A method for evaluating the force of auxiliary bearing rub during a drop process of an electromagnetic bearing rotor

Abstract

The application relates to a method for evaluating the force of auxiliary bearing collision in the process of electromagnetic bearing rotor falling, and relates to the technical field of electromagnetic bearing force evaluation. The method is used for solving the problem that the existing technology is difficult to accurately evaluate the force of the auxiliary bearing due to the randomness of the collision state of the rotor and the auxiliary bearing at each moment of rotor falling, the high coupling nonlinearity of the motion process. The method comprises the following steps: S1, collecting the motion data of each degree of freedom at each moment in the process of rotor falling through a sensor; S2, judging whether collision occurs or not, and constructing a motion state equation of the rotor; S3, constructing a resultant force and a resultant moment equation of the rotor; S4, classifying the collision according to the number of collision points, decoupling the dynamic equation to obtain the collision force of the auxiliary bearing; and S5, storing the force data. The method is helpful for the design and engineering application of the auxiliary bearing, and has important reference significance for the further research on the force state of the rotor and the auxiliary bearing in the process of rotor falling.

Description

A method for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor. Technical Field

[0001] This invention relates to the field of electromagnetic bearing stress assessment technology, and more specifically, to a method for assessing the rubbing stress of an auxiliary bearing during the drop of an electromagnetic bearing rotor. Background Technology

[0002] The electromagnetic bearing system is a typical mechatronics system, mainly composed of sensors, controllers, power amplifiers, magnetic bearings, and rotors, as shown in Figure 2. The main workflow is as follows: sensors (such as current sensors and rotor displacement sensors) transmit coil current and rotor position changes to the controller in real time. The controller then uses the power amplifier to generate a control current, which alters the electromagnetic force, causing the rotor to levitate.

[0003] However, electromagnetic bearings are limited by nonlinear characteristics such as magnetic saturation and lack overload resistance. Therefore, auxiliary bearings are necessary to withstand rotor drops in potential accidental operating conditions. The auxiliary bearing provides temporary support for the rotor and bears some overload, acting as a rotor limiter. When the electromagnetic bearing is working normally, the rotor is in a stable suspended state, and the auxiliary bearing is in standby mode. When the electromagnetic bearing fails, the rotor loses support and falls, rubbing against the auxiliary bearing, which then becomes operational.

[0004] The strong nonlinear effects of rubbing cause the rotor to exhibit complex nonlinear dynamic behavior, which can lead to rapid bearing degradation or even damage, seriously affecting system safety. The force characteristics of the auxiliary bearing during rotor drop determine the reliability of the system in the event of electromagnetic bearing failure, and are a key consideration for the applicability of electromagnetic bearings. Force analysis of the auxiliary bearing during the rotor drop process is an important part of the design and application of electromagnetic bearings.

[0005] Due to the constraints of the compact structure and high-speed rotor operation, it is difficult to install force sensors on the inner rings of the rotor and auxiliary bearing. Furthermore, the rotor drop process exhibits highly nonlinear characteristics, with strong coupling relationships between the rotor's various degrees of freedom. At each moment of the rotor drop, the collision state between the rotor and auxiliary bearing has a degree of randomness, making the interaction between them difficult to assess and thus hindering the determination of the true stress state of the auxiliary bearing. Moreover, due to the system's complex mechanical structure and stress conditions, it is currently difficult to establish an accurate and appropriate model to simulate the real-world rotor drop process. Summary of the Invention

[0006] The technical problem to be solved by this invention is:

[0007] Existing technologies struggle to accurately assess the forces acting on the auxiliary bearings due to the randomness of the rotor's collision state with the auxiliary bearing at various moments during rotor drop and the highly coupled nonlinearity of the motion process.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0009] This invention provides a method for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor. The method, used for evaluating the rubbing force of an auxiliary bearing during the drop of a vertical electromagnetic bearing rotor, includes the following steps:

[0010] S1. Collect motion data of each degree of freedom at each moment during the rotor's fall process using sensors;

[0011] S2. Determine whether a collision has occurred and construct the motion state equations of the rotor, including the momentum and angular momentum equations of the rotor center and the impulse and angular impulse equations of the rotor center.

[0012] S3. Construct the equations for the resultant force and resultant moment acting on the rotor;

[0013] S4. Classify the collisions between the rotor and the auxiliary bearing according to the number of collision points, decouple the dynamic equations for different collision types, and obtain the rubbing force of the auxiliary bearing.

[0014] S5, Stores the rubbing force data of the auxiliary shaft.

[0015] Furthermore, the sensor described in S1 is a non-contact displacement sensor to collect displacement signal data of each degree of freedom of the rotor at each moment.

[0016] Furthermore, in S2, the distance between the rotor's drop trajectory and the constraint surface is used to determine whether a collision has occurred.

[0017] Furthermore, the equations for the momentum P and angular momentum H at the rotor center in S2 are as follows:

[0018]

[0019] Where x, y, and z represent the displacements of the rotor along the principal axes of a spatial rectangular coordinate system, respectively; This represents the rotation angle of the rotor about the x-axis, which is the angle between the rotor axis and the xz plane; This represents the angle of rotation of the rotor around the y-axis, which is the angle between the rotor axis and the yz plane; Indicates rotor speed; I T I p These are the rotor's equatorial moment of inertia and polar moment of inertia, respectively, and m is the rotor's mass;

[0020] The equations for the impulse and impulse moment at the rotor center are as follows:

[0021]

[0022] Among them, F x F y and F z M represents the resultant force acting on the rotor in the x, y, and z directions. x M y and M z This represents the resultant torque acting on the rotor in the x, y, and z directions; This indicates the time interval.

[0023] Furthermore, the equations for the resultant force and resultant torque acting on the rotor as described in S3 are:

[0024]

[0025] Furthermore, S4 includes the following process:

[0026] When the rotor collides radially with the upper and lower auxiliary bearings, the equations for the resultant force and resultant torque of the upper auxiliary bearing are as follows:

[0027]

[0028]

[0029]

[0030] The equations for the resultant force and resultant moment of the lower auxiliary bearing are as follows:

[0031]

[0032]

[0033]

[0034] Where R represents the inner ring radius of the auxiliary bearing, F n With F t These represent the normal and tangential components of the force, respectively. Subscripts 1 and 2 represent the upper and lower auxiliary bearings, respectively. and These are the argument angles of the upper and lower auxiliary bearing contact points, respectively, which can be calculated from the rotor displacement signal. b1 and b2 represent the upper and lower auxiliary bearings, respectively. b1 l b2These represent the axial distances from the geometric center of the upper and lower auxiliary bearings to the geometric center of the rotor, respectively.

[0035] Considering the rotor's tilt along its own axis of rotation during the drop, the contact angle is assumed to change; if tilting occurs, there is point contact in the axial direction, and the axial contact angle... The equations for the resultant force and resultant moment of the upper auxiliary bearing are as follows:

[0036]

[0037]

[0038] The collision with the lower auxiliary bearing is still a radial collision, and the equations for the resultant force and resultant moment are as follows:

[0039]

[0040]

[0041] The x, y, and z directions of the rotor trajectory are analyzed to determine the number of collision points. Based on the number of collision points, the collisions between the rotor and the auxiliary bearing are classified. The rotor force equations are decoupled for different collision types, and the resultant torque equation is used for verification. Specific collision types are as follows:

[0042] Single-point collision: The upper and lower auxiliary bearings collide with the rotor at only one point; solve for the resultant force equation.

[0043] Two-point collision: The upper and lower auxiliary bearings collide with the rotor at a single point; or the upper auxiliary bearing has two collision points with the rotor, while the lower auxiliary bearing has no contact with the rotor. Since this situation is rare, it is not considered.

[0044] Three-point collision: The upper auxiliary bearing collides with the rotor at two points, and the lower auxiliary bearing collides with the rotor at one point. The coordinates of the two points of the upper auxiliary bearing are fitted to a single point, and then the calculation is performed according to the case that the rotor collides radially with both the upper and lower auxiliary bearings.

[0045] Surface collision: The upper auxiliary bearing makes surface contact with the rotor axial flange, while the lower auxiliary bearing either has a single-point collision with the rotor or no contact. For the equations to be well-determined and solvable, it is assumed that the axial collision force acts on the rotor shaft, and the radial collision forces of the upper and lower auxiliary bearings are equal in the normal direction. The vertical frictional force on the radial contact surface is neglected. The equations for the resultant force and resultant moment are:

[0046] Furthermore, the sampling frequency of the sensor in S1 is such that at least two samples are taken between each successive collision.

[0047] A system for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor, the system having a program module corresponding to the steps of any of the above technical solutions, and executing the steps in the above-described method for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor.

[0048] A computer-readable storage medium storing a computer program configured to, when invoked by a processor, implement the steps of the method for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor, as described in any of the above technical solutions.

[0049] Compared with the prior art, the beneficial effects of the present invention are:

[0050] This invention discloses a method for evaluating the rubbing force of auxiliary bearings during the drop test of an electromagnetic bearing rotor. It accurately collects the rotor's motion trajectory data at various moments using displacement sensors, and analyzes the resultant force on the rotor by constructing the rotor's motion state equation. This invention addresses the interaction between the rotor and the upper and lower auxiliary bearings, decomposing the resultant force on the rotor into forces on the upper and lower auxiliary bearings. Furthermore, it summarizes and analyzes collision types, decoupling the dynamic equations based on different collision types to assess the actual force on the rotor and auxiliary bearings. This invention enables real-time online calculation and detection of the rubbing force between the rotor and auxiliary bearings during a drop test, which is helpful for the design and engineering application of auxiliary bearings and provides important reference value for further research on the force state of the rotor and auxiliary bearings during a rotor drop test. Attached Figure Description

[0051] Figure 1 is a flowchart of a method for evaluating the rubbing force of an auxiliary bearing during the fall of an electromagnetic bearing rotor according to an embodiment of the present invention.

[0052] Figure 2 is a simplified schematic diagram of the electromagnetic bearing system in the background art of this invention;

[0053] Figure 3 is a simplified schematic diagram of the experimental platform in an embodiment of the present invention;

[0054] Figure 4 is a schematic diagram of the left-hand transformation of the rectangular coordinate system xyz fixed in space and the rectangular coordinate system x'y'z' rotating with the rotor in an embodiment of the present invention.

[0055] Figure 5 is a schematic diagram of the rotor motion state in an embodiment of the present invention;

[0056] Figure 6 is a schematic diagram of the collision types between the rotor and the auxiliary bearing in an embodiment of the present invention;

[0057] Figure 7 is a schematic diagram of the radial collision between the rotor and the auxiliary bearing in an embodiment of the present invention;

[0058] Figure 8 is a diagram of the rotor shaft center trajectory on the upper end face in an embodiment of the present invention;

[0059] Figure 9 is a diagram of the rotor shaft center trajectory on the lower end face in an embodiment of the present invention;

[0060] Figure 10 is a collision force diagram in the x-direction of an embodiment of the present invention;

[0061] Figure 11 is a collision force diagram in the y-direction of an embodiment of the present invention;

[0062] Figure 12 is a collision force diagram in the z-direction of an embodiment of the present invention;

[0063] Figure 13 shows the radial force on the upper auxiliary bearing in an embodiment of the present invention;

[0064] Figure 14 shows the tangential force on the upper auxiliary bearing in an embodiment of the present invention;

[0065] Figure 15 shows the radial force on the lower auxiliary bearing in an embodiment of the present invention;

[0066] Figure 16 shows the tangential force on the lower auxiliary bearing in an embodiment of the present invention. Detailed Implementation

[0067] In the description of this invention, it should be noted that the terms "first," "second," and "third" mentioned in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0068] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0069] Referring to Figures 1 to 7, the present invention provides a method for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor, comprising the following steps:

[0070] S1. Collect motion data of each degree of freedom at each moment during the rotor's fall process using sensors;

[0071] S2. Determine whether a collision has occurred and construct the motion state equations of the rotor, including the momentum and angular momentum equations of the rotor center and the impulse and angular impulse equations of the rotor center.

[0072] S3. Construct the equations for the resultant force and resultant moment acting on the rotor;

[0073] S4. Classify the collisions between the rotor and the auxiliary bearing according to the number of collision points, decouple the dynamic equations for different collision types, and obtain the rubbing force of the auxiliary bearing.

[0074] S5, Stores the rubbing force data of the auxiliary shaft.

[0075] For the electromagnetic bearing-rotor system, the rotor's axial displacement, radial displacement, and rotation are all controlled by the electromagnetic bearings, with the axial rotation driven by a motor. The axial thrust electromagnetic bearing bears the entire weight of the rotor, while the upper and lower pairs of radial electromagnetic bearings bear the rotor's radial load and actively control the rotor's attitude. The established model accurately simulates the rotor drop process under real-world conditions. The sensor and auxiliary bearing arrangement in the experimental setup is shown in Figure 3. The rotor is vertically arranged, with the auxiliary bearings and displacement sensors positioned at the upper and lower ends of the rotor, respectively. The total span of the sensors on the experimental setup is the same in both the x and y directions, with two displacement sensors positioned at each end of the rotor. The motion trajectory data of each degree of freedom of the rotor is obtained through the sensors, and the axial trajectory of the rotor at each moment of the drop can be obtained through data post-processing.

[0076] As shown in Figure 3, the relationship between the sensor signal and the rotor center degree of freedom can be expressed by the following equation:

[0077]

[0078] Where x, y, and z represent the displacements of the rotor along the principal axes of a Cartesian coordinate system. This represents the rotation angle of the rotor about the x-axis, which is the angle between the rotor axis and the xz plane; This represents the angle of rotation of the rotor around the y-axis, which is the angle between the rotor axis and the yz plane. The value indicates the rotor speed; the subscript 's' indicates the sensor; subscripts '1' and '2' indicate the upper and lower displacement sensors, respectively; and 'l' indicates the rotor speed. s1 l s2 These represent the axial distances from the geometric centers of the upper and lower displacement sensors to the geometric center of the rotor, respectively. The mathematical relationships between the rotor's degrees of freedom at the auxiliary bearing section and the sections of the upper and lower sensors are as follows:

[0079]

[0080] Where b1 and b2 represent the upper and lower auxiliary bearings respectively, l b1 l b2 These represent the axial distances from the geometric center of the upper and lower auxiliary bearings to the geometric center of the rotor, respectively.

[0081] To facilitate the analysis of the rotor's drop posture, a Cartesian coordinate system xyz fixed in space and a Cartesian coordinate system x'y'z' rotating with the rotor are established, as shown in Figure 4. In this embodiment, it is assumed that the rotor's angle and displacement in the vertical direction are both small. The coordinate system x'y'z' can be obtained through the following transformations:

[0082] 1) Establish a rectangular coordinate system xyz and rotate it around the y-axis. angle;

[0083] 2) Rotation around the x' axis angle.

[0084] The mathematical relationships involved in the coordinate transformation process are as follows:

[0085]

[0086] Among them, angle and It can be considered a small quantity, therefore the transformation matrix R is approximately as follows:

[0087]

[0088] Therefore, the relationship between the rectangular coordinate systems xyz and x'y'z' can be expressed as:

[0089]

[0090] in,

[0091]

[0092] Based on the coordinate system established above, the rotor motion state can be represented by Figure 5:

[0093] The rotor angular momentum is shown below:

[0094]

[0095] Among them, I T I p These are the equatorial moment of inertia and the polar moment of inertia of the rotor, respectively. x w y w z The rotational speeds of the rotor around the x, y, and z axes are given.

[0096] The distance between the rotor's drop trajectory and the constraint surface determines whether a collision has occurred. If the distance between the rotor's shaft trajectory and the constraint surface is less than a preset value, then contact is determined to have occurred.

[0097] The equations for the momentum P and angular momentum H at the rotor center are as follows:

[0098]

[0099] Where x, y, and z represent the displacements of the rotor along the principal axes of a spatial rectangular coordinate system, respectively; This represents the rotation angle of the rotor about the x-axis, which is the angle between the rotor axis and the xz plane; This represents the angle of rotation of the rotor around the y-axis, which is the angle between the rotor axis and the yz plane; Indicates rotor speed; I T I p These are the rotor's equatorial moment of inertia and polar moment of inertia, respectively, and m is the rotor's mass;

[0100] The equations for the rotor's impulse and impulse moment are constructed as follows:

[0101]

[0102] Among them, F x F y and F z M represents the resultant force acting on the rotor in the x, y, and z directions. x M y and M z This represents the resultant torque acting on the rotor in the x, y, and z directions; This indicates the time interval.

[0103] Based on the above analysis, the rotor can be obtained. Impulse and impulse moment within a time interval, where the time interval is... The sampling frequency can be selected. At this point, the impact of the rotor falling can be analyzed.

[0104] The impulse and impulse moment experienced by the rotor center need to be decomposed into the impulse and impulse moment at each collision point. The actual stress conditions at the stress points have a significant impact on the dynamic characteristics of the auxiliary bearing. Determining and analyzing the location of the collision points is a prerequisite for the stress on the auxiliary bearing.

[0105] When the rotor falls, the axially lower surface of the rotor flange will contact the axially upper surface of the upper auxiliary bearing. Conversely, when the rotor bounces upwards due to the impact force, it may contact the axially lower surface of the upper auxiliary bearing. Furthermore, the rotor will experience multiple radial rubbing and bouncing interactions with the inner rings of the upper and lower auxiliary bearings. The collision patterns between the rotor and the auxiliary bearings are quite complex. To avoid introducing ill-posed problems during equation solving, we preliminarily classify the collision situations between the rotor and the auxiliary bearings based on the number of collision points, and then solve the equations accordingly for different collision types. As shown in Figure 6, the collision types between the rotor and the auxiliary bearings can be summarized as: single-point collision, two-point collision, three-point collision, and surface collision.

[0106] The equations for the resultant force and resultant moment acting on the rotor are as follows:

[0107]

[0108] When the rotor collides radially with the upper and lower auxiliary bearings, their interaction is shown in Figure 7. The contact point angle in Figure 7 is... , It can be calculated from the rotor displacement signal.

[0109] When the rotor collides radially with the upper and lower auxiliary bearings, the equations for the resultant force and resultant torque of the upper auxiliary bearing are as follows:

[0110]

[0111]

[0112]

[0113] The equations for the resultant force and resultant moment of the lower auxiliary bearing are as follows:

[0114]

[0115]

[0116]

[0117] Where R represents the inner ring radius of the auxiliary bearing, F n With F t These represent the normal and tangential components of the force, respectively. Subscripts 1 and 2 represent the upper and lower auxiliary bearings, respectively. and These are the argument angles of the upper and lower auxiliary bearing contact points, respectively, which can be calculated from the rotor displacement signal. b1 and b2 represent the upper and lower auxiliary bearings, respectively. b1 l b2 These represent the axial distances from the geometric center of the upper and lower auxiliary bearings to the geometric center of the rotor, respectively.

[0118] Considering the rotor's tilt along its own axis of rotation during the drop, the contact angle is assumed to change; if tilting occurs, there is point contact in the axial direction, and the axial contact angle... The equations for the resultant force and resultant moment of the upper auxiliary bearing are as follows:

[0119]

[0120]

[0121] The collision with the lower auxiliary bearing is still a radial collision, and the equations for the resultant force and resultant moment are as follows:

[0122]

[0123]

[0124] We now need to decouple the equations according to different collision types in order to analyze the force situation of the auxiliary bearing.

[0125] For a single-point collision, it is only necessary to solve the resultant force equation, and use the resultant moment equation as verification. If the single-point collision occurs at the upper auxiliary bearing, then the solution is as follows:

[0126]

[0127] And verify the equation:

[0128]

[0129] If the single-point collision occurs at the lower auxiliary bearing, then solve:

[0130]

[0131] And verify the equation:

[0132]

[0133] For a two-point collision, the upper and lower auxiliary bearings each collide with the rotor at a single point; or the upper auxiliary bearing has two collision points with the rotor, while the lower auxiliary bearing has no contact with the rotor. Since this situation is rare, it is not considered. The equations for the resultant force and resultant moment are:

[0134]

[0135] It can be rewritten in matrix form as follows, and this equation is well-posed and solvable:

[0136]

[0137] in,

[0138]

[0139] ,

[0140] Three-point collisions are relatively rare. As shown in Figure 6, for the first scenario, it can be calculated as if the rotor were colliding radially with both the upper and lower auxiliary bearings. This means assuming the two-point collision with the upper auxiliary bearing is a single-point collision and fitting the coordinates of the two points to a single point. The second scenario is highly unlikely and will not be considered.

[0141] For surface collisions and multi-point contact types, the upper auxiliary bearing has surface contact with the rotor axial flange, while the lower auxiliary bearing may have single-point collisions or no contact with the rotor. To ensure the equations are well-determined and solvable, it is assumed that the axial collision force acts on the rotor shaft, and the radial collision forces of the upper and lower auxiliary bearings are equal in the normal direction. Neglecting the vertical frictional force on the radial contact surface, it is necessary to solve the resultant force and resultant moment equations simultaneously. The resultant force and resultant moment equations are as follows:

[0142]

[0143] in, For axial collision force, F a =K*dz+C, where k is the contact stiffness and C is the contact damping;

[0144] When the contact between the rotor and the auxiliary bearing is a combination of surface contact and two-point contact, it is necessary to assume that the axial impact force acts on the rotor shaft, and the radial impact forces of the upper and lower auxiliary bearings are equal to the normal forces. In this case, the vertical frictional force on the radial contact surface needs to be ignored. The above equations can be solved based on this assumption.

[0145] The sensor's sampling frequency is such that it samples at least twice between each successive collision.

[0146] The sampling frequency of the sensor has a significant impact on determining the contact between the rotor and the auxiliary bearing. If the sampling frequency is high enough, it is only necessary to estimate whether the distance between the rotor shaft center trajectory and the constraint surface is less than a preset value to determine if a collision has occurred. However, if the sampling frequency is too low, multiple collisions may occur within a single sampling period, making it impossible to accurately estimate the actual collision situation between the rotor and the auxiliary bearing. Therefore, at least two sampling points are required between each consecutive collision.

[0147] Example 1

[0148] The method of this invention is used to evaluate the rubbing force of the auxiliary bearing during the drop process of an electromagnetic bearing rotor.

[0149] The rotor was dropped onto the mechanical auxiliary bearing at an initial speed of 5000 r / min. Experimental data within 0.2 s after the rotor's drop were analyzed. Figures 8 and 9 show the raw data measured by the displacement sensors. Due to the axial and radial impacts on the upper part of the rotor, the signal changes detected by the upper sensor were more drastic, while the signal fluctuations of the lower sensor were relatively minor.

[0150] Using the method of this invention, the axis trajectory signals at the upper and lower ends of the rotor are processed to obtain the resultant forces acting on the rotor in the x, y, and z directions, as shown in Figures 10, 11, and 12. In the figures, a negative force indicates that the force direction is opposite to the initial direction, and the collision point between the rotor and the auxiliary bearing is opposite to the initial direction.

[0151] Using the method of this invention, the force calculation results of the auxiliary bearings are shown below according to different collision types. The radial and tangential forces of the upper auxiliary bearing are shown in Figures 13 and 14; the radial and tangential forces of the lower auxiliary bearing are shown in Figures 15 and 16.

[0152] Data analysis results show that the upper auxiliary bearing bears the axial impact and most of the radial impact; meanwhile, the lower auxiliary bearing bears only a small amount of radial impact. The upper auxiliary bearing plays a crucial role in supporting the rotor during a rotor drop. It is necessary to focus on the stress condition of the upper auxiliary bearing, determine whether it can withstand the impact of the falling rotor, and whether replacement is necessary to ensure its safe use and thus guarantee the overall safety of the system.

[0153] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the frictional force of an auxiliary bearing during the drop of an electromagnetic bearing rotor, characterized in that, The method described is used to assess the rubbing force of the auxiliary bearing during the drop process of a vertical electromagnetic bearing rotor, and includes the following steps: S1, collecting motion data of each moment and degree of freedom of the rotor during the drop process using sensors; S2, determining whether a collision has occurred, and constructing the motion state equation of the rotor, including the momentum and angular momentum equations of the rotor center, and the impulse and angular impulse equations of the rotor center; S3, constructing the equations of the resultant force and resultant torque acting on the rotor; S4, classifying the collisions between the rotor and the auxiliary bearing according to the number of collision points, and decoupling the dynamic equations for different collision types to obtain the rubbing force of the auxiliary bearing; S5, storing the rubbing force data of the auxiliary shaft; S4 includes the following process: when the rotor collides radially with the upper and lower auxiliary bearings, the equations of the resultant force and resultant torque of the upper auxiliary bearing are: The equations for the resultant force and resultant moment of the lower auxiliary bearing are as follows: Where R represents the inner ring radius of the auxiliary bearing, F n With F t These represent the normal and tangential components of the force, respectively. Subscripts 1 and 2 represent the upper and lower auxiliary bearings, respectively. and These are the argument angles of the upper and lower auxiliary bearing contact points, respectively, which can be calculated from the rotor displacement signal. b1 and b2 represent the upper and lower auxiliary bearings, respectively. b1 l b2 F represents the axial distance from the geometric center of the upper and lower auxiliary bearings to the geometric center of the rotor, respectively. x F y and F z M represents the resultant force acting on the rotor in the x, y, and z directions. x M y and M z This represents the resultant torque acting on the rotor in the x, y, and z directions; considering the rotor's tilt along its own axis of rotation during the fall, the contact angle is assumed to change; if tilting occurs, there is point contact in the axial direction, and the axial contact angle is... The equations for the resultant force and resultant moment of the upper auxiliary bearing are as follows: The collision with the lower auxiliary bearing is still a radial collision, and the equations for the resultant force and resultant moment are as follows: The x, y, and z directions of the rotor trajectory are analyzed to determine the number of collision points. Based on the number of collision points, the collisions between the rotor and auxiliary bearings are classified. The rotor force equations are decoupled for different collision types, and the resultant torque equation is used for verification. Specific collision types are: single-point collision: the upper and lower auxiliary bearings collide with the rotor at only one point; the resultant force equation is solved. Two-point collision: the upper and lower auxiliary bearings each collide with the rotor at a single point; or the upper auxiliary bearing has two collision points with the rotor, while the lower auxiliary bearing has no contact with the rotor. Since this situation is less common, therefore... The following collision scenarios are not considered: Three-point collision: The upper auxiliary bearing collides with the rotor at two points, and the lower auxiliary bearing collides with the rotor at a single point. The coordinates of the two points of the upper auxiliary bearing are fitted to a single point, and then the calculation is performed according to the case that the rotor collides radially with both the upper and lower auxiliary bearings; Surface collision: The upper auxiliary bearing makes surface contact with the rotor axial flange, and the lower auxiliary bearing either collides at a single point with the rotor or has no contact; In order for the equations to be well-determined and solvable, it is assumed that the axial collision force acts on the rotor shaft, and the radial collision forces of the upper and lower auxiliary bearings are equal in the normal direction. The vertical friction force on the radial contact surface is ignored.

2. The method for evaluating the rubbing force of the auxiliary bearing during the drop process of an electromagnetic bearing rotor, as described in claim 1, is characterized in that... The sensor described in S1 is a non-contact displacement sensor, used to collect displacement signal data of each degree of freedom of the rotor at each moment.

3. The method for evaluating the rubbing force of the auxiliary bearing during the drop process of an electromagnetic bearing rotor, as described in claim 1, is characterized in that... In S2, the distance between the rotor's drop trajectory and the constraint surface is used to determine whether a collision has occurred.

4. The method for evaluating the rubbing force of the auxiliary bearing during the drop process of an electromagnetic bearing rotor, as described in claim 1, is characterized in that... The equations for the momentum P and angular momentum H at the rotor center in S2 are: Where x, y, and z represent the displacements of the rotor along the principal axes of a spatial rectangular coordinate system, respectively; This represents the rotation angle of the rotor about the x-axis, which is the angle between the rotor axis and the xz plane; This represents the angle of rotation of the rotor around the y-axis, which is the angle between the rotor axis and the yz plane; Indicates rotor speed; I T I p Let be the rotor equatorial moment of inertia and the polar moment of inertia, respectively, and m be the rotor mass; the equations for the impulse and moment of impulse at the rotor center are constructed as follows: in, This indicates the time interval.

5. The method for evaluating the rubbing force of the auxiliary bearing during the drop process of an electromagnetic bearing rotor according to claim 4, characterized in that, The equations for the resultant force and resultant moment acting on the rotor, as described in S3, are as follows: 。 6. The method for evaluating the rubbing force of the auxiliary bearing during the drop process of an electromagnetic bearing rotor, as described in claim 1, is characterized in that... The sampling frequency of the sensor in S1 is such that at least two samples are taken between each successive collision.

7. A system for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor, characterized in that, The system has a program module corresponding to the steps of any one of claims 1 to 6 above, and executes the steps in the above-described method for evaluating the rubbing force of the auxiliary bearing during the fall of the electromagnetic bearing rotor.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program configured to, when invoked by a processor, implement the steps of any one of claims 1 to 6 for evaluating the rubbing force of an auxiliary bearing during the drop of an electromagnetic bearing rotor.

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