JPH02269443A - Motor - Google Patents

Abstract

PURPOSE:To obtain a motor of which the cogging torque is small by a method wherein a short-tooth block and a long-tooth block are disposed alternately and symmetrically on the circumference and the sum of the numbers of teeth of one set of the short-tooth block and the long-tooth block adjacent to each other is made different from integral multiples of three. CONSTITUTION:A magnet 3 fitted to a rotor 2 has four magnetic poles at equal angular intervals and faces twelve slots (a) to l for winding of an armature core 4 and twelve teeth thereof at a prescribed gap therefrom. Between the slots (a) and (d) for winding, between the slots (e) and (h) for winding and between the slots (i) and l for winding, only short teeth are concentrated partly. Between the slots (d) and (e) for winding, between the slots (h) and (i) for winding and between the slots l and (a) for winding, likewise, only long teeth are concentrated partly. In other words, three sets of short-tooth blocks and long- tooth blocks are disposed alternately on the circumference. According to this constitution, the magnetic fluctuation of the armature core 4 caused by the slots (a) to l for winding and auxiliary slots a' to c' changes smoothly.

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.A ring-shaped magnet 3 is attached to the outer periphery of a ferromagnetic rotor 2 attached to a zero-rotation shaft 1. FIG. 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 wound, tail 0 volume AllAl, A2. A3. A4
is wound around three teeth, and windings A2 and A4 are respectively placed in both winding grooves in which winding A1 is stored.
One end of the 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. C1
The same applies to ~C4. Hereinafter, A1-A4 will be collectively referred to as an A-phase winding group, B1-B4 will be a B-phase winding group, and 01-C4 will 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, C
There is an electrical phase difference of 120 degrees between the phase winding groups. Here, 180 degrees of electrical angle is 1 magnetic pole pitch of 3 in the field part.
This corresponds to 60°/P (P is the number of magnetic poles of the field section) (in this example, since P=4, 90 degrees of mechanical angle is one magnetic pole pitch and corresponds to 180 degrees of electrical angle).

FIG. 2 shows a configuration diagram of the drive circuit. Winding A1~ in Figure 1
A4 are connected in series in consideration of each winding direction to form an A-phase winding group. Similarly, the windings B1-84 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 3 and detects the 3-phase winding that changes with the rotation of the magnet 3. Sine wave signal PL
, 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 11 proportional to the product of both is input.
, 12.13 is output. As a result, the electric current ml to the A, B, and C phase winding group 1. r2. + 3 and the magnetic flux of the magnet 3 interact to generate a rotational force in a predetermined direction.

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 according to the relative rotation of the two.In particular,
This occurs in relation to both the magnetic poles of the field part and the grooves of the armature core, and as shown in Figure 1, the magnet 3 of the field part and the armature core 4
When both have magnetic periodicity, 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 over the entire circumference (360 degrees).Since the 0M1 energy is a quantity related to the square of the magnetic flux density, the field with the characteristics shown in Figure 4 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 % It.

Since the winding grooves a-2 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 ignition component. becomes. Therefore, based on this, the 24th, 36th, etc.
Contains harmonic components such as 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 first order, the 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. 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. Not. Further, even when a large number of auxiliary grooves are provided, the cogging torque cannot be sufficiently reduced because the basic component of the cogging torque matches 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 (
It is equipped with a field part having field magnetic poles (P is an even number of 2 or more) arranged at equal angular intervals on the circumference, and an armature core in which 3-phase windings are housed in 3P winding grooves. , an electric motor in which either one of the field part and the armature core is rotatable relative to the other, and the armature core has 3P teeth formed between the winding grooves. and the effective pitch is D-12
L long teeth larger than 0°/P (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+M-3P L ≧ 3 M ≧ 3, and a short tooth block consisting of two or more adjacent short teeth and at least one of the long teeth. Each of the long tooth blocks has a plurality of teeth, each of the short tooth blocks has an equal number of short teeth, each of the long tooth blocks has an equal number of long teeth, and the short tooth block and the long tooth block have the same number of short teeth. The tooth blocks are arranged symmetrically alternately on the circumference, and the adjacent one
The above object is achieved by making the sum of the number of teeth of the short tooth block and the number of teeth of the long tooth block different from an integral multiple of 3.

In addition, in the present invention, a permanent magnet material is used to form a field part having field M1 magnetic poles of P poles (P is an even number of 2 or more) at approximately equal angular intervals on the circumference, and a field part having 3P S magnetic poles at equal angular intervals on the circumference. An electric motor comprising an armature core storing three-phase windings in a wire groove, and one of the field part and the armature core is rotatable relative to the other, The armature core is
3P teeth are formed between the winding grooves, L long teeth with an effective pitch greater than D=120'/P (where L is an integer) and M teeth with an effective pitch smaller than D ( However, it has short teeth (M is an integer), the number of the long teeth and the short teeth is L + M = T ≧ 3 M ≧ 3, and a short tooth block consisting of at least one short tooth and two short teeth. a plurality of long tooth blocks each consisting of the above-mentioned adjacent long teeth, the number of the short teeth of each of the short tooth blocks being equal, 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 long tooth blocks being equal; The short tooth blocks and the long tooth blocks are arranged symmetrically alternately on the circumference, and the adjacent l
The above object is achieved by making the sum of the number of teeth of the short tooth block and the number of teeth of the long tooth block of H different from an integral multiple of 3.

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 a rotor with a predetermined gap between the permanent magnet magnetic poles. an armature core that is provided with three-phase windings in 3P winding grooves, and a drive circuit that supplies three-phase currents to the three-phase windings as the rotor rotates. 1. The armature core has 3P teeth formed between the winding grooves. There are L long teeth whose effective pitch is larger than D=420'/P (L is an integer) and M short teeth whose effective pitch is smaller than D (M is an integer). and the number of the short teeth is set as L+M=3P L ≧ 3 M ≧ 3, and a short tooth block consisting of two or more adjacent short teeth and a long tooth block consisting of one long tooth, respectively. a plurality of short tooth blocks, the number of the short teeth of each of the short tooth blocks is made equal, the number of the long teeth of each of the long tooth blocks is made equal, and the short tooth blocks and the long tooth blocks are arranged alternately on the circumference. 1 arranged symmetrically and adjacent to
The above object is achieved by making the sum of the number of teeth in the short tooth block and the number of teeth in the long tooth block different from an integral multiple of three.

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 is provided with three-phase windings in 3P winding grooves, and a drive circuit that supplies three-phase currents to the three-phase windings as the rotor rotates. The armature core has 3P teeth formed between the winding grooves, and L teeth having an effective pitch greater than D-120°/P.
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+-MmiTL ≧ 3 M ≧ 3, each of a plurality of short tooth blocks consisting of at least one of the short teeth and a plurality of long tooth blocks consisting of two or more adjacent long teeth, and the short teeth of each of the short tooth blocks , the number of long teeth of each long tooth block is made equal, the short tooth blocks and the long tooth blocks are arranged symmetrically alternately on the circumference, and the adjacent one
The above object is achieved by making the sum of the number of teeth in the short tooth block and the number of teeth in the long tooth block different from an integral multiple of three.

DESCRIPTION OF EMBODIMENTS FIG. 5 is a developed plan view of essential parts representing an embodiment of the present invention. In FIG. 5, the magnet 3 attached to the rotor 2 has four magnetic poles at equal angular intervals, and the 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 form-wound manner similar to the C-phase winding group (not shown). In other words, the @ wire A1 is wound across the winding grooves a to d. The winding MA2 is wound from the winding groove d to g, the winding A3 is wound from the winding groove g to j, and the winding @WA is wound from the winding groove j to a.
A4 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 and the winding groove l
A winding B4 is wound from B to C, and the windings B1 to B4 are connected in series in consideration of the winding direction to form a B-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 wire 1c3 is wound across the winding groove k to b, a winding C4 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 in consideration of the direction to form a C-phase winding group, has the same configuration as that shown in FIG. 2, and therefore a description 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 when arranged at equal angular intervals is D=360＠/T (in this example, D-120"/P=30°), so teeth larger than D are called long teeth. , D are called short teeth. Teeth a-b (the teeth are exposed and removed by the winding grooves at both ends) are short teeth, teeth b-c are short teeth, and teeth c'-d are short teeth. short teeth,
Teeth d-e are long teeth, teeth ef are short teeth, teeth f-g are short teeth, teeth gh are short teeth, teeth h-i are long teeth, teeth ij are short teeth, tooth j
- is a short tooth, -fi is a short tooth, tooth 1. -a is a long tooth. In other words, the number of long teeth is L=3, and the number of short teeth is M=
It is 9. Between the winding grooves a and d (a, b, c, d), between the winding grooves e and h (e, r, g, h), and the winding groove i
Between 2 and 2 (i, J, ni, l), only short teeth are partially concentrated, forming a short tooth block consisting of three short teeth (no long teeth included), similarly. , winding grooves d to e
Between (d, e), between the winding groove l and l (h, i), and between the winding groove l and a C1°a), only the long teeth are partially concentrated. It forms a long tooth block consisting of several long teeth (not including 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-f,
r-g.

The effective pitch of g-h, i-j+ j-, and k-1 is equal or approximately equal to 360'/(T+3)=24''.Long teeth de, h-i, 1
The effective pitch of −a 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 spaced at equal angular intervals (360°/15=24' intervals).
Alternatively, the centers of the grooves (centers viewed from the perspective of 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 such that one magnetic pole pitch 360'/P of the magnet 3 is the number of periods. Therefore, 1 of magnet 3
It is sufficient to consider the magnetic non-uniformity of the armature core 4 (magnetic variation caused by the arrangement of the winding groove and auxiliary groove) using the ifl pole pitch as the basic period, and in general, if the amount of variation is to be reduced, Cogging torque becomes smaller. 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 of the magnet 3 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 4 or more places), and the variation range is 3/15 of l magnetic pole pitch = 115 (1 of 1 magnetic pole pitch
/3 or less). Similarly, the winding grooves c, f, and i accommodate the B-phase winding group.

l 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;
e, h, and k are provided with a phase shift of 1/15 of one magnetic pole pitch, and the variation range is set to 115 of one magnetic pole pitch. A phase winding groove group (a, d
, g, j) and B phase winding groove group (c, r, i, l) and C
There is one groove between each phase winding groove group (b, e, h, k).
There is a phase difference of 1/3 of the magnetic pole pitch. In addition, the winding groove a
The auxiliary grooves a'' to C' are located in a phase different from the phase of ~l, and the entire groove consisting of the II groove a-1 and the auxiliary grooves a' to C' has a phase difference of 1/15. Figure 7 shows the waveform of the magnetic fluctuation of the armature core 4 due to the winding grooves a-ρ and auxiliary grooves a' to C'. The magnetic fluctuation due to the wire groove changes gently.

Since the winding groove a-1 and the auxiliary grooves a' to C' have a phase difference of 1/15, the combined 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 phase, and winding grooves c, r, i,
j! are in the same phase, and the winding grooves e and h are in the same phase, so the composite magnetic fluctuation of the conventional motor shown in Fig. 1 is very large (in the conventional example shown in Fig. 1). Auxiliary groove a'
~C' is absent).

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
I B2 B3. B4. The effective pitch of CI, C2, C3C4 is from (1M 16/15 of 1 pole pitch) = 192 degrees (electrical angle) or less (415 of 1 magnetic pole pitch) -14
The angle is greater than 4 degrees (electrical angle). Here, the effective pitch of the winding is the angle formed between the centers of the winding grooves in which the winding is housed. Regarding the A-phase winding group, the angle between the winding grooves a and d in which A1 is wound is 144° (three short dentary bones).

The angle between the winding grooves d and g of A2 is 192° (
1 long tooth and 2 short dentary bones), the angle between the winding groove g-j of A3 is 192° (1 long tooth and 2 short dentary bones), The angle between the winding grooves j and a is 19
For the B phase winding group, which is 2 degrees (one long tooth and two short teeth), the angle between the winding grooves c and f in which Bl is wound is 192" (1 2 long teeth and 2 short dentaries), B2
The angle between the winding groove f and i of B3 is 192° (one long tooth and two short teeth), and the angle between the winding groove fi of B3 is 192° (one long tooth and two short teeth).
-2 angle is 144" (3 short dentary bones), and the angle between B4 winding groove 2-0 is 192° (1 long tooth and 2 short dentary bones) For the C-phase winding group, the angle between the CI winding grooves e and h is 144".
(3 short dentary bones), the angle between the wound winding groove h- of C2 is 192° (1 long tooth and 2 short dentary bones), C3
The angle between -b is 192" (one long tooth and two short teeth), and the angle between C4 and winding groove b is 192" (one long tooth and two short teeth).
The angle between -e is 192° (one long tooth and two short dentaries)
In this way, the fluctuation range of the winding groove in which the windings of each phase are housed is reduced (less than 1/3 of the pitch of one magnetic pole).
, and if the range of variation in the effective pitch of the winding is made small (from 192 degrees or less to 144 degrees or more), the winding work becomes easier and automation becomes 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 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. Also, the total effective pitch of the continuous short tooth block and long tooth block of 3m is set equal to (360@/P) ・Q, and the total number of teeth in one set of adjacent short tooth block and long tooth block is 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 shown in Figure 5 by 2 units of angle (1 unit angle is 360"/27-13.33°)
Table 6 shows that the effective pitch of the long teeth is 3 unit angles, auxiliary grooves are provided on the short teeth and long teeth, and the entire groove consisting of the winding groove and auxiliary groove is arranged at 1 unit angle intervals. The configuration of 1(B) is based on the effective pitch of the short teeth shown in Fig. 5 by 3 unit angles (1.
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 The configuration of Table 1 (C), which is arranged at 1 unit angle intervals, is the fifth
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 change 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. 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 long teeth and short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at 1 unit angular intervals. is set to 3 unit angles (1 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 winding groove and auxiliary groove are The entire grooves are arranged at 1 unit angular intervals.

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
'), set the effective pitch of the two long teeth to 2 unit angle and 3 unit angle, respectively, provide auxiliary grooves on the long teeth, and arrange the entire groove consisting of @ line groove and auxiliary groove at lj 1st angle interval. 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 unit angle and 5 unit angle, respectively, and auxiliary grooves are provided on the long tooth and short tooth,
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 number of magnetic poles 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, if the number of magnetic poles of the magnet 3 in the field section is set to P = 8, three-phase windings will be pattern-wound in T-3P = 24 winding grooves, but 7 Table 4 shows an example in which cogging torque is reduced by alternately arranging three sets of short tooth blocks consisting of short teeth and one long tooth block 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 (
One unit angle is 360°/27-13.33'), 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 seaming 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°/65-5.538"), the effective pitch of the long teeth is set to 3 unit angles, and auxiliary grooves are provided on the long teeth and short teeth to create a groove consisting of a winding groove and an auxiliary groove. In the configuration of Table 4 (C), in which the whole of
°/75-4.8'), the effective pitch of the long teeth is set to 4 units of angle, 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 unit. They are arranged at angular intervals.

In addition, when the number of magnetic poles of the magnet 3 in the field part is set to P-8, 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 was reduced.

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 auxiliary groove is arranged at 1 unit angle intervals. In the configuration of Table 5 (C), the effective pitch of the short teeth is set to 3 unit angles (1 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 P-4 embodiment and the P-8 embodiment, it is possible to configure an electric motor in which the number of M1 poles in the field section is P-12. Also, by simply doubling the configuration of the embodiment shown in FIG.
A motor with twice the number of magnetic poles and twice the number of winding grooves can be constructed.

Using a permanent magnet material, there is a field part having P-pole field magnetic poles at equiangular intervals (equal angular intervals or approximately equiangular intervals) on the circumference, and a 3-phase magnet in T winding grooves. In the case of a motor equipped with an armature core containing windings 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 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. 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 M1 magnetic poles at approximately equal angular intervals (equal angular intervals or approximately equal angular 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=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 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 three consecutive sets of short tooth blocks and long tooth blocks is (360”/P)
・When Q is equal to Q (where Q is an integer greater than or equal to 2), if the sum of the number of teeth in one set of adjacent short tooth blocks and the number of teeth in long tooth blocks is equal to Q, then a three-phase winding While maintaining the phase between the groups at 120 degrees (electrical angle), the phase of the winding groove can be easily varied, 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 pole pieces, 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~CI..., , auxiliary groove, At~A4. Bl-B4. C1-C4...
...Winding wire. Name of agent: Patent attorney Shigetaka Awano

Claims (4)

[Claims] (1) Using permanent magnetic material, P pole (however, P is 2
The field part includes a field part having field magnetic poles (the above even number) at equal angular intervals on the circumference, and an armature core in which 3 phase windings are housed in 3P winding grooves. A motor in which either one of the magnetic part and the armature core is rotatable relative to the other, the armature core having 3P teeth formed between the winding grooves, Effective pitch is D=120°
/L long teeth larger than P (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+M=3P L≧3 M≧3, each having a plurality of short tooth blocks consisting of two or more adjacent short teeth and a plurality of long tooth blocks consisting of at least one long tooth, each of the short teeth The number of the short teeth of the blocks is made equal, the number of the long teeth of each of the long tooth blocks is made equal, and the short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on a circumference, and adjacent 1
An electric motor in which the sum of the number of teeth of the short tooth block and the number of teeth of the long tooth block of the set is different from an integral multiple of three. (2) Using permanent magnetic material, P pole (however, P is 2
The field part includes a field part having field magnetic poles (the above even number) at equal angular intervals on the circumference, and an armature core in which 3 phase windings are housed in 3P winding grooves. A motor in which either one of the magnetic part and the armature core is rotatable relative to the other, the armature core having 3P teeth formed between the winding grooves, Effective pitch is D=120°
/L long teeth larger than P (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+M=T L≧3 M≧3, each having a plurality of short tooth blocks consisting of at least one short tooth and a plurality of long tooth blocks consisting of two or more adjacent long teeth, each of the short teeth The number of the short teeth of the blocks is made equal, the number of the long teeth of each of the long tooth blocks is made equal, and the short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on a circumference, and adjacent 1
An electric motor in which the sum of the number of teeth of the short tooth block and the number of teeth of the long tooth block of the set is different from an integral multiple of three. (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 that stores three-phase windings in 3P winding grooves, and a drive circuit that supplies three-phase currents to the three-phase windings as the rotor rotates, The armature core has 3P teeth formed between the winding grooves, L long teeth with an effective pitch larger than D=120°/P (L is an integer), and 3P teeth with an effective pitch larger than D=120°/P. It has M short teeth smaller than D (M is an integer), the number of the long teeth and the short teeth is L+M=3P L≧3 M≧3, and two or more adjacent short teeth and a plurality of long tooth blocks each consisting of at least one of the long teeth, the number of the short teeth of each of the short tooth blocks being equal, and the number of the long teeth of each of the long tooth blocks being equal. The short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on the circumference, and the adjacent one
An electric motor in which the sum of the number of teeth of the short tooth block and the number of teeth of the long tooth block of the set is different from an integral multiple of three. (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 that stores three-phase windings in 3P winding grooves, and a drive circuit that supplies three-phase currents to the three-phase windings as the rotor rotates, The armature core has 3P teeth formed between the winding grooves, L long teeth with an effective pitch larger than D=120°/P (L is an integer), and 3P teeth with an effective pitch larger than D=120°/P. It has M short teeth smaller than D (M is an integer), the number of the long teeth and the short teeth is L+M=T L≧3 M≧3, and consists of at least one short tooth. Each has a plurality of short tooth blocks and a plurality of long tooth blocks each consisting of two or more adjacent long teeth, the number of the short teeth of each of the short tooth blocks is equal, and the number of the long teeth of each of the long tooth blocks is equal. The short tooth blocks and the long tooth blocks are arranged alternately and symmetrically on the circumference, and the adjacent one
An electric motor in which the sum of the number of teeth of the short tooth block and the number of teeth of the long tooth block of the set is different from an integral multiple of three.