Inductive displacement sensor of magnetic suspension bearing and magnetic suspension bearing

Abstract

The invention provides an inductive displacement sensor of a magnetic suspension bearing and the magnetic suspension bearing, the inductive displacement sensor of the magnetic suspension bearing comprises a rotating shaft, a first probe, a second probe and a third probe, the first probe, the second probe and the third probe are all located at the periphery of the rotating shaft, the rotating shaft has an axis direction, the first probe is located at a first axial position, and the second probe is located at a second axial position; the second probe is located at a second axial position, the third probe is located at a third axial position, and the second axial position is located between the first axial position and the third axial position in the axial direction; the first probe and the second probe can detect the axial displacement and radial displacement of the rotating shaft, and the third probe can detect the radial displacement of the rotating shaft so as to compare and compensate the radial displacement of the rotating shaft detected by the first probe and the second probe. According to the invention, the interference of axial displacement on the radial detection of the first and second probes (wedge-shaped probes) can be reduced, the detection error is reduced, and the precision of axial and radial displacement detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic levitation bearings, and particularly to an inductive displacement sensor and a magnetic levitation bearing for a magnetic levitation bearing. Background Art

[0002] When a magnetic levitation bearing is working, the rotating shaft is levitated in the air by electromagnetic force, so that mechanical contact between the rotating shaft and the stator of the magnetic bearing is avoided. Compared with mechanical bearings, it has the advantages of no mechanical wear, no need for lubrication, long service life, high rotational speed and strong reliability. Therefore, it is widely used in high-speed rotating industrial manufacturing fields such as flywheel energy storage, molecular pumps, compressors, aerospace, etc. In order for the rotating shaft to rotate continuously and stably during operation, a displacement sensor needs to be used to monitor the axial center trajectory of the rotating shaft. At present, the non-contact displacement sensors widely used in the field of magnetic levitation bearing systems mainly include eddy current displacement sensors, capacitive displacement sensors and inductive displacement sensors. Among them, eddy current displacement sensors need to use high-frequency alternating current signals above 400 kHz, have weak anti-electromagnetic interference ability, and are greatly affected by temperature, so the detection accuracy is relatively low. Capacitive displacement sensors monitor the displacement change of the rotating shaft by detecting the change of the capacitance value between the surface of the rotating shaft and the probe. The detection accuracy is easily affected by media such as dust and oil in the air, and is not suitable for industrial sites with complex working conditions.

[0003] The inductive displacement sensor detects the displacement change of the rotating shaft by changing the inductance of the probe coil due to the change of the magnetic conduction area corresponding to the coil probe and the rotating shaft. Therefore, the sensitivity and detection accuracy of the inductive displacement sensor depend on the detection surface area in the sensor probe and the gap between the probe and the rotating shaft. For existing inductive displacement sensors, both radial displacement detection and axial displacement detection adopt an independent installation structure, which requires a large installation space, and the detection surface area of the sensor probe is small. When the displacement of the rotating shaft changes, the inductance change of the sensor probe coil is small, so the sensitivity and detection accuracy of the sensor are relatively low.

[0004] After a patent search, the patents and literature related to the present invention are as follows:

[0005] In the sensor of the patent with the patent number CN212717638U, namely "a highly sensitive inductive radial and axial displacement sensor in a magnetic levitation bearing", the sensor stator laminations are arranged outside the sensor rotor laminations. The stator probe is wedge-shaped, and the corresponding rotor part becomes an inclined plane with the same inclination angle. The rotor inclined plane part is made of a magnetic conductive material. When the stator and rotor move axially relative to each other, the area of the magnetic conductive material of the rotor corresponding to the wedge-shaped probe of the sensor and the air gap between the stator and rotor change, thereby monitoring the displacement trajectory of the rotating shaft. In this patent, the axial displacement and radial displacement of the rotor are detected by the changes in the area of the magnetic conductive material corresponding to the left and right wedge-shaped probes of the stator and the air gap change. However, since the inductive displacement sensor of this patent detects through the change in the area of the magnetic conductive material of the wedge-shaped probe, there is interference between each detection channel. When calculating the displacement change in the radial direction, the calculation error is large and it is easily interfered. Moreover, the area of the magnetic conductive material corresponding to the probe in the radial direction of the rotor is small, resulting in a low sensitivity in the radial direction.

[0006] In the patent with the patent number CN117249164A, namely "an axial and radial self-inductive displacement sensor for a magnetic levitation bearing system", the stator core of the sensor is a circular ring core with magnetic poles in the inner ring. The coil is wound around the magnetic pole probe, and the magnetic pole probe is aligned with the rotor step surface. The axial and radial displacements of the rotor are detected by changing the effective magnetic pole area of the magnetic pole probe. Since in the sensor structure proposed in this patent, it can only detect the axial and radial displacements of the rotor through a single magnetic pole probe, when detecting the displacement change of the rotor, the calculation error will be relatively large, and the magnetic conductive area is relatively small, and the change in the inductance of the probe is small, resulting in a low sensitivity of the sensor.

[0007] Due to the technical problems that the inductive displacement sensor of the magnetic levitation bearing in the prior art has interference caused by axial / radial displacement to the radial / axial detection of the probe, resulting in low detection accuracy, etc., the present invention researches and designs an inductive displacement sensor for a magnetic levitation bearing and a magnetic levitation bearing. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the inductive displacement sensor of the magnetic levitation bearing in the prior art has interference caused by axial / radial displacement to the radial / axial detection of the probe, resulting in low detection accuracy, so as to provide an inductive displacement sensor for a magnetic levitation bearing and a magnetic levitation bearing.

[0009] To solve the above problems, the present invention provides an inductive displacement sensor for a magnetic levitation bearing, which includes:

[0010] A rotating shaft, a first probe, a second probe, and a third probe. The first probe, the second probe, and the third probe are all located on the outer periphery of the rotating shaft. The rotating shaft has an axial direction. The first probe is located at a first axial position, the second probe is located at a second axial position, and the third probe is located at a third axial position. Along the axial direction, the third axial position is located between the first axial position and the second axial position;

[0011] The first probe and the second probe can detect the axial displacement and radial displacement of the rotating shaft, and the third probe can detect the radial displacement of the rotating shaft to compare and compensate the radial displacement of the rotating shaft detected by the first probe and the second probe.

[0012] In some embodiments,

[0013] The surface of the first probe facing the rotating shaft is the first surface. In the vertical cross-sectional plane passing through the axis of the rotating shaft, the first surface is not parallel to the axis of the rotating shaft. The outer peripheral surface of the rotating shaft has a second surface, and the second surface is also not parallel to the axis of the rotating shaft. And the first surface and the second surface are opposite and parallel, and can detect the axial and / or radial displacement of the rotating shaft through the change in the distance between the first surface and the second surface during the axial and / or radial movement of the rotating shaft;

[0014] The surface of the second probe facing the rotating shaft is the third surface. In the vertical cross-sectional plane passing through the axis of the rotating shaft, the third surface is not parallel to the axis of the rotating shaft. The outer peripheral surface of the rotating shaft has a fourth surface, and the fourth surface is also not parallel to the axis of the rotating shaft. And the third surface and the fourth surface are opposite and parallel, and can detect the axial and / or radial displacement of the rotating shaft through the change in the distance between the third surface and the fourth surface during the axial and / or radial movement of the rotating shaft;

[0015] The surface of the third probe facing the rotating shaft is the fifth surface. In the vertical cross-sectional plane passing through the axis of the rotating shaft, the fifth surface is parallel to the axis of the rotating shaft. The outer peripheral surface of the rotating shaft has a sixth surface, and the sixth surface is also parallel to the axis of the rotating shaft. And the fifth surface and the sixth surface are opposite and parallel, and can detect the radial displacement of the rotating shaft through the change in the distance between the fifth surface and the sixth surface during the radial movement of the rotating shaft.

[0016] In some embodiments,

[0017] The outer normal of the second surface extends away from the axis of the rotating shaft and also extends away from the fourth surface, and the outer normal of the fourth surface extends away from the axis of the rotating shaft and also extends away from the second surface, and the outer normals of the second surface and the fourth surface do not intersect.

[0018] In some embodiments,

[0019] The second surface, the sixth surface and the fourth surface are sequentially connected along the axis direction of the rotating shaft, and a convex portion protruding radially outward is formed at the second surface, the sixth surface and the fourth surface with respect to the outer peripheral surface of the rotating shaft.

[0020] In some embodiments,

[0021] In a vertical cross-sectional plane passing through the axis of the rotating shaft, both the second surface and the fourth surface are inclined surfaces. One end of the second surface is connected to the outer peripheral surface of the rotating shaft, and the other end gradually extends radially outward to be connected to one end of the sixth surface. One end of the fourth surface is connected to the outer peripheral surface of the rotating shaft, and the other end gradually extends radially outward to be connected to the other end of the sixth surface, so that the outer diameter dimension of the outer periphery of the sixth surface is the largest part on the rotating shaft.

[0022] In some embodiments,

[0023] In a vertical cross-sectional plane passing through the axis of the rotating shaft, both the first probe and the second probe are located on one side of the axis of the rotating shaft, and the third probe is located on the other side of the axis of the rotating shaft.

[0024] In some embodiments,

[0025] The first probe and the second probe form a first probe unit. Two first probe units are adjacent and spaced along the circumferential direction of the rotating shaft to form a first probe unit group. Two adjacent third probes along the circumferential direction of the rotating shaft form a second probe unit. Both the first probe unit group and the second probe unit are multiple, and the first probe unit group and the second probe unit are staggered and spaced along the circumferential direction.

[0026] In some embodiments,

[0027] In the first probe unit, a first probe coil is wound around the first probe, a second probe coil is wound around the second probe, and the first probe coil and the second probe coil are connected and conduct electricity; in the second probe unit, a third probe coil is wound around one of the adjacent third probes, a fourth probe coil is wound around the other third probe, and the third probe coil and the fourth probe coil are connected and conduct electricity.

[0028] In some embodiments,

[0029] It includes a first layer of stator silicon steel sheets, a second layer of stator silicon steel sheets and a third layer of stator silicon steel sheets. The first layer of stator silicon steel sheets, the second layer of stator silicon steel sheets and the third layer of stator silicon steel sheets are all of annular structures. Along the axial direction of the rotating shaft, the third layer of stator silicon steel sheets is clamped between the first layer of stator silicon steel sheets and the second layer of stator silicon steel sheets. And the first probe is protrudingly arranged on the inner peripheral wall of the first layer of stator silicon steel sheets towards the radially inner side, the second probe is protrudingly arranged on the inner peripheral wall of the second layer of stator silicon steel sheets towards the radially inner side, and the third probe is protrudingly arranged on the inner peripheral wall of the third layer of stator silicon steel sheets towards the radially inner side.

[0030] In some embodiments,

[0031] The rotating shaft includes a shaft section with an integral magnetic conduction structure, that is, a rotating shaft magnetic conductor. The rotating shaft magnetic conductor sequentially extends from the shaft section opposite to the first probe through the shaft section opposite to the third probe and the shaft section opposite to the second probe, so that the first probe, the second probe and the third probe are all opposite to the rotating shaft magnetic conductor.

[0032] In some embodiments,

[0033] When the rotating shaft does not shift, the initial inductance of the first probe is L 01 , the initial inductance of the second probe is L 02 , the input voltage is U s , then:

[0034]

[0035] Where δ0 represents the initial air gap, W1 represents the number of turns of the probe coil, A0 represents the initial magnetic pole area of the probe, μ0 is the magnetic permeability, and δ1, δ2 represent the air gaps formed by the change of the initial air gap δ0 after the rotor undergoes displacement changes;

[0036] When the rotating shaft axially displaces and surges by Δδ in the direction of the second probe, the magnetic conduction surface A2 of the second probe becomes larger, the air gap δ2 between the second probe and the rotating shaft decreases, δ2 = (δ0 - Δδ), and the inductance L2 of the second probe increases; the magnetic conduction surface A1 of the first probe becomes smaller, the air gap δ1 between the first probe and the rotating shaft increases, δ1 = δ0 + Δδ, and the inductance L1 of the first probe decreases. At this time:

[0037]

[0038] Therefore, the axial output voltage is:

[0039] In some embodiments,

[0040] When the rotating shaft does not have radial offset and is at the center of rotation, the initial gaps between multiple third probes and the rotating shaft are all δ′0, their number of coil turns are all W2, the magnetic conduction area is A′0, and the initial inductances of the two upper third probes are respectively L 08 and L 11 , and the initial inductances of the two lower third probes are respectively L 10 and L 12 , the input voltage is U s , then:

[0041]

[0042] When the rotating shaft radially displaces and surges downward by Δδ′, the air gaps δ′1 between the two lower third probes and the rotating shaft decrease, and the inductances L5 and L6 increase. The air gaps δ′2 between the two upper third probes and the rotating shaft increase, and the inductances L3 and L4 decrease. At this time:

[0043]

[0044] Therefore, the radial output voltage of multiple third probes in the middle layer is:

[0045] And assume that the magnetic conduction surface of the second probe at this time is A′2, the gap is δ″2, the magnetic conduction surface A′1 of the first probe, the gap is δ″1, A′1 = A′2, δ″1 = δ″2;

[0046] At this time, the radial output voltage in the first and second probes is:

[0047] Finally, the radial output voltage U j0 of the middle layer stator and the radial output voltage U′ z0 in the upper and lower layer wedge-shaped probes, after normalization, the final radial detection output voltage of the sensor is:

[0048] U′0 = k * U j0 +(1 - k) * U′ z0 , where k is a constant.

[0049] The present invention also provides a magnetic levitation bearing, which includes the inductive displacement sensor of the aforementioned magnetic levitation bearing.

[0050] The inductive displacement sensor and the magnetic levitation bearing of a magnetic levitation bearing provided by the present invention have the following beneficial effects:

[0051] 1. By adopting the first and second probes capable of detecting the axial displacement and the radial displacement of the rotating shaft, the present invention can detect the axial and radial displacements. Further, by using the third probe capable of detecting the radial displacement of the rotating shaft, the radial displacement of the rotating shaft can be detected, so as to compare and compensate the radial displacement of the rotating shaft detected by the first probe and the second probe, reduce the interference of the axial displacement on the radial detection of the first and second probes (wedge-shaped probes), improve the detection accuracy. Through the effective combination structure of the above two probes for simultaneously detecting the axial and radial displacements of the shaft and one probe for detecting the radial displacement, the interference can be further reduced, the detection error can be minimized, and the detection accuracy of the axial and radial displacements can be improved.

[0052] 2. For the highly sensitive integrated inductive displacement sensor for radial and axial directions of the magnetic levitation bearing proposed by the present invention, the entire stator of the sensor is divided into upper, middle, and lower parts along the central axis. Wedge-shaped coil probes are evenly distributed along the circumferential direction on the upper and lower stator parts for detecting the axial and radial displacements of the rotor, and the sensor probes evenly distributed along the circumferential direction of the middle stator are used for detecting the radial displacement of the rotor. That is, when the rotor moves axially, the relative magnetic permeability area and the gap change, increasing the inductance change of the axial probe coil and enhancing the sensitivity of the sensor. When the rotor deviates radially, the wedge-shaped probes of the upper and lower stator parts and the radial probes of the middle stator can all detect the radial displacement deviation of the rotor, reducing the calculation error of detecting the radial displacement, improving the detection accuracy of the sensor, and realizing the integration of the radial and axial displacement detection of the rotating shaft, saving the installation space of the sensor and eliminating the interference between the sensor probes.

[0053] 3. The present invention further includes a shaft section of the rotating shaft that is an integral magnetic conduction structure, namely, a rotating shaft magnetic conductor. The rotating shaft magnetic conductor sequentially extends from the shaft section opposite to the first probe through the shaft section opposite to the third probe and the shaft section opposite to the second probe, such that the first probe, the second probe, and the third probe are all opposite to the rotating shaft magnetic conductor, which can further increase the magnetic conduction area and further improve the detection accuracy and detection performance. The present invention further forms a protruding portion that protrudes radially outward relative to the outer peripheral surface of the rotating shaft at the second surface, the sixth surface, and the fourth surface, where the second surface, the sixth surface, and the fourth surface are sequentially connected along the axial direction of the rotating shaft, which can further increase the magnetic conduction area of the magnetic conduction portion and further improve the detection accuracy and detection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a three-dimensional structure diagram of the high-sensitivity radial and axial integrated inductive displacement sensor for a magnetic levitation bearing according to the present invention;

[0055] Figure 2 is a working schematic diagram of the high-sensitivity radial and axial integrated inductive displacement sensor for a magnetic levitation bearing according to the present invention;

[0056] Figure 3 is a working schematic diagram of the inductive sensor of the magnetic levitation bearing according to the present invention when the rotor is axially displaced;

[0057] Figure 4 is a working schematic diagram of the inductive sensor of the magnetic levitation bearing according to the present invention when the rotor is radially displaced.

[0058] The reference numerals are represented as:

[0059] 1, first probe coil; 2, first probe; 3, second probe; 4, second probe coil; 5, rotating shaft; 6, rotating shaft magnetic conductor; 7, third probe coil; 8, third probe; 9, fourth probe coil; 10, first layer of stator silicon steel sheet; 11, second layer of stator silicon steel sheet; 12, third layer of stator silicon steel sheet; A, first surface; B, second surface; C, third surface; D, fourth surface; E, fifth surface; F, sixth surface. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0061] It should be noted that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0062] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, further discussion thereof is not required in subsequent drawings.

[0063] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be construed as limiting the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0064] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper", etc. may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the corresponding explanations will be made for the spatial relative descriptions used herein.

[0065] In addition, it should be noted that the use of terms such as "first" and "second" to define components is merely for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meanings, and thus should not be construed as limiting the protection scope of the present invention.

[0066] As Figures 1-4 shown, the present invention provides an inductive displacement sensor for a magnetic levitation bearing, which includes:

[0067] a rotating shaft 5, a first probe 2, a second probe 3, and a third probe 8. The first probe 2, the second probe 3, and the third probe 8 are all located on the outer periphery of the rotating shaft 5. The rotating shaft 5 has an axial direction. The first probe 2 is located at a first axial position, the second probe 3 is located at a second axial position, and the third probe 8 is located at a third axial position. Along the axial direction, the third axial position is located between the first axial position and the second axial position;

[0068] The first probe 2 and the second probe 3 can detect the axial displacement and the radial displacement of the rotating shaft 5, and the third probe 8 can detect the radial displacement of the rotating shaft 5 to compare and compensate for the radial displacement of the rotating shaft 5 detected by the first probe 2 and the second probe 3.

[0069] By adopting the first and second probes capable of detecting the axial displacement and radial displacement of the rotating shaft, the present invention can detect the axial and radial displacements. Further, by means of the third probe capable of detecting the radial displacement of the rotating shaft, the radial displacement of the rotating shaft can be detected. Thus, the radial displacements of the rotating shaft detected by the first probe and the second probe can be compared and compensated, reducing the interference of the axial displacement on the radial detection of the first and second probes (wedge probes), improving the detection accuracy. Through the effective combination structure of the above two probes for simultaneously detecting the axial and radial displacements of the shaft and one probe for detecting the radial displacement, the interference can be further reduced, the detection error can be minimized, and the detection accuracy of the axial and radial displacements of the shaft can be improved.

[0070] The high-sensitivity radial and axial integrated inductive displacement sensor structure of the magnetic levitation bearing of the present invention is as Figure 1 shown. This structure designs the conventional integral stator structure into three stator modules of upper, middle, and lower parts (i.e., the first, second, and third layers of stator silicon steel sheets). Among them, the stator pole columns of the upper and lower parts are designed as wedge-shaped pole columns (the first probe 2 and the second probe 3), increasing the magnetic conduction area between the probe and the rotor. The shape of the rotor of this sensor is as follows: in the middle is a horizontal plane that matches the middle stator probe of the sensor (the third probe 8), and the two ends of the horizontal plane are designed as convex ramp surfaces parallel to the magnetic conduction surfaces of the upper and lower wedge-shaped stator probes (the first probe 2 and the second probe 3), and the overall material of the rotating shaft needs to be a magnetic conduction material. Along the circumferential direction of the stator, various sensor probe coils are evenly distributed on the three parts of the stator module. And the central axes of the (group of) sensor probes on each stator module intersect at 90 degrees, so that the crosstalk displacement of the rotating shaft can be accurately detected in the mutually orthogonal radial directions. It is particularly proposed that during the assembly process of the sensor, first, the upper layer and the middle layer of the sensor are inserted from one end of the rotor, and it is ensured that the inclined surface of the wedge-shaped pole column always remains relatively parallel to the inclined surface of the rotor. Subsequently, the lower stator of the sensor is inserted from the other end of the rotor, and finally, the entire stator structure is fixed through the sensor end cover.

[0071] Figure 2 The cross-sectional view of the high-sensitivity radial and axial integrated inductive displacement sensor of the magnetic levitation bearing working on the rotating shaft is shown as in the figure. The working principle of the inductive displacement sensor is that when the displacement of the rotating shaft changes, the impedance of the sensor probe coil will change accordingly, and thus the crosstalk displacement generated by the rotating shaft can be obtained according to the impedance change of the probe coil. The impedance change of the probe coil is related to the size of the magnetic conduction surface of the rotating shaft and the gap between the two. Therefore, the sensitivity and detection accuracy of the inductive displacement sensor depend on the detection surface area in the sensor probe and the gap between the probe and the rotating shaft.

[0072] In some embodiments,

[0073] The surface of the first probe 2 facing the rotating shaft 5 is the first surface A. In the vertical section plane passing through the axis of the rotating shaft 5, the first surface A is not parallel to the axis of the rotating shaft 5. The outer peripheral surface of the rotating shaft 5 has a second surface B, and the second surface B is also not parallel to the axis of the rotating shaft 5. Moreover, the first surface A and the second surface B are opposite and parallel, and can detect the axial and / or radial displacement of the rotating shaft 5 through the change in the distance between the first surface A and the second surface B during the axial and / or radial movement of the rotating shaft 5;

[0074] The surface of the second probe 3 facing the rotating shaft 5 is the third surface C. In the vertical section plane passing through the axis of the rotating shaft 5, the third surface C is not parallel to the axis of the rotating shaft 5. The outer peripheral surface of the rotating shaft 5 has a fourth surface D, and the fourth surface D is also not parallel to the axis of the rotating shaft 5. Moreover, the third surface C and the fourth surface D are opposite and parallel, and can detect the axial and / or radial displacement of the rotating shaft 5 through the change in the distance between the third surface C and the fourth surface D during the axial and / or radial movement of the rotating shaft 5;

[0075] The surface of the third probe 8 facing the rotating shaft 5 is the fifth surface E. In the vertical section plane passing through the axis of the rotating shaft 5, the fifth surface E is parallel to the axis of the rotating shaft 5. The outer peripheral surface of the rotating shaft 5 has a sixth surface F, and the sixth surface F is also parallel to the axis of the rotating shaft 5. Moreover, the fifth surface E and the sixth surface F are opposite and parallel, and can detect the radial displacement of the rotating shaft 5 through the change in the distance between the fifth surface E and the sixth surface F during the radial movement of the rotating shaft 5.

[0076] This is a further preferred structural form of the inductive displacement sensor of the magnetic levitation bearing of the present invention. That is, the first probe and the rotating shaft are arranged as a first surface and a second surface that are parallel to each other and inclined to the axis of the rotating shaft. Thus, when the rotating shaft undergoes axial movement or radial movement, the axial and radial displacement values of the rotating shaft can be obtained through the inductance change generated by the distance between the first and second surfaces inclined to the axis of the rotating shaft. Then, the second probe and the rotating shaft are arranged as a third surface and a fourth surface that are parallel to each other and inclined to the axis of the rotating shaft. Thus, when the rotating shaft undergoes axial movement or radial movement, the axial and radial displacement values of the rotating shaft can be obtained through the inductance change generated by the distance between the third and fourth surfaces inclined to the axis of the rotating shaft. By converting the inductance values detected by the first probe and the second probe, the displacement value of the rotating shaft moving axially in a certain direction can be obtained. However, there is still a situation where the conversion of radial displacement through the radial inductance of the first and second probes is interfered by axial displacement, and the accuracy is not high enough. At this time, the present invention further combines the third probe with the fifth and sixth surfaces parallel to the rotating shaft, and these two surfaces are parallel to the axis of the rotating shaft, so as to be able to detect the inductance value generated by the radial displacement of the rotating shaft, and then compare and convert it with the radial displacement inductance values detected by the first and second probes, so as to be able to obtain accurate radial and axial displacement values of the rotating shaft, effectively improving the detection accuracy of the displacement sensor.

[0077] The inductive displacement sensor proposed by the present invention divides its entire stator into upper, middle, and lower parts along the central axis. The upper and lower stator parts are circumferentially distributed with coil probes having a certain slope, and the middle stator part is circumferentially distributed with coil probes for detecting the radial displacement of the rotating shaft, realizing an integrated design of radial displacement detection and axial displacement detection of the magnetic levitation bearing, saving the installation space of the sensor, and at the same time eliminating the interference between each detection channel, and can effectively improve the detection accuracy and sensitivity of the sensor.

[0078] 1. The present invention proposes a highly sensitive radial and axial integrated inductive displacement sensor for a magnetic levitation bearing. The sensor stator is divided into upper, middle, and lower parts. The sensor probes evenly distributed along the circumference of the upper and lower parts are used to detect the axial and radial displacements of the rotor, and the sensor probes evenly distributed along the circumference of the middle part are used to detect the radial displacement of the rotor, realizing the integration of radial and axial displacement detection of the rotating shaft, saving the installation space of the sensor, eliminating the interference between each sensor probe, and improving the detection accuracy of the sensor.

[0079] 2. In the present invention, the shapes of the stator coil probes of the upper and lower parts of the sensor are designed as wedges at a certain angle, increasing the magnetic conduction area between the probes and the rotor. That is, when the rotor moves axially, the relative magnetic conduction area and gap between the two change, increasing the inductance change of the axial probe coil and improving the sensitivity of the sensor.

[0080] In some embodiments,

[0081] While the outer normal of the second surface B extends away from the axis of the rotating shaft 5, it also extends away in a direction away from the fourth surface D. While the outer normal of the fourth surface D extends away from the axis of the rotating shaft 5, it also extends away in a direction away from the second surface B, and the outer normals of the second surface B and the fourth surface D do not intersect.

[0082] This is a further preferred setting form of the second and fourth surfaces on the rotating shaft of the present invention, that is, the outer normals of the second surface and the fourth surface extend in directions away from each other, which can cooperate with the first probe and the second probe respectively to detect the displacement value of the rotating shaft moving in a specific axis direction, and can also make the second surface, the fourth surface and the sixth surface form a structure with the middle bulging radially outward relative to the rotating shaft, thereby increasing the induction area and volume between this part and each probe, and further improving the accuracy value of the probe for detecting the displacement of the rotating shaft.

[0083] In some embodiments,

[0084] The second surface B, the sixth surface F and the fourth surface D are sequentially connected along the axis direction of the rotating shaft 5, and a convex portion bulging radially outward relative to the outer circumference of the rotating shaft 5 is formed at the second surface B, the sixth surface F and the fourth surface D.

[0085] By arranging the second surface, the sixth surface and the fourth surface on the rotating shaft of the present invention to be sequentially connected, and the structure formed by the three is a convex portion bulging radially outward relative to the rotating shaft, the induction area and induction volume of the part that can effectively increase the induction with multiple probes can be improved, thereby further improving the accuracy value of the probe for detecting the displacement of the rotating shaft.

[0086] In some embodiments,

[0087] In a vertical cross-sectional plane passing through the axis of the rotating shaft 5, both the second surface B and the fourth surface D are inclined surfaces. One end of the second surface B is connected to the outer circumference of the rotating shaft 5, and the other end gradually extends radially outward to connect with one end of the sixth surface F. One end of the fourth surface D is connected to the outer circumference of the rotating shaft 5, and the other end gradually extends radially outward to connect with the other end of the sixth surface F, so that the outer diameter dimension of the radially outer circumference of the sixth surface F is the largest part on the rotating shaft 5.

[0088] By the inclined surface structures of the second surface and the fourth surface respectively tilting in opposite directions, and the two are connected by the sixth surface, and the sixth surface is parallel to the axis, so that the part of the rotating shaft surrounded by the sixth surface forms the part with the largest outer diameter dimension on the rotating shaft, effectively increasing the induction area and induction volume of the part on the rotating shaft that can induce with multiple probes, thereby further improving the accuracy value of the probe for detecting the displacement of the rotating shaft.

[0089] Further preferably, the structure enclosed by the second surface is a ring frustum structure, the structure enclosed by the sixth surface is a ring cylinder structure, and the structure enclosed by the fourth surface is also a ring frustum structure.

[0090] In some embodiments,

[0091] In the vertical cross-sectional plane passing through the axis of the rotating shaft 5, both the first probe 2 and the second probe 3 are located on one side of the axis of the rotating shaft 5, and the third probe 8 is located on the other side of the axis of the rotating shaft 5.

[0092] This is a further preferred structural form of the present invention, that is, the first and second probes are located on one side of the axis in the vertical cross-section, and the third probe is located on the other side of the axis of the rotating shaft, so that it is not necessary to squeeze all three probes on the same side, resulting in an extension of the magnetically conductive part of the rotating shaft. While ensuring that all three probes can sense and detect, the structure can be made more compact and the volume can be reduced.

[0093] In some embodiments,

[0094] The first probe 2 and the second probe 3 form a first probe unit. Two first probe units are adjacent and spaced along the circumferential direction of the rotating shaft 5 to form a first probe unit group. Two adjacent third probes 8 along the circumferential direction of the rotating shaft 5 form a second probe unit. Both the first probe unit group and the second probe unit are multiple, and the first probe unit group and the second probe unit are staggered and spaced along the circumferential direction.

[0095] In the present invention, by processing the first and second probes to form a first probe unit, having two first probe units in the circumferential direction and forming a first probe unit group, the detection accuracy of the radial and axial displacements of the rotating shaft can be enhanced in the circumferential direction. By arranging two or more third probes in the circumferential direction to form a second probe unit, the detection and verification accuracy of the radial displacement can be enhanced in the circumferential direction. And the first probe unit group and the second probe unit are staggered and spaced along the circumferential direction, which can improve the accuracy of the detection of the axial and radial displacements at various positions of the rotating shaft in the circumferential direction and improve the accuracy of uniform detection.

[0096] In some embodiments,

[0097] In the first probe unit, a first probe coil 1 is wound around the first probe 2, a second probe coil 4 is wound around the second probe 3, and the first probe coil 1 and the second probe coil 4 are connected and conduct; in the second probe unit, a third probe coil 7 is wound around one of the adjacent third probes 8, a fourth probe coil 9 is wound around the other third probe 8, and the third probe coil 7 and the fourth probe coil 9 are connected and conduct.

[0098] In the present invention, the coils wound around the first probe and the second probe are connected and conducted, enabling the formation of a current-conducting structure between the two, thereby detecting their respective inductances and obtaining the radial and axial displacement values of the rotating shaft. The third probe has two adjacent ones, and the third probe coil and the fourth probe coil wound around the two adjacent third probes are connected and conducted respectively, thereby forming a conduction loop of the third probe, obtaining the inductance, and obtaining the radial displacement value of the rotating shaft. The radial displacement obtained by the first and second probes is compared and verified radially, thereby improving the accuracy of detecting the radial and axial displacements of the rotating shaft.

[0099] In some embodiments,

[0100] It includes a first-layer stator silicon steel sheet 10, a second-layer stator silicon steel sheet 11, and a third-layer stator silicon steel sheet 12. The first-layer stator silicon steel sheet 10, the second-layer stator silicon steel sheet 11, and the third-layer stator silicon steel sheet 12 are all annular structures. Along the axial direction of the rotating shaft 5, the third-layer stator silicon steel sheet 12 is clamped between the first-layer stator silicon steel sheet 10 and the second-layer stator silicon steel sheet 11. And the first probe 2 is protrudingly arranged on the inner peripheral wall of the first-layer stator silicon steel sheet 10 towards the radially inner side, the second probe 3 is protrudingly arranged on the inner peripheral wall of the second-layer stator silicon steel sheet 11 towards the radially inner side, and the third probe 8 is protrudingly arranged on the inner peripheral wall of the third-layer stator silicon steel sheet 12 towards the radially inner side.

[0101] The high-sensitivity radial and axial integrated inductive displacement sensor for a magnetic levitation bearing proposed by the present invention divides the entire stator of the sensor into upper, middle, and lower parts (i.e., the first, second, and third-layer stator silicon steel sheets) along the central axis. There are wedge-shaped coil probes (the first and second probes) evenly distributed in the circumferential direction on the upper and lower parts of the stator, which are used to detect the axial and radial displacements of the rotor. The sensor probes evenly distributed along the circumferential direction of the middle stator are used to detect the radial displacement of the rotor. That is, when the rotor moves axially, the relative magnetic permeability area and gap between the two change, increasing the inductance change of the axial probe coil and improving the sensitivity of the sensor. When the rotor deviates radially, the wedge-shaped probes on the upper and lower parts of the stator and the radial probes on the middle stator can all detect the radial displacement deviation of the rotor, reducing the calculation error of detecting the radial displacement, improving the detection accuracy of the sensor, and realizing the integration of detecting the radial and axial displacements of the rotating shaft, saving the installation space of the sensor and eliminating the interference between each sensor probe.

[0102] In some embodiments,

[0103] The rotating shaft 5 includes an entire shaft section with a magnetic conductive structure, namely, a rotating shaft magnetizer 6. The rotating shaft magnetizer 6 extends from the shaft section opposite to the first probe 2 through the shaft section opposite to the third probe 8 and the shaft section opposite to the second probe 3 in sequence, so that the first probe 2, the second probe 3 and the third probe 8 are all opposite to the rotating shaft magnetizer 6.

[0104] The present invention also includes a shaft segment with a whole magnetic conductive structure, namely a shaft magnet, through a rotating shaft. The shaft magnet extends from the shaft segment opposite to the first probe through the shaft segment opposite to the third probe and the shaft segment opposite to the second probe in sequence, so that the first probe, the second probe and the third probe are all opposite to the rotating shaft magnet, which can further increase the magnetic conductive area and further improve the detection accuracy and detection performance.

[0105] In some embodiments,

[0106] When the rotating shaft 5 is not offset, the initial inductance of the first probe 2 is L 01 , the initial inductance of the second probe 3 is L 02 , the input voltage is U s ,but:

[0107]

[0108] Where δ0 represents the initial air gap, W1 represents the number of turns of the probe coil, A0 represents the initial magnetic pole area of ​​the probe, μ0 represents the magnetic permeability, and δ1 and δ2 represent the air gaps formed by the initial air gap δ0 after the rotor displacement changes;

[0109] When the shaft 5 undergoes an axial displacement Δδ toward the second probe 3, the magnetic conductive surface A2 of the second probe 3 becomes larger, the air gap δ2 between the second probe and the shaft decreases, δ2=(δ0-Δδ), and the inductance L2 of the second probe increases; the magnetic conductive surface A1 of the first probe 2 becomes smaller, the air gap δ1 between the first probe and the shaft increases, δ1=δ0+Δδ, and the inductance L1 of the first probe decreases. At this time:

[0110]

[0111] Therefore, the axial output voltage is:

[0112] This is the preferred method of detecting the axial displacement of the rotating shaft of the present invention, which can accurately obtain the displacement of the axial movement of the rotating shaft. Figure 3The figure shows a schematic diagram of the operation of the sensor when the rotor is axially offset. The initial gap between the wedge probe and the rotating shaft is δ0, and the probe coils of the two are connected in series (forming a variable air gap differential structure). The wedge probes on the sensor are all W1, and the corresponding two wedge probes on the upper and lower stators are wound into a variable air gap differential structure. In the operation of the sensor proposed by the present invention, when the rotating shaft is axially displaced to the right, the relative magnetic conductive area between the wedge probe on the right sensor stator and the rotating shaft increases and the axial gap decreases, thereby increasing the inductance increase of the wedge probe coil; while the relative magnetic conductive area between the wedge probe on the left sensor stator and the rotating shaft decreases and the axial gap increases, thereby also increasing the inductance reduction of the wedge probe coil. Finally, the inductance change signal of the wedge probe coil is differentially performed, thereby greatly improving the axial detection sensitivity of the sensor.

[0113] In some embodiments,

[0114] When the shaft 5 is not radially offset and is at the center of rotation, the initial gaps between the plurality of third probes 8 and the shaft 5 are all δ′0, the number of turns of the coils are all W2, the magnetic conductive area is A′0, and the initial inductances of the two third probes located at the top are L 08 and L 11 The initial inductances of the two third probes located below are L 10 and L 12 , the input voltage is U s ,but:

[0115]

[0116] When the shaft 5 undergoes a radial displacement Δδ′ downward, the air gap δ′1 between the two third probes at the bottom and the shaft decreases, the inductances L5 and L6 increase, the air gap δ′2 between the two third probes at the top and the shaft increases, and the inductances L3 and L4 decrease. At this time:

[0117]

[0118] Therefore, the radial output voltage of the plurality of third probes 8 in the middle layer is:

[0119] And suppose that the magnetic conductive surface of the second probe 3 is A′2, the gap is δ″2, the magnetic conductive surface of the first probe 2 is A′1, the gap is δ″1, A′1=A′2, δ″1=δ″2;

[0120] At this time, the radial output voltage in the first and second probes is:

[0121] Finally, the radial output voltage U of the middle layer stator isj0 and the radial output voltage U′ in the upper and lower layer wedge-shaped probes z0 , after normalization, the final radial detection output voltage of the sensor is:

[0122] U′0 = k * U j0 +(1 - k) * U′ z0 , where k is a constant.

[0123] This is the preferred method for detecting the axial displacement of the rotating shaft in the present invention, which can accurately obtain the displacement of the radial movement of the rotating shaft. Figure 4 The figure shows the working schematic diagram of the sensor when the rotor is radially offset. When the rotating shaft is radially offset downward, the radial clearances between the wedge-shaped probes in the lower part of the circumference and the radial probes under the middle stator and the rotor both become smaller, while the radial clearances between the wedge-shaped probes (the first probe 2 and the second probe 3) in the upper part of the circumference and the radial probes (the third probe 8) above the middle stator and the rotor both become larger. Finally, the differential of the inductance change signals of the probe coils corresponding to the upper and lower parts of each stator circumference is performed, and then the radial movement displacement of the rotating shaft is obtained.

[0124] The wedge-shaped stator probes in the upper and lower parts of the sensor of the present invention can not only detect the axial displacement of the rotating shaft, but also detect the radial displacement deviation of the rotating shaft, reduce the calculation error of detecting the radial displacement, and improve the radial detection accuracy of the sensor. The inductive displacement sensor proposed by the present invention can realize the integration of the detection of the radial and axial displacements of the rotating shaft, save the installation space of the sensor, eliminate the interference between the sensor probes, improve the sensitivity and detection accuracy of the sensor in the radial and axial directions, and greatly improve the stability of the operation of the magnetic suspension bearing system.

[0125] The present invention also provides a magnetic suspension bearing, which includes the inductive displacement sensor of the aforementioned magnetic suspension bearing.

[0126] The magnetic suspension bearing of the present invention has the following effects:

[0127] 1. In the present invention, the stator of the inductive sensor of the magnetic suspension bearing is divided into two upper, middle and lower parts, which are respectively used to detect the axial and radial displacements of the rotor, realize the integration of the detection of the radial and axial displacements of the rotating shaft, save the installation space of the sensor, eliminate the interference between the sensor probes, and improve the detection accuracy of the sensor.

[0128] 2. In the present invention, the axial probe of the inductive sensor of the magnetic suspension bearing is designed as a wedge shape with a certain angle, which increases the magnetic conduction area between the probe and the rotor, improves the relative magnetic conduction area and clearance change between the probe and the rotor, increases the inductance change of the axial probe coil, and improves the sensitivity of the sensor.

[0129] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and variations can also be made, and these improvements and variations should also be regarded as within the protection scope of the present invention.

Claims

1. An inductive displacement sensor for a magnetic bearing, characterized in that: include: A rotating shaft (5), a first probe (2), a second probe (3) and a third probe (8), wherein the first probe (2), the second probe (3) and the third probe (8) are all located on the outer periphery of the rotating shaft (5), the rotating shaft (5) has an axial direction, the first probe (2) is located at a first axial position, the second probe (3) is located at a second axial position, the third probe (8) is located at a third axial position, and along the axial direction, the third axial position is located between the first axial position and the second axial position; The first probe (2) and the second probe (3) are capable of detecting the axial displacement and radial displacement of the rotating shaft (5), and the third probe (8) is capable of detecting the radial displacement of the rotating shaft (5), so as to compare and compensate for the radial displacement of the rotating shaft (5) detected by the first probe (2) and the second probe (3).

2. The inductive displacement sensor of the magnetic bearing according to claim 1 is characterized in that: The surface of the first probe (2) facing the rotating shaft (5) is a first surface (A); in a vertical cross-sectional plane passing through the axis of the rotating shaft (5), the first surface (A) is not parallel to the axis of the rotating shaft (5); the outer peripheral surface of the rotating shaft (5) has a second surface (B); the second surface (B) is also not parallel to the axis of the rotating shaft (5); and the first surface (A) and the second surface (B) are opposite and parallel to each other, so that the axial and / or radial displacement of the rotating shaft (5) can be detected by the change of the spacing between the first surface (A) and the second surface (B) during the axial and / or radial movement of the rotating shaft (5); The surface of the second probe (3) facing the rotating shaft (5) is a third surface (C); in a vertical cross-sectional plane passing through the axis of the rotating shaft (5), the third surface (C) is not parallel to the axis of the rotating shaft (5); the outer peripheral surface of the rotating shaft (5) has a fourth surface (D); the fourth surface (D) is also not parallel to the axis of the rotating shaft (5); and the third surface (C) and the fourth surface (D) are opposite and parallel to each other, so that the axial and / or radial displacement of the rotating shaft (5) can be detected by the change of the spacing between the third surface (C) and the fourth surface (D) during the axial and / or radial movement of the rotating shaft (5); The surface of the third probe (8) facing the rotating shaft (5) is the fifth surface (E). In a vertical cross-sectional plane passing through the axis of the rotating shaft (5), the fifth surface (E) is parallel to the axis of the rotating shaft (5). The outer peripheral surface of the rotating shaft (5) has a sixth surface (F), and the sixth surface (F) is also parallel to the axis of the rotating shaft (5). The fifth surface (E) and the sixth surface (F) are opposite and parallel to each other, so that the radial displacement of the rotating shaft (5) can be detected by the change in the spacing between the fifth surface (E) and the sixth surface (F) during the radial movement of the rotating shaft (5).

3. The inductive displacement sensor of the magnetic bearing according to claim 2 is characterized in that: The outer normal of the second surface (B) extends away from the axis of the rotating shaft (5) and also extends away from the fourth surface (D); the outer normal of the fourth surface (D) extends away from the axis of the rotating shaft (5) and also extends away from the second surface (B); and the outer normal of the second surface (B) does not intersect with the outer normal of the fourth surface (D).

4. The inductive displacement sensor of the magnetic bearing according to claim 2 is characterized in that: The second surface (B), the sixth surface (F) and the fourth surface (D) are connected in sequence along the axial direction of the rotating shaft (5), and a protrusion protruding toward the radial outer periphery relative to the outer peripheral surface of the rotating shaft (5) is formed on the second surface (B), the sixth surface (F) and the fourth surface (D).

5. The inductive displacement sensor of the magnetic bearing according to claim 4 is characterized in that: In a vertical cross-sectional plane passing through the axis of the rotating shaft (5), the second surface (B) and the fourth surface (D) are both inclined surfaces, one end of the second surface (B) is connected to the outer peripheral surface of the rotating shaft (5), and the other end gradually extends radially outward to connect with one end of the sixth surface (F), and one end of the fourth surface (D) is connected to the outer peripheral surface of the rotating shaft (5), and the other end gradually extends radially outward to connect with the other end of the sixth surface (F), so that the outer diameter of the radial outer periphery of the sixth surface (F) is the largest part on the rotating shaft (5).

6. The inductive displacement sensor of the magnetic bearing according to claim 1, characterized in that: In a vertical cross-sectional plane passing through the axis of the rotating shaft (5), the first probe (2) and the second probe (3) are both located on one side of the axis of the rotating shaft (5), and the third probe (8) is located on the other side of the axis of the rotating shaft (5).

7. The inductive displacement sensor of the magnetic bearing according to claim 1, characterized in that: The first probe (2) and the second probe (3) form a first probe unit. The two first probe units are adjacent and spaced apart along the circumferential direction of the rotating shaft (5), forming a first probe unit group. The two adjacent third probes (8) along the circumferential direction of the rotating shaft (5) form a second probe unit. Both the first probe unit group and the second probe unit are plural. The first probe unit group and the second probe unit are staggered and spaced apart along the circumferential direction.

8. The inductive displacement sensor for a magnetic bearing according to claim 7, characterized in that: In the first probe unit, a first probe coil (1) is wound around the first probe (2), a second probe coil (4) is wound around the second probe (3), and the first probe coil (1) and the second probe coil (4) are connected and conductive; in the second probe unit, a third probe coil (7) is wound around one of the adjacent third probes (8), a fourth probe coil (9) is wound around the other third probe (8), and the third probe coil (7) and the fourth probe coil (9) are connected and conductive.

9. The inductive displacement sensor of a magnetic bearing according to any one of claims 1 to 8, characterized in that: The invention comprises a first layer of stator silicon steel sheets (10), a second layer of stator silicon steel sheets (11) and a third layer of stator silicon steel sheets (12); the first layer of stator silicon steel sheets (10), the second layer of stator silicon steel sheets (11) and the third layer of stator silicon steel sheets (12) are all annular structures; the third layer of stator silicon steel sheets (12) is sandwiched between the first layer of stator silicon steel sheets (10) and the second layer of stator silicon steel sheets (11) along the axial direction of the rotating shaft (5); the first probe (2) is provided on the inner circumferential wall of the first layer of stator silicon steel sheets (10) so as to protrude radially inwards; the second probe (3) is provided on the inner circumferential wall of the second layer of stator silicon steel sheets (11) so as to protrude radially inwards; and the third probe (8) is provided on the inner circumferential wall of the third layer of stator silicon steel sheets (12) so as to protrude radially inwards.

10. The inductive displacement sensor of a magnetic bearing according to any one of claims 1 to 9, characterized in that: The rotating shaft (5) comprises an axis section with an entire magnetic conductive structure, namely, a rotating shaft magnet (6), wherein the rotating shaft magnet (6) extends from the axis section opposite to the first probe (2) through the axis section opposite to the third probe (8), and the axis section opposite to the second probe (3), so that the first probe (2), the second probe (3) and the third probe (8) are all opposite to the rotating shaft magnet (6).

11. The inductive displacement sensor for a magnetic bearing according to claim 1, characterized in that: When the rotating shaft (5) is not deflected, the initial inductance of the first probe (2) is L 01 , the initial inductance of the second probe (3) is L 02 , the input voltage is U s ,but: Where δ0 represents the initial air gap, W1 represents the number of turns of the probe coil, A0 represents the initial magnetic pole area of ​​the probe, μ0 represents the magnetic permeability, and δ1 and δ2 represent the air gaps formed by the initial air gap δ0 after the rotor displacement changes; When the rotating shaft (5) undergoes an axial displacement Δδ in the direction of the second probe (3), the magnetic conductive surface A2 of the second probe (3) becomes larger, the air gap δ2 between the second probe and the rotating shaft decreases, δ2=(δ0-Δδ), and the inductance L2 of the second probe increases; the magnetic conductive surface A1 of the first probe (2) becomes smaller, the air gap δ1 between the first probe and the rotating shaft increases, δ1=δ0+Δδ, and the inductance L1 of the first probe decreases. At this time: Therefore, the axial output voltage is:

12. The inductive displacement sensor of the magnetic bearing according to claim 1, characterized in that: When the rotating shaft (5) does not deviate radially and is at the center of rotation, the initial gaps between the plurality of third probes (8) and the rotating shaft (5) are all δ′0, the number of turns of the coils are all W2, the magnetic conductive area is A′0, and the initial inductances of the two third probes located at the top are L 08 and L 11 The initial inductances of the two third probes located below are L 10 and L 12 , the input voltage is U s ,but: When the shaft (5) moves radially downward, Δδ ′ When , the air gap δ′1 between the two third probes located at the bottom and the rotating shaft decreases, the inductances L5 and L6 increase, the air gap δ′2 between the two third probes located at the top and the rotating shaft increases, and the inductances L3 and L4 decrease. At this time: Therefore, the radial output voltage of the plurality of third probes (8) in the middle layer is: And assuming that the magnetic conductive surface of the second probe (3) is A′2, the gap is δ″2, the magnetic conductive surface of the first probe (2) is A′1, the gap is δ″1, A′1=A′2, δ″1=δ″2; At this time, the radial output voltage in the first and second probes is: Finally, the radial output voltage U of the middle layer stator is j0 The radial output voltage U′ in the upper and lower wedge probes z0 , after normalization, the final radial detection output voltage of the sensor is: U′0=k*U j0 +(1-k)*U′ z0 , where k is a constant.

13. A magnetic bearing, characterized in that: An inductive displacement sensor comprising a magnetic bearing as claimed in any one of claims 1 to 12.

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