JPH04286A - Speed controller for motor - Google Patents

Abstract

PURPOSE:To shorten the delay time of starting and start a motor more smoothly by a method wherein a current reference, necessary until the motor is started actually, is provided from a starting current reference setting means to a current control circuit as a lamp function separately upon starting the motor while the current reference is switched into another current reference from an original speed control circuit by the actual starting of the motor. CONSTITUTION:When a starting command S is outputted, a starting control circuit 14 outputs a 'H' signal to put a changeover switch 13 ON. An input signal for an operating amplifier 11 is a starting current reference IR1, given from a starting current reference setter 12, and an outputted current reference IR is obtained as a lamp function increased linearly while a motor is started when the current of the motor has arrived at a current reference necessary for the starting of a DC motor. Then, the changeover switch 13 is returned through the starting control circuit 14, the input signal of the operating amplifier 11 is switched into a speed difference (NR-NF) and the title controller is operated in accordance with a control characteristic or a Pl operation type speed control circuit based on a current reference of an output value immediately before switching.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a speed control circuit including an integral element that calculates a current reference for matching the actual speed of a motor with a set speed, and a current reference The present invention relates to a speed control device for a motor, including a current control circuit that controls the current of the motor according to the present invention.

(Prior Art) A speed control device for a DC motor is a control device that controls the speed of a DC motor in order to operate the DC motor at a set speed. As an example of such a control device, a conventional speed control device applied to rolling equipment is shown in FIG.

In the rolling equipment shown in Fig. 3, the (n-1) stand 2
The strip material 1 that has passed through the n-th stand 3 is wound up by a winding machine 4. Further, as a motor control device, a control device for controlling the speed of the DC motor 5 that drives the n-th stand 3 is representatively illustrated here. The speed of the DC motor 5 is controlled by an Iristor converter 6.

DC motor 5 detected by speed detector (TG) 7
The actual speed Np is fed back to the speed control circuit 8. The speed control circuit 8 compares the fed-back actual speed N with a separately given speed reference NR, and determines the deviation between the two, that is, the speed deviation (N).

-NR) is outputted as a current reference (2) that makes zero, and the sirisk converter 6 is controlled via the current control circuit 9 in accordance with the current reference (2).

In such a conventional speed control device, the speed control circuit 8 is generally configured to include an integral element, and is configured, for example, of a PI (proportional-integral) operation type. The gain of the speed control circuit 8 is set so that the speed response of the speed control loop of each stand is the same in order to stabilize the speed response of the speed control loop and maintain speed balance with other stands during acceleration and deceleration of the rolling line. is set to be.

On the other hand, in rolling equipment, the moment of inertia of the DC motor, the moment of inertia of the driven stand, the capacity of the DC motor, etc. differ depending on the stand, so if the speed response of each speed control loop is made the same, the gain of the speed control circuit 8 On the contrary, it will differ depending on the stand.

FIG. 4 shows how the actual speed N and the current reference IR change when the speed reference NR, which increases like a ramp function when starting the motor, is input to the speed control circuit 8. Fourth
In the apparatus shown in the figure, when the rolling line starts from a stopped state and accelerates, even if the speed reference NR rises from zero like a ramp function, the current reference IR becomes a quadratic function due to the PI characteristic of the speed control circuit 8. , and increases only very gradually at first. This tendency becomes particularly noticeable when the gain of the speed control circuit 8 is small. Until time Tl, the starting current value R8, which is sufficient to generate the torque necessary to start the DC motor 5, is not reached, and therefore the DC motor 5 cannot be started.

When the current of the DC motor 5 reaches the starting current value IRS at time T1, the DC motor 5 finally starts to start, and thereafter accelerates rapidly and the actual speed N reaches the speed reference NR at time T2.

(Problem to be Solved by the Invention) In such a speed control device, when the rolling line accelerates from a stopped state (NF-0) as shown in FIG. 4, there is a startup delay in the DC electric motor a15, Moreover, once the startup starts -1, the speed reference NR will continue until the speed reference NR is reached.
Accelerates rapidly at an acceleration rate that exceeds the rate of change of speed standard NR.
After reaching the speed reference NR, the vehicle accelerates in accordance with the speed reference NR.

In this control device, the torque required for acceleration/deceleration of the winder 4 is calculated from the speed reference NR of the n-th stand 3, and the torque is applied to the current control circuit 9 of the DC motor 5 for driving the winder 4. It is given as a current reference, and the tension of the strip material 1 on the exit side of the n-th stand 3 is maintained at the set tension.

The actual speed NF of the DC motor 5 is based on the speed reference NR as shown in the figure.
Since it responds with a time delay, a tension greater than the set tension is applied to the strip material 1 until time T1, and the generated torque from time TI to time T2 is the acceleration calculated based on the speed reference NR. The tension applied to the strip material 1 is therefore much smaller than the set tension. Such tension fluctuations in the strip material 1 cause the strip material 1 to break.

Furthermore, between the (n-1)th stand 2 and the nth stand 3, the gain of the speed control circuit provided for each drive motor is different, and the gain required to start each drive motor is different. There are also some differences in starting torque. Therefore, in general, there is a slight difference in activation timing between the (n-1)th stand 2 and the nth stand 3, and the acceleration rates are also different. From this point as well, the (n-th
1) The tension applied to the strip material 1 between the stand 2 and the n-th stand 3 varies greatly, causing the strip material 1 to break.

SUMMARY OF THE INVENTION An object of the present invention is to provide a speed control device for an electric motor that can reduce startup delay time as much as possible and start the motor more smoothly.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the speed control device of the present invention includes a starting current reference setting means for giving the rise of the current reference at the time of motor starting as a ramp function, and a current control device at the time of motor starting operation. Switching that applies the current reference set by the starting current reference setting means to the circuit until a value required for actual starting of the motor is reached, and then switches to provide the current reference set by the speed control circuit. It is characterized by providing means.

(Function) The cause of the delay in starting the motor is that the speed control circuit is configured to include an integral element, and the gain of the speed control circuit is low, so the current reference output from the speed control circuit does not actually start the motor. This is due to the fact that it takes time to reach a value that generates the starting torque necessary to do so. Therefore, when starting the motor, instead of providing the current reference necessary for the current control circuit until the actual motor start from the speed control circuit that includes an integral element, a starting current reference setting means is used to separately provide a current reference to the current control circuit. By giving the current as a function and switching to the current reference from the original speed control circuit at the actual start of the motor, smooth startup can be achieved while minimizing the delay in starting the motor.

(Example) Hereinafter, the present invention will be described in further detail with reference to FIG. 1 showing an example.

In FIG. 1, the same symbols as in FIG. 3 indicate corresponding circuit elements or signals. In the apparatus shown in FIG. 1, the speed control circuit includes a speed signal input section 10 which receives an actual speed N and a speed reference NR, and has a calculation resistor for calculating a deviation between the two, that is, a speed deviation (NR-NF). , the speed deviation (NR-N
, ) based on P! It consists of an operational amplifier section 11 that performs calculations. The operational amplifier unit 11 includes an amplifier 110 and a resistor 111 inserted in series for PI calculation in its feedback circuit.
and a capacitor 112. This speed control circuit is no different from the speed control circuit 8 shown in FIG. A starting current reference setter 1 that outputs a starting current reference R1 of a constant size according to the present invention for this speed control circuit.
2, a changeover switch 13 for switching the input to the operational amplifier section 11 between the output of the speed signal human power section 10 and the output of the starting current reference setting device 12, and a start-up control circuit 14 for controlling on/off of this change-over switch 13. It is provided. The start control circuit 14 outputs an "H°" signal by receiving the start command S, and outputs an "L" signal by receiving the start detection signal R indicating that the electric motor 5 has actually started starting. The signal of the actual speed NF detected by the speed detector 7 can be used as the detection signal R. The changeover switch 13
An operation coil 130 that is energized by the ° double signal and deenergized by the L ° double signal, a normally closed contact 131 interposed between the speed signal input section 10 and the operational amplifier section 11 , and a starting current reference setter 12 and the operational amplifier section 11, and the operational amplifier section 1, which is originally a PI operation type.
1 has a normally open contact 133 for short-circuiting the resistor 111 of the feedback circuit to form a Miller integrating circuit.

The operation of the apparatus shown in FIG. 1 will be explained below with reference to FIG. 2.

When the start command S is issued at time 10, the start control circuit 14 outputs an "H" signal and turns on the changeover switch 13. As a result, the contact 121 turns off and the switches 122 and 123 turn on. .

In this state, the input signal to the operational amplifier 11 is not the speed deviation (NR-N, ) but the starting current reference IR signal given from the starting current reference setter 12, and the operational amplifier 11 functions as a mirror integrator. The circuit is in a functioning state. Therefore, the current reference (2) output from the operational amplifier 11 is obtained as a ramp function that increases linearly and relatively steeply as shown in FIG. When the current reference value IR8 is reached, the electric motor 5 starts (starts rotating). At time T1□, motor 5
When the start-up actually starts, the changeover switch 13 is reset via the startup control circuit 12, and the contacts 132 and 133 are returned to the OFF state, and the contact 133 is also returned to the ON state. As a result, the starting current reference setter 12 is disconnected from the speed control circuit via the contact 132, and the original PI operation type speed control circuit is constituted by the speed manual section 10, the contact 131, and the operational amplifier section 11. In this way, the input signal of the operational amplifier 11 is switched to the speed deviation (NR-N, ), and
The operational amplifier section 11 returns to its original PI operation type, and thereafter operates in accordance with the control characteristics of a PI operation type speed control circuit based on the current reference which is the output value immediately before switching. It turns out. Actual speed N at time T1□
, reaches the speed reference NR, and thereafter the motor speed is controlled to follow the speed reference NR.

As described above, by increasing the current reference lR in a ramp-like manner in a short time when starting the motor, the current reference necessary for starting the motor is provided to the current control circuit 9 in a short time, so that the motor 5 can be set to a speed reference. It is possible to start up quickly and smoothly without much delay compared to NR.

In this way, the time delay when starting the electric motor can be shortened as much as possible, and breakage of the strip material 1 when starting the electric motor can be prevented.

Although the above description has been made regarding a speed control device for a DC motor, the present invention can also be applied to speed control for an AC motor. Moreover, although the above description is for the case where the present invention is applied to rolling equipment, it goes without saying that the present invention can be applied to other uses as well.

〔Effect of the invention〕

According to the present invention, by providing a current reference that transiently increases gradually in a ramp function manner to the current control circuit at the time of starting the motor, it is possible to almost eliminate the start-up delay time of the motor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a motor control device according to the present invention, and FIG. 2 is a time chart showing a speed signal, a current reference, and an on/off state of a starting switch when controlled by the device shown in FIG. FIG. 3 is a block diagram showing a rolling equipment and a conventional speed control device for controlling it, and FIG. 4 is a time chart showing a speed signal and current reference when controlled by the device shown in FIG. 5... DC motor, 6... Thyristor converter,
7...Speed detector, 8...Speed control circuit, 8A...
- Speed signal input section, 8B... operational amplifier section, 9... current control circuit, 10... speed signal input section, 11... operational amplifier section, 110... amplifier, 111... resistor ,1
12... Capacitor, 12... Starting current reference setter, 13... Starting switch, 130... Operating coil,
131... Normally closed contact, 132.133... Normally open contact, 14... Starting control circuit. Qi 1 figure

Claims (1)

[Claims] A speed control device for a motor, comprising: a speed control circuit including an integral element that calculates a current reference for making the actual speed of the motor match a set speed; and a current control circuit that controls the current of the motor according to the current reference. a starting current reference setting means for giving the rise of a current reference at the time of starting the motor as a ramp function; 1. A speed control device for an electric motor, comprising: switching means for applying a current to a current reference value set by the speed control circuit until the current reaches a value necessary for starting the motor, and then switching to apply a current reference set by the speed control circuit.