Low-temperature circulating cooling system for magnetic suspension superconducting magnet

Abstract

The invention discloses a low-temperature circulating cooling system for a magnetic suspension superconducting magnet, which relates to the technical field of magnetic suspension and is characterized in that a cooling device is arranged on the superconducting magnet, and a refrigerating machine is arranged on the side surface of the cooling device; a built-in superconducting motor is arranged in the cooling device, a superconducting motor stator and a superconducting motor rotor are borne in the built-in superconducting motor through bearings, and the superconducting motor stator and the superconducting motor rotor are matched with the built-in superconducting motor outer Dewar through a secondary condenser to achieve a concentric state; the rotor sealing cylinder is arranged between the superconducting motor rotor and the superconducting motor stator, and the rotor sealing cylinder is connected with a circulating gas inlet and a circulating gas outlet. Through the built-in superconducting motor, the problems of rotating shaft heat conduction and heat leakage, gas heat transfer, rotating shaft high-pressure sealing and the like due to the fact that a driving motor is externally arranged in a traditional low-temperature circulating system are solved. The mode that the magnetic suspension magnet can only be cooled through liquid helium filling is avoided, and the operation cost is saved.

Description

Technical Field

[0001] This invention relates to the field of magnetic levitation technology, and in particular to a low-temperature circulating cooling system for magnetically levitated superconducting magnets. Background Technology

[0002] High-speed maglev railways can solve problems such as wheel-rail adhesion, friction, and vibration inherent in wheel-rail railways, and have greater potential for speed increases (>600km / h), gradually becoming a research hotspot in the field of ground transportation in recent years. Meanwhile, in the fields of electromagnetic catapults and electromagnetic propulsion, achieving higher launch speeds is a common goal, with the use of superconducting magnets to generate stronger magnetic fields and thus achieve higher speeds considered a promising approach.

[0003] The existing technology ZL202210218819.X, "A Magnetic Levitation Superconducting Magnet Device with a Cooling System," only provides cooling and condensation under gravity, resulting in extremely low efficiency. While forced cooling via a motor could potentially solve this inefficiency, traditional cryogenic circulation systems, due to their externally mounted drive motors, suffer from issues such as heat leakage through the shaft, gas heat transfer, and high-pressure sealing of the shaft, making them difficult to apply to magnetic levitation superconducting magnets. Furthermore, given the scarcity of helium resources, achieving efficient cooling and low-cost operation of the superconducting magnets in this type of superconducting magnetic levitation system is crucial for its large-scale engineering application. Summary of the Invention

[0004] This invention provides a cryogenic circulating cooling system for magnetically levitated superconducting magnets, addressing the challenges of applying traditional cryogenic circulating systems to magnetically levitated superconducting magnets, such as external drive motors, heat leakage due to shaft heat conduction, gas heat transfer, and high-pressure shaft sealing. It also addresses the issue of helium scarcity, which hinders efficient cooling and low-cost operation of superconducting magnets in superconducting magnetic levitation systems.

[0005] On one hand, embodiments of the present invention provide a cryogenic circulating cooling system for a magnetically levitated superconducting magnet, comprising: A superconducting magnet, wherein a cooling device is provided on the superconducting magnet, and a refrigerator is provided on the side of the cooling device; The cooling device is equipped with a built-in superconducting motor. The superconducting motor stator and the superconducting motor rotor are supported by bearings in the built-in superconducting motor. The superconducting motor stator and the superconducting motor rotor are concentrically connected by a two-stage condenser and an external Dewar condenser of the built-in superconducting motor. The superconducting motor rotor includes a rotor metal frame, a rotor superconducting ring, and rotor permanent magnet components. The rotor metal frame is disposed on the bearing, and multiple rotor permanent magnet components are disposed on the rotor metal frame. The rotor superconducting ring is disposed on the rotor metal frame. A rotor sealing cylinder is provided around the rotor metal frame. The rotor sealing cylinder is located between the superconducting motor rotor and the superconducting motor stator. The rotor sealing cylinder seals and isolates the superconducting motor rotor and the superconducting motor stator. The built-in superconducting motor is provided with a circulating gas inlet and a circulating gas outlet. The circulating gas outlet is connected to a gas outlet and a liquid inlet. The rotor sealing cylinder is connected to the circulating gas inlet and the circulating gas outlet respectively.

[0006] In one possible implementation, the superconducting motor stator includes a stator fixed outer cylinder, a stator lamination core, and a stator winding coil. Multiple stator lamination cores are provided, and the multiple stator lamination cores are arranged in a ring around the bearing. The stator winding coil is wound on each stator lamination core, and the stator fixed outer cylinder is sleeved around the multiple stator lamination cores.

[0007] In one possible implementation, the circulating gas inlet is connected to the spiral condenser tube on the secondary condenser, the built-in superconducting motor is connected to the secondary condenser via a flange connecting the secondary cooling structure of the refrigerator, the spiral condenser tube on the secondary condenser is connected to the spiral condenser tube on the primary condenser via a condenser connecting pipe, the primary condenser is connected to the primary cooling head flange of the refrigerator, the secondary condenser is connected to the secondary cooling head flange of the refrigerator, the inlet of the spiral condenser tube on the primary condenser is connected to a transition bellows for the magnet exhaust port, and the spiral condenser tube on the primary condenser is also connected to an exhaust port.

[0008] In one possible implementation, the cooling device is equipped with an internal superconducting motor external Dewar, and an internal superconducting motor cold screen is provided between the internal superconducting motor external Dewar and the internal superconducting motor. The external Dewar is flanged and connected to the external Dewar, and the cold screen is flanged and connected to the cold screen. An external Dewar connecting transition bellows is provided on the internal superconducting motor external Dewar, and the external Dewar connecting transition bellows connects the internal superconducting motor external Dewar and the vacuum external Dewar of the superconducting magnet. The gas outlet and the magnet exhaust port transition bellows are respectively connected to the magnet liquid inlet and the magnet gas return port inside the external Dewar connecting transition bellows.

[0009] In one possible implementation, a superconducting magnet cold shield is provided outside the helium tank of the superconducting magnet. The superconducting magnet cold shield is wrapped by the vacuum external Dewar. The vacuum external Dewar is provided with a vacuum interface. The side of the vacuum interface on the vacuum external Dewar is also provided with a current lead interface and a signal line interface.

[0010] In one possible implementation, the built-in superconducting motor is supported on the external Dewar of the built-in superconducting motor by a built-in superconducting support structure.

[0011] In one possible implementation, the central part of the built-in superconducting support structure is connected to the built-in superconducting motor cold screen heat sink function.

[0012] The cryogenic circulating cooling system for the magnetically levitated superconducting magnet in this invention has the following advantages: (1) By combining high-temperature superconducting windings with permanent magnets, the efficiency of the motor is improved and the heat load loss during operation is greatly reduced.

[0013] (2) Make full use of the cooling equipment of the superconducting magnetic levitation magnet itself, introduce a high-temperature superconducting winding combined with a permanent magnet as the rotor’s built-in circulating forced flow fan, utilize the original system’s low-temperature cold source, and without introducing an additional dedicated superconducting motor cooling source, the system’s cooling efficiency can be greatly improved, the cooling time can be shortened, and excessive waste of liquid helium resources can be avoided.

[0014] (3) The adoption of a fully integrated motor structure solves the problem of excessive heat transfer and leakage caused by the traditional motor being placed outside the vacuum Dewar. At the same time, it also solves the problems of low temperature and high pressure sealing and wear caused by the traditional motor needing to drive the impeller to rotate directly in contact with the low temperature gas, thus improving the reliability of the system operation.

[0015] (4) Through a special hollow rotor structure, the low-temperature fan combines the rotating impeller with the rotor, achieving a direct and efficient combination of rotation and gas propulsion. This also provides effective strength support for the rotor structure, acts as a framework for the superconducting coils to resist high-speed rotational deformation, and the superconducting coils are arranged at a certain angle to avoid imbalance caused by rotor thrust fluctuations, thus ensuring smoother operation. Furthermore, this avoids the imbalance problem caused by placing the rotating impeller at one end of the rotor, a problem common in traditional fans. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A general diagram of the superconducting magnetic levitation magnet and the cryogenic circulation system device for the magnetic levitation superconducting magnet cryogenic circulation cooling system provided in the embodiments of this application; Figure 2 A schematic diagram of a superconducting magnetic levitation cooling device for a cryogenic circulating cooling system for a magnetic levitation superconducting magnet provided in an embodiment of this application; Figure 3A schematic diagram of the circulation pipeline of the superconducting magnetic levitation cryogenic circulation system device provided in the embodiments of this application for the cryogenic circulation cooling system of the magnetic levitation superconducting magnet; Figure 4 A schematic diagram of the overall structure and supporting components of the superconducting motor of the magnetic levitation superconducting magnet cryogenic circulating cooling system provided in the embodiments of this application; Figure 5 A schematic diagram of the overall structure and gas circulation pipeline of the superconducting motor of the magnetic levitation superconducting magnet cryogenic circulating cooling system provided in the embodiments of this application; Figure 6 A three-dimensional schematic diagram of the overall structure of the superconducting motor and the gas circulation pipeline of the cryogenic circulating cooling system for the magnetic levitation superconducting magnet provided in the embodiments of this application. Figure 7 This is the core component inside the superconducting motor of the magnetic levitation superconducting magnet cryogenic circulating cooling system provided in the embodiments of this application; Figure 8 This is an exploded view of the superconducting motor of the cryogenic circulating cooling system for a magnetic levitation superconducting magnet provided in an embodiment of this application.

[0018] Explanation of the labels in the diagram: 1. Cooling device; 2. Refrigeration unit; 3. Current lead interface; 4. Signal line interface; 5. Vacuum interface; 6. Protruding structure of the external Dewar support rod of the magnet; 7. Helium return pipeline; 8. Superconducting magnet cold shield; 9. Vacuum external Dewar; 10. Superconducting magnet; 11. PCS superconducting switch; 12. Liquid inlet pipe; 13. Magnet liquid inlet; 14. Magnet gas return port; 15. Connection unit; 16. Built-in superconducting motor; 101. External Dewar; 102. Cold shield; 103. Secondary condenser; 104. Primary condenser; 105. Liquid inlet; 106. Exhaust port; 107. Safety valve; 108. Condenser connecting pipe; 109. Gas outlet; 110. Magnet exhaust port transition corrugated pipe; 111. External Dewar connection transition corrugated pipe; 112. Vacuum port; 161. Built-in superconducting motor 162. External Dewar; 163. Built-in superconducting motor cold shield; 164. Built-in superconducting support structure; 165. Connection flange of the secondary cooling structure of the refrigerator; 166. Circulating gas inlet; 167. Circulating exhaust port; 168. Built-in superconducting motor rotor sliding bearing; 169. Built-in superconducting motor rotor rotating support ring; 1610. Bearing; 1611. Connection interface between the built-in superconducting motor and the external liquid inlet; 1611. Superconducting motor stator; 16111. Stator laminated iron core; 16112. Stator winding coil; 16113. Stator fixed outer cylinder; 1612. Superconducting motor rotor; 16121. Rotor metal frame; 16122. Rotor superconducting ring; 16123. Rotor permanent magnet component; 16124. Rotor sealing cylinder; 201. Primary cold head of the refrigerator; 202. Secondary cold head of the refrigerator. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Figure 1 This is a schematic diagram of a cryogenic circulating cooling system for a magnetically levitated superconducting magnet provided in an embodiment of the present invention; the embodiment of the present invention provides a cryogenic circulating cooling system for a magnetically levitated superconducting magnet, comprising: A superconducting magnet 10, wherein a cooling device 1 is provided on the superconducting magnet 10, and a refrigerator 2 is provided on the side of the cooling device 1; The cooling device 1 is equipped with a built-in superconducting motor 16. The built-in superconducting motor 16 carries the superconducting motor stator 1611 and the superconducting motor rotor 1612 through the bearing 169. The superconducting motor stator 1611 and the superconducting motor rotor 1612 are concentrically connected through the cooperation of the secondary condenser 103 and the built-in superconducting motor external Dewar 161. The superconducting motor rotor 1612 includes a rotor metal frame 16121, a rotor superconducting ring 16122, and a rotor permanent magnet component 16123. The rotor metal frame 16121 is disposed on the bearing 169. Multiple rotor permanent magnet components 16123 are disposed on the rotor metal frame 16121. The rotor superconducting ring 16122 is disposed on the rotor metal frame 16121. The rotor metal frame 16121 is surrounded by a rotor sealing cylinder 16124, which is located between the superconducting motor rotor 1612 and the superconducting motor stator 1611. The rotor sealing cylinder 16124 seals and isolates the superconducting motor rotor 1612 and the superconducting motor stator 1611. The built-in superconducting motor 16 is provided with a circulating gas inlet 165 and a circulating exhaust port 166. The circulating exhaust port 166 is connected to a gas outlet 109 and a liquid inlet 105. The rotor sealing cylinder 16124 is connected to the circulating gas inlet 165 and the circulating exhaust port 166 respectively.

[0021] The superconducting motor stator 1611 includes a stator fixed outer cylinder 16113, a stator lamination core 16111, and a stator winding coil 16112. Multiple stator lamination cores 16111 are provided, and the multiple stator lamination cores 16111 are arranged in a ring around the bearing 169. The stator winding coil 16112 is wound on each stator lamination core 16111, and the stator fixed outer cylinder 16113 is sleeved around the multiple stator lamination cores 16111.

[0022] The circulating gas inlet 165 is connected to the spiral condenser tube on the secondary condenser 103. The built-in superconducting motor 16 is connected to the secondary condenser 103 through the secondary cooling structure connecting flange 164. The spiral condenser tube on the secondary condenser 103 is connected to the spiral condenser tube on the primary condenser 104 through the condenser connecting pipe 108. The primary condenser 104 is connected to the primary cooling head 201 flange of the refrigerator 2. The secondary condenser 103 is connected to the secondary cooling head 202 flange of the refrigerator 2. The spiral condenser tube inlet on the primary condenser 104 is connected to the magnet exhaust port transition corrugated pipe 110. The spiral condenser tube on the primary condenser 104 is also connected to the exhaust port 106.

[0023] The cooling device 1 is equipped with a built-in superconducting motor external Dewar 161. A built-in superconducting motor cold screen 162 is provided between the built-in superconducting motor external Dewar 161 and the built-in superconducting motor 16. The built-in superconducting motor external Dewar 161 is flanged and connected to the external Dewar 101. The built-in superconducting motor cold screen 162 is flanged and connected to the cold screen 102. An external Dewar connecting transition bellows 111 is provided on the built-in superconducting motor external Dewar 161. The external Dewar connecting transition bellows 111 connects the built-in superconducting motor external Dewar 161 and the vacuum external Dewar 9 of the superconducting magnet 10. The gas outlet 109 and the magnet exhaust port transition bellows 110 are respectively connected to the magnet liquid inlet 13 and the magnet gas return port 14 in the external Dewar connecting transition bellows 111.

[0024] The superconducting magnet 10 has a superconducting magnet cold screen 8 outside its helium tank. The superconducting magnet cold screen 8 is wrapped by the vacuum external Dewar 9. The vacuum external Dewar 9 has a vacuum interface 5. The side of the vacuum interface 5 on the vacuum external Dewar 9 also has a current lead interface 3 and a signal line interface 4.

[0025] The built-in superconducting motor 16 is supported on the external Dewar 161 of the built-in superconducting motor by the built-in superconducting support structure 163.

[0026] The middle part of the built-in superconducting support structure 163 is functionally connected to the heat sink of the built-in superconducting motor cooling screen 162.

[0027] For example, Figure 1 , 2 The present invention includes a cooling device 1 placed on a superconducting magnet 10, the two being vacuum-connected via a bellows. The cooling device 1 receives its cold source from a refrigerator 2, achieving circulating cooling of helium gas. The cooling device 1 comprises an outer Dewar 101, a cold shield 102, a refrigerator 2, a liquid inlet 105, an exhaust port 106, a safety valve 107, a vacuum port 112, a gas outlet 109 connected to the magnet, a transition bellows 110 for the magnet exhaust port, and a transition bellows 111 connecting the outer Dewar. It also includes an internal primary condenser 104, a secondary condenser 103, a condenser connecting pipe 108, and a built-in superconducting motor 16. The refrigerator 2 is equipped with a primary cold head 201 and a secondary cold head 202.

[0028] The system also includes a superconducting magnet 10. A superconducting coil is fixedly placed inside a helium tank. The superconducting coil's frame features arc-shaped microfins and a microporous structure, increasing the heat exchange area and reducing the contact thermal resistance between the cold helium gas and the coil without increasing eddy currents. A superconducting magnet cold shield 8 is arranged outside the helium tank to reduce the thermal load on the low-temperature components of the helium tank caused by thermal radiation at the high-temperature end of the system (vacuum external Dewar 9). The superconducting magnet cold shield 8 is completely enclosed by the vacuum external Dewar 9. During operation, the system is evacuated to a vacuum (<1.0E5Pa) through the vacuum interface 5 to reduce heat leakage due to air conduction. The entire superconducting magnet device system also includes a current lead interface 3 for energizing the superconducting coil and a signal line interface 4 for signal acquisition and monitoring.

[0029] The superconducting magnet 10 also includes an external Dewar support rod protrusion structure 6, a helium return pipeline 7, a PCS superconducting switch 11, a liquid inlet pipe 12, a magnet liquid inlet 13, a magnet return gas inlet 14, and a connecting unit 15. The external Dewar support rod protrusion structure 6, the helium return pipeline 7, the PCS superconducting switch 11, the liquid inlet pipe 12, the magnet liquid inlet 13, the magnet return gas inlet 14, and the connecting unit 15 are used to support the operation of the superconducting magnet 10.

[0030] The overall structure of the built-in superconducting motor 16 is as follows: Figure 4-8 As shown, the overall structure of the superconducting motor, including its external auxiliary and support structures, is given in detail, such as... Figure 4As shown, the external Dewar 161 and external Dewar 101 of the built-in superconducting motor are connected by a flange to provide a vacuum environment, and are further connected by the built-in superconducting support structure 163 extending from the outside of the motor to provide structural strength support. Simultaneously, the cold shield 162 and cold shield 102 of the built-in superconducting motor are connected by a flange to reduce radiative heat leakage, and are connected to the built-in superconducting support structure 163 at the middle section to provide thermal insulation, reduce conductive heat leakage, and effectively cool the stator, reducing the resistance of the stator windings and improving motor operating efficiency. Figure 5 and Figure 6 The diagram showcases the overall internal structure of the superconducting motor. One end of the motor is connected and fixed to the secondary condenser 103 of the refrigerator 2 via a flange 164 connecting the built-in superconducting motor and the secondary cooling structure of the refrigerator 2. To reduce friction and wear, a bearing 169 is arranged between the superconducting motor rotor and the flange, thereby improving the motor's service life. It also includes a circulating gas inlet 165, a circulating exhaust port 166, a sliding bearing 167 for the built-in superconducting motor rotor, a rotating support ring 168 for the built-in superconducting motor rotor, and a connection interface 1610 between the built-in superconducting motor and an external liquid inlet.

[0031] in addition, Figure 7 and Figure 8 The detailed structure of the core components inside the built-in superconducting motor is shown. The superconducting motor stator 1611 is located outside the superconducting motor rotor 1612. The concentricity of the two needs to be adjusted by the relative cooperation between the flange 164 of the two-stage cooling structure of the refrigerator and the external Dewar 161 of the built-in superconducting motor to achieve the concentricity of the rotor and stator and ensure high-speed rotation stability. This application has designed a separate built-in superconducting motor external Dewar 161 for the superconducting circulating motor. The main purpose is to make it easier to achieve the concentric adjustment of the stator and rotor.

[0032] The detailed composition of the superconducting motor stator 1611 is as follows: Figure 8 As shown, the stator 1611 of the superconducting motor consists of an outer stator fixed cylinder 16113, an inner stator laminated iron core 16111, and stator winding coils 16112. To reduce the loss Q=I^2×R caused by Joule heat during operation, this application uses high-purity oxygen-free copper wire. Because of its residual resistivity (RRR) characteristic of hundreds or thousands (i.e., RRR=room temperature resistivity / low temperature resistivity), when the stator winding operates at low temperature, its Joule heat loss will be reduced by hundreds or thousands of times. Compared with conventional motors, this alone can improve the efficiency of this motor by about 20%. Furthermore, it should be noted that the reasonable structural design of this application means that the heat load of the stator only acts on the secondary condenser 103 of the refrigerator 2, and the impact on the secondary cooling capacity is very small and can be basically ignored. Additionally, Figure 8The number of slots in the stator is for illustrative purposes only and can be changed according to the specific application.

[0033] The detailed structure of the superconducting motor rotor 1612 is as follows: Figure 8 As shown, this application employs a unique design to reduce heat loss during rotor operation. Firstly, the rotor metal frame 16121 is recommended to be made of a material with poor conductivity, such as titanium alloy, whose resistivity of around 20K is more than 10,000 times that of highly conductive materials. This significantly reduces eddy current losses during operation (eddy current losses are inversely proportional to material resistivity). This provides structural support for the rotor superconducting ring 16122 (made of high-temperature superconducting material such as ReBCO or Bi-type) and the rotor permanent magnet component 16123. Simultaneously, the permanent magnet portion is located inside the superconducting ring assembly. Generally, to reduce excessive eddy current losses caused by cutting magnetic field lines during rotation, the permanent magnet component is cut into a segmented form. Through optimized design, the heat dissipation on the rotor in this patent can be less than one-thousandth of the total power consumption. For example, if the total power consumption of the motor is 200W, the heat load on the rotor is <0.2W.

[0034] It is important to note that the rotor metal frame 16121 is fixedly connected to the bearing 169. Simultaneously, the impeller structure inside the metal frame 16121 rotates under the drive of the shaft, providing power for the cryogenic helium gas circulation. To ensure the continuous and stable operation of the cooling circulation system, the entire cryogenic gas system must operate in an independent closed-loop system. This requires the introduction of a rotor sealing cylinder 16124 (it is recommended to use a material with poor electrical conductivity, such as titanium alloy, to reduce eddy current losses during operation). This cylinder is located outside the rotor and inside the stator, with a gap of 1-2 mm between the three, sealing and isolating them. It is then connected to the circulating exhaust port 166 and the circulating gas inlet 165, achieving closed-loop circulation of the entire cryogenic gas system.

[0035] In one possible embodiment, the reason for the reduced power loss is that the power of eddy current losses in a conventional conductor can be expressed by the following simplified formula: P_eddy∝(B²×f²×A²) / ρ.

[0036] in: P_eddy: Power of eddy current loss (unit: watts W); B: Magnetic flux density of alternating magnetic field (unit: Tesla T). f: Frequency of magnetic field change (unit: Hertz Hz); A: Cross-sectional area of ​​the material perpendicular to the magnetic field direction (unit: square meters m²). ρ: Resistivity of the material (unit: ohm-meter Ω·m); It can be clearly seen from the formula that the eddy current loss power P_eddy is inversely proportional to the resistivity ρ of conventional materials and directly proportional to the squares of B, f, and A.

[0037] Therefore, considering the cooling requirements of the entire magnetic levitation system's cooling range, a process for optimizing the heat load was proposed.

[0038] Cooling Phase: When the entire system is in a high vacuum environment, room temperature helium is injected through an external helium storage tank into the coil connected to the first-stage condenser 103 via exhaust port 106 for pre-cooling. When the entire magnet circuit is filled with helium and reaches the set pressure, the solenoid valve closes to temporarily stop helium injection (it should be noted that during the entire cooling process, the system will continuously replenish room temperature helium as the temperature decreases). At this time, the refrigerator 2 is turned on. When the temperature of the first stage of the refrigerator drops below 77K, the built-in superconducting motor 16 is turned on and runs at low speed (ensuring that the temperature of the superconducting motor's circulation exhaust port 166 and its operating temperature do not exceed the critical temperature of the high-temperature superconducting material), forcing the helium in the entire system to slowly circulate. See details of the circulation loop. Figure 3 As the helium gas undergoes pre-cooling in the first stage and further cooling in the second stage of the refrigerator 2, its temperature gradually decreases. Due to the low-speed circulation and the fact that the inlet temperature of the helium gas at the first-stage cold head of the refrigerator 2 is below the critical temperature for high-temperature superconductivity, the rotor superconducting ring 16122 enters the superconducting state (unrestricted current carrying). After a certain period of stable operation, the rotational speed (operating frequency) of the built-in superconducting motor 16 can be gradually increased. At this time, the forced convection velocity further increases, the heat transfer efficiency increases, and the system cooling rate further accelerates. Because the temperature decreases, both the superconducting performance and the permanent magnet performance are improved. The improvement in permanent magnet and superconducting performance (resulting in an increase in rotor magnetic flux density) allows for a reduction in the stator excitation current (i.e., the alternating field magnetic flux density B in the formula will decrease), thus reducing losses. The rotational speed will not be affected by the reduction in stator excitation current.

[0039] During the cooling process, as the temperature further decreases (with...) The step size. (For cryogenic cycling helium temperature reduction range), the superconducting performance will be further improved, allowing for a phased increase in motor speed (relative to the previous step). The To achieve the desired stator excitation current frequency, a larger magnetic field is generated in the high-temperature superconducting ring inductor within the rotor without inducing losses, such as... Figure 8 (Magnetic flux density at the indicated location), then reduce the speed, further reduce the stator operating current, and repeat this process. Eventually, as the temperature decreases (due to improved superconductivity), the stator excitation current will decrease, resulting in a smaller thermal load on the entire system and achieving efficient motor operation.

[0040] It is important to note that as the temperature of the entire magnet system approaches 20K or below, the heat capacity of the material decreases at low temperatures. This allows for a gradual reduction in the motor's operating speed, entering a low-speed operation phase. While the cooling rate remains relatively fast at this stage, the motor's heat loss is significantly reduced. This ensures that the superconducting magnet 10 can achieve extremely low-temperature cooling to 4.2K, even with limited cooling capacity available at low temperatures. Furthermore, this approach allows for the continued replenishment of helium after the magnet system has reached 4.2K cooling, enabling helium condensation and the production of liquid helium for the system.

[0041] Superconducting magnet 10 is powered on and operates as follows: When the superconducting magnet 10 is partially cooled below its critical temperature by the cooling cycle system and sufficient liquid helium is generated, the PCS superconducting switch 11 is first heated to change it from a superconducting state to a resistive state, thus removing the short circuit to the superconducting coil. Then, a superconducting power supply is used to energize the superconducting coil of the superconducting magnet 10 through the current lead interface 3. Once the current reaches the target value, heating of the PCS superconducting switch 11 is stopped, allowing it to re-enter the superconducting state and short-circuit the superconducting coil. At this point, the superconducting power supply current is reduced to 0A, enabling the superconducting magnet 10 to achieve closed-loop operation. The specific operating status of the magnet can be monitored and controlled in real time through relevant internal signal sensors via the monitoring signal interface 4. At this time, the device can provide a magnetic field with a polarity periodic change far exceeding that generated by conventional conductor coils. Utilizing the principle of electromagnetic levitation technology, in conjunction with ground propulsion, levitation, and guide coils, the superconducting magnet device and its mounted load can achieve ultra-high-speed operation.

[0042] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A cryogenic circulating cooling system for a magnetically levitated superconducting magnet, characterized in that, include: A superconducting magnet (10) is provided with a cooling device (1), and a refrigerator (2) is provided on the side of the cooling device (1). The cooling device (1) is equipped with a built-in superconducting motor (16). The built-in superconducting motor (16) carries the superconducting motor stator (1611) and the superconducting motor rotor (1612) through bearings (169). The superconducting motor stator (1611) and the superconducting motor rotor (1612) are concentrically connected through a secondary condenser (103) and an external Dewar (161) of the built-in superconducting motor. The superconducting motor rotor (1612) includes a rotor metal frame (16121), a rotor superconducting ring (16122), and a rotor permanent magnet component (16123). The rotor metal frame (16121) is disposed on the bearing (169). Multiple rotor permanent magnet components (16123) are disposed on the rotor metal frame (16121), and the rotor superconducting ring (16122) is disposed on the rotor metal frame (16121). The rotor metal frame (16121) is surrounded by a rotor sealing cylinder (16124), which is located between the superconducting motor rotor (1612) and the superconducting motor stator (1611). The rotor sealing cylinder (16124) seals and isolates the superconducting motor rotor (1612) and the superconducting motor stator (1611). The built-in superconducting motor (16) is provided with a circulating gas inlet (165) and a circulating exhaust port (166). The circulating exhaust port (166) is connected to a gas outlet (109) and a liquid inlet (105). The rotor sealing cylinder (16124) is connected to the circulating gas inlet (165) and the circulating exhaust port (166) respectively.

2. The cryogenic circulating cooling system for a magnetically levitated superconducting magnet according to claim 1, characterized in that, The superconducting motor stator (1611) includes a stator fixed outer cylinder (16113), a stator lamination core (16111), and a stator winding coil (16112). Multiple stator lamination cores (16111) are provided, and multiple stator lamination cores (16111) are arranged in a ring around the bearing (169). The stator winding coil (16112) is wound on each stator lamination core (16111). The stator fixed outer cylinder (16113) is sleeved around the multiple stator lamination cores (16111).

3. The cryogenic circulating cooling system for a magnetically levitated superconducting magnet according to claim 1, characterized in that, The circulating gas inlet (165) is connected to the spiral condenser tube on the secondary condenser (103). The built-in superconducting motor (16) is connected to the secondary condenser (103) through the secondary cooling structure connecting flange (164). The spiral condenser tube on the secondary condenser (103) is connected to the spiral condenser tube on the primary condenser (104) through the condenser connecting pipe (108). The primary condenser (104) is connected to the primary cooling head (201) flange of the refrigerator (2). The secondary condenser (103) is connected to the secondary cooling head (202) flange of the refrigerator (2). The spiral condenser tube inlet on the primary condenser (104) is connected to the magnet exhaust port transition corrugated pipe (110). The spiral condenser tube on the primary condenser (104) is also connected to the exhaust port (106).

4. The cryogenic circulating cooling system for a magnetically levitated superconducting magnet according to claim 3, characterized in that, The cooling device (1) is provided with an external Dewar (161) for a superconducting motor. An external Dewar (161) for a superconducting motor and a cold screen (162) for a superconducting motor are provided between the external Dewar (161) and the superconducting motor (16). The external Dewar (161) for a superconducting motor is flange-connected to an external Dewar (101). The cold screen (162) for a superconducting motor is flange-connected to a cold screen (102). An external Dewar connecting transition bellows (111) is provided on the external Dewar (161). The external Dewar connecting transition bellows (111) connects the external Dewar (161) for a superconducting motor and the vacuum external Dewar (9) for the superconducting magnet (10). The gas outlet (109) and the magnet exhaust port transition bellows (110) are respectively connected to the magnet liquid inlet (13) and the magnet gas return port (14) inside the external Dewar connecting transition bellows (111).

5. The cryogenic circulating cooling system for a magnetically levitated superconducting magnet according to claim 4, characterized in that, The superconducting magnet (10) has a superconducting magnet cold screen (8) outside its helium tank. The superconducting magnet cold screen (8) is wrapped by the vacuum external Dewar (9). The vacuum external Dewar (9) has a vacuum interface (5). The side of the vacuum interface (5) on the vacuum external Dewar (9) also has a current lead interface (3) and a signal line interface (4).

6. The cryogenic circulating cooling system for a magnetically levitated superconducting magnet according to claim 4, characterized in that, The built-in superconducting motor (16) is supported on the external Dewar (161) of the built-in superconducting motor by a built-in superconducting support structure (163).

7. The cryogenic circulating cooling system for a magnetically levitated superconducting magnet according to claim 6, characterized in that, The middle part of the built-in superconducting support structure (163) is functionally connected to the heat sink of the built-in superconducting motor cold screen (162).

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