Showing papers on "Converters published in 1976"

An Improved Method of Resonant Current Pulse Modulation for Power Converters

Abstract: Presented is a converter philosophy for controlled transfer and transformation of electric energy through internal series resonant circuits at high internal power frequencies in excess of 10 kHz. Control of the continuously oscillating high Q series resonant circuit is attained by adjustment of the phase angle ? r between the exciting voltage and the resonant current. Only a very small fraction of the energy transferred to the load is absorbed by the resonant circuits to replace the power dissipated therein. Moderate and unconditionally predictable voltage and current stresses on components result from definite control of static and dynamic behavior of the system. This system is suited for construction of failsafe and highly efficient, low cost, submegawatt, single module converters with currently available components.

Reactive Compensation and Harmonic Suppression for Industrial Power Systems Using Thyristor Converters

Abstract: This paper discusses the problems and solutions of applying reactive compensation, either static or dynamic, to industrial power systems supplying large blocks of dc power from diode or thyristor converters. The resonance between power capacitors and system reactance can produce high harmonic voltages caused by the harmonic currents generated by converters. The interaction between these harmonic voltages and regulating systems can be minimized by the use of suitable filters. The design of these filters should eliminate the interaction between power system and load and reduce harmonic current flow. Different methods of reactive power control are also discussed.

Dynamic element matching for high-accuracy monolithic D/A converters

Abstract: A novel way to obtain a very high accuracy in the bit weighting required for bipolar monolithic digital-to-analog (D/A) converters is described. The new method combines passive division using matched elements with a time division concept, needs no trimming, and is insensitive to element aging. A 12-bit monolithic D/A network with internal reference sources, built as a test circuit, demonstrates the versatility of this new technique.

Ferroelectric materials as energy converters

Abstract: The performance of ferroelectric materials as converters of thermal into electrical energy has been analyzed in terms of their fundamental dielectric and thermal properties. The time dependent operation of a single stage pyro-ferroelectric converter performing a spontaneous cyclic process has been evaluated, leading to expressions for the specific power, current and voltage outputs in terms of the relevant static and transport parameters. It is concluded that ideal efficiencies of the order of 10-15% could be attained if proper materials with relatively large performance factor are developed to be used in multistage converters operating under large ΔT's.

A Conceptually New Approach for Regulated DC to DC Converters Employing Transistor Switches and Pulsewidth Control

Abstract: A new regulated dc to dc converter circuit gains several advantages over conventional approaches by separating the pulsewidth control function from the inverter. The distinguishing feature of the new circuit is the relocation of the principal filter inductor from the rectifier output to the inverter input. This departure from the conventional use of a shunt capacitor at the inverter input yields a number of fundamental improvements. These include the following: substantially reduced inverter switching losses, elimination of transistor switch-through and transformer saturation problems, greatly reduced peak reverse voltages on rectifier diodes, and simple means for limiting the peak output voltage and the peak current in all of the semiconductor components under transient conditions. These advantages are of major significance for high-power converters employing a high switching frequency(e.g., 1.8 KW and 20 kHz).

Integrating analog-to-digital converter with digital self-calibration

Abstract: With dual-slope integrating analogue-to-digital (A/D) converters, which are most frequently used for relatively low-speed conversion, the drift of the operational amplifier is a very critical factor in limiting their performance. The newly discovered digital self-calibration method which completely eliminates the drift problem, is more readily adaptable to ratiometric conversion, where the input and the reference voltages are of the same polarity. Some of the advantages are: no necessity of manual adjustments, the use of inexpensive operational amplifiers instead of costly units with no performance degradation for the temperature range limited only by digital circuits, and the possibility of A/D converters operating on a single power supply. As is the case with the basic dual-slope converters, no precision components of high absolute or relative accuracy are required.

Table-Aided Design of the Energy-Storage Reactor in DC-to-DC Converters

Abstract: A new procedure for the selection of magnetic cores for use in energy-storage dc-to-dc power converters that eliminates the need for an automated computer search algorithm and stored data file is presented. The converter configurations included in the procedure are the three commonly encountered single-winding converters for voltage stepup, for current stepup and voltage stepup/current stepup, and for the two-winding converter for voltage stepup/current stepup. For each converter configuration, three types of controllers are considered: constant-frequency, constant on-time, and constant off-time. Using concepts developed from analyses of these converters by considering the transfer of energy by means of an energystorage inductor or transformer, a special table of parameters calculated from magnetic core data is constructed, which leads to a considerably simplified design procedure.

Circuit arrangement with a number of frequency converters, particularly y-connected direct frequency converters

Abstract: A circuit arrangement is disclosed having an odd number of Y-connected frequency converters. The control units of the frequency converters are associated with current regulators, all of which are addressed by an additional common reference value. In accord with the invention, the aforesaid reference value is derived by generating a difference voltage corresponding to the difference of the voltages at the neutral point of the frequency converter circuit and the neutral point of the load. This difference voltage is then passed through a delay member whose time constant corresponds to the time constant of the load to develop the reference value.

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.

Static converter circuit - has two converters with series outputs and composite output voltages amplitude altered by phase difference

Abstract: The static converter circuit has two thyristor bridge converters with their inputs coupled in parallel to the phase network supply and their outputs coupled in series to form a composite output voltage. The composite output voltage's amplitude is altered by altering the phase difference between the output voltages of the two separate converters. The amplitudes of the separate converters are fixed at a constant level. The advantage of using the phase difference to alter the output amplitude lies in its having only a very small back effect on the supply.

DC-DC conversion

Abstract: In aerospace and satellite application, emphasis on the design of dc-dc converters has been concentrated in the reduction of the size, weight, and cost, and in the improvement of the efficiency and reliability of the converters. This session consists of six papers of which five papers discuss various practical design aspects of the converters for achieving one or more of the above goals. One paper discusses some theoretical aspects of the converters.

Overcurrent protection in pulse-width controlled DC-to-DC converters

Abstract: A current-limiting circuit for use in pulse width controlled dc-to-dc converters is described. This circuit ensures reliable converter operation by providing device protection against various transient overcurrent stresses as well as against output overload conditions.