Superconducting generator comprising a vacuum container made of magnetic material

Abstract

A superconducting generator includes an armature configured to rotate via an axis and a fixed field disposed concentrically with the armature and radially outward from the armature. The fixed field includes a superconducting field winding and a vacuum container having an inner wall of one of a non-magnetic material or a paramagnetic material facing the armature, an opposing outer wall of a ferromagnetic material, and a plurality of side walls connecting the inner wall and the opposing outer wall. The superconducting field winding is disposed in the vacuum container. A wind turbine and method are also disclosed. The wind turbine includes a rotor having a plurality of blades. The wind turbine also includes a shaft coupled to the rotor. In addition, the wind turbine includes a superconducting generator coupled to the rotor via the shaft.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to a superconducting generator, and in particular to a superconducting generator including a vacuum container at least partially composed of a magnetic material and a wind turbine including the superconducting generator. Background Art

[0002] Conventional machines such as conventional superconducting generators typically include a stationary field and an armature. The armature includes a conventional ferromagnetic core and an armature winding disposed on the conventional ferromagnetic core. The armature winding is generally formed using conventional materials (e.g., copper or aluminum). However, the stationary field includes a superconducting field winding formed by a superconducting wire that supports very high current densities without causing any dissipation. Due to the high current density in the superconducting field winding, a conventional superconducting generator (and more particularly a superconducting wire) generates a very high magnetic field, for example, about 7 Tesla or more, when in operation.

[0003] Typical high temperature superconducting field windings are formed of superconducting materials that are brittle and must be cooled to a temperature at or below a critical temperature (e.g., 27 Kelvin) to achieve and maintain superconductivity. Superconducting field windings may be formed of high temperature superconducting materials such as those based on BSCCO (Bi2Sr2Ca n-1 Cu n O 2n+4+x ) conductor.

[0004] The superconducting field windings must generally be thermally insulated to keep the cooling power within practical limits. A vacuum vessel is generally used to help create thermal insulation for the superconducting field windings. The vacuum prevents heat from being transferred from the warm rotor core to the superconducting field windings by convection. The vacuum also provides cooling for the superconducting field windings together with the associated cooling system. The vacuum provides complete enclosure for the superconducting field windings therein and means that an associated hermetic seal is maintained on the assembly including the field coils and associated support structure and cooling equipment.

[0005] The typical vacuum container surrounding the superconducting field winding is formed of an expensive and temperature-insensitive material such as non-magnetic stainless steel so that it does not affect the magnetic properties of the superconducting field winding. As such, the overall cost of the superconducting generator is high, and it needs to include magnetic shielding to reduce the fringe magnetic field outside the vacuum container, otherwise it will leave some stronger fringe magnetic fields outside the vacuum container.

[0006] Thus, there has long been a need for a superconducting generator that incorporates a more cost-effective means for providing a vacuum vessel around the superconducting field windings, i.e., a means for enhancing the magnetic field near the ends of the superconducting field windings and passively providing some degree of magnetic shielding. The desired generator should be highly reliable, of reasonable size and weight, and constructed of cost-effective materials to reduce the overall cost of the generator and allow economical transportation and installation. Summary of the invention

[0007] According to one embodiment of the present disclosure, a superconducting generator is provided. The superconducting generator includes an armature configured to rotate via an axis and a fixed field arranged concentrically with the armature and radially outward from the armature. The fixed field includes a superconducting field winding and a vacuum container, the vacuum container including an inner wall facing the armature, an opposite outer wall, and a plurality of side walls connecting the inner wall and the outer wall. The superconducting field winding is arranged in the vacuum container. The inner wall is composed of one of a non-magnetic material or a paramagnetic material. The opposite outer wall is composed of a ferromagnetic material.

[0008] According to one embodiment of the present disclosure, a wind turbine is provided. The wind turbine includes: a rotor including a plurality of blades; a shaft coupled to the rotor; and a superconducting generator coupled to the rotor via the shaft. The fixed field includes a superconducting field winding and a vacuum container including an inner wall facing the armature and composed of one of a non-magnetic material or a paramagnetic material, an opposite outer wall composed of a ferromagnetic material, and a plurality of side walls coupling the inner wall and the opposite outer wall. The superconducting field winding is disposed in the vacuum container.

[0009] According to yet another embodiment of the present disclosure, a method is provided. The method includes operating a wind turbine having a superconducting generator, the superconducting generator including an armature having an armature winding and a fixed field having a superconducting field winding. The superconducting field winding is disposed in a vacuum vessel, the vacuum vessel being configured to have an inner wall composed of one of a non-magnetic material or a paramagnetic material and an opposing outer wall composed of a ferromagnetic material. The superconducting field winding is also disposed concentrically with the armature winding and radially outward from the armature winding. The vacuum vessel provides an increased magnetic flux near the end of the superconducting field winding and provides partial magnetic shielding.

[0010] 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 disclosure, 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

[0011] The remainder of the disclosure, including reference to the accompanying drawings, more particularly sets forth a complete and enabling disclosure of the present disclosure, including the best mode thereof, to one skilled in the art, wherein:

[0012] Figure 1is a schematic diagram of an example wind turbine according to one or more embodiments of the present disclosure;

[0013] Figure 2 is a schematic diagram of an electric machine (e.g., a superconducting generator) according to one or more embodiments of the present disclosure;

[0014] Figure 3 According to one or more embodiments of the present disclosure Figure 2 A perspective cross-sectional view of a portion of an electric machine (eg, a superconducting generator); and

[0015] Figure 4 According to one or more embodiments of the present disclosure Figure 3 An enlarged perspective cross-sectional view of a portion of an electric machine (e.g., a superconducting generator).

[0016] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of embodiments of the present disclosure. These features are considered to be applicable to a wide variety of systems including one or more embodiments of the present disclosure. As such, the drawings are not intended to include all conventional features known to those of ordinary skill in the art required to implement the embodiments disclosed herein. In the several views of the drawings, corresponding reference numerals indicate corresponding parts. DETAILED DESCRIPTION

[0017] In order to provide a concise description of these embodiments, not all features of an actual implementation may be described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions may be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints.

[0018] Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those generally understood by a person of ordinary skill in the art to which this specification belongs. As used herein, the terms "first", "second", etc. do not indicate any order, quantity or importance, but are used to distinguish one element from another. In addition, the terms "one" and "a" do not indicate a limit on quantity, but indicate that there is at least one referenced item. The use of "including", "comprising" or "having" and its variations herein is intended to cover the items listed thereafter and their equivalents and additional items. The terms "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical or magnetic connections or couplings, whether direct or indirect. As used herein, the term "paramagnetism" refers to a material that is weakly attracted by the magnetic poles of a magnet but does not retain any permanent magnetism. As used herein, the terms "light carbon steel" and "light carbon steel or low carbon steel" refer to a material containing a small percentage of carbon (typically about 0.04% to 0.30% carbon, and more particularly about 0.06% to 0.30% carbon). Additional elements may be added or increased to obtain desired properties. The term "fixed field" as used herein refers to field generating components that remain fixed during operation, such as superconducting field windings, and to the housing in which the field generating components are housed.

[0019] As used herein, the terms "may" and "may be" indicate the possibility of occurring under a set of circumstances; possessing a specified characteristic, feature, or function; and / or modifying another verb by expressing one or more capabilities, properties, or possibilities associated with the modified verb. Thus, the use of "may" and "may be" indicates that the modified term is clearly suitable, capable of being realized, or suitable for the indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes be unsuitable, incapable of being realized, or unsuitable for the indicated capacity, function, or usage.

[0020] As will be described in detail below, various embodiments of superconducting generators are proposed. The superconducting generator includes an armature configured to rotate via an axis. The superconducting generator also includes a fixed field arranged concentrically with the armature and radially outward from the armature. The fixed field includes a plurality of superconducting field windings. In order to achieve thermal insulation of the superconducting field windings, the superconducting field windings are housed in a vacuum vessel, sometimes referred to as a field coil external vacuum container (OVC). The vacuum vessel forms part of a cryostat and is used to thermally insulate the superconducting coils of the non-rotating superconducting field windings so that they can be cooled to near absolute zero, for example, to 10 Kelvin (K), and preferably to 4K. The superconducting generator is intended for use in a wind turbine.

[0021] The wind turbine includes a rotor having a plurality of blades. The wind turbine also includes a shaft coupled to the rotor. In addition, the wind turbine includes a superconducting generator coupled to the rotor via the shaft. In alternative embodiments, the superconducting generator is contemplated for use in propulsion systems, magnetic levitation devices for train transportation and nuclear fusion, etc., and is not intended to be limited to wind turbine implementations.

[0022] Reference now Figure 1 , a schematic diagram of an exemplary wind turbine 100 is presented according to one embodiment of the present specification. Wind turbine 100 may be configured to generate electrical power using wind energy. Figure 1 The wind turbine 100 described and shown in the embodiments of the present invention includes a horizontal axis configuration. However, in some embodiments, in addition to or as an alternative to the horizontal axis configuration, the wind turbine 100 may include a vertical axis configuration (not shown). The wind turbine 100 may be coupled to a network such as, but not limited to, a power grid to receive electrical power from the power grid to drive operation of the wind turbine 100 and / or its associated components and / or to supply the electrical power generated by the wind turbine 100 to the power grid. The wind turbine 100 may be coupled to an electrical load (not shown) to supply the electrical load with the electrical power generated by the wind turbine 100.

[0023] Wind turbine 100 may include a body 102 (sometimes referred to as a “nacelle”) and a rotor 104 coupled to body 102. Rotor 104 is configured to rotate relative to body 102 about an axis of rotation 106. Figure 1 In the illustrated embodiment, nacelle 102 is shown mounted on tower 108. However, in some other embodiments, wind turbine 100 may include a nacelle that may be disposed adjacent to a surface of the ground and / or water.

[0024] The rotor 104 may include a hub 110 and a plurality of blades 112 (sometimes referred to as “airfoils”) extending radially outward from the hub 110 for converting wind energy into rotational energy. Although the rotor 104 is described and shown herein as having three blades 112, the rotor 104 may have any number of blades 112. The rotor 104 may have blades 112 of any shape, and may have blades 112 of any type and / or any configuration, whether or not such shape, type, and / or configuration is described and / or shown herein.

[0025] In some embodiments, the nacelle 102 may fully or partially house one or more of the superconducting generator 114 and the shaft 116. The superconducting generator 114 may be coupled to the rotor 104 via the shaft 116 and configured to operate via the rotor 104. For example, the rotation of the rotor 104 caused by wind energy in turn causes the rotating element (e.g., armature) of the superconducting generator 114 to rotate via the shaft 116. In some embodiments, the shaft 116 may also include a gearbox (not shown). In certain embodiments, the use of a gearbox may increase the operating speed of the superconducting generator 114 and reduce the torque requirements for a given power level. The presence or absence of a gearbox is not important for the embodiments of the superconducting generator 114 described in this specification.

[0026] The superconducting generator 114 is configured based on at least the armature (in Figure 2 and Figure 3 ) to generate electrical power relative to the rotation of the fixed field. According to some embodiments described herein, the superconducting generator 114 can be configured to generate an increased amount of electrical power compared to conventional generators. The superconducting generator 114 can be implemented in the form of a synchronous generator. Figures 2 to 4 The superconducting generator 114 is described in more detail.

[0027] exist Figure 2 In FIG. 1 , a schematic diagram of an electric machine (eg, a superconducting generator 200) is presented according to an embodiment of the present disclosure. The superconducting generator 200 may represent an electric machine used in Figure 1 1. An embodiment of a superconducting generator 114 in a wind turbine 100. Without limiting the scope of the present application, as previously stated, the superconducting generator 200 may be used in any application other than a wind turbine. As a non-limiting example, Figure 2 The superconducting generator 200 depicted in FIG. 2 is a radial field generator. Furthermore, although the superconducting generator 200 is shown as Figure 2 motor, but in some other embodiments, Figure 2 The motor may also be a superconducting motor. Reference numerals 210 and 212 represent the axial direction and radial direction of the superconducting generator 200, respectively.

[0028] like Figure 2 , superconducting generator 200 includes a fixed field 202 and an armature 204 disposed in a housing 206. As an example, in some embodiments, when superconducting generator 200 is deployed as superconducting generator 114 in wind turbine 100, armature 204 may be coupled to rotor 104 of wind turbine 100 via shaft 116 or via both shaft 116 and a gearbox. Armature 204 may be configured to rotate via shaft 116. Due to the rotation of armature 204, superconducting generator 200 may generate electrical power by virtue of a voltage induced in the armature winding as the armature winding moves through a magnetic field established by at least one superconducting field winding.

[0029] exist Figure 2 200 to separately show the stationary field 202 and the armature 204. The stationary field 202 includes at least one longitudinally extending, racetrack-shaped superconducting field winding 208 ( Figure 3 The armature 204 may include an armature winding (also identified by reference numeral 308) configured to generate a magnetic field oriented in the radial direction 212 of the superconducting generator 200. The superconducting field winding may alternatively be saddle-shaped or have some other shape suitable for a particular implementation. Figure 3 In some embodiments, the armature winding 320 is a non-superconducting winding.

[0030] The fixed field 202 is arranged concentrically with the armature 204 and radially outward from the armature 204. The fixed field 202 is maintained at a temperature sufficient to keep the fixed field 202 superconducting, usually much lower than the temperature of the armature 204. Typically, in order to enable the superconducting characteristics of the fixed field 202, if the superconducting field windings 208, 308 are composed of low-temperature superconducting materials, the fixed field 202 is maintained in an ultra-low temperature range of about 4 Kelvin; if the superconducting field windings 208, 308 are composed of high-temperature superconducting materials, the fixed field 202 is maintained at a temperature of about 30 Kelvin. As non-limiting examples, the low-temperature superconducting material may include an alloy of niobium and tin, or an alloy of niobium and titanium. As a non-limiting example, the high-temperature superconducting material may include yttrium barium copper oxide (YBCO).

[0031] Now go to Figure 3 and Figure 4 According to the embodiment of the present disclosure, Figure 2 A perspective cross-sectional view 300 of a portion of a superconducting generator 200 ( Figure 3 ), and presents Figure 3 A part of the enlargement ( Figure 4 ). The superconducting generator 200 includes a fixed field 302 (similar to Figure 2 The fixed field 202) and the armature 304 (similar to Figure 2 The fixed field 302 is arranged concentrically with the armature 304 and radially outward from the armature 304, and includes a vacuum vessel 306 and at least one superconducting field winding 308. The vacuum vessel 306 forms an external vacuum reservoir (OVC) and is about Figure 4 More specifically described.

[0032] In some embodiments, the superconducting generator 200 may further include one or more slots 310, one or more conduits 312, a cooling device 314, an optional thermal shield 316, one or more torque transfer structures 318 such as a torque tube, or a combination thereof. In addition, the armature 304 includes an armature winding 320. In some embodiments, the armature winding 320 is a non-superconducting winding. Figure 3 In the embodiment shown in , a torque tube is used as the torque transfer structure 318. Without limiting the scope of the present disclosure, other types of torque transfer structures or torque transfer mechanisms may also be used to replace or supplement the torque tube. In the following description, the terms "torque transfer structure" and "torque tube" may be used interchangeably.

[0033] As in Figure 3 and Figure 4 300, the vacuum vessel 306 (sometimes referred to as a cryostat) is an annular cylindrical container that fully or partially houses the superconducting field windings 308, slots 310, one or more conduits 312, a cooling device 314, an optional heat shield 316, and one or more torque tubes 318. Reference numerals 322 and 324 represent the inner wall and outer wall of the vacuum vessel 306, respectively. In some embodiments, the inner wall 322 faces the armature 304. More particularly, the fixed field 302 and the armature 304 are arranged so that the inner wall 322 of the vacuum vessel 306 is positioned radially opposite to the outer surface 330 of the armature 304. As shown, a portion of the outer wall 324 defines a cold box 326 in which the one or more slots 310, the one or more conduits 312, and the cooling device 314 are housed. A plurality of radially extending sidewalls 328 couple the inner wall 322 of the vacuum vessel 306 to the outer wall 324 of the vacuum vessel 306.

[0034] As in Figure 4As shown by shading in the figure, in this particular embodiment, the vacuum container 306 is at least partially composed of a ferromagnetic material. As shown, the inner wall 322 is composed of one of a non-magnetic material or a paramagnetic material, and the paramagnetic material has a low magnetic permeability (typically <7 μ / μ0, and more particularly μ / μ0 is about 1.0 to 2.0), such as stainless steel, where μ / μ0=1.005, where μ0 symbolizes the magnetic permeability of free space, μ symbolizes the absolute magnetic permeability of the medium, and μ / μ0 symbolizes the relative magnetic permeability. The outer wall 324 and the side wall 328 are formed of a ferromagnetic material having a magnetic permeability of about μ / μ0 ~100-10,000. Suitable ferromagnetic materials for forming the wall 324 and the side wall 328 of the vacuum container 306 include cobalt, nickel and steel, particularly steel containing from 0.04% to 0.30% carbon, more particularly from 0.06% to 0.30% carbon. Examples of suitable steel materials include, but are not limited to, SAE-AISI 1010, SAE-AISI 1020, and ASTM A36. In yet another embodiment, only the outer wall 324 is formed of a ferromagnetic material in conjunction with the inner wall 322. In this embodiment, similar to the inner wall 322, the side wall 328 may be formed of one of a non-magnetic or paramagnetic material, such as stainless steel.

[0035] Complete (or at least partial) construction of the vacuum vessel 326 of light carbon steel or low carbon steel not only provides a more cost effective vacuum vessel 306, but also additionally provides an enhancement of the magnetic field near the end 309 of the superconducting field winding 208 and provides a degree of passive magnetic shielding, which combined greatly reduces the overall cost of the vacuum vessel 306.

[0036] Due to the external ambient pressure and the internal vacuum, the vacuum container 306 is subjected to a pressure differential load. Therefore, in some embodiments, the inner wall 322 of the vacuum container 306 is thinner than the outer wall 324 of the vacuum container 306. The radially outward force is applied to the inner wall 322 of the vacuum container 306, which can cause the inner wall 322 to bear tension. The force on the outer wall 324 of the vacuum container 306 points to the radially inward direction, so that the outer wall 324 is subjected to compression. If the outer wall 324 is not thick enough, the compression force may cause deflection. Due to the difference in the direction of the radial force between the inner wall 322 and the outer wall 324, the outer wall 324 can be designed to be thicker than the inner wall 322. In an embodiment, the inner wall 322 has a thickness of about 6-12 mm, the side wall 328 has a thickness of about 12-20 mm thick, and the outer wall 324 has a thickness of about 20-25 mm thick. In an embodiment, a portion of the outer wall 324 forming the cold box 326 has a thickness of about 10 mm.

[0037] In addition, in some embodiments, the fixed field 302 may also include a suitable arrangement for cooling and maintaining the superconducting field winding 308 at an ultra-low temperature. As an example, such an arrangement for cooling the superconducting field winding 308 may include one or more of a slot 310, a conduit 312, and a cooling device 314. The slot 310 is configured to be in fluid communication with the cooling device 314 and store a cooling fluid. Although the fixed field 302 is shown as including a single slot 310, it is also contemplated within the scope of the present specification to use two or more such slots for storing cooling fluids. Non-limiting examples of cooling fluids may include any type of gaseous or condensed cooling fluid, such as helium.

[0038] In addition, the cooling device 314 may be disposed inside or outside the vacuum vessel 306 and configured to cool the cooling fluid so as to maintain the superconducting field winding 308 at a temperature below an ultra-low temperature. At ultra-low temperatures, the material of the superconducting field winding 308 is superconducting. A suitable temperature range for the operation of the superconducting field winding 308 depends on the superconducting material selected for the superconducting field winding 308. In particular, the cooling device 314 may be configured to cool the cooling fluid so as to maintain the superconducting field winding 308 at an ultra-low temperature, such as about 4 Kelvin, which may be suitable for low-temperature superconducting materials such as alloys of niobium and titanium. In another non-limiting example, the cooling device 314 may be configured to cool the cooling fluid so as to maintain the temperature of the superconducting field winding 308 in the range of about 4 Kelvin to about 10 Kelvin, which may be suitable for low-temperature superconducting materials such as alloys of niobium and tin. In yet another non-limiting example, the cooling device 314 may be configured to cool the cooling fluid so as to maintain the temperature of the superconducting field winding 308 in a range of about 20 Kelvin to about 26 Kelvin, which may be suitable for high temperature superconducting materials such as yttrium barium copper oxide (YBCO). In addition, in a non-limiting example, liquid helium may be used as a cooling fluid for low temperature superconductors because it has a temperature of about 5.19 Kelvin. In another non-limiting example, for high temperature superconducting materials, hydrogen or neon may be used as a cooling fluid.

[0039] The conduit 312 may be disposed inside the vacuum vessel 306 and fluidly coupled to the slot 310. The conduit 312 may be disposed annularly inside the vacuum vessel 306. The conduit 312 is configured to facilitate the flow of a cooling fluid within the fixed field 302. In particular, the cooling fluid passively circulates annularly within the fixed field 302 through the conduit 312, driven by density gradients and phase changes. While circulating, the cooling fluid removes any heat deposited on or into the cryogenic structures of the fixed field 302 and the superconducting field winding 308 (such as from radiation or conduction heat transfer or from eddy current heating generated by the operation of the generator), thereby maintaining the superconducting field winding 308 at an ultra-low temperature.

[0040] Additionally, in some embodiments, an optional heat shield 316 may be disposed inside the vacuum vessel 306. In some embodiments, the optional heat shield 316 may be disposed inside the vacuum vessel 306 such that the heat shield 316 encloses the superconducting field winding 308 and also helps maintain the temperature of the superconducting field winding 308 at an ultra-low temperature.

[0041] Additionally, in some embodiments, the fixed field 302 may include one or more torque tubes 318 disposed within the vacuum vessel 306. In some embodiments, the torque tubes 318 may be disposed annularly within the vacuum vessel 306. As an example, in embodiments in which a heat shield 316 is included, the torque tubes 318 may be disposed adjacent to one or more walls of the heat shield 316. In particular, while some torque tubes 318 may be disposed within the heat shield 316, some other torque tubes 318 may be disposed outside the heat shield. In embodiments in which a heat shield 316 is not included, the torque tubes 318 may be disposed adjacent to one or more of the sidewalls 326 and the outer wall 324 of the vacuum vessel 306.

[0042] The torque tube 318 is configured to support a reaction torque due to the interaction between the magnetic field generated by the armature 304 and the magnetic field generated by the superconducting field winding 308 .

[0043] Reference now Figure 5 According to one embodiment of the present disclosure, for operating Figure 1 Flowchart 400 of a method for wind turbine 100. Figures 1 to 4 describe Figure 5 . Figure 5 The method includes operating a wind turbine 100 having a superconducting generator 114, 200 at step 402, the superconducting generator 114, 200 including an armature 204, 304 having an armature winding 320 and a fixed field 202, 302 having a superconducting field winding 208, 308. As previously described, the superconducting field winding 208, 308 is disposed in a vacuum vessel 306, the vacuum vessel 306 being configured to have an inner wall 322 and an outer wall 324, the inner wall 322 being formed of one of a non-magnetic material or a paramagnetic material, and the outer wall 324 being formed of a low carbon steel or a light carbon steel. The superconducting field winding 208, 308 is disposed concentrically with the armature 204, 304 and radially outward from the armature 204, 304.

[0044] In particular, including a vacuum vessel 306 constructed at least in part of light carbon steel or low carbon steel provides a more cost-effective vacuum vessel, thereby reducing the overall cost of the superconducting generator. As previously described, the vacuum vessel 306 also provides increased magnetic flux near the superconducting field winding ends 309 and provides partial magnetic shielding.

[0045] The step 402 of operating the wind turbine 100 includes imparting rotation to the armature 204, 304 of the superconducting generator 114, 200 via the rotor 104 of the wind turbine 100, as indicated by step 404. The rotor 104 of the wind turbine 100 is mechanically coupled to the armature 204, 304 of the superconducting generator 114, 200 such that rotation of the rotor 104 due to wind energy results in rotation of the armature 204, 304 of the superconducting generator 114, 200.

[0046] Additionally, step 402 of operating wind turbine 100 includes cooling superconducting field windings 208, 308 to ultra-low temperatures via cooling device 314, as indicated by step 406. A cooling fluid, such as liquid helium, hydrogen, neon, or a combination thereof, may be cooled and circulated through one or more conduits 312 inside stationary field 202, 302 via cooling device 314 to maintain superconducting field windings 208, 308 at ultra-low temperatures such that the material of superconducting field windings 308 is superconducting.

[0047] According to embodiments described herein, improved superconducting generators such as superconducting generators 114, 200, and wind turbines including the improved superconducting generators, such as wind turbine 100, are provided. The improvements in superconducting generators 114, 200 and wind turbine 100 can be achieved at least in part due to the inclusion of a vacuum vessel 306 constructed at least in part of light carbon steel or low carbon steel as disclosed herein according to embodiments of the present disclosure. The inclusion of a vacuum vessel 306 as described herein provides a more cost-effective vacuum around the superconducting field windings, i.e., a means for enhancing the magnetic field near the ends of the field windings and passively providing a degree of magnetic shielding. By forming the vacuum vessel 306 from cost-effective materials, the overall cost of the superconducting generator is reduced.

[0048] Furthermore, since the vacuum vessel 306 is constructed with a thinner inner wall 322 compared to its outer wall 324 , structural loads / forces acting inside and outside the superconducting generator 114 , 200 may be compensated.

[0049] This written description uses examples to disclose the invention, including preferred embodiments, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to a person skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that are indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are slightly different from the literal language of the claims. A person of ordinary skill in the art may mix and match aspects of the various embodiments described, as well as other known equivalents of each such aspect, to construct additional embodiments and techniques according to the principles of the present application.

Claims

1. A superconducting generator, comprising: an armature configured to rotate via a shaft; a fixed field disposed concentrically with the armature and radially outward from the armature, wherein the fixed field comprises: superconducting field windings; and a vacuum container comprising an inner wall facing the armature, an opposite outer wall, and a plurality of side walls connecting the inner wall and the outer wall, wherein the superconducting field winding is arranged in the vacuum container, wherein the inner wall comprises one of a non-magnetic material or a paramagnetic material, and wherein the opposing outer walls comprise ferromagnetic material, Wherein, the ferromagnetic material includes light carbon steel.

2. The superconducting generator according to claim 1, wherein: The light carbon steel comprises between 0.04% and 0.30% carbon.

3. The superconducting generator according to claim 1, wherein: The light carbon steel has a magnetic permeability of μ / μ0~100-10,000, where μ0=magnetic permeability of free space, μ=absolute magnetic permeability of the medium, and μ / μ0=relative magnetic permeability.

4. The superconducting generator according to claim 1, wherein: The light carbon steel is one of SAE-AISI 1010, SAE-AISI 1020 or ASTM A36.

5. The superconducting generator according to claim 1, wherein: The non-magnetic material and the paramagnetic material have a magnetic permeability of μ / μ0~1.0-2.0, where μ0=magnetic permeability of free space, μ=absolute magnetic permeability of the medium, and μ / μ0=relative magnetic permeability.

6. The superconducting generator according to claim 3, wherein: The non-magnetic material and the paramagnetic material include stainless steel.

7. The superconducting generator according to claim 1, wherein: The superconducting field winding is configured to generate a magnetic field oriented in a radial direction of the superconducting generator.

8. The superconducting generator according to claim 1, wherein: The plurality of sidewalls include one of the ferromagnetic material, the non-magnetic material, or the paramagnetic material.

9. The superconducting generator according to claim 1, wherein: The inner wall of the vacuum container is thinner than the outer wall.

10. The superconducting generator according to claim 1, wherein: The fixed field further comprises a heat shielding portion which is arranged inside the vacuum container and encloses the superconducting field winding.

11. A wind turbine comprising: a rotor comprising a plurality of blades; a shaft coupled to the rotor; and a superconducting generator coupled to the rotor via the shaft, wherein the superconducting generator comprises: an armature configured to rotate via a shaft; a fixed field disposed concentrically with the armature and radially outward from the armature, wherein the fixed field comprises: superconducting field windings; and A vacuum container comprising an inner wall made of one of a non-magnetic material or a paramagnetic material facing the armature, an opposite outer wall made of a ferromagnetic material, and a plurality of side walls connecting the inner wall and the opposite outer wall, wherein the superconducting field winding is arranged in the vacuum container, Wherein, the ferromagnetic material includes light carbon steel.

12. The wind turbine of claim 11, wherein: The light carbon steel has a magnetic permeability of μ / μ0~100-10,000, where μ0=magnetic permeability of free space, μ=absolute magnetic permeability of the medium, and μ / μ0=relative magnetic permeability.

13. The wind turbine of claim 12, wherein: The light carbon steel is one of SAE-AISI 1010, SAE-AISI 1020 or ASTM A36.

14. The wind turbine of claim 11, wherein: The non-magnetic material and the paramagnetic material have a magnetic permeability of μ / μ0~1.0-2.0, where μ0=magnetic permeability of free space, μ=absolute magnetic permeability of the medium, and μ / μ0=relative magnetic permeability.

15. The wind turbine of claim 14, wherein: The non-magnetic material and the paramagnetic material include stainless steel.

16. The wind turbine of claim 11, wherein: The inner wall is thinner than the outer wall.

17. A method comprising: operating a wind turbine having a superconducting generator, the superconducting generator including an armature having an armature winding and a stationary field having a superconducting field winding, the superconducting field winding being disposed in a vacuum vessel, the vacuum vessel being configured to have an inner wall composed of one of a non-magnetic material or a paramagnetic material and an opposing outer wall composed of a ferromagnetic material, the superconducting field winding being further disposed concentrically with the armature winding and radially outward from the armature winding, The vacuum vessel thereby provides an increased magnetic flux near the ends of the superconducting field windings and provides partial magnetic shielding, Wherein, the ferromagnetic material includes light carbon steel.

18. The method according to claim 17, wherein: Operating the wind turbine includes imparting rotation to an armature of the superconducting generator via a rotor of the wind turbine.

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