Bearingless motor vibration suppression strategy based on frequency band expansion type finite-dimensional repetitive controller

Abstract

The invention discloses a bearingless motor vibration suppression strategy based on a frequency band expansion type finite-dimensional repetitive controller. Comprising the following steps: starting a system; sampling a signal required at the current moment and setting a displacement reference value Pref; a displacement error signal E at the current moment is collected and input into the frequency band expansion type finite-dimensional repetitive controller, and a displacement adjustment value Ps at the current moment is obtained; inputting the displacement regulation value Ps into a displacement regulator to obtain a suspension current reference value iLref at the current moment; inputting the suspension current reference value iLref into a current regulator to complete suspension current closed-loop control; and repeating the steps II to IV. The method has the advantages that the tracking frequency band width of a traditional repetitive controller near a set frequency point is widened, the signal tracking gain of the traditional repetitive controller at the frequency point is increased, and the adjustment of the tracking frequency band width near the set frequency point is realized; the problems that a traditional repetitive controller cannot update the tracking signal frequency in real time and cannot adapt to the frequency conversion working condition are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of bearingless motor drive, and in particular to a bearingless motor vibration suppression strategy based on a frequency band expansion type finite dimensional repetitive controller. Background Art

[0002] Bearingless motors, with their significant advantages such as long life, high sealing, zero wear, and high power density, have proven themselves particularly well-suited for high-speed drive and high-purity applications in aerospace, semiconductor manufacturing, medical devices, and the chemical industry. However, in practice, due to non-ideal factors such as machining and assembly process errors and device characteristic errors, systems often face challenges such as mass imbalance, sensor interference, and electromagnetic disturbances. These factors, combined, can easily cause vibration and noise during operation, particularly at high speeds, potentially leading to stator-rotor friction. In severe cases, this can even cause system instability and compromise equipment safety. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a bearingless motor vibration suppression strategy based on a frequency band expansion finite dimensional repetitive controller which has a simple structure, is easy to implement, can update the tracking signal frequency in real time, and can achieve deep suppression of system vibration within the full speed range of the bearingless motor.

[0004] In order to solve the above technical problems, the bearingless motor vibration suppression strategy based on the frequency band expansion finite dimensional repetitive controller of the present invention includes the following steps:

[0005] I. Start the bearingless motor system;

[0006] II. Sample the signal required for bearingless motor suspension control at the current moment and set the displacement reference value P ref ;

[0007] III. Collect the displacement error signal E at the current moment and input the displacement error signal E into the band-expanded finite-dimensional repetitive controller to obtain the displacement adjustment value P at the current moment s And serve as the input signal of the displacement regulator;

[0008] IV. The displacement adjustment value P s Input into the displacement regulator to obtain the current suspension current reference value i Lref And serves as the input signal of the current regulator;

[0009] V. Set the suspension current reference value i Lref Input into the current regulator to complete the closed-loop control of the suspension current;

[0010] VI. Repeat steps II to IV to suppress the vibration of the bearingless motor system in real time.

[0011] The required signals in step II include rotor displacement signal, rotor angle signal and suspension current signal; the displacement reference value P ref Select the displacement reference value within the movable range of the rotor.

[0012] The transfer function of the band-expanded finite-dimensional repetitive controller in step III is expressed as:

[0013]

[0014] P1(s)=2s 2 +2ωs+2ω 2 -λ(s+ω) 2

[0015] P2(s)=2s 2 +2ωs+2ω 2 +λ(s 2 +ω 2 )

[0016] Where ω represents the suppression frequency point of the band-expanded finite-dimensional repetitive controller, s represents the complex frequency domain variable, λ represents the weighting factor of the band-expanded finite-dimensional repetitive controller, P(s) is the rotor displacement of the bearingless motor, E(s) is the displacement error, and N(s) is the equivalent transfer function of the finite-dimensional repetitive controller;

[0017] The relationship between the suppression frequency point ω of the band-expanding finite-dimensional repetitive controller and the motor speed n can be expressed as:

[0018]

[0019] Where p is the number of rotor pole pairs of the bearingless motor.

[0020] The displacement regulator in step IV can adopt a proportional-integral-differential control algorithm control structure to obtain the suspension current reference value i Lref .

[0021] In step V, the current regulator can be controlled by using a proportional-integral control algorithm control structure.

[0022] Advantages of the present invention:

[0023] (1) Based on the traditional finite-dimensional repetitive controller, a frequency band expansion unit with a weighted coefficient is introduced, which not only widens the tracking bandwidth of the traditional repetitive controller near the set frequency point, but also increases its signal tracking gain at this frequency point, thereby realizing the adjustment of the tracking bandwidth near the set frequency point.

[0024] (2) The real-time speed information is introduced into the parameter design of the finite-dimensional repetitive controller, which solves the problem that the traditional repetitive controller cannot update the tracking signal frequency in real time and cannot adapt to variable frequency working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a control structure diagram of the bearingless motor vibration suppression strategy based on the frequency band expansion finite dimensional repetitive controller of the present invention;

[0026] Figure 2 It is the frequency domain characteristic of the band-expanded finite-dimensional repetitive controller under the same weighting coefficient and gain coefficient in the bearingless motor vibration suppression strategy based on the band-expanded finite-dimensional repetitive controller of the present invention. DETAILED DESCRIPTION

[0027] The bearingless motor vibration suppression strategy based on the band-expanded finite-dimensional repetitive controller of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example:

[0029] like Figure 1 As shown, the bearingless motor vibration suppression strategy based on the band-expanding finite-dimensional repetitive controller of the present invention includes the following steps:

[0030] I. Start the bearingless motor system;

[0031] II. Sample the signal required for bearingless motor suspension control at the current moment and set the displacement reference value P ref The required signals include rotor displacement signal, rotor angle signal and suspension current signal. The displacement reference value P ref Select the displacement reference value within the movable range of the rotor.

[0032] III. Collect the displacement error signal E at the current moment and input the displacement error signal E into the band-expanded finite-dimensional repetitive controller to obtain the displacement adjustment value P at the current moment s And it serves as the input signal of the displacement regulator; the frequency band expansion finite dimensional repetitive controller introduces a frequency band expansion unit on the basis of the traditional finite dimensional repetitive controller, and the frequency band expansion unit includes a structure with a weighting factor.

[0033] When traditional finite-dimensional repetitive controllers are applied to bearingless motor systems, there are two problems: 1. Poor vibration suppression effect when the motor has speed fluctuations: The traditional finite-dimensional repetitive controller has a narrow suppression band. When applied to bearingless motor systems, various non-ideal factors will cause a certain deviation between the actual frequency and the design frequency, resulting in poor system vibration suppression effect; 2. Poor vibration suppression effect under motor variable frequency conditions: Under the variable frequency operating conditions of bearingless motors, the system vibration frequency also changes accordingly, and the vibration frequency also changes before and after the frequency conversion. If the suppression link is designed with a fixed frequency, then the suppression effect of the designed vibration suppression system at non-set speeds is almost zero.

[0034] Figure 1 In, G p (s) and G c (s) are the equivalent transfer functions of displacement regulator and current regulator, I L (s) and I Lref (s) are the suspension current and the suspension current reference value, D(s) is the equivalent interference signal introduced by the non-ideal factors of the process, and k c and k s are the rotor current stiffness and displacement stiffness respectively, G m (s) is the transfer function of the rotor kinematic model, and M(s) is the equivalent transfer function of the bearingless motor.

[0035] The transfer function expression of the traditional finite-dimensional repetitive controller is:

[0036]

[0037] Where N(s) is the equivalent transfer function of the finite-dimensional repetitive controller, k f is the gain of the band-expanding finite-dimensional repetitive controller, ω represents the suppression frequency point of the band-expanding finite-dimensional repetitive controller, and s represents the complex frequency domain variable.

[0038] The transfer function of the band-expanded finite-dimensional repetitive controller is derived from the transfer function of the traditional finite-dimensional repetitive controller as follows:

[0039]

[0040] P1(s)=2s 2 +2ωs+2ω 2 -λ(s+ω) 2

[0041] P2(s)=2s 2 +2ωs+2ω 2 +λ(s 2 +ω 2 )

[0042] Where ω represents the suppression frequency point of the band-expanded finite-dimensional repetitive controller, s represents the complex frequency domain variable, λ represents the weighting factor of the band-expanded finite-dimensional repetitive controller, P(s) is the rotor displacement of the bearingless motor, E(s) is the displacement error, and N(s) is the equivalent transfer function of the finite-dimensional repetitive controller.

[0043] IV. The displacement adjustment value P s Input to the displacement regulator, the displacement regulator adopts the proportional-integral-differential control algorithm control structure to obtain the current moment of the suspension current reference value i Lref And serves as the input signal of the current regulator;

[0044] V. Set the suspension current reference value i Lref The input is sent to the current regulator, which can use the proportional-integral control algorithm control structure to achieve closed-loop control of the suspension current.

[0045] VI. Repeat steps II to IV to suppress the vibration of the bearingless motor system in real time.

[0046] like Figure 2 As shown in the figure, the frequency domain characteristics of the band-expanded finite-dimensional repetitive controller under different gain coefficients and weighting coefficients are analyzed. The amplitude-frequency response curve shows that:

[0047] When the control gain k f When the weighting factor λ is the same, the suppression bandwidth of the band-expanded finite-dimensional repetitive controller of the present invention increases with the increase of the weighting factor λ, and the suppression depth also increases accordingly; when the weighting factor λ is the same, the control gain k f The larger the value, the greater the suppression bandwidth and suppression depth. f As the frequency increases, the controller's suppression effect on non-suppressed frequency signals, especially DC signals, becomes increasingly greater. Therefore, when designing, it is necessary to select a larger weighting factor λ and gain coefficient k while ensuring that other required signals are not affected. f . Analysis of the phase-frequency characteristics shows that: with the weighting factor λ and the gain coefficient k f As the phase shift angle and the corresponding frequency width increase, the stability margin of the bearingless motor closed-loop control system will become smaller. Therefore, the weighting factor λ and the gain coefficient k of the frequency band expansion finite dimensional repetitive controller of the present invention are designed. f In summary, when designing the frequency band expansion finite dimensional repetitive controller of the present invention, it is necessary to select a larger weighting factor λ and gain coefficient k while ensuring that the stability of the bearingless motor system and other required signals are not affected. f .

[0048] Furthermore, to address the problem that traditional repetitive control cannot adapt to variable-frequency motor system conditions, the present invention incorporates bearingless motor speed information into the parameter design of a band-expanded finite-dimensional repetitive controller. Considering that bearingless motor vibration caused by irrational factors is generally an integer multiple of the fundamental speed frequency, the relationship between the parameter ω of the band-expanded finite-dimensional repetitive controller and the motor speed n can be expressed as:

[0049]

[0050] Where p is the number of rotor pole pairs of the bearingless motor.

Claims

1. A bearingless motor vibration suppression strategy based on a band-expanding finite-dimensional repetitive controller, characterized in that: The following steps are involved: I. Start the bearingless motor system; II. Sample the signal required for bearingless motor suspension control at the current moment and set the displacement reference value P ref ; III. Collect the displacement error signal E at the current moment and input the displacement error signal E into the band-expanded finite-dimensional repetitive controller to obtain the displacement adjustment value P at the current moment s And serve as the input signal of the displacement regulator; IV. The displacement adjustment value P s Input into the displacement regulator to obtain the current suspension current reference value i Lref And serves as the input signal of the current regulator; V. Set the suspension current reference value i Lref Input into the current regulator to complete the closed-loop control of the suspension current; VI. Repeat steps II to IV to suppress the vibration of the bearingless motor system in real time.

2. The bearingless motor vibration suppression strategy based on a band-expanded finite-dimensional repetitive controller according to claim 1, characterized in that: The required signals in step II include rotor displacement signal, rotor angle signal and suspension current signal; the displacement reference value P ref Select the displacement reference value within the movable range of the rotor.

3. The bearingless motor vibration suppression strategy based on a band-expanded finite-dimensional repetitive controller according to claim 1, characterized in that: The transfer function expression of the band-expanded finite-dimensional repetitive controller in step III is: P1(s)=2s 2 +2ωs+2ω 2 -λ(s+ω) 2 P2(s)=2s 2 +2ωs+2ω 2 +λ(s 2 +oh 2 ) Where ω represents the suppression frequency point of the band-expanded finite-dimensional repetitive controller, s represents the complex frequency domain variable, λ represents the weighting factor of the band-expanded finite-dimensional repetitive controller, P(s) is the rotor displacement of the bearingless motor, E(s) is the displacement error, and N(s) is the equivalent transfer function of the finite-dimensional repetitive controller; The relationship between the suppression frequency point ω and the motor speed n of the band-expanded finite-dimensional repetitive controller can be expressed as: Where p is the number of rotor pole pairs of the bearingless motor.

4. The bearingless motor vibration suppression strategy based on a band-expanded finite-dimensional repetitive controller according to claim 1, characterized in that: The displacement regulator in step IV can adopt a proportional-integral-differential control algorithm control structure to obtain the suspension current reference value i Lref .

5. The bearingless motor vibration suppression strategy based on a band-expanded finite-dimensional repetitive controller according to claim 1, characterized in that: In step V, the current regulator can be controlled by using a proportional-integral control algorithm control structure.

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