A closed superconducting coil magnetic levitation bearing and its construction method

Abstract

This application belongs to the field of superconducting electric technology, specifically disclosing a closed superconducting coil magnetic levitation bearing and its construction method. The bearing includes: a closed superconducting coil stator, a flux source rotor, and a shaft; the flux source rotor is used to provide a background magnetic field; the closed superconducting coil stator is used to link and lock the background magnetic field provided by the flux source rotor in a superconducting state; when the flux source rotor moves under the action of a load, the closed superconducting coil stator is used to induce a shielding current inside; or the closed superconducting coil stator changes its internal total magnetic flux by acquiring a transmission current; wherein, when the shielding current and / or the transmission current interact with the background magnetic field, the flux source rotor is subjected to a levitation force opposite to the load direction; when the levitation force on the flux source rotor is greater than or equal to the load, the flux source rotor establishes a levitation state; the magnetic levitation bearing provided by this application can ensure long-term stable operation.

Description

Technical Field

[0001] This application belongs to the field of superconducting electric technology, and more specifically, relates to a closed superconducting coil magnetic levitation bearing and its construction method. Background Technology

[0002] Magnetic levitation bearings utilize electromagnetic force to eliminate the mutual contact between the stator and rotor, thereby significantly reducing frictional losses and making them an ideal choice for high-speed rotating machinery. With the rapid development of Type II superconducting materials, superconducting magnetic levitation bearings, based on their flux pinning properties, can achieve three-dimensional self-stabilized levitation without external interference and possess high levitation stiffness, showing broad development potential in flywheel energy storage, ultra-high-speed motors, and ship engines. Superconducting magnetic levitation bearing systems typically employ a superconducting-permanent magnet structure, where the permanent magnet acts as the flux source, and the Type II superconductor locks the flux linked to it after field cooling. When the superconductor and permanent magnet are relatively offset in any direction, a high-density shielding current is induced within the superconductor due to the flux pinning effect. This current interacts with the permanent magnet's magnetic field, generating a restoring force opposite to the direction of motion, thus achieving passive self-stabilized levitation. Currently, the materials used in superconducting magnetic levitation bearings are mainly bulk materials and stacked strips, which have the following limitations:

[0003] (1) Attenuation of levitation force: On the one hand, there is magnetic flux creep inside the high-temperature superconducting material, and the magnetic field lines will gradually detach from the pinning center over time; on the other hand, there is a certain circumferential non-uniformity in the magnetic field of the permanent magnet, and AC losses will occur inside the superconductor when the stator and rotor rotate relative to each other. Both of these factors will lead to attenuation of the bearing levitation force, thereby affecting the long-term stable operation of the system.

[0004] (2) Difficulty in establishing initial levitation: Pinned levitation relies on the mutual offset between the stator and rotor after field cooling to establish levitation. For heavy-duty equipment, a complex movable support structure is required to ensure the establishment of initial levitation. In order to reduce the initial offset and improve the compactness of the bearing structure and the utilization rate of the permanent magnet's magnetic field, the system needs to have greater stiffness, which will significantly increase the cost of using the superconductor.

[0005] (3) The suspension state is not adjustable: Once the initial suspension is established, its suspension position, stiffness, suspension force and other parameters are determined and difficult to change, which cannot meet the adjustment requirements, and the tolerance of the suspension position is low.

[0006] In summary, existing superconducting pinned magnetic levitation bearings mainly face the following problems: 1. They cannot meet the requirements for high-speed, long-term stable operation; 2. The load-bearing capacity is proportional to the stiffness, making it difficult to establish initial suspension under heavy loads, which significantly increases the cost of using superconducting bearings; 3. The suspension is not adjustable, resulting in low fault tolerance. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this application is to provide a closed superconducting coil magnetic levitation bearing and its construction method, which aims to solve the problems that existing superconducting magnetic levitation bearings cannot work stably for a long time, cannot be excited to lift, and have an unadjustable levitation state.

[0008] To achieve the above objectives, in a first aspect, this application provides a closed superconducting coil magnetic levitation bearing with three-dimensional self-stabilizing characteristics, comprising: a closed superconducting coil stator, a flux source rotor, and a rotating shaft arranged sequentially from the outside to the inside;

[0009] The flux source rotor is used to provide a background magnetic field;

[0010] The closed superconducting coil stator is used to link and lock the background magnetic field provided by the flux source rotor in the superconducting state;

[0011] When the flux source rotor moves under load, the closed superconducting coil stator induces a shielding current inside to resist changes in the linkage flux; the closed superconducting coil stator changes its total internal flux by acquiring the transmission current.

[0012] When the shielding current and / or transmission current interact with the background magnetic field, the flux source rotor is subjected to a levitation force opposite to the load direction. When the magnitude of the levitation force on the flux source rotor is equal to the load, the flux source rotor establishes a levitation state.

[0013] The three-dimensional self-stabilizing characteristic is the ability of the flux source rotor to automatically return to the suspended position after axial or radial displacement, once the flux source rotor is in a suspended state.

[0014] More preferably, the closed superconducting coil stator is wound with superconducting wire, which includes, but is not limited to, cryogenic superconducting wire or high-temperature superconducting wire; cryogenic superconducting wire includes, but is not limited to, NbTi or High-temperature superconducting wires include, but are not limited to, ReBCO, Bi-2223, and Bi-2212. Or iron-based superconductors.

[0015] More preferably, the flux source rotor is a permanent magnet, a conventionally conducting magnet, or a superconducting magnet; wherein, the superconducting magnet includes, but is not limited to, superconducting bulk material, stacked strip material, or superconducting coil.

[0016] More preferably, the working mode of the closed superconducting coil magnetic levitation bearing is pinning levitation without magnetic flux control, magnetic levitation with magnetic flux control by PCS + power supply, or magnetic levitation with magnetic flux control by wireless excitation system.

[0017] More preferably, the wireless excitation system is a transformer-rectifier flux pump, a linear traveling wave flux pump, or a rotary traveling wave flux pump.

[0018] More preferably, when the wireless excitation system is a transformer-rectifier flux pump, the transformer-rectifier flux pump includes: an alternating power supply, a transformer core, a primary winding, a secondary winding, and a superconducting switch; the superconducting switch is connected to the output terminal of the secondary winding and also serves as part of the closed loop of the closed superconducting coil stator;

[0019] The alternating power supply is used to provide an asymmetrical triangular wave to the primary winding, and the secondary winding is used to induce an asymmetrical triangular wave current with an amplitude of n times.

[0020] Specifically, when the instantaneous current in the secondary winding is less than the critical current of the superconducting switch, the superconducting switch remains closed, and the stator of the closed superconducting coil is short-circuited; when the instantaneous current in the secondary winding is greater than the critical current of the superconducting switch, the superconducting switch opens, and part of the current in the secondary winding flows to the stator of the closed superconducting coil, which is the pumped transmission current into the stator of the closed superconducting coil; by adjusting the amplitude of the positive half-wave or the amplitude of the negative half-wave of the secondary winding to be greater than the critical current of the superconducting switch, the direction of the transmission current pumped into the stator of the closed coil and the direction of the magnetic flux movement on the superconducting switch are changed, thereby realizing the magnetization or demagnetization of the stator of the closed superconducting coil;

[0021] When the wireless excitation system is a rotating traveling wave magnetic flux pump, the closed superconducting coil magnetic levitation bearing includes: a closed superconducting coil stator, a magnetic flux source rotor, a rotating shaft, a superconducting switch, and a rotating motor rotor with embedded permanent magnets; wherein, the superconducting switch is part of the closed coil stator, so that the stator forms a superconducting closed circuit;

[0022] A superconducting switch is used to regulate the magnetic flux of the coil; a rotating motor rotor with embedded permanent magnets is used to generate a rotating magnetic field. The rotating magnetic field cuts the superconducting switch, generating a DC voltage at its two ends, thereby realizing the pumping of transmission current into the superconducting double-pane coil for magnetic flux regulation; by changing the rotation direction of the rotating motor rotor, the direction of the transmission current pumped into the stator is changed.

[0023] When the wireless excitation system is a linear traveling wave flux pump, the closed superconducting coil magnetic levitation bearing includes: a closed superconducting coil stator, a flux source rotor, a shaft, a superconducting switch, and a linear traveling wave winding; wherein, the superconducting switch is part of the closed coil stator, so that the stator forms a superconducting closed loop;

[0024] The superconducting switch is used to control the magnetic flux of the coil; the linear traveling wave winding is used to generate a planar traveling wave magnetic field in the air gap when the phase sequence current is applied; the traveling wave magnetic field acts on the superconducting switch, generating a rectified voltage at its two ends, thereby realizing the pumping of transmission current into the superconducting double pancake coil for magnetic flux control; by changing the direction of the current in the traveling wave winding, the direction of the transmission current pumped into the stator is changed.

[0025] More preferably, when using a PCS+ power supply for magnetic flux control in magnetic levitation operation, it includes: a closed superconducting coil stator, a rotating shaft, a magnetic flux source rotor, a superconducting constant current switch, current leads, and an external power supply;

[0026] The flux source rotor is located inside the closed superconducting coil stator; the superconducting constant current switch is connected to the closed superconducting coil stator; the external power supply is connected to the superconducting constant current switch through current leads;

[0027] When the magnetic flux of the closed superconducting coil is controlled, the superconducting constant current switch is turned off, and the stator of the closed superconducting coil is directly connected in parallel to the two ends of the external power supply; the external power supply is used to magnetize or demagnetize the stator of the closed superconducting coil.

[0028] Secondly, this application provides a method for constructing the levitation state of a closed superconducting coil magnetic levitation bearing, specifically including the following steps:

[0029] Step 1: The flux source rotor remains stationary under the initial support device. The closed superconducting coil stator is cooled to the superconducting state. The closed superconducting coil stator is used to lock the background magnetic field provided by the flux source rotor at the current position.

[0030] Step 2: Remove the initial support device to allow the flux source rotor to move under the load, and induce a shielding current in the closed superconducting coil stator;

[0031] Alternatively, the initial support device can be retained, and transmission current can be pumped into the closed superconducting coil stator;

[0032] Step 3: The shielding current or transmission current interacts with the background magnetic field, causing the flux source rotor to be subjected to a levitation force opposite to the load direction, until the magnitude of the levitation force on the flux source rotor is equal to the load, and the flux source rotor establishes a levitation state.

[0033] More preferably, if a wireless excitation system is provided in the closed superconducting coil magnetic levitation bearing, step two specifically involves:

[0034] The flux source rotor is initially stationary under support. A wireless excitation system pumps transmission current into the closed superconducting coil stator. The transmission current interacts with the background magnetic field, causing the closed superconducting coil stator to be subjected to a Lorentz force in the same direction as the load, while the flux source rotor is subjected to a levitation force in the opposite direction to the load. When the levitation force increases to be equal to the load, the flux source rotor establishes a levitation state.

[0035] More preferably, the method for obtaining the suspension state further includes adjusting the magnitude of the suspension force and the suspension position, specifically implemented as follows:

[0036] Step 4: After the flux source rotor establishes a levitation state, a wireless excitation system is used to pump a transmission current in the same direction as the initial current into the stator of the closed superconducting coil. The total current inside the closed superconducting coil increases, and the levitation force on the flux source rotor is greater than the load. The flux source rotor moves in the direction of the levitation force.

[0037] Step 5: As the magnetic flux source rotor moves in the direction of the levitation force, a shielding current opposite to the pumped transmission current is induced inside the coil. When the shielding current increases to offset the transmission current pumped in step 4, the magnetic flux source rotor re-establishes a levitation state at the new position.

[0038] or

[0039] Step 4: After the flux source rotor establishes a levitation state, a wireless excitation system is used to pump a transmission current in the opposite direction to the initial current into the stator of the closed superconducting coil. The total current inside the closed superconducting coil decreases, the levitation force on the flux source rotor is less than the load, and the flux source rotor moves in the direction of the load.

[0040] Step 5: As the magnetic flux source rotor moves toward the load direction, a shielding current is induced inside the coil, which is opposite to the pumped transmission current. When the shielding current increases to offset the transmission current pumped in step 4, the magnetic flux source rotor re-establishes a levitation state at the new position.

[0041] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:

[0042] This application provides a magnetic levitation bearing that employs either a closed superconducting coil stator induced shielding current or a pumped transmission current. On one hand, because the superconducting coil stator is in a closed state, and the superconducting tape is simple to wind and has extremely high current density, the bearing can achieve high force density and features a compact structure and ease of axial and radial expansion. On the other hand, it supports passive induced shielding current or active pumped transmission current in the closed superconducting coil stator. The bearing can operate in various modes, including pinned levitation without flux control, magnetic levitation with flux control via PCS + power supply, or magnetic levitation with flux control via wireless excitation system. Compared to current superconducting magnetic levitation bearings that use bulk materials and stacked tapes, the magnetic levitation bearing provided in this application avoids levitation force attenuation caused by flux creep, joint resistance, and AC losses, ensuring long-term stable operation.

[0043] This application provides a magnetic levitation bearing. After the flux source rotor establishes a levitation state, the total current inside the closed superconducting coil stator can be changed by adjusting the transmission current pumped into the stator. When the pumped transmission current is in the same direction as the current establishing the levitation state, the levitation force on the flux source rotor is greater than the load, causing the rotor to move in the direction of the levitation force and eventually re-establish a levitation state at a higher position. When the pumped transmission current is in the opposite direction to the current establishing the levitation state, the levitation force on the flux source rotor is less than the load, causing the rotor to move in the direction of the load and eventually re-establish a levitation state at a lower position. Therefore, the magnetic levitation bearing provided in this application can not only establish a levitation state but also adjust the magnitude of the levitation force and the levitation position.

[0044] This application provides a magnetic levitation bearing. When a wireless excitation system is used to pump transmission current into the stator of a closed superconducting coil, compared with pinned levitation without magnetic flux control, excitation levitation eliminates the initial displacement of levitation, eliminates the need for complex movable mechanical supports, and can achieve stable levitation in the static state of the magnetic flux source rotor. At the same time, the transmission current is only limited by the critical current of the closed superconducting coil stator, which can greatly improve the load capacity of the bearing and overcome the problem that the magnitude of the induced shielding current is limited by the gradient of magnetic field change, making it difficult to achieve levitation under high load. Attached Figure Description

[0045] Figure 1(a) is a structural diagram of the magnetic levitation bearing provided in an embodiment of this application;

[0046] Figure 1(b) is a cross-sectional view of the magnetic levitation bearing provided in an embodiment of this application;

[0047] Figure 2 This is a schematic diagram of a superconducting closed-loop magnetic levitation bearing, provided in an embodiment of this application, which achieves levitation by relying on shielding current.

[0048] Figure 3 This is a schematic diagram of the induced axial stabilizing force generated when the magnetic levitation bearing system provided in this application experiences axial displacement;

[0049] Figure 4(a) is a schematic diagram of the initial levitation position of the rotor provided in an embodiment of this application;

[0050] Figure 4(b) is a schematic diagram of the induced radial stabilizing force generated when the rotor undergoes radial displacement according to an embodiment of this application;

[0051] Figure 5 This is a typical transformer-self-rectifier type wireless excitation system structure and equivalent circuit diagram provided in the embodiments of this application;

[0052] Figure 6(a) is a schematic diagram of the electromagnetic force distribution of the rotor at the initial position of the rotor using a wireless excitation system to pump in the transmission current to achieve excitation buoyancy, according to an embodiment of this application.

[0053] Figure 6(b) is a schematic diagram of the electromagnetic force distribution of the rotor suspension position when the rotor is excited and lifted by pumping in the transmission current through a wireless excitation system according to an embodiment of this application.

[0054] Figure 7(a) is a schematic diagram of the electromagnetic-force distribution of the initial levitation position using a wireless excitation system for magnetic flux control, provided in an embodiment of this application.

[0055] Figure 7(b) is a schematic diagram of the electromagnetic force distribution for achieving levitation position rise by using a wireless excitation system to control magnetic flux according to an embodiment of this application;

[0056] Figure 7(c) is a schematic diagram of the electromagnetic force distribution for achieving levitation position descent using magnetic flux control via a wireless excitation system, provided in an embodiment of this application.

[0057] Figure 8(a) is an overall structural diagram of a high-load closed superconducting coil magnetic levitation bearing controlled by a transformer-rectifier wireless excitation system provided in an embodiment of this application;

[0058] Figure 8(b) is a cross-sectional view of the bearing shown in Figure 8(a) provided in an embodiment of this application;

[0059] Figure 9 This is a schematic diagram of a closed superconducting coil magnetic levitation bearing using a rotating traveling wave wireless excitation system provided in an embodiment of this application;

[0060] Figure 10 This is a schematic diagram of a closed superconducting coil magnetic levitation bearing using a linear traveling wave wireless excitation system provided in an embodiment of this application;

[0061] Figure 11 This is a schematic diagram of a closed superconducting coil magnetic levitation bearing using a PCS+ power supply excitation system provided in an embodiment of this application;

[0062] Figure 12 This is a schematic diagram of a flywheel energy storage system based on a wirelessly excited closed superconducting coil magnetic levitation bearing, provided in an embodiment of this application. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0064] In this article, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0065] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects.

[0066] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0067] The embodiments of this application are described below with reference to the accompanying drawings.

[0068] As shown in Figures 1(a) and 1(b), this application provides a magnetic levitation bearing, including a closed superconducting coil stator 11, a flux source rotor 12, and a shaft 13. The closed superconducting coil stator is wound with superconducting wire, including but not limited to low-temperature superconducting wire (such as NbTi, ...). ) and high-temperature superconducting wires (ReBCO, Bi-2223, Bi-2212, (Iron-based superconductor), the closure method can be jointless closure or superconducting joint closure; the flux source rotor 12 can be a permanent magnet, a conventional magnet, or a superconducting magnet, including but not limited to superconducting bulk materials, stacked strips, and superconducting coils; the bearing can operate in a flux-free pinned suspension, a PCS+power supply-controlled magnetic levitation, or a magnetic levitation controlled by a wireless excitation system; the wireless excitation system includes but is not limited to various transformer-rectifier flux pumps, linear traveling wave flux pumps, and rotary traveling wave flux pumps; the rotating shaft 13 realizes torque transmission between the rotor and the rotating system;

[0069] Without magnetic flux modulation, this application achieves levitation and maintains self-stability by relying on shielding current; such as Figure 2 As shown, Figure 2The left side represents the rotor remaining stationary under initial support before levitation is established. The support system and the supporting force balancing gravity are not shown here for better contrast. Cooling the superconducting coil stator to a superconducting state locks the background magnetic field passing through the flux source rotor at that position. After removing the support device, the flux source rotor moves downwards under load (gravity or thrust). To maintain the constant linkage magnetic field, a shielding current in the corresponding direction is induced inside the coil. This current interacts with the magnetic field, causing the coil to experience a downward force, while the rotor experiences an upward levitation force. After descending a certain distance... dz Then, the levitation force increases to equal the gravity, and the rotor establishes a levitation state;

[0070] Figure 3 The left side shows the initial rotor levitation position, at which point the permanent magnet rotor experiences the axial levitation force. F z With axial load F Balance; such as Figure 3 As shown on the right, when the rotor undergoes axial displacement dz Subsequently, the upward-polarity magnetic flux linked with the closed coil stator decreases, causing a shielding current to be induced in the coil cross-section in the same direction as the original current, thus maintaining the linkage magnetic flux unchanged; the combined effect of the original current and the shielding current causes a levitation force on the rotor. F z Greater than its load F Under the combined force, the rotor will move upward until it returns to its initial equilibrium position.

[0071] Figure 4(a) shows the initial rotor suspension position, and Figure 4(b) shows the suspension position after the rotor has shifted radially to the right. Since the axial magnetic fields acting on the upper and lower sections of the coil cross-section are opposite in direction, the coil cross-section is divided into sections for discussion. As shown in Figure 4(a), in the initial position, the cross-sectional current is symmetrical vertically and interacts with the magnetic field to produce radial forces of the same magnitude but opposite in direction. F r1 and F r2 Under the action of the resultant force, the rotor will move to the left until it returns to the initial equilibrium position;

[0072] The above analysis shows that the bearing structure can achieve levitation and maintain three-dimensional self-stability without the presence of an excitation system. Due to the simple winding of superconducting tape and its extremely high current density, the bearing can achieve a high force density and features a compact structure that is easy to extend in the axial and radial directions. However, under the condition of no magnetic flux modulation, the bearing still cannot avoid the attenuation of levitation force due to magnetic flux creep, joint resistance, and AC loss, and cannot achieve long-term stable operation. Using a PCS+ power system or a wireless excitation system to modulate the magnetic flux of the closed superconducting coil can avoid this problem, and also has the functions of adjustable levitation and excitation-induced buoyancy. Figure 5 The first typical transformer-self-rectifier type wireless excitation system structure and equivalent circuit diagram 55; the transformer-self-rectifier type wireless excitation system includes a transformer core 51, a primary winding 52, a secondary winding 53, and a superconducting switch 54; the primary winding 52 can be made of a normal conducting material or a superconducting material; the secondary winding 53 is wound with a superconducting material; in the equivalent circuit diagram 55 of the wireless excitation system, an asymmetrical triangular wave is provided to the primary winding 52 by an alternating power supply. A current with an amplitude of n times is induced in the secondary winding 53. ;when When the instantaneous value is less than the critical current of the superconducting switch, the superconducting switch remains closed, closing the stator short circuit of the superconducting coil; when When the amplitude of the positive half-wave is greater than the critical current of the superconducting switch, resistance will appear on the superconducting switch 54, and part of the secondary current will flow to the closed coil load, thereby achieving load excitation; from a magnetic perspective, when the current flowing through the superconducting switch... When the current exceeds the critical current, the magnetic flux pinning force on the magnetic induction lines will be less than the Lorentz force, causing the magnetic flux to move and the magnetic induction lines to link with the closed superconducting coil loop across the superconducting bridge; conversely, if... When the instantaneous value of the negative half-wave is greater than the critical current of the superconducting switch, the magnetic flux linked with the closed superconducting coil circuit moves outward across the superconducting bridge, and the coil current decreases.

[0073] Figures 6(a) and 6(b) show schematic diagrams of the excitation and levitation of the flux source rotor using a wireless excitation system. To distinguish the shielding current, double lines are used to represent the transmission current. The coil is cooled to a superconducting state at the position shown in Figure 6(a), and the coil locks into the background magnetic field provided by the flux source rotor at this position. The wireless excitation system pumps the transmission current into the coil. The transmission current interacts with the background magnetic field, causing the coil to experience a downward Lorentz force. At the same time, the permanent magnet rotor will be subjected to an upward levitation force. As shown in Figure 6(b), when Increase the load on the permanent magnet rotor. F At the same time, the support device no longer provides support, and the bearing reaches the levitation condition; at this point, power supply to the wireless excitation system is stopped, the superconducting switch returns to the superconducting state, and together with the coil, forms a superconducting closed loop. The levitation state is essentially the same as... Figure 2 The right side is consistent and also has the same characteristics. Figure 3 The three-dimensional passive self-stabilizing characteristics shown in Figures 4(a) and 4(b) are compared to... Figure 2 The buoyancy method shown eliminates the initial displacement of suspension through magnetic buoyancy. dzIt does not require complex movable mechanical support and can achieve stable buoyancy in a precise position; in addition, the magnitude of the inductive shielding current is limited by the gradient of magnetic field change, making it difficult to achieve buoyancy under high load; while theoretically, the magnitude of the transmitted current is only limited by the critical current of the coil, which can greatly improve the load capacity of the bearing.

[0074] The levitation position can also be changed using the magnetic flux control function, as shown in Figures 7(a) to 7(c). Figure 7(a) represents the initial levitation equilibrium state, at which point the rotor's axial levitation force is... With load F The system is in equilibrium, and the suspension height remains constant. Figure 7(b) shows the use of a wireless excitation system to pump a transmission current in phase with the initial current into the stator of the closed coil, increasing the total coil current and causing... > F The rotor moves upward; during this upward movement, a shielding effect occurs, and the reverse shielding current gradually increases until it cancels out the pumped transmission current, ultimately allowing the rotor to establish a new equilibrium at a higher suspension position; Figure 7(c) shows the use of a wireless excitation system to pump a transmission current into the closed-loop stator in the opposite direction to the initial current, reducing the total coil current, thus... < F The rotor moves downwards; during this downward movement, the shielding current gradually increases until it cancels out the pumped transmission current, and the rotor establishes a new equilibrium at a lower suspension position. It is worth noting that during flux control, the superconducting switch is not completely open; the suspension remains passively self-stabilized. Therefore, this application can achieve convenient and flexible adjustment of the suspension height without disrupting the passively self-stabilized suspension.

[0075] Example

[0076] Figures 8(a) and 8(b) illustrate an embodiment of this application, showing a high-load superconducting closed-loop magnetic levitation bearing controlled by a transformer-rectifier wireless excitation system. Figure 8(a) shows the overall structure of the bearing, and Figure 8(b) shows a cross-sectional view of the bearing. The bearing includes a coil frame 81, two interconnected high-temperature superconducting double-pancake coils 82, a permanent magnet rotor 83, an auxiliary bearing stator 84, a superconducting connector 85 for the series coils, a lead-out terminal 86 for the closed coil, a transformer-rectifier wireless excitation system 87, and a cryogenic Dewar 88. The permanent magnet rotor 83 is composed of six neodymium iron boron permanent magnet rings fixed on an aluminum alloy liner. Each ring consists of 18 tile-shaped magnets, with the same polarization direction for the same ring. The magnetic poles of the six rings are arranged axially in a Halebeck array structure, concentrating the magnetic field on the outer surface of the rotor to increase the intensity and gradient of the background magnetic field around the coil. The radial poles of the magnetic array are aligned with the cross-sections of the two closed coils, respectively. The axial levitation force density and radial levitation stiffness are improved. The auxiliary bearing stator 84 is wound with an open-loop superconducting coil and does not form a closed loop. Therefore, it cannot induce the net shielding current flowing in the circumferential direction, thus having little impact on the control of the axial levitation force. Since the radial stabilizing force is generated by the shielding current on the strip width surface, it does not need to form a closed loop. Therefore, this auxiliary bearing aims to improve the radial stability of the system. The stator coil and the secondary side of the wireless excitation system are cooled by immersion in liquid nitrogen. The structures shown in Figures 8(a) and 8(b) adopt a symmetrical configuration, which is an axial extension compared to Figures 1(a) and 1(b), increasing the load capacity of the system while enhancing the axial torsional resistance. When the working direction is axial, the excitation levitation method can be used, and the current interacts with the radial magnetic field of the permanent magnet to generate axial levitation force. By increasing the magnitude of the transmission current and the number of turns of the coil, the system can easily achieve a load capacity of tons.

[0077] Figure 9 In another embodiment of this application, a superconducting closed-loop magnetic levitation bearing with wireless excitation control for a rotating traveling wave flux pump is provided. It includes a superconducting double-pancake coil 91, a flux source rotor 92, a superconducting closed connector 93 for the coil, and a rotating motor rotor 94 embedded with permanent magnets. The superconducting closed connector of the coil also serves as the excitation switch for the flux pump. When the stator coil requires excitation, the permanent magnets generate a rotating magnetic field driven by the motor, which cuts the superconducting switch strip. Under an alternating magnetic field, magnetic flux movement occurs on both sides of the thickness surface of the superconducting switch strip. The direction of this magnetic flux movement is related to the direction of the rotating magnetic field, thereby increasing or decreasing the flux linkage in the closed-loop circuit. In terms of circuitry, a DC electromotive force is generated on the switch strip, which in turn generates a DC current in the closed-loop circuit. The advantages of this system are that it uses mechanical rotation to generate a traveling wave magnetic field, the wireless excitation system can be placed in the ambient temperature range, and the bearing structure can be more compact.

[0078] Figure 10 In another embodiment of this application, a closed superconducting coil magnetic levitation bearing system for wireless excitation control of a linear traveling wave flux pump is provided, comprising: a superconducting double-pancake coil 101, a flux source rotor 102, a superconducting closed connector 103 for the coil, and a linear traveling wave winding 104; wherein, the superconducting closed connector of the coil is also the excitation switch of the flux pump; the principle of the linear traveling wave winding is similar to that of a three-phase motor generating a rotating magnetic field; when a current with a certain phase sequence is passed through the linear traveling wave winding 104, a planar traveling wave magnetic field is generated in the air gap, which acts on the excitation switch of the flux pump and generates a rectified voltage at both ends, thereby achieving excitation of the superconducting coil stator; the advantage of this system is that it uses electricity to generate the traveling wave magnetic field, making the excitation system more compact;

[0079] Figure 11 In another embodiment of this application, the structure is a closed superconducting coil magnetic levitation bearing with excitation control using PCS + power supply, including: a closed superconducting coil 111, a flux source rotor 112, a superconducting constant current switch 113, current leads 114, and an external power supply 115; the switching control method of the superconducting constant current switch 113 includes, but is not limited to, magnetic control, thermal control, or current control; when the superconducting coil is energized, the superconducting switch is turned off by the control device, and the superconducting coil is directly connected in parallel across the power supply; at this time, the stator coil is directly charged by the power supply to achieve rotor levitation; when the rotor reaches the target levitation position, the control system is turned off, the switch returns to the superconducting state, the superconducting coil operates in closed loop, and the levitation state is maintained;

[0080] Figure 12In another embodiment of this application, the structure is a high-temperature superconducting flywheel energy storage system, including a high-speed electric motor / generator 121, a magnetic coupling 122, a vacuum chamber 123, a cryogenic liquid inlet channel 124, a cryogenic liquid outlet channel 125, a closed superconducting coil magnetic levitation bearing 126 with wireless excitation control, and a cryogenic chamber 127. The working principle of the system is as follows: In the energy storage stage, the high-speed electric motor / generator 121 operates as an electric motor, accelerating the flywheel to its rated speed through the magnetic coupling, and then the magnetic coupling is turned off through a magnetic switch device, and the flywheel rotates under the support of the superconducting magnetic levitation bearing. Since the entire rotating system is placed in the vacuum chamber and the magnetic levitation bearing eliminates mechanical friction, energy is stored in the flywheel in the form of rotational kinetic energy for a long time. In the energy release stage, the magnetic coupling is turned on; the high-speed electric motor / generator 121 operates as a generator, and the flywheel drives the generator rotor to rotate through inertia, and the stored mechanical energy is gradually released in the form of electrical energy. The advantages of this flywheel energy storage system are: 1. It eliminates the need for complex buoyancy mechanisms. By energizing the high-temperature superconducting closed coil through a wireless excitation system, the flywheel can achieve stable buoyancy from its initial support position; 2. It features a compact structure. To achieve high energy storage density, the flywheel's mass can reach hundreds of tons. Superconducting pinned suspension bearings based on induced current require a large amount of superconducting material to achieve high load-bearing capacity, resulting in a bulky bearing. This application overcomes the limitation of induced current magnitude by wirelessly exciting the closed coil, thereby increasing the levitation force density and reducing stator superconductivity under the same load. The increased use of permanent magnets in the conductor and rotor makes the structure more compact; 3. Long-term stable operation; Traditional superconducting pinned suspension bearings inevitably face the problem of levitation force decay, and the flywheel cannot be suspended for a long time, and the stored energy needs to be released in time; This application can compensate for the levitation force through a wireless excitation system, maintain the levitation height of the flywheel, and achieve long-term energy storage; 4. Adjustable levitation position; The flywheel system structure is usually relatively compact and the working area is limited; This application can adjust the levitation height through wireless excitation, which can not only improve the fault tolerance of the take-off position, but also achieve a smooth landing without shutting down the cooling system.

[0081] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0082] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0083] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0084] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0085] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A closed superconducting coil magnetic levitation bearing, characterized in that, It possesses three-dimensional self-stabilizing characteristics, including: a closed superconducting coil stator, a flux source rotor, and a rotating shaft arranged sequentially from the outside to the inside; The flux source rotor is used to provide a background magnetic field; The closed superconducting coil stator is used to link and lock the background magnetic field provided by the flux source rotor in the superconducting state; When the flux source rotor moves under load, the closed superconducting coil stator induces a shielding current inside to resist changes in the linkage flux; the closed superconducting coil stator changes its total internal flux by acquiring the transmission current. When the shielding current and / or transmission current interact with the background magnetic field, the flux source rotor is subjected to a levitation force opposite to the load direction. When the magnitude of the levitation force on the flux source rotor is equal to the load, the flux source rotor establishes a levitation state. The three-dimensional self-stabilizing characteristic is the ability of the flux source rotor to automatically return to the suspended position after axial or radial displacement when it is in a suspended state. The working modes of closed superconducting coil magnetic levitation bearing suspension are pinning suspension without magnetic flux control, magnetic levitation with magnetic flux control by PCS + power supply, or magnetic levitation with magnetic flux control by wireless excitation system. Wireless excitation systems are various types of transformer-rectifier flux pumps, linear traveling wave flux pumps, or rotary traveling wave flux pumps; When the wireless excitation system is a transformer-rectifier flux pump, the transformer-rectifier flux pump includes: an alternating power supply, a transformer core, a primary winding, a secondary winding, and a superconducting switch; The superconducting switch is connected to the output terminal of the secondary winding and also serves as part of the closed loop of the closed superconducting coil stator. The alternating power supply is used to provide an asymmetrical triangular wave to the primary winding, and the secondary winding is used to induce an asymmetrical triangular wave current with an amplitude of n times. Specifically, when the instantaneous current in the secondary winding is less than the critical current of the superconducting switch, the superconducting switch remains closed, and the stator of the closed superconducting coil is short-circuited; when the instantaneous current in the secondary winding is greater than the critical current of the superconducting switch, the superconducting switch opens, and part of the current in the secondary winding flows to the stator of the closed superconducting coil, which is the pumped transmission current into the stator of the closed superconducting coil; by adjusting the amplitude of the positive half-wave or the amplitude of the negative half-wave of the secondary winding to be greater than the critical current of the superconducting switch, the direction of the transmission current pumped into the stator of the closed coil and the direction of the magnetic flux movement on the superconducting switch are changed, thereby realizing the magnetization or demagnetization of the stator of the closed superconducting coil; When the wireless excitation system is a rotating traveling wave magnetic flux pump, the closed superconducting coil magnetic levitation bearing includes: a closed superconducting coil stator, a magnetic flux source rotor, a rotating shaft, a superconducting switch, and a rotating motor rotor with embedded permanent magnets; the superconducting switch is part of the closed coil stator, enabling the stator to form a superconducting closed circuit; A superconducting switch is used to regulate the magnetic flux of a closed-loop stator; a rotating motor rotor with embedded permanent magnets generates a rotating magnetic field, which cuts the superconducting switch, producing a DC voltage across its terminals, thereby enabling the pumping of current into the stator coil for magnetic flux regulation; the direction of the pumped current into the stator is changed by altering the rotation direction of the rotating motor rotor. When the wireless excitation system is a linear traveling wave flux pump, the closed superconducting coil magnetic levitation bearing includes: a closed superconducting coil stator, a flux source rotor, a shaft, a superconducting switch, and a linear traveling wave winding; the superconducting switch is part of the closed coil stator, enabling the stator to form a superconducting closed loop; The superconducting switch is used to control the magnetic flux of the coil; the linear traveling wave winding is used to generate a planar traveling wave magnetic field in the air gap when the phase sequence current is applied; the traveling wave magnetic field acts on the superconducting switch, generating a rectified voltage at its two ends, thereby realizing the pumping of transmission current into the stator coil for magnetic flux control; by changing the direction of the current in the traveling wave winding, the direction of the transmission current pumped into the stator is changed. When using a magnetic levitation operating mode with PCS+ power supply for magnetic flux control, it includes: a closed superconducting coil stator, a rotating shaft, a magnetic flux source rotor, a superconducting constant current switch, current leads, and an external power supply; The flux source rotor is located inside the closed superconducting coil stator; the superconducting constant current switch is connected to the closed superconducting coil stator; the external power supply is connected to the superconducting constant current switch through current leads; When the closed superconducting coil stator is subjected to magnetic flux control, the superconducting constant current switch is turned off, and the closed superconducting coil stator is directly connected in parallel to the two ends of the external power supply; the external power supply is used to magnetize or demagnetize the closed superconducting coil stator.

2. The closed superconducting coil magnetic levitation bearing according to claim 1, characterized in that, The closed superconducting coil stator is wound with superconducting wire, which can be a low-temperature superconducting wire or a high-temperature superconducting wire; The low-temperature superconducting wire is NbTi or ; High-temperature superconducting wires are made of ReBCO, Bi-2223, and Bi-2212. Or iron-based superconductors.

3. The closed superconducting coil magnetic levitation bearing according to claim 1 or 2, characterized in that, The flux source rotor is a permanent magnet, a conventionally conducting magnet, or a superconducting magnet; wherein, the superconducting magnet is a superconducting bulk material, a stacked strip, or a superconducting coil.

4. A method for constructing a levitation state based on a closed superconducting coil magnetic levitation bearing according to any one of claims 1 to 3, characterized in that, Specifically, the following steps are included: Step 1: The flux source rotor remains stationary under the initial support device. The closed superconducting coil stator is cooled to the superconducting state. The closed superconducting coil stator is used to lock the background magnetic field provided by the flux source rotor at the current position. Step 2: Remove the initial support device to allow the flux source rotor to move under the load, and induce a shielding current in the closed superconducting coil stator; Alternatively, the initial support device can be retained, and transmission current can be pumped into the closed superconducting coil stator; Step 3: The shielding current or transmission current interacts with the background magnetic field, causing the flux source rotor to be subjected to a levitation force opposite to the load direction, until the magnitude of the levitation force on the flux source rotor is equal to the load, and the flux source rotor establishes a levitation state.

5. The method for constructing a suspended state according to claim 4, characterized in that, If a wireless excitation system is installed in the closed superconducting coil magnetic levitation bearing, step two is as follows: The flux source rotor is initially stationary under support. A wireless excitation system pumps transmission current into the closed superconducting coil stator. The transmission current interacts with the background magnetic field, causing the closed superconducting coil stator to be subjected to a Lorentz force in the same direction as the load, while the flux source rotor is subjected to a levitation force in the opposite direction to the load. When the levitation force increases to be equal to the load, the flux source rotor establishes a levitation state.

6. The method for constructing a suspended state according to claim 5, characterized in that, It also includes adjusting the magnitude of the levitation force and the levitation position, and the specific steps are as follows: Step 4: After the flux source rotor establishes a levitation state, a wireless excitation system is used to pump a transmission current in the same direction as the initial current into the stator of the closed superconducting coil. The total current inside the closed superconducting coil increases, and the levitation force on the flux source rotor is greater than the load. The flux source rotor moves in the direction of the levitation force. Step 5: As the magnetic flux source rotor moves in the direction of the levitation force, a shielding current is induced inside the coil in the opposite direction to the pumped transmission current. When the shielding current increases to the point of canceling the transmission current pumped in step 4, the magnetic flux source rotor re-establishes a levitation state at a higher position. or Step 4: After the flux source rotor establishes a levitation state, a wireless excitation system is used to pump a transmission current in the opposite direction to the initial current into the stator of the closed superconducting coil. The total current inside the closed superconducting coil decreases, the levitation force on the flux source rotor is less than the load, and the flux source rotor moves in the direction of the load. Step 5: As the flux source rotor moves toward the load direction, a shielding current is induced inside the coil, which is opposite to the pumped transmission current. When the shielding current increases to offset the transmission current pumped in step 4, the flux source rotor re-establishes a levitation state at a lower position.

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