JPH02269444A - Motor - Google Patents

Abstract

PURPOSE:To obtain a motor of which the cogging torque is small by setting the ratio between the effective pitch of arbitrary short teeth and the effective pitch of arbitrary long teeth at about G:H (G, H are integers and G<H<=2G) and further by providing the long teeth with an auxiliary slot. CONSTITUTION:The effective pitch of short teeth a-b, b-c, c-d, e-f, f-g, g-h, i-j, j-k and k-l is set to be equal or substantially equal to 360 deg./(T+3)=24 deg.. The effective pitch of long teeth d-e, h-i and l-a is set to be equal or substantially equal to 720 deg./(T+3)=48 deg.. In other words, the ratio between the effective pitch of the short teeth and the effective pitch of the long teeth is set at R:R+1 (R=1). Besides, each long tooth is provided with one auxiliary slot, and the centers (centers in terms of a magnetic effect of operation) of all the slots of an armature core comprising slots for winding and the auxiliary slots are disposed at an equal angular interval (an interval of 360 deg./15=24 deg.) or at a substantially equal angular interval.

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 winding grooves 5 at equal angular intervals, 12 teeth 6 are formed between each winding groove, and 3-phase winding Al-A4 .81~B4. C1-C
0 winding At, A2 . A3. A4 is 3
One end of the windings A2 and A4 are respectively stored in both winding grooves in which the winding A1 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 At and A3 are housed in both winding grooves in which winding A4 is housed. Windings 81 to B4 of other phases. C1-C
The same applies to 4. Hereinafter, A1-A4 are collectively referred to as the A-phase winding group, 81 to B4 are 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.
”/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 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 an A-phase winding group. Similarly, windings 1i81 to B4 are connected in series considering each winding direction to form a B-phase winding group, and windings 01 to C4 are connected in series considering each winding direction to form a C-phase winding group. They form a group of lines. 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. sinusoidal signal P
I, 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 1 proportional to the product of both is input.
Outputs 1, 12, and 13. As a result, the interaction between the currents 11, 12, and 13 flowing to the A, B, and C phase winding groups and the magnetic flux of the magnet 3 generates 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 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. FIG. 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 a quantity related to the square of the magnetic flux density, the fundamental harmonic component of the magnetic period/waveform of the magnet 3 in the field part with the characteristics shown in Fig. 4 is the fourth harmonic. It becomes a wave 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 of the 8th order, 12th order, etc. based on the 4th order 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-2. Winding grooves a-1 of armature core 4 are at equal angular intervals (30 degree intervals)
Therefore, the fundamental harmonic component of the magnetic non-uniformity of the armature core 4 is the 12th harmonic 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 Next,
Harmonic components such as 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. As a result, this conventional electric motor generates a very large cogging torque.

The present applicant has devised a method for reducing such cogging torque in Japanese Patent Application No. 145489/1989. 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 with a winding groove. It is something to do.

Structure of the Invention In the present invention, a permanent magnet material is used to form a field part having Pli (where P is an even number of 2 or more) field magnetic poles at approximately equal angular intervals on the circumference, and a field part having T (however, , T is an integer of 6 or more), and an armature core in which three-phase windings are housed in winding grooves, 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 an effective pitch of D=360'/T.
It has L long teeth that are larger (L is an integer) and M short teeth whose effective pitch is smaller than D (M is an integer), and the number of the long teeth and the short teeth is L+M-. T L ≧ 3 M ≧ 3, a plurality of short tooth blocks each consisting of two or more adjacent short teeth and a plurality of long tooth blocks consisting of at least one long tooth, and the short tooth block and the above The long tooth blocks are arranged alternately on the circumference, and the ratio of the effective pitch of any of the short teeth to the effective pitch of any of the long teeth is G: H, (where G and H are integers. G<H≦2G
), and furthermore, by providing an auxiliary groove on at least the long tooth, the above object is achieved.

Further, in the present invention, a permanent magnet material is used to form a field part having Pi (where P is an even number of 2 or more) field magnetic poles at approximately equal angular intervals on the circumference, and a field part having T (however, an armature core in which three-phase tkvA is housed in a winding groove (T is an integer of 6 or more), and either one of the field part and the armature core is rotatable relative to the other. In this electric motor, the armature core has an effective pitch of D=360.
L long teeth larger than °/T (L is an integer),
It has M short teeth (however, M is an integer) whose effective pitch is smaller than D, the number of the long teeth and the short teeth is L + M = T L ≧ 3 M ≧ 3, and at least one of the above Short tooth pro ν consisting of short teeth
and a plurality of long tooth blocks each consisting of two or more adjacent long teeth, the short tooth blocks and the long tooth blocks are arranged alternately on the circumference, and any one of the short teeth By setting the ratio of the effective pitch to the effective pitch of any of the long teeth to be about G:H (where G and H are integers and G<H≦2G), and further providing an auxiliary groove on at least the long teeth, The above objectives have been achieved.

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 an armature core that stores three-phase windings in T winding grooves (T is an integer of 6 or more); and a drive circuit that supplies a current of short teeth (where M is an integer), the number of the long teeth and the short teeth is L + M = T L ≧ 3 M ≧ 3, and the short teeth are composed of two or more adjacent short teeth. a block and a plurality of long tooth blocks each consisting of at least one of the long teeth, the short tooth blocks and the long tooth blocks are arranged alternately on a circumference, and the effective pitch of any of the short teeth and the effective pitch ratio of any of the long teeth is G:H (where G, f( are integers and G<1 (≦2G)
The above object is achieved by providing an auxiliary groove on at least the long tooth.

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 T spaced apart (T is an integer of 6 or more)
an armature core that stores three-phase windings in a winding groove; and a drive circuit that supplies three-phase currents to the three-phase windings as the rotor rotates. The iron core has L long teeth (where L is an integer) with an effective pitch larger than D = 360°/T and M short teeth (where M is an integer) with an effective pitch smaller than D, The number of the long teeth and the short teeth is L + M = T L ≧ 3 M ≧ 3, and a short tooth block consisting of at least one short tooth and a long tooth block consisting of two or more adjacent long teeth. The short tooth blocks and the long tooth blocks are arranged alternately on the circumference, and the ratio of the effective pitch of any of the short teeth to the effective pitch of any of the long teeth is G:H. (However, G and H are integers of the order of G<H≦2G), and by providing an auxiliary groove at least on the long tooth, the above object is achieved.

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
It faces the 12 winding grooves a-f and the 12 teeth 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 winding 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 f, the winding B2 is wound from the winding groove f to i, and the winding B2 is wound from the winding groove l to 2. The wire B3 is wound and the winding groove l
Volume from to C! IB4 is wound, winding 81 to B4
are connected in series in consideration of the winding direction to form a third phase winding group. Further, the winding C1 is wound from the winding groove e to h, the winding C2 is wound from the winding groove k to the winding groove k, and the winding C2 is wound from the winding groove k to b. C3 is wound, a winding C4 is wound across the winding groove e, and the windings C1 to C4 are connected in series considering the winding direction to form a C-phase winding group. is formed. 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
-2 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 tooth is the angle formed by the center of the winding grooves at both ends of the tooth, and the number of winding grooves is T = 3 · P - 12 (P is the number of magnetic poles in the field part). 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 the teeth larger than D are lengthened. We will call them 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, and teeth d-e.
are long teeth, teeth e-f are short teeth, teeth r-g are short teeth, teeth gh are short teeth, teeth h-i are long teeth, teeth i-j are short teeth, tooth j- is short teeth. Tooth, Tooth-1 is a short tooth, and tooth E-a is a long tooth. That is, the number of long teeth is L=3, and the number of short teeth is M=9. Winding grooves a to d (a, b, c, d), winding grooves e to h (e, f, g, h), and winding groove i
Between 2 and 2 (i, j, k, ff1), only short teeth are partially concentrated, forming a short tooth block consisting of three short teeth (no long teeth included). Similarly,
Between the winding grooves d and e (d, e), between the winding grooves 1 and 1 (h, i), and between the winding grooves l and a (1°a), only the long teeth are part. are concentrated, forming a long tooth block consisting of one long tooth (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-gg-h, i-j, j k, k-
The effective pitch of 1 is equal to or approximately equal to 360°/(T+3)=24".Long teeth d-e, h
The effective pitch of -1,1-a is 720”/(T+3)
=48° or approximately equal to 48°. That is, 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@
The centers of the respective grooves (centers viewed from the perspective of N gas action and effect) are arranged at substantially 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 1 if pole pitch 360°/P of the magnet 3. Therefore, 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) with one magnetic pole pitch as the basic period, and reduce the amount of variation to -M. If so, the cogging torque will become 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 the lvA 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 of 1/(T+3)=1/15 of one magnetic pole pitch (the phases of winding grooves a, dg, and j differ in four or more places), and the variation range is one magnetic pole pitch. The pitch is 3/15 = 115 (less than 1/3 of the 1m pole pitch). Similarly, the winding grooves c, f, and il that accommodate the B-phase winding group are 1/1 of the pitch of one magnetic pole.
A phase shift is provided with a phase difference of 5, and the variation range is tv
The A-pole pitch is 115. Furthermore, winding grooves containing the C-phase winding group, e, h, k
A phase shift is provided with a phase difference of 1/15 of one magnetic pole pitch, and the variation range is set to 115 of one magnetic pole pitch.

The A-phase winding groove group (a, d, g, j), the B-phase winding groove group (c, r, i, z), and the C-phase winding groove group (b, e, h
, k), there is a phase difference of 1/3 of l magnetic pole pitch. Further, the auxiliary grooves a' to C' are located in a phase different from the phase of the winding groove a-1, and the entire groove consisting of the winding groove a-1 and the auxiliary grooves a' to C' is l/ The phases are all different with a phase difference of 15. Figure 7 shows the waveform of the magnetic fluctuation of the TI machine core 4 due to the winding groove a-2 and the auxiliary grooves a to C''. The magnetic fluctuation changes smoothly.Winding groove a
= 1 and the auxiliary grooves a' to C' have a phase difference of 1/15, so the composite magnetic fluctuation (AC bone) is quite small. FIG. 8 shows magnetic fluctuations of the conventional electric motor shown in FIG. The winding grooves a, d, g, and j are in the same phase, and the winding grooves c, r, t, and j! are in the same phase, and the winding grooves e, h, and k are in the same phase, so the composite magnetic fluctuation of the conventional motor in Fig. 1 is very large (in the conventional example in Fig. 1, There are no 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
1. B2. B3. B4. The effective pitch of CI, C2, C3°C4 is from (16/15 of 1 magnetic pole pitch) = 192 degrees (electrical angle) or less to (415 of 1 magnetic pole pitch) = 144 degrees (
electric angle) or more. Here, the effective pitch of the winding is its f! This is the angle formed between the centers of the winding grooves in which the wires are stored. Looking at the winding group of the physiognomy, the angle between A1's winding grooves a and d is 144° (3 short dentaries), and the angle between A2's winding grooves d and d is 144° (3 short dentaries). The angle between g 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), Looking at the winding group of phase B, where the angle between the winding groove j and a of A4 is 192° (one long tooth and two short teeth), the winding of B1 Winding groove c-
The angle between f is 192' (one long tooth and two short teeth),
The angle between the winding groove r-1 of B2 is 192' (
1 long tooth and 2 short dentaries), the angle between the winding groove i-1 for B3 is 144" (3 short dentaries), the winding for B4 is The angle between the winding grooves 1-c is 192° (one long tooth and two short teeth).If we look at the C phase winding group, the winding groove e- The angle between h is 14
4° (3 short dentaries), C2 wound winding groove h-
The angle between the two is 192” (one long tooth and two short teeth),
The angle between -b and the groove for winding C3 is 192° (
1 long tooth and 2 short dentary bones), the angle between C4's winding groove be is 192' (1 long tooth and 2 short dentary bones), In this way, if the range of variation of the winding groove in which the windings of each phase are housed is reduced (to 1/3 or less of the II pole pitch), and the range of variation of the effective pitch of the winding is reduced. (from 192 degrees or less to 144 degrees or more), 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 r , and cl are eliminated, the resultant 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 a pair of adjacent short tooth blocks and long tooth blocks is different from a multiple of three, the phase of the teeth can be easily varied. Also, 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 made equal to Q, the phase difference between the three-phase winding groups can be made equal to 120 degrees (1 air 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 made thicker (possible. Furthermore, the effective pitch of the short teeth and the effective pitch of the long teeth can be set to R:R+1 or R:R+3 (R is an integer), and the electric machine consisting of the winding groove and the auxiliary groove can be Cogging torque can be easily reduced by arranging the entire grooves of the child core at intervals of 1/R of the effective pitch of the short teeth.Table 1 shows other examples of such a configuration.

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/degree (1 unit angle is 360°/27-13.33°).
) 5 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.1 Table 1 (B)
In this configuration, the effective pitch of the short teeth in Fig. 5 is set 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.

(Margins below) Table 2 The configuration in Table 2 (A) consists of a long tooth block consisting of three long teeth and a short tooth block consisting of one short tooth arranged alternately on the circumference. (Exchange the number of short teeth and long teeth in Figure 5)
, the effective pitch of the short teeth is 1 unit angle (l unit angle 36
0"/21-17.14") K Niji, 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 spaced at 1 unit angle intervals. In the configuration shown in Table 2 (B), the effective pitch of the short teeth is 2 units of angle (1 unit of 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 grooves consisting of the winding groove and the auxiliary groove are arranged at one unit angle intervals.

In the configuration shown in Table 2 (C), the effective pitch of the short teeth is set to 3 unit angles (1 unit angle is 360''/33-10.91°), and the effective pitch of the long teeth is set to 4 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 angle intervals.

Further, 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 pitches of the two long teeth are 2 and 3 unit angles, 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 intervals. 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°/4
5=8@), and the effective pitch of the two long teeth is 4 each.
A unit angle and a 5 unit angle are provided, auxiliary grooves are provided on the long teeth and short teeth, and the entire grooves consisting of the winding groove and the auxiliary groove are arranged at intervals of 1 unit angle.

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. 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 in Table 4 (A) is based on the effective pitch of the short teeth by one unit angle (
1 unit angle is 360'/27=13.33'''),
The effective pinch 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 grooves 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 H 360' / 65 = 5.538' H
: 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 angle intervals. , Table 4(C)
The configuration is such that the effective pitch of the short teeth is 3 unit angles (1 unit angle is 360°/75 = 4.8°), the effective pinch of the long teeth is 4 unit angles, and auxiliary grooves are provided on the long teeth and short teeth. The entire groove consisting of the winding groove and the auxiliary groove is arranged at one unit angle interval.

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 (
1 unit angle is 360'/45=8°), the effective pitch of the long teeth is 2 units of angle, and auxiliary grooves are provided on the long teeth.
In the configuration shown in Table 5 (B), in which the entire grooves consisting of the winding groove and the auxiliary groove are arranged at 1 unit angle intervals, the effective pitch of the short teeth is 2 unit angles (1 unit angle is 360'/ 69=5
゜217'), the effective pitch of the long teeth was set to 3 unit angles, auxiliary grooves were provided on the long teeth and short teeth, and the entire groove consisting of the winding groove and the auxiliary groove was arranged at 1 unit angle intervals. The configuration of Table 5 (C) is such that the effective pitch of the short teeth is 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 in order of unit angles.

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, 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'/T
It has L (however, 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),
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 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 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.

Furthermore, the field section is not limited to an annular magnet, and the field section may be composed of a plurality of magnet if 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, 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'~cr,..., auxiliary groove, Al~A4. Bl~B4. C1~C4...
...winding wire. Name of agent: Patent attorney Shigetaka Awano

Claims (12)

[Claims] (1) Using permanent magnetic material, P pole (however, P is 2
A field part has field magnetic poles (an even number above) at equal angular intervals on the circumference, and three-phase windings are housed in T (however, T is an integer of 6 or more) winding grooves. Equipped with an armature core,
The electric motor is such that one of the field part and the armature core is rotatable relative to the other, and the armature core has L pieces (with an effective pitch larger than D=360°/T). However, it has long teeth (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, and each has 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, and the short tooth blocks and the long tooth blocks are arranged in a circle. They are arranged alternately on the circumference, and the ratio of the effective pitch of any of the short teeth to the effective pitch of any of the long teeth is approximately G:H (where G and H are integers and G<H≦2G). , an electric motor in which at least the long teeth are provided with auxiliary grooves. (2) The electric motor according to claim (1), characterized in that G:H=R:R+1 (where R is an integer). (3) The electric motor according to claim (2), characterized in that R=1 and one auxiliary groove is provided in the center of each long tooth. (4) Using permanent magnetic material, P pole (however, P is 2
A field part has field magnetic poles (an even number above) at equal angular intervals on the circumference, and three-phase windings are housed in T (however, T is an integer of 6 or more) winding grooves. Equipped with an armature core,
The electric motor is such that one of the field part and the armature core is rotatable relative to the other, and the armature core has L pieces (with an effective pitch larger than D=360°/T). However, it has long teeth (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, and each has 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, and the short tooth block and the long tooth block are arranged in a circle. They are arranged alternately on the circumference, and the ratio of the effective pitch of any of the short teeth to the effective pitch of any of the long teeth is approximately G:H (where G and H are integers and G<H≦2G). , an electric motor in which at least the long teeth are provided with auxiliary grooves. (5) The electric motor according to claim (4), characterized in that G:H=R:R+1 (where R is an integer). (6) The electric motor according to claim (5), characterized in that R=1 and one auxiliary groove is provided in the center of each long tooth. (7) A rotor forming 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 that is provided with a predetermined gap from the permanent magnet magnetic poles. , an armature core that stores three-phase windings in T (T is an integer of 6 or more) winding grooves, and a three-phase current flowing through the three-phase windings as the rotor rotates. the armature core has an effective pitch of 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+M=T L≧3 M≧3, and two or more adjacent teeth It has a plurality of short tooth blocks each consisting of the short teeth and a plurality of long tooth blocks consisting of at least one long tooth, the short tooth blocks and the long tooth blocks are arranged alternately on the circumference, and any The ratio of the effective pitch of the short teeth to the effective pitch of any of the long teeth is set to about G:H (where G, H are integers and G<H≦2G), and at least the long teeth are provided with auxiliary grooves. Electric motor. (8) The electric motor according to claim (7), characterized in that G:H=R:R+1 (where R is an integer). (9) The electric motor according to claim (8), characterized in that R=1 and one auxiliary groove is provided at the center of each long tooth. (10) 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. , 3 in T (T is an integer of 6 or more) winding grooves.
The armature core includes an armature core that accommodates phase windings, and a drive circuit that supplies three-phase currents to the three-phase windings as the rotor rotates, and the armature core has an effective pitch of 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+M=T L≧3 M≧3, and a short tooth block consisting of at least one short tooth and two or more adjacent long teeth. Each has a plurality of long tooth blocks each consisting of teeth, the short tooth blocks and the long tooth blocks are arranged alternately on the circumference, and the effective pitch of any of the short teeth and the effective pitch of any of the long teeth are An electric motor having a pitch ratio of approximately G:H (where G and H are integers and G<H≦2G), and at least the long teeth are provided with auxiliary grooves. (11) The electric motor according to claim (10), characterized in that G:H=R:R+1 (where R is an integer). (12) The electric motor according to claim (11), characterized in that R=1 and one auxiliary groove is provided in the center of each long tooth.