Displacement detection method and device for magnetic suspension bearing, and magnetic suspension bearing system

Abstract

The invention discloses a magnetic suspension bearing displacement detection method and device, a magnetic suspension bearing system, a storage medium and a computer program product, an axial displacement detection area of a magnetic suspension bearing is provided with four displacement detection probes used for detecting axial displacement of a rotor, and the four probes are divided into two groups; the first group of two probes are installed along a first symmetrical direction, the second group of two probes are installed along a second symmetrical direction orthogonal to the first symmetrical direction, the design parameters of the same group of probes are consistent, and the design parameters of the different groups of probes are not consistent; the method comprises the following steps: carrying out mean value and difference operation on signals acquired by four probes to eliminate radial coupling interference; and filtering the signal subjected to mean value operation and differential operation by adopting same-frequency notch processing so as to filter radial coupling interference. According to the scheme, high-precision stable operation of magnetic suspension axial displacement is realized.

Description

Technical Field

[0001] This invention belongs to the field of magnetic levitation bearing technology, specifically relating to a displacement detection method, device, magnetic levitation bearing system, storage medium, and computer program product for magnetic levitation bearings. Background Technology

[0002] Active magnetic levitation bearing-rotor systems are increasingly widely used in high-speed rotating machinery due to their significant advantages of being frictionless and having low energy consumption. This system maintains rotor levitation through active electromagnetic force, and its control accuracy is highly dependent on the quality of the measurement signal from the axial displacement sensor. Interference components in the sensor signal can directly lead to a decline in control system performance and even cause rotor axial oscillation, disrupting stable system operation.

[0003] In practical applications, due to limitations in machining precision and assembly errors, the axial displacement detection surface of magnetic levitation bearings has unavoidable defects: on the one hand, the perpendicularity of the detection surface to the rotor's rotation axis cannot be completely guaranteed, and tilting is prone to occur; on the other hand, insufficient surface flatness and local unevenness are easily left after machining. These defects inevitably lead to interference components generated by the rotor's radial unbalanced displacement response being coupled into the axial displacement signal acquired by the sensor. Specifically, the tilt of the detection surface allows the radial unbalanced response to directly couple into the axial signal through the structure, while defects in the flatness of the detection surface introduce radial coupling interference of the same frequency or harmonic frequency due to the periodic change in the distance between the detection surface and the probe during rotor rotation. These radial coupling interferences not only prevent the displacement sensor from accurately acquiring the true axial displacement information of the rotor, but also cause the control system to generate harmonic control current, causing the electromagnetic bearing to generate harmonic vibration force, further aggravating the rotor's axial oscillation, and even leading to axial current saturation, severely restricting the operating accuracy and stability of the magnetic levitation bearing-rotor system.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a displacement detection method, device, system, storage medium, and computer program for magnetic levitation bearings. This addresses the problem in related solutions where machining and assembly defects such as tilting or insufficient flatness of the axial displacement detection surface lead to radial interference from axial displacement signals, hindering high-precision and stable operation of the magnetic levitation bearing. The invention achieves this by arranging four axial displacement sensor probes and performing mean and difference calculations on the displacement signals collected by the probes. This eliminates radial coupling signals from tilted detection surfaces and filters out radial coupling interference signals from uneven detection surfaces and insufficient flatness, thus achieving high-precision and stable axial displacement operation of the magnetic levitation bearing.

[0006] This invention provides a displacement detection method for a magnetic levitation bearing. The axial displacement detection area of ​​the magnetic levitation bearing is equipped with four displacement detection probes. These probes are used to detect the axial displacement of the magnetic levitation bearing rotor. The four probes are divided into two groups: two probes in the first group are installed along a first symmetrical direction, and two probes in the second group are installed along a second symmetrical direction, with the first and second symmetrical directions being orthogonal to each other. The design parameters of the two probes in the first group and the two probes in the second group are identical, but the design parameters of the probes in the first group and the second group are inconsistent. The method includes: acquiring displacement signals from the axial displacement detection surface collected by the four probes; performing mean and difference operations on the four displacement signals to eliminate radial coupling interference; and using a notch filter to filter the signals after the mean and difference operations to remove radial coupling interference.

[0007] In some embodiments, the two displacement detection probes in the first group are installed symmetrically at 180° along a first symmetry direction, and the two displacement detection probes in the second group are installed symmetrically at 180° along a second symmetry direction.

[0008] In some embodiments, the mean and difference operations on the four displacement signals include: taking a first group or a second group as a reference group and another group as a control group; taking the average value of the displacement signals collected by the two displacement detection probes in the reference group as a reference signal; performing difference operations on the reference signal and the displacement signals collected by the two displacement detection probes in the control group respectively; and performing a mean operation on the two output signals obtained after the difference operation.

[0009] In some implementations, the signal after averaging is demodulated to obtain a signal for feedback of the axial displacement change of the magnetic levitation bearing rotor.

[0010] In some embodiments, the center frequency of the same-frequency notch filtering is the same as the rotational speed of the magnetic levitation bearing rotor, and the input signal of the same-frequency notch filtering is the difference between the displacement signal fed back by axial detection and the reference displacement. The transfer function of the same-frequency notch filtering includes a bandwidth factor parameter, and the value of the bandwidth factor parameter is a preset value.

[0011] In conjunction with the above method, another aspect of the present invention provides a displacement detection device for a magnetic levitation bearing. The axial displacement detection area of ​​the magnetic levitation bearing is provided with four displacement detection probes. The displacement detection probes are used to detect the axial displacement of the magnetic levitation bearing rotor. The four displacement detection probes are divided into two groups. Two probes in the first group are installed along a first symmetrical direction, and two probes in the second group are installed along a second symmetrical direction, with the first and second symmetrical directions being orthogonal to each other. The design parameters of the two probes in the first group are identical, and the design parameters of the two probes in the second group are identical, but the design parameters of the probes in the first group are inconsistent with those in the second group. The device includes: a signal acquisition unit configured to acquire displacement signals from the axial displacement detection surface acquired by the four displacement detection probes; a signal processing unit configured to perform mean and difference operations on the four displacement signals to eliminate radial coupling interference; and a notch filter unit configured to use in-frequency notch filtering to filter the signals after mean and difference operations to remove radial coupling interference.

[0012] In some embodiments, the two displacement detection probes in the first group are installed symmetrically at 180° along a first symmetry direction, and the two displacement detection probes in the second group are installed symmetrically at 180° along a second symmetry direction.

[0013] In some embodiments, the signal processing unit performs mean and difference operations on the four displacement signals, including: taking a first group or a second group as a reference group and another group as a control group; taking the average value of the displacement signals collected by the two displacement detection probes in the reference group as a reference signal; performing difference operations on the reference signal and the displacement signals collected by the two displacement detection probes in the control group respectively; and performing mean operations on the two output signals obtained after the difference operations.

[0014] In some implementations, the signal processing unit is further configured to demodulate the signal after averaging to obtain a signal for feedback of the axial displacement change of the magnetic levitation bearing rotor.

[0015] In some embodiments, the center frequency of the same-frequency notch filtering is the same as the rotational speed of the magnetic levitation bearing rotor, and the input signal of the same-frequency notch filtering is the difference between the displacement signal fed back by axial detection and the reference displacement. The transfer function of the same-frequency notch filtering includes a bandwidth factor parameter, and the value of the bandwidth factor parameter is a preset value.

[0016] In conjunction with the above-mentioned device, the present invention further provides a magnetic levitation bearing system, including: the displacement detection device for the magnetic levitation bearing described above.

[0017] In conjunction with the above method, the present invention further provides a storage medium comprising a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the displacement detection method for the magnetic levitation bearing described above.

[0018] In conjunction with the above method, the present invention further provides a computer program product comprising a computer program that, when processed and executed, implements the steps of the displacement detection method for the magnetic levitation bearing described above.

[0019] The present invention provides a magnetic levitation bearing axial displacement detection area equipped with four displacement detection probes for detecting rotor axial displacement. The four probes are divided into two groups: the first group consists of two probes installed along a first symmetrical direction, and the second group consists of two probes installed along a second symmetrical direction orthogonal to the first symmetrical direction. Probes within the same group have identical design parameters, while probes in different groups have different design parameters. The signals collected by the four probes are averaged and differentially analyzed to eliminate radial coupling interference caused by the tilt of the detection surface. A notch filter is used to filter the processed signals to remove radial coupling interference caused by insufficient flatness or unevenness of the detection surface. This achieves high-precision and stable operation of the magnetic levitation axial displacement.

[0020] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart of an embodiment of the displacement detection method for magnetic levitation bearings of the present invention;

[0023] Figure 2 This is a schematic diagram of a structure of an embodiment of the displacement detection device for magnetic levitation bearings of the present invention;

[0024] Figure 3 This is a schematic diagram showing the distribution of the magnetic levitation coil and bearings;

[0025] Figure 4 This is a schematic diagram of the installation of an axial displacement sensor.

[0026] Figure 5 This is a schematic diagram of the normal operation of the four probes of the axial displacement sensor.

[0027] Figure 6 For axial detection surface P1 around A schematic diagram showing rotation and tilt at a certain angle;

[0028] Figure 7 For axial detection surface P1 around A schematic diagram showing rotation and tilt at a certain angle;

[0029] Figure 8 For axial detection surface P1 around Rotate, tilt, and circle at a certain angle. A schematic diagram showing rotation and tilt at a certain angle;

[0030] Figure 9 This is a schematic diagram showing an uneven surface on the axial inspection surface.

[0031] Figure 10 This is a schematic diagram illustrating a situation where the surface of the axial inspection device is not sufficiently flat.

[0032] Figure 11 For sensor probe coil detection circuit;

[0033] Figure 12 The sensor probe coil detects the signal;

[0034] Figure 13 This is the hardware processing circuit for the sensor probe signal;

[0035] Figure 14 This is a schematic diagram of a frequency limiter.

[0036] Referring to the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0037] 101 - Signal acquisition unit; 102 - Signal processing unit; 103 - Notch filter unit. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] In existing technologies, solutions for axial displacement signal interference mostly focus on a single interference source (such as optimizing only the sensor mounting position), lacking an integrated decoupling solution that can simultaneously address radial coupling interference caused by multiple defects such as detection surface tilt and insufficient surface flatness. While some solutions (such as using dual sensor mounting surfaces) can suppress interference to some extent, they suffer from complex structures and large space requirements, making them unsuitable for miniaturized and integrated equipment. Therefore, effectively eliminating radial coupling interference caused by multiple defects in the detection surface to achieve high-precision and stable axial control of magnetic levitation bearings is a key problem to be solved in the field of magnetic levitation bearings.

[0040] Therefore, this invention provides a displacement detection method for magnetic levitation bearings. In terms of hardware, four axial displacement detection probes are designed and installed vertically and symmetrically. The four displacement signals are averaged and differentially calculated to eliminate the radial coupling interference caused by the axial displacement detection surface being tilted and not absolutely perpendicular to the sensor probe mounting surface. In terms of software, a notch filter is used to further filter out the radial coupling interference caused by insufficient flatness or unevenness of the axial detection surface, thus achieving high-precision axial control.

[0041] According to an embodiment of the present invention, a displacement detection method for a magnetic levitation bearing is provided, wherein four displacement detection probes are provided in the axial displacement detection area of ​​the magnetic levitation bearing; the displacement detection probes are used to detect the axial displacement of the rotor of the magnetic levitation bearing; the four displacement detection probes are divided into two groups, two of the displacement detection probes in the first group are installed along a first symmetrical direction, and two of the displacement detection probes in the second group are installed along a second symmetrical direction, and the first symmetrical direction and the second symmetrical direction are orthogonal to each other.

[0042] Displacement detection probes include eddy current displacement sensors, laser displacement sensors, etc. The installation positions of the four displacement detection probes are as follows: Figure 3 and Figure 4 As shown, the four displacement detection probes are axial eddy current sensors S1, S2, S3, and S4. Axial eddy current sensors S1-S4 are all mounted on sensor mounting surface P2, which is opposite to the axial displacement detection surface P1. The detection direction of each probe is aligned with the axial displacement detection surface of the rotor, ensuring that the probe can capture the change in distance between the detection surface and the probe in real time. If the axial movable distance of the rotor is n, then the minimum effective range of axial eddy current sensors S1-S4 is n. On sensor mounting surface P2, axial eddy current sensors S1 and S3 are arranged opposite each other in the y-axis direction, and axial eddy current sensors S2 and S4 are arranged opposite each other in the x-axis direction. That is, S1 and S3 form one group, and S2 and S4 form another group, and the four sensors are orthogonally symmetrically installed.

[0043] In some embodiments, the two displacement detection probes in the first group are installed symmetrically at 180° along a first symmetry direction, and the two displacement detection probes in the second group are installed symmetrically at 180° along a second symmetry direction.

[0044] Two displacement detection probes in the same group are distributed in opposite directions on the corresponding symmetrical direction with the rotation axis of the magnetic levitation bearing rotor as the center, and the two probes are equidistant from the rotation axis, forming a 180° angled layout, so that the probes can collect signals from the axial displacement detection surface from the symmetrical position.

[0045] 180° symmetrical installation enables probes in the same group to accurately capture this reverse distance change, precisely enhancing the hardware layout accuracy of the displacement detection probes. This allows probes in the same group to collect tilt interference signals with equal amplitude but opposite direction, providing a crucial signal foundation for subsequent averaging and differential calculations to cancel radial coupling interference caused by the tilt of the detection surface. For example, if the detection surface tilts upward around the horizontal axis, the distance between the upper probe and the detection surface will decrease, while the distance between the lower probe and the detection surface will increase, and the amplitudes of the distance changes will be equal but the directions will be opposite.

[0046] Sensor probe coil detection circuit as follows Figure 11 As shown, probe coils S1-S4 sense the displacement change of the axial displacement detection surface of the magnetic levitation bearing rotor, causing their own electromagnetic properties to change. Resistor R1 and the probe coils form a circuit that receives signals S1, S2, S3, and S4 from the signal module, and simultaneously connects to the power supply VCC and the excitation signal. The MCU processes the relevant signals of the circuit, converting the electromagnetic change caused by the displacement of the probe coils into electrical signals that can be subsequently processed, providing the basic signals for axial displacement detection and interference elimination. The S1, S2, S3, and S4 signals are as follows: Figure 12 As shown, when the detection surface is neat, the signals of S1 and S3 are the same, and the signals of S2 and S4 are the same.

[0047] The two displacement detection probes in the first group have the same design parameters, the two displacement detection probes in the second group have the same design parameters, and the design parameters of the displacement detection probes in the first group are different from those in the second group.

[0048] Having identical design parameters for probes within the same group (such as identical temperature drift characteristics and interference noise characteristics) ensures that common interferences caused by environmental factors (such as temperature changes) or inherent characteristics (such as signal shift due to temperature drift) are completely identical in the signals acquired by the probes within the same group. Subsequent averaging operations can then cancel out these common interferences. Conversely, having different design parameters for probes in different groups avoids complete repetition of signals acquired by the two groups, ensuring that the differential interference caused by the tilt of the detection surface can be captured through the processing of the two sets of signals. This prevents interference from being impossible to eliminate through differential operations due to identical signals. The design parameters of displacement detection probes include, but are not limited to, temperature drift characteristic parameters and interference noise characteristic parameters.

[0049] When selecting displacement detection probes, parameter screening is performed on two probes in the same group to ensure that the errors of design parameters such as temperature drift and interference noise are within the preset range. For probes in different groups, models or batches with preset differences in design parameters are selected so that the signals collected by the two groups of probes can show the characteristic differences corresponding to the installation direction in the absence of interference, rather than being completely overlapping.

[0050] The detection status of the four probes of the axial displacement sensor is as follows: Figures 5 to 10 As shown, when the axial displacement detection surface P1 is flat and there is no tilting or rotation, the displacement signals collected by sensors S1 and S3 are the same, and the displacement signals collected by sensors S2 and S4 are the same. When the axial displacement detection surface P1 experiences conditions such as... Figures 6 to 10 When the sensor is rotated, tilted, uneven, or has an irregular detection surface, the displacement signal acquired by the probe will contain noise of the same frequency and its harmonics. These harmonics prevent the displacement sensor from accurately acquiring the axial displacement information of the magnetic bearing rotor and also induce harmonic control current. This harmonic control current causes harmonic vibration forces in the electromagnetic bearing mounted on the magnetic bearing stator, adversely affecting the levitation of the magnetic bearing rotor and leading to instability in the magnetic levitation bearing system.

[0051] like Figure 1 The diagram shows a flowchart of an embodiment of the method of the present invention. The displacement detection method of the magnetic levitation bearing may include steps S110 to S130.

[0052] In step S110, the displacement signals of the axial displacement detection surfaces collected by the four displacement detection probes are acquired.

[0053] After the magnetic levitation bearing system is started, the four displacement detection probes start working simultaneously, detecting the changes in distance between themselves and the axial displacement detection surface in real time, and converting the distance changes into corresponding electrical signals, i.e. displacement signals.

[0054] In step S120, the mean and difference operations are performed on the four displacement signals to eliminate radial coupling interference caused by the tilt of the axial displacement detection surface.

[0055] When the detection surface is tilted, the distance between the probes in different directions and the detection surface will show an opposite trend (e.g., when the detection surface is tilted around the horizontal axis, the distance between the probes on one side increases and the distance on the other side decreases in the vertical direction). The mean operation of the signals of the same group of probes can cancel out common interference (such as temperature drift), and the differential operation can use the mutual cancellation characteristics of the opposite interference components to eliminate the radial coupling interference caused by the tilt.

[0056] In some embodiments, the specific process of performing mean and difference operations on the four displacement signals in step S120 includes steps S210 to S240.

[0057] Step S210: Use either the first or second group as the baseline group and the other group as the control group.

[0058] Step S220: The average value of the displacement signals collected by the two displacement detection probes in the reference group is used as the reference signal.

[0059] Based on the common tilt direction of the axial displacement detection surface of the magnetic levitation bearing (e.g., the detection surface in a certain type of equipment is more likely to tilt around the horizontal axis), a set of probes installed in the corresponding direction is selected as the reference group (e.g., the first group installed vertically), and another group (e.g., the second group installed horizontally) is selected as the control group. If the detection surface does not have a fixed tilt direction, one group can be randomly selected as the reference group, and the other group as the control group. The displacement signals of the axial displacement detection surface collected in real time by the two displacement detection probes in the reference group are obtained, and the average value of the two signals is the reference signal.

[0060] The two probes in the reference group have the same design parameters. The common interferences generated by the environment or their own characteristics in the signals they collect are exactly the same. Taking the average value can make these common interferences cancel each other out, and finally obtain a reference signal that only reflects the true displacement.

[0061] Step S230: Perform differential calculation on the reference signal and the displacement signals collected by the two displacement detection probes in the control group.

[0062] First, the average value of the signals collected by the two displacement detection probes in the reference group is taken to obtain the reference signal. This operation can cancel out the error caused by the tilt of the detection surface along the x-axis. When the axial displacement detection surface is tilted, the signals collected by the two probes in the control group will exhibit reverse interference due to the change in the distance between the detection surfaces. Moreover, the interference component has the same amplitude and opposite direction as the corresponding interference component in the reference signal. Differential operation, as a design method for displacement signal detection, can make the reverse interference components cancel each other out, and at the same time effectively cancel out the temperature drift of the displacement signals of the four displacement detection probes, retaining only the true axial displacement difference signal.

[0063] Specifically, displacement signals collected by two displacement detection probes in the control group are extracted respectively. The difference between the signal from the first control group probe and the reference signal is calculated to obtain the first differential output signal. Then, the difference between the signal from the second control group probe and the reference signal is calculated to obtain the second differential output signal, thus completing the initial cancellation of interference between the two sets of signals.

[0064] Step S240: Perform a mean operation on the two output signals obtained after the difference operation.

[0065] While differential operations can cancel out major tilt interference, slight differences may exist between the two differential output signals due to minor fluctuations during signal acquisition. By averaging the two differential signals and summing the values ​​of the two differential output signals, this type of fluctuation can be smoothed out. At the same time, it can also cancel out the error caused by tilting along the y-axis detection surface, further enhancing the stability of the real displacement signal and avoiding the impact of minor residual interference on subsequent detection accuracy.

[0066] Specifically, the values ​​of the two differential output signals are added together and averaged to obtain the final mean signal. This signal has basically eliminated the radial coupling interference caused by the tilt of the detection surface (including situations where the detection surface is not tilted, the detection surface is tilted along the y-axis, the detection surface is tilted along the x-axis, or the detection surfaces are tilted simultaneously along the x-axis and y-axis), and effectively suppressed the temperature drift of the sensor.

[0067] The hardware circuit for averaging and differentiating displacement signals is as follows: Figure 13 As shown, S1 and S3 are the displacement signals collected by the baseline group, and S2 and S4 are the displacement signals collected by the control group. Therefore, the baseline signal S5 is:

[0068] ;

[0069] Take the average of S1 and S3 as reference signals, such as Figure 6 As shown, this can compensate for the error caused by the tilt of the detection surface along the x-axis. Then, the reference signal S5 is differentially analyzed with signals S2 and S4 respectively to obtain signals S6 and S7, i.e.:

[0070] ;

[0071] ;

[0072] The reference signal S5 is differentially processed with signals S2 and S4 respectively, which can effectively cancel the temperature drift of the displacement signals of the four probes S1, S3, S2, and S4. Then, the average of signals S6 and S7 is taken to obtain the output signal S8.

[0073] .

[0074] The average value of signals S6 and S7 is taken, such as Figure 7 As shown, this can offset the error caused by tilting along the y-axis detection surface. Through the above mean and difference operations, the temperature drift of the sensor can be effectively suppressed when the detection surface is tilted along the x-axis, along the y-axis, along both the x-axis and y-axis, or when the detection surface is not tilted. At the same time, it can offset the reverse tilt interference and achieve precise and complete elimination of radial coupling interference, thereby significantly improving the accuracy and stability of the axial displacement signal.

[0075] In some implementations, the signal after averaging is demodulated to obtain a signal for feedback of the axial displacement change of the magnetic levitation bearing rotor.

[0076] The signal after averaging is a modulated signal containing useful displacement information and carrier components. Demodulation processing uses specific algorithms or processing logic to separate the carrier components from the useful displacement information, so that the signal form and displacement change are directly correlated.

[0077] Specifically, the signal after averaging is filtered and preprocessed to initially suppress any residual high-frequency noise in the signal and prevent noise from affecting demodulation accuracy. Then, the demodulation algorithm is used to extract the changes in the signal related to axial displacement, and the extracted displacement changes are converted into a standard signal form to finally obtain an axial displacement change signal that can be used for feedback.

[0078] like Figure 13 As shown, after demodulation, the output signal S8 yields an analog voltage signal that reflects the change in axial displacement. This voltage signal no longer contains the radial coupling signal indicating the tilt of the detection surface. , Temperature drift It is also effectively suppressed. The analog voltage signal is converted into a digital signal by the analog-to-digital converter (ADC) and then input to the MCU.

[0079] In step S130, the signal after mean and difference operations is filtered by the same frequency notch filter to filter out radial coupling interference caused by insufficient flatness or unevenness of the axial displacement detection surface.

[0080] When the surface being tested is not flat enough or is uneven, the distance between the probe and the surface being tested will change periodically as the rotor rotates. The frequency of this change is the same as the rotor speed, which causes the frequency of the radial coupling interference signal to be the same as the rotor speed. Same-frequency notch filtering can accurately identify and filter out the interference signal of this specific frequency, while retaining the useful axial displacement signal and avoiding the false filtering of useful signals of other frequencies.

[0081] In some embodiments, the center frequency of the same-frequency notch filtering is the same as the rotational speed of the magnetic levitation bearing rotor, and the input signal of the same-frequency notch filtering is the difference between the displacement signal fed back by axial detection and the reference displacement. The transfer function of the same-frequency notch filtering includes a bandwidth factor parameter, and the value of the bandwidth factor parameter is a preset value.

[0082] By detecting the real-time rotational speed of the magnetic levitation bearing rotor, and based on the correlation between rotational speed and frequency, the target frequency that matches the rotor's rotational speed is calculated. For example, if the rotor speed is 3000 rpm, then the target frequency is 50 Hz. Only by clearly identifying the frequency of the interference signal that needs to be filtered out can the signal attenuation or filtering at that frequency be accurately performed.

[0083] Specifically, the real-time rotational speed of the magnetic levitation bearing rotor is determined, and the frequency corresponding to this rotational speed is set as the target frequency for notch filtering. The displacement signal after mean and difference calculations is input into the notch filtering module. The notch filtering module uses an internal algorithm to attenuate and filter the components in the signal that are consistent with the target frequency, and finally outputs an axial displacement signal that eliminates radial coupling interference caused by insufficient flatness or unevenness of the detection surface.

[0084] like Figure 14 As shown, a frequency limiter is used in software control to filter out radially coupled interference signals and feed them back to the MCU displacement signal. With reference displacement The difference X_nf(k) is the input variable of the same-frequency limiting circuit. The transfer function of the same-frequency limiting circuit is: ,in The bandwidth factor of the notch filter. This is the rotor speed, which is the center frequency of the notch filter.

[0085] In-frequency notch filtering effectively removes interference signals that operate at the same frequency as the rotor speed, avoiding the potential impact of traditional filtering methods on the useful signal. This ensures the accuracy of the axial displacement detection signal, enabling the magnetic levitation bearing system to be controlled based on more precise displacement signals. Eliminating in-frequency interference caused by machining defects on the detection surface results in more accurate axial displacement feedback of the magnetic levitation bearing rotor. The control system can then more precisely adjust the electromagnetic force, reducing rotor oscillations caused by displacement detection errors and improving the overall system's operational stability.

[0086] This invention eliminates radial coupling signals caused by tilted installation of the detection surface by performing mean and difference operations on the displacement signal. Furthermore, it uses a software filtering algorithm to filter out radial coupling signals caused by unevenness of the detection surface and radial coupling interference signals caused by insufficient flatness of the detection surface, thereby achieving high-precision and stable operation of magnetic levitation axial displacement.

[0087] The technical solution of this embodiment uses four displacement detection probes in the axial displacement detection area of ​​the magnetic levitation bearing to detect the rotor's axial displacement. The four probes are divided into two groups: the first group has two probes installed along a first symmetrical direction, and the second group has two probes installed along a second symmetrical direction orthogonal to the first symmetrical direction. Probes within the same group have the same design parameters, while probes in different groups have different design parameters. The signals collected by the four probes are averaged and differentially analyzed to eliminate radial coupling interference caused by the tilt of the detection surface. A notch filter is used to filter the processed signals to remove radial coupling interference caused by insufficient flatness or unevenness of the detection surface. This achieves high-precision and stable operation of the magnetic levitation axial displacement.

[0088] According to an embodiment of the present invention, a displacement detection device for a magnetic levitation bearing corresponding to a displacement detection method for a magnetic levitation bearing is also provided. The axial displacement detection area of ​​the magnetic levitation bearing is provided with four displacement detection probes; the displacement detection probes are used to detect the axial displacement of the magnetic levitation bearing rotor; the four displacement detection probes are divided into two groups, with two probes in the first group installed along a first symmetrical direction, and two probes in the second group installed along a second symmetrical direction, wherein the first symmetrical direction and the second symmetrical direction are orthogonal to each other.

[0089] Displacement detection probes include eddy current displacement sensors, laser displacement sensors, etc. The installation positions of the four displacement detection probes are as follows: Figure 3 and Figure 4As shown, the four displacement detection probes are axial eddy current sensors S1, S2, S3, and S4. Axial eddy current sensors S1-S4 are all mounted on sensor mounting surface P2, which is opposite to the axial displacement detection surface P1. The detection direction of each probe is aligned with the axial displacement detection surface of the rotor, ensuring that the probe can capture the change in distance between the detection surface and the probe in real time. If the axial movable distance of the rotor is n, then the minimum effective range of axial eddy current sensors S1-S4 is n. On sensor mounting surface P2, axial eddy current sensors S1 and S3 are arranged opposite each other in the y-axis direction, and axial eddy current sensors S2 and S4 are arranged opposite each other in the x-axis direction. That is, S1 and S3 form one group, and S2 and S4 form another group, and the four sensors are orthogonally symmetrically installed.

[0090] In some embodiments, the two displacement detection probes in the first group are installed symmetrically at 180° along a first symmetry direction, and the two displacement detection probes in the second group are installed symmetrically at 180° along a second symmetry direction.

[0091] Two displacement detection probes in the same group are distributed in opposite directions on the corresponding symmetrical direction with the rotation axis of the magnetic levitation bearing rotor as the center, and the two probes are equidistant from the rotation axis, forming a 180° angled layout, so that the probes can collect signals from the axial displacement detection surface from the symmetrical position.

[0092] 180° symmetrical installation enables probes in the same group to accurately capture this reverse distance change, precisely enhancing the hardware layout accuracy of the displacement detection probes. This allows probes in the same group to collect tilt interference signals with equal amplitude but opposite direction, providing a crucial signal foundation for subsequent averaging and differential calculations to cancel radial coupling interference caused by the tilt of the detection surface. For example, if the detection surface tilts upward around the horizontal axis, the distance between the upper probe and the detection surface will decrease, while the distance between the lower probe and the detection surface will increase, and the amplitudes of the distance changes will be equal but the directions will be opposite.

[0093] Sensor probe coil detection circuit as follows Figure 11 As shown, probe coils S1-S4 sense the displacement change of the axial displacement detection surface of the magnetic levitation bearing rotor, causing their own electromagnetic properties to change. Resistor R1 and the probe coils form a circuit that receives signals S1, S2, S3, and S4 from the signal module, and simultaneously connects to the power supply VCC and the excitation signal. The MCU processes the relevant signals of the circuit, converting the electromagnetic change caused by the displacement of the probe coils into electrical signals that can be subsequently processed, providing the basic signals for axial displacement detection and interference elimination. The S1, S2, S3, and S4 signals are as follows: Figure 12 As shown, when the detection surface is neat, the signals of S1 and S3 are the same, and the signals of S2 and S4 are the same.

[0094] The two displacement detection probes in the first group have the same design parameters, the two displacement detection probes in the second group have the same design parameters, and the design parameters of the displacement detection probes in the first group are different from those in the second group.

[0095] Having identical design parameters for probes within the same group (such as identical temperature drift characteristics and interference noise characteristics) ensures that common interferences caused by environmental factors (such as temperature changes) or inherent characteristics (such as signal shift due to temperature drift) are completely identical in the signals acquired by the probes within the same group. Subsequent averaging operations can then cancel out these common interferences. Conversely, having different design parameters for probes in different groups avoids complete repetition of signals acquired by the two groups, ensuring that the differential interference caused by the tilt of the detection surface can be captured through the processing of the two sets of signals. This prevents interference from being impossible to eliminate through differential operations due to identical signals. The design parameters of displacement detection probes include, but are not limited to, temperature drift characteristic parameters and interference noise characteristic parameters.

[0096] When selecting displacement detection probes, parameter screening is performed on two probes in the same group to ensure that the errors of design parameters such as temperature drift and interference noise are within the preset range. For probes in different groups, models or batches with preset differences in design parameters are selected so that the signals collected by the two groups of probes can show the characteristic differences corresponding to the installation direction in the absence of interference, rather than being completely overlapping.

[0097] The detection status of the four probes of the axial displacement sensor is as follows: Figures 5 to 10 As shown, when the axial displacement detection surface P1 is flat and there is no tilting or rotation, the displacement signals collected by sensors S1 and S3 are the same, and the displacement signals collected by sensors S2 and S4 are the same. When the axial displacement detection surface P1 experiences conditions such as... Figures 6 to 10 When the sensor is rotated, tilted, uneven, or has an irregular detection surface, the displacement signal acquired by the probe will contain noise of the same frequency and its harmonics. These harmonics prevent the displacement sensor from accurately acquiring the axial displacement information of the magnetic bearing rotor and also induce harmonic control current. This harmonic control current causes harmonic vibration forces in the electromagnetic bearing mounted on the magnetic bearing stator, adversely affecting the levitation of the magnetic bearing rotor and leading to instability in the magnetic levitation bearing system.

[0098] See Figure 2 The diagram shows a structural schematic of an embodiment of the device of the present invention. The displacement detection device for the magnetic levitation bearing may include: a signal acquisition unit 101, a signal processing unit 102, and a notch filter unit 103.

[0099] The signal acquisition unit 101 is configured to acquire the displacement signals of the axial displacement detection surfaces collected by the four displacement detection probes. The specific functions and processing of the signal acquisition unit 101 are described in step S110.

[0100] After the magnetic levitation bearing system is started, the four displacement detection probes start working simultaneously, detecting the changes in distance between themselves and the axial displacement detection surface in real time, and converting the distance changes into corresponding electrical signals, i.e. displacement signals.

[0101] The signal processing unit 102 is configured to perform mean and difference operations on the four displacement signals to eliminate radial coupling interference caused by the tilt of the axial displacement detection surface. The specific functions and processing of this signal processing unit 102 are described in step S120.

[0102] When the detection surface is tilted, the distance between the probes in different directions and the detection surface will show an opposite trend (e.g., when the detection surface is tilted around the horizontal axis, the distance between the probes on one side increases and the distance on the other side decreases in the vertical direction). The mean operation of the signals of the same group of probes can cancel out common interference (such as temperature drift), and the differential operation can use the mutual cancellation characteristics of the opposite interference components to eliminate the radial coupling interference caused by the tilt.

[0103] In some embodiments, the signal processing unit 102 performs mean and difference operations on the four displacement signals, including:

[0104] The signal processing unit 102 is further configured to use the first group or the second group as the reference group and the other group as the control group.

[0105] The signal processing unit 102 is further configured to use the average value of the displacement signals acquired by the two displacement detection probes in the reference group as the reference signal.

[0106] Based on the common tilt direction of the axial displacement detection surface of the magnetic levitation bearing (e.g., the detection surface in a certain type of equipment is more likely to tilt around the horizontal axis), a set of probes installed in the corresponding direction is selected as the reference group (e.g., the first group installed vertically), and another group (e.g., the second group installed horizontally) is selected as the control group. If the detection surface does not have a fixed tilt direction, one group can be randomly selected as the reference group, and the other group as the control group. The displacement signals of the axial displacement detection surface collected in real time by the two displacement detection probes in the reference group are obtained, and the average value of the two signals is the reference signal.

[0107] The two probes in the reference group have the same design parameters. The common interferences generated by the environment or their own characteristics in the signals they collect are exactly the same. Taking the average value can make these common interferences cancel each other out, and finally obtain a reference signal that only reflects the true displacement.

[0108] The signal processing unit 102 is further configured to perform differential operations on the reference signal and the displacement signals collected by the two displacement detection probes in the control group.

[0109] First, the average value of the signals collected by the two displacement detection probes in the reference group is taken to obtain the reference signal. This operation can cancel out the error caused by the tilt of the detection surface along the x-axis. When the axial displacement detection surface is tilted, the signals collected by the two probes in the control group will exhibit reverse interference due to the change in the distance between the detection surfaces. Moreover, the interference component has the same amplitude and opposite direction as the corresponding interference component in the reference signal. Differential operation, as a design method for displacement signal detection, can make the reverse interference components cancel each other out, and at the same time effectively cancel out the temperature drift of the displacement signals of the four displacement detection probes, retaining only the true axial displacement difference signal.

[0110] Specifically, displacement signals collected by two displacement detection probes in the control group are extracted respectively. The difference between the signal from the first control group probe and the reference signal is calculated to obtain the first differential output signal. Then, the difference between the signal from the second control group probe and the reference signal is calculated to obtain the second differential output signal, thus completing the initial cancellation of interference between the two sets of signals.

[0111] The signal processing unit 102 is specifically configured to perform an average operation on the two output signals obtained after the difference operation.

[0112] While differential operations can cancel out major tilt interference, slight differences may exist between the two differential output signals due to minor fluctuations during signal acquisition. By averaging the two differential signals and summing the values ​​of the two differential output signals, this type of fluctuation can be smoothed out. At the same time, it can also cancel out the error caused by tilting along the y-axis detection surface, further enhancing the stability of the real displacement signal and avoiding the impact of minor residual interference on subsequent detection accuracy.

[0113] Specifically, the values ​​of the two differential output signals are added together and averaged to obtain the final mean signal. This signal has basically eliminated the radial coupling interference caused by the tilt of the detection surface (including situations where the detection surface is not tilted, the detection surface is tilted along the y-axis, the detection surface is tilted along the x-axis, or the detection surfaces are tilted simultaneously along the x-axis and y-axis), and effectively suppressed the temperature drift of the sensor.

[0114] The hardware circuit for averaging and differentiating displacement signals is as follows: Figure 13 As shown, S1 and S3 are the displacement signals collected by the baseline group, and S2 and S4 are the displacement signals collected by the control group. Therefore, the baseline signal S5 is:

[0115] ;

[0116] Take the average of S1 and S3 as reference signals, such as Figure 6 As shown, this can compensate for the error caused by the tilt of the detection surface along the x-axis. Then, the reference signal S5 is differentially analyzed with signals S2 and S4 respectively to obtain signals S6 and S7, i.e.:

[0117] ;

[0118] ;

[0119] The reference signal S5 is differentially processed with signals S2 and S4 respectively, which can effectively cancel the temperature drift of the displacement signals of the four probes S1, S3, S2, and S4. Then, the average of signals S6 and S7 is taken to obtain the output signal S8.

[0120] .

[0121] The average value of signals S6 and S7 is taken, such as Figure 7 As shown, this can offset the error caused by tilting along the y-axis detection surface. Through the above mean and difference operations, the temperature drift of the sensor can be effectively suppressed when the detection surface is tilted along the x-axis, along the y-axis, along both the x-axis and y-axis, or when the detection surface is not tilted. At the same time, it can offset the reverse tilt interference and achieve precise and complete elimination of radial coupling interference, thereby significantly improving the accuracy and stability of the axial displacement signal.

[0122] In some embodiments, the signal processing unit 102 is further configured to demodulate the signal after averaging to obtain a signal for feedback of the axial displacement change of the magnetic levitation bearing rotor.

[0123] The signal after averaging is a modulated signal containing useful displacement information and carrier components. Demodulation processing uses specific algorithms or processing logic to separate the carrier components from the useful displacement information, so that the signal form and displacement change are directly correlated.

[0124] Specifically, the signal after averaging is filtered and preprocessed to initially suppress any residual high-frequency noise in the signal and prevent noise from affecting demodulation accuracy. Then, the demodulation algorithm is used to extract the changes in the signal related to axial displacement, and the extracted displacement changes are converted into a standard signal form to finally obtain an axial displacement change signal that can be used for feedback.

[0125] like Figure 13 As shown, after demodulation, the output signal S8 yields an analog voltage signal that reflects the change in axial displacement. This voltage signal no longer contains the radial coupling signal indicating the tilt of the detection surface. , Temperature drift It is also effectively suppressed. The analog voltage signal is converted into a digital signal by the analog-to-digital converter (ADC) and then input to the MCU.

[0126] The notch filter unit 103 is configured to use in-frequency notch filtering to filter the signal after mean and difference operations, in order to filter out radial coupling interference caused by insufficient flatness or unevenness of the axial displacement detection surface. The specific function and processing of the notch filter unit 103 are described in step S130.

[0127] When the surface being tested is not flat enough or is uneven, the distance between the probe and the surface being tested will change periodically as the rotor rotates. The frequency of this change is the same as the rotor speed, which causes the frequency of the radial coupling interference signal to be the same as the rotor speed. Same-frequency notch filtering can accurately identify and filter out the interference signal of this specific frequency, while retaining the useful axial displacement signal and avoiding the false filtering of useful signals of other frequencies.

[0128] In some embodiments, the center frequency of the same-frequency notch filtering is the same as the rotational speed of the magnetic levitation bearing rotor, and the input signal of the same-frequency notch filtering is the difference between the displacement signal fed back by axial detection and the reference displacement. The transfer function of the same-frequency notch filtering includes a bandwidth factor parameter, and the value of the bandwidth factor parameter is a preset value.

[0129] By detecting the real-time rotational speed of the magnetic levitation bearing rotor, and based on the correlation between rotational speed and frequency, the target frequency that matches the rotor's rotational speed is calculated. For example, if the rotor speed is 3000 rpm, then the target frequency is 50 Hz. Only by clearly identifying the frequency of the interference signal that needs to be filtered out can the signal attenuation or filtering at that frequency be accurately performed.

[0130] Specifically, the real-time rotational speed of the magnetic levitation bearing rotor is determined, and the frequency corresponding to this rotational speed is set as the target frequency for notch filtering. The displacement signal after mean and difference calculations is input into the notch filtering module. The notch filtering module uses an internal algorithm to attenuate and filter the components in the signal that are consistent with the target frequency, and finally outputs an axial displacement signal that eliminates radial coupling interference caused by insufficient flatness or unevenness of the detection surface.

[0131] like Figure 14 As shown, a frequency limiter is used in software control to filter out radially coupled interference signals and feed them back to the MCU displacement signal. With reference displacement The difference X_nf(k) is the input variable of the same-frequency limiting circuit. The transfer function of the same-frequency limiting circuit is: ,in The bandwidth factor of the notch filter. This is the rotor speed, which is the center frequency of the notch filter.

[0132] In-frequency notch filtering effectively removes interference signals that operate at the same frequency as the rotor speed, avoiding the potential impact of traditional filtering methods on the useful signal. This ensures the accuracy of the axial displacement detection signal, enabling the magnetic levitation bearing system to be controlled based on more precise displacement signals. Eliminating in-frequency interference caused by machining defects on the detection surface results in more accurate axial displacement feedback of the magnetic levitation bearing rotor. The control system can then more precisely adjust the electromagnetic force, reducing rotor oscillations caused by displacement detection errors and improving the overall system's operational stability.

[0133] This invention eliminates radial coupling signals caused by tilted installation of the detection surface by performing mean and difference operations on the displacement signal. Furthermore, it uses a software filtering algorithm to filter out radial coupling signals caused by unevenness of the detection surface and radial coupling interference signals caused by insufficient flatness of the detection surface, thereby achieving high-precision and stable operation of magnetic levitation axial displacement.

[0134] Since the processing and functions implemented by the device in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0135] The technical solution of this invention includes four displacement detection probes in the axial displacement detection area of ​​the magnetic levitation bearing. These probes are divided into two groups: the first group consists of two probes installed along a first symmetrical direction, and the second group consists of two probes installed along a second symmetrical direction orthogonal to the first symmetrical direction. Probes within the same group have identical design parameters, while probes in different groups have different design parameters. The signals collected by the four probes are averaged and differentially analyzed to eliminate radial coupling interference caused by the tilt of the detection surface. A notch filter is used to filter the processed signals to remove radial coupling interference caused by insufficient flatness or unevenness of the detection surface. This achieves high-precision and stable operation of the magnetic levitation bearing's axial displacement.

[0136] According to an embodiment of the present invention, a magnetic levitation bearing system corresponding to a displacement detection device for a magnetic levitation bearing is also provided. This magnetic levitation bearing system may include the displacement detection device for the magnetic levitation bearing described above.

[0137] Since the processing and functions implemented by the magnetic levitation bearing system in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned devices, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0138] The technical solution of this invention includes four displacement detection probes in the axial displacement detection area of ​​the magnetic levitation bearing. These probes are divided into two groups: the first group consists of two probes installed along a first symmetrical direction, and the second group consists of two probes installed along a second symmetrical direction orthogonal to the first symmetrical direction. Probes within the same group have identical design parameters, while probes in different groups have different design parameters. The signals collected by the four probes are averaged and differentially analyzed to eliminate radial coupling interference caused by the tilt of the detection surface. A notch filter is used to filter the processed signals to remove radial coupling interference caused by insufficient flatness or unevenness of the detection surface. This achieves high-precision and stable operation of the magnetic levitation bearing's axial displacement.

[0139] According to an embodiment of the present invention, a storage medium corresponding to a displacement detection method for a magnetic levitation bearing is also provided. The storage medium includes a stored program, wherein the program controls the device where the storage medium is located to execute the displacement detection method for the magnetic levitation bearing described above during runtime.

[0140] Since the processing and functions implemented by the storage medium in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned methods, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0141] The technical solution of this invention includes four displacement detection probes in the axial displacement detection area of ​​the magnetic levitation bearing. These probes are divided into two groups: the first group consists of two probes installed along a first symmetrical direction, and the second group consists of two probes installed along a second symmetrical direction orthogonal to the first symmetrical direction. Probes within the same group have identical design parameters, while probes in different groups have different design parameters. The signals collected by the four probes are averaged and differentially analyzed to eliminate radial coupling interference caused by the tilt of the detection surface. A notch filter is used to filter the processed signals to remove radial coupling interference caused by insufficient flatness or unevenness of the detection surface. This achieves high-precision and stable operation of the magnetic levitation bearing's axial displacement.

[0142] According to an embodiment of the present invention, a computer program product corresponding to a displacement detection method for a magnetic levitation bearing is also provided. The computer program product includes a computer program that, when processed and executed, implements the steps of the displacement detection method for the magnetic levitation bearing described above.

[0143] Since the processing and functions implemented by the computer program product in this embodiment are basically corresponding to the embodiments, principles and examples of the aforementioned methods, any details not covered in the description of this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0144] The technical solution of this invention includes four displacement detection probes in the axial displacement detection area of ​​the magnetic levitation bearing. These probes are divided into two groups: the first group consists of two probes installed along a first symmetrical direction, and the second group consists of two probes installed along a second symmetrical direction orthogonal to the first symmetrical direction. Probes within the same group have identical design parameters, while probes in different groups have different design parameters. The signals collected by the four probes are averaged and differentially analyzed to eliminate radial coupling interference caused by the tilt of the detection surface. A notch filter is used to filter the processed signals to remove radial coupling interference caused by insufficient flatness or unevenness of the detection surface. This achieves high-precision and stable operation of the magnetic levitation bearing's axial displacement.

[0145] In summary, it is readily understood by those skilled in the art that, without conflict, the aforementioned advantageous methods can be freely combined and superimposed.

[0146] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for detecting the displacement of a magnetic levitation bearing, characterized in that, The axial displacement detection area of ​​the magnetic levitation bearing is equipped with four displacement detection probes. These probes are used to detect the axial displacement of the magnetic levitation bearing rotor. Each of the four probes is divided into two groups: two probes in the first group are installed along a first symmetrical direction, and two probes in the second group are installed along a second symmetrical direction, with the first and second symmetrical directions being orthogonal to each other. The design parameters of the two probes in the first group are identical, and the design parameters of the two probes in the second group are identical, but the design parameters of the probes in the first group are inconsistent with those in the second group. The method includes: The displacement signals of the axial displacement detection surfaces collected by the four displacement detection probes are acquired; The four displacement signals are subjected to mean and difference operations to eliminate radial coupling interference; The signal after mean and difference operations is filtered using a notch filter to remove radial coupling interference.

2. The displacement detection method for a magnetic levitation bearing according to claim 1, characterized in that, The two displacement detection probes in the first group are installed symmetrically at 180° along the first symmetry direction, and the two displacement detection probes in the second group are installed symmetrically at 180° along the second symmetry direction.

3. The displacement detection method for a magnetic levitation bearing according to claim 1, characterized in that, The mean and difference operations are performed on the four displacement signals, including: Use either the first or second group as the baseline group and the other group as the control group; The average value of the displacement signals collected by the two displacement detection probes in the reference group is used as the reference signal; The reference signal is differentially analyzed with the displacement signals collected by the two displacement detection probes in the control group. The average of the two output signals obtained after the difference operation is calculated.

4. The displacement detection method for a magnetic levitation bearing according to claim 1 or 3, characterized in that, The method further includes: The signal after averaging is demodulated to obtain a signal for feedback of the axial displacement change of the magnetic levitation bearing rotor.

5. The displacement detection method for a magnetic levitation bearing according to claim 1, characterized in that, The center frequency of the same-frequency notch filtering is the same as the rotational speed of the magnetic levitation bearing rotor, and the input signal of the same-frequency notch filtering is the difference between the displacement signal fed back by axial detection and the reference displacement. The transfer function of the same-frequency notch filtering includes a bandwidth factor parameter, and the value of the bandwidth factor parameter is a preset value.

6. A displacement detection device for a magnetic levitation bearing, characterized in that, The axial displacement detection area of ​​the magnetic levitation bearing is equipped with four displacement detection probes. These probes are used to detect the axial displacement of the magnetic levitation bearing rotor. Each of the four probes is divided into two groups: two probes in the first group are installed along a first symmetrical direction, and two probes in the second group are installed along a second symmetrical direction, with the first and second symmetrical directions being orthogonal to each other. The design parameters of the two probes in the first group are identical, and the design parameters of the two probes in the second group are identical, but the design parameters of the probes in the first group are inconsistent with those in the second group. The device includes: The signal acquisition unit is configured to acquire the displacement signals of the axial displacement detection surface acquired by the four displacement detection probes; The signal processing unit is configured to perform mean and difference operations on the four displacement signals to eliminate radial coupling interference; The notch filter unit is configured to use in-frequency notch filtering to filter the signal after mean and difference operations in order to filter out radial coupling interference.

7. A magnetic levitation bearing system, characterized in that, include: The displacement detection device for magnetic levitation bearings as described in claim 6.

8. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the displacement detection method for the magnetic levitation bearing as described in any one of claims 1 to 5.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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