CN116658520B - An outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing and parameter design method - Google Patents

Abstract

The invention discloses an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing and parameter design method, comprising a "T"-shaped inner stator and an "H"-shaped outer rotor, wherein the "T"-shaped inner stator comprises an axial and radial iron core, an "H"-shaped magnetic isolation aluminum ring, a trapezoidal permanent magnet, and an axial and radial suspension winding. Six trapezoidal slots for inserting trapezoidal permanent magnets are provided in the magnetic isolation aluminum ring, and the axial iron core and the radial iron core form an integral stator, the axial iron core is wound with an axial suspension winding, and the six poles of the radial iron core are wound with radial suspension windings. The magnetic pole area is designed according to the radial axial maximum suspension force requirement, the magnetic circuit is analyzed, and according to the magnetic circuit superposition theorem, the bias magnetic flux formed by a trapezoidal permanent magnet is calculated, the axial and radial air gap bias magnetic fluxes reach 0.5B _s , the trapezoidal permanent magnet parameters are designed, and finally the number of turns of the axial and radial suspension windings are designed. Compared with the prior art, the invention reduces the cost of the hybrid magnetic bearing, improves the utilization rate of materials, is easy to install, and has small magnetic leakage.

Description

An outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing and parameter design method

Technical Field

The invention relates to a three-degree-of-freedom magnetic suspension bearing, in particular to a new structure outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing and parameter design method that is easy to install and low-cost, and can be used as a contactless suspension bearing for a transmission shaft.

Background technique

The use of magnetic bearings to support the transmission shaft has the advantages of no friction and wear, and it is easier to achieve higher power and higher speed operation. Therefore, the use of magnetic shafts to support high-speed motor rotors has a wide range of application value.

The three-degree-of-freedom AC/DC magnetic bearing integrates the functions of the axial magnetic bearing and the AC radial magnetic bearing, and realizes the axial single-degree-of-freedom and radial two-degree-of-freedom suspension of the rotor in one unit. The use of a three-degree-of-freedom AC/DC hybrid magnetic bearing to replace an axial magnetic bearing and a radial magnetic bearing to support the motor rotor will effectively improve the motor's critical speed, suspension force density and torque density. Therefore, the three-degree-of-freedom magnetic bearing has received extensive attention from the domestic and foreign industrial circles. Various structures of three-degree-of-freedom AC/DC hybrid magnetic bearings have been developed at home and abroad. These three-degree-of-freedom hybrid magnetic bearings all use axially or radially magnetized thin permanent magnet rings to provide bias flux. Thin permanent magnet rings are difficult to process and magnetize, and are expensive and difficult to install. For the large suspension force magnetic levitation bearings required for high-power magnetic levitation motors, the inner diameter of the permanent magnet ring is larger. It is technically difficult to manufacture such a thin permanent magnet ring with a large inner diameter, or the price is high, resulting in high cost of magnetic levitation motors.

Summary of the invention

Purpose of the invention: In view of the problems pointed out in the background technology, the present invention provides an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing and a parameter design method, which replaces the previous axial magnetized permanent magnet ring structure with a trapezoidal slot structure with six trapezoidal permanent magnets inserted therein and evenly distributed along the inner circumference of a magnetic isolation aluminum ring. It only requires inserting the trapezoidal permanent magnets in the trapezoidal slots, which can solve the problem of difficult installation of the permanent magnets, making the permanent magnets easy to process, cheap, and easy to install, thereby reducing the cost of the magnetic bearing and improving the utilization rate of the materials.

Technical solution: The present invention discloses an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing, comprising an "H"-shaped outer rotor and a "T"-shaped inner stator;

The "T"-shaped inner stator includes an axial iron core, a radial iron core, a magnetic isolation aluminum ring, a trapezoidal permanent magnet, a radial suspension winding and an axial suspension winding; the magnetic isolation aluminum ring is "H"-shaped, with 6 trapezoidal slots opened inside, and the trapezoidal permanent magnets are inserted into the trapezoidal slots. The magnetic isolation aluminum ring is arranged between the axial iron core and the radial iron core, and the axial iron core and the radial iron core are inserted into the magnetic isolation aluminum ring to form a stator as a whole. The axial suspension winding is wound on the axial iron core, and the inner circumference of the radial iron core is evenly distributed with 6 poles, and the radial suspension winding is wound on the poles;

The rotating shaft passes through the "H"-shaped outer rotor, and forms a radial air gap with the radial iron core; left and right axial air gaps are formed between the axial iron core and the "H"-shaped outer rotor.

Further, the "H"-shaped outer rotor, the "T"-shaped inner stator, the axial iron core, the radial iron core, the trapezoidal permanent magnet, the rotating shaft, the radial air gap, the left and right axial air gaps constitute a complete axial bias magnetic flux circuit, and the trapezoidal permanent magnet, the radial iron core, the radial air gap, and the rotating shaft constitute a radial bias magnetic flux circuit;

The "H"-shaped outer rotor, the axial iron core, the left and right axial air gaps and the rotating shaft constitute a complete axial controlled magnetic flux circuit, and the radial iron core, the radial air gap and the rotating shaft constitute a complete radial controlled magnetic flux circuit.

Furthermore, the axial inner side of the core and the radial outer side of the core corresponding to the inner and outer sides of the trapezoidal permanent magnet are planes, and the remaining parts are arc surfaces.

Furthermore, the trapezoidal permanent magnets have the same polarity on the same side.

Furthermore, the axial cross-section of the magnetic isolation aluminum ring is "H"-shaped, which is convenient for placing and installing the trapezoidal permanent magnet and for fixing the axial iron core and the radial iron core.

Furthermore, the thickness of the trapezoidal permanent magnet in the magnetizing direction is h _m , the magnetized areas are S _m1 and S _m2 , the axial magnetic pole area S _z and the radial magnetic pole area S _r satisfy S _z = 3S _r , and the vertical projection areas of S _m1 and S _r are equal.

The present invention also discloses a parameter design method for the above outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing, which is calculated based on the magnetic circuit superposition theorem and includes the following steps:

Step 1: Select permanent magnet material and core material, and determine the axial magnetic pole area S _z according to the maximum suspension force requirement F _zmax and the air gap saturation magnetic induction intensity B _s :

Step 2: Set the air gap flux generated by the bias flux in the axial and radial air gaps to be equal, both to 0.5B _s , and calculate the radial magnetic pole area and the radial maximum suspension force respectively:

Step 3: The axial and radial bias flux loops are composed of trapezoidal permanent magnets, radial and axial air gaps, axial cores, radial cores and rotor cores. The equivalent magnetic circuit is: six radial air gap reluctances are connected in parallel, six trapezoidal permanent magnet reluctances are connected in parallel, two axial air gap reluctances are connected in parallel, and finally the three are connected in series.

Step 4: Using the magnetic circuit superposition theorem, the magnetomotive force _Fm of a single trapezoidal permanent magnet, the magnetic reluctance _Rm of a single trapezoidal permanent magnet, the magnetic reluctance _Rz of a single axial air gap, the magnetic reluctance _Rr of the air gap under each radial magnetic pole, and the total magnetomotive force _Fc of a single trapezoidal permanent magnet in the magnetic circuit are expressed as follows:

Step 5: According to the selected rare earth permanent magnet material, determine the relationship between the coercive force _Hc and _hm of the permanent magnet as follows:

Step 6: Assuming that the axial length of the axial core and the radial core is L, the inner radius _R1 of the radial core is calculated from _Sr :

Wherein, η is the polar arc coefficient;

Step 7: Calculate the radial magnetic pole arc angle θ ₁ : θ ₁ =η×60°;

Step 8: Calculate S _m1 and the length of the lower side of the permanent magnet L _m1 :

Step 9: Select the inner diameter R ₂ of the magnetic isolation aluminum ring and calculate half of the angle θ ₂ between the two sides of the trapezoid:

Step ₁₀ : Determine the outer diameter _R3 of the magnetic isolation aluminum ring and the upper length _Lm2 of the permanent magnet: _R3 = _R2 + _hm / _cosθ2 , _Lm2 = _Lm1 + _2hmtanθ2 ;

Step 11: Calculate the number of axial suspension winding turns on each side and the number of ampere-turns of radial suspension winding on each pole:

Step 12: Calculate

Beneficial effects:

The present invention replaces the thin permanent magnet ring structure with 6 trapezoidal permanent magnets evenly distributed along the inner circumference. It only needs to insert 6 trapezoidal permanent magnets into the trapezoidal grooves. Compared with the three-degree-of-freedom hybrid magnetic bearing using one permanent magnet ring, it is easy to install, easy to process, cheap, reduces the cost of magnetic bearings, improves material utilization, and has low magnetic leakage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a radial subdivision and radial control magnetic path diagram of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing;

FIG2 is a diagram showing radial segmentation and radial bias magnetic flux direction of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing;

FIG3 is a diagram showing the axial splitting, axial bias magnetic path and axial control magnetic path of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing;

FIG4 is an equivalent magnetic circuit diagram of an axial bias magnetic field of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing;

FIG. 5 is a diagram showing the geometric relationship of permanent magnets of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing.

Among them, 1- "H"-shaped outer rotor, 2- "T"-shaped inner stator, 3-axial iron core, 4-radial iron core, 5-magnetic isolation aluminum ring, 6-trapezoidal permanent magnet, 7-radial suspension winding, 8-axial suspension winding, 9-rotating shaft, 10-radial air gap, 11-axial bias flux circuit, 12-axial control flux circuit, 13-left axial air gap, 14-right axial air gap, 15-radial control flux circuit, 16-radial bias flux circuit.

Detailed ways

The technical solution of the present invention is further described below in conjunction with the accompanying drawings. Figure 1 is a diagram of radial subdivision and radial control magnetic path of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing; Figure 2 is a diagram of radial subdivision and radial bias magnetic flux direction of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing; Figure 3 is a diagram of axial subdivision, axial bias magnetic path and axial control magnetic path of an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing.

FIG. 4 is an equivalent magnetic circuit diagram of the axial bias magnetic field of the outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing.

FIG5 is a diagram showing the geometric relationship of the permanent magnets of the outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing.

The present invention discloses an outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing, the structure of which includes an "H"-shaped outer rotor 1 and a "T"-shaped inner stator 2. The "H"-shaped outer rotor 1 facilitates the installation of the "T"-shaped inner stator. The "T"-shaped inner stator 2 includes an axial iron core 3, a radial iron core 4, a magnetic isolation aluminum ring 5, a trapezoidal permanent magnet 6, a radial suspension winding 7 and an axial suspension winding 8; the magnetic isolation aluminum ring 5 is "H"-shaped, with 6 trapezoidal slots opened inside, and the trapezoidal permanent magnet 6 is inserted into the slot. The magnetic isolation aluminum ring 5 is arranged between the axial iron core 3 and the radial iron core 4, and the axial iron core 3 and the radial iron core 4 are inserted into the magnetic isolation aluminum ring 5 to form a stator as a whole. The axial suspension winding 8 is wound on the axial iron core 3, and 6 poles are evenly distributed on the inner circumference of the radial iron core 4, and the radial suspension winding 7 is wound on the poles.

The rotating shaft 9 passes through the “H”-shaped outer rotor 1, and a radial air gap 10 is formed between the rotating shaft 9 and the radial iron core 4. The left and right axial air gaps 13 and 14 are formed between the axial iron core 3 and the “H”-shaped outer rotor 1.

The "H"-shaped outer rotor 1, the "T"-shaped inner stator 2, the axial iron core 3, the radial iron core 4, the trapezoidal permanent magnet 6, the rotating shaft 9, the radial air gap 10, the left and right axial air gaps 13 and 14 constitute a complete axial bias magnetic flux circuit 11, and the trapezoidal permanent magnet 6, the radial iron core 4, the radial air gap 10, and the rotating shaft 9 constitute a radial bias magnetic flux circuit 16.

The “H”-shaped outer rotor 1, the axial iron core 3, the left and right axial air gaps 13, 14 and the rotating shaft 9 constitute a complete axial controlled magnetic flux circuit 12, and the radial iron core 4, the radial air gap 10 and the rotating shaft 9 constitute a complete radial controlled magnetic flux circuit 15.

The inner side of the axial core 3 and the outer side of the radial core 4 corresponding to the inner and outer sides of the trapezoidal permanent magnet 6 are planes, and the rest are arc surfaces. The same side of the trapezoidal permanent magnet 6 has the same polarity.

The axial cross section of the magnetic isolation aluminum ring 5 is "H" shaped, which is convenient for placing and installing the trapezoidal permanent magnet 6 and fixing the axial iron core 3 and the radial iron core 4. The thickness of the trapezoidal permanent magnet 6 in the magnetizing direction is h _m , and the magnetized areas are S _m1 and S _m2 .

The axial magnetic pole area _Sz and the radial magnetic pole area _Sr satisfy _Sz = _3Sr , and the vertical projection areas of _Sm1 and _Sr are equal.

The specific steps of the parameter design method of the above outer rotor radial six-pole three-degree-of-freedom AC/DC hybrid magnetic bearing are as follows:

Step 1: Select permanent magnet material and core material, and determine the axial magnetic pole area S _z according to the maximum suspension force requirement F _zmax and the air gap saturation magnetic induction intensity B _s :

Step 2: To make full use of the material, the air gap flux generated by the bias flux in the axial and radial air gaps is equal, both 0.5B _s . The radial magnetic pole area and the radial maximum suspension force can be calculated as follows:

Step 3: The axial and radial bias flux circuits are composed of trapezoidal permanent magnets, radial and axial air gaps, axial cores, radial cores and rotor cores. The equivalent magnetic circuit is: six radial air gap reluctances in parallel, six trapezoidal permanent magnet reluctances in parallel, two axial air gap reluctances in parallel, and finally the above three are connected in series, as shown in Figure 4.

Step 4: Using the magnetic circuit superposition theorem, the magnetomotive force _Fm of a single trapezoidal permanent magnet, the magnetic reluctance _Rm of a single trapezoidal permanent magnet, the magnetic reluctance _Rz of a single axial air gap, the magnetic reluctance _Rr of the air gap under each radial magnetic pole, and the total magnetomotive force _Fc of a single permanent magnet in the magnetic circuit are expressed as follows:

Step 5: According to the selected rare earth permanent magnet material, determine the relationship between the coercive force _Hc and _hm of the permanent magnet as follows:

Step 6: Assuming that the axial length of the axial core and the radial core is L, the inner radius _R1 of the radial core can be calculated from _Sr :

Among them, η is the pole arc coefficient, which is generally between 0.9 and 0.95.

Step 7: Calculate the radial magnetic pole arc angle θ ₁ : θ ₁ = η×60°.

Step 8: Referring to Figure 5, calculate S _m1 and the length of the lower side of the trapezoidal permanent magnet L _m1 :

Step 9: Select the appropriate inner diameter R ₂ of the magnetic isolation aluminum ring and calculate half of the angle θ ₂ between the two sides of the trapezoid:

Step ₁₀ : Determine the outer diameter _R3 of the magnetic isolation aluminum ring and the upper length _Lm2 of the trapezoidal permanent magnet: _R3 = _R2 + _hm / _cosθ2 , _Lm2 = _{Lm1 +} 2hmtanθ2.

Step 11: Calculate the number of axial suspension winding turns on each side and the number of ampere-turns of radial suspension winding on each pole:

Step 12: You can calculate The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims (7)

1. The outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing is characterized by comprising an H-shaped outer rotor (1) and a T-shaped inner stator (2);

the T-shaped inner stator (2) comprises an axial iron core (3), a radial iron core (4), a magnetism isolating aluminum ring (5), a trapezoidal permanent magnet (6), a radial suspension winding (7) and an axial suspension winding (8); the magnetic aluminum isolating ring (5) is H-shaped, 6 trapezoid grooves are formed in the magnetic aluminum isolating ring, trapezoid permanent magnets (6) are inserted into the trapezoid grooves, the magnetic aluminum isolating ring (5) is arranged between the axial iron core (3) and the radial iron core (4), the axial iron core (3) and the radial iron core (4) are inserted into the magnetic aluminum isolating ring (5) to form a stator whole, an axial suspension winding (8) is wound on the axial iron core (3), 6 poles are uniformly distributed on the inner circumference of the radial iron core (4), and a radial suspension winding (7) is wound on the poles;

The rotating shaft (9) penetrates through the H-shaped outer rotor (1) and forms a radial air gap (10) with the radial iron core (4); a left axial air gap (13) and a right axial air gap (14) are formed between the axial iron core (3) and the H-shaped outer rotor (1).

2. The outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing according to claim 1, wherein the 'H' -shaped outer rotor (1), 'T' -shaped inner stator (2), axial iron core (3), radial iron core (4), trapezoidal permanent magnet (6), rotating shaft (9), radial air gap (10), left and right axial air gaps (13, 14) form a complete axial bias magnetic flux loop (11), and the trapezoidal permanent magnet (6), radial iron core (4), radial air gap (10) and rotating shaft (9) form a radial bias magnetic flux loop (16);

The H-shaped outer rotor (1), the axial iron core (3), the left axial air gap (13), the right axial air gap (14) and the rotating shaft (9) form a complete axial control magnetic flux loop (12), and the radial iron core (4), the radial air gap (10) and the rotating shaft (9) form a complete radial control magnetic flux loop (15).

3. The outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing according to claim 1, wherein: the inner side of the axial iron core (3) and the outer side of the radial iron core (4) corresponding to the inner side and the outer side of the trapezoidal permanent magnet (6) are planes, and the rest parts are arc surfaces.

4. The outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing according to claim 1, wherein: the same side polarity of the trapezoid permanent magnet (6) is the same.

5. The outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing according to claim 1, wherein: the axial section of the magnetism isolating aluminum ring (5) is H-shaped, so that the trapezoidal permanent magnet (6) can be conveniently placed and installed, and the axial iron core (3) and the radial iron core (4) can be conveniently fixed.

6. The outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing according to claim 5, wherein: the thickness of the trapezoid permanent magnet (6) in the magnetizing direction is h _m, the magnetizing areas are S _m1 and S _m2, and the axial magnetic pole area S _z and the radial magnetic pole area S _r meet the requirement that the perpendicular projection areas of S _z＝3S_r,S_m1 and S _r are equal.

7. The parameter design method based on the outer rotor radial six-pole three-degree-of-freedom alternating current-direct current hybrid magnetic bearing of claim 6 is characterized by comprising the following steps of:

step 1: selecting permanent magnet materials and iron core materials, and determining an axial magnetic pole area S _z according to the maximum levitation force requirement F _zmax and the air gap saturation induction intensity B _s:

Step 2: the magnetic densities of the air gaps generated by the bias magnetic flux in the axial air gap and the radial air gap are set to be equal and are 0.5B _s, and the area of the radial magnetic pole and the maximum radial levitation force are calculated as follows:

step 3: the axial and radial bias magnetic flux loops are composed of a trapezoidal permanent magnet, radial and axial air gaps, an axial iron core, a radial iron core and a rotor iron core, and the equivalent magnetic circuit is as follows: six radial air gap magnetic resistances are connected in parallel, six trapezoidal permanent magnet magnetic resistances are connected in parallel, two axial air gap magnetic resistances are connected in parallel, and finally the three are connected in series;

Step 4: magnetomotive force F _m of a single trapezoidal permanent magnet in a magnetic circuit, magnetic resistance R _m of the single trapezoidal permanent magnet, magnetic resistance R _z of a single axial air gap and magnetic resistance R _r of an air gap under each radial magnetic pole are expressed as total magnetomotive force F _c of the single trapezoidal permanent magnet by adopting a magnetic circuit superposition theorem:

step 5: according to the selected rare earth permanent magnet material, the relation between the coercive force H _c and the coercive force H _m of the permanent magnet is determined as follows:

F_c＝H_c×h_m，

Step 6: assuming that the axial length of the axial core and the radial core is L, the radial core inner radius R ₁ is determined from S _r as:

Wherein eta is the polar arc coefficient;

Step 7: solving radial magnetic arc angle θ ₁：θ₁ =ηx60°;

Step 8: s _m1 and the length L _m1 of the lower side of the permanent magnet are calculated:

Step 9: selecting the inner diameter R ₂ of the magnetism isolating aluminum ring, and calculating half theta ₂ of an included angle between two waists of the trapezoid:

step 10: determining the outer diameter R ₃ of the magnetism isolating aluminum ring and the upper side length of the permanent magnet L_m2：R₃＝R₂+h_m/cosθ₂,L_m2＝L_m1+2h_m tanθ₂;

Step 11: the number of turns of each axial suspension winding and the number of ampere turns of each radial suspension winding on each pole are calculated:

Step 12: calculation of