JPH07322690A - Load-balance control method for motor in process line of metal strip - Google Patents

Abstract

PURPOSE:To suppress the increase of the load of a motor, whose output capacity is small, and to keep the load balance between the motors by giving the command so that the corresponding excessive load is loaded on the motor having the large-capacity output when the load of the motor having the small-capacity output becomes excessive. CONSTITUTION:A payoff reel 2 is driven by a motor 7 of large-capacity output. A helper roll 5b is driven with a motor 8 of small-capacity output. Thus, a metal strip S is continuously processed. When the load of the motor 8 having the small-capacity output becomes excessive in the processing, the command is given so that the corresponding excessive load is loaded on the motor 7 of large-capacity output. Thus, the increase of the load of the motor 8 of small- capacity output is suppressed, and the balance of the loads among the motor 7-9 can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load balance control method for an electric motor in a metal strip process line.

[0002]

2. Description of the Related Art Conventionally, a plurality of electric motors having large and small capacities are arranged and used in a process line for continuously processing metal strips, and their load balance is theoretically calculated. Tension and acceleration of
In consideration of bend loss and the like, it is general to individually give a current command to each electric motor for control.

An example of load balance control of the entry side equipment of the tandem cold rolling mill will be described with reference to FIG. As shown in the figure, the metal strip (hereinafter simply referred to as “strip”) S supplied to the tandem cold rolling mill 1 is rewound from the payoff reel 2 and wound on the tension reel 3 after rolling. In order to weld the preceding material and the following material with the machine 4, the payoff reel 2
A looper 5, a bridle roll 6 and the like are arranged between the tandem cold rolling mill 1 and the tandem cold rolling mill 1. The looper 5 includes a plurality of deflector rolls 5a, a helper roll 5b, and a looper car 5c.

Here, the drive system of these entry side facilities will be described. The payoff reel 2 is driven by a payoff reel drive motor 7 having a large capacity output, and the helper roll 5b is driven by a helper roll drive motor 8 having a small capacity output. Also, the looper car 5c is a looper car drive motor 9 with a small capacity output.
By driving the winch 5d with, the forward / backward operation is performed via the wire 5e.

The pay-off reel drive motor 7 is a comparison calculator.
Based on the current command I _S1 given to 71, it is controlled via the electric motor control device 73 by the current signal from the current controller 72. At this time, the load current I _L1 from the motor controller 73 is detected by the current detector 74 and fed back to the comparison calculator 71. Further, similarly, the helper roll drive motor 8 uses the current command I _S2 to compare the calculator 81 and the current controller.
82, the load current I _L2 is controlled via the motor control device 83.
Is detected by the current detector 84 and fed back. Further, the looper car driving motor 9 is also controlled by the current command I _S3 via the comparison calculator 91, the current controller 92, and the motor controller 93, and the load current I _L3 is fed back by the current detector 94.

The current commands I _S1 , I _S2 , I _S3 individually given to the payoff reel drive motor 7, the helper roll drive motor 8 and the looper car drive motor 9 are obtained by theoretical calculation as described above, and On the basis of,
In the normal case, the load balance of each electric motor is controlled without any problem. It should be noted that the comparison calculator 7 which has the above-mentioned current control function
1, 81, 91, current controller 72, 82, 92, as shown,
It is housed integrally in the control panel 10, but in some cases, it is adopted by software that is created by using a programmable logic controller (PLC), for example.

[0007]

However, in the prior art as described above, since the speed control of one continuous strip S is performed by a plurality of electric motors, for example, a payoff reel drive electric motor having a large capacity output. In the case of a line with disturbance such as an error in the control accuracy of 7 or a rolling mill for shape correction (for example, a skin pass mill) in the middle, the error of the load is a motor of small capacity output such as helper roll. And its load increases,
In the worst case, it may trip and stop.

The present invention solves the problems of the prior art as described above, and the increase of the load in the line is given as a current command to the motor side of large capacity output, whereby the motor of small capacity output is provided. It is an object of the present invention to provide a load balance control method for an electric motor in a process line of a metal strip, which suppresses an increase in the load of the electric motor and keeps the load balance between the electric motors.

[0009]

SUMMARY OF THE INVENTION The present invention controls load balance when continuously processing a metal strip in a process line in which at least one motor having a large capacity output and at least one motor having a small capacity output are arranged. The process line of the metal strip, wherein when the load of the electric motor of small capacity output becomes excessive, a command is given to load an excessive amount of the electric motor to the electric motor of large capacity output. Is a load balance control method for the electric motor in.

[0010]

[Operation] According to the present invention, by using the feedback of the load current on the small capacity output electric motor side, an excessive load applied to the small capacity output electric motor side is applied to the large capacity output electric motor side as a current command. By doing so, it is possible to absorb the large-capacity output on the electric motor side. As a result, it is possible to reduce the load on the electric motor side having a small capacity output, and it is possible to balance the loads among the electric motors as a whole.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention. The same members as those in the conventional example are designated by the same reference numerals and the description thereof is omitted. As shown in the figure, the target load value I _S0 and the load current I _L2 of the small capacity output helper roll drive motor 8 are input to the comparison calculator 11, and the comparison calculation is performed based on the following equation (1).
The excess current deviation ΔI _S (where ΔI _S >
0) is output to the load control unit 12.

ΔI _S = I _L2 −I _S0 (1) In the load control unit 12, the input current deviation ΔI _S is subjected to proportional-integral control processing to produce a large-capacity output payoff reel drive motor. 7 to the comparison calculator 71. Then, in the comparison calculator 71, a new current command I _S1 ′ is calculated based on the following equation (2), and the current controller 72 and the motor controller are
The load current of the pay-off reel drive motor 7 is increased via 73.

I _S1 ′ = I _S1 −I _L1 + ΔI _S (2) As a result, the helper roll drive motor 8 with a small capacity output is obtained.
Since the excessive load generated in the control system is moved as the load of the control system of the payoff reel drive motor 7 of large capacity output, the load of the helper roll drive motor 8 of small capacity output is reduced, There is no risk of tripping.

An example of changes over time in the load currents of the payoff reel drive motor 7 and the helper roll drive motor 8 is shown in FIG. FIG. 2 (a) shows the case where the conventional method is applied, and at time t ₁ when the strip entry speed is increased, the load current on the helper roll side increases and is in an overload state. However, the load current on the pay-off reel side has hardly changed.

On the other hand, the method of the present invention is applied to FIG.
, The load current on the helper roll side hardly changes, and the load current on the payoff reel side increases. As a result, it can be seen that the excessive load on the helper roll side was given to the payoff reel side. In addition, the above-mentioned embodiment was described for the inlet side equipment of the tandem cold rolling mill,
It goes without saying that the present invention is not limited to this, and can be similarly applied to a continuous process line in which looper equipment such as a conditioning line is provided.

Further, the case of one large capacity output electric motor and one small capacity output electric motor has been described as an example. However, even when a plurality of electric motors are arranged, the priority order should be taken into consideration. Can be similarly applied by.

[0017]

As described above, according to the present invention,
In a continuous process line in which at least one large-capacity output electric motor and one small-capacity output electric motor are arranged, an excessive load applied to the small-capacity output electric motor side is absorbed by the large-capacity output electric motor side. Since the load on the motor side with a small capacity output can be reduced to prevent trip accidents etc. in advance, stable operation of the line is possible and the load balance between the motors is always kept good, It is possible to configure a control system that is resistant to disturbance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 (a) is a characteristic diagram showing the change over time of the load current of each motor when the conventional method is applied, and FIG. 2 (b) shows the change over time of the load current of each motor when the method of the present invention is applied. It is the characteristic diagram shown.

FIG. 3 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 1 tandem cold rolling mill 2 payoff reel 3 tension reel 5 looper 5a deflector roll 5b helper roll 5c looper car 7 payoff reel drive motor 8 helper roll drive motor 9 looper drive motor 10 control panel 11 load calculator 71, 81 , 91 Comparator 72, 82, 92 Current controller 73, 83, 93 Motor controller 74, 84, 94 Current detector S Metal strip (strip)

Claims (1)

[Claims] 1. A method for controlling a load balance when continuously processing a metal strip in a process line in which at least one motor having a large capacity output and at least one motor having a small capacity output are arranged. A load balance control method for an electric motor in a process line of a metal strip, wherein when a load of the electric motor of capacity output becomes excessive, a command is given to load an excessive amount of the electric power to the electric motor of large capacity output.