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In the past few years there has been a need to improve the density of power conversion systems. This need is met by increasing the operating frequency of power converters from hundreds of kilohertz to tens of megahertz. The development of higher frequency power converters has been limited by the control integrated circuits, magnetics, capacitors , and an anticipated lower conversion efficiency.
Thick-film hybrid technology is employed to fabricate a zero-current-switched, half-bridge, quasi-resonant converter for 300V dc off-line application. With a conversion frequency of 2MHz the converter delivers 80W at a power density of 21W/cu.in. This paper describes the theory of operation, detailed design rules and benefits of hybridization. Also described is a 2MHz hybridized gate drive.
Because of their tolerance of transformer non-idealities, resonant converters appear well-suited to high voltage applications. In this paper, the series and parallel resonant topologies, as well as a newly discovered hybrid resonant topology are compared for high voltage applications. Design criteria which incorporate transformer nonidealities are deloped, and are employed in the construction of high...
A series of multiple output, 500 Watt, dc-dc converter boards for use in a 3kW computer power system is described. High power-density (9 Watts/cu.in. including heatsinks) is achieved through the use of thick film hybrid modules and a 316kHz switching frequency. The system considerations, design tradeoffs, and problems encountered are described. Future considerations for further enhancements to performance...
Damage to a transistor is prevented during testing by turning on its base simultaneously with the onset of reverse biased second breakdown. Test data is similiar to that obtained with crowbar circuits. Repetitive observation is possible, but after about 10,000 test cycles, some transistors show degradation above Ic = 1A.
The SPICE PLUS simulation program offers circuit designers full capability for simulating magnetic cores used in power supplies and in other power design circuits. This paper is an overview of the model, its capabilities, and application. The magnetic model defines both major and minor hysteresis loops, which are derived from the dynamic relationship between magnetic flux density and magnetic field...
A small-signal equivalent circuit which models the frequency-domain behavior of magneticamplifier- controlled switched-mode converters operating in the continuous-mmf mode is presented. The equivalent circuit, which is based upon stateaveraging techniques, can be used with a circuitanalysis program such as SPICE to evaluate the frequency-domain behavior of a magneticamplifier- controlled converter...
The APEC '88 will address the practical application of new components and circuits, design-oriented analysis techniques and current trends in the design and manufacturing of power electronic products and systems.
A computer model of a buck switching regulator has been developed without any approximation that would limit its use to small signal perturbations and small load changes. The model can show the regulator's responses to a wide variety of disturbances. The regulator's transient and steady state responses to these disturbances can then be optimized by varying the voltage and current gains and/or including...
The half-bridge series resonant, parallel resonant and combination series-parallel resonant converters are compared for use in low output voltage power supply applications. It is shown that the combination series-parallel converter, which takes on the desirable characteristics of the pure series and the pure parallel converter, removes the main disadvantages of those two converters. Analyses and breadboard...
The waveforms of a square-wave and a quasi-resonant dc-dc converter are examined in detail so that a comparison between the switching and conduction losses for each topology can be made. Using data from commercially available semiconductor devices, conservative estimates are then given for the switching frequency at which the resonant approach becomes advantageous. The effect of an isolation transformer...
Power circuits must operate within safe limits to assure long-term reliability and prevent catastrophic failure. However, manual calculation of circuit operating conditions is both laborious and often inaccurate, and breadboard tests can be difficult and time consuming. This paper describes new CAE techniques to automatically evaluate the operating conditions of the components in a power circuit by...
Magnetic amplifiers post regulators are often used in multiple output power supplies to achieve independent regulation of the additional outputs. This paper describes a method of constructing saturable reactor regulators which eliminates the square loop requirements and allows the use of magnetically soft materials. The resulting structure is tolerant of small gaps which allows construction using...
Clamp type transient suppressors are widely used to protect electronic equipment from damage during short periods of abnormal voltage on supply lines. However, the action of these suppressors, in conjunction with stray circuit elements, can induce secondary transient effects which may also disrupt equipment operation. This paper discusses the nature and origin of these secondary effects, and provides...
In view of the increased use of higher frequencies for switching power supply, a new amorphous saturable core for a high frequency magnetic amplifier has been developed. Its core loss is about one half of that for a conventional amorphous saturable core, and one third of that for an 80 Ni permalloy core with a high rectangular ratio. The newly developed amorphous saturable core has been actually operated...
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