JPS6329502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating electric machine, and particularly to a three-phase induction motor with a pole number changeable structure having a three-phase armature winding that can have a pole number changeable ratio of 1:7.5.

In general, in order to improve the accuracy of stopping positions and alleviate shocks during stops, machine tool feeders, cargo handling machines, etc. are first slowed down from a high speed side to a low speed side, and then are braked. . Also, many methods are used that utilize regenerative braking of the induction motor when switching from high speed to low speed. For this purpose, methods have been adopted such as using a pole number converting motor that can change the rotational speed of the drive motor in two or more stages, or using two motors with different numbers of poles.

However, the method of using two electric motors with different numbers of poles not only requires a large installation area but is also disadvantageous in terms of cost. On the other hand, when using a pole change motor, it is generally necessary to have a large speed ratio of 1:4 or 1:8 for the above-mentioned applications, so each pole number of turns is required on one armature core. Measures are taken to create lines. For example, if a rotation speed corresponding to 4-pole and 30-pole windings is required, a 4-pole winding and a 30-pole winding are applied to one armature core, and when operating with 4 poles, a 30-pole winding is applied. When operating with 30 poles, the method is to leave each of the 4 pole windings idle without energizing them.

However, in this method, not only the utilization rate of the armature winding is poor, but also the dimensions of the armature core become large, which poses a problem in terms of miniaturization of the motor.

An object of the present invention is to provide a pole-changing three-phase induction motor having an armature winding that achieves a constant large pole ratio of 1:7.5 with one type of winding.

In order to achieve the above object, in the present invention, the armature winding of a three-phase induction motor is wound with a single layer concentric winding in a double star connection with the number of poles P _A pole, and each phase The coil is divided into P _A /2 groups, and each of the coils divided into P _A /2 groups consists of an odd number of coils, and each of the coils divided into P _A /2 groups is connected. By changing the single star connection, the first coil group whose polarity changes by alternating the first coil group and the second coil group whose polarity does not change are arranged alternately in each phase to obtain the number of P _A poles x 7.5 times. It has a winding.

An example of the present invention will be described below with reference to the drawings. Here, an example will be described in which the number of armature grooves is 36, the number of poles P _A =4 poles, and the number of poles P _B =30, and the number of poles can be changed. FIG. 1 shows an example of the connection configuration of three-phase armature windings in a pole-changing three-phase induction motor according to the present invention. In the figure, the solid line is the U phase, the dashed line is the V phase, and the broken line is the W phase coil. , and U ₁ , U ₂・V ₁ , V ₂・W ₁ , W ₂ are U・V・
The W-phase terminals are shown respectively. In the figure,
Each phase coil of U, V, and W is divided into P _A /2 (=2) pieces and wound, and each phase is wound with
The coils are divided into P _A /2 groups and consist of an odd number (3 pieces) of large coil a, medium coil B, and small coil c, and each phase of the same phase is divided into P _A /2 groups. The coils also consist of an odd number (three) of a large coil a', a medium coil b', and a small coil c'. The small coil c', large coil a', and medium coil b are connected in series to form a first coil group, and the large coil a, small coil c, and medium coil b' are connected in series to form a second coil group. A group of coils is formed and these are arranged alternately in each phase. By changing the connection of the coils for one pole per phase, the polarity of the first coil group changes and the polarity of the second coil group remains unchanged. Further, FIG. 2b shows a specific wiring configuration in FIG. 3.

In the three-phase armature winding configured as described above,
First, at high speed, if each phase terminal U ₂ , V ₂ , W ₂ is connected to the power supply, and U ₁ , V ₁ , W ₁ is short-circuited, a double star connection configuration as shown in Figure 2a is obtained, and the first As can be seen from the figure, the conductor arrangement shown in FIG. 3 results in a four-pole magnetomotive force distribution as shown in FIG. 4. In other words, the third
The figure shows the arrangement of conductors wound in a 4-pole concentric winding (stored in the 4-pole armature groove), which is different from the conductor arrangement of the commonly used concentric armature winding. There is no place. In the figure, U, is U
The phase conductor indicates that the current direction is opposite to that of U. V and W indicate V and W phases, and indicate that the current direction is opposite to that of V and W, respectively. In addition, Figure 4 shows the instantaneous magnetomotive force distribution where the U-phase current is 1 and the V and W-phase currents are each -1/2 in the winding arrangement shown in Figure 3, and shows the magnetomotive force of four poles. becomes.

On the other hand, at low speeds, if each phase terminal U ₁ , V ₁ , W ₁ is connected to the power supply and U ₂ , V ₂ , W ₂ is opened, a single star connection configuration as shown in Fig. 2b is obtained. The arrangement of the conductors is as shown in Figure 5, and the magnetomotive force is also the same as in the case of 4 poles, when the U-phase current is 1 and V and W are each -1/2 of the value. 6
As shown in the figure, there are 30 poles.

As mentioned above, in the pole change three-phase induction motor of this embodiment, the single-layer concentric winding is wound in a double star-connected single-layer concentric winding with the number of poles _P The coil is divided into P _A /2 (=2) groups, and the coil divided into P _A /2 groups is a large coil,
Medium coil and small coil a, b and c, a' and b'
It consists of an odd number (3) of c′, and one of them is P _A /
Of the coils divided into two groups, the first coil group c', a', and b whose polarity changes by changing the connection, and the second coil group a, c, and b' whose polarity does not change are connected to each phase. The armature windings are arranged alternately and the number of poles is 7.5 times P _A poles by changing the single star connection.

Therefore, by reversing the current direction of the first coil group, the number of poles P _B =30 is obtained, which is 7.5 times the number of P _A poles (4 poles), that is, P _A =P _B =4:30=1: A high pole ratio of 7.5 can be obtained by changing the connection of one winding, making extremely effective use of windings and eliminating waste, and reducing the size of the armature core. As a result, the motor itself can be made more compact than the conventional two-stage winding pole number conversion motor, which is economically advantageous. Also,
Windings with a smaller number of poles can be manufactured very easily in the same manner as conventional concentric windings. Furthermore, since the pole number ratio is as high as 1:7.5, it is possible to switch from high speed to low speed and utilize regenerative braking, making it extremely advantageous for machine tools and feed motors.

It should be noted that the present invention is not limited to the above embodiments, but can also be implemented as follows.

(1) In the above embodiment, P _A = 4 poles, P _B = 30 poles, and the number of slots in the iron core is 36.
Not limited to this, for example, P _A = 8 poles, P _B =
The same applies to devices with 60 poles and 72 core slots.

(2) In the above embodiment, the winding connection is 2× at high speed.
Although the case of 1×Y has been described as an example for Y and low speed, it goes without saying that connections such as 2×Y and 1×Δ are also possible.

As explained above, according to the present invention, it is possible to provide a highly reliable pole change three-phase induction motor equipped with an armature winding that obtains a constant large pole number ratio of 1:7.5 with one type of winding. .

[Brief explanation of the drawing]

FIG. 1 and FIGS. 2a and 2b are schematic configuration diagrams showing one embodiment of the present invention, and FIGS. 3 to 6 are diagrams for explaining the operation of the present invention. U, V, W...3 phases, U ₁ , U ₂ , V ₁ , V ₂ ,
W ₁ , W ₂ ...Each phase terminal, a, b, c, a', b', c'...
coil.

Claims (1)

[Claims] 1 The armature winding of a three-phase induction motor is wound with a single layer concentric winding in a double star connection with a number of poles P _A , and each phase coil is divided into two groups P _A /2. And the coils divided into two groups each consist of an odd number of coils, and the corresponding portion is P _{A /}
Of the coils divided into two groups, the first coil group whose polarity changes by changing the connection and the second coil group whose polarity does not change are arranged alternately for each phase, and by changing the single star connection, the P _A pole is created. A pole number conversion three-phase induction motor characterized by having an armature winding that obtains a pole number x7.5 times.