High-reliability low-power-consumption radial-axial magnetic bearing and design method thereof

Abstract

The invention discloses a high-reliability low-power-consumption radial-axial magnetic bearing and a design method thereof, and relates to the technical field of magnetic suspension bearings, and the high-reliability low-power-consumption radial-axial magnetic bearing comprises a rotor assembly, a magnetic conduction sleeve, a magnetic conduction sleeve and a magnetic conduction sleeve, one end of the stator assembly is provided with a plurality of stator magnetic poles I, and the other end is provided with a plurality of stator magnetic poles II; one end surface, close to the acting surface, of each stator magnetic pole I is an acting surface III; a working air gap I is formed between the acting surface III and the acting surface I; the end surfaces, close to the acting surfaces II, of the stator magnetic poles II are acting surfaces IV; a working air gap II is formed between the acting surface IV and the acting surface II; the radial coil is sleeved on the stator magnetic pole I and the stator magnetic pole II; the first permanent magnet ring is embedded in the middle of the stator assembly, and the second permanent magnet ring and the third permanent magnet ring are sleeved on the periphery of the flux sleeve. According to the invention, damping is provided for the axial passive magnetic bearing by using the function of the existing radial active magnetic bearing without increasing the loss of the magnetic bearing system, and an ideal suspension scheme is provided for the design of a high-reliability and low-loss system.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic suspension bearings, and in particular to a high-reliability, low-power consumption radial-axial magnetic bearing and a design method thereof. Background Art

[0002] Compared with traditional mechanical bearings, magnetic bearings have the advantages of being oil-free, friction-free, and capable of active vibration suppression. They meet the needs of high-speed and high-precision operation under complex working conditions and are widely used in molecular pumps, flywheel energy storage, turbomachinery, artificial hearts and other fields.

[0003] The stable operation of the rotor requires multiple magnetic bearings to achieve multi-degree-of-freedom suspension. Usually, pure electromagnetic bearings, permanent magnetic biased magnetic bearings or permanent magnetic bearings are used to suspend different degrees of freedom respectively. Among them, pure electromagnetic bearings and permanent magnetic biased magnetic bearings are called active magnetic bearings because they are actively controlled by electromagnetic coils; permanent magnetic bearings are passively controlled by permanent magnets and are called passive magnetic bearings. For example: Chinese patent CN202411035850.5 discloses a five-degree-of-freedom active magnetic bearing, in which the magnetic bearings of each degree of freedom occupy a large space, resulting in a long axial length of the system, affecting the modal improvement of the rotor assembly, and is not conducive to the improvement of the working speed of the rotor assembly. The existing design methods mostly innovate the structure of the active magnetic bearing. Chinese patent CN201110253446.1 discloses a five-degree-of-freedom radial decoupled conical magnetic bearing, which realizes active control in radial and axial directions; but this structure has two problems: First, a large current needs to be passed through the coils of each degree of freedom to achieve rotor suspension, resulting in a large amount of stator copper loss and rotor iron loss. The highly integrated structure has difficulty in dissipating heat, which causes the system to generate serious heat and affects its stable operation. Secondly, the magnetic bearings of each degree of freedom need to be equipped with hardware such as power amplifiers and sensors, which generates a large amount of additional power consumption, increases the weight of the system, and increases the size of the system.

[0004] In order to meet the requirements of high load capacity and low power consumption under the constraints of small volume and high integration as much as possible, the integration of active magnetic bearings and passive magnetic bearings has become the mainstream because permanent magnets do not require external power supply or control system, but the following problems still exist: For example, Chinese patent CN201910810450.X discloses a radial-axial permanent magnetic bearing system device, whose passive magnetic bearing lacks damping. When the system is disturbed, the direction of the passive magnetic bearing output may cause the rotor to enter an oscillation state, which brings the risk of vibration to the system, especially under the condition of rapid change of dynamic load, the stability of the system is difficult to guarantee. Chinese patent CN201510017297.7 discloses a permanent magnet biased outer rotor four-degree-of-freedom active-passive hybrid magnetic bearing, which takes into account the damping of the system and realizes active control through an additional electromagnetic damping magnetic circuit. However, this active damping method requires additional sensors, controllers and power supplies, resulting in increased system power consumption, and the advantage of low power consumption of passive bearings is no longer prominent. At the same time, the permanent magnets of the passive magnetic bearings are fixedly connected to the system and cannot be disassembled, that is, the stiffness of the system cannot be adjusted, and it cannot adapt to different working conditions, which may cause the stability of the system to deteriorate under certain loads or vibration modes. It can be seen that in the existing highly integrated magnetic levitation system, it is hoped that the system power consumption will be lower and the reliability will be higher under the premise of minimizing the volume. The passive magnetic bearing stiffness cannot be adjusted and there is no damping, which easily brings vibration risks to the system, reducing the reliability of the system and failing to meet the use requirements of complex working conditions. However, the active damping method requires an additional controller, which adds additional losses to the system. Summary of the invention

[0005] In view of this, the present invention proposes a high-reliability, low-power radial-axial magnetic bearing and a design method thereof, aiming to solve the technical problem that active damping control of the above-mentioned traditional active-passive hybrid magnetic bearing introduces large power consumption.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] On one hand, the present invention provides a high-reliability, low-power consumption radial-axial magnetic bearing, comprising:

[0008] A rotor assembly, the rotor assembly comprising a rotor shaft and a magnetically conductive sleeve coaxially fixed on the rotor shaft; the outer peripheral wall surface at one end of the magnetically conductive sleeve is a conical active surface 1, and the outer peripheral wall surface at the other end is a conical active surface 2;

[0009] A stator assembly, wherein the stator assembly is annular and movably sleeved on the outer periphery of the rotor assembly, wherein one end of the stator assembly has a plurality of stator poles 1 uniformly arranged around the outer periphery of the first action surface, and the other end has a plurality of stator poles 2 uniformly arranged around the outer periphery of the second action surface; the end surfaces of the plurality of stator poles 1 close to the first action surface are the third action surfaces opposite to the first action surface and matching the contour; a working air gap 1 is formed between the third action surface and the first action surface; the end surfaces of the plurality of stator poles 2 close to the second action surface are the fourth action surfaces opposite to the first action surface and matching the contour; a working air gap 2 is formed between the fourth action surface and the second action surface;

[0010] Radial coil; the radial coil is sleeved on the stator pole 1 and the stator pole 2;

[0011] Permanent magnet ring one, permanent magnet ring two and permanent magnet ring three; the permanent magnet ring one is axially magnetized and coaxially embedded in the middle of the stator assembly; the permanent magnet ring two and the permanent magnet ring three are both radially magnetized and sleeved on the outer periphery of the magnetic conductive sleeve and located in the annular hole of the stator assembly; the outer periphery of the permanent magnet ring two is opposite to the opposite magnetic poles at one end of the permanent magnet ring one; the outer periphery of the permanent magnet ring three is opposite to the opposite magnetic poles at the other end of the permanent magnet ring one.

[0012] The two ends of the magnetic sleeve of the high-reliability, low-power radial-axial magnetic bearing of the present invention are designed to be tapered, so that the magnetic attraction of the stator pole 1 and the stator pole 2 to the rotor assembly has both radial and axial components. The radial suspension of the rotor shaft is achieved by superposition of the radial bias magnetic circuit and the radial control magnetic circuit, specifically: the permanent magnet ring 1 generates bias magnetic flux in the working air gap 1 and the working air gap 2; the radial coil sleeved on the stator pole 1 generates control magnetic flux in the working air gap 1, and the radial coil sleeved on the stator pole 2 generates control magnetic flux in the working air gap 2 to form a radial magnetic bearing, the bias magnetic flux in the working air gap 1 and the working air gap 2 is superimposed with the control magnetic flux, and the radial position deviation of the rotor shaft can be corrected by controlling the current of the radial coil, so that the rotor shaft can be stably suspended at the axis center of the stator assembly. The axial suspension of the rotor shaft is achieved by a non-adjustable passive part and an actively adjustable active part. Specifically, the non-adjustable passive part is an axial passive magnetic bearing composed of permanent magnet ring 1, permanent magnet ring 2 and permanent magnet ring 3. When the rotor shaft is deviated from the position due to axial disturbance, the two ends of permanent magnet ring 1 can generate a magnetic attraction force on permanent magnet ring 2 and permanent magnet ring 3 in the opposite direction of the axial deviation to correct the position; the actively adjustable active part is composed of the bias magnetic flux generated by permanent magnet ring 1 in working air gap 1 and working air gap 2 and the magnetic pole sleeved on stator pole 1. The radial coil generates a control magnetic flux in the working air gap one, and the radial coil sleeved on the stator magnetic pole two generates a control magnetic flux in the working air gap two. When the axial position of the rotor shaft deviates, the radial coil current is adjusted to make the control magnetic flux in the working air gap one subtract or add the bias magnetic flux, and the control magnetic flux in the working air gap two add or subtract the bias magnetic flux, so that the magnetic attraction force of the action surface three on the action surface one and the magnetic attraction force of the action surface four on the action surface two are different in magnitude, thereby providing active damping force for the axial position deviation and vibration of the rotor shaft. The present invention uses the bearing capacity of the axial component provided as the active damping of the passive magnetic bearing by tapering the magnetic poles of the radial magnetic bearing, without additionally increasing the loss of the magnetic bearing system.

[0013] As a further improvement of the above technical solution, the stator assembly includes a stator core 1, a stator magnetic ring 1, a stator magnetic ring 2 and a stator core 2; the stator core 1, the stator magnetic ring 1, the permanent magnet ring 1, the stator magnetic ring 2 and the stator core 2 are all annular and coaxially stacked in sequence to form an annular stator structure;

[0014] The stator core 1 has a plurality of stator poles 1 uniformly arranged around the periphery of the active surface 1; the stator core 2 has a plurality of stator poles 2 uniformly arranged around the periphery of the active surface 2.

[0015] As a further improvement of the above technical solution, the rotor shaft, the stator magnetic ring 1 and the stator magnetic ring 2 are all made of soft magnetic materials; the magnetic sleeve, the stator core 1 and the stator core 2 are all laminated structures.

[0016] The above technical solution has the beneficial effect that the rotor shaft, stator magnetic ring 1 and stator magnetic ring 2 are made of soft magnetic material to reduce hysteresis loss. The laminated magnetic sleeve, stator core 1 and stator core 2 can suppress eddy current, reduce eddy current loss and reduce heat generation.

[0017] As a further improvement of the above technical solution, the stator core 1 includes an annular stator yoke 1 and three or more stator poles 1 uniformly distributed along the inner circumferential wall of the stator yoke 1;

[0018] The stator core 2 includes an annular stator yoke 2 and more than three stator poles 2 uniformly distributed along the inner circumferential wall of the stator yoke 2;

[0019] The stator magnetic yoke 1, the stator magnetic conductive ring 1, the permanent magnetic ring 1, the stator magnetic conductive ring 2 and the stator magnetic yoke 2 are coaxially detachably stacked in sequence.

[0020] The beneficial effects of the above technical solution are: the detachable and stacked stator magnetic ring 1, permanent magnet ring 1, stator magnetic ring 2 and stator magnetic yoke 2 are easy to repair and replace; in addition, by replacing the permanent magnet ring 1 with different materials and different magnetic field strengths, the stiffness of the permanent magnet in the radial-axial magnetic bearing system can be changed, thereby meeting the use requirements under complex working conditions; it can solve the problem of the non-adjustable stiffness provided by the permanent magnet in the traditional magnetic bearing without changing the magnetic properties of the permanent magnet.

[0021] As a further improvement of the above technical solution, the axial lengths of the stator magnetic ring 1, the permanent magnet ring 1 and the stator magnetic ring 2 are individually adjustable, but the sum of the three lengths remains unchanged, so that the magnetic field strength at both ends of the permanent magnet ring 1 can be adjusted by changing the axial length of the permanent magnet ring 1.

[0022] The beneficial effect of the above technical solution is: by replacing the permanent magnet ring 1 with different lengths, the magnetic field strength at its two ends is adjusted, thereby realizing the adjustment of the size of the magnetic attraction between the two ends of the permanent magnet ring 1 and the permanent magnet ring 2 and the permanent magnet ring 3, as well as the adjustment of the strength of the bias magnetic field in the working air gap 1 and the working air gap 2, thereby realizing the stiffness adjustment of the radial-axial magnetic bearing.

[0023] As a further improvement of the above technical solution, the permanent magnet ring 2 and the permanent magnet ring 3 are detachably sleeved in the middle of the magnetic conductive sleeve, and an axial air gap is formed between the outer peripheral wall surface of the permanent magnet ring 2 and the permanent magnet ring 3 and the inner peripheral wall surface of the permanent magnet ring 1.

[0024] As a further improvement of the above technical solution, the radial lengths of the permanent magnet ring two and the permanent magnet ring three are adjustable, so as to adjust the magnetic field strength on the outer peripheral side of the permanent magnet ring two and the permanent magnet ring three by changing the radial lengths of the permanent magnet ring two and the permanent magnet ring three.

[0025] The beneficial effect of the above technical solution is that by replacing permanent magnet ring 2 and permanent magnet ring 3 of different radial lengths, the magnetic attraction force between permanent magnet ring 2, permanent magnet ring 3 and both ends of permanent magnet ring 1 can be adjusted, thereby achieving stiffness adjustment of the radial-axial magnetic bearing system.

[0026] As a further improvement of the above technical solution, an annular mounting groove 1 and an annular mounting groove 2 are circumferentially opened between the corresponding active surface 1 and the active surface 2 on the outer circumferential wall of the magnetic sleeve; the annular mounting groove 1 and the annular mounting groove 2 are axially spaced apart from each other along the magnetic sleeve; the inner circumferential wall of the permanent magnet ring 2 can be removably embedded in the annular mounting groove 1; the inner circumferential wall of the permanent magnet ring 3 can be removably embedded in the annular mounting groove 2.

[0027] The beneficial effect of the above technical solution is that the inner circumferential walls of the permanent magnetic rings 2 and 3 can be detachably embedded in the outer circumferential wall of the magnetic sleeve, which can increase the stability of the structure, facilitate the connection of the magnetic circuits between the permanent magnetic rings 2 and 3 and the magnetic sleeve, and reduce magnetic leakage.

[0028] As a further improvement of the above technical solution, the first and second action surfaces have the same structure and are both in the shape of a truncated cone coaxially arranged with the rotor shaft.

[0029] Another aspect of the present invention provides a design method for a high-reliability, low-power consumption radial-axial magnetic bearing, comprising the following steps:

[0030] Step 1: Determine the mechanical parameter design input; determine the maximum operating speed of the rotor, the modal frequency of the rotor, the outer diameter of the rotor, and the mass of the rotor according to the actual working conditions and application scenarios;

[0031] Step 2: Determine the basic electromagnetic design input; determine the working air gap length of the magnetic bearing according to the mechanical assembly and actual control accuracy; determine the magnetic material according to the mechanical strength and working environment requirements, and test the material's magnetic permeability, saturation flux density and bias flux density; select the permanent magnet material according to the bias flux density and working environment; determine the radial bias force, dynamic bearing capacity and maximum bearing capacity required for the rotor according to the rotor mass and actual application conditions; determine the feasible range of current stiffness and the feasible range of displacement stiffness according to the actual dynamic performance;

[0032] Step 3: Construct a reluctance network for radial bias flux, calculate magnetic potential, reluctance, and flux, and allocate the dimensions of each component of the radial magnetic bearing;

[0033] Step 4: Construct a magnetic resistance network for radial flux control and determine coil parameters;

[0034] Step 5: Calculate radial current stiffness and displacement stiffness;

[0035] Step 6: Determine the axial passive force;

[0036] Step 7: Calculate the required axial damping.

[0037] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a high-reliability, low-power consumption radial-axial magnetic bearing and a design method thereof, which has the following advantages and beneficial effects:

[0038] 1. The passive permanent magnet design of the present invention is combined with the active conical magnetic pole to form a symmetrical high-integrated structure, which shortens the axial length of the stator and the rotor, improves the mode of the rotor assembly, and is conducive to the improvement of the operating speed of the rotor assembly.

[0039] 2. The present invention uses conical magnetic poles to realize active control of the passive part of the permanent magnet, which can ensure the stability of the system under the condition of rapid changes in dynamic loads and meet the requirements of high reliability of the system. No additional loss is added to the passive system, meeting the requirements of low loss of the system.

[0040] 3. The stacked arrangement of permanent magnets in the permanent magnet passive structure of the present invention is not only simple in structure, but also greatly improves the bearing capacity and stiffness per unit volume, and can provide a large axial bias force, breaking through the limitations of axial bearing capacity and stiffness under limited volume.

[0041] 4. The radially magnetized permanent magnet ring 2 and permanent magnet ring 3 of the present invention can be detachably embedded in the outer periphery of the magnetic conductive sleeve, and their magnetic materials and radial lengths can be flexibly replaced and adjusted according to needs; the axial length and material of the axially magnetized permanent magnet ring 1 can also be flexibly replaced and adjusted according to needs; and thus, without changing the magnetic properties of the permanent magnet, the problem of the non-adjustable stiffness provided by the permanent magnet is solved, the use requirements under complex working conditions are met, and the reliability of the system is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0043] Figure 1 A schematic axial cross-sectional view of a high-reliability, low-power consumption radial-axial magnetic bearing according to the present invention;

[0044] Figure 2A schematic structural diagram of a stator core of a high-reliability, low-power consumption radial-axial magnetic bearing according to the present invention;

[0045] Figure 3 A schematic diagram of the second structure of a stator core of a high-reliability, low-power radial-axial magnetic bearing according to the present invention;

[0046] Figure 4 A schematic diagram of the structure of a permanent magnet ring of a high-reliability, low-power radial-axial magnetic bearing according to the present invention;

[0047] Figure 5 A schematic diagram of the structure of a permanent magnet ring of a high-reliability, low-power radial-axial magnetic bearing according to the present invention;

[0048] Figure 6 A schematic diagram of a radial bias magnetic circuit of a high-reliability, low-power radial-axial magnetic bearing of the present invention;

[0049] Figure 7 A schematic diagram of a radial control magnetic circuit generated by the stator magnetic poles of a high-reliability and low-power radial-axial magnetic bearing according to the present invention cooperating with the radial coils sleeved thereon;

[0050] Figure 8 A schematic diagram of a radial control magnetic circuit generated by the cooperation between the second stator magnetic pole of a high-reliability and low-power radial-axial magnetic bearing of the present invention and a radial coil sleeved thereon;

[0051] Fig. 9 A schematic diagram of the superposition principle of radial bias magnetic flux and control magnetic flux of a high-reliability and low-power radial-axial magnetic bearing of the present invention;

[0052] Fig.10 A schematic diagram of an axial passive control magnetic circuit generated by permanent magnet rings 1, 2 and 3 of a high-reliability, low-power radial-axial magnetic bearing according to the present invention;

[0053] Fig.11 A working principle diagram of a non-damping part of a passive magnetic bearing of a high-reliability and low-power radial-axial magnetic bearing of the present invention providing a bias electromagnetic force;

[0054] Fig.12 A schematic diagram of active damping control of magnetic flux of a passive magnetic bearing of a high-reliability and low-power radial-axial magnetic bearing of the present invention;

[0055] Fig.13 A schematic diagram of the magnetic resistance calculation rules of the stator and rotor of a high-reliability and low-power radial-axial magnetic bearing of the present invention;

[0056] In the figure: 1. rotor assembly; 11. rotor shaft; 12. magnetic sleeve; 121. active surface one; 122. active surface two; 2. stator assembly; 21. stator core one; 211. stator pole one; 2111. active surface three; 212. stator yoke one; 22. stator magnetic ring one; 23. stator magnetic ring two; 24. stator core two; 241. stator pole two; 2411. active surface four; 242. stator yoke two; 3. radial coil; 4. permanent magnet ring one; 5. permanent magnet ring two; 6. permanent magnet ring three; 7. working air gap one; 8. working air gap two; 9. axial air gap. DETAILED DESCRIPTION

[0057] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0058] In the description of the present invention, it is necessary to understand that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0059] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] According to an embodiment of the present invention, Figures 1 to 5 As shown, a high-reliability and low-power consumption radial-axial magnetic bearing comprises:

[0062] The rotor assembly 1 comprises a rotor shaft 11 and a magnetically conductive sleeve 12 coaxially sleeved and fixed on the rotor shaft 11; the outer peripheral wall surface at one end of the magnetically conductive sleeve 12 is a conical active surface 121, and the outer peripheral wall surface at the other end is a conical active surface 2 122;

[0063] The stator component 2 is annular and movably sleeved on the outer periphery of the rotor component 1. One end of the stator component 2 has a plurality of stator poles 1 211 uniformly arranged around the outer periphery of the first action surface 121, and the other end has a plurality of stator poles 2 241 uniformly arranged around the outer periphery of the second action surface 122; the end surfaces of the plurality of stator poles 1 211 close to the first action surface 121 are the third action surfaces 2111 opposite to the first action surface 121 and matching the contour; a working air gap 1 7 is formed between the third action surface 2111 and the first action surface 121; the end surfaces of the plurality of stator poles 2 241 close to the second action surface 122 are the fourth action surfaces 2411 opposite to the first action surface 121 and matching the contour; a working air gap 2 8 is formed between the fourth action surface 2411 and the second action surface 122;

[0064] Radial coil 3; radial coil 3 is sleeved on stator pole 1 211 and stator pole 2 241;

[0065] Permanent magnet ring 1 4, permanent magnet ring 2 5 and permanent magnet ring 3 6; permanent magnet ring 1 4 is axially magnetized and coaxially embedded in the middle of the stator assembly 2; permanent magnet ring 2 5 and permanent magnet ring 3 6 are both radially magnetized and sleeved on the outer periphery of the magnetic conductive sleeve 12 and located in the annular hole of the stator assembly 2; the outer periphery of permanent magnet ring 2 5 is opposite to the opposite magnetic poles at one end of permanent magnet ring 1 4; the outer periphery of permanent magnet ring 3 6 is opposite to the opposite magnetic poles at the other end of permanent magnet ring 1 4.

[0066] The two ends of the magnetic sleeve 12 of the high-reliability, low-power radial-axial magnetic bearing of this embodiment are designed to be tapered, so that the magnetic attraction of the stator pole 1 211 and the stator pole 2 241 to the rotor assembly 1 has both radial and axial components. The radial suspension of the rotor shaft 11 is achieved by superposition of the radial bias magnetic circuit and the radial control magnetic circuit, specifically: the permanent magnet ring 1 4 generates a bias magnetic flux in the working air gap 1 7 and the working air gap 2 8; the radial coil 3 sleeved on the stator pole 1 211 generates a control magnetic flux in the working air gap 1 7, and the radial coil 3 sleeved on the stator pole 2 241 generates a control magnetic flux in the working air gap 2 8 to form a radial magnetic bearing, the bias magnetic flux in the working air gap 1 7 and the working air gap 2 8 is superimposed with the control magnetic flux, and the radial position deviation of the rotor shaft 11 can be corrected by controlling the current of the radial coil 3, so that the rotor shaft 11 can be stably suspended at the axis of the stator assembly 2. The axial suspension of the rotor shaft 11 is achieved by a non-adjustable passive part and an actively adjustable active part. Specifically, the non-adjustable passive part is an axial passive magnetic bearing composed of permanent magnet ring 1 4, permanent magnet ring 2 5 and permanent magnet ring 3 6. When the rotor shaft 11 is deviated from its position due to axial disturbance, the two ends of permanent magnet ring 1 4 can generate a magnetic attraction force on permanent magnet ring 2 5 and permanent magnet ring 3 6 in the opposite direction of the axial deviation to correct the position; the actively adjustable active part is a bias magnetic flux generated by permanent magnet ring 1 4 in working air gap 1 7 and working air gap 2 8 and a radial coil 3 sleeved on stator pole 1 211. The control magnetic flux is generated in the working air gap 1 7, and the radial coil 3 sleeved on the stator pole 2 241 generates a control magnetic flux in the working air gap 2 8. When the axial position of the rotor shaft 11 deviates, the control magnetic flux in the working air gap 1 7 is subtracted or added to the bias magnetic flux, and the control magnetic flux in the working air gap 2 8 is added or subtracted by adjusting the current of the radial coil 3, so that the magnetic attraction force of the action surface 3 2111 on the action surface 1 121 and the magnetic attraction force of the action surface 4 2411 on the action surface 2 122 are different in magnitude, thereby providing active damping force for the axial position deviation and vibration of the rotor shaft 11. The present invention uses the bearing capacity of the axial component provided as the active damping of the passive magnetic bearing by tapering the magnetic poles of the radial magnetic bearing, without additionally increasing the loss of the magnetic bearing system.

[0067] It should be noted that: the rotor assembly 1, the permanent magnet ring 2 5, and the permanent magnet ring 3 6 together constitute a rotor system; the stator assembly 2, the permanent magnet ring 1 4, and each radial coil 3 together constitute a stator system.

[0068] In some embodiments, the stator assembly 2 includes a stator core 1 21, a stator magnetic ring 1 22, a stator magnetic ring 2 23 and a stator core 2 24; the stator core 1 21, the stator magnetic ring 1 22, the permanent magnet ring 1 4, the stator magnetic ring 2 23 and the stator core 2 24 are all annular and coaxially stacked in sequence to form an annular stator structure;

[0069] The stator core 1 21 has a plurality of stator poles 1 211 uniformly arranged around the periphery of the active surface 1 121 ; the stator core 2 24 has a plurality of stator poles 2 241 uniformly arranged around the periphery of the active surface 2 122 .

[0070] In some embodiments, the rotor shaft 11, the stator magnetic ring 1 22 and the stator magnetic ring 2 23 are all made of soft magnetic materials.

[0071] The use of soft magnetic materials to make the rotor shaft 11, the stator magnetic conductive ring 1 22 and the stator magnetic conductive ring 2 23 can reduce hysteresis loss.

[0072] In some embodiments, the magnetic conductive sleeve 12 , the stator core 1 21 and the stator core 2 24 are all laminated structures.

[0073] The laminated structure of the magnetic conductive sleeve 12, the stator core 1 21 and the stator core 2 24 can suppress eddy current, reduce eddy current loss and reduce heat generation.

[0074] In some embodiments, the stator core 21 includes an annular stator yoke 212 and three or more stator poles 211 uniformly distributed along the inner circumferential wall of the stator yoke 212;

[0075] The second stator core 24 includes a second annular stator yoke 242 and more than three second stator poles 241 uniformly distributed along the inner circumferential wall of the second stator yoke 242;

[0076] The stator yoke 1 212 , the stator magnetic conductive ring 1 22 , the permanent magnetic ring 1 4 , the stator magnetic conductive ring 2 23 and the stator yoke 2 242 are coaxially detachably stacked in sequence.

[0077] The detachable and stacked stator magnetic ring 22, permanent magnet ring 4, stator magnetic ring 23 and stator magnetic yoke 242 are easy to repair and replace. In addition, by replacing the permanent magnet ring 4 with different materials and different magnetic field strengths, the stiffness of the permanent magnet in the radial-axial magnetic bearing system can be changed to meet the use requirements under complex working conditions. It can solve the problem of the non-adjustable stiffness provided by the permanent magnet in the traditional magnetic bearing without changing the magnetic properties of the permanent magnet.

[0078] For details, see Figures 1 to 3 There are four stator poles 1 211 and four stator poles 2 241, and the four stator poles 1 211 and the four stator poles 2 241 are arranged one by one in the axial direction of the stator assembly 2. The shapes of the stator poles 1 211 and the stator poles 2 241 can be designed in the form of pole shoes.

[0079] Specifically, the radial coils 3 are connected in series as follows: the two radial coils 3 sleeved on the stator pole 1 211 and the stator pole 2 241 corresponding to the X+ direction are connected in series, and the two radial coils 3 sleeved on the stator pole 1 211 and the stator pole 2 241 corresponding to the X- direction are connected in series; the two radial coils 3 sleeved on the stator pole 1 211 and the stator pole 2 241 corresponding to the Y+ direction are connected in series, and the two radial coils 3 sleeved on the stator pole 1 211 and the stator pole 2 241 corresponding to the Y- direction are connected in series.

[0080] It should be noted that the multiple radial coils 3 can be controlled independently or connected in series or parallel as required. The specific connection method of the multiple radial coils 3 can be set as required.

[0081] Specifically, the magnetic poles of the stator core 1 21 and the stator core 2 24 can both be eight poles or three poles.

[0082] For details, see Figure 4 and Figure 5 , Figure 4 The middle arrow indicates that the magnetization direction of the permanent magnet ring 2 5 is away from its center along its radial direction; Figure 5 The middle arrow indicates that the magnetizing direction of the permanent magnet ring 3 6 is along its radial direction and points to its center; the magnetizing direction of the permanent magnet ring 2 5 can also be along its radial direction and point to its center, but the magnetizing directions of the permanent magnet ring 2 5 and the permanent magnet ring 3 6 need to be set oppositely.

[0083] Specifically, Figure 6 The radial bias magnetic circuit generated by the permanent magnet ring 4 is shown, starting from the N magnetic pole end of the permanent magnet ring 4, and passing through the stator magnetic ring 2 23, the stator yoke 2 242, the stator pole 2 241, the action surface 4 2411, the working air gap 28, the action surface 2 122, the magnetic sleeve 12, the action surface 1 121, the working air gap 17, the action surface 3 2111, the stator pole 1 211, the stator yoke 1 212, the stator magnetic ring 22, the S magnetic pole of the permanent magnet ring 4, and the N magnetic pole of the permanent magnet ring 4, to form a closed loop.

[0084] Specifically, Figure 7 The radial control magnetic circuit generated by the cooperation between the stator pole 1 and the radial coil mounted thereon is shown. The radial coil 3 on the two radially opposite stator poles 1 is energized to generate a magnetic field, which passes through one of the stator poles 1 211, the working air gap 17, the magnetic sleeve 12, the working air gap 17, the other stator pole 1 211, and the stator yoke 1 212 in sequence to form a closed loop.

[0085] Specifically, Figure 8The radial control magnetic circuit generated by the cooperation between the stator pole 2 and the radial coil mounted thereon is shown. The radial coil 3 on the two radially opposite stator poles 2 is energized to generate a magnetic field, which passes through one of the stator poles 241, the working air gap 28, the magnetic sleeve 12, the working air gap 28, the other stator pole 241, and the stator yoke 242 in sequence to form a closed loop.

[0086] For details, see Fig. 9 , Fig. 9 The working principle of radial suspension by superposition of radial bias flux and control flux is demonstrated. Taking the radial magnetic bearing suspension corresponding to one end of the stator core 21 as an example, if the rotor shaft 11 is disturbed in the X direction, causing the rotor shaft 11 to deviate in the X+ direction, see Fig. 9 The bias magnetic flux is generated by the permanent magnetic ring 14, and passes through the stator magnetic ring 23, the stator yoke 242, the stator magnetic pole 241, the working air gap 28, the magnetic sleeve 12, the working air gap 7, the stator magnetic pole 211, the stator yoke 212, the stator magnetic ring 22 and returns to the permanent magnetic ring 14. Its direction is from the action surface 121 of the magnetic sleeve 12 to the action surface 3 2111 of the stator magnetic pole 211. The control magnetic flux is generated by the radial coil 3 corresponding to the X+ direction and the X- direction, and passes through the stator magnetic pole 1211 in the X+ direction, the working air gap 17 in the X+ direction, the magnetic sleeve 12, the working air gap 17 in the X- direction, the stator magnetic pole 1211 in the X- direction, the stator yoke 1212 and returns to the stator magnetic pole 1211 in the X+ direction. The bias magnetic flux and the control magnetic flux are superimposed, and the bias magnetic flux and the control magnetic flux are subtracted in the working air gap 7 in the X+ direction, while the bias magnetic flux and the control magnetic flux are added in the working air gap 7 in the X- direction, thereby forming a magnetic attraction force on the rotor shaft 11 toward the X- direction, attracting the rotor shaft 11 to move from the X+ direction to the X- direction until the rotor shaft 11 is stably suspended to the center position.

[0087] Specifically, Fig.10 The axial passive control magnetic circuit generated by permanent magnet ring one, permanent magnet ring two and permanent magnet ring three is shown, which passes through permanent magnet ring one 4, axial air gap 9, permanent magnet ring three 6, magnetic conductive sleeve 12, permanent magnet ring two 5, axial air gap 9 and returns to permanent magnet ring one 4 in sequence, forming a closed loop. Fig.11The working principle of realizing axial suspension through axial passive control magnetic circuit is demonstrated. If the rotor shaft 11 is disturbed in the Z direction, so that the rotor shaft 11 deviates in the Z+ direction, the permanent magnet ring 1 4 provides magnetic attraction in the Z- direction to the permanent magnet ring 2 5 and the permanent magnet ring 3 6; if the rotor shaft 11 is disturbed in the Z direction, so that the rotor shaft 11 deviates in the Z- direction, the permanent magnet ring 1 4 provides magnetic attraction in the Z+ direction to the permanent magnet ring 2 5 and the permanent magnet ring 3 6; if the rotor shaft 11 is tilted, the permanent magnet ring 1 4 can also apply a tilt correction force to the permanent magnet ring 2 5 and the permanent magnet ring 3 6. It should be noted that the axial passive control magnetic circuit part cannot realize active adjustment.

[0088] Specifically, in order to realize active axial adjustment of the rotor shaft 11, the two ends of the magnetic sleeve 12 are designed to be tapered, so that the magnetic attraction of the stator pole 1 211 and the stator pole 2 241 to the rotor assembly 1 has both radial and axial components, and the axial component can be used to actively adjust and control the axial direction, that is, to realize active damping. If the rotor shaft 11 is disturbed in the Z direction, so that the rotor shaft 11 deviates in the Z+ direction, see Fig.11 (a) shows the state, when the radial coil 3 in the Z-direction is energized, Fig.12 (a) corresponds to Fig.11 (a) The control magnetic flux in the state, the dotted arrow indicates the axial component of the magnetic field at the conical magnetic pole; the bias magnetic flux and the control magnetic flux are superimposed to form a magnetic attraction in the Z- direction, attracting the rotor to move from the Z+ direction to the Z- direction until the rotor is stably suspended in the center position. On the contrary, if the rotor shaft 11 is disturbed in the Z direction, causing the rotor shaft 11 to deviate in the Z- direction, see Fig.11 (b) indicates the state of Fig.12 (b) corresponds to Fig.11 (b) The controlled magnetic flux, the dotted arrow is the axial component of the magnetic field at the conical magnetic pole, at which a magnetic attraction force is formed in the Z+ direction.

[0089] In some embodiments, the axial lengths of the stator magnetic ring 22, the permanent magnet ring 14 and the stator magnetic ring 23 are individually adjustable but the sum of their lengths remains unchanged, so that the magnetic field strength at both ends of the permanent magnet ring 14 can be adjusted by changing the axial length of the permanent magnet ring 14.

[0090] By replacing the permanent magnet ring 1 4 with different lengths, the magnetic field strength at its two ends is adjusted, thereby achieving the adjustment of the size of the magnetic attraction between the two ends of the permanent magnet ring 1 4 and the permanent magnet ring 2 5 and the permanent magnet ring 3 6, and the intensity of the bias magnetic field in the working air gap 1 7 and the working air gap 2 8, thereby achieving the stiffness adjustment of the radial and axial magnetic bearings.

[0091] In some embodiments, permanent magnet ring 2 5 and permanent magnet ring 3 6 are detachably mounted in the middle of magnetic conductive sleeve 12 , and an axial air gap 9 is formed between the outer peripheral wall of permanent magnet ring 2 5 and permanent magnet ring 3 6 and the inner peripheral wall of permanent magnet ring 1 4 .

[0092] In some embodiments, the radial lengths of permanent magnet ring 2 5 and permanent magnet ring 3 6 are adjustable, so as to adjust the magnetic field strength on the outer peripheral side of permanent magnet ring 2 5 and permanent magnet ring 3 6 by changing the radial lengths of permanent magnet ring 2 5 and permanent magnet ring 3 6 .

[0093] By replacing permanent magnet ring 2 5 and permanent magnet ring 3 6 of different radial lengths, the magnetic attraction force at both ends of permanent magnet ring 2 5, permanent magnet ring 3 6 and permanent magnet ring 1 4 can be adjusted, thereby achieving stiffness adjustment of the radial-axial magnetic bearing system.

[0094] In some embodiments, an annular mounting groove 1 and an annular mounting groove 2 are circumferentially opened between the outer circumferential wall of the magnetic sleeve 12 corresponding to the active surface 1 121 and the active surface 2 122; the annular mounting groove 1 and the annular mounting groove 2 are axially spaced apart from each other along the magnetic sleeve 12; the inner circumferential wall of the permanent magnet ring 2 5 can be removably embedded in the annular mounting groove 1; the inner circumferential wall of the permanent magnet ring 3 6 can be removably embedded in the annular mounting groove 2.

[0095] The beneficial effect of the above technical solution is that the inner circumferential walls of the permanent magnetic ring 2 5 and the permanent magnetic ring 3 6 can be detachably embedded in the outer circumferential wall of the magnetic conductive sleeve 12, which can increase the stability of the structure and facilitate the magnetic circuit connection between the permanent magnetic ring 2 5, the permanent magnetic ring 3 6 and the magnetic conductive sleeve 12, thereby reducing leakage magnetic flux.

[0096] In some embodiments, the first active surface 121 and the second active surface 122 have the same structure and are both in the shape of a truncated cone coaxially disposed with the rotor shaft 11 .

[0097] Another embodiment of the present invention provides a design method for a high-reliability, low-power radial-axial magnetic bearing. The specific arrangement is as follows:

[0098] Step 1: Determine the mechanical parameter design input. Determine the maximum operating speed n of the rotor according to the actual working conditions and application scenarios. max , the modal frequency of the rotor is f m , the outer diameter of the rotor r ro , the mass of the rotor m.

[0099] Step 2: Determine basic electromagnetic design input (material selection, magnetic permeability testing).

[0100] Determine the working air gap length g of the magnetic bearing according to the mechanical assembly and actual control accuracy. Determine the magnetic material according to the mechanical strength and working environment requirements, and test the magnetic permeability of the material. (changes in real time with magnetic field strength) and saturation magnetic flux density B max , bias flux density Select the permanent magnet material (such as NdFeB or SmCo) according to the bias flux density and working environment. Determine the radial bias force F required for the rotor according to the mass of the rotor and the actual application conditions. bias , Dynamic bearing capacity Fcon and the maximum load capacity F max . Determine the current stiffness K according to the actual dynamic performance i Feasible range and displacement stiffness K h Feasible scope.

[0101] Step 3: Construct a reluctance network for radial bias flux, calculate magnetic potential, reluctance, and flux, and allocate the dimensions of each component of the radial magnetic bearing.

[0102] Magnetomotive force F of axial permanent magnet m =H r l r =B r μ 0 μ r l r , H c is the coercive force of the permanent magnet, l r is the axial length of the permanent magnet, μ r is the relative magnetic permeability of the axial permanent magnet, B r is the remanent magnetism of the axial permanent magnet.

[0103] Air gap reluctance at the pole A g is the effective cross-sectional area of ​​the magnetic pole. If there is a disturbance in the X+ direction, causing the rotor to move x toward X+, the X+ air gap reluctance X-air gap reluctance The same applies to the Y and Z directions. The magnetic resistance of the stator and rotor follows the structure. Fig.13 Calculation rules,

[0104]

[0105] The magnetic pressure drop matrix of each branch is RΦ=U, where R is the magnetic resistance matrix, Φ is the magnetic flux matrix, and U is the branch magnetic pressure drop.

[0106] The flux matrix of each node is AΦ=0, where A is the node association matrix. When the branch flux flows into the node, it takes -1, and when the branch flux flows out of the node, it takes 1.

[0107] Step 4: Construct a magnetic resistance network for radial flux control and determine the coil parameters.

[0108] According to the bias flux density in step 2 being equal to the maximum control flux density and the magnetic pole size in step 3, determine the coil's ampere-turns NI. Determine the inductance value based on the controller parameters Equivalent air gap The number of coil turns N is determined according to the inductance value. The wire diameter and the maximum input current I are determined according to the current density limit to ensure that the coil can be placed in the magnetic pole slot without interfering with the core size.

[0109] Step 5: Calculate radial current stiffness and displacement stiffness.

[0110] Combine the radial bias reluctance network and the radial control reluctance network to calculate the radial current stiffness and displacement stiffness. Current stiffness In the final control system, the equivalent stiffness K e =k i A(ω)-k x and equivalent damping C e =k i B(ω) / ω must always satisfy K e >0,C e > 0. Where A(ω) and B(ω) are determined by the controller used, and are the real and imaginary parts of the equivalent transfer function of the system including the controller. ω is the operating speed of the rotor assembly.

[0111] Step 6: Determine the axial passive force F z .

[0112] The axial length limit of the axial permanent magnet is determined according to the overall axial length used in the radial direction. Under the condition of axial length limit, the specific size of the axial permanent magnet is designed. A eff The effective area of ​​the overlap between the two magnets, H r is the magnetization intensity of permanent magnet ring 2 5 and permanent magnet ring 3 6, H c is the magnetization intensity of permanent magnet ring 4. Already given in the previous text.

[0113] Step 7: Calculate the required axial damping.

[0114] Calculation of the minimum damping coefficient required for an axial passive magnetic bearing λ d is the logarithmic attenuation coefficient required by the dynamic system, which is always between 0.7 and 1, n is the critical speed of the rigid body causing axial vibration, and m is the rotor mass. e >C d .

[0115] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0116] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A high-reliability, low-power consumption radial-axial magnetic bearing, characterized in that: include: A rotor assembly (1), the rotor assembly (1) comprising a rotor shaft (11) and a magnetically conductive sleeve (12) coaxially sleeved and fixed on the rotor shaft (11); an outer peripheral wall surface at one end of the magnetically conductive sleeve (12) is a conical active surface 1 (121), and an outer peripheral wall surface at the other end is a conical active surface 2 (122); The stator component (2) is annular and movably sleeved on the outer periphery of the rotor component (1); one end of the stator component (2) has a plurality of stator poles (211) evenly arranged around the outer periphery of the first action surface (121); the other end has a plurality of stator poles (241) evenly arranged around the outer periphery of the second action surface (122); the end surfaces of the plurality of stator poles (211) close to the first action surface (121) are in contact with the action surface. an active surface three (2111) which is opposite to the active surface one (121) and has a matching contour; a working air gap one (7) is formed between the active surface three (2111) and the active surface one (121); an end surface of a plurality of stator magnetic poles two (241) close to the active surface two (122) is an active surface four (2411) which is opposite to the active surface one (121) and has a matching contour; a working air gap two (8) is formed between the active surface four (2411) and the active surface two (122); Radial coil (3); the radial coil (3) is sleeved on the stator magnetic pole 1 (211) and the stator magnetic pole 2 (241); Permanent magnet ring one (4), permanent magnet ring two (5) and permanent magnet ring three (6); the permanent magnet ring one (4) is axially magnetized and coaxially embedded in the middle of the stator assembly (2); the permanent magnet ring two (5) and the permanent magnet ring three (6) are both radially magnetized and sleeved on the outer periphery of the magnetic conductive sleeve (12) and located in the annular hole of the stator assembly (2); the outer periphery of the permanent magnet ring two (5) is opposite to the opposite magnetic pole of one end of the permanent magnet ring one (4); the outer periphery of the permanent magnet ring three (6) is opposite to the opposite magnetic pole of the other end of the permanent magnet ring one (4).

2. According to claim 1, a high-reliability, low-power consumption radial-axial magnetic bearing is characterized in that: The stator assembly (2) comprises a stator core 1 (21), a stator magnetic ring 1 (22), a stator magnetic ring 2 (23) and a stator core 2 (24); the stator core 1 (21), the stator magnetic ring 1 (22), the permanent magnet ring 1 (4), the stator magnetic ring 2 (23) and the stator core 2 (24) are all annular and are coaxially stacked in sequence to form an annular stator structure; The stator core 1 (21) has a plurality of stator poles 1 (211) uniformly arranged around the periphery of the active surface 1 (121); the stator core 2 (24) has a plurality of stator poles 2 (241) uniformly arranged around the periphery of the active surface 2 (122).

3. According to claim 2, a high-reliability, low-power consumption radial-axial magnetic bearing is characterized in that: The rotor shaft (11), the stator magnetic conductive ring 1 (22) and the stator magnetic conductive ring 2 (23) are all made of soft magnetic materials; the magnetic conductive sleeve (12), the stator iron core 1 (21) and the stator iron core 2 (24) are all laminated structures.

4. According to claim 2, a high-reliability, low-power consumption radial-axial magnetic bearing is characterized in that: The stator core (21) comprises an annular stator yoke (212) and three or more stator poles (211) uniformly distributed along the inner wall of the stator yoke (212) in the circumferential direction; The stator core 2 (24) comprises an annular stator yoke 2 (242) and more than three stator poles 2 (241) uniformly distributed along the inner circumferential wall of the stator yoke 2 (242); The stator magnetic yoke 1 (212), the stator magnetic conductive ring 1 (22), the permanent magnetic ring 1 (4), the stator magnetic conductive ring 2 (23) and the stator magnetic yoke 2 (242) are coaxially detachably stacked in sequence.

5. A high-reliability, low-power consumption radial-axial magnetic bearing according to claim 4, characterized in that: The axial lengths of the stator magnetic ring 1 (22), the permanent magnet ring 1 (4) and the stator magnetic ring 2 (23) are all adjustable individually, but the sum of the three lengths remains unchanged, so that the magnetic field strength at both ends of the permanent magnet ring 1 (4) can be adjusted by changing the axial length of the permanent magnet ring 1 (4).

6. A high-reliability, low-power consumption radial-axial magnetic bearing according to claim 1, characterized in that: The permanent magnetic ring 2 (5) and the permanent magnetic ring 3 (6) are detachably mounted on the middle part of the magnetic conductive sleeve (12), and an axial air gap (9) is formed between the outer peripheral wall surface of the permanent magnetic ring 2 (5) and the permanent magnetic ring 3 (6) and the inner peripheral wall surface of the permanent magnetic ring 1 (4).

7. A high-reliability, low-power consumption radial-axial magnetic bearing according to claim 6, characterized in that: The radial lengths of the permanent magnet ring 2 (5) and the permanent magnet ring 3 (6) are adjustable, so as to adjust the magnetic field strength on the outer peripheral side of the permanent magnet ring 2 (5) and the permanent magnet ring 3 (6) by changing the radial lengths of the permanent magnet ring 2 (5) and the permanent magnet ring 3 (6).

8. A high-reliability, low-power consumption radial-axial magnetic bearing according to claim 6, characterized in that: An annular mounting groove 1 and an annular mounting groove 2 are provided along the circumferential direction between the outer circumferential wall of the magnetic conductive sleeve (12) corresponding to the first active surface (121) and the second active surface (122); the annular mounting groove 1 and the annular mounting groove 2 are arranged axially with intervals along the magnetic conductive sleeve (12); the inner circumferential wall of the permanent magnetic ring 2 (5) can be detachably embedded in the annular mounting groove 1; the inner circumferential wall of the permanent magnetic ring 3 (6) can be detachably embedded in the annular mounting groove 2.

9. A high-reliability, low-power consumption radial-axial magnetic bearing according to claim 1, characterized in that: The first action surface (121) and the second action surface (122) have the same structure and are both in the shape of a truncated cone coaxially arranged with the rotor shaft (11).

10. A design method for a high-reliability, low-power radial-axial magnetic bearing according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Determine the mechanical parameter design input; determine the maximum operating speed of the rotor, the modal frequency of the rotor, the outer diameter of the rotor, and the mass of the rotor according to the actual working conditions and application scenarios; Step 2: Determine the basic electromagnetic design input; determine the working air gap length of the magnetic bearing according to the mechanical assembly and actual control accuracy; determine the magnetic material according to the mechanical strength and working environment requirements, and test the material's magnetic permeability, saturation flux density and bias flux density; select the permanent magnet material according to the bias flux density and working environment; determine the radial bias force, dynamic bearing capacity and maximum bearing capacity required for the rotor according to the rotor mass and actual application conditions; determine the feasible range of current stiffness and the feasible range of displacement stiffness according to the actual dynamic performance; Step 3: Construct a reluctance network for radial bias flux, calculate magnetic potential, reluctance, and flux, and allocate the dimensions of each component of the radial magnetic bearing; Step 4: Construct a magnetic resistance network for radial flux control and determine coil parameters; Step 5: Calculate radial current stiffness and displacement stiffness; Step 6: Determine the axial passive force; Step 7: Calculate the required axial damping.

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