Magnetic bearing and bearing-less motor

Abstract

In an axial direction (A1) of a rotor (3), a first tooth position (220) is defined as the position of a first tooth set (222) of a stator (2), and a second tooth position (230) is defined as the position of a second tooth set (232). A first magnetization part position is defined as the position of a first magnetization part (32) of the rotor, at which a first magnetic flux flowing from at least one of the first magnetization part and a second magnetization part (33) of the rotor and interlinking with a virtual winding of the first tooth set (222) takes a local maximum value or a local minimum value. A second magnetization part position (330) is defined as the position of the second magnetization part, at which a second magnetic flux flowing from at least one of the first magnetization part and the second magnetization part and interlinking with a virtual winding of the second tooth set takes a local maximum value or a local minimum value. When the first magnetization part position is at the same position as the first tooth position in a state where the position of the rotor in the axial direction is controlled, the second magnetization part position is not at the same position as the second tooth position.

Description

Magnetic Bearing and Bearingless Motor

[0001] The present disclosure relates to a magnetic bearing and a bearingless motor. More specifically, the present disclosure relates to a magnetic bearing and a bearingless motor that actively control at least three axes.

[0002] Patent Document 1 discloses a self-bearing motor (bearingless motor). Generally, a bearingless motor is a rotary electric machine that integrates a motor and a magnetic bearing by providing motor windings and radial support windings on a stator, giving the motor itself a magnetic bearing function.

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

[0004] Japanese Patent Application Laid-Open No. 2008-289340

[0005] In the self-bearing motor of Patent Document 1, it is difficult to control the position of the rotor in the axial direction.

[0006] An object of the present disclosure is to provide a magnetic bearing and a bearingless motor that are easy to control the position of the rotor in the axial center direction.

[0007] A magnetic bearing according to one aspect of the present disclosure comprises 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 first magnetization parts that are one of the north poles and one or more south poles and one or more second magnetization parts that are the other of the north poles and south poles provided on the rotor core. The stator is opposed to the rotor at a predetermined distance in the radial direction. The stator has a first stator core, a second stator core, a first winding, and a second winding. The magnetic bearing comprises magnets or coils for magnetizing one or more first magnetization parts and magnets or coils for magnetizing one or more second magnetization parts. The first stator core has a plurality of first teeth arranged in the rotational direction of the rotor, and a first yoke for magnetically connecting at least two of the plurality of first teeth.

[0008] The second stator core includes a plurality of second teeth arranged in a rotational direction, and a second yoke for magnetically connecting at least two of the plurality of second teeth.

[0009] The first winding is wound around at least one of the multiple first teeth and the multiple second teeth to form a radial coil for controlling the radial position of the rotor.

[0010] The second winding constitutes a thrust coil for controlling the axial position of the rotor. At least a portion of the first winding and at least a portion of the second winding are in the same axial position.

[0011] Assume a first axial imaginary line and a second axial imaginary line extending along the axial direction at positions with different rotational directions. Assume a first rotational imaginary line extending along the rotational direction at positions where one or more first magnetization parts are located, and a second rotational imaginary line extending along the rotational direction at positions where one or more second magnetization parts are located.

[0012] One or more first magnetized parts and one or more second magnetized parts are provided such that the length occupied by one or more first magnetized parts in the first axial direction virtual line is longer than the length occupied by one or more second magnetized parts, and the length occupied by one or more second magnetized parts in the second axial direction virtual line is longer than the length occupied by one or more first magnetized parts.

[0013] One or more first magnetized parts and one or more second magnetized parts are provided such that the length occupied by one or more first magnetized parts in the first rotation direction virtual line is longer than the length occupied by one or more second magnetized parts, and the length occupied by one or more second magnetized parts in the second rotation direction virtual line is longer than the length occupied by one or more first magnetized parts.

[0014] The predetermined positions in the axial direction of multiple first teeth are defined as first tooth positions, and the predetermined positions in the axial direction of multiple second teeth are defined as second tooth positions. The first tooth positions and second tooth positions are at different positions in the axial direction. Assume that there is one first virtual winding wound around each of the multiple first teeth and one second virtual winding wound around each of the multiple second teeth. The first magnetic flux is defined as the fundamental wave component of the magnetic flux extending from at least one of one of the one or more first magnetization parts and one or more second magnetization parts that are linked with the first virtual winding. When the rotor moves in the axial direction, the position of the portion of the first magnetization part that is at the same position as the first tooth position in the axial direction when the first magnetic flux takes a maximum or minimum value is defined as the first magnetization part position. The second magnetic flux is defined as the fundamental wave component of the magnetic flux extending from at least one of the one or more first magnetization parts and one or more second magnetization parts that are linked with the second virtual winding. The position of the second magnetization part is defined as the position of the portion of the second magnetization part that is at the same position as the second teeth position in the axial direction when the rotor moves in the axial direction and the second magnetic flux takes a maximum or minimum value.

[0015] When the rotor's axial position is controlled, if the position of the first magnetized part is the same as the position of the first tooth in the axial direction, the position of the second magnetized part is not the same as the position of the second tooth.

[0016] A bearingless motor according to one aspect of the present disclosure comprises a magnetic bearing and a motor coil for rotating the rotor.

[0017] The magnetic bearing and bearingless motor of this disclosure, while being small and having a relatively simple configuration, enable five-axis active control of the rotor in the radial direction, axial direction, and tilt direction.

[0018] Figure 1 is a perspective view of a bearingless motor according to the first embodiment of this disclosure. Figure 2 is a perspective view of the stator of the bearingless motor. Figure 3 is a partially enlarged perspective view of the stator. Figure 4 is a perspective view of the rotor of the bearingless motor. Figure 5 is a side view of the rotor. Figure 6 is a schematic block diagram showing the control configuration of the bearingless motor. Figure 7 is a schematic diagram showing the principle of thrust force generation in the bearingless motor, showing the generation of a first magnetic flux by applying a positive thrust current. Figure 8 is a schematic diagram showing the principle of thrust force generation in the bearingless motor, showing the generation of a second magnetic flux by applying a negative thrust current. Figure 9 is a perspective view of the rotor of a bearingless motor according to the second embodiment. Figure 10 is a side view of the rotor. Figure 11 is a perspective view of the rotor of a bearingless motor according to the third embodiment. Figure 12 is a side view of the rotor. Figure 13 is a perspective view of a bearingless motor according to the fourth embodiment with a portion cut out. Figure 14 shows the relationship between the rotor axial displacement and the differential value of the flux linkage.

[0019] (First Embodiment) (1) The bearingless motor 1 and magnetic bearing 5 will be described using the overall configuration diagram 1 of the bearingless motor and magnetic bearing. The bearingless motor 1 is used, for example, in a semiconductor spin coater (not shown).

[0020] The bearingless motor 1 is a radial gap type motor and comprises a stator 2 and a rotor 3. The bearingless motor 1 rotates the rotor 3 while magnetically levitating it. The rotor 3 rotates around an axis R1 that extends in the axial direction A1 along the Z axis of a Cartesian coordinate system having X, Y, and Z axes. In the following description, the direction along the X axis will be referred to as the X-axis direction, the direction along the Y axis as the Y-axis direction, and the direction along the Z axis as the Z-axis direction. In the following description, the Z-axis direction will be described as the axial direction A1.

[0021] 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).

[0022] The magnetic bearing 5 comprises a stator 2 and a rotor 3. The bearingless motor 1 also comprises the magnetic bearing 5 and a motor coil 35 for rotating the rotor 3.

[0023] (2) Stator Figures 2 and 3 will be used to explain the stator 2.

[0024] (2-1) Frame, first stator core, and second stator core The stator 2 comprises 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 sides of the frame 21 in the axial direction A1.

[0025] The first stator core 22 includes 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. The steel plates are made of electromagnetic steel, such as silicon steel. The plurality of first teeth 222 are arranged in the rotational direction C1 on the inner circumferential edge of the first yoke 221 (in the first embodiment, they are arranged at equal intervals in the rotational direction C1). In other words, the first yoke 221 magnetically connects at least two of the plurality of first teeth 222. In the first embodiment, the first yoke 221 magnetically connects all of the plurality of first teeth 222. The plurality of first teeth 222 extend from the first yoke 221 toward the axis R1, and their tips are close to the outer circumferential surface of the rotor 3.

[0026] The second stator core 23 includes 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. The steel plates are formed from, for example, electromagnetic steel plates such as silicon steel plates. The plurality of second teeth 232 are arranged in the rotational direction C1 on the inner circumferential edge of the second yoke 231 (in the first embodiment, they are arranged at equal intervals in the rotational direction C1). In other words, the second yoke 231 magnetically connects at least two of the plurality of second teeth 232. In the first embodiment, the second yoke 231 magnetically connects all of the plurality of second teeth 232. The plurality of second teeth 232 extend from the second yoke 231 toward the axis R1, and their tips are close to the outer circumferential surface of the rotor 3.

[0027] As described above, the multiple first teeth 222 and second teeth 232 are arranged in the rotational direction C1 and the axial direction A1.

[0028] (2-2) Motor winding, radial winding, and thrust winding stator 2 has a motor winding 25 (winding), a radial winding 26 (first winding), and a thrust winding 27 (second winding).

[0029] The motor winding 25 is a winding for generating torque on the rotor 3. Since rotational control in the bearingless motor 1 is performed in three phases, the motor coil 35 is formed by winding U-phase, V-phase, and W-phase windings around the first teeth 222 and the second teeth 232 as the motor coil winding. More specifically, the motor winding 25 is wound across two first teeth 222 and second teeth 232 that are aligned in the axial direction A1 (i.e., their positions in the rotational direction C1 are the same). In this case, the coil end can be shortened compared to when the motor winding 25 is wound in sections along the axial direction A1.

[0030] The radial winding 26 is a winding that generates a radial support force (in a direction perpendicular to the axial direction A1) that supports the rotor 3. In other words, the radial winding 26 controls the radial position of the rotor 3 relative to the stator 2. In the first embodiment, since the radial position of the rotor 3 in the bearingless motor 1 is adjusted in three phases, the radial winding 26 is made up of U-phase, V-phase, and W-phase windings wound around the first teeth 222 and the second teeth 232 to form a radial coil 36. More specifically, the radial winding 26 is wound across two first teeth 222 and teeth that are aligned in the axial direction A1 (i.e., the position in the rotation direction C1 is the same). In this case, the coil end can be shortened compared to when the radial winding 26 is wound in a divided manner in the axial direction A1.

[0031] The thrust winding 27 is a winding for generating support force in the axial direction A1 and the tilt directions θx and θy of the rotor 3. In other words, the thrust winding 27 controls the position and tilt of the rotor 3 in the axial direction A1 relative to the stator 2. The thrust winding 27 is arranged 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 constitutes the thrust coil 37.

[0032] At least a portion of the radial winding 26 and a portion of the thrust winding 27 are located in the same position in the axial direction A1.

[0033] The thrust coil 37 has multiple (six in this embodiment) thrust coils 37 (multiple winding portions) divided in the rotation direction C1. Each of the multiple 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).

[0034] Note that in the drawings (Figures 1, 2, 3, 7, and 8), the coil ends of the motor winding 25 and radial winding 26 are omitted.

[0035] (3) Rotor 3 will be explained using Figures 4 and 5.

[0036] The rotor 3 is integrally attached to the rotating body (not shown) to which the output is directed, 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, one or more first magnetization sections 32, and one or more second magnetization sections 33. The magnetic bearing 5 included in the bearingless motor 1 has a magnet or coil for magnetizing the first magnetization section 32 and a magnet or coil for magnetizing the second magnetization section 33. The bearingless motor 1 of this embodiment is an IPM (Internal Permanent Magnet) motor. That is, magnets (permanent magnets) are embedded inside the first magnetization section 32 and the second magnetization section 33.

[0037] The rotor core 31 is an annular member and is rotatable about the axis R1.

[0038] The first magnetized portion 32 is a convex portion formed on the outer surface side of the rotor core 31. The second magnetized portion 33 is a convex portion formed on the outer surface side of the rotor core 31.

[0039] The first magnetized section 32 is magnetized to become an N pole by a magnet embedded inside the first magnetized section 32.

[0040] The second magnetization section 33 is magnetized to become a south pole by a magnet embedded inside the second magnetization section 33.

[0041] As shown in Figure 4, in the rotation direction C1, the length of the first magnetized portion 32 is the same as the length of the second magnetized portion 33. In the axial direction A1, the length of the first magnetized portion 32 is longer than the length of the second magnetized portion 33. The multiple first magnetized portions 32 and the multiple second magnetized portions 33 are arranged in a checkerboard pattern. Specifically, the multiple first magnetized portions 32 are arranged in the rotation direction C1 with gaps between them and at equal pitches (or equal intervals). The multiple second magnetized portions 33 are arranged in the axial direction A1 and the rotation direction C1 with gaps between them and at equal pitches (or equal intervals). Furthermore, the rows of first magnetized portions 32 and rows of second magnetized portions 33 are arranged alternately in the rotation direction C1, and the rows of first magnetized portions 32 and rows of second magnetized portions 33 are arranged alternately in the axial direction A1.

[0042] On the outer surface of the rotor core 31, in the intermediate portion in the axial direction A1, a first magnetized portion 32 and a first gap 38 (a region where no magnetic poles are located) are alternately provided in the rotation direction C1. Furthermore, a second gap 39 is provided on both sides of the first magnetized portion 32 in the axial direction A1. The first magnetized portion 32 is a long rectangle in the rotation direction C1. The length of the first magnetized portion 32 and the first gap 38 are the same in both the axial direction A1 and the rotation direction C1.

[0043] On the outer peripheral surface of the rotor core 31, on both sides in the axial direction A1, the second magnetization portions 33 and the aforementioned second gaps 39 are alternately arranged in the rotational direction C1. The second magnetization portions 33 have the same shape as the first magnetization portions 32 and are rectangles long in the rotational direction C1. The second magnetization portions 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 magnetization portions 33 in the rotational direction C1 coincides with the position of the first gaps 38. The position of the second magnetization portions 33 in the axial direction A1 coincides with the position of the second gaps 39. Summing up the above, the first magnetization portions 32, the second magnetization portions 33, the first gaps 38, and the second gaps 39 have the same length in the axial direction A1 and further have the same length in the rotational direction C1. Further, when viewed from the axial direction A1, the first magnetization portions 32 and the second magnetization portions 33 do not overlap, and when viewed in the rotational direction C1, the first magnetization portions 32 and the second magnetization portions 33 do not overlap. That is, the edges of the first magnetization portions 32 in the rotational direction C1 and the edges of the second magnetization portions 33 in the rotational direction C1 have the same position in the rotational direction C1. Further, the edges of the first magnetization portions 32 in the axial direction A1 and the edges of the second magnetization portions 33 in the axial direction A1 have the same position in the axial direction A1. With the above configuration, it is possible to generate a magnetic flux density distribution mainly including a fundamental wave component corresponding to the number of magnetic poles arranged in the axial direction A1 and the rotational direction C1.

[0044] In FIG. 5, first axial-direction virtual lines P1 and second axial-direction virtual lines P2 extending along the axial direction A1 are assumed at different positions in the rotational direction C1 of the rotor 3. Also, first rotational-direction virtual lines Q1 and second rotational-direction virtual lines Q2 extending along the rotational direction C1 are assumed at different positions in the axial direction A1 of the rotor 3. The first rotational-direction virtual line Q1 extends along the rotational direction C1 at the position of one or more of the first magnetization portions 32. The second rotational-direction virtual line Q2 extends along the rotational direction C1 at the position of one or more of the second magnetization portions 33 on the first side A11 in the axial direction.

[0045] In this case, a plurality of first magnetization portions 32 and a plurality of second magnetization portions 33 are provided as follows. The length occupied by the first magnetization portion 32 among the first axial direction virtual lines P1 is longer than the length occupied by the second magnetization portion 33, and the length occupied by the second magnetization portion 33 among the second axial direction virtual lines P2 is longer than the length occupied by the first magnetization portion 32. Further, the length occupied by the first magnetization portion 32 among the first rotation direction virtual lines Q1 is longer than the length occupied by the second magnetization portion 33, and the length occupied by the second magnetization portion 33 among the second rotation direction virtual lines Q2 is longer than the length occupied by the first magnetization portion 32.

[0046] In FIG. 5, the first axial direction virtual line P1 is drawn at the center of the rotation direction C1 of the first magnetization portion 32, but the position of the first axial direction virtual line P1 in the rotation direction C1 is not limited to the center of the rotation direction C1 of the first magnetization portion 32. The second axial direction virtual line P2 is drawn at the center of the rotation direction C1 of the second magnetization portion 33, but the position of the second axial direction virtual line P2 in the rotation direction C1 is not limited to the center of the rotation direction C1 of the second magnetization portion 33. The first rotation direction virtual line Q1 is drawn at the center of the axial direction A1 of the first magnetization portion 32, but the position of the first rotation direction virtual line Q1 in the axial direction A1 is not limited to the center of the axial direction A1 of the first magnetization portion 32. The second rotation direction virtual line Q2 is drawn at the center of the axial direction A1 of the first magnetization portion 32, but the position of the second rotation direction virtual line Q2 in the axial direction A1 is not limited to the center of the axial direction A1 of the first magnetization portion 32.

[0047] (4) Control configuration of the magnetic bearing The control configuration of the magnetic bearing 5 will be described using FIG. 6.

[0048] The magnetic bearing main body 50 is composed of a part of the stator 2 and the rotor 3. The magnetic bearing main body 50 is a so-called radial gap type magnetic bearing. The magnetic bearing main body 50 controls the positions of the translational movement (X) in the X-axis direction, the translational movement (Y) in the Y-axis direction, the translational movement (Z) in the Z-axis direction, the tilting movement (θx) around the X-axis, and the tilting movement (θy) around the Y-axis of the rotor 3.

[0049] As shown in Figure 6, the magnetic bearing 5 further comprises a magnetic bearing body 50, a control unit 51, a position sensor 521, an angle sensor 522, and a current generating unit 53. In other words, the magnetic bearing body 50 refers to the part of the magnetic bearing 5 excluding the control unit 51, the position sensor 521, the angle sensor 522, and the current generating unit 53. Similarly, the bearingless motor body 10 refers to the part of the bearingless motor 1 excluding the control unit 51, the position sensor 521, the angle sensor 522, and the current generating unit 53.

[0050] The control unit (control calculation unit) 51 includes, for example, a levitation control unit, a current control unit, and an attitude calculation unit. Each function of the control unit 51 is implemented, for example, by a computer. The magnetic bearing 5 has a processing board, for example, a printed circuit board with electronic circuits (electrical circuits) printed on its surface. The processing board includes a CPU (Central Processing Unit) and memory, etc., and constitutes a computer.

[0051] 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 that detects the distance to the surface of the rotor 3. The type of position sensor 521 is not limited.

[0052] 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 angle sensor 522 is not limited.

[0053] The current generating unit 53 includes an AC power supply, or an inverter and a DC power supply, and can apply AC to the motor coil 35, and can also apply AC to the radial coil 36 and the thrust coil 37.

[0054] (5) Operation of the bearingless motor (5-1) The rotor rotation control unit 51 controls the current generation unit 53 to supply alternating current from the current generation unit 53 to the motor coil 35. As a result, torque is generated in the rotor 3 by the magnetic field generated from the motor coil 35 and the magnetic fields generated from the first magnetization unit 32 and the second magnetization unit 33, causing the rotor 3 to rotate.

[0055] (5-2) The position control unit 51 in the X-axis and Y-axis directions supplies alternating current from the current generation unit 53 to the radial coil 36 based on detection signals from the position sensor 521 and the angle sensor 522. As a result, the rotor 3 is positioned in the X-axis and Y-axis directions by the magnetic field generated from the radial coil 36 and the magnetic fields generated from the first magnetization unit 32 and the second magnetization unit 33.

[0056] (5-3) The Z-axis position control operation control unit 51 supplies alternating current from the current generation unit 53 to the thrust coil 37 based on the detection signal from the position sensor 521. As a result, the rotor 3 is positioned in the axial direction A1 by the magnetic field generated from the thrust coil 37 and the magnetic fields generated from the first magnetization unit 32 and the second magnetization unit 33. In this case, the control unit 51 controls the current generation unit 53 so that all thrust coils 37 generate thrust force on the same side of the axial direction A1 (the first side A11 or the second side A12).

[0057] Using Figures 7 and 8, the principle of generating thrust force acting on the portion of the rotor 3 facing the thrust coil 37 when a positive thrust current and a negative thrust current are applied to a single thrust coil 37 will be explained.

[0058] In Figure 7, a positive thrust current is applied to the thrust coil 37, causing the thrust coil 37 to generate a magnetic flux M1 in the first direction. The magnetic flux M1 in the first direction flows from the frame 21 to the first stator core 22, from the first stator core 22 to the first magnetized section 32, from the first magnetized section 32 to the rotor core 31, from the rotor core 31 to the second magnetized section 33 on the second side A12 in the axial direction, from the second magnetized section 33 on the second side A12 in the axial direction 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 in the first side A11 in the axial direction.

[0059] In Figure 8, a negative thrust current is applied to the thrust coil 37, causing the thrust coil 37 to generate a second-direction magnetic flux M2. The second-direction magnetic flux M2 flows from the frame 21 to the second stator core 23, from the second stator core 23 to the first magnetization section 32, from the first magnetization section 32 to the rotor core 31, from the rotor core 31 to the second magnetization section 33 on the first side A11 in the axial direction, from the second magnetization section 33 on the first side A11 in the axial direction 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, towards the second side A12 in the axial direction.

[0060] Furthermore, when the first tooth position 220 is located between the second magnetized portion 33 and the first magnetized portion 32 on the first axial side A11, and the second tooth position 230 is located between the second magnetized portion 33 and the first magnetized portion 32 on the second axial side A12, the thrust force per unit current of the current applied to the thrust winding 27 becomes larger.

[0061] Furthermore, the securing of thrust forces F1 and F2 will be described in detail later in (5-5).

[0062] (5-4) The position control unit 51 for the θx-axis and θy-axis directions supplies current from the current generation unit 53 to the thrust coil 37 based on the detection signal from the position sensor 521. As a result, the rotor 3 is positioned in the θx-axis and θy-axis directions by the magnetic field generated from the thrust coil 37 and the magnetic fields generated from the first magnetization unit 32 and the second magnetization unit 33. In this case, for example, the control unit 51 controls the current generation unit 53 so that the thrust coils 37 arranged continuously in the three rotation directions C1 generate a thrust force on the same side of the axial direction A1 (the first side A11 or the second side A12), and the thrust coils 37 arranged continuously in the remaining three rotation directions C1 generate a thrust force on the opposite side of the axial direction A1 (the first side A11 or the second side A12).

[0063] (5-5) Securing Thrust Force In (5-3) above, it was explained that the position in the Z-axis direction can be controlled by thrust force F1 and thrust force F2. However, thrust force F1 does not occur when the magnetic flux M1 in the first direction extends radially between the stator 2 and the rotor 3 and there is no component of the magnetic flux M1 in the axial direction A1.

[0064] Therefore, in this embodiment, the positional relationship between the first teeth 222 and the first magnetized portion 32, and the positional relationship between the second teeth 232 and the second magnetized portion 33 in the axial direction A1 are characterized so that the component of the magnetic force acting between the stator 2 and the rotor 3 in the axial direction A1 is not zero.

[0065] As shown in Figure 7, first, the positions of the first teeth 222 and the second teeth 232 in the axial direction A1 will be described. The predetermined position of a plurality of first teeth 222 in the axial direction A1 is defined as the first tooth position 220. The first tooth position 220 is expressed as a coordinate value on the Z axis. The first tooth position 220 is, for example, the center position of the first tooth 222 in the axial direction A1, but it does not have to be the center position of the first tooth 222 in the axial direction A1. Also, the predetermined position of a plurality of second teeth 232 in the axial direction A1 is defined as the second tooth position 230. The second tooth position 230 is expressed as a coordinate value on the Z axis. The second tooth position 230 is, for example, the center position of the second tooth 232 in the axial direction A1, but it does not have to be the center position of the second tooth 232 in the axial direction A1. The first tooth position 220 and the second tooth position 230 are at different positions in the axial direction A1.

[0066] Next, the positions of the first magnetization section 32 and the second magnetization section 33 in the axial direction A1 will be described. When the rotor 3 moves in the axial direction A1, the rotor 3 is stopped in a state where the first magnetic flux, which will be described later, takes on a maximum or minimum value. Here, the first magnetic flux refers to the fundamental wave component of the magnetic flux extending from at least one of the first magnetization section 32 and the second magnetization section 33 that links with the first virtual winding, assuming that one first virtual winding is wound around each of the multiple first teeth 222. The position of the part of the first magnetization section 32 that is at the same position as the first tooth position 220 in the axial direction A1 when the first magnetic flux takes on a maximum or minimum value is defined as the first magnetization section position 320. In other words, the first magnetization section position 320 is the position in the axial direction A1 of the core part of the first magnetization section 32, which has the highest magnetic flux density. The position 320 of the first magnetization area is represented as a coordinate value on the Z-axis.

[0067] Furthermore, when the rotor 3 moves in the axial direction A1, the rotor 3 is stopped in a state where the second magnetic flux, described later, takes on a maximum or minimum value. Here, the second magnetic flux refers to the fundamental wave component of the magnetic flux extending from at least one of the first magnetization section 32 and the second magnetization section 33 that links with the second virtual winding, assuming that one second virtual winding is wound around each of the multiple second teeth 232. The position of the part of the second magnetization section 33 that is at the same position as the second tooth position 230 in the axial direction A1 when the second magnetic flux takes on a maximum or minimum value is defined as the second magnetization section position 330. The second magnetization section position 330 is expressed as a coordinate value on the Z axis.

[0068] In the state where the position of the rotor 3 in the axial direction A1 is controlled, when the first magnetized portion position 320 is at the same position as the first tooth position 220 in the axial direction A1, the second magnetized portion position 330 is not at the same position as the second tooth position 230. In the first embodiment, when the first magnetized portion position 320 is at the same position as the first tooth position 220, the second magnetized portion position 330 of the second magnetized portion 33 on the second side A12 in the axial direction is not at the same position as the second tooth position 230. Note that if there are multiple second magnetized portions 33 in the axial direction A1 as in the first embodiment, when the first magnetized portion position 320 is at the same position as the first tooth position 220, it is sufficient that the second magnetized portion position 330 of the second magnetized portion 33 located at any position in the axial direction A1 is not at the same position as the second tooth position 230.

[0069] As a result, either the axial component A1 (thrust component) of the magnetic force acting between the first magnetization section 32 and the stator 2 (either the first stator core 22 or the second stator core 23) or the axial component A1 (thrust component) of the magnetic force acting between the second magnetization section 33 and the stator 2 (either the first stator core 22 or the second stator core 23) is always generated, thus ensuring thrust force.

[0070] (5-6) Magnitude of Thrust Force In (5-5) above, we explained how to secure thrust force, but here we will explain how to increase the amount of thrust force generated.

[0071] First, the magnetic force acting between the first magnetization section 32 and the stator 2 (either or both of the first stator core 22 and the second stator core 23) will be explained.

[0072] Let X1 be the relative position (rotor axial displacement) of the first magnetization section position 320 with respect to the first tooth position 220 when the rotor 3 moves in the axial direction A1 (see reference numeral 61 in Figure 14). That is, equation (1) X1 is expressed as: X1 = coordinate value of the first magnetization section position 320 on the Z axis - coordinate value of the first tooth position 220 on the Z axis. Note that in Figure 14, the rotor axial displacement, flux linkage, and the derivative of the flux linkage are shown in dimensionless form.

[0073] Next, the magnitude of the first magnetic flux (flux linkage) is expressed as a function value with X1 as the variable, and this is denoted as Y1 (see Figure 14). That is, it is expressed as equation (2) Y1 = F1(X1).

[0074] Next, let Y1' be the value of the derivative obtained by differentiating Y1 with respect to X1 (the derivative of the flux linkage) (see reference numeral 62 in Figure 14). That is, it can be expressed as equation (3) Y1' = f1(X1) = dF1(X1) / dX1.

[0075] Next, let Y1'abs be the value with the smaller absolute value between the maximum and minimum values ​​of Y1'.

[0076] Next, the positional relationship is such that, while the rotor 3 is controlled to the stator 2 in the axial direction A1, the minimum value of Y1' in X1 within the stroke range of the axial direction A1 is 50% or more of Y1'abs. That is, in the magnetic bearing 5 (bearingless motor 1), while the rotor 3 is controlled to the axial direction A1, the minimum value of Y1', Y1'min, in X1 within the position range satisfies equation (4) Y1'min ≥ Y1'abs × 0.5.

[0077] Next, the magnetic force acting between the second magnetization section 33 and the stator 2 (either or both of the first stator core 22 and the second stator core 23) will be explained.

[0078] Let X2 be the relative position (rotor axial displacement) of the second magnetization section position 330 with respect to the second tooth position 230 when the rotor 3 moves in the axial direction A1 (see Figure 14). That is, equation (5) X2 is expressed as: X2 = Z-axis coordinate value of the second magnetization section position 330 - Z-axis coordinate value of the second tooth position 230.

[0079] Next, the magnitude of the second magnetic flux (flux linkage) is expressed as a function value with X² as the variable, and this is denoted as Y² (see Figure 14). That is, it is expressed as equation (6) Y² = F²(X²).

[0080] Next, let Y2' be the value of the derivative obtained by differentiating Y2 with respect to X2 (the derivative of the flux linkage) (see Figure 14). That is, it is expressed as equation (7) Y2' = f2(X2) = dF2(X2) / dX2.

[0081] Next, let Y2'abs be the value with the smaller absolute value between the maximum and minimum values ​​of Y2'.

[0082] Next, the positional relationship is such that, while the rotor 3 is controlled to the stator 2 in the axial direction A1, the minimum value of Y2' in X2 within the stroke range of axial direction A2 is 50% or more of Y2'abs. That is, in the magnetic bearing 5 (bearingless motor 1), while the rotor 3 is controlled to the axial direction A1, the minimum value of Y2', Y2'min, in X2 within the position range satisfies equation (8) Y2'min ≥ Y2'abs × 0.5.

[0083] The larger the differential values ​​of the flux linkage (Y1', Y2'), the greater the thrust force that the rotor 3 receives from the stator 2 per unit current of the current flowing through the thrust winding 27. Therefore, thrust force can be generated efficiently. In this embodiment, x is set to 0.5 in the following conditions: Y1'min ≥ Y1'abs × x and Y2'min ≥ Y2'abs × x. However, the value of x is not limited to 0.5, and values ​​between 0.3 and 0.9, such as 0.3, 0.6, 0.7, 0.8, 0.9, etc., can be appropriately adopted, and furthermore, values ​​outside the range of 0.3 to 0.9 may also be adopted.

[0084] (6) Effect: As a structure for controlling the position of the rotor 3 in the axial direction A1 and in the tilt directions θx and θy, a plurality of first magnetization parts 32 and second magnetization parts 33 are provided on the rotor 3, which makes it possible to generate a magnetic flux density distribution in the axial direction A1. In addition, a plurality of thrust coils 37 are provided on the stator 2, and the direction of the current flowing through the thrust coils 37 is changed, which makes it possible to control the rotor 3 on both sides of the axial direction A1.

[0085] Therefore, the rotor 3 has a simple structure. In particular, the rotor 3 is thin and short in the axial direction A1.

[0086] The stator 2 is also thin and short in the axial direction A1, in accordance with the above configuration of the rotor 3.

[0087] With the above configuration, the magnetic bearing 5 and the bearingless motor 1 are thin and short in the axial direction A1, making them suitable for use in, for example, semiconductor spin coaters (not shown).

[0088] Furthermore, since either the axial component A1 (thrust component) of the magnetic force acting between the first magnetization section 32 and the stator 2 (either the first stator core 22 or the second stator core 23) or the axial component A1 (thrust component) of the magnetic force acting between the second magnetization section 33 and the stator 2 (either the first stator core 22 or the second stator core 23) is always present, a thrust force can be ensured. This makes it easier to control the position of the rotor 3 in the axial direction A1.

[0089] (Second Embodiment) The second embodiment will be described using Figures 9 and 10. The basic structure and operation of the second embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0090] In the second embodiment, a magnet 301 is embedded in the rotor core 31 in the portion between the first magnetized portion 32 and the second magnetized portion 33 in the rotation direction C1. This creates a magnetic flux flow as shown by the arrow in Figure 9.

[0091] This allows rotor 3 to obtain a stronger magnetic force.

[0092] (Third Embodiment) The third embodiment will be described using Figures 11 and 12. The basic structure and operation of the third embodiment are the same as those of the second embodiment, so the following description will focus on the differences.

[0093] In the third embodiment, a magnet 302 is provided on the surface of the rotor core 31 in the portion between the first magnetized portion 32 and the second magnetized portion 33 in the rotation direction C1. Additionally, a ring magnet 303 is provided on the surface of the rotor core 31 in the portion between the first magnetized portion 32 and the second magnetized portion 33 in the axial direction A1. This creates a magnetic flux flow as shown by the arrow in Figure 11.

[0094] This allows rotor 3 to obtain a stronger magnetic force.

[0095] (Fourth Embodiment) The fourth embodiment will be described using Figure 13. The basic structure and operation of the fourth embodiment are the same as those of the second embodiment, so the following description will focus on the differences.

[0096] In the fourth embodiment, a claw pole rotor is provided as the rotor 3.

[0097] This allows rotor 3 to obtain a stronger magnetic force.

[0098] (Modifications) Embodiments 1 to 7 are merely one of many embodiments of the present disclosure. Embodiments 1 to 7 can be modified in various ways depending on the design, etc., as long as the objectives of the present disclosure are achieved. Modifications of Embodiments 1 to 7 are listed below. The modifications described below can be combined and applied as appropriate.

[0099] (1) Modified Examples of Magnetic Bearings In the first to seventh embodiments, the magnetic bearing 5 is integrally incorporated into the bearingless motor 1. However, the magnetic bearing 5 may be provided separately from the motor.

[0100] The magnetic bearing 5 may also be an SPM (Surface Permanent Magnet).

[0101] (2) Modified form of bearingless motor The rotation control in the bearingless motor 1 is not limited to a three-phase AC type.

[0102] The bearingless motor 1 may also be an SPM (Surface Permanent Magnet).

[0103] (3) Modification of the stator The number of pole slots of the stator 2 is not limited. When increasing the number of pole slots in the axial direction A1, the number of phases of the thrust coil 37 may be increased. Also, multiple thrust coils may be provided in the axial direction A1. For example, in the first embodiment, a first stator core 22 and a second stator core 23 are provided, but three stator cores may be provided.

[0104] The radial position adjustment of the rotor 3 using the radial windings 26 does not necessarily have to be performed in three phases; for example, it may be performed in two phases.

[0105] The motor winding 25 and the radial winding 26 are not distinguished and may serve both roles. In other words, a single common winding may serve both the motor winding 25 and the radial winding 26.

[0106] The radial windings 26 and motor windings 25 do not have to be concentrated windings; they can also be distributed windings.

[0107] It is acceptable for some teeth not to have a winding.

[0108] 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.

[0109] The motor windings 25 may be wound separately, without spanning the first teeth 222 and the second teeth 232, which are in the same position in the rotation direction C1.

[0110] The radial windings 26 may be wound separately, without spanning the first teeth 222 and the second teeth 232, which are in the same position in the rotation direction C1.

[0111] Both the motor winding 25 and the radial winding 26 may be wound around a single tooth.

[0112] The thrust winding 27 may be provided spanning the first tooth 222 and the second tooth 232, or it may be wound separately without spanning the first tooth 222 and the second tooth 232.

[0113] First teeth 222, second teeth 232, third teeth, fourth teeth, ... may be provided in the axial direction A1, with the U-phase (or V-phase, W-phase) winding of the motor winding 25 wound around the first tooth 222, the V-phase (or W-phase, U-phase) winding of the motor winding 25 wound around the second tooth 232, the W-phase (or U-phase, V-phase) winding of the motor winding 25 wound around the third tooth, and the U-phase (or V-phase, W-phase) winding of the motor winding 25 ... wound around the fourth tooth.

[0114] The stator 2 may be divided in the rotational direction, and thrust coils 37 may be provided on one or more (including all) divided stators.

[0115] The thrust coil 37 does not necessarily have to be divided in the rotational direction. However, in this case, active control in the θx and θy directions using the thrust coil 37 is not possible.

[0116] The thrust coil 37 does not necessarily have to be wound across multiple teeth in the rotational direction.

[0117] One, two, or all of the motor windings 25, radial windings 26, and thrust windings 27 may be wound around one or both of the first yoke 221 and the second yoke 231, but may not be wound around the first teeth 222 or the second teeth 232.

[0118] The first stator core 22 and the second stator core 23 may not be made of steel plates, but rather have a compacted magnetic core made of insulated iron powder that has been sintered.

[0119] The first yoke 221 and the second yoke 231 do not have teeth, and the coils (motor coil 35 and radial coil 36) may be air-cored.

[0120] The first magnetized portion 32 may be magnetized to the south pole (or north pole) by a magnet or coil provided on the stator 2.

[0121] The second magnetized portion 33 may be magnetized to an N pole (or S pole) by a magnet or coil provided on the stator 2.

[0122] (4) Modifications of the rotor The first magnetized portion 32 may be magnetized to the south pole (or north pole) by a magnet provided on the surface of the rotor core 31. Alternatively, a magnet may be provided in the first gap 38 between adjacent first magnetized portions 32, 32. Alternatively, the first magnetized portion 32 may be magnetized to the south pole (or north pole) by a coil provided on the rotor core 31.

[0123] The second magnetized portion 33 may be magnetized to a north pole (or south pole) by a magnet provided on the surface of the rotor core 31. Alternatively, a magnet may be provided in the second gap 39 between adjacent second magnetized portions 33, 33. Furthermore, the second magnetized portion 33 may be magnetized to a north pole (or south pole) by a coil provided on the rotor core 31.

[0124] The magnets provided on the rotor 3 may be divided into sections.

[0125] The number of first magnetization units 32 and the number of second magnetization units 33 (number of poles) is not limited in either the axial direction A1 or the rotational direction C1.

[0126] The dimensions of the first magnetization portion 32 and the second magnetization portion 33 (dimensions in the axial direction A1 and rotational direction C1) are not limited.

[0127] The length of the rotor 3 in the axial direction A1 may be longer, shorter, or equal to the length of the stator 2 in the axial direction A1.

[0128] The side view shapes of the first magnetized portion 32 and the second magnetized portion 33 are not limited to rectangles or rhombuses. For example, the side view shapes of the first magnetized portion 32 and the second magnetized portion 33 may be circular, elliptical, or rectangles with rounded corners.

[0129] In the rotational direction C1, the length of the first magnetized portion 32 may be longer or shorter than the length of the second magnetized portion 33. Also, in the axial direction A1, the length of the first magnetized portion 32 may be shorter than the length of the second magnetized portion 33 or the same as the length of the second magnetized portion 33.

[0130] Multiple first magnetization units 32 may be arranged at unequal pitches in the axial direction A1 and the rotational direction C1. Similarly, multiple second magnetization units 33 may be arranged at unequal pitches in the axial direction A1 and the rotational direction C1. This reduces the cogging torque in the bearingless motor 1.

[0131] Flux paths may be provided in the gaps where there are no magnets.

[0132] In the first embodiment, magnets may be arranged in a continuous sequence of N, S, N, S... without any gaps in the rotational direction in a portion of the rotor core 31.

[0133] The material of the rotor core 31 is not limited to laminated steel plates; for example, it may be a bulk magnetic material, a compacted magnetic core, a non-ferrous metal, or a resin.

[0134] (Aspects) The following aspects are disclosed in this specification.

[0135] The magnetic bearing (5) according to the first embodiment comprises a rotor (3) and a stator (2). The rotor (3) has a rotor core (31) that rotates about an axis (R1) extending in the axial direction (A1), and one or more first magnetized parts (32) that become one of the N poles and one or more S poles and one or more second magnetized parts (33) that become the other, provided on the rotor core (31). The stator (2) is opposed to the rotor (3) at a predetermined distance in the radial direction. The stator (2) has a first stator core (22), a second stator core (23), a first winding (radial winding 26), and a second winding (thrust winding 27). The magnetic bearing (5) includes a magnet or coil for magnetizing one or more first magnetized parts (32), and a magnet or coil for magnetizing one or more second magnetized parts (33).

[0136] The first stator core (22) has a plurality of first teeth (222) arranged in line in the rotation direction (C1) of the rotor (3), and a first yoke (221) for magnetically connecting at least two of the plurality of first teeth (222). The second stator core (23) has a plurality of second teeth (232) arranged in line in the rotation direction (C1), and a second yoke (231) for magnetically connecting at least two of the plurality of second teeth (232).

[0137] The first winding (radial winding 26) is wound around at least one of the plurality of first teeth (222) and the plurality of second teeth (232) to form a radial coil (36) for controlling the radial position of the rotor (3). The second winding (thrust winding 27) is wound around a thrust coil (37) for controlling the axial position of the rotor (3). At least a portion of the first winding (radial winding 26) and at least a portion of the second winding (thrust winding 27) are in the same position in the axial direction (A1).

[0138] Assume a first axial imaginary line (P1) and a second axial imaginary line (P2) extending along the axial direction (A1) at different positions in the rotation direction (C1). Assume a first rotational imaginary line (Q1) extending along the rotation direction (C1) at positions where one or more first magnetization parts are arranged, and a second rotational imaginary line (Q2) extending along the rotation direction (C1) at positions where one or more second magnetization parts are arranged.

[0139] The single or multiple first magnetized parts (32) and the single or multiple second magnetized parts (33) are provided such that the length occupied by one or more first magnetized parts (32) in the first axial direction virtual line (P1) is longer than the length occupied by one or more second magnetized parts (33), and the length occupied by one or more second magnetized parts (33) in the second axial direction virtual line (P2) is longer than the length occupied by one or more first magnetized parts (32).

[0140] The single or multiple first magnetized parts (32) and the single or multiple second magnetized parts (33) are provided such that the length occupied by one or more first magnetized parts (32) in the first virtual line in the direction of rotation (Q1) is longer than the length occupied by one or more second magnetized parts (33), and the length occupied by one or more second magnetized parts (33) in the second virtual line in the direction of rotation (Q2) is longer than the length occupied by one or more first magnetized parts (32).

[0141] A predetermined position in the axial direction (A1) of a plurality of first teeth (222) is defined as the first tooth position (220), and a predetermined position in the axial direction (A1) of a plurality of second teeth (232) is defined as the second tooth position (230). The first tooth position (220) and the second tooth position (230) are at different positions in the axial direction (A1). A single first virtual winding is assumed to be wound around each of the plurality of first teeth (222), and a single second virtual winding is assumed to be wound around each of the plurality of second teeth (232). The first magnetic flux is defined as the fundamental wave component of the magnetic flux extending from at least one of one of one of one of one of the first magnetization parts (32) and one or more of the second magnetization parts (33) that are linked with the first virtual winding. When the rotor (3) moves in the axial direction (A1), the position of the portion of the first magnetized portion (32) that is at the same position as the first tooth position (220) in the axial direction (A1) when the first magnetic flux takes on a maximum or minimum value is defined as the first magnetized portion position (320). The second magnetic flux is defined as the fundamental wave component of the magnetic flux extending from at least one of the one or more first magnetized portions (32) and one or more second magnetized portions (33) that are linked with the second virtual winding. When the rotor (3) moves in the axial direction (A1), the position of the portion of the second magnetized portion (33) that is at the same position as the second tooth position (230) in the axial direction (A1) when the second magnetic flux takes on a maximum or minimum value is defined as the second magnetized portion position (330).

[0142] With the rotor (3) in the axial direction (A1) position being controlled, when the first magnetized part position (320) is at the same position as the first tooth position (220) in the axial direction (A1), the second magnetized part position (330) is not at the same position as the second tooth position (230).

[0143] According to this embodiment, either the axial component (A1) of the magnetic force acting between the first magnetization section (32) and the stator (2) (either the first stator core (22) and the second stator core (23) or both) and the axial component (A1) of the magnetic force acting between the second magnetization section (33) and the stator (2) (either the first stator core (22) and the second stator core (23) or both) are always present, making it easy to control the position of the rotor (3) in the axial direction (A1). As a result, despite its small size and relatively simple configuration, it becomes possible to actively control the rotor (3) in five axes: radial, axial (A1), and tilt.

[0144] A second embodiment can be realized by combining it with the first embodiment. In the second embodiment, the second winding (thrust winding 27) has a plurality of winding portions divided in the rotational direction (C1). Each of the plurality of winding portions independently generates a force that supports the rotor (3) in the axial direction (A1), thereby controlling the tilt of the rotor (3).

[0145] According to this embodiment, when current is applied to the thrust coil (37), the rotor (3, 3A, 3B, 3C, 3D, 3E) is positioned in the axial direction (A1) by the magnetic field generated from the thrust coil (37) and the magnetic fields generated from one or more N poles (33, 33A, 33B, 33C, 33D, 33E) and one or more S poles (32, 32A, 32B, 32C, 32D, 32E). When a thrust current is applied such that magnetic fluxes (M1, M2) of 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 to some of the windings so that magnetic fluxes (M1, M2) with different orientations are generated, the tilt direction (θx, θy) of the rotor (3, 3A, 3B, 3C, 3D, 3E) is controlled.

[0146] A third embodiment can be realized by combining it with the first or second embodiment. In the third embodiment, the first winding (radial winding 26) is wound over a plurality of first teeth (222) and a plurality of second teeth (232).

[0147] According to this embodiment, the coil end can be shortened compared to the case where the winding is divided and wound in the axial direction (A1).

[0148] The fourth embodiment can be realized by combining it with any of the first to third embodiments. In the fourth embodiment, the plurality of coils (12) are formed by winding flat rectangular conductors by edgewise bending, and the relative position of the first magnetized part position (320) with respect to the first tooth position (220) when the rotor (3) moves in the axial direction (A1) is X1. The value of the first magnetic flux, which is a function of X1, is Y1. The value of the derivative obtained by differentiating Y1 with respect to X1 is Y1'. The smaller of the absolute values ​​of the maximum and minimum values ​​of Y1' is Y1'abs. When the position of the rotor (3) in the axial direction (A1) is controlled with respect to the stator (2), the minimum value of Y1' in X1 within the range of the stroke in the axial direction (A1) is 50% or more of Y1'abs.

[0149] Let X2 be the relative position of the second magnetization section (330) with respect to the second tooth position (230) when the rotor (3) moves in the axial direction (A1). Let Y2 be the value of the second magnetic flux, which is a function of X2. Let Y2' be the value of the derivative obtained by differentiating Y2 with respect to X2. Let Y2'abs be the smaller of the two absolute values ​​of the maximum and minimum values ​​of Y2'. When the position of the rotor (3) in the axial direction (A1) is controlled with respect to the stator (2), the minimum value of Y2' in X2 within the range of the stroke in the axial direction (A1) is 50% or more of Y2'abs.

[0150] According to this embodiment, the larger the value of the derivative obtained by differentiating Y1 with respect to X1, the greater the thrust force that the rotor (3) receives per unit current of the current applied to the thrust winding (27), thus enabling efficient generation of thrust force.

[0151] The fifth embodiment can be realized by combining it with any of the first to fourth embodiments. In the fifth embodiment, the bearingless motor (1) comprises a magnetic bearing (5) of any of the first to fourth embodiments and a motor coil (35) for rotating the rotor (3).

[0152] According to this embodiment, either the axial component (A1) of the magnetic force acting between the first magnetization section (32) and the stator (2) (either the first stator core (22) and the second stator core (23) or both) and the axial component (A1) of the magnetic force acting between the second magnetization section (33) and the stator (2) (either the first stator core (22) and the second stator core (23) or both) are always present, making it easy to control the position of the rotor (3) in the axial direction (A1). As a result, despite its small size and relatively simple configuration, it becomes possible to actively control the rotor (3) in five axes: radial, axial (A1), and tilt.

[0153] 1 Bearingless motor 2 Stator 3 Rotor 5 Magnetic bearing 10 Bearingless motor body 21 Frame 22 First stator core 23 Second stator core 26 First winding 27 Second winding 31 Rotor core 32 Magnetized section 33 Magnetized section 35 Motor coil 36 Radial coil 37 Thrust coil 38 First spacing 39 Second spacing 50 Magnetic bearing body 51 Control unit 53 Magnetic generation unit 220 First tooth position 221 First yoke 222 First tooth 230 Second tooth position 231 Second yoke 232 Second tooth 301 Magnet 302 Magnet 303 Ring magnet 320 First magnetized section position 321 Second magnetized section position 521 Position sensor 522 Angle sensor A1 Axial direction C1 Rotation direction F1 Stratos force F2 Stratos force M1 Magnetic flux M2 Magnetic flux P1 Imaginary line in the direction of the first axis P2 Imaginary line in the direction of the second axis Q1 Imaginary line in the direction of the first rotation Q2 Imaginary line in the direction of the second rotation R1 Axis

Claims

1. A rotor having a rotor core that rotates about an axis extending in the axial direction, and one or more first magnetized parts that are one of the N poles and one or more S poles and one or more second magnetized parts that are the other, provided on the rotor core; a stator facing the rotor at a predetermined distance apart in the radial direction; magnets or coils for magnetizing the one or more first magnetized parts; magnets or coils for magnetizing the one or more second magnetized parts, wherein the stator has a first stator core having a plurality of first teeth arranged in line in the rotational direction of the rotor, and a first yoke for magnetically connecting at least two of the plurality of first teeth; a second stator core having a plurality of second teeth arranged in line in the rotational direction, and a second yoke for magnetically connecting at least two of the plurality of second teeth, The rotor comprises: a first winding which constitutes a radial coil for controlling the radial position of the rotor by being wound around at least one of the plurality of first teeth and the plurality of second teeth; and a second winding which constitutes a thrust coil for controlling the axial position of the rotor, wherein at least a portion of the first winding and at least a portion of the second winding are in the same position in the axial direction, and assuming a first axial imaginary line and a second axial imaginary line extending along the axial direction at different positions in the rotation direction, and assuming a first rotational imaginary line extending along the rotation direction at the position where the one or more first magnetization parts are arranged, The length occupied by the one or more first magnetized portions in the first axial direction virtual line is longer than the length occupied by the one or more second magnetized portions, the length occupied by the one or more second magnetized portions in the second axial direction virtual line is longer than the length occupied by the one or more first magnetized portions, the length occupied by the one or more first magnetized portions in the first rotation direction virtual line is longer than the length occupied by the one or more second magnetized portions, and the length occupied by the one or more second magnetized portions in the second rotation direction virtual line is longer than the length occupied by the one or more first magnetized portions,The rotor is provided with one or more first magnetization parts and one or more second magnetization parts, and when a predetermined position of the plurality of first teeth in the axial direction is defined as the first tooth position and a predetermined position of the plurality of second teeth in the axial direction is defined as the second tooth position, the first tooth position and the second tooth position are at different positions in the axial direction, and assuming that there is one first virtual winding wound around each of the plurality of first teeth and one second virtual winding wound around each of the plurality of second teeth, when the rotor moves in the axial direction, the fundamental wave component of the magnetic flux extending from at least one of the one or more first magnetization parts and the one or more second magnetization parts that links with the first virtual winding is defined as the first magnetic flux, and the position of the portion of the first magnetization part that is at the same position as the first tooth position in the axial direction when the first magnetic flux takes a maximum or minimum value is defined as the first magnetization part position. A magnetic bearing wherein, when the rotor's axial position is controlled, the fundamental wave component of the magnetic flux extending from at least one of the one or more first magnetization parts and the one or more second magnetization parts that are linked with the second virtual winding is defined as the second magnetic flux, and the position of the portion of the second magnetization part that is at the same position as the second teeth position in the axial direction when the second magnetic flux takes a maximum or minimum value is defined as the second magnetization part position, wherein when the rotor's axial position is controlled, and the first magnetization part position is at the same position as the first teeth position in the axial direction, the second magnetization part position is not at the same position as the second teeth position.

2. The magnetic bearing according to claim 1, wherein the second winding has 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 tilt of the rotor.

3. The magnetic bearing according to claim 1, wherein the first winding is wound across the plurality of first teeth and the plurality of second teeth.

4. When the rotor moves in the axial direction, let X1 be the relative position of the first magnetized part with respect to the first tooth position, let Y1 be the value of the first magnetic flux which is a function of X1, let Y1' be the value of the derivative obtained by differentiating Y1 with respect to X1, and let Y1'abs be the smaller of the two absolute values ​​of the maximum and minimum values ​​of Y1', when the axial position of the rotor with respect to the stator is controlled, the minimum value of Y1' in X1 within the range of the axial stroke is 50% or more of Y1'abs, when the rotor moves in the axial direction, let X2 be the relative position of the second magnetized part with respect to the second tooth position, let Y2 be the value of the second magnetic flux which is a function of X2, let Y2' be the value of the derivative obtained by differentiating Y2 with respect to X2, and let Y2'abs be the smaller of the two absolute values ​​of the maximum and minimum values ​​of Y2', The magnetic bearing according to claim 1, wherein the minimum value of Y2' in X2 within the range of axial stroke that the rotor can take with respect to the stator is 50% or more of Y2'abs.

5. A bearingless motor comprising a magnetic bearing according to any one of claims 1 to 4, and a motor coil for rotating the rotor.

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