Folding current sensor

• US 7,936,164 B2
• Filed: 07/03/2008
• Issued: 05/03/2011
• Est. Priority Date: 07/03/2008
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Dickinson, Richard, Taylor, William P., Doogue, Michael C.
• Primary Examiner(s): Velez; Roberto
• Application Number:
  US12/167,681
• Publication Number:
  US 20100001715A1
• Time in Patent Office: 1,034 Days
• Field of Search: 324/117.H, 324/126, 324/127, 324/117.R
• US Class Current: 324/117.00H
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used

Abstract

The invention provides a current sensor that may be folded over a conductor without the need to sever the conductor or thread the conductor through the current sensor. In one embodiment, the current sensor includes an outer body having a first folding portion and a second folding portion coupled to the first folding portion. The current sensor also includes a soft ferromagnetic body disposed within the outer body comprising a first core element and a second core element. The first and second core elements form a lumen when the first and second folding portions are folded. The lumen is configured to receive a conductor. The current sensor also includes a magnetic field detector to sense a current in the conductor. The magnetic field detector is disposed at least partially between the first and second core elements when the first and second folding portions are folded.

Claims

1. A current sensor comprising:

a soft ferromagnetic body forming a lumen configured to receive a conductor, the soft ferromagnetic body having first and second folding portions configured to fold, unfold, and to enclose the conductor within the lumen; and

a magnetic field detector having at least a portion disposed within a gap extending along at least a portion of a longitudinal length of the soft ferromagnetic body when the first and second folding portions are folded, a first surface of the magnetic field detector in contact with a surface of a first extension of the first folding portion, the first extension extending from a longitudinal surface of the first folding portion within the gap leaving an area of the longitudinal surface of the first folding portion within the gap uncovered, and a second surface of the magnetic field detector opposing the first surface of the magnetic field detector in contact with a surface of a second extension of the second folding portion, the second extension extending from a longitudinal surface of the second folding portion within the gap leaving an area of the longitudinal surface of the second folding portion within the gap uncovered.

2. The current sensor of claim 1, further comprising a rotator element to rotatably couple the first and second folding portions of the soft ferromagnetic body, wherein the portion of the magnetic field detector is disposed within a side of the soft ferromagnetic body opposite to the rotator element.

3. The current sensor of claim 1, wherein a recess is formed in one of the folding portions and the magnetic field detector has at least a portion disposed between the recess and the other of the folding portions.

4. The current sensor of claim 1, wherein the first folding portion is adjacent to the second folding portion in an area adjacent to the magnetic field detector when the conductor is enclosed in the lumen.

5. The current sensor of claim 1, wherein a first recess is formed in the first folding portion, a second recess is formed in the second folding portion, and the magnetic field detector has at least a portion disposed within the first and second recesses.

6. The current sensor of claim 1, wherein the magnetic field detector comprises:

a magnetic field transducer; and

a magnetic field concentrator in proximity to the magnetic field transducer.

7. The current sensor of claim 1, wherein a width of the first extension is equal to a width of the magnetic field detector and a width of the second extension is equal to the width of the magnetic field detector.

8. The current sensor of claim 1, wherein the first extension tapers towards the magnetic field detector and the second extension tapers towards the magnetic field detector.

9. A current sensor comprising:

an outer body having a first folding portion and a second folding portion configured to fold and unfold, wherein the second folding portion is coupled to the first folding portion;

a soft ferromagnetic body disposed within the outer body and comprising a first core element and a second core element, the first and second core elements forming a lumen when the first and second folding portions are folded, the lumen configured to receive a conductor; and

a magnetic field detector to sense a current in the conductor, the magnetic field detector having at least a portion disposed between the first and second core elements in a gap extending along at least a portion of a longitudinal length of the soft ferromagnetic body when the first and second folding portions are folded, a first surface of the magnetic field detector in contact with a surface of a first extension of the first core element, the first extension extending from a longitudinal surface of the first core element within the gap leaving an area of the longitudinal surface of the first core element within the gap uncovered, and a second surface of the magnetic field detector opposing the first surface of the magnetic field detector in contact with a surface of a second extension of the second core element, the second extension extending from a longitudinal surface of the second core element within the gap leaving an area of the longitudinal surface of the second core element within the gap uncovered.

10. The current sensor of claim 9, further comprising a rotator element to rotatably couple the first and second folding portions of the outer body.

11. The current sensor of claim 10, wherein the portion of the magnetic field detector is disposed in a side of the soft ferromagnetic body opposite to the rotator element.

12. The current sensor of claim 9, wherein the soft ferromagnetic body comprises a material selected from the group consisting of a ferrite material, steel, iron alloy, NiFeMo, Supermalloy, a nickel alloy, a cobalt alloy, and Permalloy.

13. The current sensor of claim 9, wherein at least one of the first and second extensions is tapered in a direction towards the magnetic field detector.

14. The current sensor of claim 9, wherein a recess is formed in one of the folding portions and the magnetic field detector has at least a portion disposed between the recess and the other of the folding portions.

15. The current sensor of claim 9, wherein a first recess is formed in the first core element and a second recess is formed in the second core element, and the magnetic field detector has at least a portion disposed within the first and second recesses.

16. The current sensor of claim 9, wherein the magnetic field detector comprises:

a magnetic field transducer; and

at least one magnetic field concentrator in proximity to the magnetic field transducer.

17. The current sensor of claim 16, wherein the magnetic field transducer is one of a Hall effect element, a giant magnetoresistance element, or an anisotropic magnetoresistance element.

18. The current sensor of claim 9, wherein the magnetic field detector comprises a package comprising:

a magnetic field transducer; and

a magnetic field concentrator comprised of a soft magnetic material and positioned in proximity to the magnetic field transducer.

19. The current sensor of claim 18, wherein the package further comprises:

a insulator layer disposed between the magnetic field transducer and the magnetic field concentrator.

20. The current sensor of claim 9, wherein the magnetic field detector is flush-mounted with respect to the outer body and comprises at least one bent lead.

21. The current sensor of claim 9, wherein the conductor comprises at least one loop.

22. The current sensor of claim 9, wherein the soft ferromagnetic body is a tube having an outer surface coupled to the outer body, and an inner surface forming the lumen, the outer and inner surfaces defining a wall of the tube along a length of the tube, the first and second core elements coupled along the wall adjacent to at least one rotator element when the first and second core elements are folded.

23. The current sensor of claim 22, wherein the tube has a c-shaped cross-section such that the first and second core elements are not in contact along the wall of the tube opposing the at least one rotator element.

24. The current sensor of claim 22, wherein the first and second core elements are in contact along at least one portion of the wall of the tube opposing the at least one rotator element.

25. A method comprising:

providing a soft ferromagnetic body having first and second folding portions configured to fold and unfold and a magnetic field detector coupled to one of the first and second folding portions;

folding the first and second folding portions of the soft ferromagnetic body to form a lumen to receive a conductor carrying a current and to form a gap extending along at least a portion of a longitudinal length of the soft ferromagnetic body, wherein at least a portion of the magnetic field detector is disposed within the gap, a first surface of the magnetic field detector in contact with a surface of a first extension of the first folding portion, the first extension extending from a longitudinal surface of the first folding portion within the gap leaving an area of the longitudinal surface of the first folding portion within the gap uncovered, and a second surface of the magnetic field detector opposing the first surface of the magnetic field detector in contact with a surface of a second extension of the second folding portion, the second extension extending from a longitudinal surface of the second folding portion within the gap leaving an area of the longitudinal surface of the second folding portion within the gap uncovered; and

sensing the current carried in the conductor with the magnetic field detector.

26. The method of claim 25, further comprising rotatably coupling the first and second folding portions of the soft ferromagnetic body, wherein folding further comprises rotating the first and second folding portions until the portion of the magnetic field detector is disposed on a side of the soft ferromagnetic body opposing the rotator element.

27. The method of claim 26, further comprising securing the folded first and second folding portions with a securing body.