JPH0773432B2 - Motor control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor control device capable of smoothly switching from speed control to current control or vice versa during operation of an electric motor.

[Conventional technology]

When transporting a long material such as roll paper or steel strip to another place, such as a winder, many transport rolls are used.In this case, an electric motor that drives each transport roll is appropriate. If not controlled, the long material will sag between the transport rolls and wrinkles will be generated on the long material, or a large tension will be applied to the long material and the long material will stretch or be cut. This will cause inconvenience.

FIG. 2 is a model diagram showing the relationship between the position of the long material and the control mode of each conveying roll. Since the long material designated by reference numeral 2 is conveyed from right to left in the arrow direction, first of all, The case where the carrier roll 3 and then the second carrier roll are passed is shown.

In FIG. 2 (a), the long material 2 is transported by the first transport roll 3, but has not arrived at the second transport roll 4, and at this time, the first transport roll 3 The second conveying roll 4 is operating in the speed control mode to convey the long material 2 at a predetermined speed, and the second conveying roll 4 has a long peripheral speed in order to alleviate a shock when the long material 2 is bitten. The speed is controlled so as to match the conveying speed of the scale 2.

FIG. 2B shows a state in which the long material 2 is caught in the second transport roll 4, and the first transport roll 3 still sends the long material 2 by speed control. When the transport roll 4 also performs the speed control operation, both the transport rolls 3 and 4 interfere with each other and cannot be controlled.
Switches to the current control mode for torque control operation.

FIG. 2C shows a state in which the long material 2 has passed through the first transport roll 3 and the second transport roll 4 is maintained at the target value for the transport speed of the long material 2 until the current control operation. Since it is difficult to do so, it will be returned to the speed control mode. The first
The transport roll 3 continues to operate in the speed control mode as it is in preparation for the arrival of the next long material 2.

FIG. 2D shows a state in which the long material 2 has also come out of the second transport roll 4, and both the transport rolls 3 and 4 are operating in the speed control mode.

FIG. 3 is a circuit diagram showing a conventional example realizing the control mode shown in FIG.

In the conventional circuit shown in FIG. 3, the first conveyor roll 3 that conveys the long material 2 is driven by the first motor 5 and operates at a constant speed, but drives the second conveyor roll 4. The second motor 8 is controlled as follows. Note that reference numeral 6
Is an AC power supply, and the operation control of the second motor 8 is performed by phase-controlling the AC power from the AC power supply 6 by the thyristor device 7.

That is, the speed target value signal N set by the speed setter 11
A speed adjustment circuit composed of a proportional-plus-integral calculator for calculating the deviation between ^* and the actual speed value signal N from the speed transmitter 12 which is connected to the second motor 8 and detects the speed. When input to 13, the speed adjusting circuit 13 outputs a control signal that makes the input deviation zero, so that this control signal and the actual current value signal I of the second motor 8 obtained by the current detector 14 Is calculated, and the deviation is input to the current adjusting circuit 15 composed of a proportional-plus-integral calculator, and a control signal for making the input deviation zero is taken out from the current adjusting circuit 15 to the thyristor device 7 described above. The thyristor device 7 is controlled in phase.

When the long material 2 is in the state shown in FIG. 2 (A), that is, when the long material 2 is not yet bitten by the second transport roll 4, the normally open contact 21
Since A is in the open state and the normally closed contact 21B is in the closed state, the limiter installed on the output side of the speed adjustment circuit 13
The output signal of 25 is limited by 25 so as not to exceed the sum of the current target value signal I ^* set by the current setting device 24 and the current correction signal ΔI set by the current correction setting device 23. Since the value of I ^* + ΔI is sufficiently larger than the current limit value of the second motor 8, the second motor 8 is operating in the speed control mode.

Next, the state of FIG. 2B, that is, the second transport roll 4
When a long material is bitten into, the normally closed contact 21B is opened and the limiter 25 acts so that the output signal of the speed adjustment circuit 13 does not exceed the value of the current target value signal I ^*.
Since 21A is closed, the speed correction signal ΔS set by the speed correction setter 22 is added to the speed target value signal N ^* and input to the speed adjustment circuit 13.

That is, when the second motor 8 is in the current control mode in the state shown in FIG. 2B, the speed adjustment circuit 13 is saturated and the limit value of the output signal thereof is changed to change the speed section circuit. The output signal of 13 is used as the current target value signal.

[Problems to be Solved by the Invention]

As described above, the second motor 8 switches from the speed control mode to the current control mode in accordance with the position of the long material 2, but if the long material 2 leaves the first transport roll 3, The second motor 8 has to be switched to the speed control mode again.

By the way, in the current control mode, since the speed adjustment circuit 13 is in the saturated state, it is impossible to shift to the speed control mode until the saturation is released, and therefore, the shift to the speed control mode is completed. Until the time, the speed of the second motor 8 fluctuates.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to smoothly and quickly switch an electric motor operating in the current control mode to the speed control mode without causing speed fluctuations.

[Means for Solving the Problems]

In order to achieve the above object, the electric motor control device of the present invention provides a signal for controlling the deviation between the speed target value signal of the electric motor driving the transport roll and the actual speed value signal fed back from the electric motor to zero. The output of the current adjusting means is provided with a speed adjusting means for outputting and a current adjusting means for outputting a signal for controlling the deviation between the output signal of the speed adjusting means and the actual current value signal fed back from the electric motor to zero. In a motor control device for operating the electric motor in speed control operation or current control operation according to a signal, it is set to a value larger than the current limit value of the electric motor during speed control operation of the electric motor, and at a predetermined value during current control operation. A current limit adjusting means for inputting a deviation between the switched current target value signal and the speed adjusting means output signal, and an output of the current limit adjusting means. Lower limit value limiting means for limiting the lower limit value of the signal to zero, a circuit for feeding back the output signal of the lower limit value limiting means means to the input side of the speed adjusting means, and a memory means for storing the output signal of the lower limit value limiting means means. When,
A means for adding the output signal of the memory means to the speed target value signal during a period from when the material is bitten into the carrier roll driven by the electric motor until it exits, and a carrier roll also driven by the electric motor. A means for adding a constant value to the speed target value signal is provided during a period from when the conveyed material is bitten to when the conveyed material comes out.

[Action]

The present invention, when switching the electric motor operating in the current control mode to the speed control mode, by applying the actual speed signal of the electric motor immediately before the end of the current control as the speed target value signal to the current adjusting means, It is intended to suppress the occurrence of speed fluctuation when the current control mode is changed to the speed control mode.

〔Example〕

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

In FIG. 1, a first transport roll 3 for transporting the long material 2 in the arrow direction (that is, right to left), a first motor 5 for driving the same, a second transport roll 4 and a second for driving this.
The functions of the motor 8, the AC power supply 6 for supplying electric power to the second motor 8 and the thyristor device 7 are the same as in the case of the conventional example circuit shown in FIG.
Further, a speed setting device 11, a speed transmitter 12, a speed adjusting circuit 13, a current detector 14, a current adjusting circuit 15, a normally open contact 21A, a normally closed contact 2 which are installed to control the second motor 8.
Since the functions of 1B, the speed correction setting device 22, the current correction setting device 23, and the current setting device 24 are also the same as those of the conventional example circuit already described in FIG. 3, their description will be omitted.

In the present invention, the inverting circuit 31 that inverts the output signal of the speed adjusting circuit 13, the current target value signal I ^* , or the deviation of the output signal of the inverting circuit 31 from the current target value signal I ^* or the current correction value ΔI added to this I ^* And a current limit adjusting circuit 32 configured by a proportional-plus-integral calculator that inputs this deviation, a limiter 33 that limits the lower limit value of the output signal of this current limit adjusting circuit 32 to zero, and this lower limit limiter 33. A circuit for feeding back the output signal ΔN to the input side of the speed adjustment circuit 13, and a speed correction memory for storing the output signal ΔN of the lower limit limiter 33.
34 and a normally open contact 35 for adding the output signal of the speed correction memory 34 to the target speed value signal N ^* .

The operation of the present invention is as follows. That is, FIG. 2 (a)
In the state shown in (1), the control of the second motor 8 for driving the second transport roll 4 is performed with the normally open contacts 21A and 35 open and the normally closed contact 21B closed, so the current target value signal I ^*
Is added with the current correction signal ΔI, and I ^* + Δ
The value of I is larger than the limiting current of the second motor 8. On the other hand, the output of the speed adjusting circuit 13 is usually a value smaller than this limiting current, so the output of the current limiting adjusting circuit 32 is always set to zero by the lower limit limiter 33, and therefore the feedback to the speed adjusting circuit 13 is performed. The value of ΔN is also zero, and the deviation between the speed target value signal N ^* and the actual speed value signal N is input to the speed adjusting circuit 13, and the operation is performed in the speed control mode.

Next, the state of FIG. 2B, that is, the second transport roll 4
When the long member 2 is bitten into, the normally open contacts 21A and 35 are closed, the normally closed contact 21B is open, the current correction signal ΔI is cut off, and the second motor 8 sets I ^* to the current target value. The operation is in the current control mode. At this time, the speed N of the second motor 8 depends on the speed of the first motor 5. That is, since the second conveying roll 4 is connected to the first conveying roll 3 by the long material 2, the peripheral speeds of both the conveying rolls 3 and 4 and the conveying speed of the long material 2 have the same value, and therefore the second Motor 8
The actual speed value N and the target speed value N ^* are substantially equal.

By closing the normally open contacts 21A and 35, the speed correction signal .DELTA.S is added as a new input to the speed adjusting circuit 13. At this time, the actual speed value signal N and the desired speed value signal N ^* are substantially equal. Since it is a value, the output of the speed adjusting circuit tries to reach the maximum value instantaneously, but the current limiting value adjusting circuit 32 works to suppress the output to the target current value I ^* .

Further, if the output of the speed adjusting circuit 13 becomes smaller than the current target value signal I ^* , the output ΔN of the current limiting adjusting circuit 32 also becomes small, but the speed adjusting circuit 13 has this ΔN.
Has been input excessively, the output again tries to increase toward the maximum value. However, the output of the speed adjusting circuit 13 is suppressed to the target current value I ^* again by the action of the current limit adjusting open circuit 32. Thus speed adjustment circuit 13
In response to a change in the output of V.sub.2 or a change in the current target value I ^* , the speed target value is corrected, and the current of the second motor 8 can be controlled to the target value I ^* .

In FIG. 2C, that is, at the moment when the long material 2 leaves the first transport roll 3, the current correction signal ΔI is added to the current target value I ^* by closing the normally closed contact 21B, and the second motor 8
It becomes a value larger than the limiting current of. Therefore, the output of the current limit adjustment circuit 32 is always zero due to the lower limit limiter 33, so that the current limit adjustment circuit 32 does not function and the second motor 8 operates again in the speed control mode.

On the other hand, ΔN, which is the output of the current limit adjustment circuit 32 immediately before the long material 2 passes through the first transport roll 3 and the current control mode ends, is stored in the speed correction memory 34, and the speed target value signal N is stored therein. ^* Is added to obtain a new speed target value. Therefore, even when the second motor 8 (for driving the second transport roll) shifts from the current control mode to the speed control mode because the long material 2 comes out of the first transport roll 3, the peripheral speed of the second transport roll 4 is also changed. Does not change, so that the conveying speed of the long material 2 is maintained at a constant value.

Further, in the state of FIG. 2D, that is, when the long material 2 leaves the second transport roll 4, the normally open contacts 21A and 35 are opened, and the speed of the second transport roll 4 is the original speed target. Value N ^*
Will follow.

〔The invention's effect〕

According to this invention, when the electric motor operating in the current control mode is switched to the speed control mode, the speed target value immediately before the end of the current control mode is replaced with the actual speed value. It is possible to suppress the occurrence of speed fluctuations in the electric motor at the time of switching to the control mode, and it is possible to achieve the effect of smoothly and quickly shifting to the speed control mode.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a model diagram showing the relationship between the position of a long material and the control mode of each transport roll, and FIG. 3 is shown in FIG. It is a circuit diagram showing a conventional example which has realized the control mode shown. 2 ... Long material, 3 ... First transport roll, 4 ... Second transport roll, 5 ... First motor, 6 ... AC power supply, 7 ... Thyristor device, 8 ... Second motor, 11 ...... Speed setter,
12 …… Speed transmitter, 13 …… Speed adjustment circuit, 14 …… Current detector, 15 …… Current adjustment circuit, 21A, 35 …… Normally open contact, 21
B …… Normally closed contact, 22 …… Speed compensation setter, 23 …… Current compensation setter, 24 …… Current setter, 25 …… Limiter, 31…
… Inversion circuit, 32 …… Current limit adjustment circuit, 33 …… Lower limiter, 34 …… Speed correction memory.

Claims (1)

[Claims] 1. A speed adjusting means for outputting a signal for controlling a deviation between a speed target value signal of an electric motor for driving a conveying roll and an actual speed value signal fed back from the electric motor, and an output of the speed adjusting means. And a current adjusting means for outputting a signal for controlling the deviation between the signal and the actual current value signal fed back from the electric motor to zero, and the electric motor is subjected to speed control operation or current control operation according to the output signal of the current adjusting means. In the electric motor control device, a current target value signal that is set to a value larger than the current limit value of the electric motor during the speed control operation of the electric motor and is switched to a predetermined value during the electric current control operation and the speed adjusting means output Current limit adjusting means for inputting a deviation from the signal and lower limit value limiting means for limiting the lower limit value of the output signal of the current limit adjusting means to zero A circuit for feeding back the output signal of the lower limit value limiting means means to the input side of the speed adjusting means, a memory means for storing the output signal of the lower limit value limiting means means, and a material to be conveyed on a conveying roll driven by the electric motor. Means for adding the output signal of the memory means to the speed target value signal from the time when the material is bitten to the time when the material is bited, and a time period when the material to be carried is bited out of the material to be carried by the carrier roll driven by the electric motor. And a means for adding a constant value to the speed target value signal.