Claims:We claim:
1. A rotor structure (25) for use in High Temperature Superconducting (HTS) motor, the rotor structure (25) comprises:
a cylindrical member having two flanges, one at drive end shaft (1a) and other at non drive end shaft (15a);
a HTS coil housing (4) provided on recesses of the cylindrical member;
a cold Helium gas distribution chamber (7) connected with the HTS coil housing (4), the cold Helium gas distribution chamber (7) connected with cold Helium gas intermediate distribution chamber (9) via cold Helium gas connecting pipe (11);
a hot Helium gas collection chamber (6) connected with rear end of the HTS coil housing (4) to receive the hot Helium gas, the hot Helium gas collection chamber (6) connected with hot Helium gas intermediate collection chamber (8) via hot Helium gas connecting pipes (10);
a SS sleeve (3) fastened to fiber glass torque tube (2) at the drive end shaft (1) and to fiber glass torque tube (5) at the non drive end shaft (15), wherein the SS sleeve (3) holds the HTS coil housing (4);
a copper radiation shield (14) provided over the SS sleeve (3), the copper radiation shield (14) positioned over the fiber glass torque tube (2) and the fiber glass torque tube (5); and
a vacuum enclosure (16) welded to the drive end shaft (1a) and the non drive end shaft (15a) for maintaining vacuum in the rotor structure (25).

2. The rotor structure (25) as claimed in claim 1, wherein the rotor structure (25) further comprises:
a damper sleeve (17) provided over the vacuum enclosure (16); and
a damper winding (18) provide over the damper sleeve (17) for generating starting torque in the rotor (25).
3. The rotor structure (25) as claimed in claim 1, wherein the rotor structure (25) further comprises:
a slipring shaft (19) at the non drive end (15) to feed current to the HTS coil housing (4).

4. The rotor structure (25) as claimed in claim 3, wherein the rotor structure (25) further comprises:
a Helium transfer coupling (20) connected to the slipring shaft (19) to transfer Helium from cryocooler to the rotor structure (25).

5. The rotor structure (25) as claimed in claim 1, wherein the cold Helium gas intermediate distribution chamber (9) coupled with cold Helium gas inline connected tube (13) which is connected to the Helium transfer coupling (20) for sending cold Helium gas from cryocooler.

6. The rotor structure (25) as claimed in claim 1, wherein the hot Helium gas intermediate collection chamber (8) coupled with Hot Helium gas return line (12) which is connected with the Helium transfer coupling (20) for receiving the Hot Helium gas and send to the cryocooler.

7. The rotor structure (25) as claimed in claim 1, wherein the rotor structure (25) stands with high pressure upto 5Bar Helium gas and centrifugal force at speed of 500RPM.

8. The rotor structure (25) as claimed in claim 1, wherein the cold Helium gas has temperature upto 30K.
, Description:ROTOR STRUCUTRE FOR HIGH TEMPERATURE SUPERCONDUCTING (HTS) SYNCHRONOUS MOTOR
FIELD OF INVENTION
[001] The present invention relates to high temperature superconducting (HTS) motor, and in particularly to, structure of rotor for high temperature superconducting (HTS) motor. More particularly, a structure of a rotor for the HTS filed coils having helium leak tight and with the reliable sealing from outside atmosphere.
BACKGROUND OF THE INVENTION
[002] High Temperature superconducting (HTS) motor, consist of HTS field windings in the rotor and the stator consists of air gap copper windings. The HTS motors are highly efficient, compact, lighter, and noise free motors. The HTS motor field coils are cooled with low temperature Helium Gas (up to 30K). The helium gas is very light gas (atomic number is two) and leaks from even very minute cracks. So the mounting arrangement of the rotor HTS fields coils (cooled by helium gas) of the HTS motor should be with less joints and good rigidity to avoid Helium leakage and withstand the rotational forces. In this patent the complete rotor structure of High temperature superconducting synchronous motor with less joints and ease to manufacture is developed.
PRIOR ARTs

[003] European Patent no: EP913023B1 with title, Superconducting Synchronous Motor Construction discloses a rotor assembly for use within a superconducting electric motor includes a superconducting winding formed of high temperature superconductor and during operation, generates a flux path within the rotor assembly; and a high permeability magnetic material, positioned within at least a portion of the flux path so as to decrease the overall reluctance of the flux path. The rotor assembly may include a support member having an internal volume and formed of a non-magnetic, high-strength resilient material. The support member supports on its outer surface the superconducting winding and within its internal volume, the high permeability magnetic material. The magnetic material may be in the form of a core member to provide the low reluctance portion to the flux path generated by the superconducting winding.
[004] WIPO Patent No: WO0049703A9 with title “High Temperature Superconducting Rotor For Synchronous Machine” discloses a high temperature superconducting rotor for a synchronous machine includes a high temperature superconducting field winding, a field winding support concentrically arranged about the high temperature superconducting field winding, and a thermal reserve concentrically arranged about the field winding support. The thermal reserve includes a thermally conductive material. The material is either electrically conductive, for example, aluminium, or electrically non-conductive, for example, ceramics, such as beryllium oxide or alumina. The thermal reserve material includes segmentation in a direction normal to the rotor axis, along the rotor axis, neither, or both. The rotor includes a banding concentrically arranged about the thermal reserve. The banding includes an electrically conductive material, for example, steel, an electrically non-conductive material, for example, Kevlar, or both. The rotor includes an outer layer concentrically arranged about the thermal reserve. The outer layer includes a thermally non-conductive material.
[005] US patent No: US20120274161A1 with title “Rotor Core and Superconducting Rotating Machine with the Rotor Core” discloses a rotor core, a method for cooling a rotor core, and a superconducting rotating machine, capable of effectively and uniformly cooling superconducting coils without causing cold brittleness in an extremely low temperature. The rotor core, which is made of a substantially hollow cylindrical member of nonmagnetic material, has a cylindrical cavity defined therein and extending in the longitudinal axis of the member. Helium gas is delivered in the rotor core from the proximal to distal sides and vice versa, which ensures a uniform cooling of the rotor core. This also ensures a uniform and effective cooling of the superconducting coils.
OBJECTIVE
[006] An object of the present subject matter is develop a rotor structure for a HTS synchronous motor to meet the following objectives:
1. Rotor structure to withstand up to the speed of 500RPM
2. Helium leak tight in the order of 1 x e-8 mbar lit/sec
3. Less Heat in leak and high vacuum system
4. Reduction of the number of joints for minimum leak
5. Ease of manufacturing and testing
SUMMARY OF THE INVENTION:
[007] The present subject matter herein relates to a rotor structure for use in High Temperature Superconducting (HTS) motor. The rotor structure has a cylindrical member having two flanges, one at drive end shaft and other at non drive end shaft. Further, a HTS coil housing provided on recesses of the cylindrical member. The rotor structure has a cold Helium gas distribution chamber connected with the HTS coil housing and the cold Helium gas distribution chamber connected with cold Helium gas intermediate distribution chamber via cold Helium gas connecting pipe. Further, a hot Helium gas collection chamber connected with rear end of the HTS coil housing to receive the hot Helium gas and the hot Helium gas collection chamber connected with hot Helium gas intermediate collection chamber via hot Helium gas connecting pipes. The rotor has a SS sleeve which is fastened to fiber glass torque tubes at the drive end shaft and non drive end shaft, wherein the SS sleeve holds the HTS coil housing. A copper radiation shield provided over the SS sleeve. The copper radiation shield positioned over the fiber glass torque tubes. Further, a vacuum enclosure welded to the drive end shaft and the non drive end shaft for maintaining vacuum in the rotor structure. A damper sleeve is provided over the vacuum enclosure to hold a damper winding for generating starting torque in the rotor.
[008] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[009] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0010] Fig. 1 illustrates longitudinal sectional view of the rotor structure for HTS synchronous motor, in accordance with an embodiment of the present subject matter.
[0011] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE CURRENT INVESTIGATION
[0012] The present subject matter herein relates to a rotor structure for use in High Temperature Superconducting (HTS) motor. The rotor structure has a cylindrical member having two flanges, one at drive end shaft and other at non drive end shaft. Further, a HTS coil housing provided on recesses of the cylindrical member. The rotor structure has a cold Helium gas distribution chamber connected with the HTS coil housing and the cold Helium gas distribution chamber connected with cold Helium gas intermediate distribution chamber via cold Helium gas connecting pipe. Further, a hot Helium gas collection chamber connected with rear end of the HTS coil housing to receive the hot Helium gas and the hot Helium gas collection chamber connected with hot Helium gas intermediate collection chamber via hot Helium gas connecting pipes. The rotor has a SS sleeve which is fastened to fiber glass torque tubes at the drive end shaft and non drive end shaft, wherein the SS sleeve holds the HTS coil housing. A copper radiation shield provided over the SS sleeve. The copper radiation shield positioned over the fiber glass torque tubes. Further, a vacuum enclosure welded to the drive end shaft and the non drive end shaft for maintaining vacuum in the rotor structure. A damper sleeve is provided over the vacuum enclosure to hold a damper winding for generating starting torque in the rotor.
[0013] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0014] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0015] The present subject matter relates to High Temperature Superconducting (HTS) motors. Further, the HTS motors consist of HTS windings in the rotor and the air gap copper windings in the stator. The HTS windings in the rotor help in manufacturing of compact, lighter, and noise free motors. Motors with larger power ratings may be developed and the superconducting generators can also be made thereby light weight and higher efficiency.
[0016] In the present rotor, High temperature superconducting (HTS) wire is used as the wire for making field coils for High temperature superconducting (HTS) motor. These field coils are required to cool up to 30K to generate the required flux for operation of the motor. Helium gas of temperature 30K is used to cool the field coils to obtain the superconductivity. To maintain the cryogenic temperature at the field coils, the entire structure is surrounded by the vacuum. The helium gas is very light gas (atomic number is two) and leaks from even very minute cracks. Therefore, structure of the rotor should be made such a way that, the helium gas should not enter into the vacuum space and should have low heat in leak. By considering the above issues the rotor structure of the HTS synchronous motor is designed.
[0017] The present rotor is incorporated in a HTS motor with a stator, the rotor is electromagnetically connected with the stator. The rotor is connected to cryogen supply and return tubes connecting between a cryogen supply and return unit and a cooling unit so that a body of the rotor is cooled by a cryogen, such as helium gas, supplied from the cryogen supply and return unit and also superconducting coils mounted on the rotor are cooled down to at approximately 30K through the conduction cooling by the body of the rotor to maintain the superconductivity of the superconducting coils.
[0018] Referring to figure 1, rotor 25 has two flanges, one at drive end shaft 1a and other at non drive shaft 15a and a cylindrical cavity is defined therein and extending in a direction along the central axis of the rotor. The rotor 25 has recesses for receiving HTS coil housing 4. A vacuum enclosure 16 is provided over both the flanges 1a and 15a to cover the rotor 25 completely. Further, the HTS coil housing 4 is connected with cold Helium gas distribution chamber 7 towards in the direction of helium gas distribution. In other others, near the non drive shaft end 15. The cold Helium gas distribution chamber 7 are connected with the cold Helium gas intermediate distribution chamber via cold Helium gas connecting pipes between the distribution chambers 11 and 11a respectively. The cold Helium gas intermediate distribution chamber 9 receives cold helium from cooling unit through cold Helium has return line to transfer coupling 20. Other end of the HTS coil housing 4 is connected with Hot Helium gas collection chamber 6. The hot Helium gas collection chamber 6 is connected with the hot Helium gas intermediate collection chamber 8 via cold Helium gas connecting pipes 10 and 10a between the collection chambers, respectively. The Hot Helium gas intermediate collection chambers 10 and 10a and 8 receives Hot helium gas from the HTS coil housing after cooling the HTS coils the cold Helium gas becomes hot Helium gas and goes into the Hot Helium gas intermediate collection chamber 8. The Hot Helium gas intermediate collection chamber 8 is connected to the cooling unit through the Hot Helium gas return line 12 to transfer the Hot Helium gas from the Helium transfer coupling 20 to the cooling unit.
[0019] Further, a fiber glass torque tube 2 is connected with the drive end shaft flange 1a of the drive end shaft 1. Another fiber glass torque tube 5 is connected with the non drive end shaft flange 15a of the non drive end shaft 15. A SS sleeve 3 is provided over ends of the fiber glass torque tube 2 and the fiber glass torque tube 5 to hold the HTS coil housing 4. Further, above the SS sleeve 3 a copper radiation shield 14 is provided on the fiber glass torque tube 2 and the fiber glass torque tube 5. There is a gap between the SS sleeve 3 and the copper radiation shield 14. A SS enclosure 17 is provided over the complete housing of the rotor. The SS enclosure 17 is positioned over the drive end shaft flange 1a from one end and the non drive end shaft flange 15a from other end and covers the complete rotor. The SS enclosure 17 is provided for holding damper winding 18. The damper winding 18 is provided over the SS enclosure 17 for generating starting torque. At end of the non drive end shaft 15 a slipring shaft 19 is provided. The helium transfer coupling 20 is provided at the end between the hot and cold transfer tubes and the cooling unit to receive hot Helium gas and transfer cold Helium gas to the rotor HTS coil housing.
[0020] As explained above, a SS sleeve 3 holds the HTS coil housings 4. Cryogenic temperature Helium gas from Helium transfer coupling 20 which is provided at end of non drive end shaft 15 enters to the HTS coil housings 4 through intermediate cold Helium gas distribution chamber 9 and main cold Helium gas distribution chamber 7. The entered helium gas cools the HTS coils 4 and take away the heat load from the HTS coils 4, and returned via Hot Helium gas collection chamber 6 and the intermediate Hot Helium gas collection chamber 8 to the Helium transfer coupling 20. The Drive End and Non-Drive End fibre glass torque tubes 2, 5 are fastened to both sides of the coil holding SS sleeve 3. The other ends of the Drive End and Non Drive End torque tubes 2, 5 are connected to the Drive End shaft flange 1a and Non Drive End shaft flange 15a. The fibre glass torque tubes 2, 5 are used for reduction of conduction heat load from the room temperature end shafts 1 & 15.
[0021] The copper radiation shield 14 is used for the reduction of radiation heat load from external atmosphere and fixed to the fibre glass torque tubes 2 & 5. The Vacuum enclosure 16 is welded to the Drive End shaft 1 and the Non Drive End shaft 15 outer diameters or flanges 1a and 15a. This is for maintaining the vacuum in the entire rotor. The Damper sleeve 17 is for holding the Damper bars 18 or damper winding 18. The damper bars 18 generates starting torque in the rotor. The Non Drive End shaft 15 is connected to the slipring shaft 19. The slip rings 19 are used for feeding the current to the rotating field coils. The slip ring shaft 19 is connected to the Helium transfer coupling 20 which transfer the Helium from stationary cryo-cooler to the rotating HTS rotor.
[0022] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.
[0023] Reference numerals:
1. Drive end shaft
2. Fiber glass torque tube (Drive end)
3. HTS coil holding SS sleeve
4. HTS coil housing
5. Fiber glass torque tube (Non Drive end)
6. Hot Helium gas collection chamber
7. Cold Helium gas distribution chamber
8. Hot Helium gas intermediate collection chamber
9. cold Helium gas intermediate distribution chamber
10. Hot He gas connecting pipes between collection chambers
11. Cold He gas connecting pipes between distribution chambers
12. Hot helium gas return line to transfer coupling
13. Cold helium gas in line from transfer coupling
14. Copper radiation shield
15. Non Drive end shaft
16. Vacuum enclosure
17. SS enclosure for damper winding or (Damper sleeve)
18. Damper winding
19. Slipring shaft
20. Helium transfer coupling
1a: drive end shaft flange
15a: Non drive end shaft flange