Forced flow cooling system for superconducting machine

Abstract

A superconducting machine includes a vacuum vessel, at least one superconducting coil disposed within the vacuum vessel, and a cooling system for cooling the at least one superconducting coil. The cooling system includes a torque transmitting member secured to an inner wall of the vacuum vessel, at least one superconducting coil secured to the torque transmitting member. The cooling system also includes a cryocooler external to the vacuum vessel, the cryocooler including a forced flow cooling system. The cooling system also includes at least two cooling tubes for supply and return of refrigerant, the at least two cooling tubes being thermally coupled between the cryocooler and the at least one superconducting coil. By operating the cooling system, the cryocooler supplies refrigerant to the at least one superconducting coil via the at least two cooling tubes.

Description

[0001] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] 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 this invention. Technical Field

[0003] The present disclosure relates generally to superconducting generators, and more particularly to a cooling system for cooling superconducting coils of a superconducting generator. Background Art

[0004] Wind turbines have garnered increasing attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable effort has been devoted to developing reliable and efficient wind turbines. A wind turbine generally includes a rotor having a plurality of rotor blades coupled to a rotatable hub. The rotor is rotatably coupled to a nacelle mounted atop a tower. The rotor blades convert wind energy into rotational torque, or force, that drives a generator, which is rotationally coupled to the rotor.

[0005] Various electric generators, such as superconducting generators, are being explored for use in wind turbine installations, particularly in direct-drive offshore installations. These machines utilize conventional armature coils, a cooling system, and an assembly of non-magnetic teeth disposed between the coils in the armature, along with superconducting field windings. In certain designs, superconducting generators include an armature winding assembly that, unlike conventional machine configurations (e.g., conventional non-superconducting generators), rotates within a superconducting field assembly that includes a cryostat with the superconducting field coils within the cryostat.

[0006] Superconducting machines typically also include a cooling system for cooling the superconductors to cryogenic temperatures.Therefore, the art is continually seeking new and improved cooling systems for superconducting generators. Summary of the Invention

[0007] 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.

[0008] In one aspect, the present disclosure is directed to a superconducting machine. The superconducting machine includes a vacuum vessel, at least one superconducting coil disposed within the vacuum vessel, and a cooling system for cooling the at least one superconducting coil. The cooling system includes a torque transfer member secured to an inner wall of the vacuum vessel, the at least one superconducting coil secured to the torque transfer member. The cooling system also includes a cryocooler external to the vacuum vessel, the cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling pipes for supplying and returning a refrigerant, the at least two cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil. Once configured, the cryocooler supplies refrigerant to the at least one superconducting coil via the at least two cooling pipes.

[0009] In an embodiment, the forced flow cooling system comprises a reverse-Brayton cryogenic cooling system.

[0010] In further embodiments, the torque transfer member is configured to secure the at least one superconducting coil in place.Furthermore, the torque transfer member comprises a torque tube.

[0011] In additional embodiments, the torque tube is secured to opposite sides of the vacuum vessel.

[0012] In other embodiments, the torque tube extends in a radial direction relative to the superconducting machine.

[0013] In still other embodiments, the torque tube extends in an axial direction or a circumferential direction relative to the superconducting machine.

[0014] In other additional embodiments, the torque tube is a cantilevered member secured to the inner wall of the vacuum vessel.

[0015] In yet additional embodiments, the cooling system further comprises a coil support structure, the at least one superconducting coil being arranged within the coil support structure.

[0016] In still other embodiments, the coil support structure is constructed of at least one of a metal or a metal alloy or a metal additive material or a composite material.

[0017] In some other embodiments, a portion of one of the at least two cooling tubes is arranged in the coil support structure. In addition, the portion of the cooling tube arranged in the coil support structure is at least wound around a portion of the at least one superconducting coil.

[0018] In other embodiments, the coil support structure further includes a cover plate having an inner surface and an outer surface, at least one of the at least two cooling tubes being secured to the inner surface of the cover plate.

[0019] In yet other embodiments, the torque transfer member further includes a torque disc and a torque tube retainer, the torque disc being secured to the coil support structure via at least one fastener, the torque tube retainer being configured to secure the torque tube to at least one of the coil support structure or the torque disc.

[0020] In still other embodiments, the superconducting machine further includes a spring positioned around the at least one fastener.

[0021] In yet other embodiments, the superconducting machine further includes a thermal layer comprising a coating formed of one or more coating layers. In addition, the one or more coating layers are disposed on at least one of the torque transfer member, the coil support structure, or the at least two superconducting coils.

[0022] In other embodiments, the at least two cooling tubes include a first cooling tube and a second cooling tube, the first cooling tube and the second cooling tube being thermally coupled between the cryocooler and the at least one superconducting coil.

[0023] In another embodiment, the superconducting machine further includes an armature arranged together with the vacuum vessel, the armature being configured to rotate within a magnetic field generated by the at least one superconducting coil. In addition, the armature includes a winding, the winding including at least one of a hybrid Gramme winding or a fractional slot winding.

[0024] 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 transmission member fixedly attached to an inner wall of a vacuum vessel of the superconducting machine, and the at least one superconducting coil is fixedly attached to the torque transmission member. The cooling system also includes a cryocooler comprising a forced-flow cooling system. The cooling system also includes at least two cooling pipes for supplying and returning refrigerant, the at least two cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil. In operation, the cryocooler supplies refrigerant to the at least one superconducting coil via the at least two cooling pipes.

[0025] In another aspect, the present disclosure is directed to a method for cooling at least one superconducting coil of a superconducting machine having a vacuum vessel in which the at least one superconducting coil is disposed. The method includes arranging a cooling system in thermal communication with the at least one superconducting coil. Arranging the cooling system in thermal communication with the at least one superconducting coil includes a plurality of steps. Specifically, arranging the cooling system includes arranging a cryocooler of the cooling system outside the vacuum vessel. Arranging the cooling system also 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 arranged, the method also includes operating the cooling system to supply refrigerant to the at least one superconducting coil via the at least two cooling tubes.

[0026] 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 present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] A complete and enabling disclosure of the invention, including the best mode thereof, to one skilled in the art is set forth in the specification which proceeds with reference to the accompanying drawings in which:

[0028] Figure 1 illustrates a perspective view of one embodiment of a wind turbine having a generator according to the present disclosure;

[0029] Figure 2 illustrates an interior perspective view of one embodiment of a nacelle of a wind turbine having a superconducting generator according to the present disclosure;

[0030] Figure 3 Illustrated is a side view of a superconducting generator according to aspects of the present invention;

[0031] FIG4 illustrates a simplified schematic diagram of a superconducting generator according to conventional construction, particularly illustrating a cooling system arranged together with a heat shield of the generator;

[0032] Figure 5 A simplified schematic diagram of a forced flow cooling system according to the present disclosure is shown.

[0033] Figure 6 FIG. 1 illustrates a superconducting generator arranged together with the present disclosure. Figure 5 A simplified schematic diagram of a forced flow cooling system;

[0034] Figure 7 illustrates a side view of a superconducting generator, particularly illustrating the arrangement of torque transfer members, coil support structures, and cooling tubes according to the present disclosure;

[0035] Figure 8 illustrates an internal radial view of a coil support structure, particularly illustrating the arrangement of cooling tubes according to the present disclosure;

[0036] Figure 9 illustrates an interior radial view of a coil support structure, which particularly illustrates another arrangement of cooling tubes according to the present disclosure;

[0037] Figure 10 illustrates a radially outward view of a coil support structure, which particularly illustrates another arrangement of cooling tubes according to the present disclosure;

[0038] Figure 11illustrates a side view of a superconducting generator, particularly illustrating another arrangement of torque transfer members, coil support structures, and cooling tubes according to the present disclosure;

[0039] FIG. 12A to FIG. 12B illustrates various embodiments of fasteners according to the present disclosure that are configured to assemble and secure a torque transfer member to a coil support structure;

[0040] Figure 13 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of torque transfer members, coil support structures, and cooling tubes according to the present disclosure;

[0041] Figure 14 illustrates a detailed view of a torque transmitting member disc according to the present disclosure;

[0042] Figure 15 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of torque transfer members, coil support structures, and cooling tubes according to the present disclosure;

[0043] Figure 16 A flow chart illustrating a method of cooling a superconducting generator according to the present disclosure is provided.

[0044] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention. DETAILED DESCRIPTION

[0045] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the present invention, not limitation of the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, features illustrated or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention encompasses such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0046] The terms “coupled,” “fixed,” “attached,” and similar terms refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate members or features, unless specifically stated otherwise herein.

[0047] Superconducting machines, such as superconducting generators, are a class of electric machines that rely on the properties exhibited by superconducting materials. Such generators also exhibit low reactance if produced in an "air-core" configuration. Specifically, an "air-core" configuration is achieved when most of the magnetic material (such as iron) is removed from the armature and field due to the high fields generated by the superconductors. Without removing the magnetic material, the high fields generated by the superconductors can saturate the magnetic material. Therefore, the removal of the magnetic material reduces the generator's reactance.

[0048] Additionally, when superconducting materials are cooled below a certain temperature, known as the "critical temperature," they exhibit a different set of physical and electrical properties. In the field of superconducting power machines, superconducting materials are chosen to form the superconducting coils used in superconducting power machines because, once the coils are cooled below the critical temperature for the respective material, the properties of the superconducting materials and coils allow for the conduction of electrical current without energy loss. This property enables superconducting machines to operate at higher efficiencies and higher magnetic fields than would otherwise be possible without the use of superconducting materials. However, a cooling system is required to ensure that the superconducting coils are maintained below the critical temperature.

[0049] Conventional cooling systems for superconducting machines or generators operate through passive cooling systems, such as by pool boiling or thermosiphons. Pool boiling is a form of cooling in which superconducting coils are immersed in a coolant bath that carries away heat energy from the superconducting coils when they are operating. Thermosiphons operate through a mechanism in which gravity drives the coolant, heavier coolant at the top of the generator toward the bottom. The heating that occurs in the fluid as it passes through and cools the superconductor causes the hotter, lighter fluid to rise again to the top when it reaches the bottom of the generator, where a cooler cools the fluid again to repeat the cycle. For cooling to liquid helium operating temperatures (4.2K), the Gifford-McMahon recirculating cooler is the standard for cooling fluids in smaller applications such as MRI (magnetic resonance imaging).

[0050] For example, referring now to the accompanying drawings, Figure 1 Figures 4 to 5 illustrate a conventional passive cooling system for a generator housed within a wind turbine. Figure 1 In FIG, a perspective view of a wind turbine with a generator is shown. Figure 2 In FIG, an interior view of a nacelle of a wind turbine with a superconducting generator is shown. Figure 3 In FIG4 , a side view of a conventional superconducting generator is shown. In FIG4 , a simplified schematic diagram of a superconducting generator according to a conventional construction is shown, which in particular illustrates a cooling system arranged together with a heat shield of the generator.

[0051] More specifically, now refer to Figure 1, illustrates a perspective view of an embodiment of a wind turbine 10. Wind turbine 10 includes a tower 12 extending from a support surface 14, a nacelle 16 mounted on tower 12, and a rotor 18 coupled to nacelle 16. Rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outwardly from hub 20. For example, in the illustrated embodiment, rotor 18 includes three rotor blades 22. However, in alternative embodiments, rotor 18 may include more or fewer than three rotor blades 22. Each rotor blade 22 may be spaced about hub 20 to facilitate rotating rotor 18, thereby enabling kinetic energy from the wind to be converted into usable mechanical energy and subsequently into electrical energy. For example, hub 20 may be rotatably coupled to an electrical generator (not shown) positioned within nacelle 16 to enable the generation of electrical energy.

[0052] Now refer to Figure 2 , illustrates an interior perspective view of an embodiment of a nacelle 16 having a superconducting generator 23 housed therein in accordance with the present disclosure. Furthermore, as shown, a support tube 41 is directly connected to the hub 20 and supports the armature winding assembly 24. Thus, the armature winding assembly 24 is considered to be a rotating component of the generator 23 having a rotating first electromagnetic component configuration that rotates about a stationary field assembly 26 (such as a superconducting field winding assembly 26) having a second electromagnetic component configuration.

[0053] The static field assembly 26 includes superconducting coils 52, which can be a set of wires formed in a racetrack shape. Thus, in certain embodiments, the superconducting coils 52 are constrained to maintain the racetrack shape. Furthermore, as shown, each superconducting coil 52 is supported in a recess / channel 50 in the housing 42, which can be conductively cooled by cryogenic cooling tubes filled with a cryogen (e.g., helium, hydrogen, or neon) for the purpose of removing heat from the superconducting coils. As such, the housing 42 can be supported in a cryostat housing 36 (also referred to herein as a vacuum vessel), which is secured to a base tube 44.

[0054] Still refer to Figure 2 , the superconducting coils 52 may be arranged side by side in an annular array extending around the housing 42. For example, in an embodiment, thirty-six coils may form an annular array of field windings that serve as stator field windings for the generator 23. Furthermore, in an embodiment, the superconducting coils 52 may each be formed from a wire (of NbTi or other superconducting material) wound in a helical path around a racetrack form that may include a cooling conduit for the cryogen. The stationary field assembly 26 includes a superconducting coil magnet 54 produced by passing an electric current through the superconducting field coils 52, which is enclosed in the housing 42 and receives cryogen through cooling recesses / channels 50.

[0055] In additional embodiments, the cryogen recondensers 38, 40 may be housed within the field coil assembly 26, so long as the cryogen cooling liquid in the recondensers 38, 40 is at least partially elevated above the superconducting field windings to provide a gravity feed of cryogen to the windings. Alternatively, the recondensers 38, 40 may be mounted on top of the field coil assembly.

[0056] Now refer to Figure 3 , illustrates a cross-section of an embodiment of a direct-drive superconducting generator 23 in which a toroidal rotating armature winding assembly 24 ("armature 24") is radially inward of a stationary field assembly 26. It should be understood that the present disclosure described herein also functions with the armature winding assembly 24 positioned radially outward of the stationary field assembly 26. In particular, as shown, the armature 24 is substantially an inner toroidal ring configuration ( Figure 3 ). The armature 24 includes conductive coils 52 (e.g., coils or rods) arranged longitudinally along the length of the armature 24 and arranged on the inner cylindrical surface of the armature 24. The conductive coils 52 can be connected to each other at opposite ends of the conductive coils 52 by conductive end turns 28. The end turns 28 between the longitudinal conductive coils 52 depend on the number and arrangement of the conductive coils 52 and the phase of the electricity to be generated in the conductive coils 52. The outer cylindrical surface of the armature winding is separated from the inner surface of the stationary field assembly 26 by a narrow air gap (e.g., about 10 mm to 25 mm).

[0057] Generally speaking Figure 3 , the armature 24 includes a cylindrical yoke or body 30 (referred to herein as the "body") that supports a conductive coil 52. In particular, the conductive coil 52 is contained in slots defined between adjacent teeth extending radially from the body 30. The body 30 and the teeth may be of a layered laminated construction. The inner surface of the body 30 is fixed to a cylindrical housing 32 that rotates with the armature 24. In addition, as shown, the stationary field winding assembly 26 may be supported by a field winding support disk 34. In addition, the field winding support disk 34 is attached to the superconducting coil 52 ( Figure 2 ) at the ends of a cryostat housing 36. The housing 36 and its cooling components form a cryostat which cools the superconducting coils of the field windings.

[0058] The cryostat housing 36 insulates the superconducting coils 52 so that they can be cooled to a temperature near absolute zero, for example, to about 20 Kelvin (K), more preferably about 10 K, and even more preferably about 4 K. To cool the windings, the cryostat housing 36 may include one or more insulated conduits 46 to receive liquid helium (He) or other similar cryogenic liquids, such as liquid neon (Ne) or liquid hydrogen (H), referred to as cryogen. A conventional two-stage recondenser 38 is mounted in the upper region of the field coil assembly, on top of the field coil assembly, or on top of the tower 12 above the field windings to provide cryogen (e.g., liquid He) using a gravity feed. A second recondenser 40 may provide a second cooling liquid (e.g., liquid nitrogen or liquid neon) to the internal heat shield of the cryostat housing 36 via conduits 48.

[0059] Referring now to FIG4 , 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 the cooling system 102 arranged along with a thermal shield 104, a vacuum vessel 106, a cold mass 108, and a cryocooler 110 of the generator 100. In such an embodiment, 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 in Figure 3 4 to 5. Figure 9 Furthermore, as an example, the vacuum vessel 106 may be a non-rotatable component that supports a field winding assembly, such as the stationary field assembly 26 .

[0060] Thus, in such embodiments, the rotatable component may be oriented to rotate relative to the non-rotatable component during operation of the generator 100, such as Figure 3 . In such a conventional configuration, the thermal shield 104 intercepts and / or blocks radiation from the vacuum vessel 106 (as indicated by arrow 114). In addition, as shown, heat is removed to the cryocooler 110 via the thermal busbars / busbars 112, thereby blocking most of the radiant heat from the cold mass 108. In addition, as shown, the (multiple) thermal busbars / busbars 112 of such a configuration are attached to the top of the thermal shield 104 for connection to the cryocooler 110. The thermal shield 104 also intercepts heat that is conducted through structural members, such as those used to hold the static field assembly 26 in place.

[0061] However, reference Figure 1Each of these types of passive cooling systems discussed through Figure 4 (e.g., thermosiphon coolers or pool boiling) has limitations in the amount of cooling power that can be provided due to its reliance on passive cooling devices. Furthermore, each of these types of passive cooling systems requires the use of a large number of components that are difficult to manufacture and assemble and therefore costly.

[0062] Thus, the present disclosure is generally directed to a superconducting machine that utilizes a forced-flow cooling system to cool superconducting coils disposed therein, as compared to passive cooling arrangements. Furthermore, the superconducting machine may include an architecture that exploits the benefits provided by the use of forced-flow cooling. For example, specific and more general orientations of cooling tubes may be provided with the superconducting coils for cooling, independent of the direction of gravity. Apparatus and methods may be provided to account for torsional forces generated by the superconducting coils. Specifically, torque transfer components may be provided to account for movement generated by relative magnetic fields within the superconducting machine or initial contraction and expansion of the superconducting coils during operation. The cooling system may also enable different types of electrical components to be used with the superconducting machine that would not be possible with a passively cooled superconducting machine. For example, an armature having windings not previously implemented may be provided with the superconducting machine.

[0063] By providing a superconducting machine having any of these aforementioned features, the overall efficiency of the superconducting machine may be increased while also reducing the overall cost of manufacturing and operating such a machine.

[0064] Furthermore, utilizing a forced-flow cooling system provides various advantages. For example, cooling power and heat removal can be made variable and optimized for the operating superconducting machine. Furthermore, the flow of cooling power can be specifically directed to desired locations while minimizing flow maldistribution. Furthermore, the flow of cooling power can be maintained continuously without any interruptions in heat transfer. Furthermore, the forced-flow cooling system does not require any specific requirements for the internal environment within the superconducting machine (such as pressure level) in order to utilize the cooling system.

[0065] Superconducting machines can be compared with reference Figure 1 4, while providing the advantages of utilizing a forced flow cooling system. For example, the present disclosure is directed to a method particularly well suited for use in a wind turbine 10 ( Figure 1 ) is used in a superconducting machine, but the superconducting machine is not limited to such use. Figure 1 An "onshore" (land-based) wind turbine 10 installation is depicted; however, it will be appreciated that the present invention is not limited to onshore wind turbines and is equally applicable to "offshore" (water-based) wind turbine installations having fixed or floating foundations, where the generally larger generators may benefit more from forced flow cooling.

[0066] Special reference Figure 5 , illustrates a simplified schematic diagram of a forced-flow cooling system 200 according to the present disclosure. More specifically, as shown, the depicted forced-flow cooling system 200 demonstrates a means by which thermal energy can be transferred with reference to a superconducting machine as presently disclosed. Specifically, an inverse Brayton cryogenic cooling system (also known as gas refrigeration or Bell-Coleman or Joule cycles, and closely related to Claude or Linde cycles) is depicted. However, other forced-flow cooling systems may also be included.

[0067] Furthermore, in an embodiment, as shown, 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 path 212. Generally, forced-flow cooling system 200 moves thermal energy Q from cold reservoir 202 to hot reservoir 204. Specifically, forced-flow cooling system 200 moves thermal energy Q from cold reservoir 202 into first heat exchanger 206 and out through second heat exchanger 208 to hot reservoir 204. This transfer of thermal energy Q is achieved through the use of turbine-compressor 210 and thermal path 212. Furthermore, in an embodiment, turbine-compressor 210 applies work W to cooling system 200 sufficient to drive thermal energy Q from first heat exchanger 206 to second heat exchanger 208. Thermal path 212 allows thermal energy Q to be transferred from first heat exchanger 206 to second heat exchanger 208. The following will refer to Figures 6 to 16 Such a process is described in more detail.

[0068] Now refer to Figure 6 , illustrates a simplified schematic diagram of an embodiment of a forced flow cooling system 306 disposed in conjunction with a superconducting generator. As shown, superconducting generator 300 includes a vacuum vessel 302, at least one superconducting coil 304, and cooling system 306. Specifically, superconducting coil(s) 304 are disposed within vacuum vessel 302. Furthermore, cooling system 306 cools superconducting coil(s) 304.

[0069] 4 and include features of the vacuum vessel 106. 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 serve as a thermal barrier for the superconducting coil(s) 304. Additionally, the superconducting coil(s) 304 may be similar to the superconducting coil 52 or the field assembly 26 and include the same features as the superconducting coil 52 or the field assembly 26, such as the shape, orientation, or material forming the coil 52.

[0070] Still refer to Figure 6The cooling system 306 may further include a cryocooler 308 and at least two cooling pipes 310 for supplying and returning a cryogen. The cryocooler 308 may be mounted on or around the exterior of the vacuum vessel 302. As previously mentioned, the cryocooler 308 is a forced flow cooling system, such as an inverse Brayton cryogenic cooling system. The cooling pipes 310 may be thermally coupled between the cryocooler 308 and the superconducting coils 304. In addition, the cryocooler 308 may supply a coolant, refrigerant, or cryogenic cooling fluid to the superconducting coils 304 via the cooling pipes 310.

[0071] In addition, as shown, the superconducting generator 300 may also include various other components. Figure 6 As shown in FIG, the superconducting generator 300 may further include a torque transfer member 312, a thermal layer 314, and an armature 316. The torque transfer member 312 may be configured to secure the superconducting coil(s) 304 in place when the superconducting coil(s) 304 are in operation. The thermal layer 314 may provide additional thermal insulation to the superconducting coil(s) 304, if desired. Another advantage of forced cooling, with its higher cooling power, is that the thermal layer 314 does not need to be separately cooled, as is the case with all Gifford-McMahon and pool boiling systems, in order to achieve 4K 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 the magnetic field generated by the superconducting coil(s) 304. The armature 316 may include features of the armature 24, such as the armature windings. However, the armature 316 may also include features different from those of the armature 24. For example, the armature 316 may include at least one of a hybrid Grammar winding or a fractional slot winding. These types of winding / armature topologies were previously impossible due to insufficient cooling power provided by passive cooling systems for superconducting generators due to eddy current heating of the field by the armature winding. However, the cooling system of the present disclosure provides sufficient cooling power such that hybrid Grammar windings or fractional slot windings may now be possible.

[0072] The following will refer to Figures 7 to 16 Each of the components of superconducting generator 300 is discussed in more detail.

[0073] Now refer to Figure 7 , shows a side view of superconducting generator 300, which particularly illustrates the arrangement of torque transfer member 312, coil support structure 320, and cooling tube 310. As shown, torque transfer member 312 is arranged within vacuum vessel 302. In particular, torque transfer member 312 can be secured to the inner wall of vacuum vessel 302 and to superconducting coil(s) 304, thereby securing superconducting coil(s) 304 in place.

[0074] In certain embodiments, as shown, the torque transfer member 312 may include a torque tube 318. Although the torque tube 318 is described as a tube, the torque tube 318 may take on various other non-cylindrical or non-tubular shapes. Figure 7 , for example, the torque tube 318 may be secured to opposite sides of the vacuum vessel 302. Such an orientation allows the torque tube 318 to distribute mechanical forces experienced by the torque tube 318 (such as forces caused by expansion of the superconducting coil(s) 304 or forces caused by the magnetic field generated by the superconducting coil(s) 304) equally to both sides of the vacuum vessel 302.

[0075] In addition, as shown, the torque tube 318 may extend in a specific direction. For example, the torque tube 318 may extend in a radial direction relative to the generator axis 319 of the superconducting generator 300. Alternatively, the torque tube 318 may extend in an axial direction relative to the generator axis 319 of the superconducting generator 300. Specific portions of the torque tube 318 may also extend in various ways. For example, a portion of the torque tube 318 may extend in a radial direction, while another portion extends in an axial direction. Furthermore, as shown, (multiple) cooling tubes 310 may also be provided within the torque tube 318. By doing so, the torque transfer member 312 may be cooled together with the (multiple) superconducting coils 304. Reference will be made to Figures 11 to 16 Specific embodiments of the orientation of the torque transmitting member 312 and the torque tube 318 are discussed in greater detail.

[0076] Still refer to Figure 7 The superconducting generator 300 may further 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 from a variety of materials. For example, the coil support structure 320 may be constructed from at least one of a metal, a metal alloy, or a composite material. In an exemplary embodiment, the coil support structure 320 may be constructed from stainless steel. By constructing the coil support structure 320 from stainless steel, greater strength may be provided to accommodate the superconducting coil(s) 304.

[0077] Furthermore, the cooling tube(s) 310 may be disposed 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 disposed within the coil support structure 320, and the portion of the cooling tube(s) 310 disposed within the coil support structure 320 may be wrapped around at least a portion of the superconducting coil(s) 304. Figures 8 to 10 Specific embodiments of the placement of the cooling tube(s) 310 relative to the coil support structure 320 are discussed in more detail.

[0078] As previously referenced Figure 6 As mentioned, superconducting generator 300 may also include a thermal layer 314. Compared to conventional superconducting generators that utilize thermal shields formed from solid sheet materials such as steel, thermal layer 314 may take the form of a coating formed from one or more coating layers. For example, the coating layer may be a multi-layer insulator (MLI) formed from multiple layers of thin sheet materials. In certain embodiments, the coating layer may also be a coating that is sprayed or applied as needed. The material used to make thermal layer 314 may be at least one of metal foil segments. Once selected, the coating layer(s) are placed on at least one of torque transfer member 312 or coil support structure 320. By using thermal layer 314, the thermal burden on the superconducting coils is reduced. Furthermore, the overall weight of superconducting generator 300 may be reduced, which is particularly beneficial when superconducting generator 300 is placed in an elevated location, such as within a wind turbine. This weight reduction is achieved by replacing conventional thermal shields with the lighter thermal layer 314. Such replacement is made possible by the increased cooling power provided through the use of forced flow cooling system 200 within superconducting generator 300 .

[0079] In another embodiment, Figure 7 As shown in FIG, the torque transfer member 312 may further include a torque disc 322 and a torque tube retainer 324. As shown, the torque disc 322 may be secured to the coil support structure 320 via at least one fastener 326. Additionally, the torque tube retainer 324 may be configured to secure the torque tube 318 to the coil support structure 320 ( Figure 7 ) and / or torque disc 322. FIG. 12A to FIG. 12B and Figures 14 and 15 The torque plate 322 and the torque tube retainer 324 are discussed in greater detail.

[0080] Additionally, each of the components of the torque transfer member 312 may be made of a specific material. For example, the torque tube 318, the torque disc 322, and the torque tube retainer 324 may be made of a metal or metal alloy such as Steel) formed.

[0081] Now refer to Figures 8 to 10 , depicting various orientations and placements of cooling tubes. Figure 8, illustrates an interior top view of an embodiment of the coil support structure 320. Specifically, as shown, the cooling tube(s) 310 include a first cooling tube 328 and a second cooling tube 330. Like the cooling tube(s) 310, the first cooling tube 328 and the second cooling tube 330 are thermally coupled between the cryocooler 308 and the superconducting coil(s) 304. Furthermore, the first cooling tube 328 can be positioned on one side of the superconducting coil(s) 304, and the second cooling tube 330 can be positioned on the opposite side of the superconducting coil(s) 304. Specifically, in the exemplary embodiment, the first cooling tube 328 and the second cooling tube 330 are depicted as being positioned along the shorter, curved portion of the racetrack shape of the superconducting coil(s) 304. However, the first cooling tube 328 and the second cooling tube 330 can also be positioned along the longer, straight portion of the racetrack shape of the superconducting coil(s) 304. The first cooling tube 328 and the second cooling tube 330 can be connected to the same cryocooler 308. Alternatively, first cooling tube 328 and second cooling tube 330 may be connected to two separate low-temperature coolers 308 .

[0082] Special reference Figure 9 , illustrates an interior top view of another embodiment of a coil support structure 320, specifically showing another arrangement of cooling tube(s) 310. Specifically, as shown, cooling tube(s) 310 are positioned along two longer straight portions and one of the shorter curved portions of the racetrack shape of superconducting coil(s) 304. Providing cooling tube(s) 310 along a greater length of superconducting coil(s) 304 enables a greater amount of cooling power to be delivered to superconducting coil(s) 304.

[0083] Now specifically refer to Figure 10 , illustrates an interior view of yet another embodiment of a coil support structure 320, which particularly illustrates yet another arrangement of (multiple) cooling tubes 310. As shown, the coil support structure 320 may include a cover plate 332 having an inner surface 331 and an outer surface 333. If a cover plate 332 is provided, the (multiple) cooling tubes 310 may be fixedly attached to the inner surface 331 of the cover plate 332. In addition, the (multiple) cooling tubes 310 may be fixedly attached in various ways. For example, the (multiple) cooling tubes 310 may be fixedly attached in a manner similar to Figures 8 and 9 Alternatively, the cooling tube(s) 310 may be secured in a zigzag manner, thereby covering a larger area of the coil support structure 320 and providing a greater amount of cooling power to the superconducting coil(s) 304.

[0084] Special reference Figure 11, illustrates a side view of another embodiment of a superconducting generator 300, particularly showing another arrangement of a torque transfer member 312, a coil support structure 320, and a cooling tube 310. As shown, a torque tube 318 may be a cantilevered member affixed to the inner wall of the vacuum vessel 302. By cantilevering the torque tube 318, the torque tube 318 may be able to compensate for mechanical forces experienced by the torque transfer member 312. For example, if the superconducting coil(s) 304 experience contraction during operation, the cantilevering of the torque tube 318 may allow the torque tube 318 to flex to compensate for the movement caused by the contraction.

[0085] Special reference FIG. 12A to FIG. 12B , illustrates various embodiments of fasteners configured to assemble and secure the torque transfer member 312 to the coil support structure 320. Figure 12A As shown in FIG, fastener(s) 326 may be used to secure the torque tube 318 or the coil support structure 320. The torque tube 318 may be secured to various components within the superconducting generator 300. For example, fastener(s) 326 may secure the torque tube 318 to the torque plate 322, as shown in FIG. Figure 12B The fastener(s) 326 may also secure the torque tube 318 to the coil support structure 320 ( Figure 7 、 Figure 11 and Figures 14 to 16 The fastener(s) 326 may also secure the torque tube 318 to the torque tube retainer 324 ( Figure 11 ). In addition, if Figure 12B As shown in FIG, springs 334 may be placed around fastener(s) 326. By providing springs 334, torque transfer member 312 may be able to better handle mechanical forces. For example, if compression occurs along fastener(s) 326 due to operation of superconducting generator 300, springs 334 may be able to accommodate the compression without causing deformation of fastener(s) 326.

[0086] Now refer to Figure 13 , illustrates a side view of another embodiment of a superconducting generator 300, specifically depicting another arrangement of a torque transfer member 312, a coil support structure 320, and a cooling tube 310. In particular, a torque tube retainer 324 can be positioned at various locations. For example, the torque tube retainer 324 can be positioned toward the center of the coil support structure 320.

[0087] also, Figure 13A heat path 336 is depicted in which thermal energy is transferred through the superconducting generator 300. As shown, the heat path 336 originates at the superconducting coil(s) 304 and travels through the coil support structure 320 and the torque tube holder 324 to reach the torque tube 318. The thermal energy then travels outward along the torque tube 318 to reach the vacuum vessel 302. By placing the cooling tube(s) 310 along this path (e.g., within the torque tube 318 or within the coil support structure 320), the overall cooling efficiency of the superconducting generator 300 can be increased.

[0088] Now refer to Figure 14 , illustrates a detailed view of an embodiment of a torque transfer member disk 322. As shown, the torque disk 322 can include a plurality of fasteners 326 to secure the torque disk 322 to the torque tube 318, the coil support structure 320, or the torque tube holder 324. The placement of the cooling tube(s) 310 within the torque disk 322 can increase the overall cooling efficiency of the superconducting generator 300.

[0089] Now refer to Figure 15 , illustrates a side view of an embodiment of a superconducting generator 300, particularly depicting another arrangement of a torque transfer member 312, a coil support structure 320, and cooling tubes 310. As shown, cooling tube(s) 310 may be placed throughout the superconducting generator 300. For example, cooling tube(s) 310 may be placed along portions of a torque tube 318.

[0090] Furthermore, different types of cooling can be used. For example, if multiple cooling tubes 310 are used, the cooling tubes 310 can be of different types. Specifically, at least one of the cooling tubes 310 can be connected to the forced-flow cooling system 200, while another of the cooling tubes 310 can be connected to a different cooling device. For example, the cooling device can be a gas tank 338 that provides passive cooling in addition to the active cooling provided by the forced-flow cooling system 200.

[0091] Generally speaking Figure 16 , illustrates a flow chart of an embodiment of a method for cooling a superconducting generator. Although for purposes of illustration and discussion, Figure 16 The steps are depicted as being performed in a particular order, but the methods described herein are not limited to any particular order or arrangement. Using the disclosure provided herein, one skilled in the art will appreciate that the various steps of the methods may be omitted, rearranged, combined, and / or adapted in various ways.

[0092] As shown at (402), method 400 includes arranging a cooling system to be in thermal communication with at least one superconducting coil. Specifically, arranging the cooling system to be in thermal communication with at least one superconducting coil may include multiple steps. For example, as shown at (404), method 400 includes arranging a cryocooler of the cooling system outside the vacuum vessel, and as shown at (406), method 400 includes thermally coupling at least two cooling tubes between the cryocooler and at least one superconducting coil, the cryocooler having a forced flow cooling system. Once the cooling system is set up, as shown at (408), method 400 may also include operating the cooling system to supply a refrigerant or cryogenic cooling fluid to the at least one superconducting coil via the at least two cooling tubes.

[0093] Those skilled in the art 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 method and feature, can be mixed and matched by one of ordinary skill in the art to construct additional systems and techniques according to the principles of the present disclosure. Of course, it is to be understood that not all such objects or advantages described above may be achieved according to any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or performed in a manner that achieves or optimizes one advantage or set of advantages as taught herein, without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0094] Further aspects of the invention are provided by the subject matter of the following clauses:

[0095] Clause 1. A superconducting machine comprising:

[0096] Vacuum container;

[0097] at least one superconducting coil disposed within the vacuum vessel; and

[0098] A cooling system for cooling at least one superconducting coil, the cooling system comprising:

[0099] a torque transmission member fixedly connected to the inner wall of the vacuum container, and at least one superconducting coil fixedly connected to the torque transmission member;

[0100] a cryocooler, which is outside the vacuum container, the cryocooler including a forced flow cooling system, and

[0101] At least two cooling pipes are provided for supplying and returning a cryogen, wherein the at least two cooling pipes are thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies the cryogen to the at least one superconducting coil via the at least two cooling pipes.

[0102] Clause 2. The superconducting machine of clause 1, wherein the forced flow cooling system comprises an inverse Brayton cryogenic cooling system.

[0103] Clause 3. The superconducting machine of any of clauses 1-2, wherein the torque transfer member is configured to secure the at least one superconducting coil in place, wherein the torque transfer member comprises a torque tube.

[0104] Clause 4. The superconducting machine of clause 3, wherein the torque tubes are secured to opposite sides of the vacuum vessel.

[0105] Clause 5. A superconducting machine according to any of clauses 3-4, wherein the torque tube extends in a radial direction relative to the superconducting machine.

[0106] Clause 6. A superconducting machine according to any of clauses 3-5, wherein the torque tube extends in an axial direction or a circumferential direction relative to the superconducting machine.

[0107] Clause 7. A superconducting machine according to any of clauses 3 or 5-6, wherein the torque tube is a cantilevered member affixed to an inner wall of the vacuum vessel.

[0108] Clause 8. The superconducting machine of any of clauses 3-7, wherein the cooling system further comprises a coil support structure, the at least one superconducting coil being arranged within the coil support structure.

[0109] Clause 9. The superconducting machine of clause 8, wherein the coil support structure is constructed of at least one of a metal or a metal alloy or a metal additive material or a composite material.

[0110] Clause 10. A superconducting machine according to any of clauses 8-9, wherein a portion of 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 wound around at least a portion of the at least one superconducting coil.

[0111] Clause 11. The superconducting machine of any of clauses 8-10, wherein the coil support structure further comprises a cover plate having an inner surface and an outer surface, at least one of the at least two cooling tubes being secured to the inner surface of the cover plate.

[0112] Clause 12. A superconducting machine according to any of clauses 8-11, wherein the torque transfer member further comprises a torque disc and a torque tube retainer, the torque disc being secured to the coil support structure via at least one fastener, the torque tube retainer being configured to secure the torque tube to at least one of the coil support structure or the torque disc.

[0113] Clause 13. The superconducting machine of clause 12, further comprising a spring positioned around the at least one fastener.

[0114] Clause 14. A superconducting machine according to any of clauses 8-13, further comprising a thermal layer comprising a coating formed of one or more coating layers, wherein the one or more coating layers are disposed on at least one of the torque transfer member, the coil support structure, or the at least two superconducting coils.

[0115] Clause 15. The superconducting machine of any of the preceding clauses, wherein the at least two cooling tubes include a first cooling tube and a second cooling tube, the first cooling tube and the second cooling tube being thermally coupled between the cryocooler and the at least one superconducting coil.

[0116] Clause 16. A superconducting machine according to 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 comprising at least one of a hybrid Gram winding or a fractional slot winding.

[0117] Clause 17. A cooling system for cooling at least one superconducting coil of a superconducting machine, the cooling system comprising:

[0118] a torque transmission member fixedly connected to an inner wall of a vacuum container of a superconducting machine, at least one superconducting coil fixedly connected to the torque transmission member;

[0119] a cryocooler comprising a forced flow cooling system; and

[0120] At least two cooling pipes are provided for supplying and returning a cryogen, wherein the at least two cooling pipes are thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies the cryogen to the at least one superconducting coil via the at least two cooling pipes.

[0121] Clause 18. The cooling system of Clause 17, wherein the forced flow cooling system comprises a reverse Brayton cryogenic cooling system.

[0122] Clause 19. The cooling system of any of clauses 17-18, wherein the at least two cooling tubes include a first cooling tube and a second cooling tube, the first cooling tube and the second cooling tube being thermally coupled between the cryocooler and the at least one superconducting coil.

[0123] Clause 20. A method of cooling at least one superconducting coil of a superconducting machine, the superconducting machine having a vacuum vessel, wherein the at least one superconducting coil is disposed within the vacuum vessel, the method comprising:

[0124] 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:

[0125] arranging a cryocooler of the cooling system outside the vacuum container; and

[0126] thermally coupling at least two cooling tubes between a cryocooler and at least one superconducting coil, the cryocooler having a forced flow cooling system; and

[0127] The cooling system is operated to supply cryogen to the at least one superconducting coil via the at least two cooling tubes.

[0128] 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. If such other examples include structural elements that do not differ from the literal language of the claims, or if such other examples include equivalent structural elements with insubstantial differences from the literal language of the claims, such other examples are intended to be within the scope of the claims.

Claims

1. A superconducting machine comprising: Vacuum container; at least one superconducting coil disposed within the vacuum container; as well as A cooling system for cooling the at least one superconducting coil, the cooling system comprising: a torque transmission member fixedly connected to an inner wall of the vacuum container, wherein the at least one superconducting coil is fixedly connected to the torque transmission member; a cryocooler outside the vacuum container, the cryocooler including a forced flow cooling system, and At least two cooling pipes are provided for supplying and returning a refrigerant, wherein the at least two cooling pipes are thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies the refrigerant to the at least one superconducting coil via the at least two cooling pipes.

2. The superconducting machine according to claim 1, wherein The forced flow cooling system includes an inverse Brayton cryogenic cooling system.

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

4. The superconducting machine according to claim 3, wherein: The torque tubes are secured to opposite sides of the vacuum vessel.

5. The superconducting machine according to claim 3, wherein The torque tube extends in a radial direction relative to the superconducting machine.

6. The superconducting machine according to claim 3, wherein: The torque tube extends in an axial direction or a circumferential direction relative to the superconducting machine.

7. The superconducting machine according to claim 3, wherein: The torque tube is a cantilevered member secured to the inner wall of the vacuum container.

8. The superconducting machine according to claim 3, wherein: The cooling system further includes a coil support structure, the at least one superconducting coil being disposed within the coil support structure.

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

10. The superconducting machine according to claim 8, wherein A portion of 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 wound around at least a portion of the at least one superconducting coil.

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

12. The superconducting machine according to claim 8, wherein The torque transfer member further includes a torque plate secured to the coil support structure via at least one fastener and a torque tube retainer configured to secure the torque tube to at least one of the coil support structure or the torque plate.

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

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

15. The superconducting machine according to claim 1, wherein The at least two cooling tubes include a first cooling tube and a second cooling tube, and the first cooling tube and the second cooling tube are 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 the magnetic field generated by the at least one superconducting coil, wherein The armature includes a winding including at least one of a hybrid Gram 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 transmission member fixedly connected to an inner wall of a vacuum container of the superconducting machine, the at least one superconducting coil being fixedly connected to the torque transmission member; a cryocooler including a forced flow cooling system; as well as At least two cooling pipes are provided for supplying and returning a refrigerant, wherein the at least two cooling pipes are thermally coupled between the cryocooler and the at least one superconducting coil, wherein the cryocooler supplies the refrigerant to the at least one superconducting coil via the at least two cooling pipes.

18. The cooling system according to claim 17, wherein: The forced flow cooling system includes an inverse Brayton cryogenic cooling system.

19. The cooling system according to claim 17, wherein: The at least two cooling tubes include a first cooling tube and a second cooling tube, and the first cooling tube and the second cooling tube are 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, wherein the at least one superconducting coil is arranged in the vacuum vessel, 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 outside the vacuum container; 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 The cooling system is operated to supply cryogen to the at least one superconducting coil via the at least two cooling tubes.

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