implementation of the current mode control technique using a standard large-scale integrated circuit together with a number of applications is also given.

Digital-to-analog converter biasing control circuit

Abstract: A device for controlling the output voltage range of a digital-to-analog (D/A) converter of the type wherein the converter output voltage range is proportional to the magnitude of an applied bias current. The device comprises means to sample and store a selected converter output voltage, means to produce a variable current of magnitude proportional to the stored converter output voltage, and a source of constant current. The constant current and the variable current are summed and applied to the converter as the bias current. The converter output voltage range is dependent on the variable portion of the applied bias current which is in turn dependent on the stored, selected converter output voltage.

DC-DC converter having feedback type switching voltage converting circuit

Abstract: A DC-DC converter having a high conversion efficiency and stable output voltage. A constant current supply circuit, located between the output terminals of the converter, make it possible for the source current to decrease as a function of battery output voltage, resulting in lower current requirements for a lower required voltage boost and hence increased efficiency.

DC/DC converter for power switch-mode power supplies

Abstract: In a DC/DC converter which is formed from a forward converter (T1) which is controlled via at least one first semiconductor switch (S1) and from a flyback converter (T2) which is controlled via at least one second semiconductor switch (S2), which is provided with a load-shedding network and is driven ideally, it is intended that the first semiconductor switch (S1) should switch without current flowing. To this end, a tuned circuit consisting of a capacitor (C1) and an inductor coil (L1) is arranged between the poles of the DC voltage source on the primary side, in which tuned circuit the connecting point between the capacitor (C1) and the inductor coil is connected to the connection between the flyback converter (T2) and the second semiconductor switch (S2). During demagnetisation of the stray inductances (LS) of the two converters (T1, T2) with the second semiconductor switch (S2) open and the first semiconductor switch (S1) (still) closed, the potential on the second semiconductor switch (S2) can thus be raised above that on the first semiconductor switch (S1), in order to allow the first semiconductor switch (S1) to be opened without current flowing.

Small-signal dynamic analysis of regulated Class-E DC/DC converters

Abstract: Class-E dc/dc converters can operate at high switching frequencies with very low switching power losses. Using commercially available power transistors and diodes, Class-E converters can operate at switching frequencies in the low-MHz range, with efficiencies of about 85%. Previous papers dealt with the circuit parameter values needed to obtain high-efficiency operation and output-voltage regulation, and with the static control characteristic of the Class-E dc/dc converter cell. Here we extend the analysis to include the dynamic control characteristics and further information about the static characteristics. The theoretical predictions are verified by experimental measurements on a 40-watt 1.5-MHz converter.

Control device for a converter having a DC intermediate circuit

Abstract: A control arrangement for a converter is specified, which consists of a mains-powered converter (1), a DC intermediate circuit (3) and a self-powered converter (5), and supplies an asynchronous machine (6) with a variable voltage and frequency. The control device is used for continuous control of the machine voltage (U) according to the load torque applied to the machine (6), while the speed (n) of the machine (6) is controlled in a predetermined manner. The control device has a higher-level voltage controller (10) whose input receives desired values and actual values for the machine voltage (U) and whose output is connected via a lower-level current regulator (12) to a control set (16) for controlling the mains-powered converter (1). Used for rapid detection of load torque changes and, in particular, for preventing tipping of the machine is a dynamic switch-on element (17) whose input receives the actual value of the intermediate circuit voltage (Udcist) and whose output emits a dynamic additional signal (Udyn), corresponding to the timed derivation of the intermediate circuit voltage, to the input of the voltage controller (10).

Method and device for stopping a DC intermediate-circuit converter

Abstract: If it is desired to stop the converter in a converter having a current [sic] intermediate circuit, by reducing the frequency to zero, then the commutating capacitors must be adequately charged in the correct polarity for starting operation again. To this end, if the frequency falls below a predetermined frequency limit, on the one hand the intermediate circuit current is limited to a constantly predetermined value, and on the other hand the invertor is operated at an increased commutating frequency until a predetermined phase angle in the commutation cycle is reached. When this predetermined phase angle is reached, the commutation cycle is stopped and the converter is blocked. There is then so much energy stored in the invertor that the commutation cycle can be started again at any time at this predetermined phase angle.