JPH0810970B2 - Multi-phase permanent magnet type synchronous machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applied, for example, to brushless DC servo motors for OA and FA, spindles for FDD (floppy desk drive) and HDD (hard desk drive). The present invention relates to a multi-phase permanent magnet type synchronous machine that constitutes a brushless DC motor.

[Conventional technology]

 Conventionally, this type of motor has been used in which the number of phases is m, the number of pole pairs of the rotor is p, and n is an integer, p = m × n ± 1 and n = 1.

Then, in order to reduce the cogging torque of this motor, there are many devised structures such as one with an auxiliary magnetic pole in the middle of the armature magnetic pole and one with an auxiliary groove on the surface of the armature magnetic pole. Things have been proposed.

Further, as a precedent example filed by the present applicant, there is Japanese Patent Application No. Sho 62-322207 (Japanese Patent Laid-Open No. 1-164252) and a permanent magnet field two-phase multipole synchronous machine.

The gist of this prior art is that the fixed iron core is provided with four grooves at equal intervals on the circumferential surface facing the rotor, and the salient pole-shaped armature teeth formed by this are wound in two phases. Wires are wound into an armature, and 2p permanent magnet pieces are equally spaced on the circumferential surface of the rotor core facing the stator with a gap, and adjacent magnetic poles have different polarities. As described above, the multi-pole is magnetized to form a field to form a synchronous machine, the number p of permanent magnet pole pairs is an odd number of 5 or more, and the width angle t formed at the center of the circumferential surface of the armature tooth is t ≦ ( It is a permanent field two-phase multipole synchronous machine characterized by setting to π / p).

In this case, the cogging frequency Nc generated by one rotation is 2 ×
(2p).

[Problems to be Solved by the Invention]

However, in the technologies of the conventional example and the prior example, the auxiliary magnetic pole and the magnetic pole surface groove that do not contribute to the torque generation are provided to cancel the cogging torque, so that the effective torque must be sacrificed and the structure is complicated. It leads to cost up.

It is an object of the present invention to provide a multi-phase permanent magnet type synchronous machine which has a simple structure and hardly sacrifices effective torque and reduces cogging torque.

[Means for solving the problem]

In order to achieve the above object, in a three-phase permanent magnet type synchronous machine of the present invention, a permanent magnet magnetic pole of a rotor is a three-phase synchronous machine having p magnetic pole pairs, and p = 3n + (1 or 2) To increase the number of poles such as n ≧ 1 and p ≧ 5 to give a phase difference of 30 ° in electrical angle to the armature magnetic poles, it is 30/5 even when p = 5.
Offset the center position by = 6 °.

Furthermore, in a two-phase permanent magnet synchronous machine, the rotor is a two-phase synchronous machine in which the magnetic poles of the permanent magnets have the number of poles p. At p = 2n + 1, the number of poles is increased so that n ≧ 2, p ≧ 5. , 45/5 even when p = 5 to give a phase difference of 45 ° in electrical angle to the armature pole
Offset the center position by = 9 °.

[Work]

In the multi-phase permanent magnet type synchronous machine configured as described above,
The groove width of the armature magnetic pole is not so uneven, there is no obstacle in winding the armature winding, and the fundamental wave torque is reduced 3.
Only 4%, the cogging torque is significantly reduced.

That is, Nc, which is the pulsation number for each rotation of the cogging torque, is 2p for each armature tooth, but if the tooth phase differs by 180 ° in electrical angle, the same pulsation occurs, so how many is it? Even if it does, Nc = does not increase. For example, in the case of the equally divided groove pitch, Nc = 3 × 4 = 12 for a 3-phase 6-groove 4-pole case, and Nc = 2 × 6 = 12 for a 2-phase 4-groove 6-pole case. Generally, the amplitude of cogging torque decreases as Nc increases, so
The conventional method is to add auxiliary magnetic poles or auxiliary grooves so that the number of grooves is small and Nc is large.

Here, in the case of p = 5 in the case of three phases, Nc = (6/2) × 10 = 30 in the conventional equal pitch, but one tooth pitch is set as in one embodiment of the present invention. If the pitches are unequally divided by 30 ° in electrical angle, Nc = 2 × number of poles × number of grooves, and Nc = 6 × 10 = 60, which is large and the amplitude of cogging torque is significantly reduced.

Further, as in the other embodiment of the present invention, when the tooth pitch is set to be an unequal pitch in which every other electrical angle is shifted by 45 °, Nc = 4 × 10 = 40, and the amplitude of the cogging torque is also It will be reduced in general.

If you arrange here, Becomes

〔Example〕

 A front sectional view of one embodiment of the present invention is shown in FIG.

 This one embodiment is for a three-phase ten-pole case.

2 x 3 (number of phases) =
The concentrated winding coil 3 is wound around each of the magnetic poles 2 forming the salient poles 6 to form the magnetic poles U, V, W, U ', V', W'of the armature teeth. A rotor 5 having 10 poles is provided, which is opposed to each other with a gap and is magnetized by equally dividing the cylindrical permanent magnets 4 into different magnetic poles into 10 different poles.

FIG. 2 shows the relationship between the cogging force and the effective magnetic flux for one armature tooth.

In this way, teeth that differ in electrical angle by 180 ° generate the same pattern of cogging torque. For U and U ′, the cogging force is added in the same pattern in the case of a constant tooth pitch, so 2
Although it doubles, when the electrical angle is shifted by 30 ° by the unequal pitch as in the present invention, the trough of the cogging torque due to U, V, W is
The cogging torque peaks due to U ′, V ′ and W ′ are filled up, and the cogging torque is greatly reduced. Then 23
a, 23b, 23c… are the stable points of the cogging force at the point where the cogging force crosses the zero of the downward sloping slope, and 24a, 24b, 24c, 24d…
Is an unstable point of the cogging force at the point where the cogging crosses the rising zero slope.

In this way, the cogging torque becomes a double harmonic torque of the fundamental wave torque (effective magnetic flux).

In U, V and W, the fundamental wave torques have a phase difference of 120 ° with each other, so the cogging torques of the second harmonic have a phase difference of 240 ° with each other. Therefore, it is the same as the 120 ° phase.

If the cogging torque is a complete sine wave, the composition of the three cogging torques with a phase difference of 120 ° will be zero, but it will not actually be zero because the harmonic torque component is superposed on the cogging torque.

When the armature magnetic poles such as U ', V', and W'are displaced by an electrical angle of 30 °, the phase difference of cogging torque is displaced by 60 °.

Since the cogging torques of U ', V', W'are added to the cogging torques of U, V, W, the valleys are filled with mountains, and the cogging torque is greatly reduced.

 FIG. 3 is a front sectional view of another embodiment of the present invention.

In all the drawings, the same reference numeral represents the same member.

Another embodiment is a two-phase ten-pole permanent magnet synchronous machine, in which an inner stator and an outer rotor have a two-phase coil 3 (armature α phase winding, armature, α and β having a phase difference of 90 ° electrically). (β-phase winding) is wound around the magnetic pole 2.

As for the magnetic pole 2 of the stator, 90 ° between β and α Between ~ 90 ° ~ between β The armature magnetic poles with unequal pitch are formed as follows, and Nc increases and the amplitude of the gogging torque decreases as in the first embodiment.

〔The invention's effect〕

Since the present invention is configured as described above,
It has many remarkable effects as described below.
The structure is simple with 6 or 4 grooves, and the winding can be automatically wound easily.

Nc = 6 × 2p or Nc = 4 × 2p, and the cogging pulsation number is large and the amplitude is very low.

Since there is sufficient winding space, the efficiency is high and the temperature rise can be reduced.

If a strong magnet such as rare earth is used as the permanent magnet, high torque can be obtained.

Since it is a magnetic path that can be laminated, iron loss is small, so high-speed motion at high frequencies is also possible.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention, FIG. 2 is a relationship diagram of cogging force and effective magnetic flux for one armature tooth, and FIG. 3 is a front sectional view of another embodiment of the present invention. is there. 1 ... Yoke, 2 ... Magnetic pole (armature tooth), 3 ... Coil, 4 ... Permanent magnet, 5 ... Rotor, 6 ... Axis.

Claims (2)

[Claims] 1. A stator is an iron core having six teeth, and a rotor is a three-phase synchronous motor having permanent magnet magnetic poles with a pole pair number p, p = 3n + (1 or 2) n> = 1 p> = 5 n is an integer. When the width angle t formed at the center of the stator tooth is defined as: t <= 180 ° / p, the stator tooth pitch angle of each pole pair is 60 °- A multi-phase permanent magnet synchronous motor characterized by an unequal pitch that alternates between (30 ° / p) and 60 ° + (30 ° / p). 2. A stator is an iron core having four teeth, and a rotor is a three-phase synchronous motor having permanent magnet magnetic poles having a number of pole pairs p, p = 2n + 1 n> = 2 p> = 5 n is an integer. With the width angle t formed at the center of the stator teeth, the relation of t <= 180 ° / p is satisfied, and the pitch angle of the stator teeth of each pole pair is 90 °, 90 ° + 45 ° / Multi-phase permanent magnet type synchronous motor characterized by unequal pitch alternating at p, 90 ° and 90 ° -45 ° / p.