A stator superconducting structure

Abstract

The present invention discloses a stator superconducting structure, which includes: an embedding groove for embedding a stator core and a wedge groove for embedding a wedge on the inner ring of a support body; a stator fixing assembly includes wedge grooves distributed in the rotation circumferential direction thereof; a stator core includes a wedge-shaped core body formed by stacking oriented silicon steel; a superconducting tape is wound between the pole shoes at both ends of the wedge-shaped core body; a plurality of stator cores are distributed and rotated about an axis parallel to the direction of the magnetic field and arranged in a disc shape; the stator cores arranged in a disc shape are coaxially embedded between the stator housing and the stator fixing assembly; adjacent stator cores include: a wedge for tightening the stator housing and the stator fixing assembly along the stator radial direction and separating adjacent stator cores. Due to the use of YBCO superconducting coils, the structure reduces the loss of the Joule heat part of the copper wire compared with the traditional motor, that is, the efficiency is higher. Moreover, the motor can pass a large current, so that a larger torque can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical fields of motors and superconducting technologies, and in particular to a stator superconducting structure. Background Art

[0002] The electric machine typically includes a cylindrical rotor mounted to rotate about or within a cooperating stator. That is, the electric machine may have a generally cylindrical inner rotor mounted within an outer stator, or a cylindrical outer rotor mounted about an inner stator. In a superconducting electric machine, the stator and / or the rotor may include a plurality of superconducting field coils mounted on a field coil support structure so as to form a surface generally adjacent to but spaced apart from a surface of the other of the stator or the rotor.

[0003] There are a number of problems that must be overcome in such rotor and stator constructions. First, the superconducting field coils and field coil support structure must be maintained at cryogenic temperatures during operation. Conversely, it is preferred to maintain the mounting frame to which the field coil support structure is mounted as close to ambient temperature as possible to allow the rotor or stator to be connected to other devices or components that operate at ambient temperatures. Therefore, there is a need for an improved rotor and stator construction that provides very good thermal insulation between the field coil support structure and the mounting frame for the field coil support structure. Summary of the invention

[0004] A technical solution provided by the present invention is a stator superconducting structure, which solves:

[0005] 1. The loss (in the form of heat energy) generated by the stator copper wire will greatly reduce the operating efficiency of the motor, and at the same time cause the temperature to rise during the operation of the motor and increase the copper loss of the motor;

[0006] 2. The use of superconducting materials that can generate stronger magnetic fields can further enhance the air gap magnetic field of the motor.

[0007] The technical solution of the present invention is: for the stator superconducting motor, the stator part is designed to adopt a stator core, a high-temperature superconducting tape (such as YBCO) coil and a high-temperature superconducting tape protective cover, and the rotor part can also adopt a superconducting coil.

[0008] The material of the protective cover can be selected from a structural material with a softer surface hardness, higher thermal conductivity and better insulation.

[0009] The stator housing is implemented as a disc-shaped bracket body, which has a central hole penetrating in the axial direction. A series of grooves are provided on the inner ring surface of the bracket body, including: an embedding groove for embedding the stator core and a wedge groove for embedding the wedge. The embedding groove is U-shaped, and multiple embedding grooves are evenly arranged along the rotation direction of the inner ring of the bracket body. T-shaped wedge grooves are arranged between adjacent embedding grooves, and the arrangement of the wedge grooves and the embedding grooves maintains the same rotation center. At the same time, a series of through holes are arranged on the bracket body as heat dissipation channels.

[0010] The stator fixing assembly is coaxially assembled in the center hole of the bracket body. The stator fixing assembly is a cylindrical body with an outer edge of a port. T-shaped wedge grooves are also arranged on the outer edges of the ports on both sides. The T-shaped wedge grooves on the bracket body correspond to the T-shaped wedge grooves on the stator housing, which facilitates the assembly of the I-shaped wedge (conveniently connecting the fixing assembly with the stator housing using the I-shaped wedge, and further determining the installation position of the stator core to ensure the concentricity of the stator core).

[0011] At the same time, a radially concave T-groove is arranged on one side of the outer edge of the ports on both sides of the stator fixing assembly, one embedded groove corresponds to one T-groove, and the T-groove can be used to assemble with one end of the wedge-shaped iron core body. That is, the wedge-shaped iron core body can be installed in the embedded groove and inserted into the T-groove by inserting its end into the T-groove so as to be assembled between the stator housing and the stator fixing assembly.

[0012] The wedge is a connecting piece with an I-shaped cross section. One end of the wedge is inserted into the T-shaped wedge groove on the bracket body, and the other end is inserted into the T-shaped wedge groove on the stator fixing assembly, so that the stator housing and the stator fixing assembly can be tightened along the stator radial direction.

[0013] The stator core is mainly a wedge-shaped core body, which is made of oriented silicon steel laminated, bonded and welded. Because it is suitable for disc motors, the solid wedge-shaped core body is cut and designed according to the division of the disc. That is, the wedge-shaped core body is I-shaped, with pole shoes at both ends, and the two sides are cut into bevels. The superconducting tape is wound between the pole shoes at both ends of the wedge-shaped core body. Specifically, a layer of high-temperature superconducting tape protective cover is first installed between the pole shoes at both ends of the wedge-shaped core body, and the superconducting tape, such as yttrium barium copper oxide (YBCO) superconducting tape, is wound on the surface of the high-temperature superconducting tape protective cover. Since the superconducting crystal layer in the YBCO tape is thin and brittle, it is easy to break to affect the overall resistance characteristics. Therefore, the curvature needs to be kept greater than a certain value when winding. Generally, the superconducting coil is wound first and then installed on the stator core.

[0014] The stator core is embedded in the slot, and multiple stator cores are arranged in a circular disc shape. The stator core arranged in a circular disc shape is arranged coaxially with the stator housing and the stator fixing assembly, and the magnetic field formed by the stator core wound with the superconducting coil has a magnetic field direction parallel to the above-mentioned axial direction.

[0015] When the rotor is arranged on the axial end side of the stator housing, the air gap magnetic field formed by the superconducting coil on the stator interacts with the rotor magnetic field, and the rotor will continue to rotate.

[0016] Based on the above structure, the present solution further solves the cooling and heat dissipation problems in the structure.

[0017] The stator housing, stator fixing assembly, stator core, wedge, rotor, etc. are all integrated into the motor housing, so a series of cooling circuits need to be arranged in the housing. We know that the stator or rotor inside the motor generally needs to be potted, usually using resin potting to achieve insulation and fixation effects. Similarly, in this structure, the stator superconducting structure in the housing needs to be potted. In this solution, the potting of the stator superconducting structure can use general epoxy resin and other materials, or injection molding or thermosetting, thermally conductive BMC materials with better thermal conductivity can be used to replace the resin potting process.

[0018] The characteristic of this scheme is that the potting is completed by positioning the end faces of the wedge, the housing and the pole shoe of the stator core mutually. During potting, a part of the hollow cavity is reserved in the stator superconducting structure, and the airtightness of the hollow cavity is ensured by thermoplastic BMC material or epoxy resin.

[0019] The cooling methods used for the stator superconducting structure include:

[0020] 1. The large-diameter gap reserved in the casing is the coolant passage, which together with the upper and lower parts of the casing constitutes a circulating distributed cooling circuit for the coolant, or an inner and outer jacket combination to form a cooling circuit. The choice of coolant gas can be: gaseous nitrogen → liquid nitrogen → gaseous helium.

[0021] 2. The hollow cavity can be cooled by a dry powder refrigerator or the circulating distributed cooling method described in the previous step. Since the structural strength of the upper and lower surfaces of the cavity is relatively low, it is necessary to ensure a reasonable pressure inside the cavity. Distributed cooling inside the cavity must ensure that the temperature inside the cavity is ≤80K, and the preferred range is 30-50K.

[0022] 3. The stator housing includes a structural hole that penetrates in the axial direction thereof, and the structural hole can form a cooling cavity. An external water channel is arranged on the axial end surface of the stator housing to connect adjacent structural holes, and each two adjacent structural holes are connected through an external water channel to form a cooling water channel in the stator. The external water channel can be implemented as a flow channel opened on the sheet material, and the flow channel connects two adjacent structural holes.

[0023] The advantages of the present invention are:

[0024] 1. Due to the use of YBCO superconducting coils, compared with the traditional stator, the loss of the Joule heat part of the copper wire is subtracted, that is, the efficiency is higher. Moreover, the stator can pass a large current, so that a larger torque can be obtained. Because in the production of prototypes, the eddy current of the permanent magnet is exponentially related to the size of the magnetic field density B, so when the motor is running, a larger excitation magnetic field will cause a larger local eddy current of the permanent magnet, so that a stronger local eddy current is generated on the surface of the permanent magnet. This temperature imbalance characteristic will cause local permanent demagnetization of the permanent magnet; similarly, when the rotor pole number is large or the speed is fast, resulting in a higher operating frequency, a larger rotor eddy current loss will be generated, resulting in permanent demagnetization of the permanent magnet. In the design of the present invention, since the superconducting stator can pass a very large current to generate an extremely strong magnetic field, if a conventional high-grade neodymium iron boron permanent magnet is used, there may be a hidden danger of demagnetization. Therefore, this patent uses a superconducting coil surrounded by a constant current to replace the traditional permanent magnet, which can not only generate a stronger magnetic field, but also eliminate the risk of permanent demagnetization.

[0025] 2. The new stator superconducting structure and potting method facilitate the installation of superconducting coils, and the combination of cooling circuit and cavity makes the cooling effect more ideal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0027] Figure 1 is a front view of the stator superconducting structure;

[0028] Figure 2 Schematic diagram of the arrangement of the stator core;

[0029] Figure 3 This is a front view of the stator housing.

[0030] Figure 4 is a three-dimensional diagram of a stator fixing assembly;

[0031] Figure 5 This is an exploded view of a disc motor with a superconducting stator structure;

[0032] Figure 6 It is a cross-sectional view of the water channel arrangement on the stator housing;

[0033] Among them, 1. wedge-shaped iron core; 2. superconducting coil; 3. high-temperature superconducting tape protection cover; 4. stator shell; 5. stator fixing assembly; 6. wedge; 7. T-slot. DETAILED DESCRIPTION

[0034] Example 1

[0035] like Figure 5As shown in the figure, this solution uses 18 superconducting coils to replace the traditional copper coils in the stator part, and 40 magnetic steels are located on two rotor disks, that is, an 18-slot 20-pole structure. For disc motors, the number of poles will directly affect the output torque of the motor. At present, 18 slots and 20 poles is the best solution.

[0036] The structure of the stator core is also different from that of the traditional core. Due to the properties of the superconducting tape, the superconducting coil 2 needs to be wound first and then installed on the wedge-shaped core body 1. At the same time, a high-temperature superconducting tape protective cover 3 is pre-installed on the wedge-shaped core body 1. Therefore, the structure of the stator core is installed on the stator fixing assembly 5 using a mortise and tenon structure.

[0037] The composition and principle of the stator housing:

[0038] 1. Insert the pole shoe of the wedge-shaped core body 1 with the superconducting coil 2 through the T-slot 7 on the stator fixing assembly 5. The concentricity of the stator core can be ensured by the positioning design of the stator housing 4.

[0039] 2. Place the assembled stator core and upper and lower inner positioning plates into the stator housing;

[0040] 3. Insert the structural member wedge 6 into the wedge groove formed by the stator housing 4 and the stator fixing assembly 5 to ensure the coaxiality of the stator housing relative to the iron core;

[0041] 4. The end faces of the wedge, the housing and the pole shoe of the stator core are positioned with each other to complete the potting. The potting can be made of general epoxy resin and other materials, or injection molding or BMC thermal conductive materials with good thermosetting properties can be used to replace the potting process.

[0042] Embodiment 2:

[0043] Cooling system: In stator superconductors, a distributed cooling structure can be used:

[0044] 1. The large-diameter gap reserved in the stator housing is the coolant passage, which together with the upper and lower parts of the housing constitutes a coolant circuit, or an inner and outer jacket combination constitutes a cooling circuit. The coolant gas can be selected in the form of: gaseous nitrogen → liquid nitrogen → gaseous helium.

[0045] 2. The stator can be partially potted with the air gap plane formed by the end face of the stator pole shoe or insulated and plastic-sealed with BMC material, and a part of the hollow cavity and heat dissipation channel can be reserved in the stator. The hollow cavity is made of thermoplastic BMC material or epoxy resin to ensure airtightness, and the formed cavity can be cooled by a dry powder refrigerator or the circulating distributed cooling method described in the previous step. Since the structural strength of the upper and lower surfaces of the cavity is relatively low, it is necessary to ensure a reasonable pressure inside the cavity. The use of distributed cooling inside the cavity requires that the temperature inside the cavity be ≤80K, and the preferred range is 30-50K.

[0046] 3. If Figure 6 The stator housing includes a structural hole penetrating in the axial direction thereof, and the structural hole can form a cooling cavity. An external water channel is arranged on the axial end surface of the stator housing to connect adjacent structural holes, and every two adjacent structural holes are connected through an external water channel to form a cooling water channel in the stator.

[0047] The embodiments of the present invention are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A stator superconducting structure, comprising: A stator housing, a stator core embedded in the stator housing, and a stator fixing assembly coaxially arranged with the stator housing; characterized in that: The stator housing comprises a disc-shaped bracket body which penetrates axially, and comprises: an embedding groove for embedding the stator core and a wedge groove for embedding the wedge on the inner ring of the bracket body; The stator fixing assembly includes wedge grooves distributed in the rotation circumferential direction thereof; The stator core comprises a wedge-shaped core body formed by stacking oriented silicon steel layers; a superconducting tape is wound between the pole shoes at both ends of the wedge-shaped core body; A plurality of stator cores are distributed and rotated about an axis parallel to the direction of the magnetic field and arranged in a disc shape; the stator cores arranged in a disc shape are coaxially embedded between the stator housing and the stator fixing assembly; Between adjacent stator cores there are wedges for tightening the stator housing and the stator fixing assembly along the radial direction of the stator and realizing the positioning and separation of adjacent stator cores.

2. A stator superconducting structure according to claim 1, characterized in that: It comprises a shell, a stator superconducting structure in the shell is encapsulated, and the encapsulated stator superconducting structure comprises a hollow cavity; the shell comprises a cooling circuit, and the cooling circuit cools the hollow cavity.

3. A stator superconducting structure according to claim 2, characterized in that: During the cooling process, the temperature inside the hollow cavity is 30-50K.

4. A stator superconducting structure according to claim 3, characterized in that: The stator housing includes a structural hole penetrating in the axial direction thereof, and an external water channel is arranged on the axial end surface of the stator housing to connect adjacent structural holes; every two adjacent structural holes are connected by an external water channel to form a cooling water channel in the stator.

5. A stator superconducting structure according to claim 2, characterized in that: The cooling circuit includes a distributed cooling circuit and an inner and outer jacket combined cooling circuit.

6. A stator superconducting structure according to claim 2, characterized in that: The stator superconducting structure is potted based on the air gap plane formed by the pole shoe end faces of the stator core.

7. A stator superconducting structure according to claim 2, characterized in that: The potting materials of the stator superconducting structure include: epoxy resin and BMC thermal conductive material.

8. The stator superconducting structure according to claim 1, characterized in that: A high-temperature superconducting tape protective sleeve is sleeved between the pole shoes at both ends of the wedge-shaped iron core body, and a yttrium-barium-copper-oxide superconducting coil, a barium-series superconducting coil, a lanthanide-series superconducting coil, or an actinide-series superconducting coil is wound on the surface of the high-temperature superconducting tape protective sleeve.

9. A stator superconducting structure according to claim 1, characterized in that: The rotating outer surface of the stator fixing assembly includes a T-slot for clamping the end of the wedge-shaped core body.

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