JPH05252706A - Motor - Google Patents

Abstract

PURPOSE:To improve torque ripple too and thereby to improve rotation precision by effectively reducing the torque ripple caused by the torque by the magnetic flux corresponding to odd high frequency. CONSTITUTION:A rotor magnet 16 has eight magnetic poles N, S, N ... being magnetized in radial direction in the shape of symmetry after rotation, and the intensity of the magnetization in circumferential direction is in nearly trapezoidal shape. The center angles of the salient poles U1, U2, U3; V1, V2, and V3, W1, W2, and W3 of an armature core 18 are substantially 36 deg. each, and this is equivalent to an electrical angle of 144, and corresponds to twice one wavelength of the fifth higher harmonics. The magnetic flux corresponding to the fifth higher harmonics short-circuits, passing through the vicinity of the surface of each salient pole, and the total sum becomes substantially zero. The magnetic flux corresponding to the fifth higher harmonics does not interlink to the windings u, v, and w wound on each salient pole, and torque corresponding to the fifth higher harmonics does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor in which a magnet whose strength of magnetization changes in a substantially trapezoidal wave shape in the circumferential direction and an armature having an armature core having salient poles are relatively rotatable. Regarding

[0002]

2. Description of the Related Art A brushless structure in which a magnet whose magnetization intensity changes in a substantially trapezoidal wave shape in the circumferential direction and an armature having an armature core having salient poles are relatively rotatable. In an electric motor such as a spindle motor, a relative rotation occurs between a magnet and an armature, so that a change waveform of a magnetic flux passing near the armature includes an odd harmonic in addition to a fundamental wave.

Therefore, the magnetic flux corresponding to the odd harmonics is linked to the windings wound on the salient poles to generate the torque corresponding to the odd harmonics, which causes an increase in the torque ripple and the rotation accuracy. Was hindering the improvement of

The present invention has been made in view of the above problems existing in the prior art, and an object thereof is to provide a torque ripple caused by a torque due to a magnetic flux corresponding to an odd harmonic. It is an object of the present invention to provide an electric motor in which the rotation speed is effectively reduced, and thereby the rotation accuracy can be improved.

[0005]

In order to achieve the above object, an electric motor of the present invention has a magnet having a substantially trapezoidal wave-like shape in which a change in the magnetization strength associated with a change in a magnetic pole in the circumferential direction has a salient pole. An electric motor configured to be rotatable relative to an armature including an armature core, wherein a central angle of each salient pole is substantially (72n-10) degrees to 72n degrees [n is a positive integer] in electrical angle. ] Is assumed.

Further, in the electric motor of the present invention, the magnet has eight magnetic poles in eight-fold rotational symmetry, and the armature core has a central angle of substantially 33.5 to 36 degrees in mechanical angle.
9 salient poles in 9-fold rotational symmetry, and each salient pole has Y
Any one phase winding among the connected three-phase windings may be wound, and each phase winding may be wound around three salient poles every other pole. ..

Further, in the electric motor of the present invention, the magnet has four magnetic poles in a four-fold rotational symmetry, and the armature core has three magnetic poles whose central angle is substantially 31 to 36 degrees in mechanical angle. The salient poles and the three salient poles of substantially 67 degrees to 72 degrees are alternately and equidistantly arranged in the circumferential direction, so that they are rotationally symmetrical three times, and each salient pole has three Y-connections. Any one of the phase windings is wound, and the phase of the winding wound on any salient pole is different from the phase of the winding wound on the salient poles on both sides. It can also be one.

[0008]

According to the invention of claim 1, the strength of the magnetization changes in a substantially trapezoidal wave shape in the circumferential direction in accordance with the change in the magnetic pole in the circumferential direction of the magnet, so that the magnet and the armature rotate relative to each other. , The change waveform of the magnetic flux passing near the armature is
It will contain odd harmonics in addition to the fundamental wave. However, the central angle of the salient poles of the armature core is substantially (72n-10) to 72n degrees in terms of electrical angle,
Substantially corresponds to n times one wavelength of the fifth harmonic. Therefore, the magnetic flux corresponding to the fifth harmonic is short-circuited near the surface of each salient pole regardless of the relative angular position between the magnetic pole of the magnet and the salient pole of the armature core, and the total sum is substantially It becomes 0. Therefore, substantially, the magnetic flux corresponding to the fifth harmonic does not interlink with the winding wound around the salient pole, and the torque corresponding to the fifth harmonic is not generated. On the salient pole of the armature core,
Since the magnetic flux wraps around with the magnet, the central angle of the salient poles is substantially less than 72n degrees in electrical angle (72n
Even if it is -10) or more, the above-mentioned action is substantially produced.

In the invention of claim 2, since the magnetic poles of the magnet have eight poles, the central angle of the salient poles of the armature core, which is a mechanical angle of 33.5 to 36 degrees, corresponds to an electrical angle of 134 to 144 degrees. To do. Therefore, substantially, the magnetic flux corresponding to the fifth harmonic does not interlink with the winding wound around the salient pole, and the torque corresponding to the fifth harmonic is not generated.

The magnet has eight magnetic poles in eight-fold rotational symmetry, and the armature core has nine magnetic salient poles in nine-fold rotational symmetry, and each salient pole is Y-connected. Any one of the three-phase windings is wound, and the windings of each phase are wound on three salient poles every other pole. By passing different substantially symmetrical three-phase currents through the respective windings, torque due to the magnetic flux corresponding to the third harmonic is not generated.

According to the third aspect of the present invention, since the magnet has four magnetic poles, the central angle of the three salient poles of the armature core, which is a mechanical angle of 31 to 36 degrees, corresponds to an electrical angle of 62 to 72 degrees. 3 of the armature core with a mechanical angle of 67 to 72 degrees
The central angle of the salient poles corresponds to an electrical angle of 134 to 144 degrees. Therefore, substantially, the magnetic flux corresponding to the fifth harmonic does not interlink with the winding wound around the salient pole, and the torque corresponding to the fifth harmonic is not generated.

The magnet has four magnetic poles in four-fold rotational symmetry, and the armature core has two types of three salient poles, which are three poles alternately in the circumferential direction, at equal intervals, and three-fold rotational symmetry. Each salient pole is wound with one of the Y-connected three-phase windings, and the phase of the winding wound on any salient pole is Since the phases of the windings wound on the salient poles on both sides are different, a substantially symmetrical three-phase current having a phase difference of 120 degrees electrical angle is applied to each winding, so that the third harmonic wave is substantially generated. Therefore, the torque due to the magnetic flux corresponding to is not generated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 3 relate to an outer rotor type three-phase eight-pole motor as one embodiment of the present invention, and FIG. 1 is a schematic diagram thereof. Reference numeral 10 is a field means that constitutes a rotor, and 12 is an armature that constitutes a stator. The field means 10 is rotatably supported coaxially with the armature 12.

The field means 10 is a cylindrical rotor yoke 1
4 and a cylindrical rotor magnet 16 fitted in the rotor yoke 14 thereof. The rotor magnet 16 is
8 magnetic poles N, S, N ...
It has a rotational symmetry, and the polarity changes alternately in the circumferential direction. Therefore, the central angle of each magnetic pole N, S, N ... S is 45 degrees. The change in the strength of magnetization due to the change in the magnetic poles N, S, N ... S in the circumferential direction has a substantially trapezoidal wave shape as shown in FIG.

The armature 12 mainly comprises an armature core 18 and windings u, v and w. On the surface orthogonal to the direction of the rotation axis, the armature core 18 has a salient pole U that protrudes radially outward from an annular core base 18a located at the center.
1, W3, U2, V1, U3, V2, W1, V3 and W
2 has 9 poles in 9-fold rotational symmetry.
The shape of these salient poles is a substantially T shape in which each outer peripheral portion 18b is expanded in the circumferential direction, and the central angle of the outer peripheral portion 18b is substantially 36 degrees, that is, 144 degrees electrical angle. Therefore, each salient pole U1, W3, U2, V1, U3, V2, W
The central angle of the interval between the outer peripheral portions 18b at 1, V3, and W2 is 4 degrees. The outer peripheral portion 18b of each salient pole faces the inner peripheral surface of the rotor magnet 16 with a radial gap.

Each salient pole U1, W3, U2, V1, U3, V
2, W1, V3, and W2 are each wound with one phase of Y-connected three-phase windings u, v, and w, and each phase winding has three poles every three poles. It is wound around a salient pole. More specifically, the winding u is the salient poles U1, U2 and U3, the winding v is the salient poles V1, V2 and V3, and the winding w is the salient pole W.
1, W2 and W3 are wound in the same direction.

Since the change in the magnetization intensity of the rotor magnet 16 due to the change in the magnetic poles in the circumferential direction has a substantially trapezoidal wave shape, when the rotor magnet 16 rotates with respect to the armature 12, the change in the magnetic flux passing near the armature 12 is caused. The waveform will include odd harmonics in addition to the fundamental wave. However, salient poles U1, W3, U2, V1, U3, V in the armature core 18
The central angle of each outer peripheral portion 18b of 2, W1, V3 and W2 is
Each of them substantially corresponds to twice the electrical angle of 72 degrees and corresponds to twice one wavelength of the fifth harmonic. Therefore, the magnetic flux corresponding to the fifth harmonic is the rotor magnet 1
6 magnetic poles N, S, N ... S and salient poles U of the armature core 18
1, W3, U2, V1, U3, V2, W1, V3 and W
Regardless of the relative angular position with respect to 2, the salient poles U1 and W
3, U2, V1, U3, V2, W1, V3 and W2 short-circuit near the surface, the sum of which is substantially zero. Therefore, the magnetic flux corresponding to the fifth harmonic is substantially the salient poles U1 and U.
2, U3; V1, V2, V3 and windings u, v and w respectively wound around W1, W2 and W3 do not interlink,
The torque corresponding to the harmonic will not be generated.

The rotor magnet 16 has eight magnetic poles N, S, N ... S in a rotational symmetry of 8 times, and the armature core 18 has a salient pole U1 of 9 poles in a rotational symmetry of 9 times. , W3, U2,
Having V1, U3, V2, W1, V3 and W2,
Each salient pole U1, U2, U3; V1, V2, V3 and W
1, W2, and W3 are each wound with one of the three-phase windings u, v, and w that are Y-connected, u, v, and w. Since it is wound around three salient poles every other pole, a substantially symmetrical three-phase current having different phases by 120 electrical degrees is passed through the windings u, v, and w, so that substantially no The torque due to the magnetic flux corresponding to the higher harmonics will not be generated.

FIG. 3 shows the torque curve of this motor.
On the other hand, FIG. 5 shows a torque curve including torque corresponding to the fifth harmonic. As described above, in this motor, substantially no torque corresponding to the third harmonic wave and torque corresponding to the fifth harmonic wave are generated, so that the torque ripple in the generated torque is effectively reduced, and the rotation accuracy is reduced. It also helps to improve.

FIG. 4 shows an outer rotor type three-phase four-pole motor as another embodiment of the present invention, and FIG. 4 is a schematic diagram thereof. Reference numeral 50 is a field means that constitutes a rotor, and 52 is an armature that constitutes a stator. The field means 50 is rotatably supported coaxially with the armature 52.

The field means 50 is a cylindrical rotor yoke 5
4 and a cylindrical rotor magnet 56 fitted in the rotor yoke 54. The rotor magnet 56 is
It has four magnetic poles N, S, N, S magnetized in the radial direction in a rotationally symmetrical manner four times, and the polarities thereof alternate in the circumferential direction. Therefore, the central angle of each magnetic pole N, S, N, S is 90 degrees. The change in the strength of magnetization due to the change in the magnetic poles N, S, N, S in the circumferential direction has a substantially trapezoidal wave shape.

The armature 52 mainly comprises an armature core 58 and windings x, y and z. On the plane orthogonal to the direction of the rotation axis, the armature core 58 has a salient pole X that projects radially outward from an annular core base 58a located at the center.
1, Y2, Z1, X2, Y1 and Z2 at equal intervals and 3
It has six poles in a rotationally symmetrical manner. Salient pole X
The shapes of 1, Y2, Z1, X2, Y1 and Z2 are substantially T-shaped with the outer peripheral portion 58b widening in the circumferential direction, and the central angle of the outer peripheral portion 58b is substantially 36 degrees mechanical angle (72 degrees. Three salient poles X1, Y1 and Z1 having an electrical angle and three salient poles X2, Y2 and Z2 having a mechanical angle of 72 degrees mechanical (144 electrical degrees) are provided alternately in the circumferential direction. Therefore, the central angle of the interval between the outer peripheral portions 58b in each salient pole X1, Y2, Z1, X2, Y1 and Z2 is 6 degrees. Salient poles X1 and Y
The outer peripheral portions 58b of 2, Z1, X2, Y1 and Z2 face the inner peripheral surface of the rotor magnet 56 with a radial gap therebetween.

Each salient pole X1, X2; Y1, Y2 and Z
1, Z2 is wound with one of the Y-connected three-phase windings x, y, and z, and the phases of the windings wound with arbitrary salient poles are on both sides. The phase of the winding wound around the salient pole is different. The windings x, y and z each have three sets,
Two salient poles X that are substantially 180 degrees apart from each other
1, X2; Y1, Y2 and Z1, Z2 are wound in the same direction.

Since the change in the magnetization intensity of the rotor magnet 56 due to the change in the magnetic pole in the circumferential direction has a substantially trapezoidal wave shape, when the rotor magnet 56 rotates with respect to the armature 52, the change in the magnetic flux passing near the armature 52. The waveform will include odd harmonics in addition to the fundamental wave. However, the salient poles X1, Y2, Z1, X2, Y1 and Z in the armature core 58 are
The central angle of the outer peripheral portion 58b of No. 2 corresponds to substantially 72 degrees electrical angle and twice the 72 degree electrical angle, and corresponds to one wavelength of the fifth harmonic and twice that. Therefore, the magnetic flux corresponding to the fifth harmonic is generated by the magnetic poles N, S, N, S of the rotor magnet 56 and the salient poles X1, Y2, Z of the armature core 58.
Regardless of the relative angular position with respect to 1, X2, Y1 and Z2, a short circuit occurs near the surface of each salient pole X1, Y2, Z1, X2, Y1 and Z2, and the sum is substantially zero. Therefore, the magnetic flux corresponding to the fifth harmonic is substantially the salient poles X1 and X.
2; Y1, Y2 and winding x wound around Z1, Z2,
This means that the torque corresponding to the fifth harmonic does not occur without interlinking with y and z.

The rotor magnet 56 has four magnetic poles N, S, N, and S in a rotationally symmetrical four-fold structure.
The reference numeral 8 has two types of salient poles X1, Y1 and Z1 and X2, Y2 and Z2 of three poles alternately and equidistantly in the circumferential direction, and also three times in rotational symmetry. , X2; Y
1, Y2 and Z1, Z2 are wound with a winding x, y and z of any one phase among the windings x, y and z of the three phases connected in Y, and any salient poles X1 and X2. ; Y1, Y2 and Z
The phases of the windings x, y and z wound around 1, Z2 are different from the phases of the salient poles X1, X2 on both sides thereof; Y1, Y2 and the windings x, y and z wound around Z1, Z2. So 12
By supplying substantially symmetrical three-phase currents having different phases by 0 degree electrical angle to the windings x, y, and z, substantially no torque due to the magnetic flux corresponding to the third harmonic is generated.

Therefore, in this motor, substantially no torque corresponding to the third harmonic and torque corresponding to the fifth harmonic are generated, so that the torque ripple in the generated torque is effectively reduced, and the rotation accuracy is reduced. It also helps to improve.

The central angle of each salient pole in each motor is
The electrical angle may be substantially less than 72n degrees (72n-10) degrees or more [n is a positive integer]. Further, each of the above motors can be driven as a synchronous motor by a three-phase alternating current of a constant frequency having a phase difference of 120 degrees, and a three-phase drive current having a phase difference of 120 degrees can be supplied to the Hall element. Of course, it is also possible to drive by commutating according to the angular position of the magnetic pole of the rotor magnet detected by using the output or the counter electromotive voltage of the stator coil.

Furthermore, if a slip ring or the like is used, the field means may constitute the stator and the armature may constitute the rotor. It is also possible to configure the field means by an electromagnet or the like. The motor described above is merely an example. It goes without saying that the scope of the present invention is not limited to these.

[0029]

According to the electric motor of claim 1, the central angle of the salient poles of the armature core is substantially (72n) in electrical angle.
-10) to 72n degrees [n is a positive integer] and corresponds to an integral multiple of one wavelength of the fifth harmonic, so that the magnetic flux corresponding to the fifth harmonic is substantially wound around the salient pole. There is no interlinkage with the wound winding, and the torque corresponding to the fifth harmonic is not generated. Therefore, the torque ripple in the generated torque is effectively reduced, which can be useful for improving the rotation accuracy.

In the electric motor of claim 2, since the central angle of the salient poles of the armature core corresponds to an electrical angle of 134 to 144 degrees, the torque corresponding to the fifth harmonic is not substantially generated.
The torque due to the magnetic flux corresponding to the third harmonic is substantially not generated. Therefore, the torque ripple in the generated torque can be reduced more effectively, which can also help improve the rotation accuracy.

In the electric motor of claim 3, the central angle of the salient poles of the armature core is 134 to 144 degrees electrical angle or 62 to 7 degrees.
Since it corresponds to the electrical angle of 2 degrees, the torque corresponding to the fifth harmonic is not substantially generated, and the torque due to the magnetic flux corresponding to the third harmonic is not substantially generated. Therefore, the torque ripple in the generated torque is reduced more effectively,
It can also help improve the rotation accuracy.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an outer rotor type three-phase eight-pole motor.

FIG. 2 is a graph showing a change in magnetization intensity in the circumferential direction of a rotor magnet.

FIG. 3 is a torque curve.

FIG. 4 is a schematic diagram of an outer rotor type three-phase four-pole motor.

FIG. 5 is a torque curve.

[Explanation of sign]

 12 armatures 16 rotor magnets 18 armature cores 52 armatures 56 rotor magnets 58 armature cores U1 salient poles U2 salient poles U3 salient poles V1 salient poles V2 salient poles V3 salient poles W1 salient poles W2 salient poles W3 salient poles X1 salient poles X2 salient pole Y1 salient pole Y2 salient pole Z1 salient pole Z2 salient pole u winding v winding w winding x winding x winding y winding z winding

Claims (3)

[Claims] 1. A motor in which a magnet having a substantially trapezoidal wave-like change in the strength of magnetization due to a change in a magnetic pole in the circumferential direction and an armature having an armature core having salient poles are relatively rotatable. And the central angle of the salient pole is substantially (7
An electric motor characterized by being 2n-10) degrees to 72n degrees [n is a positive integer]. 2. The magnet has eight magnetic poles in a rotational symmetry of eight times, and the armature core has a central angle of substantially 3 mechanical angles.
There are 9 salient poles of 3.5 to 36 degrees in a 9-fold rotational symmetry, and each salient pole is wound with one of the Y-connected three-phase windings. The electric motor according to claim 1, wherein the windings of each phase are wound around three salient poles of every other pole. 3. The magnet has four magnetic poles in four-fold rotational symmetry, and the armature core has a central angle of substantially 31 in mechanical angle.
3 to 37 degrees salient poles and 67 to 72 degrees salient poles are alternately arranged at equal intervals in the circumferential direction, and are also three times rotationally symmetrical, and each salient pole is , One of the three windings of the Y-connection is wound, and the phase of the winding wound on any salient pole is wound on the salient poles on both sides of the winding. The electric motor according to claim 1, wherein the phase of the winding is different from that of the winding.