Apparatus and method for balancing electrical currents in a multiple-phase system
AssigneeSouthwest Electric Company
InventorDonald W. Owen
Life of this patent
Estimating the term…
Abstract
A current balancer for balancing one or more currents provided from a three-phase source to a load includes three current transformer/full-wave rectifier bridge sections and one or more saturable core reactors. Each of the current transformer/full-wave rectifier bridge sections is to be connected to a respective one of the phase lines, and a saturable core reactor is to be connected into each phase line whose current is to be controlled. The outputs of all three current transformer/full-wave rectifier bridge sections are connected in electrical parallel to provide a single direct current control current to the saturable core reactor(s).
Claims21
An apparatus for balancing current to a load in an electrical system which provides multiple phases of alternating current, said apparatus comprising:
- control current means, responsive to multiple phases of alternating current of an electrical system, for providing a single control current proportional to an average of all the multiple phases of alternating current;
- and
- variable impedance means, connected to said control current means, for providing a current conductive path for a phase of alternating current, said current conductive path having an impedance automatically variable in response to said single control current so that a phase of alternating current flowing along said current conductive path is balanced relative to the remaining phases of alternating current in response to the variable impedance.
An apparatus for balancing current to a load in an electrical system including first, second and third phases of alternating current, said apparatus comprising:
- first converter means for converting a first phase of alternating current into a first direct current;
- second converter means for converting a second phase of alternating current into a second direct current;
- third converter means for converting a third phase of alternating current into a third direct current;
- and
- variable impedance means, electrically connected to said first, second and third converter means so that said first, second and third direct currents are provided in combination to said variable impedance means as a control current, for conducting the first phase alternating current through a variable impedance responsive to said control current.
An apparatus for balancing currents in a three-phase electrical system including first, second and third phase current conductors, said apparatus comprising:
- first control means, including means for connecting to a first phase current conductor, for providing a first rectified current in response to a first phase current flowing through the first phase current conductor;
- second control means, including means for connecting to a second phase current conductor, for providing a second rectified current in response to a second phase current flowing through the second phase current conductor;
- third control means, including means for connecting to a third phase current conductor, for providing a third rectified current in response to a third phase current flowing through the third phase current conductor;
- first variable impedance means, including means for connecting to the first phase current conductor, for providing a variable impedance in electrical series with the first phase current conductor in response to a control current;
- second variable impedance means, including means for connecting to the second phase current conductor, for providing a variable impedance in electrical series with the second phase current conductor in response to said control current;
- third variable impedance means, including means for connecting to the third phase current conductor, for providing a variable impedance in electrical series with the third phase current conductor in response to said control current;
- and
- said first, second and third control means electrically connected in electrical parallel across said first, second and third variable impedance means so that said first, second and third rectified currents flow through said first, second and third variable impedance means to define said control current.
A method of energizing a motor with balanced currents from a three-phase current source, which motor is connected to three phase lines of the current source, said method comprising the steps of:
- generating a first direct current in response to a first phase current from the current source;
- generating a second direct current in response to a second phase current from the current source;
- generating a third direct current in response to a third phase current from the current source;
- combining the first, second and third direct currents into a single control current;
- and
- controlling each of an impedance in a first phase line of the current source, an impedance in a second phase line of the current source and an impedance in a third phase line of the current source in response to the single control current so that the first, second and third phase currents of the first, second and third phase lines are balanced in response to the single control current.
Dependencies are inferred from the claim text.