CN106825627A - A kind of inverter driving ejector half five degree of freedom hybrid magnetic bearing supports electro spindle - Google Patents

Abstract

The invention discloses an inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting an electric spindle. A motor is installed in the middle of the rotating shaft. The front side of the motor is a six-pole radial-axial hybrid magnetic bearing, and the rear side is a six-pole radial Hybrid magnetic bearing, the rotating shaft is fixedly connected with the rotor of the six-pole radial-axial hybrid magnetic bearing and the rotor of the six-pole radial-axial hybrid magnetic bearing; a six-pole radial-axial hybrid magnetic bearing and a six-pole radial-axial hybrid magnetic bearing are used The five degrees of freedom of the rotating shaft are supported by a radial hybrid magnetic bearing with six poles, so that the shaft rotates without friction. Both the radial-axial hybrid magnetic bearing with six poles and the radial hybrid magnetic bearing with six poles provide bias flux by permanent magnets, which greatly The power consumption is reduced, and the six-pole radial-axial hybrid magnetic bearing adopts a six-pole structure in the radial direction, which greatly reduces the nonlinearity and coupling of the levitation force characteristics, and makes it easier to achieve precise control.

Description

An inverter-driven five-degree-of-freedom hybrid magnetic bearing supported electric spindle

technical field

The invention belongs to the field of electric transmission, and relates to a magnetically suspended electric spindle, in particular to a five-degree-of-freedom hybrid magnetic bearing supported electric spindle, which is suitable for high-speed, ultra-high-speed, and high-precision numerical control machine tools.

Background technique

When the motorized spindle rotates at a high speed, the friction of traditional contact bearings will cause a series of problems such as temperature rise of the spindle, thermal deformation, increased vibration, and greatly shortened bearing life. Magnetic suspension bearings (magnetic bearings for short) use electromagnetic force to suspend the rotor in the air, so that there is no contact between the rotor and the stator. With advantages such as long life, it is very suitable for the high-speed, high-precision, and long-life requirements of high-speed electric spindles, and can monitor the position of the rotating shaft in real time, and can also actively suppress the vibration of the rotating shaft. According to the number of degrees of freedom that can be controlled, 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 way the levitation force is generated, it can be divided into active magnetic bearings (the levitation force is generated by the coil current), passive magnetic bearings (the levitation force is generated by the permanent magnet) and hybrid magnetic bearings (the levitation force is generated by the permanent magnet and the coil current).

At present, most of the research on the magnetic levitation electric spindle is aimed at the four-pole or eight-pole magnetic bearing driven by the DC power amplifier, and the DC power amplifier has a large volume, large power consumption, special design of the circuit, and high cost. Therefore, the Chinese patent application number is CN200810234272 A high-speed motorized spindle system supported by an AC magnetic bearing is disclosed in the literature of . The AC magnetic bearing is driven by a three-phase power inverter. The three-phase inverter has low power consumption, mature technology, and low cost, and has a special control chip. , so the development cycle can be greatly reduced, but the electric spindle uses an active three-pole magnetic bearing. The three-pole active magnetic bearing not only needs a coil to provide a bias magnetic field, but also has a large volume and large power consumption, and its nonlinearity and coupling are very Strong, not conducive to precise control.

Contents of the invention

The purpose of the present invention is to reduce power consumption, increase bearing capacity, improve the levitation force characteristics of the five-degree-of-freedom magnetic bearing, thereby improving control accuracy, and propose an inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting electric spindle.

The technical scheme adopted by the inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting the electric spindle of the present invention is as follows: it includes a rotating shaft, a motor is installed in the middle of the rotating shaft, and the front side of the motor is a six-pole radial-axial hybrid magnetic bearing. 1. The rear side is a six-pole radial hybrid magnetic bearing, and the rotating shaft is fixedly connected with the rotor of the six-pole radial-axial hybrid magnetic bearing and the rotor of the six-pole radial hybrid magnetic bearing.

The rotor of the six-pole radial-axial hybrid magnetic bearing is coaxially sleeved at the center of the radial stator composed of radial stator yoke and radial magnetic poles. The radial stator yoke is evenly arranged with 6 radial magnetic poles along the circumferential direction, each Each radial pole is wound with a radial control coil, and the two facing radial control coils are wound in the same direction and connected in series; the radial stator is fixedly sleeved with a ring-shaped permanent magnet, and the permanent magnet is externally fixed with an axial stator; The axial stator is a cylindrical structure with disc end caps at both ends, and the center of the disc end caps extends toward the corresponding two ends of the rotor. The two axial control coils are connected in series.

The rotor of the six-pole radial hybrid magnetic bearing is coaxially sleeved with a stator. The stator is composed of a stator yoke, three active magnetic poles and three permanent magnetic poles. The active magnetic poles and the permanent magnetic poles are arranged alternately, and each active magnetic pole is wound There is a control coil, and a permanent magnet is fixedly inlaid in the middle of each permanent magnet pole.

Compared with the prior art, the present invention has the advantages that: the present invention adopts a six-pole radial-axial hybrid magnetic bearing and a six-pole radial hybrid magnetic bearing to support the five degrees of freedom of the rotating shaft, so that the rotating shaft can rotate without friction , which is conducive to the increase of speed. In addition, both the six-pole radial-axial hybrid magnetic bearing and the six-pole radial hybrid magnetic bearing are provided with bias flux by permanent magnets, which greatly reduces power consumption. The six-pole radial-axial hybrid magnetic bearing adopts radial Compared with the existing inverter-driven hybrid magnetic bearing, the six-pole structure greatly reduces the nonlinearity and coupling of the suspension force characteristics, making it easier to achieve precise control. The radial direction is driven by a three-phase power inverter, reducing the The size and cost of the drive system are reduced.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of an inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting an electric spindle in the present invention;

Fig. 2 is a schematic diagram of the radial structure of the six-pole radial-axial hybrid magnetic bearing in Fig. 1;

Fig. 3 is a schematic diagram of the axial structure of the six-pole radial-axial hybrid magnetic bearing in Fig. 2;

Fig. 4 is a schematic diagram of the radial structure of the six-pole radial hybrid magnetic bearing in Fig. 1;

Fig. 5 is a schematic diagram of the axial structure of the six-pole radial hybrid magnetic bearing in Fig. 4;

In the figure: 1. Rotating shaft; 2. Motor; 3. Six-pole radial-axial hybrid magnetic bearing; 4. Six-pole radial hybrid magnetic bearing; 5. Displacement sensor; 6. Housing; 7. Auxiliary bearing; 8 .end cover; 9. metal disc; 31. rotor; 32. axial stator; 33. radial stator; 34. radial control coil; 35. axial control coil; 36. permanent magnet; 41. active magnetic pole; 42. Permanent magnet pole; 43. Stator yoke; 44. Control coil; 45. Permanent magnet; 46. Rotor; 91. Bias flux; 92. Axial control magnetic field; 93. Radial control flux; 321. Shaft 322. Disc end cover; 331. Radial stator yoke; 332. Radial magnetic pole.

detailed description

As shown in FIG. 1 , the present invention includes a rotating shaft 1 , a high-speed motor 2 , a six-pole radial-axial hybrid magnetic bearing 3 , a six-pole radial hybrid magnetic bearing 4 , a displacement sensor 5 , a casing 6 and an auxiliary bearing 7 . The outside is the casing 6, the front and rear ends of the casing 6 are respectively connected with an end cover 8, and the rotating shaft 1 is installed coaxially at the central axis of the casing 6, and one end of the rotating shaft 1 is connected with the tool, which is the front end of the electric spindle. An auxiliary bearing 7 is coaxially installed at the center of the two end covers 8 at the front end and the rear end, and the rotating shaft 1 passes through the two auxiliary bearings 7 coaxially. support. Inside the casing 6, a high-speed motor 2, a six-pole radial-axial hybrid magnetic bearing 3 and a six-pole radial hybrid magnetic bearing 4 are installed on the rotating shaft 1, the motor 2 is installed in the middle of the rotating shaft 1, and the six poles The radial-axial hybrid magnetic bearing 3 is on the front side of the high-speed motor 2 , and the six-pole radial hybrid magnetic bearing 4 is on the rear side of the high-speed motor 2 . The housing of the motor 2 is fixed on the casing 6 . The rotating shaft 1 is coaxially fixedly connected with the rotor of the six-pole radial-axial hybrid magnetic bearing 3 and the rotor of the six-pole radial hybrid magnetic bearing 4 . A displacement sensor 5 is respectively installed at the front end and the rear end of the rotating shaft 1 , and the displacement sensor 5 is close to the two end covers 8 for detecting the radial displacement of the front end and the rear end of the rotating shaft 1 . In addition, a metal disc 9 is installed on the rear end of the rotating shaft 1 for cooperatively detecting the axial displacement of the rotating shaft 1 .

As shown in Figures 2 and 3, the six-pole radial-axial hybrid magnetic bearing 3 is composed of a rotor 31, an axial stator 32, a radial stator 33, a radial control coil 34, an axial control coil 35 and a permanent magnet 36. . The rotor 31 is coaxially sleeved at the center of the radial stator 33 , and there is a radial air gap between the rotor 31 and the radial stator 33 . The rotor 46 is coaxially and fixedly connected with the rotating shaft 1 . The radial stator 33 is composed of a radial stator yoke 331 and a radial magnetic pole 332. The radial stator yoke 331 is a circular ring, and the inner ring of the radial stator yoke 331 is evenly arranged with six radial magnetic poles 332 along the circumferential direction. There is a radial air gap between the inner surface of the pole 332 and the outer surface of the rotor 31 . Each radial pole 332 is wound with a radial control coil 34 , and the two radial control coils 34 on two radial poles 332 facing each other have the same winding direction and are connected in series to form a phase winding. Six radial control coils 34 form a three-phase winding, and a three-phase inverter is used to control the magnitude and direction of the levitation force. An annular permanent magnet 36 is fixedly socketed outside the radial stator 33, and the permanent magnet 36 is fixedly socketed outside the axial stator 32, so that the permanent magnet 36 is embedded in the axial stator 32 and the radial stator 33 without gaps in the radial direction. between. The permanent magnet 36 is magnetized radially outward, with an N pole at its radially outer end and an S pole at its inner end. The axial stator 32 is a cylindrical structure, and the two ends of the axial stator 32 have disc end covers 322, and the centers of the disc end covers 322 at both ends of the axial stator 32 extend one to the corresponding two ends of the rotor 31. The annular axial magnetic pole 321 has an axial air gap between the axial magnetic pole 321 and the end surface of the rotor 31 . The permanent magnet 36 is embedded between the cylindrical inner wall of the axial stator 32 and the outer annular surface of the radial stator yoke 331 . The axial length of the permanent magnet 36 is smaller than that of the radial stator 33 , and the axial length of the radial stator 33 is smaller than that of the rotor 31 . Therefore, inside the axial stator 32 , there is a certain space between the two ends of the radial stator 33 and the disc end cover of the axial stator 32 . In the cylindrical interior of the axial stator 32, an axial control coil 35 is arranged on the front and rear sides of the radial stator 33, and the two axial control coils 35 on the front and rear sides are connected in series and driven by a DC power amplifier. . The two axial control coils 35 are circular, and are wound along the cylindrical side inner wall of the axial stator 32 beside the front and rear sides of the radial stator yoke 331 , and the winding directions of the two axial control coils 35 are consistent. The axial stator 32 wraps the radial stator 33 , the radial control coil 34 , the axial control coil 35 and the permanent magnet 36 in its cylindrical interior.

When the current is passed into the radial control coil 34, the radial control magnetic flux 93 produced by the radial control coil 34 on one of the radial magnetic poles 332 in the two radial magnetic poles 332 facing each other and the permanent magnet 36 produce The bias magnetic flux 91 is superimposed, and the radial control magnetic flux 93 generated by the radial control coil 34 on the other radial magnetic pole 332 cancels the bias magnetic flux 91, thereby generating levitation along the direction of one of the radial magnetic poles 332 force. When current is passed through the two axial control coils 35, the axial control magnetic field 92 on one side of the axial stator 32 is superimposed on the bias magnetic field 91 generated by the permanent magnet 36, and the axial control magnetic field 92 on the other side Offset with the bias magnetic field 91 generated by the permanent magnet 36 , thereby generating a levitation force in the same direction in the air gap between the stator 32 and the rotor 31 in the axial direction.

As shown in FIG. 4 and FIG. 5 , the six-pole radial hybrid magnetic bearing 4 includes a stator and a rotor 46 , the rotor 46 is coaxially sleeved with the stator, and the rotor 46 is coaxially and fixedly connected with the rotating shaft 1 . The stator is composed of a stator yoke 43 and a stator pole. The stator yoke 43 is circular, and 6 stator poles are evenly arranged on the inner ring surface of the stator yoke 43 along the surrounding direction. There is a radial gap between the 6 stator poles and the rotor 46. air gap. The axial length of the rotor 46 is the same as that of the stator. The six stator poles are composed of three active magnetic poles 41 and three permanent magnetic poles 42, and the active magnetic poles 41 and the permanent magnetic poles 42 are arranged alternately. The interval between each active magnetic pole 41 and two adjacent permanent magnetic poles 42 is 120°, and the interval between each permanent magnetic pole 42 and two adjacent active magnetic poles 41 is 120°. One control coil 44 is wound on each active pole 41 , and the three control coils 44 wound on three active poles 41 form a three-phase coil, which is driven by a three-phase inverter. A permanent magnet 45 is fixedly inlaid in the middle of each permanent magnet pole 42 , and the permanent magnet 45 is used to generate bias magnetic flux. The permanent magnet 45 is radially magnetized, and the inner end of the permanent magnet 45 in the radial direction is an N pole, and the outer end is an S pole. The axial length of the permanent magnet 45 is the same as that of the stator poles.

Passing currents of different magnitudes and directions to the control coils 44 on the three active magnetic poles 41 can generate forces of different magnitudes along the directions of the three active magnetic poles 41, so by adjusting the current in the control coils 44, the desired force can be generated. Suspension required.

Claims (8)

1. An inverter-driven five-degree-of-freedom hybrid magnetic bearing supported electric spindle, including a rotating shaft (1), characterized in that: the middle part of the rotating shaft (1) is equipped with a motor (2), and the front side of the motor (2) It is a six-pole radial-axial hybrid magnetic bearing (3), the rear side is a six-pole radial-axial hybrid magnetic bearing (4), the rotor of the rotating shaft (1) and the six-pole radial-axial hybrid magnetic bearing (3) and The rotors of the six-pole radial hybrid magnetic bearing (4) are all fixedly connected with the shaft center. 2. According to claim 1, an inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting electric spindle is characterized in that: the rotor (31) of the six-pole radial-axial hybrid magnetic bearing (3) is coaxial with the sleeve At the center of the radial stator (33) composed of the radial stator yoke (331) and the radial magnetic poles (332), the radial stator yoke (331) is evenly arranged with 6 radial magnetic poles (332) along the circumferential direction, each Radial control coils (34) are wound on each radial magnetic pole (332), and the two facing radial control coils (34) are wound in the same direction and connected in series; The magnet (36), the permanent magnet (36) is externally fixed and sleeved with the axial stator (32); the axial stator (32) is a cylindrical structure with disc end caps (322) at both ends, and the disc end caps (322 ) at the center of the rotor (31) to extend the axial magnetic poles (321) toward the corresponding two ends of the rotor (31); one axial control coil (35) is respectively arranged on the front and rear sides of the radial stator (33), and the two axial The control coils (35) are connected in series with each other. 3. An inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting electric spindle according to claim 1, characterized in that: the rotor (46) of the six-pole radial hybrid magnetic bearing (4) is coaxially sleeved with a stator , the stator is composed of a stator yoke (43), three active magnetic poles (41) and three permanent magnetic poles (42), the active magnetic poles (41) and the permanent magnetic poles (42) are arranged alternately, each active magnetic pole (41) A control coil (44) is wound on each, and a permanent magnet (45) is fixedly inlaid in the middle of each permanent magnet pole (42). 4. According to claim 2, an inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting the electric spindle is characterized in that: the permanent magnet (36) is magnetized outward in the radial direction, and the radially outer end is The N pole and the inner end are the S pole. 5. An inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting electric spindle according to claim 2, characterized in that: the axial length of the permanent magnet (36) is smaller than the axial length of the radial stator (33), The axial length of the radial stator (33) is smaller than the axial length of the rotor (31). 6. According to claim 3, an inverter-driven five-degree-of-freedom hybrid magnetic bearing supporting the electric spindle is characterized in that: the permanent magnet (45) is radially magnetized, and the inner end in the radial direction is an N pole, The outer end is the S pole; the axial lengths of the rotor (46), the permanent magnet (45) and the stator are the same. 7. According to claim 1, an inverter-driven five-degree-of-freedom hybrid magnetic bearing supports the electric spindle, which is characterized in that: the front and rear ends of the casing (6) are respectively connected to an end cover (8), and the two ends Each coaxial auxiliary bearing (7) is equipped with at the center of the cover (8), and the rotating shaft (1) coaxially passes through the two auxiliary bearings (7). 8. According to claim 1, an inverter-driven five-degree-of-freedom hybrid magnetic bearing supported electric spindle is characterized in that: the front end and the rear end of the rotating shaft (1) are respectively equipped with devices for detecting the radial displacement of the rotating shaft (1). The displacement sensor (5), the rear end of the rotating shaft (1) is equipped with a metal disc (9) for cooperating with detecting the axial displacement of the rotating shaft (1).