JP2023001772A - motor controller - Google Patents

Abstract

To control rotational speed of a motor by performing correction to right polarity to speed reference even when there is an effect of disturbance on a torque system.SOLUTION: A motor controller concerning one embodiment comprises: a speed control unit which controls rotational speed of a motor via an inverter by outputting torque reference of the motor on the basis of a speed command to be speed reference of the motor; a torque control unit which controls torque of the motor via the inverter by outputting a torque command to the motor on the basis of the torque reference output by the speed control unit; a current control unit which outputs a current command to the inverter to control a frequency of power to be supplied to the motor by the inverter on the basis of the torque command output by the torque control unit; and a torque command correction unit which corrects the speed command to the speed control unit by performing correction for multiplying the torque command output by the torque control unit by drooping gain.SELECTED DRAWING: Figure 2

Description

The present invention relates to a motor control device.

For example, rolling mills used in steel plants and the like often use inverters that control the rotational speed of motors (synchronous motors) by controlling the frequency of electric power supplied to the motors.

Further, there is known a synchronous motor drive system in which a speed controller converts a speed deviation, which is the difference between a speed reference and the actual speed of the motor, into a torque reference, and controls an inverter based on the torque reference (see, for example, patent documents). 1).

Furthermore, by performing drooping control with a set drooping rate (drooping gain) on the result of converting the speed deviation, which is the difference between the speed reference and the actual speed of the motor, to the torque reference, speed Techniques for adjusting in a direction to eliminate the deviation are known.

Japanese Patent Application Laid-Open No. 2014-239612

As described above, in recent years, speed control including torque system control has been put to practical use in order to control the rotational speed of a motor. However, if torque system corrections such as inertia compensation, mechanical loss compensation, and in-liquid compensation are overcompensated, the speed control works to decrease the torque in the negative direction.

In other words, in conventional motor rotation speed control, drooping control acts only on the torque reference converted from the speed deviation. Drooping sometimes worked on (reverse polarity).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to control the rotation speed of a motor by correcting the polarity to the correct polarity with respect to the speed reference even when the torque system is affected by disturbance. It is an object of the present invention to provide a motor control device capable of

A motor control device according to an aspect of the present invention is a motor control device that includes an inverter that drives a motor and that controls the rotation speed of the motor. By outputting a torque reference, a speed control unit for controlling the rotation speed of the motor via the inverter, and outputting a torque command to the motor based on the torque reference output by the speed control unit, a torque control unit for controlling the torque of the motor via the inverter; and a torque control unit for controlling the frequency of the electric power supplied to the motor by the inverter based on the torque command output by the torque control unit. a current control unit that outputs a current command; and a torque command correction unit that corrects the speed command for the speed control unit by multiplying the torque command output by the torque control unit by a drooping gain. It is characterized by

Further, in the motor control device according to one aspect of the present invention, preferably, the torque command correction unit adjusts the drooping gain so that the drooping gain is increased or decreased according to the operation state of the motor. It is characterized by having a variable coefficient unit for coefficient multiplication.

According to the present invention, even when the torque system is affected by disturbance, the rotational speed of the motor can be controlled by correcting the polarity to the correct polarity with respect to the speed reference.

It is a figure which shows the structural example of a rolling system typically. 1 is a block diagram illustrating the configuration of a motor control device and its peripherals according to an embodiment; FIG. It is a figure which shows the structural example of a speed control part. It is a figure which shows the structural example of a torque control part. It is a figure which shows the structural example of a calculation torque correction|amendment part. It is a figure which shows the structural example of a torque command correction|amendment part.

A motor control device according to one embodiment will be described below with reference to the drawings, taking a motor control device used in a rolling system as an example. FIG. 1 is a diagram schematically showing a configuration example of a rolling system 1. As shown in FIG. As shown in FIG. 1, the rolling system 1 has a hot rolling line 2, a controller 3, and a rolling control device 4, for example.

The hot rolling line 2 has, for example, a heating furnace 20, a roughing mill 21, a finishing mill 22, a water cooling device 23, a cutting machine 24, a winder 25, and the like.

In the hot rolling line 2 , the slab output from the heating furnace 20 is subjected to rough rolling by the rough rolling mill 21 , and the raw material (rolled material) is sent to the finishing rolling mill 22 . In the hot rolling line 2, the rough rolled material is further rolled to a predetermined specification by the finishing rolling mill 22, cooled by the water cooling device 23, and then cut to a predetermined length by the cutting machine 24. Then, the winder 25 winds up.

For example, the roughing mill 21 is provided with a plurality of synchronous motors 21a whose rotational speeds are controlled by a motor control device 5, which will be described later.

The controller 3 is, for example, a PLC (programmable logic controller) or the like, and controls the rolling control device 4 .

The rolling control device 4 includes, for example, a motor control device 5 , and controls each part of the hot rolling line 2 according to the control by the controller 3 . The motor control device 5 includes a drooping correction unit 6 and controls the rotational speed of the synchronous motor 21a.

Next, the motor control device 5 will be further described with reference to FIGS. 2 to 6. FIG. FIG. 2 is a block diagram illustrating the configuration of the motor control device 5 and its periphery according to one embodiment.

As shown in FIG. 2, the motor control device 5 has a speed reference output unit 50, a speed control unit 51, a torque control unit 52, a current control unit 53, an inverter 54, and a drooping correction unit 6. By controlling, the rotational speed of the synchronous motor (motor) 21a is controlled.

The speed reference output unit 50 outputs a speed command regarding the rotation speed of the synchronous motor 21 a to the speed control unit 51 .

As also shown in FIG. 3, the speed control unit 51 calculates the difference between the speed command output by the speed reference output unit 50 and the speed feedback detected as the actual speed of the synchronous motor 21a as a speed deviation. Then, the speed control unit 51 performs PI control by the speed control AMP with respect to the speed deviation, and outputs the speed control final calculated torque (PI control result) to the torque control unit 52 .

The speed control final calculated torque is a torque reference for the torque of the synchronous motor 21a. That is, the speed control unit 51 controls the rotational speed of the synchronous motor 21a via the inverter 54 by outputting the torque reference of the synchronous motor 21a based on the speed command that serves as the speed reference of the synchronous motor 21a.

As shown in FIG. 4, the torque control unit 52 outputs a torque command to the current control unit based on the speed control final calculated torque output from the speed control unit 51 and an external torque auxiliary reference input from the controller 3, for example. 53.

That is, the torque control unit 52 controls the torque of the synchronous motor 21a via the inverter 54 by outputting a torque command to the synchronous motor 21a based on the torque reference output by the speed control unit 51.

Based on the torque command output from the torque control unit 52, the current control unit 53 outputs a current command to the inverter 54 so as to control the frequency of the electric power that the inverter 54 supplies to the synchronous motor 21a.

The inverter 54 drives the synchronous motor 21a while controlling the rotation speed by controlling the frequency of the electric power supplied to the synchronous motor 21a.

The drooping correction unit 6 has a calculation torque correction unit 60 and a torque command correction unit 62, and performs drooping correction.

Specifically, as shown in FIG. 5, the calculated torque correction unit 60 multiplies the speed control final calculated torque output from the speed control unit 51 by a drooping gain related to the torque input from the controller 3, and then Invert and calculate the drooping command.

For example, when a negative speed control final calculated torque is input to the calculated torque correction unit 60, a positive drooping command is calculated.

Further, the calculation torque correction unit 60 multiplies the speed reference input from the controller 3 by a predetermined rate, adds the calculated drooping command, and outputs the speed command to the speed reference output unit 50. .

As shown in FIG. 6 , the torque command correction unit 62 has a variable coefficient unit 620 that multiplies the drooping gain by a coefficient so as to increase or decrease the drooping gain according to the operating conditions of the inverter 54 .

For example, the variable coefficient unit 620 performs coefficient multiplication so as to decrease the drooping gain when the synchronous motor 21a is started, and performs coefficient multiplication so as to increase the drooping gain during normal operation of the synchronous motor 21a.

Then, the torque command correction unit 62 multiplies the drooping gain related to the torque input from the controller 3 by the coefficient multiplied by the variable coefficient unit 620 for the torque command output from the torque control unit 52, and then reverses the result. to calculate the drooping command. Further, the torque command correction unit 62 multiplies the speed reference input from the controller 3 by a predetermined rate, adds the calculated drooping command, and outputs the speed command to the speed reference output unit 50. .

That is, the torque command correction unit 62 corrects the speed command for the speed control unit 51 by multiplying the torque command output by the torque control unit 52 by the drooping gain.

In this manner, the motor control device 5 corrects the torque command output by the torque control unit 52 by multiplying the drooping gain. Correction to the correct polarity can be made to control the rotational speed of the motor.

Each function of the motor control device 5 may be configured partially or wholly by hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array), or may be executed by a processor such as a CPU. It may be configured as a program to

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Rolling system, 2... Hot rolling line, 3... Controller, 4... Rolling control device, 5... Motor control device, 6... Drooping correction part, 20... Reheating furnace 21 Rough rolling mill 21a Synchronous motor (motor) 22 Finishing rolling mill 23 Water cooling device 24 Cutting machine 25 Roll Taker 50 Speed reference output unit 51 Speed control unit 52 Torque control unit 53 Current control unit 54 Inverter 60 Calculation torque correction unit , 62...torque command corrector, 620...variable coefficient unit

Claims (2)

In a motor control device comprising an inverter for driving a motor and controlling the rotation speed of the motor,
a speed control unit that controls the rotation speed of the motor via the inverter by outputting a torque reference of the motor based on a speed command that serves as a speed reference of the motor;
a torque control unit that controls the torque of the motor via the inverter by outputting a torque command to the motor based on the torque reference output by the speed control unit;
a current control unit configured to output a current command to the inverter so as to control the frequency of power supplied to the motor by the inverter based on the torque command output by the torque control unit;
and a torque command correction unit that corrects the speed command for the speed control unit by multiplying the torque command output by the torque control unit by a drooping gain. The torque command correction unit is
2. The motor control device according to claim 1, further comprising a variable coefficient unit that multiplies the drooping gain by a coefficient so as to increase or decrease the drooping gain in accordance with the operating conditions of the motor.

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