Electro-magnetic kinetic energy harvesting device using increased magnetic edge area

• US 7,948,124 B1
• Filed: 09/21/2009
• Issued: 05/24/2011
• Est. Priority Date: 01/28/2009
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Dick, Brian, Jazo, Hugo, Kerber, Max, Fralick, Mark, Waters, Richard
• Primary Examiner(s): NGUYEN, HANH N
• Application Number:
  US12/563,932
• Time in Patent Office: 610 Days
• Field of Search: 310/15, 310/36, 310/40.MM
• US Class Current: 310/36
• CPC Class Codes: H02K 35/00 Generators with reciprocating, oscillating or vibrating coil system, magnet, armature or other part of the magnetic circuit arrangements for handling mechanical energy structurally associated with generators H02K7/00, e.g. H02K7/06

Abstract

An energy harvesting apparatus comprising: a substrate; two magnets coupled to the substrate in close proximity to each other with like magnetic poles facing each other creating a flux gap; a coil coupled to the substrate and disposed within the flux gap, wherein the coil and the magnets are coupled to the substrate such that substrate acceleration causes relative motion between the magnets and the coil thereby exposing the coil to a changing magnetic flux.

Claims

1. An energy harvester comprising:

a substrate;

two magnets coupled to the substrate in close proximity to each other with like magnetic poles facing each other creating a flux gap;

a coil coupled to the substrate and disposed within the flux gap, wherein the coil and the magnets are coupled to the substrate such that substrate acceleration causes relative motion between the magnets and the coil thereby exposing the coil to a changing magnetic flux; and

wherein at least one of the magnets comprises at least one through-hole.

2. The energy harvester of claim 1, wherein both magnets comprise a plurality of through-holes and wherein the through-holes of each magnet are coaxially aligned with the through-holes in the opposing magnet.

3. The energy harvester of claim 2, further comprising a plurality of sub-coils positioned in the flux gap, one sub-coil being coaxially aligned with each set of coaxial through-holes.

4. The energy harvester of claim 1, wherein the magnets are Neodymium permanent magnets.

5. The energy harvester of claim 1, wherein each magnet has a face disposed in a xy plane and a length in a z direction, and wherein the coil is wrapped around a perimeter of each face and along the lengths of the magnets.

6. The energy harvester of claim 1, wherein each magnet comprises a length in a z direction and two faces in an xy plane.

7. The energy harvester of claim 6, wherein the coil is disposed in the xy plane and extends into a space between the opposing faces of the two magnets.

8. The energy harvester of claim 7, further comprising an edge coil, wherein the edge coil is wrapped around the edges of the magnets over substantially the entire lengths of the magnets.

9. The energy harvester of claim 6, further comprising two peripheral coils, one peripheral coil disposed parallel to and in close proximity to each non-opposing face.

10. The energy harvester of claim 6, wherein the profile of at least one magnet in the xy plane comprises edge-surface-area enhancements comprising alternating indentations and protrusions.

11. The energy harvester of claim 10, wherein the profiles in the xy plane of both magnets comprise mutually-aligned and substantially matching edge-surface-area enhancements.

12. The energy harvester of claim 1, wherein the facing magnetic poles are both North poles.

13. The energy harvester of claim 1, wherein the coil is disposed on a micro-electro-mechanical spring mass system that is elastically coupled to the substrate.

14. The energy harvester of claim 13, further comprising a proof mass coupled to the coil.

15. An energy harvester comprising:

a substrate;

two magnets coupled to the substrate in close proximity to each other with like magnetic poles facing each other creating a flux gap;

a coil coupled to the substrate and disposed within the flux gap, wherein the coil and the magnets are coupled to the substrate such that substrate acceleration causes relative motion between the magnets and the coil thereby exposing the coil to a changing magnetic flux; and

wherein each magnet is comprised of a plurality of polarly like-oriented sub-magnets disposed in close proximity to each other with interstices there-between such that the flux density in the flux gap is increased.

16. The energy harvester of claim 15, further comprising a plurality of sub-coils positioned in the flux gap, one sub-coil being disposed near each interstice.

17. The energy harvester of claim 16, wherein the contours of each sub-coil substantially match the contours of the corresponding interstice.

18. A micro energy harvester comprising:

a micro-fabricated substrate;

two magnets coupled to the substrate in close proximity to each other with like magnetic poles facing each other creating a flux gap, wherein at least one of the magnets further comprises at least one through-hole thereby creating regions of high flux density in the flux gap around the at least one through-hole and the edges of the magnets; and

a plurality of micro-fabricated coils coupled to the substrate and disposed within the flux gap, wherein the coils and the magnets are coupled to the substrate such that substrate acceleration causes relative motion between the magnets and the coils thereby exposing the coils to a changing magnetic flux, and wherein at least one coil is positioned in each region of high flux density.

19. The micro energy harvester of claim 18, wherein the profile of at least one magnet comprises edge-surface-area enhancements comprising alternating indentations and protrusions.