JPH02276442A - Motor - Google Patents

Abstract

PURPOSE:To reduce the cogging torque by equipping an armature core with short teeth and long teeth, arranging short-tooth blocks and long-tooth blocks alternately and symmetrically on the circumference, and making auxiliary grooves in the long teeth. CONSTITUTION:An armature core 4 has L number of long teeth having larger effective pitches than D(=360 deg./T) and M number of short teeth having smaller effective pitches than D, wherein both L and M are 3 or larger integers and T is 6 or a larger integral multiple of three. As many short-tooth blocks as integral multiples of three and as many long-tooth blocks as integral multiples of three are made, the number of the long teeth of each of the long-tooth blocks is equalized, the number of the short teeth of each of the short-tooth blocks is equalized, the short-tooth blocks and the long-tooth blocks are arranged alternately and symmetrically on the circumference, and auxiliary grooves a'-c' are made at least in the long teeth.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electric motor having a field portion having field magnetic poles and an armature core having a winding groove.

Conventional configuration and its problems In a motor in which winding grooves are provided in the armature core to house multiphase windings, the magnetic flux of the field part is transferred to the teeth formed between the winding grooves. It has the advantage that the output is large because it can converge.

Therefore, it is widely used as a driving power source for industrial robots and NCf1 devices. However, in such a motor, cogging torque is generated due to the interaction between the magnetic poles of the field section and the winding grooves of the armature core. This will be explained below with reference to the drawings, taking a brushless DC motor as an example.

FIG. 1 is a diagram showing the main parts of the structure of a conventional electric motor.6 An annular magnet 3 is attached to the outer periphery of a ferromagnetic rotor 2 attached to a rotating shaft l. The magnet 3 has four magnetic poles magnetized at equal angular intervals, forming a field portion. An armature core 4 is arranged at a predetermined gap from the magnet 3 of the field section. One of the magnet 3 and the armature core 4 is rotatably supported relative to the other (in this example, the magnet 3 is configured to rotate relative to the armature core 4).

The armature core 4 is provided with 12 winding grooves 5 at equal angular intervals, 12 teeth 6 are formed between each winding groove, and three-phase windings A1 to A4 are formed. ．． Bl~B4. C1-C
4 is wrapped. Winding AI, A2. A3. A4 is 3
One end of the windings A2 and A4 are respectively stored in both winding grooves in which the winding AI is stored. Similarly, one ends of windings A1 and A3 are stored in both winding grooves in which winding A2 is stored, and windings A2 and A3 are stored in both winding grooves in which @ wire A3 is stored. One end of A4 is housed, and one ends of windings A1 and A3 are housed in both winding grooves in which winding A4 is housed. Other phase winding Bl-B4. C1-C
The same applies to 4. Hereinafter, At-A4 will be collectively referred to as the A-phase winding group, 81 to B4 will be referred to as the B-phase winding group, and 0
1 to C4 are a C-phase winding group. Magnet 3 in the field part
The generated magnetic flux flows into or out of each tooth of the armature core 4,
It is linked to the A, B, and C phase winding groups. There is an electrical phase difference of 120 degrees between the A, B, and C phase winding groups. Here, 180 degrees of electrical angle is 360 degrees of one magnetic pole pitch of the field part.
It corresponds to °/P (P is the number of magnetic poles in the field part) (in this example,
Since P=4, 90 degrees of mechanical angle is one magnetic pole pitch,
(equivalent to 180 electrical degrees).

Figure 2 shows the configuration diagram of the drive circuit, and the winding Al-
A4 are connected in series in consideration of each winding direction to form an A-phase winding group. Similarly, the windings 81 to B4 are connected in series considering each winding direction to form a B-phase winding group,
The windings CL-C4 are connected in series in consideration of each winding direction to form a C-phase winding group. The three-phase winding group is connected in a star shape, and its terminals are connected to the drive section 11. The position detection unit 12 detects the rotational position of the magnet 3 and generates a three-phase sinusoidal signal PI that changes as the magnet 3 rotates.
, P2. Output P3. The drive unit 11 receives a command signal F.
and three-phase signals PI, P2 . P3 is input, and a three-phase sinusoidal current It is proportional to the product of both.
, 12.13 is output. As a result, a rotational force in a predetermined direction is generated by the interaction between the currents II, 12.13 flowing to the A, B, and C phase winding groups and the magnetic flux of the magnet 3.

Next, the cogging torque of this conventional example will be explained with reference to FIG. FIG. 3 is a plan view of the magnet 3 and armature core 4 in FIG. ), cogging torque is generated when the magnetic energy stored in the magnetic field between the field part and the armature core changes in accordance with the relative rotation of the two. In particular, it occurs in relation to both the magnetic poles of the field part and the grooves of the armature core.
When both the magnetite 3 of the field part and the armature core 4 have magnetic periodicity as shown in FIG. 1, a cogging torque of a common component (matching component) is generated in both. Figure 4 shows the distribution characteristics of the magnetic flux density generated by the magnet 3 over the entire circumference (360 degrees).Since magnetic energy is an amount related to the square of the magnetic flux density, a field with the characteristics as shown in Figure 4 is shown. The fundamental harmonic component of the magnetic period/waveform of the magnet 3 in the section is the fourth harmonic component.

Here, a sine wave component generated once per rotation is defined as a first harmonic component. That is, the magnet 3 includes harmonic components such as the 8th, 12th, etc. based on the 4th ignition component.

On the other hand, magnetic non-uniformity (an amount related to permeance) of the armature core 4 is caused by the winding groove a-1. Since the winding grooves a%N of the armature core 4 are arranged at equal angular intervals (30 degree intervals), the fundamental harmonic component of the magnetic non-uniformity of the armature core 4 is the 12th winding component. becomes. Therefore, based on this, the 24th, 36th, etc.
Contains harmonic components such as Cogging torque occurs when the harmonic components of the magnetic non-uniformity of the armature core 4 and the period/waveform of the magnetite 3 match (match), so the cogging torque of this conventional example is 1
2nd order, 24th order, etc. harmonic components are generated.

The twelfth component of the cogging torque is directly related to the fundamental component of the magnetic inhomogeneity of the armature core 4 caused by the twelve winding grooves. Generally, the fundamental component of the armature core 4 is considerably larger than other harmonic components, and as a result, a very large cogging torque was generated in this conventional electric motor.

The present applicant has proposed a method for reducing such cogging torque in Japanese Patent Application No. 53-145489. In Japanese Patent Application No. 53-145489, cogging torque is reduced by increasing the basic harmonic component of cogging torque by providing auxiliary grooves on each tooth of the armature core. However, in order to sufficiently reduce the cogging torque using this method, the basic order of the cogging torque must be made considerably high, and many auxiliary grooves must be provided in the armature core, making it impractical. Moreover, even when many auxiliary grooves were provided, the cogging torque could not be sufficiently reduced because the basic component of the cogging torque coincided with the basic component of the armature core.

Purpose of the Invention The present invention takes these points into consideration, and provides an electric motor with extremely low cogging torque, which is equipped with a field part having field magnetic poles and an armature core having winding grooves. It is something to do.

Structure of the Invention In the present invention, a permanent magnet material is used to form a P pole (
P is an even number of 2 or more) field VA magnetic poles are arranged at equal angular intervals on the circumference, and T (however, T is an integer multiple of 3 and an integer of 6 or more) winding grooves. An electric motor comprising an armature core housing three-phase windings, one of the field part and the armature core being rotatable relative to the other, the armature core being , the effective pitch is D=360
L long teeth larger than °/T (L is an integer),
It has M short teeth with an effective pitch smaller than D (M is an integer), the number of the long teeth and the short teeth is L ≧ 3 M ≧ 3, and two or more adjacent short teeth and at least one long tooth block each having an integral multiple of 3, the number of the long teeth of each of the long tooth blocks being equal, and the number of long teeth of each of the short tooth blocks being equal to each other. The above object is achieved by making the number of short teeth equal, arranging the short tooth blocks and the long tooth blocks alternately and symmetrically on the circumference, and providing an auxiliary groove on at least the long teeth. This is what I did.

Further, in the present invention, a permanent magnet material is used to form a field part having P poles (P is an even number of 2 or more) at equal angular intervals on the circumference, and , T is an integer multiple of 3 and an integer of 6 or more), and an armature core in which three-phase windings are housed in a winding groove, and either one of the field part and the armature core is provided. is rotatable relative to the other, and the armature core has an effective pitch of D.
= L long teeth larger than 360°/T (wherein is an integer) and M short teeth whose effective pitch is smaller than D (however, M is an integer), and the long teeth and the short teeth The number of L ≧ 3 M ≧ 3, and each of the short tooth block consisting of at least one short tooth and the long tooth block consisting of two or more adjacent long teeth is an integral multiple of 3, and the The number of long teeth in each long tooth block is made equal, the number of short teeth in each short tooth block is made equal, and the short tooth blocks and the long tooth blocks are arranged alternately in a symmetrical manner on a circumference. The above object has been achieved by providing an auxiliary groove in at least the long teeth. -Furthermore, the present invention provides a rotor that forms a field part in which permanent magnet magnetic poles of P poles (where P is an even number of 2 or more) exist at approximately equal angular intervals on the circumference, and The armature core has T (however, T is an integer multiple of 3 and an integer of 6 or more) winding grooves each housing three-phase windings, and the three-phase winding grooves are spaced apart from each other. a drive circuit that supplies three-phase currents to the phase windings; It has M short teeth with an effective pitch smaller than D (M is an integer), the number of the long teeth and the short teeth is L ≧ 3 M ≧ 3, and two or more adjacent short teeth and at least one long tooth block each having an integral multiple of 3, the number of the long teeth of each of the long tooth blocks being equal, and the number of long teeth of each of the short tooth blocks being equal to each other. The above object is achieved by making the number of short teeth equal, arranging the short tooth blocks and the long tooth blocks alternately and symmetrically on the circumference, and providing an auxiliary groove on at least the long teeth. This is what I did.

Furthermore, in the present invention, a rotor forming a field part having permanent magnet magnetic poles of Pi (where P is an even number of 2 or more) at approximately equal angular intervals on the circumference, and The armature core is provided with three-phase windings stored in T winding grooves (T is an integer multiple of 3 and an integer of 6 or more), and as the rotor rotates, the three-phase windings are and a drive circuit that supplies three-phase current to the windings, and the armature core has L pieces (
However, it has long teeth (L is an integer) and M short teeth (however, M is an integer) whose effective pitch is smaller than D, and the number of the long teeth and the short teeth is L ≧ 3 M ≧ 3. None, each of a short tooth block consisting of at least one of the short teeth and a long tooth block consisting of two or more adjacent long teeth, an integral multiple of 3, and the number of the long teeth of each long tooth block. are made equal, the number of short teeth in each of the short tooth blocks is made equal, and the short tooth blocks and the long tooth blocks are alternately arranged symmetrically on the circumference, and at least the long teeth are provided with auxiliary grooves. By providing this, the above purpose has been achieved.

DESCRIPTION OF EMBODIMENTS FIG. 5 shows a plan development view of essential parts representing an embodiment of the present invention. In FIG. 5, a magnet 3 attached to a rotor 2 has four magnetic poles spaced at equal angular intervals; Armature core 4
The 12 winding grooves a-1 and 12 teeth face each other with a predetermined gap.

The 12 winding grooves of the armature core 4 are marked with A and B in Fig. 1.
, the three-phase winding group is wound in a die-wound manner similar to the C-phase winding group (not shown). That is, the winding AI is wound from winding grooves a to d, the winding A2 is wound from winding grooves d to g, and the winding AI is wound from winding grooves g to j. A3 is wound, and the winding A is passed from the winding groove j to a.
The windings At-A4 are connected in series in consideration of the winding direction to form an A-phase winding group.

Similarly, the winding Bl is wound from the winding groove C to r, the winding B2 is wound from the winding groove r to i, and the winding B2 is wound from the winding groove i to l. The wire B3 is wound in the winding groove 2.
A winding B4 is wound from the winding B4 to C, and the windings 81 to B4 are connected in series in consideration of the winding direction to form a third phase winding group. Furthermore, the winding C1 is wound from the winding groove e to h, and the winding C1 is wound from the winding groove to k.
2 is wound, a winding C3 is wound across the winding grooves k and b, a winding C4 is wound across the winding grooves e, and the windings C1 to C4 are wound around the winding grooves k and b. They are connected in series in consideration of the direction of rotation to form a C-phase winding group. The drive circuit of this embodiment has the same configuration as that shown in FIG. 2, and its explanation will be omitted.

In the embodiment shown in FIG. 5, the winding groove a of the armature core 4 is
-42 are arranged at unequal angular intervals, and the effective pitch of the teeth formed between the winding grooves is made non-uniform. Here, the effective pitch of the teeth is the angle formed by the centers of the winding grooves at both ends of the teeth. When the number of winding grooves is T = 3 and P = 12 (P is the number of magnetic poles in the field part and P = 4), if they are arranged at equal angular intervals, the effective pitch of each tooth is D = 360" / T
(In this example, D=120@/P=30@), so D
Teeth larger than D will be called long teeth, and teeth smaller than D will be called short teeth. Teeth a-b (represented by the winding grooves at both ends) are short teeth, teeth b-c are short teeth, teeth c-d are short teeth, teeth d-e are long teeth, and teeth e-f are short teeth. Tooth, tooth f-g is short tooth, tooth g
-h is a short tooth, tjah -i is a long tooth, tooth i-j is a short tooth,
Tooth j- is a short tooth, tooth -ffi is a short tooth, and tooth Q-a is a long tooth. That is, the number of long teeth is L=3, and the number of short teeth is M=9. Between winding grooves a to d (a, b, c, d
), between winding grooves e and h (e, f, g, h), and between winding grooves i and 2 (t, j, ni, f), only short teeth are partially concentrated. It forms a short tooth block consisting of three short teeth (not including long teeth). Similarly, between the winding groove d and e (d, e) and between the winding groove and i (h, i)
And a groove for the winding! Between a and a (La), only long teeth are partially concentrated, forming a long tooth block consisting of one long tooth (not including short teeth). That is, short tooth blocks and long tooth blocks of 31 Jl are arranged alternately on the circumference.

Short teeth a-b, b-c, c-d, e-f,
r-g.

The effective pitches of g-h, ij, j-, and ni-e are:
360'/(T+3)=24° or approximately equal to 24°. The effective pitches of the long teeth de, h-i, and 1-a are equal or approximately equal to 720°/(T+3)=48'. In other words, the ratio of the effective pitch of short teeth to the effective pitch of long teeth is R:R+l (R-1)
In addition, each long tooth is provided with one auxiliary groove, and the entire armature core groove, which consists of the winding groove and the auxiliary groove, is spaced at equal angular intervals (360° x 15 = 24° intervals). ) or the centers of the valley grooves (centers seen from the magnetic effect) are arranged at approximately equal angular intervals.

Next, the cogging torque of this embodiment will be explained. As already explained, cogging torque occurs when the harmonic components of the magnetic inhomogeneity caused by the winding grooves in the armature core match the harmonic components of the magnetic period and waveform caused by the magnetic poles of the field section. . The magnetic period/waveform of the magnet 3 in the field section is a periodic function whose period is one magnetic pole pitch 360''/P of the magnet 3. Therefore, with one magnetic pole pitch of the magnet 3 as the fundamental period, It is only necessary to consider the magnetic non-uniformity of the armature core 4 (magnetic fluctuations caused by the arrangement of the winding grooves and auxiliary grooves), and in general, if the amount of fluctuation is reduced, the cogging torque will be reduced.Magnet 3 The phase relationship when looking at the winding groove a-1 of the armature core 4 and the auxiliary grooves a' to C' with one magnetic pole pitch as the basic period is
As shown in the figure.

Winding grooves a, d, and g that house the winding group of the physiognomy.

j is provided with a phase shift with a phase difference of 1/(T+3)=1/15 of 1fff pole pitch (S-line grooves a, d).

The phases of g and j differ in four or more places), and their fluctuation range is 3/15 of 1 magnetic pole pitch = 115 (1 of 1 magnetic pole pitch)
/3 or less). Similarly, the winding groove c1f, i which can accommodate the B-phase winding group.

l is provided with a phase shift of 1/15 of the 168 pole pitch, and its variation range is set to 115 of the l magnetic pole pitch. Furthermore, the winding grooves e, h, and k that accommodate the C-phase winding group are provided with a phase shift of 1/15 of the pitch of one magnetic pole, and the variation range is 115 times the pitch of one magnetic pole. is being done. A phase winding groove group (a,
d, g, j) and B phase winding groove group (c, f, i
, ff1) and C phase winding groove group (b, e, h, k)
There is a phase difference of 1/3 of one magnetic pole pitch between them. Further, the auxiliary grooves a' to C' are located in a phase different from that of the winding grooves a to i, and S! II groove a-1 and auxiliary groove a
The entire grooves consisting of ' to C' are all different in phase with a phase difference of 1/15. Fig. 7 shows the waveform of the magnetic fluctuation of the armature core 4 due to the winding groove a-1 and the auxiliary grooves a' to C'. The magnetic variation changes smoothly.

Since the winding groove a-1 and the auxiliary grooves a' to C' have a phase difference of 1/15, the composite magnetic fluctuation component (alternating current component) is considerably small. FIG. 8 shows magnetic fluctuations of the conventional electric motor shown in FIG. Winding grooves a, d,
g and j are in the same phase, the winding grooves c, r, i, and 42 are in the same phase, and the winding grooves e and h are in the same phase, so the conventional motor shown in Fig. 1 has the same phase. The composite magnetic variation is very large (the conventional example shown in FIG. 1 does not have auxiliary grooves a' to C').

Comparing FIG. 7 and FIG. 8, it can be seen that the magnetic fluctuation of the motor of this embodiment is significantly reduced. As a result, the cogging torque of this embodiment is significantly reduced.

Furthermore, each winding A1 of this embodiment. A2. A3. A4゜B
L, B2. B3. B4. The effective pitch of C1, C2, C3, and C4 is (16/l 5 of 1 magnetic pole pitch) = 192 degrees (
(electrical angle) or less to (415 of one magnetic pitch) = 144 degrees (electrical angle) or more. Here, the effective pitch of the winding is the angle formed between the centers of the winding grooves in which the winding is housed. Looking at the A-phase winding group, the angle between the winding grooves ad wrapped with Al is 1446 (3 short teeth), and the angle between the winding grooves d and g wrapped with A2 is 1446 (three short teeth). The angle between is 192
° (1 long tooth and 2 short dentaries), the angle between the winding groove g-j of A3 is 192° (1 long tooth and 2 short dentaries), The angle between the winding groove j-a of A4 is 192" (one long tooth and two short teeth),
Looking at the winding group of phase B, the angle between the winding grooves c and f where Bl is wound is 192 @ (one long tooth and two short teeth), and the angle between winding grooves c and f where B1 is wound is 192 @ (one long tooth and two short teeth). The angle between the winding grooves fi is 19
2° (1 long tooth and 2 short dentary bones), the angle between the winding groove i-1 of B3 is 144° (3 short dentary bones)
, the angle between the winding grooves 1-c of B4 is 192°.
(1 long tooth and 2 short dentaries). Looking at the winding group of phase C, the angle between the CI winding groove e and h is 144'''' (3 short teeth), and the angle between the C2 winding groove h The angle between - is 192° (one long tooth and two short teeth), and the angle between -b is 192° (one long tooth and two short teeth). 2 short dentaries), C4
The angle between the winding groove b and e is 192° (1
2 long teeth and 2 short dentaries). In this way, the fluctuation range of the winding groove in which the windings of each phase are housed is reduced (l
(1/3 or less of the magnetic pole pitch) and if the range of variation in the effective pitch of the winding is to be reduced (from 192 degrees or less to 144
degree), the winding work becomes easier and automation is possible.

In the embodiment shown in FIG. 5 described above, an auxiliary groove was provided at the tip of the long tooth, but the auxiliary groove is not necessarily necessary.
, b', and c' are eliminated, the resulting magnetic fluctuation is smaller than the conventional example shown in Fig. 8. Generally, by devising the arrangement of the long teeth and short teeth, a short tooth block with an integral multiple of 3 is created. Cogging torque can be reduced by alternately arranging long tooth blocks. At this time, if the total number of teeth in the adjacent short tooth block and long tooth block of 1&[l is made different from a multiple of 3, the phase of the teeth can be easily varied. Also,
Set the overall effective pitch of three consecutive sets of short tooth blocks and long tooth blocks to be equal to (360°/P), and set the total number of teeth in one set of adjacent short tooth blocks and long tooth blocks to Q. If they are made equal, the phase difference between the three phase winding groups is 1
It can be made equal to 20 degrees (electrical angle), and the three-phase windings can be arranged evenly.

Also, if an auxiliary groove is provided on at least one long tooth,
The cogging torque reduction effect can be increased. Furthermore, by setting the effective pitch of the short teeth and the effective pitch of the long teeth to R:R±1 or R:R+3 (R is an integer), the entire groove of the armature core consisting of the winding groove and the auxiliary groove is Cogging torque can be easily reduced by arranging them at intervals of 1/R of the effective pitch. Other examples of such configurations are shown in Table 1.

Table 1 The configuration of Table 1 (A) is based on the effective pitch of the short teeth shown in Figure 5 by 2 unit angles (1 unit angle is 360@/27 = 13.33°)
The effective pitch of the long teeth is set to 3 unit angles, auxiliary grooves are provided on the short teeth and long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at 1 unit angle intervals.Table 0 In the configuration of 1(B), the effective pitch of the short teeth in Fig. 5 is set to 3 unit angles (1 unit angle is 360°/39 = 9.23@), and the effective pitch of the long teeth is set to 4 unit angles. Auxiliary grooves are provided on the short teeth and long teeth, and the entire grooves consisting of the winding groove and the auxiliary groove are arranged at one unit angle intervals. The configuration in Table 1 (C) is based on the effective pitch of the short teeth in Figure 5 by 1 unit angle (1 unit angle is 360
@/21=17.14' ) to I, the effective pitch of the long teeth is set to 4 unit angles, auxiliary grooves are provided on the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is spaced at 1 unit angle intervals. placed in °
It is something.

Moreover, even when the long tooth block consists of three long teeth and the short tooth block consists of one short tooth, cogging torque can be reduced. Such a configuration is shown in Table 2.

Table 2 The configuration of Table 2 (A) consists of 3 sets of long tooth blocks consisting of 3 long teeth and 3 sets of short tooth blocks consisting of 1 short tooth arranged alternately on the circumference and the short teeth shown in Figure 5. (exchanging the number of long teeth), and the effective pitch of short teeth by 1 unit angle (1 unit angle is 360"/
21 = 17.14°), the effective pitch of the long teeth is set to 2 unit angles, auxiliary grooves are provided on the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at 1 unit angle intervals. In the configuration of Table 2 (B), the effective pitch of the short teeth is set to 2 unit angles (1 unit angle is 360°/33 = 10.91'), and the effective pitch of the long teeth is set to 3 unit angles, Auxiliary grooves are provided on the long teeth and short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is
They are arranged at unit angle intervals.

In the configuration of Table 2 (C), the effective pitch of the short teeth is set to 3 unit angles (l unit angle is 360'/33 = 10.91°),
The effective pitch of the long teeth is set to 4 unit angles, auxiliary grooves are provided on the long teeth and short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at intervals of 1 unit angle.

Moreover, even when the long tooth block consists of two long teeth and the short tooth block consists of two short teeth, cogging torque can be reduced. Such a configuration is shown in Table 3.

Table 3 In the configuration of Table 3(A), the effective pitch of the two short teeth is all set at 1 unit angle (1 unit angle is 360'/21-17.1
4'), the effective pitch of the two long teeth is set to 2 unit angle and 3 unit angle, respectively, auxiliary grooves are provided on the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is spaced at 1 unit angle interval. In the configuration shown in Table 3 (B), the effective pitch of the two short teeth is all 3 unit angles (l unit angle is 360"/45
= 8"), the effective pitch of the two long teeth is 4 unit angle and 5 unit angle, respectively, and auxiliary grooves are provided on the long teeth and short teeth,
The entire grooves consisting of the winding groove and the auxiliary groove are arranged at one unit angular intervals.

In each of the embodiments described above, the magnetic flux of the magnet 3 in the field section was set to P=4, but the present invention is not limited to such a case. For example, magnet 3 in the field part!
ff If the number of 4M is set to P=8, T=3 P=2
The three-phase winding will be wound in the four winding grooves, but
Table 4 shows an example in which cogging torque is reduced by alternately arranging three sets of short tooth blocks consisting of seven short teeth and long tooth blocks consisting of one long tooth on the circumference.

(Margin below) The configuration of Table 4 (A) has the effective pitch of the short teeth set by 1 unit angle (
1 unit angle is 360@/27=13.33@), the effective pitch of the long teeth is 2 unit angles, and an auxiliary groove is provided on the long teeth, so that the entire groove consisting of the winding groove and the auxiliary groove is They are arranged at 1 unit angle intervals.

The configuration in Table 4 (B) has an effective pitch of short teeth of 2 units angle (
l unit angle is 360″'/65=5.5380), the effective pitch of the long teeth is set to 3 unit angles, auxiliary grooves are provided on the long teeth and short teeth, and a groove consisting of a winding groove and an auxiliary groove is created. In the configuration of Table 4 (C), in which the entire structure of the short teeth is arranged at 1 unit angle intervals, the effective pitch of the short teeth is 3 unit angles (1 unit angle is 3 unit angles).
60"/75=4.8"), and the effective pitch of the long teeth is 4.
Auxiliary grooves are provided on the long teeth and short teeth in a unit angle, and the entire grooves consisting of the winding groove and the auxiliary groove are arranged at intervals of one unit angle.

In addition, when the number of magnetic poles of the magnet 3 of the field 1 part is set to P=8, three sets of short tooth blocks consisting of one short tooth and long tooth blocks consisting of seven long teeth are arranged alternately on the circumference. Place it in
Table 5 shows an example of reducing cogging torque.

The configuration in Table 5(A) has the effective pitch of the short teeth set by 1 unit angle (
One unit angle is 360"/45=8@), the effective pitch of the long teeth is set to 2 unit angles, and an auxiliary groove is provided on the long teeth, so that the entire groove consisting of the winding groove and the auxiliary groove is 1 unit. In the configuration shown in Table 5(B), the effective pitch of the short teeth is set at 2 unit angles (1 unit angle is 360°/69=5.
217@) and 1. The effective pitch of the long teeth is set to 3 unit angles, auxiliary grooves are provided on the long teeth and short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at intervals of 1 unit angle. In the configuration of Table 5 (C), the effective pitch of the short teeth is set to 3 unit angles (l unit angle is 360°/93 = 3.871'),
The effective pitch of the long teeth is set to 4 unit angles, and auxiliary grooves are provided on the long teeth and short teeth, so that the entire groove consisting of the winding groove and the auxiliary groove is 1.
They are arranged at unit angle intervals.

Although various embodiments have been described, the present invention is not limited to such embodiments.

For example, by combining the embodiment with P=4 and the embodiment with P=8, it is possible to configure a motor in which the number of magnetic poles in the field section is P=12. In addition, by simply doubling the configuration of the embodiment shown in FIG.
It is possible to construct a motor with twice the number of magnetic poles and twice the number of winding grooves.

Using a permanent magnet material, the field part has field magnetic poles of Pli at equiangular intervals (equal angular intervals or approximately equiangular intervals) on the circumference, and 3-phase magnets are installed in T winding grooves. In the case of a motor equipped with an armature core containing windings, and in which one of the field section and the armature core is rotatable relative to the other, the armature core has an effective pitch of D. =360”/
It has L long teeth larger than T (L is an integer) and M short teeth whose effective pitch is smaller than D (M is an integer), and the number of long teeth and short teeth is ≧ 3. M ≧ 3, and has the same number of short tooth blocks consisting of two or more short teeth and long tooth blocks consisting of at least one long tooth, and the short tooth blocks and long tooth blocks are arranged alternately on the circumference. In addition, the cogging torque can be easily reduced by increasing the number of short tooth blocks and long tooth blocks by an integral multiple of three.

In addition, a permanent magnet material is used to form a field part having P-pole field magnetic poles at equiangular intervals (equal angular intervals or approximately equiangular intervals) on the circumference, and T winding grooves. In the case of a motor that is equipped with an armature core that houses three-phase windings, and in which either the field part or the armature core is rotatable relative to the other, the armature core is Pitch is D=360
”/L long teeth larger than T (L is an integer),
A short tooth block having M short teeth with an effective pitch smaller than D (M is an integer), the number of long teeth and short teeth being L ≧ 3 M ≧ 3, and consisting of at least one short tooth. and the same number of long tooth blocks consisting of two or more long teeth, short tooth blocks and long tooth blocks are arranged alternately on the circumference, and the number of short tooth blocks and long tooth blocks is 3 each. Cogging torque can be easily reduced by multiplying by an integer.

Furthermore, if the sum of the number of teeth in an adjacent pair of short tooth blocks and the number of teeth in a long tooth block is made different from a multiple of 3, the phase of the winding groove can be easily varied, and the cogging torque can be reduced. Effective in reducing Furthermore, the effective pitch of three consecutive sets of short tooth blocks and long tooth blocks is (360°/P)
・When Q is equal to (Q is an integer greater than or equal to 2), if the sum of the number of teeth in an adjacent pair of short tooth blocks and the number of teeth in a long tooth block is equal to Q, then a three-phase winding group The phase of the winding groove can be easily varied while maintaining the phase between 120 degrees (electrical angle), which is effective in reducing cogging torque.

Furthermore, the ratio of the effective pitch of the short teeth to the effective pitch of the long teeth is set to R:R+1 (where R is an integer), and an auxiliary groove is provided on at least one long tooth, so that the winding groove and the auxiliary If the entire grooves are arranged at intervals of 1/R of the effective pitch of the short teeth, the cogging torque can be easily reduced significantly (however, the total number of grooves is not an integral multiple of the number of magnetic poles P).

In the above embodiment, the magnet was placed on the inside and the armature core was placed on the outside, but the relationship may be reversed.
Further, the field portion is not limited to an annular magnet, and may be formed of a plurality of magnetic pole pieces. In addition, various modifications can be made without changing the gist of the present invention.

Effects of the Invention The present invention provides an armature core with short teeth and long teeth and arranges them in a special relationship, thereby realizing an electric motor with extremely low cogging torque. Therefore, based on the present invention, for example, electric motors for driving joints of robots and N
If it is configured as a drive motor for C equipment, highly accurate rotational drive and position control will be possible.

[Brief explanation of drawings]

Figure 1 is a structural diagram of the main parts of a conventional electric motor, Figure 2 is a configuration diagram of its drive circuit, Figure 3 is a plan development view of the electric motor in Figure 1,
Fig. 4 is a diagram showing the distribution of magnetic flux density of the magnet in the field part, Fig. 5 is a plan development view of an electric motor according to an embodiment of the present invention, and Fig. 6 is a diagram showing one rake pitch of the magnet as a basic r1 period. Fig. 5 is a diagram showing the phase relationship of the winding grooves when looking at the armature core, Fig. 7 is a diagram showing the magnetic fluctuation of the embodiment shown in Fig. 5, and Fig. 8 is the same as Fig. 1. FIG. 3 is a diagram showing magnetic fluctuations in the conventional example shown in FIG. 2...Rotor, 3...Magnet, 4
・・・・・・Armature core, 5. a-1... Winding groove, 6... Teeth, a-c'... Auxiliary groove, A1-A4. Bl-B4. C1 to C4... Winding wire. Name of agent: Patent attorney Shigetaka Awano (1 person) Fig. Y' Fig. Tomi Azu Evening

Claims (4)

[Claims] (1) Using permanent magnetic material, P pole (however, P is 2
The field part has field magnetic poles (an even number above) at equal angular intervals on the circumference, and a three-phase An electric motor is provided with an armature core housing a winding, and one of the field part and the armature core is rotatable relative to the other, and the armature core has an effective Pitch is D=360°/
It has L long teeth larger than T (however, L is an integer) and M short teeth whose effective pitch is smaller than D (however, M is an integer), and the number of the long teeth and the short teeth is L. ≧3 M≧3, and each of the short tooth blocks consisting of two or more adjacent short teeth and the long tooth blocks consisting of at least one long tooth is an integral multiple of 3, and each of the long tooth blocks The number of the long teeth of each of the short tooth blocks is made equal, the number of the short teeth of each of the short tooth blocks is made equal, and the short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on a circumference, and at least An electric motor in which an auxiliary groove is provided on the long teeth. (2) Using permanent magnetic material, P pole (however, P is 2
The field part has field magnetic poles (an even number above) at equal angular intervals on the circumference, and a three-phase An electric motor is provided with an armature core housing a winding, and one of the field part and the armature core is rotatable relative to the other, and the armature core has an effective Pitch is D=360°/
It has L long teeth larger than T (however, L is an integer) and M short teeth whose effective pitch is smaller than D (however, M is an integer), and the number of the long teeth and the short teeth is L. ≧3 M≧3, and each of the short tooth blocks consisting of at least one short tooth and the long tooth blocks consisting of two or more adjacent long teeth is an integral multiple of 3, and each of the long tooth blocks The number of the long teeth of each of the short tooth blocks is made equal, the number of the short teeth of each of the short tooth blocks is made equal, and the short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on a circumference, and at least An electric motor in which an auxiliary groove is provided on the long teeth. (3) A rotor that forms a field part having P-pole (P is an even number of 2 or more) permanent magnet magnetic poles at approximately equal angular intervals on the circumference, and a rotor that is provided with a predetermined gap from the permanent magnet magnetic poles. , an armature core in which three-phase windings are housed in T winding grooves (T is an integer multiple of 3 and an integer of 6 or more), and as the rotor rotates, the three-phase windings are and a drive circuit that supplies three-phase current to the armature core, the armature core has L long teeth (L is an integer) with an effective pitch larger than D=360°/T, and a drive circuit with an effective pitch larger than D=360°/T. M smaller pieces (however,
M is an integer), the number of the long teeth and the short teeth is L≧3 M≧3, and a short tooth block consisting of two or more adjacent short teeth and at least one of the short teeth. Each long tooth block has an integral multiple of 3, each long tooth block has an equal number of long teeth, each short tooth block has an equal number of short teeth, and An electric motor, wherein short tooth blocks and the long tooth blocks are alternately arranged symmetrically on a circumference, and at least the long teeth are provided with auxiliary grooves. (4) A rotor that forms a field part having P-pole (P is an even number of 2 or more) permanent magnet magnetic poles at approximately equal angular intervals on the circumference, and a rotor that is provided with a predetermined gap from the permanent magnet magnetic poles. , an armature core in which three-phase windings are housed in T winding grooves (T is an integer multiple of 3 and an integer of 6 or more), and as the rotor rotates, the three-phase windings are and a drive circuit that supplies three-phase current to the armature core, the armature core has L long teeth (L is an integer) with an effective pitch larger than D=360°/T, and a drive circuit with an effective pitch larger than D=360°/T. M smaller pieces (however,
M is an integer), the number of the long teeth and the short teeth is L≧3 and M≧3, and a short tooth block consisting of at least one short tooth and two or more adjacent short teeth Each long tooth block has an integral multiple of 3, each long tooth block has an equal number of long teeth, each short tooth block has an equal number of short teeth, and An electric motor, wherein short tooth blocks and the long tooth blocks are alternately arranged symmetrically on a circumference, and at least the long teeth are provided with auxiliary grooves.