Active radial magnetic bearing and design method thereof, compressor, and air conditioner

Abstract

The present invention provides an active radial magnetic bearing and a design method thereof, a compressor, and an air conditioner, wherein the active radial magnetic bearing comprises a stator core, wherein the stator core comprises a ring-shaped core yoke and a plurality of core teeth located on the inner circumference of the core yoke, wherein the circumferential widths of the plurality of core teeth are all x, the radial width of the core yoke is y, and x / y>1. According to the present invention, when the material of the core teeth can achieve a better utilization rate, the material of the core yoke can also achieve a better utilization rate, so that the bearing capacity or support stiffness of the magnetic bearing can be better when the volume of the active radial magnetic bearing is constant, and the disadvantage of increasing the overall volume and cost due to increasing the design size of the bearing in order to improve the bearing capacity or support stiffness of the magnetic bearing can be avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of motor manufacturing, and specifically relates to an active radial magnetic suspension bearing and a design method thereof, a compressor, and an air conditioner. Background Art

[0002] Active magnetic bearings use controllable electromagnetic force to suspend the rotating shaft. To ensure that the rotor maintains stable suspension and has high operating accuracy, the magnetic bearings need to provide sufficiently large load-bearing capacity and support stiffness.

[0003] A common active magnetic suspension radial bearing includes a stator core 100, a stator winding 200, a rotor core 300, and a rotating shaft 400. There is an air gap 500 between the stator and the rotor. Figure 4 (n=4 is used as an example in the figure), the stator core 100 includes a yoke 101, 2n teeth 102 of equal width and 2n coil cavities 103, where n is generally an integer greater than 3, and 2n stator windings 200 are installed on the 2n teeth 102. The 2n teeth 102 and the stator windings 200 are divided into n groups. When a control current is passed through one of the windings, the following will be generated: Figure 4 The magnetic circuit shown (n=4 is taken as an example in the figure), in which the magnetic circuit is mainly along the main magnetic circuit (6a), but there will also be a leakage magnetic circuit (6b), and the leakage magnetic circuit (6b) shown in Figure x is only a partial example. In general, it is believed that the magnetic circuit is only along the main magnetic circuit (6a), that is, passing through the adjacent stator teeth 102, the adjacent air gap 500 and the stator yoke 101 and the rotor core 300 part therebetween. Therefore, in order to ensure the uniformity of the magnetic circuit, the width of the pole / tooth 102 of the radial magnetic suspension bearing stator and the yoke 101 between adjacent teeth of the same group are designed to be equal. However, due to the existence of the leakage magnetic circuit (6b), a small part of the magnetic lines of force passing through the stator teeth will not pass through the yoke between adjacent teeth, resulting in the magnetic saturation intensity of the stator teeth 102 being slightly higher than the yoke 101. When the tooth material reaches the optimal utilization rate, the yoke material does not reach the optimal utilization rate, so the optimal electromagnetic solution for the bearing under this size is not achieved. Summary of the invention

[0004] Therefore, the present invention provides an active radial magnetic bearing and a design method thereof, a compressor, and an air conditioner, which can overcome the deficiency in the related art that in the equal-width design of the core, tooth, and yoke of the active radial magnetic bearing, the influence of the leakage magnetic circuit of the bearing stator core is not considered, resulting in that when the material of the core tooth portion reaches a better utilization rate, the material of the core yoke portion does not reach a better utilization rate.

[0005] In order to solve the above problems, the present invention provides an active radial magnetic bearing, including a stator core, wherein the stator core includes a ring-shaped core yoke and a plurality of core teeth on the inner circumferential side of the core yoke, wherein the circumferential width of the plurality of core teeth is x, the radial width of the core yoke is y, and x / y>1.

[0006] Preferably, x / y≤1.8.

[0007] Preferably, 1.05≤x / y≤1.3.

[0008] Preferably, x<πd / (2n)-2g, wherein d is the inner diameter of the stator core, g is the radial thickness of the stator-rotor air gap formed between the stator core and the rotor core, and 2n is the number of teeth of the core.

[0009] Preferably, 0.3<2nx / πd<0.85.

[0010] Preferably, the active radial magnetic bearing further comprises a rotor core which is sleeved on the rotating shaft, and the radial thickness of the rotor core is z, where z / y>0.5.

[0011] The present invention also provides a design method for an active radial magnetic bearing, comprising the following steps:

[0012] Obtaining the outer diameter and axial thickness of the stator core of the active radial magnetic bearing;

[0013] Based on the outer diameter and the axial thickness, the stator magnetic circuit area and the coil cavity area of ​​the active radial magnetic bearing are optimized on the premise that the circumferential width x of the core teeth of the stator core and the radial width y of the core yoke of the stator core are kept equal, so as to obtain a first stator magnetic circuit area optimization value and a coil cavity area optimization value;

[0014] Determining process parameters of the stator winding based on the first stator magnetic circuit area optimization value and the coil cavity area optimization value;

[0015] Keeping the process parameters of the stator winding and the optimized value of the coil cavity area unchanged, increasing the circumferential width x of the core teeth of the stator core and reducing the radial width y of the core yoke of the stator core;

[0016] According to the obtained x and y, a correlation curve diagram is drawn, wherein the correlation curve diagram reflects the relationship between the bearing capacity and / or the bearing support stiffness and different x / y;

[0017] The x / y corresponding to the maximum value of the bearing load capacity and / or the bearing support stiffness in the correlation curve diagram is obtained as the optimal design value.

[0018] Preferably, the process parameters include any one of the number of turns, wire diameter, input current and corresponding current density, and slot fill rate of the stator winding.

[0019] The present invention also provides a compressor, comprising the above-mentioned active radial magnetic bearing.

[0020] The present invention also provides an air conditioner, comprising the above-mentioned compressor.

[0021] The present invention provides an active radial magnetic bearing and a design method thereof, a compressor, and an air conditioner, wherein the circumferential width x of the core tooth portion is designed to be greater than the radial width y of the core yoke portion, so that when the material of the core tooth portion can achieve a better utilization rate, the material of the core yoke portion can also achieve a better utilization rate, so that when the volume of the active radial magnetic bearing is constant, the bearing capacity or support stiffness of the magnetic bearing can be better, and the disadvantage of increasing the overall volume and cost due to increasing the design size of the bearing in order to improve the bearing capacity or support stiffness of the magnetic bearing can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the radial section of the active radial magnetic bearing according to an embodiment of the present invention (partial components such as the housing are omitted);

[0023] Figure 2 for Figure 1 Relationship curve between control current i and bearing capacity F in the active radial magnetic bearing (x>y) in the prior art and the active radial magnetic bearing (x=y);

[0024] Figure 3 for Figure 1 The relationship curve between different x / y and bearing capacity of the active radial magnetic bearing in the design process;

[0025] Figure 4 Schematic diagram of the path of magnetic lines of force in an active radial magnetic bearing (x=y) in the prior art (6a in the figure is the main magnetic path generated by the stator winding, and 6b is the leakage magnetic path generated by the stator winding);

[0026] Figure 5 It is a schematic structural diagram of a radial section of a homopolar hybrid radial magnetic suspension bearing in the prior art (partial components such as the housing are omitted);

[0027] Figure 6 for Figure 5 Cross-sectional view of AA in the figure (8a is the control magnetic circuit generated by the stator winding, and 8b is the bias magnetic circuit generated by the magnetic ring).

[0028] The reference numerals are:

[0029] 1. stator core; 11. core yoke; 12. core teeth; 2. rotor core; 3. rotating shaft; 4. stator winding; 100. stator core; 101. yoke; 102. teeth; 200. stator winding; 300. rotor core; 400. rotating shaft; 500. air gap; 601. stator core I; 602. magnetic ring; 603. stator core II; 604. rotor core; 605. rotating shaft; 606. stator winding; 607. teeth; 608. yoke; 609. coil cavity; 610. air gap. DETAILED DESCRIPTION

[0030] See also Figures 1 to 6 As shown, according to an embodiment of the present invention, an active radial magnetic bearing is provided, comprising a stator core 1, wherein the stator core comprises a ring-shaped core yoke 11 and a plurality of core teeth 12 on the inner circumferential side of the core yoke 11, wherein the circumferential width of the plurality of core teeth 12 is x, the radial width of the core yoke 11 is y, and x / y>1. In this technical solution, based on the phenomenon of the main magnetic circuit 6a and the leakage magnetic circuit 6b generated by the stator winding 4 of the active radial magnetic bearing in the prior art, the technical prejudice in the industry that the radial width y of the core yoke 11 of the stator core 1 of the traditional active radial magnetic bearing must be consistent with the circumferential width x of the core tooth 12 is overcome, and the circumferential width x of the core tooth 12 is creatively designed to be larger than the radial width y of the core yoke 11, so that when the material of the core tooth 12 is optimally utilized, the material of the core yoke 11 can also be optimally utilized, so that the bearing capacity or support stiffness of the magnetic bearing is better when the volume of the active radial magnetic bearing is constant (that is, the outer diameter and the axial thickness remain unchanged), and the disadvantage of increasing the design size of the bearing to increase the bearing capacity or support stiffness of the magnetic bearing, resulting in an increase in the overall volume and cost, can be avoided. Figure 2 As shown, when x / y>, when the same current (i) is passed through the stator winding 4, the corresponding bearings have a bearing capacity higher than the corresponding bearing capacity level when x=y. For example, when i=4A, the bearing capacity of x / y corresponding to the m1 curve is about 2262N, while the bearing capacity of x / y corresponding to the m2 curve is about 2063N, that is, the bearing capacity is increased by nearly 10% after the unequal magnetic circuit area structure (that is, the design of x>y).

[0031] It should be noted that the homopolar hybrid radial magnetic suspension shaft bearing is another common type of magnetic suspension bearing, which is similar to the embodiment of the present invention, such as Figure 5 and 6As shown, it specifically includes a stator core I601, a magnetic ring 602, a stator core II603, a stator winding 606, a rotor core 604, and a rotating shaft 605. There is an air gap 610 between the stator and the rotor. The stator core 601 includes a yoke 608, 2n teeth 607 of equal width, and 2n coil cavities 609. n is generally an integer greater than 2. 2n stator windings 606 are installed on the 2n teeth 607. When the control current is passed through the diagonal winding, the following will be generated: Figure 6 The bias magnetic circuit (8b) and the control magnetic circuit (8a) shown in the figure are superimposed or offset at the diagonal air gap 610, thereby generating a suspension force in the direction of the magnetic circuit superposition. It can be found that the yoke 608 only passes through the control magnetic circuit (8a), while the tooth 607 needs to pass through the control magnetic circuit (8a) and the bias magnetic circuit (8b) at the same time. Therefore, according to the principle of magnetic circuit distribution, in order to avoid uneven distribution of magnetic induction intensity, the width of the tooth 607 will be significantly larger than the width of the yoke 608. Due to the different bearing output principles, the tooth yoke widths of the stator core of the homopolar hybrid radial magnetic bearing are not equal. That is, for the homopolar hybrid radial magnetic bearing in the prior art, since its tooth yoke width is not equal to the core tooth yoke width in the present invention, but since the magnetic circuits in the teeth and yokes of the hybrid radial magnetic bearing are different from the magnetic circuits in the core teeth 12 and the core yoke 11 in the present invention, technical personnel in this field do not have the motivation to apply the tooth yoke design of unequal widths of the hybrid radial magnetic bearing to the tooth yoke design in the present invention.

[0032] Furthermore, in order to make the bearing capacity and / or bearing support stiffness of the designed active radial magnetic bearing at a better level, preferably, x / y≤1.8. Figure 3 When the bearing is required to have a higher load-bearing capacity (or to optimize the load-bearing capacity of the bearing), it is more preferred that 1.05≤x / y≤1.3.

[0033] Since the magnetic circuit will be distributed along the path with the smallest magnetic resistance, in order to avoid (weaken) the direct leakage of the magnetic circuit between adjacent teeth, rather than along the adjacent core teeth 12 and the air gaps corresponding to the core yoke 11, the rotor 2 and the core teeth 12 therebetween, it is required that the distance between adjacent teeth be greater than the sum of the air gap lengths, that is, x<πd / (2n)-2g, where d is the inner diameter of the stator core 1, g is the radial thickness of the stator-rotor air gap formed between the stator core 1 and the rotor core 2, and 2n is the number of the core teeth 12.

[0034] Furthermore, the coil cavity area (that is, the slot area between two adjacent core teeth 12) directly determines the size of the bearing excitation current. When the pole area is too large, the coil cavity area will be smaller. Under the limitations of current density and slot fill rate, the excitation current will be too small, which is not conducive to the bearing load design. Therefore, 0.3<2nx / πd<0.85 should be ensured to ensure that the circumferential width of the core teeth 12 is within an appropriate range.

[0035] Preferably, the active radial magnetic bearing also includes a rotor core 2, which is mounted on a rotating shaft 3. When the rotating shaft 3 is made of non-magnetic material or weakly magnetic material, in order to avoid saturation of the rotor core 2, the width z of the rotor core 2 should not be too small. Preferably, the radial thickness of the rotor core 2 is z, and z / y>0.5.

[0036] According to an embodiment of the present invention, there is also provided a design method for an active radial magnetic bearing, comprising the following steps:

[0037] Obtaining the outer diameter and axial thickness of the stator core 1 of the active radial magnetic bearing;

[0038] Based on the outer diameter and the axial thickness, the stator magnetic circuit area and the coil cavity area of ​​the active radial magnetic bearing are optimized on the premise that the circumferential width x of the core tooth portion 12 of the stator core 1 and the radial width y of the core yoke portion 11 of the stator core 1 are kept equal, and a first stator magnetic circuit area optimization value and a coil cavity area optimization value are obtained;

[0039] Determining the process parameters of the stator winding 4 based on the first stator magnetic circuit area optimization value and the coil cavity area optimization value;

[0040] Keeping the process parameters of the stator winding 4 and the optimized value of the coil cavity area unchanged, increasing the circumferential width x of the core tooth portion 12 of the stator core 1 and reducing the radial width y of the core yoke portion 11 of the stator core 1;

[0041] According to the obtained x and y, a correlation curve diagram is drawn, wherein the correlation curve diagram reflects the relationship between the bearing capacity and / or the bearing support stiffness and different x / y;

[0042] The x / y corresponding to the maximum value of the bearing capacity and / or the bearing support stiffness in the correlation curve diagram is obtained as the optimal design value. That is, at this time, due to the changes in x and y, the first stator magnetic circuit area optimization value will be further optimized to the final second stator magnetic circuit area optimization value.

[0043] In this technical solution, on the basis of the traditional design of equal magnetic circuit area of ​​stator core (that is, equal width of tooth yoke), after optimizing various process parameters of magnetic levitation, the optimized bearing is further optimized and adjusted through unequal magnetic circuit area (that is, unequal width of tooth yoke), and the optimal design value is obtained in combination with the relationship curve between the corresponding bearing capacity or bearing support stiffness and x / y, so that when the material of the core tooth portion 12 can achieve a better utilization rate, the material of the core yoke portion 11 can also achieve a better utilization rate, so that when the volume of the active radial magnetic levitation bearing is constant (that is, the outer diameter and the axial thickness remain unchanged), the bearing capacity or support stiffness of the magnetic levitation bearing is better, and the disadvantage of increasing the design size of the bearing in order to improve the bearing capacity or support stiffness of the magnetic levitation bearing, resulting in an increase in the overall volume and cost, can be avoided.

[0044] The process parameters include any one of the number of turns, wire diameter, input current and corresponding current density, and slot fill rate of the stator winding 4 .

[0045] According to an embodiment of the present invention, there is also provided a compressor, comprising the above-mentioned active radial magnetic bearing.

[0046] According to an embodiment of the present invention, there is also provided an air conditioner, comprising the above-mentioned compressor.

[0047] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A design method for an active radial magnetic bearing, characterized in that: The steps include: Obtaining the outer diameter and axial thickness of the stator core (1) of the active radial magnetic bearing; Based on the outer diameter and the axial thickness, the stator magnetic circuit area and the coil cavity area of ​​the active radial magnetic bearing are optimized on the premise that the circumferential width x of the core tooth portion (12) of the stator core (1) and the radial width y of the core yoke portion (11) of the stator core (1) are kept equal, so as to obtain a first stator magnetic circuit area optimization value and a coil cavity area optimization value; Determining process parameters of the stator winding (4) based on the first stator magnetic circuit area optimization value and the coil cavity area optimization value; The process parameters of the stator winding (4) and the optimized value of the coil cavity area are kept unchanged, the circumferential width x of the core tooth portion (12) of the stator core (1) is increased, and the radial width y of the core yoke portion (11) of the stator core (1) is reduced; According to the obtained x and y, a correlation curve diagram is drawn, wherein the correlation curve diagram reflects the relationship between the bearing capacity and / or the bearing support stiffness and different x / y; The x / y corresponding to the maximum value of the bearing load capacity and / or the bearing support stiffness in the correlation curve diagram is obtained as the optimal design value.

2. The design method according to claim 1, characterized in that: The process parameters include any one of the number of turns, wire diameter, input current and corresponding current density, and slot fill rate of the stator winding (4).

3. The design method according to claim 1, characterized in that: x / y>1.

4. The design method according to claim 3, characterized in that: x / y≤1.

8.

5. The design method according to claim 4, characterized in that: 1.05≤x / y≤1.

3.

6. The design method according to any one of claims 2 to 5, characterized in that: x<πd / (2n)-2g, wherein d is the inner diameter of the stator core (1), g is the radial thickness of the stator-rotor air gap formed between the stator core (1) and the rotor core (2), and 2n is the number of the core teeth (12).

7. The active radial magnetic bearing according to claim 5, characterized in that: 0.3<2nx / πd<0.

85.

8. The active radial magnetic bearing according to claim 6 or 7, characterized in that: The rotor core (2) is sleeved on the rotating shaft (3), and the radial thickness of the rotor core (2) is z, where z / y>0.5.

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