METHODS AND APPARATUS FOR IMPROVING WINDING BALANCE ON INDUCTIVE DEVICES

Abstract

Improved balance winding of electronic components including common-mode chokes and methods for using and manufacturing the same. In one embodiment, the common-mode choke includes a core and a pair of windings. The first winding and the second winding are alternatingly wound around the core with each respective winding being flipped at least once over the traverse direction of the winding barrel of the core. In one variant, the number of flips is dependent upon the core geometry, number of windings, and/or the specification limits on electrical balance. In another variant, the windings are first twisted and/or braided prior to being wound onto the winding barrel of the core.

Claims

1.-20. (canceled)

21. A common-mode choke, comprising: a core comprising a winding barrel with two flanges disposed at opposing ends of the winding barrel; a first winding; and a second winding; wherein at least the first winding and the second winding are twisted about each other to produce a twisted winding; and wherein the twisted winding is wound around the winding barrel.

22. The common-mode choke of claim 21, wherein ends of the first winding are secured to respective first terminations resident on each of the two flanges, and ends of the second winding are secured to respective second terminations resident on each of the two flanges.

23. The common-mode choke of claim 22, wherein the respective first and second terminations are each disposed on respective ones of a plurality of corners of the two flanges.

24. The common-mode choke of claim 22, wherein: the two flanges are each approximately rectangular in shape; the two approximately rectangular shaped flanges are disposed in a common angular orientation relative to a central axis of the winding barrel; and the first termination and second termination on each of the two flanges are disposed on a common side of the respective flange such that the common-mode choke can be surface mounted to a substrate with each of the first and second terminations disposed away from the substrate.

25. The common-mode choke of claim 21, wherein the twisted winding wound around the winding barrel comprises at least one additional winding is twisted with the first and second windings.

26. The common-mode choke of claim 21, wherein the twisted winding is associated with an electrical coupling that is more balanced as compared to a winding that is not twisted.

27. The common-mode choke of claim 21, wherein the core comprises an I-shaped magnetically permeable core.

28. An inductive device, comprising: a magnetically permeable core, the magnetically permeable core comprising a first flange, a second flange, and a central element disposed between and connecting the first and second flanges; and a braided winding wound around the central element, the braided winding comprising a first winding and a second winding braided together.

29. The inductive device of claim 28, wherein each end of the first and second windings of the braided winding is secured to a respective termination on the first and second flanges, the respective termination being one of four corresponding terminations.

30. The inductive device of claim 28, wherein the braided winding comprises at least a third winding braided with the first and second windings.

31. The inductive device of claim 30, wherein the first, second and third windings are comprised of a primary sub-group and a secondary sub-group; and wherein at least said primary and secondary sub-groups are at least partly braided such that at least a portion of the braided windings reside on at least three distinct levels relative to the central element.

32. The inductive device of claim 30, wherein the first, second and third windings are braided together over a given length; wherein the first, second and third are comprised of a plurality of braided portions and a plurality of braided portions; and wherein at least one of the non-braided portions resides between two adjacent braided portions

33. The inductive device of claim 28, wherein the braided winding is associated with an electrical coupling that is more uniform as compared to a non-braided winding made from the first winding and the second winding.

34. A common-mode choke, comprising: a core element comprising a winding barrel with two flanges disposed at opposing ends of the winding barrel; a first twisted winding comprising a first pair of windings twisted about each other; and a second twisted winding comprising a second pair of windings twisted about each other; wherein the first and second twisted windings are alternatingly wound about a first portion of the winding barrel in a given order; and wherein the first and second twisted windings are wound about second portion of the winding barrel in another order that is opposite of the given order.

35. The common-mode choke of claim 34, wherein the first and second twisted windings are disposed in a single layer around the winding barrel.

36. The common-mode choke of claim 34, wherein the first and second portions of the winding barrel are adjacent to each other, and the other order is caused by a flip of the given order of the winding of the first and second twisted windings.

37. The common-mode choke of claim 36, wherein the first and second twisted windings are alternatingly wound about a third portion of the winding barrel in the given order, the third portion and the second of the winding barrel being adjacent to each other.

38. The common-mode choke of claim 34, wherein, based on a plurality of flips of the first and second twisted windings, the first and second twisted windings are wound in the given order along a first plurality of portions of the winding barrel and the other order along a second plurality of portions of the winding barrel, each of the first and second plurality of portions alternating along the winding barrel.

39. The common-mode choke of claim 34, wherein the twisted winding is associated with an electrical coupling that is more balanced as compared to a winding that is not twisted.

40. The common-mode choke of claim 34, wherein at least one of the first and second twisted windings comprises at least another winding twisted with the corresponding first and second pair of windings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The features, objectives, and advantages of the disclosure will become more apparent from the detailed description set forth below taken in conjunction with the drawings, wherein:

[0040] FIG. 1 is a perspective view of a prior art common-mode choke having a single-layer bifilar winding.

[0041] FIG. 2 is a perspective view of the underside of a prior art common-mode choke having a multiple-layer bifilar winding.

[0042] FIG. 3 is a perspective view of a first exemplary embodiment of a common-mode choke having twisted wire in accordance with the principles of the present disclosure.

[0043] FIG. 4 is a perspective view of a second exemplary embodiment of a common-mode choke in accordance with the principles of the present disclosure.

[0044] FIG. 5 is a perspective view of a third exemplary embodiment of a common-mode choke having multiple layers in accordance with the principles of the present disclosure.

[0045] FIG. 6 is a perspective view of a fourth exemplary embodiment of a common mode choke having multiple layers with multiple wire flips in accordance with the principles of the present disclosure.

[0046] FIG. 6A is a front elevational view of, for example, the fourth exemplary embodiment of a common mode choke of FIG. 6, in accordance with the principles of the present disclosure.

[0047] FIG. 7 is a process flow diagram illustrating a first exemplary embodiment of a method for manufacturing the common-mode choke illustrated in FIGS. 4-6.

[0048] FIG. 8 is a process flow diagram illustrating a second exemplary embodiment of a method for manufacturing the common-mode choke illustrated in FIG. 3.

[0049] All Figures disclosed herein are Copyright 2013 Pulse Electronics, Inc. All rights reserved.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0050] Reference is now made to the drawings, wherein like numerals refer to like parts throughout.

[0051] As used herein, the terms electrical component and electronic component are used interchangeably and refer to components adapted to provide some electrical and/or signal conditioning function, including without limitation inductive reactors (choke coils), transformers, filters, transistors, gapped core toroids, inductors (coupled or otherwise), capacitors, resistors, operational amplifiers, and diodes, whether discrete components or integrated circuits, whether alone or in combination.

[0052] As used herein, the term magnetically permeable refers to any number of materials commonly used for forming inductive cores or similar components, including without limitation various formulations made from ferrite.

[0053] As used herein, the terms top, bottom, side, up, down and the like merely connote a relative position or geometry of one component to another, and in no way connote an absolute frame of reference or any required orientation. For example, a top portion of a component may actually reside below a bottom portion when the component is mounted to another device (e.g., to the underside of a PCB).

Overview

[0054] The present disclosure provides, inter alia, improved electrical balance for the windings of electronic components such as common-mode chokes that utilize I-shaped cores. In one embodiment, the electrical balance is a measure of the ratios between the common-mode signals coming from one end of the winding to the differential-mode signals coming out the other end of the winding. In order to improve upon the electrical balance, modifications of the winding process are performed. These modifications can produce a more favorable electrical balance as the small uneven coupling present within prior art winding techniques can add up over the winding length of the core resulting in an unacceptable imbalance in many modern applications.

[0055] One such modification is to twist the two (or more) windings prior to winding them onto the winding barrel of the core. Such a winding technique will cause the electrical coupling of the signal from one turn of a winding to the next turn of the other winding to be continuously changed, and hence, accumulated uneven coupling can be minimized or avoided altogether.

[0056] In an alternative configuration, the winding technique involves the flipping of the order of the wire pairs every predetermined number of turns. This enables the uneven coupling to reverse direction periodically therefore nullifying the accumulated uneven coupling effects. The number of flips may be dependent on core geometry, geometry and number of wires, as well as the specification limits on electrical balance. For example, common-mode chokes requiring more balance at high frequencies often necessitate more flips in order to limit the size of unbalanced sections of windings. These smaller sections will limit the phase of the unbalanced signal from becoming too large to be effectively cancelled. Since this technique often involves flipping the wire in order to counterbalance the unbalance accumulated in the preceding section, an odd number of flips may be optimal. However, an even number of flips may be utilized as well in certain applications. Furthermore, these windings may be comprised of twisted pair windings or alternatively, weaved windings as well.

[0057] These windings may be made from single or multiple layers. For single-layer windings, flipping will change the wire order in the traverse direction while in, for example, two-layer winding configurations the flipping changes the wire in the vertical direction (i.e. orthogonal to the traverse direction).

[0058] Furthermore, methods for manufacturing and using these aforementioned chip choke assemblies are also disclosed.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0059] It will be recognized that while the following discussion is cast in terms of an exemplary common-mode choke having an I-shaped magnetically permeable core, it would be readily apparent to one of ordinary skill given the present disclosure that same principles apply for a common-mode choke with different magnetically permeable core shapes including, e.g. a C-shaped magnetically permeable core, a square shaped magnetically permeable core, and a rectangular shaped magnetically permeable core.

[0060] Furthermore, while the magnetically permeable cores are primarily discussed herein as being formed from a ferrite material, other common core materials can be readily substituted if desired (such as e.g., laminated silicon steel, etc.) to achieve the desired electrical performance characteristics of the chip choke assembly.

Twisted Windings

[0061] Referring now to FIG. 3, a first exemplary embodiment of a common-mode choke 300 in accordance with the principles of the present disclosure is shown and described in detail. The common-mode choke 300 comprises an I-shaped core with flanges 302 disposed on opposite sides of the winding barrel of core 304. The core 304 is wound, in the illustrated embodiment, with two (2) windings 306, 308. These two (2) windings 306, 308 are twisted about each other prior to their distribution onto the core and wound around the winding barrel of core 304. This technique causes the electrical coupling of a present signal from one turn of a winding to the next turn of the other winding to be continuously changed, and hence, accumulated uneven coupling can be avoided. In other words, this technique minimizes the cumulated undesired electrical coupling within the turns of the common mode choke by randomly changing the areas of coupling so that the net effect can be much more electrically balanced. The ends of this twisted pair windings 306, 308 are subsequently secured to four (4) distinct terminations which are resident on opposite corners of each flange 302.

[0062] In an alternative embodiment, more than two (2) wires may be twisted and wound around the core. For example, a woven strand of multiple wires, such as that described in U.S. Pat. No. 8,405,481 entitled Woven Wire, Inductive Devices, and Methods of Manufacturing issued Mar. 26, 2013, which is incorporated herein by reference in its entirety, could be readily added to the core 304.

Flipped Windings

[0063] Referring now to FIG. 4, a second exemplary embodiment of a common-mode choke 400 in accordance with the principles of the present disclosure is shown and described in detail. Similar to the embodiment illustrated above with respect to FIG. 3, the common-mode choke 400 comprises an I-shaped core with flanges 402 disposed on opposite sides of core 404. The winding barrel of core 404 is wound, in the illustrated embodiment, with two (2) windings 406, 408. The windings 406, 408 are wound about the core alternating between one wire 406 and the other 408 with the order of the wire pairs 406, 408 being flipped every few turns about core 404. The flipping of the wire changes the wire order in the traverse direction. This allows the uneven coupling generated by a portion of the windings to reverse direction after every few turns and therefore, nullify the accumulated uneven coupling effects. The number of flips required is dependent upon, for example, the core geometry, the number and size of the wires utilized, and the specification limits on electrical balance. For instance, common-mode chokes that require more balance at higher frequencies need more flips in order to limit the size of the unbalanced sections. This is because the resultant smaller sections will limit the phase of unbalanced signal from becoming too large to be effectively cancelled. As illustrated in FIG. 4, the windings of the wired pair 406, 408 are flipped four (4) times.

[0064] However, in an alternative variant, the number of flips is odd (i.e., three (3) flips, five (5) flips, etc.). Using an odd number of flips is particularly useful where the number of turns for each section is the same between flips which would counterbalance the unbalance that has accumulated in the preceding section. Furthermore, while illustrated as having the wire flips occurring in multiple locations on the top portion of the core 404, the location of the wire flips can be readily varied depending upon the electrical requirements for the choke. For instance, flips can occur on the top, bottom, and sides, or even variations thereof on the winding barrel of the core, or anywhere around the circumference of a cylindrical winding barrel.

[0065] In a further variant, a pair of the twisted (or braided) windings (such as that illustrated with respect to FIG. 3) is alternatingly wound about the winding barrel of core 404. Each pair of the twisted windings is subsequently flipped periodically about the core 404, similar to that described above with respect to FIG. 4.

Multiple Layer Windings

[0066] Referring now to FIGS. 5-6A, wire flipping as discussed above with respect to FIG. 4 is illustrated with multiple layers of windings of a common-mode choke. As shown in FIG. 5, a first exemplary embodiment of a multiple layer common-mode choke 500 is shown. The choke 500 includes flanges 502 on either side of the winding barrel of core 504. The illustrated choke 500 has two wires 506, 508. On a first portion of the core 504, the first wire 508 is wound adjacent to the core 504. The second wire 506 is wound on top of the first wire 508. In a second portion of the core 504, the second wire 506 is wound adjacent to the core 504 while the first wire 508 is wound on top of the second wire 506. In between the first portion and the second portion the wires 506, 508 are flipped. Flipping the wires 506, 508 in the multiple layer winding reverses the wires in the vertical direction thereby providing better electrical balance. This improved electrical balance is a result of, inter alia, the lengths of the wires 506, 508 being made equal whereas without the flip the inner wire would be shorter than the outer wire.

[0067] Referring now to FIGS. 6 and 6A, an alternative embodiment for a multiple layer common mode choke is shown and described in detail. Specifically, the embodiment of FIG. 6 illustrates multiple wire flips (e.g., flip 612 and flip 614 in FIG. 6A) as compared with the embodiment of FIG. 5. Like the other embodiments illustrated in FIGS. 3-5, the choke 600 includes flanges 602 on opposite ends of the winding barrel of core 604. In a first portion of the core 604, a first wire 606 (indicated by dashed circle 606 in FIG. 6A) is a first distance from the core 604 and a second wire 608 (indicated by circle 608 in FIG. 6B) is a second distance from the core 604 where the second distance is longer than the first distance. The positions of the first wire 606 and the second wire 608 switch in a second portion of the winding barrel of core 604 that is adjacent to the first portion via the flipping of the wires 606, 608. In this flipped position, the second wire 608 is now at a first distance from the core 604 while the first wire 606 is at the second distance from the core. The first and second wires 606, 608 alternate distances from the core 604 along the entire length of the winding barrel of core 604. As illustrated in FIG. 6, the first and second wires 606, 608 flip eight (8) times; however, it is of course envisaged that the number of wire flips can vary depending on the particular electrical design constraints, For example, variables such as wire diameter, thickness of the wire coating, dielectric constant of the dielectric itself, and most importantly, the desired balance level, which also varies as a function of frequency are factors to consider in determining the number of wire flips within a given design.

[0068] For example, in an alternative variant (and similar to the discussion with respect to the embodiments illustrated in FIGS. 3 and 4), the number of flips is odd (i.e., three (3) flips, five (5) flips, etc.). Using an odd number of flips is particularly useful where the number of turns for each section is the same between flips which would counterbalance the unbalance that has accumulated in the preceding section. Furthermore, while illustrated as having the wire flips (e.g., wire flip 612 in FIG. 6A) occurring in multiple locations on the top portion of the core 604, the location of the wire flips can be readily varied depending upon the electrical requirements for the choke. For instance, flips can occur on the top, bottom (e.g., wire flip 614 in FIG. 6A), and sides, or even variations thereof on the winding barrel of the core, or anywhere around the circumference of a cylindrical winding barrel.

Methods of Manufacture

[0069] Exemplary methods of manufacture and use of the common-core choke according to the principles of the present disclosure are now described in detail.

[0070] Referring to FIG. 7, an exemplary method for manufacturing 700 the aforementioned common-mode choke is described in detail. The method may be performed by an automated winding machine or alternatively, may be wound by hand. In one embodiment, the core is an I-shaped core of the type illustrated in, for example, FIGS. 3-6. The core thus has an axial portion (i.e., winding barrel) and two (2) flanges disposed on both ends of the axial portion. As discussed previously herein, it will be readily apparent to those skilled in the art without departing from the present disclosure that another shape may be used as required for the final desired shape and properties of the common-mode choke assembly. In one embodiment, the windings used are magnet wire windings with two (2) such windings being wound around the axial portion of the core. In an alternative embodiment, more than two (2) windings are utilized. While the use of the I shaped core and square shaped winding barrel are exemplary, other shapes and winding barrel geometries may be formed to get the desired magnetic flux and electrical properties without deviating from the principles of the present disclosure.

[0071] At step 702, a pair of wires is wound about a core that is to form the common-mode choke. In a multiple layer variant, the pair of wires is wound vertically about the core such that a first wire of the pair is wound adjacent the core while the second wire of the pair is wound adjacent the first wire.

[0072] At step 704, after a predetermined number of windings about the core, the wires are flipped. For example, in the multiple layer variant discussed previously herein, the flipping changes the orientation of the wires in a vertical direction with respect to the winding barrel of the core. Alternatively, in a single layer variant, the flipping of the windings causes the wires to be changed in the horizontal direction (i.e. the traversal direction of the windings) with respect to the core.

[0073] At step 706, the pair of wires is continued to be wound with the predetermined orientation governed by step 704.

[0074] At step 708, if the number of flips is sufficient to limit the size of unbalanced sections with respect to specification limits on electrical balance, the method 700 ends. Otherwise, the method continues at step 706 where the windings are once again flipped.

[0075] Referring now to FIG. 8, an exemplary method for manufacturing 800 an exemplary common-mode choke as illustrated in, for example, FIG. 3 is described in detail.

[0076] At step 802, two (2) or more windings are twisted or braided together. In one embodiment, the method of braiding can be done as described in co-owned and co-pending U.S. Pat. No. 8,405,481 entitled Woven Wire, Inductive Devices, and Methods of Manufacturing issued Mar. 26, 2013, which was previously incorporated herein by reference in its entirety.

[0077] At step 804, the windings are wound onto the length of the winding barrel of a core thereby forming a common-mode choke. In an alternative variant, multiple twisted pairs from step 802 are used as the individual windings of method 800 of FIG. 8.

[0078] It will be recognized that while certain aspects of the disclosure are described in terms of specific design examples, these descriptions are only illustrative of the broader methods, and may be modified as required by the particular design. Certain steps may be rendered unnecessary or optional under certain circumstances. Additionally, certain steps or functionality may be added to the disclosed embodiments, or the order of performance of two or more steps permuted. All such variations are considered to be encompassed within the disclosure and claims herein.

[0079] While the above detailed description has shown, described, and pointed out novel features of the disclosure as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art. The foregoing description is of the best mode presently contemplated. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the disclosure, the scope of which should be determined with reference to the claims.