JPH066961A - Winding switching system for three-phase induction motor - Google Patents

Abstract

PURPOSE:To provide a winding connecting system for widening the option in the number of windings of three-phase induction motor and realizing optimal output characteristics from low speed to high speed. CONSTITUTION:In the winding switching system of three-phase induction motor for realizing constant output characteristics over wide speed range through switching of winding, each three-phase winding comprises low speed windings (1L, 2L, 3L) including all winding numbers for respective phases of the three- phase induction motor with lead wires being tapped at the opposite ends u, x1, v, y1, w, z1 of each winding and at points x2, y2, z2 of each winding defined by dividing the number of windings at an integer ratio, and high speed windings (1H, 2H, 3H) constituting the winding parts of the low speed winding between one ends u, v, w thereof and the dividing points. A DELTA-DELTA connection system is employed for switching the winding from DELTA connection of low speed winding in low speed region to DELTA connection of high speed winding in high speed region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winding switching system for a three-phase induction motor, and more particularly to a winding switching system for a three-phase induction motor used to drive a machine that requires a constant output over a wide range from low speed to high speed. .

[0002]

2. Description of the Related Art An example of a machine that requires a constant output over a wide range from low speed to high speed is an elevator or a spindle of a machine tool. For driving the spindle of a machine tool, mechanical clutch switching, pole number conversion of a three-phase induction motor, or thyristor Leonard control of a DC motor has been applied according to the speed and output torque required for machining. recent years,
Vector control induction motors that combine vector control inverters and induction motors mainly for NC lathes and machining centers equipped with advanced functions such as ATC (automatic tool change function) and automatic work indexing can also drive the spindle of machine tools. It has come to be applied.

For driving the spindle of a machine tool, a wide range of speed control is required in order to obtain an optimum cutting speed according to various work materials and sizes of the work. In other words, a wide range of constant output control is required in which the spindle of a machine tool performs low-speed machining for large-diameter machining and heavy-duty cutting and high-speed machining for small-diameter machining and light cutting. Therefore, in order to expand the constant output range of the vector control induction motor, a method of switching the winding of the induction motor at a predetermined speed is used.

FIG. 4 is a diagram showing output characteristics of a three-phase induction motor of a winding switching system. Hereinafter, the base velocity will be described with reference to the drawings. The change in output when the windings of the three-phase induction motor for low speed and high speed are switched and operated at 1500 RPM is shown. The dotted line shows the output characteristics of the three-phase induction motor with low-speed windings. The base speed of the low speed winding is 500R
The PM constant output region is 500 to 1500 RPM (constant output range is 1: 3). The solid line shows the output characteristics of a three-phase induction motor with high-speed windings. The base speed of the high speed winding is 15
00 RPM and constant output area is 1500-6000 RPM
(The constant output range is 1: 4). That is 1500R
If switching operation is performed with PM, a wide range of constant output characteristics (constant output range is 1:12) with a base speed of 500 RPM and a constant output region of 500 to 6000 RPM can be obtained. The output from the speed 0 to the base speed linearly increases until it becomes a constant output at the base speed as shown in the figure.

FIG. 5 shows a winding switching system of a three-phase induction motor according to the prior art, FIG. 5 (A) shows a Y-.DELTA. Connection system, and FIG. 5 (B) shows a YY connection system. It is a figure. Winding switching methods for switching the windings of a three-phase induction motor according to the related art between low speed and high speed include a Y-Δ connection method and a Y-Y connection method. According to the Y-Δ connection method, as shown in FIG. 5A, three windings ux, vy, and wz are Y-connected in the low speed region and Δ-connected in the high speed region. This is the method used. According to this method, as shown in Table 1, the number of windings of Y is 1T, 2T, 3T, 4T, 5T in order.
(Where T is a positive integer), the corresponding number of windings of Δ is 1 / √3T, 2 / √3T, 3 / √3, respectively.
T, 4 / √3T, 5 / √3T, and the ratio of the number of windings of low speed to high speed is uniquely determined to be 1: √3.

[Table 1]

Next, according to the Y-Y connection method, as shown in FIG.
As shown in (B) of FIG.
Three windings 1-N, v1-N, and w1-N (reference numerals 31L, 32L, and 33L, respectively, in order) are used in the low speed region, and three windings u2-N, v2-N, and w2-N. This is a method of using two windings (each reference number is 31H, 32H, 33H in order) in the high speed region. According to this method, as shown in (1) of Table 2, when the number of windings of each winding 31H, 32H, 33H in the high speed region is all 1 / √3T, the corresponding winding 31L in the low speed region is , 32L,
The number of windings of 33L is 2 / √3T and 3 / √3 respectively
T, 4 / √3T. Further, as shown in (2) of Table 2, when the number of windings of each winding 31H, 32H, 33H in the high speed region is all set to 2 / √3T, the corresponding winding 31L, 32L, 33L in the low speed region. The number of turns of each is 3 in order
/ √3T, 4 / √3T, 5 / √3T. That is,
The ratio of the number of turns of low speed to high speed is 2: 1, 3: 1, 4: 1,
It has an integer ratio such as 3: 2, 4: 2, 5: 2, and the number of windings is limited to a multiple of 1 / √3.

[Table 2]

[0007]

The winding switching methods of the Y-Δ connection method and the Y-Y connection method according to the prior art described above are combinations of winding switching, and in the Y-Δ connection method, Y is compared with Y. Δ can be selected only for the ratio of the number of windings of 1 / √3, and any combination can be provided in the YY connection method, but the number of windings is limited to an integral multiple of 1 / √3. There are problems that the number of choices is insufficient, the output is insufficient at low speed or high speed, and a winding switching system of a three-phase induction motor having optimum output characteristics cannot be obtained.

In view of the above problems, it is an object of the present invention to further expand the choices of the number of windings of a three-phase induction motor and to provide a winding switching system of a three-phase induction motor having optimum output characteristics. To do.

[0009]

FIG. 1 is a diagram showing a Δ-Δ connection system of a winding switching system of a three-phase induction motor according to the present invention. The winding switching method of the three-phase induction motor of the present invention which achieves the above-mentioned object is a winding switching method of a three-phase induction motor which has a constant output characteristic in a wide range from low speed to high speed by switching the winding. The three-phase winding has windings of each phase at both ends (u, x1), (v, y1), (w, z1) of the winding.
And a division point (x2, y2, z2) that divides the number of windings of each phase by an integer ratio, is used as a lead wire, and a structure is provided outside the frame of the motor, for example, in a terminal box. To do. Low-speed windings ((u-x1), (v-y1), (w-z) including all windings in each phase of the three-phase induction motor
1)) (the respective reference numbers are 1L, 2L, 3L in order) and one end (u,
v, w) to the dividing point, which is a high-speed winding ((u-x2), (v-y2), (w-z2)) (reference numbers 1H, 2H, 3H, respectively). Yes.),
The low-speed winding has a Δ connection in the low-speed region, and the high-speed winding has a Δ-connection in the high-speed region to switch the windings so that three-phase power is supplied to the connection points of the windings of each phase. To configure.

[0010]

In the winding switching system of the three-phase induction motor of the present invention, a dividing point for dividing the total number of windings of each phase by an integer ratio is provided,
In the low speed region, all windings of each phase are used as low speed windings and Δ-connected to supply three-phase power.In the high speed region, the winding from one end of each phase winding to the dividing point is high speed winding. As a result, a constant output is obtained in a wide range from low speed to high speed by the Δ-Δ connection method by connecting the Δ connection and supplying electric power.

[0011]

FIG. 2 is an electrical connection diagram of a winding switching system of a three-phase induction motor according to the present invention. The winding of the motor of each phase is u, x1, x2, v, y1, y2, w, z as lead wires.
Nine pieces 1 and z2 are provided outside the frame of the electric motor, for example, in a terminal box. This winding switching method is named Δ-Δ connection method. In this Δ-Δ connection method, as shown in FIG. 2, three windings of u-x1, v-y1, and w-z1 (that is, 1L, 2L, 3L) are Δ-connected in the low speed region, and u
-X2, v-y2, wz2 three windings (ie,
1H, 2H, 3H) is used as Δ connection in the high speed region. In the figure, reference numeral 21 indicates a three-phase induction motor. The three-phase power supply is input to the vector control inverter 22, and electric power is supplied from the vector control inverter 22 to the three-phase induction motor 21 via the contactors 23 and 24.
In the low speed region, the contactor 23 is closed and 24 is opened so that all the windings are used. In the high speed region, the contactor 23 is opened and 24 is closed, and the windings x1-x2, y1-y2.
z1-z2 are not used.

According to this method, as shown in (1) of Table 3, when the number of windings of each of the windings 1H, 2H, 3H in the high speed region is all T, the corresponding winding IL in the low speed region. , 2
The numbers of windings of L and 3L are 2T, 3T and 4T, respectively. Further, as shown in (2) of Table 3, when the number of windings of each winding 1H, 2H, 3H in the high speed region is 2T,
The corresponding number of windings IL, 2L, 3L in the low speed region are 3T, 4T, 5T, respectively. That is, the ratio of the number of low-speed to high-speed windings is 2: 1, 3: 1, 4: 1, 3:
It has an integer ratio such as 2, 4: 2, 5: 2, and the number of windings is limited to an integral multiple.

[Table 3]

FIG. 3 shows the output characteristics of a three-phase induction motor using various winding switching systems. (A) is a Y-Δ connection system,
(B) is a diagram showing various output characteristics in the YY connection system, and (C) is a Δ-Δ connection system. In the figure, the vertical axis represents the output kw and the horizontal axis represents the rotation speed RPM. (1) to (6) show the relationship between the number of low-speed windings and high-speed windings,
In (A), (1) is 1: 1 / √3 and (2) is 2: 2.
/ √3, (3) has a ratio of 3: 3 / √3, and in (B) and (C), the number of windings at the dividing points is (1) is 2: 1,
(2) is 3: 1; (3) is 4: 1; (4) is 3: 2
(5) shows output characteristic diagrams of the respective three-phase induction motors when the ratio is 4: 2 and (6) is 5: 2.

The output characteristics of the three-phase induction motor of the (A) Y-Δ connection system are as follows: (1) is the base speed in the low speed region at 578 RPM, 1000 RPM is the base speed in the high speed region, and (2) is the low speed at 289 RPM. It becomes the base velocity of the region and becomes the base velocity of the high speed region at 500 RPM, and (3) becomes the base velocity of the low speed region at 192 RPM and 333 RPM.
Indicates that the velocity becomes the base velocity in the high-speed region.

The output characteristics of the three-phase induction motor according to the Y-Y connection method of (B) are as follows: (1) to (3), the base speed in the high speed region is 1000 RPM, and the base speed in the low speed region is (1). 500 RPM, (2) is 333 RPM, (3)
Is 250 RPM, the base speeds in the high speed regions (4) to (6) are all 500 RPM, the base speeds in the low speed region are 333 RPM in (4), 250 RPM in (5), and (6).
Indicates 200 RPM.

The output characteristics of the three-phase induction motor of the (C) Δ-Δ connection system are 1732 RPM for all the base velocities in the high speed region of (1) to (3), and the base velocity in the low speed region is (1). 866 RPM, (2) is 577 RPM, (3)
Is 435 RPM, and the base velocities of the high speed regions (4) to (6) are all 866 RPM, the base velocities of the low speed region are (4) 577 RPM, (5) 433 RPM, (6)
Indicates 346 RPM.

As described above, the Y-Δ connection method alone has very few choices for the number of windings of the three-phase induction motor, and the YY connection method increases the choices, but is still insufficient.
It is understood that by adding the Δ connection method, the choices can be further increased, and thus various output characteristics can be provided.

[0018]

As described above, according to the winding switching system of the three-phase induction motor of the present invention, various output characteristics can be obtained by further increasing the options for the number of windings of the three-phase induction motor. You can select the winding switching method of the three-phase induction motor that is most suitable for the speed control range. Further, by adopting the Δ-Δ connection system, the number of contactors required for switching the winding is two, and the connection is easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a Δ-Δ connection system of a winding switching system of a three-phase induction motor according to the present invention.

FIG. 2 is an electrical connection diagram of a winding switching system of a three-phase induction motor according to the present invention.

FIG. 3 shows output characteristics of a three-phase induction motor using various winding switching systems, (A) is a Y-Δ connection system, and (B) is a Y-Y system.
FIG. 3C is a diagram showing a connection method, and FIG.

FIG. 4 is a diagram showing output characteristics of a three-phase induction motor of a winding switching system.

FIG. 5 shows a winding switching system of a three-phase induction motor according to the prior art, (A) shows a Y-Δ connection system, and (B) shows a Y- system.
It is a figure which shows a Y connection system.

[Explanation of symbols]

 1H, 2H, 3H, 31H, 32H, 33H ... High speed winding 1L, 2L, 3L, 31L, 32L, 33L ... Low speed winding 21 ... Three-phase induction motor 22 ... Vector control inverter 23, 24 ... Contactor

Claims (1)

[Claims] 1. In a winding switching system of a three-phase induction motor, which has a constant output characteristic in a wide range from low speed to high speed by switching windings, the three-phase winding of the three-phase induction motor has both ends of each phase winding. (U, x1), (v, y1), (w, z1) and a division point (x2, y2) obtained by dividing the number of turns of each phase winding by an integer ratio.
z2) is provided with a lead wire, and a low speed winding (1L, 2L, 3L) including all the winding numbers in each phase of the three-phase induction motor, and one end (u, v, high-speed winding (1H, 2H,
3H), and the low-speed winding is Δ-connected in the low-speed region, and the high-speed winding is Δ-connected in the high-speed region to switch the windings to form a Δ-Δ connection, and at the connection point of the windings of the respective phases. A winding switching system for a three-phase induction motor, which is characterized by supplying three-phase power.