Radial enhancement type axial mixing magnetic bearing

Abstract

The invention discloses a radial enhancement type axial hybrid magnetic bearing. A stator is composed of a stator iron core, a permanent magnet and a stator coil; the rotor comprises a rotating shaft, a rotor iron core, a collecting ring and a rotor coil; the permanent magnet is adhered to the inner side of the stator core, a radial air gap and an axial air gap exist between the permanent magnet and the rotor core, the stator coil is wound on the inner side of the stator core, two collecting rings are connected to a rotating shaft on two sides of the rotor core, the rotor coil is wound on the radial surface of the rotor core, and the rotor coil is connected with the collecting rings through holes formed in the radial direction. And then a carbon brush is connected with the stator coils on the two sides to form a control winding, the control winding is driven by a driver, and the controller controls the driver to generate suspension force on the rotor according to the axial displacement change of the rotor, so that stable suspension of the rotor is realized. According to the axial hybrid magnetic bearing, the rotor coil is additionally arranged on the surface of the rotor core to increase the axial suspension force, the axial hybrid magnetic bearing has the technical advantage of high suspension force density, and the technical development of the axial hybrid magnetic bearing is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of motor hybrid magnetic bearings and their control technologies, and particularly to a radially enhanced axial hybrid magnetic bearing with an axial positioning function for a high-speed magnetic levitation motor. Background Art

[0002] Using a magnetic levitation bearing to support the motor rotor and constructing a magnetic levitation high-speed motor is an important technical solution to achieve the high-speed operation of the motor, and the axial magnetic bearing is an essential part for realizing the axial stable suspension of the motor rotor. Axial magnetic bearings include two types: electro-magnetic excitation and permanent-magnet excitation. In particular, permanent-magnet excitation has the characteristics of large suspension force density, low power consumption, and simple control. However, the principle of the permanent-magnet excitation axial magnetic bearing is that the axial control winding generates a control magnetic field, and the permanent magnet generates a bias magnetic field. The two combined air-gap magnetic fields cause the axial air-gap magnetic field on one side to increase and the other side to decrease, thereby generating a controllable suspension force in the opposite direction of the rotor eccentricity direction to achieve the axial stable suspension of the rotor. Its bearing capacity is only related to the axial pole area. To achieve a magnetic levitation motor with higher speed and greater power, it is necessary to increase the suspension force density of the axial hybrid magnetic bearing and reduce the volume. Therefore, the present invention proposes a radially enhanced axial hybrid magnetic bearing with a larger suspension force density. This magnetic bearing generates axial suspension forces on all the axial sides and radial surfaces of the rotor, with a larger suspension force density, reducing the volume of the magnetic levitation motor and increasing its critical speed and power density. Summary of the Invention

[0003] Object of the Invention: The present invention aims to further improve the suspension force density and bearing capacity of the existing axial hybrid magnetic bearing, and proposes a radially enhanced axial hybrid magnetic bearing. Axial suspension forces are generated on the entire surface of the rotor of this magnetic bearing, and a parameter design method is given, which greatly promotes the technological progress of the axial hybrid magnetic bearing.

[0004] Technical Solution: The present invention discloses a radially enhanced axial hybrid magnetic bearing, including a stator and a rotor. The stator includes a stator core, permanent magnets, left and right stator coils; the rotor includes a rotating shaft, a rotor core, left and right slip rings, left and right carbon brushes, and a rotor coil; the permanent magnets are adhesively fixed at the center of the stator core, and there are radial air gaps and left and right axial air gaps between the permanent magnets and the rotor core; the left and right stator coils are wound on the inner side of the stator core, the rotor core is fixedly penetrated on the rotating shaft, left and right slip rings are fixed on the rotating shaft on both sides of the rotor core through insulating materials, a rotor coil is wound on the surface of the rotor core, the inlets and outlets of the rotor coil pass through deep holes at the radial positions on both sides of the rotor core and are connected to the left and right slip rings, and the other sides of the left and right slip rings are respectively connected to the left and right stator coils through the left and right carbon brushes. The rotor coil, the left and right stator coils form a control winding and are connected to the output end of the driver, and are then controlled by a controller.

[0005] Further, the number of turns of the left stator coil is equal to that of the right stator coil, and the left and right stator coils have the same winding direction as the rotor coil and are connected in series to form a control winding.

[0006] Further, the permanent magnet is radially magnetized, and the magnetic flux generated by it starts from the N pole of the permanent magnet, divides into two parts and passes through the stator core, passes through the left and right axial air gaps on both sides, then passes through the rotor core, the rotor coil, and the radial air gap, and returns to the S pole of the permanent magnet.

[0007] Further, the air-gap magnetic density of the permanent magnet in the radial air gap is B s , and the designed values of the air-gap magnetic densities generated by the left and right axial air gaps are 0.5B s , the lengths of the left and right axial air gaps are 0.5 mm; the wire diameters of the rotor coil and the left and right stator coils are d, and the length of the radial air gap is d + 0.5 mm.

[0008] Further, the parameter design method process of the radially enhanced axial hybrid magnetic bearing is as follows:

[0009] Step 1: Determine the air-gap saturation magnetic density B s Take the value of 1.2 T, and according to the bias magnetic circuit, determine the ratio of the rotor radial surface area to the axial surface area as: S r :S z = 1, let S r = S z = S;

[0010] Step 2: Set the effective ranges of each parameter. The wire diameter of the coil winding is d, and d takes values from 0.6 mm to 1 mm. The magnitude of the current i flowing through the coil winding is 3 A to 5 A, and the length of the radial air gap l rg = mm, and the lengths of the left and right axial air gaps l zg take the value of 0.5 mm;

[0011] Step 3: Determine the magnetic resistance R pm of the permanent magnet, the magnetic resistance R rg of the radial air gap, and the magnetic resistance R zg of the axial air gap:

[0012]

[0013] Among them, l pm is the axial length of the permanent magnet, l rg is the length of the radial air gap, l zg is the length of the left and right axial air gaps, μ g and μ pm are the permeabilities of air and the permanent magnet respectively, and both are approximately equal to the permeability of air. Denote μ g = μ pm = μ0;

[0014] Step 4: The permanent magnet generates a total magnetomotive force F pm is:

[0015] F pm = l pm H c

[0016] where H c is the coercivity of the permanent magnet;

[0017] Step 5: Combine the flux-magnetomotive force-reluctance relationship and substitute the above equation into the following formula:

[0018]

[0019] where the permanent magnet flux Φ pm = B s μ pm ;

[0020] Step 6: Calculate the axial length of the permanent magnet:

[0021]

[0022] Step 7: The number of turns n of the rotor coil:

[0023]

[0024] Step 8: Establish a mathematical model for the maximum bearing capacity:

[0025]

[0026] where F max is the maximum bearing capacity, R1 is the outer radius of the permanent magnet, r1 is the inner radius of the permanent magnet, and R0 is the outer radius of the rotor;

[0027] Step 9: Select the inner radius r1, the wire diameter d of the winding coil, and the current i, and determine the outer radius R1 of the permanent magnet according to the maximum bearing capacity requirement F max Determine the outer radius R1 of the permanent magnet.

[0028] Furthermore, the rotor core and the stator core are made of magnetic conductive materials, the permanent magnet ring is made of neodymium iron boron material, the left and right carbon brushes are made of graphite material, and the left and right slip rings are made of copper alloy.

[0029] Beneficial effects:

[0030] In the present invention, the stator coil is wound inside the stator core, and the rotor winding is wound on the surface of the rotor and passes through the holes radially opened on both sides of the rotor core. Then, the rotor winding is connected to the stator coils on both sides through carbon brushes to form a control winding, which is driven by a driver. The controller controls the driver to generate a suspension force on the rotor according to the change of the axial displacement of the rotor, so as to realize the generation of an axial suspension force on both the axial side and the radial surface of the rotor, increase the suspension force, reduce the volume space, lower the control difficulty, and improve the performance of the axial force of the hybrid magnetic bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. is the overall structure diagram of the radially enhanced axial hybrid magnetic bearing of the present invention;

[0032] Figure 2 FIG. is the partial parameter indication diagram of the radially enhanced axial hybrid magnetic bearing of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the protection scope of the present invention.

[0034] The present invention discloses a radially enhanced axial hybrid magnetic bearing, as Figure 1 shown, the stator 1 includes a stator core 3, a permanent magnet 4, left and right stator coils 5, 6; the rotor 2 includes a rotating shaft 7, a rotor core 8, left and right slip rings 9, 10, left and right carbon brushes 15, 16, and a rotor coil 11.

[0035] The permanent magnet 4 is adhesively fixed at the center of the stator core 3, and there are a radial air gap 12 and left and right axial air gaps 13, 14 between the permanent magnet 4 and the rotor core 8. The stator coils 5, 6 are wound inside the stator core 3. The rotor core 8 is fixedly penetrated on the rotating shaft 7, and left and right slip rings 9, 10 are fixed on the rotating shaft 7 on both sides of the rotor core 8 through insulating materials. A rotor coil 11 is wound on the surface of the rotor core 8. The incoming and outgoing wires of the rotor coil 11 pass through the deep holes at the radial positions on both sides of the rotor core 8 and are connected to the left and right slip rings 9, 10. The other sides of the left and right slip rings 9, 10 are respectively connected to the left and right stator coils 5, 6 through the left and right carbon brushes 15, 16, forming a complete control winding connected to the output end of the driver and then controlled by the controller.

[0036] The left and right stator coils 5 and 6 have the same number of turns, and the left and right stator coils 5, 6 and the rotor coil 11 have the same winding direction and are connected in series to form a control winding.

[0037] The permanent magnet 4 is radially magnetized. The magnetic flux 17 generated by it starts from the N pole of the permanent magnet 4, divides into two parts and passes through the stator core 3, passes through the left and right axial air gaps 13 and 14 on both sides, then passes through the rotor core 8, the rotor coil 11, and the radial air gap 12, and returns to the S pole of the permanent magnet 4.

[0038] The air-gap magnetic density of the permanent magnet 4 in the radial air gap 12 is B s , and the designed values of the air-gap magnetic densities generated by the axial air gaps 13 and 14 are 0.5B s . Generally, the lengths of the axial air gaps 13 and 14 are taken as 0.5 mm; the wire diameters of the rotor coil 11, the left and right stator coils 5 and 6 are d, and the length of the radial air gap 12 is taken as d + 0.5 mm;

[0039] Figure 2 This is the schematic diagram of the parameters of the present invention. For the design of the main parameters of the radially enhanced axial hybrid magnetic bearing, first determine the air-gap saturation magnetic density B s , and take the value of 1.2 T. Then, according to the bias magnetic circuit, determine the ratio of the radial surface area to the axial surface area of the rotor as: S r :S z = 1, let S r = S z = S.

[0040] Set the effective ranges of each parameter. The wire diameter of the coil winding is d, and d takes values from 0.6 mm to 1 mm. The magnitude of the current i flowing through the coil winding is 3 A to 5 A. The length l rg of the radial air gap 12 = (d + 0.5) mm, and the lengths l zg of the left and right axial air gaps 13 and 14 take the value of 0.5 mm.

[0041] According to the axial length l pm of the permanent magnet, the length l rg of the radial air gap, and the length l zg of the axial air gap, determine the magnetic resistance R pm of the permanent magnet, the magnetic resistance R rg of the radial air gap, and the magnetic resistance R zg of the axial air gap:

[0042]

[0043] Among them, μ g and μ pm are the magnetic permeabilities of air and the permanent magnet respectively. Both are approximately equal to the magnetic permeability of air, and denote μ g = μ pm = μ0.

[0044] The coercive force H c of the permanent magnet can represent the total magnetomotive force F pm generated by the permanent magnet = l pm Hc 。

[0045] Simultaneously establish the relationship between magnetic flux, magnetomotive force, and magnetic reluctance:

[0046]

[0047] Among them, the permanent magnet magnetic flux Φ pm = B s μ pm 。

[0048] Substitute the equation into the above formula to obtain the axial length of the permanent magnet:

[0049]

[0050] Number of rotor coils

[0051] Establish a mathematical model of bearing capacity:

[0052]

[0053] Among them, R1 is the outer radius of the permanent magnet, r1 is the inner radius of the permanent magnet, R0 is the outer radius of the rotor, and l pm is the axial length of the permanent magnet. Finally, select the inner radius r1, the wire diameter d of the winding coil, the current i, and determine the outer radius R1 of the permanent magnet 4 according to the maximum bearing capacity requirement F max . For specific parameters, refer to Figure 2 。

[0054] The rotor core 8 and the stator core 3 are made of magnetic conductive materials, the permanent magnet ring 4 is made of neodymium iron boron material, the left and right carbon brushes 15, 16 are made of graphite materials, and the left and right slip rings 9, 10 are made of copper alloy.

[0055] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A radially reinforced axial hybrid magnetic bearing, comprising a stator (1) and a rotor (2), characterized in that: The stator (1) comprises a stator core (3), a permanent magnet (4), and left and right stator coils (5, 6); the rotor (2) comprises a rotating shaft (7), a rotor core (8), left and right collector rings (9, 10), left and right carbon brushes (15, 16), and a rotor coil (11); the permanent magnet (4) is bonded and fixed to the center of the stator core (3), and a radial air gap (12) and left and right axial air gaps (13, 14) exist between the permanent magnet (4) and the rotor core (8); the left and right stator coils (5, 6) are wound on the inner side of the stator core (3), the rotor core (8) penetrates and is fixed on the rotating shaft (7), and the rotor core (8) is fixed to the rotating shaft (7). Left and right collector rings (9, 10) are fixed on the rotating shaft (7) on both sides of the core (8) through insulating materials, and a rotor coil (11) is wound on the surface of the rotor core (8). The input and output wires of the rotor coil (11) pass through deep holes at radial positions on both sides of the rotor core (8) and are connected to the left and right collector rings (9, 10). The other sides of the left and right collector rings (9, 10) are respectively connected to the left and right stator coils (5, 6) through left and right carbon brushes (15, 16). The rotor coil (11) and the left and right stator coils (5, 6) form a control winding connected to the output end of the driver, and then controlled by a controller.

2. A radially enhanced axial hybrid magnetic bearing according to claim 1, characterized in that: The left stator coil (5) and the right stator coil (6) have the same number of turns, and the left and right stator coils (5, 6) and the rotor coil (11) are wound in the same direction and are connected in series to form a control winding.

3. A radially enhanced axial hybrid magnetic bearing according to claim 1, characterized in that: The permanent magnet (4) is radially magnetized, and the magnetic flux (17) generated starts from the N pole of the permanent magnet (4), splits into two, passes through the stator core (3), passes through the left and right axial air gaps (13, 14) on both sides, and then passes through the rotor core (8), the rotor coil (11), the radial air gap (12), and returns to the S pole of the permanent magnet (4).

4. A radially enhanced axial hybrid magnetic bearing according to claim 1, characterized in that: The air gap magnetic flux density of the permanent magnet (4) in the radial air gap (12) is B s The design value of the air gap magnetic flux density generated by the left and right axial air gaps (13, 14) is 0.5B s The length of the left and right axial air gaps (13, 14) is 0.5 mm; the wire diameter length of the rotor coil (11) and the left and right stator coils (5, 6) is d, and the length of the radial air gap (12) is d+0.5 mm.

5. A radially enhanced axial hybrid magnetic bearing according to claim 1, characterized in that: The parameter design method of radially enhanced axial hybrid magnetic bearings is as follows: Step 1: Determine the air gap saturation flux density B s The value is 1.2T. According to the bias magnetic circuit, the ratio of the rotor radial surface to the axial surface area is determined as: S r :S z =1, let S r =S z =S; Step 2: Set the effective range of each parameter. The coil winding wire diameter is d, d is 0.6mm-1mm, the current i flowing through the coil winding is 3A-5A, and the radial air gap (12) length is l rg =(d+0.5)mm, left and right axial air gap (13, 14) length l zg The value is 0.5mm; Step 3: Determine the permanent magnet reluctance R pm , radial air gap reluctance R rg , axial air gap reluctance R zg : Among them, l pm is the axial length of the permanent magnet (4), l rg is the length of the radial air gap (12), l zg is the length of the left and right axial air gaps (13, 14), μ g and μ pm are the magnetic permeabilities of air and permanent magnet respectively, both of which are approximately equal to the magnetic permeability of air, denoted by μ g =μ pm =μ0; Step 4: The permanent magnet (4) generates a total magnetomotive force F pm for: F pm =l pm H c Among them, H c is the coercive force of the permanent magnet; Step 5: Combine the flux-magnetomotive force-magnetic resistance relationship and substitute the above equation into the following formula: Among them, the permanent magnet flux Φ pm =B s μ pm ; Step 6: Calculate the axial length of the permanent magnet (4): Step 7: Number of rotor coils n: Step 8: Establish the maximum bearing capacity mathematical model: Among them, F max is the maximum bearing capacity, R1 is the outer radius of the permanent magnet (4), r1 is the inner radius of the permanent magnet (4), and R0 is the outer radius of the rotor; Step 9: Select the inner radius r1, winding coil wire diameter d, current i, and the maximum load capacity F max Determine the outer radius R1 of the permanent magnet (4).

6. The radially enhanced axial hybrid magnetic bearing according to claim 1, characterized in that: The rotor core (8) and the stator core (3) are made of magnetic conductive materials, the permanent magnet ring (4) is made of neodymium iron boron material, the left and right carbon brushes (15, 16) are made of graphite material, and the left and right collector rings (9, 10) are made of copper alloy.

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