A method for suppressing rotor unbalance of a magnetic bearing system and a magnetic bearing system

Abstract

The present application relates to the technical field of magnetic bearing system control, and especially relates to a rotor unbalance suppression method of a magnetic bearing system and the magnetic bearing system, the suppression method comprising the following steps: collecting displacement signals in the running process of a magnetic bearing rotor, and calculating a deviation signal between an actual displacement signal of the rotor and a reference displacement signal; extracting a sine component and a cosine component of the deviation signal; establishing a target function of an unbalance amount according to the sine component and the cosine component; establishing a compensation signal function; establishing an input sensitivity function of the magnetic bearing system; judging whether the rotor unbalance component is effectively suppressed according to the input sensitivity function, the target function and the compensation signal function, and if yes, the unbalance compensation satisfies the compensation requirements of the rotor unbalance suppression process. The present application generates a rotor unbalance compensation amount based on the input sensitivity characteristics of the magnetic bearing system, and can adapt to the rotor unbalance characteristics of the magnetic bearing system at different rotational speeds.

Description

Technical Field

[0001] This invention relates to the field of magnetic bearing system control technology, and in particular to a method for suppressing rotor imbalance in a magnetic bearing system and a magnetic bearing system. Background Technology

[0002] In fields such as high-speed rotating machinery, vacuum and cleanroom systems, and turbine machinery, magnetic bearings, compared to traditional mechanical bearings, rely on electromagnetic force to levitate the rotor, achieving contactless operation between the magnetic bearing and the rotor. Therefore, they require no lubrication, have no frictional losses, and require minimal maintenance. Furthermore, magnetic bearings allow the rotor to operate at extremely high speeds, limited only by the rotor material. In addition, utilizing the active control characteristics of magnetic bearings, the rotor's own mechanical properties and external disturbances can be actively controlled, ensuring stable rotor operation. Therefore, magnetic bearings have wide applications in high-speed rotating machinery.

[0003] A magnetic bearing system typically includes modules such as a controller, displacement sensor, power amplifier, and magnetic bearing-rotor. When the displacement sensor detects a deviation between the actual rotor displacement and the reference displacement, the controller calculates a control signal based on the displacement deviation. This signal is then amplified by the power amplifier and converted into an actual current, driving the magnetic bearing to generate electromagnetic force that suspends the rotor at the reference position. However, during the mechanical manufacturing process, due to machining tolerances and assembly deviations in machining precision and mechanical fit, the rotor's center of mass cannot coincide with its geometric center. Therefore, when the rotor rotates at high speed, the rotor's unbalanced mass introduces unbalanced forces and torques into the system, resulting in an unbalanced current in the magnetic bearing coil that operates at the same frequency as the rotor, as well as unbalanced vibration displacement on the rotor. The magnitude of the unbalanced force is proportional to the square of the rotational speed. As the rotational speed increases, the unbalanced force gradually increases, causing the resulting unbalanced current to also increase. Eventually, this leads to power amplifier output saturation, resulting in unbalanced vibration and other nonlinear vibrations on the rotor. This causes the rotor to fall and violently collide with the protective bearing, ultimately causing significant damage to the equipment.

[0004] Therefore, how to solve the imbalance disturbance caused by rotor imbalance mass is an urgent technical problem that needs to be solved. Summary of the Invention

[0005] To address the imbalance disturbance problem caused by rotor imbalance mass in existing technologies, this invention provides a rotor imbalance suppression method for magnetic bearing systems. This method acquires the sine and cosine components of the rotor imbalance, and determines the sine and cosine components of a compensation signal based on the input sensitivity characteristics of the magnetic bearing system. The compensation signal is then used to eliminate the unbalanced current component at the same frequency, ensuring system stability and control accuracy, thus solving the imbalance disturbance problem caused by rotor imbalance mass in existing technologies.

[0006] The technical solution adopted by this invention to solve its technical problem is: A method for suppressing rotor imbalance in a magnetic bearing system includes the following steps: S1: Collect the displacement signal of the magnetic bearing rotor during operation and calculate the deviation signal e(t) between the actual rotor displacement signal and the reference displacement signal; S2: Extract the sine and cosine components of the deviation signal e(t); S3: Establish the objective function J of the unbalanced quantity based on the sine component and the cosine component; S4: Establish the compensation signal function w(t); S5: Establish the input sensitivity function G of the magnetic bearing system; S6: Determine whether the rotor imbalance component is effectively suppressed based on the input sensitivity function G, the target function J, and the compensation signal function w(t). If yes, proceed to step S7; otherwise, proceed to step S1. S7: The imbalance compensation meets the compensation requirements of the rotor imbalance suppression process.

[0007] Optionally, the sine component e1 and the cosine component e2 of the deviation signal e(t) are obtained by Fourier decomposition.

[0008] Optionally, the deviation signal e(t) is as follows: e(t) = e1sinΩt + e2cosΩt + u(t); where Ω is the rotor rotation angular frequency; t is time; e1 is the amplitude coefficient of the rotor unbalance response on the sine basis; e2 is the amplitude coefficient of the rotor unbalance response on the cosine basis; and u(t) is other control quantity or non-target frequency component.

[0009] Optionally, the objective function J is as follows: , where e1 is the amplitude coefficient of the rotor unbalance response on the sine basis; e2 is the amplitude coefficient of the rotor unbalance response on the cosine basis.

[0010] Optionally, the compensation signal function w(t) is as follows: w(t) = w1sinΩt + w2cosΩt; where Ω is the rotor rotation angular frequency; t is time; w1 is the coefficient of the compensation signal on the sine basis; and w2 is the coefficient of the compensation signal on the cosine basis.

[0011] Optionally, the input sensitivity function G is as follows: .

[0012] Optionally, determining whether the rotor imbalance component is effectively suppressed based on the input sensitivity function G, the target function J, and the compensation signal function w(t) includes: determining the final compensation amount through iterative calculation according to the following formula: .

[0013] Another object of the present invention is to provide a magnetic bearing system, including a controller, the controller including an imbalance compensation module; the imbalance compensation module suppresses the rotor imbalance state by means of the rotor imbalance suppression method of the magnetic bearing system described above.

[0014] Optionally, the controller may further include a dual-throw ratio controller module.

[0015] Optionally, the controller further includes an integration module.

[0016] The beneficial effects of this invention are: The rotor imbalance suppression method for magnetic bearing systems provided by this invention can effectively reduce the unbalanced current component in the magnetic bearing coil current. This invention generates rotor imbalance compensation based on the input sensitivity characteristics of the magnetic bearing system. Compared with other imbalance compensation methods, the imbalance compensation based on the input sensitivity function can adapt to the rotor imbalance characteristics of the magnetic bearing system at different speeds. The generated compensation can theoretically effectively reduce the rotor imbalance current, while avoiding system instability caused by excessively large iteration step size or large phase deviation between the compensation and the imbalance during the compensation calculation process. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the static and dynamic imbalance of the rotor in the magnetic bearing system of this invention; Figure 2 This is a block diagram illustrating the principle of the rotor imbalance suppression method for the magnetic bearing system in this invention. Figure 3 This is a control block diagram of the magnetic bearing system in this invention; Figure 4 This is a block diagram of the various modules of the controller in this invention; Figure 5 This is a schematic diagram of the radial displacement of an existing rotor during high-speed operation; Figure 6 This is a schematic diagram of the control current when the rotor is running at high speed. Figure 7 This is a schematic diagram of the radial displacement frequency domain analysis of an existing rotor during high-speed operation; Figure 8 This is a schematic diagram of the frequency domain analysis of the control current during high-speed operation of the existing rotor; Figure 9 This is a schematic diagram of the radial displacement of the rotor during high-speed operation after applying the rotor imbalance suppression method based on system input sensitivity provided by this invention; Figure 10This is a schematic diagram of the control current during high-speed rotor operation after applying the rotor imbalance suppression method based on system input sensitivity provided by this invention; Figure 11 This is a schematic diagram of the radial displacement frequency domain analysis of the rotor during high-speed operation after applying the rotor imbalance suppression method based on system input sensitivity provided by this invention; Figure 12 This is a schematic diagram of the frequency domain analysis of the control current during high-speed rotor operation after applying the rotor imbalance suppression method based on system input sensitivity provided by this invention.

[0019] In the diagram: 1-Controller; 2-Power Amplifier; 3-Magnetic Bearing-Rotor; 4-Displacement Sensor; 11-Dual Throw Ratio Controller Module; 12-Integral Module; 13-Unbalance Compensation Module. Detailed Implementation

[0020] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] See Figure 1 As shown, rotor imbalance in a magnetic bearing system includes: Static imbalance: Static imbalance is mainly caused by rotor mass eccentricity. When the rotor rotates at high speed, the unbalanced mass generates centrifugal force, which manifests as an unbalanced force with the same frequency as the rotor speed. Assuming the unbalanced mass is located at the outer edge of the rotor and the rotor radius is r, the magnitude of the rotor's static unbalanced force is: F unb =ΔmΩ 2 r; Among them, F unb The unbalanced force is Δm, the unbalanced mass is Ω, the motor speed (angular frequency) is r, and the rotor radius is r. Dynamic imbalance: Dynamic imbalance is mainly caused by uneven mass distribution at different positions along the rotor's axis. When the rotor rotates at high speed, the unbalanced mass generates an unbalanced torque. Assuming the unbalanced mass is located diagonally on both sides of the rotor, and the rotor length is l, the magnitude of the unbalanced torque is: M unb =ΔmΩ 2 r*l / 2.

[0023] Both static and dynamic imbalances introduce synchronous imbalance disturbances into the magnetic bearing system, causing synchronous displacement vibrations in the rotor and generating synchronous imbalance currents in the magnetic bearing coils. In a magnetic bearing system, the unbalanced force and unbalanced torque of the rotor at high speed are caused by errors in the rotor machining and assembly process, and these errors are almost unavoidable. Furthermore, if the unbalance of the rotor is not suppressed, it will lead to a large unbalanced current in the power amplifier and a large unbalanced vibration displacement in the rotor.

[0024] To address the imbalance disturbance caused by rotor imbalance mass in existing technologies, this invention provides a method for suppressing rotor imbalance in a magnetic bearing system. (See [link to relevant documentation]). Figure 2 As shown, the suppression method specifically includes the following steps: S1: Collect the displacement signal of the magnetic bearing rotor during operation and calculate the deviation signal e(t) between the actual rotor displacement signal and the reference displacement signal; Specifically, the displacement sensor of the magnetic bearing system is preferably used to collect the actual displacement signal of the rotor in at least one degree of freedom direction in real time. The controller compares the reference displacement signal with the actual displacement signal to obtain the deviation signal e(t). In the radial magnetic bearing system, the displacement signals in the x and y directions can be collected and calculated separately. In the five-degree-of-freedom magnetic bearing system, the displacement deviation signals of the two radial degrees of freedom, the axial degrees of freedom, and the corresponding angular degrees of freedom can also be processed separately. S2: Extract the sine and cosine components of the deviation signal e(t); Since the rotor imbalance disturbance is mainly manifested as a synchronous component with the same frequency as the rotor speed, after obtaining the deviation signal e(t), the controller extracts the sine and cosine components in the deviation signal e(t) according to the rotor rotation angular frequency Ω. S3: Establish the objective function J of the unbalanced quantity based on the sine and cosine components; The objective function J is used to evaluate the magnitude of the synchronous imbalance component in the deviation signal e(t). When the objective function J is less than the preset threshold or its change is less than the preset threshold, it can be considered that the rotor imbalance component has been effectively suppressed. S4: Establish the compensation signal function w(t); In order to cancel the synchronous unbalance component in the deviation signal e(t), the controller generates a compensation signal function w(t) with the same frequency as the rotor rotation angular frequency Ω. By adjusting the compensation signal function w(t), the compensation signal can perform inverse compensation for the synchronous unbalance component in the deviation signal e(t). S5: Establish the input sensitivity function G of the magnetic bearing system; Specifically, in this step, an input sensitivity function G for the magnetic bearing system is established to characterize the influence of the compensation signal w(t) on the synchronous unbalance component in the deviation signal e(t). The input sensitivity function G can be calculated using a magnetic bearing system model or obtained through experimental identification. For example, when the rotor is at a specified speed, a test compensation signal with known amplitude and phase can be input into the system, and the corresponding deviation signal response can be collected. The input sensitivity function G at that speed can be obtained based on the relationship between input and output. For different speeds, the corresponding input sensitivity function G can be obtained separately, or the input sensitivity function G at the current speed can be obtained through interpolation or model update. Specifically, the input sensitivity function G describes how the system error changes after a given compensation input. From the perspective of the magnetic bearing control system, since the actual magnetic bearing system is not an ideal static system, the compensation signal applied to the power amplifier, electromagnet, and rotor dynamics system will go through a series of dynamic stages before finally manifesting as a change in displacement deviation. Based on this, in order to accurately eliminate unbalance components, this invention introduces the input sensitivity function G to consider the transmission relationship between the compensation input and the error output of the system. Thus, through the dynamic response characteristics of the magnetic bearing system itself, the compensation amount is made closer to the actual required input, rather than simply superimposing the error amplitude in reverse. S6: Determine whether the rotor imbalance component is effectively suppressed based on the input sensitivity function G, the target function J, and the compensation signal function w(t). If yes, proceed to step S7; otherwise, proceed to step S1. Specifically, in this step, the compensation signal function w(t) is updated based on the input sensitivity function G and the synchronous unbalance component in the current deviation signal, and the target function J is calculated; when the target function J is less than the initial value or the set target threshold, or when the target function J is less than the preset target threshold in several consecutive iterations, or when the synchronous unbalance current component is less than the preset current threshold, it is determined that the rotor unbalance component has been effectively suppressed, and the process proceeds to step S7; otherwise, the process returns to step S1. S7: The imbalance compensation meets the compensation requirements of the rotor imbalance suppression process.

[0025] Once the compensation requirements are met, the controller can maintain the current compensation amount or continue to update at a low frequency based on changes in speed, load, or operating status to maintain the suppression effect on the synchronous unbalance component. This invention generates the compensation amount by inputting the sensitivity function G, which avoids the problem of excessive compensation amount or large phase deviation caused by simply relying on empirical step size for iteration. Since the compensation signal is related to the dynamic characteristics of the magnetic bearing system's input and output, it can generate the rotor unbalance compensation amount more accurately at different speeds, thereby reducing the synchronous unbalance current in the magnetic bearing coil and reducing the rotor synchronous unbalance displacement.

[0026] The rotor imbalance suppression method for magnetic bearing systems provided by this invention can effectively reduce the unbalanced current component in the magnetic bearing coil current. This invention generates rotor imbalance compensation based on the input sensitivity characteristics of the magnetic bearing system. Compared with other imbalance compensation methods, the imbalance compensation based on the input sensitivity function can adapt to the rotor imbalance characteristics of the magnetic bearing system at different speeds. The generated compensation can theoretically effectively reduce the rotor imbalance current, while avoiding system instability caused by excessively large iteration step size or large phase deviation between the compensation and the imbalance during the compensation calculation process.

[0027] In this invention, the sine component e1 and the cosine component e2 of the deviation signal e(t) are preferably obtained by Fourier decomposition.

[0028] Since the rotor imbalance disturbance is mainly manifested as a synchronous component with the same frequency as the rotor speed, after obtaining the deviation signal e(t), the controller performs Fourier decomposition on the deviation signal e(t) according to the rotor rotation angular frequency Ω to extract the sine and cosine components in the deviation signal e(t).

[0029] The preferred deviation signal e(t) of this invention is shown in the following equation: e(t)=e1sinΩt+e2cosΩt+u(t); Where Ω is the rotor rotational angular frequency; t is time; e1 is the amplitude coefficient of the rotor unbalanced response on the sine basis; e2 is the amplitude coefficient of the rotor unbalanced response on the cosine basis; and u(t) is other control variables or non-target frequency components.

[0030] In actual control, e1 and e2 can be obtained by multiplying the deviation signal e(t) within one or more rotor rotation cycles with sinΩt and cosΩt respectively and integrating or summing them. Alternatively, e1 and e2 can be extracted by digital phase-locked loop, synchronous demodulation or discrete Fourier transform.

[0031] In this invention, the objective function J is used to evaluate the magnitude of the synchronization imbalance component in the deviation signal e(t). Specifically, the preferred objective function J is shown in the following equation: , where e1 is the amplitude coefficient of the rotor unbalance response on the sine basis; e2 is the amplitude coefficient of the rotor unbalance response on the cosine basis.

[0032] When the absolute values ​​of e1 and e2 are large, it indicates that there is a large synchronous unbalance component in the deviation signal e(t); when e1 and e2 gradually decrease, it indicates that the synchronous unbalance component is gradually suppressed; when the objective function J is less than the preset threshold or its change is less than the preset threshold, it can be considered that the rotor unbalance component has been effectively suppressed.

[0033] The preferred compensation signal function w(t) of this invention is as follows: w(t) = w1sinΩt + w2cosΩt; where Ω is the rotor rotation angular frequency; t is time; w1 is the coefficient of the compensation signal on the sine basis; and w2 is the coefficient of the compensation signal on the cosine basis.

[0034] By adjusting w1 and w2, the amplitude and phase of the compensation signal can be adjusted simultaneously, enabling the compensation signal to perform anti-phase compensation for the synchronous unbalance component in the deviation signal e(t). When the rotor unbalance can be completely compensated, we have: .

[0035] The input sensitivity function G is used to characterize the influence of the compensation signal w(t) on the deviation signal e(t); specifically, the preferred input sensitivity function G in this invention is as follows: , where e(s) is the expression of the deviation signal e(t) in the complex frequency domain, and w(s) is the expression of the compensation signal w(t) in the complex frequency domain.

[0036] The present invention preferably determines whether the rotor imbalance component is effectively suppressed based on the input sensitivity function G, the target function J, and the compensation signal function w(t), including: determining the final compensation amount through iterative calculation according to the following formula: Where w(n) is the compensation amount after the nth iteration, w(n-1) is the compensation amount after the (n-1)th iteration, and G -1 Let G be the inverse of the input sensitivity function G, and e(n) be the synchronization imbalance component obtained in the nth iteration.

[0037] Specifically, the ultimate effect of the compensation amount w is to minimize the objective function J, that is, to minimize the controller input imbalance, at which point: ; Substituting the input deviation e and the sensitivity function G into this partial derivative, we get: ; The iterative relationship of the unbalance compensation amount determined by this formula shows that the final compensation amount w can completely compensate for the unbalance component in the input deviation e.

[0038] That is, the preferred method of this invention is for the controller to iteratively update the compensation amount based on the input sensitivity function G and the synchronous imbalance component e(n) in the current deviation signal. The above iterative relationship shows that in each iteration, the controller calculates the compensation correction amount to offset the synchronous imbalance component based on the currently detected synchronous imbalance component e(n) and the inverse of the input sensitivity function G, and adds the compensation correction amount to the compensation amount w(n-1) of the previous moment or the previous iteration cycle to obtain a new compensation amount w(n). When the objective function J is less than the preset target threshold, or the change in the objective function J is less than the preset change threshold in several consecutive iterations, or the synchronous imbalance current component is less than the preset current threshold, it can be determined that the rotor imbalance component has been effectively suppressed, and the process proceeds to step S7; otherwise, the displacement signal continues to be acquired and the compensation amount is updated.

[0039] This invention reduces the unbalanced component current in the power amplifier by introducing a rotor imbalance compensation module, thereby reducing the output of the synchronous electromagnetic force in the magnetic bearing and preventing the power amplifier output from saturating. Ultimately, this causes the rotor to rotate around its inertial axis, reducing rotor vibration displacement.

[0040] In summary, this invention provides a rotor imbalance suppression method based on system input sensitivity, which can effectively reduce the imbalance component of the controller output, reduce the output current of the power amplifier, reduce rotor displacement vibration, and improve the suspension stability and reliability of the rotor of the magnetic bearing system under high-speed rotation operation.

[0041] Currently, to address the imbalance disturbance of the rotor in a magnetic bearing system under high-speed rotation, the common approach is to optimize the controller parameters and increase the phase margin of the system controller to attenuate the imbalance disturbance. However, when the frequency of the imbalance disturbance is high, increasing the phase margin of the controller has limited effect, and therefore cannot suppress the rotor vibration caused by the rotor imbalance. This invention is based on the fact that the source of unbalanced force and unbalanced torque is the error in the rotor machining and assembly process, and this error is almost unavoidable. To solve the imbalance disturbance caused by unbalanced mass, this invention proposes a rotor imbalance suppression method based on the input sensitivity of the magnetic bearing system. That is, an imbalance suppression module is added to the controller. By generating a compensation signal that is completely opposite to the frequency signal in the rotor that is in sync with the rotational speed, the same-frequency unbalanced current signal in the magnetic bearing coil is almost eliminated, avoiding saturation of the controller and power amplifier outputs. At the same time, the rotor rotates around its inertial axis, reducing the unbalanced displacement in the rotor and improving the stability of the magnetic bearing system.

[0042] Another object of the present invention is to provide a magnetic bearing system, see [link to previous document]. Figure 3As shown, the magnetic bearing system includes a controller 1, and may also include a power amplifier 2, a magnetic bearing rotor 3, and a displacement sensor 4. The controller 1 is implemented by a DSP (Digital Signal Processor), which can calculate the deviation between the rotor displacement signal detected by the displacement sensor 4 and the reference displacement, and output the actual control quantity (such as the duty cycle signal of the power amplifier switching element). It drives the power amplifier through an internal PWM drive circuit or an external drive circuit, and is the actual implementation unit of the control algorithm. The controller 1 hardware consists of analog circuits including a central processing unit (CPU), memory, analog-to-digital / digital-to-analog converter, etc. It stores the software low-level and logic layer programs in memory and drives the various parts to work together. The software logic consists of a reference displacement and feedback displacement signal deviation, a displacement deviation signal calculation section, and a drive output section that converts the calculated value into a switch duty cycle signal. This module executes the control algorithm calculation for the magnetic bearing system. Power amplifier 2 is a switching circuit composed of MOSFET switching transistors or IGBTs and power diodes, connected to an external DC power supply. It can drive the magnetic bearing coil to generate current, thereby controlling the electromagnetic force output of the magnetic bearing. Magnetic bearing-rotor 3 is the actuator part of the magnetic bearing system. When current flows through the magnetic bearing coil, it generates an electromagnetic attraction on the magnetic bearing rotor. By controlling the current of the magnetic bearing coil, the electromagnetic force of the magnetic bearing is controlled to provide adjustable stiffness and damping to the rotor, thereby ensuring the stable levitation of the rotor. Displacement sensor 4 is used to detect and feedback the actual displacement signal of the rotor in real time and input the signal to controller 1, enabling closed-loop control of the magnetic bearing rotor displacement.

[0043] Specifically, the controller 1 of the present invention preferably includes an imbalance compensation module 13; the imbalance compensation module 13 suppresses the unbalanced state of the rotor through the rotor imbalance suppression method of the magnetic bearing system described above.

[0044] Specifically, the imbalance compensation module 13 is used to acquire or receive the deviation signal e(t), extract the sine component e1 and the cosine component e2 from the deviation signal e(t), and establish the objective function J=e1. 2 +e2 2 The compensation signal w(t) = w1sinΩt + w2cosΩt is generated iteratively based on the input sensitivity function G to suppress the rotor synchronous imbalance component.

[0045] This invention adds an unbalanced compensation module 13 to the controller 1 to perform Fourier decomposition on the rotor displacement signal to determine the sine and cosine components of the rotor unbalance. At the same time, based on the input sensitivity characteristics of the magnetic bearing system, the sine and cosine components of the compensation signal are determined, so that the compensation signal can almost eliminate the same-frequency unbalanced current component in the controller 1, thereby ensuring the stability and control accuracy of the system.

[0046] The magnetic bearing system provided by this invention can effectively reduce the unbalanced current component in the magnetic bearing coil current. This invention generates rotor unbalance compensation based on the input sensitivity characteristics of the magnetic bearing system. Compared with other unbalance compensation methods, the unbalance compensation based on the input sensitivity function can adapt to the rotor unbalance characteristics of the magnetic bearing system at different speeds. The generated compensation can theoretically effectively reduce the rotor unbalanced current, while avoiding system instability caused by excessively large iteration step size or large phase deviation between the compensation and unbalance during the compensation calculation process.

[0047] Furthermore, the controller 1 in this invention may also include a conventional dual-throw ratio controller module 11 and an integral module 12. The dual-throw ratio controller module 11 is a phase-lead controller. Since the magnetic bearing itself is a negative stiffness system, the negative feedback signal provides positive stiffness and damping to the magnetic bearing system through the dual-throw ratio controller module 11, ensuring the stability of the system. The integral module 12 is used to eliminate the static difference between the actual rotor displacement and the reference displacement, so that the rotor is suspended at the reference displacement set position.

[0048] The dual-throw ratio controller module 11 is in the continuous domain form as follows: ; In the formula, k p ζ is the gain of the dual-throw ratio controller, and ζ is the damping ratio of the dual-throw ratio controller, with a value between 0 and 2; ω z and ω p These correspond to the zero-point frequency and the pole frequency, respectively, where ω z Less than ω p The dual-throw ratio controller functions similarly to a traditional PD (proportional-derivative) controller (which provides greater phase compensation than the PD controller), providing positive stiffness and damping for the magnetic bearing system.

[0049] The block diagram of each module of the controller in this invention is as follows: Figure 4 As shown, during the operation of the magnetic bearing system provided by the present invention, the controller 1 first realizes the stable suspension control of the rotor through the dual-throw ratio controller module 11 and the integral module 12; when the rotor speeds up or runs at high speed, the imbalance compensation module 13 compensates for the synchronous imbalance component of the rotor according to the system input sensitivity function G.

[0050] The working principle of the magnetic bearing system provided by this invention is as follows: the displacement sensor detects the rotor displacement in real time and inputs the corresponding voltage signal into the controller; the controller calculates the deviation between the reference displacement and the actual feedback displacement signal of the rotor and outputs a coil current reference command, and converts the current reference command into the duty cycle of the power amplifier switching element; after receiving the switching drive signal output by the controller, the power amplifier drives the magnetic bearing coil to generate current, thereby adjusting the electromagnetic force of the magnetic bearing to make the rotor stably levitate at the reference position.

[0051] It should be noted that the magnetic bearing system provided by the present invention can use the unbalance compensation module 13 alone, or the unbalance compensation module 13 can be used in conjunction with other control modules, depending on actual needs.

[0052] With the cooperation of the above control modules, the magnetic bearing system provided by the present invention can effectively reduce the synchronous current and synchronous displacement vibration caused by rotor imbalance while ensuring the stability of the foundation suspension, thereby improving the stability and reliability of the system under high-speed operation.

[0053] To verify the technical effect of the present invention, a specific application example is provided.

[0054] See Figures 5-8 As shown, without applying the rotor imbalance suppression method based on system input sensitivity provided by this invention, the rotor generates significant synchronous imbalance vibration during high-speed rotation. Taking the rotor radial displacement hx as an example, the rotor amplitude is close to 15μm, and the control current fluctuation amplitude exceeds 1A. Figure 7 , Figure 8 This corresponds to the frequency domain distribution of rotor displacement and control current. At this time, the rotational speed is 75Hz, and the corresponding displacement at the same frequency is approximately 9.23μm; the component of the control current at the same frequency is approximately 0.81A.

[0055] Figures 9-12 After applying the rotor imbalance suppression method based on system input sensitivity provided by this invention, and... Figures 5-8 Under the same rotational speed conditions, the rotor displacement of the magnetic bearing and the control effect of the control current were compared. The rotor amplitude was reduced to about 7.5 μm, and the control current fluctuation amplitude was about 0.5 A. Figure 11 , Figure 12 The frequency domain distribution of the magnetic bearing rotor displacement and its control current under the same rotational speed conditions after applying the present invention is as follows: the rotor displacement at the same frequency decreases from 9.2μm to 5.6μm; the rotor control current component at the same frequency decreases from 0.81A to about 0.1A, and after compensation, it is only 12.3% of the original unbalanced current component.

[0056] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for suppressing rotor imbalance in a magnetic bearing system, characterized in that, Includes the following steps: S1: Collect the displacement signal of the magnetic bearing rotor during operation and calculate the deviation signal e(t) between the actual rotor displacement signal and the reference displacement signal; S2: Extract the sine and cosine components of the deviation signal e(t); S3: Establish the objective function J of the unbalanced quantity based on the sine component and the cosine component; S4: Establish the compensation signal function w(t); S5: Establish the input sensitivity function G of the magnetic bearing system; S6: Determine whether the rotor imbalance component is effectively suppressed based on the input sensitivity function G, the target function J, and the compensation signal function w(t). If yes, proceed to step S7; otherwise, proceed to step S1. S7: The imbalance compensation meets the compensation requirements of the rotor imbalance suppression process.

2. The rotor imbalance suppression method for a magnetic bearing system as described in claim 1, characterized in that, The sine component e1 and the cosine component e2 of the deviation signal e(t) are obtained by Fourier decomposition.

3. The rotor imbalance suppression method for a magnetic bearing system as described in claim 2, characterized in that, The deviation signal e(t) is given by the following formula: e(t) = e1sinΩt + e2cosΩt + u(t); where Ω is the rotor rotation angular frequency; t is time; e1 is the amplitude coefficient of the rotor unbalance response on the sine basis; e2 is the amplitude coefficient of the rotor unbalance response on the cosine basis; and u(t) is other control quantities or non-target frequency components.

4. The rotor imbalance suppression method for a magnetic bearing system as described in claim 3, characterized in that, The objective function J is shown in the following equation: , where e1 is the amplitude coefficient of the rotor unbalance response on the sine basis; e2 is the amplitude coefficient of the rotor unbalance response on the cosine basis.

5. The rotor imbalance suppression method for a magnetic bearing system as described in claim 1, characterized in that, The compensation signal function w(t) is as follows: w(t) = w1sinΩt + w2cosΩt; where Ω is the rotor rotation angular frequency; t is time; w1 is the coefficient of the compensation signal on the sine basis; and w2 is the coefficient of the compensation signal on the cosine basis.

6. The rotor imbalance suppression method for a magnetic bearing system as described in claim 1, characterized in that, The input sensitivity function G is shown in the following formula: .

7. The rotor imbalance suppression method for a magnetic bearing system as described in claim 6, characterized in that, Determining whether the rotor imbalance component is effectively suppressed based on the input sensitivity function G, the target function J, and the compensation signal function w(t) includes: determining the final compensation amount through iterative calculation according to the following formula: .

8. A magnetic bearing system, characterized in that, The system includes a controller, which includes an imbalance compensation module; the imbalance compensation module suppresses the rotor imbalance state using the rotor imbalance suppression method of the magnetic bearing system as described in any one of claims 1-7.

9. The magnetic bearing system as claimed in claim 8, characterized in that, The controller also includes a dual-throw ratio controller module.

10. The magnetic bearing system as claimed in claim 8, characterized in that, The controller also includes an integration module.

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