CURRENT SENSORS USING MAGNETOSTRICTIVE MATERIAL

• US 20140132256A1
• Filed: 11/14/2013
• Published: 05/15/2014
• Est. Priority Date: 11/14/2012
• Status: Active Grant

• Current Assignee: UWM Research Foundation, Inc. (University of Wisconsin System)
• Original Assignee: UWM Research Foundation, Inc. (University of Wisconsin System)
• Inventors: Law, Chiu Tai, El-Hajjar, Rani
• Granted Patent: US 9,417,294 B2
• Time in Patent Office: Days
• US Class Current: 324/244.1
• CPC Class Codes: G01R 33/0327 with application of magnetostriction
• CPC Class Codes: G01R 5/00 Instruments for converting a single current or a single voltage into a mechanical displacement

Abstract

A current sensor device. The current sensor device includes a strain distribution converter; an optical fiber coupled with the strain distribution converter; and a magnetostrictive material associated with the strain distribution converter such that a change in shape of the magnetostrictive material causes a change in length of the optical fiber.

Claims

1. A current sensor device, comprising:

a strain distribution converter;

an optical fiber coupled with the strain distribution converter; and

a magnetostrictive material associated with the strain distribution converter such that a change in shape of the magnetostrictive material causes a change in length of the optical fiber.

2. The current sensor of claim 1, wherein the magnetostrictive material comprises Terfenol-D.

3. The current sensor of claim 1, wherein the optical fiber is embedded within the strain distribution converter.

4. The current sensor of claim 1, wherein the strain distribution converter comprises epoxy.

5. The current sensor of claim 1, wherein the magnetostrictive material comprises a rod having a first end and a second end with a long axis therebetween, wherein the optical fiber has a long axis, and wherein the long axis of the rod of magnetostrictive material is parallel to the long axis of the optical fiber.

6. The current sensor of claim 5, wherein the strain distribution converter comprises a tapered portion having a narrow end opposite a wide end, and wherein the first end of the rod of magnetostrictive material abuts the narrow end of the tapered portion of the strain distribution converter.

7. The current sensor of claim 6, wherein the wide end of the strain distribution converter and the second end of the magnetostrictive material are maintained at a fixed distance relative to one another such that changes in size of the magnetostrictive material along the long axis cause changes in a length of the strain distribution converter between the narrow end and the wide end.

8. The current sensor of claim 7, wherein an increase in size of the magnetostrictive material along the long axis causes a decrease in length of the strain distribution converter between the narrow end and the wide end.

9. The current sensor of claim 8, wherein the decrease in length of the strain distribution converter between the narrow end and the wide end is non-linear.

10. The current sensor of claim 9, wherein the decrease in length of the strain distribution converter is greater at the narrow end.

11. The current sensor of claim 10, further comprising a non-magnetostrictive sleeve surrounding the rod of magnetostrictive material, wherein the non-magnetostrictive sleeve comprises a material having a similar coefficient of thermal expansion as the magnetostrictive material.

12. The current sensor of claim 7, wherein the wide end of the strain distribution converter and the second end of the magnetostrictive material are maintained at a fixed distance relative to one another by a pair of supports.

13. The current sensor of claim 12, further comprising

a second tapered strain distribution converter having a narrow end and a wide end, the wide end of the second tapered strain distribution converter attached to one of the pair of supports, and

a second rod comprising a non-magnetostrictive material having a similar coefficient of thermal expansion as the magnetostrictive material, the second rod having a first end and a second end, the first end of the second rod attached to the narrow end of the second tapered strain distribution converter and the second end of the second rod attached to the other of the pair of supports.

14. The current sensor of claim 1, wherein the magnetostrictive material is embedded within the strain distribution converter.

15. The current sensor of claim 14, wherein the strain distribution converter comprises

a first end opposite a second end, and

a gradation of magnetostrictive material between the first end and the second end.

16. The current sensor of claim 15, wherein the gradation of magnetostrictive material comprises a continuous gradient.

17. The current sensor of claim 15, wherein the gradation of magnetostrictive material comprises a stepwise gradient.

18. The current sensor of claim 15, wherein the gradation of magnetostrictive material comprises a gradation of particle sizes ranging in size from about 20 micrometers to about 300 micrometers.

19. The current sensor of claim 15, wherein the gradation of magnetostrictive material comprises a range of volume fractions.

20. The current sensor of claim 15, wherein the first end of the strain distribution converter comprises a greater amount of magnetostrictive material than the second end of the strain distribution converter.

21. The current sensor of claim 15, further comprising a magnetic core having an air gap, wherein the strain distribution converter is disposed within the air gap of the magnetic core.

22. The current sensor of claim 1, wherein the optical fiber comprises a fiber Bragg grating.

23. A current sensor device, comprising:

a strain distribution converter; and

a magnetostrictive material associated with the strain distribution converter such that a change in shape of the magnetostrictive material causes a change in shape of the strain distribution converter.

24. The current sensor of claim 23, wherein the strain distribution converter comprises a composite comprising the magnetostrictive material.

25. The current sensor of claim 24, wherein the composite has a speckle pattern.

26. The current sensor of claim 25, further comprising a camera for collecting a plurality of images of the speckle pattern.

27. The current sensor of claim 26, further comprising analyzing the plurality of images using a correlation algorithm to identify a change in shape of the strain distribution converter.