Tunable inductor and method of use thereof

Abstract

A tunable inductor includes an annular magnetic core defining a plurality of gaps, a compressible gap material located in the gaps, at least one winding wound around the magnetic core, a force application structure, and a film substantially covering the tunable inductor. The force application structure is operable to apply a force to the magnetic core to adjust the gap and thereby adjust the inductance of the adjustable inductor. The membrane is configured to prevent movement of the force application structure when above a predetermined temperature threshold and to allow movement of the force application structure when below the predetermined threshold.

Description

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 862985, filed June 18, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The embodiments involve adjustable inductors. Summary of the Invention

[0003] Inductors, such as, but not limited to, toroidal inductors, may have a predetermined set inductance that can be adjusted off-site. For example, such a toroidal inductor can only be adjusted by adding or removing turns or by repositioning the wires on the core after winding.

[0004] Adding or removing turns only results in integer changes to the value – inductance is proportional to the square of the number of turns. The effects of repositioning the winding are negligible and not easily repeatable. Typically, for example, inductors with ±3% tolerances require careful clearance and / or material selection, consistent winding turns and / or location, and / or may require adding or removing turns. Often, parts fail to achieve the desired value and must be scrapped or disassembled and rewound.

[0005] Adjustable inductors, such as those described in U.S. Patent No. 10,102,952 (incorporated herein by reference), can be adjusted in the field. Because of this field-adjustable capability, adjustable inductors can be used in a variety of applications.

[0006] For example, one embodiment provides an adjustable inductor including a toroidal core defining a plurality of gaps, a compressible gap material located in the gaps, at least one winding wound on the core, a force-applying structure, and a thin film substantially covering the adjustable inductor. The force-applying structure is operable to apply a force to the core to adjust the gaps, and thereby adjust the inductance of the adjustable inductor. The thin film is configured to prevent movement of the force-applying structure when above a predetermined temperature threshold and to allow movement of the force-applying structure when below a predetermined temperature threshold.

[0007] Another embodiment provides a tunable notch filter inductor including a tunable inductor and a capacitor. The tunable inductor includes a toroidal core defining a plurality of gaps, a compressible gap material located within the gaps, at least one winding wound on the core, and a force-applying structure operable to apply a force to the core to adjust the gaps, and thereby adjust the inductance of the tunable inductor. The capacitor is electrically connected in series with the tunable inductor.

[0008] Another embodiment provides a three-matched filter inductor, comprising a first adjustable toroidal inductor having a first variable inductance, a second adjustable toroidal inductor having a second variable inductance, and a third adjustable toroidal inductor having a third variable inductance. The first, second, and third variable inductors are matched after the first, second, and third adjustable toroidal inductors are manufactured.

[0009] Other aspects of this application will become apparent from consideration of the detailed description and accompanying drawings. Attached Figure Description

[0010] Figure 1 This is a perspective view of an adjustable inductor according to some embodiments.

[0011] Figure 2 According to some embodiments Figure 1 The inductor shown is a top view.

[0012] Figure 3 This is a top view of the magnetic core of an inductor partially assembled with gap material according to some embodiments.

[0013] Figure 4 This is a top view of a magnetic core assembled with gap material and fixtures according to some embodiments.

[0014] Figure 5 This is a top view of a wound magnetic core according to some embodiments.

[0015] Figure 6 This is a top view of a wound magnetic core with a partially removable detachable core, according to some embodiments.

[0016] Figure 7 According to some embodiments, including thin films Figure 1 The inductor shown is shown in top view.

[0017] Figure 8 It is according to some embodiments including such Figure 1 The circuit diagram shown is for a tunable notch filter with one or more inductors.

[0018] Figure 9 It is according to some embodiments including such Figure 1 A perspective view of a three-matched filter inductor with one or more inductors shown. Detailed Implementation

[0019] Before explaining any embodiment of this application in detail, it should be understood that the application of this application is not limited to the construction details and component arrangement set forth in the following description or shown in the accompanying drawings. This application can have other embodiments and can be practiced or implemented in various ways.

[0020] The phrase "series configuration" as used in this article refers to a circuit arrangement in which the described components are typically arranged sequentially such that the output of one component is coupled to the input of another, even though the same current may not flow through every component. For example, in a series configuration, additional circuit components can be connected in parallel with one or more components in the series configuration. Furthermore, additional circuit components can be connected at nodes in a series configuration, creating branches in the circuit. Therefore, the components in a series configuration do not necessarily form a true "series circuit."

[0021] Furthermore, the phrase "parallel configuration" as used herein refers to a circuit arrangement in which the described elements are typically arranged in such a way that one element is connected to another, such that the circuit forms parallel branches of the circuit arrangement. In this configuration, the individual elements of the circuit may not have the same potential difference. For example, in a parallel configuration of a circuit, two circuit elements connected in parallel may be connected in series with one or more additional elements of the circuit. Therefore, a circuit in a "parallel configuration" may include elements that do not necessarily form a true "parallel circuit" on their own.

[0022] Figure 1-6 The diagram illustrates electrical components such as a toroidal inductor 10 and a method of assembling the inductor 10. The illustrated inductor 10 is adjustable to adjust its inductance. The inductor 10 typically includes (see...) Figure 1-2 The magnetic core 14 defines multiple gaps 18, the gap material 22 positioned in the gaps 18, the force-applying structure 26 (e.g., hose clamp) for adjusting the gaps 18, and the wound coil 30.

[0023] In the illustrated configuration, the magnetic core 14 has a ring shape and defines at least two gaps 18. Figure 3-4 The four gaps 18 shown provide cores 34 (four cores 34, two at approximately 120° each and two at approximately 60° each). In other configurations (not shown), the core 14 may be formed in different angular portions (e.g., four 90° cores 34) and / or have fewer or more gaps 18 (e.g., six 60° cores 34).

[0024] The illustrated magnetic core 14 is formed by winding, spot-welding, and annealing strip steel (e.g., M3, M6, M50, or other grades). The layers of the magnetic core 14 are held together (e.g., by varnish). The magnetic core 14 is then cut to provide the required number of gaps 18.

[0025] In other configurations (not shown), the magnetic core 14 may be formed from different materials (e.g., amorphous sheets, iron powder, iron-silicon-aluminum powder, etc.) and / or through different processes (e.g., molding, casting, etc.). In such configurations, the magnetic core 14 may form (e.g., molding, compression, and firing) the required gap 18.

[0026] like Figure 3-4 As shown, gap material 22 is positioned in each gap 18. Gap material 22 may be substantially non-magnetic and non-conductive. Gap material 22 may also withstand magnetic temperatures (maximum temperatures in the range of about 130°C to about 220°C) and may operate at low temperatures (as low as about -55°C).

[0027] Essentially incompressible "rigid" gap materials 22a (e.g., high-temperature gap materials used in magnetic materials (glass epoxy, gluconate)). ® (Available from Rochling Glastic Composites, Cleveland, Ohio), GPO glass fiber epoxy resin, Nomex ® Paper (available from DuPont in Wilmington, Delaware), circuit board materials, glass, treated paper, and combinations thereof, can be placed in a fixed gap 18a (e.g., a non-adjustable gap 18) (see [reference]). Figure 3-4 In the illustrated configuration, the thickness of the gap material 22a in the fixed gap 18a is selected to establish the inductance adjustable range and basic inductance of the inductor 10.

[0028] For retention purposes during assembly, rigid gap material 22a is positioned within the adjustable gap 18b. A compressible "flexible" gap material 22b (e.g., silicone sheet, silicone foam, high-temperature soft rubber, etc., and combinations thereof) can then be placed within the adjustable gap 18b (see [link to relevant documentation]). Figure 2 and Figure 6 ).

[0029] The rigid core 38 is formed by securing (e.g., using high-temperature adhesive) a rigid gap material 22a in place among a plurality of separators 34 (e.g., three separators 34) of the magnetic core 14. The rigid gap material 22a can also be detachably positioned in the gap 18b during assembly (e.g., by debonding; see [link to product]). Figure 3-4 ), and can be used alone or in combination with flexible gap material 22b in the final adjustable gap 18b.

[0030] The magnetic core 14 is assembled from one or more rigid cores 38 and at least one detachable core 42. In the illustrated construction (see...), Figure 3-4In this configuration, the magnetic core 14 includes a rigid core 38 extending about 300° (e.g., three cores 34 extending about 120°, 60°, and 120°) and a removable core 42 extending about 60°. In other configurations (not shown), the cores 38 and 42 may be oriented at different angles (e.g., about 270° and about 90°, respectively).

[0031] In some diagrammatic constructions (e.g., see...) Figure 1-2 and Figure 6 The force-applying structure 26 includes a clamp 46 (e.g., a hose clamp) at least partially located around (e.g., surrounding) the magnetic core 14. The clamp 46 may be non-magnetic (e.g., stainless steel, aluminum, etc.) and typically holds portions 38, 42 of the magnetic core 14 together. When the clamp 46 is tightened (see...), Figure 1-2 It is operable to apply force (e.g., radial force) to the removable portion 42 of the magnetic core 14 to adjust the gap 18b.

[0032] In the illustrated configuration, the force-applying structure 26 includes only one clamp 46. In other configurations, more than one clamp 46 may be provided (e.g., two clamps). Figure 1 The image shows one additional force-applying structure 26' / clamp 46' (three or more) indicated by dashed lines. Figure 1 As shown, the driving portions of the force-applying structures 26, 26' (clamps 46, 46') are shown to be circumferentially spaced apart, but in other configurations (not shown), they may be circumferentially aligned.

[0033] In other configurations (not shown), the force-applying structure 26 may include another mechanical device, such as a radially oriented screw (e.g., a thumb screw) supported on a circumferential belt, to apply a radial force to the removable portion 42. In other configurations (not shown), the force-applying structure 26 may include cable ties, cable ties, binding material applied by a strapping machine, etc.

[0034] The wound coil 30 includes (see) Figure 1-2 and Figure 5-6 One or more windings 50 are wound around a rigid core 38, but not around a removable core 42. The windings 50 may include thin-film coated wires, Teflon... ® Materials available from DuPont, other materials resistant to magnetic temperatures, glass winding, etc. Each winding 50 has the required number of turns, the number of strands of wire (e.g., single strand, multi-strand), etc. In the illustrated configuration, coil 30 includes dual windings 50. The number of magnetic cores 34 and the relative dimensions of cores 38, 42 can be determined based on the required dimensions of coil 30 on rigid core 38.

[0035] Before winding, the rigid core 38 can be wrapped (with tape 54), impregnated, glued with epoxy resin, or otherwise coated for electrical insulation. In the illustrated configuration, the removable core 42 is wound separately from the rigid core 38 with one or more strips of tape 54.

[0036] When the cores 38 and 42 are firmly secured by the clamp 46 (to withstand the winding force), in the illustrated configuration (see...) Figure 5 The winding 50 is wound onto the rigid core 38 only with the required number of turns. In other configurations (not shown), the winding 50 may be wound onto a portion of the removable core 42.

[0037] After winding, clamp 46 is released (see...) Figure 6 ), and the rigid gap material 22a in at least one gap 18b (two adjustable gaps 18b in the illustrated configuration) is replaced with a flexible gap material 22b (see Figure 2 Alternatively, a combination of flexible gap material 22b and rigid gap material 22a may be used. The clamp 46 is tightened to set the lower limit of the adjustment for the gap 18b and the inductance.

[0038] The clamp 46 is adjusted (e.g., tightened to increase inductance, loosened to decrease inductance) to radially move the removable core 42 to adjust the gap 18b (in the illustrated configuration, both gaps 18b can be adjusted) and thereby adjust the inductance of the inductor 10 to the desired value. In the illustrated configuration, the inductance of the inductor 10 can be adjusted within a range of 10% of the inductance value. This adjustment range can be varied depending on the different sizes of the adjustable gaps 18b, the amount of compressible gap material 22b, or compressibility, etc.

[0039] In an alternative configuration, the adjustable gap 18b can only be adjusted using rigid gap material 22a. After winding, the thickness of the rigid gap material 22a in the adjustable gap 18b is changed to alter the inductance. The thickness (number of sheets of rigid gap material 22a and / or the thickness of each sheet) is varied until the desired inductance is achieved.

[0040] like Figure 7 As shown, inductor 10 may be at least partially encased in a finish or film (shown by dashed line 60). In some embodiments, the film may be a varnish. In operation, the film is configured to prevent movement of the force-applying structure 26 below a predetermined temperature threshold, and thus prevent adjustment of the inductance of inductor 10. When heated to a temperature above the predetermined temperature threshold, the film may soften sufficiently to allow movement of the force-applying structure 26, and thus allow adjustment of the inductance of inductor 10. It should be understood that in other embodiments, inductor 10 may be unfinished, and such inductor 10 will remain adjustable during use.

[0041] Figure 8 This is a circuit diagram illustrating a tunable notch filter 100 comprising one or more inductors 10 according to some embodiments. As shown, the tunable notch filter 100 may include one or more capacitors C1-C4, each capacitor being electrically connected in series with inductors L1-L4 respectively. The capacitor and inductor pairs can then be electrically connected to each other in a parallel connection manner. In the illustrated embodiment, each inductor L1-L4 has a similar configuration to the inductor 10 described in detail above.

[0042] Incorporating inductor 10 into the tunable notch filter 100 allows each inductor L1-L4 to be tuned according to the expected harmonics. For example, the expected harmonics of the 5th, 7th, 11th, and 13th orders, as well as other harmonics that depend on the phase connection.

[0043] Since inductors L1-L4 can be adjusted on-site, inductors L1-L4 can be paired with capacitors C1-C4, and adjustments can be made not only for the inductance value but also for the capacitance change, allowing for individual tuning of the components to the correct resonant frequency.

[0044] Furthermore, the capacitors used in notch filters may age and lose capacitance. This can lead to detuning of the notch filter, shifting its frequency upwards and away from its intended value. This detuning can significantly reduce the filter's attenuation at the intended notch frequency and shift the filter's center frequency away from its intended frequency into a frequency region that may have resonant peaks, creating resonant circuitry that can cause severe ringing and potential damage to filter components. By incorporating adjustable inductors L1-L4 into the tunable notch filter 100, the frequency can be corrected without replacing the capacitors, thus reducing downtime.

[0045] Figure 9 A three-matched filter inductor 150 according to some embodiments is shown. As shown, the three-matched filter inductor 150 may include inductors 155a-155c. In the illustrated embodiment, each inductor 155a-155c has a similar construction to the inductor 10 described in detail above (e.g., inductors 155a-155c may be adjustable inductors).

[0046] Incorporating inductors 155a-155c into a three-matched filter inductor 150 allows inductors 155a-155c to be matched in the field without extensive rework. For example, inductors 155a-155c can be adjusted after the windings are positioned, eliminating the need for unwinding and rewinding the windings.

[0047] During the production of fixed inductors used in triple-matched filter inductors, each inductor is grouped together based on a matching core. However, the magnetism generated during winding can vary depending on the winding position, the gap size between the starting and ending windings (if multi-strand wires are used), and the relative position of each turn of each strand of wire. This variation in inductance value, derived from winding characteristics, can cause inductors with matching cores to become mismatched during field installation. The triple-matched filter inductor 150 addresses these drawbacks by allowing field adjustment of inductors 155a-155c.

[0048] Furthermore, an embodiment provides an adjustable inductor. Various features and advantages of this application are set forth in the following claims.

Claims

1. A tunable notch filter inductor, comprising: An adjustable inductor, the adjustable inductor comprising: A toroidal magnetic core with multiple gaps defined; The material located in the gap; At least one winding wound around a magnetic core; A force-applying structure operable to apply a force to the magnetic core to adjust the gap, and thereby adjust the inductance of the adjustable inductor; and The adjustable inductor also includes a thin film that substantially covers the adjustable inductor.

2. The tunable notch filter inductor according to claim 1 further includes a capacitor connected in series with the tunable inductor.

3. The tunable notch filter inductor according to claim 2, wherein, The inductance of the adjustable inductor is adjusted according to the change in the capacitance of the capacitor.

4. The tunable notch filter inductor according to claim 1, wherein, The material is a compressible material.

5. The tunable notch filter inductor according to claim 1, wherein, The material is incompressible and rigid.

6. The tunable notch filter inductor according to claim 1, wherein, The material is substantially nonmagnetic and non-conductive.

7. The tunable notch filter inductor according to claim 1, wherein, The film is a varnish.

8. The tunable notch filter inductor according to claim 1, wherein, The thin film is configured as follows: The force-applying structure is allowed to move when the temperature exceeds a predetermined threshold; and Prevent the force-applying structure from moving when the temperature is below a predetermined threshold.

9. The tunable notch filter inductor according to claim 8, wherein, The predetermined temperature threshold is approximately 150°C.

10. An adjustable inductor, comprising: A magnetic core with multiple gaps defined; The material located in the gap; At least one winding wound around a magnetic core; A force-applying structure operable to apply a force to the magnetic core to adjust the gap, and thereby adjust the inductance of the adjustable inductor; and The thin film that substantially covers the adjustable inductor is configured as follows: When the temperature falls below a predetermined threshold, the force-applying structure is prevented from moving, and When the temperature exceeds a predetermined threshold, the force-applying structure is allowed to move.

11. The adjustable inductor according to claim 10, wherein, The predetermined temperature threshold is approximately 150°C.

12. The adjustable inductor according to claim 10, wherein, The film is a varnish.

13. The tunable notch filter inductor according to claim 10, wherein, The material is a compressible material.

14. The tunable notch filter inductor according to claim 10, wherein, The material is incompressible and rigid.

15. The tunable notch filter inductor according to claim 10, wherein, The material is substantially nonmagnetic and non-conductive.

16. The adjustable notch filter inductor according to claim 10, further comprising a capacitor connected in series with the adjustable inductor.

17. The adjustable notch filter inductor according to claim 16, wherein, The inductance of the adjustable inductor is adjusted according to the change in the capacitance of the capacitor.

18. A three-matched filter inductor, comprising: A first adjustable inductor having a first variable inductance; A second adjustable inductor having a second variable inductance; as well as A third adjustable inductor with a third variable inductance; The first variable inductor, the second variable inductor, and the third variable inductor are matched after the first adjustable inductor, the second adjustable inductor, and the third adjustable inductor are manufactured. The first adjustable inductor includes: A toroidal magnetic core with multiple gaps defined; Material located in the plurality of gaps; A force-applying structure operable to apply a force to the magnetic core to adjust the plurality of gaps, and thereby adjust the first variable inductance; and The first adjustable inductor also includes a thin film that substantially covers the first adjustable inductor.

19. The three-matched filter inductor of claim 18, wherein the thin film is configured as follows: When the temperature exceeds a predetermined threshold, the force-applying structure is allowed to move, and When the temperature falls below the predetermined temperature threshold, the force-applying structure is prevented from moving.

20. The three-matched filter inductor according to claim 18, wherein, The first, second, and third adjustable inductors each include at least one winding, and wherein the first, second, and third adjustable inductors are matched without unwinding or rewinding at least one coil on each of the first, second, and third adjustable inductors.

21. An adjustable inductor, comprising: A magnetic core with adjustable width; A force-applying structure operable to apply a force to the magnetic core to adjust the width, and thereby adjust the inductance of the adjustable inductor; and The thin film that substantially covers the adjustable inductor is configured as follows: When the temperature falls below a predetermined threshold, the force-applying structure is prevented from moving, and When the temperature exceeds a predetermined threshold, the force-applying structure is allowed to move.

22. The adjustable inductor according to claim 21, wherein, The predetermined temperature threshold is approximately 150°C.

23. The adjustable inductor according to claim 21, wherein, The configuration is such that the force applied by the force-applying structure is a first force and a second force greater than the first force; The increase from the first force to the second force is configured to increase the inductance; and The reduction from the second force to the first force is configured to reduce the inductance.

24. The adjustable inductor according to claim 21, wherein, The configuration is such that the force applied by the force-applying structure is a first force and a second force greater than the first force; The increase from the first force to the second force is configured to reduce the width of the magnetic core; and The reduction from the second force to the first force is configured to increase the width of the magnetic core.

25. The adjustable inductor according to claim 21, wherein, The film is a varnish.

26. The adjustable inductor according to claim 21, wherein, The magnetic core is a toroidal magnetic core with multiple gaps, the adjustable inductor further includes material located in the multiple gaps and at least one winding wound on the magnetic core, and wherein the force-applying structure is operable to apply a force to the magnetic core to adjust the gaps, and thereby adjust the width of the magnetic core.

27. The adjustable inductor according to claim 26, wherein, The material is essentially nonmagnetic and conductive.

28. A tunable notch filter inductor, comprising: An adjustable inductor, the adjustable inductor comprising: A magnetic core with adjustable width, and A force-applying structure operable to apply a force to the magnetic core to adjust the width, and thereby adjust the inductance of the adjustable inductor; and The adjustable inductor also includes a thin film that substantially covers the adjustable inductor.

29. The tunable notch filter inductor of claim 28 further includes a capacitor connected in series with the tunable inductor, wherein the inductance of the tunable inductor is adjusted according to the capacitance of the capacitor.

30. The tunable notch filter inductor according to claim 28, wherein, The film is a varnish.

31. The tunable notch filter inductor according to claim 28, wherein: The configuration is such that the forces applied by the force-applying structure are a first force and a second force greater than the first force; The increase from the first force to the second force is configured to increase the inductance; and The reduction from the second force to the first force is configured to reduce the inductance.

32. The tunable notch filter inductor according to claim 28, wherein: The configuration is such that the forces applied by the force-applying structure are a first force and a second force greater than the first force; The increase from the first force to the second force is configured to reduce the width of the magnetic core; and The reduction from the second force to the first force is configured to increase the width of the magnetic core.

33. The tunable notch filter inductor according to claim 28, wherein, The magnetic core is a toroidal magnetic core with multiple gaps, the adjustable inductor further includes material located in the multiple gaps and at least one winding wound on the magnetic core, and wherein the force-applying structure is operable to apply a force to the magnetic core to adjust the gaps, and thereby adjust the width of the magnetic core.

34. The tunable notch filter inductor according to claim 28, wherein, The thin film is configured as follows: When the temperature falls below a predetermined threshold, the force-applying structure is prevented from moving, and When the temperature exceeds a predetermined threshold, the force-applying structure is allowed to move.

35. The tunable notch filter inductor according to claim 28, wherein, The predetermined temperature threshold is approximately 150°C.

36. A three-matched filter inductor, comprising: A first adjustable inductor having a first variable inductance; A second adjustable inductor having a second variable inductance; as well as A third adjustable inductor with a third variable inductance; The first variable inductor, the second variable inductor, and the third variable inductor are matched after the first adjustable inductor, the second adjustable inductor, and the third adjustable inductor are manufactured. The first adjustable inductor includes: A magnetic core with adjustable width, and A force-applying structure operable to apply a force to the magnetic core to adjust the width, and thereby adjust the inductance of the adjustable inductor; and The first adjustable inductor also includes a thin film that substantially covers the first adjustable inductor.

37. The three-matched filter inductor according to claim 36, wherein, The thin film is configured as follows: When the temperature falls below a predetermined threshold, the force-applying structure is prevented from moving, and When the temperature exceeds a predetermined threshold, the force-applying structure is allowed to move.

38. The three-matched filter inductor according to claim 36, wherein, The configuration is such that the forces applied by the force-applying structure are a first force and a second force greater than the first force; The increase from the first force to the second force is configured to increase the inductance; and The reduction from the second force to the first force is configured to reduce the inductance.

39. The three-matched filter inductor according to claim 36, wherein, The configuration is such that the force applied by the force-applying structure is a first force and a second force greater than the first force; The increase from the first force to the second force is configured to reduce the width of the magnetic core; and The reduction from the second force to the first force is configured to increase the width of the magnetic core.

40. The three-matched filter inductor according to claim 36, wherein, The magnetic core is a toroidal magnetic core with multiple gaps, the adjustable inductor further includes material located in the multiple gaps and at least one winding wound on the magnetic core, and wherein the force-applying structure is operable to apply a force to the magnetic core to adjust the gaps, and thereby adjust the width of the magnetic core.

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