RU1819365C - Method of automatic control over reversible rectifier drive and device for its realization - Google Patents

Abstract

Usage: the invention can be used in the metallurgical, papermaking and other industries. Essence: in this drive, during a dead time pause, the reference signal is fixed to the value at the beginning of the pause. When the pause ends, the reference signal continues to be generated according to the same law. The current in the electric motor appears after a dead time without sharp changes. 2 s.p. f-ly, 1 ill.

Description

4 The invention relates to electrical engineering, in particular to automatic control systems for reversible valve actuators, and can be used in the metallurgical, papermaking, machine tool, aviation and other industries.

The purpose of the invention is to increase the reliability of control by eliminating sudden changes in current during switching. Groups of valves of the converter. In this way, npw current reversals reduce the oscillation of the control process and dynamic loads in the electromechanical drive system.

The drawing shows a device for automatically controlling a reversible valve actuator, by which a method for automatically controlling a reversible valve actuator is implemented.

The device comprises a speed setting unit 1, an automatic speed control system 2, and a logical switching device 3. System 2.

The automatic speed control comprises series-connected speed controllers 4 and current 5, a reversible thyristor converter 6 with separate control of valve groups, and a direct current electric motor 7. The pulse-phase control system 8 of the converter 6 is connected to the control electrodes of the valve groups through two controlled keys 9,10, the control electrodes of which are connected to the corresponding outputs of the logical switching device 3 and the inputs of the OR circuit 11, the output of which is connected to the synchronization input of the unit 1 speed reference. The speed sensors 12 and current 13 are connected to the inputs of the respective controllers, and the inputs of the logical switching device are 3 outputs of the speed controller 4 and the current sensor 13.

The speed setting unit 1 comprises a control signal source connected in series, a comparison unit 15, a relay element 16 with a dead zone, a controlled key 17, an integration link 18, the output of which is connected.

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with input of comparison node 15 and block output

I speed reference. The control electrode of the key 17 is connected through the synchronization input of the speed setting unit 1 to the output of the OR circuit 11.

A method for automatically controlling a reversible valve actuator, for example, the mechanisms of a numerically controlled machine, is carried out using a speed setting unit 1, for example, a programmable controller, a system 2 for automatically controlling the speed of an electric motor 7, for example, a slave speed control system and a motor three, and a logical switching device 3 , for example, with three-position logic.

So, the speed reference signal at the output of block 1 varies linearly in accordance with a predetermined process control program. The automatic control system 2 processes the change of the reference signal, and the signals at the outputs of the regulators 4, 5 of the EMF of the converter 6, the current in the main circuit of the electric motor 7 and its speed are changed in accordance with the control action and the settings of the regulators of the automatic control system 2. Using the logical switching device 3 and the current sensor 13, the polarity of the current reference signal is monitored, for example, at the output of the speed controller 4, and the current of the electric motor 7 is determined by the voltage value at the output of the current sensor 13. And in accordance with the polarity of the current reference signal connect the output of the pulse-phase control system 8 to the control electrodes of the corresponding valve group of the converter 6. When the polarity of the current reference signal changes and the motor current decreases to zero, using the logic the first switching device 3 and a controllable switch 9 is disconnected the system output 8-phase control pulse from control electrodes working group of valves, e.g. group forward reverse converter 6 and the set value is read The relative dead time (using the logical switching device 3). During a dead time pause using the OR circuit

II form a synchronization signal for speed setting unit 1. According to this signal, the execution of the program for generating the speed reference signal is stopped and the signal at the output of block 1 for the duration of a dead time pause is fixed to its value at the moment of the start of the dead time pause. After the set value of the dead time is expired using the logic switching device 3 and the controlled key 10, the output of the pulse-phase control system 8 is connected to the control electrodes of another valve group of the converter 6, for example, a group of valves back. The synchronization signal at the input of block 1 changes

0 its value, the key 17 is closed and the control and speed reference signals continue to be generated further according to the established program, i.e., they continue to execute the algorithm for generating the speed signal 5 from the value fixed at the beginning of the dead time pause. Since the speed reference signal at the input of the control system 2 does not change during a dead time, and the speed of the electric motor

0 changes insignificantly, the speed control error signal and, accordingly, the proportional components of the signals at the outputs of the regulators during a dead time pause remain unchanged.

5, as a result, the current of the electric motor 7, after the end of the dead time, increases smoothly without sudden changes and overshoot. Thus, this control method also creates conditions for

0 to bring the state of the regulators of the control system 2 during a dead time pause to the necessary initial conditions.

A device for automatically controlling a reversible valve actuator 5 operates as follows. When changing the EMF at the output of the source 14 of the control signal, for example, a command device, as a function of a certain process parameter, the signal at the output of the speed setting unit 1 changes linearly with the rate determined by the time constant of the integrating link 18. The signal at the output of the link 18 less signal at the output of the source 14, and the signal at

5 the output of the comparison node 15 exceeds the threshold of the relay element 16 and at the input of the integrating link 18, the signal is equal to the saturation voltage of the relay element 16. System 2 of automatic

0 speed control produces a linearly changing speed reference signal and the voltage at the outputs of the regulators 4, 5. EMF of the inverter 6, the current in the main circuit of the electric motor 7 and its speed 5 are changed in accordance with the control action, that is, the dynamic current of the motor is maintained constant, and the speed varies linearly. Logic switching device 3 controls the polarity of the reference signal

current at the output of the speed controller and the value of the current in the main circuit of the electric motor according to the voltage at the output of the current sensor, and when the polarity of the current reference signal changes and the motor current decreases to zero, the signals at the outputs of the logical switching device are zero. When the derivative of the control signal changes sign, the derivative of the speed reference signal also changes accordingly, as well as the signs of the signals at the output of the regulators 4, 5 change, and the current of the electric motor 7 decreases to zero and changes its polarity.

At the time when the current demand signal changes sign and the current in the main circuit of the electric motor decreases to zero at the outputs of the logical switching device 3, at the output of the OR circuit 11 and at the synchronization input of the speed setting unit, the signals are zero. Consequently, there are no signals at the control inputs of the keys 9,10,17 and the keys 9, 17 are opened. As a result, the output of the pulse-phase control system 8 is disconnected from the control electrodes of the valve group of the converter 6. for example, the group is forward, and the output of the relay element 16 is from the input of the integrating link 18. Since the signal at the output of the integrating link 18 is zero , then the signal at its output during a dead time pause does not change and is fixed to its value at the time the dead time pause starts, i.e. at the moment of opening of key 17.

When the dead time pause countdown ends, a logic one signal appears at the corresponding output of the logic switching device 3 in accordance with the polarity of the current reference signal. At the control electrode of the key 10 and at the output of the OR circuit 11, the signals are equal to a logical unit and the controlled keys 1.0, 17 are closed. The output of the pulse-phase control system 8 is connected to the control electrodes of another valve group of the converter b, for example, to the back, and the output of the relay element 16 is connected to the input of the integrating link 18 and the signal at its output starts to linearly change from a fixed value.

Since the speed of the electric motor 8 during the pause varies insignificantly, and the speed reference signal is fixed, the speed control error and the proportional components of the signals at the outputs of the regulators 4, 5 do not change during the dead time, and the current of the electric motor 7 after the end of the dead time increases smoothly without sudden changes and overshoot. The exclusion of sudden changes in current when switching valve groups makes it possible to eliminate the operation of the maximum current protection of the converter and shocks in the electromechanical system of the electric drive.

Claims (2)

1. The method of automatic control of a reversible valve actuator, carried out using a speed setting unit, an automatic motor speed control system and a logical switching device, according to which a speed setting signal is generated according to a certain law, the speed and current of the motor are measured, the measured values are compared with the set and the error signals are converted according to the established laws, and the resulting signal is fed to the input of the pulse-phase control system the thyristor converter, they control the polarity of the current signal and when the polarity of this signal changes and the current decreases to zero, disconnect the output of the pulse-phase control system from the control electrodes of the working group in the converter terminals and, after the end of the established dead time, connect the output of the pulse-phase control system to the control electrodes of another group of valves, characterized in that, in order to increase the reliability of control, the speed reference signal for a while estokovoy fixed pause equal to its value at the moment of its start, and after a pause signal specifying speed continues to form at a given law, 2. A device for automatically controlling a reversible valve actuator, comprising a speed setting unit, a speed controller, a current controller, a pulse-phase control system, the output of which is connected to the power electrodes of two controlled keys, two other power electrodes of which are connected to the control electrodes of the valves of the corresponding groups of the converter, and the control electrodes of the keys are connected to the corresponding outputs of the logical switching device, and the sensor The speed and current indicators are connected to the inputs of the regulators of the same name, and the inputs of the logical switching device are connected to the outputs of the current sensor and the speed controller, characterized in that, in order to increase reliability, it is additionally introduced a third controlled key and an OR circuit, the inputs of which are connected to the outputs of the logical switching device, and its output is connected to the corresponding synchronizing input of the task unit, which contains a control signal source connected in series, a comparison unit, a relay element with a dead zone, a third control key, an integrating link, the output of which is connected to the second input of the comparison unit and is the output of the speed reference unit, and the control electrode of the third key is connected to the synchronization input of the speed reference unit. .