CN106763184B - A six-pole radial-axial hybrid magnetic bearing - Google Patents

Abstract

The present invention discloses a kind of sextupole radial-axial hybrid magnetic bearing that can control radial two-freedom and axial freedom simultaneously, the outer coaxial sleeve radial stator of rotor, and radial stator is coaxially cased with the permanent magnet of circular ring shape outside, axial stator is coaxially cased with outside permanent magnet；Radial stator it is evenly distributed in the circumferential direction there are six magnet radial poles, radial control coil is wound in each magnet radial poles, the radial control coils series connection of two in aspectant two magnet radial poles and winding direction is identical；The axial control coil of one circular ring shape is respectively housed, two axial control coils are connected and winding direction is identical by the axial ends side of radial stator；Radial stator of the invention uses sextupole structure, forms three-phase windings, reduces switching tube quantity, reduces power loss and driver cost, reduces the coupling between radial two freedom degrees.

Description

A six-pole radial-axial hybrid magnetic bearing

technical field

The invention relates to a non-contact magnetic suspension bearing (magnetic bearing for short), in particular to a three-degree-of-freedom hybrid magnetic bearing that can simultaneously control two radial degrees of freedom and axial degrees of freedom, and is suitable for aerospace, nuclear energy and wind power generation. , biomedicine, flywheel energy storage, high-speed motorized spindle and other types of rotating machinery support in industrial fields, belonging to the field of high-speed and ultra-high-speed electrical transmission.

Background technique

The magnetic bearing uses electromagnetic force to suspend the rotor in the air, so that there is no contact between the rotor and the stator. It has the advantages of no friction, no wear, no need for lubricating oil, high supporting speed, dynamic adjustment of rotor displacement, high rotation accuracy, and long life. Magnetic bearings can be divided into single-degree-of-freedom magnetic bearings (axial magnetic bearings), two-degree-of-freedom magnetic bearings (radial magnetic bearings) and three-degree-of-freedom magnetic bearings (radial-axial magnetic bearings) according to the number of degrees of freedom that can be controlled. According to the way the suspension force is generated, it can be divided into active magnetic bearing (suspended force is generated by coil current), passive magnetic bearing (suspended force is generated by permanent magnet) and hybrid magnetic bearing (suspended force is generated by permanent magnet and coil current). Among them, the hybrid magnetic bearing uses permanent magnets to provide bias magnetic flux, which can reduce the number of coil turns, reduce power loss, and reduce the volume and weight of the magnetic bearing. Usually the radial magnetic bearing adopts a four-pole or eight-pole structure, and is driven by two bipolar switching power amplifiers. Phase inverter drive. In the "Three Degrees of Freedom AC-DC Radial-Axial Hybrid Magnetic Bearing and its Control Method" disclosed in the Chinese Patent Application No. 200510040066.4, the radial and axial magnetic bearings are combined into a whole, and a permanent magnet is used at the same time. Provide radial and axial bias flux, and there is no coupling between the axial control magnetic circuit and the radial control magnetic circuit, the radial adopts a three-pole structure, and is driven by a three-phase power inverter. However, the problem of this kind of magnetic bearing is: the spatial asymmetry of the three-pole structure and the condition that the three-phase current sum of the three-phase inverter is zero, the maximum suspension force of the radial suspension force in the direction of the magnetic pole and the opposite direction of the magnetic pole is not equal. etc. When designing the magnetic bearing, the minimum direction of the suspension force must meet the bearing capacity requirements, which will inevitably lead to an increase in the volume of the magnetic bearing. In addition, the three-pole asymmetric structure increases the nonlinearity between the magnetic bearing suspension force, current and displacement, and also enhances the coupling between the two radial degrees of freedom.

SUMMARY OF THE INVENTION

In order to overcome the shortcomings of the existing hybrid magnetic bearing with three-pole structure, the present invention proposes a six-pole radial-axial hybrid magnetic bearing to reduce the volume of the magnetic bearing, improve the space utilization rate, and reduce the nonlinearity of the magnetic bearing. Decreases the coupling between the radial degrees of freedom.

The technical scheme adopted in the present invention is as follows: a radial stator is coaxially sleeved outside the rotor, a circular permanent magnet is coaxially sleeved outside the radial stator, and an axial stator is coaxially sleeved outside the permanent magnet; There are six radial magnetic poles evenly arranged, each radial magnetic pole is wound with a radial control coil, and the two radial control coils on the two facing radial magnetic poles are connected in series and in the same winding direction; An annular axial control coil is installed on each side of the end side, and the two axial control coils are connected in series and in the same winding direction.

Further, the axial stator is composed of an axial stator cylinder, two axial stator discs and two axial magnetic poles. Both ends of the axial stator cylinder are fixedly connected with an axial stator disc. The same and symmetrically arranged face-to-face, the middle of the axial stator disk protrudes toward the opposite direction and extends annular axial magnetic poles to the axial ends of the rotor, and the two axial magnetic poles correspond to the axial ends of the rotor. leave an axial air gap.

Furthermore, the permanent magnets are fixedly embedded between the outer annular surface of the radial stator and the inner annular surface of the axial stator cylinder, and the axial control coil is wound on the inner annular surface of the axial stator cylinder.

Compared with the existing hybrid magnetic bearing, the advantages of the present invention are: the radial stator of the present invention adopts a six-pole structure to form a three-phase winding, adopts a three-phase full-bridge drive, reduces the number of switch tubes, reduces power loss and drives. cost. The radial six-pole structure makes the suspension force/displacement and suspension force/current characteristics of the magnetic bearing tend to be linear, and improves the bearing capacity of the magnetic bearing, reduces the coupling between the two radial degrees of freedom, and solves the problem of the three-pole diameter. The nonlinearity between the radial suspension force and the control current caused by the radial asymmetry of the axial-axial hybrid magnetic bearing and the coupling between the two radial degrees of freedom suspension force. In the present invention, the permanent magnet and the coil jointly generate the levitation force, thereby reducing the power consumption of the system. The control of the present invention is simpler and more precise.

Description of drawings

1 is a radial cross-sectional view of a six-pole radial-axial hybrid magnetic bearing of the present invention;

Fig. 2 is A-A sectional view in Fig. 1;

Fig. 3 is the sectional view of the installation structure of the axial stator and the axial control coil in Fig. 2;

Fig. 4 is the installation structure diagram of radial stator and radial control coil in Fig. 1;

Fig. 5 is the axial magnetic circuit schematic diagram of the present invention;

Fig. 6 is the radial magnetic circuit schematic diagram of the present invention;

In the figure: 1. Rotor; 2. Axial stator; 3. Radial stator; 4. Radial control coil; 5. Axial control coil; 6. Permanent magnet; 21. Axial stator cylinder; 31. Radial stator Yoke; 41, 42, 43, 44, 45, 46. Radial control coil; 51, 52. Axial control coil; 71, 72. Axial air gap; 81. Radial air gap; 91. Bias flux ; 92. Axial control flux; 93. Radial control flux; 221, 222. Axial stator disk; 231, 232. Axial magnetic pole;

Detailed ways

As shown in FIG. 1 and FIG. 2 , the present invention consists of a rotor 1 , an axial stator 2 , a radial stator 3 , a radial control coil 4 , an axial control coil 5 and a permanent magnet 6 . The rotor 1 is located at the center of the radial stator 3, the radial stator 3 is coaxially sleeved outside the rotor 1, the radial stator 3 is coaxially sleeved with an annular permanent magnet 6, and the outer Stator 2. The annular permanent magnet 6 is magnetized in the radial direction, the inner side of the permanent magnet 6 is the S pole, and the outer side is the N pole. The permanent magnets 6 are embedded between the outer annular surface of the radial stator 3 and the inner annular surface of the axial stator 2 . The axial length of the permanent magnets 6 is less than the axial length of the radial stator 3 , and the axial length of the radial stator 3 is less than the axial length of the rotor 1 .

The radial stator 3 is formed by combining the radial stator yoke 31 and the radial magnetic poles 32 as a whole. The radial stator yoke 31 is annular, and the inner annular surface of the radial stator yoke 31 is uniformly arranged with six radial magnetic poles 32 along the circumferential direction. , forming a hexapole structure. A radial control coil 4 is wound around each radial pole 32 . An axial control coil 5 is installed on each of the axial ends of the radial stator 3. The axial control coil 5 is in the shape of a circular ring and is wound along the inner annular surface of the axial stator 2. The axial control coil 5 is connected to the radial The stators 3 are not in contact and are spaced apart in the axial direction.

The axial stator 2 is cylindrical. The radial stator 3, the radial control coil 4, the axial control coil 5 and the permanent magnet 6 are all contained in the axial stator 2. The axial stator 2 is connected to the rotor 1 and the radial stator. 3. The central axes of the axial control coil 5 and the permanent magnet 6 are collinear.

An axial air gap is left between the two axial ends of the axial stator 2 and the axial two ends of the rotor 1 , and the axial air gaps at the two ends are an axial air gap 71 and an axial air gap 72 respectively. A radial air gap 81 is left between the inner annular surface of the six radial magnetic poles 32 of the radial stator 3 and the outer annular surface of the rotor 1 .

The rotor 1 and the radial stator 3 are made of laminated silicon steel sheets. The radial control coil 4 and the axial control coil 5 are made of copper wire with insulating paint with a nominal diameter of 0.67mm. The axial stator 2 is made of iron-silicon alloy material. . The permanent magnet 6 is made of rare earth RuFeB permanent magnet material, which is magnetized outward in the radial direction for generating bias magnetic flux.

As shown in FIG. 3 , the cylindrical axial stator 2 is composed of an axial stator cylinder 21 , two axial stator disks and two axial magnetic poles. Both ends of the axial stator cylinder 21 are fixedly connected with an axial stator disk, and the two axial stator disks are respectively an axial stator disk 221 and an axial stator disk 222. The two axial stator disks 221 and 222 have the same structure. And symmetrically arranged face to face. The outer diameter of the axial stator cylinder 21 is equal to the outer diameters of the two axial stator disks 221 and 222 .

The middle of the two axial stator disks 221 and 222 has an annular axial magnetic pole that protrudes in the opposite direction. The two axial magnetic poles are respectively the axial magnetic pole 231 and the axial magnetic pole 232. The magnetic poles 231 and the axial magnetic poles 232 respectively extend to the two axial ends of the rotor 1 correspondingly, and there are axial air gaps 71 and 72 corresponding to the axial ends of the rotor 1 . The axial stator cylinder 21 is sleeved outside the permanent magnet 6 and is fixed with the permanent magnet 6 , that is, the permanent magnet 6 is fixedly embedded between the outer annular surface of the radial stator 3 and the inner annular surface of the axial stator cylinder 21 . Two axial control coils 5 are wound on the inner ring surface of the axial stator cylinder 21, namely the control coil 51 on one side of the axial direction and the axial control coil 52 on the other side of the axial direction. The axial control coil 51 and the axial control coil 52 are connected in series with each other and are wound in the same direction. The radial stator 3 , the radial control coil 4 , the axial control coil 5 and the permanent magnet 6 are all accommodated inside the cylinder enclosed by the axial stator cylinder 21 and the two axial stator disks 221 , 222 .

As shown in FIG. 4, the six radial magnetic poles 32 of the radial stator 3 are radial magnetic poles 321, 322, 323, 324, 325, 326 in sequence, and six radial magnetic poles 321, 322, 323, 324, 325, One radial control coil 4 is wound on each 326, and the six radial control coils 4 are radial control coils 41, 42, 43, 44, 45, and 46 in sequence. The two radial control coils on the two radial magnetic poles 32 facing each other are connected in series and in the same winding direction to form a three-phase coil. The three-phase coil is connected by a star and driven by a three-phase full bridge circuit.

As shown in FIG. 5 , when the present invention works, the permanent magnet 6 generates a bias magnetic flux 91, and the bias magnetic flux 91 flows out from the permanent magnet 6 into the axial stator cylinder 21, and is equally divided into two axial directions at both ends of the axial direction. The stator discs 221 and 222 enter the rotor 1 through the axial air gaps 71 and 72 respectively, flow out from the rotor 1 through the radial air gap 81 and then enter the radial magnetic poles 32 , and then flow through the radial stator yoke 31 and return to the permanent magnets 6, thereby forming a closed bias flux 91. When a forward current is passed through the two axial control coils 51 and 52, the generated axial control magnetic flux 92 flows from one axial stator disk 221 into the axial stator cylinder 21, and flows from the axial stator cylinder 21 to the other shaft To the stator disc 222, then to the rotor 1 via the axial air gap 72, and finally back to the axial stator disc 221 via the axial air gap 71. Since the direction of the bias magnetic flux 91 in the axial air gap 71 at one end is opposite to the direction of the axial control magnetic flux 92 in the axial air gap 71, the bias magnetic flux 91 and the axial control magnetic flux 92 at one end are in opposite directions. The axial air gap 71 is offset, and the axial air gap 72 at the other end is strengthened, thereby generating an axial suspension force to the other end. When the current passing through the two axial control coils 51 and 52 is negative, the bias magnetic flux 91 and the axial control magnetic flux 92 are superimposed in the axial air gap 71 at one end, and the axial air gap 72 at the other end is superimposed. The biasing magnetic flux 92 and the axial control magnetic flux 92 are offset, thereby generating an axial levitation force toward one end of the axial direction. Therefore, the magnitude and direction of the axial suspension force can be controlled by controlling the magnitude and positive and negative of the current in the two axial control coils 51 and 52 .

As shown in FIG. 6 , the bias magnetic flux 91 generated by the permanent magnet 6 enters the radial magnetic poles 321 , 322 , 323 , 324 , 325 , and 326 from the rotor 1 through the radial air gap 81 . When positive current is applied to the radial control coil 41 and the radial magnetic pole 44, the radial control magnetic flux 93 generated on the side of the radial magnetic pole 321 and the radial control coil 41 is in the same direction as the bias magnetic flux 91. The magnetic flux 91 and the radial control magnetic flux 93 are superimposed, and the radial control magnetic flux 93 generated on the opposite side of the radial magnetic pole 324 and the radial control coil 44 is opposite to the direction of the bias magnetic flux 91. The flux 91 and the radial control magnetic flux 93 are canceled, thereby generating a radial suspension force along the radial magnetic poles 321. When the radial control coil 41 and the radial control coil 44 pass negative current, the result is the same as when the radial control coil 41 Contrary to when the radial magnetic pole 44 is supplied with a positive current, a reverse radial suspension force is generated. Similarly, passing a current into the radial control coil 42 and the radial control coil 45 can generate a radial levitation force in the direction of the radial magnetic pole 322 or the radial magnetic pole 325 . The passing of current in the middle can generate a radial levitation force along the direction of the radial magnetic pole 323 or the radial magnetic pole 326 . Therefore, by controlling the currents in the radial control coils 41 , 42 , 43 , 44 , 45 , and 46 , radial levitation forces with different magnitudes in various directions can be generated.

Claims (2)

1. A six-pole radial-axial hybrid magnetic bearing, the outer coaxial sleeve of the rotor (1) is a radial stator (3), characterized in that: the outer coaxial sleeve of the radial stator (3) is provided with an annular permanent The magnet (6), the permanent magnet (6) is coaxially sleeved with an axial stator (2); the radial stator (3) is uniformly arranged with six radial magnetic poles (32) along the circumferential direction, and each radial magnetic pole ( 32) are wound with radial control coils (4), and the two radial control coils (4) on the two facing radial poles (32) are connected in series and in the same winding direction; An annular axial control coil (5) is installed on each side of the end, and the two axial control coils (5) are connected in series and in the same winding direction; the axial stator (2) consists of an axial stator cylinder (21), Two axial stator discs and two axial magnetic poles are formed. Both ends of the axial stator cylinder (21) are fixedly connected with an axial stator disc. The two axial stator discs have the same structure and are symmetrically arranged face to face. The middle of the disc protrudes in the opposite direction and extends annular axial magnetic poles to the axial ends of the rotor (1), and shafts are correspondingly left between the two axial magnetic poles and the axial ends of the rotor (1). The permanent magnet (6) is fixedly embedded between the outer annular surface of the radial stator (3) and the inner annular surface of the axial stator cylinder (21), and the axial control coil (5) is wound around the axial stator cylinder The inner ring surface of (21); the permanent magnet (6) is magnetized in the radial direction, the inner side is the S pole, the outer side is the N pole; the two radial control coils (4) on the two radial magnetic poles (32) facing each other ) to form a three-phase coil, which is connected in a star shape and driven by a three-phase full-bridge circuit; the permanent magnet (6) generates a bias magnetic flux (91), which controls the current flow in the two axial control coils (5). The magnitude and positive and negative can control the magnitude and direction of the axial suspension force, and the current in the six radial control coils (4) can be controlled to generate radial suspension forces of different directions and sizes. 2. A six-pole radial-axial hybrid magnetic bearing according to claim 1, characterized in that: the axial length of the permanent magnet (6) is less than the axial length of the radial stator (3), and the radial stator ( 3) The axial length is smaller than the axial length of the rotor (1).