JP2000209898A - Controller for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for motor which can prevent the creak of gears even under a condition such that the load of a DC motor becomes smaller and is controlled with a zero current. SOLUTION: A controller for motor is provided with a level detector for detecting the level of a current feedback signal from a current detector 13, which detects the current of a DC motor 5. The detector 24 detects a negative value, when the current value of the motor 5 becomes a fixed value or smaller. The negative output signal of the detector 24 is added with respect to a tension control amplifier 23 as a correct signal to reduce a reference tension signal 21. Consequently, the tension between the rolls of sections 1 and 2 is reduced, and the load of the motor 5 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation in the vicinity of zero current where a motor in a paper machine repeats power running and regeneration.

[0002]

2. Description of the Related Art A conventional motor control device will be described with reference to FIG. Here, the target is a paper machine, and a thyristor leonard device that controls a DC motor will be described as an example. In the paper machine line, when controlling the tension between section 1 and section 2 and both sections to be constant, the roll of section 1 is driven by a DC motor 5 via a gear, and the roll of section 2 is driven by a DC motor 8. Each is driven via a gear. The DC motor 5 is a converter 4 that can rectify the AC power supply 3 in the forward and reverse directions with a control rectifier. The DC motor 8 is the converter 7 that can rectify the AC power supply 6 with a control rectifier in the forward and reverse directions.
, Each has been uproar.

The DC motor 5 compares and controls the speed reference signal 9 and the speed feedback signal from the speed detector 10 and executes speed control with a speed control amplifier 11.
1 is a current reference signal, is limited by a current limiting circuit 12, is compared and controlled by a current feedback signal from a current detector 13, and is current controlled by a current control amplifier 14. Similarly, the DC motor 8 compares and controls the speed reference signal 15 and the speed feedback signal from the speed detector 16 to execute speed control by the speed control amplifier 17, and the output of the speed control amplifier 17 is the current reference signal. The current is limited by the current limiting circuit 18, compared and controlled by the current feedback signal from the current detector 19, and controlled by the current control amplifier 20. Further, a tension reference signal 2
1 is compared with the tension feedback signal from the tension detector 22, the tension is controlled by the tension control amplifier 23, and this output is input to the speed control amplifier 17 as a speed correction signal, and the tension corresponding to the tension reference signal 21 is obtained. DC motor 8
The speed is corrected. Note that the current limiting circuit can limit both forward and reverse directions.

[0004]

However, the above-mentioned conventional motor control device has the following problems. That is, the roll driven by the DC motor 5 through the gear is pulled through the material from the section 2 by the tension setting plant of the subsequent section 2, so that the load on the DC motor in the section 1 is reduced and the current is reduced to zero. In the case of controlling, the current of the DC motor is frequently switched between normal and reverse. The direction of torque of the DC motor is frequently switched, and the teeth frequently move in the forward direction and the reverse direction until the teeth of the gears mesh with each other, so that a gear noise occurs.
This gear noise can damage the gear and, if continued, lead to gear damage.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a motor control device that prevents gear noise even when the load on the DC motor is reduced and control is performed at zero current. And

[0006]

According to a first aspect of the present invention, there is provided a first drive device for controlling the speed of a roll of a first section via a first electric motor, and A second drive device for controlling the speed of the roll of the second section located downstream of the section via a second electric motor so as to constantly control the tension of the material between the first section and the second section; And a tension adjusting means for reducing the tension of the material based on the current value of the first electric motor. According to the present invention, the power running operation of the preceding section can be performed by lowering the tension between the sections, and gear noise can be prevented.

According to a second aspect of the present invention, there is provided a first drive device for controlling the speed of a roll of a first section via a first electric motor, and a second drive device located downstream of the first section.
The section rolls through the second electric motor to the first
A motor having a section and a second drive device for speed-controlling the tension of the material between the second sections to be constant, wherein the first drive is performed based on a current value in the first motor. A current limiting circuit for setting a current limiting value of the motor to zero is provided. According to the present invention, by setting the current limit value on the regeneration side of the preceding section to zero, gear noise can be prevented by preventing the regenerating operation of the preceding section from being performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. 1, the same reference numerals as those in FIG. 3 indicate the same elements. In the present embodiment, a level detector 24 for detecting the level of the current feedback signal from the current detector 13 for detecting the current of the DC motor 5 is provided. This level detector 24 outputs a negative value when the current value of the DC motor 5 becomes equal to or less than a certain value. This output signal is added to the tension control amplifier 23 so as to reduce the tension reference signal 21 as a correction signal. As a result, the tension between the rolls of the sections 1 and 2 is reduced, and the operation of the DC motor 5 is increased. The level detector 24 starts operating after the DC motor 5 operates.

Next, the operation will be described in detail. Consider a case where the tension reference signal 21 is increased from the state where the DC motor 5 is in the power running operation, and as a result, the DC motor 5 becomes lightly loaded.

When the tension reference signal 21 is increased,
By comparison with the tension feedback signal from the tension detector 22, (tension reference signal)> (tension feedback signal). The control signal from the tension control amplifier 23 increases before the tension reference signal 21 increases, and is input to the speed control amplifier 17 as a command to increase the speed. The speed of the DC motor 8 increases, the tension between section 1 and section 2 increases, and section 1
Rolls driven by gears by the DC motor 5 of the second section 2 are pulled through the material from the rolls which are disturbed by gears by the DC motor 8 of the section 2 at the subsequent stage.

As a result, when the load on the DC motor 5 in section 1 decreases and the current becomes low (for example, Ism), the current (Is
m) is detected by the level detector 24, and the level detector 24
, A negative signal (a signal for reducing the tension reference signal) is input to the tension control amplifier 23 as a correction signal.

The tension between the sections 1 and 2 is reduced, and it is possible to prevent the current of the DC motor 5 from falling below zero. The power running operation of the DC motor fiber 5 can be continued while preventing gear noise.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a current limit adjuster 25 for detecting the level of the current feedback signal from the current detector 13 for detecting the current of the DC motor 5 is provided.

The current limit adjuster 25 includes a DC motor 5
Is a circuit for outputting a signal to the current limiting circuit 12 of the DC motor 5 so that the current limit value on the regenerative side becomes zero when the current value becomes equal to or less than a certain value.

Next, the operation of the above configuration will be described. Similar to the first embodiment, a case is considered where the tension reference signal 21 is increased from the state in which the DC motor 5 is in power running operation, and as a result, the DC motor 5 becomes lightly loaded.

When the tension reference signal 21 is increased,
By comparison with the tension feedback signal from the tension detector 22, (tension reference signal)> (tension feedback signal). The control signal from the tension control amplifier 23 increases before the tension reference signal 21 increases, and is input to the speed control amplifier 17 as a command to increase the speed. The speed of the DC motor 8 is increased and section 1
And the tension between the section 2 and the section 2 is increased, and the roll driven by the DC motor 5 of the section 1 via the gear pulls through the material from the roll driven by the gear by the DC motor 8 of the subsequent section 2. Phenomenon occurs.

As a result, when the load on the DC motor 5 in section 1 decreases and the current becomes low (for example, Ism), the current Ism of the DC motor 5 from the current detector 13 is detected by the current limit adjuster 25. Then, the current limit value on the regenerative side of the DC motor 5 is reduced from the current limit adjuster 25 to zero. According to the present embodiment, since the signal is input to current limiting circuit 12, even if the current of DC motor 5 becomes zero, the operation can be continued without going to the negative (regeneration) side.

Although a DC motor and a thyristor leonard device have been described as examples here, it goes without saying that the same effects can be obtained according to the present invention even when an AC motor and an inverter device are applied. Also,
The present invention is similarly applicable not only to a paper machine but also to a system for controlling tension such as a winder.

[0019]

As described above, according to the present invention, the power running operation is continued without switching the current to the regenerative side by monitoring the current value of the DC motor, so that the gear noise can be prevented. It becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional motor control device.

[Explanation of symbols]

 1, 2 Section 3, 6 AC power supply 4, 7 Converter 5, 8 DC motor 9, 15 Speed reference signal 10, 16 Speed detector 11, 17 Speed control amplifier 12, 18, Current limiting circuit 13, 19 Current detector 14 , 20 current control amplifier 21 tension reference signal 22 tension detector 23 tension control amplifier 24 level detector 25 current limit adjuster

Claims (2)

[Claims] 1. A first drive device for controlling the speed of a roll of a first section via a first motor, and a roll of a second section located downstream of the first section via a second motor. A control device for controlling the speed of the motor so as to control the tension of the material between the first section and the second section to be constant, based on a current value in the first motor. A control device for an electric motor, further comprising a tension adjusting means for reducing a tension of the material. 2. A first drive device for controlling the speed of a roll of a first section via a first motor, and a roll of a second section located downstream of the first section via a second motor. A control device for controlling the speed of the motor so as to control the tension of the material between the first section and the second section to be constant, based on a current value in the first motor. A motor control device, further comprising a current limiting circuit for setting a current limit value of the first motor to zero.