Magnetic suspension high-speed rotor field dynamic balance method and system considering unbalanced magnetic pulling force

Abstract

The invention discloses a magnetic suspension high-speed rotor field dynamic balancing method and system considering unbalanced magnetic pulling force, and the method comprises the steps: enabling a magnetic suspension rotor to operate at two rotating speeds in an automatic centering control mode based on a magnetic suspension bearing-rotor simplified model considering the unbalanced magnetic pulling force, acquiring a same-frequency control current of the magnetic bearing at a corresponding rotating speed, and calculating an unbalanced magnetic pulling force; calculating unbalanced magnetic pulling force compensation current according to the unbalanced magnetic pulling force, and subtracting the unbalanced magnetic pulling force compensation current from the same-frequency control current of the magnetic bearing at the balanced rotating speed to obtain rotor unbalanced compensation current; calculating the correction mass according to the relation between the rotor unbalance compensation current and the correction mass; carrying out mass correction on a rotor dynamic balance disc; and adopting a conventional control mode, increasing the speed to the highest operation rotating speed, and checking the dynamic balance effect of the magnetic suspension high-speed rotor. According to the invention, the influence of unbalanced magnetic pulling force on the field dynamic balance precision can be eliminated, and the field dynamic balance precision and efficiency of the magnetic suspension rotor are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of active magnetic bearing control, and in particular to a method and system for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pulling force. Background Art

[0002] The magnetic levitation molecular pump has no mechanical contact, no need for lubrication, high speed, active control and other excellent properties. It meets the higher requirements of vacuum degree and cleanliness of vacuum environment in various high-tech fields and has become an indispensable vacuum equipment in the field of high-end manufacturing.

[0003] Affected by the uneven materials and assembly errors in the production process, there is a deviation between the inertial main axis and the geometric main axis of the rotor, causing the rotor to be unbalanced. Affected by the rotor imbalance, the magnetic levitation molecular pump generates a disturbing centrifugal force during the rotation process. The disturbing centrifugal force is transmitted from the rotor to the bearing seat or the exhaust pipe, which will produce undesirable vibration and noise, and will have a greater adverse effect on some equipment with low vibration requirements, such as electron microscopes, photolithography machines, etc.; Under high speed conditions, the disturbing centrifugal force will excite significant vibrations of the same frequency, increase unnecessary control current, and easily cause the power amplifier to reach saturation. In severe cases, it may even cause the rotor to contact the protective bearing and cause the rotor to fall. Therefore, on-site dynamic balancing of the rotor is the key to the long-term and effective operation of the molecular pump.

[0004] The common field dynamic balancing instruments on the market mainly use the influence coefficient method as the basic principle. They measure the vibration amplitude and phase under multiple test weights through amplitude sensors and key phase sensors to calculate the size and angle of the unbalanced response. This type of dynamic balancing instrument has specific requirements for the installation position of the sensor. For magnetic levitation molecular pumps, the sensor installation requirements are usually not met, so the measured amplitude and phase information is not accurate enough. In addition, due to the existence of various nonlinear factors, traditional field dynamic balancing instruments cannot guarantee the dynamic balancing accuracy in the field dynamic balancing of magnetic levitation molecular pumps.

[0005] The influence of unbalanced magnetic pull on the system's frequency response cannot be ignored at lower speeds (usually near the dynamic balancing speed). If conventional methods are used to ignore the unbalanced magnetic pull and perform on-site dynamic balancing at lower speeds, the calculated correction quality will be inaccurate and the dynamic balancing effect at high speeds will be affected.

[0006] The magnetic levitation molecular pump contains displacement sensors, current sensors, speed sensors, etc. for magnetic bearing control, and the magnetic bearing has the ability of active control. These provide the hardware basis for the on-site dynamic balancing of the magnetic levitation molecular pump, without the need to add additional sensors, and the cost is reduced.

[0007] Compared with patent CN110578703A, the present invention does not need to test weight, and can solve the correction position according to the established magnetic bearing-rotor dynamics model. Compared with patent CN106153256B, the innovation of the present invention is that it takes into account the influence of unbalanced magnetic pull on the on-site dynamic balancing accuracy of the magnetic levitation molecular pump, and separately calculates the magnitude and phase of the unbalanced magnetic pull of the magnetic levitation molecular pump according to the difference between the rotor imbalance and the unbalanced magnetic pull system response. Finally, according to the equivalent relationship between magnetic force, unbalanced magnetic pull and rotor imbalance, the adverse effect of unbalanced magnetic pull on on-site dynamic balancing is eliminated, and the on-site dynamic balancing accuracy of the magnetic levitation molecular pump is improved. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a method for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pull, the method comprising:

[0009] Step S1, based on a simplified magnetic bearing-rotor model taking into account unbalanced magnetic pull, in an automatic centering control mode, the magnetic suspension rotor is operated at two different speeds, the magnetic bearing co-frequency control current at different speeds is obtained, and the unbalanced magnetic pull is calculated based on the magnetic bearing co-frequency control current;

[0010] Step S2, calculating a corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, subtracting the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed, to obtain a rotor imbalance compensation current;

[0011] Step S3, calculating the correction mass according to the relationship between the compensation current of the rotor imbalance and the correction mass, and performing mass correction on the rotor dynamic balancing disk;

[0012] Step S4: Based on the rotor after mass correction, the conventional control mode is adopted to increase the speed to the maximum operating speed to check the on-site dynamic balancing effect of the magnetic suspension molecular pump.

[0013] Optionally, in step S1, the specific process of establishing a simplified magnetic bearing-rotor model considering unbalanced magnetic pull in the automatic centering control mode includes:

[0014] The radial plane where the rotor mass center is located is P0. Under small angle conditions, the rotor inertia axis A I The generalized coordinates are q, and the rotor geometric axis A G The generalized coordinates of G , the relationship between the rotor inertia axis and the geometric axis is expressed as

[0015] q=q G +q u

[0016] The rotor unbalance q uExpressed as

[0017]

[0018] Among them, e, is the amplitude and phase of the static unbalance of the rotor, δ, ψ are the amplitude and phase of the couple unbalance of the rotor; define l a ,l b is the distance between the two radial magnetic bearings a and b and the center of mass of the rotor, l m is the distance from the motor stator to the rotor mass center, l A ,l B is the distance from the correction plane to the rotor mass center; T f ,T m are the coordinate transformation matrices of the magnetic bearing force and the unbalanced magnetic pulling force respectively; K I ,K X are the magnetic bearing current stiffness matrix and displacement stiffness matrix respectively; I is the magnetic bearing drive differential control current, X is the rotor displacement at the magnetic bearing; F m It is an unbalanced magnetic pull, which is characterized by a fixed initial phase, constant amplitude, and the same frequency as the rotation speed;

[0019]

[0020] Among them, f m is the amplitude of the unbalanced magnetic pull, η is the initial phase of the unbalanced magnetic pull;

[0021] Establish a magnetic bearing-rotor dynamics model considering unbalanced magnetic pull and rotor imbalance:

[0022]

[0023] in, are the second-order derivative and first-order derivative of the generalized coordinate q of the rotor inertia axis respectively;

[0024] Automatic centering control is used to make the rotor rotate around its geometric axis. The generalized displacement A of the geometric axis G Approaching 0, only the current stiffness force needs to be calculated when calculating the magnetic bearing force, so the dynamic model is simplified to:

[0025]

[0026] They are q u The second and first derivatives of .

[0027] Optionally, in step S1, based on a simplified magnetic bearing-rotor model considering unbalanced magnetic pull, in an automatic centering control mode, the magnetic suspension rotor is operated at two different speeds of ω1 and ω2, and the same-frequency control current of the magnetic bearing at different speeds is obtained. The specific process of calculating the unbalanced magnetic pull includes:

[0028] The magnetic suspension rotor is made to run at two different speeds ω1 and ω2 respectively, and automatic centering control is adopted to make the rotor rotate around the geometric axis of the magnetic suspension high-speed rotor system;

[0029] The magnetic bearing currents at two rotational speeds ω1 and ω2 are measured respectively, and the magnetic bearing currents at the two rotational speeds are extracted at the same frequency to obtain the same-frequency currents I1 and I2 at two different rotational speeds;

[0030] Magnetic bearing force at two speeds, rotor imbalance, unbalanced magnetic pull F m The equivalent relationship is expressed as:

[0031]

[0032] in

[0033] J z ,J r are the equatorial moment of inertia and polar moment of inertia of the rotor respectively. The unbalanced magnetic pull F is calculated based on the equatorial moment of inertia of the rotor and the polar moment of inertia of the rotor. m .

[0034] Optionally, in step S2, the specific process of calculating the corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, subtracting the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed, and obtaining the rotor unbalance compensation current includes:

[0035] Increase the speed to the equilibrium speed ω, and make the rotor rotate around the geometric axis at the equilibrium speed ω;

[0036] The unbalanced magnetic pull compensation current and the rotor unbalance compensation current are calculated based on the relationship between the unbalanced magnetic pull and the unbalanced magnetic pull compensation current, as shown below:

[0037]

[0038] Among them, I a ,I b are the same frequency control currents of a and b magnetic bearings, I aU ,I bU a, b are the unbalanced compensation currents of the magnetic bearings, I am ,I bm a and b are the unbalanced magnetic pull compensation currents of the magnetic bearings respectively.

[0039] Optionally, in step S3, the correction mass is calculated according to the relationship between the rotor unbalance compensation current and the correction mass; the specific process of performing mass correction on the rotor dynamic balancing disk includes:

[0040] At the speed ω, the correction effect of the automatic centering control is equivalent to that of the correction mass, that is, the force and torque generated by the automatic centering control are equal, thereby solving the size and phase of the correction mass:

[0041]

[0042] Among them, m A ,m B is the corrected mass vector, including magnitude and direction, r A, r B are the correction radii of the A and B correction planes respectively.

[0043] The present invention also discloses a magnetic suspension high-speed rotor on-site dynamic balancing system taking into account unbalanced magnetic pulling force, the system comprising: a model building module, a rotor unbalance compensation current calculation module, a mass correction module and an on-site dynamic balancing effect module;

[0044] The model building module is used to operate the magnetic suspension rotor at two different speeds based on a simplified magnetic suspension bearing-rotor model taking into account unbalanced magnetic pull in an automatic centering control mode, obtain the magnetic bearing co-frequency control current at different speeds, and calculate the unbalanced magnetic pull based on the magnetic bearing co-frequency control current;

[0045] The rotor unbalanced compensation current calculation module is used to calculate the corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, and subtract the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed to obtain the rotor unbalance compensation current;

[0046] The mass correction module is used to calculate the correction mass according to the relationship between the rotor unbalance compensation current and the correction mass and perform mass correction on the rotor dynamic balancing disk;

[0047] The on-site dynamic balancing effect inspection module is used to adopt a conventional control mode to increase the speed to the maximum operating speed and inspect the on-site dynamic balancing effect of the magnetic suspension molecular pump.

[0048] Optionally, in the model building module, the workflow of establishing a simplified magnetic bearing-rotor model considering unbalanced magnetic pull in the automatic centering control mode specifically includes:

[0049] The radial plane where the rotor mass center is located is P0. Under small angle conditions, the rotor inertia axis A I The generalized coordinates are q, and the rotor geometric axis AG The generalized coordinates of G , the relationship between the rotor inertia axis and the geometric axis is expressed as

[0050] q=q G +q u

[0051] The rotor unbalance q u Expressed as

[0052]

[0053] Among them, e, is the amplitude and phase of the static unbalance of the rotor, δ, ψ are the amplitude and phase of the couple unbalance of the rotor; define l a ,l b is the distance between the two radial magnetic bearings a and b and the center of mass of the rotor, l m is the distance from the motor stator to the rotor mass center, l A ,l B is the distance from the correction plane to the rotor mass center; T f ,T m are the coordinate transformation matrices of the magnetic bearing force and the unbalanced magnetic pulling force respectively; K I ,K X are the magnetic bearing current stiffness matrix and displacement stiffness matrix respectively; I is the magnetic bearing drive differential control current, X is the rotor displacement at the magnetic bearing; F m It is an unbalanced magnetic pull, which is characterized by a fixed initial phase, constant amplitude, and the same frequency as the rotation speed;

[0054]

[0055] Among them, f m is the amplitude of the unbalanced magnetic pull, η is the initial phase of the unbalanced magnetic pull;

[0056] Establish a magnetic bearing-rotor dynamics model considering unbalanced magnetic pull and rotor imbalance:

[0057]

[0058] in, are the second-order derivative and first-order derivative of the generalized coordinate q of the rotor inertia axis respectively;

[0059] Automatic centering control is adopted to make the rotor rotate around the geometric axis, and the generalized displacement A of the geometric axis G Approaching 0, only the current stiffness force needs to be calculated when calculating the magnetic bearing force, so the dynamic model is simplified to:

[0060]

[0061] They are q u The second and first derivatives of .

[0062] Optionally, in the current stiffness calculation module, based on a simplified magnetic bearing-rotor model considering unbalanced magnetic pull, in an automatic centering control mode, the magnetic suspension rotor is operated at two different speeds of ω1 and ω2, and the same-frequency control current of the magnetic bearing at different speeds is obtained. The workflow for calculating the unbalanced magnetic pull specifically includes:

[0063] The magnetic suspension rotor is made to run at two different speeds ω1 and ω2 respectively, and automatic centering control is adopted to make the rotor rotate around the geometric axis of the magnetic suspension high-speed rotor system;

[0064] The magnetic bearing currents at two rotational speeds of ω1 and ω2 are measured respectively, and the magnetic bearing currents at the two rotational speeds are extracted at the same frequency to obtain the same-frequency currents I1 and I2 at two different rotational speeds;

[0065] Magnetic bearing force at two speeds, rotor imbalance, unbalanced magnetic pull F m The equivalent relationship is expressed as:

[0066]

[0067] in

[0068] J z , J r are the equatorial moment of inertia and polar moment of inertia of the rotor respectively. The unbalanced magnetic pull F is calculated based on the equatorial moment of inertia of the rotor and the polar moment of inertia of the rotor. m .

[0069] Optionally, the specific workflow of the rotor unbalance compensation current calculation module includes:

[0070] Increase the speed to the equilibrium speed ω, and make the rotor rotate around the geometric axis at the equilibrium speed ω;

[0071] The unbalanced magnetic pull compensation current and the rotor unbalance compensation current are calculated based on the relationship between the unbalanced magnetic pull and the unbalanced magnetic pull compensation current, as shown below:

[0072]

[0073] Among them, I a ,I b are the same frequency control currents of a and b magnetic bearings, I aU ,I bU a, b are the unbalanced compensation currents of the magnetic bearings, I am ,I bma and b are the unbalanced magnetic pull compensation currents of the magnetic bearings respectively.

[0074] Optionally, the workflow of the quality correction module specifically includes:

[0075] At the speed ω, the correction effect of the automatic centering control is equivalent to that of the correction mass, that is, the force and torque generated by the automatic centering control are equal, thereby solving the size and phase of the correction mass:

[0076]

[0077] Among them, m A ,m B is the corrected mass vector, including magnitude and direction, r A, r B are the correction radii of the A and B correction planes respectively.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] The on-site dynamic balancing method for a magnetic suspension molecular pump designed by the present invention taking unbalanced magnetic pulling force into consideration does not require the addition of an additional sensor or the use of an additional dynamic balancing instrument, thereby reducing costs.

[0080] The on-site dynamic balancing method of the magnetic levitation molecular pump designed by the present invention taking into account the unbalanced magnetic pulling force can effectively improve the influence of the unbalanced magnetic pulling force on the dynamic balancing accuracy, and improve the on-site dynamic balancing accuracy of the magnetic levitation molecular pump.

[0081] The on-site dynamic balancing method of the magnetic levitation molecular pump designed by the present invention taking into account the unbalanced magnetic pulling force does not require multiple starts and stops and multiple additions of test weights, thereby improving the efficiency of the on-site dynamic balancing of the magnetic levitation molecular pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0083] Figure 1 This is a simplified schematic diagram of the rotor structure of a magnetic levitation molecular pump according to an embodiment of the present invention;

[0084] Figure 2 This is a block diagram of the automatic centering control of the magnetic levitation molecular pump system according to an embodiment of the present invention;

[0085] Figure 3 The figure is a flow chart of the on-site dynamic balancing method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0086] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0087] Embodiment 1

[0088] A method for on-site dynamic balancing of magnetically suspended high-speed rotors taking into account unbalanced magnetic pull, such as Figure 3 As shown, the method includes:

[0089] Step S1, based on a simplified magnetic bearing-rotor model considering unbalanced magnetic pull, in an automatic centering control mode, the magnetic suspension rotor is operated at two speeds, the magnetic bearing co-frequency control current at the corresponding speed is obtained, and the unbalanced magnetic pull is calculated.

[0090] The simplified schematic diagram of the rotor structure of the magnetic levitation molecular pump is as follows Figure 1 As shown, the radial plane where the rotor mass center is located is P o , the radial plane where the magnetic bearings at the A and B ends are located is P bA ,P bB , the plane where the permanent magnet of the motor is located is P m , define the inertial coordinate system OXYZ, where O is the geometric center of the stator section where the rotor mass center is located, the X and Y axes correspond to the output directions of the radial magnetic bearings, and the Z axis is upward along the stator geometric axis.

[0091] The rotor geometric axis is a G , the axis of inertia is a I The rotor imbalance comes from the misalignment between the geometric axis and the inertia axis caused by factors such as uneven machining. Under small angle conditions, the relationship between the inertia axis and the geometric axis can be expressed as q I =q G +q u ,in e,φ is the amplitude and phase of the rotor static imbalance, δ, is the amplitude and phase of the rotor unbalance. a ,l b is the distance from the magnetic bearing a, b to the rotor mass center, l m is the distance from the motor stator to the rotor mass center, l A ,l B is the distance from the correction plane to the rotor center of mass.

[0092] Therefore, a magnetic bearing-rotor dynamics model considering unbalanced magnetic pull and rotor imbalance is established:

[0093]

[0094] Where T f ,T m is the transfer matrix of magnetic bearing force and unbalanced magnetic pulling force, KI ,K X are the current and displacement stiffness matrices respectively, I is the magnetic bearing drive current, X is the rotor displacement at the magnetic bearing, F m It is an unbalanced magnetic pull, which is an interference force with a fixed initial phase, constant magnitude, and the same frequency as the rotation speed.

[0095] Step S2: Calculate the corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, subtract the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed, and obtain the rotor imbalance compensation current.

[0096] In order to reduce the number of variables involved in the calculation, automatic centering control is used to make the rotor rotate around its geometric axis.

[0097] The speed of the magnetic levitation molecular pump is increased to ω1 and ω2 respectively, and the automatic centering control is adopted to make the rotor rotate around its geometric axis; the magnetic bearing current at the two speeds of ω1 and ω2 is measured respectively, and the same-frequency extraction is performed on it to obtain the same-frequency currents I1 and I2 at the two speeds of ω1 and ω2.

[0098] Step S3, calculating the correction mass according to the relationship between the rotor unbalance compensation current and the correction mass and performing mass correction on the rotor dynamic balancing disk.

[0099] The equivalent relationship between the magnetic bearing force, rotor imbalance, and unbalanced magnetic pull at two speeds S31, ω1, and ω2 can be expressed as:

[0100]

[0101] Where U(ω) is the rotor imbalance. Since the rotor imbalance, unbalanced magnetic pull, and bearing current are all at the same frequency as the speed, the ωt term in the sine and cosine functions can be discarded, and F can be solved. m .

[0102] S32, speed up to the balanced speed ω, and command the rotor to rotate around the geometric axis at the balanced speed ω. At this time, the same-frequency control current consists of two parts, which are used to compensate for the rotor imbalance and unbalanced magnetic pull, namely

[0103] Among them I aU ,I bU a, b are the unbalanced compensation currents of the magnetic bearings, I am ,I bm a and b are the unbalanced magnetic pull compensation currents of the magnetic bearing respectively.

[0104] Build I am ,I bm The relationship between the unbalanced magnetic pull and I am ,I bmThe electromagnetic force generated compensates for the unbalanced magnetic pull

[0105] From this, the rotor unbalance compensation current of a and b magnetic bearings can be calculated

[0106] S33. At the speed ω, the correction effect of the automatic centering control is equivalent to that of the correction mass, that is, the force and torque generated are equal, which can be expressed as follows:

[0107]

[0108] The magnitude and phase of the correction mass are thus calculated.

[0109]

[0110] S34, reduce the speed to zero, add the calculated correction mass, and re-increase the speed to the balanced speed ω, and use the conventional control mode to detect whether the displacement vibration at this time meets the requirements. If it does, complete the on-site dynamic balancing, otherwise, repeat steps S32-S33 until the displacement vibration at the balanced speed meets the requirements. The vibration requirement is less than 1 / 20 of the protection gap.

[0111] Step S4: adopt the conventional control mode, increase the speed to the maximum operating speed, and check the dynamic balancing effect of the magnetic suspension high-speed rotor.

[0112] Embodiment 2

[0113] A magnetic suspension high-speed rotor on-site dynamic balancing system taking into account unbalanced magnetic pulling force, the system comprising: a model building module, a rotor unbalance compensation current calculation module, a mass correction module and an on-site dynamic balancing effect module;

[0114] The model building module is used to operate the magnetic suspension rotor at two different speeds in an automatic centering control mode based on a simplified magnetic suspension bearing-rotor model considering unbalanced magnetic pull, obtain the magnetic bearing co-frequency control current at different speeds, and calculate the unbalanced magnetic pull based on the magnetic bearing co-frequency control current; specifically includes:

[0115] Based on magnetic levitation molecular pump system, such as Figure 2 As shown, the radial plane where the rotor mass center is located is P o , the rotor geometric axis is a G , the axis of inertia is a I The rotor imbalance comes from the misalignment of the geometric axis and the inertia axis. Under small angle conditions, the relationship between the inertia axis and the geometric axis is expressed as q I =q G +q u , Among them, e,φ is the amplitude and phase of the rotor static imbalance, δ, is the amplitude and phase of the rotor unbalance; l a ,l b is the distance from the magnetic bearing a, b to the rotor mass center, l m is the distance from the motor stator to the rotor mass center, l A ,l B The distance from the correction plane to the rotor center of mass is:

[0116] Based on the data of magnetic levitation molecular pump, a magnetic bearing-rotor dynamics model considering unbalanced magnetic pull and rotor imbalance is established:

[0117]

[0118] Where q = q I is the generalized coordinate of the rotor inertia axis, q I =q G +q u ,q G is the generalized coordinate of the rotor geometric axis, and the rotor imbalance can be expressed as e,φ is the amplitude and phase of the rotor static imbalance, δ, is the amplitude and phase of the rotor unbalance, T f ,T m is the transfer matrix of magnetic bearing force and unbalanced magnetic pulling force, K I ,K X are the current and displacement stiffness matrices respectively, I is the magnetic bearing drive current, X is the rotor displacement at the magnetic bearing, F m is the unbalanced magnetic pull, They are the second-order derivative and first-order derivative of the generalized coordinate q of the rotor inertia axis, respectively.

[0119] The rotor unbalanced compensation current calculation module is used to calculate the corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, and subtract the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed to obtain the rotor unbalance compensation current; specifically includes:

[0120] The speed of the magnetic levitation molecular pump is increased to ω1 and ω2 respectively, and the automatic centering control is adopted to make the rotor rotate around the geometric axis of the magnetic levitation molecular pump system;

[0121] The magnetic bearing currents at the two speeds of ω1 and ω2 are measured respectively, and the same-frequency extraction is performed on them to obtain the same-frequency currents I1 and I2 at the two speeds of ω1 and ω2.

[0122] The mass correction module is used to calculate the correction mass according to the relationship between the rotor unbalance compensation current and the correction mass and to perform mass correction on the rotor dynamic balancing disk; the on-site dynamic balancing effect inspection module is used to use the conventional control mode to increase the speed to the maximum operating speed and inspect the on-site dynamic balancing effect of the magnetic suspension molecular pump. Specifically including:

[0123] a. Based on the equivalent relationship between the magnetic bearing force, rotor imbalance and unbalanced magnetic pull at two speeds of ω1 and ω2, the following can be expressed:

[0124]

[0125] Among them, U(ω) is the rotor imbalance. Since the rotor imbalance, unbalanced magnetic pull, and bearing current are all at the same frequency as the speed, the ωt term in the sine and cosine functions can be discarded, and F can be solved. m ;

[0126] b. Increase the speed to the balanced speed ω, and command the rotor to rotate around the geometric axis at the balanced speed ω. At this time, the same-frequency control current consists of two parts, which are used to compensate for the rotor imbalance and unbalanced magnetic pull, namely:

[0127]

[0128] Among them, I aU ,I bU a, b are the unbalanced compensation currents of the magnetic bearings, I am ,I bm a and b are the unbalanced magnetic pull compensation currents of magnetic bearings respectively;

[0129] Build I am ,I bm The relationship between the unbalanced magnetic pull and I m The electromagnetic force generated compensates for the unbalanced magnetic pull

[0130] Calculate the rotor unbalance compensation current of magnetic bearings a and b based on the unbalanced magnetic pull

[0131] c. At the speed ω, the correction effect of the automatic centering control is equivalent to that of the correction mass, that is, the force and torque generated are equal, which can be expressed as follows:

[0132]

[0133] Based on d, the magnitude and phase of the correction mass are calculated:

[0134]

[0135] d. Use the conventional control mode to detect whether the displacement vibration at this time meets the requirements. If it does, complete the on-site dynamic balancing. Otherwise, repeat bc until the displacement vibration at the balancing speed meets the requirements.

[0136] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pull, characterized in that: include: Step S1, based on a simplified magnetic bearing-rotor model taking into account unbalanced magnetic pull, in an automatic centering control mode, the magnetic suspension rotor is operated at two different speeds, the magnetic bearing co-frequency control current at different speeds is obtained, and the unbalanced magnetic pull is calculated based on the magnetic bearing co-frequency control current; Step S2, calculating a corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, subtracting the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed, to obtain a rotor imbalance compensation current; Step S3, calculating the correction mass according to the relationship between the compensation current of the rotor imbalance and the correction mass, and performing mass correction on the rotor dynamic balancing disk; Step S4: Based on the rotor after mass correction, the conventional control mode is adopted to increase the speed to the maximum operating speed to check the on-site dynamic balancing effect of the magnetic suspension molecular pump.

2. The method for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pull according to claim 1, characterized in that: In step S1, the specific process of establishing a simplified magnetic bearing-rotor model considering unbalanced magnetic pull in the automatic centering control mode includes: The radial plane where the rotor mass center is located is P0. Under small angle conditions, the rotor inertia axis A I The generalized coordinates are q, and the rotor geometric axis A G The generalized coordinates of G , the relationship between the rotor inertia axis and the geometric axis is expressed as q=q G +q u The rotor unbalance q u Expressed as Among them, e, is the amplitude and phase of the static unbalance of the rotor, δ, ψ are the amplitude and phase of the couple unbalance of the rotor; define l a ,l b is the distance between the two radial magnetic bearings a and b and the center of mass of the rotor, l m is the distance from the motor stator to the rotor mass center, l A ,l B is the distance from the correction plane to the rotor mass center; T f ,T m are the coordinate transformation matrices of the magnetic bearing force and the unbalanced magnetic pulling force respectively; K I ,K X are the magnetic bearing current stiffness matrix and displacement stiffness matrix respectively; I is the magnetic bearing drive differential control current, X is the rotor displacement at the magnetic bearing; F m It is an unbalanced magnetic pull, which is characterized by a fixed initial phase, constant amplitude, and the same frequency as the rotation speed; Among them, f m is the amplitude of the unbalanced magnetic pull, η is the initial phase of the unbalanced magnetic pull; Establish a magnetic bearing-rotor dynamics model considering unbalanced magnetic pull and rotor imbalance: in, are the second-order derivative and first-order derivative of the generalized coordinate q of the rotor inertia axis respectively; Automatic centering control is used to make the rotor rotate around its geometric axis. The generalized displacement A of the geometric axis G Approaching 0, only the current stiffness force needs to be calculated when calculating the magnetic bearing force, so the dynamic model is simplified to: They are q u The second and first derivatives of .

3. The method for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pull according to claim 1, characterized in that: In step S1, based on the simplified model of magnetic suspension bearing-rotor considering unbalanced magnetic pull, in the automatic centering control mode, the magnetic suspension rotor is operated at two different speeds of ω1 and ω2, and the same-frequency control current of the magnetic bearing at different speeds is obtained. The specific process of calculating the unbalanced magnetic pull includes: The magnetic suspension rotor is made to run at two different speeds ω1 and ω2 respectively, and automatic centering control is adopted to make the rotor rotate around the geometric axis of the magnetic suspension high-speed rotor system; The magnetic bearing currents at two rotational speeds ω1 and ω2 are measured respectively, and the magnetic bearing currents at the two rotational speeds are extracted at the same frequency to obtain the same-frequency currents I1 and I2 at two different rotational speeds; Magnetic bearing force at two speeds, rotor imbalance, unbalanced magnetic pull F m The equivalent relation is expressed as: in J z ,J r are the equatorial moment of inertia and polar moment of inertia of the rotor respectively. The unbalanced magnetic pull F is calculated based on the equatorial moment of inertia of the rotor and the polar moment of inertia of the rotor. m .

4. The method for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pull according to claim 1, characterized in that: In step S2, the corresponding unbalanced magnetic pull compensation current is calculated according to the unbalanced magnetic pull, and the unbalanced magnetic pull compensation current is subtracted from the magnetic bearing co-frequency control current at a balanced speed to obtain the rotor unbalance compensation current. The specific process includes: Increase the speed to the equilibrium speed ω, and make the rotor rotate around the geometric axis at the equilibrium speed ω; The unbalanced magnetic pull compensation current and the rotor unbalance compensation current are calculated based on the relationship between the unbalanced magnetic pull and the unbalanced magnetic pull compensation current, as shown below: Among them, I a ,I b are the same frequency control currents of a and b magnetic bearings, I aU ,I bU a, b are the unbalanced compensation currents of the magnetic bearings, I am ,I bm a and b are the unbalanced magnetic pull compensation currents of the magnetic bearings respectively.

5. The method for on-site dynamic balancing of a magnetically suspended high-speed rotor taking into account unbalanced magnetic pull according to claim 3, characterized in that: In the step S3, the correction mass is calculated according to the relationship between the rotor unbalance compensation current and the correction mass; the specific process of performing mass correction on the rotor dynamic balancing disk includes: At the speed ω, the correction effect of the automatic centering control is equivalent to that of the correction mass, that is, the force and torque generated by the automatic centering control are equal, thereby solving the size and phase of the correction mass: Among them, m A ,m B is the corrected mass vector, including magnitude and direction, r A, r B are the correction radii of the A and B correction planes respectively.

6. A magnetic levitation high-speed rotor on-site dynamic balancing system taking into account unbalanced magnetic pulling force, the magnetic levitation high-speed rotor on-site dynamic balancing system is used to implement the magnetic levitation high-speed rotor on-site dynamic balancing method according to any one of claims 1 to 5, characterized in that: The system comprises: a model building module, a rotor unbalance compensation current calculation module, a mass correction module and an on-site dynamic balancing effect module; The model building module is used to operate the magnetic suspension rotor at two different speeds based on a simplified magnetic suspension bearing-rotor model taking into account unbalanced magnetic pull in an automatic centering control mode, obtain the magnetic bearing co-frequency control current at different speeds, and calculate the unbalanced magnetic pull based on the magnetic bearing co-frequency control current; The rotor unbalanced compensation current calculation module is used to calculate the corresponding unbalanced magnetic pull compensation current according to the unbalanced magnetic pull, and subtract the unbalanced magnetic pull compensation current from the magnetic bearing co-frequency control current at a balanced speed to obtain the rotor unbalance compensation current; The mass correction module is used to calculate the correction mass according to the relationship between the rotor unbalance compensation current and the correction mass and perform mass correction on the rotor dynamic balancing disk; The on-site dynamic balancing effect inspection module is used to adopt a conventional control mode to increase the speed to the maximum operating speed and inspect the on-site dynamic balancing effect of the magnetic suspension molecular pump.

7. The magnetic suspension high-speed rotor on-site dynamic balancing system considering unbalanced magnetic pull according to claim 6, characterized in that: In the model building module, the workflow of establishing a simplified magnetic bearing-rotor model considering unbalanced magnetic pull in the automatic centering control mode specifically includes: The radial plane where the rotor mass center is located is P0. Under small angle conditions, the rotor inertia axis A I The generalized coordinates are q, and the rotor geometric axis A G The generalized coordinates of G , the relationship between the rotor inertia axis and the geometric axis is expressed as q=q G +q u The rotor unbalance q u Expressed as Among them, e, is the amplitude and phase of the static unbalance of the rotor, δ, ψ are the amplitude and phase of the couple unbalance of the rotor; define l a ,l b is the distance between the two radial magnetic bearings a and b and the center of mass of the rotor, l m is the distance from the motor stator to the rotor mass center, l A ,l B is the distance from the correction plane to the rotor mass center; T f ,T m are the coordinate transformation matrices of the magnetic bearing force and the unbalanced magnetic pulling force respectively; K I ,K X are the magnetic bearing current stiffness matrix and displacement stiffness matrix respectively; I is the magnetic bearing drive differential control current, X is the rotor displacement at the magnetic bearing; F m It is an unbalanced magnetic pull, which is characterized by a fixed initial phase, constant amplitude, and the same frequency as the rotation speed; Among them, f m is the amplitude of the unbalanced magnetic pull, η is the initial phase of the unbalanced magnetic pull; Establish a magnetic bearing-rotor dynamics model considering unbalanced magnetic pull and rotor imbalance: in, are the second-order derivative and first-order derivative of the generalized coordinate q of the rotor inertia axis respectively; Automatic centering control is adopted to make the rotor rotate around the geometric axis, and the generalized displacement A of the geometric axis G Approaching 0, only the current stiffness force needs to be calculated when calculating the magnetic bearing force, so the dynamic model is simplified to: They are q u The second and first derivatives of .

8. The magnetic suspension high-speed rotor on-site dynamic balancing system taking into account unbalanced magnetic pull according to claim 6, characterized in that: In the current stiffness calculation module, based on the simplified model of magnetic suspension bearing-rotor considering unbalanced magnetic pull, in the automatic centering control mode, the magnetic suspension rotor is operated at two different speeds of ω1 and ω2, and the same-frequency control current of the magnetic bearing at different speeds is obtained. The workflow of calculating the unbalanced magnetic pull specifically includes: The magnetic suspension rotor is made to run at two different speeds ω1 and ω2 respectively, and automatic centering control is adopted to make the rotor rotate around the geometric axis of the magnetic suspension high-speed rotor system; The magnetic bearing currents at two rotational speeds of ω1 and ω2 are measured respectively, and the magnetic bearing currents at the two rotational speeds are extracted at the same frequency to obtain the same-frequency currents I1 and I2 at two different rotational speeds; Magnetic bearing force at two speeds, rotor imbalance, unbalanced magnetic pull F m The equivalent relation is expressed as: in J z , J r are the equatorial moment of inertia and polar moment of inertia of the rotor respectively. The unbalanced magnetic pull F is calculated based on the equatorial moment of inertia of the rotor and the polar moment of inertia of the rotor. m .

9. The magnetic suspension high-speed rotor on-site dynamic balancing system taking into account unbalanced magnetic pull according to claim 6, characterized in that: The specific workflow of the rotor unbalance compensation current calculation module includes: Increase the speed to the equilibrium speed ω, and make the rotor rotate around the geometric axis at the equilibrium speed ω; The unbalanced magnetic pull compensation current and the rotor unbalance compensation current are calculated based on the relationship between the unbalanced magnetic pull and the unbalanced magnetic pull compensation current, as shown below: Among them, I a ,I b are the same frequency control currents of a and b magnetic bearings, I aU ,I bU a, b are the unbalanced compensation currents of the magnetic bearings, I am ,I bm a and b are the unbalanced magnetic pull compensation currents of the magnetic bearings respectively.

10. The magnetic suspension high-speed rotor on-site dynamic balancing system taking into account unbalanced magnetic pull according to claim 6, characterized in that: The workflow of the quality correction module specifically includes: At the speed ω, the correction effect of the automatic centering control is equivalent to that of the correction mass, that is, the force and torque generated by the automatic centering control are equal, thereby solving the size and phase of the correction mass: Among them, m A ,m B is the corrected mass vector, including magnitude and direction, r A, r B are the correction radii of the A and B correction planes respectively.

Images