A misaligned self-centering hybrid magnetic thrust bearing structure and a restoring force calculation method

Abstract

The application belongs to the technical field of hybrid magnetic suspension bearings, and discloses a staggered self-centering hybrid magnetic thrust bearing structure and a restoring force calculation method. The staggered self-centering hybrid magnetic thrust bearing structure comprises a radial repulsion ring, an axial repulsion ring and an axial electromagnetic bearing. The radial repulsion ring is used to generate a restoring force for offsetting an unbalanced force of the axial repulsion ring along a radial direction and a gravity of a rotor, and maintaining stability of the rotor along two offset degrees of freedom in a radial plane. The axial repulsion ring is used to offset an unbalanced load of the radial repulsion ring along an axial direction and an external axial load, and maintain stability of the rotor along the axial direction. The axial electromagnetic bearing is used to offset a tilting moment of the rotor around the radial plane, and maintain stability of the rotor around two rotation degrees of freedom in a transverse direction and a vertical direction. The restoring force calculation method does not need to rely on finite element simulation, is suitable for occasions where calculation resources are limited and parameters need to be quickly iterated in the early stage of design, and has good rapidity, practicability and convenience in actual engineering application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hybrid magnetic suspension bearings, and relates to a hybrid magnetic thrust bearing structure with staggered self-centering and a restoring force calculation method. BACKGROUND

[0002] The hybrid magnetic thrust bearing is a combined magnetic suspension bearing system formed on the basis of active magnetic bearings, passive magnetic thrust bearings and other auxiliary supporting and stabilizing structures, and has the advantages of strong control ability of active magnetic bearings, realization of stable suspension of a rotor, strong residual magnetic field of passive magnetic thrust bearings and large load capacity, is beneficial to reducing the size of the magnetic bearing, saving materials and being suitable for miniaturization and small volume application occasions. Most of the existing hybrid magnetic thrust bearing designs adopt permanent magnets to provide a bias magnetic field and electromagnets to provide a control magnetic field for balancing a load or external interference. In actual use, coupling often exists between the control magnetic field and the bias magnetic field, thereby increasing the power loss and heat generation of the coil, and the permanent magnet has a demagnetization risk. In addition, when designing the hybrid magnetic thrust bearing, considering the axial thrust load bearing requirement, the passive magnetic thrust bearing is designed to have positive stiffness in the axial direction, so that it can generate a restoring force for offsetting external loads in the axial direction. However, according to the Enshou theorem, the magnetic force generated by the passive magnetic thrust bearing in the radial plane is necessarily unstable, and when the rotor has a small radial deviation, the magnetic force generated by the permanent magnet will make it accelerate to slip off, instead of returning to the center position. In order to realize the stable suspension of the rotor, the stability of the remaining degrees of freedom in addition to the axial deviation and rotation two degrees of freedom needs to be considered. At present, in order to realize the two degrees of freedom stability of the rotor along the radial plane, a radial electromagnetic bearing needs to be additionally designed, which increases the design difficulty and structural complexity of the hybrid magnetic thrust bearing. Therefore, it is of great significance to propose a hybrid magnetic thrust bearing structure with staggered self-centering function along the radial direction and a radial restoring force calculation method.

[0003] For the problem of radial suspension of hybrid magnetic thrust bearing, Yang Jiafeng, Gong Gaohe and Wu Rui proposed a five-degree-of-freedom hybrid magnetic suspension bearing system in the patent "Five-degree-of-freedom hybrid magnetic suspension bearing, motor and control method thereof" (CN202310616587.8). The system uses permanent magnets to generate a bias magnetic field in the radial and axial air gap between the rotor and the stator, supplemented by a control coil to generate a control magnetic field to achieve suspension. The advantage is that it can realize multi-degree-of-freedom suspension, shorten the length of the rotating shaft, and is conducive to improving the rotating speed of the rotating shaft. However, the coupling relationship between the bias magnetic field generated by the permanent magnet and the control magnetic field generated by the coil in the hybrid magnetic suspension bearing proposed in the paper is complex, and there are many types of coils, which requires a high control system. For the problem of structural design of magnetic suspension thrust bearing, Zhu Longfei, Guo Zhenghua and Liu Kang et al. proposed an axial permanent magnet suspension thrust permanent magnet bearing in the patent "Axial permanent magnet suspension thrust permanent magnet bearing" (CN202411016278.8). The advantage is that it can realize axial high-load suspension and reduce maintenance and repair difficulty. However, the structure of the magnetic suspension bearing proposed in the paper still needs auxiliary bearings to maintain balance in the radial direction, and the rotor has contact constraints in the radial direction, which cannot achieve stable suspension.

[0004] In summary, it is of great significance to propose a staggered self-centering hybrid magnetic thrust bearing structure and a restoring force calculation method to solve the problems of complex magnetic circuit and large coupling interference of existing radial suspension structure, as well as to guide the design of hybrid magnetic thrust bearing radial suspension structure and rapid calculation of radial restoring force. SUMMARY

[0005] The present application aims to make up for the defects of the prior art, and provides a misaligned self-centering hybrid magnetic thrust bearing structure and a restoring force calculation method.The purpose is to realize the stability of the remaining degrees of freedom except the axial offset and rotation of the rotor by providing a hybrid magnetic bearing structure composed of a radial repulsion ring, an axial repulsion ring and an axial electromagnetic bearing.The radial repulsion ring is used to generate a restoring force to offset the imbalance of the axial repulsion ring in the radial direction and the gravity of the rotor, and to maintain the stability of the two offset degrees of freedom of the rotor in the radial plane.The axial repulsion ring is used to offset the imbalance load of the radial repulsion ring in the axial direction and the external axial load, and to maintain the stability of the rotor in the axial direction.The axial electromagnetic bearing installed at both ends of the hybrid magnetic thrust bearing avoids excessive coupling with the magnetic circuit of the permanent magnet, and is used to offset the overturning moment of the rotor around the radial plane, to maintain the stability of the rotor around the two rotation degrees of freedom of the horizontal and vertical directions, and to assist in bearing part of the external load and enhance the load capacity of the hybrid magnetic thrust bearing.Further, in order to realize the rapid iteration of the initial structure parameters of the radial repulsion ring and the axial repulsion ring, an analytical calculation method of the radial restoring force is provided, which comprehensively considers the influence of the radial imbalance force of the axial repulsion ring and the gravity of the rotor, and provides important technical support for the design of the structure parameters of the repulsion ring of the misaligned self-centering hybrid magnetic thrust bearing.The calculation method does not need to rely on finite element simulation, and is suitable for occasions with limited computing resources, rapid iteration of initial design parameters and the like, and has good rapidity, practicability and convenience in actual engineering applications.

[0006] The technical scheme of the present application:

[0007] A misaligned self-centering hybrid magnetic thrust bearing structure is composed of a radial repulsion ring, an axial repulsion ring and an axial electromagnetic bearing, the radial repulsion ring generates a restoring force to resist the radial offset of the rotor, and maintains the stability of the movement of the rotor in the radial plane; the axial repulsion ring bears the external axial load and maintains the axial stability of the rotor; the axial electromagnetic bearing at both ends of the bearing assists in maintaining the stability of the rotation of the rotor around the radial plane, offsets the unbalanced overturning moment of the rotor and part of the external axial load. The misaligned self-centering hybrid magnetic thrust bearing structure comprises a mounting shaft, a bearing cover, a protective bearing, a circular nut, a conductor disc, an end cover, a stator core, an axial coil, a threaded sleeve, a rotor radial magnet disc, a rotor radial repulsion ring, a stator radial repulsion ring, a stator radial magnet disc, a stator spacer ring, a rotor axial magnet disc, a rotor axial repulsion ring, a stator axial repulsion ring, a stator axial magnet disc, a positioning strip, a flat key, a stator cylinder and an axial displacement sensor.

[0008] In assembly, the rotor axial repulsion ring and the stator axial repulsion ring are respectively axially embedded in the ring grooves of the rotor axial magnet disc and the stator axial magnet disc; the rotor radial repulsion ring and the stator radial repulsion ring are respectively radially embedded in the ring grooves of the rotor radial magnet disc and the stator radial magnet disc; the axial electromagnetic bearing is composed of a conductor disc, a stator core, an axial coil and an axial displacement sensor, the axial gap between the stator core and the conductor disc is detected by the four axial displacement sensors arranged uniformly along the circumference of the stator core, so that the real-time position of the rotor around the plane is obtained; the conductor disc mounted on the mounting shaft is subjected to electromagnetic attraction in four directions by the four axial coils arranged uniformly along the circumference of the stator core, and the resistance moment hindering the rotor from tilting around the plane is generated by the two groups of axial electromagnetic bearings arranged symmetrically at both ends, so that the stability of the rotor rotating around the plane is realized. XY X, +X, -Y, +Y XY XY

[0009] The rotor axial magnet disc is circumferentially positioned on the mounting shaft by means of a flat key, and the axial pre-tightening and positioning of the rotor axial magnet disc, the rotor radial magnet disc and the conductor disc are realized by a round nut; the stator axial magnet disc, the stator spacer ring and the stator radial magnet disc are circumferentially positioned with the stator cylinder by means of a positioning strip, and are axially positioned and pre-tightened by a threaded sleeve; the stator core is interference-fitted on the inner stop of the end cover, and is fixed to the shaft end of the stator cylinder through the outer stop on the end cover; the protection bearing is embedded in the side ring groove of the end cover, and is axially positioned and pre-tightened by a bearing cover to prevent direct contact between the rotor and the stator. Through the above structural design, the mixed magnetic thrust bearing rotor can be self-centered and stably suspended in each direction, and the rotor radial suspension only relies on the repulsion force generated by the permanent magnet ring, which is simple in structure and does not require an additional control system.

[0010] A restoring force calculation method of a misaligned self-centering mixed magnetic thrust bearing structure, first, the key parameters of the misaligned self-centering mixed magnetic thrust bearing are determined; second, a single-side radial repulsion ring radial restoring force analytical model is constructed to obtain a restoring force calculation formula; third, a single-side axial repulsion ring radial unbalanced force analytical model is constructed to obtain an unbalanced force calculation formula; then, a rotor single-side radial effective restoring force calculation formula is obtained; finally, the radial effective restoring force under the maximum displacement of the rotor is obtained, and a bearing safety factor is calculated. This method comprehensively considers the influence of the radial unbalanced force of the axial repulsion ring and the rotor gravity on the radial restoring force, and can realize the rapid calculation of the radial restoring force supporting the rotor, which has the advantages of small calculation amount and convenient operation in actual engineering application.

[0011] The steps are as follows:

[0012] First step, determine the key parameters of the misaligned self-centering mixed magnetic thrust bearing;

[0013] ​​​​First, determine the structural parameters of the rotor radial repulsion ring and the stator radial repulsion ring: the inner radius of the stator radial repulsion ring is... R 1. The outer radius of the rotor radial repulsion ring is R 2. The axial lengths of both the rotor radial repulsion ring and the stator radial repulsion ring are... L The radial thickness of both the rotor radial repulsion ring and the stator radial repulsion ring is H Then, the structural parameters of the rotor axial repulsion ring and the stator axial repulsion ring are determined: the outer radii of both the rotor axial repulsion ring and the stator axial repulsion ring are... r 1. The inner radius is... r 2. The axial length is all l The axial distance between the rotor radial repulsion ring and the stator radial repulsion ring is s Finally, the rotor's own weight is G The radial clearance at the bearing protection point is g The residual magnetism of the rotor radial repulsion ring, stator radial repulsion ring, rotor axial repulsion ring, and stator axial repulsion ring is all... B r Both relative permeability are μ r ;

[0014] The second step is to construct an analytical model of the radial restoring force of a single-sided radial repulsion ring and obtain the formula for calculating the restoring force.

[0015] First, define the intermediate function. f ( θ )as follows:

[0016] (1)

[0017] In the formula: δ 0 is the nominal air gap thickness, and δ 0= R 1- R 2. α Let be the section modulus of the rotor radial repulsion ring and the stator radial repulsion ring, and , μ r =1.05、 e For the rotor radial repulsion ring edge + X Directional offset; θ The circumferential position angle is initially equal to + X Directions coincide;

[0018] Secondly, obtain the total magnetic energy of the air gap as a function of the offset. e Analytical expression of change W m ( e )as follows:

[0019] (2)

[0020] In the formula: R avg Let be the average radius of the rotor radial repulsion ring and the stator radial repulsion ring, and ; μ 0 is the free permeability, and μ 0=4 π ×10 -7 H / m;

[0021] Then, for the analytical expression W m ( e The Taylor expansion is performed, and the calculation formula is as follows:

[0022] (3)

[0023] In the formula: W 0 represents the zero eccentric potential energy constant term, and ; ; W 2 is a linear stiffness term, and ; ; O ( e 3 ) represents a higher-order infinitesimal term;

[0024] Finally, the radial restoring force as a function of the offset is obtained using the virtual displacement method. e Analytical expression of change f 1( e )as follows:

[0025] (4)

[0026] The third step is to construct an analytical model of radial unbalanced force of a single-sided axial repulsion ring and obtain the calculation formula for the unbalanced force.

[0027] First, obtain the analytical expression for the radial distance between corresponding points of the rotor axial repulsion ring and the stator axial repulsion ring. δ ( θ )as follows:

[0028] (5)

[0029] In the formula: s The axial clearance between the rotor axial repulsion ring and the stator axial repulsion ring; It is the eccentric direction angle, and ;

[0030] Then, it is assumed that all magnetic field energy is concentrated at the average radius of the rotor axial repulsion ring and the stator axial repulsion ring.r avg On the cylindrical surface, the analytical formula for the total magnetic energy of the air gap is... W n ( e )as follows:

[0031] (6)

[0032] In the formula: r avg Let be the average radius of the rotor axial repulsion ring and the stator axial repulsion ring, and ; β The leakage flux coefficient ranges from 0.1 to 0.3.

[0033] Finally, the radial unbalanced force as a function of the offset is obtained using the virtual displacement method. e Analytical expression of change f 2( e )as follows:

[0034] (7)

[0035] Step 4: Obtain the calculation formula for the effective radial restoring force on one side of the rotor;

[0036] Effective radial restoring force on one side of the rotor f m ( e )as follows:

[0037] (8)

[0038] Step 5: Obtain the effective radial restoring force under the maximum rotor offset and calculate the load-bearing safety factor;

[0039] Due to the radial constraint of the protected bearing, the maximum radial offset of the rotor is the radial clearance at the protected bearing. e = g Substitute radial effective restoring force f m ( e The effective radial restoring force under the maximum rotor offset was calculated. F r The load-bearing safety factor is calculated by combining the rotor's own weight. S The calculation formula is as follows:

[0040] (9)

[0041]

[0042] This completes the calculation of the restoring force of the misaligned self-centering hybrid magnetic thrust bearing structure.

[0043] The beneficial effects of this invention are that it proposes a misaligned self-centering hybrid magnetic thrust bearing, which is assembled from a radial repulsion ring, an axial repulsion ring, and an axial electromagnetic bearing. The radial repulsion ring generates a restoring force to resist the radial offset of the rotor, maintaining the stability of the rotor's movement along the radial plane. The structure is simple and requires no additional control system. The axial repulsion ring bears the external axial load and maintains the axial stability of the rotor, with high load-bearing capacity and no need for power supply. The axial electromagnetic bearings at both ends of the bearing assist in maintaining the stability of the rotor's rotation around the radial plane, offsetting the unbalanced overturning moment and part of the external axial load on the rotor. It provides good real-time position control performance for the rotor, helping to enhance the rotor's ability to resist changes in external load and achieve stable levitation in all directions. Furthermore, based on the structural characteristics of the proposed misaligned self-centering hybrid magnetic thrust bearing, an analytical calculation method for the radial restoring force is proposed, comprehensively considering the radial unbalanced force of the axial repulsion ring and the rotor's gravity. This method enables rapid calculation of the radial restoring force supporting the rotor, offering advantages such as low computational load and convenient operation in practical engineering applications. It provides important technical support for the initial rapid design iteration of the radial restoring force of the misaligned self-centering hybrid magnetic thrust bearing. Attached Figure Description

[0044] Figure 1 This is an assembly drawing of a misaligned self-centering hybrid magnetic thrust bearing;

[0045] Figure 2 yes Figure 1 Middle YZ A sectional view of a plane;

[0046] Figure 3 yes Figure 2 Schematic diagram of the rotor assembly;

[0047] Figure 4 for Figure 2 A schematic diagram of real-time rotor position control via a central axial electromagnetic bearing;

[0048] Figure 5 for Figure 2 Schematic diagram of the analytical model of the radial restoring force generated by a single-sided radial repulsion ring;

[0049] Figure 6 for Figure 2 Schematic diagram of the analytical model of radial unbalanced force generated by a single-sided axial repulsion ring;

[0050] Figure 7 A flowchart of a method for calculating the radial restoring force of a misaligned self-centering hybrid magnetic thrust bearing;

[0051] In the diagram: 1-Mounting shaft, 2-Bearing cover, 3-Protective bearing, 4-Round nut, 5-Conductor disc, 6-End cover, 7-Stator core, 8-Axial coil, 9-Threaded sleeve, 10-Rotor radial magnet disc, 11-Rotor radial repulsion ring, 12-Stator radial repulsion ring, 13-Stator radial magnet disc, 14-Stator spacer, 15-Rotor axial magnet disc, 16-Rotor axial repulsion ring, 17-Stator axial repulsion ring, 18-Stator axial magnet disc, 19-Positioning bar, 20-Flat key, 21-Stator cylinder, 22-Axial displacement sensor. Detailed Implementation

[0052] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0053] This implementation case uses a misaligned self-centering hybrid magnetic thrust bearing with an axial rated load of 300N for analytical calculation of radial restoring force. The specific steps are as follows:

[0054] The first step is to determine the key parameters of the misaligned self-centering hybrid magnetic thrust bearing;

[0055] Figure 2 A type of misaligned self-centering hybrid magnetic thrust bearing along YZ A sectional view of the plane, wherein the inner radius of the stator radial repulsion ring 12 is... R 1 = 0.032m, the outer radius of the rotor radial repulsion ring 11 is R 2 = 0.0312m, axial length is L =0.012m, radial thickness is H =0.008m; the outer radii of the rotor axial repulsion ring 16 and the stator axial repulsion ring 17 are r 1 = 0.0365m, inner radius is r 2 = 0.0245m, axial length is l =0.006m, axial spacing is s =0.001m; Rotor's own weight G =15N; Protects the radial clearance at 3 points on the bearing. g =0.0005m; Residual magnetism of rotor radial repulsion ring 11, stator radial repulsion ring 12, rotor axial repulsion ring 16 and stator axial repulsion ring 17 B r =1.41T, permeability μ r =1.05;

[0056] The second step is to construct an analytical model of the radial restoring force of a single-sided radial repulsion ring and obtain the formula for calculating the restoring force.

[0057] Substituting the known parameters into equations (1) to (4), we can see that... δ0 = 0.0008m α =0.192、 R avg =0.0316m W 0 = 0.947 J W 1=0、 W 2 = -82049.616 N / m W 3=0, f ( θ The analytical expression is as follows:

[0058]

[0059] W m ( e The analytical expression is as follows:

[0060]

[0061] W m ( e The Taylor expansion of the analytical expression is as follows:

[0062]

[0063] f 1( e The analytical expression is as follows:

[0064]

[0065] The third step is to construct an analytical model of radial unbalanced force of a single-sided axial repulsion ring and obtain the calculation formula for the unbalanced force.

[0066] Substituting the known parameters into equations (5) to (7), we can see that... r avg =0.0305m β =0.2, δ ( θ The analytical expression is as follows:

[0067]

[0068] W n ( e The analytical expression is as follows:

[0069]

[0070] f 2( e The analytical expression is as follows:

[0071]

[0072] Step 4: Obtain the calculation formula for the effective radial restoring force on one side of the rotor;

[0073] Will f 1( e )and f 2( e Substituting into equation (8), we can obtain, f m ( e The analytical expression is as follows:

[0074]

[0075] Step 5: Obtain the effective radial restoring force under the maximum rotor offset and calculate the load-bearing safety factor;

[0076] Due to the radial constraint of the protected bearing, the maximum radial displacement of the rotor is equal to the clearance of the protected bearing. e = g Substituting 0.0005m into equation (9), the radial restoring force under the maximum rotor offset can be obtained. F r =20.976N, substituting into equation (10) yields the bearing safety factor. S =1.4. The calculation is now complete.

[0077] This calculation method comprehensively considers the effects of the radial unbalanced force of the axial repulsion ring and the rotor gravity, and can realize the rapid calculation of the radial restoring force of the supporting rotor. In practical engineering applications, it has the advantages of small calculation amount and convenient operation, and provides important technical support for the initial rapid design iteration of the radial restoring force of misaligned self-centering hybrid magnetic thrust bearings.

Claims

1. A restoring force calculation method for a misaligned self-centering hybrid magnetic thrust bearing structure, characterized in that, The steps are as follows: The first step is to construct and determine the key parameters of the misaligned self-centering hybrid magnetic thrust bearing; The misaligned self-centering hybrid magnetic thrust bearing structure comprises a mounting shaft (1), a bearing cover (2), a protective bearing (3), a circular nut (4), a conductor disc (5), an end cover (6), a stator core (7), an axial coil (8), a threaded sleeve (9), a rotor radial magnet disc (10), a rotor radial repulsion ring (11), a stator radial repulsion ring (12), a stator radial magnet disc (13), a stator spacer ring (14), a rotor axial magnet disc (15), a rotor axial repulsion ring (16), a stator axial repulsion ring (17), a stator axial magnet disc (18), a positioning strip (19), a flat key (20), a stator cylinder (21), and an axial displacement sensor (22); The rotor axial repulsion ring (16) and the stator axial repulsion ring (17) are respectively axially embedded in the ring groove of the rotor axial magnet disc (15) and the stator axial magnet disc (18); the rotor radial repulsion ring (11) and the stator radial repulsion ring (12) are respectively radially embedded in the ring groove of the rotor radial magnet disc (10) and the stator radial magnet disc (13); the axial electromagnetic bearing is composed of the conductor disc (5), the stator core (7), the axial coil (8) and the axial displacement sensor (22), the axial gap between the stator core (7) and the conductor disc (5) is detected by the four axial displacement sensors (22) arranged uniformly along the circumference of the stator core (7), so that the real-time position of the rotor around XY the plane is obtained; the electromagnetic suction force in four directions is applied to the conductor disc (5) sleeved on the mounting shaft (1) by the four axial coils (8) arranged uniformly along the circumference of the stator core (7), and the resistance moment hindering the rotor from tilting around X, +X, -Y, +Y the plane is generated by the two groups of axial electromagnetic bearings arranged symmetrically at both ends, so that the stability of the rotor rotating around XY the plane is realized. XY ​ The rotor axial magnet disc (15) is circumferentially positioned on the mounting shaft (1) by the flat key (20), and the rotor axial magnet disc (15), the rotor radial magnet disc (10), and the conductor disc (5) are axially pre-tightened and positioned by the circular nut (4); the stator axial magnet disc (18), the stator spacer ring (14), and the stator radial magnet disc (13) are circumferentially positioned with the stator cylinder (21) by the positioning strip (19), and are axially positioned and pre-tightened by the threaded sleeve (9); the stator core (7) is interference-fitted on the inner stop of the end cover (6), and is fixed to the shaft end of the stator cylinder (21) through the outer stop of the end cover (6); the protective bearing (3) is embedded in the side ring groove of the end cover (6), and is axially positioned and pre-tightened by the bearing cover (2) to prevent direct contact between the rotor and the stator; The second step is to construct a single-sided radial repulsion ring radial restoring force analytical model to obtain a restoring force calculation formula. First, define the intermediate function f ( θ ) as follows: In the formula: δ 0 is a nominal air gap thickness, and δ 0= R 1- R 2、 α is a cross-sectional coefficient of the rotor radial repulsion ring (11) and the stator radial repulsion ring (12), and , μ r =1.05、 e is a direction offset of the rotor radial repulsion ring (11) along the X direction; θ is a circumferential position angle, which is initially coincident with the X direction; Secondly, the total magnetic energy of air gap is acquired with the offset e The analytical expression of the variation W m ( e ) is as follows: wherein: R avg R is the average radius of the rotor radial repulsion ring (11) and the stator radial repulsion ring (12), and ; μ 0 is the vacuum permeability, and μ 0 = 4 π × 10 -7 H / m; Then, the Taylor expansion of the analytical expression W m ( e ) is calculated as follows: wherein: W 0 is a zero-eccentricity potential constant term, and ; ; W 2 is a linear stiffness term, and ; ; O ( e 3 ) is a high-order infinitesimal term; Finally, the radial restoring force versus displacement is obtained by the virtual displacement method e Analytical expression of the variation f 1( e ) as follows: ； The third step is to construct a single-sided axial repulsion ring radial unbalanced force analytical model to obtain an unbalanced force calculation formula. First, the radial distance analytical expression of the corresponding points of the rotor axial repulsion ring (16) and the stator axial repulsion ring (17) is obtained as follows: δ θ )​ In the formula: s is the axial gap of the rotor axial repulsion ring (16) and the stator axial repulsion ring (17); is the eccentric direction angle, and ; Then, assuming that all the magnetic field energy is concentrated in the average radius of the rotor axial repulsion ring (16) and the stator axial repulsion ring (17) cylindrical surface r avg , then the air gap total magnetic energy analytical expression W n ( e ) is as follows: In the formula: r avg R is the average radius of the rotor axial repulsion ring (16) and the stator axial repulsion ring (17), and ; β is a leakage coefficient, and the value range is 0.1~0.3; Finally, the radial unbalance force with the offset is obtained by the virtual displacement method e The analytical expression of the change f 2( e ) is as follows: ； The fourth step is to obtain a single-sided radial effective restoring force calculation formula of the rotor. Radial effective restoring force on one side of the rotor f m ( e ) as follows: ； The fifth step is to obtain the radial effective restoring force under the maximum displacement of the rotor and calculate the bearing safety factor.

2. The restoring force calculation method of the misaligned self-centering hybrid magnetic thrust bearing structure according to claim 1, characterized in that, The key parameters of the misaligned self-centering hybrid magnetic thrust bearing include: Firstly, the structure parameters of the rotor radial repulsion ring (11) and the stator radial repulsion ring (12) are determined: the inner radius of the stator radial repulsion ring (12) is R 1, the outer radius of the rotor radial repulsion ring (11) is R 2, the axial length of the rotor radial repulsion ring (11) and the stator radial repulsion ring (12) is L , and the radial thickness of the rotor radial repulsion ring (11) and the stator radial repulsion ring (12) is H ; then, the structure parameters of the rotor axial repulsion ring (16) and the stator axial repulsion ring (17) are determined: the outer radius of the rotor axial repulsion ring (16) and the stator axial repulsion ring (17) is r 1, the inner radius is r 2, the axial length is l , the axial spacing of the rotor radial repulsion ring (11) and the stator radial repulsion ring (12) is s ; finally, the rotor self-gravity is G ; the radial clearance at the protection bearing (3) is g ; the residual magnetism of the rotor radial repulsion ring (11), the stator radial repulsion ring (12), the rotor axial repulsion ring (16) and the stator axial repulsion ring (17) is B r , and the relative magnetic permeability is μ r .

3. The method of claim 2, wherein, The specific implementation process of the fifth step is as follows: Due to the radial constraint of the protective bearing (3), the maximum radial offset of the rotor is the radial clearance at the protective bearing (3). e = g Substitute radial effective restoring force f m ( e The effective radial restoring force under the maximum rotor offset was calculated. F r The load-bearing safety factor is calculated by combining the rotor's own weight. S The calculation formula is as follows: Thus, the restoring force calculation of the misaligned self-centering hybrid magnetic thrust bearing structure is completed.

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