Inductive displacement sensor, magnetic suspension bearing system and compressor

Abstract

The utility model particularly relates to an inductance type displacement sensor, a magnetic suspension bearing system and a compressor, the inductance type displacement sensor comprises a stator and at least two sensor coil assemblies, the stator is of an annular structure, and the at least two sensor coil assemblies are arranged on the inner circle of the stator and are arranged along the inner circumference of the stator at intervals. The sensor coil assembly comprises a first magnetic pole and at least one second magnetic pole set, each second magnetic pole set comprises two second magnetic poles, the two second magnetic poles in each second magnetic pole set are symmetrically arranged on the two opposite sides of the first magnetic pole in the inner circumferential direction of the stator, and the magnetism of the second magnetic poles is opposite to that of the first magnetic pole. According to the inductance type displacement sensor, the number of the magnetic poles is arranged to be an odd number such as three or five, so that the magnetic field of the stator yoke part can be effectively improved, the magnetic field distribution is more uniform, and the problems of over-high magnetic density and large magnetic resistance of the existing inductance type displacement sensor can be solved.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, specifically to an inductive displacement sensor, a magnetic levitation bearing system, and a compressor. Background Technology

[0002] Inductive displacement sensors are based on electromagnetic principles, determining the magnitude of displacement by measuring changes in inductance. They have wide applications in both rotary and translational mechanisms. In the field of magnetic levitation bearings, inductive displacement sensors are used in numerous scenarios due to their strong anti-interference capabilities, simple identification and control, and low hardware requirements.

[0003] Currently, inductive displacement sensors used in the field of magnetic levitation bearings employ multiple sets of magnetic poles arranged on the stator, with each set consisting of two or four poles, or multiple poles spaced equally on the stator. However, this type of inductive displacement sensor, due to the theoretical closed magnetic circuit formed by every two magnetic poles, tends to result in excessively high magnetic flux density at the yoke of the stator core, increasing magnetic reluctance. Furthermore, to achieve the same positional accuracy, the two-pole configuration requires more winding turns or necessitates the addition of more core elements. Utility Model Content

[0004] The purpose of this invention is to at least solve the problems of excessively high magnetic flux density and high magnetic reluctance in existing inductive displacement sensors. This objective is achieved through the following technical solution:

[0005] The first aspect of this utility model provides an inductive displacement sensor, including a stator and at least two sensor coil assemblies. The stator has a ring structure, and the at least two sensor coil assemblies are disposed on the inner circle of the stator and are spaced apart along the circumferential direction of the inner circle of the stator.

[0006] The sensor coil assembly includes a first magnetic pole and at least one second magnetic pole group. Each second magnetic pole group includes two second magnetic poles and is arranged along the inner circumference of the stator. The two second magnetic poles in each second magnetic pole group are symmetrically arranged on opposite sides of the first magnetic pole, and the magnetism of the second magnetic pole is opposite to that of the first magnetic pole.

[0007] The inductive displacement sensor of this invention includes a stator and at least two sensor coil assemblies. Each sensor coil assembly includes a first magnetic pole and at least one group of second magnetic poles, and each group of second magnetic poles includes two second magnetic poles symmetrically arranged on opposite sides of the first magnetic pole. In other words, each sensor coil assembly includes at least three magnetic poles, and the number of magnetic poles is odd. This effectively improves the magnetic field of the stator yoke, making the magnetic field distribution more uniform, which helps to improve the measurement accuracy of the inductive displacement sensor and solves the problems of excessively high magnetic flux density and high magnetic reluctance in existing inductive displacement sensors.

[0008] In addition, the inductive displacement sensor according to this utility model may also have the following additional technical features:

[0009] In some embodiments of this utility model, the first magnetic pole has a first coil, the second magnetic pole has a second coil, and in the same sensor coil assembly, the number of turns of the first coil is the sum of the number of turns of all the second coils.

[0010] In some embodiments of this utility model, the first magnetic pole includes a first stator tooth, and the first coil is wound around the first stator tooth; the second magnetic pole includes a second stator tooth, and the second coil is wound around the second stator tooth;

[0011] In the same sensor coil assembly, the cross-sectional area of ​​the first stator tooth is the sum of the cross-sectional areas of all the second stator teeth.

[0012] In some embodiments of this utility model, the first stator tooth and the stator are integrally formed, and the second stator tooth and the stator are integrally formed.

[0013] In some embodiments of this utility model, along the inner circumference of the stator, there is a first distance between the second magnetic pole and the first magnetic pole;

[0014] Along the inner circumference, there is a gap between two adjacent sensor coil assemblies, and the size of the gap along the inner circumference is a second spacing, and the first spacing is smaller than the second spacing.

[0015] The second aspect of this utility model provides a magnetic levitation bearing system, including an inductive displacement sensor as described in this utility model, and a rotor assembly, the rotor assembly being rotatably disposed inside the stator;

[0016] The rotor assembly includes a rotor core and a rotor protective sleeve fitted over the outside of the rotor core, and the rotor core is coaxially arranged with the stator.

[0017] The magnetic levitation bearing system described in this utility model includes the aforementioned inductive displacement sensor and rotor assembly, with the rotor assembly and stator arranged concentrically to form a more uniform magnetic field between the rotor assembly and the stator, which helps to improve the measurement accuracy of the inductive displacement sensor.

[0018] In some embodiments of this utility model, the rotor core and the rotor protective sleeve are interference fit.

[0019] In some embodiments of this utility model, along the axial direction of the rotor core, the axial length of the rotor core is less than the axial length of the rotor protective sleeve;

[0020] And / or, the rotor protective sleeve includes a body and an adhesive component, wherein the body is a fibrous or metal component and the adhesive component is an organic material.

[0021] In some embodiments of this utility model, the rotor core is a solid steel component or an assembly made of multiple silicon steel sheets stacked together.

[0022] A third aspect of this invention provides a compressor, the compressor including a magnetic levitation bearing system as described in this invention, the magnetic levitation bearing system including an inductive displacement sensor.

[0023] The compressor of this utility model embodiment has the same technical effect as the magnetic levitation bearing system of this utility model embodiment, and will not be described again here. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0025] Figure 1 This is a cross-sectional view of the inductive displacement sensor shown in the embodiment of this utility model in its operating state.

[0026] Figure 2 for Figure 1 A partially enlarged schematic diagram of the structure shown.

[0027] The markings in the attached diagram are as follows:

[0028] 10. Stator;

[0029] 20. Sensor coil assembly;

[0030] 21. First magnetic pole; 211. First stator tooth; 212. First coil;

[0031] 22. Second magnetic pole; 221. Second stator tooth; 222. Second coil;

[0032] 30. Rotor assembly; 31. Rotor core; 32. Rotor protective sleeve. Detailed Implementation

[0033] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0034] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0035] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0036] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations.

[0037] Inductive displacement sensors convert changes in inductance caused by the displacement of an object into a voltage signal, thereby detecting the displacement of the object. In high-speed magnetic levitation motors, they can monitor the position of the levitated rotor in space, confirming whether it is levitated at the center. Based on electromagnetic principles, inductive displacement sensors determine the magnitude of displacement by measuring changes in inductance. They have wide applications in both rotary and translational mechanisms. In the field of magnetic levitation bearings, inductive displacement sensors are used in many scenarios due to their strong anti-interference capabilities, simple identification and control, and low hardware requirements.

[0038] However, existing inductive displacement sensors in the field of magnetic levitation bearings mostly use an even number of magnetic poles, such as 2 or 4 poles. Since each pair of magnetic poles forms a theoretically closed magnetic circuit, the magnetic flux density at the yoke of the iron core is prone to be too high, increasing magnetic reluctance. At the same time, to achieve the same positional accuracy, the two-pole method requires more winding turns or more iron cores.

[0039] Based on the above-mentioned technical problems, this utility model proposes an inductive displacement sensor to solve the problems of excessively high magnetic flux density and large magnetic reluctance in existing inductive displacement sensors.

[0040] like Figure 1 and Figure 2 As shown, in terms of overall design, the inductive displacement sensor includes a stator 10 and at least two sensor coil assemblies 20. The stator 10 has a ring structure, and the at least two sensor coil assemblies 20 are arranged on the inner circle of the stator 10 and are spaced apart along the circumferential direction of the inner circle of the stator 10.

[0041] The sensor coil assembly 20 includes a first magnetic pole 21 and at least one second magnetic pole group. Each second magnetic pole group includes two second magnetic poles 22. Along the inner circumference of the stator 10, the two second magnetic poles 22 in each second magnetic pole group are symmetrically arranged on opposite sides of the first magnetic pole 21, and the magnetism of the second magnetic poles 22 is opposite to that of the first magnetic pole 21.

[0042] Specifically, by configuring each sensor coil assembly 20 with a first magnetic pole 21 and at least one second magnetic pole group, and each second magnetic pole group including two second magnetic poles 22, and symmetrically arranging the two second magnetic poles 22 on opposite sides of the first magnetic pole 21, that is, by configuring each sensor coil assembly 20 with at least three magnetic poles, and the number of magnetic poles being odd, the magnetic field of the stator 10 yoke can be effectively improved, making the magnetic field distribution more uniform. This helps to improve the measurement accuracy of the inductive displacement sensor and solves the problems of excessive magnetic flux density and large magnetic reluctance in existing inductive displacement sensors.

[0043] Furthermore, compared to existing inductive displacement sensors, this inductive displacement sensor can effectively reduce the number of coil turns on the magnetic poles and the thickness of the stator 10 while maintaining the same measurement accuracy. The thickness of the stator 10 refers to the difference between the outer radius and the inner radius of the stator.

[0044] It should be understood that the inductive displacement sensor includes a stator 10 and a sensor coil assembly 20. This inductive displacement sensor is used in a magnetic levitation bearing system. The stator 10 has a ring structure, with an inner circle and an outer circle. The sensor coil assembly 20 is disposed on the inner circle of the stator 10. Optionally, the number of sensor coil assemblies 20 is set to at least two. In this embodiment, the number of sensor coil assemblies 20 is four, and the four sensor coil assemblies 20 are arranged circumferentially spaced along the inner circle of the stator 10.

[0045] Still Figure 1 As shown, the sensor coil assembly 20 includes a first magnetic pole 21 and at least one second magnetic pole group, each second magnetic pole group including two second magnetic poles 22. In this embodiment, the first magnetic pole 21 and the second magnetic pole 22 have the same structure. Furthermore, along the inner circumference of the stator 10, the two second magnetic poles 22 in each second magnetic pole group are symmetrically arranged on opposite sides of the first magnetic pole 21, that is, when the magnetism of the second magnetic pole 22 is positive, the magnetism of the first magnetic pole 21 is negative.

[0046] It should be noted that the number of second magnetic pole groups is at least one. That is, all the second magnetic poles 22 of each sensor coil assembly 20 are set to an even number, such as two or four, and all the second magnetic poles 22 are arranged symmetrically with the first magnetic pole 21 as the center.

[0047] Still Figure 1As shown, in this embodiment, there are four sensor coil assemblies 20, and the four sensor coil assemblies 20 are equally spaced along the inner circumference of the stator 10. Each sensor coil assembly 20 includes a first magnetic pole 21 and a second magnetic pole group, meaning each group of sensor coil assemblies 20 includes three magnetic poles. Each sensor coil assembly 20 includes three magnetic poles, and the second magnetic poles 22 on both sides of the first magnetic pole 21 have opposite magnetic poles to the first magnetic pole 21. This improves the magnetic field of the yoke of the stator 10, making the magnetic field distribution more uniform and helping to improve the measurement accuracy of the inductive displacement sensor. Furthermore, setting the number of magnetic poles to three helps to reduce the manufacturing difficulty of the inductive displacement sensor.

[0048] It is important to further understand that the first magnetic pole 21 and the second magnetic pole 22 have the same structure. The first magnetic pole 21 includes a first stator tooth 211 and a first coil 212, and correspondingly, the second magnetic pole 22 includes a second stator tooth 221 and a second coil 222. The first coil 212 is wound around the first stator tooth 211, and the second coil 222 is wound around the second stator tooth 221. The following description uses the first magnetic pole 21 as an example. In this embodiment, the first stator tooth 211 has a columnar structure, with its first end connected to the stator 10 and its second end extending towards the center of the stator 10.

[0049] Still Figure 1 As shown, along the extending direction of the first stator tooth 211, the length of the first coil 212 is less than the length of the first stator tooth 211, and one end of the first coil 212 is spaced apart from the inner circle of the stator 10, while the other end of the first coil 212 is spaced apart from the end face of the second end of the first stator tooth 211. Optionally, in the same sensor coil assembly 20, the first coil 212 and the second coil 222 are connected in series along the circumferential direction of the inner circle of the stator 10.

[0050] In this embodiment, the first stator tooth 211 and the stator 10 are integrally formed, and the second stator tooth 221 and the stator 10 are integrally formed. This arrangement helps to reduce the manufacturing difficulty of the inductive displacement sensor and improve the manufacturing efficiency.

[0051] In other embodiments of this application, the first stator tooth 211 is detachably connected to the stator 10, and the second stator tooth 221 is also detachably connected to the stator 10. Specifically, a T-shaped mounting groove is provided on the inner circle of the stator 10, and a connecting part is provided at the end of the first stator tooth 211 or the second stator tooth 221 facing the stator 10. The connecting part and the mounting groove are engaged. With this configuration, the coil can be inserted into the stator tooth from the outside along the extension direction of the stator tooth, thereby effectively avoiding the problem of mutual restriction between the detection surface area of ​​the stator tooth and the coil.

[0052] Furthermore, in the same sensor coil assembly 20, the number of turns of the first coil 212 is the sum of the number of turns of all the second coils 222. In this embodiment, the sensor coil assembly 20 includes a first magnetic pole 21 and two second magnetic poles 22, and the two second magnetic poles 22 are symmetrically arranged on opposite sides of the first magnetic pole 21. In this case, the number of turns of the first coil 212 is the sum of the number of turns of the second coils 222 on the two adjacent second magnetic poles 22, and the two second coils 222 have the same number of turns. By limiting the number of turns on the first coil 212 and the second coil 222, it is helpful to form a more stable magnetic field, which helps to improve the calculation accuracy of the displacement of the rotor assembly.

[0053] It should be noted that when the sensor coil assembly 20 includes a first magnetic pole 21 and two second magnetic pole groups, that is, when a sensor coil assembly 20 includes a first magnetic pole 21 and four second magnetic poles 22, the number of turns of the first coil 212 is the sum of the number of turns of the four second coils 222. This setting helps to ensure the stability of the magnetic field and the accuracy of the calculation of the rotor displacement.

[0054] It is important to further understand that, within the same sensor coil assembly 20, the cross-sectional area of ​​the first stator tooth 211 is the sum of the cross-sectional areas of all the second stator teeth 221. In this embodiment, along the axial direction of the stator 10, the lengths of the first magnetic pole 21 and the second magnetic pole 22 of the sensor coil assembly 20 are the same. Simultaneously, along the inner circumferential direction of the stator 10, the width of the first stator tooth 211 is the sum of the widths of its two adjacent second stator teeth 221, so that the cross-sectional area of ​​the first stator tooth 211 is the sum of the cross-sectional areas of all the second stator teeth 221. By making the cross-sectional area of ​​the first stator tooth 211 the sum of the cross-sectional areas of all the second stator teeth 221, on the one hand, it helps to reduce the space occupied by the second magnetic pole 22, thereby reducing the space ratio of the sensor coil assembly 20; on the other hand, it also helps to further ensure the stability of the magnetic field and improve the measurement accuracy of the inductive displacement sensor.

[0055] It should be noted that, in this embodiment, the cross-section of the first stator tooth 211 is not the same as the cross-section of its two adjacent second stator teeth 221, but the cross-section of each stator tooth is perpendicular to its extension direction.

[0056] Furthermore, along the inner circumference of the stator 10, there is a first distance L1 between the second magnetic pole 22 and the first magnetic pole 21. Simultaneously, there is a space between adjacent sensor coil assemblies 20, the dimension of which along the inner circumference is a second distance L2. The first distance L1 is smaller than the second distance L2; that is, the second distance L2 is the distance between two circumferentially adjacent second magnetic poles 22 located in different sensor coil assemblies 20. In this embodiment, each sensor coil assembly 20 includes two second magnetic poles 22, each second magnetic pole 22 has a first distance L1 between it and its adjacent first magnetic pole 21, and adjacent sensor coil assemblies 20 have a space between them, the dimension of which along the inner circumference is a second distance L2, where L1 < L2. By setting the first distance and the second distance, and making the first distance L1 smaller than the second distance L2, the magnetic circuit of each sensor coil assembly 20 is closed, and the magnetic circuit interference between adjacent sensor coil assemblies 20 is reduced, which helps to further ensure the stability of the magnetic field.

[0057] This embodiment also relates to a magnetic levitation bearing system, which includes the aforementioned inductive displacement sensor and a rotor assembly 30, the rotor assembly 30 being rotatably disposed inside the stator 10. Still as Figure 1 As shown, in this embodiment, the rotor assembly 30 is rotatably disposed inside the stator 10. Specifically, the rotor assembly 30 includes a rotor core 31 and a rotor protective sleeve 32, wherein the rotor protective sleeve 32 is sleeved on the outside of the rotor core 31. At this time, the rotor core 31, the rotor protective sleeve 32 and the stator 10 are coaxially arranged to ensure that the inductive displacement sensor can effectively detect the offset of the rotor core 31, thereby realizing displacement detection. Optionally, the rotor core 31 is a solid steel part, or an assembly made of multiple silicon steel sheets stacked together, or an assembly made of other materials.

[0058] It should be noted that this magnetic levitation bearing system is used in a compressor. In this embodiment, the compressor is a centrifugal air compressor, which can be a single-stage centrifugal air compressor, a multi-stage centrifugal air compressor, or a magnetically levitation centrifugal air compressor; this application does not impose any limitations on this. The compressor also includes structures such as a bladeless diffuser and a gas collector. The compressor 1 can also be a centrifuge used in a refrigeration system, i.e., a centrifugal compressor.

[0059] Furthermore, the rotor core 31 and the rotor protective sleeve 32 are interference-fitted. In this embodiment, the rotor protective sleeve 32 is a prefabricated part, and then the rotor protective sleeve 32 is assembled with the rotor core 31 by press fitting or cold fitting, thereby achieving an interference fit between the rotor core 31 and the rotor protective sleeve 32. This arrangement helps to improve the assembly efficiency of the rotor assembly 30, and thus improves the assembly efficiency of the inductive displacement sensor.

[0060] It should be understood that when the rotor protective sleeve 32 is a prefabricated component, the prefabricated component includes a main body and an adhesive component. In this embodiment, the main body is a fiber component or a metal component, and the adhesive component is an organic material, that is, the organic material is added to the main body during the prefabrication process. Optionally, the organic material is resin. This configuration can effectively enhance the structural integrity of the rotor protective sleeve 32 and improve its structural strength. Since the manufacturing method of the prefabricated component is relatively mature, it will not be described in detail here.

[0061] In some other embodiments of this application, the rotor protective sleeve 32 is made of fiber winding, and in this case, the rotor core 31 and the rotor protective sleeve 32 are also interference-fitted. In this embodiment, the rotor protective sleeve 32 includes a main body, and the main body is a fibrous material, such as carbon fiber or glass fiber. The rotor protective sleeve 32 described above can be formed by winding the main body around the outside of the rotor core 31. This arrangement helps to improve the connection effect between the rotor protective sleeve 32 and the rotor core 31, and also allows the diameter and number of winding turns of the main body to be selected according to the distance between the stator 10 and the rotor, i.e., the annular area of ​​the rotor protective sleeve 32, making the fabrication of the rotor assembly more targeted.

[0062] It should be noted that when the rotor protective sleeve 32 is prepared by winding the main body, in order to ensure the structural integrity of the rotor protective sleeve 32, an adhesive needs to be added during the winding process. Optionally, the adhesive is an organic material such as resin.

[0063] Furthermore, along the axial direction of the rotor core 31, the axial length of the rotor core 31 is less than the axial length of the rotor protective sleeve 32. For example... Figure 2 As shown, in this embodiment, the axial length of the rotor core 31 is less than the axial length of the rotor protective sleeve 32, and the axial center of the rotor protective sleeve 32 is aligned with the axial center of the rotor core. Furthermore, along the axial direction of the rotor core 31, the axial end face of the rotor protective sleeve 32 extends beyond the rotor core 31, so as to better protect the rotor core 31 and improve the safety of the inductive displacement sensor.

[0064] The third aspect of this embodiment also relates to a compressor that includes the above-described magnetic levitation bearing system, and the magnetic levitation bearing system includes an inductive displacement sensor.

[0065] The compressor in this embodiment has the same technical effect as the magnetic levitation bearing system in this embodiment, and will not be described again here.

[0066] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. An inductive displacement sensor, characterized by It includes a stator and at least two sensor coil assemblies. The stator has a ring structure, and the at least two sensor coil assemblies are disposed on the inner circle of the stator and are spaced apart along the circumferential direction of the inner circle of the stator. The sensor coil assembly includes a first magnetic pole and at least one second magnetic pole group. Each second magnetic pole group includes two second magnetic poles and is arranged along the inner circumference of the stator. The two second magnetic poles in each second magnetic pole group are symmetrically arranged on opposite sides of the first magnetic pole, and the magnetism of the second magnetic pole is opposite to that of the first magnetic pole.

2. Inductive displacement sensor according to claim 1, characterized in that The first magnetic pole has a first coil, and the second magnetic pole has a second coil. In the same sensor coil assembly, the number of turns of the first coil is the sum of the number of turns of all the second coils.

3. An inductive displacement sensor according to claim 2, characterised in that, The first magnetic pole includes a first stator tooth, and the first coil is wound around the first stator tooth; the second magnetic pole includes a second stator tooth, and the second coil is wound around the second stator tooth; In the same sensor coil assembly, the cross-sectional area of ​​the first stator tooth is the sum of the cross-sectional areas of all the second stator teeth.

4. An inductive displacement sensor according to claim 3, characterised in that, The first stator tooth and the stator are integrally formed, and the second stator tooth and the stator are integrally formed.

5. The inductive displacement sensor according to any one of claims 1 to 4, characterized in that, Along the inner circumference of the stator, there is a first distance between the second magnetic pole and the first magnetic pole; Along the inner circumference, there is a gap between two adjacent sensor coil assemblies, and the size of the gap along the inner circumference is a second spacing, and the first spacing is smaller than the second spacing.

6. A magnetic bearing system characterized by, The system includes an inductive displacement sensor as described in any one of claims 1-5, and a rotor assembly rotatably disposed inside the stator. The rotor assembly includes a rotor core and a rotor protective sleeve fitted over the outside of the rotor core, and the rotor core is coaxially arranged with the stator.

7. The magnetic bearing system of claim 6, wherein, The rotor core and the rotor protective sleeve are interference fit.

8. The magnetic bearing system of claim 6, wherein, Along the axial direction of the rotor core, the axial length of the rotor core is less than the axial length of the rotor protective sleeve; And / or, the rotor protective sleeve includes a body and an adhesive component, wherein the body is a fibrous or metal component and the adhesive component is an organic material.

9. The magnetic bearing system of claim 6, wherein, The rotor core is a solid steel component or an assembly made of multiple silicon steel sheets stacked together.

10. A compressor characterized by, The compressor includes a magnetic levitation bearing system as described in any one of claims 6-9, wherein the magnetic levitation bearing system includes an inductive displacement sensor.

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