Self-damped inductor

• US 7,317,374 B2
• Filed: 01/02/2004
• Issued: 01/08/2008
• Est. Priority Date: 01/03/2003
• Status: Expired due to Fees

• Current Assignee: Nu-Core, Inc.
• Original Assignee: Nu-Core, Inc.
• Inventors: Flanders, Andrew E., Judah, Bradley E., Bartha, Andrew
• Primary Examiner(s): MAI, ANH T
• Application Number:
  US10/750,214
• Publication Number:
  US 20040207503A1
• Time in Patent Office: 1,467 Days
• Field of Search: 336182-183, 336/180, 336/212, 336/92, 336220-222, 381/110, 381/111, 381/99, 381/94.1
• US Class Current: 336/220
• CPC Class Codes: H01F 17/045 with core of cylindric geometry and coil wound along its longitudinal axis, i.e. rod or drum core
• CPC Class Codes: H01F 2027/348 Preventing eddy currents
• CPC Class Codes: H01F 21/08 by varying the permeability of the core, e.g. by varying magnetic bias
• CPC Class Codes: H01F 27/24 Magnetic cores
• CPC Class Codes: H01F 29/146 Constructional details
• CPC Class Codes: H01F 3/08 made from powder powder coatings on sheets H01F3/02; on strips or ribbons H01F3/04; on wires H01F3/06
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H01F 30/06 characterised by the structure
• CPC Class Codes: H01F 38/023 of inductances
• CPC Class Codes: H03H 2001/0092 Inductor filters, i.e. inductors whose parasitic capacitance is of relevance to consider it as filter

Abstract

An inductor with self-damping properties for use in multiple applications including for high power broadband frequency applications is provided by a coil having an input end and an output end and wound about a core of magnetically permeable material and an eddy current generator incorporated either at the time of manufacture or post manufacturing. The core can be air (e.g., a hollow coil of wire). Alternative core materials are iron, iron powder, steel laminations and other appropriate materials. The core may be incorporated into some form of frame whether I shaped, U shaped, E shaped or of an encapsulated shape arrangement. The inductor'"'"'s Q value may be changed selectively by deliberately inducing eddy currents in preferred locations. The eddy currents are induced into the inductors and have the effect of introducing a back EMF which is designed and scaled appropriately to adjust the Q value at the desired frequency resulting is less phase distortion. When phase “distortion” is minimized, waveform is necessarily well preserved. The listener then observes improved clarity, identity, vitality and intelligibility. The phase angle within the response band depends on the roll-off or roll-up slope, be it a 1^st, 2^nd or 3^rd order. One self damped inductor includes an iron double “E” core inductor carrying a primary coil of insulated copper wire wound around an iron core. Core is formed by the central leg of an “E” frame pair and carries an eddy current generating winding implemented by winding an electrically conductive insulated and isolated secondary coil around the outside of the primary winding. An electrical connection is established between the two ends of the secondary coil. The secondary coil preferably comprises a single turn of wire but may consist of a thicker gauge wire or of multiple turns if it is desirable to increase the magnitude of the eddy currents generated.

Claims

1. A damped electromagnetic inductor device, comprising:

at least one primary coil formed of a continuous conductor having first and second terminal ends, each primary coil having a helical winding section wound around an interior space, said at least one primary coil capable of producing magnetic field lines, wherein the interior space is intersected by said primary coil magnetic field lines;

at least one secondary closed loop formed of a continuous conductor and being electrically insulated from said primary coil, said secondary closed loop having a section wound around said interior space, said secondary closed loop capable of producing eddy currents in response to said primary coil magnetic field lines; and

wherein said secondary closed loop continuous conductor comprises a single closed cylindrical loop made from a conductive sheet.

2. The damped electromagnetic inductor device of claim 1, wherein said at least one secondary closed loop conductive sheet is disposed within the interior of said at least one primary coil.

3. The damped electromagnetic inductor device of claim 2, further comprising:

a magnetically permeable core dimensioned to fit within said interior space, said core carrying (a) said primary coil'"'"'s magnetic flux and (b) flux induced from eddy currents induced in said closed loop when current flows through said primary coil.

4. The damped electromagnetic inductor device of claim 3, wherein said magnetically permeable core is made of iron.

5. The damped electromagnetic inductor device of claim 1, wherein said at least one secondary closed loop conductive sheet is disposed around the exterior of said at least one primary coil.

6. The damped electromagnetic inductor device of claim 5, further comprising:

a magnetically permeable core dimensioned to fit within said interior space, said core carrying (a) said primary coil'"'"'s magnetic flux and (b) flux induced from eddy currents induced in said closed loop when current flows through said primary coil.

7. A damped electromagnetic inductor device, comprising:

at least one primary coil formed of a continuous conductor having first and second terminal ends, each primary coil having a helical winding section wound around an interior space, said at least one primary coil capable of producing magnetic field lines, wherein the interior space is intersected by said primary coil magnetic field lines;

at least one secondary closed loop formed of a continuous conductor and being electrically insulated from said primary coil, said secondary closed loop having a section wound around said interior space, said secondary closed loop capable of producing eddy currents in response to said primary coil magnetic field lines wherein said magnetically permeable frame comprises first and second encapsulating flux conductive frames,

said first flux conductive frame having a substantially hemispherical or bowl-shaped outer wall encircling an annular interior space that surrounds a first central core projecting into the frame'"'"'s interior, said central core being aligned along a central axis and terminating in a distal core end;

said second flux conductive frame also having a substantially hemispherical or bowl-shaped outer wall encircling an annular interior space that surrounds a second central core projecting into the second frame'"'"'s interior, said second central core being aligned along a central axis and terminating in a second distal core end;

wherein said first flux conductive frame and said second flux conductive frame are releasably juxtaposed together such that the first and second outer walls engage one another to define an enclosed interior volume dimensioned to receive said first coil and said second coil;

said first and second central cores being substantially coaxially aligned to carry said primary coil and said secondary closed loop; and

wherein said first central core'"'"'s distal end engages said second central core'"'"'s distal end to provide a substantially continuous flux path through said first and second central cores and through said first frame'"'"'s wall and said second frame'"'"'s wall.

8. The damped electromagnetic inductor device of claim 7, wherein said first and second encapsulating flux conductive frames define substantially continuous outer wall surfaces meeting in a tight seam, and

wherein said primary coil'"'"'s first and second terminals comprise flexible conductors brought outside of the enclosed interior volume through at least a first aperture in one of said first frame'"'"'s wall and said second frame'"'"'s wall.

9. The damped electromagnetic inductor device of claim 7, wherein said magnetically permeable frame is made of iron.