JPS5952624B2 - induction motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction motor that can obtain a high power factor even when used at low output by combining the stator windings with Y-connection and Δ-connection during operation.

Conventionally, when pumps and blowers, whose loads mainly change to light loads depending on the season or time of day, are operated without changing their rotational speed, a single electric motor has generally been used.

However, it is known that when operating at a low output below the rated value, efficiency and power factor, which are important characteristics of an electric motor, deteriorate significantly.

Therefore, as a countermeasure to this problem, select a motor with the maximum rating as usual, and avoid the possibility that the motor will have poor characteristics under light loads.
A method that takes care to design a motor that produces the best characteristics in the middle of several types of rated output, and a pole conversion motor that brings the motor rotation speed closer to the required characteristics by changing the connection of the windings. However, each of these methods has problems such as requiring a large amount of materials, consuming a large amount of power, and not always being able to obtain optimal characteristics, making them uneconomical.

On the other hand, conventionally, the Y-△ starting method switches the connection of the motor between Y connection and △ connection in order to perform a reduced voltage start when starting the motor, and a combination of these is called the TD type starting method. There is a connection.

In this TD starting method, half of the windings are Y-connected and the other half are △-connected during starting acceleration, and all windings are △-connected during operation, which reduces starting torque more than the Y-△ starting method. This is a starting method that can be made larger.

Here, the characteristics of Y-Δ starting and TD starting are compared with direct starting as follows.

However, the above-mentioned TD starting method is not for obtaining several types of output from one motor, but is a connection used to reduce the starting current only at the time of starting, and is normally operated with only the △ connection. .

The object of the present invention was made in view of the above-mentioned circumstances, and consists of forming the windings belonging to each phase of the stator into a plurality of winding groups (hereinafter referred to as unit windings), and connecting these windings to each phase. The Y-connection part and the △-connection part are combined as appropriate so that the impedances are equal, and the Y-connection part and the △-connection part are connected to change the ratio to achieve an appropriate magnetic flux density, matching the desired load factor. By getting the output
It is an object of the present invention to provide an induction motor that can maintain a good power factor depending on each output and has a high energy saving effect.

An embodiment of the present invention will be described below with reference to the drawings.

The number of windings in the stator winding of an induction motor is the same as the number of stator grooves in the two-layer winding system, but for reasons of workability, one pole component is wound continuously (two poles or four poles). (Sometimes the minutes are wound continuously).

Therefore, in terms of the number of windings for one phase of the motor, there are a group of continuously wound windings for the number of poles, and a group of windings on the side with the number of poles is connected to a special connection (hereinafter referred to as a mixture of Y connection and △ connection). It has a structure in which the capacity of the motor can be changed arbitrarily using a method (referred to as Y-Δ connection).

As a specific example, a three-phase six-pole induction motor will be described.

It should be noted that the overall components of the induction motor, such as the core frame, rotating shaft, and bearings, are no different from the conventional ones.

The present invention is different in that there are a plurality of windings and in their interconnection, so this point will be mainly explained.

FIG. 1 shows the basic connection. In this example, the induction motor has 18 stator grooves, and the unit windings inserted into each stator groove are denoted by 1. 2. 3. ...
...Add 18.

Thus, the windings formed in one phase consist of six unit windings 1 to 6, and the other phases consist of unit windings 7 to 12.
Furthermore, the other phases each consist of six unit windings, ie, unit windings 13 to 18.

Each phase has three unit windings connected in series to form two series circuits, and these series circuits are connected in parallel.

Therefore, if the voltage applied between the terminals is E, and one impedance in the figure is Z, and there is no effect of magnetic saturation, etc., it is expressed as.Based on this, the capacitance for the case shown in Figure 1 is calculated as follows. is given by

Based on this basic configuration, the present invention allows a Y-Δ connection configuration as shown in FIGS. 2 to 5 by using all windings of the same capacity.

Figure 2 shows the series circuits of unit windings 3 and 5 and 4 and 6 connected in parallel to form a first circuit A1, windings 9, 11 and 10.
and 12 series circuits are connected in parallel to form a second circuit B1,
The series circuits of windings 15 and 17 and 16 and 18 are connected in parallel to form third circuits C1, respectively, and these circuits A1. B1. C1 is connected with a △ connection, and the tops of this △ connection are designated as Ul, vl, and Wl, respectively.

On the other hand, parallel circuit A2 of unit windings 1 and 2, unit windings 7 and 8
Parallel circuits B2 of unit windings 13 and 14 form parallel circuits C2 of J'L, respectively, and these parallel circuits A2°B2. Connect each end of C2 to the top of the △ connection U1. V, , Wl, respectively, and the circuit A1. Form a Y connection via B and C1.

As a result, the circuit configuration shown in FIG. 2 is Y-Δ connected, and the terminals U and V are connected as described above.

When calculating the capacity with E as the applied voltage between W and Z as one impedance, the capacity in FIG. 2 is the same as that of the parallel circuit A2. B2. Connect C2 with △,
Each top U2 of this △ connection. v2. W2 includes the aforementioned first, second, and third circuits A1. B1. This is a configuration in which each end of C1 is connected.

As a result, the circuit configuration in FIG. 3 is Y-Δ connected, and when calculated in the same manner as described above, the capacitance in FIG. 3 is given by:

Figure 4 shows a parallel circuit A3 with unit windings 3, 4, 5, and 6, a parallel circuit B3 with unit windings 9, 10, 11, and 12, and a parallel circuit B3 with unit windings 1.
5, 16, 17, and 18 respectively form a parallel circuit C3, and these parallel circuits A3°B3. Connect C3 to each other.

The top U3 of this △ connection. ■3. The above-mentioned parallel circuit A is connected to W3.
2. B2. Connect each end of C2.

As a result, the circuit configuration in FIG. 4 is Y-Δ connected, and when the capacitance is calculated in the same manner as described above, the circuit configuration in FIG. 4 becomes as follows.

In Figure 5, unit windings 3, 4, 5, and 6 form a series circuit A4, unit windings 9, 10, 11, and 12 form a series circuit B4, and unit windings 15, 16, 17, and 18 form a series circuit C4. and form these series circuits A4, B4, respectively. Connect C4 to each other.

The top U4 of this △ connection. V4. The above-mentioned parallel circuit A is connected to W4.
2. B2. Connect each end of C2.

As a result, the circuit configuration in FIG. 5 is Y-Δ connected, and when the capacitance is calculated in the same manner as described above, in FIG. 5, the following is obtained.

Therefore, as shown in Figs. 2 to 5, the windings are
- By changing the connection to △ connection and using it, you can achieve 100%, 60%, 42.9%, 8% even though it is one electric motor.
It can be seen that several types of outputs such as 5.7% and 27.3% can be obtained.

Although windings of the same capacity are used in the above example, the motor output capacity can be changed in a manner other than that described above by changing the ratio of the Y-connected portion and the Δ-connected portion and by changing the number of parallel circuits.

Here, the following Table 1 shows the combinations in the cases of FIGS. 1 to 5 using the above-mentioned six-pole machine as an example.

Therefore, as is clear from the combination table in Table 1 above, the number of combinations of the number of Y-connections, the number of Δ-connections, and the number of parallel circuits increases.

As an example, if the Y node has two windings, the combinations are as follows: 2 types of changes for Y connection, and 5 changes for △ connection.
There are 10 combinations depending on the seed multiplier.

The theoretical number of this combination is as follows. That is, the number of poles is 6
If the number of outputs is doubled, 65 types of combinations will be possible.

Next, the experimental results will be explained using Table 2.

Table 2 shows the electric power of 6 poles 7.5kW (400V-60Hz
) is the characteristic measurement value when the above connection change is made.

It can be seen that good characteristics can be obtained.

For reference, when a general 7.5 kW electric motor is used at 5.5 kW without any connection changes, the efficiency is -86.5 (%
).

The power factor was 74 (%), and when used at 3.7 kW, the efficiency was 83% and the power factor was 65 (%).

This also shows that in the present invention, a high power factor can be obtained even when using low power.

This reduces reactive power, resulting in power savings, and
It has the advantage of being able to operate with low starting current and low current.

In the table of the above examples, the capacity is 100% and 60%.

42.9% Y-△ connection, 100% and 75% respectively
.

50%, but in order to improve this point, we changed the number of turns in the Y connection part and the △ connection part to change the capacity allocation, and changed the capacity by changing the number of continuous unit windings. It is also possible.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but as described above without changing the gist of the invention, the present invention includes windings belonging to each phase of the stator in a plurality of unit winding groups. These are appropriately combined so that the impedance of each phase is equal, and are configured into a Y connection part and a △ connection part, and are connected to change the ratio of the Y connection part and △ connection part to obtain the desired load factor. Since the appropriate output is obtained, optimum characteristics can be obtained for each of several types of rated output, and an induction motor suitable for power saving, material saving, and energy saving can be provided.

[Brief explanation of drawings]

Figure 1 is a basic configuration diagram of the winding of the induction motor of the present invention, Figure 2
5 to 5 are circuit configuration diagrams in which the windings are connected in different Y-Δ connections. 1 to 18...Unit winding, U, V-W...
・Terminal, A1-A4. B1-B4. C1-C4...
...Each circuit, U1~U4゜■1~■4. W1~W4...
・・・・Each top of the △ connection.

Claims (1)

[Claims] In an induction motor with a 13-phase connection, the windings belonging to each phase of the stator are formed into multiple winding groups, and these are appropriately combined so that the impedance of each phase is equal to the Y connection part and the △ connection part. 1. An induction motor comprising: a terminal for changing the ratio of the Y-connection portion and the Δ-connection portion so as to obtain an output commensurate with a desired load factor.