Self-adaptive control method for misalignment vibration of magnetic suspension rotor

Abstract

The invention relates to the technical field of magnetic suspension rotor control, in particular to a magnetic suspension rotor misalignment vibration self-adaptive control method, which comprises the following steps: constructing a magnetic suspension multi-span rotor misalignment model, collecting a misalignment displacement signal of a magnetic suspension multi-span rotor, and performing AD conversion on the displacement signal; inputting one branch of the displacement signal after AD conversion into a frequency identification module, and inputting an output signal of the frequency identification module into a repetitive controller; the other branch of the displacement signals after AD conversion is input into an IDPID module, and two branch output signals are connected in parallel; dA conversion is carried out on output signals after parallel connection, then power amplification is carried out, the amplified signals are used for adjusting the control current of the magnetic suspension bearing rotor so as to adjust the electromagnetic force, and misalignment vibration suppression of the magnetic suspension multi-span rotor and stable suspension of magnetic suspension are achieved. According to the invention, the problem of poor double-frequency disturbance suppression effect due to misalignment of the existing magnetic suspension multi-span rotor is solved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic suspension rotor control, and in particular to a magnetic suspension rotor misalignment vibration adaptive control method. Background Art

[0002] When a misalignment fault occurs in a rotating machinery, the relative position and working state of the bearings will change, which will cause a frequency-doubled disturbance signal to be generated in the rotor vibration displacement.

[0003] Magnetic bearings can suspend the rotor through magnetic field force, so that it has no physical contact with the stator, so there is no friction loss and a longer life. It has been found through testing that the 2nd frequency component is dominant in the vibration caused by misalignment of the magnetic bearing rotor, and as the degree of misalignment increases, the proportion of 2nd frequency will further increase. The repetitive controller based on the internal model principle has a good suppression effect on the disturbance signal and has a simple structure and small calculation amount. In recent years, it has been applied to the magnetic bearing system. However, as the speed of the magnetic bearing rotor changes, the disturbance frequency parameter in the repetitive controller must also be adjusted. The speed information can be obtained from the sensor in the magnetic bearing system, but the misalignment signal extraction of the magnetic suspension multi-span rotor cannot be obtained through the internal structure of the magnetic suspension multi-span rotor and the extraction is relatively complex. In the existing literature, repetitive control is mostly applied to the vibration control of the magnetic bearing rotor, such as the literature "Application of repetitive control in vibration suppression of magnetic suspension high-speed rotors" by Han Bangcheng et al., which is rarely mentioned in the vibration suppression of magnetic bearing multi-span rotors. In addition, the existing literature widely uses repetitive control to suppress the fixed-frequency disturbance of the magnetic bearing rotor vibration, but it is difficult to suppress the full-frequency misalignment disturbance of the magnetic bearing multi-span rotor. Summary of the invention

[0004] In view of the shortcomings of the existing methods, the present invention solves the problem that the existing magnetic suspension multi-span rotor misalignment has a poor suppression effect on the double frequency disturbance.

[0005] The technical solution adopted by the present invention is: a method for adaptively controlling the vibration of a magnetically suspended rotor misalignment comprises the following steps:

[0006] Step 1: construct a magnetic suspension multi-span rotor misalignment model, collect the misalignment displacement signal of the magnetic suspension multi-span rotor, and perform AD conversion on the displacement signal;

[0007] As a preferred embodiment of the present invention, the displacement signal is collected by using a displacement sensor.

[0008] As a preferred embodiment of the present invention, the misalignment displacement signal is obtained by the deformation amount of the coupling when there is misalignment between the driving rotor and the driven rotor.

[0009] As a preferred embodiment of the present invention, the deformation formula of the coupling is:

[0010]

[0011] Among them, d is the misalignment, ω is the angular velocity of the rotor rotation, O1 is the center line of the active rotor, O2 is the center line of the driven rotor, and G is the intersection point of the perpendicular line from O1 to O2.

[0012] Step 2: Input one of the displacement signals after AD conversion into the frequency identification module, and input the output signal of the frequency identification module into the repetitive controller; input the other displacement signal after AD conversion into the IDPID module, and connect the two output signals in parallel;

[0013] As a preferred embodiment of the present invention, the frequency identification module includes: an improved ANF module and a frequency identification module, and the signal of the improved ANF module is input into the frequency identification module; wherein the formula of the tracking displacement value of the improved ANF module is:

[0014]

[0015] Where b is a constant, A x and A y are the displacement signals in the x and y directions respectively obtained by the sensor, x1' and x2' are tracking signals respectively, s is the Laplace operator, and α is the phase shift angle.

[0016] As a preferred embodiment of the present invention, the formula for the frequency estimation value of the frequency identification module is:

[0017]

[0018] Among them, k is the integral parameter and its value is greater than 0, x1' and x2' are A x and A y The x- and y-direction tracking displacement values.

[0019] As a preferred implementation of the present invention, an integration method is used to make the frequency estimation value infinitely close to the actual rotational speed frequency, and a compensation link is used to filter out high-frequency noise in the frequency estimation signal.

[0020] Step 3: Perform DA conversion on the parallel output signal, and then perform power amplification, and use the amplified signal to adjust the control current of the magnetic suspension bearing rotor and then adjust the electromagnetic force, so as to achieve the misalignment vibration suppression of the magnetic suspension multi-span rotor and the stable suspension of the magnetic suspension;

[0021] As a preferred embodiment of the present invention, a magnetically suspended rotor misalignment vibration adaptive control system includes: a memory for storing instructions executable by a processor; and a processor for executing the instructions to implement a magnetically suspended rotor misalignment vibration adaptive control method.

[0022] As a preferred embodiment of the present invention, a computer readable medium stores computer program codes, and when the computer program codes are executed by a processor, a method for adaptively controlling the misalignment vibration of a magnetically suspended rotor is implemented.

[0023] Beneficial effects of the present invention:

[0024] 1. The present invention realizes the extraction of displacement signals of magnetically suspended multi-span rotors by improving the ANF module, obtains real-time double frequency signals through the frequency identification module, and realizes the adaptive suppression effect of misalignment signals through the repetitive controller;

[0025] 2. The present invention introduces a driven rotor into the magnetic suspension multi-span rotor misalignment model, and the moving rotor acts on the coupling with a double frequency signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a block diagram of the principle of adaptive control of misalignment vibration of a magnetically suspended rotor according to the present invention;

[0027] Figure 2 This is a schematic diagram of the misaligned structure of a magnetically suspended multi-span rotor;

[0028] Figure 3 The schematic diagram of the adaptive vibration control of the magnetically suspended multi-span rotor misalignment;

[0029] Figure 4 Based on the improved ANF module;

[0030] Figure 5 It is a frequency identification module;

[0031] Figure 6 This is the recognition effect diagram of the 2nd frequency information at different fundamental frequencies;

[0032] Figure 7 This is a diagram showing the suppression effect of misalignment vibration disturbance at different fundamental frequencies;

[0033] Figure 8 This is a diagram showing the noise suppression effect of the parallel system and the non-parallel system after adding white noise. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and embodiments. This figure is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner, and therefore it only shows the components related to the present invention.

[0035] like Figure 1 As shown, a method for adaptively controlling the vibration of a magnetically suspended rotor misalignment comprises the following steps:

[0036] Step 1: construct a magnetic suspension multi-span rotor misalignment model, collect the misalignment displacement signal of the magnetic suspension multi-span rotor, and perform AD conversion on the displacement signal;

[0037] The displacement sensor is used to collect the displacement signal of the misalignment of the magnetically suspended multi-span rotor.

[0038] like Figure 2 , the misalignment between the active rotor and the driven rotor of the magnetic suspension multi-span rotor misalignment model can be analyzed by force to obtain the deformation of the coupling. The formula is:

[0039]

[0040] Among them, d is the misalignment, ω is the angular velocity of the rotor rotation, O1 is the center line of the active rotor, O2 is the center line of the driven rotor, and G is the intersection point of the perpendicular line from O1 to O2.

[0041] From this, the force on the coupling can be obtained. By manually decomposing the force on the coupling, its force conditions in the horizontal and vertical directions can be obtained. Therefore, the force acting on the magnetic bearing rotor due to misalignment is:

[0042]

[0043] Among them, K is the stiffness of the half coupling, and 2ω represents the 2nd frequency disturbance.

[0044] F r The displacement signal A in the x-direction and y-direction of the displacement sensor x and A y There is a linear relationship.

[0045] In summary, it can be seen that in the magnetic levitation multi-span rotor misalignment model, the rotor misalignment will generate a rotational force with a frequency twice the rotor speed, which will cause a 2-fold frequency signal to appear in the rotor system. The 2-fold frequency will also increase with the increase of the misalignment amount. Therefore, by eliminating the 2-fold frequency harmonic component in the rotor, the problem of vibration caused by misalignment of the magnetic levitation rotor can be eliminated.

[0046] Step 2: Input one of the displacement signals after AD conversion into the frequency identification module, and input the output signal of the frequency identification module into the repetitive controller; input the other displacement signal after AD conversion into the IDPID module, and connect the two output signals in parallel;

[0047] The frequency identification module consists of an improved ANF module and a frequency identification module. The improved ANF module is used to obtain the tracking displacement value, and the tracking displacement signal is input into the frequency identification module to obtain the difference between the tracking displacement value and the actual speed. The double frequency signal of the rotor is calculated according to the difference, and the double frequency signal is suppressed by a repetitive controller; and by calculating the frequency signal of the rotor, the convergence parameters are adjusted to improve the convergence speed of the improved ANF module.

[0048] The double frequency signal output by the frequency recognition module is transmitted to the delay link of the repetitive controller to achieve the double frequency suppression effect.

[0049] Figure 3 The control block diagram of the magnetic suspension multi-span rotor system with a double frequency interference signal is shown in FIG. In this system, the displacement signals in the X and Y directions are obtained by the displacement sensor inside the magnetic suspension multi-span rotor and input into the frequency identification module. The double frequency signal is extracted by identifying the frequency signal. The signal is input into the delay link in the repetitive controller, and the double frequency signal is suppressed by the repetitive controller. -sT is the delay link, Q is the low-pass filter link, and K(s) is the dynamic compensator, which can enhance the system's suppression effect on low-frequency harmonics; and the output of the repetitive controller is connected in parallel with the incomplete differential PID controller (Incomplete Differential PID, IDPID) to form a composite structure to enhance the overall stability of the system.

[0050] The repetitive controller may adopt an existing repetitive controller, such as the document “Application of Repetitive Control in Vibration Suppression of Magnetically Suspended High-Speed ​​Rotors” by Han Bangcheng et al.

[0051] Figure 4 In order to improve the schematic diagram of the ANF module, the present invention introduces a phase shift angle α into the existing ANF module. By adjusting the phase shift angle, the stability of the magnetic bearing system and the estimation of the full speed range can be achieved. The signal obtained by the displacement sensor is input into the improved ANF module, and the output signal identical to the input signal can be obtained by calculation. The output expression of the tracking displacement signal of the improved ANF module is:

[0052]

[0053] Where b is a constant, A x and A y are the displacement signals in the x-direction and y-direction respectively obtained by the sensor, z1' and x2' are the tracking signals respectively, s is the Laplace operator, and α is the phase shift angle.

[0054] The present invention introduces a phase shift angle α. Adjusting the phase shift angle can optimize the response characteristics of the notch filter, so that it can maintain a stable estimation in the entire speed range, especially in extremely low speed or high speed change conditions; this makes up for the problem that the traditional notch filter method is unstable at certain specific speeds. After the phase shift angle is introduced, the estimation error of the algorithm is significantly reduced. The speed estimation accuracy can be maintained at a high level, improving the robustness and applicability of the algorithm, significantly shortening the response time in speed change scenarios, and there is no obvious estimation fluctuation.

[0055] The displacement signals in the magnetically suspended rotor system have orthogonal characteristics. After the phase shift angle is introduced, the notch filter ensures the decoupling between the orthogonal signals by adjusting the phase relationship between the signals, making it possible to estimate the rotation speed more stably. At the same time, the existence of the phase shift angle adjusts the dynamic response of the system, ensuring that the notch filter can more accurately match the actual frequency signal of the rotor, thereby improving the system's tolerance to frequency mismatch.

[0056] Figure 5 For the frequency identification module, the tracking displacement signal of the improved ANF module is used as input, and the 2-fold frequency signal is extracted to obtain the frequency estimation value of the frequency identification module. The formula is:

[0057]

[0058] Among them, is the integral parameter and its value is greater than 0; b is a constant used to adjust the convergence speed; A x and A y is the sinusoidal signal output by the sensor, x1′ and x2′ are A x and A y The tracking value of ; α is the phase shift angle.

[0059] In the frequency identification module, because the radial displacement of the rotor changes little in the rigid state, β is used to Simplified, the simplified frequency estimation formula is:

[0060] Ω=β[cosα(A x x2′-A y x1′)+sinα(A x x1′+A y x2′)-sinα(x1′ 2 +x2′ 2 )] (5)

[0061] At the same time, the integration method is used to make the frequency estimation value infinitely close to the actual speed frequency. Finally, the compensation link Q(s) is added to filter out the high-frequency noise in the frequency estimation signal, so that the speed estimation value is more stable and avoids violent fluctuations, thereby achieving the adjustment and improvement of the estimation speed and accuracy of the speed estimation result.

[0062] Step 3: Perform DA conversion on the parallel output signal and then perform power amplification, and use the amplified signal to adjust the control current of the magnetic suspension bearing rotor, so as to achieve the misalignment vibration suppression of the magnetic suspension multi-span rotor and the stable suspension of the magnetic suspension through electromagnetic force;

[0063] The IDPID and the repetitive controller are connected in parallel in the magnetic suspension bearing rotor system to increase the anti-interference ability of the system. The parallel digital signal is converted into an analog signal through DA conversion and input into the power amplifier. The power amplifier converts the received signal into a control current acting on the electromagnetic winding to generate electromagnetic force, thereby realizing the suppression of the misalignment vibration of the magnetic suspension multi-span rotor and the stable suspension of the magnetic suspension system.

[0064] The transfer function of IDPID is:

[0065]

[0066] Among them, K P is the proportionality coefficient, T i is the integration time constant, T d is the differential time constant, T f is the filter coefficient.

[0067] The invention discloses a magnetic suspension rotor misalignment vibration adaptive control system, comprising: a mechanical part composed of a magnetic suspension bearing rotor, a coupling and a driven rotor, an electrical part composed of a displacement sensor, an AD conversion, an IDPID, a frequency identification module, a repetitive controller, a DA conversion and a power amplifier, wherein the rotor displacement signal is connected with the input of the IDPID and the frequency identification module after AD conversion, the output of the frequency identification module is connected with the input of the repetitive control module, the output of the IDPID is connected with the output of the repetitive control module in parallel and then connected with the input of the DA conversion, the output of the DA conversion is connected with the input of the power amplifier, and the output of the power amplifier is connected with the magnetic suspension bearing rotor.

[0068] How the system works:

[0069] Firstly, the displacement signal of the magnetically suspended multi-span rotor is collected by the displacement sensor, and the analog signal collected by the sensor is converted into a digital signal by A / D conversion. Secondly, the digital signal is controlled by incomplete differential PID to realize the stable suspension of the magnetically suspended rotor. At the same time, the signal is tracked by the improved ANF module in the frequency identification module, and the tracking signal and the collected signal are subtracted by the frequency identification algorithm module to obtain the frequency information. Then, the obtained frequency information is input into the repetitive control module to suppress the signal. Finally, the repetitive control module is connected in parallel with the incomplete differential PID and the obtained digital signal is converted into an analog signal by D / A conversion and input into the power amplifier. The power amplifier converts the received signal into a control current acting on the electromagnetic winding to generate a corresponding electromagnetic force, thereby realizing the suppression of the misalignment vibration of the magnetically suspended multi-span rotor and the stable suspension of the magnetic suspension system.

[0070] Figure 6 The rotor rotates at a frequency of 25Hz and changes the frequency to 50Hz in 0.5s. The frequency identification module identifies the twice frequency of the speed, that is, the frequency recognition of the improved ANF module is compared with the existing ANF module. It can be seen that after the improvement, the twice frequency information generated by the misalignment of the magnetic levitation multi-span rotor can be accurately extracted in a shorter time, and the signal can be quickly transmitted to the next link to suppress the misalignment signal, thereby improving the system's suppression ability and response speed to disturbance signals.

[0071] Figure 7 This is the result of suppressing the disturbance signal at different speeds. When the rotor speed changes at 1s, the frequency of the disturbance signal also changes. Under the control of the algorithm, the disturbance signal is further suppressed.

[0072] Figure 8 This is the suppression effect after adding noise when the repeat controller is connected in parallel with IDPID and not in parallel. From the figure, we can see that the parallel system has a better suppression effect on noise.

[0073] To suppress the misalignment vibration of the magnetically suspended multi-span rotor, the corresponding frequency information can be obtained through the rotor displacement sensor, and the frequency information can be input into the repetitive controller to suppress the disturbance signal, and it can be connected in parallel with the IDPID to improve the stability of the system.

[0074] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for adaptively controlling the vibration of a magnetically suspended rotor misalignment, characterized in that: The following steps are involved: Step 1: construct a magnetic suspension multi-span rotor misalignment model, collect the misalignment displacement signal of the magnetic suspension multi-span rotor, and perform AD conversion on the displacement signal; Step 2: Input one of the displacement signals after AD conversion into the frequency identification module, and input the output signal of the frequency identification module into the repetitive controller; input the other displacement signal after AD conversion into the IDPID module, and connect the two output signals in parallel; Step 3: Perform DA conversion on the parallel output signal, and then perform power amplification. The amplified signal is used to adjust the control current of the magnetic suspension bearing rotor and then adjust the electromagnetic force, so as to achieve the suppression of misalignment vibration of the magnetic suspension multi-span rotor and the stable suspension of the magnetic suspension.

2. The magnetic suspension rotor misalignment vibration adaptive control method according to claim 1 is characterized in that: The frequency identification module includes: an improved ANF module and a frequency identification module, and the signal of the improved ANF module is input into the frequency identification module; wherein the formula for tracking displacement value of the improved ANF module is: Where b is a constant, A x and A y are the displacement signals in the x and y directions respectively obtained by the sensor, x1' and x2' are tracking signals respectively, s is the Laplace operator, and α is the phase shift angle.

3. The magnetic suspension rotor misalignment vibration adaptive control method according to claim 2 is characterized in that: The formula for the frequency estimation value of the frequency identification module is: Among them, k is the integral parameter and its value is greater than 0, x1' and x2' are A x and A y The x- and y-direction tracking displacement values.

4. The magnetic suspension rotor misalignment vibration adaptive control method according to claim 3 is characterized in that: The integration method is used to make the frequency estimation value infinitely close to the actual speed frequency, and the compensation link is used to filter out the high-frequency noise in the frequency estimation signal.

5. The magnetic suspension rotor misalignment vibration adaptive control method according to claim 1, characterized in that: The misalignment displacement signal is obtained by the deformation of the coupling when the driving rotor and the driven rotor are misaligned.

6. The magnetic suspension rotor misalignment vibration adaptive control method according to claim 5, characterized in that: The deformation formula of the coupling is: Among them, d is the misalignment, ω is the angular velocity of the rotor rotation, O1 is the center line of the active rotor, O2 is the center line of the driven rotor, and G is the intersection point of the perpendicular line from O1 to O2.

7. The magnetic suspension rotor misalignment vibration adaptive control method according to claim 1, characterized in that: The displacement signal is collected by using displacement sensor.

8. The magnetic suspension rotor misalignment vibration adaptive control system is characterized by: include: a memory for storing instructions executable by a processor; A processor is used to execute instructions to implement the magnetic suspension rotor misalignment vibration adaptive control method as described in any one of claims 1-7.

9. A computer readable medium storing a computer program code, characterized in that: The computer program code, when executed by a processor, implements the magnetic suspension rotor misalignment vibration adaptive control method as described in any one of claims 1 to 7.

Images