Superconducting rotating machine and its cooling method

Abstract

To simplify a cooling structure.SOLUTION: A superconductive rotating machine 100 comprises a superconduction field winding 22 in a rotator 21. The rotator is housed in a non-rotational container (a three-layer cylindrical container 30) having a three-layer cylindrical structure of a vacuum case 31, a radiation shield 32, and a gas container 33 from an outer layer side, and is connected to a rotational shaft (a shaft 41) via a torque tube 40. In the gas container, a heat exchange gas 99 is sealed, a first heat exchanger 51 is provided to the radiation shield and the torque tube. A second heat exchanger 52 is provided between the superconduction field winding and the gas container. The first heat exchanger and the second heat exchanger are heat-exchanged by heat transmission of the heat exchange gas sealed into the gas container.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a superconducting rotating machine and a method for cooling the same. [Background technology]

[0002] Conventionally, superconducting field windings, commonly referred to as "superconducting coils," have been used in devices in various fields. For example, in devices such as magnetic resonance imaging (MRI) and nuclear magnetic resonance spectroscopy (NMR), superconducting field windings are used as a means of generating magnetic fields. Superconducting field windings are windings composed of superconducting wires that can conduct large currents when cooled to a temperature below the critical temperature.

[0003] In addition to devices such as magnetic resonance imaging (MRI) and nuclear magnetic resonance spectroscopy (NMR), superconducting field windings are also used as a means of generating magnetic fields in rotating machines such as generators and electric motors. Hereinafter, rotating machines that use superconducting field windings as a means of generating magnetic fields will be referred to as "superconducting rotating machines."

[0004] Among superconducting rotating machines, there is a configuration in which a superconducting field winding fixed to a shaft is placed inside a vacuum-insulated container, and the superconducting field winding is rotated together with the shaft (see, for example, Patent Document 1). In this configuration, the superconducting field winding is cooled to a temperature below the critical temperature by supplying an extremely low-temperature refrigerant into the shaft from an external cooling station (cold head or cooling means not shown in Patent Document 1). At that time, the temperature of the refrigerant rises due to heat exchange with the rotor, but it is returned to the external cooling station and cooled. Gaseous helium or neon are used as refrigerants. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2005-528867 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, devices such as magnetic resonance imaging (MRI) systems and nuclear magnetic resonance spectrometers (NMR) use superconducting field windings in non-rotating components. In contrast, superconducting rotating machines use superconducting field windings in the rotor component. Such superconducting rotating machines cool the superconducting field windings by circulating cryogenic coolant between an external cooling station and the rotor. As a cooling structure, such superconducting rotating machines have a rotating coupling on the shaft to introduce the cryogenic coolant into the rotor, or a pump in the cooling station to transfer the cryogenic coolant. Compared to magnetic resonance imaging (MRI) systems and nuclear magnetic resonance spectrometers (NMR), such superconducting rotating machines have a more complex cooling structure, which presents challenges such as difficulty in cooling the superconducting field windings and a tendency for reliability to decrease.

[0007] This invention was made to solve the aforementioned problems, and its main objective is to provide a superconducting rotating machine with a simplified cooling structure and a method for cooling the same. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a superconducting rotating machine, wherein a superconducting field winding is provided on the rotor, the rotor is housed in a non-rotating container having a three-layer cylindrical structure consisting of a vacuum container, a radiation shield, and a gas container from the outer layer side, and is connected to a rotating shaft via a torque tube, a heat exchange gas is sealed in the gas container, a first heat exchanger is provided between the radiation shield and the torque tube, a second heat exchanger is provided between the superconducting field winding and the gas container, and the first heat exchanger and the second heat exchanger are configured to exchange heat by heat conduction of the heat exchange gas sealed in the gas container. Other methods will be described later. [Effects of the Invention]

[0009] According to the present invention, the cooling structure can be simplified. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the superconducting rotating machine according to Embodiment 1. [Figure 2A] This is a log-log graph showing pressure (InP) and thermal conductivity (Inλ) under cryogenic conditions. [Figure 2B] This is a log-log graph of pressure InP and windage loss InW under cryogenic conditions. [Figure 3] This is a schematic diagram of the heat exchange section in a heat exchanger. [Figure 4] This is a schematic diagram of the heat exchange section in a modified example of a heat exchanger. [Figure 5] This figure shows an example of a structural member configuration that achieves both high thermal conductivity and low eddy current loss. [Figure 6] This is a schematic diagram of the superconducting rotating machine according to Embodiment 2. [Figure 7] This is a schematic diagram of the superconducting rotating machine according to Embodiment 3. [Figure 8] This is a schematic diagram of a comparative example of a superconducting rotating machine. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention (hereinafter referred to as "these embodiments") will be described in detail with reference to the drawings. Note that each figure is merely a schematic representation to the extent necessary for a thorough understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. Furthermore, in each figure, common or similar components are denoted by the same reference numerals, and their redundant descriptions are omitted.

[0012] [Embodiment 1] <Configuration of a superconducting rotating machine> The configuration of the superconducting rotating machine 100 according to this embodiment 1 will be described below with reference to Figure 1. Figure 1 is a schematic diagram of the superconducting rotating machine 100 according to this embodiment 1.

[0013] The superconducting rotating machine 100 according to this embodiment is a rotating machine provided with a superconducting field winding 22 on a rotor 21. The superconducting rotating machine 100 according to this embodiment is suitable for, for example, a large-scale device in the megawatt class.

[0014] As shown in FIG. 1, the superconducting rotating machine 100 according to Embodiment 1 has a three-layer cylindrical container 30 inside a casing 10 fixedly installed at an arbitrary location. The three-layer cylindrical container 30 is a non-rotating container that does not rotate. The three-layer cylindrical container 30 has a vacuum container 31, a radiation shield 32, and a gas container 33 in order from the outside. The vacuum container 31 and the radiation shield 32 are containers that maintain the internal space at a high vacuum. The gas container 33 is a container in which a heat exchange gas 99 is enclosed inside.

[0015] The vacuum container 31, the radiation shield 32, and the gas container 33 each have a cylindrical shape. However, the vacuum container 31, the radiation shield 32, and the gas container 33 do not have to be truly cylindrical shapes, and may be, for example, shapes with irregularities provided at arbitrary portions. Also, in the example shown in FIG. 1, the radiation shield 32 and the gas container 33 have shapes in which both axial ends extend in the axial direction. Further, the radiation shield 32 may have a shape in which a portion for housing a first heat exchanger 51 described later is widened.

[0016] The radiation shield 32 partitions the space between the vacuum container 31 and the gas container 33 into an outer space and an inner space. In the space between the vacuum container 31 and the gas container 33, the space outside the radiation shield 32 is maintained at a temperature in a medium temperature region of about 50 K [Kelvin], for example. Also, the space inside the radiation shield 32 is maintained at a temperature in an inner cryogenic region of about 10 K [Kelvin], for example.

[0017] A rotor 21 is located inside the gas container 33. The rotor 21 has a superconducting field winding 22 and a field support 23 that supports the superconducting field winding 22. A superconducting wire is used for the superconducting field winding 22. A superconducting wire is a wire that can conduct large currents when cooled to a temperature below its critical temperature. The superconducting field winding 22 is cooled to an extremely low temperature by a two-stage GM refrigerator 60 and becomes superconducting, allowing it to conduct large currents with zero resistance.

[0018] The rotor 21 is connected to the shaft 41, which is the axis of rotation, via the torque tube 40, and rotates together with the shaft 41. The shaft 41 is rotatably supported by a bearing 42. The shaft 41 extends from the axial end plate (side plate) of the outer casing 10 to the outside world via the bearing 42, and transmits power to the outside world. The heat exchange gas 99 is sealed by a magnetic fluid seal 43 near the bearing 42. The torque tube 40 and the shaft 41 are configured to be in contact with the heat exchange gas 99 sealed in the gas container 33.

[0019] In the cylindrical portion of the radiation shield 32, a first heat exchanger 51 is installed between the radiation shield 32 and the torque tube 40. Furthermore, at the axial end of the gas container 33, a second heat exchanger 52 is installed between the superconducting field winding 22 and the gas container 33. In the example shown in Figure 1, the second heat exchanger 52 is located at the right axial end between the superconducting field winding 22 and the gas container 33, but it may also be located at the left axial end or at both axial ends. The first heat exchanger 51 and the second heat exchanger 52 exchange heat through the heat conduction of the heat exchange gas 99 sealed in the gas container 33.

[0020] Furthermore, an armature support 13, which supports the armature winding 12 (stator winding), is positioned between the outer casing 10 and the vacuum container 31, and the armature support 13 is supported by the iron core 11.

[0021] A two-stage GM refrigerator 60 is installed at the axial end of the three-layer cylindrical container 30. The two-stage GM refrigerator 60 is a GM (Gifford-McMahon) refrigerator that has two stages, a first stage 61 and a second stage 62, and cools both stages. Hereinafter, the two-stage GM refrigerator may be simply referred to as the "two-stage refrigerator". As shown in Figure 1, it is preferable to have multiple two-stage GM refrigerators 60. Furthermore, it is preferable that the multiple two-stage GM refrigerators 60 be installed at equal intervals on a circle centered on the shaft 41 at the axial end of the three-layer cylindrical container 30.

[0022] The first stage 61 of the two-stage GM refrigerator 60 is connected to the axial end of the radiation shield 32 and conduction-cools the first heat exchanger 51. In other words, in the superconducting rotating machine 100, the radiation shield 32 side of the first heat exchanger 51 is conduction-cooled by the first stage 61 of the two-stage GM refrigerator 60. By cooling the first heat exchanger 51, the first stage 61 of the two-stage GM refrigerator 60 indirectly cools the superconducting field winding 22. In addition, the second stage 62 of the two-stage GM refrigerator 60 is connected to the gas container 33 and conduction-cools the second heat exchanger 52. In other words, in the superconducting rotating machine 100, the gas container 33 side of the second heat exchanger 52 is conduction-cooled by the second stage 62 of the two-stage GM refrigerator 60. By cooling the second heat exchanger 52, the second stage 62 of the two-stage GM refrigerator 60 indirectly cools the torque tube 40. The first stage 61 is a cooling unit that cools to a medium temperature range of, for example, 50 K [Kelvin]. The second stage 62 is a cooling unit that cools to an extremely low temperature range of, for example, 10 K [Kelvin].

[0023] The first heat exchanger 51 and the second heat exchanger 52 are composed of opposing metal plates with excellent thermal conductivity, such as oxygen-free copper. A heat exchange gas 99 is interposed between the opposing metal plates of the first heat exchanger 51 and the second heat exchanger 52, and heat exchange occurs between the opposing metal plates by the heat exchange gas 99.

[0024] The midpoint between the radiation shield 32, the first heat exchanger 51, and the torque tube 40 is cooled to a temperature close to that of the first stage 61 of the two-stage GM refrigerator 60, for example, about 50 Kelvin. In addition, the superconducting field winding 22, field support 23, gas container 33, and second heat exchanger 52 are cooled to a temperature close to that of the second stage 62 of the two-stage GM refrigerator 60, for example, about 10 Kelvin.

[0025] The space outside the gas container 33 and inside the vacuum container 31 is maintained at a high vacuum, enhancing the thermal insulation between the three-layer cylindrical container 30 (vacuum container 31, radiation shield 32, and gas container 33).

[0026] The torque tube 40 and shaft 41 incorporate magnetic current input terminals 46 for introducing current from an external power source to the superconducting field winding 22. For the magnetic current input terminals 46, it is preferable to use high-temperature superconducting current leads that have low thermal conductivity and zero resistance, allowing for the passage of large currents, in order to suppress heat intrusion from the outside into the low-temperature area. The ends of the magnetic current input terminals 46 utilize slip rings and carbon brushes, enabling the introduction of current to the rotor 21 from the outside. Copper conductors are used for the armature winding 12. The armature winding 12 is located in a room-temperature environment outside the vacuum chamber 31.

[0027] A technique for cooling magnetic resonance imaging (MRI) devices using a GM refrigerator has been proposed. However, this technique for cooling MRI devices using a GM refrigerator is difficult to apply to the superconducting rotating machine 100 because it relies on cooling via gas and does not take into account the position of the heat exchanger.

[0028] <Structure of the comparative example> In order to clearly explain the features of the superconducting rotating machine 100 according to this embodiment 1, we will first describe the configuration of the comparative example superconducting rotating machine 1000 with reference to Figure 8, and then describe the features of the superconducting rotating machine 100 according to this embodiment 1. The comparative example superconducting rotating machine 1000 shown in Figure 8 corresponds to a conventional general superconducting rotating machine.

[0029] As shown in Figure 8, the comparative example superconducting rotating machine 1000 has a vacuum vessel 1031 inside an outer casing 1010 that is fixedly installed at any location. The vacuum vessel 1031 is a vessel that maintains a high vacuum in its internal space.

[0030] A rotor 1021 is located inside the vacuum vessel 1031. The rotor 1021 has a superconducting field winding 1022 and a field support 1023 that supports the superconducting field winding 1022. A superconducting wire is used for the superconducting field winding 1022.

[0031] The rotor 1021 is housed in a vacuum vessel 1031 and connected to the rotating shaft 1041 via a torque tube 1040. The rotor 1021 (superconducting field windings 1022 and field support 1023), the vacuum vessel 1031, and the torque tube 1040 rotate as a single unit. The shaft 1041 is rotatably supported by a bearing 1042. The shaft 1041 extends from the axial end face plate (side plate) of the outer casing 1010 to the outside world via the bearing 1042, transmitting power to the outside world. Inside the torque tube 1040 and the shaft 1041, there is a flow path for circulating cryogenic coolant 1099 between the externally located cooling station 1080 and the rotor 1021. In the comparative example, the superconducting rotating machine 1000 cools the superconducting field winding 1022 by supplying a coolant 1099 from an external cooling station 1080 into the torque tube 1040 and shaft 1041. The shaft 1041 is also equipped with a coolant introduction rotary coupling 1083 for introducing the coolant 1099 into the rotor 1021. The cooling station 1080 is also equipped with a pump 1081 for transferring the coolant.

[0032] Between the outer casing 1010 and the vacuum container 1031, an armature support 1013 is positioned to support the armature winding 1012 (stator winding), and the armature support 1013 is supported by the iron core 1011.

[0033] The superconducting field winding 1022 is insulated from the vacuum vessel 1031, which is at room temperature, by being cooled to an extremely low temperature by the refrigerant 1099 circulating between the vacuum vessel 1031 and the cooling station 1080, as the internal space of the vacuum vessel 1031 is a high vacuum.

[0034] The torque tube 1040 and shaft 1041 incorporate magnetic current input terminals 1046 for introducing current from an external power source to the superconducting field winding 1022. For example, high-temperature superconducting current leads are used for the magnetic current input terminals 1046. The ends of the magnetic current input terminals 1046 use slip rings and carbon brushes, allowing current to be introduced to the rotor 1021 from the outside. High-purity copper conductors are used for the armature winding 1012. The comparative example superconducting rotary machine 1000 allows refrigerant 1099 to be supplied to the rotor 1021 by a refrigerant input rotary coupling 1083. The refrigerant 1099 circulates between the external cooling station 1080 and the rotor 1021 and is constantly maintained at an extremely low temperature by a GM refrigerator 1082 located in the cooling station 1080.

[0035] <Features of the superconducting rotating machine according to Embodiment 1 compared to the superconducting rotating machine of the comparative example> The following describes the features of the superconducting rotating machine 100 according to this embodiment 1 compared to the comparative example superconducting rotating machine 1000.

[0036] In the comparative example, the superconducting rotating machine 1000 circulates a coolant 1099 between the external cooling station 1080 and the rotor 1021. This coolant GM refrigerator 1082 installed in the cooling station 1080 continuously removes heat generated in the cryogenic region within the vacuum vessel 1031 and heat entering from the external environment, thereby maintaining a cryogenic environment that allows the superconducting state of the superconducting field winding 1022 to be maintained (see Figure 8).

[0037] On the other hand, in the superconducting rotating machine 100 according to this embodiment 1, the first heat exchanger 51 and the second heat exchanger 52 are cooled by a two-stage GM refrigerator 60. Then, heat exchange occurs between the first heat exchanger 51 and the second heat exchanger 52 through the heat conduction of the heat exchange gas 99 sealed in the gas container 33, thereby maintaining an extremely low temperature environment in which the superconducting state of the superconducting field winding 22 can be maintained (see Figure 1).

[0038] Generally, a GM chiller is a device that transfers heat from a low-temperature section to a high-temperature section (removes heat), and its operation consumes electricity. The coefficient of performance (COP) of a GM chiller is calculated by dividing the cooling capacity by the power consumption required for operation, and it decreases as the cooling temperature decreases. Typical performance (COP) of commercially available GM chillers is, for example, around 0.0002 at 4K [Kelvin], 0.002 at 10K [Kelvin], 0.007 at 20K [Kelvin], and 0.02 at 50K [Kelvin]. In order to remove heat from the cryogenic section with such a GM chiller, the power consumption is greater than the cooling capacity. Since the power consumption of a GM chiller represents a loss for a rotating machine, it is desirable to suppress heat generation in the cryogenic section and heat intrusion from the outside.

[0039] In this regard, the comparative example superconducting rotating machine 1000 has a configuration that makes it susceptible to external heat intrusion and Joule heating in the cooling section in the cryogenic region, as will be explained below. Furthermore, the comparative example superconducting rotating machine 1000 has a configuration that makes it susceptible to heat intrusion by radiation, as will be explained below. Specifically, the comparative example superconducting rotating machine 1000 has a configuration in which the rotational force of the rotor 1021 is transmitted to the shaft 1041 by the torque tube 1040. In such a comparative example superconducting rotating machine 1000, it is desirable to make the torque tube 1040 robust. However, if the cross-sectional area of ​​the torque tube 1040 is increased to make it robust, the torque tube 1040 becomes the main heat intrusion path from the outside. In addition, although a high-temperature superconducting current lead is used for the magnetic current introduction terminal 1046 inside the torque tube 1040, a high-purity copper conductor is used in the part that is hotter than its critical temperature, so there is a possibility that external heat intrusion and Joule heating will penetrate into the cooling section in the cryogenic region. Therefore, the comparative example superconducting rotating machine 1000 is configured to be susceptible to external heat intrusion and Joule heating. Here, the "cooling section in the cryogenic region" refers to a space that should be cooled to, for example, about 10 K [Kelvin]. The superconducting field winding 1022, which should be cooled to about 10 K [Kelvin], is located in the "cooling section in the cryogenic region". Furthermore, the comparative example superconducting rotating machine 1000 does not have means to cool the torque tube 1040 and the shaft 1041. Therefore, in this respect as well, the comparative example superconducting rotating machine 1000 is configured to be susceptible to external heat intrusion and Joule heating. Moreover, although the comparative example superconducting rotating machine 1000 has a vacuum insulation layer between the superconducting field winding 1022 and the armature winding 1012 by arranging the rotor 1021 inside the vacuum vessel 1031, there is a possibility that heat may penetrate into the space where the superconducting field winding 1022 is located due to radiation. Therefore, the comparative example superconducting rotating machine 1000 has a configuration that makes it susceptible to the effects of heat intrusion due to radiation.

[0040] On the other hand, the superconducting rotating machine 100 according to this embodiment 1 is configured to be less susceptible to external heat intrusion and Joule heating in the cooling section of the cryogenic region, as will be explained below. Furthermore, the superconducting rotating machine 100 according to this embodiment 1 is configured to be less susceptible to heat intrusion by radiation, as will be explained below. Specifically, the superconducting rotating machine 100 according to this embodiment 1 has a first heat exchanger 51 and a second heat exchanger 52 inside a non-rotating three-layer cylindrical container 30. The superconducting rotating machine 100 according to this embodiment 1 uses a two-stage GM refrigerator 60 to cool the first heat exchanger 51 and the second heat exchanger 52, with the first heat exchanger 51 being used as a cooling section of the medium temperature region cooled to a temperature of about 50 K [Kelvin] and the second heat exchanger 52 being used as a cooling section of the cryogenic region cooled to a temperature of about 10 K [Kelvin]. In this regard, for example, the comparative example superconducting rotating machine 1000 (see Figure 8) does not have a cooling section for the medium temperature range, so radiant heat from room temperature, heat entering from the outside through the torque tube 1040, and heat entering from the outside through the magnetic current introduction terminal 1046, as well as Joule heating, can all potentially enter the aforementioned "cooling section for the cryogenic range". Therefore, the comparative example superconducting rotating machine 1000 is configured to be easily affected by heat entering from the outside and Joule heating. In contrast, the superconducting rotating machine 100 according to this embodiment 1 (see Figure 1) has the first heat exchanger 51 as a cooling section for the medium temperature range. Therefore, the superconducting rotating machine 100 according to this embodiment 1 receives radiant heat from room temperature, heat entering from the outside through the torque tube 40, and heat entering from the outside through the magnetic current introduction terminal 46, as well as Joule heating, in the cooling section for the medium temperature range, thereby removing heat from the cooling section for the medium temperature range. The superconducting rotating machine 100 according to this embodiment 1 is configured to be less susceptible to external heat intrusion and Joule heating. Furthermore, in the superconducting rotating machine 100 according to this embodiment 1, the torque tube 40 and shaft 41 are in contact with the heat exchange gas 99 that is cooled when the first heat exchanger 51 and the second heat exchanger 52 are cooled by the two-stage GM refrigerator 60. Therefore, the superconducting rotating machine 100 according to this embodiment 1 has means for cooling the torque tube 40 and shaft 41.Therefore, in this respect as well, the superconducting rotating machine 100 according to this embodiment 1 is configured to be less susceptible to the effects of heat intrusion from the outside and Joule heating. Furthermore, the superconducting rotating machine 100 according to this embodiment 1 is provided with a radiation shield 32 and a gas container 33 inside the vacuum container 31, suppressing the intrusion of heat into the space where the superconducting field winding 22 is located due to radiation. Therefore, the superconducting rotating machine 100 according to this embodiment 1 is configured to be less susceptible to the effects of heat intrusion due to radiation.

[0041] Furthermore, the superconducting rotating machine 100 according to this embodiment 1 can reduce power consumption and perform highly efficient cooling compared to the comparative example superconducting rotating machine 1000, as described below. Specifically, the superconducting rotating machine 100 according to this embodiment 1 is equipped with a cooling section for the medium temperature range and has a structure that removes heat entering from the cooling section for the medium temperature range. In such a superconducting rotating machine 100 according to this embodiment 1, the power consumption of the two-stage GM refrigerator 60 associated with heat removal from the cooling section for the cryogenic range of about 10 K [Kelvin] is 500 times the cooling capacity. On the other hand, the power consumption of the two-stage GM refrigerator 60 associated with heat removal from the cooling section for the medium temperature range of about 50 K [Kelvin] is about 50 times the cooling capacity. Thus, the superconducting rotating machine 100 according to this embodiment 1 can reduce power consumption and perform highly efficient cooling compared to the comparative example superconducting rotating machine 1000.

[0042] Furthermore, the comparative example superconducting rotating machine 1000 cools the refrigerant 1099 with a GM refrigerator 1082, removing heat generation in the cryogenic cooling section and heat intrusion from the outside with a single refrigerant 1099. The coefficient of performance (COP) of a refrigerator decreases as the cooling temperature decreases. Therefore, the comparative example superconducting rotating machine 1000 tends to have a low coefficient of performance (COP) for the refrigerator. In contrast, the superconducting rotating machine 100 according to this embodiment 1 cools the first heat exchanger 51 and the second heat exchanger 52 with a two-stage GM refrigerator 60, thereby cooling the cooling section in the medium temperature range and the cooling section in the cryogenic range. The superconducting rotating machine 100 according to this embodiment 1 can improve the coefficient of performance (COP) of the refrigerator compared to the comparative example superconducting rotating machine 1000.

[0043] Furthermore, the comparative example superconducting rotating machine 1000 has an external cooling station 1080, which increases the installation area and cost. Also, the comparative example superconducting rotating machine 1000 has a mechanism for circulating a cryogenic coolant such as a pump 1081, which also increases the cost. In contrast, the superconducting rotating machine 100 according to this embodiment 1 does not have an external cooling station 1080, thus reducing the installation area and cost. Also, the superconducting rotating machine 100 according to this embodiment 1 does not require a pump 1081, which further reduces the cost.

[0044] Furthermore, as a cooling structure for a superconducting rotating machine, a structure with two circulation mechanisms for low-temperature and medium-temperature refrigerants can be considered. However, such a structure requires the provision of two gas circulation paths within the torque tube 40. Since magnetic current introduction terminals 46 are also installed inside the torque tube 40, the internal structure of the torque tube 40 becomes complex, worsening manufacturability. In contrast, the superconducting rotating machine 100 according to this embodiment 1 does not have two circulation mechanisms for low-temperature and medium-temperature refrigerants, thus simplifying the internal structure of the torque tube 40 and suppressing the deterioration of manufacturability.

[0045] From the above comparison, the superconducting rotating machine 100 according to this embodiment 1 can improve cooling efficiency and eliminate the complex refrigerant circulation mechanism and cooling station 1080 found in the comparative example superconducting rotating machine 1000. Therefore, the superconducting rotating machine 100 according to this embodiment 1 can reduce the installation area and improve reliability. Furthermore, by improving the cooling efficiency, the superconducting rotating machine 100 according to this embodiment 1 can lower the operating temperature of the superconducting field winding 22. As a result, the superconducting rotating machine 100 according to this embodiment 1 can improve the critical current density in the high magnetic field region of the superconducting field winding 22, thereby improving the gap magnetic flux density, making the rotating machine smaller and lighter, and reducing the amount of superconducting wire used, thus lowering costs.

[0046] In the comparative example, the superconducting rotating machine 1000 has a configuration in which the superconducting field winding 1022 and the vacuum vessel 1031 housing the superconducting field winding 1022 rotate together. In contrast, in the superconducting rotating machine 100 according to this embodiment 1, although the superconducting field winding 22 rotates, the gas vessel 33 housing the superconducting field winding 22 is fixed. In view of this, it is preferable that the superconducting rotating machine 100 according to this embodiment 1 has a configuration that takes into account the following points (1) and (2).

[0047] (1) The superconducting rotating machine 100 according to this embodiment 1 is preferably configured to take windage losses into consideration. Specifically, the superconducting rotating machine 100 is preferably configured such that the pressure of the heat exchange gas 99 is reduced below atmospheric pressure in a range in which heat transfer by gas molecular conduction is dominant over radiation. This point will be explained with reference to Figures 2A and 2B.

[0048] Figure 2A is a log-log graph of pressure InP and thermal conductivity Inλ under cryogenic conditions. The solid line L1 shows the relationship between pressure InP and thermal conductivity Inλ under cryogenic conditions. Pressure region P1 is dominated by heat conduction by radiation. Pressure region P2 is dominated by heat conduction by gas molecules. When radiation is present, the thermal conductivity (heat transfer) improves further than that of the solid line L1, as shown by the dashed line L1a.

[0049] Figure 2B is a log-log graph of pressure InP and windage loss InW under cryogenic conditions. The solid line L2 shows the relationship between pressure InP and windage loss InW under cryogenic conditions. Windage loss InW is an increasing function of pressure InP.

[0050] In the superconducting rotating machine 100 according to this embodiment 1, the superconducting field winding 22 and the gas container 33 are in relative motion, and windage loss due to the heat exchange gas 99, which does not occur in the comparative example superconducting rotating machine 1000, occurs in the cooling section in the cryogenic region. Effective countermeasures include reducing the pressure of the heat exchange gas 99 to an extent that suppresses windage loss while maintaining its role as a heat exchange gas 99, and further increasing the heat exchange area of ​​the heat exchanger. Windage loss is suppressed by pressure reduction. On the other hand, in heat exchange in a heat exchanger, radiation is dominant in the region where the pressure of the heat exchange gas 99 is extremely low (for example, below 1 Pa) (see pressure region P1 in Figure 2A). Furthermore, in the region where the pressure is increased to a certain extent (for example, above 10 Pa), gas molecular conduction becomes dominant in heat exchange in a heat exchanger, and the pressure dependence disappears (see pressure region P2 in Figure 2A). Furthermore, in the region where the pressure is increased, radiation becomes dominant in heat exchange in a heat exchanger, and it becomes a function of increasing pressure.

[0051] The difference in pressure dependence shown in Figures 2A and 2B indicates that the superconducting rotating machine 100 can suppress windage losses while maintaining heat conduction (heat transfer) by keeping the pressure as low as possible within the range where heat conduction (heat transfer) by gas molecular conduction is dominant (especially by reducing the pressure below atmospheric pressure).

[0052] The superconducting rotating machine 100 according to this first embodiment can maintain a certain degree of heat exchange while suppressing windage losses by making the pressure of the heat exchange gas 99 in a region where gas molecular conduction is dominant. In this case, increasing the heat exchange area of ​​the heat exchanger is also effective. Figure 3 is a schematic diagram of the heat exchange section 70A in the first heat exchanger 51 and the second heat exchanger 52. In the example shown in Figure 3, the heat exchange section 70A is configured by arranging a first structure 71a and a second structure 72a opposite each other, and attaching a pair of heat exchangers 73a to the first structure 71a and the second structure 72a. The pair of heat exchangers 73a are opposing plates made of a material with high thermal conductivity. The heat exchange section 70A exchanges heat between the first structure 71a and the second structure 72a via the heat exchange gas 99 filled between the pair of heat exchangers 73a.

[0053] The heat exchange section 70A shown in Figure 3 can be modified, for example, to the heat exchange section 70B shown in Figure 4. Figure 4 is a schematic diagram of the heat exchange section 70B in a modified example of the first heat exchanger 51 and the second heat exchanger 52. In the example shown in Figure 4, the heat exchange section 70B is configured by arranging a first structure 71b and a second structure 72b opposite each other, and attaching a pair of heat exchangers 73b to the first structure 71b and the second structure 72b. The pair of heat exchangers 73b are opposing comb-shaped members made of a material with high thermal conductivity. By making the shape of the heat exchangers 73b comb-shaped, the heat exchange area of ​​the heat exchangers 73b can be increased in the heat exchange section 70B, and the amount of heat exchanged can be significantly increased compared to the heat exchange section 70A shown in Figure 3.

[0054] (2) The superconducting rotating machine 100 according to this embodiment 1 is preferably configured to take into account the eddy currents generated in the three-layer cylindrical container 30. Specifically, the superconducting rotating machine 100 preferably has fiber-reinforced composite material applied to at least a part of the vacuum container 31, the radiation shield 32, or the gas container 33. This point will be explained below.

[0055] The alternating magnetic field generated by the rotating superconducting field winding 22 is applied to a three-layer cylindrical container 30, which is a multilayer cylindrical structure consisting of a vacuum container 31, a radiation shield 32, and a gas container 33. If the vacuum container 31 and gas container 33 are made of a metal material such as stainless steel, and the radiation shield 32 is made of a highly thermally conductive metal material such as aluminum, eddy currents will be generated in these metal materials. In particular, if eddy currents are generated in the radiation shield 32 and gas container 33, which are in the low-temperature region, Joule heating will occur, making heat removal difficult. Therefore, in the superconducting rotating machine 100 according to this embodiment 1, it is preferable that at least a part of one of the vacuum container 31, radiation shield 32, or gas container 33 is made of a fiber-reinforced composite material. For example, in the superconducting rotating machine 100 according to this embodiment 1, it is preferable to apply glass fiber reinforced composite material (GFRP) to the gas container 33 and vacuum container 31 where suppression of eddy current generation is required, and carbon fiber reinforced resin composite material (CFRP) to the radiation shield 32 where high thermal conductivity is required.

[0056] Furthermore, as shown in Figure 5, the superconducting rotating machine 100 according to this embodiment 1 can also improve thermal conductivity while suppressing eddy currents by attaching high thermal conductivity nanowires 77 to the fiber-reinforced composite material 76 in a direction perpendicular to the direction Ai (current direction) in which eddy currents flow. The high thermal conductivity nanowires 77 are thin metal wires having relatively high thermal conductivity.

[0057] <Remarks> The superconducting rotating machine 100 according to this embodiment 1 has a configuration that takes the following matters into consideration.

[0058] For example, rotating machines such as generators and electric motors are widely used in fields such as industry, transportation, and power generation as systems that convert electricity into rotational force. Generally, the torque T and output P of a rotating machine are given by the following equations (1) and (2).

[0059] T = k1·L·D 2 ·B g ·I …(1) P = k²·L·D 2 ·B g ·I·n …(2)

[0060] Here, T is the torque of the rotating machine, I is the output of the rotating machine, k1 and k2 are constants, L is the stator length, D is the rotor outer diameter, B g is the gap magnetic flux density, I is the electrical load (total current per unit circumference of the armature winding), and n is the rotational speed.

[0061] Incidentally, in the transportation sector in particular, including electric vehicles, electric propulsion ships, and electric aircraft, the electrification of power is progressing in order to reduce greenhouse gas emissions, which is referred to as "carbon neutrality." In this electrification of power, it is desirable to improve the torque density and power density of rotating machinery. And in order to improve the torque density and power density of rotating machinery, the gap magnetic flux density B g Improving this is effective.

[0062] Generally, the gap magnetic flux density B gCopper windings or permanent magnets are used in the field, which is the source of the magnetic flux density. g As a means of further improving this, superconducting field windings are sometimes used as the field. Since superconducting wires can conduct large currents when cooled below their critical temperature, using superconducting field windings as the field makes it possible to generate an extremely strong magnetic field.

[0063] In devices such as magnetic resonance imaging (MRI) systems and nuclear magnetic resonance spectroscopy (NMR) systems, superconducting field windings are cooled by immersion in a liquid coolant such as helium or by conduction cooling. Cryogenic refrigerators, such as GM (Gifford-McMahon) refrigerators, are used for recondensation of the evaporating coolant and heat removal by conduction cooling. In MRI systems, NbTi wires, for which mass production technology is already established, are primarily used, while Nb3Sn wires, capable of generating higher magnetic fields, are also used in nuclear magnetic resonance spectroscopy systems. Furthermore, in recent nuclear magnetic resonance spectroscopy systems, copper oxide high-temperature superconductivity (HTS) wires, such as rare-earth or bismuth-based wires, are sometimes used to generate even higher magnetic fields. Low-temperature superconducting (LTS) wires such as NbTi and Nb3Sn have low critical temperatures, and even copper oxide superconducting wires can generate stronger magnetic fields by lowering the operating temperature. Therefore, they are commonly used in magnetic resonance imaging (MRI) and nuclear magnetic resonance spectroscopy (NMR) systems cooled to 4 Kelvin.

[0064] On the other hand, in superconducting rotating machines, the field is usually the rotor, and the superconducting field windings that rotate as the rotor are cooled. Cooling the superconducting field windings in such superconducting rotating machines is more difficult compared to magnetic resonance imaging (MRI) or nuclear magnetic resonance spectroscopy (NMR) systems.

[0065] Low-temperature superconducting (LTS) wires with a low critical temperature have a small amount of heat (energy margin) required for the transition to the resistive state. Therefore, even a slight mechanical disturbance, such as the sliding of wires on the order of micrometers or cracks in the impregnated resin in winding, may cause a quench (a phenomenon in which a superconducting conductor during energization suddenly and uncontrollably transitions to the normal conducting state due to thermal, electromagnetic, or mechanical factors). For this reason, great care must be taken when applying them to superconducting rotating machines with a harsher operating environment compared to magnetic resonance imaging (MRI) devices and nuclear magnetic resonance spectroscopy (NMR) devices. In addition, since the coefficient of performance (COP) of cryogenic refrigerators decreases as the cooling temperature decreases, it is preferable to increase the operating temperature of superconducting rotating machines. Therefore, in recent years, the development of superconducting rotating machines using copper oxide high-temperature superconducting (HTS) wires with a high critical temperature that can be used at 20 - 77 K [Kelvin] has been underway. Also, magnesium diboride (MgB2) wires, whose critical temperature is in the middle between LTS wires and copper oxide HTS wires, are also used.

[0066] When the cooling temperature increases due to the application of copper oxide HTS wires, the COP increases and the difficulty of cooling decreases. However, at present, copper oxide HTS wires are more costly and have a shorter single length compared to LTS wires. Therefore, cost reduction and elongation of the wires remain as issues.

[0067] Magnesium diboride (MgB2) wires are superior to LTS wires in that they can be used at around 20 K. However, even when used at 20 K, compared to copper oxide HTS wires, the upper critical magnetic field is low, and it is difficult to generate a strong magnetic field at an operating temperature of at least around 20 K. To generate a high gap magnetic flux density B g for an electric motor using a permanent magnet as the field magnet, it is preferable to cool it to a lower temperature (e.g., 10 K), and compared to copper oxide HTS wires, the difficulty of cooling increases.

[0068] Thus, in superconducting rotating machines, it is necessary to cool the rotating superconducting field windings, which is more difficult to cool than in magnetic resonance imaging (MRI) or nuclear magnetic resonance spectroscopy (NMR) systems. Furthermore, even when using superconducting materials that can be used at higher temperatures, such as copper oxide high-temperature superconductivity (HTS) wires or magnesium diboride (MgB2) wires, there is a trade-off between the cost, productivity, and operating temperature of each type of superconducting wire. In this context, in order to commercialize superconducting rotating machines, it is desirable to be able to easily cool the superconducting field windings to lower temperatures.

[0069] The superconducting rotating machine 100 according to this embodiment 1 has a configuration that takes these matters into consideration. The main features of the superconducting rotating machine 100 according to this embodiment 1 are as follows. (1) The system is equipped with a cooling section for the medium temperature range (first heat exchanger 51) that cools to a temperature of about 50 K [Kelvin] and a cooling section for the cryogenic range (second heat exchanger 52) that cools to a temperature of about 10 K [Kelvin]. (2) The rotor 21 is housed inside a non-rotating container (three-layer cylindrical container 30). (3) A radiation shield 32 is placed inside the vacuum vessel 31 to suppress heat from entering the space where the superconducting field winding 22 is located due to radiation. (4) The heat exchange between the first heat exchanger 51 and the second heat exchanger 52 is performed by heat exchange gas 99 sealed in a gas container 33.

[0070] As described above, the superconducting rotating machine 100 according to this embodiment 1 (see Figure 1) has a first heat exchanger 51 as a cooling section for the medium temperature range and a second heat exchanger 52 as a cooling section for the cryogenic temperature range inside a three-layer cylindrical container 30 which is a non-rotating container, and the first heat exchanger 51 and the second heat exchanger 52 are cooled by a two-stage GM refrigerator 60. Compared to the superconducting rotating machine 1000 of the comparative example (see Figure 8), the superconducting rotating machine 100 according to this embodiment 1 does not require gas introduction from the cooling station 1080 to the rotor 1021 via the refrigerant introduction rotary coupling 83, and the cooling structure can be simplified. Furthermore, the reliability can be improved by simplifying the cooling structure.

[0071] Furthermore, the superconducting rotating machine 100 according to this embodiment 1 can remove heat ingress from the outside at an intermediate temperature that improves the coefficient of performance (COP) of the refrigerator, thanks to the first heat exchanger 51 which serves as a cooling unit in the medium temperature range. Therefore, the superconducting rotating machine 100 according to this embodiment 1 can cool the rotor 21 more efficiently than the superconducting rotating machine 1000 of the comparative example. As a result, the superconducting field winding 22 can be cooled to a lower temperature, improving the current characteristics of the superconducting field winding 22 and enabling the rotating machine to be made smaller and lighter.

[0072] [Embodiment 2] The superconducting rotating machine 100 according to Embodiment 1 described above (see Figure 1) is configured to indirectly cool the torque tube 40 and the superconducting field winding 22 by cooling the first heat exchanger 51 and the second heat exchanger 52 with a two-stage GM refrigerator 60. However, the superconducting rotating machine 100 can be configured without using the two-stage GM refrigerator 60 if the torque tube 40 and the superconducting field winding 22 can be cooled.

[0073] Therefore, in this second embodiment, a superconducting rotating machine 100A is provided that does not use a two-stage GM refrigerator 60.

[0074] The configuration of the superconducting rotating machine 100A according to this second embodiment will be described below with reference to Figure 6. Figure 6 is a diagram showing the configuration of the superconducting rotating machine 100A according to this second embodiment.

[0075] As shown in Figure 6, the superconducting rotating machine 100A according to this second embodiment differs from the superconducting rotating machine 100 according to the first embodiment (see Figure 1) in that it is equipped with a cooling station 80, a first circulation path 81, and a second circulation path 82 instead of a two-stage GM refrigerator 60.

[0076] The cooling station 80 is a cooling mechanism located away from (outside) the rotor 21. The cooling station 80 is equipped with a refrigerator (not shown). The first circulation path 81 is a flow path connecting the radiant shield 32 side of the first heat exchanger 51 in the three-layer cylindrical container 30 to the cooling station 80. Inside the first circulation path 81, for example, a medium-temperature circulating gas 81a with a temperature of approximately 50 K [Kelvin] flows. The second circulation path 82 is a flow path connecting the gas container 33 side of the second heat exchanger 52 inside the three-layer cylindrical container 30 to the cooling station 80. A low-temperature circulating gas 82a, for example, with a temperature of approximately 10 K [Kelvin], flows through the second circulation path 82.

[0077] In this second embodiment, the superconducting rotating machine 100A cools the medium-temperature circulating gas 81a and the low-temperature circulating gas 82a in a refrigerator (not shown) located in a cooling station 80 at a location (external) away from the rotor 21. The superconducting rotating machine 100A circulates the medium-temperature circulating gas 81a between the radiation shield 32 side of the first heat exchanger 51 and the cooling station 80 via a first circulation path 81. As a result, the superconducting rotating machine 100A circulates the first heat exchanger 51 to a temperature of approximately 50 K [Kelvin], thereby indirectly cooling the torque tube 40. The superconducting rotating machine 100A circulates the low-temperature circulating gas 82a between the gas container 33 side of the second heat exchanger 52 and the cooling station 80 via a second circulation path 82. As a result, the superconducting rotating machine 100A according to this second embodiment cools the second heat exchanger 52 to a temperature of approximately 10 K [Kelvin], thereby indirectly cooling the superconducting field winding 22.

[0078] According to the superconducting rotating machine 100A of this second embodiment, the cooling structure can be simplified, similar to the superconducting rotating machine 100 of the first embodiment.

[0079] [Embodiment 3] The superconducting rotating machine 100 according to Embodiment 1 described above (see Figure 1) is configured to cool the first heat exchanger 51 and the second heat exchanger 52 with a two-stage GM refrigerator 60.

[0080] In contrast, this third embodiment provides a superconducting rotating machine 100B configured to cool the first heat exchanger 51 and the second heat exchanger 52 using separate refrigerators with different operating temperatures.

[0081] The configuration of the superconducting rotating machine 100B according to this third embodiment will be described below with reference to Figure 7. Figure 7 is a diagram showing the configuration of the superconducting rotating machine 100B according to this third embodiment.

[0082] As shown in Figure 7, the superconducting rotating machine 100B according to this third embodiment differs from the superconducting rotating machine 100 according to the first embodiment (see Figure 1) in that it is equipped with a medium-temperature side refrigerator 91 and a low-temperature side refrigerator 92 instead of a two-stage GM refrigerator 60.

[0083] The intermediate-temperature chiller 91 is the first chiller that cools the first heat exchanger 51. The low-temperature chiller 92 is a second chiller that cools the second heat exchanger 52. The low-temperature chiller 92 cools the second heat exchanger 52 to a temperature of approximately 10 K [Kelvin].

[0084] According to the superconducting rotating machine 100B of this third embodiment, the cooling structure can be simplified, similar to the superconducting rotating machine 100 of the first embodiment.

[0085] The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace some of the configurations of the embodiments with other configurations, and it is also possible to add other configurations to the configurations of the embodiments. In addition, it is possible to add, delete, or replace some of the configurations of each configuration with other configurations. [Explanation of symbols]

[0086] 10,1010 Outer covering 11,1011 Iron core 12,1012 Armature winding 13,1013 Armature support 21,1021 rotor 22,1022 Superconducting field winding (field winding) 23,1023 Field support 30. Three-layer cylindrical container (non-rotating container) 31,1031 Vacuum container 32 Radiation Shield 33 Gas containers 40,1040 Torque Tube 41,1041 Shaft (rotating axis) 42,1042 bearings 43 Magnetic Fluid Seals 46,1046 Magnetic current introduction terminal 51 1st heat exchanger 52 Second heat exchanger 60 2-stage GM refrigerator (2-stage refrigerator) 61 Stage 1 62 Stage 2 70A,70B Heat exchange section 71a,71b 1st structure 72a,72b 2nd structure 73a,73b Heat exchanger 76 Fiber-reinforced composite materials 77. High thermal conductivity nanowire (metal wire) 80 Cooling Stations 81 1st circulation route 82 Second circulation route 81a Medium temperature circulating gas 82a Low-temperature circulating gas 91 Medium-temperature refrigerator (first refrigerator) 92 Low-temperature side refrigerator (second refrigerator) 99 Heat exchange gas 100, 100A, 100B, 1000 Superconducting Rotating Machine 1080 Cooling Station 1081 Pump 1082 GM refrigerator 1083 Refrigerant Inlet Rotary Connector (Rotary Connector) 1099 Refrigerant Ai: Direction of eddy current flow (current direction)

Claims

1. Equipped with superconducting field windings on the rotor, The rotor is housed within a non-rotating container having a three-layer cylindrical structure consisting of a vacuum container, a radiation shield, and a gas container from the outer layer side, and is connected to the rotating shaft via a torque tube. The aforementioned gas container is filled with heat exchange gas. A first heat exchanger is installed between the radiation shield and the torque tube. A second heat exchanger is provided between the superconducting field winding and the gas container. The first heat exchanger and the second heat exchanger exchange heat through the heat conduction of the heat exchange gas sealed in the gas container. A superconducting rotating machine characterized by the following features.

2. A superconducting rotating machine according to claim 1, A two-stage refrigerator is inserted into the aforementioned vacuum container. The first stage of the two-stage refrigerator conducts cooling the radiant shield side of the first heat exchanger. The second stage of the two-stage refrigerator cools the gas container side of the second heat exchanger by conduction. A superconducting rotating machine characterized by the following features.

3. A superconducting rotating machine according to claim 1, It is equipped with two refrigerant flow paths at different temperatures. The higher temperature refrigerant cools the radiant shield side of the first heat exchanger. A cooler refrigerant cools the gas container side of the second heat exchanger. A superconducting rotating machine characterized by the following features.

4. A superconducting rotating machine according to claim 1, The pressure of the heat exchange gas is reduced below atmospheric pressure to a degree where heat transfer by gas molecular conduction is dominant over radiation. A superconducting rotating machine characterized by the following features.

5. A superconducting rotating machine according to claim 1, A fiber-reinforced composite material is applied to at least a portion of the vacuum vessel, the radiation shield, or the gas vessel. A superconducting rotating machine characterized by the following features.

6. A superconducting rotating machine according to claim 5, A highly thermally conductive metal wire is attached to the surface of the aforementioned fiber-reinforced composite material in a direction perpendicular to the direction in which eddy currents flow. A superconducting rotating machine characterized by the following features.

7. A superconducting rotating machine according to claim 1, The first heat exchanger and the second heat exchanger have a heat exchange gas interposed between opposing plates made of a highly thermally conductive material. A superconducting rotating machine characterized by the following features.

8. A superconducting rotating machine according to claim 1, The system includes a refrigerator located away from the rotor, The refrigerator is configured to cool the first and second heat exchangers by forming different refrigerant circulation paths on the radiant shield side of the first heat exchanger and the gas container side of the second heat exchanger. A superconducting rotating machine characterized by the following features.

9. A superconducting rotating machine according to claim 1, A first refrigerator for cooling the first heat exchanger, The system comprises a second chiller for cooling the second heat exchanger, The first and second refrigerators have different operating temperatures. A superconducting rotating machine characterized by the following features.

10. A method for cooling a superconducting rotating machine, comprising: a rotor equipped with superconducting field windings; the rotor housed within a non-rotating container having a three-layer cylindrical structure consisting of a vacuum vessel, a radiation shield, and a gas vessel from the outer layer side, and connected to a rotating shaft via a torque tube; the gas vessel being filled with a heat exchange gas; a first heat exchanger being provided between the radiation shield and the torque tube; and a second heat exchanger being provided between the superconducting field windings and the gas vessel, wherein the first and second heat exchangers exchange heat through the heat conduction of the heat exchange gas sealed in the gas vessel; A two-stage refrigerator is inserted into the aforementioned vacuum container. The first stage of the two-stage refrigerator conducts cooling the radiant shield side of the first heat exchanger. The second stage of the two-stage refrigerator cools the gas container side of the second heat exchanger by conduction. A method for cooling a superconducting rotating machine, characterized by the following features.

11. A method for cooling a superconducting rotating machine, comprising: a rotor equipped with superconducting field windings; the rotor housed within a non-rotating container having a three-layer cylindrical structure consisting of a vacuum vessel, a radiation shield, and a gas vessel from the outer layer side, and connected to a rotating shaft via a torque tube; the gas vessel being filled with a heat exchange gas; a first heat exchanger being provided between the radiation shield and the torque tube; and a second heat exchanger being provided between the superconducting field windings and the gas vessel, wherein the first and second heat exchangers exchange heat through the heat conduction of the heat exchange gas sealed in the gas vessel; A refrigerator is installed at a location away from the rotor. A first circulation path is formed between the radiation shield side of the first heat exchanger and the refrigerator. A second circulation path is formed between the gas container side of the second heat exchanger and the refrigerator. The refrigerant passing through the first circulation path and the refrigerant passing through the second circulation path are cooled to different temperatures in the refrigerator, thereby cooling the first heat exchanger and the second heat exchanger. A method for cooling a superconducting rotating machine, characterized by the following features.

12. A method for cooling a superconducting rotating machine, comprising: a rotor equipped with superconducting field windings; the rotor housed within a non-rotating container having a three-layer cylindrical structure consisting of a vacuum vessel, a radiation shield, and a gas vessel from the outer layer side, and connected to a rotating shaft via a torque tube; the gas vessel being filled with a heat exchange gas; a first heat exchanger being provided between the radiation shield and the torque tube; and a second heat exchanger being provided between the superconducting field windings and the gas vessel, wherein the first and second heat exchangers exchange heat through the heat conduction of the heat exchange gas sealed in the gas vessel; The superconducting rotating machine is provided with a first refrigerator for cooling the first heat exchanger and a second refrigerator for cooling the second heat exchanger. The first heat exchanger and the second heat exchanger are cooled by the first refrigerator and the second refrigerator at different operating temperatures. A method for cooling a superconducting rotating machine, characterized by the following features.

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