Cooling systems for superconducting generators

Abstract

The electric machine includes a shaft, a support structure circumferentially disposed about the shaft and defining a circumferential surface, a plurality of conductive coils secured to the support structure, and a cooling system. The cooling system includes an inlet manifold for supplying cooling fluid to the electric machine, an outlet manifold for removing cooling fluid from the electric machine, and at least one passageway in fluid communication with the inlet manifold and the outlet manifold. The at least one passageway is disposed between two adjacent conductive coils of the plurality of conductive coils. The at least one passageway defines an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section. The turn section defines a length such that the inlet section and the outlet section are disposed in contact with each other along their respective lengths, thereby reducing the electrical conductivity of the at least one passageway. These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure.

Description

[Technical Field]

[0001] The present disclosure relates generally to cooling systems, and more particularly to cooling systems for superconducting generators. [Background technology]

[0002] Wind power is considered one of the cleanest and most environmentally friendly energy sources currently available, and in this regard, wind turbines have become a popular choice. Modern wind turbines typically include a tower, a generator, a gearbox, a nacelle, and a rotatable hub to which one or more rotor blades are attached. The rotor blades are typically attached to the hub via their respective pitch bearings, which allow each rotor blade to rotate around its pitch axis. The rotor blades capture the kinetic energy of the wind using the well-known airfoil principle. For example, rotor blades typically have an airfoil cross-section. During operation, air flows over the rotor blades, creating a pressure difference on either side of the blade. This results in a lift force acting on each rotor blade, from the pressure side to the suction side. This lift force generates torque on the main rotor shaft, which can drive a generator directly or be transmitted to a generator via gears to generate electricity.

[0003] Generally, a generator or motor (collectively referred to herein as a rotating electric machine) includes a plurality of conductive coils for generating a static or rotating magnetic field, and at least one armature coil for generating a rotating or stationary magnetic field associated with the movement of the armature which interacts with the magnetic field from the conductive coils.

[0004] Such rotating electric machines typically utilize alternating magnetic poles formed by the conductive coils of the field winding. That is, north poles are positioned between south poles, creating a regular north, south, north, south, etc. magnetic field pattern. This alternating polarity is created by the conductive coils of the field winding, which are made of conductors carrying currents in opposite directions. The magnetic field generated by the field coils interacts with the magnetic poles of the conductive coils of the armature, producing torque. Torque is created by the interaction of two magnetic fields that tend to align. The magnitude of the torque is related to the strength of the magnetic field and the radius over which the fields interact.

[0005] Many such generators also include a cooling system to assist in cooling the conductive coils to maintain the conductive coils and surrounding insulation at an appropriate temperature.

[0006] A generator cooling system may require multiple mechanical connections to efficiently cool each conductive coil. However, as the number of mechanical connections increases, the likelihood of failure of the entire cooling system may increase. Furthermore, the manufacturing costs of the mechanical connections may increase the overall manufacturing costs of the generator.

[0007] Furthermore, because such cooling systems are located near other components of the generator, they may also experience increased heat. This increased heat can occur when magnetic flux passes through the cooling system, generating eddy currents within the cooling system. These eddy currents can cause currents to flow along the cooling system. These currents can increase the overall resistance of the cooling system (especially the materials used to construct the cooling system). The increased resistance increases the thermal load on the cooling system. The increased thermal load can heat the cooling system and reduce its overall ability to cool components located outside of the cooling system. The reduced capacity of the cooling system can also make it difficult for the components to operate efficiently, as they may operate at suboptimal temperatures.

[0008] As a result, the industry continues to seek new and improved cooling systems for electrical generators that address the aforementioned problems. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 2022 / 190663 Summary of the Invention

[0010] Aspects and advantages of the present disclosure will be set forth in part in the description that follows, or will be obvious from the description, or may be learned through practice of the present disclosure.

[0011] In one aspect, the present disclosure relates to an electric machine. The electric machine includes a shaft, a support structure circumferentially disposed around the shaft and defining a circumferential surface, a plurality of conductive coils secured to the support structure, and a cooling system. The cooling system includes an inlet manifold for supplying cooling fluid to the electric machine, an outlet manifold for removing cooling fluid from the electric machine, and at least one passageway in fluid communication with the inlet manifold and the outlet manifold. The at least one passageway is disposed between two adjacent conductive coils of the plurality of conductive coils. The at least one passageway defines an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section. The turn section defines a length such that the inlet section and the outlet section are disposed in contact with each other along their respective lengths, thereby reducing the electrical conductivity of the at least one passageway. These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0012] In one embodiment, the support structure is the yoke of the armature or field assembly.

[0013] In another embodiment, the system further includes a first divider disposed along the length of each of the inlet manifold and the outlet manifold to separate flow between the inlet manifold and the outlet manifold.

[0014] In an additional embodiment, the first partition is constructed from a material having a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / m·K).

[0015] In another embodiment, the first partition is made of a non-metallic material.

[0016] In yet another embodiment, the cooling system further includes a cooling inlet and a cooling outlet, the cooling system defining modules, and at least one module connected to the cooling inlet and cooling outlet.

[0017] In other additional embodiments, the cooling inlet port is connected to an inlet manifold of the at least one module and the cooling outlet port is connected to an outlet manifold of the at least one module.

[0018] In other additional embodiments, the connections between the cooling inlet and outlet sections and the inlet and outlet manifolds include flexible connectors.

[0019] In yet another embodiment, the electric machine further includes a second partition disposed along the length of each of the inlet and outlet portions to separate flow between the inlet and outlet portions.

[0020] In yet another embodiment, the second partition is constructed from a material with a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / m·K).

[0021] In another embodiment, the second partition is made of a non-metallic material.

[0022] In an additional embodiment, the cooling fluid comprises at least one of water, coolant, antifreeze, gas, or combinations thereof.

[0023] In other embodiments, the inlet and outlet manifolds and the inlet and outlet sections are constructed from a conductive material.

[0024] In yet another embodiment, the cooling system further includes at least two passages in fluid communication with the inlet manifold and the outlet manifold, the at least two passages being disposed between two adjacent conductive coils of the plurality of conductive coils.

[0025] In another aspect, the present disclosure relates to a method for cooling an electric machine having a plurality of conductive coils, the method including disposing at least one passageway between two adjacent conductive coils of the plurality of conductive coils, the at least one passageway fluidly communicating with an inlet manifold for supplying a cooling fluid to the electric machine and an outlet manifold for removing the cooling fluid from the electric machine. The at least one passageway includes an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn-back section disposed between the inlet section and the outlet section. A length of the turn-back section is defined such that the inlet section and the outlet section are disposed in contact with each other along their respective lengths, providing electrical insulation between the inlet section and the outlet section. The method includes operating the inlet manifold and the outlet manifold to supply the cooling fluid to the at least one passageway to cool two adjacent conductive coils of the plurality of conductive coils.

[0026] In yet another aspect, the present disclosure relates to a wind turbine. The wind turbine includes a generator including a shaft, a support structure circumferentially disposed about the shaft and defining a circumferential surface, a plurality of conductive coils secured to the support structure, and a cooling system. The cooling system includes an inlet manifold for supplying cooling fluid to the generator, an outlet manifold for removing cooling fluid from the generator, and at least one passageway in fluid communication with the inlet manifold and the outlet manifold. The at least one passageway is disposed between two adjacent conductive coils of the plurality of conductive coils. The at least one passageway defines an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section. The turn section defines a length such that the inlet section and the outlet section are disposed in contact with each other along their respective lengths, thereby reducing the electrical conductivity of the at least one passageway. These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure. [Brief explanation of the drawings]

[0027] A full and enabling disclosure of the present disclosure, including the best mode thereof, shown to one of ordinary skill in the art is set forth in this specification, in which reference is made to the accompanying drawings.

[0028] [Figure 1] FIG. 1 is a side perspective view of an embodiment of a wind turbine having a generator according to the present disclosure. [Figure 2] FIG. 2 is an interior perspective view of one embodiment of a nacelle of the wind turbine of FIG. 1, particularly showing a generator housed in the nacelle according to the present disclosure. [Figure 3] 1 illustrates a perspective view of one embodiment of a generator according to the present disclosure. [Figure 4] 1 shows a schematic diagram of one embodiment of a cooling system for a generator according to the present disclosure. [Figure 5] 5 is a side view of the cooling system of FIG. 4, particularly showing the passages of the cooling system, in accordance with the present disclosure. [Figure 6] FIG. 2 is a schematic diagram illustrating another embodiment of a cooling system for a generator according to the present disclosure. [Figure 7] 7 is a side view of the cooling system of FIG. 6, particularly showing the passages of the cooling system, in accordance with the present disclosure. [Figure 8] 1 is a side view of yet another embodiment of a cooling system for a generator according to the present disclosure, particularly showing multiple passages of the cooling system. [Figure 9] FIG. 10 is a side view of yet another embodiment of a cooling system for a generator according to the present disclosure, particularly showing the passages of the cooling system. [Figure 10] 2 is a schematic diagram of another embodiment of a cooling system for a generator, particularly showing the connections of the individual cooling systems. [Figure 11] FIG. 1 is a flow diagram of one embodiment of a method for cooling a generator having multiple conductive coils in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0029] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, and not as a limitation of the disclosure. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still further embodiments. Accordingly, it is intended that the present disclosure cover all modifications and variations that come within the scope of the appended claims and their equivalents.

[0030] As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to denote the position or importance of the individual components.

[0031] Terms such as "coupled," "fixed," and "attached" refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein.

[0032] Approximate language, as used throughout this specification and claims, is applied to modify any quantitative expression that can be acceptably varied without resulting in a change in the basic function to which the quantitative expression relates. Thus, a value modified by one or more terms such as "approximately," "about," or "substantially" is not limited to the exact value specified. In at least some instances, approximate language corresponds to the precision of an instrument for measuring a value or the precision of a method or machine for constructing or manufacturing a component and / or system. For example, approximate language may express within a 10% margin.

[0033] Throughout this specification and claims, range limits are combined and interchangeable, and unless the context or language indicates otherwise, the ranges are specified and include all subranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0034] Generally, the present disclosure relates to energy conversion systems (such as wind power systems) that include electric machines (such as superconducting generators or motors). The present disclosure is described herein generally with respect to superconducting generators, and more particularly with respect to wind turbine superconducting generators, but is not limited to superconducting generators. For example, the present disclosure relates to a generator that includes a shaft, a support structure, a plurality of conductive coils, and a cooling system. The cooling system can include an inlet manifold for supplying cooling fluid to the generator, an outlet manifold for removing cooling fluid from the generator, and a passageway in fluid communication with the inlet manifold and the outlet manifold. Furthermore, the passageway can be disposed between two adjacent conductive coils of the plurality of coils.

[0035] Thus, an advantage of the present disclosure is that it reduces the total number of necessary mechanical connections required for a cooling system necessary to adequately cool a generator. Another advantage of the present disclosure is that the reliability of the cooling system may be improved because the total number of necessary mechanical connections is reduced. Furthermore, the overall manufacturing cost of the cooling system may be reduced because fewer parts and mechanical connections are required. Yet another advantage of the present disclosure is that the cooling system may be more resistant to temperature increases as a result of eddy currents forming within the cooling system.

[0036] Referring now to the drawings, FIG. 1 is a side perspective view of one embodiment of a wind turbine 100 having a superconducting generator 114 in accordance with the present disclosure. As shown, wind turbine 100 generally includes a tower 108 extending from a support surface, a nacelle 102 mounted to tower 108, and a rotor 104 coupled to nacelle 102. Rotor 104 includes a rotatable hub 110 and at least one rotor blade 112 (three rotor blades are shown in the figure) coupled to hub 110 and extending outwardly from hub 110. Each rotor blade 112 may be spaced relative to hub 110 and may rotate rotor 104 about axis of rotation 106 to convert kinetic energy from the wind into usable mechanical energy, and thus electrical energy. To this end, rotor 104 is coupled to generator 114 via a shaft (not shown). For purposes of the present disclosure, generator 114 is a direct-drive superconducting generator. Superconducting generators are distinguished from non-superconducting generators by having coils constructed of superconducting material ("superconductor") rather than ordinary conductive materials (e.g., copper, aluminum, etc.) that have electrical resistance. However, to place the superconducting material in a non-resistive superconducting state, the superconductor must be maintained below a certain temperature ("critical temperature"). Thus, improved cooling systems for, for example, non-superconducting coils would be particularly useful in superconducting generators because they would reduce the overall temperature of the generator and, therefore, minimize heat leakage to the superconducting coils. However, it should be understood that improved cooling systems are also useful in generators with non-superconducting coils.

[0037] Referring now to FIG. 2 , a simplified internal view of one embodiment of the nacelle 102 of the wind turbine 100 shown in FIG. 1 is shown in accordance with the present disclosure. As shown, the generator 114 is housed within the nacelle 102 and includes a field assembly 120 and an armature 118. Further as shown, the generator 114 is generally coupled to the rotor 104 to generate electrical power from rotational energy generated by the rotor 104. For example, as shown in the illustrated embodiment, the rotor 104 includes a rotor shaft 122 that is coupled to the hub 110 and may rotate therewith. The rotor shaft 122 may be rotatably coupled to the armature 118 of the generator 114. As commonly understood, the rotor shaft 122 may provide a torque input to the armature of the generator 114 in response to rotation of the rotor blades 112 and the hub 110. As shown, the armature 118 is located inside the field assembly 120 of the generator 114. However, it should be understood that the armature 118 may be located on the outside and the field assembly 120 on the inside.

[0038] In one embodiment, power may be generated using commonly known principles of induction by applying a torque input to the armature 118 of the generator 114. The armature 118 may rotate within a magnetic field provided by a field assembly 120 of the generator 114 (e.g., in an internal rotor configuration).

[0039] However, in other embodiments, the armature 118 of the generator 114 can be the outer component and the field assembly 120 of the generator 114 can be the inner component (e.g., in an external rotor configuration). Further, as shown, additional space can be defined between the outer and inner components to allow for movement (e.g., rotation) between the outer and inner components. It should be understood that in other embodiments, the armature 118 can be a stationary element that operates in a rotating magnetic field provided by the rotation of the field windings.

[0040] 2, the magnetic field generated by the armature 118 is due to the magnetomotive force (MMF) generated by the current flowing through the armature 118. The MMF has both spatial and temporal harmonics associated with it due to the separation of the coils and magnetic saturation in the steel structure.

[0041] Referring to FIG. 3 , a cutaway perspective view of one embodiment of a generator 114 according to the present disclosure is shown. In particular, as shown, the generator 114 may include a housing 116 for enclosing the generator's internal components (e.g., an armature 118, which may be described herein and secured to a rotor shaft 122, and a field assembly 120, which may be secured to the stationary housing 116). Further, as shown, the generator 114 may also include at least one winding set. For example, as shown, the winding set may include one or more conductors carrying electrical current formed into coils 124, which may be attached to a support structure 126. As shown, the support structure 126 may be circumferentially disposed around the rotor shaft 122 and define a circumferential surface. Further, the support structure 126 may be a yoke of the field assembly 120. Alternatively, if the armature 118 is located outside of the field assembly 120, the support structure 126 may be the circumferential surface of the armature 118.

[0042] Additionally, the coils 124 may be spaced apart from one another, with a space 128 between adjacent coils 124. By providing a space 128 between each coil 124, a resulting opposing magnetic field (e.g., a second common polarity) may be generated in that space 128 due to the natural law of conservation of magnetic flux generated by the coils 124.

[0043] 4 and 5 , various views of an embodiment of a cooling system 200 for a generator 114 in accordance with the present disclosure are shown. As shown, the cooling system 200 generally includes an inlet manifold 202, an outlet manifold 204, a passageway 208, and a core 206. Accordingly, in one embodiment, the inlet manifold 202 can be configured to supply a cooling fluid 210 to the generator 114. Additionally, the outlet manifold 204 can be configured to remove the cooling fluid 210 from the generator 114. The outlet manifold 204 can be positioned a length L1 away from the inlet manifold 202, forming a gap 209 between the outlet manifold 204 and the inlet manifold 202. The passageway 208 can be in fluid communication with the inlet manifold 202 and the outlet manifold 204. More specifically, as shown, the passageway 208 can be disposed between two adjacent coils 124 of the plurality of conductive coils 124. For example, if the generator 114 includes only two adjacent coils 124, one passageway 208 may be disposed between the two coils 124. Furthermore, if there are four or more coils 124 in the generator 114, two or more passageways 208 may be disposed between each pair of coils 124.

[0044] The passageways 208 may be constructed from a selection of materials useful in setting up a cooling system for the generator 114. For example, the passageways may be constructed from a metal (such as copper or aluminum), a metal alloy (such as a copper or aluminum alloy), a non-metallic material, or a combination thereof.

[0045] 5 , the passageway 208 may further include an inlet portion 212, an outlet portion 214, and a turn portion 216. The inlet portion 212 includes a fluid inlet 218 connected to the inlet manifold 202, from which the cooling fluid 210 may flow into the passageway 208. Similarly, the outlet portion 214 includes a fluid outlet 220 connected to the outlet manifold 204, from which the cooling fluid 210 may flow into the outlet manifold 204. In particular, as shown, the turn portion 216 generally represents a region of the passageway 208 disposed between the inlet portion 212 and the outlet portion 214.

[0046] Additionally, fluid inlet 218 and fluid outlet 220 may include connectors (such as flexible connectors). In such an embodiment, the flexible connectors may expand and / or contract with cooling system 200 as temperatures change within cooling system 200. Additionally, in one embodiment, forming fluid inlet 218 and fluid outlet 220 from flexible connectors may avoid effects on the connections between passageways 208 and inlet manifold 202 and / or outlet manifold 204 caused by expansion and / or contraction of cooling system 200.

[0047] 5, the fold portion 216 may define a length L2 such that a gap 222 is formed between the inlet portion 212 and the outlet portion 214, separating the inlet portion 212 and the outlet portion 214 from one another.

[0048] In further embodiments, the passageway 208 may also include one or more insulators 224 and one or more ground wires 226 disposed relative to the one or more insulators 224. Thus, as shown, the insulators 224 may be disposed in the inlet section 212, the outlet section 214, or both. The insulators 224 are particularly important when either the passageway 208 or the inlet and outlet manifolds 202, 204 are made of a conductive material, such as a metallic material, which has optimal heat transfer properties. For example, if the passageway 208 or the inlet and outlet manifolds 202, 204 are made of a conductive material, the insulators 224 can prevent current from flowing from the manifolds 202, 204 to the passageway 208 or from the passageway 208 to the manifolds 202, 204. This advantage is particularly important in relation to the characteristics of the cooling system 200. For example, if the cooling system 200 is constructed of a conductive material, the cooling system 200 may be located near the magnetic flux generated by the conductive coil 124, which may generate eddy currents. These eddy currents induce localized electrical losses in the material of the passages 208 or manifolds 202, 204, causing these components to heat up. Furthermore, because the passages 208 or manifolds 202, 204, respectively, are electrically conductive, when eddy currents are generated, the passages 208 or manifolds 202, 204 act as conductors, causing eddy currents to flow through and along the cooling system 200. This current flow increases the internal resistance of the cooling system 200 as the current flows through it, resulting in further increases in internal temperature. To address this issue, the insulator 224 is configured to block the path that current would otherwise flow through either the inlet or outlet manifolds 202, 204 and then throughout the cooling system 200.

[0049] Similarly, the insulator 224 and ground wire 226 can be located at either the inlet section 212 or the outlet section 214. Alternatively, the inlet section 212 and the outlet section 214 may be naturally electrically grounded through the means (not shown) to which the inlet section 212 and the outlet section 214 are attached within the generator 114. In this configuration, the ground wire 226 attached to 204 may not be needed.

[0050] Additionally, the ground wire 226 can be located in either the inlet manifold 202 or the outlet manifold 204. Alternatively, the inlet section 212, the outlet section 214, and the passageway 208 can be grounded at a single point through the ground wire 226. By arranging the ground wire 226 in any of the above configurations, a known voltage can be established across the inlet / outlet manifolds 202, 204 or the inlet / outlet sections 212, 214.

[0051] In additional embodiments, cooling fluid 210 may be any suitable cooling fluid, such as a cooling liquid (e.g., water, coolant, or an antifreeze compound such as propylene glycol), a cooling gas (e.g., air or hydrogen gas), or a combination thereof.

[0052] 6-7, various views of another embodiment of a cooling system 300 for a generator 114 according to the present disclosure are illustrated. As shown in the illustrated embodiment, the cooling system 300 may have similar components to the embodiment illustrated with reference to Figures 4 and 5. For example, the cooling system 300 may include a passageway 308 having an inlet portion 312, an outlet portion 314, and a turn portion 316.

[0053] However, in contrast to the embodiments of FIGS. 4 and 5, the inlet manifold 302 and the outlet manifold 304 are in contact with each other. Furthermore, a partition 306 can be disposed between the inlet manifold 302 and the outlet manifold 304. The partition 306 can be constructed of various materials, such as materials with particularly low thermal conductivity. For example, the material can be a metallic material such as steel, which has a thermal conductivity of 45 watts per meter per degree Kelvin (W / m·K) or less. Alternatively, the material can be a non-metallic material with a thermal conductivity much lower than that of steel. For example, the non-metallic material can be a polymeric material with a thermal conductivity of about 2% of that of steel, or about 0.6 W / m·K to about 1 W / m·K. By selecting a material for the partition 306, heat transfer from the outlet manifold 304 to the inlet manifold 302 can be reduced or prevented, even though the inlet manifold 302 and the outlet manifold are located close to each other.

[0054] In such an embodiment, the cooling system 300 can be made less conductive because the inlet manifold 302 is in contact with the outlet manifold 304, but the inlet manifold 302 and the outlet manifold 304 no longer exist as a conductive loop or circuit. This is because there is no path available for electrical currents that may be generated in either the inlet manifold 302 or the outlet manifold 304. Instead, eddy currents may be generated as magnetic flux passes through the material of the inlet manifold 302 and the outlet manifold 304, but because the manifolds 302, 304 are in contact with each other, the voltages at the inlet manifold 302 and the outlet manifold 304 remain at similar values. Because the voltages between the manifolds 302, 304 are similar, electrical currents cannot flow from the inlet manifold 302 to the outlet manifold 304 or from the outlet manifold 304 to the inlet manifold 302.

[0055] 7, the inlet section 312 and the outlet section 314 can be arranged to contact each other, similar to the inlet manifold 302 and the outlet manifold 304. A partition 318 can also be arranged between the inlet and outlet manifolds 304 to separate the flow. Similar to the configuration of the inlet manifold 302, the outlet manifold 304, and the partition 306, the inlet section 312, the outlet section 314, and the partition 318 can reduce the electrical conductivity of the passage 308. For example, by arranging the inlet section 312 and the outlet section 314 in contact with each other, the voltages of the inlet section 312 and the outlet section 314 can be similar or identical, thereby reducing or preventing current from flowing through the passage 308. Furthermore, similar to the partition 306, the partition 318 can be formed from a metallic material (e.g., steel) or a non-metallic material (e.g., a polymeric material) to reduce heat transfer from the outlet section 314 to the inlet section 312. Although divider 306 and divider 318 are described as separate components, it should be understood that divider 306 and divider 318 may be integrated with one another to form a single divider that separates both inlet manifold 302 and outlet manifold 304 from inlet section 312 and outlet section 314.

[0056] Referring now to FIG. 8 , a side view of yet another embodiment of a cooling system 400 having multiple passages 403, 405 is shown. In particular, as shown, the cooling system 400 may include a first passage 403 and a second passage 405. However, it should be understood that more than two passages may be disposed between two adjacent coils 124. Furthermore, as shown and described herein, both the first passage 403 and the second passage 405 may be connected to an inlet manifold 402 and an outlet manifold 404. One advantage of including the first passage 403 and the second passage 405 is that it may increase the mass flow rate of the cooling fluid, thereby increasing the overall cooling capacity for a given overall pressure between the inlet manifold 402 and the outlet manifold 404. Furthermore, as shown, the inlet section 412 and the outlet section 414 may be in contact with each other, and a partition section 406 may be disposed between the inlet section 412 and the outlet section 414, similar to the embodiments of FIGS. 6 and 7 .

[0057] 9, a side view of yet another embodiment of a cooling system 500 is shown having a single passageway 508 with an inlet section 512 and an outlet section 514 defined using a partition 506. As shown, the passageway 508 has two turn sections 516 so that cooling fluid entering from the inlet manifold 502 can flow through the passageway 508, return to the outlet manifold 504, and flow through the single passageway 508.

[0058] 10 , a schematic diagram of another embodiment of a cooling system is shown. As shown, cooling system 600 includes a cooling inlet section 604, a cooling outlet section 602, and a cooling module 606. Cooling module 606 may be any of cooling systems 200, 300, 400, 500, or 600 described above, or may include any of the cooling systems described above. For example, if cooling module 606 is cooling system 300, cooling inlet section 604 may be connected to inlet manifold 302 (inlet manifold 302 is connected to inlet section 312), and cooling outlet section 602 may be connected to outlet manifold 304 (outlet manifold 304 is connected to outlet section 314). Connection between each of these components may be achieved using a connector 608. Connector 608 may be a flexible connector similar to the flexible connectors used to form fluid inlet 218 and fluid outlet 220 of cooling system 200. Additionally, any number of cooling modules 606 may be included. Furthermore, when one or more cooling systems 600 are used with an electrical generator (such as generator 114), one or more cooling modules 606 may be positioned around the entire circumference of the generator. Providing cooling inlet section 604, cooling outlet section 602, and cooling module 606 in this manner may reduce the circumferential extent of cooling module 606, thereby facilitating manufacturing and placement of cooling module 606 (which may include cooling system 200, 300, 400, 500, or 600) within an electrical machine (such as generator 114).

[0059] Referring now to FIG. 11 , a flow diagram of one embodiment of a method 700 for cooling a generator having multiple conductive coils is shown. It should be understood that method 700 can be implemented using, for example, cooling systems 300, 400, 500, or 600 described herein with respect to FIGS. 4-10 . FIG. 11 shows steps performed in a particular order for purposes of illustration and discussion. Those skilled in the art, with the benefit of the disclosure provided herein, will understand that the various steps of method 700, or any other method disclosed herein, may be suitably altered, modified, rearranged, performed simultaneously, or altered in various ways without departing from the scope of the present disclosure.

[0060] As shown in (702), method 700 includes disposing at least one passageway between two adjacent conductive coils of the plurality of conductive coils. The passageway may be fluidly connected to an inlet manifold that supplies cooling fluid to the generator and an outlet manifold that removes cooling fluid from the generator. During this step, the at least one passageway may define an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn-back section disposed between the inlet and outlet sections. Further, the turn-back section disposed between the inlet and outlet sections may have a length such that the inlet and outlet sections contact each other along their respective lengths to provide electrical insulation. As shown in (704), method 700 further includes operating the inlet and outlet manifolds to supply cooling fluid to the passageway to cool two adjacent conductive coils of the plurality of conductive coils.

[0061] Various aspects and embodiments of the disclosure are defined by the following embodiments. [Embodiment 1] 1. An electric machine comprising: shaft, a support structure disposed circumferentially about said shaft and defining a circumferential surface; a plurality of conductive coils secured to the support structure; and 1. A cooling system comprising: an inlet manifold for supplying cooling fluid to the electric machine; an outlet manifold for removing cooling fluid from the electric machine; at least one passageway in fluid communication with the inlet manifold and the outlet manifold, the at least one passageway being disposed between two adjacent conductive coils of the plurality of conductive coils, the at least one passageway defining an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section; Cooling system including Including, the folded portion defines a length such that the inlet portion and the outlet portion are arranged to contact each other along the respective lengths of the inlet portion and the outlet portion, thereby reducing the conductivity of the at least one passageway. [Embodiment 2] 2. An electric machine as described in embodiment 1, wherein the support structure is an armature or a yoke of a field assembly. [Embodiment 3] 3. An electric machine as described in embodiment 1 or 2, further comprising a first partition disposed along the length of each of the inlet manifold and the outlet manifold to separate flow between the inlet manifold and the outlet manifold. [Embodiment 4] 4. The electric machine of embodiment 3, wherein the first partition is made of a material having a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / m·K). [Embodiment 5] 4. The electric machine of embodiment 3, wherein the first partition is made of a non-metallic material. [Embodiment 6] An electric machine as described in any one of embodiments 1 to 5, further comprising a cooling inlet section and a cooling outlet section, wherein the cooling system defines modules, and at least one module is connected to the cooling inlet section and the cooling outlet section. [Embodiment 7] 7. An electric machine as described in embodiment 6, wherein the cooling inlet portion is connected to an inlet manifold of the at least one module and the cooling outlet portion is connected to an outlet manifold of the at least one module. [Embodiment 8] 8. An electric machine as described in embodiment 7, wherein the connections between the cooling inlet and outlet sections and the inlet and outlet manifolds include flexible connectors. [Embodiment 9] 9. The electric machine of any one of embodiments 1 to 8, further comprising a second partition disposed along the length of each of the inlet and outlet sections to separate flow between the inlet and outlet sections. [Embodiment 10] 10. The electric machine of embodiment 9, wherein the second partition is made of a material having a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / m·K). [Embodiment 11] 10. The electric machine of embodiment 9, wherein the second partition is made of a non-metallic material. [Embodiment 12] 12. The electric machine of any one of embodiments 1 to 11, wherein the cooling fluid includes at least one of water, a coolant, an antifreeze, a gas, or a combination thereof. [Embodiment 13] 13. The electric machine of any one of embodiments 1 to 12, wherein the inlet and outlet manifolds and the inlet and outlet sections are made of an electrically conductive material. [Embodiment 14] An electric machine as described in any one of embodiments 1 to 13, wherein the cooling system further includes at least two passages in fluid communication with the inlet manifold and the outlet manifold, the at least two passages being arranged between two adjacent conductive coils among the plurality of conductive coils. [Embodiment 15] 1. A method of cooling an electric machine having a plurality of conductive coils, comprising: disposing at least one passage between two adjacent conductive coils of the plurality of conductive coils, the at least one passage being in fluid communication with an inlet manifold for supplying a cooling fluid to the electric machine and an outlet manifold for removing a cooling fluid from the electric machine, the at least one passage including an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn-back section disposed between the inlet section and the outlet section, the turn-back section having a length such that the inlet section and the outlet section are disposed in contact with each other along their respective lengths, such that electrical insulation is provided between the inlet section and the outlet section; and operating the inlet manifold and the outlet manifold to supply the cooling fluid to the at least one passage so as to cool two adjacent conductive coils of the plurality of conductive coils; A method comprising: [Embodiment 16] 16. The method of embodiment 15, further comprising disposing a first divider disposed along the length of each of the inlet and outlet manifolds to separate flow between the inlet and outlet sections. [Embodiment 17] 17. The method of claim 15 or 16, further comprising disposing a second partition disposed along the length of each of the inlet and outlet sections to separate the flow between the inlet and outlet sections. [Embodiment 18] 17. The method of claim 16, wherein the first partition comprises a non-metallic material, the non-metallic material having a thermal conductivity of less than about 45 watts per meter per Kelvin (W / m·K). [Embodiment 19] The method according to any one of embodiments 15 to 18, further comprising arranging at least two passages between two adjacent conductive coils of the plurality of conductive coils, the at least two passages being fluidly connected to an inlet manifold for supplying cooling fluid to the electric machine and an outlet manifold for removing the cooling fluid from the electric machine. [Embodiment 20] 1. A wind turbine comprising: a generator, the generator comprising: shaft, a support structure disposed circumferentially about said shaft and defining a circumferential surface; a plurality of conductive coils secured to the support structure; and 1. A cooling system comprising: an inlet manifold for supplying cooling fluid to the generator; an outlet manifold for removing cooling fluid from the generator; at least one passageway in fluid communication with the inlet manifold and the outlet manifold, the at least one passageway being disposed between two adjacent conductive coils of the plurality of conductive coils, the at least one passageway defining an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section; Cooling system including Including, the folded portion defines a length such that the inlet portion and the outlet portion are arranged to contact each other along the respective lengths of the inlet portion and the outlet portion, thereby reducing the electrical conductivity of the at least one passageway.

[0062] The description herein uses examples to disclose the present disclosure, including the best mode, and will enable any person skilled in the art to practice the disclosure, including making and using devices or systems, and performing the incorporated methods. The patentable scope of the disclosure 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 have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ insubstantial from the literal language of the claims. [Explanation of symbols]

[0063] 100 wind turbines 102 Nacelle 104 rotor 106 Rotation axis 108 Tower 110 Hub 112 rotor blades 114 Generator 116 Stationary Housing 118 Armature 120 Field assembly 122 rotor shaft 124 Conductive Coil 126 Support Structure 128 Space 200 Cooling System 202 Inlet manifold 204 Outlet manifold 206 cores Passage 208 209 Gap 210 Cooling fluid 212 Entrance 214 Exit section 216 Turn-back section 218 Fluid Inlet 220 Fluid outlet 222 Gap 224 Insulator 226 Ground wire 300 Cooling System 302 Inlet manifold 304 Outlet Manifold 306 Partition 308 Passage 312 Entrance 314 Exit section 316 Turn-back section 318 Partition 400 Cooling System 402 inlet manifold 403 First Passage 404 Outlet Manifold 405 Second Passage 406 Partition 412 Entrance 414 Exit section 500 Cooling System 502 inlet manifold 504 Outlet manifold 506 Partition 508 Passage 512 Entrance 514 Exit section 516 Turned part 600 Cooling System 602 Cooling outlet section 604 Cooling inlet section 606 Cooling Module 608 Connector 700 methods

Claims

1. 1. An electric machine comprising: shaft, a support structure disposed circumferentially about said shaft and defining a circumferential surface; a plurality of conductive coils secured to the support structure; and 1. A cooling system comprising: an inlet manifold for supplying cooling fluid to the electric machine; an outlet manifold for removing cooling fluid from the electric machine; at least one passageway in fluid communication with the inlet manifold and the outlet manifold, the at least one passageway being disposed between two adjacent conductive coils of the plurality of conductive coils, the at least one passageway defining an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section; Cooling system including Including, the folded portion defines a length such that the inlet portion and the outlet portion are arranged to contact each other along the respective lengths of the inlet portion and the outlet portion, thereby reducing the conductivity of the at least one passageway.

2. The electric machine of claim 1 , wherein the support structure is an armature or a yoke of a field assembly.

3. The electric machine of claim 1 , further comprising a first divider disposed along a length of each of the inlet manifold and the outlet manifold to separate flow between the inlet manifold and the outlet manifold.

4. The electric machine of claim 3 , wherein the first partition is constructed from a material having a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / m·K).

5. The electric machine of claim 3 , wherein the first partition is constructed of a non-metallic material.

6. The electric machine of claim 1 , further comprising a cooling inlet and a cooling outlet, the cooling system defining modules, and at least one module connected to the cooling inlet and cooling outlet.

7. The electric machine of claim 6 , wherein the cooling inlet is connected to an inlet manifold of the at least one module and the cooling outlet is connected to an outlet manifold of the at least one module.

8. The electric machine of claim 7 , wherein connections between the cooling inlet and outlet sections and the inlet and outlet manifolds include flexible connectors.

9. The electric machine of claim 1 , further comprising a second partition disposed along the length of each of the inlet and outlet sections to separate flow between the inlet and outlet sections.

10. The electric machine of claim 9 , wherein the second partition is constructed from a material having a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / m·K).

11. The electric machine of claim 9 , wherein the second partition is constructed from a non-metallic material.

12. The electric machine of claim 1 , wherein the cooling fluid comprises at least one of water, a coolant, an antifreeze, a gas, or a combination thereof.

13. The electric machine of claim 1 , wherein the inlet and outlet manifolds and the inlet and outlet sections are constructed from an electrically conductive material.

14. 2. The electric machine of claim 1, wherein the cooling system further includes at least two passages in fluid communication with the inlet manifold and the outlet manifold, the at least two passages being disposed between two adjacent conductive coils of the plurality of conductive coils.

15. 1. A method of cooling an electric machine having a plurality of conductive coils, comprising: disposing at least one passage between two adjacent conductive coils of the plurality of conductive coils, the at least one passage being in fluid communication with an inlet manifold for supplying a cooling fluid to the electric machine and an outlet manifold for removing a cooling fluid from the electric machine, the at least one passage including an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn-back section disposed between the inlet section and the outlet section, the turn-back section having a length such that the inlet section and the outlet section are disposed in contact with each other along their respective lengths, and disposing the at least one passage such that electrical insulation is provided between the inlet section and the outlet section; operating the inlet manifold and the outlet manifold to supply the cooling fluid to the at least one passage so as to cool two adjacent conductive coils of the plurality of conductive coils; A method comprising:

16. 16. The method of claim 15, further comprising disposing a first divider disposed along a length of each of the inlet and outlet manifolds to separate flow between the inlet and outlet portions.

17. 16. The method of claim 15, further comprising disposing a second divider disposed along the length of each of the inlet and outlet sections to separate the flow between the inlet and outlet sections.

18. 17. The method of claim 16, wherein the first partition comprises a non-metallic material, the non-metallic material having a thermal conductivity of less than about 45 watts per meter per degree Kelvin (W / mK).

19. 16. The method of claim 15, further comprising disposing at least two passages between two adjacent conductive coils of the plurality of conductive coils, the at least two passages being in fluid communication with an inlet manifold for supplying cooling fluid to the electric machine and an outlet manifold for removing the cooling fluid from the electric machine.

20. 1. A wind turbine comprising: a generator, the generator comprising: shaft, a support structure disposed circumferentially about said shaft and defining a circumferential surface; a plurality of conductive coils secured to the support structure; and 1. A cooling system comprising: an inlet manifold for supplying cooling fluid to the generator; an outlet manifold for removing cooling fluid from the generator; at least one passageway in fluid communication with the inlet manifold and the outlet manifold, the at least one passageway being disposed between two adjacent conductive coils of the plurality of conductive coils, the at least one passageway defining an inlet section including a fluid inlet in fluid communication with the inlet manifold, an outlet section including a fluid outlet in fluid communication with the outlet manifold, and a turn section disposed between the inlet section and the outlet section; Cooling system including Including, the folded portion defines a length such that the inlet portion and the outlet portion are arranged to contact each other along the length of each of the inlet portion and the outlet portion, thereby reducing the electrical conductivity of the at least one passageway.

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