KR20120027494A - Permanent-magnet type synchronous motor - Google Patents

Abstract

In the slotless motor provided with the stator protrusion, a permanent magnet synchronous motor capable of making the cogging torque caused by magnet deviation infinitely close to zero is obtained. In a permanent magnet synchronous motor having a stator protrusion 1a and an annular shape and having a coil 10 and a permanent magnet in the stator protrusion, provided to reduce cogging torque at the coil end portion of the winding between the stator protrusions. It has the protrusion 1b further. By providing the stator protrusion 1a and the same number of protrusions 1b at the coil end portion, the influence of the magnet deviation and the cogging torque generated by the stator protrusion can produce a component that is out of phase and cancel the cogging torque. .

Description

Permanent magnet synchronous motor {PERMANENT-MAGNET TYPE SYNCHRONOUS MOTOR}

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

In a permanent magnet synchronous motor, cogging torque is a torque pulsation component generated between the stator core (stator core) and the rotor (rotor) when the rotor magnet (rotor) is rotated by external driving during winding energization. . The torque ripple is a torque pulsation generated between the stator core and the rotor (rotor) similarly when energized and driven through a winding.

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 poles of the permanent magnet for one mechanical rotation of the rotor. In addition, the magnitude of this cogging torque is inversely proportional to the number of pulsations.

In a so-called slotless motor having an air core coil installed in the stator and a permanent magnet in the rotor, there are no teeth portions of the stator. For this reason, cogging torque does not arise in theory. However, in order to fix the air core coil, a protrusion of something is required. On the other hand, the characteristic of a motor improves by providing the protrusion which becomes a tooth in the center of a coil.

However, cogging torque will generate | occur | produce when providing the process which becomes a tooth. Then, the technique which reduces cogging torque is proposed by providing the process which becomes a tooth in the part used as the center of a coil, and devising the processus | protrusion shape etc. (for example, refer patent document 1).

Japanese Patent Laid-Open No. 2004-187344

However, the prior art has the following problems.

In a motor with a small diameter, a slotless structure in which no teeth are provided in the stator may be used.

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

These ring magnets have a plurality of poles in one magnet. For this reason, the magnet deviation of each pole becomes large by being influenced when creating a magnetized yoke shape or a ring magnet. As a result, when the rotor is mechanically rotated once, cogging torque equal to the number of slots is generated.

The cogging torque generated by this magnet deviation is different in frequency from the cogging torque generated by the number of least common multiples 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 deviation only by devising the shape of the projection.

In addition, in the slotless motor, since the air core coil is used, the bulging portion of the coil end portion is increased, thereby increasing the unnecessary space.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to obtain a permanent magnet synchronous motor capable of making the cogging torque caused by magnet deviation infinitely close to zero in a slotless motor provided with stator protrusions. It is done.

The permanent magnet synchronous motor according to the present invention has a stator protrusion, a ring formed in an annular shape, a winding mounted on the stator protrusion, and a permanent magnet synchronous motor having a permanent magnet. To have.

According to the permanent magnet synchronous motor according to the present invention, in the slotless motor provided with the stator projections by providing the same number of projections as the stator projections in the winding end portion and effectively utilizing unnecessary space, the cogging torque generated by the magnet deviation. It is possible to obtain a permanent magnet synchronous motor that can be set to near zero.

1 is a cross-sectional view showing a cross section perpendicular to the axial direction of a permanent magnet synchronous motor according to Embodiment 1 of the present invention;
2 is an enlarged view of a projection of the permanent magnet synchronous motor according to the first embodiment of the present invention;
3 is a perspective view of a permanent magnet synchronous motor according to Embodiment 1 of the present invention;
4 is a perspective view of a permanent magnet synchronous motor according to Embodiment 1 of the present invention;
5 is a perspective view of a permanent magnet synchronous motor according to Embodiment 1 of the present invention;
6 is a perspective view of a permanent magnet synchronous motor according to Embodiment 1 of the present invention;
7 is a planar development view of a permanent magnet synchronous motor according to Embodiment 1 of the present invention;
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 rotational angle of the permanent magnet synchronous motor according to the first embodiment of the present invention.
9 is a cross-sectional view showing a cross section perpendicular to the axial direction of the permanent magnet synchronous motor according to the second embodiment of the present invention;
10 is a perspective view of a permanent magnet synchronous motor according to the second embodiment of the present invention;
11 is a planar development view of a permanent magnet synchronous motor according to Embodiment 2 of the present invention;
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 rotational angle of the permanent magnet synchronous motor according to the second embodiment of the present invention.
13 is a cross-sectional view showing a cross section perpendicular to the axial direction of the permanent magnet synchronous motor according to the third embodiment of the present invention;
14 is a perspective view of a permanent magnet synchronous motor according to Embodiment 3 of the present invention;
FIG. 15 is a planar development view of a permanent magnet synchronous motor according to Embodiment 3 of the present invention; FIG.
Fig. 16 is a diagram showing a cogging torque waveform of only the protruding portion and the cogging torque waveform of the cutting portion only with respect to the rotational angle of the permanent magnet synchronous motor according to the third embodiment of the present invention.
17 is an orientation diagram of a radial ring magnet;
18 is an orientation diagram of a polar anisotropic ring magnet of a permanent magnet synchronous motor according to Embodiment 4 of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of the permanent magnet synchronous motor of this invention is described using drawing.

The present invention also relates to a motor driven by a so-called three-phase power source, which has a stator protrusion and a permanent magnet formed in an annular shape and provided with a winding (coil). Then, a stator protrusion (main electrode) is provided in the center portion of the coil of such a motor, and a protrusion having the same size in the circumferential direction and the axial direction is provided between the protrusion between the coil center and the protrusion. By providing such a structure, the cogging torque which arises by the deviation about the magnet, such as the deviation of the pole pitch of a magnet, the deviation of the residual magnetic flux density (Br) of a magnet, or an orientation deviation, is erased by producing the reverse phase component, and cogging It is a technical feature that it becomes possible to reduce torque. In other words, the technical feature is that the projection-shaped cogging torque reduction unit is provided.

Embodiment 1

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the axial direction perpendicular | vertical cross section of the permanent magnet synchronous motor in Embodiment 1 of this invention. As an example, it is what consists of 8-pole 6 slots. FIG. 2 is an enlarged view of the projections of the permanent magnet synchronous motor in Embodiment 1 of the present invention, showing the sizes of the projections 1a and 1b in FIG. The projection 1a corresponds to the stator projection, and the projection 1b corresponds to the projection provided for reducing the cogging torque.

3 to 6 are perspective views of the permanent magnet synchronous motor according to the first embodiment of the present invention, and are perspective views in the axial direction on the plane AA ′ of FIG. 1. 3 shows the arrangement of the projections 1a and 1b. 4 shows the length in the axial direction of the projections 1a and 1b. 5 illustrates a state in which the coil 10 is attached to the protrusion 1a of FIG. 3. 6 shows the state after attaching the coil 10 to this protrusion 1a.

7 is a planar development view of the permanent magnet synchronous motor in Embodiment 1 of this invention, and is a planar development view which is a state after attaching the coil 10 to the projection 1a shown in FIG. In addition, although the motor of 8 poles is illustrated in FIG. 1, the combination of a pole number and a slot number 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 rotational angle of the permanent magnet synchronous motor in Embodiment 1 of the present invention.

In addition, in FIG. 2, the permanent magnet type synchronous motor in Embodiment 1 is set to W1 = W2 and d1 = d2, and the cross-sectional shapes of the projections 1a and the projections 1b are the same. In addition, as shown in FIGS. 7A to 7C, the length in the axial direction of the magnet in FIG. 4 is L, and the length of the projection is L1 = (L2 + L3). However, in FIG. 7A, L> (L1 + L2 + L3), in FIG. 7B, L = (L1 + L2 + L3), and in FIG. 7C, L <(L1 + L2 + L3). In this manner, either L2 = L3 or L2? L3 is not a problem.

Next, the case where there is a deviation of the magnet 20 in the magnet 20 formed in the ring shape as shown in FIG. 1 is examined. When only the projection 1a (stator projection) shown in FIG. 3 exists, as many torque pulsations as the number of slots, that is, cogging torque, are generated while the rotor is mechanically rotated once. On the other hand, the case where the air core coil 10 is formed like FIG. 5 is considered. In this case, each portion of the air core coil 10 is ideally rectangular in shape, and the magnetic flux from the magnet 20 can be received more by making the rectangular shape as an overall shape.

However, in a practical machine, the coil end part has a rounded shape and becomes an elliptical shape. Therefore, in the first embodiment, as shown in Fig. 3, the projections 1b having the same size as the projections 1a are formed between the ends of the coils 10 adjacent to each other, that is, in the space of the coil end portion. It is provided in the coil end part of the center of 1a). Thereby, as shown in FIG. 8, the cogging torque which shifted out of phase with the protrusion 1a by the protrusion 1b generate | occur | produces.

The cogging torque generated by the projection 1a and the cogging torque generated by the projection 1b are shifted by half a period from each other (see FIG. 8). For this reason, it becomes possible to reduce the cogging torque which arises by a magnet deviation.

As described above, according to the first embodiment, in the slotless motor, protrusions having the same size are provided at positions that become centers between the protrusions adjacent to each other in the radial direction, that is, the coil end portion in the radial direction, It is configured to effectively utilize the space that is not necessary. This makes it possible to produce a component which is out of phase with the cogging torque generated by the deviation of the extreme pitch width, thereby making it possible to reduce the cogging torque.

Embodiment 2

In the first embodiment, the case where the shapes of the stator protrusions 1a and the protrusions 1b are the same has been described. On the other hand, in Embodiment 2, the case where the shape of the protrusion 1b differs from the shape of the stator protrusion 1a is demonstrated.

Fig. 9 is a sectional view showing a cross section perpendicular to the axial direction of the permanent magnet synchronous motor according to the second embodiment of the present invention. FIG. 10 is a perspective view of a permanent magnet synchronous motor in Embodiment 2 of the present invention, and is a perspective view in the axial direction in the plane AA ′ of FIG. 9.

11 is a planar development view of the permanent magnet synchronous motor in Embodiment 2 of this invention, and shows the planar development view when the coil 10 is installed in the core of FIG. 9 and FIG.

As shown in FIG. 10 and FIG. 11, the protrusion 1b is made into a shape different from the protrusion 1a, and the protrusion shape is designed so that it does not contact the coil 10 in the space between adjacent coil end parts. Doing. By providing the protrusion 1b of such a shape, it becomes possible to reduce cogging torque by a magnet deviation similarly to 1st Embodiment.

Fig. 12 shows the cogging torque waveform of only the stator protrusion 1a and the cogging torque waveform of only the protrusion 1b with respect to the rotational angle of the permanent magnet synchronous motor in the second embodiment of the present invention. This is a cogging torque waveform when mechanically rotated once. Since the projection 1b is different in shape from the projection 1a, the cogging torque waveform is in a different shape. Therefore, by setting the size of the shape of the projection 1b to an optimal shape using simulation such as magnetic field analysis, cogging torque out of phase can be generated in the projections 1a and 1b, and the cogging torque can be reduced. Become.

As described above, according to the second embodiment, even if the protrusions 1a and the protrusions 1b have different shapes, the shape of the protrusions 1b is optimized by using simulations such as magnetic field analysis. The same effect as can be obtained. As a result, even in a motor having a short shape in the axial direction of the coil end, the projections provided in the coil end portion have a shape in accordance with the coil shape, whereby the length in the axial direction can be shortened, resulting from magnet deviation. Cogging torque can be further reduced.

Embodiment 3

In this Embodiment 3, the structure which further provided the projection 1b and further provided the cutting part for reducing the cogging torque which arises by the number of poles and the number of protrusions is demonstrated.

FIG. 13 is a cross-sectional view showing a cross section perpendicular to the axial direction of the permanent magnet synchronous motor according to the third embodiment of the present invention, showing an example consisting of eight poles and six slots. It is a perspective view of the permanent magnet synchronous motor in Embodiment 3 of this invention, and is a perspective view of the axial direction in the AA 'surface of FIG. 15 is a planar development view of a permanent magnet synchronous motor in Embodiment 3 of the present invention.

As shown in FIGS. 13-15, by providing the projection 1a, the cogging torque which becomes the minimum common multiple of a pole number and a protrusion number is generated between the rotor mechanically rotating. Here, since the protrusions 1a are six on the eight poles, a cogging torque of 24 peaks is generated. In addition, when there is a deviation in the magnet 20, as described above in the first and second embodiments, cogging torque due to the magnet deviation is generated. The cogging torque due to such magnet deviation can be reduced by providing the protrusion 1b at the coil end portion as shown in the first embodiment and the second embodiment.

In the third embodiment, the cutting section 2a is provided between the projections 1a, and the cutting section 2b is provided between the projections 1b, thereby generating by the number of poles and the number of projections. It is possible to produce a component that is inverse to the cogging torque. It is a figure which shows the cogging torque waveform of only the protrusion part and the cogging torque waveform of only the cutting part with respect to the rotation angle of the permanent magnet type synchronous motor in Embodiment 3 of this 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 cutting portion 2a and the cutting portion 2b are further provided to correspond to the projections 1a and the projections 1b, respectively, to thereby be the same as the first embodiment and the second embodiment. In addition to the effect, the cogging torque generated by the number of poles and the number of protrusions can be reduced. That is, by providing such a cutting part, a new effect of reducing the cogging torque generated by the projection can be obtained.

Embodiment 4

In the fourth embodiment, a case where the cogging torque reduction measures described in the first to third embodiments described above is applied to a permanent magnet synchronous motor having a polar anisotropic ring magnet will be described.

17 is an orientation view of the radial ring magnet 21. On the other hand, FIG. 18 is an orientation view of the polar anisotropic ring magnet 22 of the permanent magnet synchronous motor in Embodiment 4 of this invention. The anisotropic ring magnet 22 theoretically has no magnetic flux passing through the rotor core bag portion from the orientation thereof. For this reason, the diameter of the rotor core 30 is small and it is used for the motor etc. which do not take large rotor core back part.

In addition, unlike the radial ring magnet 21, the polar anisotropic ring magnet 22 has a direction in which magnetization is possible from the orientation of molding. For this reason, the deviation of the pole pitch of each pole tends to be larger than that of the radial ring magnet 21. As a result, in the motor having a small diameter, when the projection 1a for mounting the stator core is provided using the polar anisotropic ring magnet 22, the cogging torque due to the deviation of the magnet is largely generated. Therefore, as shown in the first to third embodiments, countermeasures against cogging torque due to magnet deviation are effective.

As described above, according to the fourth embodiment, when the polar anisotropic ring magnet is used, the cogging torque countermeasure can be implemented by applying the configuration of the foregoing first to third embodiments. That is, the polar anisotropy ring magnet has a larger magnet deviation than the radial ring magnet. However, especially in motors with small diameters, polar anisotropic ring magnets are often used due to the influence of the rotor core back. For this reason, the structure of Embodiment 1 thru | or Embodiment 3 becomes effective as a countermeasure to cogging torque in the case of using a polar anisotropic ring magnet with a small diameter motor.

In addition, in the motor having a small diameter, when a large number of slots (coils) are provided, the size of the coil to be produced is also reduced. Moreover, it becomes difficult to manufacture a coil of small size in a stator. For this reason, it is conceivable to select a combination of pole slots in which the number of slots becomes small. When the cogging torque countermeasures of the first embodiment to the fourth embodiment are executed, the number of slots can be reduced by selecting a combination of a 2-pole 3-slot, 4-pole 3-slot, 4-pole 6-slot, and 8-pole 6-slot, Production is possible even with a small diameter motor.

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

In other words, in a motor with a small diameter, a precision for producing a coil is required, and a precision for installing the coil is also required. For this reason, when there are many slots (that is, the number of coils), coil manufacture becomes difficult and the work which equips a coil becomes difficult. Therefore, the combination of Z and P is defined so as to have the relationship as described above, and the knitting becomes smaller by selecting the knitting in which the number of slots becomes small, thereby facilitating production.

Claims (6)

In a permanent magnet synchronous motor having a stator protrusion, an annular shape, a winding attached to the stator protrusion, and a permanent magnet,
Characterized in that the projections at the coil end of the winding between the stator projections
Permanent magnet synchronous motor. The method of claim 1,
The projection has a width in the radial direction that is the same as the stator projection, and an axial length has the same shape as the stator projection.
Permanent magnet synchronous motor. The method of claim 1,
The projection has a shape that matches the shape of the coil in the coil end portion of the winding.
Permanent magnet synchronous motor. The method according to any one of claims 1 to 3,
A cutting portion is further provided between each of the stator protrusions and the protrusions in the circumferential direction.
Permanent magnet synchronous motor. The method according to any one of claims 1 to 4,
The permanent magnet is characterized in that the polar anisotropic ring magnet
Permanent magnet synchronous motor. 6. The method according to any one of claims 1 to 5,
When the number of stator protrusions is Z (Z is a natural number) and the number of poles of the permanent magnet is 2P pole (P is a natural number), Z / (3 (phase) × 2P) is 0.5 or 0.25. It is configured to
Permanent magnet synchronous motor.

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