CN116663201B - Method, equipment and medium for determining suspension center of magnetic suspension molecular pump rotor - Google Patents

Method, equipment and medium for determining suspension center of magnetic suspension molecular pump rotor Download PDF

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Publication number
CN116663201B
CN116663201B CN202310927226.5A CN202310927226A CN116663201B CN 116663201 B CN116663201 B CN 116663201B CN 202310927226 A CN202310927226 A CN 202310927226A CN 116663201 B CN116663201 B CN 116663201B
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rotor
magnetic bearing
axial
radial
center
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CN116663201A (en
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孙灵豪
张亮
高鑫
王少伯
张嘉伟
罗珂
张广远
陈林
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Beijing Zhongke Jiuwei Technology Co ltd
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Beijing Zhongke Jiuwei Technology Co ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/04—Shafts or bearings, or assemblies thereof
    • F04D29/046—Bearings
    • F04D29/048—Bearings magnetic; electromagnetic
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/003—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring position, not involving coordinate determination
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

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  • Engineering & Computer Science (AREA)
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  • General Engineering & Computer Science (AREA)
  • Pure & Applied Mathematics (AREA)
  • Mathematical Optimization (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Mathematical Analysis (AREA)
  • Computational Mathematics (AREA)
  • Electromagnetism (AREA)
  • Mechanical Engineering (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)

Abstract

The present disclosure discloses a method, apparatus and medium for determining a levitation center of a magnetic levitation molecular pump rotor. The magnetic levitation molecular pump comprises a rotor, and axial and radial magnetic bearings to support the rotor in use, the method comprising the steps of: controlling the current of the axial magnetic bearing to enable the rotor to float according to the designed axial suspension center or the preselected axial suspension center, and adjusting the current of the radial magnetic bearing to obtain the radial displacement extremum of the rotor; calculating the final radial suspension center of the rotor according to the radial displacement extreme value; controlling the current of the radial magnetic bearing to enable the rotor to float according to the final radial suspension center, and adjusting the current of the axial magnetic bearing to obtain an axial displacement extremum of the rotor; and calculating the final axial suspension center of the rotor according to the axial displacement extreme value. The method provided by the embodiment of the disclosure can ensure that the finally determined radial suspension center and axial suspension center both exclude the influence of factors such as friction force and the like, and improve the accuracy of the suspension center.

Description

Method, equipment and medium for determining suspension center of magnetic suspension molecular pump rotor
Technical Field
The present disclosure relates generally to the field of magnetic levitation molecular pumps. More particularly, the present disclosure relates to a method, apparatus, and medium for determining a levitation center of a rotor of a magnetic molecular pump.
Background
The magnetic suspension molecular pump is a molecular pump technology for realizing long-term safe, reliable and energy-saving stable flow control by utilizing a friction-free magnetic suspension principle. Because the friction-free magnetic suspension technology is adopted in the magnetic suspension molecular pump, compared with the traditional mechanical bearing turbine molecular pump, the vibration and noise are reduced, and the magnetic suspension molecular pump can stably work for a long time and realize more accurate control and adjustment. In view of the excellent performance of the magnetic levitation molecular pump, the magnetic levitation molecular pump is widely applied to the fields of semiconductor industry and the like, such as gas pumping for links such as etching, ion implantation, photoetching and the like.
Magnetic levitation molecular pumps generally employ magnetic bearings to provide levitation forces that support the molecular pump rotor. In the magnetic suspension molecular pump, a magnetic bearing is sleeved on a rotor, and the electromagnetic force applied to the rotor by the magnetic bearing can be adjusted by controlling coil current in the magnetic bearing.
Since the magnetic bearing is a non-contact bearing, it is required to be used together with a protection bearing in a magnetic levitation molecular pump. In abnormal operation, such as power failure, unstability, etc., the rotor in the magnetic suspension molecular pump is supported by the protection bearing of the magnetic suspension molecular pump, thereby preventing the rotor from contacting parts except the protection bearing and causing damage.
When the magnetic suspension molecular pump works normally, the magnetic bearing is required to output certain electromagnetic force to suspend the rotor, and the suspension center of the rotor is required to be consistent with the protection center of the protection bearing, so that the requirement of the rotor on the maximum movable space under the condition of the magnetic bearing support is met. However, due to the factors of the difference of the processing circuit of the magnetic bearing controller, the error between the installation position of the probe of the displacement sensor and the design position, the installation error of the protection bearing and the displacement sensor, the difference of the outgoing line and the adapter, and the like, the actual value of the suspension center of the rotor supported by the magnetic bearing and the design value often have the difference, which can influence the control effect of the magnetic bearing, and can cause the collision between the rotor and other parts in the magnetic suspension molecular pump to cause serious damage to the magnetic suspension molecular pump when serious, so the adjustment of the suspension center of the rotor of the magnetic suspension molecular pump is an important link for ensuring the rotor to work with the protection center as the center.
Currently, in the prior art, a certain current is directly applied to a stator, and after a rotor is adsorbed on a corresponding magnetic pole, a suspension center is calculated. However, the influence of gravity, friction force or acting force such as magnetic force of a motor permanent magnet is not considered in the method, so that the finally obtained suspension center is poor in accuracy.
In view of the foregoing, it is desirable to provide a solution for determining the suspension center of a rotor of a magnetic suspension molecular pump, so as to eliminate the influence of factors such as gravity, friction force or magnetic force of a permanent magnet of a motor on the adjustment result and improve the consistency of the determined suspension center and the protection center.
Disclosure of Invention
To address at least one or more of the technical problems mentioned above, the present disclosure proposes, among other aspects, a magnetic levitation molecular pump rotor levitation center determination scheme.
In a first aspect, the present disclosure provides a method of determining a levitation center of a rotor of a magnetic levitation molecular pump, the magnetic levitation molecular pump comprising a rotor, and an axial magnetic bearing and a radial magnetic bearing to support the rotor in use, the method comprising the steps of: controlling the current of the axial magnetic bearing to enable the rotor to float according to the designed axial suspension center or the preselected axial suspension center, and adjusting the current of the radial magnetic bearing to obtain the radial displacement extremum of the rotor; calculating the final radial suspension center of the rotor according to the radial displacement extreme value; controlling the current of the radial magnetic bearing to enable the rotor to float according to the final radial suspension center, and adjusting the current of the axial magnetic bearing to obtain an axial displacement extremum of the rotor; and calculating the final axial suspension center of the rotor according to the axial displacement extreme value.
In some embodiments, the step of levitating the rotor according to a designed axial levitation center or a preselected axial levitation center specifically includes: judging whether the position of the rotor determined based on the designed axial suspension center is within the effective suspension range of the rotor; if yes, the rotor is suspended according to the designed axial suspension center; and if not, adjusting the current of the axial magnetic bearing to obtain an axial displacement extremum of the rotor, calculating an axial suspension center of the rotor according to the axial displacement extremum, and taking the axial suspension center as a preselected axial suspension center to suspend the rotor according to the preselected axial suspension center.
In some embodiments, the step of adjusting the current of the radial magnetic bearing specifically comprises: sequentially applying positive current of a first fixed time and negative current of a second fixed time to the radial magnetic bearing according to a preset radial gradient curve; and/or the step of adjusting the current of the axial magnetic bearing comprises in particular: and sequentially applying positive current for a first fixed time and negative current for a second fixed time to the axial magnetic bearing according to a preset axial gradient curve.
In some embodiments, the radial gradient curve is as follows: when (when)In the time-course of which the first and second contact surfaces,the method comprises the steps of carrying out a first treatment on the surface of the When->When (I)>； wherein ,/>Representing the actual value of the electromagnetic force output by the radial magnetic bearing,/->Indicating the current applied to the radial magnetic bearing, < >>Representing the weight of the rotor and,design value representing electromagnetic force output by radial magnetic bearing during normal operation, < >> and />Representing the current regulation factor, ">Greater than 0->Greater than 1, t represents the time of application of the current, +.>Representing the included angle between the direction of the magnetic pole of the radial magnetic bearing and the direction of the resultant force applied by the rotor,/and%>，/>Indicating vacuum permeability->Representing the magnetic pole area of the radial magnetic bearing, +.>Represents the number of turns of the radial magnetic bearing, +.>Air gap of the magnetic pole of the radial magnetic bearing and the surface of the rotor is represented, < >>Representing the bias current of the design +.>The distance of the rotor deviating from the suspension center is represented, and the value of the distance is the radius of the effective suspension range; and/or the axial gradient profile is as follows: when->In the time-course of which the first and second contact surfaces,the method comprises the steps of carrying out a first treatment on the surface of the When->When (I)>； wherein ,/>Representing the actual value of the electromagnetic force output by the axial magnetic bearing,/->Indicating the current applied to the axial magnetic bearing, +.>Representing the weight of the rotor>Design value representing electromagnetic force output by axial magnetic bearing during normal operation, < >> and />Representing the current regulation factor, ">Greater than 0->Greater than 1, t represents the time of application of the current, +.>Representing the included angle between the magnetic pole direction of the axial magnetic bearing and the resultant force direction of the rotor, < > >，/>Indicating vacuum permeability->Representing the magnetic pole area of the axial magnetic bearing, +.>Represents the number of turns of the coil of the axial magnetic bearing, +.>Air gap of the magnetic pole of the axial magnetic bearing and the surface of the rotor is represented, < >>Representing the bias current of the design +.>The distance of the rotor from the center of levitation is expressed and is taken as the radius of the effective levitation range.
In some embodiments, the radial magnetic bearings comprise a first radial magnetic bearing and a second radial magnetic bearing; the magnetic suspension molecular pump comprises a first transverse displacement sensor and a first longitudinal displacement sensor which are adjacent to the first radial magnetic bearing and are all used for measuring the displacement value of the rotor, and a second transverse displacement sensor and a second longitudinal displacement sensor which are adjacent to the second radial magnetic bearing and are all used for measuring the displacement value of the rotor; the final radial suspension center comprises a final transverse suspension center and a final longitudinal suspension center, and the final radial suspension center is specifically obtained by the following steps: controlling the current of the axial magnetic bearing to enable the rotor to suspend according to the designed axial suspension center or the preselected axial suspension center; adjusting the currents of the first radial magnetic bearing and the second radial magnetic bearing, acquiring a first transverse displacement extreme value measured by a first transverse displacement sensor and used for transversely measuring the rotor and a second transverse displacement extreme value measured by a second transverse displacement sensor and used for transversely measuring the rotor, and respectively calculating the final transverse suspension center of the rotor at the positions of the first radial magnetic bearing and the second radial magnetic bearing according to the first transverse displacement extreme value and the second transverse displacement extreme value; controlling the current of the first radial magnetic bearing and the second radial magnetic bearing to enable the rotor to float at the final transverse suspension center of the position where the first radial magnetic bearing and the second radial magnetic bearing are respectively positioned; adjusting the currents of the first radial magnetic bearing and the second radial magnetic bearing, acquiring a first longitudinal displacement extreme value of the rotor in the longitudinal direction, which is measured by a first longitudinal displacement sensor, and a second longitudinal displacement extreme value of the rotor in the longitudinal direction, which is measured by a second longitudinal displacement sensor, and respectively calculating final longitudinal suspension centers of the rotor at the positions of the first radial magnetic bearing and the second radial magnetic bearing according to the first longitudinal displacement extreme value and the second longitudinal displacement extreme value; wherein, the transverse direction and the longitudinal direction are perpendicular to each other and all belong to the radial direction.
In some embodiments, the method further comprises: if the position of the rotor determined based on the final radial suspension center exceeds the effective suspension range of the rotor, feeding back a preset first error code mark; and if the position of the rotor determined based on the final axial levitation center is outside the effective levitation range of the rotor, feeding back a predetermined second error code identification.
In some embodiments, the radial displacement extremum includes a radial displacement maximum and a radial displacement minimum, and the final radial suspension center is calculated based on the steps of: taking the midpoint between the position of the maximum radial displacement and the position of the minimum radial displacement as the final radial suspension center; and/or the axial displacement extremum comprises an axial displacement maximum and an axial displacement minimum, and the final axial suspension center is calculated based on the following steps: taking the midpoint between the position of the maximum axial displacement and the position of the minimum axial displacement as the final axial suspension center.
In some embodiments, the step of adjusting the current of the radial magnetic bearing specifically comprises: sequentially applying current to the radial magnetic bearing according to the sine and cosine curve to enable the rotor to do circular motion on the protection bearing; and the step of adjusting the current of the axial magnetic bearing specifically comprises: and sequentially applying positive current for a first fixed time and negative current for a second fixed time to the axial magnetic bearing according to a preset axial gradient curve.
In a second aspect, the present disclosure provides an electronic device comprising: a processor; and a memory storing program instructions that, when executed by the processor, cause the apparatus to implement a method according to any one of the first aspects.
In a third aspect, the present disclosure provides a computer-readable storage medium having stored thereon computer-readable instructions which, when executed by one or more processors, implement the method of any of the first aspects.
By the method for determining the suspension center of the rotor of the magnetic suspension molecular pump, when the rotor is controlled to axially suspend according to the designed axial suspension center or the preselected axial suspension center, the final radial suspension center of the rotor is calculated, and at the moment, the influence of the friction force of the rotor and the axial magnetic bearing in the axial direction can be avoided due to the fact that the rotor is suspended in the axial direction, so that the accurate final radial suspension center can be calculated. Similarly, by controlling the rotor to suspend in the radial direction, the final axial suspension center of the rotor is calculated, and the influence of the friction force between the radial magnetic bearing and the rotor can be eliminated, thereby calculating the accurate final suspension center.
Drawings
The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. Several embodiments of the present disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar or corresponding parts and in which:
FIG. 1 illustrates an exemplary block diagram of a magnetic levitation molecular pump according to an embodiment of the present disclosure;
FIG. 2 illustrates an exemplary flow chart of a method of determining a center of rotor levitation of an embodiment of the present disclosure;
FIG. 3 illustrates an exemplary flow chart of a rotor axial levitation method of an embodiment of the present disclosure;
FIG. 4 illustrates an exemplary flow chart of a method of determining a final radial suspension center of an embodiment of the present disclosure;
fig. 5 shows an exemplary block diagram of the electronic device of an embodiment of the present disclosure.
Detailed Description
The following description of the embodiments of the present disclosure will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the disclosure. Based on the embodiments in this disclosure, all other embodiments that may be made by those skilled in the art without the inventive effort are within the scope of the present disclosure.
It should be understood that the terms "comprises" and "comprising," when used in this specification and the claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the present disclosure is for the purpose of describing particular embodiments only, and is not intended to be limiting of the disclosure. As used in the specification and claims of this disclosure, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the term "and/or" as used in the present disclosure and claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
As used in this specification and the claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".
Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
Exemplary application scenarios
When the magnetic suspension molecular pump works normally, the magnetic bearing is required to output certain electromagnetic force to suspend the rotor, and the suspension center of the rotor is required to be consistent with the protection center of the protection bearing, so that the requirement of the rotor on the maximum movable space under the condition of the magnetic bearing support is met.
However, due to the differences of the processing circuits of the magnetic bearing controller, the errors between the installation positions of the probes of the displacement sensor and the design positions, the installation errors of the protection bearings and the displacement sensor, the differences of the lead wires and the adapter, and other factors, the actual value of the suspension center of the rotor supported by the magnetic bearing often has differences from the design value.
In practical application, the size of the magnetic suspension molecular pump can reach 10 2 mm and above, but the suspension distance accuracy of the rotor is 10 -1 mm and below, therefore rotor gravity, installation error and control circuit difference often can cause to a great extent to the difference value of suspension center, still probably lead to the rotor to collide with other parts in the magnetic suspension molecular pump when serious, lead to the magnetic suspension molecular pump to take place serious damage, and the alignment magnetic suspension molecular pump rotor suspension center is the important link of guaranteeing the safe work of magnetic suspension molecular pump.
The technical scheme adopted at present does not consider the influence of gravity, friction force or acting force such as motor permanent magnet magnetic force, and the finally obtained suspension center has poor accuracy, and can not meet the high-precision requirement on the rotor suspension center when the magnetic suspension molecular pump works safely.
Exemplary application scenario
In view of this, the embodiment of the disclosure provides a solution for determining a suspension center of a rotor of a magnetic suspension molecular pump, which determines a radial suspension center when controlling axial suspension of the rotor and determines an axial suspension center when performing radial suspension, so that it can be ensured that the finally determined radial suspension center and axial suspension center both exclude the influence of factors such as friction force, and the accuracy of the suspension center is improved.
Fig. 1 illustrates an exemplary block diagram of a magnetic levitation molecular pump 100 according to an embodiment of the present disclosure, and fig. 2 illustrates an exemplary flowchart of a method 200 of determining a center of levitation of a rotor according to an embodiment of the present disclosure.
As shown in fig. 1, a magnetically levitated molecular pump 100 in an embodiment of the disclosure includes a rotor 10, and axial and radial magnetic bearings 20 and 30 to support the rotor in use. It should be noted that the number of the axial magnetic bearings 20 and the radial magnetic bearings 30 is not strictly limited in the embodiment of the present disclosure, for example, the magnetic levitation molecular pump 100 shown in fig. 1 includes 1 set of axial magnetic bearings 20 and 2 radial magnetic bearings 30 of the first radial magnetic bearing 31 and the second radial magnetic bearing 32. In other embodiments, the magnetic levitation molecular pump 100 may also include 2 or more axial magnetic bearings 20, etc., which are not described herein.
Further, the magnetic levitation molecular pump 100 may further include a protection bearing 50 and a motor stator 60.
In the magnetic levitation molecular pump 100 shown in fig. 1, the current variation of the axial magnetic bearing 20 can control the displacement of the rotor 10 in the rotor length direction, which is also referred to as the axial direction in the embodiment of the present disclosure, i.e. the Z-axis direction in fig. 1, and the final axial levitation center of the rotor needs to be determined by the displacement of the rotor 10 in the rotor length direction. The current variation of the radial magnetic bearing 30 enables control of the displacement of the rotor 10 in a two-dimensional plane of the rotor cross-section, which displacement may include translation and rotation, which displacement may be represented by coordinates in a two-dimensional coordinate system XOY, so it is understood that the radial direction includes a transverse direction and a longitudinal direction, i.e., the X-axis direction and the Y-axis direction in fig. 1, and that the transverse direction and the longitudinal direction are perpendicular to each other, and that the presently disclosed embodiments utilize the displacement of the rotor 10 in the rotor cross-section to determine the final radial levitation center of the rotor.
Further, since the magnetic levitation molecular pump 100 includes two radial magnetic bearings in total of the first radial magnetic bearing 31 and the second radial magnetic bearing 32, the radial direction in the magnetic levitation molecular pump 100 may further include a first lateral direction and a first longitudinal direction, and a second lateral direction and a second longitudinal direction. Based on this, the rotor levitation center to be determined can be further split into 1 final axial levitation center, 2 final transverse levitation centers and 2 final longitudinal levitation centers.
For ease of understanding, embodiments of the present disclosure will be described with reference to fig. 2 by taking the magnetic levitation molecular pump 100 shown in fig. 1 as an example, and the method 200 for determining the levitation center of the rotor according to embodiments of the present disclosure will be described.
As shown in fig. 2, in step S201, the current of the axial magnetic bearing is controlled to suspend the rotor according to the designed axial suspension center or the preselected axial suspension center, and the current of the radial magnetic bearing is adjusted to obtain the radial displacement extremum of the rotor.
When the rotor is successfully suspended in the axial direction, the influence of the force of gravity on the axial direction of the magnetic bearing through the space vector can be counteracted, and meanwhile, the influence of friction force generated by contact between the rotor and the axial magnetic bearing is avoided. On the premise, the current of the radial magnetic bearing is adjusted to ensure that the movement of the rotor in the radial direction is not interfered by gravity and friction, and the acquired radial displacement extreme value of the rotor has higher precision and reliability.
In embodiments of the present disclosure, the magnetically levitated molecular pump has one designed levitation center that includes a designed axial levitation center and a designed radial levitation center. In the execution of step S201, the rotor may be guided to perform axial levitation by using the existing designed axial levitation center preferentially, and when the designed axial levitation center does not meet the requirement of axial levitation, a pre-selected axial levitation center is recalculated to guide the rotor to perform axial levitation.
In some embodiments, a specific process of rotor axial levitation is illustrated in fig. 3, fig. 3 illustrates an exemplary flow chart of a rotor axial levitation method 300 of an embodiment of the disclosure.
As shown in fig. 3, in step S301, it is determined whether the position of the rotor determined based on the designed axial levitation center is within the effective levitation range of the rotor.
If yes, go to step S302; if not, step S303 is performed.
In step S302, the rotor is levitated as designed to axially levitate the center.
In step S303, the current of the axial magnetic bearing is adjusted to obtain an axial displacement extremum of the rotor, and then an axial levitation center of the rotor is calculated according to the axial displacement extremum and is used as a preselected axial levitation center, so that the rotor is levitated according to the preselected axial levitation center.
In the execution of step S303, since there is no levitation center available at this time and located within the effective levitation range of the rotor, it is necessary to directly apply a certain current to the axial magnetic bearing to attract the rotor to the magnetic pole and calculate the preselected axial levitation center. It will be appreciated that since the rotor is not previously radially levitated, the calculated preselected axial levitation center will be affected by gravity and friction to introduce some error and cannot be used as the final axial levitation center.
Further, if the position of the rotor, as determined based on the preselected axial levitation center, is outside of the effective levitation range of the rotor, a predetermined third error code identification may be fed back. And the technician can find an error link according to the error code identification of the error reporting, so that the determination flow of the suspension center is corrected and revised.
By the axial levitation method provided in fig. 3, some embodiments of the present disclosure may use the designed axial levitation center to complete axial levitation of the rotor when the designed axial levitation center meets levitation requirements, improving efficiency; or when the designed axial suspension center does not meet the suspension requirement, a preselected axial suspension center is preliminarily calculated to ensure that the rotor is in an axial suspension state in the final radial suspension center determination process, so that the influence of friction force between the axial magnetic bearing and the rotor and the influence of gravity on the axial direction through a space vector are eliminated.
In step S202, the final radial levitation center of the rotor is calculated from the radial displacement extremum.
In this embodiment, the radial displacement extremum includes a radial displacement maximum and a radial displacement minimum, and step S202 takes a midpoint between the position of the radial displacement maximum and the position of the radial displacement minimum as a final radial suspension center. Since the displacement of the rotor in the radial direction is the displacement on the two-dimensional plane, according to the two-dimensional coordinate system constructed in fig. 1, the displacement can be divided into the X-axis displacement and the Y-axis displacement, taking the X-axis displacement as an example, assuming that the maximum value of the displacement of the rotor on the X-axis is 5 and the minimum value of the displacement is-3, the X-axis coordinate of the final radial suspension center of the rotor is 1, and the Y-axis is the same as the X-axis coordinate.
Further, if the position of the rotor determined based on the final radial levitation center is outside the effective levitation range of the rotor, a predetermined first error code identification may be fed back. And the technician can find an error link according to the error code identification of the error reporting, so that the determination flow of the suspension center is corrected and revised.
In step S203, the current of the radial magnetic bearing is controlled to suspend the rotor according to the final radial suspension center, and the current of the axial magnetic bearing is adjusted to obtain the axial displacement extremum of the rotor.
After determining the final radial levitation center of the rotor in step S202, the final radial levitation center at this time is the accurate usable radial levitation center calculated by excluding the influence of gravity and friction force, so that the rotor can be directly guided to perform radial levitation by using the final radial levitation center, thereby excluding the influence of friction force between the radial magnetic bearing and the rotor and the influence of gravity in the radial direction through the space vector.
In step S204, a final axial levitation center of the rotor is calculated from the axial displacement extremum.
Similarly to the radial displacement extremum, the axial displacement extremum includes an axial displacement maximum and an axial displacement minimum, and step S204 may take a midpoint between the position of the axial displacement maximum and the position of the axial displacement minimum as the final axial suspension center.
Further, if the position of the rotor determined based on the final axial levitation center is outside the effective levitation range of the rotor, a predetermined second error code identification may be fed back. And the technician can find an error link according to the error code identification of the error reporting, so that the determination flow of the suspension center is corrected and revised.
By the method for determining the rotor levitation center shown in fig. 2, the embodiments of the present disclosure may improve the reliability and accuracy of the final determined rotor levitation center by controlling the rotor axial levitation to avoid the interference of friction and gravity to the final radial levitation center calculation process, and similarly, by controlling the rotor radial levitation to avoid the interference of friction and gravity to the final axial levitation center calculation process.
In the disclosed embodiment, the displacement value of the rotor is acquired by a displacement sensor 40 in the magnetic levitation molecular pump. The displacement sensors in the magnetic levitation molecular pump can be classified into radial displacement sensors 41 and axial displacement sensors 42 according to functions, and the radial displacement sensors 41 specifically include: a first lateral displacement sensor and a first longitudinal displacement sensor adjacent to the first radial magnetic bearing and each for measuring a rotor displacement value, and a second lateral displacement sensor and a second longitudinal displacement sensor adjacent to the second radial magnetic bearing and each for measuring a rotor displacement value, the axial displacement sensor 42 being for measuring a displacement value in the rotor axial direction.
Further, since the magnetic levitation molecular pump 100 illustrated in fig. 1 includes 2 radial magnetic bearings, in calculating the final radial levitation center of the rotor, it is necessary to determine the final lateral levitation center and the final longitudinal levitation center of the rotor at the positions of the first radial magnetic bearings and the second radial magnetic bearings, respectively, through the first lateral displacement sensor, the first longitudinal displacement sensor, the second lateral displacement sensor, and the second longitudinal displacement sensor.
The process of determining the final radial levitation center of the magnetic levitation molecular pump 100 is described below with reference to fig. 4, which shows an exemplary flowchart of a method 400 of determining the final radial levitation center of an embodiment of the present disclosure.
As shown in fig. 4, in step S401, the current of the axial magnetic bearing is controlled to levitate the rotor according to the designed axial levitation center or the preselected axial levitation center.
In this embodiment, the execution process of step S401 may refer to the axial levitation method shown in fig. 3, and will not be described in detail herein.
In step S402, currents of the first radial magnetic bearing and the second radial magnetic bearing are adjusted to obtain a first lateral displacement extremum and a second lateral displacement extremum of the rotor in a lateral direction.
In this embodiment, the first lateral displacement extremum is a displacement extremum of the rotor in a lateral direction where the first radial magnetic bearing is located, which is measured by the first lateral displacement sensor; the second lateral displacement extremum is the displacement extremum of the rotor in the lateral direction where the second radial magnetic bearing is located, which is measured by the second lateral displacement sensor.
In order to facilitate distinguishing the first radial magnetic bearing from the second radial magnetic bearing, the lateral direction of the first radial magnetic bearing may be denoted BY AX, the lateral direction of the second radial magnetic bearing may be denoted BY BX, and correspondingly the longitudinal direction of the first radial magnetic bearing may be denoted BY AY, and the longitudinal direction of the second radial magnetic bearing may be denoted BY.
In step S403, final lateral suspension centers of the rotor at the positions of the first radial magnetic bearing and the second radial magnetic bearing are calculated according to the first lateral displacement extremum and the second lateral displacement extremum, respectively.
Similar to step S202 in the previous embodiment, a midpoint between the position of the maximum value of the first lateral displacement and the position of the minimum value of the first lateral displacement may be taken as a final lateral suspension center of the rotor at the position of the first radial magnetic bearing, and similarly, a midpoint between the position of the maximum value of the second lateral displacement and the position of the minimum value of the second lateral displacement may be taken as a final lateral suspension center of the rotor at the position of the second radial magnetic bearing.
In step S404, the currents of the first radial magnetic bearing and the second radial magnetic bearing are controlled to levitate the rotor with a final lateral levitation center at which the first radial magnetic bearing and the second radial magnetic bearing are located, respectively.
In this embodiment, the rotor is guided to float in the transverse direction by using the determined final transverse suspension center, so that the influence of friction force between the radial magnetic bearing and the rotor in the transverse direction is eliminated, and the precise final longitudinal suspension center is solved.
In step S405, currents of the first radial magnetic bearing and the second radial magnetic bearing are adjusted to obtain a first longitudinal displacement extremum and a second longitudinal displacement extremum of the rotor in the longitudinal direction.
In this embodiment, the first longitudinal displacement extremum is a displacement extremum of the rotor in the longitudinal direction of the first radial magnetic bearing, which is measured by the first longitudinal displacement sensor; the second longitudinal displacement extremum rotor is a displacement extremum in the longitudinal direction of the second radial magnetic bearing, which is measured by a second longitudinal displacement sensor.
In step S406, final longitudinal suspension centers of the rotor at the first radial magnetic bearing and the second radial magnetic bearing are calculated according to the first longitudinal displacement extremum and the second longitudinal displacement extremum, respectively.
Similarly to the final transverse levitation center in step S403, in step S406, a midpoint between the position of the maximum value of the first longitudinal displacement and the position of the minimum value of the first longitudinal displacement may be taken as the final longitudinal levitation center of the rotor at the first radial magnetic bearing, and a midpoint between the position of the maximum value of the second longitudinal displacement and the position of the minimum value of the second longitudinal displacement may be taken as the final longitudinal levitation center of the rotor at the second radial magnetic bearing.
The determination of the final radial levitation center is described above in which the final transverse levitation center of the rotor is determined first and then the final longitudinal levitation center of the rotor is determined. In practical application, the determination time sequence of the final transverse suspension center and the final longitudinal suspension center can be exchanged, namely, the final longitudinal suspension center of the rotor is determined first, and then the final transverse suspension center of the rotor is determined.
It will be appreciated that in other embodiments of the present disclosure, the currents of the first and second radial magnetic bearings may also be adjusted after controlling the rotor to levitate according to a designed or preselected axial levitation center to calculate the final longitudinal levitation center of the rotor at the first and second radial magnetic bearings, and then controlling the currents of the first and second radial magnetic bearings to levitate the rotor at the final longitudinal levitation center of the first and second radial magnetic bearings, respectively, to calculate the final transverse levitation center of the rotor at the first and second radial magnetic bearings.
By the method for determining the final radial suspension center shown in fig. 4, the embodiment can accurately find the final radial suspension center where the plurality of radial magnetic bearings are located, and prevent the rotor and the radial magnetic bearings from being collided or rubbed to cause serious damage when the magnetic suspension molecular pump works.
In the determination of the levitation center as shown in the previous embodiments of the present disclosure, it is necessary to obtain the displacement extremum of the rotor by adjusting the current of the axial magnetic bearing and/or the radial magnetic bearing. In the conventional suspension center searching scheme, the current applied to the magnetic bearing is generally increased or decreased linearly, and the displacement rate of the rotor is increased linearly due to lack of buffering of current change, so that the rotor can easily strike the protection bearing, and damage to the magnetic suspension molecular pump is caused.
In view of this problem, some embodiments of the present disclosure provide ways of adjusting the current of radial magnetic bearings and/or axial magnetic bearings as follows.
For the radial magnetic bearing, the embodiment can sequentially apply positive current of a first fixed time and negative current of a second fixed time to the radial magnetic bearing according to a preset radial gradient curve;
for the axial magnetic bearing, the present embodiment may sequentially apply a positive current for a first fixed time and a negative current for a second fixed time to the axial magnetic bearing according to a predetermined axial gradient curve.
It should be noted that the specific values of the first fixed time and the second fixed time may be set according to actual situations, which are not limited only herein.
Wherein the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the axial magnetic bearing,/->Indicating the current applied to the axial magnetic bearing, +.>Representing the weight of the rotor>Design value representing electromagnetic force output by axial magnetic bearing during normal operation, < >> and />Representing the current regulation factor, ">Greater than 0->Greater than 1, t represents the time of application of the current, +.>Representing the included angle between the magnetic pole direction of the axial magnetic bearing and the resultant force direction of the rotor, < >>，/>Indicating vacuum permeability->Representing the magnetic pole area of the axial magnetic bearing, +.>Represents the number of turns of the coil of the axial magnetic bearing, +.>Air gap of the magnetic pole of the axial magnetic bearing and the surface of the rotor is represented, < >>Representing the bias current of the design +.>The distance of the rotor from the center of levitation is expressed and is taken as the radius of the effective levitation range.
In some embodiments, the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the radial magnetic bearing,/->Indicating the current applied to the radial magnetic bearing, < > >Representing the weight of the rotor>Representing the design value of electromagnetic force output by the radial magnetic bearing during normal operation, and />Representing the current regulation factor, ">Greater than 0->Greater than 1, t represents the time of application of the current, +.>Representing the included angle between the direction of the magnetic pole of the radial magnetic bearing and the direction of the resultant force applied by the rotor,/and%>，/>Indicating vacuum permeability->Representing the magnetic pole area of the radial magnetic bearing, +.>Represents the number of turns of the radial magnetic bearing, +.>Air gap of the magnetic pole of the radial magnetic bearing and the surface of the rotor is represented, < >>Representing the bias current of the design +.>The distance of the rotor from the center of levitation is expressed and is taken as the radius of the effective levitation range.
Since the magnetic levitation molecular pump in fig. 1 has two radial magnetic bearings, and the radial direction of each radial magnetic bearing can be further divided into a transverse direction and a longitudinal direction, the radial gradient profile can be further subdivided as follows.
For the determination of the final transverse levitation center of the first radial magnetic bearing, the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the first radial magnetic bearing when determining the final transversal suspension centre where the first radial magnetic bearing is located,/the>Indicating the current applied to the first radial magnetic bearing when determining the final transversal suspension centre where the first radial magnetic bearing is located, +. >And the design value of electromagnetic force output by the normal operation of the first radial magnetic bearing is represented when the rotor is suspended according to the design transverse suspension center of the position of the first radial magnetic bearing.
For the determination of the final longitudinal suspension center of the first radial magnetic bearing, the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the first radial magnetic bearing when determining the final longitudinal levitation center where the first radial magnetic bearing is located,/the first radial magnetic bearing>Indicating the current applied to the first radial magnetic bearing when determining the final longitudinal levitation center at which the first radial magnetic bearing is located, +.>And the design value of electromagnetic force output by the normal operation of the first radial magnetic bearing is represented when the rotor is suspended according to the designed longitudinal suspension center of the position of the first radial magnetic bearing.
For the determination of the final transverse levitation center of the second radial magnetic bearing, the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the second radial magnetic bearing when determining the final transverse suspension centre where the second radial magnetic bearing is located, < >>Indicating the final transverse suspension center at which the second radial magnetic bearing is located, toward the first Current applied by two radial magnetic bearings, +.>And the design value of electromagnetic force output by the normal operation of the second radial magnetic bearing is represented when the rotor is suspended according to the design transverse suspension center of the position of the second radial magnetic bearing.
For the determination of the final longitudinal suspension center of the second radial magnetic bearing, the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the second radial magnetic bearing when determining the final longitudinal levitation center where the second radial magnetic bearing is located, < >>Indicating the current applied to the second radial magnetic bearing when determining the final longitudinal levitation center where the second radial magnetic bearing is located, +.>And the design value of electromagnetic force output by the normal operation of the second radial magnetic bearing is represented when the rotor is suspended according to the designed longitudinal suspension center of the position of the second radial magnetic bearing.
Below are respectively to and />For example, the construction of the axial gradient curve and the radial gradient curve is illustrated.
The construction process of the radial gradient curve is described, when the protection center of the magnetic bearing is searched, a force needs to be applied to the stator of the magnetic bearing, and the force is the levitation force when the magnetic bearing is designed, so that the rotor can quickly reach the protection bearing. Then the suspension force is reduced, and the rotor is kept attached to the protection bearing for a period of time, so that the displacement sensor can stably output the acquired displacement value, and the force is defined as the holding force.
When a radial gradient curve is constructed, the rotor is in an axial suspension state, and the magnetic suspension molecular pump is assumed to be in a standing state, namely, the cross section of the rotor faces the ground, the retaining force of the rotor is minimum when the rotor does not move in the radial direction, and the retaining force takes a value of 0; assuming that the magnetic molecular pump is in a lying position, for example, the length direction of the rotor is parallel to the ground, the holding force of the rotor is the largest when the rotor does not move in the axial direction, and the holding force is equal to the gravity of the rotor, since the magnetic molecular pump comprises two radial magnetic bearings, each radial magnetic bearing provides a holding force of the gravity magnitude of 1/2 of the rotor.
Thus, a gradient curve of the radial magnetic bearing output electromagnetic force can be designed with the gravity of the 1/2 rotor as a boundary, as shown below:
when (when)When (I)>；
When (when)When (I)>；
It can be seen that, in order to ensure that the magnetic levitation molecular pump can be adjusted normally at any angle, the present embodiment requires that each radial magnetic bearing provide electromagnetic force of 1/2 of the rotor gravity to support the rotor at minimum when adjusting the current of the radial magnetic bearing.
The relationship between the current and the force of the magnetic bearing can be obtained according to the electromagnetic theory as follows:
；
where f represents the electromagnetic force output by the magnetic bearing and i represents the coil current.
Based on the electromagnetic theory, the relationship between the electromagnetic resultant force and the control current of the differential magnetic bearing is deduced as follows:
；
wherein ,representing the resultant force of the magnetic bearing->Representing the calculated control current.
Substituting the gradient curve of the designed radial magnetic bearing output electromagnetic force into the relation between the electromagnetic resultant force of the differential magnetic bearing and the control current, the control current curve shown as follows can be obtained:
when (when)When (I)>；
When (when)When (I)>。
Similarly, a determination of the first can be deducedA final longitudinal levitation center at which the radial magnetic bearing is located, and control current curves required for the final transverse levitation center and the final longitudinal levitation center at which the second radial magnetic bearing is located、 and />。
The construction process of the axial gradient curve is described next, when the axial gradient curve is constructed, the rotor is in a radial suspension state, and the magnetic suspension molecular pump is assumed to be in a normal standing state, for example, the cross section of the rotor faces the ground, the retaining force of the rotor is maximum when the rotor does not move in the axial direction, and the retaining force is equal to the gravity of the rotor; assuming that the magnetic suspension molecular pump is in a lying posture, for example, the length direction of the rotor is parallel to the ground, the holding force of the rotor is minimum when the rotor does not move in the axial direction, and the holding force takes a value of 0. In order to ensure that the magnetic levitation molecular pump can be normally adjusted no matter what angle is installed, the retaining force generated by the axial magnetic bearing is required to meet the requirement of the maximum value, namely, the retaining force generated by the axial magnetic bearing is equal to the gravity of the rotor.
Thus, the gradient curve of the axial magnetic bearing output electromagnetic force can be designed with the gravitational force of the rotor as a boundary, as shown below:
when (when)When (I)>，/>；
When (when)When (I)>，/>；
Therefore, in order to ensure that the magnetic levitation molecular pump can be adjusted normally at any angle, the present embodiment requires that the axial magnetic bearing provide electromagnetic force with the minimum amount of rotor gravity to support the rotor when adjusting the current of the axial magnetic bearing.
Substituting the gradient curve of the electromagnetic force output by the axial magnetic bearing into the relation between the electromagnetic resultant force of the differential magnetic bearing and the control current, the current control curve shown as follows can be obtained:
when (when)When (I)>；
When (when)When (I)>；
Wherein, in order to distinguish the radial current control curve and the axial current control curve, the axial current control curve is usedThe included angle between the magnetic pole direction of the axial magnetic bearing and the resultant force direction of the rotor is expressed by +.>Representing the magnetic pole area by->Indicating the number of turns of the coil by->Representing the air gap of the axial magnetic bearing pole with the rotor surface.
The current control curve provided by the embodiment can reduce the influence of the motor permanent magnet on the process of determining the suspension center, reduces the impact risk of suspension center operation on the protection bearing by using soft-change current, reduces the vibration of the magnetic bearing, and reduces the influence of friction force on the process of determining the suspension center.
The above embodiments describe a radial gradient profile under control of which the rotor is moved in the X-axis direction or the Y-axis direction in determining the final radial levitation center of the rotor. In yet other embodiments of the present disclosure, the current of the radial magnetic bearing may also be controlled by another radial curve in determining the final radial levitation center of the rotor such that the rotor performs a circular motion to obtain the radial displacement extremum of the rotor.
Specifically, the radial curve is a sine-cosine curve, and current is sequentially applied to the radial magnetic bearing according to the sine-cosine curve, so that the rotor performs circular motion on the protection bearing, and a radial displacement extreme value of the rotor is obtained.
In this embodiment, the positive current of the first fixed time and the negative current of the second fixed time may be sequentially applied to the axial magnetic bearing according to a predetermined axial gradient curve to obtain an axial displacement extremum of the rotor. The specific expression of the axial gradient curve is described in detail in the foregoing, and will not be repeated here.
Further, some embodiments of the present disclosure may also complete the calculation of the sensitivity coefficient of the displacement sensor after finding the final levitation center of the rotor by the levitation center determining method of any of the above embodiments.
Illustratively, the sensitivity correction coefficient of the displacement sensor is equal to the ratio of the designed protection range to the actual detected protection range, taking the axial direction as an example, assuming that the range of the axial displacement extremum determined by any of the previous embodiments is [ S_Z ] - , S_Z + ]Wherein S_Z + Representing the coordinate value of the position of the maximum value of the actual axial displacement on the Z axis, S_Z - Representing the coordinate value of the position of the minimum value of the actual axial displacement on the Z axis, and designing the magnetic suspension moleculeThe protection range of the design is [ Z ] when the pump is in use - , Z +], wherein ,Z+ Representing the coordinate value of the position of the maximum axial displacement designed by the design scheme of the magnetic suspension molecular pump on the Z axis, Z - Representing the coordinate value of the position of the minimum axial displacement designed by the design scheme of the magnetic suspension molecular pump on the Z axis, the sensitivity correction coefficient is equal to。
In the design process of the magnetic suspension molecular pump, the protection clearance between the protection bearing and the rotor is smaller than the stator clearance between the magnetic bearing and the rotor, and the protection clearance is also smaller than the sensor clearance between the displacement sensor and the rotor, so that the rotor is supported by the protection bearing under the abnormal operation conditions such as power failure, instability and the like, and the rotor is prevented from contacting parts except the protection bearing. The protection gap is fixed, but due to factors such as probe difference of the displacement sensor, stray inductance, contact resistance of the connector, component error of the conditioning circuit and the like, the sensitivity of the displacement sensor and the suspension center are different, which affects the control effect of the magnetic suspension molecular pump control algorithm, so that in the process of adjusting the suspension center, the sensitivity correction coefficient of the displacement sensor needs to be increased to ensure the consistency of the sensitivity of the displacement sensors of all channels, and further the control effect of the magnetic suspension molecular pump control algorithm is ensured.
Corresponding to the foregoing functional embodiments, an electronic device as shown in fig. 5 is also provided in the embodiments of the present disclosure. Fig. 5 shows an exemplary block diagram of the electronic device of an embodiment of the present disclosure.
The electronic device 500 shown in fig. 5 includes: a processor 510; and a memory 520, the memory 520 having stored thereon executable program instructions which, when executed by the processor 510, cause the electronic device to implement any of the methods as described hereinbefore.
In the electronic apparatus 500 of fig. 5, only constituent elements related to the present embodiment are shown. Thus, it will be apparent to those of ordinary skill in the art that: the electronic device 500 may also include common constituent elements that are different from the constituent elements shown in fig. 5.
Processor 510 may control the operation of electronic device 500. For example, the processor 510 controls the operation of the electronic device 500 by executing programs stored in the memory 520 on the electronic device 500. The processor 510 may be implemented by a Central Processing Unit (CPU), an Application Processor (AP), an artificial intelligence processor chip (IPU), etc. provided in the electronic device 500. However, the present disclosure is not limited thereto. In this embodiment, the processor 510 may be implemented in any suitable manner. For example, the processor 510 may take the form of, for example, a microprocessor or processor, and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro) processor, logic gates, switches, application specific integrated circuits (Application Specific Integrated Circuit, ASIC), a programmable logic controller, and an embedded microcontroller, among others.
Memory 520 may be used to store hardware for various data, instructions, etc. that are processed in electronic device 500. For example, the memory 520 may store processed data and data to be processed in the electronic device 500. Memory 520 may store data sets that have been processed or to be processed by processor 510. Further, the memory 520 may store applications, drivers, etc. to be driven by the electronic device 500. For example: the memory 520 may store various programs related to current control, displacement identification, etc., to be executed by the processor 510. The memory 520 may be a DRAM, but the present disclosure is not limited thereto. The memory 520 may include at least one of volatile memory or nonvolatile memory. The nonvolatile memory may include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), flash memory, phase change RAM (PRAM), magnetic RAM (MRAM), resistive RAM (RRAM), ferroelectric RAM (FRAM), and the like. Volatile memory can include Dynamic RAM (DRAM), static RAM (SRAM), synchronous DRAM (SDRAM), PRAM, MRAM, RRAM, ferroelectric RAM (FeRAM), and the like. In an embodiment, the memory 520 may include at least one of a Hard Disk Drive (HDD), a Solid State Drive (SSD), a high density flash memory (CF), a Secure Digital (SD) card, a Micro-secure digital (Micro-SD) card, a Mini-secure digital (Mini-SD) card, an extreme digital (xD) card, a cache (caches), or a memory stick.
In summary, specific functions implemented by the memory 520 and the processor 510 of the electronic device 500 provided in the embodiments of the present disclosure may be explained in comparison with the foregoing embodiments of the present disclosure, and may achieve the technical effects of the foregoing embodiments, which will not be repeated herein.
Alternatively, the present disclosure may also be implemented as a non-transitory machine-readable storage medium (or computer-readable storage medium, or machine-readable storage medium) having stored thereon computer program instructions (or computer programs, or computer instruction codes) which, when executed by a processor of an electronic device (or electronic device, server, etc.), cause the processor to perform part or all of the steps of the above-described methods according to the present disclosure.
While various embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous modifications, changes, and substitutions will occur to those skilled in the art without departing from the spirit and scope of the present disclosure. It should be understood that various alternatives to the embodiments of the disclosure described herein may be employed in practicing the disclosure. The appended claims are intended to define the scope of the disclosure and are therefore to cover all equivalents or alternatives falling within the scope of these claims.

Claims (9)

1. A method of determining a levitation center of a rotor of a magnetic levitation molecular pump, the magnetic levitation molecular pump comprising a rotor, and an axial magnetic bearing and a radial magnetic bearing to support the rotor in use, the method comprising the steps of:
controlling the current of the axial magnetic bearing to enable the rotor to float according to a designed axial suspension center or a preselected axial suspension center, and adjusting the current of the radial magnetic bearing to obtain a radial displacement extremum of the rotor; the step of adjusting the current of the radial magnetic bearing specifically comprises the following steps: sequentially applying positive current of a first fixed time and negative current of a second fixed time to the radial magnetic bearing according to a preset radial gradient curve;
calculating a final radial suspension center of the rotor according to the radial displacement extreme value;
controlling the current of the radial magnetic bearing to enable the rotor to float according to the final radial suspension center, and adjusting the current of the axial magnetic bearing to obtain an axial displacement extreme value of the rotor; the step of adjusting the current of the axial magnetic bearing specifically comprises the following steps: sequentially applying positive current of a first fixed time and negative current of a second fixed time to the axial magnetic bearing according to a preset axial gradient curve; and
And calculating the final axial suspension center of the rotor according to the axial displacement extreme value.
2. The method according to claim 1, characterized in that: the step of suspending the rotor according to a designed axial suspension center or a preselected axial suspension center comprises the following steps:
judging whether the position of the rotor determined based on the designed axial suspension center is within the effective suspension range of the rotor;
if yes, enabling the rotor to float according to the designed axial suspension center; and
if not, the current of the axial magnetic bearing is adjusted to obtain an axial displacement extremum of the rotor, then an axial suspension center of the rotor is calculated according to the axial displacement extremum, and the axial suspension center is used as the preselected axial suspension center, so that the rotor is suspended according to the preselected axial suspension center.
3. The method according to claim 1, characterized in that:
the radial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the radial magnetic bearing,/->Indicating the current applied to the radial magnetic bearing, < >>Representing the weight of the rotor>Design value representing electromagnetic force output by radial magnetic bearing during normal operation, < > > and />Representing the current regulation factor, ">Greater than 0->Greater than 1, t represents the time of application of the current, +.>Indicating the direction of the magnetic pole of the radial magnetic bearing and the rotorAngle of resultant force direction,/>，/>Indicating vacuum permeability->Representing the pole area of the radial magnetic bearing,represents the number of turns of the radial magnetic bearing, +.>Air gap of the magnetic pole of the radial magnetic bearing and the surface of the rotor is represented, < >>Representing the bias current of the design +.>The distance of the rotor deviating from the suspension center is represented, and the value of the distance is the radius of the effective suspension range;
and/or
The axial gradient curve is as follows:
when (when)When (I)>；
When (when)When (I)>；
wherein ,representing the actual value of the electromagnetic force output by the axial magnetic bearing,/->Indicating the current applied to the axial magnetic bearing,representing the weight of the rotor>Design value representing electromagnetic force output by axial magnetic bearing during normal operation, < >> and />Representing the current regulation factor, ">Greater than 0->Greater than 1, t represents the time of application of the current, +.>Representing the included angle between the magnetic pole direction of the axial magnetic bearing and the resultant force direction of the rotor, < >>，/>Indicating vacuum permeability->Representing the magnetic pole area of the axial magnetic bearing, +.>Represents the number of turns of the coil of the axial magnetic bearing, +.>Air gap of the magnetic pole of the axial magnetic bearing and the surface of the rotor is represented, < > >Representing the bias current of the design +.>The distance of the rotor from the center of levitation is expressed and is taken as the radius of the effective levitation range.
4. A method according to any one of claims 1 to 3, characterized in that:
the radial magnetic bearings comprise a first radial magnetic bearing and a second radial magnetic bearing;
the magnetic suspension molecular pump comprises a first transverse displacement sensor and a first longitudinal displacement sensor which are adjacent to the first radial magnetic bearing and are all used for measuring the rotor displacement value, and a second transverse displacement sensor and a second longitudinal displacement sensor which are adjacent to the second radial magnetic bearing and are all used for measuring the rotor displacement value;
the final radial levitation center comprises a final transverse levitation center and a final longitudinal levitation center, and the final radial levitation center is specifically obtained by the following steps:
controlling the current of the axial magnetic bearing to enable the rotor to float according to a designed axial suspension center or a preselected axial suspension center;
adjusting the currents of the first radial magnetic bearing and the second radial magnetic bearing, acquiring a first transverse displacement extreme value measured by the first transverse displacement sensor and in the transverse direction of the rotor, and a second transverse displacement extreme value measured by the second transverse displacement sensor and in the transverse direction of the rotor, and respectively calculating the final transverse suspension center of the rotor at the positions of the first radial magnetic bearing and the second radial magnetic bearing according to the first transverse displacement extreme value and the second transverse displacement extreme value;
Controlling the current of the first radial magnetic bearing and the second radial magnetic bearing to enable the rotor to float at the final transverse suspension center of the position where the first radial magnetic bearing and the second radial magnetic bearing are respectively located;
adjusting the currents of the first radial magnetic bearing and the second radial magnetic bearing, acquiring a first longitudinal displacement extreme value of the rotor in the longitudinal direction, which is measured by the first longitudinal displacement sensor, and a second longitudinal displacement extreme value of the rotor in the longitudinal direction, which is measured by the second longitudinal displacement sensor, and respectively calculating final longitudinal suspension centers of the rotor at the positions of the first radial magnetic bearing and the second radial magnetic bearing according to the first longitudinal displacement extreme value and the second longitudinal displacement extreme value;
wherein the transverse direction and the longitudinal direction are perpendicular to each other and all belong to the radial direction.
5. A method according to any one of claims 1 to 3, further comprising:
if the position of the rotor determined based on the final radial levitation center exceeds the effective levitation range of the rotor, feeding back a predetermined first error code identification; and
if the position of the rotor determined based on the final axial levitation center is beyond the effective levitation range of the rotor, a predetermined second error code identification is fed back.
6. A method according to any one of claims 1 to 3, characterized in that:
the radial displacement extremum includes a radial displacement maximum and a radial displacement minimum, and the final radial suspension center is calculated based on the steps of:
taking the midpoint between the position of the maximum radial displacement and the position of the minimum radial displacement as the final radial suspension center; and/or
The axial displacement extremum comprises an axial displacement maximum value and an axial displacement minimum value, and the final axial suspension center is calculated based on the following steps:
and taking the midpoint between the position of the maximum axial displacement and the position of the minimum axial displacement as the final axial suspension center.
7. The method according to claim 1, characterized in that:
the step of adjusting the current of the radial magnetic bearing specifically comprises:
and applying current to the radial magnetic bearing according to sine and cosine Qu Xianxiang in sequence, so that the rotor performs circular motion on the protection bearing.
8. An electronic device, comprising:
a processor; and
a memory storing program instructions that, when executed by the processor, cause the apparatus to implement the method of any one of claims 1-7.
9. A computer readable storage medium having stored thereon computer readable instructions which, when executed by one or more processors, implement the method of any of claims 1-7.
CN202310927226.5A 2023-07-27 2023-07-27 Method, equipment and medium for determining suspension center of magnetic suspension molecular pump rotor Active CN116663201B (en)

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