Bearingless motor three-ring suspension control method based on eccentric compensation

Abstract

The invention discloses a bearingless motor three-ring suspension control method based on eccentric compensation. Aiming at the problems that a bearingless motor rotor is easy to oscillate and is difficult to suspend stably, eccentric compensation is introduced, and positive feedback generated by rotor eccentricity can be inhibited. In order to solve the problem that overshoot is large in the radial displacement adjusting process, a radial speed ring is introduced on the basis of traditional displacement current double-ring suspension control, when the displacement error is zero, the radial speed given value and the actual radial speed are both zero, and therefore a rotor can move to the given position without overshoot and oscillation. By introducing eccentric compensation and radial speed control, a complicated and difficult-to-control bearingless motor can be equivalent to a traditional servo motor, the design difficulty of controller parameters is reduced, and meanwhile, the stability of a suspension control system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of bearingless motor control, and in particular to a bearingless motor three-ring suspension control method based on eccentricity compensation. Background Art

[0002] A bearing motor is a motor that combines the functions of a motor and a magnetic bearing. Because it has no mechanical friction and does not require lubrication, it is widely used in aerospace, semiconductor manufacturing, life sciences and other fields. However, the radial displacement of the rotor of a bearingless motor is prone to oscillation, and achieving high-precision stable suspension is still a big challenge.

[0003] The reason why the radial displacement of the bearingless motor rotor is difficult to control is the positive feedback caused by the rotor eccentricity. The greater the eccentricity, the more intense the positive feedback, which will make the suspension control system more difficult to stabilize. Even if the suspension control system can be stabilized, the radial displacement of the rotor will overshoot during the adjustment process, reducing the accuracy of suspension control. In addition, the suspension controller has many parameters and is severely coupled with variables such as motor current and rotor radial displacement, so the parameter design is relatively complex. If inappropriate controller parameters are selected, it may lead to increased radial displacement fluctuations and even instability of the suspension control system.

[0004] Therefore, how to ensure that the bearingless motor rotor moves to a given position without overshoot and oscillation while reducing the difficulty of suspension controller parameter design has become a topic that needs to be studied. Summary of the invention

[0005] An embodiment of the present invention provides a three-ring suspension control method for a bearingless motor based on eccentricity compensation. The three-ring suspension control method for a bearingless motor taking eccentricity compensation into consideration proposed by the present invention introduces eccentricity compensation control and radial speed control on the basis of traditional displacement current dual-loop suspension control (the suspension control part of the current bearingless motor adopts displacement current dual-loop control).

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0007] S1, obtain a radial displacement sampling signal x by sampling the displacement sensor installed in the bearingless motor sn . Radial displacement given signal x * Subtract x sn After that, the radial displacement error signal is transmitted to the radial displacement controller APR, and APR outputs the radial speed given signal v x * ;

[0008] S2, according to x sn and displacement sensor gain k sn , get the actual radial velocity signal vx ;

[0009] S3、v x * Subtract v x , the radial velocity error signal is transmitted to the radial velocity controller ASR to obtain the suspension force given signal before compensation;

[0010] S4, the output result of ASR, that is, the suspension force given signal before compensation, minus the output result of the eccentricity compensation controller, to obtain the suspension force given signal F x * ;

[0011] S5, F x * After mathematical model calculation, the suspension current given value i of the bearingless motor can be obtained: x * .

[0012] The three-ring suspension control method for a bearingless motor based on eccentricity compensation provided by an embodiment of the present invention introduces eccentricity compensation to address the problem that the bearingless motor rotor is prone to oscillation and difficult to stably suspend, thereby suppressing the positive feedback generated by the rotor eccentricity. In order to address the problem of large overshoot during radial displacement adjustment, a radial velocity loop is introduced on the basis of the traditional displacement current dual-loop suspension control, so that when the displacement error is zero, the radial velocity set value and the actual radial velocity are both zero, and the rotor can therefore move to a given position without overshoot and oscillation. By introducing eccentricity compensation and radial velocity control, the present invention can make a complex and difficult-to-control bearingless motor equivalent to a traditional servo motor, thereby reducing the difficulty of designing controller parameters and improving the stability of the suspension control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. 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 work.

[0014] Figure 1 A structural block diagram of a three-ring suspension control of a bearingless motor taking eccentricity compensation into consideration provided by the present invention.

[0015] Figure 2 The rotor radial displacement, radial velocity and suspension current waveform of the bearingless motor under the three-loop suspension control considering eccentricity compensation proposed by the present invention and the traditional double-loop control. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention. It can be understood by those skilled in the art that, unless specifically stated, the singular forms "one", "one", "said" and "the" used herein may also include plural forms. It should be further understood that the term "including" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups. It should be understood that when we say that an element is "connected" or "coupled" to another element, it can be directly connected or coupled to other elements, or there may also be intermediate elements. In addition, the "connection" or "coupling" used here may include wireless connection or coupling. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as generally understood by those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0017] The embodiment of the present invention provides a bearingless motor three-ring suspension control method based on eccentricity compensation, such as Figure 1 As shown, the introduction of eccentricity compensation can suppress the positive feedback generated by the rotor eccentricity. On the basis of the traditional displacement current dual-loop suspension control, the introduction of the radial velocity loop can achieve that when the displacement error is zero, the radial velocity set value and the actual radial velocity are both zero, so that the rotor can move to a given position without overshoot and oscillation. By introducing eccentricity compensation and radial velocity control, the present invention can make the complex and difficult-to-control bearingless motor equivalent to a traditional servo motor, reduce the difficulty of designing the controller parameters, and improve the stability of the suspension control system.

[0018] The general process of the method includes:

[0019] S1, obtain a radial displacement sampling signal x by sampling the displacement sensor installed in the bearingless motor sn . Radial displacement given signal x * Subtract x snAfter that, the radial displacement error signal is transmitted to the radial displacement controller APR, and APR outputs the radial speed given signal v x * ;

[0020] S2, according to x sn and displacement sensor gain k sn , get the actual radial velocity signal v x ;

[0021] S3、v x * Subtract v x , the radial velocity error signal is transmitted to the radial velocity controller ASR to obtain the suspension force given signal before compensation;

[0022] S4, the output result of ASR, that is, the suspension force given signal before compensation, minus the output result of the eccentricity compensation controller, to obtain the suspension force given signal F x * ;

[0023] S5, F x * After mathematical model calculation, the suspension current given value i of the bearingless motor can be obtained: x * .

[0024] S6, suspension current given signal i x * Through the equivalent current loop G i (s), and the actual suspension current i is obtained x .

[0025] S7, actual suspension current i x Output to the bearingless motor can generate a controllable suspension force f ix . Controllable suspension force f ix , eccentric force f ex With external force f d Add them together to get the total external force F on the rotor x .

[0026] S8, F x Dividing by the rotor mass m and integrating twice, the radial displacement can be obtained.

[0027] Among them, x sn Divide by k sn Then differentiate with respect to time to get v x .

[0028] The step S4 comprises: in the ASR, the compensation force f is subtracted from the given signal of the suspension force before compensation. c , get the suspension force given signal Fx * ; Among them, the eccentricity compensation controller is based on x sn Generate a compensation force f with the same magnitude and opposite direction as the eccentric force currently applied to the rotor of the bearingless motor c , and f c Introduced to the place where the suspension force is given.

[0029] In this embodiment, the transfer function of the eccentricity compensation controller is: k x is the force displacement coefficient, k sn is the displacement sensor gain, and s is a complex variable. The eccentricity compensation controller can adopt a non-physical controller, specifically a compensation method, which is implemented in the form of code.

[0030] In this embodiment, S5 includes:

[0031] F x * Input suspension force model G mm (s), and output the suspension current given signal i x * , the transfer function of the suspension force model is: k c is the force current coefficient, which is used to characterize the suspension force generated by unit suspension current.

[0032] In this embodiment, S6 includes:

[0033] i x * Input equivalent current loop G i (s), and the actual suspension current i is obtained x , the transfer function of the equivalent current loop is: ω bc is the bandwidth of the equivalent current loop.

[0034] In this embodiment, S7 includes:

[0035] F x =f ix +f ex +f d , f ix =k c i x , f ix =k c i x , f ix represents the controllable suspension force, f ex represents the eccentric force, and x represents the radial displacement of the rotor.

[0036] In this embodiment, the APR adopts a proportional (P) control algorithm, the ASR adopts a proportional-integral (PI) control algorithm, and the suspension current controller adopts a proportional-integral (PI) control algorithm. Figure 2 The present invention proposes the rotor radial displacement, radial velocity and suspension current waveform of the bearingless motor under the three-ring suspension control considering eccentricity compensation and the traditional double-ring control. Under the three-ring suspension control considering eccentricity compensation, the rotor moves from the initial position (x=-200μm) to the displacement given value (x=0μm), and the speed is always greater than or equal to zero, so the rotor will not move in the opposite direction, and there is no overshoot. In addition, under the three-ring suspension control considering eccentricity compensation, the rotor starts to decelerate before reaching the displacement given value. When the rotor moves to the displacement given value, the radial velocity just decreases to zero, and the rotor can be stably suspended at the displacement given value. The radial displacement controller APR adopts a proportional (P) control algorithm, the radial velocity controller ASR adopts a proportional-integral (PI) control algorithm, and the suspension current controller adopts a proportional-integral (PI) control algorithm. After adding eccentricity compensation and radial velocity control, the proportional-integral (PI) parameters in the radial displacement controller APR, the radial velocity controller ASR and the suspension current controller can be designed with reference to the traditional servo motor controller parameter design process.

[0037] Compared with the prior art, the main advantages of this embodiment are:

[0038] 1. The control method proposed in the present invention can make the rotor of the bearingless motor move to a given position without overshoot and oscillation.

[0039] 2. The control method proposed in the present invention can convert the bearingless motor into a traditional servo motor for control, and the parameters in the suspension controller can be designed according to the traditional servo motor controller parameter design process, which reduces the difficulty of suspension controller parameter design.

[0040] 3. In the control method proposed in the present invention, the radial displacement controller can achieve system stability and no steady-state error without integral and differential control. At the same time, the proportional coefficient of the radial displacement controller is decoupled from parameters such as the motor excitation current and the rotor radial displacement.

[0041] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A bearingless motor three-ring suspension control method based on eccentricity compensation, characterized in that: include: S1, obtain a radial displacement sampling signal x by sampling the displacement sensor installed in the bearingless motor sn . Radial displacement given signal x * Subtract x sn After that, the radial displacement error signal is transmitted to the radial displacement controller (Automatic Position Regulator, APR), and the APR outputs the radial speed given signal v x * ; S2, according to x sn and displacement sensor gain k sn , get the actual radial velocity signal v x ; S3、v x * Subtract v x , the radial velocity error signal is transmitted to the radial velocity controller (Automatic Speed ​​Regulator, ASR) to obtain the suspension force given signal before compensation; S4, the output result of ASR, that is, the suspension force given signal before compensation, minus the output result of the eccentricity compensation controller, to obtain the suspension force given signal F x * ; S5. According to F x * , get the suspension current given value i of the bearingless motor x * .

2. The method according to claim 1, characterized in that S2 include: x sn Divide by k sn Then differentiate with respect to time to get v x .

3. The method according to claim 1, characterized in that S4 include: Subtract the compensation force f from the given signal of the uncompensated suspension force c , get the suspension force given signal F x * ; Among them, the eccentricity compensation controller is based on x sn Generate a compensation force f with the same magnitude and opposite direction as the eccentric force currently applied to the rotor of the bearingless motor c .

4. The method according to claim 3, characterized in that The transfer function of the eccentricity compensation controller is: k x is the force displacement coefficient, k sn is the displacement sensor gain, and s is a complex variable.

5. The method according to claim 1, characterized in that S5 include: In the suspension current controller, F x * Input suspension force model G mm (s), and output the suspension current given signal i x * , the transfer function of the suspension force model is: k c is the force current coefficient, which is used to characterize the suspension force generated by unit suspension current; i x * Input equivalent current loop G i (s), and the actual suspension current i is obtained x , the transfer function of the equivalent current loop is: ω bc is the bandwidth of the equivalent current loop; Actual suspension current i x The output is sent to a bearingless motor, which generates a controllable suspension force f ix .

6. The method according to claim 5, characterized in that S5 include: f ix represents the controllable suspension force, f ex represents the eccentric force, and x represents the radial displacement of the rotor.

7. The method according to claim 1, characterized in that APR adopts a proportional (P) control algorithm, ASR adopts a proportional-integral (PI) control algorithm, and the suspension current controller adopts a proportional-integral (PI) control algorithm.

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