Rotor of a superconducting rotating electric machine and superconducting rotating electric machine

Abstract

To make it capable of stable operation by lowering the maximum temperature of a superconducting rotary electric machine's coil.SOLUTION: A rotor for a superconducting rotary electric machine includes a superconducting coil, a current lead that supplies current to the superconducting coil, a heat transfer part provided in a rotor core and thermally connected to the superconducting coil and the current lead, a supply pipe that supplies a refrigerant gas inside the rotor core, and a return pipe provided on the outer diameter side of the supply pipe that discharges the refrigerant gas that has cooled the superconducting coil via the heat transfer part on the rotor core side. The current lead is configured to be cooled by the refrigerant gas after cooling the superconducting coil.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Embodiments of the present invention relate to a rotor of a superconducting rotating electrical machine and a superconducting rotating electrical machine.

Background Art

[0002] In recent years, carbon neutrality has been demanded as a measure against global warming. Among them, the development of superconducting rotating electrical machines for electric aircraft and the like has been promoted. In a system using a superconducting rotating electrical machine, a superconducting coil is cooled to an extremely low temperature. The cooling method is roughly divided into two types.

[0003] One is a method of installing a small refrigerator for each superconducting coil and directly connecting the refrigerator and the superconducting coil. The other is a method of arranging a large refrigerator in the center and circulating the refrigerant cooled by the refrigerator. Generally, the larger the refrigerator, the higher the efficiency. Therefore, in terms of efficiency, the latter is superior. As a method of cooling a superconducting rotating electrical machine by circulating a refrigerant, a method using liquid helium is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a system using a superconducting rotating electrical machine for an electric aircraft or the like, from the viewpoints of miniaturization and weight reduction, etc., a high-temperature superconducting coil that is easy to cool is considered to be cooled to about 20K. For cooling at about 20K, helium gas, liquid hydrogen, or the like is used as the refrigerant. Hereinafter, the method using helium gas will be described.

[0006] In systems using liquid refrigerants, the refrigerant temperature remains constant as long as the liquid is present, so it is sufficient to circulate refrigerant exceeding the heat load. However, when circulating gas as a refrigerant, the temperature rises due to the heat absorbed by the refrigerant gas, so measures must be taken to prevent the refrigerant gas temperature from becoming too high. On the other hand, in superconducting coils, if even a part undergoes a normal conduction transition, the entire coil undergoes a normal conduction transition. Therefore, it is necessary to keep the maximum coil temperature of the superconducting coil below the critical temperature. However, if heat ingress occurs before the refrigerant gas reaches the coil, the temperature of the refrigerant gas rises significantly, causing the maximum coil temperature to become high. In such cases, stable operation becomes difficult.

[0007] The problem that this invention aims to solve is to provide a rotor for a superconducting rotating electric machine and a superconducting rotating electric machine that can lower the maximum coil temperature and enable stable operation. [Means for solving the problem]

[0008] The rotor of the superconducting rotating electric machine according to this embodiment comprises a superconducting coil, current leads for energizing the superconducting coil, a heat transfer section provided on the rotor core and thermally connected to the superconducting coil and the current leads, a supply pipe for supplying refrigerant gas into the rotor core, and a return pipe provided on the outer diameter side of the supply pipe for discharging the refrigerant gas that has cooled the superconducting coil via the heat transfer section on the rotor core side, wherein the current leads are configured to be cooled by the refrigerant gas after it has cooled the superconducting coil. [Effects of the Invention]

[0009] According to the present invention, the maximum coil temperature of a superconducting rotating electric machine can be lowered, enabling stable operation. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a conceptual diagram showing an example of the overall system configuration including a superconducting rotating electric machine according to the embodiment. [Figure 2]Figure 2 is a conceptual diagram showing an example of the configuration of the superconducting rotating electric machine 1 shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view showing an example of the configuration of the rotating part 11 shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view showing an example of the cross-sectional shape of rotor 11a in section AA shown in Figure 3. [Figure 5] Figure 5 is a conceptual diagram showing an example of the electrical connection relationship between the superconducting coil 31 and the brush 12c shown in Figure 3. [Figure 6] Figure 6 is a cross-sectional view showing an example of the structure near the pipe connection Q shown in Figure 2. [Figure 7] Figure 7 is a cross-sectional view showing an example of the cross-sectional shape of the BB section of the structure shown in Figure 6. [Figure 8] Figure 8 is a cross-sectional view showing an example of the cross-sectional shape in the CC section of the structure shown in Figure 6. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the drawings.

[0012] (System Configuration) Figure 1 is a conceptual diagram showing an example of the overall system configuration including a superconducting rotating electric machine according to the embodiment.

[0013] The system shown in Figure 1 comprises a superconducting rotating electric machine 1 and a gas circulation cooling system 4 including a cooling source 2 and a low-temperature blower 3.

[0014] The superconducting rotating electric machine 1 is equipped with a high-temperature superconducting coil and has a mechanism for cooling the superconducting coil using a refrigerant gas such as helium gas supplied from outside the machine to the inside.

[0015] The gas circulation cooling system 4 circulates a refrigerant gas such as helium gas to cool the superconducting rotating electrical machine 1. The refrigerant gas is cooled to an extremely low temperature by the cooling source 2 and sent to the superconducting rotating electrical machine 1 by the low-temperature blower 3. From the superconducting rotating electrical machine 1, the refrigerant gas that has cooled the superconducting coil and whose temperature has risen is discharged. The refrigerant gas whose temperature has risen is sent to the cooling source 2 through the low-temperature blower 3 and cooled again by the cooling source 2.

[0016] (Configuration of the superconducting rotating electrical machine 1) FIG. 2 is a conceptual diagram showing an example of the configuration of the superconducting rotating electrical machine 1 shown in FIG. 1.

[0017] As shown in FIG. 2, the superconducting rotating electrical machine 1 includes a rotating part 11 including a rotor 11a and a rotating shaft (drive shaft) 11b, and a fixed part 12 including a refrigerant supply part 12a, a stator coil 12b, a brush 12c, and a seal part 12d. There is a piping communication part Q where the pipes of both sides communicate with each other between the rotating part 11 and the fixed part 12. Details of the piping communication part Q will be described later.

[0018] The rotor 11a rotates around the rotating shaft (drive shaft) 11b. The refrigerant supply part 12a supplies the refrigerant gas sent from the cooling source 2 into the rotating rotor 11a, or returns the used refrigerant gas returned from the rotor 11a side to the cooling source 2 through the low-temperature blower 3. The stator coil 12b is arranged on the outer diameter side of the rotor 11a. The brush 12c is energized by contacting the slip ring on the rotating rotor 11a side. The seal part 12d prevents leakage of the refrigerant gas flowing back and forth between the pipe on the rotating part 11 side and the pipe on the fixed part 12 side.

[0019] (Configuration of the rotating part 11) FIG. 3 is a cross-sectional view showing an example of the configuration of the rotating part 11 shown in FIG. 2. FIG. 4 is a cross-sectional view showing an example of the cross-sectional shape at the A-A cross-section of the rotor 11a shown in FIG. 3. Here, in order to make it easier to understand the structure of the main part, some of the dimensions of each part shown in the figure are made larger or smaller than the actual ones. Therefore, the size relationship of each part shown in the figure is different from the actual one.

[0020] As shown in Figures 3 and 4, the rotating part 11 includes a high-temperature superconducting coil 31 (hereinafter referred to as "superconducting coil 31") that generates a magnetic field, and a gas circulation cooling mechanism 32 that circulates refrigerant gas, which includes a supply pipe 32a, a return pipe 32b, and a heat transfer section 32c, as well as a supply channel wall 32a' and a return channel wall 32b'. Furthermore, it includes various elements such as current leads 33, heat transfer plates 34, a rotor core 35, a current lead cooling stage 36, slip rings 37, a vacuum vessel 41, and an insulating section 42. These elements are basically arranged inside the vacuum vessel 41, but some, such as a part of the rotating shaft 11b and the slip rings 37, are arranged outside the vacuum vessel 41.

[0021] A current lead 33 is electrically connected to the superconducting coil 31 via a lead wire (not shown) that supplies current to the superconducting coil 31. This current lead 33 is electrically connected to a slip ring 37. The slip ring 37 conducts current by contacting the brush 12c on the fixed part 12 side.

[0022] The superconducting coil 31 and the current lead 33 are cooled by a refrigerant gas flowing through the gas circulation cooling mechanism 32.

[0023] The gas circulation cooling mechanism 32 mainly includes a supply pipe 32a, a return pipe 32b, and a heat transfer section 32c, and also includes a supply channel wall 32a', a return channel wall 32b', and an insulating section 42 located on the inner diameter side of the heat transfer section 32c.

[0024] The supply pipe 32a and the return pipe 32b are arranged concentrically on one side of the rotor core 35 in the longitudinal direction (the side opposite to the side where the rotation axis 11b is provided). The respective longitudinal directions of the supply pipe 32a and the return pipe 32b are arranged parallel to the axial direction of the rotation axis 11b, and the return pipe 32b is arranged to surround the supply pipe 32a on the outer diameter side of the supply pipe 32a.

[0025] The supply pipe 32a supplies refrigerant gas sent from the fixed section 12 side into the rotor core 35. The return pipe 32b discharges the refrigerant gas that has cooled the superconducting coil 31 via the heat transfer section 32c on the rotor core 35 side back to the fixed section 12 side.

[0026] The superconducting coil 31 is positioned on the heat transfer section 32c and is thermally connected to the heat transfer plate 34. The heat transfer plate 34 is positioned on the heat transfer section 32c. The heat transfer section 32c is provided on the rotor core 35. The heat transfer section 32c may also be configured to form a part of the rotor core 35.

[0027] The current lead 33 is thermally connected to the current lead cooling stage 36. The current lead cooling stage 36 is thermally connected to the surface of the rotor axial end of the heat transfer section 32c (specifically, the end closer to the return pipe 32b of both ends in the rotor axial direction) in order to cool the current lead 33.

[0028] In other words, the heat transfer section 32c is directly thermally connected to the superconducting coil 31, thermally connected to the superconducting coil 31 via the heat transfer plate 34, and thermally connected to the current lead 33 via the current lead cooling stage 36. In this case, the current lead cooling stage 36 and the current lead 33 are located downstream of the superconducting coil 31 in the flow path through which the refrigerant gas flows, and the current lead 33 is cooled via the current lead cooling stage 36 by the refrigerant gas after the superconducting coil 31 has been cooled.

[0029] The rotor core 35 includes a supply channel wall 32a', a return channel wall 32b', and a heat insulating section 42 inside.

[0030] The supply channel wall 32a' forms a channel through which the refrigerant gas supplied from the supply pipe 32a flows. The return channel wall 32b', together with the heat transfer section 32c, forms a channel through which the refrigerant gas sent to the return pipe 32b flows. The insulation section 42 is provided between the supply channel wall 32a' and the return channel wall 32b', forming a vacuum insulation layer. The insulation section 42 provides insulation between the refrigerant gas supplied from the supply pipe 32a and the refrigerant gas sent to the return pipe 32b.

[0031] The refrigerant gas supplied from the refrigerant supply unit 12a to the rotor 11a, as shown in Figure 2, passes through the supply pipe 32a and enters the supply channel surrounded by the supply channel wall 32a' within the rotor core 35, and proceeds toward the rotating shaft 11b. At this time, since there is an insulating section 42 on the outer diameter side of the supply channel wall 32a', heat intrusion from the outer diameter side is suppressed. After this, the refrigerant gas changes direction in the circumferential direction of the rotor core 35 near the end on the rotating shaft 11b side and proceeds, then changes direction again and enters the return channel surrounded by the heat transfer section 32c and the return channel wall 32b', and proceeds toward the return pipe 32b while cooling the heat transfer section 32c.

[0032] The refrigerant gas cools the superconducting coil 31 via the heat transfer section 32c or via the heat transfer section 32c and the heat transfer plate 34, and then cools the current leads 33 via the heat transfer section 32c and the current lead cooling stage 36. The current leads 33, which occupy a large portion of the heat load, are cooled by the refrigerant gas after the superconducting coil 31 has been cooled, and therefore do not affect the cooling of the superconducting coil 31.

[0033] In the example shown in Figure 4, the heat transfer plate 34 has a shape similar to a hexagonal prism, but this shape is just one example and is not limited to this. The heat transfer plate 34 may also have a cylindrical shape, for example. In the case of a cylindrical shape, by arranging the superconducting coil 31 on its circumferential surface, the total distance between the refrigerant gas passing through the inner surface of the heat transfer plate 34 and the superconducting coil 31 can be shortened, thereby reducing the temperature difference due to heat conduction between the two. Furthermore, when connecting the current lead cooling stage 36 to the rotor axial end of the cylindrical heat transfer plate 34, the heat transfer area of ​​the connection surface can be increased, thereby improving the heat transfer efficiency.

[0034] (Electrical connection relationship between superconducting coil 31 and brush 12c) Figure 5 is a conceptual diagram showing an example of the electrical connection relationship between the superconducting coil 31 and the brush 12c shown in Figure 3. To facilitate understanding of the main structure, some of the dimensions of the illustrated parts have been made larger or smaller than their actual dimensions. Therefore, the relative sizes of the illustrated parts may differ from those of the actual parts.

[0035] As shown in Figure 5, lead wires 38, current leads 33, and slip rings 37 are interposed in the electrical connection between the superconducting coil 31 and the brush 12c.

[0036] The superconducting coil 31 has two lead ends, one corresponding to positive (+) and the other to negative (-). These are electrically connected to the current lead 33 via lead wires 38, and the current lead 33 is electrically connected to the slip ring 37. The slip ring 37 then contacts the brush 12c on the fixed part 12, thereby enabling current flow.

[0037] The slip ring 37 is positioned on, for example, the vacuum vessel wall 51, which is part of the vacuum vessel 41. A portion of the current lead 33 is passed through a pre-existing through-hole in the vacuum vessel wall 51 for electrical connection to the slip ring 37. However, an insulator 52 is provided between the vacuum vessel wall 51 and the slip ring 37, and between the vacuum vessel wall 51 and the current lead 33, to ensure insulation between them.

[0038] (Structure near the pipe connection point Q) Figure 6 is a cross-sectional view showing an example of the structure near the pipe connection Q shown in Figure 2. Figure 7 is a cross-sectional view showing an example of the cross-sectional shape at section BB of the structure shown in Figure 6. Figure 8 is a cross-sectional view showing an example of the cross-sectional shape at section CC of the structure shown in Figure 6. Here, in order to make the structure of the main parts easier to understand, some of the dimensions of the parts shown have been made larger or smaller than the actual dimensions. Therefore, the relative sizes of the dimensions of the parts shown may differ from the actual dimensions.

[0039] Furthermore, in Figures 6 to 8, to make it easier to distinguish between the piping on the rotating part 11 side and the piping on the fixed part 12 side, the piping on the rotating part 11 side is shown in dark gray, and the piping on the fixed part 12 side is shown in light gray.

[0040] As described above, the rotating part 11 is provided with a supply pipe 32a and a return pipe 32b arranged concentrically. Similarly, the stationary part 12 is provided with a supply pipe 61a and a return pipe 61b arranged concentrically. The longitudinal directions of the supply pipe 61a and the return pipe 61b are arranged parallel to the axial direction of the rotating shaft 11b, and the return pipe 61b is arranged to surround the supply pipe 61a on the outer diameter side of the supply pipe 61a.

[0041] The supply pipe 61a on the rotating section 11 side is in communication with the supply pipe 32a on the rotating section 11 side. Specifically, a portion of the supply pipe 61a (the portion extending in the axial direction) is inserted into the inner diameter side of a portion of the supply pipe 32a, and a seal portion 12d is provided to seal the gap that occurs between the portion of the supply pipe 61a and the portion of the supply pipe 32a.

[0042] Furthermore, the return pipe 32b on the rotating section 11 side is in communication with the return pipe 61b on the rotating section 11 side. Specifically, a portion of the return pipe 32b is inserted into the inner diameter side of a portion of the return pipe 61b, and a seal portion 12d is provided to seal the gap that occurs between the portion of the return pipe 32b and the portion of the return pipe 61b.

[0043] An insulating section 62, which forms a vacuum insulating layer, is provided between the supply pipe 32a and the return pipe 32b. This insulating section 62 provides insulation between the refrigerant gas flowing through the supply pipe 32a and the refrigerant gas flowing through the return pipe 32b. An insulating section 62, which forms a vacuum insulating layer, is also provided on the outer diameter side of the return pipe 32b. This insulating section 62 provides insulation between the refrigerant gas flowing through the return pipe 32b and the space where the current lead 33 is located.

[0044] Similarly, an insulating section 63 forming a vacuum insulating layer is provided between the supply pipe 61a and the return pipe 61b. This insulating section 63 provides insulation between the refrigerant gas flowing through the supply pipe 61a and the refrigerant gas flowing through the return pipe 61b. In addition, an insulating section 63 forming a vacuum insulating layer is also provided on the outer diameter side of the return pipe 61b. This insulating section 63 provides insulation between the refrigerant gas flowing through the return pipe 61b and the outside air.

[0045] The refrigerant gas supplied from the aforementioned cooling source 2 enters the supply pipe 61a. At this time, since there is an insulating section 63 on the outer diameter side of the supply pipe 61a, heat intrusion from the outer diameter side is suppressed. After this, the refrigerant gas enters the supply pipe 32a. At this time, since there is an insulating section 62 on the outer diameter side of the supply pipe 32a, heat intrusion from the outer diameter side is suppressed.

[0046] Furthermore, the refrigerant gas, having finished cooling the heat transfer section 32c, enters the return pipe 32b. At this time, since there is an insulating section 62 on the outer diameter side of the return pipe 32b, heat intrusion from the outer diameter side is suppressed. After this, the refrigerant gas enters the return pipe 61b. At this time, since there is an insulating section 63 on the outer diameter side of the return pipe 61b, heat intrusion from the outer diameter side is suppressed. After this, the refrigerant gas returns to the cooling source 2 through the low-temperature blower 3.

[0047] As described above, according to the superconducting rotating electric machine 1 of this embodiment, heat intrusion into the supply pipes 32a and 61a is blocked by the return pipes 32b and 61b and the heat insulating sections 62 and 63 surrounding them, so that the refrigerant gas passing through the supply pipes 32a and 61a can be sent into the rotor core 35 while being kept at a low temperature. In addition, the rotor core 35 has a supply channel wall 32a', a return channel wall 32b', and a heat insulating section 42, and these block heat intrusion into the supply channel surrounded by the supply channel wall 32a', so that the refrigerant gas supplied into the rotor core 35 can be sent to the return channel between the heat transfer section 32c and the return channel wall 32b' while being kept at a low temperature.

[0048] Furthermore, according to the superconducting rotating electric machine 1 of the embodiment, the refrigerant gas passing through the return channel between the heat transfer section 32c and the return channel wall 32b' is configured to cool the superconducting coil 31 via the heat transfer section 32c, or via the heat transfer section 32c and the heat transfer plate 34, and then cool the current lead 33 via the heat transfer section 32c and the current lead cooling stage 36. As a result, the current lead 33, which occupies a large portion of the heat load, does not affect the cooling of the superconducting coil 31, and the maximum coil temperature of the superconducting rotating electric machine can be lowered.

[0049] Furthermore, the temperature rise of the refrigerant gas is inversely proportional to the gas flow rate; the larger the gas flow rate, the smaller the rise in temperature. To suppress the temperature rise of the refrigerant gas, it is effective to reduce pressure loss and increase the gas flow rate. To achieve this, the piping through which the refrigerant gas flows should be made wider (increased in diameter), except for the piping sections that are difficult to narrow (i.e., the sections where the piping on the rotating section 11 and the piping on the stationary section 12 are connected). In this way, pressure loss can be reduced and gas flow rate can be increased, thereby further suppressing the temperature rise of the refrigerant gas, lowering the maximum temperature of the coil, and enabling more stable operation of the superconducting coil 31.

[0050] Furthermore, although the above embodiment describes the case where the gas circulation cooling system 4 forms a single loop, the gas circulation cooling system 4 may also form multiple loops. Also, a cryogenic refrigerator may be used as the cooling source 2, but a refrigerant such as liquid hydrogen may be used instead. Also, although the above embodiment illustrates the case where a low-temperature blower is used as the means of gas circulation, a circulation system consisting of a compressor and heat exchanger at room temperature may be used instead.

[0051] As described in detail above, according to the embodiment, the maximum coil temperature of the superconducting rotating electric machine can be lowered, and stable operation can be achieved.

[0052] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0053] 1...Superconducting rotating electric machine, 2...Cooling source, 3...Low temperature blower, 4...Gas circulation cooling system, 11...Rotating part, 11a...Rotor, 11b...Rotating shaft (drive shaft), 12...Fixed part, 12a...Refrigerant supply part, 12b...Stator coil, 12c...Brush, 12d...Seal part, 31...Superconducting coil, 32...Gas circulation cooling mechanism, 32a...Supply piping, 32a'...Supply channel wall, 32b...Return piping, 32b'...Return channel wall, 32c...Heat transfer part, 33...Current lead, 34...Heat transfer plate, 35...Rotor core, 36...Current lead cooling stage, 37...Slip ring, 38...Lead wire, 41...Vacuum vessel, 42...Insulation part, 51...Vacuum vessel wall, 52...Insulator, 61a...Supply piping, 61b...Return piping, 62,63...Insulation part.

Claims

1. Superconducting coils and Current leads that supply current to the superconducting coil, A heat transfer section is provided on the rotor core and is thermally connected to the superconducting coil and the current lead, A supply pipe for supplying refrigerant gas into the rotor core, A return pipe is provided on the outer diameter side of the supply pipe and discharges the refrigerant gas that has cooled the superconducting coil via the heat transfer section on the rotor core side, It is equipped with, The current lead is configured to be cooled by the refrigerant gas after the superconducting coil has been cooled. Rotor of a superconducting rotating electric machine.

2. The heat transfer section has a cylindrical shape, and the superconducting coil is arranged on its circumferential surface. The rotor of the superconducting rotating electric machine according to claim 1.

3. The current lead cooling stage is further provided, which is thermally connected to the heat transfer section and is used to cool the current lead. The rotor of the superconducting rotating electric machine according to claim 1.

4. The current lead cooling stage is thermally connected to the surface of the rotor axial end of the heat transfer section. The rotor of the superconducting rotating electric machine according to claim 3.

5. The rotor core is It includes an insulating section that provides insulation between the refrigerant gas supplied from the supply pipe and the refrigerant gas sent to the return pipe. The rotor of the superconducting rotating electric machine according to claim 1.

6. The aforementioned heat insulating portion includes a vacuum heat insulating layer, The rotor of the superconducting rotating electric machine according to claim 5.

7. The system includes an insulating section that provides insulation between the refrigerant gas flowing through the supply pipe and the refrigerant gas flowing through the return pipe. The rotor of the superconducting rotating electric machine according to claim 1.

8. The aforementioned heat insulating portion includes a vacuum heat insulating layer, The rotor of the superconducting rotating electric machine according to claim 7.

9. A superconducting rotating electric machine configured using the rotor of a superconducting rotating electric machine according to any one of claims 1 to 8.

Images