JPH06335283A - Motor controller - Google Patents

Abstract

PURPOSE:To provide a motor controller for suppressing a slip by controlling the rotational speed of the motor, that is, the rotational speed of a roll when slip is generated between a strip and the roll. CONSTITUTION:When slip is generated between a strip 1 and a roll 2, a rotational speed signal NFBK increases, resulting in NFBK>NC. In this case, when the comparison difference N(=NFBK-NC) exceeds a certain value, a deadband 14 sends an output, a current reference compensation signal can be obtained through multiplycation of a certain gain G in the limiter and a new current reference signal IREF can be obtained by subtracting a current reference compensation signal, in the subtraction unit 17, from the current reference signal outputted from an arithmetic unit 12. As a result, the current to be applied to the motor 3 is reduced (becomes lower than a total mechanical loss), resulting in drop of the rotational speed. Since the rotational speed of the roll 2 is reduced, the slip can be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for an electric motor used for driving a tension bridle roll of a process line, a stretcher of a tension leveler, a pinion stand of a tension leveler, and controlling the tension of a strip (steel plate). It is about.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional motor control device. In the figure, 1 is a strip traveling in the direction of the arrow shown in the figure, 2 is a roll for applying tension to the strip 1, 3 is an electric motor for driving the roll 2 via a speed reducer 4, and 5 is a rotational speed of the electric motor 3. _Is a speed detector that detects the rotation speed and outputs a rotation speed signal N _FBK .

Further, 6 is a calculator for obtaining a rotation speed calculation value of the electric motor 3 corresponding to the line speed reference signal V *, and 7 is a speed limiting bias BI for current control to the rotation speed calculation value.
An adder for adding AS to obtain a rotation speed reference signal N _REF of the electric motor 3, and 8 is a rotation speed signal N _FBK detected by the speed detector 5 and a rotation speed reference signal N _REF obtained by the adder 7. Based on the speed controller (SC) for controlling the speed of the electric motor 3, 9 is a limiter for limiting the electric current of the electric motor 3, 10 is a current controller (CC) for controlling the electric current of the electric motor 3, 11 is the electric motor 3 It is a thyristor conversion device (THY) for driving. further,
Reference _{numeral 12} is a calculator that calculates the current reference signal I _REF of the electric motor 3 from the tension of the strip, that is, the torque of the roll 2.
The symbols T ₁ and T ₂ input to the calculator 12 are the entrance tension and the exit tension of the roll 2.

Next, the operation will be described. In the motor control device having the above-described configuration, the strip 1 wound around the roll 2 connected to the electric motor 3 via the speed reducer 4 is controlled by controlling the current of the electric motor 3 to control the speed of the strip 2. The torque applied to the strip 1 is controlled, and the tension applied to the strip 1 is controlled.

The specific control will be described in detail. The rotation speed reference signal N _REF of the electric motor 3 is calculated by the calculator 6 and the adder 7 as (Equation 1). N _REF = {V * / (π · D · γ)} + BIAS (Equation 1) where π: Circumferential ratio D: Diameter of roll 2 γ: Reduction ratio of reducer 4 V *: Line speed Reference signal (speed of strip 1)

Assuming that there is no slip between the strip 1 and the roll 2, the speed of the strip 1 and the peripheral speed of the roll 2 are the same. Therefore, the rotation speed reference signal N _REF
Is the bias BI for speed limitation based on the rotation speed signal N _FBK.
It increases by the amount of AS. When (N _REF > N _FBK ), the speed controller 8 is normally PI (proportional-integral) controlled, and the output of the speed controller 8 is saturated.
At that time, the saturation value is limited by the limiter 9 and given to the current controller 10, and the electric motor 3 is brought into the current control state.

The limit value for the limiter 9 is calculated and given by the calculator 12 as the equation (2) as the current reference signal I _REF . I _REF = K · (D / 2γ) · (T ₂ −T ₁ ) + I _L + I _C (Equation 2) where K: torque constant of the electric motor _IL : electric motor 3, speed reducer 4, roll 2 Current of mechanical loss I _C : Current of inertia compensation of roll 2 (during acceleration / deceleration)

Next, when a slip occurs between the strip 1 and the roll 2, the tension is not secured, so that the tension component current of the first term of (Equation 2) becomes the acceleration torque component current of the roll 2 and is accelerated. As a result, the rotation speed reference signal N _{REF of} the electric motor 3 and the rotation speed signal N _FBK match, and the current control state is changed to the speed control state. Also, strip 1
And the peripheral speed of the roll 2 are increased by the latter by the speed limiting bias BIAS.

[0009]

Since the conventional motor control device is constructed as described above, when a slip occurs between the strip 1 and the roll 2, the speed of the electric motor 3,
That is, since there is no function for reducing the speed of the roll 2, once slip occurs, there is a problem in that it cannot be recovered. That is, continuously, "Strip 1
The speed is less than the peripheral speed of the roll 2, and the roll 2 rotates faster by the speed limiting bias BIAS, and the strip 1 cannot be given a predetermined tension.

The present invention has been made in order to solve the above-mentioned problems of the conventional example, and when slip occurs between the strip and the roll, the speed of the electric motor, that is, the speed of the roll 2 is changed. An object of the present invention is to obtain a control device for an electric motor that suppresses the slip and thereby suppresses the slip.

[0011]

The motor control device according to the present invention controls the torque applied to the roll by controlling the current to the motor driving the roll around which the strip is wound. In a control device for an electric motor configured to control applied tension, slip detection means for obtaining a signal corresponding to a slip between the roll and the strip, and a current to the electric motor is corrected based on an output of the slip detection means. And a correction means for performing the correction.

[0012]

In the motor control device according to the present invention, the slip detecting means detects the slip state between the strip and the roll, and the correcting means adjusts the electric current of the electric motor in accordance with the slip state so that the electric motor, that is, the roll. Reduces speed and suppresses slip.

[0013]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating a control device for an electric motor according to a first embodiment. In FIG. 1, the same reference numerals as those in the conventional example shown in FIG. 4 indicate the same parts, 1 is a strip that advances in the direction of the arrow shown in the figure, 2 is a roll for applying tension to the strip 1, and 3 is a speed reducer for the roll 2. An electric motor 5 driven via 4 is a speed detector that detects the rotational speed of the electric motor 3 and sends out a rotational speed signal N _FBK .

Reference numeral 6 is a calculator for converting the line speed reference signal V * into a corresponding rotation speed calculation value of the electric motor 3, and 7 is a rotation speed calculation value to which a bias BIAS for speed limitation during current control is added. The adder 8 obtains the rotation speed reference signal N _REF of the electric motor 3, and 8 is based on the rotation speed reference signal N _FBK detected by the speed detector 5 and the rotation speed reference signal N _REF obtained by the adder 7. A speed controller (SC) for controlling the speed of the electric motor 3, 9 is a limiter for limiting the electric current of the electric motor 3, 10 is a current controller (CC) for controlling the electric current of the electric motor 3, and 11 is for driving the electric motor 3. It is a thyristor converter (THY). Further, reference numeral 12 is a calculator for calculating the current reference signal I _REF of the electric motor 3 from the tension of the strip, that is, the torque of the roll 2, and reference numerals T ₁ and T ₂ input to the calculator 12 are used.
Is the tension on the inlet side and the tension on the outlet side of the roll 2.

As a new code, 13 is the rotational speed signal N _FBK of the electric motor 3 and the calculated rotational speed N of the electric motor 3 when there is no slip between the strip 1 and the roll 2.
_C is a subtractor for obtaining a comparison difference, 14 is a dead band that outputs an output when the comparison difference exceeds a certain value, 15 is a limiter that limits the output of the dead band 14, and 16 is a predetermined value for the output of the limiter 15. Is a gain for obtaining a current reference correction signal, and 17 is the output of the calculator 12 and the gain 16
Is a subtractor that subtracts the current reference correction signal from to obtain a new current reference signal. Here, the rotation speed calculation value N _C of the electric motor 3 is calculated by the calculator 6 as (Equation 3). N _C = V * / (π · D · γ) (Equation 3)

Next, the operation will be described. Now, when there is no slip between the strip 1 and the roll 2, the rotational speed calculation value N _C and the rotational speed signal N _FBK are substantially equal to each other, and N _FBK
≈N _C holds. Therefore, at this time, the input of the dead band 14 is 0, the output is 0, the output of the limiter 15 is 0,
Therefore, the current reference correction signal is also 0. That is, as shown in FIG. 2, the input / output characteristics of the dead band 14 are 0 when the difference between the rotation speed signal N _FBK and the rotation speed calculation value N _C is smaller than a certain value, and the output exceeds a certain value. And the output is sent.

Next, when a slip occurs between the strip 1 and the roll 2, the rotation speed signal N _FBK increases and N
_FBK > N _C. At this time, the comparison difference _ΔN (= N _FBK
Exceeds a certain value -N _C), deadband 14 sends the output, is multiplied by the gain G which is passed through the limiter 15 current reference correction signal is obtained, is output from the arithmetic unit 12 by subtractor 17 A new current reference signal I _REF is obtained by subtracting the current reference correction signal from the current reference signal. As a result, the current to the electric motor 3 decreases (when it is less than the total mechanical loss), the speed decreases, and the speed of the roll 2 decreases, so that the slip is suppressed.

It should be noted that the purpose of the limiter 15 is to operate only in the direction of decreasing the current and to prevent it from operating vice versa, as shown in the input / output characteristics of FIG. The dead band value of the dead band 14 is set smaller than the speed limiting bias BIAS. The purpose of the dead band 14 is that the rotational speed signal N _FBK and the rotational speed calculation value N _C do not completely match due to the influence of calculation error and other mechanical factors, and some difference is ignored.

Therefore, according to the above-described embodiment, the conventional motor control device is provided with the subtractor 13 and the dead band 14 for detecting the slip between the strip 1 and the roll 2.
Since the current reference correction signal is obtained by multiplying the gain through the limiter 15 and the gain 16 to correct the current reference signal, the current of the electric motor 3 is adjusted according to the slip state between the strip 1 and the roll 2. Is adjusted, the speed of the electric motor 3, that is, the speed of the roll 2 is suppressed, so that the slip can be suppressed.

In addition to the above embodiment, the present invention is different in the tension leveler stretcher and the pinion stand only in the calculation formula of the rotational speed calculation value of the electric motor. The same effect is obtained. Further, the same circuit configuration can be applied to a control device in which the current reference signal I _REF is directly input to the current controller 10.

[0021]

As described above, according to the present invention, the torque applied to the roll is controlled by controlling the current to the electric motor that drives the roll around which the strip is wound, so that the tension applied to the strip is controlled. In a control device for an electric motor to be controlled, a slip detecting means for obtaining a signal according to a slip between the roll and the strip, and a correcting means for correcting a current to the electric motor based on an output of the slip detecting means Since, by adjusting the electric current of the electric motor according to the slip state between the strip and the roll, the speed of the electric motor, that is, the speed of the roll is suppressed, and thus the effect of suppressing slip can be obtained. Play.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a control device for an electric motor according to a first embodiment of the present invention.

FIG. 2 is an input / output characteristic diagram of the dead band 14 of FIG.

FIG. 3 is an input / output characteristic diagram of a limiter 15 of FIG.

FIG. 4 is a configuration diagram showing a conventional controller for an electric motor.

[Explanation of symbols]

 1 Strip 2 Roll 3 Electric Motor 5 Speed Detector 9 Limiter 10 Current Controller 13 Subtractor 14 Dead Band 15 Limiter 16 Gain 17 Subtractor

Claims (1)

[Claims] 1. A control device for an electric motor, wherein a torque applied to the roll is controlled by controlling an electric current to an electric motor that drives a roll around which the strip is wound, thereby controlling a tension applied to the strip. A slip detecting means for obtaining a signal according to a slip between the roll and the strip, and a correcting means for correcting a current to the electric motor based on the output of the slip detecting means are provided. Control device.