CN118423364B - An octapole five-degree-of-freedom hybrid magnetic bearing and a control method thereof - Google Patents
An octapole five-degree-of-freedom hybrid magnetic bearing and a control method thereof Download PDFInfo
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- CN118423364B CN118423364B CN202410655365.1A CN202410655365A CN118423364B CN 118423364 B CN118423364 B CN 118423364B CN 202410655365 A CN202410655365 A CN 202410655365A CN 118423364 B CN118423364 B CN 118423364B
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- 238000000034 method Methods 0.000 title claims abstract description 16
- 230000002829 reductive effect Effects 0.000 claims abstract description 20
- 239000000725 suspension Substances 0.000 claims description 50
- 238000000429 assembly Methods 0.000 claims description 6
- 230000000712 assembly Effects 0.000 claims description 6
- 230000005426 magnetic field effect Effects 0.000 claims description 5
- 230000002093 peripheral effect Effects 0.000 claims 1
- 230000004907 flux Effects 0.000 abstract description 28
- 238000005339 levitation Methods 0.000 abstract description 11
- 230000003068 static effect Effects 0.000 abstract description 6
- 238000006073 displacement reaction Methods 0.000 description 10
- 238000010586 diagram Methods 0.000 description 8
- 238000004804 winding Methods 0.000 description 6
- UQMRAFJOBWOFNS-UHFFFAOYSA-N butyl 2-(2,4-dichlorophenoxy)acetate Chemical compound CCCCOC(=O)COC1=CC=C(Cl)C=C1Cl UQMRAFJOBWOFNS-UHFFFAOYSA-N 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 230000004323 axial length Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
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- 230000000670 limiting effect Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
- F16C32/0406—Magnetic bearings
- F16C32/044—Active magnetic bearings
- F16C32/0459—Details of the magnetic circuit
- F16C32/0461—Details of the magnetic circuit of stationary parts of the magnetic circuit
- F16C32/0465—Details of the magnetic circuit of stationary parts of the magnetic circuit with permanent magnets provided in the magnetic circuit of the electromagnets
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
- F16C32/0406—Magnetic bearings
- F16C32/044—Active magnetic bearings
- F16C32/0474—Active magnetic bearings for rotary movement
- F16C32/0489—Active magnetic bearings for rotary movement with active support of five degrees of freedom, e.g. two radial magnetic bearings combined with an axial bearing
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- Mechanical Engineering (AREA)
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- Electromagnetism (AREA)
- Magnetic Bearings And Hydrostatic Bearings (AREA)
Abstract
The application provides an eight-pole five-degree-of-freedom hybrid magnetic bearing and a control method thereof, wherein a magnetic field generated by a permanent magnet is utilized to replace a static bias magnetic field generated by an electromagnet in an active magnetic bearing, so that the power loss is greatly reduced, the ampere turns of the electromagnet are reduced, the volume of the magnetic bearing is reduced, the efficiency of the magnetic bearing is improved, axial and radial control magnetic fluxes do not pass through a permanent magnet, and a low-power consumption permanent magnet bias five-degree-of-freedom integrated magnetic bearing with larger axial and radial levitation force can be generated.
Description
Technical Field
The application relates to the technical field of magnetic suspension bearings, in particular to an octal five-degree-of-freedom hybrid magnetic suspension bearing.
Background
With the development of modern industry, the high speed is a main direction of motor development, and in equipment with quiet working environment, higher requirements are imposed on a high-speed motor, namely, the problems of abrasion, noise and the like caused by lubrication in the running process of the motor are reduced. The magnetic suspension bearing realizes the non-contact of the bearing static structure and the rotating structure, thereby eliminating the defects of the traditional bearing, replacing the traditional mechanical bearing in the motor with the magnetic suspension bearing creates a high-speed rotating condition for the motor rotor, greatly reduces the mechanical power loss generated in the rotating process of the motor, improves the efficiency of the high-speed motor, and enables the high-speed motor to be more resistant to severe running environments such as noise, greasy dirt and the like.
According to the generation principle of levitation force, the magnetic suspension bearings can be divided into an Active Magnetic Bearing (AMBs), a Passive Magnetic Bearing (PMBs) and a Hybrid Magnetic Bearing (HMBs), wherein the active magnetic bearing is a bearing which utilizes electromagnetic force generated by electromagnetic coils on a stator to stably suspend a rotor in space, and the passive magnetic bearing is a magnetic suspension bearing of a permanent magnet. Unlike AMBs and PMBs, the HMB hybrid magnetic bearing utilizes the magnetic field generated by the permanent magnet to replace the static bias magnetic field generated by the electromagnet in the active magnetic bearing, so that the power loss is greatly reduced, the ampere-turns of the electromagnet is reduced, the volume of the magnetic bearing is reduced, and the efficiency of the magnetic bearing is improved. In addition, HMB can be further classified into 1-DOF axial HMB, 2-DOF radial HMB, and 3-DOF radial and axial HMB. In order to achieve stable levitation of the high-speed rotor, multiple HMB units are required to form a five degree of freedom (5-DOF) magnetic levitation system.
Disclosure of Invention
The application aims to solve the technical problems and provides the octupole five-degree-of-freedom hybrid magnetic suspension bearing capable of realizing stable suspension of a high-speed rotor and greatly reducing power loss.
The mixed magnetic suspension bearing with the eight poles and five degrees of freedom comprises a rotating shaft, wherein a rotating shaft thrust disc is arranged in the middle of the rotating shaft, rotors are sleeved at two ends of the rotating shaft, stator components are sleeved at the periphery of the rotors, and each stator component comprises a shell sleeved on the rotating shaft;
Radial bearing stator components which are positioned at two ends of the shell and sleeved on the rotor and used for generating controllable magnetic radial attraction force and providing radial magnetic field effect for the rotor so as to adjust the radial position of the rotor;
The axial bearing stator assembly comprises a left axial stator ring and a right axial stator ring which are respectively sleeved at two ends of the rotating shaft thrust disc and positioned in the shell, and are used for generating controllable magnetic axial suction force and providing an axial magnetic field effect for the rotor so as to adjust the radial position of the rotor;
And the permanent magnet ring group is arranged between the radial bearing stator assembly and the axial bearing stator assembly and provides symmetrical bias magnetic circuits for the bearing.
The eight-pole five-degree-of-freedom hybrid magnetic suspension bearing comprises the radial bearing stator assembly, wherein the annular sleeve comprises a plurality of flanges, the inner wall of the annular sleeve is convexly provided with the flanges towards the direction of the rotor, and a plurality of the flanges are respectively provided with a control coil in a winding manner so as to generate controllable magnetic radial attraction force to stably suspend the rotating shaft in a non-contact manner.
The eight-pole five-degree-of-freedom hybrid magnetic suspension bearing is characterized in that 8 flanges are arranged and uniformly distributed on the inner wall of the annular sleeve along the circumference, and the 8 flanges are all wound with the control coil.
The mixed magnetic suspension bearing with the eight poles and five degrees of freedom is characterized in that a placing groove for placing the axial bearing stator assembly is formed in the shell, and the placing groove is positioned on the periphery side of the rotating shaft thrust disc.
The mixed magnetic suspension bearing with eight poles and five degrees of freedom comprises the left permanent magnet ring arranged on the left side of the shell and the right permanent magnet ring arranged on the right side of the shell, wherein the opposite ends of the left permanent magnet ring and the right permanent magnet ring are homopolar.
The mixed magnetic suspension bearing with eight poles and five degrees of freedom is characterized in that NdFe35 is adopted as the material of the permanent magnet ring group.
The mixed magnetic suspension bearing with eight poles and five degrees of freedom is characterized in that the magnetic pole distribution of 8 flanges is NNSSNNSS.
A control method of a magnetic suspension bearing, adopting the mixed magnetic suspension bearing with eight poles and five degrees of freedom, comprising the following steps:
obtaining a minimum distance da between the rotating shaft thrust disc and the left axial stator ring;
obtaining a minimum distance db between the rotating shaft thrust disc and the right axial stator ring;
and according to the magnitude relation between the minimum distance da and the minimum distance db, adjusting the current direction and/or the current magnitude in the axial bearing stator assembly so as to enable the rotating shaft thrust disc to axially move towards the side with the larger value of the minimum distance da and the minimum distance db.
Compared with the prior art, the application has the following beneficial effects:
The application provides an eight-pole five-degree-of-freedom hybrid magnetic suspension bearing, which replaces a static bias magnetic field generated by an electromagnet in an active magnetic suspension bearing by utilizing a magnetic field generated by a permanent magnet, 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, the efficiency of the magnetic suspension bearing is improved, axial and radial control magnetic fluxes do not pass through a permanent magnet, and a low-power-consumption permanent magnet bias five-degree-of-freedom integrated magnetic bearing with larger axial and radial levitation force can be generated.
According to the control method of the magnetic suspension bearing, the left permanent magnet ring and the right permanent magnet ring are respectively positioned between the axial stator ring and the two radial stators, so that the axial control magnetic circuit and the radial control magnetic circuit can be isolated, the coupling between the radial control magnetic circuit and the axial control magnetic circuit is effectively reduced, the control difficulty of the magnetic bearing is further reduced, namely, the control logic is simplified, the efficiency of the magnetic suspension bearing is improved, the axial control magnetic flux and the radial control magnetic flux do not pass through the permanent magnets, and the low-power consumption permanent magnet bias five-degree-of-freedom integrated magnetic bearing with larger axial and radial suspension force can be generated.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below.
FIG. 1 is a schematic perspective view of an octapole five degree of freedom hybrid magnetic bearing assembly of the present application;
FIG. 2 is an exploded view of an octal five degree of freedom hybrid magnetic bearing of the present application;
FIG. 3 is a cross-sectional view at A-A of an octal five degree of freedom hybrid magnetic bearing of the present application;
FIG. 4 is a cross-sectional view of an octal five degree of freedom hybrid magnetic bearing at B-B in accordance with the present application;
FIG. 5 is a schematic diagram of a magnetic circuit of a B-B section of an octapole five-degree-of-freedom hybrid magnetic bearing according to the present application;
FIG. 6 is a cross-sectional pole profile at A-A of an octapole five degree-of-freedom hybrid magnetic bearing of the present application;
FIG. 7 is a cross-sectional axial superposition flux diagram at B-B of an octapole five degree of freedom hybrid magnetic bearing of the present application;
FIG. 8 is a graph of axial superposition magnetic field strength of a section B-B of an octapole five degree-of-freedom hybrid magnetic bearing of the present application;
FIG. 9 is a graph of radial superposition magnetic field strength of a cross section at A-A of an octapole five degree of freedom hybrid magnetic bearing of the present application.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
As shown in fig. 1-9, an eight-pole five-degree-of-freedom hybrid magnetic suspension bearing comprises a rotating shaft 1, a rotating shaft thrust disc 2, a rotor 3, a stator assembly 4, a shell 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 ring-shaped sleeve 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.
The mixed magnetic suspension bearing with the eight poles and five degrees of freedom comprises a rotating shaft 1, a rotating shaft thrust disc 2 is arranged in the middle of the rotating shaft 1, a rotor 3 is sleeved at two ends of the rotating shaft 1, a stator assembly 4 is sleeved at the periphery of the rotor 3, and the stator assembly 4 comprises a shell 40 sleeved on the rotating shaft 1;
radial bearing stator assemblies 41, which are located at two ends of the housing 40 and are sleeved on the rotor 3, for generating controllable magnetic radial attraction force, and providing radial magnetic field effect for the rotor 3 to adjust the radial position of the rotor 3;
The axial bearing stator assembly 42 comprises a left axial stator ring 421 and a right axial stator ring 422, which are respectively sleeved at two ends of the rotating shaft thrust disc 2 and are positioned in the shell 40, and are used for generating controllable magnetic axial suction force to provide an axial magnetic field effect for the rotor 3 so as to adjust the radial position of the rotor 3;
the permanent magnetic ring group 5 is arranged between the radial bearing stator assembly 41 and the axial bearing stator assembly 42, provides symmetrical bias magnetic circuits for the bearing, replaces a static bias magnetic field generated by an electromagnet in an active magnetic suspension bearing by utilizing a magnetic field generated by a permanent magnet, greatly reduces power loss, reduces ampere turns of the electromagnet, reduces the volume of the magnetic suspension bearing, improves the efficiency of the magnetic suspension bearing, and can generate a low-power-consumption permanent magnetic bias five-degree-of-freedom integrated magnetic bearing with larger axial and radial suspension force without passing through permanent magnets by axial and radial control magnetic fluxes.
Preferably, the radial bearing stator assembly 41 includes a ring-shaped sleeve 410, the inner wall of the ring-shaped sleeve 410 is convexly provided with a plurality of flanges 411 towards the direction of the rotor 3, and a plurality of control coils 412 are wound on the flanges 411 to generate controllable magnetic radial attraction force to stably suspend the rotating shaft 1 in a non-contact manner.
Preferably, 8 flanges 411 are provided, and are uniformly distributed on the inner wall of the annular sleeve 410 along the circumference, and the 8 flanges 411 are all wound with the control coil 412.
Preferably, a placement groove 401 in which the axial bearing stator assembly 42 can be placed is provided in the housing 40, and the placement groove 401 is located on the circumferential side of the rotating shaft thrust disc 2.
Preferably, the permanent magnet ring set 5 includes a left permanent magnet ring 51 located at the left side of the housing 40 and a right permanent magnet ring 52 located at the right side of the housing 40, and opposite ends of the left permanent magnet ring 51 and the right permanent magnet ring 52 are in the same polarity.
Preferably, ndFe35 is used as the material of the permanent magnet ring set 5.
Preferably, the 8 magnetic poles of the flange 411 are distributed NNSSNNSS, and the radial magnetic bearings are divided into the same polarity and the different polarity according to the distribution direction of the magnetic poles. The magnetic bearing with heteropolarity distribution has small circumferential size, compact structure and fully utilized 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 magnetic force lines distributed by NSSN changes less than NSNS in one period, the loss is small, the winding scheme prescribes the winding direction of each magnetic pole coil and the connection mode between the coils, the designed radial bearing structure is an electromagnetic decoupling topological structure, the driving mode is a differential driving mode of opposite poles, and two adjacent magnetic poles form a magnetic flux loop.
More preferably, for the bearing capacity of the magnetic suspension bearing, under the condition of determining the structural form, the magnetic pole area is increased, the coil cavity area is necessarily reduced, the proportion of the magnetic pole and the winding volume is required to be distributed according to the bearing requirement and the using condition, the distribution of the magnetic pole cross section area A and the stator coil cavity area A cu is specifically shown, according to the mathematical model, the relation between the bearing capacity of the eight-pole radial magnetic suspension bearing and the two areas is deduced to be that
The pole area a and the coil cavity area a cu can be represented by the pole width b, respectively
The change rule of the electromagnetic force along with the magnetic pole width b can be obtained according to the formula.
More preferably, the eddy current displacement sensor probe passes a high frequency alternating current through an air coil enclosed in a housing, and the electromagnetic coil unit induces eddy currents on the conductive object under test and absorbs energy from the oscillating circuit. The coil inductance varies with the distance of the probe from the surface of the object being measured, and external circuitry in the sensor's front-end converts this variation into an output voltage signal. Because the magnetic field of the magnetic suspension bearing changes and influences, a sensor with shielding is needed, and secondly, the rotor can be positioned by adopting current ripple, but the method has poor reliability, the pulse can be lost when the relay is switched, and the pulse can be compensated by software, so that the method has the advantage of low price.
The force of the electromagnet on the levitated object is generated on the boundary of objects of different magnetic permeability, i.e. the surface of the levitated object. The change in the energy of the magnetic field in the air gap causes the object surface to generate a force that is a function of the displacement of the levitated object, the magnetic flux remains constant for small displacements ds, when the air gap s increases, the displacement d s increases, the air gap volume V a increases, and the magnetic field energy storage W a of the air gap changes by dW a where W a is:
The energy is converted into mechanical energy for suspending the object, so that the electromagnetic force on the surface of the object is the partial conduction of the magnetic field energy to the air gap s according to the principle of virtual displacement, and the electromagnetic force is
From the point of view of the supporting capacity, the air gap should be as small as possible. Firstly, the air gap is reduced, the whole size of the bearing can be reduced, secondly, the smaller the air gap is, the same bearing size is, the larger the electromagnetic force of the bearing is, the larger the air gap is, the larger the movable range of the rotor is, under the general condition, the air gap is 0.3-0.6mm when the diameter of the rotor is smaller than 100mm, and the air gap is 0.6-1mm when the diameter of the rotor is 100-1000 mm. The diameter of the rotor is 100mm, so the selected air gap is 0.5mm.
And an equivalent magnetic circuit, wherein the bias magnetic flux starts from the N pole and returns to the S pole of the permanent magnet, and forms a closed path along the radial and axial air gaps. The control magnetic flux is generated by the axial and radial bearing stator assemblies forming closed loops through the axial and radial air gaps, respectively. Further, the left-right bias magnetic flux and the left-right radial control magnetic flux are independent of each other.
If the rotor is centered in the stator, the rotor will be magnetically balanced by the biasing magnetic flux. Once an external force is applied to the rotor, which is off center from the stator, the displacement sensor detects the changes and transmits these signals to the controller. Then, the controller adjusts the winding current to generate a control flux linkage, and the control flux linkage is overlapped with the bias flux linkage to generate a five-degree-of-freedom suspension force, so that the rotor is finally pulled back to the center of the stator. The displacement data of the rotating shaft monitored by the displacement sensor is transmitted to the control unit, so that the control unit respectively controls the currents of the axial bearing stator assembly and the radial bearing stator assembly, axial magnetic force lines pass through the two bearing stators and the left and right axial air gaps to form a closed magnetic loop, and the generated axial force acts on the axial thrust disc to further regulate the axial suspension force, overcome external disturbance or load and realize stable suspension of the rotating shaft, namely realize stable suspension of the rotor;
the radial bearing magnetic force lines 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 loop, the generated radial force acts on the radial bearing rotor core, the radial levitation force is regulated, the external disturbance or load is overcome, and the stable levitation of the rotating shaft, namely the stable levitation of the rotor is realized.
A control method of a magnetic suspension bearing, adopting the mixed magnetic suspension bearing with eight poles and five degrees of freedom, comprising the following steps:
obtaining a minimum distance da between the rotating shaft thrust disc 2 and the left axial stator ring 421;
Obtaining a minimum distance db between the rotating shaft thrust disc 2 and the right axial stator ring 422;
The direction and/or magnitude of the current in the axial bearing stator assembly 42 is adjusted according to the magnitude relationship between the minimum distance da and the minimum distance db so that the spindle thrust disc 2 moves axially toward the side of the larger of the minimum distance da and the minimum distance db.
When da is greater than 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 and the permanent magnet bias magnetic circuit generated by the left permanent magnet ring are overlapped in the same direction, and the control magnetic circuit and the permanent magnet bias magnetic circuit generated by the right permanent magnet ring are reversely cut down, and the current in the axial bearing stator assembly is controlled to be smaller and smaller;
When da is less than 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 magnet bias magnetic circuit generated by the left permanent magnet ring are reversely cut down, and are overlapped in the same direction with the permanent magnet bias magnetic circuit generated by the right permanent magnet ring, the current in the axial bearing stator assembly is controlled to be smaller and smaller, and the first direction is opposite to the second direction.
When da=db, the current direction or current magnitude within the axial bearing stator assembly is maintained.
Only one group of axial bearing stator assemblies which are coaxially arranged with the rotating shaft thrust disc are arranged in the interval, and the offset or superposition of magnetic fluxes can be realized by utilizing the direction difference of the permanent magnet bias magnetic circuit and the axial control magnetic circuit, so that the axial bearing stator assemblies can realize the adjustment control of the axial position of the rotating shaft thrust disc, the control logic is simpler, the axial length of the five-degree-of-freedom magnetic bearing can be designed to be smaller, the corresponding rotating shaft length can be shortened, the rotating shaft rotating speed can be improved, and more importantly, the left permanent magnet ring and the right permanent magnet ring are respectively positioned between the axial stator ring and the two radial stators, the axial control magnetic circuit and the radial control magnetic circuit can be isolated, the coupling existing between the radial control magnetic circuit and the axial control magnetic circuit is effectively reduced, the control difficulty of the magnetic bearing is further reduced, and the control logic is simplified.
More preferably, the application also provides a radial control method which is similar to the axial control method, because the magnetic pole distribution is NNSSNNSS, the magnetic pole distribution is actually equivalent to four poles, taking left radial control as an example, the distance between the obtained radial coil and the radial rotor is dc, dd, de, df respectively, the distance between the large four poles and the rotor corresponds to the air gap distance between the large four poles and the rotor clockwise, and the distance dc is the upper side distance.
When dc > de, the control magnetic circuit generated by the control current in the corresponding radial coil is overlapped with the permanent magnet bias magnetic circuit generated by the upper permanent magnet ring in the same direction and is reversely cut down with the permanent magnet bias magnetic circuit generated by the lower permanent magnet ring, the current in the stator assembly of the radial bearing on the dc side is controlled to be larger and larger, and the current in the stator assembly of the radial bearing on the de side is controlled to be smaller and smaller, and 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 overlapped with the permanent magnet bias magnetic circuit generated by the permanent magnet ring at the front side of the magnetic suspension bearing in the same direction, and is reversely reduced with the permanent magnet bias magnetic circuit generated by the rear side permanent magnet ring, so that the current in the dd side radial bearing stator assembly is controlled to be larger and larger, and the current in the df side radial bearing stator assembly is controlled to be smaller and smaller, and when dd < df, the control method is opposite.
When dc=dd= =de=df, the current direction or current magnitude within the radial bearing stator assembly is maintained unchanged.
The magnetic poles shown in fig. 6 are in different-polarity magnetic pole distribution NNSSNNSS, and when the rotor rotates, the direction of magnetic force lines changes less than NSNS in one period, so that the loss is small, and the radial position adjustment of the rotating shaft is a better choice, and the adjustment is decoupled from the axial control magnetic circuit, so that independent adjustment can be realized without collision with the axial coil.
In particular, as shown in fig. 5, the arrows in the figure show the radial magnetic path trend, the axial magnetic path trend, the offset magnetic path trend, the a offset magnetic path, the b radial control magnetic path and the c axial control magnetic path, so that the left permanent magnet ring and the right permanent magnet ring are identical in performance, and the difference is that the magnetic poles are opposite to each other, respectively generate a left offset magnetic path and a right offset magnetic path, and the left offset magnetic path and the right offset magnetic path are structurally symmetric to the left and right with respect to the radial direction, so that the left and right forces above the shaft are balanced. The axial bearing stator assembly is centrally symmetrical along the radial surface, so that the axial control magnetic circuit generated by the axial bearing stator assembly after the axial bearing stator assembly is electrified can be ensured to be symmetrical about the radial surface, the permanent magnet bias magnetic circuit of the rotating shaft thrust disc is bilaterally symmetrical, and the control difficulty of the magnetic bearing is further reduced. The displacement of the rotating shaft and the rotor in the axial direction completely depends on the magnitude and the direction of control current in the axial coil, and the left permanent magnet ring and the right permanent magnet ring respectively provide symmetrical offset magnetic circuits and simultaneously effectively prevent the axial control magnetic circuit from flowing to one side of the left radial control magnetic circuit and one side of the right radial control magnetic circuit so as to prevent the coupling of the left permanent magnet ring and the right permanent magnet ring. In addition, according to the structure of the following figure, the permanent magnet bias magnetic circuit is single, the magnetic leakage is small, and the axial control magnetic circuit is directly formed into a loop by the stator core and the rotating shaft thrust plate.
FIG. 7 shows the axial superposition of the control current in the axial direction and the magnetic flux generated by the permanent magnet ring, with the maximum flux in the middle of the axial rotor, and the axial direction, the direction of the magnetic flux pointing to the center of the structure, the midpoint of the rotor. Because the permanent magnet ring is magnetized axially, 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 to form an axial closed path, the magnetic density on the rotor is symmetrical, and the resultant force on the three rotors is zero. The three sheet rotors form a closed path. The distribution of magnetic flux on the rotor is symmetrical, the magnetic flux intensity is symmetrical on the radial surface, the resultant force on the sheet rotor is zero, and the equivalent magnetic path is closed.
FIG. 8 is a graph of superimposed magnetic densities produced by a control current in the axial direction and a permanent magnet ring, with the axial coil current set to be in the same direction, and the axial coil default current of 0A when no rotor deflection occurs. As can be seen, the control flux overlaps the bias flux in one direction increasing and the overlap in the opposite direction decreasing. The resultant force points to the direction of magnetic field enhancement, if the rotor deviates to the left, the axial coil is electrified, as shown in the following figure 8, the right magnetic field intensity pulls the rotor back to the middle point, and whether the power is cut off is judged according to the rotor position detected by the sensor.
FIG. 9 is a graph of superimposed magnetic density generated by control current in the radial direction and a permanent magnet ring, and when the rotor is shifted, whether the radial coil is energized is determined based on the degree of rotor shift detected by the sensor. The radial position of the rotating shaft is adjusted according to the adjustment mode of the radial bearing in the prior art, and the adjustment is decoupled from the axial control magnetic circuit, so that independent adjustment can be realized.
The specific design flow is as follows:
1) Drawing an equivalent magnetic circuit diagram according to the structure diagram, and designing control magnetic flux and bias magnetic flux at each air gap;
2) Calculating a radial levitation force formula, and solving a force/displacement parameter and a force/current parameter;
3) Solving the magnetic pole area according to a radial levitation force formula;
4) According to the air gap control magnetic flux, a radial control winding is obtained;
5) Further determining the radius of the rotor core, the radius of the rotating shaft, the width, the axial length and the tooth height of the radial stator;
6) Calculating the width and magnetizing thickness of the permanent magnet;
7) Drawing a two-dimensional model by using Maxwell software, and analyzing from a magnetic force diagram, a magnetic density distribution diagram, a force/current relation diagram and a force/displacement relation diagram;
8) Under the condition that the air gap of the auxiliary bearing is determined and the passive magnetic pulling force generated by the permanent magnetic pole is overcome, the ratio of the control magnetic pole area to the permanent magnetic stimulating area is found out, and the maximum radial levitation force is obtained;
9) And designing an experimental prototype, and carrying out static suspension experiments and dynamic suspension experiments.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (5)
1. The eight-pole five-degree-of-freedom hybrid magnetic suspension bearing is characterized by comprising a rotating shaft (1), wherein a rotating shaft thrust disc (2) is arranged in the middle of the rotating shaft (1), rotors (3) are sleeved at two ends of the rotating shaft (1), and stator assemblies (4) are sleeved on the peripheral sides of the rotors (3), and the eight-pole five-degree-of-freedom hybrid magnetic suspension bearing is characterized in that the stator assemblies (4) comprise a shell (40) sleeved on the rotating shaft (1);
Radial bearing stator components (41) which are positioned at two ends of the shell (40) and sleeved on the rotor (3) for generating controllable magnetic radial attraction force and providing radial magnetic field action for the rotor (3) so as to adjust the radial position of the rotor (3);
The axial bearing stator assembly (42) comprises a left axial stator ring (421) and a right axial stator ring (422), which are respectively sleeved at two ends of the rotating shaft thrust disc (2) and are positioned in the shell (40) and used for generating controllable magnetic axial suction force so as to provide an axial magnetic field effect for the rotor (3) to adjust the radial position of the rotor (3);
a permanent magnet ring set (5) arranged between the radial bearing stator assembly (41) and the axial bearing stator assembly (42) for providing a symmetrical bias magnetic circuit for the bearing;
The radial bearing stator assembly (41) comprises a circular ring-shaped sleeve (410), a plurality of flanges (411) are convexly arranged on the inner wall of the circular ring-shaped sleeve (410) towards the direction of the rotor (3), and a control coil (412) is wound on each of the plurality of flanges (411) so as to generate controllable magnetic radial suction to stably suspend the rotating shaft (1) in a non-contact manner;
the number of the flanges (411) is 8, the flanges are uniformly distributed on the inner wall of the circular ring-shaped sleeve (410) along the circumference, the control coils (412) are wound on the 8 flanges (411), and the magnetic poles of the 8 flanges (411) are distributed NNSSNNSS;
The magnetic pole distribution is NNSSNNSS, which is actually equivalent to a quadrupole, taking radial control on the left side as an example, the distances between the radial coils and the radial rotor are dc, dd, de, df respectively, the distances between the large quadrupole and the rotor are corresponding to the clockwise, and the distance dc is the upper-side distance, and the method comprises the following steps:
When dc > de, the control magnetic circuit generated by the control current in the corresponding radial coil is overlapped with the permanent magnet bias magnetic circuit generated by the upper permanent magnet ring in the same direction and is reversely cut down with the permanent magnet bias magnetic circuit generated by the lower permanent magnet ring, and the current in the stator assembly of the radial bearing on the dc side is controlled to be larger and larger, and the current in the stator assembly of the radial bearing on the de side is controlled to be smaller and smaller;
when dd > df, the control magnetic circuit generated by the control current in the corresponding radial coil is overlapped with the permanent magnet bias magnetic circuit generated by the permanent magnet ring at the front side of the magnetic suspension bearing in the same direction, and is reversely reduced with the permanent magnet bias magnetic circuit generated by the permanent magnet ring at the rear side, so that the current in the dd side radial bearing stator assembly is controlled to be larger and larger, and the current in the df side radial bearing stator assembly is controlled to be smaller;
When dc=dd=de=df, the current direction or current magnitude within the radial bearing stator assembly is maintained unchanged.
2. The eight-pole five-degree-of-freedom hybrid magnetic suspension bearing according to claim 1, wherein a placement groove (401) for placing the axial bearing stator assembly (42) is formed in the shell (40), and the placement groove (401) is located on the periphery of the rotating shaft thrust disc (2).
3. The eight-pole five-degree-of-freedom hybrid magnetic suspension bearing of claim 1 wherein the permanent magnet ring set (5) comprises a left permanent magnet ring (51) located on the left side of the housing (40) and a right permanent magnet ring (52) located on the right side of the housing (40), the opposite ends of the left permanent magnet ring (51) and the right permanent magnet ring (52) being of the same polarity.
4. The eight-pole five-degree-of-freedom hybrid magnetic suspension bearing according to claim 1 wherein the permanent magnet ring set (5) is made of NdFe35.
5. A control method of a magnetic suspension bearing is characterized in that: use of an octupole five degree of freedom hybrid magnetic bearing as claimed in any of claims 1 to 4 comprising the steps of:
Obtaining a minimum distance da between the rotating shaft thrust disc (2) and the left axial stator ring (421);
obtaining a minimum distance db between the spindle thrust disc (2) and the right axial stator ring (422);
The current direction and/or current magnitude in the axial bearing stator assembly (42) is adjusted according to the magnitude relation between the minimum distance da and the minimum distance db so as to enable the rotating shaft thrust disc (2) to axially move towards the side with the larger value of the minimum distance da and the minimum distance db.
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| CN102891544A (en) * | 2011-07-21 | 2013-01-23 | 天津昊高磁材有限公司 | Inner-tooth-shaped octopole stator magnetic core |
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| 永磁偏置五自由度磁轴承结构及磁路分析;王冠, 徐龙祥;机电产品开发与创新;20030625(第06期);16-18/23 * |
| 王冠,徐龙祥.永磁偏置五自由度磁轴承结构及磁路分析.机电产品开发与创新.2003,(第06期),16-18/23. * |
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