JPH02269456A - Motor - Google Patents

Abstract

PURPOSE:To reduce cogging torque by providing long teeth and short teeth in an armature core and by disposing them in a specific positional relationship. CONSTITUTION:A magnet 3 of a rotor 2 face twelve slots (a) to l for winding and twelve teeth of an armature core 4 at prescribed gap therefrom. The armature core 4 has long teeth in the number of L (L is an integer) of which the effective pitch is larger than D=360 deg./T and short teeth in the number of M (M is an integer) of which the effective pitch is smaller than D, and the numbers of the long teeth and the short teeth are set to be L>=3 and M>=3. Moreover, it has short-tooth block comprising two or more short teeth and long-tooth blocks comprising at least one long tooth in the same numbers and the short- tooth block and the long-tooth block are disposed alternately on the circumference. The number of the short-tooth blocks and that of the long-tooth blocks are set to be integral multiples of three, respectively. By this constitution, cogging torque can be reduced and therefore highly precise rotation control and positional control of a motor for driving a joint of a robot and a motor for driving an NC apparatus are enabled.

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 NC equipment. 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. An annular magnet 3 is attached to the outer periphery of a ferromagnetic rotor 2 attached to a rotating shaft 1. 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 JT-wire grooves 5 at equal angular intervals, and 12 teeth 6 between each winding groove.
are formed, and three-phase windings At to A4. Bl~B4. C1
~C4 is wrapped.

Winding AI, A2. A3. A4 is wound so as to surround the three teeth, and one ends of the windings A2 and A4 are respectively stored in both winding grooves in which the winding At is stored.

Similarly, one ends of windings A1 and A3 are stored in both winding grooves in which winding A2 is stored, and one ends of winding A2 and A3 are stored in both winding grooves in which winding A3 is stored, respectively. 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. Windings B1 to B4 of other phases. The same applies to C1 to C4. Hereinafter, Al-A4 will be grouped together as an A-phase winding group, and B
Let 1 to B4 be a B-phase winding group, and 01 to C4 be a C-phase winding group. The magnetic flux generated by the magnet 3 in the field section flows into or out of each tooth of the armature core 4, and interlinks with the A, B, and C phase winding groups. A, B.

There is an electrical phase difference of 120 degrees between the C-phase winding groups. Here, 180 degrees of electrical angle corresponds to 1 magnetic pitch of 360''/P (P is the number of magnetic poles of the field section) of the field section (in this example, since P=4, the mechanical angle of 90 degrees is (1 magnetic pole pitch, equivalent to 180 electrical degrees).

Figure 2 shows the configuration diagram of the drive circuit, and the windings A1 to A1 in Figure 1 are shown in Figure 2.
A4 are connected in series in consideration of each winding direction to form a human phase winding group. Similarly, windings B1 to B4 are connected in series considering each winding direction to form a B-phase winding group,
The windings 01 to C4 are connected in series in consideration of each winding direction to form a C-phase winding group. The 3-phase winding group is star-connected, and the 0 position detection unit 12 whose terminal is connected to the drive unit 11 detects the rotational position of the magnet 30, and detects the 3-phase sine that changes as the magnet 3 rotates. wavy signal P1
．． P2. Output P3. The drive unit 11 receives a command signal F.
and the three-phase body numbers PI, P2 . P3 is input, and a three-phase sinusoidal current 11 proportional to the product of both is input.
, 12.13 is output. As a result, a rotational force in a predetermined direction is generated by the interaction between the electric currents 11, 12, 13 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 of FIG. 1 developed along the lines xx' and Y-Y' (the windings are omitted and the winding grooves are a~! ), 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 magnet 3 of the field part and the armature core 4 have magnetic periodicity as shown in FIG. 1, a cogging torque of a component (matching component) that exists in common in both occurs. Figure 4 shows the distribution characteristics of the magnetic flux density generated by the magnet 3 for all l1l (360 degrees).Since magnetic energy is an amount related to the square of the magnetic flux density, the 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 grooves a to 2. Since the winding grooves ayl 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 fire component. . Therefore, based on this, harmonic components such as the 24th, 36th, etc. are included. Cogging torque occurs when the magnetic non-uniformity component of the armature core 4 and the harmonic component of the period/waveform of the magnet 3 match (match), so the cogging torque of this conventional example is the 12th Harmonic components such as the 24th order, 24th order, etc. 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. In order to sufficiently reduce the cogging torque, it is necessary to make the basic order of the cogging torque quite high, and many auxiliary grooves must be provided in the armature core, which is impractical. Even when a large number of cogging torques 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 electric and a-type iron cores.

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) A field part having M1 magnetic poles at equal angular intervals on the circumference, and T (T is an integer multiple of 3 and an integer of 6 or more) winding grooves. An electric motor comprising an armature core housing phase windings, one of the field part and the armature core being rotatable relative to the other, the armature core comprising: , the effective pitch is D=36
L long teeth larger than 0°/T (L is an integer) and M teeth whose effective pitch is smaller than D (M is an integer)
, the number of the long teeth and the short teeth is L ≧ 3 M ≧ 3, and the short tooth block is made up of two or more adjacent short teeth and at least one of the long teeth. Each long tooth block has an integral multiple of 3, the number of long teeth of each of the long tooth blocks is equal, the number of short teeth of each of the short tooth blocks is equal, and the short tooth block and The above object is achieved by arranging the long tooth blocks alternately and symmetrically on the circumference.

In addition, the present invention uses permanent magnet materials to
(However, P is an even number greater than or equal to 2) The field part has field magnetic poles at equal angular intervals on the circumference, and
and an armature core in which three-phase SvA is housed in a winding groove (an integer multiple of 6 or more), and one of the field part and the armature core is provided with respect to the other. The motor is rotatable, and the armature core has L long teeth (L is an integer) with an effective pitch greater than D=360°/T, and M teeth (L is an integer) with an effective pitch smaller than D. provided that M is an integer) short teeth, the number of the long teeth and the short teeth is L ≧ 3 M ≧ 3, and a short tooth block consisting of at least one short tooth and two or more adjacent each having an integral multiple of 3 of the long tooth blocks consisting of the long teeth, the number of the long teeth of each of the long tooth blocks being equal, the number of the short teeth of each of the short tooth blocks being equal, and The above object is achieved by arranging the short tooth blocks and the long tooth blocks alternately and symmetrically on the circumference.

Furthermore, the present invention provides a rotor that forms a field portion 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 having a predetermined gap between the permanent magnet magnetic poles and the rotor. an armature core that stores three-phase windings in T winding grooves (T is an integer multiple of 3 and an integer of 6 or more); a drive circuit that supplies three-phase current to the windings of the armature core, and the armature core has L long teeth (L is an integer) with an effective pitch larger than D-360'/T; It has M (however, M is an integer) short teeth with a pitch smaller than D, the number of the long teeth and the short teeth is L ≧ 3 M ≧ 3, and from 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 the long teeth of each of the short tooth blocks being equal to each other. The above object is achieved by making the number of teeth equal and by arranging the short tooth blocks and the long tooth blocks alternately and symmetrically on the circumference.

Furthermore, the present invention provides a rotor that forms a field portion 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 having a predetermined gap between the permanent magnet magnetic poles and the rotor. an armature core that stores three-phase windings in T winding grooves (T is an integer multiple of 3 and an integer of 6 or more); and a drive circuit that supplies three-phase current to the windings of the armature core, 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. The above object is achieved by making the numbers of the short teeth equal, making the number of the short teeth of each of the short tooth blocks the same, and arranging the short tooth blocks and the long tooth blocks alternately and symmetrically on the circumference. This 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.
Similarly to the C-phase winding group, the three-phase winding group is wound in a form-wound manner (not shown). In other words, the winding A1 is wound across the winding grooves a to d. The winding A2 is wound from the winding groove d to g, the winding A3 is wound from the wire groove g to j, and the winding A2 is wound from the winding groove j to a. Line A
4 is wound, and the windings A1 to A4 are connected in series in consideration of the winding direction to form an A-phase winding group.

Similarly, the winding B1 is wound from the winding groove C to r, the winding B2 is wound from the winding groove f to i, and the winding B2 is wound from the winding groove i to 2. 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. Further, the winding CI is wound from the winding groove e to h, and the winding C is wound from the winding groove to k.
2 is wound, a winding C3 is wound across the winding groove k to b, a winding IC4 is wound across the winding groove e, and the windings 01 to C4 are wound around the winding. The drive circuit of this embodiment, which is connected in series to form a C-phase winding group in consideration of the winding direction, has the same configuration as that shown in FIG. 2, and the explanation thereof will be omitted.

In the embodiment shown in FIG. 5, the winding groove a of the armature core 4 is
-1 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 a tooth is the angle formed by the center of the winding grooves at both ends of the tooth.The number of winding grooves is T-3・P=12 (P is the number of magnetic poles in the field part and P=4 ), the effective pitch of each tooth is D=360@/T (in this example, D-120°/P=30") when arranged at equal angular intervals, so teeth larger than D are called long teeth. , D are called short teeth.Teeth a-b (teeth are represented by winding grooves at both ends) are short teeth, teeth b-c are short teeth, teeth c-d are short teeth, tooth d-
e is a long tooth, teeth e-f are short teeth, teeth f-g are short teeth, teeth gh
is a short tooth, tooth h-i is a long tooth, tooth ij is a short tooth, tooth j- is a short tooth, tooth ρ is a short tooth, and tooth 1-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 the winding grooves a to d (a, b, c, d) and the winding groove e
Between h and h (e, f, g, h) and between winding grooves i and l (t, j, ni, f), only short teeth are partially concentrated, and three short teeth Similarly, between the winding grooves d and e (d,
Between e) and the winding groove (h, i) and the winding groove! Between a and a (f.

In a), only long teeth are partially concentrated, forming a long tooth block consisting of one long tooth (does not include short teeth)
That is, three sets of short tooth blocks and long tooth blocks are arranged alternately on the circumference.

Short teeth a-b, b-c, c-d, e-1, r
-g.

For gh, i-J, j-, the effective pitch of k-1 is equal or approximately equal to 360@/(T+3)-24°. Long teeth de, hi, 1-a
The effective pitch of the teeth is equal to or approximately equal to 720°/(T+3)-48". In other words, the ratio of the effective pitch of the short teeth to the effective pitch of the long teeth is R:R+1 (R
-1). In addition, each long tooth is provided with one auxiliary groove, and the entire armature core groove consisting of the winding groove and the auxiliary groove is at equal angular intervals (360@/15-24" intervals) or approximately at equal angular intervals. The center of the valley groove (the center seen from the magnetic effect) is located in the interval.

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 in which one magnetic pole pitch 360°/P of the magnet 3 is a circumference vi. Therefore, 1 of magnet 3
The magnetic non-uniformity of the armature core 4 (magnetic variation caused by the arrangement of the winding groove and the auxiliary groove) can be considered using the magnetic pole pitch as the basic period, and in general, cogging is used to reduce the amount of variation. Torque becomes smaller. magnet 3
FIG. 6 shows the phase relationship between the winding groove a-1 and the auxiliary grooves a' to C' of the armature core 4, with one magnetic pole pitch as the basic period.

Winding grooves a, d, and g accommodate the A-phase winding group.

j is provided with a phase shift with a phase difference of 1/(T+3)=1/15 of one magnetic pole pitch (winding 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)
Similarly, the winding grooves c, f, and i accommodate the B-phase winding group.

2 is provided with a phase shift of 1/15 of the pitch of one magnetic pole, and its variation range is set to 115 of the pitch of one magnetic pole. Furthermore, a winding groove in which a C-phase winding group is housed;
A phase shift is provided for e and h with a phase difference of 1/15 of the tm pole pitch, and the variation range is set to 115 of one magnetic pole pitch. A phase winding groove group (a, d, g, j), B phase @ line groove group (c, f, i, l), and C phase winding groove group (b, e, h , k), there is a phase difference of 1/3 of l magnetic pole pitch. Also,
Auxiliary grooves a~C in a phase different from the phase of winding grooves a~2
' is located, and the entire groove consisting of the winding groove a-2 and the auxiliary grooves a to C' are all different in phase with a phase difference of 1/15. Figure 7 shows the waveform of the magnetic fluctuation of the armature core 4 due to the winding groove a-2 and the auxiliary grooves a' to C'. The magnetic variation changes smoothly.

Since the winding groove a-2 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. Figure 8 shows the 0 winding grooves a, d2g, which show the magnetic fluctuations of the conventional motor in Figure 1.
, j are in phase, and the winding grooves c, f, i,
z are in the same phase, the winding grooves, e, h,
Since k are in the same phase, the composite magnetic fluctuation of the conventional motor shown in FIG. 1 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 AI, A2 . A3゜A4. B
l, B2. B3. B4. The effective pitch of CI, C2, C3°C4 is (16/15 of 1m1M pitch) = 192 degrees (
(electrical angle) or less to (415 of one magnetic pole 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 A1 winding grooves a and d is 1.
44° (3 short teeth), A2 winding groove d
The angle between -g is 192" (one long tooth and two short teeth)
, the angle between the winding grooves g and j of A3 is 192'
(1 long tooth and 2 short dentary bones), the angle between the A4 winding groove j-a is 192° (1 long tooth and 2 short dentary bones) , for the B-phase winding group, the angle between the winding grooves c and f for B1 is 192'' (one long tooth and two short teeth), and the angle between winding grooves c and f for B1 is 192'' (one long tooth and two short teeth) Winding groove f-
The angle between i is 192° (one long tooth and two short teeth)
, the angle between the winding groove i-2 of B3 is 144'
(3 short dentary bones), B4 winding groove ρ-
The angle between C is 192° (one long tooth and two short teeth). Looking at the C-phase winding group, the angle between the C1 winding grooves e and h is 144° (three short dentaries);
The angle between the winding groove h- of C2 is 192° (
(1 long tooth and 2 short dentaries), the angle between -b in the winding groove of C3 is 192" (1 long tooth and 2 short dentaries), The angle between the winding groove and e is 192° (one long tooth and two short teeth).In this way, the winding groove in which each phase of winding is stored is Winding work is easier if the fluctuating range of the groove is small (less than 1/3 of the pitch of one magnetic pole) and the effective pitch of the winding is smaller (from 192 degrees or less to 144 degrees or more). This also makes automation 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.
,br, Even if CI is eliminated, the composite magnetic fluctuation is smaller than that of the conventional example shown in FIG. In general, cogging torque can be reduced by devising the arrangement of long teeth and short teeth and alternately arranging short tooth blocks and long tooth blocks of an integral multiple of 3. At this time, if the total number of teeth in the adjacent set of short tooth block and long tooth block is different from a multiple of 3, then
The phase of the teeth can be easily varied. In addition, the total effective pitch of three consecutive sets of short tooth blocks and long tooth blocks is set equal to (360°/P) ・Q, and the total number of teeth in one set of adjacent short tooth blocks and long tooth blocks is If it is equal to Q, the phase difference between the three-phase winding group is 120
degree (electrical angle), and three sets of 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 armature core groove consisting of the winding groove and the auxiliary groove is set to the effective pitch of the short teeth. If they are arranged at intervals of 1/R of the pitch, the cogging torque can be easily reduced. 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 in Figure 5 by 2 units of angle (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 1 (B)
In this configuration, the effective pitch of the short teeth in Fig. 5 is 3 unit angles (l
The unit angle is 360°/39-9.23"), 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 groove consisting of the winding groove and the auxiliary groove is are arranged at 1 unit angle intervals.The configuration of Table 1(C) is as follows:
The effective pitch of the short teeth in the figure is 1 unit angle (1 unit angle is 36
0°/21 = 17.14°), 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. This is what was placed.

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.

(Margin below) Table 2 The configuration in Table 2 (A) consists of three sets of long tooth blocks consisting of three long teeth and three short tooth blocks consisting of one short tooth arranged alternately on the circumference. (Exchange the number of short teeth and long teeth in Figure 5), and set the effective pitch of the short teeth by 1 unit angle (1 unit angle is 360″'
/21-17.14@), the effective pitch of the long teeth was set to 2 unit angles, auxiliary grooves were provided on the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove was arranged at 1 unit angle intervals. It is something. In the configuration shown in 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 short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at one unit angular intervals.

In the configuration of Table 2 (C), the effective pitch of the short teeth is set to 3 unit angles (1 unit angle is 360°/33 strokes 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 1 unit angle (l unit angle is 360"/21 = 17.14
), the effective pitches of the two long teeth are set to 2 and 3 unit angles, respectively, an auxiliary groove is provided on the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is made positive for 1 unit angle. In the configuration shown in Table 3 (B), the effective pitch of the two short teeth is all 3 unit angles (1 unit angle is 360°/45=
8°), the effective pitch of the two long teeth is 4 units angle and 5 unit angle, respectively, 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 1 unit angle. They are arranged at angular intervals.

In each of the above embodiments, the number of magnetic poles of the magnet 3 in the field section is set to P=4, but the present invention is not limited to such a case.For example, the number of magnetic poles of the magnet 3 in the field section is P=4. If P = 8, three-phase windings will be pattern-wound in T = 3 P = 24 winding grooves, but a short tooth block consisting of 7 short teeth and one Table 4 shows an example in which cogging torque is reduced by alternately arranging three sets of long tooth blocks 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 set to 2 unit angles, auxiliary grooves are provided on the long teeth, and the entire grooves consisting of the winding groove and the auxiliary groove are arranged at intervals of 1 unit angle.

The configuration in Table 4 (B) has an effective pitch of short teeth of 2 units angle (
1 unit angle is 360 @ / 65 = 5.538°), the effective pitch of the long teeth is 3 unit angles, auxiliary grooves are provided on the long teeth and short teeth, and the groove consists of the winding groove and the auxiliary groove. In the configuration of Table 4 (C), in which the whole of the short teeth are arranged at 1 unit angle intervals, the effective pitch of the short teeth is 3 unit angles (1 unit angle is 360
” /75=4.8＠＠ﾑI、、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 in the field 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. Table 5 shows an example in which the cogging torque is reduced by the arrangement.

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 one unit. The configuration shown in Table 5 (B), which is arranged at angular intervals, has an effective pitch of short teeth of 2 units of angle (1 unit of angle is 360°/69=5.
217'), the effective pitch of the long teeth is 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 1 unit angle intervals. It is.

The configuration in Table 5(C) has the effective pitch of the short teeth set by 3 unit angles (
One unit angle is 360@/93=3.871), 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 groove consisting of the winding groove and the auxiliary groove is The entire structure is arranged at 1 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, P-pole field magnetic poles are arranged at equal angular intervals on the circumference (equal angular intervals or approximately equal angular intervals), and 3-phase magnets are installed in T winding grooves. In the case of a motor equipped with an armature core containing windings of D-360°/T
It has L (however, L is an integer) long teeth that are larger than D, and M (however, M is an integer) short teeth whose effective pitch is smaller than D, and the number of long teeth and short teeth is L ≧ 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. , and by increasing the number of short tooth blocks and long tooth blocks by an integral multiple of 3, the cogging torque can be easily reduced.

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) and M teeth whose effective pitch is smaller than D (M is an integer)
The number of long teeth and short teeth is L ≧ 3 M ≧ 3, and the number of short teeth blocks consisting of at least one short tooth and the same number of long teeth blocks consisting of two or more long teeth. The cogging torque can be easily reduced by arranging short tooth blocks and long tooth blocks alternately on the circumference and making the number of short tooth blocks and long tooth blocks each an integral multiple of 3.

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 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 the continuous 3 & Il short tooth block and long tooth block 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 set of short tooth blocks and the number of teeth in long tooth blocks is equal to Q, then a three-phase winding The phase of the winding groove can be easily varied while maintaining the phase between the groups at 120 degrees ('T!1 air 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 R
;R+1 (where R is an integer) or at least 1
If an auxiliary groove is provided on each of the long teeth and the entire groove consisting of the winding groove and the auxiliary groove is arranged at an interval of 1/R of the effective pitch of the short teeth, the cogging torque can be easily reduced significantly. can(
However, the total number of grooves is not an integral multiple of the number of magnetic poles P).

In the above embodiments, the magnet is placed on the inside and the armature core is placed on the outside, but the relationship may be reversed.

Further, the field section is not limited to an annular magnet, and the field portion may be formed of a plurality of magnetic scrapers, and various other 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, electric motors for driving joints of robots, 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 a motor according to an embodiment of the present invention, and FIG. A diagram showing the phase relationship of the winding grooves when looking at the armature core shown in the figure, Figure 7 is a diagram showing the magnetic fluctuation of the embodiment shown in Figure 5, and Figure 8 is a diagram showing the magnetic variation shown in Figure 1. FIG. 3 is a diagram showing magnetic fluctuations in a conventional example. 2...Rotor, 3...Magnet, 4
・・・・・・Armature core, 5. a-1... Winding groove, 6... Teeth, a'~cl..., Auxiliary groove, Al~A4. Bl-B4. C1-C4...
...Winding wire. Name of agent: Patent attorney Shigetaka Awano (1 person)

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 the short tooth blocks is equal, the number of the short teeth of each of the short tooth blocks is the same, and the short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on a circumference. . (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 the short tooth blocks is equal, the number of the short teeth of each of the short tooth blocks is the same, and the short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on a circumference. . (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 in which short tooth blocks and long tooth blocks are alternately arranged symmetrically on the circumference. (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 in which short tooth blocks and long tooth blocks are alternately arranged symmetrically on the circumference.