High-speed motor magnetic suspension bearing based on thermal-magnetic coupling clearance dynamic optimization and design method thereof

Abstract

The invention relates to a high-speed motor magnetic suspension bearing based on thermal-magnetic coupling clearance dynamic optimization and a design method thereof. When the motor rotates at a high speed to generate temperature rise, the rotor thermally expands to drive the inner ring of the L-shaped magnetic suspension rotor to displace outwards, radial and axial internal clearances are synchronously compressed, and then a suspension steady state under the current working condition is adaptively constructed under the thermal expansion working condition, so that the stability of the magnetic suspension bearing is improved. The self-adaptive adjustment of the clearance is realized; when the motor stops rotating and is naturally cooled to the environment temperature, the inner ring of the L-shaped magnetic suspension rotor retreats reversely, and the radial and axial clearance is automatically recovered to the initial cold state design value; therefore, it is ensured that the radial and axial clearance can be precisely, reversibly and dynamically restored between a cold-state initial design value and a hot-state working compression value along with the temperature change of the rotor, and self-adaptive clearance adjustment in the whole starting and stopping period of the motor is achieved.

Description

Technical Field

[0001] This invention relates to the field of magnetic levitation bearing technology, specifically to a high-speed motor magnetic levitation bearing and its design method based on dynamic optimization of thermo-magnetic coupling clearance. Background Technology

[0002] The rapid development of new energy technologies has placed increasingly stringent demands on the power density and limiting speed of electric motors. Currently, the supporting components of high-speed motors primarily rely on steel or hybrid ceramic bearings. Under high-speed rotation conditions, the motor rotor not only bears enormous centrifugal loads but also generates a large amount of heat due to eddy current losses and mechanical friction. This causes the rotor and the inner ring of the bearing to expand thermally, compressing the balls. This compression completely eliminates the original design clearance of the bearing, leading to a further sharp increase in friction, ultimately resulting in bearing failures such as plastic deformation, seizure, or even burnout. Currently, the limiting speed of mainstream grease-lubricated mechanical bearings in industry is typically limited to 20,000~25,000 RPM.

[0003] Chinese patent document CN115001336A discloses a method for controlling rotor vibration of a high-speed magnetic levitation motor at full speed. This method acquires rotor displacement signals through sensors and uses active control methods such as PID controllers to output control signals to compensate for phase and suppress rotor vibration. The core technical solution of this method is to control the rotor suspension clearance and stability through dynamic adjustment of electromagnetic force. However, this technical solution has the following technical defects: its control model is only based on the single-dimensional dynamic feedback of "displacement-electromagnetic force," failing to incorporate the "thermal field effect" into the control closed loop. Under high-speed extreme conditions, the drastic temperature rise inside the motor will cause significant thermal expansion of the rotor and bearing inner rings. Thermal expansion not only changes the physical clearance but also causes nonlinear distortion of the magnetic reluctance. Because this existing technology lacks a "thermal-magnetic coupling" compensation model, once severe thermal deformation occurs, its original displacement feedback parameters will become mismatched, ultimately leading to deviations in the electromagnetic force output, which can easily cause bearing rubbing or even seizure and burnout.

[0004] Chinese patent document CN105650117A discloses a magnetic levitation bearing assembly and a compressor. This solution discloses a magnetic levitation bearing assembly with an internal "working clearance adjustment device." This device is arranged radially and axially between the fixed housing, the iron core, and the thrust disc. It primarily achieves structural adjustment of the working clearance of the magnetic levitation bearing by changing the length of the adjustment device and the reserved clearance. However, this technical solution has the following drawbacks: It is essentially a static or passive mechanical structure clearance adjustment. When high-speed motors face complex and variable operating conditions, the distribution of the internal thermal field and the amount of thermal expansion are real-time and highly dynamic. This purely mechanical preset clearance or manual adjustment has an extremely slow response and cannot achieve "real-time dynamic optimization" of the micron-level clearance. Furthermore, the mechanical shims or adjusting rings themselves will undergo fatigue deformation under long-term thermal stress, making it impossible to guarantee working accuracy throughout their entire lifespan.

[0005] In summary, existing magnetic levitation bearing technologies often treat "mechanical adjustment of clearance" and "electromagnetic clearance control" in isolation, and both lack in-depth exploration and real-time compensation of the cross-coupling effects of thermal and magnetic fields. The single passive absorption or one-dimensional displacement feedback methods in existing technologies cannot guarantee the micron-level accuracy of clearance and system stability under ultra-high-speed operating conditions. Therefore, there is an urgent need to realize a high-speed motor magnetic levitation bearing and its design method based on dynamic optimization of clearance through thermal-magnetic coupling. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a high-speed motor magnetic levitation bearing and its design method based on dynamic optimization of thermal-magnetic coupling clearance.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance includes two sets of magnetic levitation bearing assemblies that are mirror-symmetrically disposed at both ends of the motor rotor.

[0009] The magnetic levitation bearing assembly includes an L-shaped magnetic levitation stator outer ring disposed on the stator side of the motor and an L-shaped magnetic levitation rotor inner ring disposed on the rotor side of the motor.

[0010] The L-shaped magnetic levitation stator outer ring is fixed to the motor housing; the L-shaped magnetic levitation rotor inner ring is bonded to the motor rotor and rotates synchronously with the motor rotor; the L-shaped magnetic levitation stator outer ring covers the outer side of the L-shaped magnetic levitation rotor inner ring, and a magnetic levitation air gap is reserved between the two, the magnetic levitation air gap including radial magnetic levitation clearance and axial magnetic levitation clearance.

[0011] Furthermore, the inner cylindrical surface of the outer ring of the L-shaped magnetic levitation stator and its corresponding axial end face, as well as the outer cylindrical surface of the inner ring of the L-shaped magnetic levitation rotor and its corresponding axial end face, are all magnetized with the first polarity.

[0012] The inner vertical end face of the inner ring of the L-shaped magnetic levitation rotor on the left side of the motor rotor and the inner vertical end face of the inner ring of the L-shaped magnetic levitation rotor on the right side of the motor rotor are both magnetized to the second polarity.

[0013] The first polarity is opposite to the second polarity.

[0014] Furthermore, the inner ring of the L-shaped magnetic levitation rotor is bonded to the motor rotor with adhesive.

[0015] This invention also includes a design method for a high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance, the method comprising:

[0016] S1. Obtain the basic parameters of the motor rotor;

[0017] S2. Construct a thermal expansion displacement model of the rotor at the rated maximum operating temperature, and calculate the radial thermal expansion displacement and axial thermal expansion displacement of the rotor as it expands due to heat and is transmitted to the inner ring of the L-shaped magnetic levitation rotor.

[0018] S3. Construct a dynamic clearance compression model for the magnetic levitation bearing. Based on the radial thermal expansion displacement and the axial thermal expansion displacement, calculate the actual radial clearance and actual axial clearance between the outer ring and the inner ring of the bearing under thermal conditions.

[0019] S4. Establish the adaptive equation for magnetic balance, and determine the optimal initial installation radial clearance, axial clearance and effective area of ​​magnetic poles for the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor, with the dynamic disturbance force of magnetic repulsion balance under hot working conditions as the target.

[0020] Furthermore, the thermal expansion displacement model is as follows:

[0021] ;

[0022] ;

[0023] in, This is the radial thermal expansion. This is the axial thermal expansion. The initial ambient temperature of the motor. The rated maximum operating temperature, is the coefficient of linear expansion of the rotor material. The effective radius of the rotor's heated area. This is the effective axial length.

[0024] Furthermore, the dynamic clearance compression model is as follows:

[0025] ;

[0026] ;

[0027] in, The initial radial clearance designed for the inner and outer rings of the L-shape. This is the initial axial clearance. This refers to the actual radial clearance under hot operating conditions. This represents the actual axial clearance under hot operating conditions.

[0028] Furthermore, step S4 specifically includes the following steps:

[0029] S41. Based on the repulsive property of like poles of permanent magnets, the thermal magnetic repulsion force generated between the inner and outer rings of the L-shaped magnetic levitation rotor is inversely proportional to the square of the actual clearance between them; taking the dynamic disturbance force of the surge in magnetic repulsion force under thermal conditions as the benchmark, establish the adaptive equations for radial and axial magnetic force balance.

[0030] The adaptive equation for radial magnetic force balance is:

[0031] ;

[0032] The adaptive equation for axial magnetic force balance is:

[0033] ;

[0034] in, The magnetic constant of the permanent magnet material; and These are the radial effective magnetic pole areas and axial effective magnetic pole areas of the inner ring of the L-shaped magnetic levitation rotor and the outer ring of the stator, respectively. and These are the actual radial clearance and actual axial clearance under hot operating conditions, respectively. and These represent the initial radial magnetic repulsion and the initial axial magnetic repulsion under cold, static conditions, respectively. and These are the radial centrifugal disturbance force and the axial aerodynamic disturbance force generated by the rotor under extreme thermal conditions, respectively.

[0035] S42. Perform magnetic steady-state optimization calculation, set the objective function for magnetic steady-state optimization, and make the radial magnetic repulsion increment under hot conditions... Greater than or equal to the radial centrifugal disturbance force And the axial magnetic repulsion increment Greater than or equal to the axial aerodynamic disturbance force That is, the following inequality conditions must be met:

[0036] ;

[0037] ;

[0038] in, , These are the initial radial clearances under cold, static conditions. and initial axial clearance The initial radial magnetic repulsion force and the initial axial magnetic repulsion force generated; , These are the radial centrifugal disturbance force and the axial aerodynamic disturbance force generated by the rotor under extreme thermal conditions, respectively. , These are respectively due to the clearance being compressed to [a certain value] under hot operating conditions. and The radial and axial magnetic repulsion forces, which surged respectively, are related to the actual clearance. and It is inversely proportional to the square of.

[0039] S43. Input different initial clearance combinations and iterate the adaptive equation for magnetic balance until the output satisfies the inequality conditions. and The parameter solution is obtained to determine the optimal initial installation radial clearance, axial clearance, and effective pole area of ​​the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor.

[0040] Furthermore, the magnetic steady-state optimization process also includes safety boundary constraints to prevent mechanical abrasion and magnetic pole failure.

[0041] The safety boundary constraints include:

[0042] During the iterative calculation process, the minimum safe assembly and operating clearance of the motor is preset to be... ; This is a hard threshold set during the optimization process.

[0043] To ensure the high reliability of the design parameters output by the algorithm in practical engineering, this section... Further explanation, The hard threshold set during the optimization process is usually taken as... ~ Depending on the machining accuracy, even at the highest temperature rise limit, the calculated actual clearance must be greater than the threshold to redundantly compensate for the unbalanced amplitude in rotor dynamics and the manufacturing tolerances of parts.

[0044] In any iteration step, the actual radial clearance under the aforementioned thermal condition must be satisfied. Compared with actual axial clearance Strictly greater than the minimum safe assembly and operating clearance, i.e.:

[0045] ;

[0046] ;

[0047] If the initial gap of the current iteration output and If the clearance under hot operating conditions does not satisfy the above inequality, then the effective magnetic pole area of ​​the inner ring of the L-shaped magnetic levitation rotor and the outer ring of the stator should be adjusted. and Alternatively, a higher-performance permanent magnet material could be selected to improve the magnetic constant. Then, it re-enters step S4 for optimization iteration.

[0048] Furthermore, after outputting the optimal initial clearance that meets the conditions in step S4, the design method also includes performing a hot-state dynamic stiffness verification on the levitation steady state, specifically including:

[0049] S51. Calculate the thermal magnetic stiffness: radial magnetic repulsion. Regarding radial clearance Differentiate to obtain the thermal radial magnetic stiffness. ; Axial magnetic repulsion Regarding axial clearance Differentiate to obtain the hot axial magnetic stiffness. ;

[0050] S52. Calculate the critical frequency: considering the rotor mass. And rotational inertia, using the calculated thermal radial magnetic stiffness and thermal axial magnetic stiffness Calculate the critical resonant frequency of the rotor under the stated thermal limiting condition. ;

[0051] S53. Avoidance zone verification: Verify the critical resonance frequency. Check whether the excitation frequency range corresponding to the rated operating speed of the motor is avoided. If not, return to step S4 to readjust the initial clearance. and The combination ratio, or adjusting the effective area of ​​the magnetic poles. , Until the avoidance requirements are met.

[0052] Furthermore, the rotor parameters include: basic physical dimensions, mass, moment of inertia, rated operating speed of the motor, coefficient of linear expansion of the material, and rated maximum operating temperature.

[0053] Compared with the prior art, the advantages of the present invention are:

[0054] (1) This invention abandons the traditional mechanical contact support scheme and proposes a "passive suspension, clearance adaptive" support scheme constructed using L-shaped permanent magnets. Since the mechanical contact path is completely blocked, eliminating mechanical friction and wear, the maximum allowable speed of the magnetic levitation bearing in this invention no longer depends on the support components themselves, but rather on the centrifugal structural strength of the rotor body and permanent magnet material under high-speed rotation. The magnetic levitation bearing in this invention supports the stable operation of the motor at ultra-high speeds exceeding 100,000 RPM.

[0055] (2) This invention innovatively constructs a non-contact NdFeB support system consisting of an L-shaped magnetic levitation stator outer ring on the stator side and an L-shaped magnetic levitation rotor inner ring on the rotor side. The radial levitation force is set by adjusting the cylindrical length of the L-shaped magnetic ring, and the axial constraint force is set by adjusting the vertical end face height or component span, forming a non-interfering adjustment mechanism that can achieve optimal mechanical matching for different dynamic requirements of high-speed motors.

[0056] (3) The present invention uses the principle of like repulsion of permanent magnets to block mechanical contact, completely eliminating the hidden dangers of bearing plastic deformation, seizing or even burning caused by high-speed friction and heat generation, and removing the speed limit of traditional bearings, so that the motor can operate in the physical limit speed range determined by the strength of rotor material.

[0057] (4) The magnetic levitation bearing in this invention has the ability to adaptively adjust the clearance. When the motor rotates at high speed and generates a temperature rise, the rotor thermal expansion drives the inner ring of the L-shaped magnetic levitation rotor to move outward, synchronously compressing the radial and axial clearances. Thus, under the thermal expansion condition, it adaptively constructs a levitation steady state under the current working condition, realizing the adaptive adjustment of the clearance. When the motor stops rotating and cools down naturally to the ambient temperature, the inner ring of the L-shaped magnetic levitation rotor retracts in the opposite direction, and the radial and axial clearances automatically recover to the initial cold state design value. This ensures that the radial and axial clearances can be accurately and reversibly restored between the set clearance under the initial normal temperature state and the dynamic clearance under the high-speed thermal expansion condition as the rotor temperature changes, realizing the adaptive adjustment of the clearance throughout the motor start-stop cycle. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the overall assembly structure of the high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance in an embodiment of the present invention;

[0059] Figure 2 This is an exploded decomposition diagram of a high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance in an embodiment of the present invention.

[0060] Figure 3This is a schematic diagram of the axial cross-section and magnetic pole distribution of a high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance in an embodiment of the present invention.

[0061] Figure 4 This is a flowchart of the design method for a high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance in an embodiment of the present invention.

[0062] in:

[0063] 1. Motor rotor; 2. Inner ring of L-shaped magnetic levitation rotor; 3. Outer ring of L-shaped magnetic levitation stator; 4. High viscosity high temperature resistant colloid; 5. Radial suspension clearance; 6. Axial suspension clearance. Detailed Implementation

[0064] The present invention will be further described below with reference to the accompanying drawings:

[0065] like Figures 1-3 The high-speed motor magnetic levitation bearing shown is based on dynamic optimization of thermal-magnetic coupling clearance, comprising: a motor rotor and two sets of magnetic levitation bearing assemblies arranged in a mirror-symmetric manner at both ends of the motor rotor; the magnetic levitation bearing assembly includes an L-shaped magnetic levitation stator outer ring 3 disposed on the stator side of the motor and an L-shaped magnetic levitation rotor inner ring disposed on the rotor side of the motor; wherein, the L-shaped magnetic levitation stator outer ring 3 is fixed to the motor housing; the L-shaped magnetic levitation rotor inner ring 2 is bonded to the motor rotor 1 by a high-viscosity high-temperature resistant colloid 4 and rotates synchronously with the motor rotor 1; the L-shaped magnetic levitation stator outer ring 3 covers the outside of the L-shaped magnetic levitation rotor inner ring 2, and an initial magnetic levitation air gap (the initial magnetic levitation air gap refers to the set clearance under the initial room temperature state) is reserved between the two, the magnetic levitation air gap including radial magnetic levitation clearance 5 and axial magnetic levitation clearance 6. In this embodiment, the high-viscosity high-temperature resistant colloid is a high-temperature resistant colloid known in the art, such as high-temperature resistant epoxy resin structural adhesive, silicone resin adhesive, or anaerobic retaining adhesive.

[0066] This invention constructs a non-contact support structure consisting of an L-shaped permanent magnet outer ring and an L-shaped permanent magnet inner ring. To accommodate centrifugal loads under high-speed rotation, the L-shaped magnetic levitation rotor inner ring 2 does not employ a traditional interference fit. Instead, it is bonded and fixed to the shaft end of the motor rotor 1 using a layer of high-viscosity, high-temperature resistant colloid 4, allowing it to rotate synchronously with the motor rotor 1 without relative slippage. The L-shaped magnetic levitation stator outer ring 3 is rigidly fixed to the motor housing via mechanical fitting and covers the outer side of the L-shaped magnetic levitation rotor inner ring, with an initial magnetic levitation air gap reserved between them. Both the L-shaped magnetic levitation rotor inner ring and the L-shaped magnetic levitation stator outer ring are made of highly coercive sintered NdFeB permanent magnet material.

[0067] In this embodiment, the high-viscosity, high-temperature resistant colloid 4 not only serves a fixing function but also acts as a mechanical filter. The colloid layer has a specific elastic modulus, which can provide a small amount of radial stress release when the inner ring expands with the rotor, preventing the brittle permanent magnet material from cracking under drastic temperature changes. Furthermore, by adjusting the thermal conductivity of the colloid layer, the response speed of the inner ring to temperature sensing can be controlled, making the increase in magnetic repulsion and the increase in rotor speed more closely matched on a time scale, ensuring the smoothness of the suspension state transition.

[0068] The specific arrangement characteristics of the magnetic poles in the magnetic levitation bearing assembly are as follows:

[0069] The inner cylindrical surface of the outer ring of the L-shaped magnetic levitation stator has the same polarity as the outer cylindrical surface of the inner ring of the L-shaped magnetic levitation rotor (e.g., N pole), providing radial levitation force using the principle of like poles repulsion. At the same time, by using the vertical end face of the L-shaped structure, the corresponding vertical end face of the rotor inner ring and the stator outer ring is set to have the same polarity (e.g., N pole), generating an inward axial repulsive force. Combined with the opposite like polarity of the inner vertical end face of the left and right rotor inner rings (e.g., S pole), an outward axial repulsive force is generated, effectively preventing axial movement. Specifically, the inner cylindrical surface of the outer ring 3 of the L-shaped magnetic levitation stator and its corresponding axial end face, as well as the outer cylindrical surface of the inner ring 2 of the L-shaped magnetic levitation rotor and its corresponding axial end face, are all magnetized with a first polarity (such as the N pole), thereby generating a levitation support force in the radial direction and an axial compressive force pointing towards the geometric center of the motor in the axial direction; the inner vertical end face of the left L-shaped magnetic levitation rotor inner ring and the inner vertical end face of the right L-shaped magnetic levitation rotor inner ring are both magnetized with a second polarity (such as the S pole); the first polarity and the second polarity are opposite, and by using the inward axial compressive force generated by the first polarity and the outward axial expansion force generated by the second polarity, a composite magnetic levitation steady-state system of "external axial magnetic compression and internal axial magnetic expansion" is constructed.

[0070] The magnetic levitation bearing in this invention employs a clearance adaptive adjustment mechanism. When the motor rotates at high speed, causing the rotor temperature to rise, the rotor undergoes radial and axial thermal deformation. In the radial dimension, due to thermal expansion, the outer cylindrical surface of the rotor and the inner ring expands outward, compressing the radial clearance perpendicular to the axis, resulting in a nonlinear increase in the radial magnetic levitation repulsive force. In the axial dimension, the axial elongation of the rotor causes the inner ring to move to both sides, compressing the axial clearance parallel to the axis, resulting in a nonlinear increase in the axial constraint repulsive force. The simultaneous reduction of these two clearances leads to an enhancement of the magnetic levitation force, adaptively constructing a levitation steady state under the current operating conditions during thermal expansion, thus achieving adaptive clearance adjustment. After shutdown and cooling, the inner ring contracts and retracts with the rotor, driving the clearance to precisely reset to the initial design value. Through a bidirectional reversible cycle between hot and cold states, clearance adaptation is achieved throughout the entire life cycle of the motor.

[0071] This invention pertains to a passive magnetic levitation design, with its core being a thermal adaptive mechanism. Addressing the thermal expansion and contraction effects under high-speed rotation, the inner ring of the rotor is allowed to slightly shift outwards with the rotor's thermal expansion. Utilizing the physical property that the decrease in magnetic pole spacing leads to increased repulsive force, a new force balance is automatically established. The clearance is adaptively adjusted through the dynamic migration of the magnetic equilibrium point, avoiding the deformation and failure problems of traditional mechanical bearings caused by thermal expansion compressing the ball bearings. This improves the operational stability and service life of high-speed motors. The magnetic levitation bearing in this invention is suitable for ultra-high speed conditions, completely blocking the mechanical contact path between the outer and inner rings of the L-shaped magnetic levitation stator by utilizing the principle of like pole repulsion of permanent magnets. This invention eliminates the mechanical contact of traditional bearings, removes the speed limit limitation caused by frictional heating, and requires no lubricating medium, enabling the motor to operate stably within the physical speed limit region determined by the centrifugal strength of the rotor material.

[0072] The structural layout and magnetic circuit configuration process of the above-mentioned magnetic levitation bearing are as follows:

[0073] (1) Structural layout design

[0074] Mirror-symmetrical L-shaped magnetic levitation bearing assemblies are installed at both ends of the motor rotor. Each assembly consists of an L-shaped magnetic levitation stator outer ring end structure flange fixed to the housing, and an L-shaped magnetic levitation rotor inner ring fixed to the rotor shaft and rotating synchronously by a high-viscosity, high-temperature resistant colloid. The L-shaped magnetic levitation stator outer ring covers the outside of the L-shaped magnetic levitation rotor inner ring, with a magnetic levitation air gap reserved between them. Both the L-shaped magnetic levitation stator outer ring and the L-shaped magnetic levitation rotor inner ring are made of high-performance neodymium iron boron permanent magnet material.

[0075] (2) Radial levitation magnetic circuit configuration

[0076] The inner cylindrical surface of the outer ring of the L-shaped magnetic levitation stator and the outer cylindrical surface of the inner ring of the L-shaped magnetic levitation rotor are set to have the same magnetic pole polarity (e.g., N pole). Radial levitation force is generated by utilizing the principle of like poles repelling each other. The radial levitation force is perpendicular to the surface of the rotating shaft and is used to overcome the rotor's gravity and the centrifugal eccentric load generated by rotation, thus restricting the rotor's radial degree of freedom.

[0077] (3) Axial constraint magnetic circuit configuration

[0078] By utilizing the vertical end faces of an L-shaped structure for limiting movement, an innovative axial balance mechanism is constructed, involving external axial magnetic compression and internal axial magnetic expansion. On one hand, the vertical end faces of the outer ring of the L-shaped magnetic levitation stator and the corresponding vertical end faces of the inner ring of the L-shaped magnetic levitation rotor are set to have the same magnetic polarity (e.g., N pole). Utilizing the principle of like poles repulsion, an axial compressive force pointing towards the geometric center of the motor is generated at both ends of the rotor, forming an external axial constraint. On the other hand, the inner vertical end faces of the left and right L-shaped magnetic levitation rotor inner rings are set to have the same magnetic polarity (e.g., S pole). Utilizing the long-range like pole repulsion between the inner rings at both ends, an axial expansion force away from the motor center is generated, forming an internal axial tension. Through the interaction of the aforementioned axial compressive force pointing towards the motor's geometric center and the axial expansion force away from the motor center, non-contact levitation of the L-shaped bearing at a preset position is achieved.

[0079] like Figure 3 As shown in the cross-sectional force diagram, this invention, through a specific magnetization direction design, constructs a synergistic magnetic field in space, achieving stable levitation under external pressure and internal support:

[0080] (1) Radial levitation magnetic circuit

[0081] The inner cylindrical surface of the outer ring 3 of the L-shaped magnetic levitation stator and the outer cylindrical surface of the inner ring 2 of the L-shaped magnetic levitation rotor are set to have the same polarity (marked as N pole in the figure). Utilizing the principle of like poles repelling each other, a strong radial repulsive force perpendicular to the surface of the rotating shaft is generated. This force is used to overcome the rotor's gravity and the centrifugal eccentric load generated by high-speed rotation, achieving radial non-contact levitation.

[0082] (2) Single-sided axially constrained magnetic circuit

[0083] By utilizing the axial end face of the L-shaped structure, the vertical end face of the outer ring 3 of the L-shaped magnetic levitation stator and the vertical end face of the inner ring 2 of the L-shaped magnetic levitation rotor are set to the same polarity (marked as N pole in the figure). This generates an axial compressive force pointing towards the geometric center of the motor at both ends of the motor rotor, constituting the external boundary restriction of the rotor position.

[0084] (3) Double-end axial tensioning magnetic circuit

[0085] like Figure 3 As shown, the inner vertical end face of the left L-shaped magnetic levitation rotor and the inner vertical end face of the right L-shaped magnetic levitation rotor are set to have the same polarity (marked as S pole in the figure). Although the two ends are a certain distance apart, the repulsive force between like poles of the permanent magnets creates an axial expansion force away from the center of the motor inside the rotor.

[0086] With the above configuration, the rotor is stably locked at the balance point between the external axial compressive force and the internal axial expansion force, achieving stable suspension.

[0087] The working principle of the above-mentioned magnetic levitation bearing is as follows:

[0088] This embodiment utilizes the principle of thermal expansion and contraction to construct a reversible dynamic adjustment mechanism, effectively solving the problem of high-speed thermal failure. Under high-speed temperature rise conditions of the motor, the multi-dimensional thermal deformation of the rotor drives the inner ring 2 of the L-shaped magnetic levitation rotor to expand outward, simultaneously compressing the radial suspension air gap and the unilateral axial constraint air gap. Based on the nonlinear stiffness characteristics of magnetic field repulsion, the slight reduction in air gap automatically triggers a sharp increase in suspension force, thereby passively enhancing the constraint on the rotor while absorbing thermal expansion deformation, completely eliminating the hidden danger of mechanical seizure. When the motor stops to cool down, the rotor volume shrinks, driving the inner ring to retract in the opposite direction, so that the clearances in each dimension are automatically and accurately reset to the initial cold-state design value, ensuring the repeatability and long-term stability of the system throughout the entire cycle.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. The specific polarity and arrangement of the magnetic poles can be adjusted according to the actual motor structure (e.g., interchange the N / S poles) to enable its application in various high-speed rotating machinery.

[0090] like Figure 4 As shown, this invention provides a design method for high-speed motor magnetic levitation bearings based on dynamic optimization of thermal-magnetic coupling clearance. This method, based on an L-shaped inner and outer ring structure, includes the following thermal-magnetic coupling clearance dynamic optimization steps:

[0091] S1. Obtain basic parameters

[0092] Obtain the basic parameters of the high-speed motor rotor, including the rotor's basic physical dimensions, material linear expansion coefficient, and rated maximum operating temperature.

[0093] S2. Constructing a thermal expansion displacement model

[0094] A thermal expansion displacement model of the rotor is constructed at the rated maximum operating temperature, and the radial thermal expansion displacement and axial thermal expansion displacement transmitted to the inner ring of the L-shaped magnetic levitation rotor are calculated respectively.

[0095] S3. Construct a dynamic clearance compression model

[0096] A dynamic clearance compression model for an L-shaped magnetic levitation bearing is constructed. Based on the radial thermal expansion displacement and axial thermal expansion displacement, the actual radial clearance and actual axial clearance after synchronous compression due to the outward displacement of the inner ring under hot working conditions are calculated.

[0097] S4. Determine the magnetic equilibrium point.

[0098] An adaptive magnetic balance equation is established, and the magnetic balance point is determined using this equation. Based on the magnetic balance point, the installation positions of the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor are determined. Specifically, the objective function for optimization is to balance the dynamic disturbance force generated by the rotor under high-speed conditions caused by the surge in magnetic repulsion between the inner and outer rings of the L-shaped magnetic levitation stator due to clearance compression. The optimal initial installation radial clearance, axial clearance, and effective pole area of ​​the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor are solved in reverse to determine these parameters.

[0099] Furthermore, the thermal expansion displacement model is as follows:

[0100] ;

[0101] ;

[0102] in, This is the radial thermal expansion. This is the axial thermal expansion. The initial ambient temperature of the motor. The rated maximum operating temperature, is the coefficient of linear expansion of the rotor material. The effective radius of the rotor's heated area. This is the effective axial length.

[0103] Furthermore, the dynamic clearance compression model is as follows:

[0104] ;

[0105] ;

[0106] in, The initial radial clearance designed for the inner and outer rings of the L-shape. This is the initial axial clearance. This refers to the actual radial clearance under hot operating conditions. This represents the actual axial clearance under hot operating conditions.

[0107] Furthermore, step S4 specifically includes the following steps:

[0108] S41. Based on the repulsive property of like poles of permanent magnets, the thermal magnetic repulsion force generated between the inner and outer rings of the L-shaped magnetic levitation rotor is inversely proportional to the square of the actual clearance between them; taking the dynamic disturbance force of the surge in magnetic repulsion force under thermal conditions as the benchmark, establish the adaptive equations for radial and axial magnetic force balance.

[0109] The adaptive equation for radial magnetic force balance is:

[0110] ;

[0111] The adaptive equation for axial magnetic force balance is:

[0112] ;

[0113] in, The magnetic constant of the permanent magnet material; and These are the radial effective magnetic pole areas and axial effective magnetic pole areas of the inner ring of the L-shaped magnetic levitation rotor and the outer ring of the stator, respectively. and These are the actual radial clearance and actual axial clearance under hot operating conditions, respectively. and These represent the initial radial magnetic repulsion and the initial axial magnetic repulsion under cold, static conditions, respectively. and These are the radial centrifugal disturbance force and the axial aerodynamic disturbance force generated by the rotor under extreme thermal conditions, respectively.

[0114] S42. Perform magnetic steady-state optimization calculation, set the objective function for magnetic steady-state optimization, and make the radial magnetic repulsion increment under hot conditions... Greater than or equal to the radial centrifugal disturbance force And the axial magnetic repulsion increment Greater than or equal to the axial aerodynamic disturbance force That is, the following inequality conditions must be met:

[0115] ;

[0116] ;

[0117] in, , These are the initial radial clearances under cold, static conditions. and initial axial clearance The initial radial magnetic repulsion force and the initial axial magnetic repulsion force generated; , These represent the rotor under extreme hot conditions (corresponding to the estimated temperature rise). The radial centrifugal disturbance force and axial aerodynamic disturbance force generated at the highest speed (and the maximum speed); , These are respectively due to the clearance being compressed to [a certain value] under hot operating conditions. and The radial and axial magnetic repulsion forces, which surged respectively, are related to the actual clearance. and It is inversely proportional to the square of.

[0118] S43. Input different initial clearance combinations and iterate the adaptive equation for magnetic balance until the output satisfies the inequality conditions. and The parameter solution is obtained to determine the optimal initial installation radial clearance, axial clearance, and effective pole area of ​​the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor.

[0119] Furthermore, the magnetic steady-state optimization process also includes safety boundary constraints to prevent mechanical rubbing and magnetic pole failure;

[0120] The safety boundary constraints include:

[0121] During the iterative calculation process, the minimum safe assembly and operating clearance of the motor is preset to be... ; This is a hard threshold set during the optimization process.

[0122] To ensure the high reliability of the design parameters output by the algorithm in practical engineering, this section... Further explanation, The hard threshold set during the optimization process is usually taken as... ~ Depending on the machining accuracy, even at the highest temperature rise limit, the calculated actual clearance must be greater than the threshold to redundantly compensate for the unbalanced amplitude in rotor dynamics and the manufacturing tolerances of parts.

[0123] In any iteration step, the actual radial clearance under the aforementioned thermal condition must be satisfied. Compared with actual axial clearance Strictly greater than the minimum safe assembly and operating clearance, i.e.:

[0124] ;

[0125] ;

[0126] If the initial gap of the current iteration output and If the clearance under hot operating conditions does not satisfy the above inequality, then the effective magnetic pole area of ​​the inner ring of the L-shaped magnetic levitation rotor and the outer ring of the stator should be adjusted. and Alternatively, a higher-performance permanent magnet material could be selected to improve the magnetic constant. Then, it re-enters step S4 for optimization iteration.

[0127] Through iterative calculations, the surge in magnetic stiffness under extreme temperature rise conditions is ensured. This allows the system's natural frequency to be much higher than the motor's rotational frequency. This speed-dependent self-hardening characteristic enables the bearing to automatically adapt to changes in disturbance forces throughout the entire process from startup to ultra-high-speed operation, avoiding the complex electronic active control system of traditional magnetic levitation bearings and achieving an active adaptive effect of a passive structure.

[0128] In embodiments of this invention, the bearing design is no longer based on a single cold-state geometric clearance, but introduces a three-dimensional coupling of temperature, displacement, and magnetic force. When the high-speed motor rotor rotates at extreme speeds, the heat generated by its losses is conducted through the rotor matrix to the inner ring 2 of the L-shaped magnetic levitation rotor. Since the inner ring 2 of the L-shaped magnetic levitation rotor is made of high-performance neodymium iron boron material and fixed by a high-viscosity, high-temperature resistant colloid 4, its radial and axial displacement heights follow the linear thermal expansion law of the rotor. This invention utilizes materials science equations... Accurately predicting the thermal expansion displacement of the inner ring of an L-shaped magnetic levitation rotor at different speed stages can transform what was originally considered harmful thermal expansion into an actuator that actively adjusts magnetic stiffness. When the motor temperature rises... As the clearance increases, the radial suspension clearance 5 and the axial suspension clearance 6 decrease simultaneously. According to the physical property that magnetic repulsion is inversely proportional to the square of the clearance, the static load capacity and dynamic stiffness of the bearing will increase nonlinearly.

[0129] Furthermore, after outputting the optimal initial clearance that meets the conditions in step S4, the design method also includes performing a hot-state dynamic stiffness verification on the levitation steady state, specifically including:

[0130] S51. Calculate the thermal magnetic stiffness: radial magnetic repulsion. Regarding radial clearance Differentiate to obtain the thermal radial magnetic stiffness. ; Axial magnetic repulsion Regarding axial clearance Differentiate to obtain the hot axial magnetic stiffness. ;

[0131] S52. Calculate the critical frequency: considering the rotor mass. And rotational inertia, using the calculated thermal radial magnetic stiffness and thermal axial magnetic stiffness Calculate the critical resonant frequency of the rotor under the stated thermal limiting condition. ;

[0132] S53. Avoidance zone verification: Verify the critical resonance frequency. Check whether the excitation frequency range corresponding to the rated operating speed of the motor is avoided. If not, return to step S4 to readjust the initial clearance. and The combination ratio, or adjusting the effective area of ​​the magnetic poles. , Until the avoidance requirements are met.

[0133] To address the technical bias that existing rigid bearings are prone to seizing under high-speed temperature rise, this invention innovatively proposes a dynamic optimization algorithm for thermal-magnetic coupling clearance.

[0134] In traditional design, clearance This is typically considered a static constant. However, in this invention, considering the rotor heating effect of the high-speed motor, the L-shaped inner ring expands and displaces synchronously with the rotor. This invention transforms this thermal expansion displacement, traditionally considered harmful, into a favorable condition for enhancing magnetic stiffness.

[0135] Specifically, the magnetic repulsion generated between the inner and outer rings of the L-shape With gap It exhibits a highly nonlinear inverse proportional relationship. When the rotor temperature changes from... Rise to At that time, the clearance was compressed to and At this time, radial magnetic repulsion axial magnetic repulsion It will passively surge according to the following exponential pattern:

[0136] ;

[0137] ;

[0138] in, The magnetic constant of the permanent magnet material is... and These represent the effective opposing areas of the radial and axial directions of the L-shaped magnetic poles, respectively.

[0139] Due to the centrifugal disturbance caused by the unbalanced mass when the motor is running at high speed. It increases sharply with the square of the rotational speed. The core setting of this algorithm is that the initial clearance must be adjusted. and polar surface area This makes in The magnetic repulsion force increases due to thermal expansion. The centrifugal disturbance force is exactly greater than or equal to that at the limiting speed. ,Right now:

[0140] ;

[0141] Through the above algorithm iteration, the present invention achieves an adaptive dynamic constraint effect with large clearance and low resistance in the cold state (low speed) and small clearance and automatic hardening of magnetic stiffness in the hot state (high speed), fundamentally breaking through the speed bottleneck of traditional structures.

[0142] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-speed motor magnetic levitation bearing based on dynamic optimization of thermal-magnetic coupling clearance, characterized in that, include: Two sets of magnetic levitation bearing assemblies are set at both ends of the motor rotor (1) and are mirror-symmetrical; The magnetic levitation bearing assembly includes an L-shaped magnetic levitation stator outer ring (3) disposed on the stator side of the motor and an L-shaped magnetic levitation rotor inner ring (2) disposed on the rotor side of the motor (1). The L-shaped magnetic levitation stator outer ring (3) is fixed to the motor housing; the L-shaped magnetic levitation rotor inner ring (2) is bonded to the motor rotor (1) and rotates synchronously with the motor rotor (1); the L-shaped magnetic levitation stator outer ring (3) covers the outside of the L-shaped magnetic levitation rotor inner ring (2), and a magnetic levitation air gap is reserved between the two, the magnetic levitation air gap includes radial magnetic levitation clearance (5) and axial magnetic levitation clearance (6).

2. The high-speed motor magnetic levitation bearing according to claim 1, characterized in that, The inner cylindrical surface of the outer ring (3) of the L-shaped magnetic levitation stator and its corresponding axial end face, as well as the outer cylindrical surface of the inner ring (2) of the L-shaped magnetic levitation rotor and its corresponding axial end face, are all magnetized with the first polarity. The inner vertical end face of the inner ring (2) of the L-shaped magnetic levitation rotor on the left side of the motor rotor and the inner vertical end face of the inner ring (2) of the L-shaped magnetic levitation rotor on the right side of the motor rotor are both magnetized to the second polarity. The first polarity is opposite to the second polarity.

3. The high-speed motor magnetic levitation bearing according to claim 1, characterized in that, The inner ring (2) of the L-shaped magnetic levitation rotor is bonded to the motor rotor (1) by a colloid (4).

4. A design method for high-speed motor magnetic levitation bearings based on dynamic optimization of thermal-magnetic coupling clearance, characterized in that, The method includes: S1. Obtain the basic parameters of the motor rotor; S2. Construct a thermal expansion displacement model of the rotor at the rated maximum operating temperature, and calculate the radial thermal expansion displacement and axial thermal expansion displacement of the rotor as it expands due to heat and is transmitted to the inner ring of the L-shaped magnetic levitation rotor. S3. Construct a dynamic clearance compression model for the magnetic levitation bearing. Based on the radial thermal expansion displacement and the axial thermal expansion displacement, calculate the actual radial clearance and actual axial clearance between the outer ring and the inner ring of the bearing under thermal conditions. S4. Establish the adaptive equation for magnetic balance, and determine the optimal initial installation radial clearance, axial clearance and effective area of ​​magnetic poles for the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor, with the dynamic disturbance force of magnetic repulsion balance under hot working conditions as the target.

5. The design method according to claim 4, characterized in that, The thermal expansion displacement model is as follows: ； ； in, This is the radial thermal expansion. This is the axial thermal expansion. The initial ambient temperature of the motor. The rated maximum operating temperature, is the coefficient of linear expansion of the rotor material. The effective radius of the rotor's heated area. This is the effective axial length.

6. The design method according to claim 4, characterized in that, The dynamic clearance compression model is as follows: ； ； in, The initial radial clearance designed for the inner and outer rings of the L-shape. This is the initial axial clearance. This refers to the actual radial clearance under hot operating conditions. This represents the actual axial clearance under hot operating conditions.

7. The design method according to claim 4, characterized in that, Step S4 specifically includes the following steps: S41. Based on the repulsive property of like poles of permanent magnets, the thermal magnetic repulsion force generated between the inner and outer rings of the L-shaped magnetic levitation rotor is inversely proportional to the square of the actual clearance between them; taking the dynamic disturbance force of the surge in magnetic repulsion force under thermal conditions as the benchmark, establish the adaptive equations for radial and axial magnetic force balance. The adaptive equation for radial magnetic force balance is: ； The adaptive equation for axial magnetic force balance is: ； in, The magnetic constant of the permanent magnet material; and These are the radial effective magnetic pole areas and axial effective magnetic pole areas of the inner ring of the L-shaped magnetic levitation rotor and the outer ring of the stator, respectively. and These are the actual radial clearance and actual axial clearance under hot operating conditions, respectively. and These represent the initial radial magnetic repulsion and the initial axial magnetic repulsion under cold, static conditions, respectively. and These are the radial centrifugal disturbance force and the axial aerodynamic disturbance force generated by the rotor under extreme thermal conditions, respectively. S42. Perform magnetic steady-state optimization calculation, set the objective function for magnetic steady-state optimization, and make the radial magnetic repulsion increment under hot conditions... Greater than or equal to the radial centrifugal disturbance force And the axial magnetic repulsion increment Greater than or equal to the axial aerodynamic disturbance force That is, the following inequality conditions must be met: ； ； in, , These are the initial radial clearances under cold, static conditions. and initial axial clearance The initial radial magnetic repulsion force and the initial axial magnetic repulsion force generated; , These are the radial centrifugal disturbance force and the axial aerodynamic disturbance force generated by the rotor under extreme thermal conditions, respectively. , These are respectively due to the clearance being compressed to [a certain value] under hot operating conditions. and The radial and axial magnetic repulsion forces, which surged respectively, are related to the actual clearance. and It is inversely proportional to the square of ; S43. Input different initial clearance combinations and iterate the adaptive equation for magnetic balance until the output satisfies the inequality conditions. and The parameter solution is obtained to determine the optimal initial installation radial clearance, axial clearance, and effective pole area of ​​the outer ring of the L-shaped magnetic levitation stator and the inner ring of the L-shaped magnetic levitation rotor.

8. The design method according to claim 7, characterized in that, The magnetic steady-state optimization process also includes safety boundary constraints to prevent mechanical wear and magnetic pole failure. The safety boundary constraints include: During the iterative calculation process, the minimum safe assembly and operating clearance of the motor is preset to be... ; A hard threshold set during the optimization process; In any iteration step, the actual radial clearance under the aforementioned thermal condition is satisfied. Compared with actual axial clearance Greater than the minimum safe assembly and operating clearance, i.e.: ； ； If the initial gap of the current iteration output and If the clearance under hot operating conditions does not satisfy the above inequality, then the effective magnetic pole area of ​​the inner ring of the L-shaped magnetic levitation rotor and the outer ring of the stator should be adjusted. and Alternatively, a higher-performance permanent magnet material could be selected to improve the magnetic constant. Then, it re-enters step S4 for optimization iteration.

9. The design method according to claim 4, characterized in that, After outputting the optimal initial clearance that meets the conditions in step S4, the design method further includes performing a hot-state dynamic stiffness check on the levitation steady state, specifically including: S51. Calculate the thermal magnetic stiffness: radial magnetic repulsion. Regarding radial clearance Differentiate to obtain the thermal radial magnetic stiffness. ; Axial magnetic repulsion Regarding axial clearance Differentiate to obtain the hot axial magnetic stiffness. ; S52. Calculate the critical frequency: considering the rotor mass. And rotational inertia, using the calculated thermal radial magnetic stiffness and thermal axial magnetic stiffness Calculate the critical resonant frequency of the rotor under the stated thermal limiting condition. ; S53. Avoidance zone verification: Verify the critical resonance frequency. Check whether the excitation frequency range corresponding to the rated operating speed of the motor is avoided. If not, return to step S4 to readjust the initial clearance. and The combination ratio, or adjusting the effective area of ​​the magnetic poles. , Until the avoidance requirements are met.

10. The design method according to claim 4, characterized in that, The rotor parameters include: basic physical dimensions, mass, moment of inertia, rated operating speed of the motor, coefficient of linear expansion of the material, and rated maximum operating temperature.

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