Sensing current flowing through a power line

• US 20080007416A1
• Filed: 07/07/2006
• Published: 01/10/2008
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ambient S A
• Inventors: Cern, Yehuda
• Granted Patent: US 8,093,745 B2
• Time in Patent Office: Days
• US Class Current: 340/664
• CPC Class Codes: G01R 15/14 Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
• CPC Class Codes: G01R 23/06 by converting frequency into an amplitude of current or voltage

Abstract

There is provided a method for measuring a parameter of a power frequency current being carried by a power line. The method that includes (a) transducing a power frequency current flowing through a power line, into a power frequency voltage, via an inductive coupler that couples a communications signal from the power line, (b) separating the power frequency voltage from the communications signal, and (c) determining a value of a parameter of the power frequency current from the power frequency voltage. There is also provided a system and an apparatus for measuring the parameter.

Claims

1. A method comprising:

transducing a power frequency current flowing through a power line, into a power frequency voltage, via an inductive coupler that couples a communications signal from said power line;

separating said power frequency voltage from said communications signal; and

determining a value of a parameter of said power frequency current from said power frequency voltage.

2. The method of claim 1,

wherein said inductive coupler includes:

(a) a magnetic core having an aperture therethrough, wherein said power line is routed through said aperture and serves as a primary winding for said inductive coupler; and

(b) a secondary winding wound around a portion of said magnetic core, wherein said power frequency voltage is induced across said secondary winding.

3. The method of claim 1, wherein said separating comprises passing said power frequency voltage through a filter that blocks said communications signal.

4. The method of claim 3,

wherein said communications signal is routed to a circuit that passes said communications signal and blocks said power frequency voltage, and

wherein said method further comprises:

routing said power frequency voltage around said circuit;

multiplexing said power frequency voltage and said communications signal together, downstream of said circuit, to yield a multiplexed signal; and

demultiplexing said multiplexed signal, prior to said determining.

5. The method of claim 1, wherein said power frequency voltage has a frequency in a range of about 50-60 Hz, and said communications signal has a frequency of greater than about 1 MHz.

6. The method of claim 1, wherein said parameter is selected from the group consisting of (a) a magnitude of said power frequency current, and (b) a phase of said power frequency current, with respect to a reference phase.

7. The method of claim 1, further comprising,

modulating said value onto a resultant communication signal;

and

coupling said resultant communication signal to said power line, via said inductive coupler.

8. The method of claim 1,

wherein said inductive coupler includes

(a) a magnetic core having an aperture therethrough, wherein said power line is routed through said aperture and serves as a primary winding for said inductive coupler;

and

(b) a secondary winding wound around a portion of said magnetic core, wherein said coupled signal is induced across said secondary winding,

wherein said separating comprises passing said power frequency voltage through a filter that blocks said communications signal, and

wherein said method further comprises;

modulating said value onto a resultant communications signal; and

routing said resultant communications signal to said inductive coupler.

9. A system comprising:

an inductive coupler that (a) couples a communications signal from a power line, and (b) transduces a power frequency current flowing through said power line, into a power frequency voltage;

a filter that separates said power frequency voltage from said communications signal; and

a processor that determines a value of a parameter of said power frequency current from said power frequency voltage.

10. The system of claim 9,

wherein said inductive coupler includes:

(a) a magnetic core having an aperture therethrough, wherein said power line is routed through said aperture and serves as a primary winding for said inductive coupler; and

(b) a secondary winding wound around a portion of said magnetic core, wherein said value of a parameter of said power frequency current from said power frequency voltage is induced across said secondary winding.

11. The system of claim 9, wherein said filter passes said power frequency voltage and blocks said communications signal.

12. The system of claim 11,

wherein said communications signal is routed to a circuit that passes said communications signal and blocks said power frequency voltage, and

wherein said system further comprises:

a bypass module that routes said power frequency voltage around said circuit;

an arrangement that multiplexes said power frequency voltage and said communications signal together, downstream of said circuit, to yield a multiplexed signal; and

an arrangement that demultiplexes said multiplexed signal so that said processor can determine said value.

13. The system of claim 9, wherein said power frequency voltage has a frequency in a range of about 50-60 Hz, and said communications signal has a frequency of greater than about 1 MHz.

14. The system of claim 9, wherein said parameter is selected from the group consisting of (a) a magnitude of said power frequency current, and (b) a phase of said power frequency current, with respect to a reference phase.

15. The system of claim 9, further comprising:

a modulator that modulates said value onto a resultant communications signal,

wherein said system couples said resultant communications signal to said power line, via said inductive coupler.

16. The system of claim 9,

wherein said inductive coupler includes

(a) a magnetic core having an aperture therethrough, wherein said power line is routed through said aperture and serves as a primary winding for said inductive coupler;

and

(b) a secondary winding wound around a portion of said magnetic core, wherein said coupled signal is induced across said secondary winding,

wherein said filter passes said power frequency voltage and blocks said communications signal,

wherein said system further comprises a modulator that modulates said value onto a resultant communications signal, and

wherein said system couples said resultant communications signal to said power line, via said inductive coupler.

17. An apparatus comprising:

a filter that separates a power frequency voltage from a communication signal that is coupled, via an inductive coupler, from a power line that carries a power frequency current; and

a processor that determines a value of a parameter of said power frequency current from said power frequency voltage.

18. The apparatus of claim 17, wherein said filter passes said power frequency voltage and blocks said communications signal.

19. The apparatus of claim 17, wherein said power frequency voltage has a frequency in a range of about 50-60 Hz, and said communications signal has a frequency of greater than about 1 MHz.

20. The apparatus of claim 17, further comprising a modulator that modulates said value onto a resultant communications signal for coupling to said power line via said inductive coupler.