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Title: Method and apparatus for controlling current in inductive loads such as large diameter coils

Abstract

A method and apparatus for controlling electric current in loads that are essentially inductive, such that sparking and "ringing" current problems are reduced or eliminated. The circuit apparatus employs a pair of solid state switches (each of which switch may be an array of connected or parallel solid state switching devices such as transistors) and means for controlling those switches such that a power supply supplying two d.c. voltages (e.g. positive 150 volts d.c. and negative 150 volts d.c.) at low resistance may be connected across an essentially inductive load (e.g. a 6 gauge wire loop one hundred meters in diameter) alternatively and such that the first solid state switch is turned off and the second is turned on such that both are not on at the same time but the first turned on and the other on in less time than the inductive time constant (L/R) so that the load is essentially always presented with a low resistance path across its input. In this manner a steady AC current may be delivered to the load at a frequency desired. Shut-off problems are avoided by gradually shortening the period of switching to less than the time constant so that themore » maximum energy contained in the inductive load is reduced to approximately zero and dissipated in the inherent resistance. The invention circuit may be employed by adjusting the timing of switching to deliver a desired waveform (such as sinusoidal) to the load.« less

Inventors:
 [1]
  1. (3832 Harrison Ave., Brookfield, IL 60513)
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
863925
Patent Number(s):
4276484
Assignee:
Riveros, Carlos A. (3832 Harrison Ave., Brookfield, IL 60513) LLNL
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
method; apparatus; controlling; current; inductive; loads; diameter; coils; electric; essentially; sparking; ringing; reduced; eliminated; circuit; employs; pair; solid; switches; switch; array; connected; parallel; switching; devices; transistors; means; power; supply; supplying; voltages; positive; 150; volts; negative; resistance; load; gauge; wire; loop; hundred; meters; alternatively; time; constant; path; input; manner; steady; delivered; frequency; desired; shut-off; avoided; gradually; shortening; period; maximum; energy; contained; approximately; zero; dissipated; inherent; employed; adjusting; timing; deliver; waveform; sinusoidal; apparatus employs; inductive load; maximum energy; wire loop; switching devices; electric current; power supply; time constant; switching device; circuit apparatus; resistance path; inductive loads; desired wave; /307/324/361/

Citation Formats

Riveros, Carlos A. Method and apparatus for controlling current in inductive loads such as large diameter coils. United States: N. p., 1981. Web.
Riveros, Carlos A. Method and apparatus for controlling current in inductive loads such as large diameter coils. United States.
Riveros, Carlos A. Thu . "Method and apparatus for controlling current in inductive loads such as large diameter coils". United States. https://www.osti.gov/servlets/purl/863925.
@article{osti_863925,
title = {Method and apparatus for controlling current in inductive loads such as large diameter coils},
author = {Riveros, Carlos A.},
abstractNote = {A method and apparatus for controlling electric current in loads that are essentially inductive, such that sparking and "ringing" current problems are reduced or eliminated. The circuit apparatus employs a pair of solid state switches (each of which switch may be an array of connected or parallel solid state switching devices such as transistors) and means for controlling those switches such that a power supply supplying two d.c. voltages (e.g. positive 150 volts d.c. and negative 150 volts d.c.) at low resistance may be connected across an essentially inductive load (e.g. a 6 gauge wire loop one hundred meters in diameter) alternatively and such that the first solid state switch is turned off and the second is turned on such that both are not on at the same time but the first turned on and the other on in less time than the inductive time constant (L/R) so that the load is essentially always presented with a low resistance path across its input. In this manner a steady AC current may be delivered to the load at a frequency desired. Shut-off problems are avoided by gradually shortening the period of switching to less than the time constant so that the maximum energy contained in the inductive load is reduced to approximately zero and dissipated in the inherent resistance. The invention circuit may be employed by adjusting the timing of switching to deliver a desired waveform (such as sinusoidal) to the load.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1981},
month = {1}
}

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