JPS6223537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric motor having an armature core having a salient pole structure.

In general, motors with a salient pole structure on the armature core for winding are smaller and lighter because they can link more field magnetic flux to the windings than motors without a salient pole structure. This is an electric motor that produces a large output torque.

However, since the armature core has a salient pole structure, which is magnetically non-uniform, when a permanent magnet is used as the field part, for example, it has the disadvantage that cogging force is generated due to interaction with the permanent magnet. There is. This will be explained below with reference to the drawings.

FIG. 1 shows a diagram of the main parts of an example of a conventional electric motor. A permanent magnet 2 attached to the rotor 1 is an annular magnet having eight magnetic poles spaced at approximately equal angular intervals (45 degrees), and constitutes a field section. The armature core 3 has six winding salient poles 4a ₁ , 4
b ₁ , 4c ₁ , 4a ₂ , 4b ₂ , 4c ₂ , which are
They are located at approximately equal angular intervals (60°), and are arranged with a required gap from the magnetic poles of the permanent magnet 2. One drive coil 5a ₁ , 5b _{1 , 5c 1} , 5a ₂ , 5b ₂ , 5c ₂ is wound around each of _the winding salient poles 4a ₁ to 4c ₂ .

The above-mentioned salient winding poles 4a ₁ to 4c ₂ are divided into independent three-phase groups, ie, 4a ₁ , 4a ₂ and 4b ₁ , 4b _{2 and 4c 1 ,} 4c ₂ with respect to the relative positional relationship with the magnetic poles of the permanent magnet 2. ing. Since the magnetic flux interlinking with the drive coil is equal to the magnetic flux flowing into the winding salient pole, the drive coil is
It is divided into phase groups 5a ₁ , 5a ₂ , 5b ₁ , 5b ₂ , 5c ₁ and 5c ₂ . Therefore, if the rotational position of the permanent magnet 2 is detected using a magnetic sensing element such as a Hall element, and the drive coils of each phase to be energized are sequentially switched using a semiconductor switch such as a transistor, then the rotor 1 can be It can be rotated continuously in any direction.

Next, the relationship between the cogging force and the magnetic fluctuation of the armature core of the conventional example shown in FIG. 1 will be explained.

Generally, cogging force is generated when the magnetic energy stored in the magnetic field between the permanent magnet 2 and the armature core 3 changes depending on the relative position of the two. Since magnetic energy is a quantity related to the square of the magnetic flux density, the permanent magnet 2 has a basic period of one magnetic pole pitch, and the magnetic fluctuation of its harmonic component (the square of the magnetic velocity density generated by the permanent magnet 2) (quantities related to). Therefore, 1 of permanent magnet 2
It is sufficient to consider the magnetic fluctuation of the armature core 3 (amount related to the permeance of the armature core 3 viewed from the surface of the permanent magnet 2) with the magnetic pole pitch as the basic period, and in general, it is possible to reduce this fluctuation. , if the frequency of fluctuation is increased, the cogging force, which is the interaction with the permanent magnet 2, becomes smaller.

The magnetic fluctuations of the conventional armature core 3 shown in FIG. 1 are caused by grooves 6a ₁ , 6b ₁ , 6c ₁ , 6a ₂ ,
It is caused by 6b ₂ and 6c ₂ . These grooves have almost the same shape, and the groove groups (6a ₁ , 6a ₂ , and 6a
Between b ₁ , 6b ₂ and 6c ₁ , 6c ₂ is 1/1 magnetic pole pitch.
There is a phase difference of 3. Therefore, the composite magnetic fluctuation of the armature core 3 becomes as shown by the solid line in FIG. In addition, the broken lines a ₁ , a ₂ , b ₁ , b ₂ , c ₁ , c ₂ in Fig. 2
represents the magnetic fluctuation caused by each groove 6a ₁ , 6a ₂ , 6b ₁ , 6b ₂ , 6c ₁ , 6c ₂ .

As is clear from FIG. 2, the magnetic fluctuations of the conventional armature core 3 shown in FIG.
This results in large fluctuations with valleys. As a result, the direction of the cogging force also changes three times in the order of acceleration, deceleration, and acceleration for each rotation of one magnetic pole pitch of the rotor.

Generally, the magnitude of each component of cogging force is related to the product of the magnitude of the component in the armature core and the magnitude of the component in the permanent magnet, which is the field part, and if the product is small, cogging The magnitude of the corresponding component of force also becomes smaller. Further, the magnitude of the components of a permanent magnet generally decreases as the components become higher-order components. Therefore, if the magnitude of the magnetic fluctuation of the armature core is reduced or the order of the dominant component of the fluctuation is made higher, the cogging force will be reduced.

Based on the above-mentioned idea, the present invention makes the pitch of one magnetic pole of the permanent magnet for the field equal to the fundamental period by making the effective opposing widths, that is, the opposing pitches of the salient poles for winding with respect to the field part unequal. The above conditions are realized by increasing the number of phases in the grooves between the salient poles of the armature core, which have independent phases with respect to the relative positional relationship with the magnetic poles when moving the armature core, thereby providing an electric motor with small cogging force. .

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 3 is a diagram showing the main part of an embodiment of the present invention. The permanent magnet 2 attached to the rotor 1 is an annular magnet having eight magnetic poles at equal angular intervals or approximately at equal angular intervals (45 degrees), as in the conventional example shown in FIG. The armature core 13 has six winding salient poles 14a ₁ , 14b ₁ , 14c ₁ , 14a ₂ , 14 at equal angular intervals or approximately at equal angular intervals (60°).
It has b ₂ , 14c ₂ radially. Here, the grooves located on both sides of the winding salient poles 14a ₁ , 14c ₁ , 14b _{2 ,} namely a1 and a2, a3 and a4, a5 and a6
The pitch between the centers is about 67.5°, and the grooves located on both sides of the winding salient poles 14b ₁ , 14a ₂ , 14c ₂ , i.e., a2 and a3, a4 and a5, a6 and a1
The center-to-center pitch is approximately 52.5°. In other words, there are two types of center spacing between the grooves located on both sides of the salient poles of the armature core 13 (67.5° and 52.5°).
is being done.

Further, each of the winding salient poles 14a ₁ to 14c ₂ has one drive coil 15a ₁ , 15b ₁ , 15c ₁ ,
15a ₂ , 15b ₂ , and 15c ₂ are wound.

In this embodiment, similarly to the conventional example shown in FIG.
The drive coils 15a ₁ to 15c ₂ are independent three-phase sets, namely 15a ₁ , 15a ₂ and 15b ₁ , 15b ₂ and 15c ₁ ,
It is divided into 15c _{and 2} . Therefore, in this case as well, the rotational position of the permanent magnet 2 is detected by a magnetic sensing element such as a Hall element, and the semiconductor switch circuit 7 as illustrated in FIG.
If the energized drive coils of each phase are sequentially switched, the rotor 1 can be continuously rotated in the same direction.

Next, magnetic fluctuations in the armature core 13 of this embodiment will be described.

6 of the groove located on both sides of the salient pole of the armature core 13
There are two types of center spacing (67.5° and 52.5°).
6 grooves are arranged at unequal angular intervals so that Six grooves a1 to a formed
6 are all made to have independent phases (the center phases of the grooves are all different, and the distance between adjacent center phases is at least (1 magnetic pole pitch)/12). Actually, the center phase intervals of the six grooves are set at equal intervals of (1 magnetic pole pitch)/6.
As a result, the relationship between the magnetic fluctuations of each groove becomes as shown by the broken line in FIG. 5, and the composite magnetic fluctuation of the armature core 13 becomes as shown by the solid line in the same figure.
Comparing this with the magnetic fluctuation of the conventional example in Figure 1 (solid line in Figure 2), the magnitude of the magnetic fluctuation is smaller and the order of the dominant component of the fluctuation is higher. ing. Therefore, the cogging force of the electric motor of this embodiment is smaller than that of the conventional example.

As shown in the embodiment shown in FIG. 3 above, the grooves are arranged at unequal angular intervals so that the center intervals of the grooves located on both sides of the salient poles of the armature core are unequal (two or more types of pitches). If so, the phase of the groove in the armature core can be easily shifted with respect to the relative positional relationship with the magnetic pole of the permanent magnet when one magnetic pole pitch of the permanent magnet is considered as the basic period, so the cogging force can be easily reduced. Can be reduced. At this time, regarding the relative positional relationship with the magnetic poles of the permanent magnet when one magnetic pole pitch of the permanent magnet is considered as the basic period, the phases of the grooves of the armature core are all independent, and the phase interval is (1 magnetic pole pitch). /(number of salient poles) or approximately equal, the effect of reducing cogging force will also be greater. In particular, if the number of winding salient poles around which a single-phase drive coil is wound and the variation in the width of the salient poles are made equal for each phase, the generated torque will not vary between phases. do not have. Furthermore, as in the embodiment shown in FIG. The electric motor can be easily manufactured with a small number of wires.

FIG. 6 shows a main part configuration diagram of another embodiment of the present invention. To explain this, the permanent magnets 2 attached to the rotor 1 are similar to those used in the embodiment shown in FIG. 3 described above. The armature core 23 includes six winding salient poles 24a ₁ , 24b ₁ , 24c ₁ , 24a ₂ , 2
4b ₂ , 24c ₂ and six auxiliary salient poles 30a, 30b, 30c, 30d, 30 located between them
e and 30f, and each of the salient poles is integrally formed of, for example, a laminate of silicon steel plates. Here, the winding salient poles 24a ₁ , 24c ₁ , 24
Between the grooves located on both sides of b ₂ , that is, grooves β1 and β2
The angular intervals between β5 and β6, and between β9 and β10 are approximately 56.25°, and the salient poles for winding 24b ₁ , 2
Between the grooves located on both sides of 4a ₂ and 24c ₂ , that is, the groove β
The angular intervals between 3 and β4, between β7 and β8, and between β11 and β12 are approximately 41.25°, and each auxiliary salient pole 30a
Between the grooves located on both sides of ~30f, that is, between grooves β2 and β3, between β4 and β5, between β6 and β7, between β8 and β
The angular intervals between β10 and β11, and between β12 and β1 are approximately 11.25°. In this way, the spacing between the centers of the 12 grooves located on both sides of the salient poles of the armature core 23 has three different pitches (56.25° and 41.25°).
11.25°), and the relative positional relationship with the magnetic poles of the permanent magnet 2 when one magnetic pole pitch of the permanent magnet 2 is considered as the basic period, is between the salient poles. 12 grooves β1 formed in
- β12 are all made to have independent phases (the center phases of the grooves are all different, and the distance between adjacent center phases is set to be more than (1 magnetic pole pitch)/24). Actually, the center phase intervals of the 12 grooves are set at equal intervals of (1 magnetic pole pitch)/12. Therefore, the magnetic composite fluctuation in the armature core 23 is as shown by the solid line in FIG. In addition,
The broken lines in the figure indicate the magnetic fluctuations of each of the grooves β1 to β12.

That is, in the embodiment shown in FIG. 6, the fluctuation has 12 peaks and troughs.

Moreover, each winding salient pole 24a ₁ , 24b ₁ , 24c ₁ ,
24a ₂ , 24b ₂ , 24c ₂ each have one drive coil 25a ₁ , 25b ₁ , 25c ₁ , 25a ₂ , 25
b ₂ and 25c ₂ are wound. The drive coil has three phases, namely 25a ₁ , 25a ₂ and 25b ₁ , 25
b ₂ , 25c ₁ and 25c ₂ , and how they are driven is the same as in the previous embodiment.

As shown in the embodiment of FIG. 6, if an auxiliary salient pole is provided between the winding salient poles and located between the magnetic poles of the permanent magnet, the order of magnetic fluctuations in the armature core will be increased. , and the amount of variation thereof can be easily reduced, resulting in an electric motor with small cogging force. Furthermore, the width (effective opposing pitch) through which the magnetic flux flows into each of the winding salient poles in this embodiment is closer to one magnetic pole pitch of the permanent magnet than in the embodiment shown in FIG. 3 described above. Therefore, the maximum value of the magnetic flux flowing into each winding salient pole, that is, the magnetic flux interlinking with the drive coil becomes large, and efficiency is also improved.

Note that when the winding salient pole and the auxiliary salient pole are integrally formed of the same magnetic material as in the embodiment of the present invention shown in FIGS. 3 and 6, the grooves between each salient pole are shape,
The accuracy of the arrangement is improved, and the effect of the present invention is more stable. However, the present invention is not limited to such a structure. For example, the present invention is not limited to such a structure. may be formed from separate magnetic members. In this case, after winding the salient pole structure for winding, it is sufficient to assemble both salient pole structures with magnetic coupling, which facilitates the winding work.

Furthermore, although the above description has been made regarding a three-phase drive type electric motor having three phases of winding salient poles that are independent in their relative positional relationship with the magnetic poles of the permanent magnet, the present invention is not limited to such a drive type. , it is also possible to implement other general multi-phase drive systems.

In particular, when the order of the dominant component of the composite magnetic fluctuation of the armature core is l, in the case of (2m+1) phase (m≧1), (2m+1)<l...(1) In the case of a 2m phase (m≧2), if m<l...(2), the effects of the present invention can be easily obtained.

Further, in each of the above-described embodiments of the present invention, the rotor is provided with a field part, but the present invention is not limited to such a structure, and the field part may be used as a stator and the armature core may be used as a rotor. However, it is not limited to the abduction type, but may be an adduction type. Further, each salient pole of the armature core is not limited to a laminate of silicon steel plates, and may be formed by bending a steel plate.

As is clear from the above description, the present invention is capable of realizing an electric motor with a small number of drive coils, easy to manufacture, and low cogging force at low cost.
In particular, it can be used as a rotation drive source for audio equipment such as record players and tape recorders, and video equipment such as video tape recorders, which require smooth rotational torque, to bring about great effects.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the main parts of a conventional electric motor, Figure 2 is a diagram showing magnetic fluctuations in the armature core,
FIG. 3 is a main part configuration diagram of an embodiment of the present invention, FIG. 4 is a main part circuit diagram showing an example of the drive circuit configuration, and FIG. 5 is a magnetic FIG. 6 is a diagram showing the main part configuration of another embodiment of the present invention, and FIG. 7 is a diagram showing the magnetic variation of the armature core in the embodiment of FIG. 6. . 1... Rotor, 2... Permanent magnet, 13, 23...
...Armature core, 14a ₁ ~ 14c ₂ , 24a ₁ ~ 24c ₂
... Salient poles for winding, 15a ₁ to 15c ₂ , 25a ₁ to 25
c ₂ ... Drive coil, 6a ₁ to 6c ₂ , a1 to a6, β
1 to β12...Groove, 30a to 30f...Auxiliary salient pole.

Claims (1)

[Scope of Claims] 1. A field section in which four or more N and S poles are arranged alternately at equal pitch intervals or approximately equal pitch intervals, and a permanent magnet is substantially formed in an annular shape; formed between an armature core having T salient poles (T is an integer of 6 or more) arranged so as to face the magnetic poles of the field portion all around the circumference, and the salient poles; 2m + 1 phase (m is 1) stored in T grooves
(wherein 2m+1 is an integer equal to or less than T/2) drive coils, and one of the field part and the armature core is rotatable relative to the other, The grooves are arranged at unequal angular intervals so that the T center intervals formed by the grooves located on both sides of each salient pole of the armature core are a plurality of pitches, and The center phases of the T grooves in the armature core are all different when one magnetic pole pitch is a basic period, and the phase interval between adjacent center phases is set to be at least (one magnetic pole pitch)/2T or more apart. An electric motor characterized by: 2. It is characterized in that when one magnetic pole pitch of the field part is taken as the basic period, the adjacent phase intervals of the center phases of the grooves of the armature core are all equal to or almost equal to (1 magnetic pole pitch)/T. An electric motor according to claim 1. 3. The electric motor according to claim 1, wherein T is an integral multiple of 2 or more of (2m+1).