JP5478136B2 - Permanent magnet synchronous motor - Google Patents

Description

  The present invention relates to a permanent magnet type synchronous motor that suppresses cogging torque.

  In a permanent magnet synchronous motor, cogging torque is generated between the stator core (stator core) and the rotor (rotor) when the rotor magnet (rotor) is rotated by external drive when no winding is energized. Torque pulsation component. The torque ripple is a torque pulsation generated between the stator core and the rotor (rotor) when the winding is energized and driven.

  In general, the cogging torque generates a pulsation number of the least common multiple of the number of slots of the stator and the number of magnetic poles of the permanent magnet per mechanical rotation of the rotor. The magnitude of this cogging torque is inversely proportional to the number of pulsations.

  In a so-called slotless motor in which an air-core coil is provided on the stator and a permanent magnet is provided on the rotor, there is no tooth portion of the stator. For this reason, no cogging torque is theoretically generated. However, in order to fix the air-core coil, some kind of protrusion is required. On the other hand, by providing a protrusion as a tooth at the center of the coil, the characteristics of the motor are improved.

  However, if a protrusion serving as a tooth is provided, a cogging torque is generated. Thus, a technique has been proposed in which a cogging torque is reduced by providing a tooth projection at the center of the coil and devising the shape of the projection (for example, see Patent Document 1).

JP 2004-187344 A

However, the prior art has the following problems.
In a motor with a small diameter, a slotless structure in which teeth are not provided on the stator may be used.

  In such a small-diameter motor, the rotor diameter is also small, and it is difficult to attach a segment magnet (single pole magnet). For this reason, a radial anisotropic ring magnet or a polar anisotropic ring magnet may be used as a magnet.

  These ring magnets have a plurality of pole numbers in one magnet. For this reason, the magnet variation of each pole becomes large under the influence of creating a magnetized yoke shape or ring magnet. As a result, when the rotor makes one mechanical rotation, cogging torque having the same number of pulsations as the number of slots is generated.

  The cogging torque generated by this magnet variation has a different frequency from the cogging torque generated by the least common multiple of the number of poles and the number of protrusions. For this reason, it is difficult to reduce the cogging torque generated by the magnet variation only by devising the shape of the protrusion.

  In addition, since the slotless motor uses an air-core coil, the bulge of the coil end portion becomes large, and a useless space increases.

  The present invention has been made to solve the above-described problems, and in a slotless motor provided with a stator protrusion, a permanent magnet capable of making the cogging torque caused by magnet variation as close to zero as possible. An object is to obtain a synchronous motor.

A permanent magnet type synchronous motor according to the present invention is caused by variations in a permanent magnet in a permanent magnet type synchronous motor having a stator protrusion, an annularly formed winding attached to the stator protrusion, and a permanent magnet. the cogging torque, by providing the projections for cogging torque reduction to the coil end portion of the winding between the stator projection, vanishing and out creating a negative phase component of the cogging torque, a cogging torque reduction projection, the width in the radial direction It is the same as the stator protrusion and has the same axial length as the stator protrusion .

  According to the permanent magnet type synchronous motor according to the present invention, the same number of protrusions as the stator protrusions are provided at the coil end portion, and the useless space is effectively utilized. A permanent magnet type synchronous motor that can make the cogging torque as close to zero as possible can be obtained.

It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of the permanent-magnet-type synchronous motor in Embodiment 1 of this invention. It is an enlarged view of the protrusion part of the permanent magnet type synchronous motor in Embodiment 1 of this invention. 1 is a perspective view of a permanent magnet type synchronous motor in Embodiment 1 of the present invention. 1 is a perspective view of a permanent magnet type synchronous motor in Embodiment 1 of the present invention. 1 is a perspective view of a permanent magnet type synchronous motor in Embodiment 1 of the present invention. 1 is a perspective view of a permanent magnet type synchronous motor in Embodiment 1 of the present invention. It is a plane development view of the permanent magnet type synchronous motor in Embodiment 1 of the present invention. It is the figure which showed the cogging torque waveform of only the stator protrusion 1a with respect to the rotation angle of the permanent magnet type synchronous motor in Embodiment 1 of this invention, and the cogging torque waveform of only the protrusion 1b. It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of the permanent-magnet-type synchronous motor in Embodiment 2 of this invention. It is a perspective view of the permanent magnet type synchronous motor in Embodiment 2 of this invention. It is a plane expanded view of the permanent magnet type synchronous motor in Embodiment 2 of this invention. It is the figure which showed the cogging torque waveform of only the stator protrusion 1a with respect to the rotation angle of the permanent magnet type synchronous motor in Embodiment 2 of this invention, and the cogging torque waveform of only the protrusion 1b. It is sectional drawing which shows a cross section perpendicular | vertical to the axial direction of the permanent-magnet-type synchronous motor in Embodiment 3 of this invention. It is a perspective view of the permanent magnet type synchronous motor in Embodiment 3 of this invention. It is a plane expanded view of the permanent magnet type synchronous motor in Embodiment 3 of this invention. It is the figure which showed the cogging torque waveform of only the protrusion part with respect to the rotation angle of the permanent-magnet-type synchronous motor in Embodiment 3 of this invention, and the cogging torque waveform of only the cutting part. It is an orientation diagram of a radial ring magnet. It is an orientation figure of the polar anisotropic ring magnet of the permanent magnet type synchronous motor in Embodiment 4 of this invention.

Hereinafter, a preferred embodiment of a permanent magnet type synchronous motor of the present invention will be described with reference to the drawings.
The present invention relates to a motor driven by a so-called three-phase power source, and relates to a motor having a stator projection and a permanent magnet formed in an annular shape and provided with a winding (coil). A stator projection (main pole) is provided at the central portion of the coil of such a motor, and projections having the same size in the circumferential direction and the axial direction are provided between the projections between the coil centers. By providing such a configuration, cogging torque generated due to magnet-related variations such as magnet pole pitch variation, magnet residual magnetic flux density Br variation, or orientation variation is canceled by creating a reverse phase component thereof, and cogging torque It is a technical feature that it can be reduced. In other words, a technical feature is that a protrusion-shaped cogging torque reduction unit is provided.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a cross section perpendicular to the axial direction of the permanent magnet type synchronous motor according to Embodiment 1 of the present invention. As an example, the permanent magnet type synchronous motor is composed of 8 poles and 6 slots. FIG. 2 is an enlarged view of the protrusion portion of the permanent magnet type synchronous motor according to the first embodiment of the present invention, and shows the size of the protrusions 1a and 1b in FIG. The protrusion 1a corresponds to a stator protrusion, and the protrusion 1b corresponds to a protrusion provided to reduce cogging torque.

  3 to 6 are perspective views of the permanent magnet type synchronous motor according to Embodiment 1 of the present invention, and are perspective views in the axial direction on the AA ′ plane of FIG. 1. FIG. 3 shows the arrangement of the protrusions 1a and 1b. FIG. 4 shows the axial lengths of the protrusions 1a and 1b. FIG. 5 shows a state where the coil 10 is attached to the protrusion 1a of FIG. Further, FIG. 6 shows a state after the coil 10 is attached to the protrusion 1a.

  FIG. 7 is a plan development view of the permanent magnet type synchronous motor according to the first embodiment of the present invention, and is a plan development view showing a state after the coil 10 is attached to the protrusion 1a shown in FIG. . 1 illustrates a motor having 8 poles, the combination of the poles and the number of slots is not limited to this.

  FIG. 8 is a diagram showing a cogging torque waveform of only the stator protrusion 1a and a cogging torque waveform of only the protrusion 1b with respect to the rotation angle of the permanent magnet type synchronous motor according to Embodiment 1 of the present invention.

  The permanent magnet type synchronous motor according to the first embodiment has W1 = W2 and d1 = d2 in FIG. 2, and the cross-sectional shapes of the protrusion 1a and the protrusion 1b are the same. Further, the length of the magnet in FIG. 4 in the axial direction is L as shown in FIGS. 7A to 7C, and the length of the protrusion is L1 = (L2 + L3). . However, L> (L1 + L2 + L3) in FIG. 7A, L = (L1 + L2 + L3) in FIG. 7B, and L <(L1 + L2 + L3) in FIG. 7C. Thus, there is no problem if either L2 = L3 or L2 ≠ L3.

  Next, in the magnet 20 formed in a ring shape as shown in FIG. When only the protrusion 1a (stator protrusion) shown in FIG. 3 is present, torque pulsation equal to the number of slots, that is, cogging torque is generated while the rotor makes one mechanical rotation. On the other hand, the case where the air-core coil 10 as shown in FIG. 5 is formed is considered. In this case, the corner portion of the air-core coil 10 is ideally a square shape, and can receive more magnetic flux from the magnet 20 by making the overall shape a rectangular shape.

  However, in the actual machine, the coil end portion is rounded and has an elliptical shape. Therefore, in the first embodiment, the protrusion 1b having the same size as the protrusion 1a is formed between the ends of the adjacent coils 10, that is, in the space between the coil ends, as shown in FIG. It is provided at the coil end. As a result, as shown in FIG. 8, the projection 1b generates a cogging torque out of phase with the projection 1a.

  The cogging torque generated by the protrusion 1a and the cogging torque generated by the protrusion 1b are shifted from each other by a half cycle (see FIG. 8). For this reason, it is possible to reduce the cogging torque generated by the magnet variation.

  As described above, according to the first embodiment, in the slotless motor, a protrusion having the same size is provided at the axial end, that is, at the center between the protrusions adjacent in the radial direction to the coil end. Is provided to effectively use the useless space. As a result, a component having a phase opposite to that of the cogging torque generated due to the variation in the pole pitch width can be created, and the cogging torque can be reduced.

Embodiment 2. FIG.
In the first embodiment, the case where the shapes of the stator protrusion 1a and the protrusion 1b are the same has been described. On the other hand, in the second embodiment, the case where the shape of the protrusion 1b is different from the shape of the stator protrusion 1a will be described.

  FIG. 9 is a cross-sectional view showing a cross section perpendicular to the axial direction of the permanent magnet type synchronous motor according to Embodiment 2 of the present invention. As an example, FIG. 9 shows an 8-pole 6-slot structure. 10 is a perspective view of a permanent magnet type synchronous motor according to Embodiment 2 of the present invention, and is an axial perspective view of the AA ′ plane of FIG. FIG. 11 is a plan development view of the permanent magnet type synchronous motor according to the second embodiment of the present invention, and shows a plan development view when the coil 10 is applied to the cores of FIGS.

  As shown in FIGS. 10 and 11, the protrusion 1 b has a shape different from that of the protrusion 1 a, and the protrusion shape is designed so as not to contact the coil 10 in a space between adjacent coil end portions. By providing the projection 1b having such a shape, it is possible to reduce the cogging torque due to the magnet variation, as in the first embodiment.

  FIG. 12 is a diagram showing a cogging torque waveform of only the stator protrusion 1a and a cogging torque waveform of only the protrusion 1b with respect to the rotation angle of the permanent magnet synchronous motor according to the second embodiment of the present invention. It is a cogging torque waveform when it makes one rotation mechanically. Since the protrusion 1b has a different shape from the protrusion 1a, the cogging torque waveform has a different shape. Therefore, by setting the shape of the protrusion 1b to an optimum shape by using a simulation such as magnetic field analysis, a cogging torque having a phase shift in the protrusions 1a and 1b can be generated, and the cogging torque can be reduced. Is possible.

  As described above, according to the second embodiment, even if the protrusion 1a and the protrusion 1b have different shapes, the shape of the protrusion 1b is optimized by using a simulation such as magnetic field analysis. The effect similar to the form 1 of this can be acquired. As a result, even in a motor with a short axial length of the coil end, the length in the axial direction can be shortened by making the protrusion provided on the coil end portion a shape that matches the coil shape, Furthermore, the cogging torque generated due to magnet variation can be reduced.

Embodiment 3 FIG.
In the third embodiment, a configuration in which the protrusion 1b is provided and further provided with a shaving portion for reducing the cogging torque generated by the number of poles and the number of protrusions will be described.

  FIG. 13 is a cross-sectional view showing a cross section perpendicular to the axial direction of the permanent magnet type synchronous motor according to the third embodiment of the present invention. As an example, the permanent magnet type synchronous motor is composed of 8 poles and 6 slots. FIG. 14 is a perspective view of the permanent magnet type synchronous motor according to Embodiment 3 of the present invention, and is an axial perspective view of the AA ′ plane of FIG. FIG. 15 is a plan development view of the permanent magnet type synchronous motor according to Embodiment 3 of the present invention.

  As shown in FIGS. 13 to 15, by providing the protrusion 1a, a cogging torque that is the least common multiple of the number of poles and the number of protrusions is generated while the rotor is mechanically rotated once. Here, since there are 6 protrusions 1a with 8 poles, 24 peaks of cogging torque are generated. In addition, when there is a variation in the magnet 20, as described in the first and second embodiments, a cogging torque due to the variation in the magnet is generated. The cogging torque due to such magnet variation can be reduced by providing the projection 1b at the coil end portion as described in the first and second embodiments.

  Furthermore, in the third embodiment, the cutting portion 2a is provided between the protrusions 1a, and the cutting portion 2b is provided between the protrusions 1b, so that the number of poles and the cogging torque generated by the number of protrusions are opposite to each other. Can be produced. FIG. 16 is a diagram showing a cogging torque waveform of only the protruding portion and a cogging torque waveform of only the shaving portion with respect to the rotation angle of the permanent magnet type synchronous motor according to the third embodiment of the present invention. As a result, the cogging torque generated by the number of poles and the number of protrusions can be reduced.

  As described above, according to the third embodiment, the same effect as in the first and second embodiments can be obtained by further providing the shaving portion 2a and the shaving portion 2b corresponding to each of the projection 1a and the projection 1b. In addition, the cogging torque generated by the number of poles and the number of protrusions can be reduced. That is, by providing such a shaved portion, a further effect of reducing the cogging torque generated by the protrusion can be obtained.

Embodiment 4 FIG.
In the fourth embodiment, a case where the cogging torque reduction measures described in the first to third embodiments are applied to a permanent magnet type synchronous motor including a polar anisotropic ring magnet will be described.

  FIG. 17 is an orientation diagram of the radial ring magnet 21. In contrast, FIG. 18 is an orientation diagram of polar anisotropic ring magnet 22 of the permanent magnet type synchronous motor according to Embodiment 4 of the present invention. The polar anisotropic ring magnet 22 theoretically has no magnetic flux passing through the rotor core back portion. For this reason, it is used for a motor or the like in which the rotor core 30 has a small diameter and the rotor core back portion cannot be made large.

  Further, unlike the radial ring magnet 21, the polar anisotropic ring magnet 22 determines the magnetizable direction from the molding orientation. For this reason, the deviation of the pole pitch of each pole is likely to be larger than that of the radial ring magnet 21. As a result, in a motor having a small diameter, when the polar anisotropic ring magnet 22 is used and the protrusion 1a for attaching the stator core is provided, a large cogging torque is generated due to variations in the magnet. Therefore, as described in the first to third embodiments, a countermeasure against cogging torque due to magnet variation is effective.

  As described above, according to the fourth embodiment, when a polar anisotropic ring magnet is used, it is possible to take measures against cogging torque by applying the configuration of the first to third embodiments. . That is, the polar anisotropic ring magnet has a larger magnet variation than the radial ring magnet. However, a polar anisotropic ring magnet is often used particularly in a motor having a small diameter due to the influence of the rotor core back. Therefore, the configurations of the first to third embodiments are effective as a countermeasure against cogging torque when a polar anisotropic ring magnet is used with a motor having a small diameter.

  In a motor having a small diameter, if a large number of slots (coils) are provided, the size of the coil to be manufactured also becomes small. In addition, it is difficult to manufacture a small-size coil on the stator. For this reason, it is conceivable to select a combination of pole slots with a small number of slots. When taking measures against cogging torque in the first to fourth embodiments, by selecting a combination of 2 poles 3 slots, 4 poles 3 slots, 4 poles 6 slots, and 8 poles 6 slots, the number of slots can be reduced and the diameter can be reduced. Even small motors can be manufactured.

  Quantitatively, when Z stator protrusions (Z is a natural number) and 2P poles (P is a natural number) permanent magnets, Z / (3 (phase) × 2P) is 0.5 or 0.25. This combination of pole slots is effective for a motor having a small diameter.

  In other words, a motor having a small diameter is required to produce a coil with high accuracy, and accuracy to apply the coil is also required. For this reason, when the number of slots (that is, the number of coils) is increased, it is difficult to produce a coil, and the work of applying the coil becomes difficult. Therefore, by defining the combination of Z and P so as to have the relationship as described above, and selecting a combination with a small number of slots, the manufacture becomes easy.

  1a protrusion (stator protrusion), 1b protrusion, 2a, 2b shaving part, 10 coil (winding), 20 magnet, 21 radial ring magnet, 22 polar anisotropic ring magnet, 30 rotor core.

Claims (5)

A stator projection,
A winding formed in an annular shape and attached to the stator protrusion;
In a permanent magnet type synchronous motor having a permanent magnet,
The cogging torque generated by the variations regarding the permanent magnet, by providing the projections for cogging torque reduction to the coil end portion of the winding between the stator projection, vanishing and out creating a negative phase component of the cogging torque,
The cogging torque reducing protrusion has a radial width that is the same as that of the stator protrusion, and an axial length that is the same shape as the stator protrusion . A stator projection,
A winding formed in an annular shape and attached to the stator protrusion;
In a permanent magnet type synchronous motor having a permanent magnet,
The cogging torque generated by the variations regarding the permanent magnet, by providing the projections for cogging torque reduction to the coil end portion of the winding between the stator projection, vanishing and out creating a negative phase component of the cogging torque,
A permanent magnet type synchronous motor further comprising a shaving portion between each of the stator protrusions and between the cogging torque reducing protrusions in the circumferential direction . In the permanent magnet type synchronous motor according to claim 1 or 2 ,
The cogging torque reduction protrusion has a shape that matches the coil shape of the coil end portion of the winding. In the permanent magnet type synchronous motor according to claim 1 or 2 ,
The permanent magnet is a polar anisotropic ring magnet. A permanent magnet type synchronous motor, wherein: In the permanent magnet type synchronous motor according to claim 1 or 2 ,
When the number of stator protrusions is Z (Z is a natural number) and the number of poles of the permanent magnet is 2P poles (P is a natural number), Z / (3 (phase) × 2P) is 0.5 or 0.25. A permanent-magnet synchronous motor characterized by having a relationship of

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