A hybrid superconducting disc motor with superconducting stator

Abstract

The invention discloses a hybrid superconducting disc motor with a superconducting stator. The stator comprises a stator core, a stator fixing assembly and a stator shell; the rotor comprises a rotor shaft and a rotor back iron; the stator shell comprises a bracket body, and the bracket body inner ring comprises an embedding groove for embedding the stator core and a wedge groove for embedding a wedge; the stator fixing assembly comprises wedge grooves distributed in the rotation circumferential direction thereof; the stator core comprises a wedge-shaped core body formed by stacking oriented silicon steel; a superconducting strip is wound between pole shoes at both ends of the wedge-shaped core body; the stator cores arranged in a disc shape are coaxially embedded between the stator shell and the stator fixing assembly; adjacent stator cores comprise a wedge for tightening the stator shell and the stator fixing assembly along the radial direction of the stator and realizing the separation of adjacent stator cores; the rotor back iron is located at both ends of the stator shell in the axial direction; and the rotor back irons at both sides comprise permanent magnets.

Description

Technical Field

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

[0002] The disc motor, also known as the axial flux motor, has the main magnetic circuit direction of the motor axial direction. Compared with the traditional radial flux cylinder motor, the disc motor has the advantages of small size, light weight, high torque density and high power density.

[0003] The existing axial flux disc motor structures mainly include single stator single rotor, double stator single rotor, double rotor single stator and multi-stage motor structures, in which the stator part is composed of stator core plus copper wire winding, and the rotor part is composed of rotor bracket and permanent magnet magnetic steel.

[0004] The traditional motor with dual rotor and single stator structure can be found in CN107408875A / CN109478808A. The motor in CN109478808A is a YASA type yokeless axial flux motor, and the patent is mainly a new type of stator core structure and production process. Although the scheme optimizes the mechanical stability and / or good or improved cooling capacity based on the YASA type motor, its winding still uses copper wire. Therefore, although the heat dissipation is improved, as the alternating current is passed, copper wire loss will still be generated in the form of heat energy, causing the temperature of the stator part to rise. And the rotor part will also produce losses due to the eddy current generated by the alternating current inductance, causing the temperature of the rotor part to rise.

[0005] Although the name of patent CN101262169A contains the words "axial flux" and "high-temperature superconducting motor", it is essentially a topological structure optimization of a stepper motor.

[0006] Although the title of patent CN101599690B also contains the words "axial flux motor" and "high-temperature superconducting motor", its content focuses only on the optimization of axial and tangential magnetic circuits, which is essentially different from the magnetic circuit form of the YASA type axial flux motor. At the same time, there is no in-depth creative design for the description of superconducting materials and the use process.

[0007] Patent CN107769501B is a YASA type disc motor, but its solution mainly involves the optimization of the magnetic circuit of the rotor part, and the purpose of enhancing the magnetic flux strength of the motor is achieved by additionally setting permanent magnets in the axial direction.

[0008] In summary, in a disc motor, when copper wire windings are used, the current loss in the copper wire will reduce the motor efficiency, and the heat generated will cause the stator temperature to rise; in addition, the eddy current loss of the upper magnetic steel of the rotor disk causes the rotor temperature to rise, and if the temperature is too high, it may cause the magnetic steel to demagnetize. Summary of the invention

[0009] A technical solution provided by the present invention is a hybrid superconducting disc motor with a superconducting stator, which solves

[0010] 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;

[0011] 2. The use of superconducting materials that can generate stronger magnetic fields can further enhance the air gap magnetic field of the motor, but the limitations of the structural cooling solution will cause the motor temperature to be too high.

[0012] The technical solution of the present invention is: The technical solution of the present invention is: for the disc-type superconducting motor, the design of the stator part adopts a stator core, a high-temperature superconducting tape (YBCO) coil and a high-temperature superconducting tape protective cover, while the rotor still adopts a permanent magnet (such as neodymium iron boron NdFeB material).

[0013] 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.

[0014] 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).

[0015] 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.

[0016] 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.

[0017] The stator core is mainly a wedge-shaped core body, which is made of oriented silicon steel stacked, 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 sleeve is first installed between the pole shoes at both ends of the wedge-shaped core body, and the superconducting tape is wound on the surface of the high-temperature superconducting tape protective sleeve, such as yttrium barium copper oxide (YBCO) superconducting tape. 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.

[0018] 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.

[0019] When the rotor is arranged on the axial end side of the stator housing, the magnetic field formed by the rotor interacts with the air gap magnetic field formed by the stator core and superconducting coil on the stator, and the rotor will continue to rotate.

[0020] Based on the above structure, the present solution further solves the cooling and heat dissipation problems in the structure.

[0021] 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.

[0022] 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.

[0023] The cooling methods used for the stator superconducting structure include:

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Compared with the stator part, the rotor part still uses permanent magnets, such as neodymium iron boron NdFeB material.

[0028] Specifically, rotor back irons are provided at both ends of the stator housing in the axial direction, and the rotor back irons are fitted with the rotor shaft through connecting keys and keyways. Permanent magnets are included on both sides of the rotor back irons, and the permanent magnets are arranged corresponding to the wedge-shaped iron core body, and the permanent magnets are arranged in a circular trajectory.

[0029] The advantages of the present invention are:

[0030] 1. Due to the use of YBCO superconducting coils, the loss of Joule heat of copper wire is reduced, that is, the efficiency is higher. In addition, the motor can pass a large current, so that a greater torque can be obtained.

[0031] 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.

[0032] 3. Compared with traditional motors, the loss is lower, and the temperature rise problem can be avoided, so that the overall performance of the motor is improved; compared with full superconductivity, the cost is low, and it can adapt to the working conditions where the power demand is larger than that of traditional motors but smaller than that of full superconductivity. 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, the larger excitation magnetic field will cause the local eddy current of the permanent magnet to be larger, so that the surface of the permanent magnet will produce stronger local eddy currents. This temperature imbalance characteristic will cause local permanent demagnetization of the permanent magnet; similarly, when the operating frequency is higher due to the large number of rotor poles or the faster speed, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0034] Figure 1 This is the structural explosion diagram of the hybrid superconducting disc motor;

[0035] Figure 2 This is the assembly diagram of the hybrid superconducting disc motor;

[0036] Figure 3 This is the assembly diagram of the superconducting structure stator.

[0037] Figure 4 It is the structural diagram of the stator core;

[0038] Figure 5 is a front view of the stator housing;

[0039] Figure 6 It is a structural diagram of the stator fixing assembly;

[0040] Figure 7 It is a cross-sectional view of the water channel arrangement on the stator housing;

[0041] 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; 8. permanent magnet; 9. rotor back iron. DETAILED DESCRIPTION

[0042] Example 1

[0043] The stator part is designed with a stator core, a high-temperature superconducting tape (YBCO) coil and a high-temperature superconducting tape protective cover, while the rotor still uses permanent magnets (such as neodymium iron boron NdFeB material).

[0044] The stator part includes: a stator housing, a stator fixing assembly, a wedge, and a stator core.

[0045] Assembly and principle of stator housing:

[0046] 1. Insert the pole shoe of the wedge-shaped core body 1 with the superconducting coil 2 into 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.

[0047] 2. Place the assembled stator core and upper and lower inner positioning plates into the stator housing;

[0048] 3. Insert the wedge 6 into the gap formed by the stator assembly and the stator fixing assembly to ensure the coaxiality of the stator housing relative to the iron core;

[0049] 4. The wedge 6, the housing and the end faces of 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 or other materials, or injection molding or BMC thermal conductive materials with good thermosetting properties can be used to replace the potting process.

[0050] Cooling system: In the structure of stator superconductor, the stator can adopt distributed cooling structure:

[0051] 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.

[0052] 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 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. Due to the low structural strength of the upper and lower surfaces of the cavity, 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.

[0053] 3. If Figure 7 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 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.

[0054] Stator core and superconducting coil:

[0055] Due to the properties of superconducting materials, we need to wind the superconducting coil 2 first, then put the high-temperature superconducting tape protection cover 3 on the lower half of the iron core, put the superconducting coil outside the high-temperature superconducting tape protection cover, and finally embed or splice the upper half using mortise and tenon / gap fit.

[0056] The rotor part includes: a rotor shaft, a rotor back iron 9, and a permanent magnet 8.

[0057] The design of the rotor part adopts a surface-mounted design of permanent magnets 8. The permanent magnets on both sides are respectively attached to the inner surfaces of their respective rotor back irons 9 and connected by gluing. The permanent magnets 8 are arranged corresponding to the stator core.

[0058] Embodiment 2:

[0059] This solution uses 18 superconducting coils to replace the traditional copper coils in the stator, and 40 magnets 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 motor output torque. At present, 18 slots and 20 poles is the best solution.

[0060] 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 needs to be wound first and then installed on the core, so the structure of the core adopts a mortise and tenon structure.

[0061] The design of the rotor part adopts a permanent magnet surface-mounted design. The permanent magnets on both sides are respectively attached to the inner surface of their respective rotor back irons and connected by gluing. The permanent magnets are arranged corresponding to the stator core.

[0062] 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 hybrid superconducting disc motor with a superconducting stator, comprising: stator and rotor; The stator includes: a stator housing, a stator core embedded in the stator housing, and a stator fixing assembly coaxially arranged with the stator housing; the rotor includes: a rotor shaft penetrating the axial direction of the stator, and rotor back irons on both sides sleeved on the rotor shaft; the characteristics are: 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 are included: wedges for tightening the stator housing and the stator fixing assembly along the stator radial direction and realizing the positioning and separation of adjacent stator cores; The rotor back irons are located at both ends of the stator housing in the axial direction; the rotor back irons on both sides include permanent magnets; and the permanent magnets are arranged in a circular trajectory corresponding to the wedge-shaped iron core.

2. The hybrid superconducting disc motor with a stator superconducting according to claim 1, characterized in that: It comprises a shell, a stator in the shell is potted, and the potted stator comprises a hollow cavity; the shell comprises a cooling circuit, and the cooling circuit cools the hollow cavity.

3. The hybrid superconducting disc motor with a stator superconducting according to claim 2, characterized in that: During the cooling process, the temperature inside the hollow cavity is 30-50K.

4. The hybrid superconducting disc motor with a stator superconducting 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. The hybrid superconducting disc motor with a stator superconducting 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. The hybrid superconducting disc motor with a superconducting stator according to claim 2, characterized in that: The cooling medium used in the cooling circuit includes: gaseous / liquid nitrogen, gaseous helium, and dry powder.

7. The hybrid superconducting disc motor with a superconducting stator according to claim 2, characterized in that: The stator is potted based on the air gap plane formed by the end faces of the stator core pole shoes.

8. The hybrid superconducting disc motor with a superconducting stator according to claim 2, characterized in that: The potting materials of the stator include: epoxy resin and BMC thermal conductive material.

9. The hybrid superconducting disc motor with a stator superconducting 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.

10. The hybrid superconducting disc motor with a superconducting stator 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 iron core body.

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