RU2539631C1 - Electric drive for rolling mill - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electrical engineering and can be used in an automated electric drive. The technical result is reduced dynamic loads and high quality of control when rolling metals. The electric drive for a rolling mill comprises a motor angular velocity setting device (1), a scaling amplifier (2), two comparator elements (3, 4), a nonlinear function generator (5), a controlled switch (7), a limiting unit (8), a velocity controller (9), a current controller (10), a power amplifier (11), a current sensor (12), an independent driving dc motor (13), a voltage sensor (14), a motor angular velocity sensor (15), a rolling speed sensor (16), an ingot displacement sensor (17), a controlled timer (18) which generates delay, and a pulse generator (19) for generating pulses with an amplitude U₀ and duration Δτ.

EFFECT: high quality of control in the electric drive and lower dynamic loads caused by looseness, achieving a predicted increase in electromagnetic torque of the electric motor before the ingot is gripped by rollers.

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Description

The present invention relates to an automated electric drive and is intended for use as part of industrial technological complexes of rolling production.

Known electric drives containing a direct current electric motor of independent excitation, the anchor winding of which is connected through a current sensor to the output of a power amplifier, the input of which is connected to the output of a current regulator connected by a summing input to the output of the speed controller, and by a subtracting input to the output of the current sensor, the adjuster and the angle sensor engine speeds, the outputs of which are connected respectively to the summing and subtracting inputs of the comparison element, the output of which is connected to the input of the speed controller, and dates voltage transducer connected to the armature winding of the motor (RF Patent No. 2065660. Publ. 20.08.96, Bull. No. 23, IPC H02P 5/06; Thyristor DC drives / A. G. Ivanov et al. - Electrical Engineering, 2001, no. 2, p. 10-15, fig. 3; Pivnyak G.G., Beshta O.S., Filkin MP Automation of an electric drive at the rental virobnosti. .4.11).

In known electric drives, speed control and subordinate regulation of motor current are carried out. During operation of the electric drive when the ingot is gripped as a result of the load application, the backlash in the mechanical transmission opens, causing a shock and leading to an increase in dynamic loads.

Therefore, the disadvantage of the known technical solutions are high dynamic loads during rolling of metals.

Of the known technical solutions, the closest to the proposed result is an electric drive of a rolling mill containing an independent excitation DC motor, the anchor winding of which is connected through a current sensor to the output of the power amplifier, the input of which is connected to the output of the current regulator, connected by the first summing input to the output of the regulator speed, and subtracting the input to the output of the current sensor, the outputs of the master and the sensor of the angular velocity of the motor are connected respectively to the summing to it and the subtracting inputs of the first comparison element, the output of which through the restriction unit is connected to the first summing input of the speed controller and is directly connected to the first input of the nonlinear functional converter that implements the function

where ε, u ₂ - the first and second input signals; U _e is the voltage corresponding to the level of a logical unit,

the second input of which is connected to the output of the speed controller through a scaling amplifier, and the output is connected to the control input of a controlled key connected between the summing input of the speed controller and the output of the second comparison element, the summing input of which is connected to the output of the speed controller, and the subtracting input is connected to the output of the voltage sensor connected to the armature winding of the motor (RF Patent No. 2254665, IPC H02P 5/06. - Publish. 20.06.2005, Bull. No. 17).

In the known electric drive, speed and voltage are regulated on the anchor winding and subordinate regulation of the motor current. When the drive is operating as a result of the load, the backlash in the mechanical transmission opens, causing a shock and leading to an increase in dynamic loads.

Therefore, the disadvantage of the known technical solutions are high dynamic loads during rolling of metals.

The purpose of the invention is to reduce dynamic loads during rolling of metals.

This goal is achieved by the fact that in a known electric drive containing a DC motor of independent excitation, the anchor winding of which is connected through a current sensor to the output of the power amplifier, the input of which is connected to the output of the current regulator, connected by a summing input to the output of the speed controller, and by a subtracting input to the output the current sensor, the outputs of the master and the sensor of the angular velocity of the motor are connected respectively to the summing and subtracting inputs of the first comparison element, the output of which is connected with the combined input of the limiting unit and the first input of a nonlinear functional converter, the second input of which is connected through a scaling amplifier to the output of the master, summing and subtracting the inputs of the second comparison element are connected to the outputs of the speed master and voltage sensor, respectively, and the output through the first controlled key is connected to one of the inputs of the adder, the other input of which is connected to the output of the restriction unit, and the output is connected to the input of the speed controller, the control input of the controlled key connected to the output of a nonlinear functional converter; the input of the voltage sensor is connected to the armature winding of the motor; an additional rolling speed sensor, an ingot displacement sensor, a controllable timer forming a delay

where τ ₀ is a constant; V is the linear speed of the ingot at the entrance to the stand, L is the distance from the linear displacement sensor to the working stand, a pulse shaper, and the current regulator is equipped with a second summing input connected through a pulse shaper to the output of a controlled timer, the control and installation inputs of which are connected to the outputs, respectively rolling speed sensor and ingot movement sensor.

Compared with the closest similar technical solution, the proposed electric rolling mill has the following new features:

- rolling speed sensor;

- ingot displacement sensor;

- controlled timer;

- pulse shaper;

- the current controller is equipped with a second summing input.

Therefore, the claimed technical solution meets the requirement of "novelty."

When implementing the present invention, it is possible to reduce dynamic loads and improve the quality of speed control by reducing the dynamic load caused by the opening of play by proactively increasing the electromagnetic moment of the DC motor. The increase in the electromagnetic moment is carried out by connecting a signal of amplitude U ₀ and duration Δτ to the second summing input of the current regulator from the output of the pulse shaper by the signal of a controlled timer for the time interval τ ₀ until the load is applied. As a result of this, transients in the armature winding of the electric drive are initialized, which lead to a short-term increase in the armature current and, accordingly, the electromagnetic moment. Capture of the ingot occurs at an increased moment developed by the engine. Backlash disclosure in this case does not occur, and speed fluctuations do not develop. Thus, the dynamic load is reduced, the quality of regulatory processes is improved.

Therefore, the claimed technical solution meets the requirement of "positive effect".

For each distinguishing feature, a search is made for well-known technical solutions in the field of electrical engineering, automation, and electric drive.

Known current regulators equipped with several inputs (summing and subtracting) in electric drives (Handbook of an automated electric drive / Under the editorship of VA Eliseev and AV Shinyansky. - M .: Energoatomizdat, 1983, p. 246-247, fig. .7.34; Thyristor DC electric drives / A.G. Ivanov et al. - Electrical Engineering, 2001, No. 2, pp. 10-15, Fig. 3).

In known technical solutions and the proposed device, regulators with several inputs perform similar functions.

Known pulse shapers in electric drives (Perelmutter V.M., Sidorenko V.A. Control systems of thyristor electric drives of direct current. - M.: Energoatomizdat, 1988, p.40-45). In known devices, pulse shapers are used to control thyristors. In the proposed technical solution, the pulse shaper is used for a new purpose - to form a correction signal for the current loop of an adjustable electric drive.

Managed timers, rolling speed sensors, and ingot displacement sensors have not been found in known devices of a similar purpose.

Thus, these features provide the claimed technical solution according to the requirement of "significant differences".

The essence of the invention is illustrated by drawings. Figure 1 shows the functional diagram of the electric drive, figure 2 shows the dependence of the maximum load moment during rolling on the value of the correction signal supplied to the second summing input of the current regulator 10; figure 3 shows the simulation results of the electric drive of the rolling mill.

The electric drive of the rolling mill (Fig. 1) contains a motor angular speed adjuster 1, a scaling amplifier 2, the first 3 and second 4 comparison elements, a nonlinear functional converter 5 that implements the function

controlled key 7, restriction unit 8, speed controller 9, current controller 10, power amplifier 11, current sensor 12, independent excitation DC motor 13, voltage sensor 14, engine angular speed sensor 15, rolling speed sensor 16, ingot displacement sensor 17 6, a controlled timer 18, forming a delay duration

where τ ₀ is a constant; V is the linear speed of the ingot at the entrance to the stand, L is the distance from the linear displacement sensor to the working stand, the shaper 19 pulses of amplitude U ₀ and duration Δτ; live rolls 21.

In the proposed electric drive of the rolling mill, the anchor winding of the DC motor 13 through a current sensor 12 is connected to the output of the power amplifier 11, the input of which is connected to the output of the current regulator 10, connected by the first summing input to the output of the angular speed controller 9 of the engine, and by the subtracting input to the output of the sensor current 12, the outputs of the setter 1 and the sensor 15 of the angular velocity of the motor 13 are connected respectively to the summing and subtracting inputs of the first element of comparison 3, the output of which is through the block limiting 8 The key to a first summing input of the speed controller 9 and is directly connected to a first input of a nonlinear functional converter 5 that implements the function

where ε, u ₂ - the first and second input signals; U _e is the voltage corresponding to the level of a logical unit,

the second input of which, through the scaling amplifier 2, is connected to the output of the speed controller 1, and the output is connected to the control input of the first controlled key 7, connected between the summing input of the speed controller 9 and the output of the second comparison element 4, the summing input of which is connected to the output of the speed controller 1, and the subtracting input is connected to the output of the voltage sensor 14 connected to the armature winding of the motor 13, the second summing input of the current regulator is connected through a pulse shaper 19 to the output of the controlled t timed restart 18 forming the delay duration

where τ ₀ - a given constant duration of the time interval from the beginning of the formation of the correction signal until the ingot 6 enters stand 20; V is the linear speed of the ingot at the entrance to the stand, L is the distance from the sensor 17 of the movement of the ingot 6 to the working stand 20, the control and installation inputs of the controlled timer are connected to the outputs of the sensor for rolling speed 16 and the sensor 17 of the movements of the ingot 6.

Electric drive rolling mill operates as follows. The armature winding of the independent excitation DC motor 13 is connected to the output of the power amplifier 11. The motor speed Ω is regulated by changing the voltage across the armature winding. The angular velocity of the engine 13 is measured by a sensor 15 of the angular velocity of the engine, for example a tachogenerator. The current of the motor 13 is measured using a current sensor 12, for example a shunt. The voltage measurement at the armature winding of the motor 13 is made by the voltage sensor 14.

The signal u ₁ proportional to the required value of the engine speed 13 is received at the summing input of the first comparison element 3 from the output of the engine angular speed setter 1. The subtracting input of the first comparison element 3 receives the output signal u _{15 of the} engine angular speed sensor 15 proportional to the rotor speed Ω of the engine rotor 13. In the comparison element, the calculation of the regulatory error ε = u ₁ -u ₁₅ . The signal ε from the output of the comparison element 3 is fed to the combined first input of the nonlinear functional converter 5 and the input of the restriction unit 8. At the second input of the nonlinear functional converter 5, the signal u ₂ from the output of the scaling amplifier 2 is proportional to the reference signal u ₁ . At the output of the nonlinear functional converter 5, a signal is formed

where ε, u ₂ - the first and second input signals;

U _e is the voltage corresponding to the level of a logical unit. The output of block 8 is

where ε _m is the maximum value of the output signal of the restriction block.

The second comparison element 4, to the summing and subtracting inputs of which the signals from the outputs of the engine speed sensor 1 and the voltage sensor 14 respectively, calculates the mismatch u ₄ = γ = u ₁ -u ₁₄ . In a direct current electric drive, the motor speed is directly proportional to the voltage and to the armature winding and the moment of load resistance M _c :

where c is the structural constant of the engine;

r is the resistance of the armature winding.

therefore

therefore, the voltage mismatch in the electric drive system differs from the speed mismatch by a value proportional to the load moment M _c .

The signal u ₄ from the output of the second comparison element 4 through the first controlled key 7 is fed to one of the inputs of the adder, the second input of which is the output signal of the restriction unit 8. The first controlled key 7 in accordance with the algorithm (1) of the nonlinear functional converter 5 is closed when | ε | ≥ | u ₂ | and open for | ε | <| u ₂ |. This means that with a large error of the electric drive system with respect to speed ε, the value of this error at the first summing input of the speed controller 9 is limited to ε _m , and a signal proportional to the voltage mismatch acts on the other summing input of the speed controller 9. The speed controller 9 converts the input signal in accordance with the regulation law, for example, proportional-integral, and generates a reference signal for the slave current control loop 10, which in turn generates a control signal for the power amplifier 11. The control system operates in such a way that the total errors u ₄ + u ₈ , decreases, therefore, decrease ε and γ. When the mismatch of the system in speed 8 reaches the value u ₂ , the output signal of the nonlinear functional converter 5 changes and the controlled key 7 opens. Next, the electric drive functions as a dual-circuit speed control system with a slave current control loop. The mismatch 8 of the electric drive thus reaches a value whose value is determined by the structure of the electric drive and the error of the speed sensor.

If there is play in the mechanical transmission when the ingot is gripped as a result of applying the shock load, the gap opens, the “driving” mass (electric motor rotor) is accelerated, and the “driven” mass is braked; as a result, the gap in the mechanical transmission begins to decrease and “adhesion” of these masses occurs, an impact load is reapplied to the drive. The backlash opening process is repeated. Due to fluctuations in the speed of both masses, additional dynamic loads arise in the electromechanical system. A decrease in the engine speed, leading to the opening of the gap, is due to the impossibility of an instant increase in the corresponding electromagnetic moment, which is proportional to the current in the armature winding. Thus, the opening of the gap is associated with a slowed increase in the current of the armature winding of the motor. To solve this problem, a proactive increase in current in the armature winding of the electric motor 13 is proposed by changing the voltage on the armature winding. This effect in the proposed technical solution is achieved by pre-feeding to the second summing input of the current regulator 10 a pulse with an amplitude of U ₀ and a duration of Δτ, for a time interval of τ ₀ before the ingot 6 is captured by the rolls of the working stand of the rolling mill 20.

, через которое произойдет захват слитка валками первой рабочей клети, а по сигналу датчика 17 перемещений слитка 6 отсчитывает интервал $$\tau =\frac{L}{V}-{\tau }_0$$

и формирует на своем выходе сигнал логической единицы, запускающий формирователь импульсов 19, на выходе которого формируется одиночный импульс с амплитудой U₀ и длительностью Δτ.The controlled timer 18 according to the results of a survey of the rolling speed sensor 16 calculates the time $${\tau }_{\mathrm{one}}=\frac{L}{V}$$

, through which the ingot will be captured by the rolls of the first working stand, and according to the signal of the sensor 17 movements of the ingot 6 counts the interval $$\tau =\frac{L}{V}-{\mathrm{<figure-callout\; id="0"\; label="\tau "\; filenames="00000015.png,00000016.png"\; state="\{\{state\}\}">\tau </figure-callout>}}_0$$

and generates a logic unit signal at its output, which starts the pulse shaper 19, at the output of which a single pulse is formed with an amplitude of U ₀ and a duration of Δτ.

As a result of applying a pulse to the second summing input of the current regulator 10, a transition process occurs during the time τ ₀ before the ingot 6 is taken by the rolls of the first working stand, accompanied by an increase in the current of the armature winding, and, accordingly, the electromagnetic moment. Thus, at the time of application of the load, an increased current flows in the anchor circuit of the drive motor 13, and accordingly, the motor develops an increased electromagnetic moment. As a result of this, the impact force of rotating masses decreases, and a sharp decrease in speed does not occur after application of the load and opening of the play. Thus, the dynamic load is reduced, the quality of regulatory processes is improved.

When simulating the rolling mill 300, it was found that the greatest effect is achieved if the time between the moment of application of the load and the pulse supply is not more than 0.5 s.

In order to confirm the positive effect achieved by using the proposed technical solution, computer simulation of the electric drive was carried out, implemented according to the scheme depicted in figure 1.

System parameters had the following meanings.

DC motor: armature resistance r = 0.0244 Ohm; anchor chain inductance L = 0.0046 H; design constant c = 18 V · s / rad; reduced moment of inertia J = 130 kg · m ² ; power amplifier: transmission coefficient k _у = 78; PI current controller: current regulator transmission coefficient k _rt = 0.0244; time constant T _rt = 5.3043 s; PI speed controller: transmission coefficient of the speed controller k _pc = 80; time constant T _pc = 0.7 s; a scaling amplifier with a transmission coefficient k = 2.

The results of simulation are shown in figure 3. From the diagram it follows that when using the proposed technical solution, the load moment when gripping the ingot is reduced by 1.4 times, and speed fluctuations do not develop.

Thus, the use in a known electric drive containing a DC motor, the anchor winding of which is connected through a current sensor to the output of a power amplifier, the input of which is connected to the output of the current regulator, connected by the first summing input to the output of the speed controller, and by subtracting the input to the output of the current sensor, the outputs of the master and the engine angular velocity sensor are connected respectively to the summing and subtracting inputs of the first comparison element, the output of which is connected to moat summing input of the speed controller and is directly connected to a first input of a nonlinear functional converter that implements a function $$F(\epsilon ,u_2)=\{\begin{array}{l}{U}_{e}PR\mathrm{and}\left|e\right|\ge {\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="00000015.png,00000016.png"\; state="\{\{state\}\}">u</figure-callout>}}_2;\\ 0PR\mathrm{and}\left|\epsilon \right|<{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="00000015.png,00000016.png"\; state="\{\{state\}\}">u</figure-callout>}}_2,\end{array}$$

where ε, u ₂ - the first and second input signals; U _e is the voltage corresponding to the level of a logical unit, the second input of which is connected through the scaling amplifier to the output of the angular speed adjuster of the engine, and the output is connected to the control input of the controlled key connected between the summing input of the speed controller and the output of the second comparison element, the summing input of which is connected to the output of the angular speed adjuster of the engine, and the subtracting input is connected to the output of the voltage sensor connected to the armature winding of the motor, additionally a speed sensor This rolling sensor, the displacement sensor of the ingot, the controlled timer, the pulse shaper and the equipment of the current regulator with a second summing input connected through the pulse shaper to the output of the controlled timer, the control and installation inputs of which are connected to the outputs of the rolling speed sensor and the ingot displacement sensor, respectively, can reduce dynamic loads when rolling metals.

Using the proposed device in industrial systems for rolling production will improve the technical level of equipment and the quality of the process.

Claims (1)

An electric drive of a rolling mill containing a DC motor, the anchor winding of which is connected through a current sensor to the output of a power amplifier, the input of which is connected to the output of the current regulator connected by the first summing input to the output of the motor angular speed controller, and by the subtracting input to the output of the current sensor, outputs the set point and the engine angular velocity sensor are connected respectively to the summing and subtracting inputs of the first comparison element, the output of which through the restriction block is connected to the first summing input of the speed controller and is directly connected to the first input of a nonlinear functional converter that implements the function

where ε, u ₂ - the first and second input signals; U _e is the voltage corresponding to the level of a logical unit, the second input of which is connected through a scaling amplifier to the output of the speed controller, and the output is connected to the control input of the first controlled key connected between the summing input of the speed controller and the output of the second comparison element, the summing input of which is connected to the output speed adjuster, and the subtracting input is connected to the output of the voltage sensor connected to the armature winding of the motor, characterized in that the speed sensor is additionally introduced te rolling, motion sensor of the ingot, controlled timer, forming a delay duration

,
where τ ₀ - a given constant duration of the time interval from the beginning of the formation of the correction signal until the ingot enters the crate; V is the linear speed of the ingot at the entrance to the stand, L is the distance from the displacement sensor of the ingot to the working stand, and the pulse shaper, and the current regulator is equipped with a second summing input connected via a pulse shaper to the output of the controlled timer, the control and installation inputs of which are connected to the outputs respectively, a rolling speed sensor and an ingot displacement sensor.

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