Control method for a magnetic bearing, magnetic bearing compressor and storage medium

Abstract

This disclosure provides a control method for magnetic levitation bearings, a magnetic levitation compressor, and a storage medium, belonging to the field of magnetic levitation technology. The method includes: a control method for magnetic levitation bearings, comprising: when the rotor is in a levitation state, acquiring the factory equilibrium position and an initial displacement setpoint; acquiring first sensor data from a first displacement sensor, wherein the first displacement sensor is located at one end of the rotor; determining the actual shaft extension based on the factory equilibrium position, the initial displacement setpoint, and the first sensor data; determining a change amount based on half of the actual shaft extension; if the change amount is within a preset range, compensating the initial displacement setpoint with the change amount to obtain a target displacement setpoint; and controlling the axial movement of the rotor based on the target displacement setpoint. This disclosure has the advantage of improving the operational stability of the rotor bearing.

Description

Technical Field

[0001] This disclosure relates to the field of magnetic levitation technology, and in particular to a control method for magnetic levitation bearings, a magnetic levitation compressor, and a storage medium. Background Technology

[0002] With the development of magnetic levitation technology, 2.5-DOF magnetic levitation bearings with thrust disks at both ends are increasingly used. Current technologies typically employ a single-sided fixed control strategy, using the fixed position of one end of the rotor as a reference. Axial displacement is adjusted by manually calibrating the initial shaft extension. This control strategy is only suitable when rotor thermal expansion occurs at one end. If thermal expansion coupling effects occur simultaneously at both ends of the rotor, this control strategy cannot effectively balance the rotor to its equilibrium position, causing mechanical center shift and leading to rotor axial oscillation or even instability.

[0003] Therefore, there is an urgent need for a control method that can be used for 2.5-DOF magnetic levitation bearings to solve the above-mentioned technical problems. Summary of the Invention

[0004] This disclosure provides a control method, a magnetic levitation compressor, and a storage medium for magnetic levitation bearings, to improve the stability of rotor bearing operation.

[0005] In a first aspect, embodiments of this disclosure provide a control method for a magnetic levitation bearing, comprising:

[0006] When the rotor is in a suspended state, obtain the factory balance position and the initial displacement setpoint;

[0007] Acquire first sensor data from the first displacement sensor, wherein the first displacement sensor is located at one end of the rotor;

[0008] The actual shaft extension is determined based on the factory balance position, the initial displacement setpoint, and the data from the first sensor.

[0009] The amount of variation is determined based on half of the actual shaft extension;

[0010] If the change is within a preset range, the change is compensated to the initial displacement setpoint to obtain the target displacement setpoint;

[0011] The axial movement of the rotor is controlled based on the target displacement setpoint.

[0012] In one possible implementation, determining the actual shaft extension based on the factory balance position, the initial displacement setpoint, and the first sensor data includes: determining the current offset of the rotor relative to the factory balance position based on the initial displacement setpoint and the factory balance position; and determining the actual shaft extension based on the current offset, the factory balance position, and the first sensor data.

[0013] In one possible implementation, before the step of obtaining the factory balance position, the method further includes: controlling the rotor to move to both ends of the axial direction at the moment of power-on; obtaining the maximum and minimum values ​​of the second displacement sensor, wherein the second displacement sensor is located at the other end of the rotor opposite to the first displacement sensor; and taking the average of the maximum and minimum values ​​as the factory balance position.

[0014] In one possible implementation, determining the current offset of the rotor relative to the factory balance position based on the initial displacement setpoint and the factory balance position includes: using the difference between the displacement setpoint and the factory balance position as the current offset.

[0015] In one possible implementation, the method according to claim 1, wherein determining the actual shaft extension based on the current offset, the first sensor data, and the factory balance position, comprises: determining the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position; obtaining a shaft extension calibration value, the shaft extension calibration value being used to characterize the shaft extension of the rotor in a preset state; and using the difference between the shaft extension calibration value and the current rotor characteristic length as the actual shaft extension.

[0016] In one possible implementation, the step of determining the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position includes calculating the current rotor characteristic length according to the following formula: Current rotor characteristic length = First sensor data - Factory balance position - Current offset.

[0017] In one possible implementation, before obtaining the shaft extension calibration value, the method further includes: at the power-on moment, when the rotor is in a preset state, using the difference between the first sensor data at the power-on moment and the factory balance position as the shaft extension calibration value; wherein the preset state includes at least one of the following: the rotor is in a suspended state, or the rotor has not undergone thermal expansion;

[0018] The shaft extension calibration quantity is stored at a preset location.

[0019] In one possible implementation, determining the amount of change based on half of the actual shaft extension includes: obtaining a current offset, wherein the current offset of the rotor relative to the factory balance position is determined based on the initial displacement setpoint and the factory balance position; and determining the amount of change based on half of the actual shaft extension and the current offset.

[0020] In one possible implementation, the step of determining the amount of change based on half of the actual shaft extension and the current offset includes determining the amount of change according to the following formula:

[0021] Change = (Actual shaft extension ÷ 2) - Current offset.

[0022] In one possible implementation, after the step of determining the amount of change based on half of the actual shaft extension, the method further includes: if the amount of change is less than the lower limit of the preset range, then determining the actual shaft extension at the next moment based on the target displacement setpoint.

[0023] In one possible implementation, after the step of determining the amount of change based on half of the actual shaft extension, the method further includes: if the amount of change is greater than the upper limit of the preset range, determining the direction of movement of the rotor based on the amount of change; controlling the rotor to move a target length in the direction of movement, and then re-determining the actual shaft extension until the amount of change is less than the lower limit of the preset range.

[0024] In one possible implementation, controlling the axial movement of the rotor according to the target displacement given value includes: if the change is positive, controlling the rotor to move the absolute value of the change in a direction away from the first displacement sensor according to the target displacement given value; or, if the change is negative, controlling the rotor to move the absolute value of the change in a direction closer to the first displacement sensor according to the target displacement given value.

[0025] In one possible implementation, after controlling the axial movement of the rotor according to the target displacement given value, the method further includes: when it is detected that the rotor is not suspended, updating the target displacement given value to the factory balance position.

[0026] Secondly, embodiments of this disclosure provide a magnetic levitation compressor, including: a first displacement sensor, a second displacement sensor, a rotor, a stator, a controller, and a housing;

[0027] The first displacement sensor and the second displacement sensor are disposed opposite to each other at both ends of the rotor. The first displacement sensor, the second displacement sensor, the rotor, and the stator are all integrated and installed within the housing.

[0028] Both the first displacement sensor and the second displacement sensor are data-connected to the controller. The controller is configured to: acquire the factory balance position and the initial displacement setpoint when the rotor is in a suspended state; acquire the first sensor data of the first displacement sensor, wherein the first displacement sensor is located at one end of the rotor; determine the actual shaft extension based on the factory balance position, the initial displacement setpoint, and the first sensor data; determine the change amount based on half of the actual shaft extension; if the change amount is within a preset range, compensate the initial displacement setpoint with the change amount to obtain the target displacement setpoint; and control the axial movement of the rotor based on the target displacement setpoint.

[0029] In one possible implementation, two thrust disks are further included, which are respectively disposed at both ends of the rotor. The first displacement sensor is used to monitor the thermal expansion of one of the thrust disks, and the second displacement sensor is used to monitor the thermal expansion of the other thrust disk.

[0030] Thirdly, embodiments of this disclosure provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0031] This disclosure provides a control method for magnetic levitation bearings, a magnetic levitation compressor, and a storage medium. First, when the rotor is in a suspended state, the actual shaft extension is determined using the acquired factory balance position, initial displacement setpoint, and data from a first displacement sensor. This determines the amount of change, allowing for more accurate control of the rotor's axial movement. Next, the change is checked to see if it is within a preset range. If so, the change is compensated for by adding it to the initial displacement setpoint to obtain a target displacement setpoint. Finally, the rotor's axial movement is controlled based on the target displacement setpoint, achieving real-time adjustment of the rotor to the mechanical center. This ensures the thrust plate is located at the electromagnetic center, improving the rotor's stability during long-term operation, preventing displacement instability, and enhancing the stability of the rotor bearing operation. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0033] Figure 1A schematic diagram of a 2.5-DOF magnetic levitation motor system provided in an embodiment of this disclosure;

[0034] Figure 2 This is a flowchart illustrating a control method for magnetic levitation bearings provided in this disclosure;

[0035] Figure 3 This is a schematic diagram of the principle of the second sensor provided in an embodiment of this disclosure;

[0036] Figure 4 A timing diagram illustrating the axial movement control process of a rotor provided in this disclosure;

[0037] Figure 5 This is a schematic diagram of the control process for a control equation used in a magnetic levitation bearing, provided as an embodiment of the present disclosure.

[0038] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0039] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0040] In related technologies, magnetic levitation bearing systems generally employ a single-sided thrust disk design (e.g., 3+2 or 2+2+1 configuration), with an axial thrust disk only located at one end of the rotor (P end), and no thrust disk at the other end (N end). The single-sided fixed control strategy uses the fixed P end position as a reference, and axial displacement adjustment is achieved by manually calibrating the initial shaft extension (i.e., the difference between the N end displacement sensor reading and the factory equilibrium position). Existing technologies assume that rotor thermal expansion only occurs at the N end, which is far from the thrust disk, and calculate the shaft extension by calibrating the shaft extension on one side and superimposing subsequent expansion changes. However, this design is only suitable for single-sided thrust disk structures. In novel 2.5-DOF magnetic levitation bearings (with thrust disks at both ends), the traditional method fails because it cannot balance the bidirectional thermal expansion coupling effect.

[0041] Figure 1 This is a schematic diagram of a 2.5-DOF magnetic levitation motor system provided in an embodiment of this disclosure.

[0042] like Figure 1As shown, it includes a rotor, stator core, housing, front and rear radial bearings, double-end thrust bearings, limit collars, mechanical bearings, front and rear thrust discs, multiple displacement sensors, and the rotor core. Figure 1 It is known that when both ends of the rotor expand thermally simultaneously, the thrust discs on both sides deviate too far from the electromagnetic center, exceeding the normal operating range, causing changes in stiffness. This can lead to axial oscillation or even instability of the rotor. If the rotor falls after running for a period of time and then re-levitates to its original equilibrium position, the thrust discs, being far from the electromagnetic center, may cause levitation instability or even prevent the rotor from maintaining its levitation state. This necessitates waiting for the rotor to cool down, increasing downtime for maintenance by more than 30%. Therefore, it is evident that if the new 2.5-DOF magnetic levitation bearing still employs the traditional single-sided fixed control strategy,

[0043] To solve the above-mentioned technical problems, the present disclosure provides the following technical concept: the rotor is adjusted to the equilibrium position (mechanical center) in real time through a dynamic compensation algorithm, so that the thrust disk is located at the electromagnetic center, effectively avoiding displacement instability under long-term operation, thereby improving the stability of the bearing.

[0044] The technical solutions of this disclosure and how they solve the aforementioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of this disclosure will now be described with reference to the accompanying drawings.

[0045] Figure 2 This is a flowchart illustrating a control method for magnetic levitation bearings provided in this disclosure, as shown below. Figure 2 As shown, the method includes:

[0046] S201: When the rotor is in a suspended state, obtain the factory balance position and initial displacement setpoint.

[0047] In this embodiment, the rotor is in a suspended state at the factory balance position during operation. After the rotor is lowered and the thrust discs cool down, it is in a non-suspended state. When the rotor is in a suspended state, as time goes by, the thrust discs at both ends of the rotor thermally expand simultaneously, and the amount by which the thrust discs deviate from the electromagnetic center will become larger and larger. Once it exceeds the normal operating range, the stiffness changes, which will cause axial oscillation or even instability of the rotor.

[0048] S202: Obtain first sensor data from the first displacement sensor, wherein the first displacement sensor is located at one end of the rotor.

[0049] In this embodiment, as can be seen from step S201, when the rotor is in a suspended state, data from the first displacement sensor can be collected in real time. The first displacement sensor can be set as follows: Figure 1The image shows the right end of the axis.

[0050] In this embodiment, the factory balance position can be the mechanical center position of the rotor, and the factory balance position is generally fixed.

[0051] In an optional embodiment of this disclosure, the factory balance position can also be calculated based on current actual data. Before obtaining the factory balance position in step S201, the method further includes:

[0052] Step A: At the moment of power-on, control the rotor to move to both ends of the axial direction respectively.

[0053] In this embodiment, when the rotor is powered on and running, the rotor is moved to both ends of the axial direction by controlling the axial suction edge.

[0054] Step B: Obtain the maximum and minimum values ​​of the second displacement sensor, wherein the second displacement sensor is located at the opposite end of the rotor from the first displacement sensor.

[0055] In this embodiment, the maximum value obtained by the second displacement sensor can be as follows: Figure 1 The displacement sensor on the left side of the axis, as shown, collects the displacement value of the thrust disk when it is close to the rightmost side of the axis. The minimum value can be the displacement value collected by the displacement sensor on the left side of the axis when the thrust disk is close to the leftmost side of the axis. The other end opposite to the first displacement sensor can be as follows: Figure 1 The end shown is located near the left side of the axis (also known as the P end).

[0056] Step C: Use the average of the maximum and minimum values ​​as the factory equilibrium position.

[0057] In this embodiment, the equilibrium position is the mechanical center at the moment of power-on, before the thrust plate heats up and expands. At this time, the offset value is still 0. Therefore, the average of the maximum and minimum values ​​can be used as the factory equilibrium position.

[0058] In this embodiment, the maximum and minimum values ​​of the first displacement sensor are obtained by axial suction at the initial power-on moment, so as to obtain a more accurate initial displacement setpoint at the current moment.

[0059] S203: Determine the actual shaft extension based on the factory balance position, initial displacement setpoint, and data from the first sensor.

[0060] In this embodiment, the initial displacement setpoint can be a pre-defined value. For example, the initial displacement setpoint can be equal to the factory balance position at the initial power-on moment. Alternatively, the initial displacement setpoint can be the mechanical center position calculated from the data of the second sensor after the rotor was placed on the shaft last time. If the rotor does not deviate after being placed on the shaft, the initial displacement setpoint is the factory balance position.

[0061] In this embodiment, the factory balance position can be either calibrated and stored at a preset position before leaving the factory, or it can be measured after power-on. The specific position can be determined according to the actual situation, and this embodiment does not limit it.

[0062] In this embodiment, the method for determining the actual shaft extension may be as follows: first, the difference between the initial displacement and the factory balance position is calculated to obtain the offset value; then, based on the offset value, the first sensor data, and the factory balance position, the value length used to characterize the timing expansion or contraction of the rotor at the current moment is obtained; finally, based on the length and the factory-set shaft extension, the actual shaft extension is obtained.

[0063] In this embodiment, the actual shaft extension can also be determined by calculating the difference between the first sensor data at the current moment and the first sensor data at the initial power-on moment. Since the factory balance position at the initial power-on moment is the same as the initial displacement setpoint, the offset is 0. At this time, the actual shaft extension is the difference between the first sensor data collected by the first displacement sensor at the current moment and the first sensor data collected at the initial power-on moment.

[0064] In this embodiment, the actual shaft extension can also be determined by comparing the factory balance position, the initial displacement setpoint, and the data from the first sensor with a preset table. Of course, it is understood that the actual shaft extension can also be determined in other possible ways. The specific method can be determined according to the actual situation, and this embodiment does not limit it.

[0065] Figure 3 This is a schematic diagram of the displacement sensor principle provided in the embodiments of this disclosure.

[0066] like Figure 3 As shown, 1 represents the stator section, and 2 represents the rotor section. The shaded area between stator section 1 and rotor section 2 represents the magnetic pole area. When rotor section 2 moves left and right, the magnetic pole area changes, and the resulting change in electrical signal is calculated by software into the actual change in axial clearance. Based on this principle, an electromagnetic force is generated by applying current to the bearing, causing the rotor to move horizontally left and right. Due to the presence of a limiting ring near the thrust plate, a displacement sensor can detect the axial clearance data and obtain the factory equilibrium position.

[0067] In an optional embodiment of this disclosure, step S203 specifically includes:

[0068] S203a: Determine the current offset of the rotor relative to the factory balance position based on the initial displacement setpoint and the factory balance position.

[0069] In this embodiment, the current offset of the rotor relative to the factory balance position can be the amount of thermal expansion of the thrust disk after being heated or the data of the rotor's offset relative to the mechanical center as of the current moment relative to the initial power-on moment.

[0070] In an optional embodiment of this disclosure, step S203a includes: using the difference between the initial displacement setpoint and the factory equilibrium position as the current offset.

[0071] In this embodiment, the current offset of the rotor relative to the factory balance position can be obtained by subtracting the factory balance position from the initial displacement setpoint. As the rotor levitation time progresses, the current offset is the initial displacement setpoint minus the factory balance position. Since it is necessary to control the rotor to continuously move towards the mechanical center during the levitation process to ensure that the thrust plates at both ends are in the normal electromagnetic center region, the initial displacement setpoint is not fixed. For example, it can be the displacement setpoint calculated during the last adjustment, or it can be a manually set displacement setpoint.

[0072] In an optional embodiment of this disclosure, the current offset can also be determined by collecting data from displacement sensors at both ends of the rotor and motor displacement sensors, and by using a temperature-expansion coefficient model to calculate the current offset, with the N end as the reference.

[0073] It is understood that the current method of determining the offset is not limited to the examples above. Those skilled in the art may make other changes based on the technical essence of the embodiments in this specification. However, as long as the function and effect achieved are the same as or similar to those in the embodiments of this specification, they should be covered within the protection scope of the embodiments of this specification.

[0074] In this embodiment, the difference between the initial displacement setpoint and the factory balance position is used as the current offset, making the process of calculating the current offset applicable to more scenarios, such as the initial power-on moment of the rotor and the scenario after the rotor has been running for a period of time. In different scenarios, a more accurate current offset can be obtained.

[0075] S203b: Determine the actual shaft extension based on the current offset, factory balance position, and data from the first sensor.

[0076] In this embodiment, the maximum shaft extension length at the current moment can be based on the data from the first sensor. Then, the factory balance position and the current offset are subtracted sequentially to obtain an actual length of the rotor at the current moment. Based on the pre-calibrated shaft extension calibration amount and the actual length of the rotor at the current moment, the actual shaft extension is calculated.

[0077] In this embodiment, the current offset of the rotor relative to the factory balance position is determined based on the initial displacement setpoint and the factory balance position. Based on the current offset, the factory balance position and the data from the first sensor, the actual shaft extension is determined, taking into account the case where the offset is not zero, thus obtaining a more accurate actual shaft extension.

[0078] Specifically, in an optional embodiment of this disclosure, S203b may include the following steps:

[0079] b1: Determine the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position.

[0080] In this embodiment, the current rotor characteristic length represents the actual expansion or contraction of the rotor at the current moment. If the current offset is 0, it means that without moving the shaft, the current rotor characteristic length is the difference between the first displacement sensor and the factory balance position. The shaft extension is calculated through the first displacement sensor. When the shaft is moved, the current offset is not zero, and the first displacement sensor changes with the movement of the shaft. The current shaft extension is not the true shaft extension and needs to be added to it.

[0081] Specifically, in an optional embodiment of this disclosure, step b1 calculates the current rotor characteristic length according to the following formula:

[0082] Current rotor characteristic length = First sensor data - Factory balance position - Current offset.

[0083] In this embodiment, the current rotor characteristic length can characterize the actual change length of the rotor. During the rotor operation, as thermal expansion increases and the control shaft moves, the data of the first sensor changes. At this time, the shaft extension is not the real shaft extension. Therefore, the current rotor characteristic length at the current moment can be obtained by subtracting the factory balance position from the first sensor data and then subtracting the current offset.

[0084] In this embodiment, the current rotor characteristic length is accurately calculated using a specific calculation formula, providing more accurate data for subsequent calculation of the actual shaft extension, thereby improving the accuracy of the final actual shaft extension.

[0085] b2: Obtain the shaft extension calibration value, which is used to characterize the shaft extension of the rotor under a preset state.

[0086] In this embodiment, obtaining the shaft extension calibration value can be a process of obtaining the factory shaft extension value through pre-calibration manually, or it can be a process of pre-calibration automatically, such as collecting the first sensor data and reading the factory balance position, and then calculating the value based on the first sensor data and the factory balance position.

[0087] In an optional embodiment of this disclosure, step b2 may further include the following before obtaining the shaft extension calibrated quantity:

[0088] b21: At power-on, when the rotor is in a preset state, the difference between the first sensor data at power-on and the factory balance position is used as the shaft extension calibration value; wherein the preset state may include at least one of the following: the rotor is in a suspended state, or the rotor has not undergone thermal expansion. Of course, more or fewer restrictions can be set for the preset state, and the specifics can be determined according to the actual situation. This specification does not limit this embodiment.

[0089] In this embodiment, the rotor being in a suspended state can be at the moment of power-on. At this time, although the rotor is in a suspended state, no thermal expansion has occurred, and the offset is 0. Therefore, the shaft extension calibration value can be the difference between the data from the first sensor and the factory equilibrium position.

[0090] b22: Store the shaft extension calibration value at the preset position.

[0091] In this embodiment, the preset location can be a storage location in a control device or hardware device electrically connected to the 2.5-degree-of-freedom magnetic levitation motor system, or a memory connected to the control device. For example, the preset location can be a memory with power-off retention function such as an electrically erasable programmable read-only memory (EEPROM), a flash memory (Flash Memory), or a magnetoresistive memory (MRAM).

[0092] In this embodiment, by storing the shaft extension calibration value to a preset position and saving it after power failure, it can be read when the shaft extension calibration value is used later, saving the time of retrieving the shaft extension calibration value in the next cycle and improving the efficiency of controlling the axial movement of the rotor.

[0093] b3: The difference between the calibrated shaft extension value and the current characteristic length of the rotor is taken as the actual shaft extension.

[0094] In this embodiment, the difference between the calibrated shaft extension and the current characteristic length of the rotor is the actual shaft extension.

[0095] In this embodiment, the shaft extension calibration value is obtained by calibrating the shaft extension, and the difference between the shaft extension calibration value and the current rotor characteristic length is used as the actual shaft extension. This is more accurate and can make the subsequent control process more precise, further reducing the possibility of instability.

[0096] S204: Determine the amount of variation based on half of the actual shaft extension.

[0097] In this embodiment, the current offset can be calculated based on the factory balance position and the initial displacement setpoint. The method for calculating the current offset can be the same as that in the above embodiments, and will not be repeated here.

[0098] In this embodiment, after obtaining the current offset, the change can be calculated based on the actual shaft extension and the current offset.

[0099] Specifically, in an optional embodiment of this disclosure, step S204 may include:

[0100] S204a: Obtain the current offset, where the current offset of the rotor relative to the factory balance position is determined based on the initial displacement setpoint and the factory balance position.

[0101] In this embodiment, the current offset can be determined based on the initial displacement given value and the factory balance position. The calculation process for determining the current offset of the rotor relative to the factory balance position in step S204a has been described in step S203a, so it will not be repeated here.

[0102] S204b: Determine the amount of change based on half of the actual shaft extension and the current offset.

[0103] In this embodiment, the change can represent the additional movement of the rotor to be controlled subsequently. The larger the change, the greater the distance the rotor drives the thrust plate away from the electromagnetic center. At this point, it is necessary to dynamically and repeatedly control the rotor to move left or right so that the rotor drives the thrust plate to be located at the electromagnetic center. The change can be calculated using a pre-set formula based on the actual shaft extension and the current offset.

[0104] In this embodiment, the current offset of the rotor relative to the factory balance position is first determined, and then the change is determined based on half of the actual shaft extension and the current offset. This allows for more accurate control of the rotor's movement over the corresponding distance. Adding the current offset prevents changes in the displacement sensor values ​​after shaft movement, resulting in a shaft extension closer to the actual value.

[0105] Specifically, in an optional embodiment of this disclosure, step S204b determines the amount of change according to the following formula: amount of change = (actual shaft extension ÷ 2) - current offset.

[0106] In this embodiment, the change is obtained by subtracting the current offset from half of the actual shaft extension. For example, if the actual shaft extension is 18μm and the current offset is 2μm, then the change = (9-2)μm = 7μm.

[0107] In this embodiment, the change is determined by a specific calculation formula, making the final value of the change more accurate. This is beneficial for subsequent rotor movement control, allowing the rotor to be adjusted closer to the mechanical center, thereby bringing the thrust plate closer to the electromagnetic center.

[0108] S205: If the change is within the preset range, the change will be compensated to the initial displacement setpoint to obtain the target displacement setpoint.

[0109] In this embodiment, the preset range can be a pre-defined numerical range. When the change is within this range, it means that only a small distance needs to be controlled to move the rotor towards the P end or N end to adjust the rotor to the mechanical center in real time. For example, the preset range can be 6 to 20 μm.

[0110] In this embodiment, when the change is within a preset range, the target displacement setpoint is updated by compensating for the change in the initial displacement setpoint. The target displacement setpoint can then be used as a control parameter, and the controller can control the rotor to move towards end P or end N by a corresponding amount based on this parameter. For example, the target displacement setpoint can be the initial displacement setpoint of 2μm plus the change + 7μm, resulting in 9μm. Accordingly, based on 2μm, it is only necessary to control the rotor to move towards end P by 7μm, so that the rotor's position after movement is 9μm from the machine center.

[0111] Based on the above embodiments, in an optional embodiment of this disclosure, after step S203, the following may be included:

[0112] If the change is less than the lower limit of the preset range, the actual shaft extension at the next moment is determined based on the target displacement given value.

[0113] In this embodiment, when the change is less than the lower limit of the preset range, it indicates that the deviation between the initial mechanical center of the rotor and the current mechanical center caused by rotor expansion or contraction has not reached the level of displacement instability. At this point, simply return to step S201 and use the target displacement setpoint as the new displacement setpoint to determine the actual shaft extension at the next moment. This process is repeated until the change exceeds the lower limit of the preset range or the rotor falls off the shaft, at which point the next round of adjustment control is performed. The specific method for determining the actual shaft extension at the next moment is similar to the process in steps S201 to S203, so it will not be repeated here. The difference is that in this embodiment, the target displacement setpoint replaces the original initial displacement setpoint for subsequent steps to determine the actual shaft extension in this round.

[0114] In this embodiment, when the change is less than the lower limit of the preset range, the target displacement setpoint is used as a reference to determine the actual shaft extension at the next moment. By slowly accumulating the shaft extension, the axial movement of the rotor is not over-controlled, thus improving the stability and accuracy of the rotor movement control.

[0115] Based on the above embodiments, as an optional embodiment of this disclosure, after step S203, the method may further include: if the change is greater than the upper limit of a preset range, determining the rotor's moving direction based on the change. After controlling the rotor to move a target length in the moving direction, the actual shaft extension is re-determined until the change is less than the lower limit of the preset range.

[0116] In this embodiment, if the change is greater than the upper limit of a preset range, for example, if the change is greater than 20 μm, the specific direction of movement can be determined based on the sign of the change. If the change is negative, the first direction is the direction closer to the first displacement sensor; otherwise, the direction of movement is the direction away from the first displacement sensor.

[0117] In this embodiment, the length of the moving target can be converted into a control quantity, and then the rotor can be controlled to move in the moving direction based on the control quantity.

[0118] S206: Control the axial movement of the rotor based on the target displacement setpoint.

[0119] In this embodiment, the axial movement of the rotor can be controlled based on the target displacement setpoint by generating a control quantity based on the target displacement setpoint, and then outputting the control quantity to the magnetic levitation bearing to control the axial movement of the rotor.

[0120] Specifically, in an optional embodiment of this disclosure, step S206 may include:

[0121] S206a: If the change is positive, then the rotor is controlled to move away from the first displacement sensor according to the target displacement given value.

[0122] In this embodiment, a positive change value can be predefined to represent a scenario where the rotor is in a state of slow, increasing expansion of the shaft extension. As the positive change value increases, the distance the rotor will move will also increase. When the change value is positive, it can be considered that the rotor is too close to the N end. Subsequently, the rotor can be moved towards the P end by the change value to adjust the rotor's mechanical center to the change value plus the initial displacement setpoint. This embodiment does not specifically limit the expansion scenario of moving towards the P end or towards the N end to the shaft extension expansion scenario. Specifically, depending on the actual situation, the direction in which the rotor moves by the change value can be defined when the change value is positive.

[0123] Alternatively, S206b: If the change is negative, then control the rotor to move towards the direction closer to the first displacement sensor based on the target displacement given value.

[0124] In this embodiment, when the change is negative, the absolute value of the change represents the distance the rotor needs to move in a scenario where the bearing contraction is slowly increasing. As the negative change increases, the distance the rotor will move will also increase. When the change is negative, it can be considered that the rotor is too close to end P. Subsequently, the rotor can be moved towards end N by the distance of the change to adjust its mechanical center to the change plus the initial displacement setpoint. This embodiment does not specifically limit the movement towards end N to a contraction scenario or a shaft extension contraction scenario. Specifically, depending on the actual situation, the direction in which the rotor moves by the absolute value of the change can be defined when the change is negative.

[0125] In this embodiment, the accurate direction of rotor movement is determined by the sign of the change. Then, based on the target displacement given value, the accurate distance the rotor needs to move in the correct direction is obtained, which improves the accuracy of rotor axial movement control and thus improves rotor stability.

[0126] Based on the above embodiments, as an optional embodiment of this disclosure, a control method for magnetic levitation bearings may further include, after step S206: when the rotor is detected to be in a non-levitation state, the target displacement setpoint is updated to the factory balance position.

[0127] In this embodiment, the non-suspended rotor position refers to the state after the rotor has fallen off the shaft. Since the shaft extension accumulates to the large bearing scenario after the rotor has been running for a period of time, if the rotor is to be resuspended later, it cannot be suspended normally according to the original factory balance position. Therefore, the factory balance position is assigned to the target displacement setpoint in order to control the rotor movement in the next round.

[0128] In this embodiment, when the rotor is detected to be in a non-suspended state, the target displacement setpoint is updated to the factory balance position so that the rotor can be adaptively reset when it is resuspended. That is, after the rotor is resuspended, it will find a new balance position, reducing the risk of instability.

[0129] Based on the above embodiments, and to facilitate understanding of the control method for magnetic levitation bearings provided in the above embodiments, the following will be explained with reference to specific examples:

[0130] Figure 4 This is a timing diagram illustrating the axial movement control process of a rotor provided in this disclosure.

[0131] like Figure 4As shown, at the initial power-on time t0, the initial displacement setpoint is equal to the factory equilibrium position, and the calibrated shaft extension calibration value is x μm. As the rotor levitation time increases, the current offset gradually increases, and the corresponding current rotor characteristic length also gradually changes. When time reaches t1, the change is 5 μm. At this time, the change is not within the preset range of 6 to 20 μm, and there is no need to control the axial movement of the rotor.

[0132] When time reaches t2, the calculated shaft extension is 14μm, which is within the preset range of 6 to 20μm. At this time, half of the shaft extension is used for adjustment, that is, the rotor is controlled to move 7μm to the left. After the movement is completed, it becomes the state at time t3.

[0133] Furthermore, if the change in tx accumulates to 80μm at some point after time t1, it exceeds the upper limit of the preset range of 20μm. Therefore, the rotor is first controlled to move 20μm to the left, and then the change is judged. If the change is 40μm, the rotor is controlled to move 20μm to the left. Then the change is calculated and judged again until the change is less than 6μm or the rotor falls off the shaft, and the entire control process ends.

[0134] In summary, this disclosure provides a control method for magnetic levitation bearings. First, when the rotor is in a suspended state, the actual shaft extension is determined using the acquired factory balance position, initial displacement setpoint, and data from a first displacement sensor, thus determining the amount of change. Next, it is detected whether the amount of change is within a preset range. If so, the amount of change is compensated to the initial displacement setpoint to obtain a target displacement setpoint. Finally, the axial movement of the rotor is controlled according to the target displacement setpoint, achieving real-time adjustment of the rotor to the mechanical center, thereby placing the thrust disk at the electromagnetic center, improving the stability of the rotor during long-term operation, and preventing displacement instability.

[0135] Figure 5 This is a schematic diagram of the control process for a control equation used in a magnetic levitation bearing, provided as an embodiment of the present disclosure.

[0136] The following will combine Figure 5 The entire control process of a control method for a magnetic levitation bearing provided in this disclosure embodiment is described. For example... Figure 5 As shown, the specific implementation process of this method for magnetic levitation bearings may include the following steps: after the implementation process begins.

[0137] S501: Determine whether the rotor is suspended.

[0138] In this embodiment, if the rotor is suspended, step S502 is executed; if it is not suspended, the shaft extension is cleared to zero, and the process jumps directly to the end step of the control process of the magnetic levitation bearing.

[0139] In subsequent control processes, if the system recycles to step S501 and the bearing is not levitated, the change can be cleared to zero before returning to the end step of the current magnetic levitation bearing control process.

[0140] S502: Calculate the current offset based on the initial displacement setpoint and the factory equilibrium position.

[0141] In this embodiment, the calculation formula for step S502 can be: Current offset = Initial displacement setpoint - Factory balance position. The factory balance position can be the mechanical center, which is fixed and unchanging. When the rotor has not expanded, the current offset is 0 according to the control process in related technologies.

[0142] S503: Determine the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position.

[0143] In this embodiment, the first sensor data corresponds to the value collected by the BZ displacement sensor in the above embodiment, and the current rotor characteristic length corresponds to the current length in the above embodiment. The formula for determining the current rotor characteristic length in step S503 can be: length = BZ displacement sensor value - factory balance position - current offset.

[0144] In this embodiment, when calculating the current rotor characteristic length, if the current offset is 0, it indicates that the shaft has not moved. The calculation method is: length = BZ displacement sensor value - factory balance position. Since the shaft extension is calculated through the BZ displacement sensor, the BZ sensor value changes after the shaft is moved. At this time, the current rotor characteristic length does not reflect the true shaft extension, so the current offset needs to be added.

[0145] S504: Determine whether the shaft extension needs to be calibrated.

[0146] In this embodiment, if the determination result is calibration, step S505 is executed; otherwise, step S506 is executed. Calibration can be achieved through manual calibration.

[0147] S505: Record the current rotor characteristic length as the factory shaft extension.

[0148] In this embodiment, the difference between the current BZ displacement sensor and the factory balance position is used as the current rotor characteristic length, and the obtained current rotor characteristic length is stored in EEPROM and saved after power failure. Thus, it can be seen that the factory shaft extension is stored in EEPROM.

[0149] S506, calculate the actual shaft extension as the factory shaft extension minus the current rotor characteristic length.

[0150] S507: The change is calculated as half of the actual shaft extension minus the current offset.

[0151] S508: Determine whether the change is within the preset range.

[0152] In this embodiment, if the change is within a preset range, step S509 is executed; otherwise, step S5010 is executed. For example, the preset range can be 6 to 20 μm.

[0153] S509: The target displacement setpoint is calculated as the initial displacement setpoint plus the change.

[0154] In this embodiment, after calculating the target displacement setpoint in step S509, the axial movement of the rotor can be controlled based on the target displacement setpoint. The target displacement setpoint can be moved to the left or right by the sign of the change. Positive and negative can represent expansion or contraction, which is used to control the rotor in scenarios where the shaft extension expands or contracts slowly. After moving the rotor once, the process returns to step S501 to continue the subsequent control process.

[0155] S5010: Determine whether the change is greater than the upper limit of the preset range.

[0156] In this embodiment, the upper limit of the preset range can be 20 μm. When the value or absolute value of the change is greater than 20 μm, step S5011 is executed; otherwise, the process jumps directly to the end step of the current magnetic levitation bearing control process.

[0157] S5011, calculate the target displacement setpoint as the sum or difference between the initial displacement setpoint and the upper limit of the preset range.

[0158] In this embodiment, the calculation formula for step S501 can be: target displacement given value = initial displacement given value ± upper limit of preset range. It should be noted that when the magnetic levitation bearing is in a scenario with a large shaft extension after running for a period of time, when it is re-levitated, the factory balance position will be assigned to the initial displacement given value. At this time, if it cannot levitate normally according to the factory balance position, the shaft needs to be moved according to half of the actual shaft extension. However, if it is moved too much at once, it will cause the actual shaft extension to overshoot and trigger a fault. Therefore, each time step S5011 is executed, the upper limit of a fixed preset range, such as 20μm, is moved. After multiple moves, it will move to a symmetrical position.

[0159] In this embodiment, after calculating the target displacement setpoint, the axial movement of the rotor can be controlled based on the target displacement setpoint. After moving the rotor once, the process returns to step S501 to continue the subsequent control process.

[0160] In this embodiment, if the rotor is continuously moved and the change is less than the lower limit of the preset range, such as 6μm, or when other control flow termination conditions are met, the process can jump to the termination step.

[0161] This disclosure also provides an embodiment for a magnetic levitation compressor.

[0162] You can continue to refer to this. Figure 1 The magnetic levitation compressor includes a first displacement sensor, a second displacement sensor, a rotor, a stator, a controller, and a housing.

[0163] The first displacement sensor and the second displacement sensor are positioned opposite each other at both ends of the rotor. The first displacement sensor, the second displacement sensor, the rotor, and the stator are all integrated and installed inside the housing.

[0164] In this embodiment, the first displacement sensor and the second displacement sensor can be specifically installed at both ends of the rotor near the thrust plate.

[0165] Both the first and second displacement sensors are connected to the controller via data transfer. The controller is used to: acquire the factory balance position and the initial displacement setpoint when the rotor is in a suspended state; acquire the first sensor data of the first displacement sensor, wherein the first displacement sensor is located at one end of the rotor; determine the actual shaft extension based on the factory balance position, the initial displacement setpoint, and the first sensor data; determine the change amount based on half of the actual shaft extension; if the change amount is within a preset range, compensate the initial displacement setpoint for the change amount to obtain the target displacement setpoint; and control the axial movement of the rotor based on the target displacement setpoint.

[0166] In this embodiment, the controller can be any hardware device with a processor or control module capable of data connection with the magnetic levitation compressor. For example, the controller can be a chip, a programmable controller, a computer, or other devices based on data processing and control functions. This embodiment does not impose any limitations on this. Figure 1 The specific structure of the controller is not shown in the diagram.

[0167] In an optional embodiment of this disclosure, the magnetic levitation compressor further includes two thrust discs, which are respectively disposed at both ends of the rotor.

[0168] In an optional embodiment of this disclosure, the controller is specifically configured to: determine the current offset of the rotor relative to the factory balance position based on the initial displacement setpoint and the factory balance position; and determine the actual shaft extension based on the current offset, the factory balance position, and the data from the first sensor.

[0169] In an optional embodiment of this disclosure, before the controller is specifically used to obtain the factory balance position, it is further used to: control the rotor to move to both ends of the axial direction at the time of power-on; obtain the maximum and minimum values ​​of the second displacement sensor, wherein the second displacement sensor is located at the other end of the rotor opposite to the first displacement sensor; and take the average of the maximum and minimum values ​​as the factory balance position.

[0170] In an optional embodiment of this disclosure, the controller is specifically configured to: use the difference between the initial displacement setpoint and the factory equilibrium position as the current offset.

[0171] In an optional embodiment of this disclosure, the controller is specifically configured to: determine the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position; obtain a shaft extension calibration value, which is used to characterize the shaft extension of the rotor in a preset state; and use the difference between the shaft extension calibration value and the current rotor characteristic length as the actual shaft extension.

[0172] In an optional embodiment of this disclosure, the controller is specifically configured to: determine the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position, including calculating the current rotor characteristic length according to the following formula: Current rotor characteristic length = First sensor data - Factory balance position - Current offset.

[0173] In an optional embodiment of this disclosure, before the controller is used to acquire the shaft extension calibration value, it is further used to: at the time of power-on, when the rotor is in a preset state, use the difference between the first sensor data at the time of power-on and the factory balance position as the shaft extension calibration value; wherein the preset state includes at least one of the following: the rotor is in a suspended state, the rotor has not undergone thermal expansion; and store the shaft extension calibration value at a preset position.

[0174] In an optional embodiment of this disclosure, the controller is specifically configured to: obtain the current offset, wherein the current offset of the rotor relative to the factory balance position is determined based on the initial displacement setpoint and the factory balance position; and determine the change based on half of the actual shaft extension and the current offset.

[0175] In an optional embodiment of this disclosure, the controller is specifically configured to: determine the amount of change based on half of the actual shaft extension and the current offset, including determining the amount of change according to the following formula:

[0176] Change = (Actual shaft extension ÷ 2) - Current offset.

[0177] In an optional embodiment of this disclosure, after determining the amount of change based on half of the actual shaft extension, the controller is further configured to: if the amount of change is less than the lower limit of a preset range, determine the actual shaft extension at the next moment based on the target displacement given value.

[0178] In an optional embodiment of this disclosure, after determining the amount of change based on half of the actual shaft extension, the controller is further configured to: if the amount of change is greater than the upper limit of a preset range, determine the direction of movement of the rotor based on the amount of change; after controlling the rotor to move a target length in the direction of movement, redetermine the actual shaft extension until the amount of change is less than the lower limit of the preset range.

[0179] In an optional embodiment of this disclosure, the controller is specifically configured to: if the change is positive, control the rotor to move in a direction away from the first displacement sensor by the absolute value of the change according to the target displacement given value; or, if the change is negative, control the rotor to move in a direction closer to the first displacement sensor by the absolute value of the change according to the target displacement given value.

[0180] In an optional embodiment of this disclosure, after the controller controls the axial movement of the rotor according to the target displacement setpoint, it is further configured to: when the rotor is detected to be in a non-suspended state, update the target displacement setpoint to the factory balance position.

[0181] The controller provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0182] This disclosure also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement any of the control methods for magnetic levitation bearings described in the above embodiments.

[0183] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0184] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0185] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0186] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0187] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0188] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0189] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0190] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A control method for magnetic levitation bearings, characterized in that, include: When the rotor is in a suspended state, obtain the factory balance position and the initial displacement setpoint; Acquire first sensor data from a first displacement sensor, wherein the first displacement sensor is located at one end of the rotor; The actual shaft extension is determined based on the factory balance position, the initial displacement setpoint, and the data from the first sensor. The amount of variation is determined based on half of the actual shaft extension; If the change is within a preset range, the change is compensated to the initial displacement setpoint to obtain the target displacement setpoint; The axial movement of the rotor is controlled based on the target displacement setpoint.

2. The method according to claim 1, characterized in that, The step of determining the actual shaft extension based on the factory balance position, the initial displacement setpoint, and the data from the first sensor includes: Based on the initial displacement setpoint and the factory balance position, determine the current offset of the rotor relative to the factory balance position; The actual shaft extension is determined based on the current offset, the factory balance position, and the data from the first sensor.

3. The method according to claim 1, characterized in that, Before the step of obtaining the factory balance position, the method further includes: At the moment of power-on, the rotors are controlled to move to both ends of the axial direction respectively; Obtain the maximum and minimum values ​​of the second displacement sensor, wherein the second displacement sensor is located at the other end of the rotor opposite to the first displacement sensor; The average of the maximum and minimum values ​​is taken as the factory equilibrium position.

4. The method according to claim 2, characterized in that, Based on the initial displacement setpoint and the factory balance position, determine the current offset of the rotor relative to the factory balance position, including: The difference between the initial displacement setpoint and the factory equilibrium position is used as the current offset.

5. The method according to claim 2, characterized in that, The step of determining the actual shaft extension based on the current offset, the first sensor data, and the factory balance position includes: The current rotor characteristic length is determined based on the current offset, the first sensor data, and the factory balance position; Obtain a shaft extension calibrated value, which is used to characterize the shaft extension of the rotor in a preset state; The difference between the calibrated shaft extension value and the current characteristic length of the rotor is taken as the actual shaft extension.

6. The method according to claim 5, characterized in that, The step of determining the current rotor characteristic length based on the current offset, the first sensor data, and the factory balance position includes calculating the current rotor characteristic length according to the following formula: The current rotor characteristic length = the first sensor data - the factory balance position - the current offset.

7. The method according to claim 5, characterized in that, Before obtaining the shaft extension calibration value, the following steps are also included: At the moment of power-on, when the rotor is in a preset state, the difference between the first sensor data at the moment of power-on and the factory balance position is used as the shaft extension calibration value; wherein the preset state includes at least one of the following: the rotor is in a suspended state, or the rotor has not undergone thermal expansion; The shaft extension calibration quantity is stored at a preset location.

8. The method according to claim 1, characterized in that, The determination of the variation based on half of the actual shaft extension includes: Obtain the current offset, wherein the current offset of the rotor relative to the factory balance position is determined based on the initial displacement setpoint and the factory balance position; The amount of change is determined based on half of the actual shaft extension and the current offset.

9. The method according to claim 8, characterized in that, The step of determining the change based on half of the actual shaft extension and the current offset includes determining the change according to the following formula: Change = (Actual shaft extension ÷ 2) - Current offset.

10. The method according to claim 1, characterized in that, Following the step of determining the amount of variation based on half of the actual shaft extension, the method further includes: If the change is less than the lower limit of the preset range, the actual shaft extension at the next moment is determined based on the target displacement given value.

11. The method according to claim 1, characterized in that, Following the step of determining the amount of variation based on half of the actual shaft extension, the method further includes: If the change is greater than the upper limit of the preset range, the direction of movement of the rotor is determined based on the change. After controlling the rotor to move the target length in the moving direction, the actual shaft extension is re-determined until the change is less than the lower limit of the preset range.

12. The method according to claim 1, characterized in that, The step of controlling the axial movement of the rotor according to the target displacement given value includes: If the change is positive, then the rotor is controlled to move away from the first displacement sensor by the absolute value of the change based on the target displacement given value; Alternatively, if the change is negative, the rotor is controlled to move towards the first displacement sensor by the absolute value of the change based on the target displacement given value.

13. The method according to any one of claims 1 to 12, characterized in that, After controlling the axial movement of the rotor according to the target displacement given value, the method further includes: When the rotor is detected to be in a non-suspended state, the target displacement setpoint is updated to the factory balance position.

14. A magnetic levitation compressor, characterized in that, include: The components include a first displacement sensor, a second displacement sensor, a rotor, a stator, a controller, and a housing. The first displacement sensor and the second displacement sensor are disposed opposite to each other at both ends of the rotor. The first displacement sensor, the second displacement sensor, the rotor, and the stator are all integrated and installed within the housing. Both the first displacement sensor and the second displacement sensor are data-connected to the controller. The controller is configured to: acquire the factory balance position and the initial displacement setpoint when the rotor is in a suspended state; acquire the first sensor data of the first displacement sensor, wherein the first displacement sensor is located at one end of the rotor; determine the actual shaft extension based on the factory balance position, the initial displacement setpoint, and the first sensor data; determine the change amount based on half of the actual shaft extension; if the change amount is within a preset range, compensate the initial displacement setpoint with the change amount to obtain the target displacement setpoint; and control the axial movement of the rotor based on the target displacement setpoint.

15. The magnetic levitation compressor according to claim 14, characterized in that, It also includes two thrust disks, which are respectively located at both ends of the rotor.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 13.

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