EP4643445A1

EP4643445A1 - Forced flow cooling system for a superconducting machine

Info

Publication number: EP4643445A1
Application number: EP22941865.2A
Authority: EP
Inventors: James William Bray; Ernst Wolfgang Stautner
Original assignee: General Electric Renovables Espana SL
Current assignee: Ge Vernova Renovables Espana SL
Priority date: 2022-12-27
Filing date: 2022-12-27
Publication date: 2025-11-05
Also published as: CN120457621A; KR20250130337A; WO2024144764A1; JP2026503226A

Abstract

A superconducting machine includes a vacuum vessel, at least one superconducting coil arranged within the vacuum vessel, and a cooling system for cooling the at least one superconducting coil. The cooling system includes a torque transfer component secured to an interior wall of the vacuum vessel, the at least one superconducting coil being secured to the torque transfer component. The cooling system also includes a cryocooler exterior to the vacuum vessel, the cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling tubes for cryogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil. By operating the cooling system, the cryocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling tubes.

Description

FORCED FLOW COOLING SYSTEM FOR A SUPERCONDUCTING MACHINE

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] This invention was made with Government support under Contract No. DE-EE0008787 awarded by the Department of Energy' (DOE). The Government has certain rights in the invention.

FIELD

[0002] The present disclosure relates in general to superconducting generators, and more particularly to a cooling system for cooling a superconducting coil of the superconducting generator.

BACKGROUND

[0003] Wind turbines have received increased attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient. A wind turbine generally includes a rotor having a plurality' of rotor blades coupled to a rotatable hub. The rotor is rotatable coupled to a nacelle that is mounted atop a tower. The rotor blades convert wind energy into a rotational torque or force that drives the generator, rotationally coupled to the rotor.

[0004] Various electrical generators, such as superconducting generators, are being explored for use in wind turbine installations, particularly in direct-drive offshore installations. These machines use superconducting field windings and assemblies of conventional armature coils, cooling systems, and nonmagnetic teeth disposed between coils in the armature. In a particular design, the superconducting generator includes an armature winding assembly that, unlike conventional machines (e.g., conventional, non-superconducting generator) configurations, rotates within a superconducting field assembly, which includes a cryostat with superconducting field coils inside the cryostat.

[0005] Superconducting machines also typically include a cooling system for cooling the superconductors to cryogenic temperatures. Accordingly, the art is continuously seeking new and improved cooling systems for superconducting generators.

BRIEF DESCRIPTION

[0006] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0007] In one aspect, the present disclosure is directed to a superconducting machine. The superconducting machine includes a vacuum vessel, at least one superconducting coil arranged within the vacuum vessel, and a cooling system for cooling the at least one superconducting coil. The cooling system includes a torque transfer component secured to an interior wall of the vacuum vessel, the at least one superconducting coil being secured to the torque transfer component. The cooling system also includes a cryocooler exterior to the vacuum vessel, the cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling tubes for cryogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil. Once provided, the cry ocooler supplies a cry ogen to the at least one superconducting coil via the at least two cooling tubes.

[0008] In an embodiment, the forced-flow cooling system includes a reverse- Brayton cryocooling system.

[0009] In further embodiments, the torque transfer component is configured to secure the at least one superconducting coil in place. Further, the torque transfer component includes a torque tube.

[0010] In additional embodiments, the torque tube is secured to opposing sides of the vacuum vessel.

[0011] In other embodiments, the torque tube extends in a radial direction with respect to the superconducting machine.

[0012] In still further embodiments, the torque tube extends in an axial or circumferential direction with respect to the superconducting machine.

[0013] In other additional embodiments, the torque tube is a cantilevered component secured to the interior wall of the vacuum vessel. [0014] In further additional embodiments, the cooling system further includes a coil support structure, the at least one superconducting coil being arranged within the coil support structure.

[0015] In still other embodiments, the coil support structure is constructed of at least one of a metal or metal alloy or metallic additive material or a composite.

[0016] In yet other embodiments, a portion of the one of the at least two cooling tubes is arranged within the coil support structure. Further, the portion of the cooling tube arranged within the coil support structure is wrapped around, at least, a portion of the at least one superconducting coil.

[0017] In other embodiments, the coil support structure further includes a cover plate having an interior surface and an exterior surface, at least one of the at least two cooling tubes being secured to the interior surface of the cover plate.

[0018] In yet other embodiments, the torque transfer component further includes a torque disk and a torque tube holder, the torque disk secured to the coil support structure via at least one at least one fastener, the torque tube holder configured to secure the torque tube to at least one of the coil support structure or the torque disk. [0019] In still other embodiments, the superconducting machine further includes a spring placed around the at least one fastener.

[0020] In yet still other embodiments, the superconducting machine further includes a thermal layer, the thermal layer including a coating formed of one or more coating layers. Further, the one or more coating layers are placed on at least one of the torque transfer component, the coil support structure, or the at least two superconducting coils

[0021] In other embodiments, the at least two cooling tubes include a first cooling tube and a second cooling tube, the first and second cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil

[0022] In further embodiments, the superconducting machine further includes an armature arranged with the vacuum vessel, the armature configured to rotate within a magnetic field generated by the at least one superconducting coil. Further, the armature includes a winding, the winding including at least one of a hybrid Gramme winding or a fractional slot winding. [0023] In another aspect, the present disclosure is directed to a cooling system for cooling at least one superconducting coil of a superconducting machine. The cooling system includes a torque transfer component secured to an interior wall of a vacuum vessel of the superconducting machine, the at least one superconducting coil being secured to the torque transfer component. The cooling system also includes a cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling tubes for cryogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil. While operated, the cryocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling tubes.

[0024] In another aspect, the present disclosure is directed to a method of cooling at least one superconducting coil of a superconducting machine, the superconducting machine having a vacuum vessel with the at least one superconducting coil arranged therein. The method includes arranging a cooling system in thermal communication with the at least one superconducting coil. The step of arranging the cooling system in thermal communication with the at least one superconducting coil includes multiple steps. Specifically, arranging the cooling system includes arranging a cryocooler of the cooling system exterior to the vacuum vessel. Arranging the cooling system also includes thermally coupling at least two cooling tubes between the cry ocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system. Once the cooling system is arranged, the method also includes operating the cooling system to supply a cryogen to the at least one superconducting coil via the at least two cooling tubes.

[0025] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary' skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0027] FIG. 1 illustrates a perspective view of one embodiment of a wind turbine having a generator according to the present disclosure;

[0028] FIG. 2 illustrates a perspective, internal view of one embodiment of a nacelle of a wind turbine having a superconducting generator according to the present disclosure;

[0029] FIG. 3 illustrates a side view of a superconducting generator in accordance with aspects of the present invention;

[0030] FIG. 4 illustrates a simplified, schematic diagram of a superconducting generator according to conventional construction, particularly illustrating a cooling system arranged with a thermal shield of the generator;

[0031] FIG. 5 illustrates a simplified, schematic diagram of a forced-flow cooling system according to the present disclosure.

[0032] FIG. 6 illustrates a simplified, schematic diagram of the forced-flow' cooling system of FIG. 5 arranged with a superconducting generator according to the present disclosure;

[0033] FIG. 7 illustrates a side view of a superconducting generator, particularly illustrating an arrangement of a torque transfer component, a coil support structure, and cooling tubes according to the present disclosure;

[0034] FIG. 8 illustrates an interior, radial view of a coil support structure, particularly illustrating an arrangement of cooling tubes according to the present disclosure;

[0035] FIG. 9 illustrates an interior, radial view of a coil support structure, particularly illustrating another arrangement of cooling tubes according to the present disclosure;

[0036] FIG 10. illustrates a radially outward view of a coil support structure, particularly illustrating another arrangement of cooling tubes according to the present disclosure;

[0037] FIG. 11 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of a torque transfer component, a coil support structure, and cooling tubes according to the present disclosure;

[0038] FIGS. 12A-12B illustrate various embodiments of fasteners configured to assemble a torque transfer component and secure the torque transfer component to a coil support structure according to the present disclosure;

[0039] FIG. 13 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of a torque transfer component, a coil support structure, and cooling tubes according to the present disclosure;

[0040] FIG. 14 illustrates a detailed view of a torque transfer component disk according to the present disclosure;

[0041] FIG. 15 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of a torque transfer component, a coil support structure, and cooling tubes according to the present disclosure;

[0042] FIG. 16 provides a flow diagram illustrating a method of cooling a superconducting generator according to the present disclosure.

[0043] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

DETAILED DESCRIPTION

[0044] Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. [0045] The terms “coupled,’’ “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein.

[0046] A superconducting machine is a type of electric machine, such as a superconducting generator, that relies on the use of the properties exhibited by superconducting materials. Such a generator will also have a low reactance if produced in an “air-core” form. Specifically, an “air-core” form is provided when most of the magnetic material, such as iron, is removed from the armature and field due to the high fields produced by the superconductor. Without the removal of the magnetic material, the high fields produced by the superconductor may saturate the magnetic material. Thus, the removal of the magnetic material lowers the generator reactance.

[0047] In addition, a superconducting material exhibits a different set of physical and electrical properties when they are cooled below a certain temperature which is referred to as a “critical temperature.” In the field of superconducting electrical machines, a superconducting material is chosen to form superconducting coils for the superconducting electrical machine because the properties of the superconducting material and coils allow for the conductance of current without energy loss once the coils are brought below the critical temperature for the respective material. This property enables superconducting machines to operate at a higher efficiency and with higher magnetic fields than would otherwise be possible without the use of superconducting materials. However, cooling systems are required to ensure that the superconducting coils are maintained below the critical temperature.

[0048] Conventional cooling systems for superconducting machines or generators operate through a passive cooling system such as through pool boiling or thermosiphons. Pool boiling is a form of cooling where the superconducting coils are submerged in a bath of coolant that carries thermal energy' away from the superconducting coils as they are being operated. The thermosiphon operates through a mechanism where gravity’ drives the cooler, heavier coolant at the top of the generator toward the bottom. The heating that occurs in the fluid as it passes and cools the superconductor causes the hotter, lighter fluid when it reaches the bottom of the generator to rise again to the top, where the cooler re-cools it to repeat the cycle. For cooling to liquid helium operating temperatures (4.2 K), Gifford-McMahon cycle coolers are the standard for cooling the fluid in smaller applications such as MRI (magnetic resonance imaging).

[0049] For example, referring now to the drawings, FIGS. 1-4 illustrate a conventional passive cooling system for a generator housed within a wind turbine. For example, in FIG. 1, a perspective view of a wind turbine having a generator is illustrated. In FIG. 2, an internal view of a nacelle of a wind turbine having a superconducting generator is illustrated. In FIG. 3, a side view of a conventional superconducting generator is illustrated. In FIG. 4, a simplified, schematic diagram of a superconducting generator according to conventional construction is shown, particularly illustrating a cooling system arranged with a thermal shield of the generator.

[0050] More specifically, referring now to FIG. 1, a perspective view of an embodiment of a wind turbine 10 is illustrated. The wind turbine 10 includes a tower 12 extending from a support surface 14, a nacelle 16 mounted on the tower 12, and a rotor 18 coupled to the nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outwardly from the hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in an alternative embodiment, the rotor 18 may include more or less than three rotor blades 22. Each rotor blade 22 may be spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub 20 may be rotatably coupled to an electric generator (not show n) positioned within the nacelle 16 to permit electrical energy to be produced.

[0051] Referring now to FIG. 2, a perspective, internal view of an embodiment of the nacelle 16 having a superconducting generator 23 housed therein according to the present disclosure is illustrated. Further, as shown, a support tube 41 is connected directly to the hub 20 and supports an armature winding assembly 24. Thus, the armature winding assembly 24 is considered as the rotating component of the generator 23 with a rotating first electromagnetic component configuration that rotate around a stationary field assembly 26 having a second electromagnetic component configuration, such as a superconducting field winding assembly 26.

[0052] The stationary' field assembly 26 includes superconducting coils 52, which may be a group of wires formed in a racetrack shape. Thus, in certain embodiments, the superconducting coils 52 are constrained to retain the racetrack shape. Moreover, as shown, each superconducting coil 52 is supported in a recess/passage 50 in a casing 42 that may be conduction cooled by cry ogenic cooling tubes filled with a cry ogen (e.g., helium, hydrogen, or neon) for purposes of removing heat from the superconducting coils. As such, the casing 42 may be supported in a cryostat housing 36, also referred to herein as the vacuum vessel, which is fixed to a base tube 44.

[0053] Still referring to FIG. 2, the superconducting coils 52 may be arranged side by side in an annular array extending around the casing 42. For example, in an embodiment, thirty-six coils may form an annular array of field windings that serve as the stator field winding for the generator 23. Furthermore, in an embodiment, the superconducting coils 52 may be each formed of (NbTi or other superconducting materials) wi re wrapped in a helical path around a racetrack form that may include cooling conduits for the cry ogen. The stationary field assembly 26 includes superconducting coil magnets 54 created by passing current through the superconducting field coils 52, which are enclosed in the casing 42 and receive cryogen through cooling recesses/passages 50.

[0054] In additional embodiments, cryogen re-condensers 38, 40 may be housed in the field coil assembly 26. provided that the cryogen cooling liquid in the recondensers 38. 40 is at least partially elevated above the superconducting field windings to provide for gravity feed of the cryogen to the windings. Alternatively, the re-condensers 38, 40 may be mounted on top of the field coil assembly.

[0055] Referring now' to FIG. 3, a cross-section of an embodiment of the direct drive superconducting generator 23 with the annular rotating armature winding assembly 24 (“armature 24”) radially inward of the stationary field assembly 26 is illustrated. It should be understood that the present disclosure described herein can also function with the armature winding assembly 24 positioned radially outward of the stationary field assembly 26 as well. In particular, as shown, the armature 24 is essentially an inner annular ring configuration (FIG. 3) that rotates within the stationary field assembly 26. The armature 24 includes the conducting coils 52, e g., coils or bars, arranged longitudinally along the length of the armature 24 and on an inside cylindrical surface of the armature 24. The conducting coils 52 may be connected at their opposite ends to one another by conductive end turns 28. The end turns 28 between the longitudinal conducting coils 52 are dependent on their number and arrangement, and the phases of electricity to be generated in the conducting coils 52. The outside cylindrical surface of the armature windings is separated by a narrow' air gap, e.g., about 10-25 mm, from the inner surface of the stationary field assembly 26.

[0056] Referring generally to FIG. 3, the armature 24 includes a cylindrical yoke or body 30 (referred to as ‘’body” herein) that supports the conducting coils 52. In particular, the conducting coils 52 are contained in slots defined between adjacent teeth that extend radially from the body 30. The body 30 and teeth may be a layered, laminated construction. The inner surface of the body 30 is fixed to a cylindrical housing 32 that rotates with the armature 24. Moreover, as shown, the stationary field winding assembly 26 may be supported by a field winding support disc 34. Further, the field winding support disc 34 is attached to an end of the cry ostat housing 36 containing the superconducting coils 52 (FIG. 2) of the field winding assembly 26. The housing 36 and its cooling components form a cryostat that cools the superconducting coils of the field winding.

[0057] The cryostat housing 36 insulates the superconducting coils 52 so that they may be cooled to near absolute zero temperature, e.g.. to about 20 Kelvin (K), and more preferably about 10 K. and still more preferably to about 4K. To cool the windings, the cry ostat housing 36 may include one or more insulated conduits 46 to receive liquid helium (He) or other similar cry ogenic liquid such as liquid neon (Ne) or liquid hy drogen (H) (referred to as cry ogen). A conventional two-stage recondenser 38 mounted in an upper region of the field coil assembly, on top of the field coil assembly, or on top of the tower 12, and above the field windings to provide cryogen, e.g., liquid He, using a gravity feed. The second re-condenser 40 possibly provides a second cooling liquid, e.g., liquid nitrogen or neon, to an inner thermal shield of the cryostat housing 36 via conduit 48.

[0058] Referring now to FIG. 4, various components of a schematic diagram of a simplified cooling system 102 for a superconducting generator 100 according to conventional construction are illustrated. More specifically, as shown, the superconducting generator 100 generally includes a cooling system 102 arranged with a thermal shield 104 of the generator 100, a vacuum vessel 106. a cold mass 108. and a cryocooler 110. In such embodiments, for example, the cold mass 108 may be a stationary' component, such as the field winding assembly 26 within which the armature winding assembly 24 rotates. It should be understood that the annulus for the armature winding assembly is show n in FIG. 3, but is omitted from FIGS. 4-9 in an effort to simplify the figures and more clearly explain the details of the present disclosure. Furthermore, as an example, the vacuum vessel 106 may be a nonrotatable component supporting a field winding assembly, such as the stationary field assembly 26.

[0059] Thus, in such embodiments, the rotatable component may be oriented to rotate relative to the nonrotatable component during the operation of the generator 100 as shown in FIG. 3. In such conventional configurations, the thermal shield 104 intercepts and/or blocks radiation (as indicated by arrows 114) from the vacuum vessel 106. Further, as shown, heat is removed via a thermal bus/busbar 112 to the cryocooler 110, thereby blocking most radiation heat from the cold mass 108. Moreover, as shown, the thermal bus/busbar(s) 112 of such configurations are attached to the top of the thermal shield 104 for connection to the cryocooler 110. The thermal shield 104 also intercepts heat conducted in through structural components, such as those used to hold the stationary field assembly 26 in place. [0060] However, each of these types of passive cooling systems, discussed in reference to FIGS. 1-4 (e.g., thermosiphon coolers or pool boiling), have a limit on the amount of cooling pow er that can be provided as a consequence of their reliance on passive means of cooling. Further, each of these types of passive cooling systems require the use of a large number of parts that are difficult to manufacture and assemble, and as a consequence, costly.

[00 1] Thus, the present disclosure is generally directed to a superconducting machine utilizing a forced-flow cooling system, in contrast to the passive cooling means, to cool the superconducting coils arranged therein. Further, the superconducting machine may include an architecture that takes advantage of the benefits provided by the use of forced-flow cooling. For example, specific and more general orientations of cooling tubes may be provided w ith the superconducting coils for cooling, not dependent on gravity direction. Means and methods of addressing torsional forces generated by the superconducting coils may be provided. Specifically, a torque transfer component may be provided to address movements generated by the opposing magnetic fields within the superconducting machine or the initial shrinkage and expansion of the superconducting coils w hen operated. The cooling system may also enable different types of electrical components to be used with the superconducting machine that were not possible with passively cooled superconducting machines. For example, an armature may be provided with the superconducting machine that has windings not previously implemented.

[0062] By providing a superconducting machine with any one of these aforementioned features, the overall efficiency of the superconducting machines may be improved while also lowering the overall cost of manufacturing and operating such machines.

[0063] Furthermore, by utilizing a forced-flow cooling system, various advantages may be provided. For example, the cooling power and removal of heat may be made variable and can be optimized for the superconducting machine being operated. Further, the flow of cooling power can be particularly directed to desired locations while minimizing flow maldistribution. Moreover, the flow of cooling power can be maintained in a continuous manner without any discontinuity in the heat transfer. Further, a forced-flow cooling system does not require any particular requirements of the internal environment within the superconducting machine such as a pressure level to utilize the cooling system.

[0064] The superconducting machine may be used with the features discussed in reference to FIGS. 1-4 while providing the advantages of utilizing forced-flow cooling systems. For example, the present disclosure is directed to a superconducting machine that, although not limited to such use, is particularly well-suited for use in a wind turbine 10 (FIG. 1). Further, FIG. 1 depicts an “on-shore” (land-based) wind turbine 10 installation; how ever, it should be appreciated that the present invention is not limited to onshore wind turbines and is just as applicable to “off-shore" (waterbased) wind turbine installations, with either fixed or floating foundations, where the generally larger generators may benefit more from forced-flow cooling.

[0065] Referring particularly to FIG. 5, a simplified, schematic diagram of a forced-flow- cooling system 200 according to the present disclosure is illustrated. More specifically, as shown, the forced-flow cooling system 200 as depicted demonstrates the means in w hich thermal energy may be transferred in reference to a superconducting machine as presently disclosed. Specifically, a reverse-Brayton cryocooling system (also known as the gas refrigeration or Bell Coleman or Joule cycle and closely related to Claude or Linde cycle) is depicted. However, other forced-flow cooling systems may also be included.

[0066] Moreover, in an embodiment, as shown, the forced-flow cooling system 200 may include a cold reservoir 202, a hot reservoir 204, a first heat exchanger 206, a second heat exchanger 208, a turbine-compressor 210, and a thermal pathway 212. In general, the forced-flow cooling system 200 moves thermal energy Q away from the cold reservoir 202 and to the hot reservoir 204. In particular, the forced-flow cooling system 200 moves thermal energy Q from the cold reservoir 202 into the first heat exchanger 206 and out through the second heat exchanger 208 into the hot reservoir 204. This transfer of thermal energy Q is achieved through the use of the turbine-compressor 210 and the thermal pathway 212. Moreover, in an embodiment, the turbine-compressor 210 exerts work W into the cooling system 200 sufficient to drive the thermal energy Q from the first heat exchanger 206 to the second heat exchanger 208. The thermal pathway 212 allows the thermal energy Q to transfer from the first heat exchanger 206 to the second heat exchanger 208. Such a process will be described in more detail below in reference to FIGS. 6-16.

[0067] Referring now to FIG. 6, a simplified, schematic diagram of an embodiment of a forced-flow cooling system 306 arranged with a superconducting generator is illustrated. As shown, the superconducting generator 300 includes a vacuum vessel 302, at least one superconducting coil 304, and a cooling system 306. Specifically, the superconducting coil(s) 304 is arranged within the vacuum vessel 302. Further, the cooling system 306 cools the superconducting coil(s) 304.

[0068] The vacuum vessel 302 may be similar and include the features of the vacuum vessel 106 discussed in reference to FIG. 4. For example, the vacuum vessel 302 may house each of the electrical components of the superconducting generator 300, such as the superconducting coil(s) 304. The vacuum vessel 302 may also act as a thermal barrier for the superconducting coil(s) 304. In addition, the superconducting coil(s) 304 may be similar and include the same features as the superconducting coils 52 or the field assembly 26 such as the shape, orientation, or the materials from which the coils 52 are formed.

[0069] Still referring to FIG. 6, the cooling system 306 may further include a cryocooler 308 and at least two cooling tubes 310 for cryogen supply and return. The cryocooler 308 may be mounted on or around the exterior of the vacuum vessel 302. As aforementioned, the cryocooler 308 is a forced-flow cooling system, such as a reverse-Brayton cryocooling system. The cooling tube(s) 310 may be thermally coupled between the cryocooler 308 and the superconducting coil(s) 304. Further, the cry ©cooler 308 may supply a coolant or a cryogen or a cryogenic cooling fluid to the superconducting coil(s) 304 via the cooling tube(s) 310.

100701 Furthermore, as shown, the superconducting generator 300 may also include various other components. For example, as shown in FIG. 6, the superconducting generator 300 may also include a torque transfer component 312, a thermal layer 314, and an armature 316. The torque transfer component 312 may be provided to secure the superconducting coil(s) 304 in place while the superconducting coil(s) 304 are being operated. The thermal layer 314 may provide further thermal insulation to the superconducting coil(s) 304, if needed. A further advantage of forced cooling with its higher cooling power is that the thermal layer 314 need not be separately cooled, as is the case with all Gifford-McMahon and pool-boiling systems in order to reach 4 K cold-mass operation. The armature 316 may provide a magnetic field that acts in opposition to the magnetic field provided by the superconducting coil(s) 304. The armature 316 may be arranged with the vacuum vessel 302. In addition, the armature 316 may be configured to rotate within a magnetic field generated by the superconducting coil(s) 304. The armature 316 may include the features of the armature 24 such as armature windings. However, the armature 316 may also include features distinct from armature 24. For example, the armature 316 may include at least one of a hybrid Gramme winding or a factional slot winding. These types of winding/ armature topologies were previously not possible due to an insufficient amount of cooling power being provided by passive cooling systems for superconducting generators due to eddy current heating of the field by the armature windings. How ever, the cooling system of the present disclosure provides a sufficient cooling power such that a hybrid Gramme winding or a factional slot winding may now be achievable.

[0071] Each of the components of the superconducting generator 300 will be discussed in greater detail below⁷ in reference to FIGS. 7-16.

[0072] Referring now⁷ to FIG. 7, a side view of a superconducting generator 300 is show n, particularly illustrating an arrangement of a torque transfer component 312, a coil support structure 320, and cooling tubes 310. As shown, the torque transfer component 312 is arranged within the vacuum vessel 302. Particularly, the torque transfer component 312 may be secured to an interior wall of the vacuum vessel 302 and secured to the superconducting coil(s) 304, thereby securing the superconducting coil(s) 304 in place.

[00731 In certain embodiments, as shown, the torque transfer component 312 may include a torque tube 318. Although the torque tube 318 is described as a tube, the torque tube 318 may take a variety of other non-cylindrical or non-tubular shapes. As shown particularly in FIG. 7, for example, the torque tube 318 may be secured to opposing sides of the vacuum vessel 302. Such an orientation allows for the torque tube 318 to equal distribute the mechanical forces that the torque tube 318 endures (such as the forces resulting from the expansion of the superconducting coil(s) 304 or the forces resulting from the magnetic field generated by the superconducting coil(s) 304) to both sides of the vacuum vessel 302.

[0074] In addition, as shown, the torque tube 318 may extend in specific directions. For example, the torque tube 318 may extend in a radial direction with respect to a generator axis 319 of the superconducting generator 300. Alternatively, the torque tube 318 may extend in an axial direction with respect to the generator axis 319 of the superconducting generator 300. Specific portions of the torque tube 318 may also extend in various manners. For example, a portion of the torque tube 318 may extend in a radial direction while another portion extends in an axial direction. Further, as shown, the cooling tube(s) 310 may also be provided within the torque tube 318. By doing this, the torque transfer component 312 may be cooled along with the superconducting coil(s) 304. Specific embodiments of orientation of the torque transfer component 312 and the torque tube 318 will be discussed in greater detail with reference to FIGS. 11-16.

[0075] Referring still to FIG. 7, the superconducting generator 300 may also include a coil support structure 320. As shown, the superconducting coil(s) 304 may be arranged within the coil support structure 320. The coil support structure 320 may be constructed of a variety of materials. For example, the coil structure 320 may be constructed from at least one of a metal or metal alloy or a composite. In an exemplary⁷ embodiment, the coil support structure 320 may be constructed from a stainless steel. By constructing the coil support structure 320 using a stainless steel, greater strength may be provided to house the superconducting coil(s) 304.

[0076] Further, the cooling tube(s) 310 may be provided within the coil support structure 320, thereby providing direct cooling to the superconducting coil(s) 304. For example, a portion of the cooling tube(s) 310 may be arranged within the coil support structure 320, and the portion of the cooling tube(s) 310 arranged within the coil support structure 320 may be wrapped around, at least, a portion of the superconducting coil(s) 304. Specific embodiments of placement of the cooling tube(s) 310 with respect to the coil support structure 320 will be discussed in greater detail with reference to FIGS. 8-10.

[0077] As aforementioned with reference to FIG. 6, the superconducting generator 300 may also include a thermal layer 314. In contrast to conventional superconducting generators, which utilize a thermal shield formed from a solid sheet of material such as steel, the thermal layer 314 may take the form of a coating formed of one or more coating layers. For example, the coating layers may be a multi-layered insulation (MLI) formed from multiple layers of thin sheets of material. In certain embodiments, the coating layers may also be a coating sprayed or applied as needed. The materials used to make up the thermal layer 314 may be at least one of a metallic foil segment. Once selected, the coating layer(s) are placed on at least one of the torque transfer component 312 or the coil support structure 320. By using the thermal layer 314, the heat burden on the superconducting coils is reduced. Also, the overall weight of the superconducting generator 300 may be reduced which is especially beneficial when placing the superconducting generator 300 at elevated locations such as within a wind turbine. This reduction in weight is achieved through the replacement of the conventional thermal shield with the lighter thermal layer 314. Such a replacement is made possible by the increased cooling power provided by using the forced-flow cooling system 200 within the superconducting generator 300.

[0078] In further embodiments, as shown in FIG. 7. the torque transfer component 312 may also include a torque disk 322 and a torque tube holder 324. As shown, the torque disk 322 may be secured to the coil support structure 320 via at least one fastener 326. Further, the torque tube holder 324 may be configured to secure the torque tube 318 to the coil support structure 320 (FIG. 7) and/or the torque disk 322. The torque disk 322 and the torque tube holder 324 will be discussed in greater detail with reference to FIGS. 12A-B and FIGS. 14-15.

[0079] In addition, each of the components of the torque transfer component 312 may be made out of specific materials. For example, the torque tubes 318, the torque disk 322, and the torque tube holder 324 may be formed from a metal or a metal alloy such as Inconel® steel.

[0080] Referring now to FIGS. 8-10, various orientations and placements of cooling tubes are depicted. As shown in FIG. 8, an interior, top view of an embodiment of the coil support structure 320 is illustrated. In particular, as shown, the cooling tube(s) 310 includes a first cooling tube 328 and a second cooling tube 330. Like the cooling tube(s) 310, the first and second cooling tubes 328, 330 are thermally coupled between the cryocooler 308 and the superconducting coil(s) 304. Further, the first cooling tube 328 may be placed on one side of the superconducting coil(s) 304. and the second cooling tube 330 may be placed on another, opposite side of the superconducting coil(s) 304. Specifically, in an exemplary embodiment, the first and second cooling tubes 328, 330 are depicted as placed along the shorter, curved portions of the racetrack shape of the superconducting coil(s) 304. However, the first and second cooling tubes 328, 330 may also be placed on the long, straight portion of the racetrack shape of the superconducting coil(s) 304. The first and second cooling tubes 328, 330 may be connected to the same cryocooler 308. Alternatively, the first and second cooling tubes 328, 330 may be connected two separate cryocoolers 308.

[0081] Referring particularly to FIG. 9, an interior, top view of another embodiment of the coil support structure 320 is illustrated, particularly showing another arrangement of the cooling tube(s) 310. In particular, as shown, the cooling tube(s) 310 is placed along both longer, straight portions and one of the shorter, curved portions of the racetrack shape of the superconducting coil(s) 304. Providing the cooling tube(s) 310 along a greater length of the superconducting coil(s) 304 mayenable for a greater amount of cooling power to be delivered to the superconducting coil(s) 304.

[0082] Referring now particularly to FIG. 10, an interior view of yet another embodiment of the coil support structure 320 is illustrated, particularly showing still another arrangement of cooling tube(s) 310. As shown, the coil support structure 320 may include a cover plate 332 having an interior surface 331 and an exterior surface 333. If the cover plate 332 is provided, the cooling tube(s) 310 may be secured to the interior surface 331 of the cover plate 332. Further, the cooling tube(s) 310 may be secured in a variety of manners. For example, the cooling tube(s) 310 may be secured in a similar manner to the embodiment depicted in FIGS. 8-9. Alternatively, the cooling tube(s) 310 may be secured in a zig-zag manner thereby covering a greater extent of the coil support structure 320 and providing a greater amount of cooling power to the superconducting coil(s) 304.

[0083] Referring particularly to FIG. 11, a side view of another embodiment of the superconducting generator 300 is illustrated, particularly showing another arrangement of a torque transfer component 312, a coil support structure 320, and cooling tubes 310. As shown, the torque tube 318 may be a cantilevered component secured to the interior wall of the vacuum vessel 302. By cantilevering the torque tube 318. the torque tube 318 may be able to compensate for mechanical forces undertaken by the torque transfer component 312. For example, if the superconducting coil(s) 304 undergoes shrinkage while being operated, cantilevering of the torque tube 318 may allow for flexing of the torque tube 318 to compensate for the movement resulting from the shrinkage.

[0084] Referring particularly to FIGS. 12A-12B, various embodiments of fasteners configured to assemble the torque transfer component 312 and secure the torque transfer component 312 to the coil support structure 320 are illustrated. As shown in FIG. 12A, the fastener(s) 326 may be utilized to secure the torque tube 318 or the coil support structure 320. The torque tube 318 may be secured to a variety of components within the superconducting generator 300. For example, the fastener(s) 326 may secure the torque tube 318 to the torque disk 322 as shown in FIG. 12B. The fastener(s) 326 may also secure the torque tube 318 to the coil support structure 320 (FIGS. 7. 11. and 14-16). The fastener(s) 326 may also secure the torque tube 318 to the torque tube holder 324 (FIG. 11). Further, as shown in FIG. 12B, a spring 334 may be placed around the fastener(s) 326. By providing a spring 334, the torque transfer component 312 may be able to better account for mechanical forces. For example, if compression occurs along the fastener(s) 326 as a result of operating the superconducting generator 300, the spring 334 may be able to accommodate the compression without resulting in deformation of the fastener(s) 326.

[0085] Referring now to FIG. 13, a side view of another embodiment of the superconducting generator 300 is illustrated, particularly depicting another arrangement of a torque transfer component 312, a coil support structure 320, and cooling tubes 310. In particular, the torque tube holder 324 may be placed at a variety of locations. For example, the torque tube holder 324 may be placed toward the center of the coil support structure 320.

[0086] Further, FIG. 13 depicts the thermal pathway 336 in which thermal energy transfers through the superconducting generator 300. As shown, the thermal pathway 336 originates at the superconducting coil(s) 304 and travels through the coil support structure 320 and the torque tube holder 324 to the torque tube 318. The thermal energy⁷ then travels outward along the torque tube 318 arriving at the vacuum vessel 302. By placing the cooling tube(s) 310 along this pathway (e.g. within the torque tube 318 or within the coil support structure 320). the overall efficiency of cooling of the superconducting generator 300 may be increased.

[0087] Referring now to FIG. 14, a detailed view of an embodiment of a torque transfer component disk 322 is illustrated. As shown, the torque disk 322 may include multiple fasteners 326 to secure the torque disk 322 to either the torque tube 318, the coil support structure 320, or the torque tube holder 324. Placement of the cooling tube(s) 310 within the torque disk 322 may increase the overall cooling efficiency of the superconducting generator 300.

[0088] Referring now to FIG. 15, a side view of an embodiment of the superconducting generator 300 is illustrated, particularly depicting another arrangement of a torque transfer component 312, a coil support structure 320, and cooling tubes 310. As show n, the cooling tube(s) 310 may be placed throughout the superconducting generator 300. For example, the cooling tube(s) 310 may be placed along multiple portions of the torque tubes 318.

[0089] Further, different types of cooling may be used. For example, if multiple cooling tubes 310 are used, the cooling tubes 310 may be different types.

Particularly , at least one of the cooling tubes 310 may be connected to the forced-flow cooling system 200, while another of the cooling tubes 310 may be connected to a different cooling means. For example, the cooling means may be a gas tank 338 which provides passive cooling in addition to the active cooling provide by the forced-flow cooling system 200.

[0090] Referring generally to FIG. 16, a flow diagram of an embodiment of a method of cooling a superconducting generator is illustrated. Although FIG. 16 depicts steps performed in a particular order for purposes of illustration and discussion, the methods described herein are not limited to any particular order or arrangement. One skilled in the art, using the disclosures provided herein, will appreciate that various steps of the methods can be omitted, rearranged, combined and/or adapted in various ways.

[0091] As shown at (402), the method 400 includes arranging a cooling system in thermal communication with the at least one superconducting coil. Specifically, arranging the cooling system in thermal communication with the at least one superconducting coil may include multiple steps. For example, as shown at (404), the method 400 includes arranging a cryocooler of the cooling system exterior to the vacuum vessel, and as shown at (406), the method 400 includes thermally coupling at least two cooling tubes between the cryocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system. Once the cooling system is provided, the method 400, as shown at (408), may also include operating the cooling system to supply a cryogen or a cryogenic cooling fluid to the at least one superconducting coil via the at least two cooling tubes.

[0092] The skilled artisan will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described, as well as other known equivalents for each such methods and feature, can be mixed and matched by one of ordinary skill in this art to construct additional systems and techniques in accordance with principles of this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0093] Further aspects of the invention are provided by the subject matter of the following clauses:

Clause 1. A superconducting machine, comprising: a vacuum vessel; at least one superconducting coil arranged within the vacuum vessel; and a cooling system for cooling the at least one superconducting coil, the cooling system comprising: a torque transfer component secured to an interior wall of the vacuum vessel, the at least one superconducting coil being secured to the torque transfer component; a cryocooler exterior to the vacuum vessel, the cryocooler comprising a forced-flow cooling system, and at least two cooling tubes for cryogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling tubes.

Clause 2. The superconducting machine of clause 1, wherein the forced- flow cooling system comprises a reverse-Brayton cryocooling system.

Clause 3. The superconducting machine of any of clauses 1-2, wherein the torque transfer component is configured to secure the at least one superconducting coil in place, wherein the torque transfer component comprises a torque tube.

Clause 4. The superconducting machine of clause 3, wherein the torque tube is secured to opposing sides of the vacuum vessel.

Clause 5. The superconducting machine of any of clauses 3-4, wherein the torque tube extends in a radial direction with respect to the superconducting machine.

Clause 6. The superconducting machine of any of clauses 3-5, wherein the torque tube extends in an axial or circumferential direction with respect to the superconducting machine.

Clause 7. The superconducting machine of any of clauses 3 or 5-6 , wherein the torque tube is a cantilevered component secured to the interior wall of the vacuum vessel.

Clause 8. The superconducting machine of any of clauses 3-7, wherein the cooling system further compnses a coil support structure, the at least one superconducting coil being arranged within the coil support structure.

Clause 9. The superconducting machine of clause 8, wherein the coil support structure is constructed of at least one of a metal or metal alloy or metallic additive material or a composite.

Clause 10. The superconducting machine of any of clauses 8-9, wherein a portion of the one of the at least two cooling tubes is arranged within the coil support structure, and wherein the portion of the cooling tube arranged within the coil support structure is wrapped around, at least, a portion of the at least one superconducting coil.

Clause 11. The superconducting machine of any of clauses 8-10, wherein the coil support structure further comprises a cover plate having an interior surface and an exterior surface, at least one of the at least two cooling tubes being secured to the interior surface of the cover plate.

Clause 12. The superconducting machine of any of clauses 8-11, wherein the torque transfer component further comprises a torque disk and a torque tube holder, the torque disk secured to the coil support structure via at least one at least one fastener, the torque tube holder configured to secure the torque tube to at least one of the coil support structure or the torque disk.

Clause 13. The superconducting machine of clause 12, further comprising a spring placed around the at least one fastener.

Clause 14. The superconducting machine of any of clauses 8-13, further comprising a thermal layer, the thermal layer comprising a coating formed of one or more coating layers, wherein the one or more coating layers are placed on at least one of the torque transfer component, the coil support structure, or the at least two superconducting coils.

Clause 15. The superconducting machine of any of the preceding clauses, wherein the at least two cooling tubes comprises a first cooling tube and a second cooling tube, the first and second cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil. Clause 16. The superconducting machine of any of the preceding clauses, further comprising an armature arranged with the vacuum vessel, the armature configured to rotate within a magnetic field generated by the at least one superconducting coil, wherein the armature comprises a winding, the winding comprising at least one of a hybrid Gramme winding or a fractional slot winding.

Clause 17. A cooling system for cooling at least one superconducting coil of a superconducting machine, the cooling system comprising: a torque transfer component secured to an interior wall of a vacuum vessel of the superconducting machine, the at least one superconducting coil being secured to the torque transfer component; a cryocooler comprising a forced-flow cooling system; and at least two cooling tubes for cryogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling tubes.

Clause 18. The cooling system of clause 17, wherein the forced-flow cooling system comprises a reverse-Brayton cryocool ing system.

Clause 19. The cooling system any of clauses 17-18, wherein the at least two cooling tubes comprises a first cooling tube and a second cooling tube, the first and second cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil.

Clause 20. A method of cooling at least one superconducting coil of a superconducting machine, the superconducting machine having a vacuum vessel with the at least one superconducting coil arranged therein, the method comprising: arranging a cooling system in thermal communication with the at least one superconducting coil, wherein arranging the cooling system in thermal communication with the at least one superconducting coil comprises: arranging a cryocooler of the cooling system exterior to the vacuum vessel; and thermally coupling at least two cooling tubes between the cryocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system; and operating the cooling system to supply a cryogen to the at least one superconducting coil via the at least two cooling tubes.

[0094] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

WHAT IS CLAIMED IS:

1. A superconducting machine, comprising: a vacuum vessel; at least one superconducting coil arranged within the vacuum vessel; and a cooling system for cooling the at least one superconducting coil, the cooling system comprising: a torque transfer component secured to an interior wall of the vacuum vessel, the at least one superconducting coil being secured to the torque transfer component; a cryocooler exterior to the vacuum vessel, the cryocooler comprising a forced-flow cooling system, and at least two cooling tubes for cryogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cry ocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling tubes.

2. The superconducting machine of claim 1 , wherein the forced-flowcooling system comprises a reverse-Brayton cryocooling system.

3. The superconducting machine of claim 1, wherein the torque transfer component is configured to secure the at least one superconducting coil in place, wherein the torque transfer component comprises a torque tube.

4. The superconducting machine of claim 3, wherein the torque tube is secured to opposing sides of the vacuum vessel.

5. The superconducting machine of claim 3, w herein the torque tube extends in a radial direction with respect to the superconducting machine.

6. The superconducting machine of claim 3, wherein the torque tube extends in an axial or circumferential direction with respect to the superconducting machine.

7. The superconducting machine of claim 3, wherein the torque tube is a cantilevered component secured to the interior wall of the vacuum vessel.

8. The superconducting machine of claim 3, wherein the cooling system further comprises a coil support structure, the at least one superconducting coil being arranged within the coil support structure.

9. The superconducting machine of claim 8, wherein the coil support structure is constructed of at least one of a metal or metal alloy or metallic additive material or a composite.

10. The superconducting machine of claim 8, wherein a portion of the one of the at least two cooling tubes is arranged within the coil support structure, and wherein the portion of the cooling tube arranged within the coil support structure is wrapped around, at least, a portion of the at least one superconducting coil.

11. The superconducting machine of claim 8, wherein the coil support structure further comprises a cover plate having an interior surface and an exterior surface, at least one of the at least two cooling tubes being secured to the interior surface of the cover plate.

12. The superconducting machine of claim 8, wherein the torque transfer component further comprises a torque disk and a torque tube holder, the torque disk secured to the coil support structure via at least one at least one fastener, the torque tube holder configured to secure the torque tube to at least one of the coil support structure or the torque disk.

13. The superconducting machine of claim 12. further comprising a spring placed around the at least one fastener.

14. The superconducting machine of claim 8, further comprising a thermal layer, the thermal layer comprising a coating formed of one or more coating layers, wherein the one or more coating layers are placed on at least one of the torque transfer component, the coil support structure, or the at least two superconducting coils.

15. The superconducting machine of claim 1, wherein the at least two cooling tubes comprises a first cooling tube and a second cooling tube, the first and second cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil.

16. The superconducting machine of claim 1, further comprising an armature arranged with the vacuum vessel, the armature configured to rotate within a magnetic field generated by the at least one superconducting coil, wherein the armature comprises a winding, the winding comprising at least one of a hybrid Gramme winding or a fractional slot winding.

17. A cooling system for cooling at least one superconducting coil of a superconducting machine, the cooling system comprising: a torque transfer component secured to an interior wall of a vacuum vessel of the superconducting machine, the at least one superconducting coil being secured to the torque transfer component; a cryocooler comprising a forced-flow cooling system; and at least two cooling tubes for cry ogen supply and return, the at least two cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling tubes.

18. The cooling system of claim 17, wherein the forced-flow cooling system comprises a reverse-Brayton cryocooling system.

19. The cooling system of claim 17, wherein the at least two cooling tubes comprises a first cooling tube and a second cooling tube, the first and second cooling tubes thermally coupled between the cryocooler and the at least one superconducting coil.

20. A method of cooling at least one superconducting coil of a superconducting machine, the superconducting machine having a vacuum vessel with the at least one superconducting coil arranged therein, the method comprising: arranging a cooling system in thermal communication with the at least one superconducting coil, wherein arranging the cooling system in thermal communication with the at least one superconducting coil comprises: arranging a cryocooler of the cooling system exterior to the vacuum vessel; and thermally coupling at least two cooling tubes between the cryocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system; and operating the cooling system to supply a cryogen to the at least one superconducting coil via the at least two cooling tubes.