JP6484009B2 - motor - Google Patents

Description

  The present invention relates to a motor including a permanent magnet having magnetic poles formed with a skew angle.

  In the motor, cogging occurs in which the magnetic attractive force between the permanent magnet and the stator core pulsates finely depending on the rotation angle. Such cogging causes vibration and noise, and further deterioration of control performance. Therefore, it has been proposed to suppress cogging by forming the magnetic poles of the permanent magnet with skew. At this time, since the fundamental wave of cogging is generated by the least common multiple of the number of magnetic poles of the permanent magnet and the number of slots of the stator core per one rotation of the rotor, in order to cancel the fundamental wave of cogging, the skew angle is set to 60 electrical degrees. Generally set to °. For example, if the number of magnetic poles of the permanent magnet is 8 and the number of slots (number of salient poles) of the stator core is 12, the fundamental wave of cogging is generated 24 times per rotation of the rotor, so that the skew angle is 15 in mechanical angle. If it is set to ° (electrical angle 60 °), the fundamental wave of cogging can be canceled.

  On the other hand, when n is an integer equal to or greater than 1, when the number of magnetic poles of the permanent magnet is 2 × n and the number of salient poles of the stator core is 3 × n, the skew angle is a mechanical angle, (76 ° / n) × A configuration in which 0.8 is set to (76 ° / n) × 1.2, that is, a configuration in which the skew angle is 60.8 ° to 91.2 ° in electrical angle is proposed (see Patent Document 1).

Japanese Patent Laid-Open No. 5-168181

  Here, the inventor of the present application has reduced the degree of freedom in design with the miniaturization and flattening of the motor, so the width of the body around which the coil wire is wound around the salient pole of the stator core is reduced. Then, we are considering expanding the winding space of the coil wire. However, if the body width of the salient pole is reduced, the magnetic flux density in the non-excited state increases, resulting in an increase in cogging torque, and even if the magnetic pole is formed with a skew angle of 60 ° in electrical angle in the permanent magnet, There is a problem that the torque is large. On the other hand, in the skew angle range (electrical angle range of 60.8 ° to 91.2 °) described in Patent Document 1, it is difficult to suppress the cogging torque, or the back electromotive force is reduced or reversed. An increase in distortion of the electromotive force waveform occurs.

  In view of the above problems, an object of the present invention is to suppress cogging even when the magnetic flux density in the non-excited state of the trunk portion around which the coil wire is wound at the salient pole of the stator core is increased. Another object is to provide a motor capable of obtaining an appropriate back electromotive force.

In order to solve the above problems, a motor according to the present invention includes a stator core in which a plurality of salient poles around which a coil wire is wound are formed in the circumferential direction, and a cylindrical permanent magnet in which a plurality of magnetic poles are formed in the circumferential direction. And when the n is an integer greater than or equal to 1, the number of the magnetic poles is 2 × n, the number of the salient poles is 3 × n, barrel coil wire is wound, the magnetic flux density in a non-excitation state where no current to the coil wire is not less than 90% of the saturation magnetic flux density, the magnetic flux density in the non-excited state of the body portion than 1.0T The permanent magnet is characterized in that the magnetic pole is formed with an electrical angle of 65 ° to 75 °.

  In the present invention, the body around which the coil wire is wound around the salient pole has the magnetic flux density in the non-excited state increased to 90% or more of the saturation magnetic flux density. ing. Further, since the skew angle is 65 ° to 75 ° in electrical angle, cogging can be suppressed even when the magnetic flux density in the non-excited state of the portion where the coil wire is wound in the salient pole is increased. At the same time, an appropriate back electromotive force can be obtained.

  In the present invention, it is possible to adopt a configuration in which the body portion is magnetically saturated in a non-excited state in which the coil wire is not energized.

The present invention, the magnetic flux density in the non-excited state before kidou portion is effectively applied when it is more than 1.3 T.

  In the present invention, the dimension of the stator core in the motor axial direction is preferably longer than the dimension of the permanent magnet in the motor axial direction.

  In the present invention, the body around which the coil wire is wound around the salient pole has the magnetic flux density in the non-excited state increased to 90% or more of the saturation magnetic flux density. ing. Further, since the skew angle is 65 ° to 75 ° in electrical angle, cogging can be suppressed even when the magnetic flux density in the non-excited state of the portion where the coil wire is wound in the salient pole is increased. At the same time, an appropriate back electromotive force can be obtained.

It is explanatory drawing which shows typically the one aspect | mode of the motor to which this invention is applied. It is explanatory drawing which shows the principal part of the motor to which this invention is applied. It is a graph which shows changes, such as a cogging torque at the time of changing a skew angle, in the motor whose rating is 50W. It is explanatory drawing which shows the measurement result of cogging at the time of changing a skew angle in the motor whose rating is 50W. It is a graph which shows changes, such as a cogging torque at the time of changing a skew angle, in the motor whose rating is 100W. It is explanatory drawing which shows the measurement result of cogging at the time of changing a skew angle in the motor whose rating is 100W.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(General configuration of motor)
FIG. 1 is an explanatory view schematically showing one mode of a motor to which the present invention is applied. FIG. 2 is an explanatory view showing a main part of a motor to which the present invention is applied, and FIGS. 2A and 2B are an explanatory view of salient poles of a stator core and an explanatory view of a permanent magnet. In FIG. 1 (a), the number of magnetic poles of the permanent magnet is 4, but in FIG. 2 (b), a permanent magnet with 8 magnetic poles is shown so that the state of skew can be easily understood.

As shown in FIG. 1, in the motor 1, the stator 2 is fixed to the inner peripheral side of a cylindrical motor case 10. The stator 2 includes a stator core 20 in which a plurality of salient poles 21 are formed in the circumferential direction, and a coil wire 28 wound around the salient pole 21 via an insulator 27. The stator core 20 has a structure in which a plurality of magnetic plates are stacked, and an annular portion 22 held by the motor case 10 and salient poles that protrude radially inward from a plurality of locations in the circumferential direction of the annular portion 22. 21. In addition, the salient pole 21 has a trunk portion 23 that protrudes radially inward from the annular portion 22, and an inner peripheral flange portion 24 that extends in the circumferential direction at the radially inner end of the trunk portion 23. Yes.

  The motor case 10 holds ball bearings 4 and 5 at positions separated in the motor axial direction L, and the rotor 6 is rotatably supported by the ball bearings 4 and 5. The rotor 6 includes a rotating shaft 61 extending in the motor axial direction L, and a cylindrical permanent magnet 62 fixed to the outer peripheral surface of the rotating shaft 61, and the rotating shaft 61 is supported by ball bearings 4, 5. Has been. The outer peripheral surface 63 of the permanent magnet 62 is opposed to the inner peripheral flange portion 24 of the salient pole 21 on the radially inner side.

  In this way, the motor 1 is configured as an inner rotor type brushless motor. When the motor 1 is driven, the U, V, W phase coil wires 28 are connected to the U, V, W phase coils. Each sinusoidal motor current is fed.

  Here, the stator core 20 may be configured by arranging a plurality of divided cores 25 shown in FIG. 2A in the circumferential direction. In this case, the divided core 25 is a radially outer end portion of the salient pole 21. It has the outer peripheral side flange part 26 extended in the circumferential direction. Accordingly, when a plurality of divided cores 25 are arranged in the circumferential direction, the annular portion 22 is configured by the outer peripheral side flange portions 26 of the divided cores 25 adjacent in the circumferential direction contacting each other.

  2B, the permanent magnet 62 has a plurality of magnetic poles 620 formed in the circumferential direction. In the plurality of magnetic poles 620, N poles and S poles are alternately arranged. Here, the permanent magnet has a plurality of magnetic poles 620 formed with a skew of a skew angle θ. The skew angle θ is a spread angle in the circumferential direction at both axial ends of a boundary line 625 between one magnetic pole 620 and a magnetic pole 620 adjacent thereto. Therefore, if the skew angle θ is constant, when the length L62 of the permanent magnet 62 in the motor axial direction L is long, the inclination of the boundary line 625 between the magnetic pole 620 and the magnetic pole 620 becomes small, and the length L62 is short. In some cases, the slope of the boundary line 625 increases. The permanent magnet 62 may be integrally formed in the motor axial direction L, or may be divided into a plurality of parts in the motor axial direction L. In either case, the boundary line 625 is linear. Extend.

(Detailed configuration)
In the motor 1 configured as described above, when n is an integer of 1 or more, the number of magnetic poles 620 is 2 × n, and the number of salient poles 21 is 3 × n. Therefore, for example, when the number of magnetic poles 620 is 4, the number of salient poles 21 is 6, when the number of magnetic poles 620 is 6, the number of salient poles 21 is 9, and the number of magnetic poles 620 is 8. The number of salient poles 21 is twelve. As shown in FIG. 1, the dimension L20 of the stator core 20 in the motor axial direction L is longer than the dimension L62 of the permanent magnet 62 in the motor axial direction L.

  In the motor 1 of this embodiment, the width W0 of the body portion 23 around which the coil wire 28 is wound in the salient pole 21 is narrowed, and a space for winding the coil wire 28 is secured widely. As a result, the body portion 23 of the salient pole 21 is in a non-excited state in which the coil wire 28 is not energized, and the magnetic flux density is 1.0 T or more, further 1.3 T or more, and is magnetically saturated, or substantially It is in a magnetic saturation state. More specifically, the body portion 23 of the salient pole 21 is in a non-excited state, and the magnetic flux density is 90% or more of the saturation magnetic flux density.

Here, in the motor 1 of this embodiment, the permanent magnet 62 is formed with magnetic poles 620 with an electrical angle of 65 ° to 75 ° skew angle θ for the reason described later. For this reason, salient pole 2
Even when the magnetic flux density in the non-excited state of the one body portion 23 is increased to a substantially magnetically saturated state or a completely magnetically saturated state, cogging can be suppressed and an appropriate Back electromotive force can be obtained.

(Evaluation result 1)
In this example, in the motor 1 with a rating of 50 W, the influence on the cogging torque and the counter electromotive force when the skew angle θ is changed is examined, and the results are shown in FIGS. 3 and 4.

  FIG. 3 is a graph showing changes in cogging torque or the like when the skew angle θ is changed in the motor 1 having a rating of 50 W. FIGS. 3A, 3B, and 3C show the skew angle θ. 3 is a graph showing the relationship between the cogging torque and the cogging torque, the graph showing the relationship between the skew angle θ and the counter electromotive force, and the graph showing the relationship between the skew angle θ and the amount of distortion of the counter electromotive force. FIG. 4 is an explanatory diagram showing the measurement results of cogging when the skew angle θ is changed in the motor 1 having a rating of 50 W. FIGS. 4A and 4B show the skew angle θ as an electrical angle. It is explanatory drawing which shows cogging of the Example set to 70 degrees, and explanatory drawing which shows cogging of the reference example which set skew angle (theta) to 60 degrees by the electrical angle. Note that the amount of distortion of the back electromotive force is a distortion rate with respect to a sine wave. When the back electromotive force is a sine wave, the cogging torque decreases, and when the amount of distortion increases, the cogging torque tends to increase. Therefore, it is desirable that the distortion rate of the back electromotive force is as small as possible.

  As shown in FIG. 3A, when the skew angle θ is set to 60 °, the cogging torque is large, whereas the cogging torque decreases as the skew angle θ is increased from 60 °. When the skew angle θ is 85 °, the cogging torque is minimized, and when it exceeds 85 °, the cogging torque increases. Therefore, as shown in FIG. 4B, when the skew angle θ is set to 60 °, cogging is large, whereas as shown in FIG. 4A, the skew angle θ is set to 70 °. If set, cogging is small.

  As shown in FIG. 3B, the back electromotive force decreases as the skew angle θ increases from 60 °. Further, as shown in FIG. 3C, as the skew angle θ is increased from 60 °, the distortion amount of the back electromotive force rapidly increases when it exceeds 75 °.

  Therefore, in consideration of all the cogging torque, back electromotive force, and back electromotive force distortion amount, it is preferable to set the skew angle θ in the range of 65 ° to 75 ° (the range indicated by the arrow G in FIG. 3). If it is within the range, the cogging is suppressed even when the magnetic flux density in the non-excited state of the body portion 23 of the salient pole 21 is increased to a substantially magnetically saturated state or a completely magnetically saturated state. And an appropriate back electromotive force can be obtained. On the other hand, when the skew angle θ is less than 65 °, cogging is large, and when the skew angle θ exceeds 75 °, the counter electromotive force decreases and the amount of distortion of the counter electromotive force increases. Here, when the back electromotive force is small, the rotational torque when the motor 1 is driven is lowered, which is not preferable.

(Evaluation result 2)
FIG. 5 is a graph showing changes in cogging torque and the like when the skew angle θ is changed in the motor 1 with a rating of 100 W. FIGS. 5A, 5B, and 5C show the skew angle θ. 3 is a graph showing the relationship between the cogging torque and the cogging torque, the graph showing the relationship between the skew angle θ and the counter electromotive force, and the graph showing the relationship between the skew angle θ and the amount of distortion of the counter electromotive force. FIGS. 6A and 6B are explanatory diagrams showing measurement results of cogging when the skew angle θ is changed in the motor 1 having a rating of 100 W. FIGS. 6A and 6B show the skew angle θ as an electrical angle. It is explanatory drawing which shows cogging of the Example set to 68 degrees, and explanatory drawing which shows cogging of the reference example which set skew angle (theta) to 60 degrees by the electrical angle.

As shown in FIG. 5A, when the skew angle θ is set to 60 °, the cogging torque is slightly large, whereas the cogging torque decreases as the skew angle θ is increased from 60 °. When the skew angle θ is about 70 °, the cogging torque is minimized, and when it exceeds 75 °, the cogging torque increases rapidly. Therefore, as shown in FIG. 6B, when the skew angle θ is set to 60 °, cogging is large, whereas as shown in FIG. 6A, the skew angle θ is set to 68 °. If set, cogging is small.

  Further, as shown in FIG. 5B, the back electromotive force decreases as the skew angle θ increases from 60 °. Further, as shown in FIG. 5C, when the skew angle θ is set to 60 °, the amount of back electromotive force distortion is large, but as the skew angle θ becomes larger than 60 °, The amount of electromotive force distortion is reduced. When the skew angle θ is about 70 °, the amount of back electromotive force distortion is minimized, and when it exceeds 75 °, the amount of back electromotive force distortion increases rapidly.

  Therefore, considering all the cogging torque, back electromotive force, and back electromotive force distortion amount, it is preferable to set the skew angle θ in the range of 65 ° to 75 ° (the range indicated by the arrow G in FIG. 5). If it is within the range, the cogging is suppressed even when the magnetic flux density in the non-excited state of the body portion 23 of the salient pole 21 is increased to a substantially magnetically saturated state or a completely magnetically saturated state. And an appropriate back electromotive force can be obtained. On the other hand, when the skew angle θ is less than 65 °, cogging is large, and when the skew angle θ exceeds 75 °, the counter electromotive force decreases and the amount of distortion of the counter electromotive force increases.

(Other embodiments)
Although the inner rotor type brushless motor (motor 1) has been described above, the present invention is not limited to this, and is applicable to an outer rotor type brushless motor. In the above embodiment, the dimension L20 of the stator core 20 in the motor axial direction L is longer than the dimension L62 of the permanent magnet 62 in the motor axial direction L. However, the dimension L20 of the stator core 20 in the motor axial direction L is permanent. You may apply this invention to the motor shorter than the dimension L62 of the motor axial direction L of the magnet 62. FIG.

1 .... Motor, 2 .... Stator, 4, 5 .... Ball bearing, 6 .... Rotor, 10 .... Motor case, 20 .... Stator core, 21 .... Tail pole, 22 .... Ring part, ... Body part 24 .... Inner peripheral side flange part 25 ... Segment core 26 ... Outer side flange part 27 ... Insulator 28 ... Coil wire 61 ... Rotary shaft 62 ... Permanent magnet 620・ ・ Magnetic poles, 625 ・ ・ Boundary line, L ・ ・ Motor axial direction, W0 ・ ・ Body width, θ ・ ・ Skew angle

Claims (4)

A stator core in which a plurality of salient poles around which a coil wire is wound are formed in the circumferential direction;
A rotor including a cylindrical permanent magnet having a plurality of magnetic poles formed in the circumferential direction;
In a motor having
When n is an integer of 1 or more, the number of magnetic poles is 2 × n, the number of salient poles is 3 × n,
In the salient pole, barrel the coil wire is wound, the magnetic flux density in a non-excitation state where no current to the coil wire is not less than 90% of the saturated magnetic flux density, the magnetic flux in the non-excitation state of the body portion The density is 1.0 T or more,
The permanent magnet has the magnetic pole formed with an electrical angle of 65 ° to 75 ° skew angle.   The motor according to claim 1, wherein the body portion is magnetically saturated in a non-excited state in which the coil wire is not energized. 3. The motor according to claim 1, wherein a magnetic flux density of the body portion in a non-excited state is 1.3 T or more. The dimensions of the motor shaft line direction of the stator core, the motor according to any one of claims 1 to 3, characterized in that longer than the size of the motor shaft line direction of the permanent magnet.

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