DK202300051Y3 - INDUCTOR ARRANGEMENTS AND METHODS OF DESIGN THEREOF - Google Patents

Abstract

A double coil inductor device includes an inner coil device including an inner coil and first and second terminals, and an outer coil device including an outer coil and third and fourth terminals. The inner coil includes an inner metal foil, and an inner electrical insulator plate that is spirally wound with the inner metal foil. The outer coil includes an outer metal foil, and an outer electrical insulator plate spirally interwoven with the outer metal foil. The inner coil is placed within an outer coil air core of the outer coil so that the outer coil circumferentially surrounds the inner coil. The first and second terminals are electrically connected to the inner metal foil at respective first and second locations spaced along the inner metal foil. The third and fourth terminals are electrically connected to the outer metal foil at respective third and fourth locations spaced along the outer metal foil.

Description

DK 202300051 Y3 1

INDUCTOR ARRANGEMENTS AND METHODS OF DESIGN

THEREFORE

RELATED APPLICATIONS

[0001] The present application claims priority from US Provisional Patent Application No. 62/988,122, filed on March 11, 2020, and is a continuation application that claims priority from US Patent Application No. 16/114,287, filed on August 28, 2018, which claims priority from US Provisional Patent Application No. 62/557,289, filed Sep. 12, 2017, which is incorporated herein by reference.

TERRITORY

[001] The present invention relates to inductor devices and, more specifically, to inductor devices that include inductor coils and methods of making them.

BACKGROUND

[002] Inductor coils are used in AC networks for power factor correction, voltage regulation, reduction of di/dt and protection of downstream equipment.

SUMMARY

[001] According to embodiments of the invention, an inductor device includes a coil that includes a spirally wound metal foil.

[002] In some embodiments, the coil has a longitudinal coil axis and a radial coil thickness, the metal foil has a foil width that extends substantially parallel to the coil axis, and the foil width is greater than the coil thickness.

[003] In some embodiments, the metal foil has a foil thickness in the range from approx. 0.5 mm to 1 mm.

[004] In some embodiments, the coil includes an electrical insulator layer that is spirally interwoven with the metal foil.

[005] In some embodiments, the electrical insulator layer has a thickness in the range of approx. 0.05 to 1 mm.

[006] In some embodiments, the ratio between the foil width and the foil thickness is from approx. 170 to 500.

DK 202300051 Y3 2

[007] According to some embodiments, the metal foil and the electrical insulator layer are not bonded to each other across their width.

[008] In some embodiments, the coil has a substantially cylindrical outer profile.

[009] According to some embodiments, the inductor device includes an electrically insulating epoxy resin that surrounds and engages the coil.

[0010] In some embodiments, the inductor device further includes a second coil that includes a second helically wound metal foil, and the epoxy resin surrounds and engages the second coil and is sandwiched between the first and second coils.

[0011] According to some embodiments, the inductor device includes a housing defining a closed chamber with the coil disposed within the chamber.

[0012] In some embodiments, the inductor assembly includes at least one mounting bracket that supports the housing and the coil.

[0013] According to some embodiments, the inductor device includes a terminal rail that is electrically connected to the metal foil and includes a terminal, and an electrically insulating heat-shrink tube that surrounds a portion of the terminal rail.

[0014] In some embodiments, the coil includes a second metal foil that is spirally wound with the first metal foil to form a multilayer conductor.

[0015] In some embodiments, the coil includes an electrical insulator layer that is spirally wound with the first and second metal foils.

[0016] According to some embodiments, the first and second metal foils and the electrical insulator layer are not bonded to each other across their width.

[0017] According to some embodiments, the coil has a coil longitudinal axis, the coil has an inner winding of the metal foil and an outer winding of the metal foil, the inductor device includes a first terminal rail connected to the inner winding and extending outwardly from an axial end of the inductor device, and the inductor device includes a second terminal rail connected to the outermost winding and extending outwardly from the axial end of the inductor assembly.

[0018] According to embodiments of the invention, a multi-unit inductor system includes first and second inductor devices. The first inductor device includes a first coil, the first coil includes a helically wound first metal foil. The second inductor device includes a second coil, the second

DK 202300051 Y3 3 coil includes a spirally wound second metal foil. The first coil is electrically connected to the second coil.

[0019] In some embodiments, the first coil has a first coil length axis and the second coil has a second coil length axis. Each of the first and second inductor devices includes: a first terminal rail connected to the coil thereof and extending outwardly from an axial end of the inductor device; and a second terminal rail connected to the coil thereof and extending outwardly from the axial end of the inductor assembly. The first and second inductor devices are placed side by side, and the first terminal rail of the second inductor device is electrically connected to the second terminal rail of the first inductor device.

According to embodiments of the invention, a method of forming an inductor device includes spirally winding a metal foil into the shape of a coil.

[0021] In some embodiments, the method includes spirally wrapping an electrical insulator plate with the metal foil.

[0022] According to some embodiments, the metal foil and the electrical insulator plate are not bonded to each other during the step of interwinding the electrical insulator plate and the metal foil.

[0023] According to some embodiments, a dual coil inductor device includes an inner coil device and an outer coil device.

The inner coil device includes an inner coil and first and second terminals.

The inner coil includes an inner metal foil and an inner electrical insulator plate that is spirally wound with the inner metal foil. The outer coil device includes an outer coil and third and fourth terminals. The outer coil includes an outer metal foil and an outer electrical insulator plate spirally wound with the outer metal foil. The outer coil defines an outer coil air core. The inner coil is placed inside the outer coil air core so that the outer coil circumferentially surrounds the inner coil. The first terminal is electrically connected to the inner metal foil at a first location, the second terminal is electrically connected to the inner metal foil at a second location, and the first and second locations are spaced along the inner metal foil. The third terminal is electrically connected to the outer metal foil at a third location, the fourth terminal is electrically connected to the outer metal foil at a fourth location, and the third and fourth locations are spaced along the outer metal foil.

DK 202300051 Y3 4

[0024] According to some embodiments, the dual coil inductor device includes: a first terminal rail that includes the first terminal and is attached to an inner winding of the inner metal foil; a second terminal rail including the second terminal and attached to an outermost winding of the inner metal foil; a third terminal rail including the third terminal and attached to an inner winding of the outer metal foil; and a fourth terminal rail that includes the fourth terminal and is attached to an outermost winding of the outer metal foil.

[0025] In some embodiments, the dual coil inductor assembly includes a clamp plate and a fastener that mechanically secures one of the first and second terminal rails in electrical contact with the inner metal foil.

[0026] In some embodiments, the inner metal foil and the inner electrical insulator plate are not bonded to each other across their width, and the outer metal foil and the outer electrical insulator plate are not bonded to each other across their width.

[0027] According to some embodiments, a method of using a dual coil inductor device includes providing a dual coil inductor device that includes an inner coil device and an outer coil device. The inner coil device includes an inner coil and first and second terminals. The inner coil includes an inner metal foil and an inner electrical insulator plate that is spirally wound with the inner metal foil. The outer coil device includes an outer coil and third and fourth terminals. The outer coil includes an outer metal foil and an outer electrical insulator plate spirally wound with the outer metal foil. The outer coil defines an outer coil air core. The inner coil is placed inside the outer coil air core so that the outer coil circumferentially surrounds the inner coil. The first terminal is electrically connected to the inner metal foil at a first location, the second terminal is electrically connected to the inner metal foil at a second location, and the first and second locations are spaced along the inner metal foil. The third terminal is electrically connected to the outer metal foil at a third location, the fourth terminal is electrically connected to the outer metal foil at a fourth location, and the third and fourth locations are spaced along the outer metal foil. The method includes connecting the dual coil inductor device to first and second leads of an alternating current electrical system, including: electrically connecting an input of the first lead with

DK 202300051 Y3 the first terminal; electrically connecting an output of the first wire to the second terminal; electrical connection of an input of the second wire with the third terminal; and electrically connecting an output of the second wire to the fourth. [0028] According to some embodiments, the first wire is a phase wire and the second wire is a neutral wire.

[0029] According to some embodiments, the first line is a first phase line and the second line is a second phase line.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a top perspective view of an inductor device according to embodiments of the invention.

[0031] FIG. 2 is a cross-sectional view of the inductor device of FIG. 1 taken along the line 2-2 in FIG. 1.

[0032] FIG. 3 is a perspective view of the inductor device of FIG. 1, where shells of the inductor device have been removed for the purpose of explanation.

[0033] FIG. 4 is a perspective view of the inductor device of FIG. 1, with the shells and casing of the inductor device removed for the purpose of explanation.

[0034] FIG. 5 is a perspective view of the inductor device of FIG. 1, where the shells, casing and coils of the inductor device have been removed for purposes of explanation.

[0035] FIG. 6 is a perspective view of a coil device forming part of the inductor device of FIG. 1.

[0036] FIG. 7 is a side view of the coil assembly of FIG. 6.

[0037] FIG. 8 is an end view of the coil assembly of FIG. 6.

[0038] FIG. 9 is an enlarged, fragmentary cross-sectional view of the coil assembly of FIG. 6.

[0039] FIG. 10 is a fragmentary perspective view of a conductor foil and an insulator plate forming parts of the coil assembly of FIG. 6, where the conductor foil and insulator plate are shown flattened for the purpose of explanation.

[0040] FIG. 11 is an electrical diagram representing a two-phase alternating current electrical system including the inductor device of FIG. 1.

DK 202300051 Y3 6

[0041] FIG. 12 is a perspective view of an inductor device according to further embodiments of the invention.

[0042] FIG. 13 is a cross-sectional view of the inductor device of FIG. 12 taken along the line 13-13 in FIG. 12.

[0043] FIG. 14 is an electrical diagram representing an electrical power system that includes the inductor device of FIG. 12.

[0044] FIG. 15 is a perspective view of an inductor device according to further embodiments of the invention.

[0045] FIG. 16 is a cross-sectional view of the inductor device of FIG. 15 taken along the line 16-16 in FIG. 15.

[0046] FIG. 17 is a perspective view of the inductor device of FIG. 15, where shells of the inductor device have been removed for the purpose of explanation.

[0047] FIG. 18 is a perspective view of the inductor device of FIG. 15, where the shells, casing and coils of the inductor structure have been removed for the purpose of explanation.

[0048] FIG. 19 is a perspective view of a coil device forming part of the inductor device of FIG. 15.

[0049] FIG. 20 is an exploded perspective view of the coil assembly of FIG. 19.

[0050] FIG. 21 is an enlarged, fragmentary end view of the coil assembly of FIG. 19.

[0051] FIG. 22 is an enlarged, fragmentary end view of the coil assembly of FIG. 19.

[0052] FIG. 23 is a side view of the coil assembly of FIG. 19.

[0053] FIG. 24 is a perspective view of a multi-unit inductor system that includes a plurality of inductor devices of FIG. 15.

[0054] FIG. 25 is a schematic diagram of a multi-unit inductor system that includes a plurality of the inductor devices of FIG. 1.

[0055] FIG. 26 is a schematic diagram of the inductor system with multiple units i

FIG. 5.

[0056] FIG. 27 is a perspective view of an inductor device according to further embodiments of the invention.

[0057] FIG. 28 is a cross-sectional view of the inductor device of FIG. 27 taken along the line 28-28 in FIG. 27.

[0058] FIG. 29 is a perspective view of a multi-unit inductor system that includes a plurality of the inductor devices of FIG. 27.

DK 202300051 Y3 7

[0059] FIG. 30 is a perspective view of a coil device according to further embodiments of the invention.

[0060] FIG. 31 is an exploded perspective view of the coil assembly of FIG. 30.

[0061] FIG. 32 is a side view of the coil assembly of FIG. 30.

[0062] FIG. 33 is an enlarged, fragmentary end view of the coil assembly of FIG. 30.

[0063] FIG. 34 is an enlarged, fragmentary end view of the coil assembly of FIG. 30.

[0064] FIG. 35 is a top perspective view of a dual coil inductor device according to further embodiments.

[0065] FIG. 36 is an opposite top perspective view of the dual coil inductor assembly of FIG. 35.

[0066] FIG. 37 is a cross-sectional view of the dual-coil inductor device of FIG. 35 taken along the line 37-37 in FIG. 36.

[0067] FIG. 38 is an exploded perspective view of a coil assembly forming part of the dual coil inductor assembly of FIG. 35.

[0068] FIG. 39 is a perspective view of the coil assembly of FIG. 38.

[0069] FIG. 40 is an opposite perspective view of the coil assembly of FIG. 38.

[0070] FIG. 41 is an end view of the coil assembly of FIG. 38.

[0071] FIG. 42-44 are enlarged fragmentary cross-sectional views of the coil assembly of FIG. 38 taken along the line 42-42 in FIG. 40.

[0072] FIG. 45 is a schematic diagram representing an alternating current electrical system that includes the dual coil inductor device of FIG. 35.

[0073] FIG. 46 is a schematic diagram representing an additional alternating current electrical system that includes the dual coil inductor device of FIG. 35.

[0074] FIG. 47 is a fragmentary side view of two conductor foils and two electrical insulator plates forming parts of the coil assembly of FIG. 38, where the conductor foils and electrical insulator plates are shown flattened for purposes of explanation.

[0075] FIG. 48 is a fragmentary perspective view of the two conductor foils and the two electrical insulator plates forming parts of the coil assembly of FIG. 38, where the conductor foils and electrical insulator plates are shown flattened for purposes of explanation.

[0076] FIG. 49 is a top perspective view of a dual coil inductor device according to further embodiments.

DK 202300051 Y3 8

[0077] FIG. 50 is a cross-sectional view of the dual-coil inductor device of FIG. 49 taken along the line 50-50 in FIG. 49.

[0078] FIG. 51 is a cross-sectional view of a dual coil inductor device according to further embodiments.

[0079] FIG. 52 is an enlarged fragmentary end view of an inner coil assembly forming part of the dual coil inductor assembly of FIG. 51.

[0080] FIG. 53 is an enlarged fragmentary end view of an outer coil assembly forming part of the dual coil inductor assembly of FIG. 51.

[0081] FIG. 54 is a fragmentary perspective view of the dual coil inductor assembly of FIG. 51

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of areas or features may be exaggerated for clarity. However, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this description is thorough and complete and will fully convey the scope of the invention to those skilled in the art.

[0083] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these expressions. These terms are used only to distinguish one element, component, area, layer or section from another area, layer or section. Thus, a first element, component, region, layer or section discussed below could be referred to as a second element, component, region, layer or section without departing from the teachings of the present invention.

[0084] Spatial terms such as "below," "below," "lower," "above," "upper," and the like may be used herein for ease of description to describe the relationship of an element or feature to another element. or another characteristic as illustrated in the figures. It will be understood that the spatially referring terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if

DK 202300051 Y3 9 the arrangement in the figures is reversed, elements described as "under" or "below under" other elements or characteristics will then be oriented "above" the other elements or characteristics. Thus, an example of the term "under" may include both an orientation of over and under. The device may be oriented differently (rotated 90? or other orientations) and the spatially referring descriptors used herein are interpreted accordingly.

[0085] As used herein, the singular forms "a", "an" and "the", "that" are intended to also include the plural forms, unless otherwise expressly stated.

It will further be understood that the terms "includes", "comprises", "including" and/or "comprehensive", when used in this specification, indicate the presence of specified characteristics, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other characteristics, integers, steps, operations, elements, components and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or intermediate elements may be present. As used herein, the term "and/or" includes any and all combinations of one or more of the associated specified elements.

[0086] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will further be understood that terms such as those defined in commonly used dictionaries shall be construed to have a meaning consistent with their meaning in the context of this specification and the relevant prior art and will not be construed in an idealized or overly formal meaning unless expressly defined herein.

[0087] Typical inductance coil designs use a conductor which is insulated by a varnish and wound around a coil. However, such designs will typically not be able to withstand significant transient overvoltages between the windings of the coil and will be large in size since the load current requires a significant cross-section of the conductor. In this case, a significant gap is lost between the windings of the conductor, since it has a round shape. If an insulating cover were fitted over the coil to ensure that it can withstand very high transient overvoltages, then the overall coil unit would be even larger in size.

DK 202300051 Y3 10

Furthermore, vibration can be a problem, as there is minimal contact between the windings of the coil, allowing for possible movement.

Referring to FIG. 1-11, there is shown a dual coil inductor device 100 according to embodiments of the invention. The inductor device 100 has a longitudinal axis L-L.

The inductor assembly 100 includes a housing 110, a pair of axially spaced support bases 120, a support shaft 122, an electrically insulating connector 124, a pair of bushings 126, casing 128, insulating sleeve or tube 129, a first coil assembly 131 and a second coil assembly 151.

[0090] The bases 120 and shaft 122 are metal (in some embodiments aluminum). The shaft 122 is supported by and attached to the bases 120 at each end.

The connecting piece 124 is mounted around the shaft 122.

The connecting piece 124 can be formed from a plastic or polymer material, such as polyethersulfone, with a dielectric strength in the range of approx. 30 to 40 kV/mm.

[0092] Coil assemblies 131, 151 (described in more detail below) are mounted on connector 124 and shaft 122. Coil assemblies 131, 151 each include a pair of terminal busbars 140, 142, 160, 162.

[0093] The housing 110 includes a pair of laterally opposed shells 114 and a pair of axially opposed end plates 112 that are secured together to form the housing 110. The housing 110 defines an internal cavity or chamber 118 within which the support shaft 122, the connecting piece 124 , the casing 128, the insulating tubes 129, the first coil device 131 and the second coil device 151 are arranged and contained. Four terminal openings 116 are defined in the housing 110 and are in communication with the chamber 118.

[0094] The housing components 112, 114 may be formed from any suitable material. In some embodiments, housing components 112, 114 are formed from an electrically insulating polymeric flame retardant material such as Noryl

N190X from SABIC with a dielectric strength of approx. 19 kV/mm.

Each of the four insulating tubes 129 surrounds a length of a respective terminal rail 140, 142, 160, 162 that extends through the chamber 118, through a terminal opening 116 and beyond the terminal opening 116 by a prescribed distance. The tubes 129 may be formed of any suitable material. In some embodiments, the tubes 129 are formed from an electrically insulating polymeric material. In some embodiments, the tubes 129 are formed from an electrical

DK 202300051 Y3 11 insulating elastomeric material. In some embodiments, the tubes 129 are formed from an electrically insulating heat-shrinkable polymer (e.g., elastomer) that has been heat-shrunk around the corresponding terminal rail 140, 142, 160, 162.

[0096] The enclosure 128 fills the empty space in the chamber 118 that is not occupied by the other components. The enclosure 128 may be formed from any suitable material. The enclosure 128 is electrically insulating. In some embodiments, the enclosure 128 is formed of a material having a breakdown voltage of at least 18 kV/mm. In some embodiments, the encapsulation 128 is an epoxy resin or a polyurethane resin.

[0097] Each bushing 126 is annular and is clamped or sandwiched between an end plate 112 and the adjacent base 120 and mounted on the shaft 122.

The bushings 126 may be formed from any suitable material.

In some embodiments, the bushings are formed from a resilient polymeric material.

In some embodiments, the bushings 126 are formed of an elastomer and, in some embodiments, a silicone elastomer or rubber.

[0098] The coil device 131 includes a multilayer coil 130, an inner terminal rail 140, and an outer terminal rail 142.

[0099] The coil 130 is an air core coil. The coil 130 has a coil axis A-A and axially opposite ends 130A, 130B. The coil 130 includes an electrically conductive conductor sheet, strip or foil 132 and an electrically insulating insulator strip or sheet 134. The foil 132 and sheet 134 are spirally wound or wound about the axis

A-A to form windings 136. The windings 136 extend progressively from an innermost winding 136E of the conductor foil 132 in an inner passage 138 to an outermost winding 136F of the conductor foil 132 on the outer diameter of the coil 130. Each winding 136 is radially superimposed on, stacked on or wound around the previous winding 136.

[00100] Conductor foil 132 has opposite side edges 132A which are axially spaced along the coil axis A-A and extend substantially parallel to each other.

Conductor foil 132 is spiral wound such that each edge 132A remains substantially in or near a single lateral plane E-E (FIG. 7) through coil 130 from winding 136E to winding 136F. That is, the conductor foil 132 is held in line with itself and is spirally, not screw-wound.

[00101] According to some embodiments, coil 130 includes at least 10 turns or turns from winding 136E to winding 136F and, in some embodiments, from about 60 to 100 wins. It will be understood that in the figures the layers 132, 134 and

DK 202300051 Y3 12 the windings of the coils 130, 150 not specifically shown or in FIG. 8, is only partially shown. As such, the depictions of the layers 132, 134 in the drawings may not be to scale with respect to the number of turns, the thickness of the layers, or the distance between the layers.

[00102] The conductive foil 132 may be formed of any suitable electrically conductive material. In some embodiments, the conductor foil 132 is formed of metal. In some embodiments, the conductor foil 132 is formed of copper or aluminum.

[00103] The insulator plate 134 may be formed of any suitable electrically insulating material. In some embodiments, the insulator plate 134 is formed of a polymeric material. In some embodiments, the insulator sheet 134 is formed of polyester film. In some embodiments, the insulator plate 134 is formed of a material with a breakdown voltage of at least 4 kV/mm and in some embodiments in the range of about 13 kV/mm to 20 kV/mm.

[00104] Coil 130 is generally tubular. In some embodiments, the outer profile of coil 130 is substantially cylindrical and substantially circular in lateral cross-section.

[00105] The coil 130 has a thickness CT (FIG. 7), a length CL (FIG. 7; parallel to the coil axis L-L) and an outer diameter CD (FIG. 8). The thickness CT is the radial distance from the innermost conductor winding 136E to the outermost conductor winding 136F in a lateral plane N-N (FIG. 7) perpendicular to the axis A-A of the coil.

[00106] According to some embodiments, the coil 130 is generally cylindrical with a length CL greater than its outer diameter CD. According to some embodiments, the ratio CL/CD is at least 0.2 and in some embodiments is in the range of about 0.3 to 1.5.

[00107] FIG. 9-10 are fragmentary images of the conductor foil 132 and the insulator plate 134 laid flat (eg, before winding into the coil 130). The conductor foil 132 has a thickness

MT, a length ML and a width MW. The insulator plate 134 has a thickness IT, a length IL and a width IW.

[00108] According to some embodiments, the conductor foil width MW is greater than the outer diameter CD of the coil. In some embodiments, the MW/CD ratio is at least 0.2 and in some embodiments ranges from about 0.4 to 1.5.

[00109] According to some embodiments, the conductor foil width MW is greater than the coil thickness CT. In some embodiments, the MW/CT ratio is at least 0.5 and in some embodiments ranges from about 2 to 3.

DK 202300051 Y3 13

[00110] According to some embodiments, the thickness MT is in the range from approx. 0.1 to 2 mm and in some embodiments in the range of approx. 0.5 mm to 1 mm. According to some embodiments, the length ML is in the range from about 1 m to 40 m. According to some embodiments, the width MW is in the range from approx. 0.5 cm to 30 cm.

[00111] According to some embodiments, the thickness IT is in the range from approx. 0.05 to 1 mm. According to some embodiments, the length IL is in the range from approx. 1 m to 40 m.

According to some embodiments, the width IW is in the range from approx. 0.5 cm to 30 cm.

[00112] According to some embodiments, the MW/MT ratio is at least 2.5 and in some embodiments is in the range of about 170 to 500.

[00113] According to some embodiments, the ratio IW/IT is at least 2.5 and in some embodiments ranges from about 1000 to 4000.

[00114] According to some embodiments, the edge sections 134G of the insulator plate 134 extend axially outward past the adjacent edges of the conductor foil 132 a distance 10 (FIG. 7). In some embodiments, the distance I0 is at least 1 mm and in some embodiments in the range from about 3 mm to 10 mm.

[00115] According to some embodiments, the coil 130 is formed by the following method. The conductor foil 132 is individually designed as a discrete band, strip, plate or foil. The insulator plate 134 is separately individually formed as a discrete band, strip, plate or foil. The preformed foil 132 and the preformed sheet 134 are then mated, laminated, or layered together and spirally wound into the spiral configuration to form the coil 130. In some embodiments, the layers 132, 134 are wound together around a cylindrical mandrel, mold, or support. In some embodiments, the layers 132 , 134 are wrapped around the connector 124 .

[00116] In some embodiments, the foil 132 and the plate 134 are not bonded to each other along their length before being wound into the coil. That is, the foil 132 and the sheet 134 are loosely wound and are not bonded or laminated to each other until after forming the coil 130. In some embodiments, the foil 132 and the sheet 134 are not bonded to each other in the finished coil 130 except at the encapsulation 128 at the ends of the coil 130. In this case, the foil 132 and the plate 134 are thus not bonded to each other across their width. In some embodiments, the foil 132 and the plate 134 are tightly wound so that air gaps between the turns of the conductor foil 132 are minimized or eliminated.

[00117] The terminal busbars 140, 142 may be formed from any suitable electrically conductive material. In some embodiments is

DK 202300051 Y3 14 the terminal busbars 140, 142 formed of metal. In some embodiments, the terminal busbars 140, 142 are formed of copper or tinned copper.

[00118] The inner terminal rail 140 (FIG. 2) includes a contact pin 140A and a terminal pin T1 connected via a connector pin 140B. The contact leg 140A is fixed in mechanical and electrical contact with the inner winding 136E of the conductor foil 132 by means of screws 5, nuts 6 and a clamping member or plate 141 (FIG. 8). The conductor foil winding 136E is inserted or clamped between the contact leg 140A and the clamping plate 141. The screws 5 penetrate the winding 136E and are fixed by the nuts 6, so that the contact leg 140A and the clamping plate 141 clamp together on the winding 136E in between. The terminal bone

T1 extends out of the housing 110 through an opening 116.

[00119] The outer terminal rail 142 (FIG. 2) includes a contact pin 142A and a terminal pin T2 connected via a connector pin 142B. The contact leg 142A is fixed in mechanical and electrical contact with the outermost winding 136F of the conductor foil 132 by means of screws 5, nuts 6 and a clamping plate 141 (FIG. 5).

The winding 136F is clamped between the contact leg 142A and the terminal plate 141 by means of the screws 5 (which penetrate the winding 136F) and the nuts 6 in the same manner as described above for the contact leg 140A, the screws 5, the nuts 6 and the terminal plate 141. The terminal leg T2 extends from the housing 110 through an opening 116.

[00120] The coil device 151 is constructed in the same manner as the coil device 131 and includes a multilayer coil 150, an inner terminal rail 160 and an inner terminal rail 162 corresponding to 130, the inner terminal rail 140 and the outer terminal rail 142. The coil 150 has a coil axis B-B.

[00121] The terminal leg T3 of the inner terminal rail 160 is fixed in mechanical and electrical contact with the inner winding 156E of the conductor foil of the coil 150 by means of screws 5, nuts 6 and a clamping plate 141 in the same way as described above for the contact leg 140A, the screws 5 , the nuts 6 and the clamping plate 141. The terminal leg T3 extends out of the housing 110 through an opening 116.

[00122] The terminal leg T4 of the outer terminal rail 162 is fixed in mechanical and electrical contact with the outermost winding 156F of the conductor foil of the coil 150 by means of screws 5, nuts 6 and a clamping plate 141 in the same way as described above for the contact leg 140A, the screws 5 , the nuts 6 and

DK 202300051 Y3 15 the terminal plate 141. The terminal leg T4 extends out of the housing 110 through an opening 116.

[00123] Thus, in accordance with some embodiments, the coils 130, 150 use a metal foil or conductor that is very thin (eg from 0.2 mm up to 1.5 mm) and very wide (eg from 30 mm up to 200 mm). This conductor is then wound in the form of a foil around a plastic cylinder (e.g. the connecting piece 124).

Between the turns of the foil, a thin insulating plate is used, which will provide sufficient insulation between the turns of the coil (eg from 5kV up to 20kV).

Busbars are connected to the inner and outer windings of the conductor foil and protrude from the housing. The busbars are further electrically insulated using heat-shrinkable electrically insulating sleeves. The heat-shrinkable sleeves can prevent overlap between the busbars and the rest of the coils. The coils are covered inside a plastic housing and then encapsulated with epoxy resin to provide electrical insulation between the turns of the conductor foil at the two axial ends of the coil. Furthermore, the encapsulation prevents moisture from entering the coil, which can reduce the insulation of the coil or degrade the insulation properties of the insulation used. Furthermore, the enclosure will also make the coil more stable in case of vibrations and also increase the insulation between the coil's two outputs.

[00124] According to method embodiments, the inductor device 100 is a two-phase coil used in a two-phase alternating current electrical system 7 as illustrated by the diagram in FIG. 11. The input of line L1 is connected to terminal T2, and the output of line L1 is connected to terminal T1.

The input of line L2 is connected to terminal T3, and the output of line L2 is connected to terminal T4. In some embodiments, the alternating current system has a voltage L1-L2 of about 650 Vrms and a load current of approx. 100A.

Circuit breakers may be provided between the input terminals T2, T3 of the inductor device 100 and the power supply. The output terminals T1, T4 of the inductor devices 100 may be connected to a power distribution panel.

[00125] In the event of a surge current (high di/dt) in one wire, the insulating tube 129 will insulate the covered terminal rail, thereby preventing flashover between the coil connected to that wire and a terminal rail on the other coil. For example, it can be seen in FIG. 3, that the connecting leg 140B of the busbar 140 extends along the length of the coil 150. When a surge current is applied to the coil 150, the tube 129 on the terminal rail 140 can prevent flashover from the coil 150 to the connecting leg 140B of the busbar 140.

DK 202300051 Y3 16

[00126] The encapsulation 128 (e.g., epoxy resin) covers the ends of the coils 130, 150 and thereby stabilizes the coils 130, 150 and increases the electrical isolation between the turns of the conductor foil (e.g., the conductor foil 132) within each coil 130, 150 The enclosure 128 also increases the electrical isolation between the adjacent ends of the two coils 130, 150. The enclosure 128 further increases the electrical isolation between the coils 130, 150 and the busbars 140, 142, 160, 162.

[00127] The outer plastic housing 110 can withstand vibration and provide environmental protection for the coils 130, 150. The housing 110 also increases the electrical insulation of the coils 130, 150. The strong mounting brackets or bases 120 and the support shaft 122 can ensure that the inductor device 100 can withstand vibration .

[00128] The bushings 126 may serve to accommodate manufacturing tolerances in the inductor device 100 and thereby reduce vibration. The bushings 126 may also serve to dampen or absorb forces (eg, vibrations) applied to the inductor device 100. The bushings 126 may also resiliently and temporarily accommodate expansion of the inductor device 100 caused by heating of the coils 130, 150.

[00129] The enclosure can also accommodate manufacturing tolerances in the inductor device 100 and thereby reduce vibration.

[00130] Since screws 5 or other fasteners and clamp plates 141 are used to attach the busbars 140, 142, 160, 162 to the inner and outer windings 136E, 136F, 156E, 156F, it is not necessary to use a welding or soldering technique, that can melt the thin coil conductor foil.

[00131] FIG. 12-14 show an inductor device 200 according to further embodiments of the invention. Inductor assembly 200 is constructed in the same manner as inductor assembly 100, but includes only a single coil assembly 231. Coil assembly 231 includes a coil 230 and terminal busbars 240, 242 similar to and constructed in the same manner as described for coil assembly 131, coil 130, and terminal busbars 140, 142 .The terminal busbars 240, 242 have terminal pins T1 and T2 corresponding to the terminal pins T1 and T2 of the inductor device 100.

[00132] As shown schematically in FIG. 14, the inductor device 200 can be connected in series to the protective earth (PE) of a power system 9 with a voltage of 650 Vrms between its wires and a load current of 100A.

The inductor device 200 may be rated for half the actual line currents (ie about 50A) in accordance with relevant

DK 202300051 Y3 17 standards. The output T1 of the inductor device 200 is connected to the PE terminals inside a distribution panel.

[00133] According to some embodiments of the invention, an inductor device as described herein has a specific load current of about 100 A, can operate in a normal low voltage (LV) application (up to 1000Vac), is capable of withstanding very high transient overvoltage events, that can develop across its ends (in the 100kV range), is capable of withstanding extreme vibrating conditions, is capable of being installed in outdoor environments, substantially reduces or minimizes the risk of fire under fault, has a small area and a small size (eg, less than 43,000 cm3), and is relatively light (eg, less than 25 kg).

[00134] FIG. 15-24 show a dual coil inductor device 300 according to further embodiments of the invention. The inductor device 300 is constructed in the same way as the inductor device 100, but is configured such that the terminal legs T1, T2 extend from one axial end 302A of the inductor device 300, and the terminal legs T3, T4 extend from the opposite axial end 302B of the inductor device 300.

[00135] The inductor assembly 300 includes a housing assembly 310, a pair of axially spaced support bases 320, a support shaft 322, an electrically insulating connector 324, a pair of bushings 326, enclosure 328, insulating sleeve or tube 329, a first coil assembly 331, and a second coil assembly 351 corresponding to components 110, 120, 122, 124, 126, 128, 129, 131 and 151, respectively, except as shown and described.

[00136] Housing assembly 310 includes a pair of axially opposed cylindrical cup-shaped shells 314 and a pair of axially opposed end plates 312A and 312B.

Each shell 314 defines a chamber 318 to contain a respective one of the devices 331, 351 and the enclosure 328. Two terminal openings 316 are defined in each end plate 312 and communicate with the adjacent chamber 318. An electrically insulating spacer bushing 315 is interposed between the adjacent inner ends of the shells 314. The partition bushing 315 may be formed of a material as described above for the bushings 126.

[00137] The coil assemblies 331, 351 are constructed in the same manner as the coil assemblies 131, 151 except in the configuration of their terminal busbars 340, 342, 360, 362. Referring to FIG. 21, the terminal rail 340 is connected to the inner winding 336E of the coil 330 and

DK 202300051 Y3 18 has a terminal leg T1 that extends through an opening 316 in the end plate 312A. Referring to FIG. 22, the terminal rail 342 is connected to the outermost winding 336F of the coil 330 and has a terminal leg T2 extending through the second opening 316 in the end plate 312A. The terminal rail 360 is connected to the inner winding of the coil 350 and has a terminal leg T3 extending through an opening 316 in the end plate 312B. The terminal rail 362 is connected to the outermost winding of the coil 350 and has a terminal leg T4 extending through the second opening 316 in the end plate 312B. Each terminal leg T1, T2, T3, T4 is covered by an insulating tube 329 extending through the respective opening 316. Each terminal leg T1, T2, T3, T4 may further be covered by an inner insulating tube 327 within the insulating tube 329.

The insulating tube 327 can be formed from the same material as described for the insulating tube 129.

[00138] FIG. 19-23 show the coil assembly 331 in more detail.

The coil assembly 351 is constructed in the same manner as the coil assembly 331. As can be seen in FIG. 19-23, the coil 330 includes a foil 332, an insulator plate 334, clamp plates 341 and fasteners 5, 6 corresponding to and assembled in the same manner as the components 132, 134, 141, 5 and 6, respectively, of the coil assembly 131. The end of the inner winding 336E of the foil 332 is mechanically fixed in electrical contact with the terminal rail 340 by means of a terminal plate 341A and fasteners 5, 6. The busbar 340, the terminal plate 341A and the winding 336E can be received in a slot in the connector 324 as shown. The end of the outermost winding 336F of the foil 332 is mechanically fixed in electrical contact with the terminal rail 342 by means of a clamping plate 341 and fasteners 5, 6.

[00139] As will be understood from FIG. 16, the dual coil inductor assembly 300 has a longitudinal axis L-L, the coil 330 has a coil axis A-A, and the coil 350 has a coil axis B-B. The coil axes A-A, B-B are substantially parallel to, and in some embodiments substantially coaxial with, the axis L-L. In some embodiments, the coil axes A-A, B-B are substantially parallel to each other. The terminal legs T1, T2, T3, T4 each extend or protrude axially from one end 302A, 302B of the inductor device 300 in a direction along the axis L-L. In some embodiments, the terminal legs T1, T2, T3, T4 each extend along an axis substantially parallel to the axis L-L.

DK 202300051 Y3 19

[00140] Thus, the input terminal T1 and the output terminal T2 of the coil 330 extend from the same end 302A of the unit 300. The input terminal T3 and the output terminal T4 of the coil 350 extend from the same opposite end 302B of the unit 300. This construction can enable the coils 330, 350 to be better insulated from each other because there is no terminal rail from one coil 330, 350 extending over the other coil 330, 350.

[00141] The terminal configuration of the inductor device 300 also allows the device with of a multi-unit inductor system 301 as shown in FIG. 24 and 26 for example. System 301 includes a plurality (as shown four) of dual coil inductor devices 300A-D (each constructed as described for device 300) in a relatively compact side-by-side arrangement.

The inductor coils 330 of the inductor devices 300A-D are connected to line L1 and to each other in series by connecting conductors 7 (e.g. metal cables).

The inductor coils 350 of the inductor devices 300A-D are connected to the line L2 and to each other in series by connecting conductors 7 (e.g. metal cables).

[00142] In the system 301, the longitudinal axes L-L of the inductor devices 300A-D extend non-coaxially to each other. That is, the respective longitudinal axes

L-L of the inductor devices 300A-D extend (as shown) substantially parallel to each other but laterally offset from each other, or may extend across each other.

[00143] The configuration of the system 301 avoids a coaxial configuration of inductor devices 100A-D as shown in the inductor system 101 of FIG. 25, for example, where a common central metal post 122' supports each of the coils 130, 150 of the multi-inductor devices 100A-D. In the system 101, the dielectric withstand voltage of the system 101 may be limited by the distance D1 between each terminal T1, T2, T3, T4 and the adjacent base 120. In the event of a lightning strike or other overvoltage event, the induced voltage on the coil terminals due to the high di/dt result in an estimate; as a result, the current can switch from a terminal T1-T4 to the adjacent base 120, and from the base 120, the current can be passed through the central metal post 122' to the high voltage HV side of the circuit, thereby shorting around the coils 130, 150 of the downstream the inductor devices 100A-D. That is, the total dielectric withstand voltage of the system 101 is reduced because

DK 202300051 Y3 20 the voltage potential between the ends LV, HV of the circuit is bridged by the central metal post 122".

[00144] In contrast, and with reference to FIG. 26, in system 301, current from a lightning surge or other surge event may still trip, due to induced lightning impulse voltage from the high di/di, from a terminal T1, T2,

T3, T4 to the adjacent base 320 across a distance D2. However, in order for the current to lead to the next inductor device 300B-D, the current must travel a distance D3 from the base 320 of the first inductor device 300A to the base 320 of the inductor device 300B. The distances between the bases 320 of the adjacent inductor devices 300A-D can be chosen to provide an increased and sufficient dielectric withstand voltage between the inductor devices 300A-

D and for the system 301 in general. In this way, a high amount of electrical isolation is achieved between the inductor devices 300A-D. As a result, the overall lightning impulse overvoltage of the overall system 301 is maintained from the LV side to the HV side. For example, if the lightning impulse breakdown voltage of each inductor device 300A-D is 100 kV, then the total lightning impulse breakdown voltage of system 301 will be 400 kV. This can be accomplished while maintaining an electrically conductive metal support shaft 322 in each inductor device 300A-D. A metal support shaft 322 may be desirable to provide improved strength, thermal conductivity, resistance to thermal damage (eg, melting), and ease and flexibility of manufacture.

[00145] The spacer 315 can electrically isolate the coil devices 331, 351 from each other. The spacer 315 may serve to accommodate manufacturing tolerances in the inductor device 300 and thereby reduce vibration. The spacer bushing 315 may also serve to dampen or absorb forces (eg, vibrations) applied to the inductor device 300. The spacer bushing 315 may also resiliently and temporarily accommodate expansion of the inductor device 300 caused by heating of the coils 330, 350.

[00146] FIG. 27-29 show an inductor device 400 according to further embodiments of the invention. Inductor assembly 400 is constructed in the same manner as inductor assembly 300, but includes only a single coil assembly 431. Coil assembly 431 includes a coil 430 and terminal busbars 440, 442 similar to and constructed in the same manner as described for coil assembly 131, coil 130 and terminal busbars 140,

DK 202300051 Y3 21 142. The terminal busbars 440, 442 have terminal pins T1 and T2 corresponding to the terminal pins T1 and T2 on the inductor device 300.

[00147] The inductor assembly 400 has a longitudinal axis L-L and the coil 430 has a coil axis A-A. The coil axis A-A is substantially parallel to, and in some embodiments substantially coaxial with, the axis L-L. The terminal legs T1, T2 each extend and project axially from the end 410A of the inductor device 400 in a direction along the axis L-L. In some embodiments, the terminal legs T1, T2 each extend along an axis substantially parallel to the axis L-L. Thus, the input terminal T1 and the output terminal span

T2 of the coil 430 from the same end 402B of the device 400 as discussed above with respect to the inductor device 300.

[00148] A plurality of the inductor devices 300 can be assembled into a multi-unit inductor system 401 as shown in FIG. 29, for example. System 401 includes a plurality (as shown four) of inductor devices 400A-D (each constructed as described for device 400) in a relatively compact side-by-side arrangement.

The inductor coils 430 of the inductor devices 400A-D are connected to the line L1 and to each other in series by connecting conductors 7 (e.g. metal cables).

[00149] In the system 401, the longitudinal axes L-L of the inductor devices 400A-D extend non-coaxially to each other. That is, the respective longitudinal axes

L-L of the inductor devices 400A-D extend (as shown) substantially parallel to each other but laterally offset from each other, or may extend across each other. Thus, this configuration may provide the advantages discussed above with respect to the inductor assembly 300.

[00150] Referring to FIG. 31-34, a coil assembly 531 according to further embodiments is shown therein. The spool device 531 can be used instead of any of the spool devices 131, 151, 231, 331, 351, 431.

The spool assembly 531 is constructed and operates in the same manner as the spool assembly 331, except as follows.

[00151] The coil assembly 331 includes a coil 530 that differs from the coil 330 as described below. The coil assembly 531 also includes terminal busbars 540 , 542 , clamp plates 341 , and fasteners 5 , 6 similar to and assembled in the same manner as the components 340 , 342 , 341 , 5 , and 6 , respectively, of the coil assembly 331 .

DK 202300051 Y3 22

[00152] The coil 530 includes a first foil 532 and an insulator plate 534 corresponding to the foil 332 and the insulator plate 334. The coil 530 further includes a second conductor or foil 533. The first and second foils 532, 533 together form an electrical multilayer conductor 537. The foils 532 , 533 can be formed from the same materials and in the same dimensions as described above for the foil 132.

[00153] The first foil 532, the second foil 533 and the insulator plate 534 are spirally interlaced or wound about the coil axis A-A to form windings 536 with the second foil 533 sandwiched or sandwiched between the first foil 532 and the insulator plate 534. The windings 536 extend progressively from an inner winding 536E of the multilayer conductor 537 (ie, the conductor foils 532, 533) to an outer winding 536F of the multilayer conductor 537 (ie, the conductor foils 532, 533) on the outer diameter of the coil 530. Each winding 536 is radially superimposed on, stacked on, or wrapped around the preceding winding 536. The foils 532, 533 may be tightly wound so that they actually make electrical contact with each other.

[00154] Each of the conductor foils 532, 533 has opposite side edges that are axially spaced along the coil axis A-A and extend substantially parallel to each other. Conductor foils 532, 533 are spirally wound such that each side edge remains substantially in or near a single lateral plane (ie corresponding to planes E-E in

FIG. 7) through coil 530 from winding 536E to winding 536F. That is, the multilayer conductor 537 and the conductor foils 532, 533 are held in line with themselves and are spirally, not screw-wound. In some embodiments, the conductor foils 532, 533 have substantially the same extent.

[00155] The end of the inner winding 536E of the multilayer conductor (ie, the ends of the foil 532 and the foil 533) is mechanically fixed in electrical contact with the terminal rail 540 by means of the terminal plate 541A and fasteners 5, 6. The busbar 540, the terminal plate 541A and the winding 536E can be received in a slot in connector 524 as shown. The end of the outermost winding 536F of the multilayer conductor (ie, the ends of the foil 532 and the foil 533) is mechanically fixed in electrical contact with the terminal rail 542 by means of the terminal plate 541 and fasteners 5, 6.

[00156] The multilayer conductor 537 has an increased cross-sectional area compared to the foil 132 and thereby provides less electrical resistance for a conductor of the same length. As a result, the coil 530 (and thereby an inductor device incorporating the coil device 531) can be rated for a larger current and power.

DK 202300051 Y3 23

[00157] For example, the two-phase inductor device 300 may be rated at 100A for each line L1, L2 (with the load currents through L1 and L2). The PE inductor device 400 may be rated at 50A (ie half the capacity of the wire coil). In this case, the coils of the inductor devices 300, 400 each use a single conductor foil.

[00158] The parallel, superimposed conductor foils 532, 533 of the multilayer conductor 537 double the cross-sectional area of the coil conductor compared to the single foil conductors of the inductor devices 300, 400. As a result, the two-phase inductor device incorporating the coil device 531 can be rated at 150A for each wire L1, L2, and the PE inductor device incorporating the coil device 531 may be rated at 75A.

[00159] In some embodiments, foil 532, foil 533, and insulator plate 534 are not bonded together along their length prior to winding into the coil. That is, the foils 532, 533 and the plate 534 are loosely intertwined and are not bonded or laminated to each other until after forming the coil 530. In some embodiments, the foils 532, 533 and the insulator plate 534 are not bonded to each other in the finished coil 130 except by the casing 528 at the ends of the coil 530. In this case, the layers 532, 533, 534 are not bonded to each other across their width. In some embodiments, foils 532, 533 and plate 534 are tightly wound so that air gaps between the turns of conductor foils 532, 533 are minimized or eliminated.

[00160] The multilayer conductor 537 provides advantages over using a thicker single foil for the coil conductor (eg, two 0.8 mm foils 522, 533 instead of a single 1.6 mm foil 132) because a thicker single foil can be too thick to make the turns effectively (ie without creating gaps between the turns of the coil, etc.). The outer diameter of coil 530 can be increased modestly compared to the diameter of coil 130 while maintaining the same coil length. On the other hand, if the conductor cross-section were increased using the same thickness of foil 132 (eg, 0.8 mm) but doubling the width of foil 132, then the coil area would be essentially twice the length, which may require the inductor device to have an undesirable area.

[00161] Referring to FIG. 35-48, a combined dual coil inductor device 600 according to embodiments of the invention is shown therein.

The inductor device 600 is constructed in the same manner as the inductor devices 100 and 300, but is configured so that two

DK 202300051 Y3 24 independent coils 630 and 650 are intertwined and integrated into a single coil device 631.

[00162] Referring to FIG. 35-37, the inductor assembly 600 includes a housing assembly 610, a pair of axially spaced support bases 620, a support shaft 622, an electrically insulating connector 624, a pair of bushings 626, enclosure 628, and insulating sleeves or tubes 629 corresponding to components 110, 120, 122, 124, 126, 128 and 129, except as shown and discussed.

The inductor device 600 includes terminal legs T1, T2 extending from an axial end 602A of the inductor device 600 and terminal legs T3, T4 extending from the opposite axial end 602B of the inductor device 600.

The double coil device 631 is placed in the housing device 610 as described above.

[00163] Referring to FIG. 38-41, the coil assembly 631 includes a first coil 630 and a second coil 650 that are combined to form a combined coil 639 as described below. The coil assembly 631 also includes terminal busbars 640, 642, 660, 662, clamp plates 641, and fasteners 5, 6 (FIGS. 42-44) corresponding to components 340, 342, 360, 362, 341, 5, and 6 of the coil assembly 331, respectively.

[00164] The combined coil 639 includes a first foil 632, a second foil 652, a first insulator plate 634, and a second insulator plate 654. When spirally wound as described below and as shown, the first foil 632 forms the first coil 630. When it is spiral wound as described below and as shown, the second foil 652 forms the second coil 650.

[00165] Foils 632, 652 may be constructed and formed in the same manner as described for foil 132. Foil 632 has an inner end 632A (FIGS. 38 and 42) and an opposite outer end 632B (FIGS. 38 and 43). The foil 652 has an inner end 652A (FIGS. 38 and 42) and an opposite outer end 652B (FIGS. 40 and 44). The insulator plates 634, 654 may be constructed and formed in the same manner as described for the insulator plate 134.

[00166] The first foil 632, the second foil 652, the first insulator plate 634, and the second insulator plate 654 are spirally interwoven or wound about the coil axis A-A to form windings 636 with the insulator plates 634, 654 interposed or placed between the first foil 632 and the second foil 652. The windings 636 extend successively or progressively from an innermost winding 636E of the foils 632, 652 to an outermost winding 636F of the foils 632, 652 on the outer diameter of the

DK 202300051 Y3 25 combined coil 639. Each winding 636 is radially superimposed on, stacked on, or wound around the previous winding 636. The foils 632, 652 and the insulator plates 634, 654 may be tightly wound in side-to-side contact with each other. That is, each insulator plate 634, 654 is in side-to-side contact with the metal foils 632, 652 on each side of the insulator plate 634, 654, but the metal foils 632, 652 are not in side-to-side contact with each other. The foils 632, 652 are not in electrical contact with each other, but are electromagnetically coupled, as described herein.

[00167] FIG. 47 is a fragmentary side view of the conductor foils 632, 652 and insulator plates 634, 654 shown flattened prior to winding to form the combined coil 639. FIG. 48 is an exploded, fragmentary perspective view of the conductor foils 632, 652 and insulator plates 634, 654 shown flattened prior to winding to form the combined coil 639

[00168] As shown in FIG. 42-44, 47 and 48, foils 632, 652 and insulator plates 634, 654 are interlaced such that foils 632, 652 are electrically isolated from each other by insulator plates 634, 654 along the entire length of each foil 632, 652.

[00169] Each of the conductor foils 632, 652 has opposite side edges that are axially spaced along the coil axis A-A and extend substantially parallel to each other. Conductor foils 632, 652 are spirally wound such that each side edge remains substantially in or near a single lateral plane (ie, corresponding to planes E-E in

FIG. 7) through coil 639 from winding 636E to winding 636F. That is, the conductor foils 632, 652 are held in line with themselves and are spirally, not screw-wound. In some embodiments, the conductor foils 632, 652 each extend all the way from the outer surface of the inner winding 636E to the outer winding 636F.

[00170] In some embodiments, the foils 632, 652 and the insulator plates 634, 654 are not bonded together along their length before being wound into the coil. That is, the foils 632, 652 and insulator plates 634, 654 are loosely intertwined and are not bonded or laminated to each other until after the formation of the combined coil 639. In some embodiments, the foils 632, 652 and insulator plates 634, 654 are not bonded to each other in the finished combined coil 639 except for the encapsulation 628 at the ends of the combined coil 639. In this case, the layers 632, 652, 634, 654 are not bonded to each other across their width. In some embodiments, foils 632, 652 and insulator plates 634, 654 are tightly wound so that air gaps between the windings of conductor foils 632, 652 and insulator plates 634, 654 are minimized or eliminated while improving electromagnetic coupling.

DK 202300051 Y3 26

[00171] As shown in FIG. 37 and 42, the terminal leg T1 is electrically connected to the conductor foil 632 at a first location. In some embodiments and as shown, the first location is close to (ie, at or near) the inner end 632A of the foil 632.

More specifically, the end of the inner winding 636E of the conductor foil 632 is mechanically fixed in electrical contact with the terminal rail 640 by means of a terminal plate 641 and fasteners 5, 6. The busbar 640, the terminal plate 641 and the conductor foil 632 can be received in a slot in the connector 624 as shown .

[00172] As shown in FIG. 37 and 43, the terminal leg T2 is electrically connected to the conductor foil 632 at a second location spaced from the first location along the length of the foil 632. In some embodiments and as shown, the second location is close to (ie, at or near) the outer end 632B of the foil 632. More specifically, the end of the outermost winding 636F of the foil 632 is mechanically secured in electrical contact with the terminal rail 642 by means of a clamping plate 641 and fasteners 5, 6.

[00173] As shown in FIG. 37 and 42, the terminal leg T3 is electrically connected to the conductor foil 652 at a first location. In some embodiments and as shown, the first location is close to (ie, at or near) the inner end 652A of the foil 652 .

More specifically, the end of the inner winding 636E of the conductor foil 652 is mechanically fixed in electrical contact with the terminal rail 660 by means of a terminal plate 641 and fasteners 5, 6. The bus bar 660, the terminal plate 641 and the conductor foil 652 can be received in a slot in the connector 624 as shown .

[00174] As shown in FIG. 37 and 44, the terminal leg T4 is electrically connected to the conductor foil 652 at a second location spaced from the first location along the length of the foil 652. In some embodiments and as shown, the second location is close to (ie, at or near) the outer end 652B of the foil 652. More specifically, the end of the outermost winding 636F of the foil 652 is mechanically secured in electrical contact with the terminal rail 662 by means of a clamping plate 641 and fasteners 5, 6.

[00175] The busbar 640 serves as a wire or terminal (T1) to the inner end 632A of the foil 632. The busbar 642 serves as a wire or terminal (T2) to the outer end 632B of the foil 632. The electrical connection points between the terminals T1, T2 and the foil 632 are separated along the length of the foil 632 and are separated by the coil 630 turns.

[00176] The busbar 660 serves as a wire or terminal (T3) to the inner end 652A of the foil 652. The busbar 662 serves as a wire or terminal

DK 202300051 Y3 27 (T4) to the outer end 652B of the foil 652. The electrical connection points between the terminals T3, T4 and the foil 652 are spaced along the length of the foil 652 and are separated by the turns of the coil 650.

[00177] The dual-coil inductor device 600 may be used instead of the inductor devices 100 and 300. According to method embodiments, the inductor device 600 is used in an AC electrical system 11 that includes a phase line L1 and a neutral line N as illustrated by the diagram in FIG. 45. The input of the wire L1 is connected to the terminal T1 of the inductor device 600, and the output of the wire L1 is connected to the terminal T2 of the inductor device 600. The input of the neutral wire N is connected to the terminal T3 of the inductor device 600, and the output of the neutral wire N is connected to the terminal T4 of the inductor device 600.

In some embodiments, the alternating current system has a voltage L1-N of about 650

Vrms and a load current of approx. 100A. Circuit breakers may be provided between the input terminals T1, T3 of the inductor assembly 600 and the power supply. The output terminals T2, T4 of the inductor devices 600 may be connected to a power distribution panel.

[00178] According to other embodiments, the inductor device 600 is used in a two-phase alternating current electrical system 12 as illustrated by the diagram in FIG. 46.

The input of wire L1 is connected to terminal T1 of inductor assembly 600, and the output of wire L1 is connected to terminal T2 of inductor assembly 600. The input of wire L2 is connected to terminal T3 of inductor assembly 600, and the output of wire L2 is connected to terminal T4 on the inductor assembly 600. In some embodiments, the AC system has a voltage L1-L2 of about 650 Vrms and a load current of approx. 100A. Circuit breakers may be provided between the input terminals T2, T3 of the inductor device 600 and the power supply.

The output terminals T1, T4 of the inductor devices 600 may be connected to a power distribution panel.

[00179] It will be appreciated that coils 630 and 650 are effectively nested within each other.

This construction can reduce the size, weight and cost of the inductor device 600 compared to e.g. the inductor device 300.

[00180] This construction can also improve the ability of the inductor device to withstand vibrations.

DK 202300051 Y3 28

[00181] Coils 630 and 650 are electromagnetically coupled to each other. By interwinding the coils 630, 650 as described (ie spirally winding the conductor foils 632 and 652 together), the mutual inductance and inductive electromagnetic coupling between the coils 630, 650 is increased. This allows the combined coil 639 to achieve a greater inductance value by using individual coils 630, 650 with lower individual inductance values. As a result, the coils 630, 650 can be formed with fewer turns and the size and weight of the combined coil 639 can be smaller for the same total inductance value compared to e.g. the inductor device 300.

[00182] In some embodiments, the coefficient of inductive coupling between coils 630 and 650 is, for example, about 0.9 against a coefficient for inductive coupling between the coils 330 and 350 of approx. 0.13 for the inductor device 300.

As a result, the inductor device 600 may include coils 630, 650 each having an individual inductance value of about 500 pH each to achieve an effective total inductance on wire L1 or wire N of approx. 900 pH.

[00183] Embodiments of the combined dual inductor device (e.g., the inductor device 600) can provide a very high voltage isolation level of about 400 kV along each line (L1, L2, or N) and about 30 kV between the two lines (e.g. .between L1 and N or between L1 and L2).

[00184] In alternative embodiments, either (ie, one or both) of the conductor foils 632 , 652 may be replaced with a pair of foils in side-by-side electrical contact as described above for the multilayer conductor 537 .

[00185] Referring to FIG. 49 and 50, a combined dual coil inductor device 700 according to further embodiments of the invention is shown therein.

The inductor assembly 700 is constructed in the same manner as, and may be used in the same manner as, the dual coil inductor assembly 600, except as described below.

[00186] The dual-coil inductor device 700 includes a coil device 731 constructed substantially in the same manner as the coil device 631. The dual-coil inductor device 700 also includes terminal busbars 740, 742, 760, and 762 corresponding to the terminal busbars 640, 642, 660, and 662.

[00187] The terminal busbars 740, 742, 760 and 762 form the terminals T1,

T2, T3 and T4. The terminal busbars 740, 742, 760 and 762 are respectively connected to the innermost winding 736E of the first coil 730 (corresponding to the coil 630), the outermost winding 736F of the first coil 730, the innermost winding 736E

DK 202300051 Y3 29 of the second coil 750 (corresponding to the coil 650) and the outermost winding 736F of the second coil 750, in the same way as described for the terminal busbars 640, 642, 660 and 662.

[00188] The dual coil inductor device 700 differs from the dual coil inductor device 600 in that the terminal legs T1 and T3 extend from one end of the coil device 631 and the terminal legs T2 and T4 extend from the opposite end of the coil device 631. Each of the coils 730 , 750 thus has one of its terminal legs T1, T4, T3, T4 on each end of the coil device 731.

[00189] Referring to FIG. 51-54, a combined dual coil inductor device 800 according to further embodiments of the invention is shown therein.

The inductor assembly 800 is constructed in the same manner as, and may be used in the same manner as, the dual coil inductor assembly 600, except as described below.

[00190] The combined dual coil inductor device 800 includes an inner coil 830 and an outer coil 850 which are combined or radially stacked to form a combined coil device 839. The coils 830 and 850 are not interwound as in the dual coil inductor device 600.

[00191] The inductor assembly 800 includes a housing 810, a pair of axially spaced support bases 820, a support shaft 822, an electrically insulating connector 824, enclosure 828, insulating sleeve or tube 829, a first or inner coil assembly 8, a second or outer coil assembly 851 and an intermediate coil electrical insulation layer 870. The housing 810, support bases 820, support shaft 822, enclosure 828, and insulating sleeves or tubes 829 may be constructed in the same manner as the housing 110, support bases 120, support shaft 122, electrically insulating connector 124, enclosure 124, and insulating sleeves or the tubes 129 for example. The enclosure 828 is not shown in FIG. 54.

[00192] The inner coil device 831 includes a multilayer coil 830, an inner terminal rail 840, and an outer terminal rail 842. The inner coil device 831, the inner coil 830, the inner terminal rail 840, and the outer terminal rail 842 are constructed in substantially the same manner as the coil assembly 131, the inner coil 130, the inner terminal rail 140 and the outer terminal bus rail 142 (FIGS. 6-10).

[00193] The inner coil 830 is an air core coil. Referring to FIG. 52, the inner coil 830 includes an electrically conductive conductor plate, strip, or foil

DK 202300051 Y3 30 832 (corresponding to the foil 132) and an electrically insulating insulator strip or plate 834 (corresponding to the insulating plate 134). The foil 832 and the plate 834 are spirally wound together or wound about a coil axis A-A to form windings 836, as described for the coil 130.

[00194] The inner terminal rail 840 includes a contact leg 840A and a terminal leg T1. The contact leg 840A is secured in mechanical and electrical contact with the inner winding 836E of the conductor foil 832 by means of a clamping member or plate 841 and fasteners as described above for the coil 130.

The terminal leg T1 extends out of the housing 810 through an opening.

[00195] The outer terminal rail 842 includes a contact leg 842A and a terminal leg T2. The contact leg 842A is secured in mechanical and electrical contact with the outermost winding 836F of the conductor foil 832 by means of a clamping member or plate 841 and fasteners as described above for the coil 130.

The terminal leg T2 extends out of the housing 810 through an opening.

[00196] The outer coil device 851 includes a multilayer coil 850, an inner terminal rail 860, and an outer terminal rail 862. The inner coil device 851, the inner coil 850, the inner terminal rail 860, and the outer terminal rail 862 are constructed in substantially the same manner as the coil assembly 131, the inner coil 130, the inner terminal rail 140 and the outer terminal rail 142 (FIGS. 6-10).

[00197] The outer coil 850 is an air core coil. Referring to FIG. 52, the outer coil 850 includes an electrically conductive conductor sheet, strip or foil 852 (corresponding to the foil 132) and an electrically insulating insulator strip or sheet 854 (corresponding to the insulating sheet 134). The foil 852 and the sheet 854 are spirally wound together or wound about the coil axis A-A to form windings 856, as described for the coil 130.

[00198] The inner terminal rail 860 includes a contact leg 860A and a terminal leg T3. The contact leg 860A is secured in mechanical and electrical contact with the inner winding 856E of the conductor foil 852 by means of a clamping member or plate 841 and fasteners as described above for the coil 130.

The terminal leg T3 extends out of the housing 810 through an opening.

[00199] The outer terminal rail 862 includes a contact leg 862A and a terminal leg T4. The contact leg 862A is fixed in mechanical and electrical contact with the outermost winding 856F of the conductor foil 852 by means of a clamping element or

DK 202300051 Y3 31 plate 841 and fasteners as described above for coil 130.

The terminal leg T4 extends out of the housing 810 through an opening.

[00200] The insulating layer 870 may be tubular. The insulating layer 870 defines an internal cavity or passage 870B. Each terminal leg T1, T2, T3, T4 is covered by an insulating tube 829 extending through the respective opening of the housing 810.

The insulating tubes 829 may be constructed as described for the insulating tubes 129.

[00201] The inter-coil electrical insulation layer 870 may be formed of any suitable material and in any suitable shape. In some embodiments, the inter-coil electrical insulation layer 870 is or includes a tubular layer or element of electrical insulating material. In some embodiments, the intermediate coil electrical insulation layer 870 is or includes a helically wound or twisted sheet or web of electrical insulating material.

The insulation layer 870 may be formed of a plurality of rigid insulation elements which are combined to form the tubular structure. In some embodiments and as shown in FIG. 51 and 54, the insulating layer 870 includes a single tubular element. In some embodiments, one or more axially extending channels 870A (FIG. 54) are defined in the insulating layer 870 and conformably receive the busbars 842, 860.

[00202] The inner coil assembly 830 is mounted around or on the insulating connector 824 such that the connector 824 extends through the inner passage or air core 838 of the coil 830. The outer coil 850 is again mounted around or around the inner coil 830. inter-coil electrical insulating layers 870 are disposed radially between the coil devices 831, 851 to prevent electrical contact between the electrically conductive components (ie the foils and busbars) of the respective coils. The inner coil 830 is placed in the inner cavity 870B of the insulating layer 870.

[00203] The dual coil inductor device 800 may be formed by wrapping the foil 832 and insulating layer 834 around the connector 824 (to form the coil 830), mounting the inter-coil electrical insulating layer 870 over the coil 830, and wrapping the foil 852 and insulating layer 854 around the electrical intermediate coil insulation layer 870. Foil 832 and foil 852 are each wound about axis A-A and in some embodiments are wound concentrically.

[00204] The outer coil 850 circumferentially surrounds the inner coil 830. That is, the outer coil 850 is radially superimposed over the inner coil 830, and the inner

DK 202300051 Y3 32 coil 830 is placed in the inner passage or air core 858 of the outer coil 850. The outer coil 850 and the inner coil 830 are electrically isolated from each other. The inner foil 832 is not spirally wound with the outer foil 854 as in the dual-coil inductor device 700. The innermost winding 856E of the foil 852 is located radially outward past the outermost winding 836F of the foil 832. The ends of the foils 832, 852 are terminated by respective busbars 840. , 842, 860 and 862, which provide respective terminals T1, T2, T3 and T4 to form external connections.

[00205] In some embodiments, the inner coil 830 and the outer coil 850 are concentric.

[00206] As discussed above, the coil assemblies 831 , 851 and the coils 830 , 850 in some embodiments are constructed (including components, arrangements, materials, dimensions, and assembly methods) as described above with respect to the coil assembly 131 and the coil 130 .

[00207] While a separate insulating layer 870 is shown to provide electrical isolation between the electrically conductive components of the coil devices 831, 851, in other embodiments the insulating layer 834, 854 of one of the coils 830, 850 may be extended to wrap completely around the outer surface of the coil assembly 831 to electrically isolate the coil assembly 831 from the coil assembly 851.

[00208] In alternative embodiments, either (ie, one or both) of the conductor foils 832 , 852 can be replaced with a pair of foils in side-to-side contact as described above for the multilayer conductor 537 .

[00209] The double-coil inductor device 800 may be used instead of the inductor device 600. According to method embodiments, the inductor device 800 is used in an AC electrical system 11 that includes a phase line L1 and a neutral line N as illustrated by the diagram in FIG. 45.

The input of the wire L1 is connected to the terminal T1 of the dual-coil inductor device 800, and the output of the wire L1 is connected to the terminal T2 of the dual-coil inductor device 800. The input of the neutral wire N is connected to the terminal T3 of the dual-coil inductor device 800, and the output of the neutral wire N is connected to the terminal T4 of the dual coil inductor device 800. In some embodiments, the alternating current system has a voltage L1-N of about 650 Vrms and a load current of approx. 100A. Circuit breakers may be provided

DK 202300051 Y3 33 between the input terminals T1, T3 on the inductor device 800 and the power supply. The output terminals T2, T4 of the inductor devices 800 may be connected to a power distribution panel.

[00210] According to other embodiments, the inductor device 800 is used in a two-phase alternating current electrical system 12 as illustrated by the diagram in FIG. 46.

The input of wire L1 is connected to the terminal T1 of the dual-coil inductor device 800, and the output of the wire L1 is connected to the terminal T2 of the dual-coil inductor device 800. The input of wire L2 is connected to the terminal T3 of the dual-coil inductor device 800, and the output of wire L2 is connected to terminal T4 of the dual coil inductor device 800. In some embodiments, the AC system has a voltage L1-L2 of approximately 650 Vrms and a load current of approx. 100A.

Circuit breakers may be provided between the input terminals T2, T3 of the inductor device 800 and the power supply. The output terminals T1, T4 of the inductor devices 800 may be connected to a power distribution panel.

[00211] By surrounding the coil 830 with the coil 850 as described, the mutual inductance and inductive coupling between the coils 830, 850 is increased. This allows the combined coil device 839 to achieve a greater inductance value using individual coils 830, 850 with lower individual inductance values. As a result, the coils 830, 850 can be formed with fewer turns, and the size and weight of the combined coil 839 can be smaller for the same total inductance value compared to, for example, the inductor device 300. As discussed above with respect to the inductor device 600, the coefficient of inductance serves coupling between coils 830 and 850 to provide a greater effective total inductance on line L1 or line N than would be achieved with coils 830, 850 individually.

Embodiments of the combined dual inductor device (eg, the inductor device 800) can also provide a very high voltage isolation level of about 400 kV along each wire (L1, L2, or N) and about 30 kV between the two wires (eg, between L1 and N or between L1 and L2).

[00212] Although the arrangement of the inductor device 800 will also provide improved inductive coupling (for example, inductive coupling of about 0.6), it will typically not be as great as that provided by the inductor device 600 .

[00213] A dual-coil inductor device that includes a coil in coil design as described (eg, the dual-coil inductor device 800) can advantageously

DK 202300051 Y3 34 provide lower capacitance compared to the dual coil inductor device 600. A dual coil inductor device of this design also separates the wire L and neutral N conductors so that the risk of shorting between L and Neutral is reduced or eliminated.

[00214] While inductor devices as shown herein and in accordance with some embodiments are air-core (iron-free) coils, according to other embodiments each of the inductor devices may have a ferromagnetic core (e.g., an iron core, a laminated core, a ferrite core, an electrically operated iron core, a manganese-zinc ferrite, a molybdenum permalloy powder core, a nickel-zinc ferrite core, a Sendust core, a silicon steel core or a nanocrystalline core).

[00215] The foregoing is illustrative of the present invention and should not be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without substantially departing from the teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, and equivalents of the claims are to be included therein.

Claims (22)

DK 202300051 Y3 35 Requirements 1. Double coil inductor device comprising: a coil device comprising: a first metal foil; a first electrical insulator plate; another meta foil; a second electrical insulator plate; and first, second, third and fourth terminals; wherein: the first metal foil, the first electrical insulator plate, the second metal foil and the second electrical insulator plate are all spirally wound together to form a combined coil; the spirally wound first metal foil forms a first coil; the helically wound second metafoil forms a second coil; the first and second electrical insulator plates are interposed between the first and second metal foils such that the first and second metal foils are electrically isolated from each other by the first and second electrical insulator plates; the first terminal is electrically connected to the first metal foil at a first location, the second terminal is electrically connected to the first metal foil at a second location, and the first and second locations are spaced along the first metal foil; and the third terminal is electrically connected to the second metal foil at a third location, the fourth terminal is electrically connected to the second metal foil at a fourth location, and the third and fourth locations are spaced along the second metal foil. 2. The dual coil inductor device of claim 1, wherein: the first metal foil has opposite first and second ends; the second metal foil has opposite first and second ends; the first terminal is electrically connected to the first metal foil near the first end thereof: the second terminal is electrically connected to the first metal foil near the second end thereof; DK 202300051 Y3 36 the third terminal is electrically connected to the second metal foil near the first end thereof; and the fourth terminal is electrically connected to the second metal foil near the other end thereof. 3. The dual coil inductor device according to claim 1, wherein: the combined coil has a coil axis around which the first and second metal foils and the first and second electrical insulator plates are wound; and the first, second, third, and fourth terminals are first, second, third, and fourth terminal legs, respectively, extending outwardly from the combined coil to enable electrical connections between the dual coil device and electrical wiring. 4. The double coil inductor device according to claim 3, wherein each of the first, second, third and fourth terminal legs extends outwardly from an axial end of the combined coil. The dual-coil inductor device of claim 1, wherein the dual-coil inductor device includes: a first terminal bus bar that includes the first terminal and is attached to an inner winding of the first metal foil; a second terminal bus bar including the second terminal and attached to an outermost winding of the first metal foil; a third terminal bus bar that includes the third terminal and is attached to an inner winding of the second metal foil; and a fourth terminal rail that includes the fourth terminal and is attached to an outermost winding of the second metal foil. 6. The Hölge dual coil inductor device of claim 5, including: a first electrically insulating polymer tube surrounding a portion of the first terminal busbar; a second electrically insulating polymer tube surrounding a portion of the second terminal busbar; DK 202300051 Y3 37 a third electrically insulating polymer tube surrounding a portion of the third terminal busbar; and a fourth electrically insulating polymer tube surrounding a portion of the fourth terminal busbar. 7. The dual coil inductor assembly of claim 5, including a clamp plate and a fastener that mechanically secures one of the first and second terminal busbars in electrical contact with the first metal foil. 8. The double coil inductor device according to claim 1, wherein the first and second metal foils and the first and second electrical insulator plates are not bonded to each other across their widths, 9. The double-coil inductor device according to claim 1, wherein the first and second metal foils each have a foil thickness in the range from approx. 0.5 mm to 1 mm. 10. The double coil inductor device according to claim 1, wherein the first and second electrical insulator plates each have a thickness in the range of approx. 0.05 to 1 mm. 11. The dual coil inductor device of claim 1, wherein the first and second metal foils each have a foil thickness and a foil width, and a ratio of the foil width to the foil thickness of each of the first and second metal foils is in the range of about 170 to 500. 12. The dual coil inductor device of claim 1, wherein the combined coil has a | the essentially cylindrical outer profile. 13. The dual coil inductor device of claim 1 including an electrically insulating epoxy resin surrounding and passing | engagement with the combined coil. 14. The dual coil inductor assembly of claim 1, including a housing defining a closed chamber in which the combined coil is disposed within the chamber. 15. The dual coil inductor assembly of claim 14 including at least one mounting bracket supporting the housing and the combined coil. DK 202300051 Y3 38 16. The dual coil inductor device of claim 1, wherein the first coil includes a third metal foil spirally wound in side-to-side electrical contact with the first metal foil to form a multilayer conductor, 17. The dual coil inductor device of claim 16, wherein the first, second and third metal foils and the first and second electrical insulator plates are not bonded to each other across their width. 18. The dual coil inductor device of claim 16, wherein the second coil includes a fourth metal foil that is spirally wound in side-to-side electrical contact with the second metal foil to form a second multilayer seeder. 19, Dual coil inductor device comprising: an inner coil device including: an inner coil including: an inner metal foil; and an inner electrical insulator plate spirally interwoven with the inner metal foil; and first and second terminals; an outer coil device including: an outer coil including: an outer metal foil; and an outer electrical insulator plate spirally wound with the outer metal foil; and third and fourth terminals; where: the outer coil defines an outer coil air core; the inner coil is disposed within the outer coil air core such that the outer coil circumferentially surrounds the inner coil; the first terminal is electrically connected to the inner metal foil at a first location, the second terminal is electrically connected to the inner metal foil at a second location, and the first and second locations are spaced along the inner metal foil; and DK 202300051 Y3 39 the third terminal is electrically connected to the outer metal foil at a third location, the fourth terminal is electrically connected to the outer metal foil at a fourth location, and the third and fourth locations are spaced along the outer metal foil. The dual-coil inductor device of claim 19, wherein the dual-coil inductor device includes: a first terminal bus bar that includes the first terminal and is attached to an inner winding of the inner metal pleat; a second terminal busbar that includes the second terminal and is attached to an outermost winding of the inner metal foil; a third terminal bus bar that includes the third terminal and is attached to an inner winding of the outer metal foil; and a fourth terminal busbar that includes the fourth terminal and is attached to an outermost winding of the outer metal foil. 21, The dual-coil inductor device of claim 20, including a clamp plate and a fastener that mechanically secures one of the first and second terminal busbars in electrical contact with the inner metal foil, 22. The dual-coil inductor device of claim 19, wherein: the inner metafoil and the inner slectric insulator plate are not bonded to each other across their width; and the outer metal foil and the outer electrical insulator plate are not bonded to each other across their width.