Low-temperature cooling structure and superconducting electric machine

Abstract

The application relates to the field of superconducting motors, in particular to a low-temperature cooling structure and a superconducting motor, which comprises an inlet-side constant-pressure box, an outlet-side constant-pressure box, a stator thermostat and a superconducting winding assembly. The inlet-side constant-pressure box and the outlet-side constant-pressure box are arranged on the two sides of the stator thermostat in the axial direction and are respectively connected with an external low-temperature circulating system, and the two form a stable pressure difference for driving the one-way flow of low-temperature fluid. The stator thermostat is formed by an inlet-side porous plate with a hole array, an outlet-side porous plate and a constant-temperature area surrounded thereby, and the superconducting winding assembly is arranged in the area. The superconducting winding is a multi-layer stacked structure, an interlayer framework with an interlayer cooling groove is arranged between adjacent layers, and the hole array and the interlayer cooling groove are sequentially connected to form a through cooling flow path. The low-temperature fluid is driven by the stable pressure difference to flow through the winding interlayers, the problems of insufficient interlayer cooling and uneven flow distribution of the multi-layer superconducting winding are solved, the uniformity of winding cooling and the heat exchange efficiency are improved, and the risk of local quenching is reduced.

Description

Technical Field

[0001] This invention relates to the field of superconducting motors, and more specifically to a cryogenic cooling structure and a superconducting motor. Background Technology

[0002] Superconducting motors, leveraging the high current-carrying capacity and low-loss characteristics of superconducting materials at low temperatures, can significantly improve the power density, operating efficiency, and electromagnetic load level of motors. They hold significant application value in high-end equipment fields such as aerospace propulsion, marine power, high-power generation, and special drives. Compared to conventional motors, superconducting motors require their superconducting windings to operate stably below their critical temperature over long periods. Therefore, the design of the cryogenic cooling structure directly determines the operational reliability of the superconducting windings, the overall energy efficiency of the motor, and its long-term service stability, making it one of the core components of the superconducting motor technology system.

[0003] Axial flux motors, with their outstanding advantages of short axial dimension, high torque density, and compact structure, can be combined with superconducting windings to form high-power-density superconducting motors, making them an important research direction in the field of superconducting motors. However, the stator, mover, and air gap region of axial flux superconducting motors are usually arranged compactly along the axial direction, leaving very limited space inside the motor for arranging cooling channels and cryogenic structures. Especially in structures using multi-layer stacked superconducting windings, the heat dissipation path between the layers inside the windings is relatively long, making it difficult to quickly and evenly conduct the generated heat outwards. This can easily lead to uneven temperature distribution and continuous local heat accumulation within the windings, posing a direct threat to the safe operation of the superconducting windings.

[0004] Currently, common cooling methods for superconducting motors include immersion cooling, external surface cooling, cold plate thermal conductivity cooling, and localized fluid flushing cooling. While these methods can meet the low-temperature requirements of superconducting windings to some extent, they still have significant technical limitations for multi-layered superconducting winding structures. Cooling media often fail to fully penetrate the interlayer regions of the winding, with cooling primarily concentrated on the outer surface or localized contact areas. The core region inside the winding generally suffers from insufficient heat exchange and large temperature gradients, making it difficult to effectively control the risk of localized quenching. Furthermore, during operation, the superconducting winding is subjected to multiple heat sources, including AC losses, joint losses, thermal conductivity from the support structure, and radiative heat loads. This dispersed heat generation further exacerbates the uneven temperature distribution within the winding. Relying solely on external surface or localized cooling cannot achieve uniform and efficient heat exchange between the layers of a multi-layered winding, failing to fundamentally eliminate the potential for localized heat accumulation and hindering further improvements in the operational stability and power density of superconducting motors. In addition, most existing cooling structures are unable to form a stable and consistent cooling medium flow state throughout the entire winding. The medium flow rate and pressure in different winding areas and different interlayer positions are prone to fluctuations, which further amplifies the problem of uneven cooling and cannot meet the cooling requirements for long-term reliable operation of high power density superconducting motors. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature cooling structure and a superconducting motor to solve the problems of insufficient interlayer cooling, uneven distribution of cooling fluid, easy local heat accumulation inside the winding, and high risk of local quench failure in existing superconducting motors with multilayer superconducting windings.

[0006] To achieve the above objectives, the following technical solution is adopted.

[0007] A cryogenic cooling structure includes an inlet-side constant pressure chamber, an outlet-side constant pressure chamber, a stator thermostat, and a superconducting winding assembly;

[0008] The inlet-side constant pressure box and the outlet-side constant pressure box are located on opposite sides of the stator thermostat. The inlet-side constant pressure box and the outlet-side constant pressure box are connected to an external cryogenic circulation system. The fluid pressure in the inlet-side constant pressure box is higher than the fluid pressure in the outlet-side constant pressure box, so as to form a stable pressure difference between the inlet-side constant pressure box and the outlet-side constant pressure box to drive the unidirectional flow of cryogenic fluid.

[0009] The stator thermostat includes an inlet-side perforated plate, an outlet-side perforated plate, and a constant-temperature region enclosed by the inlet-side perforated plate and the outlet-side perforated plate, and the superconducting winding assembly is disposed within the constant-temperature region.

[0010] The inlet-side perforated plate is disposed between the inlet-side constant pressure box and the superconducting winding assembly, and the outlet-side perforated plate is disposed between the superconducting winding assembly and the outlet-side constant pressure box; the inlet-side perforated plate is provided with an inlet-side hole array, and the outlet-side perforated plate is provided with an outlet-side hole array.

[0011] The superconducting winding assembly includes multiple superconducting windings arranged along the circumferential direction. Each superconducting winding includes multiple superconducting winding layers stacked together. An interlayer skeleton is provided between adjacent superconducting winding layers, and an interlayer cooling groove is formed on the interlayer skeleton.

[0012] The inlet side hole array, the interlayer cooling tank, and the outlet side hole array are connected in sequence to form a cryogenic cooling flow path for unidirectional flow of cryogenic fluid.

[0013] Optionally, both the inlet-side hole array and the outlet-side hole array are arranged in sections according to the position of the superconducting winding assembly. Each group of hole arrays corresponds to the position of at least one superconducting winding, and each fluid through hole in each group of hole arrays is respectively connected to the interlayer cooling groove in the corresponding superconducting winding.

[0014] Optionally, both the inlet-side constant pressure box and the outlet-side constant pressure box are annular or circular cavities, extending along the circumferential direction of the stator assembly to cover multiple superconducting windings arranged in the circumferential direction.

[0015] Optionally, the interlayer cooling groove is formed on the interlayer skeleton along the extension direction of the superconducting winding, and the cross-sectional shape of the interlayer cooling groove is one of rectangle, semicircle or trapezoid.

[0016] Optionally, the constant temperature zone of the stator thermostat is a sealed chamber, and the inlet-side perforated plate and the outlet-side perforated plate are fixedly connected by fasteners or welding to enclose the superconducting winding assembly within the constant temperature zone.

[0017] Optionally, when the cryogenic fluid flows through the interlayer cooling tank, a portion of the cryogenic fluid flows along the gap between adjacent superconducting windings or a local gap on the outside of the superconducting windings to provide auxiliary cooling to the sides of the superconducting windings.

[0018] Optionally, the inlet-side constant pressure box is provided with an inlet-side constant pressure box air inlet, and the outlet-side constant pressure box is provided with an outlet-side constant pressure box exhaust port; the inlet-side constant pressure box air inlet is used to connect with the cryogenic fluid output pipeline of the external cryogenic circulation system, and the outlet-side constant pressure box exhaust port is used to connect with the cryogenic fluid recovery pipeline of the external cryogenic circulation system.

[0019] Optionally, when the cryogenic cooling structure is applied to an axial flux superconducting motor, the inlet-side constant pressure box is positioned close to the air gap of the axial flux superconducting motor, and the outer wall of the inlet-side constant pressure box faces the mover assembly and permanent magnet of the axial flux superconducting motor; the cryogenic fluid introduced into the inlet-side constant pressure box keeps the outer wall of the inlet-side constant pressure box at a low temperature, so that the inlet-side constant pressure box acts as a cryogenic cooling screen to absorb the heat radiated or conducted by the mover assembly and / or the permanent magnet.

[0020] A superconducting motor includes a stator assembly, a mover assembly, an air gap disposed between the stator assembly and the mover assembly, and the cryogenic cooling structure.

[0021] The superconducting winding assembly is disposed on the stator assembly or the mover assembly; the cryogenic cooling structure is fixedly disposed on the side where the superconducting winding assembly is located;

[0022] The mover assembly is disposed on one or both sides of the stator assembly along the axial direction. A permanent magnet is disposed on the side of the mover assembly facing the stator assembly, and the air gap is formed between the permanent magnet and the stator assembly.

[0023] Optionally, the permanent magnet is fixed to the surface of the mover assembly by bonding or embedding; the constant pressure box on the inlet side of the low-temperature cooling structure acts as a low-temperature cold shield to absorb the heat radiated from the mover assembly and / or the permanent magnet to the stator assembly.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This application establishes a stable pressure difference by setting constant pressure boxes on both sides of the stator thermostat along the axial direction. Combined with the perforated array of a perforated plate and the cooling grooves between the winding layers, a complete through-flow path is formed. This allows cryogenic fluid to continuously flow through the interlayer region of the superconducting winding under stable pressure conditions in a single direction. This effectively avoids uneven flow distribution caused by cooling fluid pressure fluctuations, enabling the cooling medium to fully penetrate the internal interlayer region of the multi-layer winding. This overcomes the limitations of traditional cooling methods that only act on the outer surface of the winding, significantly enhancing the heat transfer capacity inside the winding and significantly improving the temperature uniformity within the multi-layer winding. It fundamentally alleviates the problem of local heat accumulation, reduces the risk of local quenching, and provides a reliable guarantee for the long-term stable operation of the superconducting winding. Simultaneously, the skeleton structure set between the winding layers not only provides support and separation for the multi-layer winding, ensuring the stability and stacking accuracy of the winding structure, but also directly forms an interlayer cooling channel for the cryogenic fluid, achieving functional integration of structural support and cooling heat exchange. This effectively improves the internal space utilization of the motor and adapts to the compact structural layout characteristics of axial flux motors.

[0026] The perforated plate features an array of holes corresponding to the superconducting windings and interlayer cooling channels, enabling directional distribution of cryogenic fluid and further improving cooling consistency across different winding regions and interlayer positions. The constant-pressure chamber, employing annular or circular cavity structures, can completely cover the entire superconducting winding along its circumference, providing a uniform and stable fluid supply environment for each winding and adapting to circumferentially arranged superconducting winding structures. The interlayer cooling channels are arranged along the winding's extension direction, perfectly matching the winding's structural form to ensure heat exchange coverage. Diverse cross-sectional shapes can accommodate different heat exchange requirements and processing specifications. The constant-temperature zone employs a sealed chamber design, reducing the intrusion of external heat into the interior, maintaining the low-temperature stability of the winding environment, and reducing the operating energy consumption of the cryogenic circulation system. In addition to the main interlayer cooling pathway, the gaps on the winding sides can form auxiliary cooling pathways, simultaneously achieving supplementary heat exchange in the winding side regions, further improving the overall temperature uniformity of the winding. Fluid interfaces on both sides of the constant-pressure chamber facilitate connection to external cryogenic circulation systems, enabling the recycling of the cooling medium. When this cooling structure is applied to an axial flux superconducting motor, the constant pressure box near the air gap can also serve as a low-temperature cooling shield, absorbing the heat radiated or conducted by the mover assembly and permanent magnet. While completing the cooling of the stator winding, it also takes into account the heat load control of the mover side, comprehensively improving the overall thermal stability and operational reliability of the motor. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional view of a low-temperature cooling structure according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the perforated plate structure of the stator thermostat in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the superconducting winding and interlayer skeleton in an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the superconducting winding and interlayer skeleton from another angle in an embodiment of the present invention.

[0031] The components are: 1. Mover assembly; 2. Permanent magnet; 3. Air gap; 4. Stator assembly; 5. Superconducting winding assembly; 51. Superconducting winding; 6. Inlet-side constant pressure box; 61. Inlet-side constant pressure box air inlet; 7. Outlet-side constant pressure box; 71. Outlet-side constant pressure box exhaust port; 8. Stator thermostat; 81. Inlet-side perforated plate; 811. Inlet-side hole array; 821. Outlet-side hole array; 82. Outlet-side perforated plate; 83. Constant temperature zone; 9. Interlayer skeleton; 91. Interlayer cooling groove; 10. Side gap. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0033] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0034] Example 1

[0035] like Figures 1 to 4 As shown, this embodiment provides a low-temperature cooling structure that can be applied to various superconducting rotating motors that require a low-temperature cooling environment. It is particularly suitable for the compact structural layout of axial flux superconducting motors and can achieve uniform and efficient through-cooling of multi-layer superconducting windings 51.

[0036] The cryogenic cooling structure consists of an inlet-side constant pressure chamber 6, a stator thermostat 8, and an outlet-side constant pressure chamber 7 arranged sequentially along the axial direction. The superconducting winding assembly 5 is integrated inside the stator thermostat 8. The inlet-side constant pressure chamber 6 and the outlet-side constant pressure chamber 7 are respectively connected to an external cryogenic circulation system. The external cryogenic circulation system continuously supplies cryogenic fluid at a set temperature and pressure to the inlet-side constant pressure chamber 6 and recovers the heat-exchanged fluid discharged from the outlet-side constant pressure chamber 7 for recooling, thereby maintaining the continuous operation of the cooling circuit. Under the control of the external cryogenic circulation system, the fluid pressure inside the inlet-side constant pressure chamber 6 is always higher than the fluid pressure inside the outlet-side constant pressure chamber 7, thus forming a stable and controllable pressure difference between the two constant pressure chambers. This pressure difference serves as the driving force for the cryogenic fluid flow, driving the cryogenic fluid to flow unidirectionally from the inlet-side constant pressure chamber 6 to the outlet-side constant pressure chamber 7 along the axial direction. This avoids problems such as fluid backflow, turbulence, or large fluctuations in flow rate, providing stable hydrodynamic conditions for winding cooling.

[0037] Both the inlet-side constant pressure chamber 6 and the outlet-side constant pressure chamber 7 can adopt an annular cavity structure. The inner and outer diameters of the annular cavity are adapted to the circumferential arrangement range of the superconducting winding assembly 5, and can completely cover all the circumferentially arranged superconducting windings 51 along the circumferential direction of the stator assembly 4, ensuring that each superconducting winding 51 receives a uniform fluid supply. In addition to the annular cavity, in low-power circular superconducting motors, the constant pressure chamber can also adopt an integral circular cavity structure to adapt to the overall structural dimensions of the machine. The chamber body can be made of low-temperature adaptable materials such as austenitic stainless steel or high-strength aluminum alloy. These materials can maintain stable mechanical properties in cryogenic environments and will not suffer from low-temperature embrittlement. They also have low thermal conductivity, which can reduce the transfer of heat from the external environment to the interior of the chamber. To further reduce heat leakage, the outer surface of the constant pressure chamber can be covered with a multi-layer vacuum insulation structure. By alternately stacking multiple layers of reflective foil and spacers, the intrusion of ambient radiant heat into the chamber body is blocked, reducing the heat load of the cryogenic circulation system. The constant pressure chamber can be equipped with a flow equalization structure, such as a guide plate or a porous flow equalization plate at the fluid inlet, so that the low temperature fluid entering the chamber can quickly diffuse into the entire cavity, eliminating the problem of excessive local flow velocity or uneven pressure, ensuring that the fluid pressure at all locations inside the cavity is consistent, providing equal inlet pressure conditions for the cooling channels of each downstream winding, and ensuring the uniformity of cooling flow of each winding from the source.

[0038] The inlet-side constant pressure chamber 6 is equipped with an inlet-side constant pressure chamber air inlet 61, and the outlet-side constant pressure chamber 7 is equipped with an outlet-side constant pressure chamber exhaust port 71. Both the air inlet and exhaust port can use standard cryogenic pipeline connectors, which can be directly and sealed to the output and recovery pipelines of the external cryogenic circulation system. The number of air inlets can be set to one or more according to the motor power and cooling flow requirements. When multiple air inlets are set, they can be evenly arranged along the circumference of the constant pressure chamber, which, together with the internal flow equalization structure, further improves the uniformity of pressure distribution inside the chamber. The arrangement of the exhaust port corresponds to that of the air inlet, and it can also be evenly arranged circumferentially to ensure that the fluid on the outlet side can be discharged smoothly and avoid the problem of local pressure accumulation on the outlet side. The external cryogenic circulation system can be configured with a pressure regulating unit and a flow monitoring unit to collect pressure data inside the two constant pressure tanks in real time. By adjusting the output power of the refrigeration unit or the opening of the pipeline valves, the pressure difference between the two sides can be precisely controlled to ensure that the pressure difference is always maintained within the set range. This ensures that the flow rate and total flow of the cooling fluid are stable and adapts to the cooling needs of the motor under different operating conditions.

[0039] Cryogenic fluids can be selected from gaseous helium, gaseous neon, gaseous hydrogen, or liquid neon, with different fluid media suited to different operating temperature ranges. Gaseous helium has stable chemical properties and a wide applicable temperature range, adaptable to cooling requirements from room temperature to liquid helium temperature range, making it a commonly used cooling medium for high-temperature superconducting motors. Liquid neon has a large latent heat and stronger cooling capacity per unit volume, making it suitable for applications with high heat loads. In practical applications, the appropriate cryogenic fluid medium can be flexibly selected based on the critical temperature of the superconducting winding 51 and the system cooling cost.

[0040] The stator thermostat 8, located between the inlet-side constant pressure chamber 6 and the outlet-side constant pressure chamber 7, is the core structure that houses the superconducting winding assembly 5 and maintains a low-temperature operating environment. The stator thermostat 8 consists of an inlet-side perforated plate 81, an outlet-side perforated plate 82, and a constant-temperature zone 83 formed by the two. The constant-temperature zone 83 is an independent sealed chamber that completely encloses the superconducting winding assembly 5, isolating it from external heat interference. Both the inlet-side perforated plate 81 and the outlet-side perforated plate 82 are annular plate structures. Their outer and inner edges are fixed by annular connecting beams. The connection can be achieved by vacuum brazing or by using bolts and low-temperature seals for a detachable seal. The low-temperature seals can be indium wire seals or modified polytetrafluoroethylene (PTFE) gaskets. These sealing materials maintain good elasticity and sealing performance at low temperatures, preventing gas leakage or heat infiltration into the chamber. When a detachable connection is adopted, it is convenient to inspect, maintain or replace the internal superconducting winding assembly 5 in the later stage, thus improving the maintainability of the structure. When a welded connection is adopted, the sealing performance is better and the structural strength is higher, making it suitable for application scenarios with long-term stable operation.

[0041] An inlet-side perforated plate 81 is arranged between the inlet-side constant pressure box 6 and the superconducting winding assembly 5, serving as a fluid distribution structure between the inlet-side constant pressure box 6 and the constant temperature zone 83. An outlet-side perforated plate 82 is arranged between the superconducting winding assembly 5 and the outlet-side constant pressure box 7, serving as a fluid collection structure between the constant temperature zone 83 and the outlet-side constant pressure box 7. An inlet-side perforated plate 81 has an inlet-side perforated array 811, and an outlet-side perforated plate 82 has an outlet-side perforated array 821. The positions, quantities, and arrangements of the two sets of perforated arrays correspond one-to-one. The perforated arrays are partitioned according to the circumferential arrangement of the superconducting winding assembly 5. Each set of perforated arrays corresponds to the installation position of a superconducting winding 51, and each fluid through-hole in each set of perforated arrays is directly opposite the port of the interlayer cooling groove 91 within the corresponding superconducting winding 51. This partitioned arrangement allows the cryogenic fluid in the constant pressure box 6 on the inlet side to be precisely distributed through the hole array to each interlayer cooling groove 91 of each superconducting winding 51, avoiding disorderly diffusion of fluid in the constant temperature region 83, reducing meaningless flow loss, and improving the effective utilization rate of the cooling medium.

[0042] The fluid through-holes on the perforated plate can have circular, rectangular, or oblong cross-sections. The cross-sectional dimensions of the through-holes are adapted to the port dimensions of the interlayer cooling groove 91, ensuring that the fluid can smoothly enter the cooling groove from the through-holes and reducing the flow resistance caused by abrupt changes in cross-section. The edges of the through-holes can be rounded or chamfered to eliminate local turbulence caused by sharp edges and reduce fluid pressure loss. The arrangement density of the hole array can be differentiated according to the heating characteristics of different regions of the superconducting winding 51. For example, in the end joint area of ​​the superconducting winding 51, due to the relatively large joint loss and higher local heat generation, the through-hole arrangement in this area can be densified to increase the cooling flow rate in this area, achieve on-demand cooling, and further balance the overall temperature distribution of the winding. The perforated plate is also made of low-temperature-compatible metal materials and has sufficient structural strength to withstand the pressure difference force of the constant pressure boxes on both sides. It can also serve as the installation support structure for the superconducting winding assembly 5, providing a stable installation reference for the winding. The perforated plate can be processed with precision laser drilling or CNC milling to ensure the processing accuracy of the holes and the alignment accuracy between the through holes and the interlayer cooling grooves 91, thus avoiding the problems of increased flow resistance and uneven flow distribution caused by misalignment.

[0043] The superconducting winding assembly 5 is located inside the constant temperature zone 83 of the stator thermostat 8, and includes multiple superconducting windings 51 evenly arranged along the circumference. Each superconducting winding 51 has a fan-shaped structure, and multiple fan-shaped superconducting windings 51 are spliced ​​together to form a complete annular stator winding structure. Each superconducting winding 51 is formed by stacking multiple layers of superconducting windings 51 axially. The superconducting winding layers 51 are formed by winding superconducting strips according to a preset winding method. The superconducting strips can be bismuth-based or yttrium-based high-temperature superconducting strips, or low-temperature superconducting wires can be selected according to the operating temperature range to adapt to different motor performance requirements and cooling system configurations. After stacking multiple layers of superconducting windings 51, the current carrying capacity and excitation magnetic performance of the windings can be effectively improved to meet the design requirements of high power density motors. The ends of the superconducting windings 51 are provided with joint structures to realize the electrical connection between windings and the connection with external power supply lines. The joint area is treated with a low-resistance welding process to reduce joint loss and reduce local heat generation.

[0044] An interlayer skeleton 9 is provided between two adjacent superconducting winding layers 51. The outline of the interlayer skeleton 9 matches the outline of the superconducting winding layer 51 and completely fills the space between the adjacent superconducting winding layers 51. The interlayer skeleton 9 serves two purposes: firstly, it acts as an interlayer support structure, providing stable axial support for the multi-layer superconducting winding 51 layers, ensuring the positional accuracy and structural stability between each winding layer, and preventing deformation or displacement of the windings under electromagnetic forces; secondly, it acts as an interlayer insulation structure, isolating adjacent superconducting winding layers 51 and meeting the electrical insulation requirements of the windings. The interlayer skeleton 9 can be made of glass fiber reinforced epoxy composite material. This type of material has high specific strength and excellent insulation performance, while having low thermal conductivity, which can reduce heat conduction between different winding layers and reduce the mutual temperature influence between layers. In addition, the interlayer skeleton 9 can also be made of other engineering materials that meet the requirements of low-temperature mechanical properties and insulation performance, and can be flexibly selected according to the needs of the actual application scenario.

[0045] Interlayer cooling grooves 91 are formed on the interlayer frame 9, extending along the extension direction of the superconducting winding 51, that is, from the radial inner end to the radial outer end of the superconducting winding 51, forming a cooling channel that runs through the entire radial length of the winding. Multiple interlayer cooling grooves 91 can be formed in parallel on a single interlayer frame 9, and the multiple cooling grooves are evenly arranged along the circumferential width of the winding. A supporting rib structure is retained between two adjacent cooling grooves. The top and bottom surfaces of the supporting ribs are in close contact with the superconducting winding 51 layers on both sides, ensuring the supporting strength while also conducting the heat of the winding to the cooling groove area, thus enhancing the heat transfer effect. The cross-sectional shape of the interlayer cooling groove 91 can be set as rectangular, semi-circular, or trapezoidal, and different cross-sectional shapes have different heat transfer and flow characteristics. Rectangular cross-section cooling tanks are simple to manufacture, have smooth walls, and stable heat transfer area, making them suitable for mass production. Semi-circular cross-section cooling tanks have smooth inner wall transitions, low fluid flow resistance, and can reduce the pressure difference requirement for fluid drive. Trapezoidal cross-section cooling tanks can generate stronger turbulence in the fluid within the tank, enhancing convective heat transfer, making them suitable for applications with high heat density. In practical applications, the appropriate cooling tank cross-section can be flexibly selected based on cooling flow requirements, pressure difference limitations, and manufacturing process conditions. The inner wall of the interlayer cooling tank 91 can also undergo microstructural treatment, such as machining micro-ribs or creating a rough surface, to further enhance the turbulence of the fluid within the tank, improve the convective heat transfer coefficient, and increase heat transfer capacity without increasing the cross-sectional area of ​​the cooling tank, making it suitable for high-load motor operation scenarios.

[0046] The interlayer skeleton 9 and the superconducting winding 51 layers can be bonded and fixed with low-temperature-compatible epoxy resin, ensuring a tight fit between the two, eliminating contact gaps, reducing contact thermal resistance, and enabling the heat generated by the superconducting winding 51 layers to be quickly transferred to the low-temperature fluid in the interlayer cooling tank 91, thereby improving heat exchange efficiency. The two ends of all interlayer cooling tanks 91 are respectively connected to the inlet side hole array 811 of the inlet side perforated plate 81 and the outlet side hole array 821 of the outlet side perforated plate 82, thus connecting the inlet side hole array 811, the interlayer cooling tank 91 and the outlet side hole array 821 in sequence to form a complete through-type low-temperature cooling flow path.

[0047] During actual operation, driven by the stable pressure difference between the inlet-side constant pressure tank 6 and the outlet-side constant pressure tank 7, the cryogenic fluid first flows from the inlet-side constant pressure tank 6 through the perforated array of the inlet-side perforated plate 81 and enters the interlayer cooling tank 91 corresponding to each superconducting winding 51. The cryogenic fluid flows continuously radially along the winding within the interlayer cooling tank 91, undergoing thorough convective heat exchange with the surfaces of the superconducting winding 51 layers on both sides of the cooling tank. It continuously absorbs AC losses, joint losses, and other conducted heat generated by the operation of the superconducting winding 51, achieving primary cooling of the core interlayer region of the superconducting winding 51. After heat exchange, the cryogenic fluid flows out from the other end of the interlayer cooling tank 91, collects through the perforated array of the outlet-side perforated plate 82 and enters the outlet-side constant pressure tank 7, finally returning to the external cryogenic circulation system through the exhaust port 71 of the outlet-side constant pressure tank, completing one cooling cycle.

[0048] In addition to the main cooling fluid flowing through the interlayer cooling tank 91, a portion of the cryogenic fluid flowing out from the perforated plate 81 on the inlet side enters the gap between adjacent superconducting windings 51, as well as the local gap between the outer side of the superconducting winding 51 and the inner wall of the constant temperature zone 83, flowing axially from the inlet side to the outlet side. This portion of fluid can directly scour the circumferential and radially outer surfaces of the superconducting winding 51, carrying away the heat generated on the side of the winding, thus providing auxiliary cooling for the superconducting winding 51. The auxiliary cooling flow path can cover the winding side areas that the interlayer cooling tank 91 cannot directly act on, eliminating cooling blind spots and allowing all surfaces of the superconducting winding 51 to contact the cryogenic fluid for heat exchange, further improving the overall temperature uniformity of the winding and avoiding local hot spots. The auxiliary cooling fluid eventually flows into the constant pressure tank 7 on the outlet side and is discharged together with the fluid in the main cooling flow path, without adding extra complexity to the fluid loop.

[0049] Inside the constant-temperature zone 83, except for the superconducting winding assembly 5, the remaining space can maintain a low-pressure static gas environment or be filled with low-temperature insulating support material with low thermal conductivity, further reducing convective and radiative heat transfer within the chamber and minimizing the impact of external heat leakage on the winding temperature. The overall sealed design of the stator thermostat 8 effectively isolates the external ambient temperature environment. Combined with the low-temperature shielding effect of the constant-pressure boxes on both sides, the constant-temperature zone 83 can maintain a stable low-temperature environment for a long time, providing reliable operating conditions for the superconducting winding 51.

[0050] Example 2

[0051] This embodiment provides a superconducting motor that adopts the aforementioned low-temperature cooling structure, featuring good cooling uniformity, high operational stability, and high power density. It can be applied to various scenarios such as aerospace propulsion, ship electric propulsion, and high-power power generation.

[0052] The superconducting motor includes a stator assembly 4, a mover assembly 1, and an air gap 3 between the stator assembly 4 and the mover assembly 1. A cryogenic cooling structure is integrated and located on one side of the superconducting winding assembly 5. This embodiment uses a single-air-gap 3 axial flux superconducting motor as an example. The mover assembly 1 is located on one axial side of the stator assembly 4 and has a disk-shaped structure that can rotate around the central axis of the motor. The yoke of the mover assembly 1 is made of laminated low-carbon steel or silicon steel sheets with excellent magnetic permeability, used to form the main magnetic circuit of the motor and reduce magnetic reluctance. A permanent magnet 2 is fixedly mounted on the end face of the mover assembly 1 facing the stator assembly 4. The permanent magnet 2 can be made of rare-earth permanent magnet materials with high magnetic energy product, such as neodymium iron boron permanent magnet 2 or samarium cobalt permanent magnet 2, possessing high remanence and coercivity, and can maintain stable magnetic properties in high-temperature environments. The permanent magnets 2 can be arranged evenly along the circumference in an alternating manner of N and S poles, or they can be arranged in a Halbach array, thereby increasing the sinusoidal degree of the magnetic flux density of the air gap 3, reducing the torque pulsation of the motor, and improving the smoothness of operation.

[0053] The permanent magnet 2 can be fixed to the yoke surface of the mover assembly 1 by adhesive bonding using low-temperature, high-strength structural adhesive to ensure the bonding strength can withstand the centrifugal force generated by high-speed rotation. Alternatively, it can be fixed by embedding, where a mounting groove matching the shape of the permanent magnet 2 is machined on the yoke surface of the mover assembly 1, and the permanent magnet 2 is embedded into the mounting groove and bonded in place. This fixing method has higher structural reliability, can withstand greater centrifugal loads, and is suitable for high-speed motor applications. An air gap 3 of a predetermined thickness is left between the permanent magnet 2 and the stator assembly 4. This air gap 3 serves as the space for the motor's magnetic circuit and energy transfer. The thickness of the air gap 3 can be precisely adjusted according to the electromagnetic design requirements of the motor to balance the motor's power density and excitation losses.

[0054] The cryogenic cooling structure is fixedly mounted on the stator assembly 4. The stator assembly 4 includes a stator frame and a stator yoke. The stator yoke is made of silicon steel sheets or solid magnetic materials with excellent magnetic permeability and is used to form the main magnetic circuit of the motor. The outlet-side constant pressure box 7 of the cryogenic cooling structure can be directly fixedly mounted on the end face of the stator yoke. The stator thermostat 8 and the inlet-side constant pressure box 6 are arranged sequentially towards the air gap 3, with the inlet-side constant pressure box 6 positioned close to the air gap 3. The outer wall of the inlet-side constant pressure box 6 facing the air gap 3 is directly opposite the mover assembly 1 and the permanent magnet 2. Since a cryogenic fluid continuously flows inside the inlet-side constant pressure box 6, the box wall will maintain a low temperature. Therefore, the inlet-side constant pressure box 6 can also be used as a cryogenic cooling shield.

[0055] During motor operation, the mover assembly 1 and permanent magnet 2 generate a certain amount of heat loss. Simultaneously, heat from the external environment is transferred to the air gap 3 region through the casing. This heat is transferred to the stator side via radiation and convection. The outer wall of the inlet-side constant pressure box 6, operating at low temperatures, absorbs most of the radiant and convective heat, preventing further heat transfer to the internal stator thermostat 8 and superconducting winding 51, effectively reducing the thermal load on the superconducting winding 51. At the same time, the cooling effect of the inlet-side constant pressure box 6 indirectly reduces the operating temperature of the mover-side permanent magnet 2, preventing demagnetization due to prolonged high-temperature operation, improving the lifespan and magnetic stability of the permanent magnet 2, and ultimately enhancing the overall reliability and lifespan of the motor.

[0056] The motor is externally housed in a casing, which can be made of cast iron or aluminum alloy, providing mechanical protection for the internal stator assembly 4, mover assembly 1, and cryogenic cooling structure. The casing may contain a vacuum insulation cavity or be filled with porous insulation material to reduce heat transfer from the external environment to the motor, thus lowering the overall thermal load of the cryogenic cooling system. The motor shaft is supported on the stator frame by cryogenic bearings, which can be ceramic rolling bearings or steel bearings compatible with cryogenic grease, ensuring stable rotation even at low temperatures and reducing frictional losses. A rotary seal structure is installed between the shaft and the casing to ensure a sealed environment inside the casing, minimizing the intrusion of external heat.

[0057] During motor operation, the external cryogenic circulation system continuously operates, maintaining a stable pressure difference between the inlet-side constant pressure tank 6 and the outlet-side constant pressure tank 7. This drives the cryogenic fluid to continuously flow through the interlayer cooling groove 91 and side gap 10 of the superconducting winding 51, continuously carrying away the heat loss generated by the superconducting winding 51 and ensuring that the superconducting winding 51 remains within a safe operating range below the critical temperature. When an alternating current is applied to the superconducting winding 51, it generates an alternating magnetic field, which interacts with the magnetic field of the permanent magnet 2 on the mover side to produce electromagnetic torque, driving the mover assembly 1 to rotate around its axis, thus converting electrical energy into mechanical energy. Throughout the entire operation, the cryogenic cooling structure provides a uniform and stable cooling environment for the superconducting winding 51. Even under high load and high speed conditions, it effectively prevents localized heat accumulation inside the winding, eliminates the risk of localized quenching, and ensures continuous and stable motor operation.

[0058] In addition to the single-air-gap 3 structure, this superconducting motor can also adopt a double-air-gap 3 topology. The mover assembly 1 is respectively positioned on both axial sides of the stator assembly 4, forming a double-air-gap 3 structure with movers on both sides. In this case, the stator assembly 4 is located in the middle, with air gaps 3 and mover assemblies 1 on both sides. The corresponding cryogenic cooling structure can be achieved by setting inlet-side constant pressure boxes 6 on both sides of the stator assembly 4 and outlet-side constant pressure box 7 in the middle, forming a flow path structure with air inlet on both sides and air outlet in the middle. Both inlet-side constant pressure boxes 6 can act as cryogenic cooling shields to thermally shield the mover assemblies 1 on both sides. This double-air-gap 3 structure results in higher motor torque density, and the double-side cooling shield effect can simultaneously control the thermal load of the movers on both sides, ensuring the overall thermal stability of the motor. This is suitable for applications with extremely high power density requirements.

[0059] It should be noted that the above description in this embodiment uses the structure where the superconducting winding assembly 5 is located on the stator assembly 4 as an example. In actual engineering applications, this cryogenic cooling structure can also be adapted to the application scenario where the superconducting winding assembly 5 is located on the mover assembly 1. When the superconducting winding assembly 5 is located on the mover assembly 1, the cryogenic cooling structure rotates together with the mover assembly 1. The inlet-side constant pressure box 6 is still located close to the air gap 3, and the outlet-side constant pressure box 7 is arranged on the side of the mover assembly 1 facing away from the air gap 3. The cryogenic fluid can be introduced into the rotating inlet-side constant pressure box 6 from the fixed external pipeline through a rotary sealing joint, flow through the internal cooling flow path, and then be led out from the outlet-side constant pressure box 7 to the external recovery pipeline through the rotary sealing joint. In this application scenario, the cooling path configuration, fluid flow pattern, and cooling effect are completely consistent with the stator-side arrangement, achieving uniform, continuous cooling of the multi-layer superconducting winding 51. Simultaneously, the constant pressure box 6 near the inlet side of the air gap 3 can still act as a cryogenic cooling shield, absorbing heat transferred from the stator side and maintaining the operational stability of the mover-side superconducting winding 51. This structure can flexibly adapt to both stator and mover superconducting motor topologies, exhibiting broad application adaptability.

[0060] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or equivalent to the scope of this invention are included in this invention.

Claims

1. A low-temperature cooling structure, characterized in that, It includes an inlet-side constant pressure box (6), an outlet-side constant pressure box (7), a stator thermostat (8), and a superconducting winding assembly (5). The inlet-side constant pressure box (6) and the outlet-side constant pressure box (7) are located on opposite sides of the stator thermostat (8) along the axial direction. The inlet-side constant pressure box (6) and the outlet-side constant pressure box (7) are connected to an external cryogenic circulation system. The fluid pressure in the inlet-side constant pressure box (6) is higher than the fluid pressure in the outlet-side constant pressure box (7) to form a stable pressure difference between the inlet-side constant pressure box (6) and the outlet-side constant pressure box (7) to drive the unidirectional flow of cryogenic fluid. The stator thermostat (8) includes an inlet-side perforated plate (81), an outlet-side perforated plate (82), and a constant temperature region (83) enclosed by the inlet-side perforated plate (81) and the outlet-side perforated plate (82), and the superconducting winding assembly (5) is disposed within the constant temperature region (83). The inlet-side perforated plate (81) is disposed between the inlet-side constant pressure box (6) and the superconducting winding assembly (5), and the outlet-side perforated plate (82) is disposed between the superconducting winding assembly (5) and the outlet-side constant pressure box (7); the inlet-side perforated plate (81) is provided with an inlet-side hole array (811), and the outlet-side perforated plate (82) is provided with an outlet-side hole array (821). The superconducting winding assembly (5) includes multiple superconducting windings (51) arranged along the circumferential direction. Each superconducting winding (51) includes multiple superconducting winding layers stacked together. An interlayer skeleton (9) is provided between adjacent superconducting winding layers. An interlayer cooling groove (91) is provided on the interlayer skeleton (9). The inlet side hole array (811), the interlayer cooling tank (91), and the outlet side hole array (821) are connected in sequence to form a cryogenic cooling flow path for unidirectional flow of cryogenic fluid.

2. The low-temperature cooling structure according to claim 1, characterized in that, The inlet side hole array (811) and the outlet side hole array (821) are arranged in sections according to the position of the superconducting winding assembly (5). Each group of hole arrays corresponds to the position of at least one superconducting winding (51), and each fluid through hole in each group of hole arrays is connected to the interlayer cooling groove (91) in the corresponding superconducting winding (51).

3. The low-temperature cooling structure according to claim 1, characterized in that, The inlet-side constant pressure box (6) and the outlet-side constant pressure box (7) are both annular or circular cavities, extending along the circumferential direction of the stator assembly to cover multiple superconducting windings (51) arranged along the circumferential direction.

4. The low-temperature cooling structure according to claim 1, characterized in that, The interlayer cooling groove (91) is opened on the interlayer skeleton (9) along the extension direction of the superconducting winding (51), and the cross-sectional shape of the interlayer cooling groove (91) is one of rectangle, semi-circle or trapezoid.

5. The low-temperature cooling structure according to claim 1, characterized in that, The constant temperature zone (83) of the stator thermostat (8) is a sealed chamber. The inlet side perforated plate (81) and the outlet side perforated plate (82) are fixedly connected by fasteners or welding to enclose the superconducting winding assembly (5) in the constant temperature zone (83).

6. The low-temperature cooling structure according to claim 1, characterized in that, When the cryogenic fluid flows through the interlayer cooling tank (91), some of the cryogenic fluid flows along the gap between adjacent superconducting windings (51) or the local gap outside the superconducting windings (51) to provide auxiliary cooling to the side of the superconducting windings (51).

7. The low-temperature cooling structure according to claim 1, characterized in that, The inlet-side constant pressure box (6) is provided with an inlet-side constant pressure box air inlet (61), and the outlet-side constant pressure box (7) is provided with an outlet-side constant pressure box exhaust port (71); the inlet-side constant pressure box air inlet (61) is used to connect with the low temperature fluid output pipeline of the external low temperature circulation system, and the outlet-side constant pressure box exhaust port (71) is used to connect with the low temperature fluid recovery pipeline of the external low temperature circulation system.

8. The low-temperature cooling structure according to claim 1, characterized in that, When the cryogenic cooling structure is applied to the axial flux superconducting motor, the inlet-side constant pressure box (6) is located close to the air gap (3) of the axial flux superconducting motor, and the outer wall of the inlet-side constant pressure box (6) faces the mover assembly (1) and permanent magnet (2) of the axial flux superconducting motor; the cryogenic fluid introduced into the inlet-side constant pressure box (6) keeps the outer wall of the inlet-side constant pressure box (6) at a low temperature, so that the inlet-side constant pressure box (6) acts as a cryogenic cooling screen to absorb the heat radiated or conducted by the mover assembly (1) and / or the permanent magnet (2).

9. A superconducting motor, characterized in that, It includes a stator assembly (4), a mover assembly (1), an air gap (3) disposed between the stator assembly (4) and the mover assembly (1), and a low-temperature cooling structure as described in any one of claims 1 to 8; The superconducting winding assembly (5) is disposed on the stator assembly (4) or the mover assembly (1); the cryogenic cooling structure is fixedly disposed on the side where the superconducting winding assembly (5) is located; The mover assembly (1) is disposed on one or both sides of the stator assembly (4) along the axial direction. A permanent magnet (2) is disposed on the side of the mover assembly (1) facing the stator assembly (4), and the air gap (3) is formed between the permanent magnet (2) and the stator assembly (4).

10. The superconducting motor according to claim 9, characterized in that, The permanent magnet (2) is fixed to the surface of the moving part (1) by bonding or embedding; the constant pressure box (6) on the inlet side of the low temperature cooling structure acts as a low temperature cold screen to absorb the heat radiated from the moving part (1) and / or the permanent magnet (2) to the stator part (4).

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