Forced-flow cooling systems for superconducting machines.

Abstract

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 transmission component fixed to an inner wall of the vacuum vessel, and the at least one superconducting coil is fixed to the torque transmission component. The cooling system also includes a cryocooler outside the vacuum vessel, the cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling pipes for supplying and recovering a cryogen, the at least two cooling pipes being 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 pipes.

Description

[Technical Field]

[0001] The present disclosure relates generally to superconducting generators, and more particularly to a cooling system for cooling superconducting coils of a superconducting generator. [Background technology]

[0002] Wind turbines are gaining increasing attention as an environmentally safe, relatively inexpensive, alternative energy source. This growing interest has led to significant efforts to develop reliable and efficient wind turbines. A wind turbine typically includes a rotor having multiple 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 rotatably coupled to the rotor.

[0003] Various generators, such as superconducting generators, are being investigated for use in wind turbine installations, particularly direct-drive offshore installations. These machines use superconducting field windings and conventional armature coils, cooling systems, and non-magnetic tooth assemblies disposed between the coils in the armature. In certain designs, superconducting generators differ from conventional machine (e.g., conventional non-superconducting generator) configurations in that they include an armature winding assembly that rotates within a superconducting field assembly that includes a cryostat with superconducting field coils within the cryostat.

[0004] Superconducting machines also typically include a refrigeration system for cooling the superconductor to cryogenic temperatures. Accordingly, there is a constant need in the art for new and improved refrigeration systems for superconducting generators. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2016 / 276906 Summary of the Invention

[0006] Aspects and advantages of the present invention will be set forth in part in the description that follows, 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 disposed within the vacuum vessel, and a cooling system for cooling the at least one superconducting coil. The cooling system includes a torque transmission component fixed to an inner wall of the vacuum vessel, and the at least one superconducting coil is fixed to the torque transmission component. The cooling system also includes a cryocooler outside the vacuum vessel, the cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling pipes for supplying and recovering a cryogen, the at least two cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil. When provided, the cryocooler supplies a cryogen to the at least one superconducting coil via the at least two cooling pipes.

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

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

[0010] In an additional embodiment, the torque tubes are secured to opposite sides of the vacuum vessel.

[0011] In other embodiments, the torque tube extends radially relative to the superconducting machine.

[0012] In yet a further embodiment, the torque tube extends axially or circumferentially relative to the superconducting machine.

[0013] In other additional embodiments, the torque tube is a cantilevered component fixed to the interior wall of the vacuum vessel.

[0014] In yet an additional embodiment, the cooling system further includes a coil support structure, and the at least one superconducting coil is disposed within the coil support structure.

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

[0016] In yet another embodiment, a portion of one of the at least two cooling pipes is disposed within the coil support structure, and further, the portion of the cooling pipe disposed within the coil support structure is wrapped around at least a portion of the at least one superconducting coil.

[0017] In another embodiment, the coil support structure further includes a cover plate having an inner surface and an outer surface, and at least one of the at least two cooling pipes is secured to the inner surface of the cover plate.

[0018] In yet another embodiment, the torque transfer component further includes a torque disc and a torque tube holder, wherein the torque disc is secured to the coil support structure via at least one fastener, and the torque tube holder is configured to secure the torque tube to at least one of the coil support structure or the torque disc.

[0019] In yet another embodiment, the superconducting machine further includes a spring positioned about the at least one fastener.

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

[0021] In another embodiment, the at least two cooling pipes include a first cooling pipe and a second cooling pipe, the first and second cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil.

[0022] In a further embodiment, the superconducting machine further includes an armature disposed 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 Graham 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 transmission component fixed to an inner wall of a vacuum vessel of the superconducting machine, with at least one superconducting coil fixed to the torque transmission component. The cooling system also includes a cryocooler including a forced-flow cooling system. The cooling system also includes at least two cooling pipes for supplying and recovering a cryogen, the at least two cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil. During operation, the cryocooler supplies the cryogen to the at least one superconducting coil via the at least two cooling pipes.

[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 at least one superconducting coil disposed therein. The method includes disposing a cooling system in thermal communication with the at least one superconducting coil. Disposing the cooling system in thermal communication with the at least one superconducting coil includes multiple steps. Specifically, disposing the cooling system includes disposing a cryocooler of the cooling system outside the vacuum vessel. Disposing the cooling system also includes thermally coupling at least two cooling pipes between the cryocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system. The method also includes, once the cooling system is disposed, operating the cooling system to supply cryogen to the at least one superconducting coil via the at least two cooling pipes.

[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.

[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 this specification, which makes reference to the accompanying figures. [Brief explanation of the drawings]

[0027] [Figure 1] 1 shows a perspective view of an embodiment of a wind turbine having a generator according to the present disclosure. [Figure 2] 1 illustrates a perspective internal view of one embodiment of a nacelle of a wind turbine having a superconducting generator according to the present disclosure. [Figure 3] 1 shows a side view of a superconducting generator according to an aspect of the present invention. [Figure 4] 1 shows a simplified schematic diagram of a superconducting generator of conventional construction, particularly showing the cooling system disposed with the generator's thermal shield. [Figure 5] 1 shows a simplified schematic diagram of a forced-flow cooling system according to the present disclosure. [Figure 6] 6 shows a simplified schematic diagram of the forced-flow cooling system of FIG. 5 deployed with a superconducting generator according to the present disclosure. [Figure 7] 1 illustrates a side view of a superconducting generator, particularly showing the arrangement of torque transmission components, coil support structure, and cooling tubes in accordance with the present disclosure. [Figure 8] 1 illustrates a radial view of the interior of a coil support structure, particularly showing the placement of cooling tubes, in accordance with the present disclosure. [Figure 9] 10 illustrates an internal radial view of a coil support structure, particularly illustrating another arrangement of cooling tubes, in accordance with the present disclosure. [Figure 10] 10 illustrates a radially outward view of the coil support structure, particularly illustrating another arrangement of cooling tubes in accordance with the present disclosure. [Figure 11] 1 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of torque transfer components, coil support structures, and cooling tubes in accordance with the present disclosure. [Figure 12A] 1 illustrates one embodiment of a fastener configured to assemble torque transfer components and secure the torque transfer components to a coil support structure according to the present disclosure. [Figure 12B] 10 illustrates another embodiment of a fastener configured to assemble torque transfer components and secure the torque transfer components to a coil support structure according to the present disclosure. [Figure 13] 1 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of torque transfer components, coil support structures, and cooling tubes in accordance with the present disclosure. [Figure 14] 1 illustrates a detailed view of a torque transmitting component disk according to the present disclosure. [Figure 15] 1 illustrates a side view of a superconducting generator, particularly illustrating another arrangement of torque transfer components, coil support structures, and cooling tubes in accordance with the present disclosure. [Figure 16] 1 provides a flow diagram illustrating a method for cooling a superconducting generator according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0028] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.

[0029] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided as an illustration of the invention, not as a limitation of the invention. Indeed, 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 example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a still further embodiment. It is therefore intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

[0030] Terms such as "coupled," "fixed," and "attached" refer to both direct coupling, fixing, or attachment, and indirect coupling, fixing, or attachment through one or more intermediate components or features, unless otherwise specified herein.

[0031] Superconducting machines are a type of electric machine that rely on the properties exhibited by superconducting materials, such as superconducting generators. Such generators also have low reactance when fabricated in an "air-core" configuration. Specifically, due to the high magnetic fields generated by superconductors, "air-core" configuration occurs when most of the magnetic material, such as iron, is removed from the armature and field. If the magnetic material is not removed, the high magnetic fields generated by the superconductors can saturate the magnetic material. Therefore, removing the magnetic material reduces the generator reactance.

[0032] Additionally, superconducting materials exhibit a different set of physical and electrical properties when cooled below a certain temperature, called the "critical temperature." In the field of superconducting electric machines, superconducting materials are selected to form the superconducting coils for superconducting electric machines because the properties of the superconducting material and coil allow electrical current to flow without energy loss once the coil's temperature is below the critical temperature of the respective material. This property allows the superconducting machine to operate at higher efficiencies and in 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 coil remains below its critical temperature.

[0033] Conventional cooling systems for superconducting machines or generators operate by passive cooling systems such as pool boiling or thermosiphons. Pool boiling is a form of cooling in which superconducting coils are immersed in a bath of coolant, which removes thermal energy from the operating superconducting coils. Thermosiphons operate by gravity driving the cooler, heavier coolant at the top of the generator to the bottom. Heat generated within the fluid as it passes through the superconductor and cools it causes the hotter, lighter fluid to rise to the top again when it reaches the bottom of the generator, where the cooler cools it again, repeating the cycle. For cooling down to the operating temperature of liquid helium (4.2 K), Gifford-McMahon cycle coolers are the standard for cooling fluids in smaller applications such as MRI (magnetic resonance imaging).

[0034] For example, referring now to the drawings, Figures 1-4 illustrate conventional passive cooling systems for generators housed within wind turbines. For example, Figure 1 illustrates a perspective view of a wind turbine having a generator. Figure 2 illustrates an internal view of a wind turbine nacelle having a superconducting generator. Figure 3 illustrates a side view of a conventional superconducting generator. Figure 4 illustrates a simplified schematic diagram of a superconducting generator of conventional construction, particularly illustrating the cooling system disposed with the generator's thermal shield.

[0035] More specifically, referring now to FIG. 1 , a perspective view of one embodiment of a wind turbine 10 is shown. 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 outward from the hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in alternative embodiments, the rotor 18 may include more or fewer than three rotor blades 22. Each rotor blade 22 may be spaced about the hub 20 to facilitate rotation of the rotor 18 so that kinetic energy from the wind can be converted into usable mechanical energy and, subsequently, electrical energy. For example, the hub 20 may be rotatably coupled to a generator (not shown) positioned within the nacelle 16 to generate electrical energy.

[0036] 2, a perspective interior view of one embodiment of nacelle 16 having a superconducting generator 23 therein in accordance with the present disclosure is shown. Additionally, as shown, support tube 41 is directly connected to hub 20 and supports armature winding assembly 24. Armature winding assembly 24 is therefore considered a rotating component of generator 23, having a rotating first electromagnetic component configuration that rotates adjacent to stationary field assembly 26 having a second electromagnetic component configuration, such as superconducting field winding assembly 26.

[0037] The stationary field assembly 26 includes superconducting coils 52, which may be a group of wires formed into a racetrack shape. Thus, in certain embodiments, the superconducting coils 52 are constrained to maintain the racetrack shape. Further, as shown, each superconducting coil 52 is supported within a recess / passage 50 within the casing 42, which may be conduction 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. Thus, the casing 42 may be supported within a cryostat housing 36, also referred to herein as a vacuum vessel, which is secured to the base tube 44.

[0038] 2, the superconducting coils 52 may be arranged side-by-side in an annular array extending around the casing 42. For example, in one embodiment, 36 coils may form an annular array of field windings that function as the stator field windings of the generator 23. Furthermore, in one embodiment, the superconducting coils 52 may each be formed of wire (NbTi or other superconducting material) wrapped in a helical path around a racetrack configuration that may include a cooling conduit for the cryogen. The stationary field assembly 26 includes superconducting coil magnets 54 formed by passing an electric current through the superconducting field coils 52, which are enclosed within the casing 42 and receive the cryogen via cooling recesses / passages 50.

[0039] In additional embodiments, the cryogen recondensers 38, 40 may be housed within the field coil assembly 26, provided that the cryogen coolant in the recondensers 38, 40 is at least partially raised above the superconducting field windings to provide gravity feed of the cryogen to the windings. Alternatively, the recondensers 38, 40 may be mounted on top of the field coil assembly.

[0040] Referring now to FIG. 3 , a cross section of one embodiment of a direct drive superconducting generator 23 is shown in which an annular rotating armature winding assembly 24 (“armature 24”) is radially inward of a stationary field assembly 26. It should be understood that the disclosure described herein can also function with an armature winding assembly 24 positioned radially outward of the stationary field assembly 26. 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 conducting coils 52, e.g., coils or bars, arranged on the inner cylindrical surface of the armature 24 longitudinally along the length of the armature 24. The conducting coils 52 may be connected to each other at their ends by conductive end turns 28. The number and arrangement of end turns 28 between the longitudinal conducting coils 52 depends on the number and arrangement, as well as the phase of the electricity generated in the conducting coils 52. The outer cylindrical surface of the armature winding is separated from the inner surface of the fixed field assembly 26 by a narrow air gap, for example, about 10-25 mm.

[0041] Referring generally to FIG. 3 , the armature 24 includes a cylindrical yoke or body 30 (referred to herein as “body”) that supports a conducting coil 52. In particular, the conducting coil 52 is housed within slots defined between adjacent teeth extending radially from the body 30. The body 30 and 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. Further, as shown, the stationary field winding assembly 26 may be supported by a field winding support disk 34. Furthermore, the field winding support disk 34 is attached to the end of a cryostat housing 36 that houses the superconducting coil 52 ( FIG. 2 ) of the field winding assembly 26. The housing 36 and its cooling components form a cryostat that cools the superconducting coil of the field winding.

[0042] The cryostat housing 36 insulates the superconducting coil 52 so that it can be cooled to near absolute zero, e.g., 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 for receiving liquid helium (He) or other similar cryogenic liquids, such as liquid neon (Ne) or liquid hydrogen (H) (referred to as a 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, and above the field windings to provide a cryogen, e.g., liquid He, using gravity feed. A second recondenser 40 may supply a second cooling liquid, e.g., liquid nitrogen or neon, to the inner thermal shield of the cryostat housing 36 via conduit 48.

[0043] Referring now to FIG. 4 , various components of a simplified cooling system 102 schematic diagram for a superconducting generator 100 of conventional construction are shown. More specifically, as shown, the superconducting generator 100 generally includes the cooling system 102 arranged with the generator's 100 thermal shield 104, vacuum vessel 106, cold mass 108, and cryocooler 110. 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 the armature winding assembly annulus, shown in FIG. 3 , has been omitted from FIGS. 4-9 for purposes of simplifying the illustration and more clearly illustrating the details of the present disclosure. Further, by way of example, the vacuum vessel 106 may be a non-rotating component that supports a field winding assembly, such as the stationary field assembly 26.

[0044] Thus, in such embodiments, the rotatable components may be oriented to rotate relative to the non-rotating components during operation of the generator 100, as shown in FIG. 3. In such conventional configurations, the thermal shield 104 blocks and / or blocks radiation from the vacuum vessel 106 (as indicated by arrows 114). Further, as shown, heat is removed via the thermal bus / bus bar 112 toward the cryocooler 110, thereby blocking most of the radiant heat from the cold mass 108. Further, as shown, the thermal bus / bus bar 112 in such configuration is attached to the top of the thermal shield 104 for connection to the cryocooler 110. The thermal shield 104 also blocks heat conducted through structural components, such as those used to hold the stationary field assembly 26 in place.

[0045] However, each of these types of passive cooling systems (e.g., thermosyphon coolers or pool boilers) described with reference to Figures 1-4 is limited in the amount of cooling power it can provide as a result of relying on passive cooling means. Furthermore, each of these types of passive cooling systems requires the use of numerous parts that are difficult to manufacture and assemble, and consequently costly.

[0046] Accordingly, the present disclosure is generally directed to superconducting machines that utilize forced-flow cooling systems for cooling superconducting coils disposed therein, as opposed to passive cooling means. Furthermore, superconducting machines may include architectures that exploit the benefits provided by using forced-flow cooling. For example, cooling tubes for cooling superconducting coils may be provided in specific and more general orientations, independent of the direction of gravity. Means and methods may be provided to address torsional forces generated by superconducting coils. Specifically, torque transmission components may be provided to address motion generated by opposing magnetic fields within the superconducting machine or the initial contraction and expansion of the superconducting coils during operation. Cooling systems may also enable the use of various types of electrical components with superconducting machines that were not possible with passively cooled superconducting machines. For example, a superconducting machine may be provided with an armature having windings not previously implemented therein.

[0047] By providing a superconducting machine having any one of these aforementioned features, the overall efficiency of the superconducting machine may be improved, while also reducing the overall cost of manufacturing and operating such a machine.

[0048] Furthermore, utilizing a forced-flow cooling system can provide various advantages. For example, cooling power and heat removal can be variable and optimized for the superconducting machine being operated. Furthermore, the flow of cooling power can be directed specifically to desired locations with minimal flow maldistribution. Furthermore, the flow of cooling power can be maintained continuously without any interruptions to heat transfer. Furthermore, a forced-flow cooling system does not require any specific requirements for the internal environment within the superconducting machine, such as pressure levels, to utilize the cooling system.

[0049] Superconducting machines may be used with the features described with reference to Figures 1-4 while still providing the benefits of utilizing a forced-flow cooling system. For example, the present disclosure is directed to superconducting machines that are particularly well-suited for use in wind turbines 10 (Figure 1), although the present disclosure is not limited to such use. Furthermore, while Figure 1 illustrates an "onshore" (land-based) wind turbine 10 installation, it should be understood that the present invention is not limited to onshore wind turbines, but is equally applicable to "offshore" (water-based) wind turbine installations having fixed or floating foundations, with larger generators generally benefiting more from forced-flow cooling.

[0050] With particular reference to FIG. 5, a simplified schematic diagram of a forced-flow cooling system 200 according to the present disclosure is shown. More specifically, as shown, the depicted forced-flow cooling system 200 demonstrates the means by which thermal energy may be transferred with reference to a superconducting machine as presently disclosed. Specifically, a reverse Brayton cryocooling system (also known as gas refrigeration or a Bell-Coleman cycle or Joule cycle, which is closely related to a Claude cycle or Linde cycle) is shown. However, other forced-flow cooling systems may also be included.

[0051] Further, in one 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 transfers thermal energy Q away from cold reservoir 202 and to hot reservoir 204. In particular, forced-flow cooling system 200 transfers thermal energy Q from cold reservoir 202 into first heat exchanger 206, through second heat exchanger 208, and from there into hot reservoir 204. This transfer of thermal energy Q is accomplished through the use of turbine compressor 210 and thermal path 212. Further, in one embodiment, turbine compressor 210 exerts work W on cooling system 200 sufficient to drive thermal energy Q from first heat exchanger 206 to second heat exchanger 208. The thermal pathway 212 allows thermal energy Q to be transferred from the first heat exchanger 206 to the second heat exchanger 208. Such a process is described in more detail below with reference to Figures 6-16.

[0052] 6, a simplified schematic diagram of one embodiment of a forced-flow cooling system 306 disposed with a superconducting generator is shown. 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 304 is disposed within the vacuum vessel 302. Furthermore, the cooling system 306 cools the superconducting coil 304.

[0053] Vacuum vessel 302 may be similar to and include the features of vacuum vessel 106 described with reference to Figure 4. For example, vacuum vessel 302 may house each of the electrical components of superconducting generator 300, such as superconducting coil 304. Vacuum vessel 302 may also function as a thermal barrier for superconducting coil 304. Additionally, superconducting coil 304 may be similar to superconducting coil 52 or field assembly 26 and may include the same features, such as the shape, orientation, or material from which coil 52 is formed.

[0054] 6 , the cooling system 306 may further include a cryocooler 308 and at least two cooling pipes 310 for supplying and recovering a cryogen. The cryocooler 308 may be mounted on or around the exterior of the vacuum vessel 302. As described above, the cryocooler 308 is a forced-flow cooling system, such as a reverse Brayton cryocooling system. The cooling pipes 310 may be thermally coupled between the cryocooler 308 and the superconducting coil 304. Furthermore, the cryocooler 308 may supply a coolant, cryogen, or cryogenic cooling fluid to the superconducting coil 304 via the cooling pipes 310.

[0055] 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 transmission component 312, a thermal layer 314, and an armature 316. The torque transmission component 312 may be provided to secure the superconducting coil 304 in place while the superconducting coil 304 is operated. The thermal layer 314 may provide additional insulation for the superconducting coil 304, if necessary. An additional advantage of forced cooling at higher cooling powers is that the thermal layer 314 does not need to be cooled separately, as is the case with all Gifford-McMahon and pool boiling systems, to reach 4 K cold mass operation. The armature 316 may provide a magnetic field that counteracts the magnetic field provided by the superconducting coil 304. The armature 316 may be disposed with the vacuum vessel 302. Additionally, the armature 316 may be configured to rotate within the magnetic field generated by the superconducting coil 304. Armature 316 may include features of armature 24, such as armature windings. However, armature 316 may also include features different from armature 24. For example, armature 316 may include at least one of hybrid Gramm windings or fractional-slot windings. These types of winding / armature topologies were previously not possible due to the insufficient amount of cooling power provided by passive cooling systems for superconducting generators due to eddy current heating of the field by the armature windings. However, the cooling system of the present disclosure provides sufficient cooling power so that hybrid Gramm windings or fractional-slot windings may now be achievable.

[0056] Each of the components of superconducting generator 300 is described in more detail below with reference to FIGS.

[0057] 7, a side view of superconducting generator 300 is shown, particularly illustrating the arrangement of torque transfer components 312, coil support structure 320, and cooling tubes 310. As shown, torque transfer components 312 are disposed within vacuum vessel 302. In particular, torque transfer components 312 may be secured to the interior wall of vacuum vessel 302 and to superconducting coils 304, thereby securing superconducting coils 304 in place.

[0058] In certain embodiments, as shown, torque transmission component 312 may include torque tube 318. While torque tube 318 is described as a tube, torque tube 318 may take on a variety of other non-cylindrical or non-tubular shapes. As particularly shown in FIG. 7 , for example, torque tube 318 may be affixed to opposite sides of vacuum vessel 302. Such an orientation allows torque tube 318 to equally distribute mechanical forces it withstands (such as forces resulting from the expansion of superconducting coil 304 or forces resulting from the magnetic field generated by superconducting coil 304) to both sides of vacuum vessel 302.

[0059] Further, as shown, torque tube 318 may extend in a particular direction. For example, torque tube 318 may extend radially relative to generator axis 319 of superconducting generator 300. Alternatively, torque tube 318 may extend axially relative to generator axis 319 of superconducting generator 300. Particular portions of torque tube 318 may also extend in various manners. For example, one portion of torque tube 318 may extend radially, while another portion extends axially. Further, as shown, cooling tube 310 may also be provided within torque tube 318. By doing so, torque transfer component 312 may be cooled along with superconducting coil 304. Particular embodiments of the orientation of torque transfer component 312 and torque tube 318 are described in more detail with reference to FIGS. 11-16 .

[0060] Continuing to refer to FIG. 7 , the superconducting generator 300 may also include a coil support structure 320. As shown, the superconducting coil 304 may be disposed within the coil support structure 320. The coil support structure 320 may be constructed of various materials. For example, the coil structure 320 may be constructed of at least one of a metal, a metal alloy, or a composite. In an exemplary embodiment, the coil support structure 320 may be constructed of stainless steel. Using stainless steel to construct the coil support structure 320 may provide greater strength to accommodate the superconducting coil 304.

[0061] Additionally, cooling tubes 310 may be disposed within coil support structure 320, thereby providing direct cooling to superconducting coil 304. For example, a portion of cooling tube 310 may be disposed within coil support structure 320, or the portion of cooling tube 310 disposed within coil support structure 320 may be wrapped around at least a portion of superconducting coil 304. Particular embodiments of the positioning of cooling tube 310 relative to coil support structure 320 are described in more detail with reference to FIGS.

[0062] As described above with reference to FIG. 6 , the superconducting generator 300 may also include a thermal layer 314. In contrast to conventional superconducting generators that 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 from one or more coating layers. For example, the coating layer may be a multi-layer insulation (MLI) formed from multiple layers of thin sheets of material. In certain embodiments, the coating layer may also be a sprayed or applied coating as needed. The material used to construct the thermal layer 314 may be at least one metal foil segment. The coating layer, when selected, is positioned on at least one of the torque-transmitting component 312 or the coil support structure 320. The use of the thermal layer 314 reduces the thermal load on the superconducting coil. Additionally, the overall weight of the superconducting generator 300 may be reduced, which is particularly beneficial when the superconducting generator 300 is located in an elevated location, such as within a wind turbine. This weight reduction is achieved by replacing a conventional thermal shield with the lighter thermal layer 314. Such a replacement is made possible by the increased cooling power provided by the use of the forced-flow cooling system 200 within the superconducting generator 300 .

[0063] In a further embodiment, as shown in Figure 7, torque transfer component 312 may also include a torque disc 322 and a torque tube holder 324. As shown, torque disc 322 may be secured to coil support structure 320 by at least one fastener 326. Additionally, torque tube holder 324 may be configured to secure torque tube 318 to coil support structure 320 (Figure 7) and / or torque disc 322. Torque disc 322 and torque tube holder 324 are described in more detail with reference to Figures 12A-12B and 14-15.

[0064] Additionally, each of the components of torque transfer component 312 may be made from a particular material. For example, torque tube 318, torque disc 322, and torque tube holder 324 may be formed from a metal or metal alloy such as Inconel® steel.

[0065] 8-10, various orientations and positioning of the cooling tubes are illustrated. As shown in FIG. 8, an internal top view of one embodiment of the coil support structure 320 is illustrated. In particular, as shown, the cooling tube 310 includes a first cooling tube 328 and a second cooling tube 330. Similar to the cooling tube 310, the first and second cooling tubes 328, 330 are thermally coupled between the cryocooler 308 and the superconducting coil 304. Furthermore, the first cooling tube 328 may be positioned on one side of the superconducting coil 304, and the second cooling tube 330 may be positioned on another, opposite side of the superconducting coil 304. Specifically, in the exemplary embodiment, the first and second cooling tubes 328, 330 are shown positioned along the shorter curved portions of the racetrack shape of the superconducting coil 304. However, the first and second cooling pipes 328, 330 may also be positioned on a long straight portion of the racetrack shape of the superconducting coil 304. The first and second cooling pipes 328, 330 may be connected to the same cryocooler 308. Alternatively, the first and second cooling pipes 328, 330 may be connected to two separate cryocoolers 308.

[0066] 9, an internal top view of another embodiment of the coil support structure 320 is shown, particularly illustrating another arrangement of the cooling tubes 310. In particular, as shown, the cooling tubes 310 are positioned along both the longer straight portions and one of the shorter curved portions of the racetrack shape of the superconducting coil 304. Providing the cooling tubes 310 along the longer lengths of the superconducting coil 304 may enable a greater amount of cooling power to be delivered to the superconducting coil 304.

[0067] 10 , an internal view of yet another embodiment of a coil support structure 320 is shown, particularly illustrating yet another arrangement of cooling pipes 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 the cover plate 332 is provided, the cooling pipes 310 may be secured to the inner surface 331 of the cover plate 332. Furthermore, the cooling pipes 310 may be secured in a variety of ways. For example, the cooling pipes 310 may be secured in a manner similar to the embodiment shown in FIGS. 8-9 . Alternatively, the cooling pipes 310 may be secured in a zigzag pattern, thereby covering a larger area of ​​the coil support structure 320 and providing a larger amount of cooling power to the superconducting coil 304.

[0068] 11 , a side view of another embodiment of superconducting generator 300 is shown, particularly illustrating an alternative arrangement of torque transfer components 312, coil support structure 320, and cooling tubes 310. As shown, torque tube 318 may be a cantilevered component fixed to the interior wall of vacuum vessel 302. Cantilevering torque tube 318 may allow torque tube 318 to compensate for mechanical forces applied by torque transfer components 312. For example, if superconducting coil 304 contracts during operation, cantilevering torque tube 318 may allow torque tube 318 to flex to compensate for movement resulting from the contraction.

[0069] 12A-12B, various embodiments of fasteners configured to assemble torque transfer component 312 and secure torque transfer component 312 to coil support structure 320 are shown. As shown in FIG. 12A, fasteners 326 may be utilized to secure torque tube 318 or coil support structure 320. Torque tube 318 may be secured to various components within superconducting generator 300. For example, fasteners 326 may secure torque tube 318 to torque disk 322, as shown in FIG. 12B. Fasteners 326 may also secure torque tube 318 to coil support structure 320 (FIGS. 7, 11, and 14-16). Fasteners 326 may also secure torque tube 318 to torque tube holder 324 (FIG. 11). Additionally, as shown in FIG. 12B, a spring 334 may be positioned around fastener 326. Providing spring 334 may allow torque transmission component 312 to better account for mechanical forces. For example, if compression occurs along fastener 326 as a result of operation of superconducting generator 300, spring 334 may be able to accommodate the compression without causing deformation of fastener 326.

[0070] 13, a side view of another embodiment of superconducting generator 300 is shown, illustrating, among other things, an alternative arrangement of torque transfer components 312, coil support structure 320, and cooling tubes 310. In particular, torque tube holder 324 may be positioned in various locations. For example, torque tube holder 324 may be positioned toward the center of coil support structure 320.

[0071] 13 further illustrates a thermal path 336 through which thermal energy travels throughout superconducting generator 300. As shown, thermal path 336 begins at superconducting coil 304 and travels through coil support structure 320 and torque tube holder 324 to torque tube 318. The thermal energy then travels outward along torque tube 318 where it reaches vacuum vessel 302. By positioning cooling tube 310 along this path (e.g., within torque tube 318 or within coil support structure 320), the overall efficiency of cooling of superconducting generator 300 may be increased.

[0072] 14 , there is shown a detailed view of one embodiment of torque transfer component disk 322. As shown, torque disk 322 may include a number of fasteners 326 for securing torque disk 322 to either torque tube 318, coil support structure 320, or torque tube holder 324. By locating cooling tubes 310 within torque disk 322, the overall cooling efficiency of superconducting generator 300 may be increased.

[0073] 15 , a side view of one embodiment of a superconducting generator 300 is shown, particularly illustrating an alternative arrangement of torque transmission components 312, coil support structure 320, and cooling tubes 310. As shown, cooling tubes 310 may be positioned throughout superconducting generator 300. For example, cooling tubes 310 may be positioned along multiple portions of torque tube 318.

[0074] Additionally, different types of cooling may be used. For example, if multiple cooling pipes 310 are used, the cooling pipes 310 may be of different types. In particular, at least one of the cooling pipes 310 may be connected to the forced-flow cooling system 200, while another of the cooling pipes 310 may be connected to a different cooling means. For example, the cooling means may be a gas tank 338 that provides passive cooling in addition to the active cooling provided by the forced-flow cooling system 200.

[0075] Referring generally to Figure 16, a flow diagram of one embodiment of a method for cooling a superconducting generator is shown. While Figure 16 depicts steps performed in a particular order for purposes of illustration and explanation, the methods described herein are not limited to any particular order or arrangement. Those skilled in the art will understand, using the disclosure provided herein, that various steps of the methods can be omitted, rearranged, combined, and / or adapted in various ways.

[0076] Method 400 includes placing a cooling system in thermal communication with at least one superconducting coil, as shown at (402). Specifically, placing the cooling system in thermal communication with the at least one superconducting coil may include multiple steps. For example, method 400 may include placing a cryocooler of the cooling system outside of a vacuum vessel, as shown at (404). Method 400 may also include thermally coupling at least two cooling pipes between the cryocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system, as shown at (406). Once the cooling system is provided, method 400 may also include operating the cooling system to supply a cryogen or cryogenic cooling fluid to the at least one superconducting coil via the at least two cooling pipes, as shown at (408).

[0077] 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 to each such method and feature, can be mixed and matched by those skilled in the art to construct additional systems and techniques in accordance with the principles of the present disclosure. Of course, it should be understood that not all such objects or advantages described above may necessarily 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 performed in a manner that achieves or optimizes one advantage or group of advantages taught herein without necessarily achieving other objects or advantages that may be taught or suggested herein.

[0078] Further aspects of the invention are provided by the subject matter of the following clauses. Clause 1. A vacuum vessel; at least one superconducting coil disposed within the vacuum vessel; a cooling system for cooling the at least one superconducting coil, the cooling system comprising: a torque transmission component fixed to an inner wall of the vacuum vessel, wherein at least one superconducting coil is fixed to the torque transmission component; a cryocooler external to the vacuum vessel, the cryocooler comprising a forced-flow cooling system; at least two cooling pipes for supplying and recovering a cryogen, the at least two cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil, and the cryocooler supplies the cryogen to the at least one superconducting coil via the at least two cooling pipes; Superconducting machines. 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 clause 1 or 2, wherein the torque transmission component is configured to secure at least one superconducting coil in position, the torque transmission component comprising a torque tube. Clause 4. A superconducting machine as described in clause 3, wherein the torque tubes are fixed to opposite sides of the vacuum vessel. Clause 5. A superconducting machine according to clause 3 or 4, wherein the torque tube extends radially relative to the superconducting machine. Clause 6. A superconducting machine according to any one of clauses 3 to 5, wherein the torque tube extends axially or circumferentially relative to the superconducting machine. Clause 7. A superconducting machine according to clause 3, 5 or 6, wherein the torque tube is a cantilevered component fixed to the inner wall of the vacuum vessel. Clause 8. A superconducting machine according to any one of clauses 3 to 7, wherein the cooling system further comprises a coil support structure, and wherein the at least one superconducting coil is disposed within the coil support structure. Clause 9. A superconducting machine as described in clause 8, wherein the coil support structure is constructed of at least one of a metal or a metal alloy or a metal-added material or a composite. Clause 10. A superconducting machine as described in clause 8 or 9, wherein a portion of one of the at least two cooling pipes is disposed within the coil support structure, and the portion of the cooling pipe disposed within the coil support structure is wound around at least a portion of the at least one superconducting coil. Clause 11. A superconducting machine as described in any of clauses 8 to 10, wherein the coil support structure further comprises a cover plate having an inner surface and an outer surface, and at least one of the at least two cooling pipes is fixed to the inner surface of the cover plate. Clause 12. A superconducting machine as described in any of clauses 8 to 11, wherein the torque transmission component further comprises a torque disk and a torque tube holder, the torque disk being secured to the coil support structure via at least one fastener, and the torque tube holder being 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 positioned about the at least one fastener. Clause 14. A superconducting machine according to any of clauses 8 to 13, further comprising a thermal layer, the thermal layer comprising a coating formed of one or more coating layers, the one or more coating layers being positioned on at least one of the torque transmission 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 pipes comprise a first cooling pipe and a second cooling pipe, the first and second cooling pipes being 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 disposed with the vacuum vessel, the armature configured to rotate within a magnetic field generated by the at least one superconducting coil, the armature comprising a winding, the winding comprising at least one of a hybrid Graham 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 transmission component fixed to an inner wall of a vacuum vessel of the superconducting machine, the at least one superconducting coil being fixed to the torque transmission component; a cryocooler having a forced-flow cooling system; at least two cooling pipes for supplying and recovering a cryogen, the at least two cooling pipes being thermally coupled between the cryocooler and the at least one superconducting coil, and the cryocooler supplies the cryogen to the at least one superconducting coil via the at least two cooling pipes; Cooling system. Clause 18. The cooling system of clause 17, wherein the forced flow cooling system comprises a reverse Brayton cryocooling system. Clause 19. A cooling system as described in clause 17 or 18, wherein the at least two cooling pipes comprise a first cooling pipe and a second cooling pipe, and the first and second cooling pipes are 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 at least one superconducting coil disposed therein, the method comprising: placing a cooling system in thermal communication with the at least one superconducting coil, locating the cryocooler of the cooling system outside the vacuum vessel; and disposing at least two cooling pipes thermally coupling between a cryocooler and the at least one superconducting coil, the cryocooler having a forced-flow cooling system; operating a cooling system to supply cryogen to the at least one superconducting coil through at least two cooling pipes; A method comprising:

[0079] This specification 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 related 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 contain structural elements that do not differ from the literal language of the claims, or if they contain equivalent structural elements that have no substantial difference from the literal language of the claims. [Explanation of symbols]

[0080] 10. Wind Turbines 12. Tower 14 Support surface 16 Nacelle 18 rotors 20 rotatable hubs 22 rotor blades 23 Direct-drive superconducting generator 24 Armature winding assembly, armature 26 Superconducting field winding assembly, fixed field assembly, field coil assembly 28 Conductive End Turns 30 Main Unit 32 Housing 34 Field winding support disk 36 Cryostat housing 38 Cryogenic recondenser, two-stage recondenser 40 Cryogen recondenser, second recondenser 41 Support pipe 42 Casing 44 bass tube 46 Insulated duct 48 Conduit 50 Cooling recesses / passages 52 Superconducting coils, superconducting field coils, conducting coils 54 Superconducting Coil Magnet 100 Superconducting Generator 102 Cooling System 104 Thermal Shield 106 Vacuum container 108 Cold Mass 110 Cryocooler 112 Thermal Bus / Bus Bar 114 Arrow 200 Forced Flow Cooling System 202 Low Temperature Reservoir 204 High Temperature Reservoir 206 First Heat Exchanger 208 Second Heat Exchanger 210 Turbine Compressor 212 Heat Path 300 Superconducting Generator 302 Vacuum container 304 at least one superconducting coil 306 Forced Flow Cooling System 308 Cryocooler 310 At least two cooling channels 312 Torque Transmission Components 314 Thermal Layer 316 Armature 318 Torque Tube 319 Generator axis 320 Coil support structure, coil structure 322 Torque disc, torque transmission component disc 324 Torque Tube Holder 326 At least one fastener 328 First Cooling Pipe 330 Second Cooling Pipe 331 Inside 332 Cover Plate 333 Exterior 334 Spring 336 Heat Path 338 Gas Tank 400 ways 402 Placement 404 Placement 406 Thermal Bonding 408 Supply Q Thermal Energy Double Work

Claims

1. a vacuum vessel (302); at least one superconducting coil (304) disposed within the vacuum vessel (302); a cooling system (306) for cooling the at least one superconducting coil (304), wherein the cooling system (306) comprises: a torque transmission component (312) fixed to an inner wall of the vacuum vessel (302), the at least one superconducting coil (304) being fixed to the torque transmission component (312); a cryocooler (308) outside the vacuum vessel (302), the cryocooler (308) comprising a forced-flow cooling system; and at least two cooling pipes (310) for supplying and recovering a cryogen, the at least two cooling pipes (310) being thermally coupled between the cryocooler (308) and the at least one superconducting coil (304), wherein the cryocooler (308) supplies a cryogen to the at least one superconducting coil (304) via the at least two cooling pipes (310). Superconducting machines.

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

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

4. The superconducting machine of claim 3, wherein the torque tubes (318) are secured to opposite sides of the vacuum vessel (302).

5. The superconducting machine of claim 3 , wherein the torque tube (318) extends radially relative to the superconducting machine.

6. The superconducting machine of claim 3, wherein the torque tube (318) extends axially or circumferentially relative to the superconducting machine.

7. The superconducting machine of claim 3, wherein the torque tube (318) is a cantilevered component fixed to the interior wall of the vacuum vessel (302).

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

9. The superconducting machine of claim 8, wherein the coil support structure (320) is constructed from at least one of a metal, a metal alloy, a metal additive material, or a composite.

10. 9. The superconducting machine of claim 8, wherein a portion of one of the at least two cooling pipes (310) is disposed within the coil support structure (320), and the portion of the cooling pipe disposed within the coil support structure (320) is wrapped around at least a portion of the at least one superconducting coil (304).

11. 9. The superconducting machine of claim 8, wherein the coil support structure (320) further comprises a cover plate (332) having an inner surface (331) and an outer surface (333), and at least one of the at least two cooling pipes (310) is fixed to the inner surface (331) of the cover plate (332).

12. 10. The superconducting machine of claim 8, wherein the torque transmission component further comprises a torque disk and a torque tube holder, the torque disk secured to the coil support structure via at least one fastener, and 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 (334) positioned about the at least one fastener (326).

14. 10. The superconducting machine of claim 8, further comprising a thermal layer (314), the thermal layer (314) comprising a coating formed of one or more coating layers, the one or more coating layers positioned on at least one of the torque transmitting component (312), the coil support structure (320), or the at least two superconducting coils.

15. 2. The superconducting machine of claim 1, wherein the at least two cooling pipes (310) comprise a first cooling pipe (328) and a second cooling pipe (330), the first and second cooling pipes (328, 330) being thermally coupled between the cryocooler (308) and the at least one superconducting coil (304).

16. 10. The superconducting machine of claim 1, further comprising an armature (316) disposed with the vacuum vessel (302), the armature (316) configured to rotate within a magnetic field generated by the at least one superconducting coil (304), the armature (316) comprising windings, the windings comprising at least one of hybrid Graham windings or fractional slot windings.

17. A cooling system (306) for cooling at least one superconducting coil (304) of a superconducting machine, said cooling system (306) comprising: a torque transmission component (312) fixed to an inner wall of a vacuum vessel (302) of the superconducting machine, the at least one superconducting coil (304) being fixed to the torque transmission component (312); a cryocooler (308) with a forced-flow cooling system; and at least two cooling pipes (310) for supplying and recovering a cryogen, the at least two cooling pipes (310) being thermally coupled between the cryocooler (308) and the at least one superconducting coil (304), wherein the cryocooler (308) supplies a cryogen to the at least one superconducting coil (304) via the at least two cooling pipes (310). A cooling system (306).

18. The cooling system (306) of claim 17, wherein the forced-flow cooling system comprises a reverse Brayton cryocooling system.

19. 18. The cooling system (306) of claim 17, wherein the at least two cooling pipes (310) comprise a first cooling pipe (328) and a second cooling pipe (330), the first and second cooling pipes (328, 330) being thermally coupled between the cryocooler (308) and the at least one superconducting coil (304).

20. 1. A method (400) of cooling at least one superconducting coil (304) of a superconducting machine, the superconducting machine having a vacuum vessel (302) within which the at least one superconducting coil (304) is disposed, the method (400) comprising: Placing (402) a cooling system (306) in thermal communication with the at least one superconducting coil (304), wherein placing (402) the cooling system (306) in thermal communication with the at least one superconducting coil (304) comprises: disposing (404) a cryocooler (308) of the cooling system (306) outside the vacuum vessel (302); and disposing (402) including thermally coupling (406) at least two cooling pipes (310) between the cryocooler (308) and the at least one superconducting coil (304), the cryocooler (308) having a forced-flow cooling system; operating the cooling system (306) to supply (408) cryogen to the at least one superconducting coil (304) via the at least two cooling pipes (310); The method (400) includes:

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