JPH0685628B2 - Electric motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor provided with an armature core having winding grooves that are larger in number than the number of magnetic poles in a field unit.

Configuration of conventional example and its problems An electric motor in which a winding groove is provided in an armature core to accommodate a multi-phase winding, the magnetic flux of the field part is formed in the teeth formed between the winding grooves. Has the advantage that the output is large. Therefore, industrial robots and
Widely used as a driving power source for NC equipment. However, in such an electric motor, cogging torque is generated by the interaction between the magnetic poles of the field magnet and the winding grooves of the armature core. This will be described below with reference to the drawings.

FIG. 1 is a main part configuration diagram showing a structure of a conventional electric motor. An annular magnet 3 is attached to the outer circumference of a ferromagnetic rotor 2 attached to the rotating shaft 1. The magnet 3 is magnetized with four magnetic poles at equal angular intervals to form a field portion. An armature core 4 is arranged at a predetermined distance from the magnet 3 of the field unit. One of the magnet 3 and the armature core 4 is rotatably supported with respect to the other (in the present example, the armature core 4
In contrast, the magnet 3 is designed to rotate). The armature core 4 is provided with 24 winding grooves 5 at equal angular intervals, 24 teeth 6 are formed between the winding grooves, and three-phase windings A1 to A4 are provided. , B1 to B4, C1 to C4 are wound. The windings A1, A2, A3, A4 are wound so as to surround five teeth, and the winding A2 is placed in the winding groove next to both winding grooves in which the winding A1 is housed. One end of A4 is stored. Similarly, one end of each of the windings A1 and A3 is housed in the winding groove next to both winding grooves in which the winding A2 is housed,
The winding grooves of both winding grooves in which winding A3 is housed have one ends of windings A2 and A4, respectively, and the winding next to both winding grooves in which winding A4 is housed. Windings A1 and A3 respectively
One end of is stored. Windings of other phases B1 to B4, C1 to C4
Is also the same. Hereinafter, A1 to A4 are collectively referred to as an A phase winding group, B1 to B4 are referred to as a B phase winding group, and C1 to C4 are referred to as a C phase winding group. The magnetic flux generated by the magnet 3 in the field unit flows into or out of each tooth of the armature core 4, and is linked to the winding groups of A, B, and C phases. There is an electrical phase difference of 120 degrees between the A, B and C phase winding groups. Here, the electrical angle of 180 degrees corresponds to one magnetic pole pitch of 360 degrees / P (P is the number of magnetic poles of the field section) in the field section (in this example, P = 4, so the mechanical angle of 90 degrees is 1). Magnetic pole pitch, which corresponds to an electrical angle of 180 degrees).

FIG. 2 shows a configuration diagram of the drive circuit. Windings A1 to A4 in Fig. 1
Are connected in series in consideration of each winding direction to form an A-phase winding group. Similarly, the windings B1 to B4 are connected in series in consideration of the respective winding directions to form a B-phase winding group, and the winding C1
C4 are connected in series in consideration of each winding direction to form a C-phase winding group. The three-phase winding group is star-connected, and its terminals are connected to the drive unit 11. The position detector 12 detects the rotational position of the magnet 3 and outputs three-phase sinusoidal signals Pa, Pb, Pc that change with the rotation of the magnet 3. The command signal F and the three-phase signals Pa, Pb, Pc of the position detection unit 12 are input to the drive unit 11, and three-phase sinusoidal currents Ia, Ib, Ic proportional to the product of both are output. As a result, A, B, C
Rotational force is generated in a predetermined direction by interaction with the phase winding group.

Next, the cogging torque of this conventional example will be described with reference to FIG. FIG. 3 is a plan development view of the magnet 3 and the armature core 4 of FIG. 1 taken along the line XX and the line YY. (The winding is omitted and the winding grooves are indicated by a to x). The 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 between the two. In particular, it occurs in relation to both the magnetic poles of the field part and the grooves of the armature core,
As shown in FIG. 1, when both the magnet 3 of the field magnet section and the armature core 4 have a magnetic periodicity, a cogging torque of a component (matching component) commonly present in both of them is generated. FIG. 4 shows the distribution characteristics of the magnetic flux density generated by the magnet 3 over the entire circumference (360 degrees). Since the 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 of the magnetic field portion having the characteristic shown in FIG. 4 is the 4th harmonic. It becomes an ingredient. Here, the sine wave component of one rotation once is the first harmonic component. That is, the magnet 3 contains harmonic components such as the 8th, 12th, ... Based on the 4th component.

On the other hand, the magnetic nonuniformity (the amount related to permeance) of the armature core 4 is caused by the winding grooves a to x. Since the winding grooves a to x of the armature core 4 are arranged at equal angular intervals (15 degrees), the fundamental harmonic component of the magnetic nonuniformity of the armature core 4 is the 24th component. Become. Therefore, based on this, harmonic components of the 48th order, the 72nd order, ... Are included. Since the cogging torque is generated when the magnetic nonuniformity component of the armature core 4 and the harmonic component of the period / waveform of the magnet 3 are matched (matched), the cogging torque of this conventional example is the 24th. Harmonic components of the next, the 48th, etc. occur.

The 24th-order component of the cogging torque is related to the basic component of the magnetic nonuniformity of the armature core 4 caused by the 24 winding grooves. Generally, the fundamental component of the armature core 4 is considerably larger than the other harmonic components. As a result, a very large cogging torque is generated in this conventional electric motor.

The present applicant has proposed a method of reducing such cogging torque in Japanese Patent Laid-Open No. 55-71163. JP 55
In Japanese Patent No. 71163, the auxiliary groove is provided at the wave portion of the armature core to increase the basic harmonic component of the cogging torque and reduce the cogging torque. However, in order to sufficiently reduce the cogging torque by such a method, the fundamental order of the cogging torque needs to be set to a considerably high order, and many auxiliary grooves must be provided in the armature core, which is not practical. Not. Further, even when a large number of auxiliary grooves are provided, the basic component of the cogging torque matches the basic component of the armature core, so that the cogging torque cannot be reduced sufficiently.

SUMMARY OF THE INVENTION In consideration of the above points, the present invention significantly reduces the cogging torque in an electric motor in which the number of winding grooves of the armature core is larger than the number of magnetic poles of the field magnet portion.

Structure of the Invention In the present invention, a field portion having permanent magnet magnetic poles of P poles (where P is an integer of 4 or more) on the circumference at predetermined angular intervals, and a predetermined gap from the permanent magnet magnetic poles are provided. A field magnet portion and an armature core having 6P winding grooves around which three-phase windings are wound and teeth formed between the winding grooves. One of the teeth is an electric motor rotatable with respect to the other, and the effective pitch of each tooth of the armature core is an angle formed by the centers of the winding grooves at both ends of each tooth. At this time, the armature core has N equal teeth (where N is an integer of 4 or more) whose effective pitch is equal to D = 60 ° / P and L whose effective pitch is greater than D (here, L Is an integer of 2 or more) and M short teeth with an effective pitch smaller than D (where M is an integer of 2 or more), and , When the arrangement of teeth of the armature core is blocked in a predetermined direction, starting from the long teeth and ending with the constant teeth, at least two of the long teeth and at least two of the constant teeth are partially adjacent to each other. Concentrated long pitch blocks and starting from the short teeth and ending at the equal teeth,
Short pitch blocks in which at least two short teeth and at least two equal teeth are partially adjacent and concentrated are alternately arranged on the circumference, and further, between the long teeth and the long teeth. At least one of the equal teeth is arranged in the, and at least one of the equal teeth is arranged between the short tooth and the short tooth,
The above object is achieved by disposing at least one equal tooth between the long tooth and the short tooth.

Description of Embodiments FIG. 5 is a developed plan view of a main part of an embodiment of the present invention. In FIG. 5, the magnet 3 attached to the rotor 2 has four magnetic poles arranged at equal angular intervals.
24 winding grooves a to x and 24 teeth facing each other at a predetermined interval. In the 24 winding grooves of the armature core 4,
A winding group of three layers is wound in the same manner as the winding group of A, B, and C phases in FIG. 1 (illustration is omitted). That is, the winding groove a
To f, the winding A1 is wound, the winding groove g is wound over 1, the winding A2 is wound, the winding groove m is passed over r, and the winding A3 is wound. A winding A4 is wound from the wire groove s to x, and the windings A1 to A4 are connected in series in consideration of the winding direction to form a phase A winding group. Similarly, the winding B1 is wound over the winding grooves e to j, the winding B2 is wound over the winding grooves k to p, and the winding B is wound over the winding grooves q to v. The wire B3 is wound, and the wire B4 is wound across the winding groove w to d.
Is wound 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 C1 is wound from the winding grooves i to n, the winding C2 is wound from the winding grooves o to t, and the winding grooves u to b.
The winding C3 is wound around the winding C3, the winding C4 is wound around the winding groove c to h, and the windings C1 to C4 are connected in series in consideration of the winding direction to form the C-th winding. Forming a phase winding group. The drive circuit of this embodiment has the same configuration as that of FIG.

In the embodiment shown in FIG. 5, the winding groove a of the armature core 4 is used.
The arrangement of ~ x is arranged at unequal angular intervals, and the effective pitch of the teeth formed between the winding grooves is made nonuniform. Here, the effective pitch of the teeth is the angle formed by the centers of the winding grooves at both ends of the teeth. When the number of winding grooves is T = 6 · P = 24 (P is the number of magnetic poles in the magnetic field part and P = 4), the effective pitch of each tooth is D = 60 ° / P when they are arranged at equal angular intervals. Since the effective pitch of the teeth is equal to D = 15 °, teeth having an effective tooth pitch equal to D are called equal teeth, teeth larger than D are called long teeth, and teeth smaller than D are called short teeth. In FIG. 5, equal teeth are indicated by E, long teeth are indicated by R, and short teeth are indicated by Z. The tooth a-b (representing the tooth by the winding grooves at both ends) is a constant tooth (E), the tooth bc is a long tooth (R), the tooth cd is a constant tooth (E), and the tooth d-e is a tooth. Equal tooth (E), tooth e-f is long tooth (R), tooth f-g is equal tooth (E), tooth g-h is equal tooth (E), tooth h-j is long tooth (R), The tooth i-j is a constant tooth (E), the tooth j-k is a constant tooth (E), the tooth kl is a constant tooth (E), the tooth 1-m is a constant tooth (E), the tooth m-n is a constant tooth (E). Tooth (E), tooth n-o is a short tooth (Z), tooth op is a constant tooth (E), tooth pq is a constant tooth (E), tooth qr is a short tooth (Z), a tooth. r-s is a constant tooth (E), tooth s-t is a constant tooth (E), tu is a short tooth (Z),
The tooth u-v is a tooth (E), the tooth v-w is a tooth (E), the tooth w-.
x is a constant tooth (E) and tooth xa is a constant tooth (E). That is, the number of equal teeth is N = 18, the number of long teeth is L = 3, and the number of short teeth is M = 3. The effective pitch of the long teeth b-c, e-f, h-i is made equal to D. (1 + 1 / P) = 5.D / 4. The effective pitch of the short teeth n−o, q−r, t−u is D · (1−
1 / P) = 3 · D / 4. When the tooth arrangement of the armature core 4 is blocked in a predetermined direction, the winding groove b
Between n and n (b, c, d, e, f, g, h, i, j, k, l, m, n) start with long teeth and end with equitooth, only long teeth and equitooth Are concentrated intensively and form a long pitch block including three long teeth (not including short teeth). Similarly, between the winding grooves n and b (n, o, p, q, r, s, t, u, v, w, x, a, b) start with short teeth and end with equitooth, Only the short teeth and the equal teeth are partially concentrated, forming a short pitch block including three short teeth (not including long teeth). Regarding the boundary between the long pitch block and the short pitch block, an equitooth that follows the long tooth is included in the long pitch block when viewed from a predetermined direction, and an equitooth that follows the short tooth is included in the short pitch block. Further, since the long pitch block does not include short teeth and the short pitch block does not include long teeth, the long pitch block and the short pitch block can be clearly distinguished. If the number of teeth in the long pitch block is equal to the number of teeth in the short pitch block, the angle formed by the long pitch block is larger than the angle formed by the short pitch block. Long pitch block am in FIG.
Is 9 ・ D + 15 ・ D / 4 = 51 ・ D / 4 = 191.25 ° and short pitch block ma is 9 ・ D + 9 ・ D / 4 = 45 ・ D / 4 = 168.75
It is ゜.

Next, the cogging torque of this embodiment will be described. As described above, cogging torque occurs when the harmonic component of magnetic non-uniformity due to the winding groove of the armature core and the magnetic period / waveform harmonic component due to the magnetic poles of the field part match. . The magnetic period / waveform of the magnet 3 in the field part is a periodic function having a period of one magnetic pole pitch of the magnet 3 of 360 ° / P. Therefore, it is sufficient to consider the magnetic nonuniformity of the armature core 4 (the magnetic variation caused by the arrangement of the winding grooves) with one magnetic pole pitch of the magnet 3 as the basic period, and generally, the variation amount is reduced. Then, the cogging torque becomes smaller. FIG. 6 shows a phase relationship when the winding grooves a to x of the armature core 4 are viewed with one magnetic pole pitch of the magnet 3 as a basic cycle. Winding grooves a, f, g, l, m, r, s, x that house the A-phase winding group are 1/24 of one magnetic pole pitch.
A phase shift is provided by the minimum phase difference of (the winding grooves a, f, g,
l, m, r, s, x differ from six or more), and the variation range is 7/24 of one magnetic pole pitch (1/3 or less of one magnetic pole pitch). Similarly, winding grooves d, e, which house the B-phase winding group,
The j, k, p, q, v, and w are provided with a phase shift with a minimum phase difference of 1/24 of one magnetic pole pitch, and the variation range is set to 7/24 of one magnetic pole pitch. Furthermore, the winding grooves b, c, h, i, n, o, t, u accommodating the C-phase winding group are provided with a phase shift with a minimum phase difference of 1/24 of one magnetic pole pitch, The range of variation is 7/24 of one magnetic pole pitch. In addition, A phase winding groove (a, f, g,
l, m, r, s, x) and B phase winding groove (d, e, j, k, p, q, v, w) and C
1 between each phase winding groove (b, c, h, i, n, o, t, u)
There is a phase difference of 1/3 of the magnetic pole pitch. Fig. 7 shows winding groove a
3 shows waveforms of magnetic fluctuations of the armature core 4 due to x.
Depending on the opening of the winding groove, the amount of magnetic fluctuation due to each winding groove changes gently. Since the winding grooves a to x have different phases by 1/24, the combined magnetic fluctuation (AC) is considerably small. FIG. 8 shows the first
The magnetic variation of the conventional electric motor of the figure is shown. Winding groove a,
g, m, s have the same phase, winding grooves b, h, n, t have the same phase, winding grooves c, i, o, u have the same phase, and winding grooves d, j, p, v
Has the same phase, the winding grooves e, k, q, w have the same phase, and the winding grooves f, l, r, x have the same phase, so the combined magnetic field of the conventional motor shown in FIG. The fluctuation amount is very large. Comparing FIG. 7 and FIG. 8, it can be seen that the magnetic variation of the electric motor of this embodiment is significantly reduced. As a result, the cogging torque of this embodiment is greatly reduced.

Furthermore, each winding A1, A2, A3, A4, B1, B2, B3, B4, C of this embodiment
The effective pitch of 1, C2, C3, C4 is (11/12 of one magnetic pole pitch) = 1
From 65 degrees (electrical angle) or less (9/12 of one magnetic pole pitch) = 135
The angle is above the electrical angle. Here, the effective pitch of the winding is the angle formed by the centers of the winding grooves in which the winding is housed. For example, in the case of the A-phase winding group, the angle between the winding grooves af with respect to A1 is 165 ° (three equal teeth and two long teeth), and the winding groove g− with respect to A2 is − The angle between l is
157.5 ° (4 equal teeth and 1 long tooth), the angle between winding grooves mr for A3 is 135 ° (3 equal teeth and 2 short teeth), winding for A4 The angle between the line grooves s-x is 142.5 ° (4 equal teeth and 1 short tooth). Similarly, for other B-phase and C-phase winding groups, the winding angle is 165 degrees or less to 135 degrees or more. In this way, if the variation range of the winding groove accommodating the windings of each phase is reduced (1/3 or less of one magnetic pole pitch) and the variation range of the effective pitch of the winding is reduced (165 From less than 135 degrees to more than 135 degrees), winding work becomes easier and automation is possible.

Further, in the present embodiment, the effective pitch of the long teeth D · (1 + 1 /
P) = 5 · D / 4 is very close to the effective pitch D of the constant tooth, and the effective pitch D of the short tooth is D · (1-1 / P) = 3 · D / 4 is the effective pitch D of the constant tooth. Very small. Therefore, there is also an advantage that long and short teeth can be easily formed on the armature core.

Further, since the equal teeth are arranged between the adjacent long teeth in the long pitch block and the equal teeth are arranged between the adjacent short teeth in the short pitch block, the winding storage space is made uniform. It will be easy.

9 (a), (b), (c) and (d) show another embodiment of the present invention. FIG. 9 (a) shows the arrangement of the winding grooves (the arrangement of teeth) in the configuration of FIG.
The teeth e-f, f-g, g-h are long teeth, the teeth m-n, r-s, w-x are short teeth, and the other teeth are equal teeth. The effective pitch of the constant teeth, the long teeth and the short teeth is the same as that of the embodiment shown in FIG.

FIG. 9 (b) shows a configuration in which the arrangement of the winding grooves (the arrangement of the teeth) in the configuration of FIG. 5 is changed, and the teeth b-c, c-d, h-
i is a long tooth, teeth n-o, op-tu, and tu are short teeth, and the other teeth are equal teeth. The effective pitch of the constant teeth, the long teeth and the short teeth is the same as that of the embodiment shown in FIG.

FIG. 9 (c) is a view in which the arrangement of the winding grooves (teeth arrangement) in the configuration of FIG. 5 is changed, and two teeth fg and l-m are long teeth, and Two of r-s and x-a are short teeth, and the other teeth are equal teeth. The effective pitch of the long teeth f-g is D · (1 + 2 / P) = 6 · D / 4 (6 / of the effective pitch D of equal teeth)
4), and the effective pitch of the long tooth 1-m is D · (1 + 1 / P)
= 5 · D / 4, and the effective pitch of the short teeth r−s is D · (1
−2 / P) = 2 · D / 4, and the effective pitch of the short teeth x−a is D
・ (1-1 / P) = 3 ・ D / 4. In this way, the cogging torque can be reduced also by disposing the long pitch block including two long teeth and the short pitch block including two short teeth.

FIG. 9 (d) is a view in which the arrangement of the winding grooves (the arrangement of teeth) in the configuration of FIG. 5 is changed, and two teeth fg and hi are long teeth, and Three of n-o, r-s, and x-a are short teeth, and the other teeth are equal teeth. The effective pitch of the long tooth f−g is D · (1 + 2 / P) = 6 · D / 4 (6/4 of the effective pitch D of the constant tooth), and the effective pitch of the long tooth hi is D · (1
+ 1 / P) = 5 · D / 4, and the effective pitch of the short teeth n−o, r−s, x−a is D · (1-1 / P) = 3 · D / 4. Thus, the cogging torque can also be reduced by disposing the long pitch block including two long teeth and the short pitch block including three short teeth.

Although the number of magnetic poles of the magnet 3 of the field magnet portion is P = 4 in each of the above-described embodiments, the present invention is not limited to such a case.

FIG. 10 is a plan development view of the essential parts showing another embodiment of the present invention. In FIG. 10, the magnet 3 attached to the rotor 2 has 6 magnetic poles at equal angular intervals, and the 36 winding grooves a to j ′ of the armature core 4 and the 36 teeth have predetermined intervals. Open and face each other. The 36 winding grooves of the armature core 4 are wound with a three-layer winding group consisting of A, B, and C phase winding groups (not shown). That is, the winding A1 is wound from the winding grooves a to f, the winding A2 is wound from the winding grooves g to l, and the winding A is wound from the winding grooves m to r. A3
Is wound, the winding A4 is wound from the winding groove s to x, the winding A5 is wound from the winding groove y to d ', and the winding groove e'to j The winding A6 is wound across the ‘
.. A6 are connected in series in consideration of the winding direction to form a phase A winding group. Similarly, the winding B1 is wound over the winding grooves e to j, the winding B2 is wound over the winding grooves k to p, and the winding B is wound over the winding grooves q to v. The wire B3 is wound, the winding B4 is wound from the winding groove w to b ', and the winding B5 is wound from the winding groove c'to h'.
The winding B6 is wound from the winding groove i'to the winding groove d, and the winding B1
B6 are connected in series in consideration of the winding direction to form a B-phase winding group. Further, the winding C1 is wound over the winding grooves i to n, and C2 is wound over the winding grooves o to t.
Is wound, the winding C3 is wound over the winding grooves u to z, and the winding C4 is wound over the winding grooves a ′ to f ′.
The winding C5 is wound over the winding grooves g ′ to b, the winding C6 is wound over the winding grooves c to h, and the windings C1 to C6 are taken into consideration in the winding direction. Are connected in series to form a C-th phase winding group. The drive circuit of this embodiment has the same configuration as that of FIG.

In the embodiment shown in FIG. 10, the winding groove a of the armature core 4 is used.
The arrangement of ~ j 'is arranged at unequal angular intervals to make the effective pitch of the teeth formed between the winding grooves non-uniform. The effective pitch of the constant teeth is D = 60 ° / P = 10 ° (where P is the number of magnetic poles in the field part, P = 6), and the effective pitch of the long teeth is larger than D, Has an effective pitch smaller than D. Tooth a
-B is a constant tooth (E), tooth b-c is a long tooth (R), tooth cd is a constant tooth (E), tooth d-e is a constant tooth (E), tooth ef is a long tooth (E). R), the tooth f-g is a constant tooth (E), the tooth g-h is a constant tooth (E), the tooth h-j is a long tooth (R), the tooth i-j is a constant tooth (E), the tooth j-. k is a constant tooth (E), tooth kl is a long tooth (R), tooth 1-m is a constant tooth (E), tooth mn is a constant tooth (E), tooth n-o is a long tooth (R). ), The tooth op is a tooth (E), the tooth pq is a tooth (E), the tooth qr is a tooth (E), the tooth r-s is a tooth (E), and the tooth st. Is a tooth (E), tooth t-u is a short tooth (Z), tooth u-v is a tooth (E), tooth v-w is a tooth (E), tooth w-x is a tooth (Z). , Tooth x-y is a constant tooth (E), tooth yz is a constant tooth (E), z-a 'is a short tooth (Z), tooth a'-b' is a constant tooth (E), tooth b '. -C 'is a constant tooth (E), tooth c'-d' is a short tooth (Z), and tooth d'-e 'is a constant tooth (E). ), Teeth e'-f 'is equal teeth (E), the teeth f'-g' is Tanha (Z), the teeth g '-h'
Is a tooth (E), tooth h'-i 'is a tooth (E), tooth i'-
j ′ is a constant tooth (E), and tooth j′-a is a constant tooth (E). That is, the number of equal teeth is N = 26, the number of long teeth is L = 5, and the number of short teeth is M = 5. Long tooth bc, ef, h-i, k-l, n
The effective pitch of −o is made equal to D · (1 + 1 / P) = 7 · D / 6. Short teeth t-u, w-x, z-a ', c'-d',
The effective pitch of f'-g 'is D · (1-1 / P) = 5 · D / 6
Is made equal to. Between winding grooves b to t (b, c, d,
e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t) start from the long tooth and end with the equitooth, and only the long tooth and the equitooth Partially concentrated, forming a long pitch block containing 5 long teeth (not including short teeth). Similarly, between the winding grooves t and b (t, u, v, w, x, y, z, a ', b', c ', e', f ', g', h ', i' ,
j ′, a, b) starts from the short tooth and ends with the equitooth, and only the short tooth and the equitooth are partially concentrated to form a short pitch block including five short teeth (long tooth). Not included).

Next, the cogging torque of this embodiment will be described. FIG. 11 shows the phase relationship when the winding grooves a to j ′ of the armature core 4 are viewed with the basic pitch of one magnetic pole pitch of the magnet 3 of 360 ° / P. Winding grooves a, f, which house the A-phase winding group
g, l, m, r, s, x, y, d ′, e ′, j ′ are phase-shifted with a minimum phase difference of 1/36 of the magnetic pole pitch (winding grooves a, f, g, l, m, r, s,
The phases of x, y, d ', e', and j'are all different), and the variation range is 11/36 (1/3 or less) of one magnetic pole pitch.
Similarly, the winding grooves d, e, j, k, p, which house the B-phase winding group,
q, v, w, b ', c', h ', i' are provided with a phase shift with a minimum phase difference of 1/36 of one magnetic pole pitch, and the variation range is set to 11/36 of one magnetic pole pitch. There is. Further, the winding grooves b, c, h, i, n, o, t, u, z, a ′, f ′, g ′ for accommodating the C-phase winding group are 1
A phase shift is provided with a minimum phase difference of 1/36 of the magnetic pole pitch,
The fluctuation range is 11/36 of one magnetic pole pitch.
A-phase winding groove group (a, f, g, l, m, r, s, x, y, d ′, e ′,
j ') and B-phase winding groove groups (d, e, j, k, p, q, v, w, b', c ',
h ', i') and C-phase winding groove group (b, c, h, i, n, o, t, u, z,
There is a phase difference of 1/3 of one magnetic pole pitch between a ', f', g '). As a result, the magnetic variation of the composition of the armature core 4 is reduced, and the cogging torque of this embodiment is greatly reduced.

Furthermore, each winding A1, A2, A3, A4, A5, A6, B1, B2, B of this embodiment
Effective pitch of 3, B4, B5, B6, C1, C2, C3, C4, C5, C6 is (8/9 of 1 pole pitch) = 160 degrees (electrical angle) or less (7/9 of 1 pole pitch) = 140 degrees (electrical angle) or more. Here, the effective pitch of the winding is the angle formed by the centers of the winding grooves in which the winding is housed. For example, looking at the A-phase winding group, the angle between the winding grooves a-f wound around A1 is 16
0 °, the angle between the winding groove g-1 wound around A2 is 160 °,
The angle between the winding winding grooves m and r of A3 is 155 °, the angle between the winding winding grooves sx of A4 is 140 °, and the winding winding groove of A5 is A The angle between y-d 'is 140 °, and the angle between the winding grooves e'-j' of the wound A6 is 145 °. For other B-phase and C-phase winding groups as well, from 160 degrees to 140 degrees
More than a degree. In this way, if the variation range of the winding groove in which the winding of each phase is housed is made small (1/3 or less of one magnetic pole pitch) and the variation range of the effective pitch of the winding is made small, (From 160 degrees or less to 140 degrees or more), winding work becomes easy and automation is possible.

Further, in the present embodiment, the effective pitch of the long teeth D · (1 + 1 /
P) = 7 ・ D / 6 is very close to the effective pitch D of the equitooth, and the effective pitch D of the short tooth is D ・ (1-1 / P) = 5 ・ D / 6 is also very effective to the effective pitch of the equitooth. Close to you. Therefore, long teeth and short teeth can be easily formed on the armature core.

Although various embodiments have been described, the invention is not limited to such embodiments. For example, the embodiment shown in FIG. 5 and the embodiment shown in FIG. 10 can be combined to construct an electric motor in which the number of magnetic poles in the field portion is P = 10. Further, the configuration of the embodiment shown in FIG. 5 can be simply doubled to construct an electric motor having double the number of magnetic poles and the number of winding grooves. Also, the presence of equal teeth is not always necessary.

Generally, a field portion having field poles of P poles (where P is an integer of 4 or more) at predetermined angular intervals on the circumference, and 6P winding grooves in which three-phase windings are wound. And an armature core having teeth formed between the winding grooves, and in the case of an electric motor in which one of the field part and the armature core is rotatable with respect to the other. The above-mentioned armature core has L long teeth (where L is an integer) with an effective pitch larger than D = 60 ° / P and M pieces with an effective pitch smaller than D (where M is an integer). By setting the number of the long teeth and the number of the short teeth to L ≧ 2 M ≧ 2, it is possible to easily change the phase of the winding groove and reduce the cogging torque.

Further, the armature core is also provided with N (where N is an integer) equal teeth whose effective pitch is equal to D, such as long pitch blocks and short teeth in which only long teeth and equal teeth are partially concentrated. It has the same number of short pitch blocks in which only teeth are partially concentrated, long pitch blocks and short pitch blocks are alternately arranged on the circumference, and at least two long pitch blocks are included in at least one long pitch block. Including at least one tooth and at least two short teeth in at least one short pitch block, the angle between a pair of adjacent long pitch block and short pitch block is (360 ° / P) · Q (where , Q is an integer of 2 or more), the effective pitch of the long teeth in the long pitch block is made equal to D · (1 + G / Q) (where G is an integer of 1 or more and Q / 2 or less). , The effective pitch of the short teeth in the short pitch block is D ・ (1-H / Q) Here, H is by equal to Q / 2 an integer) with one or more, can be easily reduced cogging torque.

In the embodiment of FIG. 5 described above, P = 4, N = 18 (> P),
(P>) L = 3 ≧ 2, (P>) M = 3 ≧ 2, and Q = P
= 4, G = 1, H = 1. In the embodiment shown in FIG. 9 (c), P = 4, N = 20 (> P), (P>) L = 2 ≧ 2,
(P>) M = 2 ≧ 2, Q = P = 4, G = 1 or G
= 2 = Q / 2, H = 1 or H = 2 = Q / 2.

Further, as in the embodiment of FIG. 5 described above, when the pitch of one magnetic pole of the field magnet section is used as the basic period, the variation range of the phase of the winding groove accommodating the winding of the predetermined phase is set to one magnetic pole pitch. If it is set to 1/3 or less, the winding will not be complicated. Further, if the effective pitch of the winding is set to 165 degrees or less to 135 degrees or more, automation of winding work can be easily realized.

In the above embodiments, the magnet is arranged inside and the armature core is arranged outside, but the relationship may be reversed.
Further, the field magnet portion is not limited to the ring-shaped magnet, but may be composed of a plurality of magnet magnetic pole pieces. Besides, various modifications can be made without changing the gist of the present invention.

EFFECTS OF THE INVENTION The present invention significantly reduces the cogging torque by specially arranging the winding grooves in an electric motor in which the number of winding grooves is larger than the number of magnetic poles in the field unit. Therefore,
Based on the present invention, for example, an electric motor for driving a joint of a robot,
If an electric motor for driving NC equipment is configured, highly accurate rotation drive and position control are possible.

[Brief description of drawings]

FIG. 1 is a structural diagram of a main part of a conventional electric motor, FIG. 2 is a configuration diagram of a drive circuit, FIG. 3 is a plan development view of the electric motor of FIG. 1, and FIG. 4 is a magnetic flux density of a magnet of a field part. FIG. 5 is a developed plan view showing an embodiment of the electric motor of the present invention, and FIG. 6 is a winding when the armature core of FIG. 5 is viewed with one magnetic pole pitch of the magnet as a basic period. FIG. 7 is a diagram showing the phase relationship of the groove for use, FIG. 7 is a diagram showing the magnetic variation of the embodiment of FIG. 5, FIG. 8 is a diagram showing the magnetic variation of the conventional example of FIG. 1, and FIG. 11 (a), (b), (c), and (d) are views showing another embodiment of the present invention, FIG. 10 is a plan development view showing another embodiment of the electric motor of the present invention, and FIG. FIG. 11 is a diagram showing a phase relationship of winding grooves when the armature core of FIG. 10 is viewed with one magnetic pole pitch of a magnet as a basic cycle. 2 ... Rotor, 3 ... Magnet, 4 ... Armature iron core,
5, a to x, a to j ... Winding groove, 6 ... Tooth, A1 to A4, B1 to B4,
C1 to C4 ... Winding.

Claims (2)

[Claims] 1. A field portion having permanent magnet magnetic poles of P pole (where P is an integer of 4 or more) at a predetermined angular interval on the circumference, and a permanent magnet magnetic pole provided with a predetermined gap therebetween. A 6P winding groove around which a phase winding is wound and an armature core having teeth formed between the winding groove, wherein the field part and the armature core are In any one of the above is an electric motor that is rotatable with respect to the other, when the effective pitch of each tooth of the armature core is an angle formed by the centers of the winding grooves at both ends of each tooth, The armature core has N equal teeth (where N is an integer of 4 or more) having an effective pitch equal to D = 60 ° / P and L teeth having an effective pitch greater than D (here, L is 2). The above electric machine, and M short teeth with an effective pitch smaller than D (here, M is an integer of 2 or more). When the arrangement of teeth of the iron core is blocked in a predetermined direction, starting from the long tooth and ending with the equal tooth, at least two long teeth and at least two equal teeth are partially adjacent and concentrated. A long pitch block, and starting from the short tooth and ending at the equal tooth,
Short pitch blocks in which at least two short teeth and at least two equal teeth are partially adjacent and concentrated are alternately arranged on the circumference, and further, between the long teeth and the long teeth. At least one of the equal teeth is arranged in the, and at least one of the equal teeth is arranged between the short tooth and the short tooth,
An electric motor, wherein at least one equal tooth is arranged between the long tooth and the short tooth. 2. The electric motor according to claim 1, wherein P> L and P> M.