CN201121656Y - Radial-axial hybrid magnetic bearings driven by radial four-pole two-phase AC - Google Patents

Abstract

The utility model discloses a radial-axial hybrid magnetic bearing driven by a radial four-pole two-phase AC. The permanent magnet is circular and radially magnetized, and is embedded in a circular groove inside the axial stator. , which is closely connected with the outside of the radial four-pole stator, and provides radial and axial bias flux at the same time; The four poles of the stator are evenly distributed along the circumference and placed between the axially opposite axial stator poles; the rotor is stacked on the rotating shaft by circular silicon steel sheets, forming an axial air gap with the axial stator, and forming an axial air gap with the radial stator. Both the axial stator and the axial stator form a radial air gap; the axially opposite axial control coils are energized in series to generate axial control magnetic flux; each radial control coil is wound on the outer rings of two axially opposite axial stator poles, Radial control magnetic flux is generated after electrification, which reduces the volume of the power amplifier, reduces the cost of the power amplifier, simplifies the driving control method, and improves the working efficiency of the magnetic bearing.

Description

Radial-axial hybrid magnetic bearings driven by radial four-pole two-phase AC

technical field

The utility model belongs to the technical field of electromechanical transmission equipment, belongs to the field of magnetic bearings without any mechanical contact, in particular refers to a new radial-axial hybrid magnetic bearing driven by radial four-pole two-phase AC, which is suitable for various The three-degree-of-freedom suspension support of similar rotating machinery can be used as a non-contact suspension support for rotating parts in mechanical equipment such as five-degree-of-freedom magnetic levitation high-speed machine tool electric spindle systems.

Background technique

With the rapid development of magnetic bearing technology in the 1970s, magnetic bearing researchers at home and abroad focused on the study of active axial single-degree-of-freedom and radial two-degree-of-freedom magnetic bearings. The signal provides both static bias flux and control flux. Any stable rotating system rotor needs to impose constraints on its five degrees of freedom, so usually one axial single-degree-of-freedom magnetic bearing and two two-degree-of-freedom radial magnetic bearings are used to form a five-degree-of-freedom suspension support system . On the one hand, the radial two-degree-of-freedom magnetic bearing and the axial single-degree-of-freedom magnetic bearing both occupy a large axial space, resulting in a long axial length and a large volume of the motor shaft supported by the magnetic bearing; at the same time, the critical speed of the rotor decreases , the development of motors or various types of rotating spindles to higher speeds and power is limited; on the other hand, using DC control, DC power amplifiers are expensive and bulky, and a radial magnetic bearing usually requires four unipolar (or two Road bipolar) power amplifier circuit, which directly leads to the large volume and high cost of the magnetic bearing, which greatly limits its application fields, especially in the fields of aerospace and military applications.

Therefore, researchers began to work on improving and optimizing the above two aspects. At the Seventh International Magnetic Bearing Conference in 2000, Redemann.C of the Swiss Federal Institute of Technology (ETH) in Zurich published a test report on the application of a 30kW bearingless sealed pump, and studied a two-degree-of-freedom three-phase AC hybrid magnetic bearing. The magnetic bearing directly adopts the three-phase inverter commonly used in the industry to provide the control current, and uses the permanent magnet to provide the static bias magnetic field, which greatly reduces the size of its power amplifier and reduces the loss, but it still needs to be combined with an axial active magnetic bearing In order to realize the three-degree-of-freedom suspension support, there is still no progress in the compact axial structure of the overall system, the improvement of the critical speed of the rotor, and the improvement of the bearing capacity of the magnetic bearing.

The relevant existing domestic patent applications are as follows: (1) a low-power permanent magnet bias outer rotor radial magnetic bearing (patent publication number: CN1644940); (2) permanent magnet bias radial magnetic bearing (patent Publication number: CN1693726); (3) A radial magnetic bearing with permanent magnet bias outer rotor (patent publication number: CN1730960); (4) Three-degree-of-freedom AC-DC radial-axial hybrid magnetic bearing and its control method ( Patent publication number: CN1737388); (5) A permanent magnetic bias axial hybrid magnetic bearing (patent publication number: CN101025198); (6) three-degree-of-freedom AC hybrid magnetic bearing (patent publication number: CN101038011).

The magnetic bearing proposed in the above patent 1 uses a double-sided eight-pole structure to control the two degrees of freedom in the radial direction, and uses 8 radial excitation coils, and the radial direction is driven and controlled by a DC power amplifier. The defect is the mechanical structure of the coil Large size and high power loss. Patent 2 proposes to use two pairs of poles in the radial direction, and the windings on the two opposite teeth are connected in series to control the two degrees of freedom in the radial direction. The disadvantage is that the bearing capacity of the magnetic bearing is small. The magnetic bearing of patent 3 adopts 8 stator core magnetic poles evenly distributed on the circumference, which is surrounded by an excitation coil, and 4 permanent magnets are embedded in the stator core. The disadvantage is high power loss. The three-degree-of-freedom AC hybrid magnetic bearings proposed in patents 4 and 6 all adopt a single-sided three-pole radial stator and a disc-type axial stator structure, and an axial air flow is formed between the rotor and the air axial stator and radial stator respectively. Gap and radial air gap, the disadvantage is that the available magnetic pole effective area of the magnetic bearing is small, and the bearing capacity is small. The axial hybrid magnetic bearing of patent 5 also adopts an axial stator disc structure, and the control coils are respectively placed between two axial stator discs, and an axial air gap is formed between the rotor and the axial stator and radial stator respectively. and radial air gap, but does not specify how many poles are used.

Contents of the invention

The purpose of this utility model is to increase the layout space of the control coil, increase the effective area of the magnetic pole of the magnetic bearing, further reduce the volume of the mechanical structure of the magnetic bearing, improve its bearing capacity, and design a kind of structure with reasonable and compact structure, small axial length and high bearing capacity. Large, good stability and high efficiency, while controlling the axial degree of freedom and radial two degrees of freedom AC-DC hybrid magnetic bearings, thereby reducing the axial size of the electric spindle or various rotating spindles that require suspension support, so that the system's The critical speed is further increased, and the volume and cost of the power amplifier are greatly reduced, so that this type of magnetic bearing can be widely used in suspension support systems such as ultra-high-speed ultra-precision CNC machine tools, magnetic levitation bearingless motors, flywheel energy storage systems, and artificial satellites. application.

The technical solution adopted by the utility model is: comprising a permanent magnet close to the radial stator, a radial control wire, an axial control coil wound on the axial stator, and a rotor sleeved on the rotating shaft; the permanent magnet is annular and Radial magnetization, made of rare earth material neodymium iron boron (NdFeB), embedded in the annular groove on the inner side of the axial stator, closely connected with the outer side of the radial quadrupole stator, providing radial and axial bias magnetism at the same time Magnetic flux; the four poles of the radial stator are evenly distributed along the circumference, and each radial stator pole is placed between two axially opposite axial stator poles; the rotor is stacked on the rotating shaft by circular silicon steel sheets , form an axial air gap with the axial stator, and form a radial air gap with both the radial stator and the axial stator; the axial control coils on the axially opposite axial stator poles are connected in series, and the axial control magnetic flux is generated after energization ; Each radial control coil is wound on the outer rings of two axially opposite axial stator poles, and generates radial control magnetic flux after electrification.

The axial stator adopts a double-piece eight-pole structure with 2 pieces × 4 poles. Each piece on the left and right sides is composed of 4 radial-axial double magnetic pole surface iron cores evenly distributed along the circumference. Dual pole faces.

The beneficial effects of the utility model are:

1. Traditional DC radial two-degree-of-freedom magnetic bearings require four-way unipolar (or two-way bipolar) power amplifier circuits, but a new type of radial four-pole two-phase AC driven radial- The axial hybrid magnetic bearing can completely drive and control the two degrees of freedom in the radial direction with only one two-phase AC inverter, thus reducing the volume of the power amplifier, reducing the cost of the power amplifier, simplifying the driving control method, and greatly improving the performance of the magnetic bearing. work efficiency.

2. The permanent magnet is used to provide axial and radial static biasing magnetic field at the same time, and the control coil only provides a dynamic magnetic field to balance the load and external interference. Therefore, the number of ampere turns of the control coil is greatly reduced, further reducing the volume of the magnetic bearing. The weight of the magnetic bearing is reduced; at the same time, because there is no need to provide a bias current, the power loss is reduced, energy is saved, and the volume of the radiator of the power amplifier is reduced.

3. The axial stator adopts a double-piece eight-pole radial-axial double magnetic pole surface structure, the radial stator adopts a four-pole structure uniformly distributed along the circumference, and the axial control coil and radial control coil are distributed in two layers inside and outside, greatly The layout space of the control coil is increased, which provides conditions for the coil ampere-turns required by the magnetic bearing to overcome greater external disturbances and loads.

4. The axial coil and the radial coil adopt DC and AC drive control respectively, and the magnetic fields are independent of each other and are easy to control; there is a certain coupling between the radial two degrees of freedom, but the two-phase AC decoupling method can be used to control the radial two degrees of freedom. degree of control.

5. The bearing capacity of the magnetic bearing depends on the magnetomotive force inside the permanent magnet and the effective magnetic pole area. The radial air gap is formed between the rotor and the radial stator and the axial stator, which greatly increases the radial effective magnetic pole area.

Description of drawings

Fig. 1 is an axial sectional view of the utility model;

Fig. 2 is a radial sectional view of the utility model;

In the figure: 1. stator, 2. radial control coil, 3. axial stator, 4. axial air gap, 5. radial air gap, 6. rotor, 7 rotating shaft, 8. axial control coil, 9. Permanent magnets;

The solid line 10 with arrow is the static bias magnetic circuit that ring type permanent magnet 9 produces;

The dotted line 11 with arrows is the loop formed by the axial control magnetic flux between the axial stator 3, the axial air gap 4 and the rotor 6;

The dotted line 12 with the arrow represents the loop formed by the radial control magnetic flux between the two radially opposite magnetic poles and the yoke connecting them, the radial air gap 5 and the rotor 6;

Fig. 3 is the left side view of section A-A among Fig. 1;

Fig. 4 is a right view of section B-B in Fig. 1 .

Detailed ways

The utility model first constructs a radial-axial hybrid magnetic bearing structure and a magnetic circuit driven by a radial four-pole two-phase AC, and constructs its mathematical model according to an equivalent magnetic circuit method. Based on this mathematical model combined with the predetermined design parameters, the structural parameters and electrical parameters of the magnetic bearing are formulated and calculated, and a magnetic bearing with excellent performance that meets the requirements of practical applications is designed according to this formula. Based on these structural parameters, use Maxwell 3D in the finite element analysis software ANSOFT software to further optimize the design of the magnetic bearing structural parameters, and verify the correctness of the structural design principles and magnetic flux distribution. Finally, according to the mathematical model and various actual parameters, the controller is designed, and the (displacement, current) double closed-loop control system, axial DC power amplifier circuit and radial AC power inverter circuit are constructed.

The principle of the utility model is to construct a brand-new magnetic circuit, so that the radial and axial directions can fully share the static bias magnetic flux provided by the permanent magnet without coupling, thus integrating the radial two degrees of freedom and the axial freedom The combined control of the degree of freedom saves space and facilitates the increase of the ampere-turns of the control coil. Compared with the combination of the two-degree-of-freedom magnetic bearing and the single-degree-of-freedom magnetic bearing, the space occupied by the magnetic bearing in the axial direction is greatly reduced and the increase The layout space of the control coil is reduced; at the same time, a two-phase AC inverter is used to drive and control the radial control current of the magnetic bearing, which reduces the number of power devices, is simple to control, saves manufacturing costs, and improves work efficiency.

The specific scheme of the utility model is: as shown in Figures 1 to 4, the utility model includes a radial four-pole stator 1 uniformly distributed along the circumference, a radial control coil 2, and a double-piece eight-pole radial-axial double magnetic pole The axial stator 3, the axial air gap 4, the radial air gap 5, the rotor 6, the rotating shaft 7, the axial control coil 8 and the permanent magnet 9 are composed of a planar structure. A circular permanent magnet 9 with radial magnetization provides both axial and radial static bias fluxes. The permanent magnet material is made of high-performance rare earth permanent magnet material NdFeB (NdFeB), which is divided into 4 pieces, which is convenient for permanent magnetization. The magnet 9 is processed and embedded in the stator, and then spliced into a ring-shaped permanent magnet 9 embedded in the ring-shaped groove inside the stator. The axial stator 3 adopts a double-piece eight-pole (2 pieces × 4 poles) radial-axial double magnetic pole surface structure, and each piece on the left and right sides is composed of 4 radial-axial double magnetic pole surface iron cores evenly distributed along the circumference Composition: Four-pole radial stator 1 magnetic poles are evenly distributed along the circumference, and each radial stator 1 magnetic pole is placed between two axially opposite axial stator 3 magnetic poles. According to the requirements of the magnetic circuit, its mechanical structure and component structure are constructed; the magnetic circuit components must have good magnetic permeability, low hysteresis, and minimize eddy current loss and hysteresis loss, thus determining the rotor 6, the axial stator 3 and the radial The stator 1 is made of laminated silicon steel sheets, while the rotating shaft 7 is made of electrical pure iron. The rotor 6 is laminated on the rotating shaft by circular silicon steel sheets, forming an axial air gap 4 with the axial stator 3 , and forming a radial air gap 5 with both the axial stator 3 and the radial stator 1 . Two axial control coils 8 on two axially opposite axial stators 3 magnetic poles are connected in series to generate axial control magnetic flux; radial control coils 2 are wound on the outer rings of axially opposite two axial stators 1 magnetic poles , through two-phase alternating current to generate radial control flux.

The bias magnetic flux provided by the permanent magnet 9 flows out from the N pole of the annular permanent magnet 9, flows through the left and right parts of the axial stator 3 in a balanced manner, and then flows in through the axial air gap 4, the rotor 6, and the radial air gap 5 in sequence. Radial stator 1, finally back to the S pole of the permanent magnet 9. The axial control magnetic flux is shown by the dotted line 11 with an arrow in the figure. After the axial control coil 8 is supplied with direct current, an axial control magnetic flux circuit is formed between the axial stator 3, the axial air gap 4 and the rotor 6. , changing the direction and magnitude of the control current will control the magnitude and direction of the magnetic flux to change accordingly. The radial control coil 2 on the two magnetic poles that are radially 90° to each other is fed with a two-phase balanced alternating current to form a radial control magnetic flux between the axial stator 3 and the radial stator 1, the radial air gap 5, and the rotor 6 Loop 12 generates rotating synthetic flux to overcome external disturbances or loads; the same is true for the radial control coils 2 on the other two magnetic poles, so that a strengthened synthetic rotating flux is obtained, so that the magnetic bearing can overcome greater external disturbances and load.

Claims (3)

1, a kind of radial-axial hybrid magnetic bearing of radially four utmost point two-phase alternating currents driving, comprise with the close permanent magnet (9) of radial stator (1), radially control coil (2), axial control coil (8), rotor (6) on axial stator (3) are enclosed within the rotating shaft (7), it is characterized in that: permanent magnet (9) is circular shape and radial magnetizing, adopt the rare earth material neodymium iron boron to make, be embedded in the inboard circular shape groove of axial stator (3), closely link to each other with four pole radial stators (1) outside, radial and axial magnetic bias magnetic flux is provided simultaneously; Four utmost points of radial stator (1) evenly distribute along circumference, and each radial stator (1) magnetic pole all places respectively between axially relative 2 axial stator (3) magnetic pole; Rotor (6) is sleeved in the rotating shaft (7) by the ring silicon steel plate stacking, forms axial air-gap (4) with axial stator (3), all forms radial air gap (5) with radial stator (1) and axial stator (3); Axial control coil (8) series connection on axially relative axial stator (3) magnetic pole, energising back produce axially control magnetic flux; Radially control coil (2) is on axially relative 2 axial stator (3) outer ring for each, and the energising back produces radially controls magnetic flux.

2, the radial-axial hybrid magnetic bearing that drives according to described radially four utmost point two-phase alternating currents of claim 1, it is characterized in that: axial stator (3) adopts the double-disk ends of the earth structure of 2 * 4 utmost points, every of the left and right sides is formed along the two magnetic pole strength iron cores of the equally distributed radial-axial of circumference by 4, and every utmost point has radial-axial pair magnetic pole strengths.

3, the radial-axial hybrid magnetic bearing that drives according to described radially four utmost point two-phase alternating currents of claim 1 is characterized in that: radially control coil (2) adopts a two-phase alternating current inverter to carry out drive controlling.

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