JP4713348B2 - Permanent magnet synchronous motor - Google Patents

Description

  The present invention relates to a permanent magnet type synchronous motor (hereinafter referred to as a motor). More specifically, the present invention relates to a cogging torque reduction structure in a permanent magnet type synchronous motor.

  In general, a permanent magnet synchronous motor includes a stator core having a plurality of pole teeth protruding in the radial direction and arranged at equal angular intervals with a slot in between, and a stator including a coil wound around the pole teeth, And a rotor provided with permanent magnets in which S poles and N poles are alternately arranged in the circumferential direction on a peripheral surface facing a tip surface of the tooth via a predetermined gap.

In such a motor, gogging torque is generated by the magnetic attractive force acting between the stator core and the permanent magnet, and this cogging torque causes rotation unevenness and signals, which is not preferable. Thus, it has been proposed to reduce cogging torque in the entire motor by forming an auxiliary groove called a dummy slot on the tip surface of the pole teeth (see, for example, Patent Document 1).
JP 11-18326 A

  However, when an integrated stator core as described in Patent Document 1 is used, the nozzles for winding the coils are adjacent to each other so that the nozzles can enter the slots formed between the pole teeth. There is no choice but to widen the gap between the tips of the pole teeth. For this reason, since the cogging torque generated in the gap between the tips of adjacent pole teeth is large, it is necessary to enlarge the auxiliary groove in order to offset it. As a result, there is a problem that the magnetic collecting force of the stator core is reduced.

  In view of the above problems, an object of the present invention is to provide a motor capable of reducing the cogging torque while suppressing a decrease in the collecting force of the stator core.

In order to solve the above problems, the present invention includes a stator core in which a plurality of pole teeth protruding in the radial direction are arranged at equal angular intervals with a slot between them, and a coil wound around the pole teeth. In a permanent magnet type synchronous motor having a stator and a rotor having permanent magnets in which S poles and N poles are alternately arranged in the circumferential direction on a circumferential surface facing a tip surface of the pole teeth via a predetermined gap The stator core includes a plurality of divided cores provided with the pole teeth arranged in the circumferential direction, and the plurality of pole teeth includes a tip portion that extends in the circumferential direction on the tip side, Is formed with an auxiliary groove that divides the tip surface at an equal angle in the circumferential direction, and the opening width in the circumferential direction of the gap formed between the tip portions of adjacent pole teeth in the plurality of pole teeth, The opening width in the circumferential direction of the auxiliary groove is substantially equal, The opening area of the gap formed between the tip parts of adjacent pole teeth in the number of pole teeth is substantially equal to the opening area of the auxiliary groove, and between the tip parts of adjacent pole teeth in the plurality of pole teeth. In the gap formed in the step, the depth dimension defined by the radial dimension at the circumferential end portion of the tip end portion and the radial depth dimension of the auxiliary groove are substantially equal, and are adjacent to each other in the plurality of pole teeth. The internal volume of the gap formed between the tips of the mating pole teeth is substantially equal to the internal volume of the auxiliary groove .

In the present invention, since the split core is used, the stator can be configured by arranging the split core in the circumferential direction after winding the coil around the split core. For this reason, since it is not necessary to pass the nozzle for winding a coil in the clearance gap between the tip parts of a pole tooth, the clearance gap between tip parts of a pole tooth can be narrowed. For this reason, the cogging torque which generate | occur | produces in the clearance gap between the front-end | tip parts of adjacent pole teeth can be made small. Moreover, since the auxiliary groove | channel which divides | segments this front end surface to the circumferential direction at equal angles is formed in the front end surface of a pole tooth, the cogging torque in the whole motor can be reduced. In addition, since the gap between the tip portions of the pole teeth is narrow, the auxiliary groove may be narrowed, so that a reduction in the collecting force of the stator core due to the formation of the auxiliary groove can be suppressed. In addition, when an auxiliary groove is formed on the tip surface of the pole tooth, generation of eddy current can be suppressed. Further, since the gap formed between the tip portions of the adjacent pole teeth and the auxiliary groove in the plurality of pole teeth are formed in the above-described dimensions, the gap is generated between the tip portions of the adjacent pole teeth. The cogging torque and the cogging torque generated in the auxiliary groove can be made equal, and therefore the cogging torque in the entire motor can be reduced.

  In the present invention, the permanent magnet is preferably composed of a plurality of divided permanent magnets arranged in the circumferential direction. If comprised in this way, cost reduction can be aimed at compared with the case where an integral-type permanent magnet is used. Further, in the case of a split permanent magnet, when magnetizing a magnet, not only radial magnetization but also anisotropic magnetization such as parallel magnetization can be easily performed. Therefore, it is easy to make the waveform of the induced voltage close to a sine wave.

  In the present invention, it is preferable that the plurality of divided permanent magnets are arranged in a state in which the divided permanent magnets adjacent in the circumferential direction are separated from each other. If comprised in this way, when the division | segmentation permanent magnets cannot contact | connect or deliberately contact, the part which a magnetic pole changes is made constant by making the space | interval between division | segmentation permanent magnets into a fixed space | interval. be able to.

  In the present invention, it is preferable that the plurality of divided permanent magnets are arranged in a state in which the divided permanent magnets adjacent in the circumferential direction are in contact with each other. If comprised in this way, the operation | work at the time of arrange | positioning a division | segmentation permanent magnet to the circumferential direction can be performed easily and efficiently. Further, by arranging the split permanent magnets in contact with each other, the portion where the magnetic pole changes can be made constant.

  In the present invention, it is preferable that the surface of the split permanent magnet facing the tip surface of the pole teeth is an arc surface having a curvature that is narrow at the center in the circumferential direction and wide at both sides in the circumferential direction. . The narrower the gap between the tip surface of the pole teeth and the permanent magnet, the greater the magnetic force collection and the induced voltage, while the cogging torque also increases. If this shape is adopted, the magnetic force collection and the induced voltage are reduced. Without this, the cogging torque can be reduced.

The present invention can be applied to an inner rotor type motor in which the rotor is disposed inside the stator. The present invention may be applied to an outer rotor type motor in which the rotor is disposed outside the stator .

In the present invention, since the split core is used for the stator, the stator can be configured by arranging the split core in the circumferential direction after winding the coil around the split core. For this reason, since it is not necessary to pass the nozzle for winding a coil in the clearance gap between the tip parts of a pole tooth, the clearance gap between the tip parts of a pole tooth can be narrowed. For this reason, the cogging torque which generate | occur | produces in the clearance gap between the front-end | tip parts of adjacent pole teeth can be made small. Moreover, since the auxiliary groove | channel which divides | segments this front end surface to the circumferential direction at equal angles is formed in the front end surface of a pole tooth, the cogging torque in the whole motor can be reduced. In addition, since the gap between the tip portions of the pole teeth is narrow, the auxiliary groove may be narrowed, so that a reduction in the collecting force of the stator core due to the formation of the auxiliary groove can be suppressed. In addition, when an auxiliary groove is formed on the tip surface of the pole tooth, generation of eddy current can be suppressed. Further, since the gap formed between the tip portions of the adjacent pole teeth and the auxiliary groove in the plurality of pole teeth are formed in the above-described dimensions, the gap is generated between the tip portions of the adjacent pole teeth. The cogging torque and the cogging torque generated in the auxiliary groove can be made equal, and therefore the cogging torque in the entire motor can be reduced.

  A motor to which the present invention is applied will be described below with reference to the drawings. The present invention can be applied to both the inner rotor type and the outer rotor type. Hereinafter, an example in which the present invention is applied to an inner rotor type motor will be described.

[Embodiment 1]
FIG. 1 is a cross-sectional view showing a configuration of a motor to which the present invention is applied. 2A and 2B are a cross-sectional view showing a configuration of a stator core to which the present invention is applied, and an explanatory view showing a configuration of auxiliary grooves.

(overall structure)
As shown in FIG. 1, the motor 1 of this embodiment includes a cylindrical motor case 22, a stator 3 disposed in the motor case 22, and a rotor 4 disposed inside the stator 3. ing. The motor case 22 is open at both ends in the motor center axis M direction, and a bearing holding member 21 is attached to the motor case 22 so as to cover one of the openings, and the bearing is held so as to cover the other opening. A member 23 is attached to the motor case 22. Therefore, the bearing holding member 21 and the bearing holding member 23 are also used as case members. The rotor 4 includes a permanent magnet 42 on the outer peripheral surface of the rotating shaft 41, and bearings 43 and 44 held by bearing holding members 21 and 23 are attached to both ends of the rotating shaft 41.

  As shown in FIGS. 1 and 2A, the stator 3 includes a stator core 31 in which a plurality of pole teeth 311 protruding radially inward are arranged at equal angular intervals with a slot 35 therebetween, and pole teeth 311. In contrast, the coil 32 wound via an insulator 33 is provided, and the tip surface 313 of the pole tooth 311 is opposed to the outer peripheral surface of the permanent magnet 42 through a predetermined gap. Here, the coil 32 is wound thinly on the inner peripheral side in the radial direction and thick on the outer peripheral side.

(Configuration of stator core)
In the motor 1 configured as described above, the stator core 31 has a configuration in which a plurality of divided cores 310 having pole teeth 311 are arranged in an annular shape at equal angular intervals in the circumferential direction. In this embodiment, the stator 3 has nine poles, and nine divided cores 310 are arranged at intervals of 40 °. In each of the plurality of divided cores 310, each pole tooth 311 includes a tip portion 312 extending on both sides in the circumferential direction on the tip side, and a gap 38 is formed between the tip portions 312 of adjacent pole teeth 311. Is formed. However, in this embodiment, since the split core 310 is used for the stator core 31, after the coil 32 is wound around the split core 310, the stator 3 can be configured by arranging the split core 310 in the circumferential direction. It is not necessary to pass the nozzle for winding the wire through the gap 38 between the tip portions 312 of the pole teeth 311. Therefore, the opening width of the gap 38 between the tip portions 312 can be narrowed. For example, in this embodiment, the opening width d1 of the gap 38 formed between the tip portions 312 is 0.5 mm , and the depth dimension d2 is 0.8 mm .

However, since the cogging torque is generated even if the gap 38 between the tip portions 312 is narrow, in this embodiment, the tip surface 313 of the pole tooth 311 has a slit shape that divides the tip surface 313 at an equal angle in the circumferential direction. The auxiliary groove 39 is formed. The number of the auxiliary grooves 39 may be set to an optimum value according to the size of the divided core 310 and the like, but in this embodiment, the divided core 310 occupies an angle θc of 40 °. Two auxiliary grooves 39 are formed at an angular interval of 13.3 ° on the tip surface 313 of 311, and the angular ranges θa and θb of the three regions on the tip surface 313 of the pole tooth 311 are all 13. 33 °.

(Permanent magnet configuration)
In the present embodiment, in the rotor 4, the permanent magnet 42 disposed around the rotation shaft 41 is composed of a plurality of divided permanent magnets 420 disposed at equal angular intervals. In this embodiment, the permanent magnet 42 is constituted by six divided permanent magnets 420.

  Here, the six divided permanent magnets 420 are arranged in a state where the divided permanent magnets 420 adjacent in the circumferential direction are in contact with each other.

  The six divided permanent magnets 420 have an inner circumferential surface that is a circular arc surface centered on the motor center axis M, but an outer circumferential surface that faces the distal end surface 313 of the pole tooth 311 is a distal end surface of the pole tooth 311. The size of the gap formed between 313 and 313 is a circular arc surface having a curvature that is narrow at the center in the circumferential direction and wide at both sides in the circumferential direction.

(Main effects of this form)
As described above, in this embodiment, since the split core 310 is used for the stator core 31, after the coil 32 is wound around the split core 310, the split core 310 can be arranged in the circumferential direction to constitute the stator 3. . For this reason, since it is not necessary to pass the nozzle for winding the coil 32 through the gap 38 between the tip portions 312 of the pole teeth 311, the gap 38 between the tip portions 312 can be narrowed. For this reason, the cogging torque generated in the gap 38 between the tip portions 312 of the pole teeth 311 is small.

  Further, since the auxiliary groove 39 that divides the tip surface 313 at an equal angle in the circumferential direction is formed on the tip surface 313 of the pole tooth 311, the cogging torque in the entire motor can be reduced.

  For example, when the auxiliary grooves 39 are formed at equal angular intervals as shown in FIG. 3A, and when the auxiliary grooves 39 are not formed as shown in FIG. 3B, as shown in FIG. When the cogging torque and the induced voltage are simulated in the case where the auxiliary groove 39 is formed at a position shifted from the equiangular interval, the results shown in FIGS. 3D and 3E are obtained. FIG. 3D is a graph showing a comparison of simulation results of cogging torque, and FIG. 3E is a graph showing a comparison of simulation results of induced voltage. 3D and 3E, the measurement results when the auxiliary grooves 39 are formed at equiangular intervals as shown in FIG. 3A are indicated by solid lines La, and as shown in FIG. 3B. The measurement result when the auxiliary groove 39 is not formed is indicated by a solid line Lb, and as shown in FIG. 3C, the measurement result when the auxiliary groove 39 is formed at a position shifted from the equiangular interval is indicated by a solid line Lc. is there.

  As can be seen from FIG. 3D, in the configuration according to the present invention shown in FIG. 3A, the auxiliary grooves 39 are not formed (the shape shown in FIG. 3B) or the auxiliary grooves 39 are spaced at equal angular intervals. The cogging torque can be greatly reduced as compared with the case where it is formed at a position deviated from (the shape shown in FIG. 3C). Further, as shown in FIG. 3E, even when the configuration shown in FIG. 3A is adopted, the configuration in which the auxiliary groove 39 is not formed (the shape shown in FIG. 3B), the auxiliary groove 39, etc. Compared with the case where the configuration (shape shown in FIG. 3C) formed at a position deviated from the angular interval is adopted, the induced voltage does not decrease.

  In addition, according to the present embodiment, since the split core 310 is used for the stator core 31, the gap 38 between the tip portions 312 of the pole teeth 311 can be narrowed, so the auxiliary groove 39 may be narrowed. It is possible to suppress a decrease in the magnetic collecting force of the stator core 31 that performs the operation.

Further, when the auxiliary groove 39 is formed on the tip surface 313 of the pole tooth 311, the tip surface 313 that collects magnetism is collected.
As a result of the unevenness formed in the magnetic field, the space in the magnetic circuit is increased, and the magnetic flux collected is locally reduced. Thereby, since the overcurrent generated on the surface of the tip end surface 313 that collects the magnetism can be reduced, the generation of the eddy current can be suppressed.

Here, the circumferential opening width of the auxiliary groove 39 is preferably equal to the circumferential opening width d1 of the gap 38 formed between the tip portions 312 of the adjacent pole teeth 311. The radial depth dimension of the auxiliary groove 39 is preferably equal to the radial depth dimension d2 of the gap 38 formed between the tip portions 312 of the adjacent pole teeth 311. Moreover, the opening area per one of the auxiliary grooves 39 is preferably equal to the opening area of the gap 38 formed between the tip portions 312 of the adjacent pole teeth 311, and further, the opening area per one of the auxiliary grooves 39. The internal volume is preferably equal to the internal volume of the gap 38 formed between the tip portions 312 of the adjacent pole teeth 311. With this configuration, the cogging torque generated in the gap 38 between the tip portions 312 of the pole teeth 311 can be made equal to the cogging torque generated in the auxiliary groove 39, so that the cogging torque in the entire motor is reduced. it can.

  In this embodiment, since the split permanent magnet 420 is used as the permanent magnet 42, the cost can be reduced as compared with the case where an integral permanent magnet is used. Further, with the split permanent magnet 420, when magnetizing the magnet, not only radial magnetization but also anisotropic magnetization such as parallel magnetization can be easily performed. Therefore, it is easy to make the waveform of the induced voltage close to a sine wave.

  Further, in the present embodiment, the plurality of divided permanent magnets 420 are arranged in a state where the divided permanent magnets 420 adjacent to each other in the circumferential direction are in contact with each other, so that the work for arranging the divided permanent magnets 420 in the circumferential direction is easy and easy. It can be done efficiently. Further, by arranging the split permanent magnets 420 in contact with each other, the portion where the magnetic poles can be changed can be made constant. Further, when the divided permanent magnets 420 are not in contact with each other, the portions where the magnetic poles can be changed can be made constant by setting the intervals between the divided permanent magnets to be constant.

  Furthermore, in the split permanent magnet 420, the outer peripheral surface facing the tip surface 313 of the pole tooth 311 has a narrow gap between the tip surface 313 and the tip surface 313 of the pole tooth 311 at the center in the circumferential direction. It consists of a circular arc surface with a curvature that widens on both sides. Here, when the gap between the tip surface 313 of the pole tooth 311 and the permanent magnet 42 is narrowed, the magnetic collecting force and the induced voltage are increased, while the cogging torque is also increased. In addition, the cogging torque can be reduced without reducing the induced voltage.

That is, when the radius of the virtual circle formed by the tip surface 313 of the pole tooth 311 is fixed to 20 mm, the radius of the virtual circle formed by the outer peripheral surface of the permanent magnet 42 (the radius of the rotor 4) is set to 15.9 mm. The values of the induced voltage emf [vp-p] and the cogging torque T [mNmp-p] when the curvature of the divided permanent magnet 420 is changed as shown below are as follows.
Curvature of split permanent magnets Induced voltage Cogging torque 14 132.2 0.905
13 130.9 0.672
12 129.3 0.480
11 127.3 0.315
10 124.6 0.183
9 120.9 0.100
8 115.8 0.063
In order not to reduce the induced voltage emf [vp-p], when the radius r [mm] (radius of the rotor 4) of the virtual circle formed by the outer peripheral surface of the permanent magnet 42 is changed as shown below, the following results are obtained. Rotor radius Induced voltage Cogging torque 15.9 115.8 0.063
16.0 121.4 0.092
16.1 127.3 0.139
16.2 131.5 0.209
It becomes. Thus, if the radius of the virtual circle (the radius of the rotor 4) formed by the outer peripheral surface of the permanent magnet 42 is increased, a decrease in induced voltage can be suppressed, but the virtual circle formed by the outer peripheral surface of the permanent magnet 42 The cogging torque also increases as the radius (the radius of the rotor 4) increases. Therefore, by providing the auxiliary groove 39, it is possible to suppress a reduction in the induced voltage and reduce the cogging torque.

[Other embodiments]
In the above embodiment, a configuration is adopted in which two auxiliary grooves 39 are formed in the pole teeth 311. However, if the inner diameter of the divided core 310 is large, three auxiliary grooves 39 are provided, and the inner diameter of the divided core 310 is When it is small, one auxiliary groove 39 may be provided.

Moreover, in the said form, although the width dimension d1 of the clearance gap 38 was 0.5 mm and the depth dimension d2 was 0.8 mm , the width dimension d1 of the clearance gap 38 is set to 0.4-1.6 mm, for example, Since the depth dimension d2 of the gap 38 is set to 0.3 to 1.2 mm, for example, the auxiliary groove 39 is more preferably set to have an internal volume so that the opening area or the depth dimension is equal to the gap 38. What is necessary is just to comprise equally.

  Further, in the above embodiment, the divided permanent magnet 420 employs a configuration in which the divided permanent magnets 420 are fixed to the rotating shaft 41 while being connected to each other. However, the divided permanent magnets 420 are fixed to the rotating shaft 41 in a state of being separated from each other. It may be adopted.

It is sectional drawing which shows the structure of the motor to which this invention is applied. (A), (b) is sectional drawing which shows the structure of the stator core to which this invention is applied, and explanatory drawing which shows the structure of an auxiliary groove. It is explanatory drawing which shows the structure of a division | segmentation core, and the relationship between a cogging torque and an induced voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 3 Stator 4 Rotor 31 Stair core 310 Divided core 311 Polar tooth 312 Tip part 313 Tip face 38 Clearance 39 between tip parts Auxiliary groove 41 Rotating shaft 42 Permanent magnet 420 Split permanent magnet

Claims (6)

A stator core having a plurality of pole teeth protruding in the radial direction arranged at equal angular intervals with a slot in between, a stator having a coil wound around the pole teeth, and a predetermined surface on a tip surface of the pole teeth In a permanent magnet type synchronous motor having a rotor with permanent magnets in which S poles and N poles are alternately arranged in the circumferential direction on the circumferential surfaces facing each other through a gap,
The stator core is formed by arranging a plurality of divided cores provided with the pole teeth in the circumferential direction,
The plurality of pole teeth includes a distal end portion that extends in the circumferential direction on the distal end side,
An auxiliary groove that divides the tip surface at an equal angle in the circumferential direction is formed on the tip surface of the pole tooth,
The opening width in the circumferential direction of the gap formed between the tip portions of adjacent pole teeth in the plurality of pole teeth is substantially equal to the opening width in the circumferential direction of the auxiliary groove,
The opening area of the gap formed between the tip portions of adjacent pole teeth in the plurality of pole teeth is substantially equal to the opening area of the auxiliary groove,
In the gap formed between the tip portions of adjacent pole teeth in the plurality of pole teeth, the depth dimension defined by the radial dimension at the circumferential end portion of the tip portion and the radial direction of the auxiliary groove The depth dimension of
A permanent magnet type synchronous motor , wherein an inner volume of a gap formed between tip portions of adjacent pole teeth in the plurality of pole teeth is substantially equal to an inner volume of the auxiliary groove .   2. The permanent magnet type synchronous motor according to claim 1, wherein the permanent magnet includes a plurality of divided permanent magnets arranged in a circumferential direction.   3. The permanent magnet type synchronous motor according to claim 2, wherein the plurality of divided permanent magnets are arranged in a state in which the divided permanent magnets adjacent in the circumferential direction are separated from each other.   3. The permanent magnet type synchronous motor according to claim 2, wherein the plurality of divided permanent magnets are arranged in a state in which the divided permanent magnets adjacent in the circumferential direction are in contact with each other.   4. The curved permanent magnet according to claim 2, wherein a surface of the split permanent magnet that faces the tip surface of the pole teeth has a curvature that is narrow at the center in the circumferential direction and wide at both sides in the circumferential direction. A permanent magnet type synchronous motor comprising a surface. 6. The permanent magnet type synchronous motor according to claim 1, wherein the rotor is disposed inside the stator .

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