Magnetic bearing and bearingless motor

Abstract

In a magnetic bearing according to a first embodiment, a second rotor magnet (N pole) (33) and a first rotor magnet (S pole) (32) are provided as follows. On a first axial direction virtual line (P1), the length occupied by the first rotor magnet (32) is longer than the length occupied by the second rotor magnet (33), and on a second axial direction virtual line (P2), the length occupied by the second rotor magnet (33) is longer than the length occupied by the first rotor magnet (32). Further, on a first rotation direction virtual line (Q1), the length occupied by the first rotor magnet (32) is longer than the length occupied by the second rotor magnet (33), and on a second rotation direction virtual line (Q2), the length occupied by the second rotor magnet (33) is longer than the length occupied by the first rotor magnet (32).

Description

Magnetic bearings and bearingless motors

[0001] The present disclosure relates to magnetic bearings and bearingless motors, and more particularly to magnetic bearings and bearingless motors with active control of at least three axes.

[0002] Patent Document 1 discloses a self-bearing motor (bearingless motor). Generally, a bearingless motor is a rotating electric machine in which a motor winding and a radial support winding are provided on a stator, thereby integrating the motor with a magnetic bearing and giving the motor itself a magnetic bearing function.

[0003] The self-bearing motor disclosed in Patent Document 1 is a five-axis actively controlled bearingless motor that can stably levitate the rotor by actively controlling five axes: the radial direction of the rotor (X-axis, Y-axis), the axial direction of the rotor (Z-axis), and the tilt direction of the rotor (θx-axis, θy-axis).

[0004] JP 2008-289340 A

[0005] The self-bearing motor of Patent Document 1 has a complex rotor structure in the axial direction, which may result in an increased axial dimension. The stator winding is also complex, which may result in an increased coil end size in the axial direction. Furthermore, the large number of phases required for control may increase the volume and cost of the control equipment.

[0006] The present disclosure provides a magnetic bearing and a bearingless motor that can be made thin.

[0007] A magnetic bearing according to one aspect of the present disclosure includes a rotor and a stator. The rotor has a rotor core that rotates about an axis extending in the axial direction, and one or more north poles and one or more south poles provided on the rotor core. The stator faces the rotor at a predetermined distance in the radial direction. Assuming that a first axial virtual line and a second axial virtual line extend along the axial direction of the rotor at different positions in the rotational direction, and assuming that a first rotational direction virtual line and a second rotational direction virtual line extend along the rotational direction at different positions in the axial direction of the rotor, the one or more north poles and the one or more south poles are provided as follows: The length occupied by the south poles on the first axial virtual line is longer than the length occupied by the north poles, and the length occupied by the north poles on the second axial virtual line is longer than the length occupied by the south poles. The length of the first rotation direction imaginary line occupied by the south pole is longer than the length of the north pole, and the length of the second rotation direction imaginary line occupied by the north pole is longer than the length of the south pole.

[0008] A bearingless motor according to one aspect of the present disclosure includes the above-described magnetic bearing and a motor coil for rotating a rotor.

[0009] The magnetic bearing and bearingless motor of the present disclosure can be made thinner in the axial direction.

[0010] FIG. 1 is a perspective view of a bearingless motor according to a first embodiment of the present disclosure. FIG. 2 is a perspective view of a stator of the bearingless motor according to the first embodiment. FIG. 3 is a partially enlarged perspective view of the stator of the bearingless motor according to the first embodiment. FIG. 4 is a perspective view of a rotor of the bearingless motor according to the first embodiment. FIG. 5 is a schematic side view showing the arrangement of magnetic poles of the rotor according to the first embodiment. FIG. 6 is a schematic block diagram showing the control configuration of the bearingless motor according to the first embodiment. FIG. 7 is a schematic view showing the principle of thrust force generation in the bearingless motor according to the first embodiment, illustrating the generation of a first magnetic flux by application of a positive thrust current. FIG. 8 is a schematic view showing the principle of thrust force generation in the bearingless motor according to the first embodiment, illustrating the generation of a second magnetic flux by application of a negative thrust current. FIG. 9 is a schematic side view showing the arrangement of magnetic poles of a rotor according to a second embodiment. FIG. 10 is a schematic side view showing the arrangement of magnetic poles of a rotor according to a third embodiment. FIG. 11 is a schematic side view showing the arrangement of magnetic poles of a rotor according to a fourth embodiment. FIG. 12 is a schematic side view showing the arrangement of magnetic poles of a rotor according to a fifth embodiment. Fig. 13 is a schematic side view showing the arrangement of magnetic poles of a rotor according to a sixth embodiment. Fig. 14 is a schematic side view showing the arrangement of magnetic poles of a rotor according to a seventh embodiment.

[0011] A magnetic bearing and a bearingless motor according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. However, the drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Note that the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0012] First Embodiment A magnetic bearing 5 and a bearingless motor 1 according to a first embodiment will be described with reference to FIGS. 1 to 8. FIG.

[0013] (1) Overall Configuration of Bearingless Motor Fig. 1 is a perspective view of a bearingless motor 1. The bearingless motor 1 will be described using Fig. 1. The bearingless motor 1 is used, for example, in a semiconductor spin coater (not shown).

[0014] The bearingless motor 1 is a radial gap type motor and includes a stator 2 and a rotor 3. The bearingless motor 1 rotates the rotor 3 while magnetically levitating it. The rotor 3 rotates about an axis R1 that is aligned with the Z axis of a Cartesian coordinate system having an X axis, a Y axis, and a Z axis. In the following description, the direction along the X axis is referred to as the X-axis direction, the direction along the Y axis is referred to as the Y-axis direction, and the direction along the Z axis is referred to as the Z-axis direction. In the following description, the Z-axis direction will be referred to as the axial direction A1.

[0015] The bearingless motor 1 has a magnetic bearing 5 that supports the rotor 3. The magnetic bearing 5 controls the position of the rotor 3 by creating an imbalance in magnetic flux density (described later).

[0016] (2) Stator Fig. 2 is a perspective view of the stator 2 of the bearingless motor 1, and Fig. 3 is a partially enlarged perspective view of the stator 2. The stator 2 will be described with reference to Figs. 2 and 3.

[0017] (2-1) Frame, First Stator Core, and Second Stator Core The stator 2 has a frame 21, a first stator core 22, and a second stator core 23. The frame 21 is a cylindrical member. The first stator core 22 and the second stator core 23 are annular members and are fixed to both side portions of the frame 21 in the axial direction A1.

[0018] The first stator core 22 has a first yoke 221 and a plurality of first teeth 222. The first yoke 221 is annular. The first yoke 221 has a plurality of steel plates stacked in the axial direction A1. The steel plates are formed of electromagnetic steel plates such as silicon steel plates. The plurality of first teeth 222 are arranged radially at equal intervals on the inner peripheral edge of the first yoke 221. In other words, the first yoke 221 magnetically connects the plurality of first teeth 222. The plurality of first teeth 222 extend from the first yoke 221 toward the axis R1, with their tips located close to the outer peripheral surface of the rotor 3.

[0019] The second stator core 23 has a second yoke 231 and a plurality of second teeth 232. The second yoke 231 is annular. The second yoke 231 has a plurality of steel plates stacked in the axial direction A1. The steel plates are formed of, for example, electromagnetic steel plates such as silicon steel plates. The plurality of second teeth 232 are arranged radially at equal intervals on the inner peripheral edge of the second yoke 231. In other words, the second yoke 231 magnetically connects the plurality of second teeth 232. The plurality of second teeth 232 extend from the second yoke 231 toward the axis R1, with their tips located close to the outer peripheral surface of the rotor 3.

[0020] As described above, the plurality of first teeth 222 and second teeth 232 are arranged side by side in the rotational direction C1 and the axial direction A1.

[0021] (2-2) Motor Winding, Radial Winding, and Thrust Winding The stator 2 has a motor winding 25 (winding), a radial winding 26 (first winding), and a thrust winding 27 (second winding).

[0022] The motor windings 25 are windings for generating torque in the rotor 3. Because rotation control in the bearingless motor 1 is performed in three phases, U-phase, V-phase, and W-phase motor coil windings are wound around the first teeth 222 and the second teeth 232 to form the motor coil 35. More specifically, the motor windings 25 are wound across the two first teeth 222 and the two second teeth 232 that are aligned in the axial direction A1 (i.e., that are at the same position in the rotational direction C1). In this case, the coil ends can be made shorter than when the motor windings 25 are wound separately in the axial direction A1.

[0023] The radial winding 26 is a winding for generating a supporting force in the radial direction (direction perpendicular to the axial direction A1) that supports the rotor 3 (i.e., for controlling the radial position of the rotor 3). In other words, the radial winding 26 adjusts the radial position of the rotor 3 relative to the stator 2. In the first embodiment, the radial position of the rotor 3 in the bearingless motor 1 is adjusted in three phases, so the radial winding 26 has U-phase, V-phase, and W-phase windings wound around the first teeth 222 and the second teeth 232, respectively, to form a radial coil 36. More specifically, the radial winding 26 is wound across the two first teeth 222 and the two second teeth 232 that are aligned in the axial direction A1 (i.e., that are positioned at the same position in the rotational direction C1). In this case, the coil end can be shortened compared to when the radial winding 26 is wound separately in the axial direction A1.

[0024] The thrust winding 27 is a winding for generating a support force in the axial direction A1 and in the tilt directions θx and θy of the rotor 3. The thrust winding 27 is disposed on the upper and lower surfaces of the first yoke 221 of the first stator core 22, extending at a predetermined angle in the rotational direction C1, and forms a thrust coil 37.

[0025] The thrust coil 37 has a plurality of (six in this embodiment) thrust coils 37 (multiple winding portions) divided in the rotational direction C1. Each of the plurality of thrust coils 37 independently generates a force that supports the rotor 3 in the axial direction A1, thereby controlling the tilt of the rotor 3 (described later).

[0026] In the drawings (FIGS. 1, 2, 3, 7 and 8), the coil ends of the motor winding 25 and the radial winding 26 are omitted.

[0027] (2-3) Stator Magnets As shown in Fig. 3, the stator 2 further includes a plurality of first stator magnets 28 and a plurality of second stator magnets 29. The plurality of first stator magnets 28 and the plurality of second stator magnets 29 generate a restoring force that constantly urges the rotor 3 upward in the axial direction A1 (first axial side A11). This makes it possible to compensate for the weight of the rotor 3. There are no limitations on the presence, number, or locations of the first stator magnets 28 and the plurality of second stator magnets 29.

[0028] (3) Rotor Fig. 4 is a perspective view of the rotor 3, and Fig. 5 is a schematic side view showing the arrangement of magnetic poles of the rotor 3. The rotor 3 will be described with reference to Figs.

[0029] The rotor 3 is integrally attached to a rotating body (not shown) as an output destination and transmits torque to the rotating body. The rotor 3 faces the stator 2 at a predetermined radial distance. The rotor 3 has an annular rotor core 31, a plurality of first rotor magnets 32, and a plurality of second rotor magnets 33. The bearingless motor 1 is an IPM (Interior Permanent Magnet) motor. In other words, the first rotor magnet 32 ​​and the second rotor magnet 33 are embedded in the outer peripheral surface of the rotor core 31.

[0030] The rotor core 31 is an annular member and is rotatable about an axis R1.

[0031] The first rotor magnet 32 ​​is a plate-shaped south-pole magnet arranged with its south pole facing the outer peripheral surface of the rotor core 31. The second rotor magnet 33 is a plate-shaped north-pole magnet arranged with its north pole facing the outer peripheral surface of the rotor core 31. As shown in FIG. 4 , the length of the first rotor magnet 32 ​​is the same as the length of the second rotor magnet 33 in the rotational direction C1. The length of the first rotor magnet 32 ​​is longer than the length of the second rotor magnet 33 in the axial direction A1. The multiple first rotor magnets 32 and the multiple second rotor magnets 33 are arranged in a checkered pattern (i.e., a checkered pattern). Specifically, the multiple first rotor magnets 32 are arranged at equal intervals (or equal spacing) with gaps between them in the axial direction A1 and the rotational direction C1. The multiple second rotor magnets 33 are also arranged at equal intervals (or equal spacing) with gaps between them in the axial direction A1 and the rotational direction C1. Furthermore, the columns of the first rotor magnets 32 and the columns of the second rotor magnets 33 are alternately arranged in the rotational direction C1, and the rows of the first rotor magnets 32 and the rows of the second rotor magnets 33 are alternately arranged in the axial direction A1.

[0032] In the middle portion of the outer peripheral surface of the rotor core 31 in the axial direction A1, first rotor magnets 32 and first gaps 38 (areas where no magnetic poles are arranged) are alternately provided in the rotational direction C1. Furthermore, second gaps 39 are provided on both sides of the first rotor magnet 32 ​​in the axial direction A1. The first rotor magnet 32 ​​is a rectangle whose longer side is in the rotational direction C1. The first rotor magnet 32 ​​and the first gaps 38 have the same length in both the axial direction A1 and the rotational direction C1.

[0033] On both sides of the outer peripheral surface of the rotor core 31 in the axial direction A1, the second rotor magnets 33 and the aforementioned second gaps 39 are alternately arranged in the rotational direction C1. The second rotor magnets 33 have the same shape as the first rotor magnets 32, being rectangular and elongated in the rotational direction C1. The second rotor magnets 33 and the second gaps 39 have the same length in both the axial direction A1 and the rotational direction C1. The position of the second rotor magnet 33 in the rotational direction C1 coincides with the position of the first gaps 38. The position of the second rotor magnet 33 in the axial direction A1 coincides with the position of the second gaps 39. Furthermore, the first rotor magnets 32 and the second rotor magnets 33 do not overlap when viewed from the axial direction A1, and the first rotor magnets 32 and the second rotor magnets 33 do not overlap when viewed in the rotational direction C1. In other words, the edge of the first rotor magnet 32 ​​in the rotational direction C1 and the edge of the second rotor magnet 33 in the rotational direction C1 coincide with each other in the rotational direction C1. Furthermore, the edge of the first rotor magnet 32 ​​in the axial direction A1 and the edge of the second rotor magnet 33 in the axial direction A1 are aligned in the axial direction A1. With the above configuration, it is possible to generate a magnetic flux density distribution that mainly includes fundamental wave components according to the number of magnet poles aligned in the axial direction A1 and the rotational direction C1.

[0034] 5 assumes a first axial imaginary line P1 and a second axial imaginary line P2 extending along the axial direction A1 at different positions in the rotational direction C1 of the rotor 3. Also, FIG. 5 assumes a first rotational direction imaginary line Q1 and a second rotational direction imaginary line Q2 extending along the rotational direction C1 at different positions in the axial direction A1 of the rotor 3. In this case, a plurality of first rotor magnets 32 and a plurality of second rotor magnets 33 are provided as follows: the length of the first axial imaginary line P1 occupied by the first rotor magnet 32 ​​is longer than the length of the second rotor magnet 33, and the length of the second axial imaginary line P2 occupied by the second rotor magnet 33 is longer than the length of the first rotor magnet 32. Furthermore, the length of the first rotation direction virtual line Q1 occupied by the first rotor magnet 32 ​​is longer than the length of the second rotor magnet 33, and the length of the second rotation direction virtual line Q2 occupied by the second rotor magnet 33 is longer than the length of the first rotor magnet 32.

[0035] 5, the first axial imaginary line P1 is drawn at the center of the rotational direction C1 of the first rotor magnet 32, but the position of the first axial imaginary line P1 in the rotational direction C1 may be anywhere within the area of ​​the first rotor magnet 32. The second axial imaginary line P2 is drawn at the center of the rotational direction C1 of the second rotor magnet 33, but the position of the second axial imaginary line P2 in the rotational direction C1 may be anywhere within the area of ​​the second rotor magnet 33. The first rotational direction imaginary line Q1 is drawn at the center of the axial direction A1 of the first rotor magnet 32, but the position of the first rotational direction imaginary line Q1 in the axial direction A1 may be anywhere within the area of ​​the first rotor magnet 32. The second rotational direction imaginary line Q2 is drawn at the center of the axial direction A1 of the second rotor magnet 33, but the position of the second rotational direction imaginary line Q2 in the axial direction A1 may be anywhere within the area of ​​the second rotor magnet 33.

[0036] (4) Control Configuration of Magnetic Bearing Fig. 6 is a schematic block diagram showing the control configuration of the bearingless motor 1. The control configuration of the magnetic bearing 5 will be described with reference to Fig. 6.

[0037] The magnetic bearing 5 is composed of a part of the stator 2 and the rotor 3. The magnetic bearing 5 is a so-called radial gap type magnetic bearing. The magnetic bearing 5 controls the position of the rotor 3 in terms of translational motion in the X-axis direction (X), translational motion in the Y-axis direction (Y), translational motion in the Z-axis direction (Z), tilt motion around the X-axis (θx), and tilt motion around the Y-axis (θy).

[0038] As shown in FIG. 6 , the magnetic bearing 5 further includes a control unit 51 , a position sensor 521 , an angle sensor 522 , and a current generating unit 53 .

[0039] The control unit 51 has, for example, a levitation control unit, a current control unit, and an attitude calculation unit. Each function of the control unit 51 is realized, for example, by a computer. The magnetic bearing 5 has, for example, a processing board made of a printed circuit board or the like on whose surface an electronic circuit (electrical circuit) is printed. The processing board has, for example, a CPU (Central Processing Unit), memory, etc., and constitutes a computer. The CPU then executes a program stored in the memory, causing the computer to function as the control unit 51. Note that the control unit 51 may also be a hardware circuit designed specifically to realize the above functions.

[0040] The position sensor 521 is a non-contact sensor for detecting the position of the rotor 3. The position sensor 521 is, for example, a distance measuring sensor for detecting the distance to the surface of the rotor 3. The type of the position sensor 521 is not limited.

[0041] The angle sensor 522 is a sensor for detecting the angle of the rotor 3. The angle sensor 522 is, for example, a rotary encoder. The type of the angle sensor 522 is not limited.

[0042] The current generating unit 53 includes an AC power supply or an inverter and a DC power supply, and can apply three-phase AC to the motor coil 35 and can apply AC to the radial coil 36 and thrust coil 37 .

[0043] (5) Operation of the Bearingless Motor (5-1) Rotor Rotation Operation The control unit 51 controls the current generating unit 53 to supply three-phase AC from the current generating unit 53 to the motor coil 35. As a result, a torque is generated in the rotor 3 by the magnetic field generated by the motor coil 35 and the magnetic fields generated by the first rotor magnet 32 ​​and the second rotor magnet 33, causing the rotor 3 to rotate.

[0044] (5-2) Position Control Operation in the X-Axis and Y-Axis Directions The control unit 51 supplies AC current from the current generating unit 53 to the radial coil 36 based on the detection signal from the position sensor 521. As a result, the position of the rotor 3 in the X-axis and Y-axis directions is controlled by the magnetic field generated from the radial coil 36 and the magnetic fields generated from the first rotor magnet 32 ​​and the second rotor magnet 33.

[0045] (5-3) Position Control Operation in the Z-Axis Direction The control unit 51 causes the current generating unit 53 to supply an alternating current to the thrust coil 37 based on a detection signal from the position sensor 521. As a result, the position of the rotor 3 in the axial direction A1 is controlled by the magnetic field generated from the thrust coil 37 and the magnetic fields generated from the first rotor magnet 32 ​​and the second rotor magnet 33. In this case, the control unit 51 controls the current generating unit 53 so that all of the thrust coils 37 generate a thrust force on the same side in the axial direction A1 (the first axial side A11 or the second axial side A12).

[0046] Fig. 7 is a schematic diagram showing the principle of thrust force generation in the bearingless motor 1, and Fig. 8 is a schematic diagram showing the principle of thrust force generation in the bearingless motor 1. Using Figs. 7 and 8, the principle of thrust force generation acting on a portion of the rotor 3 facing the thrust coil 37 when a positive thrust current and a negative thrust current are applied to one thrust coil 37 will be described.

[0047] 7, a positive thrust current is applied to the thrust coil 37, causing the thrust coil 37 to generate a first magnetic flux M1. The first magnetic flux M1 flows from the frame 21 to the first stator core 22, from the first stator core 22 to the first rotor magnet 32, and from the first rotor magnet 32 ​​to the rotor core 31. The first magnetic flux M1 then flows from the rotor core 31 to the second rotor magnet 33 on the second axial side A12, from the second rotor magnet 33 on the second axial side A12 to the second stator core 23, and from the second stator core 23 to the frame 21. As a result, a thrust force F1 acts on the portion of the rotor 3 facing the thrust coil 37 toward the first axial side A11.

[0048] 8 , a negative thrust current is applied to the thrust coil 37, causing the thrust coil 37 to generate a second magnetic flux M2. The second magnetic flux M2 flows from the frame 21 to the second stator core 23, from the second stator core 23 to the first rotor magnet 32, and from the first rotor magnet 32 ​​to the rotor core 31. The second magnetic flux M2 then flows from the rotor core 31 to the second rotor magnet 33 on the first axial side A11, from the second rotor magnet 33 on the first axial side A11 to the second stator core 23, and from the second stator core 23 to the frame 21. As a result, a thrust force F2 acts on the portion of the rotor 3 facing the thrust coil 37 toward the second axial side A12.

[0049] (5-4) Position Control Operation in the θx-Axis and θy-Axis Directions Based on the detection signal from the position sensor 521, the control unit 51 controls the current generating unit 53 to supply direct current to the thrust coils 37. As a result, the position of the rotor 3 in the θx-axis and θy-axis directions is controlled by the magnetic fields generated by the thrust coils 37 and the magnetic fields generated by the first rotor magnet 32 ​​and the second rotor magnet 33. In this case, for example, the control unit 51 controls the current generating unit 53 so that the three thrust coils 37 arranged consecutively in the rotational direction C1 generate thrust forces toward the same side of the axial direction A1 (the first axial side A11 or the second axial side A12). At the same time, the control unit 51 controls the current generating unit 53 so that the remaining three thrust coils 37 arranged consecutively in the rotational direction C1 generate thrust forces toward the opposite side of the axial direction A1 (the first axial side A11 or the second axial side A12).

[0050] (6) Effects A magnetic flux density distribution can be generated in the axial direction A1 by providing a plurality of first rotor magnets 32 and second rotor magnets 33 in the rotor 3 as a structure for controlling the position of the rotor 3 in the axial direction A1 and the tilt directions θx and θy. In addition, by providing a plurality of thrust coils 37 in the stator 2 and changing the direction of current flowing through the thrust coils 37, it is possible to control the rotor 3 on both sides of the axial direction A1.

[0051] Therefore, the rotor 3 has a simple structure. In particular, the rotor 3 is thin and short in the axial direction A1.

[0052] In accordance with the above-described configuration of the rotor 3, the stator 2 is also thin and short in the axial direction A1.

[0053] With the above configuration, the magnetic bearing 5 and the bearingless motor 1 are thin and short in the axial direction A1, and are suitable for use in, for example, a semiconductor spin coater (not shown).

[0054] Second Embodiment In the first embodiment, the ratio of the length of the first rotor magnet 32 ​​to the length of the first gap 38 in the rotation direction C1 is 1:1. However, the ratio does not have to be 1:1. A second embodiment will be described as such an embodiment.

[0055] The second embodiment will be described with reference to Fig. 9. The basic structure and basic operation of the second embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0056] FIG. 9 is a schematic side view showing the arrangement of magnetic poles of a rotor 3A according to the second embodiment. In the rotor 3A, the first rotor magnets 32A and the second rotor magnets 33A are arranged in a checkerboard pattern. First gaps 38A and second gaps 39A are also provided. Specifically, the first rotor magnets 32A and the second rotor magnets 33A are rectangular and are arranged at intervals in the axial direction A1 and the rotational direction C1. Furthermore, the rows of the first rotor magnets 32A and the rows of the second rotor magnets 33A are alternately arranged in the rotational direction C1, and the rows of the first rotor magnets 32A and the rows of the second rotor magnets 33A are alternately arranged in the axial direction A1.

[0057] When viewed from the axial direction A1, both ends of the first rotor magnet 32A in the rotational direction C1 overlap with both ends of the second rotor magnet 33A in the rotational direction C1. Specifically, compared to the first embodiment, the first rotor magnet 32A is longer in the rotational direction C1, and the first gap 38A is shorter in the rotational direction C1. Furthermore, the first rotor magnet 32A is longer in the rotational direction C1 than the second rotor magnet 33A.

[0058] In the second embodiment, the supporting force in the axial direction A1 is increased, and the rotational torque around the axis R1 and the supporting force in the X and Y directions are reduced, compared to the first embodiment.

[0059] Third Embodiment In the first embodiment, the ratio of the length of the first rotor magnet 32 ​​to the length of the second gap 39 in the axial direction A1 is 1:1. However, the ratio does not have to be 1:1. A second embodiment will be described as such an embodiment.

[0060] The third embodiment will be described with reference to Fig. 10. The basic structure and basic operation of the third embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0061] FIG. 10 is a schematic side view showing the arrangement of magnetic poles of a rotor 3B according to the third embodiment. In the rotor 3B, a plurality of first rotor magnets 32B and a plurality of second rotor magnets 33B are arranged in a checkerboard pattern. First gaps 38B and second gaps 39B are also provided. Specifically, the plurality of first rotor magnets 32B and the plurality of second rotor magnets 33B are rectangular and are arranged at intervals in the axial direction A1 and the rotational direction C1. Furthermore, rows of the first rotor magnets 32B and rows of the second rotor magnets 33B are alternately arranged in the rotational direction C1, and rows of the first rotor magnets 32B and rows of the second rotor magnets 33B are alternately arranged in the axial direction A1.

[0062] When viewed from the direction of rotation C1, both ends of the first rotor magnet 32B in the axial direction A1 overlap with both ends of the second rotor magnet 33B in the axial direction A1. Specifically, compared to the first embodiment, the first rotor magnet 32B is longer in the axial direction A1, and the second gap 39B is shorter in the axial direction A1. Furthermore, the first rotor magnet 32B is longer in the axial direction A1 than the second rotor magnet 33B.

[0063] As an example of a case in which the lengths in the axial direction A1 of the first rotor magnet 32B and the second rotor magnets 33B on both the upper and lower sides are different, for example, the ratio of the lengths in the axial direction A1 of the upper second rotor magnet 33B, the first rotor magnet 32B, and the lower second rotor magnet 33B from top to bottom in the axial direction A1 may be 0.5:1:0.5.

[0064] In the third embodiment, compared to the first embodiment, the supporting force in the axial direction A1 is reduced, and the rotational torque around the axis R1 and the supporting force in the X and Y directions are increased.

[0065] Fourth Embodiment In the first embodiment, the ratio of the length of the first rotor magnet 32 ​​to the length of the first gap 38 in the rotation direction C1 is 1:1. However, the ratio does not have to be 1:1. A fourth embodiment will be described as such an embodiment.

[0066] The fourth embodiment will be described with reference to Fig. 11. The basic structure and basic operation of the fourth embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0067] FIG. 11 is a schematic side view showing the arrangement of magnetic poles of a rotor 3C according to the fourth embodiment. In the rotor 3C, a plurality of first rotor magnets 32C and a plurality of second rotor magnets 33C are arranged in a checkerboard pattern (i.e., a checkered pattern). First gaps 38C and second gaps 39C are also provided. Specifically, the plurality of first rotor magnets 32C and the plurality of second rotor magnets 33C are rectangular and are arranged at intervals in the axial direction A1 and the rotational direction C1. Furthermore, rows of the first rotor magnets 32C and rows of the second rotor magnets 33C are alternately arranged in the rotational direction C1, and rows of the first rotor magnets 32C and rows of the second rotor magnets 33C are alternately arranged in the axial direction A1.

[0068] When viewed from the axial direction A1, both ends of the first rotor magnet 32C in the rotational direction C1 and both ends of the second rotor magnet 33B in the rotational direction C1 are spaced apart in the rotational direction C1. Specifically, compared to the first embodiment, the first rotor magnet 32C is shorter in the rotational direction C1, and the first gap 38 is longer in the rotational direction C1. Furthermore, the first rotor magnet 32C is shorter in the rotational direction C1 than the second rotor magnet 33C.

[0069] In the fourth embodiment, the same effects as in the first embodiment are obtained, and although the rotational torque around the axis R1 and the supporting force in the X and Y directions are reduced, the amount of permanent magnets can be reduced.

[0070] Fifth Embodiment In the first embodiment, the ratio of the length of the first rotor magnet 32 ​​to the length of the second gap 39 in the axial direction A1 is 1:1. However, the ratio does not have to be 1:1. As such an embodiment, a fifth embodiment will be described.

[0071] The fifth embodiment will be described with reference to Fig. 12. The basic structure and basic operation of the fifth embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0072] FIG. 12 is a schematic side view showing the arrangement of magnetic poles of a rotor 3D according to the fifth embodiment. In the rotor 3D, a plurality of first rotor magnets 32D and a plurality of second rotor magnets 33D are arranged in a checkerboard pattern (i.e., a checkered pattern). First gaps 38D and second gaps 39D are also provided. Specifically, the plurality of first rotor magnets 32D and the plurality of second rotor magnets 33D are rectangular and are arranged at intervals in the axial direction A1 and the rotational direction C1. Furthermore, rows of the first rotor magnets 32D and rows of the second rotor magnets 33D are alternately arranged in the rotational direction C1, and rows of the first rotor magnets 32D and rows of the second rotor magnets 33D are alternately arranged in the axial direction A1.

[0073] When viewed from the direction of rotation C1, both ends of the first rotor magnet 32D in the axial direction A1 and both ends of the second rotor magnet 33D in the axial direction A1 are spaced apart in the axial direction A1. Specifically, compared to the first embodiment, the first rotor magnet 32D is shorter in the axial direction A1, and the second gap 39D is longer in the axial direction A1. Furthermore, the first rotor magnet 32D is shorter in the axial direction A1 than the second rotor magnet 33D.

[0074] In the fifth embodiment, the same effect as in the first embodiment is obtained, and the supporting force in the axial direction A1 is reduced, but the amount of permanent magnets can be reduced.

[0075] Sixth Embodiment In the first embodiment, the first gap 38 and the second gap 39 are provided. However, the rotor magnets may be disposed without any gaps. As such an embodiment, a sixth embodiment will be described.

[0076] The sixth embodiment will be described with reference to Fig. 13. The basic structure and basic operation of the sixth embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0077] FIG. 13 is a schematic side view showing the arrangement of magnetic poles of a rotor 3E according to the sixth embodiment. As shown in FIG. 13 , in the rotor 3E, the plurality of first rotor magnets 32E and the plurality of second rotor magnets 33E are arranged in a checkerboard pattern (i.e., a checkered pattern). Specifically, the plurality of first rotor magnets 32E and the plurality of second rotor magnets 33E are identical in shape and are arranged in the axial direction A1 and the rotational direction C1. Furthermore, the rows of the first rotor magnets 32E and the rows of the second rotor magnets 33E are alternately arranged in the rotational direction C1, and the rows of the first rotor magnets 32E and the rows of the second rotor magnets 33E are alternately arranged in the axial direction A1.

[0078] Specifically, the first rotor magnets 32E are arranged in the rotational direction C1 in the middle of the axial direction A1. The first rotor magnets 32E are rhombic. The vertices of the first rotor magnets 32E arranged in the rotational direction C1 are in contact with each other.

[0079] The second rotor magnets 33E are arranged in the rotational direction C1 on both sides of the axial direction A1. The second rotor magnets 33E are rhombic, and have the same shape as the first rotor magnets 32E. The second rotor magnets 33E arranged in the rotational direction C1 have their vertices in contact with each other. The second rotor magnets 33E and the first rotor magnets 32E have their sides in contact with each other.

[0080] Furthermore, third rotor magnets 321E are arranged between the second rotor magnets 33E above in the axial direction A1 in Fig. 13 in the rotational direction C1. Also, third rotor magnets 321E are arranged between the second rotor magnets 33E below in the axial direction A1 in Fig. 13 in the rotational direction C1. The third rotor magnet 321E is triangular. Like the first rotor magnet 32E, the third rotor magnet 321E has an S pole. As a result, the multiple first rotor magnets 32E, the multiple second rotor magnets 33E, and the multiple third rotor magnets 321E are arranged without any gaps. With the above configuration, a sinusoidal magnetic flux density distribution can be generated in the axial direction A1 and the rotational direction C1.

[0081] 13 , a first axial virtual line P1 and a second axial virtual line P2 are assumed to extend along the axial direction A1 at different positions in the rotational direction C1 of the rotor 3E. Also, in FIG. 13 , a first rotational virtual line Q1 and a second rotational virtual line Q2 are assumed to extend along the rotational direction C1 at different positions in the axial direction A1 of the rotor 3E. In this case, a plurality of first rotor magnets 32E, a plurality of second rotor magnets 33E, and a plurality of third rotor magnets 321E are arranged as follows: The length of the first axial virtual line P1 occupied by the first rotor magnet 32E and the third rotor magnet 321E is longer than the length occupied by the second rotor magnet 33E, and the length of the second axial virtual line P2 occupied by the second rotor magnet 33E is longer than the length occupied by the first rotor magnet 32E and the third rotor magnet 321E. The length of the first rotation direction virtual line Q1 occupied by the first rotor magnet 32E and the third rotor magnet 321E is longer than the length of the second rotor magnet 33E, and the length of the second rotation direction virtual line Q2 occupied by the second rotor magnet 33E is longer than the length of the first rotor magnet 32E and the third rotor magnet 321E.

[0082] 13, the first axial imaginary line P1 is drawn at the center of the rotational direction C1 of the first rotor magnet 32E, but the position of the first axial imaginary line P1 in the rotational direction C1 may be offset from the center of the rotational direction C1 as long as the above-mentioned conditions are met. The second axial imaginary line P2 is drawn at the center of the rotational direction C1 of the second rotor magnet 33E, but the position of the second axial imaginary line P2 in the rotational direction C1 may be offset from the center of the rotational direction C1 as long as the above-mentioned conditions are met. The first rotational direction imaginary line Q1 is drawn at the center of the axial direction A1 of the first rotor magnet 32E, but the position of the first rotational direction imaginary line Q1 in the axial direction A1 may be offset from the center of the axial direction A1 as long as the above-mentioned conditions are met. The second rotation direction virtual line Q2 is drawn at a position shifted from the center of the axial direction A1 of the second rotor magnet 33E to the first axial side A11, but the position of the second rotation direction virtual line Q2 in the axial direction A1 may be the center of the axial direction A1 or may be shifted from the center as long as it is within a range that satisfies the above conditions.

[0083] In the sixth embodiment, the same effects as in the first embodiment can be obtained.

[0084] Furthermore, in the sixth embodiment, since there are no gaps between the rotor magnets, the arrangement density of the first rotor magnets 32E and the second rotor magnets 33E can be increased.

[0085] Seventh Embodiment Another example of the arrangement pattern of rotor magnets in the seventh embodiment will be described using Fig. 14. The basic structure and basic operation of the seventh embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0086] The seventh embodiment is basically the same as the sixth embodiment, and therefore the same reference numerals are used for the same members.

[0087] FIG. 14 is a schematic side view showing the arrangement of magnetic poles of a rotor 3E according to the seventh embodiment. As shown in FIG. 14 , in the rotor 3E, the plurality of first rotor magnets 32E and the plurality of second rotor magnets 33E are arranged in a checkerboard pattern (i.e., a checkered pattern). Specifically, the plurality of first rotor magnets 32E and the plurality of second rotor magnets 33E have the same shape and are arranged in the axial direction A1 and the rotational direction C1. Furthermore, the rows of the first rotor magnets 32E and the rows of the second rotor magnets 33E are alternately arranged in the rotational direction C1, and the rows of the first rotor magnets 32E and the rows of the second rotor magnets 33E are alternately arranged in the axial direction A1.

[0088] Specifically, the first rotor magnets 32E are arranged in the rotational direction C1 in the middle of the axial direction A1. The first rotor magnets 32E are rhombic. The vertices of the first rotor magnets 32E arranged in the rotational direction C1 are in contact with each other.

[0089] The second rotor magnets 33E are arranged in the rotational direction C1 on both sides of the axial direction A1. The second rotor magnets 33E are rhombic, and have the same shape as the first rotor magnets 32E. The second rotor magnets 33E arranged in the rotational direction C1 have their vertices in contact with each other. The second rotor magnets 33E and the first rotor magnets 32E have their sides in contact with each other.

[0090] Furthermore, a third rotor magnet 321E is arranged between the second rotor magnets 33E above in the axial direction A1 in Fig. 14 in the rotational direction C1. A third rotor magnet 321E is also arranged between the second rotor magnets 33E below in the axial direction A1 in Fig. 14 in the rotational direction C1. The third rotor magnet 321E is triangular. Like the first rotor magnet 32E, the third rotor magnet 321E has an S pole. As a result, the multiple first rotor magnets 32E, the multiple second rotor magnets 33E, and the multiple third rotor magnets 321E are arranged without any gaps. With the above configuration, a sinusoidal magnetic flux density distribution can be generated in the axial direction A1 and the rotational direction C1.

[0091] Next, the arrangement pattern of the first rotor magnet 32E and the second rotor magnet 33E will be further described. At different positions in the rotational direction C1 of the rotor 3E, n third axial imaginary lines U1 extending along the axial direction A1 are assumed at equal intervals in the order of 1 to n. Furthermore, at different positions in the axial direction A1 of the rotor 3E, m third rotational imaginary lines V1 are assumed at equal intervals in the order of 1 to m along the rotational direction C1. Of the intersections between the Xth third axial imaginary line U1 and the Yth third rotational imaginary line V1, a first intersection G1 is defined when X and Y are both odd numbers, and a second intersection H1 is defined when X and Y are both even numbers. The first rotor magnet 32E is located at the first intersection G1. The second rotor magnet 33E is located at the second intersection H1.

[0092] In the above configuration, the first rotor magnet 32E and the second rotor magnet 33E are respectively arranged at the first intersection G1 and the second intersection H1 of the third axial virtual line U1 and the third rotational virtual line V1, thereby increasing the arrangement density of the first rotor magnet 32E and the second rotor magnet 33E. Note that, although an example has been described in which the first rotor magnet 32E is located at the first intersection G1 and the second rotor magnet 33E is located at the second intersection H1, the reverse is of course also possible. In other words, a configuration in which the second rotor magnet 33E is located at the first intersection G1 and the first rotor magnet 32E is located at the second intersection H1 may also be used.

[0093] (Modifications) The first to seventh embodiments are merely examples of various embodiments of the present disclosure. The first to seventh embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the first to seventh embodiments are listed below. The modifications described below can be applied in appropriate combinations.

[0094] (1) Modified Examples of Magnetic Bearing In the first to seventh embodiments, the magnetic bearing 5 is integrally incorporated into the bearingless motor 1. However, the magnetic bearing 5 may also be provided independently from the motor.

[0095] The magnetic bearing 5 may be a surface permanent magnet (SPM).

[0096] (2) Modified Examples of Bearingless Motors The rotation control of the bearingless motor 1 is not limited to the three-phase AC type.

[0097] The bearingless motor 1 may be a surface permanent magnet (SPM).

[0098] (3) Modifications of the Stator The number of pole slots of the stator 2 is not limited. When the number of pole slots in the axial direction A1 is increased, the number of phases of the stator 2 may be increased. Furthermore, the stator 2 may be provided with a plurality of thrust coils in the axial direction A1. For example, although the first embodiment includes the first stator core 22 and the second stator core 23, three stator cores may be provided.

[0099] The adjustment of the radial position of the rotor 3 using the radial winding 26 does not have to be performed in three phases, but may be performed in two phases, for example.

[0100] The motor winding 25 and the radial winding 26 may not be distinguished from each other and may serve both roles. That is, one common winding may serve as both the motor winding 25 and the radial winding 26.

[0101] The radial winding 26 and the motor winding 25 may be distributed windings instead of concentrated windings.

[0102] There may be teeth that are not wound with a winding.

[0103] The first teeth 222 and the second teeth 232 may be arranged at unequal intervals in the rotational direction C1 or the axial direction A1.

[0104] The motor winding 25 may be wound separately without spanning the first teeth 222 and the second teeth 232 that are at the same position in the rotation direction C1.

[0105] The radial winding 26 may be wound separately without spanning the first teeth 222 and the second teeth 232 that are at the same position in the rotational direction C1.

[0106] Both the motor winding 25 and the radial winding 26 may be wound around one tooth.

[0107] The stator 2 may be divided in the rotation direction C1, and a thrust coil 37 may be provided in each divided stator.

[0108] The thrust coil 37 does not have to be divided in the rotation direction C1, but in this case, active control in the θx direction and the θy direction using the thrust coil 37 is not possible.

[0109] The first yoke 221 and the second yoke 231 may have a powder magnetic core made by sintering insulating coated iron powder instead of a steel plate.

[0110] The first yoke 221 and the second yoke 231 may not have teeth, and the coils (motor coil 35 and radial coil 36) may be air-core.

[0111] (4) Modified Rotor The number (number of poles) of the first rotor magnets 32 and the second rotor magnets 33 is not limited in either the axial direction A1 or the rotational direction C1.

[0112] The side view shapes of the first rotor magnet 32 ​​and the second rotor magnet 33 are not limited to rectangular or rhombic, but may be, for example, circular, elliptical, or rectangular with rounded corners.

[0113] In the rotational direction C1, the length of the first rotor magnet 32 ​​may be longer or shorter than the length of the second rotor magnet 33. In addition, in the axial direction A1, the length of the first rotor magnet 32 ​​may be shorter than the length of the second rotor magnet 33 or the same as the length of the second rotor magnet 33.

[0114] The first rotor magnets 32 may be arranged at an uneven pitch in the axial direction A1 and the rotational direction C1. The second rotor magnets 33 may be arranged at an uneven pitch in the axial direction A1 and the rotational direction C1. This reduces the cogging torque in the bearingless motor 1.

[0115] The rotor core 31 does not have to be made of an annular member, but may be made of a solid member such as a cylinder.

[0116] The rotor 3 may be of a consequent pole type. In this case, a magnet is provided as one of the north and south poles, and an iron salient pole is provided as the other north and south pole. A flux path may be provided in the gap where there is no magnet.

[0117] In the first embodiment, the ratio between the second rotor magnet 33 and the first gap 38 or the second gap 39 does not have to be 1:1.

[0118] In the first embodiment, in a partial region of the rotor core 31, the magnets may be arranged continuously with the NSNS magnets without any gap in the rotation direction C1.

[0119] The material of rotor core 31 is not limited to laminated steel plates, but may be, for example, bulk magnetic material, a powder magnetic core, a non-ferrous metal, a resin, or the like.

[0120] The divided magnet may not be divided, and the desired magnetic flux density distribution may be achieved by magnetization.

[0121] The magnetization directions of the first rotor magnet 32 ​​and the plurality of second rotor magnets 33 are not limited to any particular direction as long as the pole arrangement described in the claims can be realized. For example, magnetization methods such as parallel magnetization, radial magnetization, and polar anisotropic magnetization may be used.

[0122] (Aspects) The present specification discloses the following aspects.

[0123] A magnetic bearing (5) according to a first aspect includes a rotor (3, 3A, 3B, 3C, 3D, 3E) and a stator (2). The rotor (3, 3A, 3B, 3C, 3D, 3E) has a rotor core (31) that rotates around an axis (R1) extending in an axial direction (A1), and one or more north poles (33, 33A, 33B, 33C, 33D, 33E) and one or more south poles (32, 32A, 32B, 32C, 32D, 32E) provided on the rotor core (31). The stator (2) faces the rotor (3, 3A, 3B, 3C, 3D, 3E) at a predetermined interval in the radial direction. Assuming that a first axial direction imaginary line (P1) and a second axial direction imaginary line (P2) extending along the axial direction (A1) are provided at different positions in the rotation direction (C1) of the rotors (3, 3A, 3B, 3C, 3D, 3E), and that a first rotation direction imaginary line (Q1) and a second rotation direction imaginary line (Q2) extending along the rotation direction (C1) are provided at different positions in the axial direction (A1) of the rotors (3, 3A, 3B, 3C, 3D, 3E), one or more N poles (33, 33A, 33B, 33C, 33D, 33E) and one or more S poles (32, 32A, 32B, 32C, 32D, 32E) are provided as follows. The length of the first axial imaginary line (P1) occupied by the south poles (32, 32A, 32B, 32C, 32D, 32E) is longer than the length of the north poles (33, 33A, 33B, 33C, 33D, 33E), and the length of the second axial imaginary line (P2) occupied by the north poles (33, 33A, 33B, 33C, 33D, 33E) is longer than the length of the south poles (32, 32A, 32B, 32C, 32D, 32E). The length of the first rotation direction imaginary line (Q1) occupied by the south poles (32, 32A, 32B, 32C, 32D, 32E) is longer than the length of the north poles (33, 33A, 33B, 33C, 33D, 33E), and the length of the second rotation direction imaginary line (Q2) occupied by the north poles (33, 33A, 33B, 33C, 33D, 33E) is longer than the length of the south poles (32, 32A, 32B, 32C, 32D, 32E).

[0124] According to this aspect, by arranging one or more north poles (33) and south poles (32) in the rotors (3, 3A, 3B, 3C, 3D, 3E) as described above as a structure for controlling the position of the rotors (3, 3A, 3B, 3C, 3D, 3E) in the axial direction (A1) and in the tilt directions (θx, θy), a magnetic flux density distribution can be generated in the axial direction (A1). Therefore, it is possible to control the rotors (3, 3A, 3B, 3C, 3D, 3E) on both sides of the axial direction (A1). As a result, the rotors (3, 3A, 3B, 3C, 3D, 3E) become thin and short in the axial direction (A1), and the stator (2) also becomes thin and short in the axial direction A1 (Z-axis direction) in accordance with the above configuration of the rotor 3. With the above configuration, a thin magnetic bearing (5) that is short in the axial direction (A1) can be obtained.

[0125] In the magnetic bearing (5) according to the second aspect, in the first aspect, the stator (2) has a plurality of teeth (222, 232), a yoke (221, 231), a first winding (26), and a second winding (27). The plurality of teeth (222, 232) are arranged side by side in the rotational direction (C1) and the axial direction (A1). The yoke (221, 231) magnetically connects at least two of the plurality of teeth (222, 232). The first winding (26) is wound around the teeth (222, 232) to form a radial coil (36) for controlling the radial position of the rotor (3, 3A, 3B, 3C, 3D, 3E). The second winding (27) constitutes a thrust coil (37) for controlling the position of the rotor (3, 3A, 3B, 3C, 3D, 3E) in the axial direction (A1).

[0126] According to this aspect, when a current is applied to the radial coil (36), the magnetic field generated from the radial coil (36) and the magnetic fields generated from the one or more north poles (33, 33A, 33B, 33C, 33D, 33E) and the one or more south poles (32, 32A, 32B, 32C, 32D, 32E) control the position of the rotor (3, 3A, 3B, 3C, 3D, 3E) in the radial direction. Furthermore, when a current is applied to the thrust coil (37), the position of the rotor (3, 3A, 3B, 3C, 3D, 3E) is controlled in the axial direction (A1) by a magnetic field generated from the thrust coil (37) and a magnetic field generated from one or more north poles (33, 33A, 33B, 33C, 33D, 33E) and one or more south poles (32, 32A, 32B, 32C, 32D, 32E).

[0127] In the magnetic bearing (5) according to the third aspect, in the second aspect, the first winding (26) is wound across a plurality of teeth (222, 232) that are positioned at different positions in the axial direction (A1) among the plurality of teeth (222, 232).

[0128] According to this aspect, the coil end can be made shorter than when the winding is wound separately in the axial direction (A1).

[0129] In a magnetic bearing (5) according to a fourth aspect, in the first aspect, the stator (2) has a winding (27) that constitutes a thrust coil (37) that controls the position of the rotor (3, 3A, 3B, 3C, 3D, 3E) in the axial direction (A1). The winding (27) has a plurality of winding portions that are divided in the direction of rotation (C1). Each of the plurality of winding portions independently generates a force that supports the rotor (3, 3A, 3B, 3C, 3D, 3E) in the axial direction (A1), thereby controlling the inclination of the rotor (3, 3A, 3B, 3C, 3D, 3E).

[0130] According to this aspect, when a current is applied to the thrust coil (37), the position of the rotor (3, 3A, 3B, 3C, 3D, 3E) in the axial direction (A1) is controlled by a magnetic field generated from the thrust coil (37) and a magnetic field generated from the one or more north poles (33, 33A, 33B, 33C, 33D, 33E) and the one or more south poles (32, 32A, 32B, 32C, 32D, 32E). When a thrust current is applied so that magnetic fluxes (M1, M2) in the same direction are generated in all winding portions, the position of the rotor (3, 3A, 3B, 3C, 3D, 3E) in the axial direction (A1) is controlled. When a thrust current is applied so that magnetic fluxes (M1, M2) of different directions are generated in some winding portions, the position of the inclination direction (θx, θy) of the rotor (3, 3A, 3B, 3C, 3D, 3E) is controlled.

[0131] In the magnetic bearing (5) according to the fifth aspect, in the first aspect, one or more north poles (33E) and one or more south poles (32E) are arranged as follows. At different positions in the rotation direction (C1) of the rotor (3E), n third axial direction imaginary lines (U1) extending along the axial direction (A1) are assumed at equal intervals in the order of 1 to n. At different positions in the axial direction (A1) of the rotor (3E), m third rotation direction imaginary lines (V1) are assumed at equal intervals in the order of 1 to m along the rotation direction (C1). Of the intersections between the Xth third axial direction imaginary line (U1) and the Yth third rotation direction imaginary line (V1), if the Xth X and the Yth Y are both odd numbers, this is designated as a first intersection (G1), and if both X and Y are even numbers, this is designated as a second intersection (H1). One of the north pole (33E) and the south pole (32E) is located at the first intersection (G1), and the other of the north pole (33E) and the south pole (32E) is located at the second intersection (H1).

[0132] According to this aspect, the north pole (33E) and the south pole (32E) are arranged at the first intersection (G1) and the second intersection (H1) of the third axial direction virtual line (U1) and the third rotation direction virtual line (V1), thereby increasing the arrangement density of the north pole (33E) and the south pole (32E).

[0133] A bearingless motor (1) according to a sixth aspect includes a magnetic bearing (5) and a motor coil (35) for rotating a rotor (3).

[0134] According to this embodiment, a thin bearingless motor (1) that is short in the axial direction (A1) can be obtained.

[0135] REFERENCE SIGNS LIST 1 Bearingless motor 2 Stator 3 Rotor 5 Magnetic bearing 22 First stator core 23 Second stator core 26 Radial winding (first winding) 27 Thrust winding (second winding) 31 Rotor core 32, 32A, 32B, 32C, 32D, 32E First rotor magnet (South pole) 33, 33A, 33B, 33C, 33D, 33E Second rotor magnet (North pole) 35 Motor coil 36 Radial coil 37 Thrust coil 221 First yoke 222 First teeth 231 Second yoke 232 Second teeth P1 First axial imaginary line P2 Second axial imaginary line Q1 First rotational direction imaginary line Q2 Second rotational direction imaginary line U1 Third axial imaginary line V1 Third rotational direction imaginary line G1 First intersection H1 Second intersection R1 Axial center A1 Axial direction 1 Rotation direction

Claims

1. A rotor comprising: a rotor core which rotates about an axis extending in the axial direction; a rotor having one or more N poles and one or more S poles provided on the rotor core; and a stator which faces the rotor at a predetermined distance in the radial direction, wherein when a first axial direction virtual line and a second axial direction virtual line which extend along the axial direction of the rotor are assumed at different positions in the rotational direction of the rotor, and a first rotation direction virtual line and a second rotation direction virtual line which extend along the rotational direction of the rotor are assumed at different positions in the axial direction of the rotor, the length occupied by the S pole on the first axial direction virtual line is longer than the length occupied by the N pole, the length occupied by the N pole on the second axial direction virtual line is longer than the length occupied by the S pole, the length occupied by the S pole on the first rotation direction virtual line is longer than the length occupied by the N pole, and the length occupied by the N pole on the second rotation direction virtual line is longer than the length occupied by the S pole, A magnetic bearing, wherein said one or more north poles and said one or more south poles are provided.

2. A magnetic bearing as described in claim 1, wherein the stator has: a plurality of teeth arranged in the rotational direction and the axial direction; a yoke for magnetically connecting at least two of the plurality of teeth; a first winding wound around the teeth to form a radial coil for controlling the radial position of the rotor; and a second winding forming a thrust coil for controlling the axial position of the rotor.

3. A magnetic bearing as set forth in claim 2, wherein the first winding is wound across a plurality of teeth that are located at different positions in the axial direction among the plurality of teeth.

4. A magnetic bearing as described in claim 1, wherein the stator has a winding that forms a thrust coil that controls the axial position of the rotor, the winding having a plurality of winding portions divided in the rotational direction, and each of the plurality of winding portions independently generates a force that supports the rotor in the axial direction, thereby controlling the inclination of the rotor.

5. The magnetic bearing according to claim 1, wherein, when n third axial direction virtual lines extending along the axial direction are assumed to be equally spaced in the order of 1 to n at different positions in the rotational direction of the rotor, and m third rotation direction virtual lines are assumed to be equally spaced in the order of 1 to m along the rotational direction at different positions in the axial direction of the rotor, a first intersection point is set as an intersection point between an Xth third axial direction virtual line and a Yth third rotation direction virtual line when the Xth X and the Yth Y are both odd numbers, and a second intersection point is set as an intersection point when the X and Y are both even numbers, and one of the N pole and the S pole is located at the first intersection point, and the other of the N pole and the S pole is located at the second intersection point.

6. A bearingless motor comprising: a magnetic bearing according to any one of claims 1 to 5; and a motor coil for rotating the rotor.

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