JPH078123B2 - 3-phase DC motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a three-phase DC motor, and more particularly to a cored DC motor with significantly reduced cogging.

[Conventional technology]

In a conventional three-phase DC motor, the combination of the number of field poles P and the number of salient poles or slots (hereinafter referred to as the number of slots) N formed on the circumference of the core is generally P = (3 ±
1) n, N = 3n (where n is a natural number). In the case of a cored motor, cogging occurs between the magnetic pole boundary (the boundary between the N pole and the S pole) and the salient pole portion, and the order of the cogging is usually
As shown in Tables 1 and 2, the least common multiple of N and P occurs.

The principle (mechanism) of such conventional motor cogging generation will be described with reference to FIGS. 4 and 5 by taking the case of n = 4 (8 poles, 12 slots) in Table 1 as an example. To do. Fig. 4 shows the conventional 3 with 8 poles and 12 slots.
FIG. 3 is a schematic cross-sectional view of the three-phase DC motor 10, in which a winding L (coil) L is wound around each slot of the core C (salient pole portions c _{1 to} c ₁₂ ) of the three-phase DC motor 10 to form an armature portion. A cylindrical magnet M having 8 poles is arranged via a constant air gap g, and a yoke Y for forming a magnetic path is attached to the outer periphery of the magnet M. Such a three-phase DC motor is configured such that one of the field portion composed of the magnet M and the yoke Y and the armature portion is fixed, and the other is rotatable with respect to it.

Here, the field magnetic poles (M _{1 to} Mp) are magnetic poles composed of N poles or S poles, and the N pole magnetic poles and the S pole magnetic poles are alternately arranged at equal intervals on the circumference of the yoke Y. P (at this time P = 8)
Arranged to form the magnet M.

Further, the salient pole portion projects from the core C on the T-shape forming the slot, and the winding L of three phases is continuously wound around the slot of the salient pole portion to form the armature portion.

In the three-phase DC motor 10 having such a configuration, when one of the armature portion and the field portion is fixed and the other is rotated, N
Cogging occurs between the boundaries a to h of the magnetic poles of the pole and the S pole and the salient pole portion, and at the positions of the boundaries a to h, respectively, FIG.
Waveform cogging as shown in (h) was generated. Then, the cogging of the entire motor is a combination of these, and the waveform is as shown in (i) of the figure, and the number of times of cogging per rotation (hereinafter referred to as the cogging order) is
It is 24. This is the least common multiple of the number of magnetic poles (P = 8) and the number of slots (N = 12).

[Problems to be Solved by the Invention]

By the way, in such a conventional three-phase DC motor 10, since cogging occurs simultaneously at the same timing at a plurality of places represented by k = N × P / (least common multiple of N and P) (1), There is a drawback that cogging becomes very large. For example, in the 8-pole 12-slot motor 10 described above, if the size of the cogging generated at one of the boundaries a to h is t, the total size C of the cogging is T = kt = 12 × 8t / 24 = 4t, which is four times as large as the cogging generated at the boundaries a to h. Therefore, when such a motor 10 is used for a VTR drum motor or a capstan motor, for example, there are problems that the jitter is adversely affected and noise or vibration is generated.

[Means for Solving the Problems]

In order to solve the above problems, a three-phase DC motor of the present invention, (1) the magnet and the field portion consisting of a yoke (Y) and (M), a core (C) and the winding (L ₁ ~L ₃ ) A three-phase direct current motor having an armature part composed of and a field part forming a field magnetic pole (M _{1 to} Mp) in which the magnet (M) is a P pole,
The armature portion is arranged at equal angular intervals on the circumference of the yoke (Y), and the armature portion has N salient pole portions (c ₁ ) to which the core (C) is wound with three-phase windings (L _{1 to} L ₃ ). ~ Cn) and are evenly spaced on the circumference,
It is fixed or rotatable with respect to the field part, and the field pole (M ₁
˜Mp) and the salient pole portions (c _{1 to} cn), the number of poles P of the field magnetic poles (M _{1 to} Mp) and the number N of the salient pole portions (c _{1 to} cn) are P =
2 (4n + 3), N = 3 (2n + 1) (n is a natural number),
In addition, the least common multiple of the number P of poles of the field magnetic poles (M _{1 to} Mp) and the number N of salient pole portions (c _{1 to} cn) is configured to be equal to N × P,
In addition, (2) the three-phase windings (L _{1 to} L ₃ ) are arranged such that the windings of one phase are alternately arranged in the salient pole portions (c _{1 to} cn). It is configured to be continuously wound around N / 3 salient poles.

〔Example〕

The main feature of the three-phase DC motor (hereinafter also simply referred to as “motor”) of the present invention is that the selection (relationship) between the number of slots N and the number of magnetic poles P is devised in order to reduce cogging.
It has been set to the above relationship. The concrete numerical values are shown in Table 3.

In the case of such a combination, the positions of the salient pole portions formed at equal intervals on the circumference of the magnetic pole and the core are displaced,
Unlike conventional motors, cogging that occurs at the same timing is never added together. Generally, the higher the degree of cogging, the less the degree of cogging. However, in the case of the present invention, a combination in which the degree of cogging as shown in Table 3 becomes higher than that in the conventional example shown in Tables 1 and 2. Therefore, the cogging is extremely small and the rotation is smooth.
A phase DC motor was realized. (In order to reduce cogging, there are methods such as operating the magnetizing waveform and providing an auxiliary groove or a compensating pole in the core, but the method of operating the magnetizing waveform is difficult to set conditions, The auxiliary groove reduces the total magnetic flux, thus reducing the torque, and the auxiliary pole reduces the winding space and torque when the motor is downsized.
In the case of the three-phase DC motor of the present invention, such an operation is completely unnecessary, so that the assembly is easy and the torque is not lowered. By the way, when the number of magnetic poles P and the number of slots N are combined as in the case of the three-phase DC motor of the present invention, the salient pole portions are all out of phase with respect to the magnetic poles. A coil must be wound around the part to form one phase. Therefore, in the case of the motor of the present invention, 1
While reversing the winding direction of the coil on every other salient pole,
It is formed by winding around N / 3 (number of phases) salient poles.

Next, specific examples of the three-phase DC motor according to the present invention will be described in comparison with conventional examples. Figure 3 is number 4
It is a plane development view of the conventional motor shown in the figure. As shown, the salient pole portions c ₁ , c ₄ , c ₇ , and c ₁₀ have the same phase with respect to the magnetic poles,
If the first-phase coil L ₁ is wound counterclockwise (ccw) with respect to the salient pole portion c ₁ , the salient pole portions c ₄ , c ₇ , and c ₁₀ are also wound in the ccw direction in the same manner. It forms the u phase. Further, the v-phase and w-phase are similarly formed for the other two-phase coils L ₂ and L ₃ .

In addition, the space between each salient pole is the electrical angle ψ = ψ = (360 ° / N) × (P / 2) …………… (2) (However, N: number of slots, P / 2: pole In the case of the conventional motor 10 shown in FIG. 3, for example, the phase difference between the salient pole portions c ₁ and c _{2 with} respect to the magnetic pole is the electrical angle ψ ₁ ,
₁ = (360 ° / 12) × 8/2 = 120 °, and a three-phase motor is formed by forming the coil as described above. In this case, since the four salient pole portions have the same phase with respect to the magnetic poles, as described with reference to FIGS. 4 and 5,
The cogging generated in the same phase is added as it is, and in the case of the conventional example shown in FIG. 3, the cogging torque becomes about four times the cogging torque generated by one salient pole portion as a whole.
In the figure, ● → and → ○ indicate the start and end of winding of the coil, respectively.

<First Embodiment> Next, a specific configuration example of the three-phase DC motor of the present invention will be described with reference to FIG. FIG. 1 shows a combination of the number of magnetic poles P and the number of slots N shown in Table 3, where n =
FIG. 3 is a plan development view showing a 1-phase (14-pole, 9-slot) three-phase DC motor. In this figure, the same parts as those of the conventional example shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted. Nine salient poles c ₁ to c ₉ because it has all the phase shifted with respect to the magnetic pole, to form a one phase to choose three salient less deviation way to each other. In the combination of P and N of the motor according to the present invention, the winding direction of the coil may be reversed around every other salient pole portion as described above. That is, if the coil L ₁ is wound around the salient pole portion c ₁ in the ccw direction in FIG. ₁ , the phase difference ψ ₂ between the salient pole portions c ₁ and c _{3 with} respect to the magnetic poles is Electrical angle ψ ₂ = (360 ° / 9) × 7 × 2 = 560 ° =
It becomes 360 ° + 200 °, which can be regarded as an electrical angle of 200 °, so if the coil is wound in the clock (cw) direction, the counter electromotive force waveform (hereinafter referred to as “counterelectromotive waveform”) Phase difference ψ
₂ ′ is φ ₂ ′ = 200 ° −180 ° = 20 °. Similarly,
If it is wound around the salient pole portion c ₅ in the cw direction, the phase difference becomes 20 ° with respect to the salient pole portion c ₃ . Thus c ₁ (ccw) → c ₃ (c
The u phase is formed by winding the coil L ₁ every other three salient pole portions so that w) → c ₅ (ccw).

Further, the salient pole portion c ₄ has a phase ψ ₃ with respect to the salient pole portion c ₁ , and ψ ₃ =
(360 ° / 9) × 7 × 3 = 840 ° = 2 × 360 ° apparent as substantial electrical angle + 120 ° are 120 ° out similar to the above, ccw direction salient pole portion c _4, butt Cw direction on pole c ₆ , salient pole c
Wind the coil L ₂ around ₈ in the ccw direction (ie c ₄ (ccw) → c
₆ (cw) → c ₈ (ccw)} v phase is formed. Similarly, starting the winding of salient pole portion c ₇ whose actual electrical angle is shifted by 120 ° with respect to salient pole portion c ₄ , c ₇ (ccw) → c ₉ (cw) → c ₂ (cc
w) is formed by winding the coil L _{3 around the three} salient poles so that the w-phase coil is formed by the coils of u to w phases.
The coil L of the direct-current motor 1 that is in phase is configured.

FIG. 6 is a diagram showing the counter electromotive waveform of each phase of the three-phase DC motor 1, and the curve α in FIG. 6 (A) is the counter electromotive waveform generated by the coil wound around the salient pole portion c ₁ . , The curve β is the counter electromotive waveform due to the coil wound around the salient pole portion c ₃ , the curve γ is the counter electromotive waveform due to the coil wound around the salient pole portion c ₅ , and the curve δ is the salient pole portions c ₁ and c ₃ ,
It is a composite waveform by the coil wound around c ₅ , that is, a u-phase back electromotive waveform. Similarly, the curve ξ in FIG. 6 (B) is the back electromotive force waveform ε, ζ, generated by the coils wound around the salient pole portions c ₄ , c ₆ , c ₈ .
It is a composite waveform of η, that is, a v-phase counter-electromotive waveform, and the curve μ in FIG. 6 (C) is the counter-electromotive waveforms θ, κ, which are formed by the coils wound around the salient pole portions c ₇ , c ₉ , c ₂ . It is a composite waveform of λ, that is, a w-phase back electromotive waveform.

When the characteristics of the three-phase DC motor 1 were measured in comparison with a conventional motor having the closest number of poles and slots, it was confirmed that the cogging torque was significantly reduced as compared with the conventional motor. Was done.

Second Embodiment Next, a second embodiment of the three-phase DC motor of the present invention will be described.
This will be described with reference to the plan development view of FIG. In this figure, the same parts as those in the first embodiment shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. In the three-phase DC motor 2 of the second embodiment, the combination of the number of magnetic poles P and the number of slots N in Table 3 is n = 2 (22 poles and 15 slots). The difference between the three-phase DC motor 2 and the motor 1 is that the number of magnetic poles of the magnet M and the number of salient pole portions (the number of slots) increase, as is clear from the comparison between FIGS. 1 and 2. Every other five salient poles (eg c ₁ , c ₃ , c ₅ , c ₇ ,
c ₉₎ in to the winding reversing the direction to form a one phase winding. In this case as well, the salient pole portions c _{1 to} c ₁₅ are all out of phase with the magnetic poles, and one phase is formed by selecting five (15 slots / 3 phases) with little deviation from each other.

That is, as shown in FIG. 2, assuming that the coil L ₁ is wound around the salient pole portion c ₁ in the ccw direction, the salient pole portion c ₃ has a space between the salient pole portions c ₁ and c _{3 with} respect to the magnetic pole. The phase difference ψ _{4 of} is the electrical angle, and from the second formula ψ ₄ = (360 ° / 15) × 11 × 2 = 528 ° = 360 ° + 168
゜ (11 is the number of pole pairs), the effective electrical angle is 16
When the coil L ₁ is wound around the salient pole portion c ₃ in the cw direction, the phase difference ψ ₄ ′ of the counter electromotive waveform is ψ ₄ ′ = 180 ° −168 °
゜ = 12 ゜. In addition, salient poles c ₅ , c ₇ , and c ₉ are ccw, cw, and c, respectively.
The coil L ₁ is wound in the cw direction to form the u phase. The v-phase coil L ₂ has a salient pole portion c ₁₁ (ccw) → c ₁₃
(Cw) → c ₁₅ (ccw) → c ₂ (cw) → c ₄ (ccw) in this order by winding coils around the five salient pole portions. The w phase is c ₆ (ccw) → c ₈ (cw) → c ₁₀ (ccw)
→ c ₁₂ (cw) → c ₁₄ (ccw) in order of 5 L
It is formed by winding ₃ . In this case, since the salient pole portions c ₁ and c ₁₁ and the salient pole portions c ₁₁ and c ₆ are out of phase with each other by a substantial electrical angle of 120 °, these DC phases are three phases in u to w phases. The coil L of the motor 2 is constructed.

The counter electromotive waveforms of these u to w phases are shown in FIGS. 7 (A) to 7 (C).
The difference from FIGS. 6 (A) to 6 (C) is that the number of salient pole portions (the number of slots) is increased by 2 for each phase, and other operating principles are as follows. Since it is the same as that in FIG. 6, the counter electromotive waveforms generated by the salient pole portions c _{1 to} c ₁₅ are denoted by the same reference numerals as those of the salient pole portions, and detailed description thereof will be omitted.

[Effect]

The three-phase DC motor according to the present invention is configured as described above, and in particular,
It is possible to prevent cogging from occurring at the same timing by providing the core having N salient pole portions with three-phase windings formed at a phase interval different from that of the field magnetic poles. Becomes That is, since the cogging torque due to the generation of cogging can be significantly reduced, vibration,
It is possible to significantly reduce the occurrence of motor jitter and noise. Therefore, all the problems of the conventional three-phase DC motor can be solved, and the motor of the present invention can be applied to VTR, HD
When it is installed in devices such as D and FDD, it has a practically excellent feature that it can realize remarkably high performance.

Furthermore, without changing the magnetic pole width formed in the winding slot or increasing or decreasing the number of magnetic poles, for example, the salient pole portion having the same magnetic pole width is different in phase from the field magnetic pole. Since the coils can be wound around a plurality of salient pole portions which are provided at intervals and have a relatively small phase shift from each other to form one phase, the directions of the coils wound around the salient pole portions are alternately inverted. The cogging torque can be significantly reduced as described above by only shifting the timing of cogging, so that the efficiency or workability of the motor assembling process such as coil winding work is not impaired. effective.

[Brief description of drawings]

1 and 2 show a first three-phase DC motor according to the present invention.
And a plan development view of the second embodiment, FIGS. 3 and 4 are plan development views and schematic sectional views of a conventional typical three-phase DC motor, respectively, and FIG. 5 is cogging generation of the conventional three-phase DC motor. FIG. 6 is a waveform diagram for explaining the principle, FIG. 6 is a back electromotive waveform diagram for explaining the operation of the first embodiment of the three-phase DC motor of the present invention, and FIG. 7 is a back electromotive waveform for the operation explanation of the second embodiment of the motor of the present invention. It is a figure. 1,2 …… 3-phase DC motor, C …… Core, salient poles …… c _{1 to} c
₁₅ , L ... Winding (coil), M ... Magnet, N ...
Number of slots, P ... Number of magnetic poles, Y ... Yoke, g ... Air gap.

Claims (2)

[Claims] 1. A three-phase DC motor having a field magnet portion including a magnet (M) and a yoke (Y), and an armature portion including a core (C) and windings (L _{1 to} L ₃ ). In the field part, the magnet (M) is a P-field magnetic pole (M ₁ ~ M
p), arranged at equal angular intervals on the circumference of the yoke (Y), and the armature part has N cores (C) with three-phase windings (L _{1 to} L ₃ ). It has salient poles (c _{1 to} cn), is arranged at equal intervals on the circumference, is fixed or rotatable with respect to the field magnet, and has magnetic poles (M _{1 to} Mp) and salient poles (c). _{1 to} cn) means a combination of the number P of poles of the field magnetic poles (M _{1 to} Mp) and the number N of salient pole portions (c _{1 to} cn) P = 2 (4n + 3), N = 3 (2n + 1) (N is a natural number), and the least common multiple of the pole number P of the field magnetic poles (M _{1 to} Mp) and the number N of the salient pole portions (c _{1 to} cn) is equal to N × P. 2. The three-phase windings (L _{1 to} L ₃ ) are arranged such that windings for one phase are alternately arranged in the salient pole portions (c _{1 to} cn). The three-phase DC motor according to claim 1, which is continuously wound around N / 3 salient pole portions.