An octapole five-degree-of-freedom hybrid magnetic suspension bearing and a control method thereof

Abstract

The present application provides an octapole five-degree-of-freedom hybrid magnetic bearing and a control method thereof. The magnetic field generated by a permanent magnet is used to replace the static bias magnetic field generated by an electromagnet in an active magnetic bearing, thereby greatly reducing power loss, reducing the ampere-turns of the electromagnet, reducing the volume of the magnetic bearing, and improving the efficiency of the magnetic bearing. The axial and radial control magnetic fluxes do not pass through the permanent magnet, and a low-power consumption permanent magnet biased five-degree-of-freedom integrated magnetic bearing with greater axial and radial suspension force can be generated.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic suspension bearings, and in particular to an octapole five-degree-of-freedom hybrid magnetic suspension bearing. Background Art

[0002] With the development of modern industry, high speed has become the main direction of motor development. In equipment with a quiet working environment, there are higher requirements for high-speed motors, that is, the motor should reduce wear and noise caused by lubrication during operation. Magnetic bearings achieve non-contact between the static and rotating structures of the bearing, thereby eliminating the shortcomings of traditional bearings. Replacing the traditional mechanical bearings in the motor with magnetic bearings creates conditions for high-speed rotation of the motor rotor, greatly reducing the mechanical power loss generated by the motor during rotation, improving the efficiency of high-speed motors, and making high-speed motors more resistant to harsh operating environments such as noise and oil pollution.

[0003] According to the principle of generating suspension force, magnetic bearings can be divided into active magnetic bearings (AMBs), passive magnetic bearings (PMBs) and hybrid magnetic bearings (HMBs). Active magnetic bearings are a type of bearing that uses electromagnetic coils on the stator to generate electromagnetic force to stably suspend the rotor in space; passive magnetic bearings are magnetic bearings with permanent magnets. Unlike AMBs and PMBs, HMB hybrid magnetic bearings use the magnetic field generated by permanent magnets to replace the static bias magnetic field generated by the electromagnets in active magnetic bearings, which greatly reduces power loss, reduces the ampere-turns of the electromagnets, reduces the size of the magnetic bearings, and improves the efficiency of the magnetic bearings. In addition, HMBs can also be divided into 1-DOF axial HMBs, 2-DOF radial HMBs, and 3-DOF radial and axial HMBs. In order to achieve stable suspension of high-speed rotors, multiple HMB units are required to form a five-degree-of-freedom (5-DOF) magnetic suspension system. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides an octapole five-degree-of-freedom hybrid magnetic suspension bearing that can achieve stable suspension of high-speed rotors and greatly reduce power loss.

[0005] An octapole five-degree-of-freedom hybrid magnetic suspension bearing comprises a rotating shaft, a rotating shaft thrust plate is arranged in the middle of the rotating shaft, rotors are sleeved at both ends of the rotating shaft, a stator assembly is sleeved on the circumference of the rotor, and the stator assembly comprises a housing sleeved on the rotating shaft;

[0006] A radial bearing stator assembly, which is located at both ends of the housing and sleeved on the rotor, is used to generate a controllable magnetic radial attraction force, provide a radial magnetic field for the rotor to adjust the radial position of the rotor;

[0007] An axial bearing stator assembly, comprising a left axial stator ring and a right axial stator ring, which are respectively sleeved on both ends of the shaft thrust plate and located in the housing, and are used to generate a controllable magnetic axial suction force, provide an axial magnetic field for the rotor to adjust the radial position of the rotor;

[0008] The permanent magnet ring group is arranged between the radial bearing stator assembly and the axial bearing stator assembly to provide a symmetrical bias magnetic circuit for the bearing.

[0009] As described above, in the octapole five-degree-of-freedom hybrid magnetic levitation bearing, the radial bearing stator assembly includes an annular sleeve, the inner wall of the annular sleeve is provided with a plurality of flanges protruding toward the rotor, and control coils are wound around the plurality of flanges to generate controllable magnetic radial suction to stably suspend the rotating shaft without contact.

[0010] As described above, in the octapole five-degree-of-freedom hybrid magnetic bearing, eight flanges are provided and evenly distributed along the circumference on the inner wall of the annular sleeve, and the eight flanges are all wound with the control coil.

[0011] As described above, in the octapole five-degree-of-freedom hybrid magnetic suspension bearing, a placement groove for placing the axial bearing stator assembly is provided in the housing, and the placement groove is located on the peripheral side of the shaft thrust plate.

[0012] In the octapole five-degree-of-freedom hybrid magnetic bearing as described above, the permanent magnet ring group includes a left permanent magnet ring located on the left side of the shell and a right permanent magnet ring located on the right side of the shell, and the opposite ends of the left permanent magnet ring and the right permanent magnet ring are of the same polarity.

[0013] In the above-mentioned octapole five-degree-of-freedom hybrid magnetic suspension bearing, the material of the permanent magnet ring group is NdFe35.

[0014] As described above, in the eight-pole five-degree-of-freedom hybrid magnetic bearing, the magnetic pole distribution of the eight flanges is NNSSNNSS.

[0015] A control method for a magnetic suspension bearing, using the octapole five-degree-of-freedom hybrid magnetic suspension bearing as described in any one of the above items, comprises the following steps:

[0016] Obtaining the minimum distance da between the shaft thrust plate and the left axial stator ring;

[0017] Obtaining the minimum distance db between the shaft thrust plate and the right axial stator ring;

[0018] According to the size relationship between the minimum spacing da and the minimum spacing db, the current direction and / or current size in the axial bearing stator assembly is adjusted to make the shaft thrust plate move axially toward the larger value of the minimum spacing da and the minimum spacing db.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present application provides an octapole five-degree-of-freedom hybrid magnetic bearing, which replaces the static bias magnetic field generated by the electromagnet in the active magnetic bearing by utilizing the magnetic field generated by the permanent magnet, thereby greatly reducing the power loss, reducing the ampere-turns of the electromagnet, reducing the volume of the magnetic bearing, and improving the efficiency of the magnetic bearing. The axial and radial control magnetic fluxes do not pass through the permanent magnet, and a low-power permanent magnet biased five-degree-of-freedom integrated magnetic bearing with greater axial and radial suspension force can be generated. Since the axial bearing stator assembly is provided with two left and right groups, the left and right groups of axial bearing stator assemblies are respectively arranged on the left and right sides of the thrust plate of the rotating shaft, and two groups of radial magnetic bearing cores are also provided on both sides.

[0021] The present application provides a control method for a magnetic levitation bearing, in which a left permanent magnet ring and a right permanent magnet ring are respectively located between an axial stator ring and two radial stators, so that the axial control magnetic circuit and the radial control magnetic circuit can be isolated, and the coupling between the radial control magnetic circuit and the axial control magnetic circuit can be effectively reduced, thereby further reducing the control difficulty of the magnetic bearing, that is, the control logic is simplified, and the efficiency of the magnetic levitation bearing is improved. The axial and radial control magnetic fluxes do not pass through the permanent magnets, and a low-power permanent magnet biased five-degree-of-freedom integrated magnetic bearing with greater axial and radial suspension force can be generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.

[0023] Figure 1 It is a three-dimensional schematic diagram of an assembly of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0024] Figure 2 This is an exploded view of an octapole five-degree-of-freedom hybrid magnetic bearing of the present application;

[0025] Figure 3 This is a cross-sectional view taken along line AA of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0026] Figure 4 This is a cross-sectional view taken along the BB section of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0027] Figure 5 This is a cross-sectional magnetic circuit diagram at BB of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0028] Figure 6 This is a cross-sectional magnetic pole distribution diagram at AA of an eight-pole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0029] Figure 7 This is an axial superimposed magnetic flux diagram of the cross section at BB of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0030] Figure 8 This is a cross-sectional axial superimposed magnetic field intensity diagram at BB of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application;

[0031] Fig. 9 This is a radial superimposed magnetic field intensity diagram of the cross section at AA of an octapole five-degree-of-freedom hybrid magnetic suspension bearing of the present application. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings:

[0033] like Figure 1-9 As shown, an octapole five-degree-of-freedom hybrid magnetic suspension bearing includes a rotating shaft 1, a rotating shaft thrust plate 2, a rotor 3, a stator assembly 4, a housing 40, a radial bearing stator assembly 41, an axial bearing stator assembly 42, a left axial stator ring 421, a right axial stator ring 422, a permanent magnet ring group 5, a circular ring kit 410, a flange 411, a control coil 412, a placement groove 401, a left permanent magnet ring 51, and a right permanent magnet ring 52.

[0034] An octapole five-degree-of-freedom hybrid magnetic suspension bearing comprises a rotating shaft 1, a rotating shaft thrust plate 2 is arranged in the middle of the rotating shaft 1, rotors 3 are sleeved at both ends of the rotating shaft 1, a stator assembly 4 is sleeved on the circumference of the rotor 3, and the stator assembly 4 comprises a housing 40 sleeved on the rotating shaft 1;

[0035] A radial bearing stator assembly 41, which is located at both ends of the housing 40 and is sleeved on the rotor 3, and is used to generate a controllable magnetic radial attraction force, provide a radial magnetic field for the rotor 3 to adjust the radial position of the rotor 3;

[0036] An axial bearing stator assembly 42, comprising a left axial stator ring 421 and a right axial stator ring 422, which are respectively sleeved on both ends of the shaft thrust plate 2 and located in the housing 40, and are used to generate a controllable magnetic axial suction force, provide an axial magnetic field for the rotor 3 to adjust the radial position of the rotor 3;

[0037] The permanent magnet ring group 5 is arranged between the radial bearing stator assembly 41 and the axial bearing stator assembly 42, and provides a symmetrical bias magnetic circuit for the bearing. By utilizing the magnetic field generated by the permanent magnet, the static bias magnetic field generated by the electromagnet in the active magnetic suspension bearing is replaced, so that the power loss is greatly reduced, the ampere-turns of the electromagnet are reduced, the volume of the magnetic suspension bearing is reduced, and the efficiency of the magnetic suspension bearing is improved. The axial and radial control magnetic fluxes do not pass through the permanent magnet, and a low-power permanent magnet biased five-degree-of-freedom integrated magnetic bearing with greater axial and radial suspension force can be generated. Since its axial bearing stator assembly is provided with two left and right groups, the left and right groups of axial bearing stator assemblies are respectively arranged on the left and right sides of the thrust plate of the rotating shaft, and two groups of radial magnetic bearing cores are also provided on both sides.

[0038] Preferably, the radial bearing stator assembly 41 includes an annular sleeve 410, and a plurality of flanges 411 are protruded from the inner wall of the annular sleeve 410 toward the rotor 3, and a control coil 412 is wound around each of the plurality of flanges 411 to generate a controllable magnetic radial suction force to stably suspend the rotating shaft 1 in a non-contact manner.

[0039] Preferably, eight flanges 411 are provided and evenly distributed along the circumference on the inner wall of the annular sleeve 410 , and the control coil 412 is wound around each of the eight flanges 411 .

[0040] Preferably, a placement groove 401 for placing the axial bearing stator assembly 42 is provided in the housing 40 , and the placement groove 401 is located on the peripheral side of the rotating shaft thrust plate 2 .

[0041] Preferably, the permanent magnet ring group 5 includes a left permanent magnet ring 51 located on the left side of the shell 40 and a right permanent magnet ring 52 located on the right side of the shell 40 , and the opposite ends of the left permanent magnet ring 51 and the right permanent magnet ring 52 have the same polarity.

[0042] Preferably, the material of the permanent magnet ring group 5 is NdFe35.

[0043] Preferably, the magnetic pole distribution of the eight flanges 411 is NNSSNNSS, and the radial magnetic bearing is divided into homopolarity and heteropolarity according to the distribution direction of the magnetic poles. The magnetic bearing with heteropolar distribution has a small circumferential dimension, a compact structure, and full utilization of the circumferential space. The distribution of the magnetic poles of the heteropolar structure is divided into NSSN and NSNS. When the rotor rotates, the direction of the magnetic lines of force of the NSSN distribution changes less times than that of the NSNS in one cycle, and the loss is small. The winding scheme stipulates the winding direction of each pole coil and the connection method between each coil. The designed radial bearing structure is an electromagnetic decoupling topology structure, and the driving mode is a differential drive mode of relative two poles. Two adjacent poles constitute a flux loop.

[0044] More preferably, for the bearing capacity of the magnetic suspension bearing, when the structural form is determined, the area of ​​the magnetic pole increases, and the area of ​​the coil cavity must decrease. It is necessary to allocate the proportion of the magnetic pole and the winding volume according to the bearing requirements and use conditions, which is specifically expressed as the cross-sectional area A of the magnetic pole and the area A of the stator coil cavity. cu According to the mathematical model, the relationship between the bearing capacity of the octupole radial magnetic bearing and the two areas is:

[0045] Then the magnetic pole area A and the coil cavity area A cu can be expressed by the magnetic pole width b as

[0046]

[0047] According to the above formula, we can get the law of change of electromagnetic force with the magnetic pole width b.

[0048] More preferably, the eddy current displacement sensor probe passes a high-frequency alternating current through a hollow coil enclosed in a shell, and the electromagnetic coil unit induces eddy currents on the conductive object being measured and absorbs energy from the oscillation circuit. The coil inductance varies with the distance between the probe and the surface of the object being measured, and the external circuit in the sensor preamplifier converts this change into an output voltage signal. Because of the influence of the magnetic field change of the magnetic bearing, a shielded sensor must be used. Secondly, current ripple can also be used to position the rotor, but this method has poor reliability and pulses may be lost when the relay is switched, which can be compensated by software. The advantage is that the price is low.

[0049] The force exerted by the electromagnet on the suspended object is generated on the boundary of objects with different magnetic permeabilities, that is, on the surface of the suspended object. The change of magnetic field energy in the air gap generates a force on the surface of the object. The force is a function of the displacement of the suspended object. For small displacement ds, the magnetic flux remains constant. When the air gap s increases, the displacement d s Increase, air gap volume V a Increase, the magnetic field energy storage W of the air gap a Change dW a Where W a for:

[0050]

[0051] This part of energy is converted into mechanical energy for the suspended object. Therefore, according to the virtual displacement principle, the electromagnetic force on the surface of the object is the partial conduction of the magnetic field energy to the air gap s, and the electromagnetic force is

[0052]

[0053] From the perspective of supporting capacity, the air gap should be reduced as much as possible. First, the air gap can reduce the overall size of the bearing; second, the smaller the air gap, the greater the electromagnetic force of the bearing for the same bearing size; the larger the air gap, the larger the range of rotor movement. Generally, when the rotor diameter is less than 100mm, the air gap is 0.3-0.6mm; when the rotor diameter is in the range of 100-1000mm, the air gap is 0.6-1mm. In this application, the rotor diameter is 100mm, so the air gap is selected as 0.5mm.

[0054] Equivalent magnetic circuit: The bias flux starts from the N pole of the permanent magnet and returns to the S pole, forming a closed path along the radial and axial air gaps. The control flux is generated by the axial and radial bearing stator assemblies through the axial and radial air gaps to form a closed loop. In addition, the left and right bias fluxes and the left and right radial control fluxes are independent of each other.

[0055] If the rotor is located at the center of the stator, the rotor will be subjected to the magnetic balance of the bias flux. Once an external force acts on the rotor, the rotor deviates from the center of the stator, and the displacement sensor detects the change and transmits these signals to the controller. The controller then adjusts the winding current to generate a control flux, which is superimposed with the bias flux to generate a five-degree-of-freedom suspension force, ultimately pulling the rotor back to the center of the stator. The shaft displacement data monitored by the displacement sensor is transmitted to the control unit so that the control unit controls the current of the axial bearing stator assembly and the radial bearing stator assembly respectively. The axial magnetic lines of force pass through the two bearing stators and the left and right axial air gaps to form a closed magnetic circuit. The generated axial force acts on the axial thrust plate, thereby adjusting the axial suspension force, overcoming external disturbances or loads, and achieving stable suspension of the shaft, that is, achieving stable suspension of the rotor;

[0056] The radial bearing magnetic lines of force pass through the radial bearing stator, the radial bearing rotor core, and the radial air gap between the radial bearing stator and the radial bearing rotor core to form a closed magnetic circuit. The generated radial force acts on the radial bearing rotor core to adjust the radial suspension force, overcome external disturbances or loads, and achieve stable suspension of the shaft, that is, stable suspension of the rotor.

[0057] A control method for a magnetic suspension bearing, using the octapole five-degree-of-freedom hybrid magnetic suspension bearing as described in any one of the above items, comprises the following steps:

[0058] Obtaining the minimum distance da between the shaft thrust plate 2 and the left axial stator ring 421;

[0059] Obtaining the minimum distance db between the shaft thrust plate 2 and the right axial stator ring 422;

[0060] According to the size relationship between the minimum spacing da and the minimum spacing db, the current direction and / or current size in the axial bearing stator assembly 42 is adjusted to make the shaft thrust plate 2 move axially toward the larger value of the minimum spacing da and the minimum spacing db.

[0061] When da>db, the current direction in the axial bearing stator assembly is the first current direction so that the control magnetic circuit generated by the axial bearing stator assembly is superimposed in the same direction with the permanent magnetic bias magnetic circuit generated by the left permanent magnet ring and is reduced in the opposite direction with the permanent magnetic bias magnetic circuit generated by the right permanent magnet ring. The current in the axial bearing stator assembly should be controlled to be smaller and smaller.

[0062] When da<db, the current direction in the axial bearing stator assembly is the second current direction so that the control magnetic circuit generated by the axial bearing stator assembly and the permanent magnetic bias magnetic circuit generated by the left permanent magnet ring are reversely reduced and superimposed in the same direction with the permanent magnetic bias magnetic circuit generated by the right permanent magnet ring, thereby controlling the current size in the axial bearing stator assembly to become smaller and smaller, and the first direction is opposite to the second direction.

[0063] When da=db, the current direction or current magnitude in the axial bearing stator assembly is maintained unchanged.

[0064] By only arranging a group of axial bearing stator assemblies coaxially arranged with the shaft thrust plate in the interval, the directions of the permanent magnet bias magnetic circuit and the axial control magnetic circuit can be used to cancel or superimpose the magnetic flux, so that the axial bearing stator assembly can adjust and control the axial position of the shaft thrust plate. The control logic is simpler, and therefore has a smaller axial space requirement. The axial length of the five-degree-of-freedom magnetic bearing can be designed to be smaller, thereby shortening the corresponding shaft length and increasing the shaft speed. More importantly, the left permanent magnet ring and the right permanent magnet ring are respectively located between the axial stator ring and the two radial stators, which can isolate the axial control magnetic circuit from the radial control magnetic circuit, effectively reduce the coupling between the radial control magnetic circuit and the axial control magnetic circuit, and further reduce the control difficulty of the magnetic bearing, that is, the control logic is simplified.

[0065] More preferably, the present application also provides a radial control method: similar to the axial control method, since the magnetic pole distribution is NNSSNNSS, it is actually equivalent to a quadrupole. Taking the left-side radial control as an example, the spacings between the radial coil and the radial rotor are dc, dd, de, and df, respectively. The clockwise direction corresponds to the air gap distance between the large quadrupole and the rotor, and the spacing dc is the upper spacing.

[0066] When dc > de, the control magnetic circuit generated by the control current in the corresponding radial coil is superposed in the same direction as the permanent magnet bias magnetic circuit generated by the upper permanent magnet ring and is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the lower permanent magnet ring. The magnitude of the current in the dc-side radial bearing stator assembly should be controlled to increase more and more, and the magnitude of the current in the de-side radial bearing stator assembly should be controlled to decrease more and more; when dc < de, the control method is opposite.

[0067] When dd > df, the control magnetic circuit generated by the control current in the corresponding radial coil is superposed in the same direction as the permanent magnet bias magnetic circuit generated by the permanent magnet ring on the front side of the magnetic levitation bearing and is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the permanent magnet ring on the rear side. The magnitude of the current in the dd-side radial bearing stator assembly should be controlled to increase more and more, and the magnitude of the current in the df-side radial bearing stator assembly should be controlled to decrease more and more; when dd < df, the control method is opposite.

[0068] When dc == dd == de == df, the direction or magnitude of the current in the radial bearing stator assembly is maintained unchanged.

[0069] Specifically, Figure 6 As shown, the magnetic poles adopt a heteropolar structure with the magnetic pole distribution of NNSSNNSS. When the rotor rotates, the direction of the magnetic force lines changes fewer times in a cycle than that of NSNS, and the loss is smaller. Therefore, it becomes a better choice. For the adjustment of the radial position of the rotating shaft, since its adjustment is decoupled from the axial control magnetic circuit, independent adjustment can be achieved without conflicting with the axial coil.

[0070] Specifically, Figure 5 As shown, the arrows in the figure show the radial magnetic circuit direction, the axial magnetic circuit direction, the bias magnetic circuit direction, the a bias magnetic circuit, the b radial control magnetic circuit, and the c axial control magnetic circuit. It can be seen that the left permanent magnet ring and the right permanent magnet ring are completely the same in performance, but the difference is that the magnetic poles are opposite, generating the left bias magnetic circuit and the right bias magnetic circuit respectively. They are radially symmetric about the left and right in structure, so the left and right forces are balanced above the shaft. The axial bearing stator assembly is centrosymmetric along the radial plane, so that the axial control magnetic circuit generated after the axial bearing stator assembly is energized can be symmetric about this radial plane, and the permanent magnet bias magnetic circuit of the rotating shaft thrust disk is symmetric about the left and right, further reducing the control difficulty of the magnetic bearing. The displacement of the rotating shaft and the rotor in the axial direction completely depends on the magnitude and direction of the control current in the axial coil. While the left permanent magnet ring and the right permanent magnet ring respectively provide symmetric bias magnetic circuits, they also effectively prevent the axial control magnetic circuit from flowing to the left radial control magnetic circuit and the right radial control magnetic circuit side, thereby preventing the coupling from occurring. In addition, according to the structure of the following figure, the permanent magnet bias magnetic circuit is single and the magnetic leakage is small, and the axial control magnetic circuit directly forms a loop by the stator core and the rotating shaft thrust disk.

[0071] Figure 7It is the axial superposition magnetic flux generated by the control current in the axial direction and the permanent magnet ring. In the middle of the axial rotor, the magnetic flux is the largest; in the axial direction, the magnetic flux direction points to the center of the structure, the midpoint of the rotor. Since the permanent magnet ring is axially magnetized, the bias magnetic flux generated by the N pole passes through the left stator, the left radial air gap, the left rotor, the axial iron core, the left axial air gap, the middle rotor, the right axial air gap, the right rotor, the right radial air gap, and the right stator to return to the S pole, forming an axial closed path. The magnetic density on the rotor is symmetrical, and the resultant force on the three rotors is zero. The three rotors form a closed path. The magnetic flux distribution on the rotor is symmetrical, the magnetic flux intensity is symmetrical in the radial plane, and the resultant force on the rotor is zero. It can be seen that the equivalent magnetic circuit path is closed.

[0072] Figure 8 The superimposed magnetic density diagram of the axial control current and the permanent magnet ring is shown in Figure 1. The axial coil current is set to the same direction. When the rotor does not deviate, the axial coil default current is 0A. As can be seen from Figure 1, the control flux and the bias flux overlap and increase in one direction, while the overlap decreases in the opposite direction. The resultant force points to the direction of magnetic field enhancement. If the rotor deviates to the left, the axial coil is energized, as shown below. Figure 8 As shown, the magnetic field strength on the right side pulls the rotor back to the midpoint, and determines whether the power is off based on the rotor position detected by the sensor.

[0073] Fig. 9 It is the superimposed magnetic density diagram generated by the radial control current and the permanent magnet ring. When the rotor is offset, the radial coil is judged whether it is energized according to the rotor offset detected by the sensor. The radial position of the shaft can be adjusted according to the adjustment method of the radial bearing in the prior art, because its adjustment is decoupled from the axial control magnetic circuit, so it can be adjusted independently.

[0074] Specific design process:

[0075] 1) According to the structural diagram, draw the equivalent magnetic circuit diagram and design the control flux and bias flux at each air gap;

[0076] 2) Calculate the radial suspension force formula and find the force / displacement parameters and force / current parameters;

[0077] 3) Calculate the magnetic pole area according to the radial suspension force formula;

[0078] 4) According to the air gap control flux, find the radial control winding;

[0079] 5) Further determine the rotor core radius, shaft radius, radial stator width, axial length and stator tooth height;

[0080] 6) Calculate the width and magnetization thickness of the permanent magnet;

[0081] 7) Use Maxwell software to draw a two-dimensional model and analyze it from the magnetic field line diagram, magnetic density distribution diagram, force / current relationship curve diagram, and force / displacement relationship curve diagram;

[0082] 8) When the air gap of the auxiliary bearing is determined and the passive magnetic pull generated by the permanent magnetic pole is overcome, find the ratio of the control magnetic pole area to the permanent magnetic stimulation area to obtain the maximum radial suspension force;

[0083] 9) Design experimental prototypes and conduct static suspension experiments and dynamic suspension experiments.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An octupole five-degree-of-freedom hybrid magnetic bearing, characterized in that: It includes a rotating shaft (1), a rotating shaft thrust disc (2) is provided in the middle of the rotating shaft (1), rotors (3) are sleeved at both ends of the rotating shaft (1), and a stator assembly (4) is sleeved on the circumferential side of the rotors (3), and is characterized in that: the stator assembly (4) includes a housing (40) sleeved on the rotating shaft (1); A radial bearing stator assembly (41), which is located at both ends of the housing (40) and sleeved on the rotor (3), is used to generate a controllable magnetic radial suction force to provide a radial magnetic field action for the rotor (3) to adjust the position of the rotor (3) in the radial direction; An axial bearing stator assembly (42), including a left axial stator ring (421) and a right axial stator ring (422), which are respectively sleeved at both ends of the rotating shaft thrust disc (2) and located in the housing (40), is used to generate a controllable magnetic axial suction force to provide an axial magnetic field action for the rotor (3) to adjust the position of the rotor (3) in the radial direction; A permanent magnet ring group (5), which is arranged between the radial bearing stator assembly (41) and the axial bearing stator assembly (42), provides a symmetric bias magnetic circuit for the bearing; The radial bearing stator assembly (41) includes a circular ring-shaped kit (410), and a plurality of flanges (411) protrude from the inner wall of the circular ring-shaped kit (410) towards the rotor (3), and control coils (412) are wound on the plurality of flanges (411) to generate a controllable magnetic radial suction force to stably suspend the rotating shaft (1) in a non-contact manner; There are 8 flanges (411), which are evenly distributed along the circumference on the inner wall of the circular ring-shaped kit (410), the 8 flanges (411) are all wound with the control coils (412), and the magnetic pole distribution of the 8 flanges (411) is NNSSNNSS; The magnetic pole distribution is NNSSNNSS, which is actually equivalent to a quadrupole. Taking the left radial control as an example, the distances between the radial coil and the radial rotor are dc, dd, de, and df respectively, which clockwise correspond to the air gap distances between the large quadrupole and the rotor, and the distance dc is the upper side distance, and the following steps are included: When dc>de, the control magnetic circuit generated by the control current in the corresponding radial coil is superposed in the same direction as the permanent magnet bias magnetic circuit generated by the upper permanent magnet ring and is cut in the opposite direction to the permanent magnet bias magnetic circuit generated by the lower permanent magnet ring. The current magnitude in the dc-side radial bearing stator assembly should be controlled to be larger and larger, and the current magnitude in the de-side radial bearing stator assembly should be controlled to be smaller and smaller; when dc<de, the control method is opposite; When dd>df, the control magnetic circuit generated by the control current in the corresponding radial coil is superposed in the same direction as the permanent magnet bias magnetic circuit generated by the permanent magnet ring in the front side of the magnetic suspension bearing and is cut in the opposite direction to the permanent magnet bias magnetic circuit generated by the permanent magnet ring in the rear side. The current magnitude in the dd-side radial bearing stator assembly should be controlled to be larger and larger, and the current magnitude in the df-side radial bearing stator assembly should be controlled to be smaller and smaller; when dd<df, the control method is opposite; When dc = dd = de = df, the current direction or current magnitude in the radial bearing stator assembly is maintained unchanged.

2. The octupole five-degree-of-freedom hybrid magnetic bearing according to claim 1, characterized in that: A placement groove (401) for placing the axial bearing stator assembly (42) is provided in the housing (40), and the placement groove (401) is located on the peripheral side of the rotating shaft thrust plate (2).

3. The octupole five-degree-of-freedom hybrid magnetic bearing according to claim 1, characterized in that: The permanent magnet ring group (5) comprises a left permanent magnet ring (51) located on the left side of the shell (40) and a right permanent magnet ring (52) located on the right side of the shell (40), and the opposite ends of the left permanent magnet ring (51) and the right permanent magnet ring (52) have the same polarity.

4. The octupole five-degree-of-freedom hybrid magnetic bearing according to claim 1, characterized in that: The material of the permanent magnet ring group (5) is NdFe35.

5. A control method for a magnetic bearing, characterized in that: The octapole five-degree-of-freedom hybrid magnetic bearing according to any one of claims 1 to 4 is used, comprising the following steps: Obtaining a minimum distance da between the rotating shaft thrust plate (2) and the left axial stator ring (421); Obtaining a minimum distance db between the rotating shaft thrust plate (2) and the right axial stator ring (422); According to the size relationship between the minimum spacing da and the minimum spacing db, the current direction and / or current size in the axial bearing stator assembly (42) is adjusted to enable the rotating shaft thrust plate (2) to move axially toward the side with the larger value between the minimum spacing da and the minimum spacing db.

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