JPS6035990A - Speed controller of motor - Google Patents

Abstract

PURPOSE:To suppress the variation of the speed of a motor due to the variation of a load torque to a small value by compensating a feed forward with a load torque calculated by the deviation between a motor current obtained from a current detector and the differentiated value of a speed detector. CONSTITUTION:A speed regulator 1 outputs as a current command value i* a deviation between an actual speed value (n) and a target value n*. A current regulator 2 controls the firing angle of a thyristor converter 3 so that the detected current value (i) becomes equal to a current command value i*. On the other hand, a load torque arithmetic unit 8 simulates an acceleration torque taua by a differentiator 82, simulates the current converted value ia of the acceleration/ deceleration torque taua by a torque current converter 81, obtains a current converted value iL of a load torque by the deviation i-ia to the motor current (i) and adds it to the output of the regulator 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a speed control device for an electric motor, and particularly to a speed control device for an electric motor that suppresses speed fluctuations when load torque fluctuates.

[Prior art and its problems]

In general, this type of control device is controlled so that the actual speed value (detected value) follows changes in the set speed as quickly as possible and matches the set value, and also handles changes in load torque. , it is desirable to prevent the actual speed value from fluctuating. Conventionally, as this type of control device, a speed control device having an armature current control loop (ACR loop) as a minor loop is known. However, in such speed control devices, the response of the control system is determined by the parameters of the speed regulator, so it is difficult to suppress speed fluctuations within a predetermined value when there is a sudden change in load torque, and a certain limit is reached. Therefore, there was a drawback that optimal control was not possible.

Furthermore, as this type of technique, one disclosed in Japanese Patent Laid-Open No. 162894/1983 is known. This estimates the speed of the motor by integrating the detected current value, estimates the load torque by integrating the deviation between the detected speed value and the estimated speed value, and adjusts the speed by using the sum of this and its differential value. However, in this method, the device for estimating the load torque is complicated, making adjustment difficult.

In addition, the present applicant has determined that when the deviation of the motor torque calculated from the differential value of the speed detection value and the current detection value exceeds a predetermined value, a signal is issued to prevent the rolling material from being caught in the rolling mill or to remove the tail end. A rolled material detection circuit has been proposed which is designed to obtain the following, but this is merely a circuit that uses the deviation described above only to determine whether or not the rolled material is being rolled.

[Purpose of the invention]

The present invention has been made in view of the above problems, and an object of the present invention is to simply and inexpensively provide a speed control device for an electric motor that can suppress fluctuations in speed due to fluctuations in load torque.

[Key points of the invention]

This invention was made by focusing on the fact that load torque can be calculated from the deviation between the motor current obtained from a current detector and the differential value of a speed detector, and attempts to perform feedforward compensation using this calculated load torque. It is something to do.

[Embodiments of the invention]

The figure is a block diagram showing an embodiment of the present invention. In the figure, 1 is a speed regulator (A8IL), 2 is a current regulator (A8IL), and 2 is a current regulator (A8IL).
ACR), 3 is a thyristor converter, and 4 is a DC chamber! alJ
L 5 is a speed generator (speed detector), 6 is a current detector,
8 is a load torque calculator.

Note that the load torque calculator 8 includes a torque current converter 81 and a differential element 82. Further, 8 in the figure represents a Laplace operator, TM represents a starting time constant of the electric motor, and φ represents a field element.

The speed regulator 1 provides an output as a current command value i* to the current regulator 2 such that the actual speed m (detected value) n detected by the speed generator 5 meets the target Wi (set value). . The current 1 Mrn device 2 outputs the current detection DI value i from the current detector 6 to be equal to this current command value 5*, and controls the firing angle of the thyristor converter 3 to control the DC motor. The speed of step 4 is controlled to a desired value.

On the other hand, in the load torque calculator 8, the differential element 82 simulates the acceleration/deceleration torque (motor generated torque) τa, and the torque/current converter 81 simulates the current conversion value jl of the acceleration/deceleration torque τa. The motor current i is detected by the detector 6, and the current conversion value iL of the load torque is obtained from the deviation 1-ia. Therefore, by adding this to the JII force of the speed regulator 1, fluctuations in motor speed due to fluctuations in load torque can be suppressed.

Note that even if the 1 current is replaced by a torque, and the current regulator is replaced by a 1M torque adjuster, the same control as described above is possible.

〔Effect of the invention〕

As described above, according to this invention, negative torque can be estimated using a simple circuit, which has the advantage of easily and quickly suppressing speed fluctuations due to load torque fluctuations. be.

Note that the present invention can be applied not only to the above-mentioned DC motor, but also as a control device for a controlled object having similar control characteristics.

[Brief explanation of drawings]

The figure is a configuration diagram showing an embodiment of the present invention. Description of symbols 1...Speed regulator, 2...Current regulator, 3...Thyristor converter, 4...DC motor, 5... ...Speed generator, 6...
Current detector, 8...Load torque calculator, 81.
... Torque current converter, 82 ... Differential element agent Patent attorney Akio Namiki Patent attorney Kiyoshi Matsuzaki

Claims (1)

[Claims] A speed l1ftI device that controls the rotational speed of the motor to a predetermined value, an electric ftHfa device that controls the motor current using the adjustment output as a current command value, and a differential value of the motor current detection value and the motor rotational speed. and a load torque calculator that estimates and calculates a load torque equivalent amount based on the load torque equivalent amount, and performs feedforward compensation of the load torque by adding the load torque equivalent amount to the output of the speed regulator. Speed control device.