Gas tank cooling for thermal shield of superconducting machine

Abstract

A generator includes a non-rotatable member supporting a field winding assembly and a rotatable member oriented to rotate relative to the non-rotatable member during operation of the generator. Further, the generator includes an armature winding assembly fixedly coupled to the rotatable member for rotation with the rotatable member during operation of the generator. The armature winding assembly includes a plurality of conductive coils. The generator further includes a thermal shield surrounding the field winding assembly fixedly coupled to the stationary member; a cryocooler in thermal contact with the thermal shield; and a gas tank adjacent to and in thermal contact with the thermal shield, the gas tank containing a cooling gas configured to circulate therein so as to provide uniform cooling to the thermal shield.

Description

Technical Field

[0001] The present disclosure relates generally to superconducting machines, and more particularly to a cooling system for cooling a thermal shield of a superconducting machine. Background Art

[0002] Wind turbines have received increasing attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop reliable and efficient wind turbines. Generally, a wind turbine includes a plurality of rotor blades connected to the main shaft of the turbine via a rotor hub. The rotor hub is positioned on top of a tubular tower or base. Utility-grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) may have large rotors (e.g., 100 meters or more in diameter). The rotor blades convert wind energy into a rotational torque or force that drives a generator rotationally coupled to the rotor.

[0003] Low reactance machines (e.g., superconducting generators) are being explored for use in wind turbine installations, particularly in offshore installations. These machines use an assembly of superconducting field windings and armature coils, a cooling system, and non-magnetic teeth disposed between the coils in the armature. In a particular design, the superconducting generator includes an armature winding assembly that, unlike conventional machine (e.g., conventional non-superconducting generator) configurations, rotates within a superconducting field assembly that includes a cryostat with superconducting field coils inside the cryostat.

[0004] Superconducting machines typically also include a cryogenic cooling system for cooling its various components. Accordingly, the art is continually seeking new and improved cooling systems for superconducting generators. Summary of the invention

[0005] 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.

[0006] In one aspect, the present disclosure is directed to a generator comprising a non-rotatable member supporting a field winding assembly and a rotatable member oriented to rotate relative to the non-rotatable member during operation of the generator. In addition, the generator comprises an armature winding assembly fixedly coupled to the rotatable member so as to rotate with the rotatable member during operation of the generator. The armature winding assembly comprises a plurality of conductive coils. The generator further comprises: a heat shield surrounding the field winding assembly fixedly coupled to the stationary member; a cryogenic cooler in thermal contact with the heat shield; and a gas tank adjacent to and in thermal contact with the heat shield, the gas tank containing a cooling gas configured to circulate in the gas tank so as to provide uniform cooling to the heat shield.

[0007] In another aspect, the present disclosure is directed to a cooling system for a superconducting generator. The cooling system includes a heat shield for surrounding a field winding assembly fixedly coupled to a stationary component of the superconducting generator. The stationary component is oriented relative to the rotatable component during operation of the superconducting generator. The cooling system further includes a cryocooler that is in thermal contact with an outer surface of the heat shield via a bus bar. In addition, the cooling system includes a gas tank in thermal contact with the heat shield, the gas tank including a toroidal shape and positioned radially inward of the heat shield on an inner surface of the heat shield, the gas tank containing a cooling gas that is configured to circulate in the gas tank so as to provide uniform cooling to the heat shield.

[0008] 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

[0009] A complete and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0010] Figure 1 illustrates a perspective view of one embodiment of a wind turbine having a generator according to the present disclosure;

[0011] 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;

[0012] Figure 3 illustrates a side view of a generator according to aspects of the present invention;

[0013] Figure 4 illustrates a simplified schematic diagram of a superconducting generator according to conventional construction, particularly illustrating a cooling system arranged in conjunction with a heat shield of the generator;

[0014] Figure 5 A simplified schematic diagram illustrating an embodiment of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating a toroidal gas tank of the cooling system arranged with the heat shield of the generator;

[0015] Figure 6 A perspective view illustrating an embodiment of a toroidal gas tank of a cooling system for a thermal shield of a superconducting generator according to the present disclosure;

[0016] Figure 7A perspective view illustrating an embodiment of a toroidal gas tank of a cooling system for a thermal shield of a superconducting generator according to the present disclosure;

[0017] Figure 8 A perspective view illustrating an embodiment of a securing assembly of a toroidal gas tank of a cooling system for a thermal shield of a superconducting generator according to the present disclosure;

[0018] Fig. 9 A simplified schematic diagram illustrating yet another embodiment of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating a toroidal gas tank of the cooling system, which is arranged together with the heat shield of the generator so that the cooling gas circulates symmetrically in four quadrants of the gas tank;

[0019] Fig.10 A simplified schematic diagram illustrating yet another embodiment of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating a toroidal gas tank of the cooling system, which is arranged together with the heat shield of the generator so that cooling gas circulates in the gas tank in a single loop;

[0020] Fig.11 A simplified schematic diagram illustrating another embodiment of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating a toroidal gas tank of the cooling system, which is arranged together with the heat shield of the generator so that cooling gas circulates in the gas tank in a single loop;

[0021] Fig.12 An internal perspective view illustrating another embodiment of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating a toroidal gas tank of the cooling system integrated with the heat shield of the generator;

[0022] Fig.13 illustrates a detailed internal view of a toroidal gas tank of a cooling system for a thermal shield of a superconducting generator according to the present disclosure, and in particular illustrates the toroidal gas tank of the cooling system integrated with the thermal shield of the generator;

[0023] Fig.14 A partial perspective view illustrating an embodiment of a toroidal gas tank of a cooling system for a thermal shield of a superconducting generator according to the present disclosure;

[0024] Fig.15 Graphics Fig.14 A detailed partial view of the torus gas tank;

[0025] FIG. 16A to FIG. 16D illustrates an example cross-sectional shape of a toroidal gas tank of a cooling system for a thermal shield of a superconducting generator according to the present disclosure;

[0026] Fig.17A cross-sectional view illustrating an embodiment of a toroidal gas tank of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating the toroidal gas tank integrated at an edge of the heat shield of the generator; and

[0027] Fig.18 A cross-sectional view illustrating another embodiment of a toroidal gas tank of a cooling system for a heat shield of a superconducting generator according to the present disclosure, and in particular illustrating the toroidal gas tank welded to an inner surface of the heat shield.

[0028] 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

[0029] 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 rather than by way of 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, a feature illustrated or described as part of an embodiment may be used together with another embodiment to produce yet another additional 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.

[0030] The terms "coupled," "fixed," "attached to," and the like 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.

[0031] Conventional heat shields in superconducting generators have a large temperature differential around the circumference of the shield, which reduces the effectiveness of blocking radiated heat reaching the cold mass that the shield is intended to protect. This is because cooling of the heat shield occurs at the top of the heat shield, while thermal energy (radiated and conducted) enters the heat shield around the circumference.

[0032] Thus, the present disclosure is generally directed to a cooling system for a thermal shield of a generator, such as a superconducting generator, that moves heat more efficiently, thereby creating a more uniform temperature distribution. In a particular embodiment, for example, a cooling system of the present disclosure includes a toroidal thermal shield for surrounding a field winding assembly fixedly coupled to a structural member of the superconducting generator, a cryocooler in thermal contact with an outer surface of the toroidal thermal shield via a bus bar, and at least one gas tank in thermal contact with the thermal shield. In addition, the gas tank may have a generally toroidal shape such that circulation of cooling gas in the gas tank reduces temperature differences around the circumference of the thermal shield. In addition, in an embodiment, the bus bar thermally connecting the cryocooler to the thermal shield may be placed in an asymmetric position relative to the thermal shield to enhance gas circulation in the gas tank for maximizing heat transfer, thereby providing a more uniform thermal temperature distribution that reduces radiative heat transfer to a cold mass.

[0033] With reference to the accompanying drawings, Figure 1 A perspective view of a wind turbine 10 is shown. As mentioned, the present disclosure is directed to a generator that is particularly suitable for use in a wind turbine 10, although not limited to such use. Figure 1 An "onshore" (land-based) wind turbine 10 installation is depicted, but it will be appreciated that the invention is not limited to onshore wind turbines and is equally applicable to "offshore" (water-based) wind turbine installations having fixed or floating foundations.

[0034] Still reference Figure 1 , 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 hub 20 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 than three or less than three rotor blades 22. Each rotor blade 22 may be spaced around hub 20 to facilitate rotating rotor 18 so that kinetic energy can be converted from wind into usable mechanical energy and subsequently into electrical energy. For example, hub 20 may be rotatably coupled to a generator (not shown) positioned within nacelle 16 to allow electrical energy to be generated.

[0035] Reference now Figure 2 , illustrates an interior perspective view of an embodiment of a nacelle 16 having a superconducting generator 23 housed therein according to the present disclosure. Further, 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 around a stationary field assembly 26 (such as a superconducting field winding assembly 26) having a second electromagnetic component configuration.

[0036] The static field assembly 26 includes superconducting coils 52, which may be groups of wires formed in a racetrack shape. Therefore, in certain embodiments, the superconducting coils 52 are constrained to maintain the racetrack shape. In addition, as shown, each superconducting coil 52 is supported in a recess / passage 50 in the housing 42, which may be conductively cooled by a cryogenic cooling tube 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 may be supported in a cryostat housing 36 (also referred to herein as a vacuum vessel), which is secured to a base tube 44.

[0037] Still reference 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 (36) coils may form an annular array of field windings used as stator field windings for the generator 23. Further, in an embodiment, the superconducting coils 52 may each be formed of a wire (of NbTi or other superconducting material) wound helically around a racetrack form, which may include a cooling conduit for a cryogen. The stationary field assembly 26 includes a superconducting coil magnet 54 formed by passing an electric current through the superconducting field coils 52, which is enclosed in the housing 42 and receives a cryogen through a cooling recess / passage 50.

[0038] In additional embodiments, the cryogen recondensers 38, 40 may be housed in the field coil assembly 26, provided that the cryogen cooling liquid in the recondensers 38, 40 is at least partially elevated above the superconducting field windings to provide a gravity feed of cryogen to the windings. Alternatively, the recondensers 38, 40 may be mounted on top of the field coil assembly.

[0039] Reference now Figure 3 , illustrates a cross-section of an embodiment of a direct drive superconducting generator 23 having an annular rotating armature winding assembly 24 ("armature 24") radially inside 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 outside of the stationary field assembly 26. In particular, as shown, the armature 24 is essentially an inner annular ring configuration ( Figure 4). The armature 24 includes conductive coils 52 (e.g., coils or bars) arranged longitudinally along the length of the armature 24 and arranged on the inner cylindrical surface of the armature 24. The conductive coils 52 may be connected to each other at their opposite ends by conductive end turns 28. The end turns 28 between the longitudinal conductive coils 52 depend on their number and arrangement, as well as 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 10-25 mm).

[0040] 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 a slot 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 end of a cryostat housing 36. The housing 36 and its cooling components form a cryostat which cools the superconducting coils of the field windings.

[0041] The cryostat housing 36 insulates the superconducting coils 52 so that the superconducting coils 52 can be cooled to a temperature close to absolute zero, for example, to about 20 Kelvin (K), and more preferably to about 10K, and still more preferably to about 4K. To cool the windings, the cryostat housing 36 may include one or more insulating conduits 46 to receive liquid helium (He) or other similar cryogenic liquids (referred to as cryogen). A conventional two-stage recondenser 38 is mounted in an upper region of the field coil assembly, on top of the field coil assembly, or on top of the tower 12, and above the field windings to provide cryogen, such as liquid He, using a gravity feed. The second recondenser 40 may provide a second cooling liquid, such as liquid nitrogen or neon, to the internal heat shield of the cryostat housing 36 via the conduit 48.

[0042] Reference now Figure 4, illustrating various components of a schematic diagram of a simplified cooling system 102 for a superconducting generator 100 according to conventional construction. More specifically, as shown, the superconducting generator 100 generally includes a cooling system 102, which is arranged together 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 can be a stationary component such as a field winding assembly 26, and the armature winding assembly 24 rotates within the field winding assembly 26. It should be understood that the annular structure for the armature winding assembly is Figure 3 However, in order to simplify the drawings and more clearly explain the details of the present disclosure, Figures 4 to 9 In addition, as an example, vacuum vessel 106 may be a non-rotatable component that supports a field winding assembly such as stationary field assembly 26. Thus, in such an embodiment, the rotatable component may be oriented to rotate relative to the non-rotatable component during operation of 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 busbar / 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 conducted through structural members (such as those used to hold the static field assembly 26 in place).

[0043] Therefore, for conventional cooling systems such as Figure 4 ), the thermal shield 104 has a temperature (T) distribution around its circumference. Cooling is provided by a cryocooler 110 via a thermal bus / busbar 112, which is positioned at the top of the thermal shield 104 for efficient heat transfer. As such, cooler temperatures are observed near the hot bus / busbar 112, and warmer temperatures are observed farther away from the hot bus / busbar 112. Therefore, a large temperature differential is observed between the top and bottom of the thermal shield 104, thereby causing additional radiated heat from the thermal shield 104 to the cold mass 108. Such a large temperature differential is undesirable because it causes a high thermal load on the cold mass 108 and therefore reduces the operating margin of the superconducting field windings. As mentioned, it should be understood that, Figure 4 The configuration relative to Figure 3 The field winding assembly 26 is simplified to better illustrate the operating principle of the cooling system.

[0044] Therefore, the present disclosure is directed to an improved cooling system 200 that solves the aforementioned problems. In particular, the cooling system 200 of the present disclosure reduces the large temperature differences in the heat shield 104 by reducing the temperature at the hottest point on the heat shield 104. For example, referring now to Figures 5 to 11 , illustrating various components of an embodiment of an improved cooling system 200 for a superconducting generator 100 according to the present disclosure.

[0045] In particular, if Figure 5 and Figures 9 to 11 , the cooling system 200 includes a thermal shield 204 configured to surround a stationary component 208, such as a field winding assembly 26. As mentioned, the thermal shield 204 is disposed between a cold mass, which may be a stationary component 208 such as a field winding assembly 26, and a vacuum vessel 106, which may be a non-rotating component that supports a field winding assembly such as a stationary field assembly 26. Thus, in such an embodiment, the rotatable component may be oriented to rotate relative to the non-rotatable component during operation of the generator. It should be further understood that in addition to the structural components used to support the thermal shield and the cold mass within the vacuum vessel 106, the vacuum vessel 106 may also be separate and decoupled from the stationary field assembly 26.

[0046] Still reference Figure 5 and Figures 9 to 11 , the cooling system 200 further includes a cryocooler 210 in thermal contact with the heat shield 204. In particular, as Figure 5 and Figures 9 to 11 As shown in , the cryocooler 210 is in thermal contact with the heat shield 204 via the bus bar 212. In addition, in an embodiment, as shown in Figures 5 to 7 and Figures 9 to 11 , the cooling system 200 includes a gas tank 206 adjacent to and in thermal contact with the heat shield 204. Thus, in such embodiments, the gas tank 206 contains a cooling gas 213 that is configured to circulate within the gas tank 206 to provide uniform cooling to the heat shield 204. For example, in embodiments, the cooling gas 213 may be helium at a pressure, such as about one (1) bar, although pressures above and below 1 bar may also be utilized.

[0047] More specifically, if Figure 6 and Figure 7 As shown in , in an embodiment, the gas tank 206 may have a generally toroidal shape 211, i.e., similar to a donut shape. As described herein, a toroidal shape may include any three-dimensional shape having a surface of revolution with a hole in the middle. Thus, a toroidal shape may have a circular or elliptical cross-section (e.g., Figure 6 ) and square or rectangular cross-sections (as shown in Figure 7). In addition, the gas tank 206 may be a single gas tank, or may be segmented to include multiple gas tanks 206. It will be appreciated that if the multiple gas tanks 206 are each annular and connected to a heat shield, segmentation into multiple tanks is possible without departing from the spirit of the present invention.

[0048] In addition, in an embodiment, the gas tank 206 may be constructed of any suitable material, such as steel, aluminum, and / or another other suitable metal or metal alloy. In addition, as shown in the illustrated embodiment, the gas tank 206 may be positioned radially inward of the heat shield 204, for example, against the inner surface 214 of the heat shield 204. In an alternative embodiment, the gas tank 206 may be positioned radially outward of the heat shield 204, for example, against the outer surface of the heat shield 204. Therefore, as shown, in an embodiment, the gas tank 206 may extend around the entire inner circumference of the heat shield 204. It will be appreciated that the physical contact between the gas tank 206 and the heat shield 204 thermally couples the two components, thereby allowing the gas tank 206 to participate in determining the temperature distribution around the circumference of the heat shield 204.

[0049] In additional embodiments, Figure 8 , for example, the gas tank 206 may be secured to the heat shield 204 using any suitable means, such as via a securing assembly 226. In particular, as shown, the securing assembly 226 may include one or more brackets 228 that may be secured around and / or to the gas tank 206 and / or the heat shield 204. In an embodiment, such brackets 228 may be metal brackets, such as aluminum brackets, or any other suitable material other than aluminum.

[0050] Special reference Figure 5 and Fig. 9 In an embodiment, busbar 212 may be positioned at substantially the 12 o'clock position of heat shield 204 such that cooling gas 213 circulates symmetrically in four quadrants (e.g., labeled I, II, III, and IV) of gas tank 206, as indicated by arrows 216. Thus, in such an embodiment, the symmetrical gas circulation in all four quadrants reduces the temperature difference between upper location 220 and lower location 222 of heat shield 204.

[0051] In an alternative embodiment, if Fig.10 , the bus bar 212 may be offset from the 12 o'clock position of the heat shield 204 so that the cooling gas 213 circulates in the gas tank 206 in a single loop 218. In such an embodiment, as shown, by offsetting the bus bar 212, the gas circulation pattern is broken, thereby forcing the gas to circulate throughout the gas tank 206. Thus, in an embodiment, relative to Fig. 9Due to the symmetrical configuration of the heat shield 204 , a loop circulation increases heat transfer within the gas tank 206 and reduces the temperature difference between the upper location 220 and the lower location 222 and the overall temperature at the hot spot 224 on the heat shield 204 .

[0052] In particular, as shown, the busbars 212 may be positioned in a first quadrant of the thermal shield 204 (eg, in Fig.10 1 ), so that the cooling gas 213 circulates in the gas tank 206 in a clockwise direction driven by gravity. Thus, as shown, the first quadrant I generally refers to the quadrant between the 12 o'clock position and the 3 o'clock position of the thermal shield 204. Thus, as an example, the busbars 212 are positioned from about one (1) o'clock position to about two (2) o'clock position.

[0053] Alternatively, in an embodiment, if Fig.11 As shown in FIG. , the busbar 212 may be positioned in the fourth quadrant of the thermal shield 204 (eg, in Fig.11 2 (labeled IV) in the figure, so that the cooling gas 213 circulates in the gas tank 206 in a clockwise direction driven by gravity. Therefore, as shown, the fourth quadrant generally refers to the quadrant between the 9 o'clock position and the 12 o'clock position of the thermal shield 204. Therefore, as an example, the busbar 212 is positioned from about ten (10) o'clock position to about eleven (11) o'clock position.

[0054] Reference now Figures 12 to 18 , further illustrating additional embodiments of the gas tank 206 described herein. Figures 12 to 18 The gas tank 206 is integrated with the heat shield 204, rather than being fixed to the heat shield 204 via the fixing assembly 226. In particular, as Fig.12 and Fig.13 As shown in FIG. 2 , the gas tank 206 is integrally formed with (or welded to) the heat shield 204 , such as at one or more edges of the heat shield 204 .

[0055] The integrated gas tank 206 may have a variety of configurations or shapes. Figures 12 to 16A As shown in FIG. 1 , the gas tank 206 may have a circular opening 228 defining a tank portion for receiving the cooling gas 213 and having a wall 232 ( FIG. 24 ) configured to engage with the heat shield 204. Fig.13 ) is aligned with the tangential flange 230. In another embodiment, as Fig. 16B As shown in FIG. 1 , the gas tank 206 may include a circular opening 228 having a wall ( 224 ) for contacting the heat shield 204 . Fig.13 ) are connected to the opposite thickened edge 234. Similarly, Fig. 16CAs shown in FIG. , the gas tank 206 may include a wall ( Fig.13 ) but also includes a circular opening 228 of an opposing thickened edge 234 connected thereto, but also includes a cutout 236 for reducing the overall material of the gas tank 206.

[0056] In some other embodiments, Fig.16D As shown in FIG. , the gas tank 206 may include a wall ( Fig.13 ) in a circular opening 228 in a square or rectangular wall 238 connected thereto. In such an embodiment, Fig.17 and Fig.18 As shown in FIG. , the wall 238 of the gas tank 206 may be secured to the edge of the heat shield 204 ( Fig.17 ) or fixed to the inner surface 242 ( Fig.18 ).exist Fig.17 and Fig.18 In each of these, as an example, the wall 238 of the gas tank 206 may be secured to the heat shield 204 using, for example, welding, as indicated via weld joint 244 .

[0057] In addition, if Fig.14 As shown in , the gas tank 206 may be a unitary tank formed from a single curved part, such as by extrusion. Fig.15 As shown in , the gas tank 206 can be formed from a plurality of segments 240 that are circumferentially arranged together. In such an embodiment, as shown, the segments 240 can be linear rather than curved.

[0058] Various advantages may be realized using the gas canisters described herein, such as improved thermal contact and mechanical stability.

[0059] In addition, the skilled person will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described and other known equivalents for each such method and feature can be mixed and matched by a person of ordinary skill in the art to construct additional systems and techniques according to the principles of the present disclosure. Of course, it will be understood that not necessarily all such purposes or advantages described above can be achieved according to any particular embodiment. Thus, for example, it will be appreciated by those skilled in the art that the systems and techniques described herein can be embodied or performed in a manner that achieves or optimizes an advantage or a group of advantages as taught herein, without necessarily achieving other purposes or advantages as taught or suggested herein.

[0060] Further aspects of the invention are provided by the subject matter of the following clauses:

[0061] Clause 1. A generator comprising:

[0062] a non-rotating member that supports the field winding assembly;

[0063] a rotatable member oriented to rotate relative to the non-rotatable member during operation of the generator;

[0064] an armature winding assembly fixedly coupled to the rotatable member for rotation therewith during operation of the generator, the armature winding assembly comprising a plurality of conductive coils;

[0065] a heat shield surrounding a field winding assembly fixedly coupled to a stationary component;

[0066] a cryocooler in thermal contact with the thermal shield; and

[0067] A gas tank is adjacent to and in thermal contact with the heat shield, the gas tank containing a cooling gas configured to circulate within the gas tank to provide uniform cooling to the heat shield.

[0068] Clause 2. The generator of clause 1, wherein the gas tank has a toroidal shape.

[0069] Clause 3. The generator of any of the preceding clauses, wherein the gas tank is positioned radially inwardly of the heat shield.

[0070] Clause 4. The generator of any of the preceding clauses, wherein the gas tank extends around the entire inner circumference of the heat shield.

[0071] Clause 5. The generator of any of the preceding clauses, wherein the stationary component comprises a vacuum vessel.

[0072] Clause 6. The generator of any of the preceding clauses, wherein the cooling gas comprises a cryogen gas.

[0073] Clause 7. The generator according to any of the preceding clauses, wherein the cryocooler is in thermal contact with the heat shield via a bus bar.

[0074] Clause 8. The generator of Clause 7, wherein the busbar is positioned at substantially the 12 o'clock position of the heat shield so that the cooling gas circulates symmetrically in the four quadrants of the gas tank.

[0075] Clause 9. The generator according to clauses 7 to 8, wherein the busbars are offset from the 12 o'clock position of the heat shield so that the cooling gas circulates in the gas tank in a single loop.

[0076] Clause 10. The generator of clause 9, wherein the busbars are positioned in a first quadrant of the heat shield such that cooling gas circulates in the gas tank in a clockwise direction driven by gravity, the first quadrant being between the 12 o'clock position and the 3 o'clock position of the heat shield.

[0077] Clause 11. The generator according to clauses 9 to 10, wherein the busbars are positioned in a fourth quadrant of the heat shield such that cooling gas circulates in the gas tank in a counterclockwise direction driven by gravity, the fourth quadrant being between the 12 o'clock position and the 9 o'clock position of the heat shield.

[0078] Clause 12. The generator of any of the preceding clauses, wherein the generator is a superconducting generator and the plurality of conductive coils are superconducting coils.

[0079] Clause 13. A cooling system for a superconducting generator, the cooling system comprising:

[0080] a thermal shield for surrounding a field winding assembly fixedly coupled to a stationary component of a superconducting generator, the stationary component being oriented relative to the rotatable component during operation of the superconducting generator;

[0081] a cryocooler in thermal contact with an outer surface of the heat shield via the busbars; and

[0082] A gas tank is in thermal contact with the heat shield, the gas tank comprising a toroidal shape and positioned radially inward of the heat shield on an inner surface of the heat shield, the gas tank containing a cooling gas configured to circulate in the gas tank to provide uniform cooling to the heat shield.

[0083] Clause 14. The cooling system of Clause 13, wherein the gas tank extends around the entire inner circumference of the heat shield.

[0084] Clause 15. The cooling system of clauses 13-14, wherein the stationary component comprises a vacuum vessel.

[0085] Clause 16. The cooling system of clauses 13 to 15, wherein the cooling gas comprises a cryogen gas.

[0086] Clause 17. The cooling system of clauses 13 to 16, wherein the busbar is positioned at substantially the 12 o'clock position of the heat shield so that the cooling gas circulates symmetrically in the four quadrants of the gas tank.

[0087] Clause 18. The cooling system of clauses 13 to 17, wherein the busbars are offset from the 12 o'clock position of the heat shield so that the cooling gas circulates in the gas tank in a single loop.

[0088] Clause 19. The cooling system of clause 18, wherein the busbars are positioned in a first quadrant of the heat shield such that cooling gas circulates in the gas tank in a clockwise direction driven by gravity, the first quadrant being between the 12 o'clock position and the 3 o'clock position of the heat shield.

[0089] Clause 20. The cooling system of clauses 18 to 19, wherein the busbar is positioned in a fourth quadrant of the heat shield such that the cooling gas circulates in the gas tank in a counterclockwise direction driven by gravity, the fourth quadrant being between the 12 o'clock position and the 9 o'clock position of the heat shield.

[0090] This written description uses examples to disclose the invention (including the best mode), and also to enable any person skilled in the art to practice the invention (including making and using any devices or systems, and performing any incorporated methods). The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A generator, comprising: a non-rotating member that supports the field winding assembly; a rotatable component oriented to rotate relative to the non-rotatable component during operation of the generator; an armature winding assembly fixedly coupled to the rotatable member for rotation therewith during the operation of the generator, the armature winding assembly comprising a plurality of conductive coils; a thermal shield surrounding the field winding assembly fixedly coupled to the non-rotatable member; a cryocooler in thermal contact with the thermal shield; as well as A gas tank is adjacent to and in thermal contact with the heat shield, the gas tank containing a cooling gas configured to circulate within the gas tank to provide uniform cooling to the heat shield.

2. The generator according to claim 1, wherein: The gas tank has a torus shape.

3. The generator according to claim 1, wherein: The gas tank is positioned radially inwardly of the heat shield.

4. The generator according to claim 1, wherein: The gas tank extends around the entire inner circumference of the heat shield.

5. The generator according to claim 1, wherein: The non-rotatable member includes a vacuum vessel.

6. The generator according to claim 1, wherein: The cooling gas includes a cryogen gas.

7. The generator according to claim 1, wherein: The cryocooler is in thermal contact with the heat shield via a bus bar.

8. The generator according to claim 7, wherein: The busbar is positioned at substantially the 12 o'clock position of the heat shield so that the cooling gas circulates symmetrically in the four quadrants of the gas tank.

9. The generator according to claim 7, wherein: The busbars are offset from the 12 o'clock position of the heat shield so that the cooling gas circulates in the gas tank in a single loop.

10. The generator according to claim 9, wherein: The busbars are positioned in a first quadrant of the heat shield between the 12 o'clock and 3 o'clock positions of the heat shield such that the cooling gas circulates in the gas tank in a clockwise direction driven by gravity.

11. The generator according to claim 9, wherein: The busbars are positioned in a fourth quadrant of the heat shield between the 12 o'clock position and the 9 o'clock position of the heat shield such that the cooling gas circulates in the gas tank in a counterclockwise direction driven by gravity.

12. The generator according to claim 1, wherein: The generator is a superconducting generator, and the plurality of conducting coils are superconducting coils.

13. A cooling system for a superconducting generator, the cooling system comprising: a thermal shield for surrounding a field winding assembly fixedly coupled to a stationary component of the superconducting generator, the stationary component being oriented relative to a rotatable component during operation of the superconducting generator; a cryocooler in thermal contact with an outer surface of the heat shield via a bus bar; and a gas tank in thermal contact with the heat shield, the gas tank comprising a toroidal shape and positioned radially inward of the heat shield on an inner surface of the heat shield, the gas tank containing a cooling gas configured to circulate in the gas tank to provide uniform cooling to the heat shield.

14. The cooling system according to claim 13, wherein: The gas tank extends around the entire inner circumference of the heat shield.

15. The cooling system according to claim 13, wherein: The stationary member includes a vacuum container.

16. The cooling system according to claim 13, wherein: The cooling gas includes a cryogen gas.

17. The cooling system according to claim 13, wherein: The busbar is positioned at substantially the 12 o'clock position of the heat shield so that the cooling gas circulates symmetrically in the four quadrants of the gas tank.

18. The cooling system according to claim 13, wherein: The busbars are offset from the 12 o'clock position of the heat shield so that the cooling gas circulates in the gas tank in a single loop.

19. The cooling system according to claim 18, wherein: The busbars are positioned in a first quadrant of the heat shield between the 12 o'clock and 3 o'clock positions of the heat shield such that the cooling gas circulates in the gas tank in a clockwise direction driven by gravity.

20. The cooling system of claim 18, wherein: The busbars are positioned in a fourth quadrant of the heat shield between the 12 o'clock position and the 9 o'clock position of the heat shield such that the cooling gas circulates in the gas tank in a counterclockwise direction driven by gravity.

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