Modularized five-degree-of-freedom magnetic suspension compressor rotor system

Abstract

The utility model discloses a modularized five-degree-of-freedom magnetic suspension compressor rotor system, which belongs to the field of compressor rotors and comprises a magnetic suspension rotor spindle and a driving motor arranged in the middle of the magnetic suspension rotor spindle. The magnetic suspension rotor main shaft between the driving motor and the centrifugal impeller and the magnetic suspension rotor main shaft between the driving motor and the cooling impeller are respectively and sequentially provided with an axial magnetic bearing assembly and a radial magnetic bearing assembly; the axial magnetic bearing assembly is of a non-thrust disc structure in which a magnetic field is directly coupled; the radial magnetic bearing assembly is of a modular structure with partitioned magnetic poles. According to the modularized five-degree-of-freedom magnetic suspension compressor rotor system, the axial magnetic bearing assembly directly coupled with the magnetic field is adopted, a thrust disc is omitted, the assembly process of the axial magnetic bearing is simplified, meanwhile, the partitioned magnetic poles are adopted, redundancy control is achieved, and stability is higher.

Description

Technical Field

[0001] This utility model relates to the field of compressor rotor technology, and in particular to a modular five-degree-of-freedom magnetic levitation compressor rotor system. Background Technology

[0002] Compressors are widely used in air conditioning, refrigeration equipment, and hydrogen production equipment; they are also extensively used in industries such as textiles, metallurgy, chemicals, fermentation, glass, pharmaceuticals, and papermaking. Magnetic levitation compressors utilize magnetic levitation technology, employing magnetic bearings to levitate the compressor rotor within a magnetic field, thus achieving contactless operation. This design reduces energy loss and noise caused by mechanical bearing friction in traditional compressors, improving system efficiency and reliability.

[0003] Existing magnetic levitation compressors typically employ one axial thrust magnetic bearing and two radial magnetic bearings to achieve stable rotor levitation. The axial thrust magnetic bearing consists of two stators and a thrust disk. This structure requires assembly: first, one stator is installed; then, the thrust disk is mounted on the shaft using a thermal assembly process; finally, the other stator is installed. This assembly is therefore quite difficult, and disassembly is inconvenient in case of malfunction. Furthermore, the presence of the thrust disk limits the rotor's maximum speed and results in significant losses during operation.

[0004] Although radial magnetic bearings have proven to be sufficiently reliable, bearing system failures have occurred repeatedly, leading to rotor drops. To improve the reliability of radial magnetic bearings, two redundancy designs are typically employed: one is an independent redundancy structure design, which involves designing an independent spare bearing that will activate and continue providing support if the original bearing fails. This design increases structural complexity, leading to higher assembly, maintenance, and manufacturing costs. The other is an analytical redundancy structure, which reconstructs the support by selecting and configuring useful parts of the remaining structure based on different magnetic pole failure characteristics. This design requires each magnetic pole to be independent, and each magnetic pole needs to be equipped with a power amplifier, increasing the power consumption and manufacturing cost of the magnetic bearing system. Utility Model Content

[0005] The purpose of this invention is to provide a modular five-degree-of-freedom magnetic levitation compressor rotor system to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, this utility model provides a modular five-degree-of-freedom magnetic levitation compressor rotor system, including a magnetic levitation rotor main shaft and a drive motor disposed in the middle of the magnetic levitation rotor main shaft. Centrifugal impellers and cooling impellers are respectively installed at both ends of the magnetic levitation rotor main shaft. An axial magnetic bearing assembly and a radial magnetic bearing assembly are sequentially arranged on the magnetic levitation rotor main shaft between the drive motor and the centrifugal impellers and on the magnetic levitation rotor main shaft between the drive motor and the cooling impellers. The axial magnetic bearing assembly is a thrustless disk structure with direct magnetic field coupling; the radial magnetic bearing assembly is a modular structure with segmented magnetic poles.

[0007] Preferably, the axial magnetic bearing assembly includes an axial rotor assembly sleeved on the outside of the magnetic levitation rotor main shaft and an axial stator assembly sleeved on the outside of the axial rotor assembly, with an air gap between the axial rotor assembly and the axial stator assembly.

[0008] The axial stator assembly includes an axial stator core and an axial coil winding, which is wound around the two axial stator poles on the axial stator core.

[0009] The axial rotor assembly includes an axial rotor core and axial rotor magnetic poles integrally formed with the surface of the axial rotor core.

[0010] The axial stator magnetic poles and the axial rotor magnetic poles overlap in the axial portion, and the overlap width is 1 / 5 of the width of the axial rotor magnetic pole or the axial stator magnetic pole. The overlap directions of the two axial magnetic bearing assemblies located on both sides of the drive motor are opposite.

[0011] Preferably, the radial magnetic bearing assembly includes cages at both ends and a modular radial magnetic pole assembly, radial coil winding, and radial rotor core laminations arranged from the outside to the inside within the mounting cavity formed by the cages at both ends. The modular radial magnetic pole assembly includes multiple E-shaped magnetic poles evenly arranged in a circumferential array on the inner wall of one of the cages. Each E-shaped magnetic pole has a central pole post at the middle position of its inner arc side, and side pole posts are arranged symmetrically on both sides of the central pole post. The width of the central pole post is twice the width of the side pole posts, and radial coil windings are wound on both the central pole post and the side pole posts.

[0012] When the radial coil winding is energized, it forms SNS magnetic poles to form an electromagnetic circuit from the intermediate pole post, radial rotor core laminations, side pole posts to the return intermediate pole post.

[0013] Preferably, two magnetic pole grooves are formed on the outer arc side of one of the E-shaped magnetic poles. The two magnetic pole grooves are located between the two side pole posts and the middle pole post, respectively. A permanent magnet is provided in the magnetic pole groove, with the N pole of the permanent magnet facing the middle pole post, so as to form a permanent magnet circuit consisting of the N pole of the permanent magnet, the middle pole post, the radial rotor core laminations, the side pole posts, and the S pole of the permanent magnet.

[0014] Preferably, the radial coil windings on the side pole posts on both sides of the same E-shaped magnetic pole are connected in series and then connected together with the radial coil winding wound on the middle pole post to the two-in-four-out terminal. The two-in-four-out terminal is connected to the power amplifier so that the three radial coil windings on the same E-shaped magnetic pole can share one power amplifier.

[0015] Preferably, a fault detection coil is wound on both the side pole and the middle pole, and the fault detection coil is electrically connected to the operational amplifier;

[0016] To achieve the following: When current passes through the radial coil winding under normal conditions, a magnetic field is generated under the action of electromagnetic induction. When the radial coil winding changes, the generated magnetic flux changes. According to Faraday's law of electromagnetic induction and Oersted's law, the magnetic flux passing through the fault detection coil changes accordingly and induces an electromotive force, thereby forming a voltage difference across the radial coil winding. The voltage difference signal is processed by the operational amplifier and output to the operational amplifier. The voltage difference signal amplified by the operational amplifier is used to determine that the radial coil winding is normal.

[0017] When a fault occurs in the radial coil winding, changes in the current flowing through the radial coil winding will not cause a change in the voltage difference signal amplified by the operational amplifier, thus indicating that the radial coil winding has failed.

[0018] Preferably, an inductive radial displacement sensor is also provided on the magnetic levitation rotor main shaft between the radial magnetic bearing assembly and the centrifugal impeller or cooling impeller. The radial displacement sensor is electrically connected to the radial coil winding of the radial magnetic bearing assembly via a controller, so as to realize the radial displacement signal of the magnetic levitation rotor main shaft detected by the inductive radial displacement sensor, control the current to be passed through the radial coil winding, and ensure the balance and stability of the magnetic levitation rotor main shaft.

[0019] A protective bearing is provided between the inductive radial displacement sensor and the centrifugal impeller or cooling impeller;

[0020] Both the centrifugal impeller and the cooling impeller have flow divider blades, and the diameter and height of the centrifugal impeller are larger than those of the cooling impeller, respectively.

[0021] Preferably, the inductive radial displacement sensor includes a sensor measuring ring sleeved on the main shaft of the magnetic levitation rotor and a sensor stator core sleeved outside the sensor measuring ring. An air gap is left between the sensor stator core and the sensor measuring ring, and an even number of sensor magnetic poles are evenly arranged inside the sensor stator core. Each sensor magnetic pole is wound with a sensor coil winding. Opposite sensor coil windings are connected in series and wound in opposite directions. One of two adjacent sensor coil windings is energized and the other is de-energized.

[0022] Preferably, the axial stator core, axial rotor core, radial rotor core laminations, E-shaped magnetic poles, and sensor stator core are all made of silicon steel; the permanent magnets are made of rare earth permanent magnet materials; and the sensor measuring ring is made of permalloy.

[0023] Therefore, the present invention employs the above-mentioned modular five-degree-of-freedom magnetic levitation compressor rotor system, which has the following beneficial effects:

[0024] 1. The use of a thrust-disk-less axial magnetic bearing assembly simplifies the assembly process of the axial magnetic bearing, reduces losses during equipment operation, and is beneficial to improving the rotor's limiting speed. At the same time, this axial magnetic bearing assembly also increases the radial stiffness of the rotor system, improving system stability. In other words, it improves the reliability of the radial magnetic bearing and reduces the energy consumption and manufacturing cost of the radial magnetic bearing assembly.

[0025] 2. The radial magnetic bearing assembly adopts a modular design, which allows for quick disassembly when the magnetic bearing system fails, facilitating rapid and accurate problem location and repair.

[0026] 3. In the radial magnetic levitation bearing assembly, one magnetic pole is introduced into the permanent magnet, which reduces the current requirement in the electromagnetic coil. Only four power amplifiers are needed to achieve analytical redundancy design, which facilitates quick and accurate problem location and repair.

[0027] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a side view of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0029] Figure 2 This is a cross-sectional view of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0030] Figure 3 This is a schematic diagram of the axial magnetic bearing assembly of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0031] Figure 4 This is a Maxwell simulation magnetic field line distribution diagram of the axial magnetic bearing assembly of the modular five-degree-of-freedom magnetic levitation compressor rotor system described in this utility model.

[0032] Figure 5 This is an exploded view of the radial magnetic bearing assembly of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0033] Figure 6This is a magnetic circuit diagram of the radial magnetic bearing assembly of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0034] Figure 7 This is a Maxwell simulation magnetic field line distribution diagram of the radial magnetic bearing assembly of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0035] Figure 8 This is a schematic diagram of the radial coil winding connection of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention;

[0036] Figure 9 This is a schematic diagram of the circuit connection between the fault detection coil and the operational amplifier of a modular five-degree-of-freedom magnetic levitation compressor rotor system according to the present invention.

[0037] Figure 10 This is a schematic diagram of the structure of an inductive radial displacement sensor for a modular five-degree-of-freedom magnetic levitation compressor rotor system described in this utility model.

[0038] Figure Labels

[0039] 1. Magnetic levitation rotor spindle; 11. Shaft segment; 2. Drive motor; 21. Motor stator; 22. Motor rotor core; 3. Axial magnetic bearing assembly; 31. Axial stator core; 32. Axial coil winding; 33. Axial rotor core; 34. Stator pole; 35. Rotor pole; 4. Radial magnetic bearing assembly; 41. Cage; 42. E-shaped pole; 43. Permanent magnet; 44. Radial coil winding; 45. Radial rotor core laminations; 46. Two-in-four-out terminal block; 47. Power amplifier 48. Fault detection coil; 49. Operational amplifier; 410. Permanent magnet circuit; 411. Electromagnetic circuit; 412. Mounting groove; 413. Mounting hole; 414. Intermediate pole post; 415. Side pole post; 416. Magnetic pole groove; 5. Inductive radial displacement sensor; 51. Sensor stator core; 502. Sensor coil winding; 53. Sensor measuring ring; 54. Sensor magnetic pole; 6. Protective bearing; 7. Cooling impeller; 8. Centrifugal impeller; 9. Sleeve; 10. Air gap. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present utility model embodiments clearer, the present utility model embodiments will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model embodiments and are not intended to limit the present utility model embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0041] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0042] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0043] like Figures 1-10 As shown, a modular five-degree-of-freedom magnetic levitation compressor rotor system includes a magnetic levitation rotor shaft 1 and a drive motor 2 disposed in the middle of the magnetic levitation rotor shaft 1. In this embodiment, the motor rotor core 22 of the drive motor 2 is fixed to the middle of the magnetic levitation rotor shaft 1 via a shaft segment 11, and the motor stator 21 is sleeved on the outside of the motor rotor core 22. Centrifugal impellers 8 and cooling impellers 7 are respectively installed at both ends of the magnetic levitation rotor shaft 1. An axial magnetic bearing assembly 3 and a radial magnetic bearing assembly 4 are sequentially arranged on the magnetic levitation rotor shaft 1 between the drive motor 2 and the centrifugal impeller 8 and between the drive motor 2 and the cooling impeller 7. The axial magnetic bearing assembly 3 is a thrustless structure with direct magnetic field coupling; the radial magnetic bearing assembly 4 is a modular structure with segmented magnetic poles. The remaining two adjacent components on the magnetic levitation rotor shaft 1 are positioned by a sleeve 9.

[0044] Specifically, the axial magnetic bearing assembly 3 includes an axial rotor assembly sleeved on the outside of the magnetic levitation rotor main shaft 1 and an axial stator assembly sleeved on the outside of the axial rotor assembly, with an air gap 10 between the axial rotor assembly and the axial stator assembly; the axial stator assembly includes an axial stator core 31 and an axial coil winding 32, with the axial coil winding 32 wound between two axial stator magnetic poles 34 on the axial stator core 31; the axial rotor assembly includes an axial rotor core 33 and an axial rotor magnetic pole 35 integrally formed with the axial rotor core 33; the axial stator magnetic pole 34 and the axial rotor magnetic pole 35 overlap in the axial portion, and the overlap width is 1 / 5 of the width of the axial rotor magnetic pole 35 or the axial stator magnetic pole 34, and the overlap directions of the two axial magnetic bearing assemblies 3 on both sides of the drive motor 2 are opposite.

[0045] The radial magnetic bearing assembly 4 includes cages 41 at both ends and a modular radial magnetic pole assembly, a radial coil winding 44, and a radial rotor core lamination 45 arranged from the outside to the inside within the mounting cavity formed by the cages 41 at both ends. The modular radial magnetic pole assembly includes multiple E-shaped magnetic poles 42 evenly arranged in a circumferential array on the inner wall of one of the cages 41. Each E-shaped magnetic pole 42 has a central pole post 414 at the middle position of its inner arc side, and the two sides of the central pole post 414 are axially symmetrically arranged. There is a side pole post 415, and the width of the middle pole post 414 is twice the width of the side pole post 415. The number of turns of the radial coil winding wound on the middle pole post is twice the number of turns of the radial coil winding wound on the side pole post. Both the middle pole post 414 and the side pole post 415 are wound with radial coil windings 44. After the radial coil windings 44 are energized, they form SNS magnetic poles to form an electromagnetic circuit from the middle pole post 414, the radial rotor core laminations 45, the side pole post 415 to the return to the middle pole post 414.

[0046] In this embodiment, four E-shaped magnetic poles 42 are provided, and the E-shaped magnetic poles 42 are snapped onto the inner wall of one of the retainers 41 via the mounting groove 412. The end face of the other retainer 41 is provided with a mounting hole 413 to maintain a stable connection between the two retainers 41.

[0047] Two magnetic pole grooves 415 are formed on the outer arc side of one of the E-shaped magnetic poles 42. The two magnetic pole grooves 415 are located between the two side pole posts 415 and the middle pole post 414, respectively. A permanent magnet 43 is arranged in the magnetic pole groove 415, with the N pole of the permanent magnet 43 facing the middle pole post 414, so as to form a permanent magnet circuit 410 consisting of the N pole of the permanent magnet 43, the middle pole post 414, the radial rotor core lamination 45, the side pole posts 415, and the S pole of the permanent magnet 43.

[0048] The radial coil windings 44 on the side pole posts 415 on both sides of the same E-shaped magnetic pole 42 are connected in series and together with the radial coil windings 44 wound on the middle pole post 414 are connected to the two-in-four-out terminal 46. The two-in-four-out terminal 46 is connected to the power amplifier 47 so that the three radial coil windings 44 on the same E-shaped magnetic pole 42 can share one power amplifier 47.

[0049] Both the side pole post 415 and the middle pole post 414 are wound with fault detection coils 48, which are electrically connected to operational amplifier 49. This allows for the generation of a magnetic field under electromagnetic induction when current flows through the radial coil winding 44 under normal conditions. When the radial coil winding 44 changes, the generated magnetic flux changes. According to Faraday's law of electromagnetic induction and Oersted's law, the magnetic flux passing through the fault detection coil 48 changes accordingly, inducing an electromotive force, thus creating a voltage difference across the radial coil winding 44. This voltage difference signal is processed by operational amplifier 49 and output to operational amplifier 49. The amplified voltage difference signal is used to determine if the radial coil winding 44 is normal. When a fault occurs in the radial coil winding 44, changes in the current flowing through it will not cause a change in the amplified voltage difference signal, thus indicating a fault in the radial coil winding 44.

[0050] An inductive radial displacement sensor 5 is also provided on the magnetic levitation rotor main shaft 1 between the radial magnetic bearing assembly 4 and the centrifugal impeller 8 or the cooling impeller 7. The radial displacement sensor is electrically connected to the radial coil winding 44 of the radial magnetic bearing assembly 4 via a controller, so as to realize the control of the radial current flowing through the radial coil winding 44 based on the radial displacement signal detected by the inductive radial displacement sensor 5, thereby ensuring the balance and stability of the magnetic levitation rotor main shaft 1. A protective bearing 6 is provided between the inductive radial displacement sensor 5 and the centrifugal impeller 8 or the cooling impeller 7. Both the centrifugal impeller 8 and the cooling impeller 7 have flow divider blades, and the diameter and height of the centrifugal impeller 8 are larger than those of the cooling impeller 7, respectively.

[0051] The inductive radial displacement sensor 5 includes a sensor measuring ring 53 sleeved on the magnetic levitation rotor main shaft 1 and a sensor stator core 51 sleeved outside the sensor measuring ring 53. An air gap 10 is left between the sensor stator core 51 and the sensor measuring ring 53. An even number of sensor magnetic poles 54 are evenly arranged inside the sensor stator core 51. Each sensor magnetic pole 54 is wound with a sensor coil winding 502. Opposite sensor coil windings 502 are connected in series and wound in opposite directions. One of two adjacent sensor coil windings 502 is energized and the other is de-energized.

[0052] The axial stator core 31, axial rotor core 33, radial rotor core laminations 45, E-shaped magnetic poles 42, and sensor stator core 51 are all made of silicon steel; the permanent magnet 43 is made of rare earth permanent magnet material; and the sensor measuring ring 53 is made of permalloy.

[0053] A control method for a modular five-degree-of-freedom magnetic levitation compressor rotor system, including axial displacement control and radial displacement control;

[0054] The axial displacement control steps are as follows: Currents of opposite direction and equal magnitude are supplied to the axial coil windings 32 of the two axial magnetic bearing assemblies 3 located on both sides of the drive motor 2, so that the axial net force on the magnetic levitation rotor main shaft 1 is zero, and the suspension balance is maintained; when the magnetic levitation rotor main shaft 1 drives the axial rotor assembly to undergo axial displacement, the overlap between the axial stator magnetic pole 34 and the axial rotor magnetic pole 35 changes. At this time, the current supplied to the axial coil winding 32 on the side with increased overlap is reduced, and the current supplied to the axial coil winding 32 on the side with decreased overlap is increased, generating a reverse axial electromagnetic force until the magnetic levitation rotor main shaft 1 returns to balance.

[0055] Radial displacement control includes a rotational speed-based variable bias current control strategy and a redundant control strategy under fault conditions. The rotational speed-based variable bias current control strategy is as follows: When the rotational speed of the magnetic levitation rotor shaft 1 is 0 or lower than a set first threshold, the permanent magnet force provided by the permanent magnet 43 is used to levitate the magnetic levitation rotor shaft 1; when the magnetic levitation rotor shaft 1 rotates at a second threshold, a first bias current is passed into the radial coil winding 44 to generate an electromagnetic circuit 411. At this time, the electromagnetic circuit 411 is superimposed with the permanent magnet circuit 410 generated by the permanent magnet to enhance the radial stiffness and levitate the magnetic levitation rotor shaft 1; when the magnetic levitation rotor shaft 1 rotates at a third threshold, a second bias current is passed into the radial coil winding 44 to increase the radial stiffness and levitate the magnetic levitation rotor shaft 1; wherein the third threshold, the second threshold, and the first threshold decrease sequentially, and the second bias current is greater than the first bias current;

[0056] It should be noted that the magnitudes of the first threshold, second threshold, third threshold, first bias current, and second bias current set above all need to be determined according to the device dimensions. In this embodiment, the first threshold is 1 / 3 of the rotor's limiting speed, the second threshold is 2 / 3 of the rotor's limiting speed, and the third threshold is the rotor's limiting speed; the first bias current is 1 / 4 of the maximum coil current, and the second bias current is 1 / 2 of the maximum coil current.

[0057] Furthermore, in this embodiment, when the intermediate pole post 414 and the side pole post 415 fail simultaneously, one end of the retainer 41 can be opened, and the faulty E-shaped magnetic pole 42 can be removed and replaced. Since the entire radial magnetic bearing assembly 4 adopts a modular design, it is not necessary to completely disassemble the entire radial magnetic bearing assembly 4 during the replacement process, which can achieve quick disassembly and assembly, improve maintenance efficiency, and improve the reliability of the radial magnetic bearing assembly 4.

[0058] The redundancy control strategy is as follows: When the radial coil winding 44 on the side pole post 415 fails, the current of the radial coil winding 44 on the middle pole post 414 is increased to compensate for the electromagnetic flux (under experimental conditions, the current in the radial coil winding 44 on the middle pole post 414 is increased to twice the original value; under actual conditions, it is adjusted according to the rotor vibration amplitude detected by the displacement sensor, that is, the current is increased until the difference between the rotor vibration amplitude and the vibration amplitude before the coil failure is less than the set value), thereby keeping the radial displacement stiffness in the direction of the E-shaped magnetic pole 42 unchanged; when the radial coil winding 44 on the middle pole post 414 fails, the current of the radial coil winding 44 on both side pole posts 415 is increased to compensate for the electromagnetic flux, thereby keeping the radial displacement stiffness in the direction of the E-shaped magnetic pole 42 unchanged.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. A modular five-degree-of-freedom magnetic levitation compressor rotor system, comprising a magnetic levitation rotor shaft and a driving motor arranged in the middle of the magnetic levitation rotor shaft, a centrifugal impeller and a cooling impeller are respectively arranged at both ends of the magnetic levitation rotor shaft, and an axial magnetic bearing assembly and a radial magnetic bearing assembly are sequentially arranged on the magnetic levitation rotor shaft between the driving motor and the centrifugal impeller and on the magnetic levitation rotor shaft between the driving motor and the cooling impeller, characterized in that: The axial magnetic bearing assembly is a thrustless disk structure with direct magnetic field coupling; the radial magnetic bearing assembly is a modular structure with segmented magnetic poles.

2. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 1, characterized in that: The axial magnetic bearing assembly includes an axial rotor assembly sleeved on the outside of the magnetic levitation rotor main shaft and an axial stator assembly sleeved on the outside of the axial rotor assembly, with an air gap between the axial rotor assembly and the axial stator assembly. The axial stator assembly includes an axial stator core and an axial coil winding, which is wound between two axial stator poles on the axial stator core. The axial rotor assembly includes an axial rotor core and axial rotor magnetic poles integrally formed with the surface of the axial rotor core. The axial stator magnetic poles and the axial rotor magnetic poles overlap in the axial portion, and the overlap width is 1 / 5 of the width of the axial rotor magnetic pole or the axial stator magnetic pole. The overlap directions of the two axial magnetic bearing assemblies located on both sides of the drive motor are opposite.

3. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 2, characterized in that: The radial magnetic bearing assembly includes cages at both ends and a modular radial magnetic pole assembly, radial coil windings, and radial rotor core laminations arranged from the outside to the inside within the mounting cavity formed by the cages at both ends. The modular radial magnetic pole assembly includes multiple E-shaped magnetic poles evenly arranged in a circumferential array on the inner wall of one of the cages. Each E-shaped magnetic pole has a central pole post at the middle position of its inner arc side. Side pole posts are arranged symmetrically on both sides of the central pole post. The width of the central pole post is twice the width of the side pole posts. Radial coil windings are wound on both the central pole post and the side pole posts. The number of turns of the radial coil windings wound on the central pole post is twice the number of turns of the radial coil windings wound on the side pole posts. When the radial coil winding is energized, it forms SNS magnetic poles to form an electromagnetic circuit from the intermediate pole post, radial rotor core laminations, side pole posts to the return intermediate pole post.

4. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 3, characterized in that: Two magnetic pole grooves are opened on the outer arc side of one of the E-shaped magnetic poles. The two magnetic pole grooves are located between the two side pole posts and the middle pole post, respectively. A permanent magnet is installed in the magnetic pole groove, with the N pole of the permanent magnet facing the middle pole post, so as to form a permanent magnet circuit consisting of the N pole of the permanent magnet, the middle pole post, the radial rotor core laminations, the side pole posts, and the S pole of the permanent magnet.

5. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 4, characterized in that: The radial coil windings on the side pole posts of the same E-shaped magnetic pole are connected in series and then connected together with the radial coil winding wound on the middle pole post to the two-in-four-out terminal. The two-in-four-out terminal is connected to the power amplifier so that the three radial coil windings on the same E-shaped magnetic pole can share one power amplifier.

6. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 5, characterized by: Fault detection coils are wound on both the side poles and the middle poles, and the fault detection coils are electrically connected to the operational amplifier.

7. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 6, characterized by: An inductive radial displacement sensor is also installed on the magnetic levitation rotor main shaft between the radial magnetic bearing assembly and the centrifugal impeller or cooling impeller. The radial displacement sensor is electrically connected to the radial coil winding of the radial magnetic bearing assembly via a controller, so as to realize the radial displacement signal of the magnetic levitation rotor main shaft detected by the inductive radial displacement sensor, control the current to be passed through the radial coil winding, and ensure the balance and stability of the magnetic levitation rotor main shaft. A protective bearing is provided between the inductive radial displacement sensor and the centrifugal impeller or cooling impeller; Both the centrifugal impeller and the cooling impeller have flow divider blades, and the diameter and height of the centrifugal impeller are larger than those of the cooling impeller, respectively.

8. A modular five-degree-of-freedom magnetic levitation compressor rotor system according to claim 7, characterized in that: The inductive radial displacement sensor includes a sensor measuring ring sleeved on the main shaft of the magnetic levitation rotor and a sensor stator core sleeved outside the sensor measuring ring. An air gap is left between the sensor stator core and the sensor measuring ring, and an even number of sensor magnetic poles are evenly arranged inside the sensor stator core. Each sensor magnetic pole is wound with a sensor coil winding. Opposite sensor coil windings are connected in series and wound in opposite directions. One of two adjacent sensor coil windings is energized and the other is de-energized.

9. A modular five degree of freedom magnetic levitation compressor rotor system according to claim 8, characterized by: The axial stator core, axial rotor core, radial rotor core laminations, E-shaped magnetic poles, and sensor stator core are all made of silicon steel; the permanent magnets are made of rare earth permanent magnet materials; and the sensor measuring ring is made of permalloy.

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