SU1473062A1 - Ac drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of cranes, mechanisms for the movement of coke machines, mechanism for pushing out coke, a screw conveyor for feeding the charge, etc. The aim of the invention is to improve the accuracy of controlling the frequency of rotation of an electric motor. The invention makes it possible to increase reliability due to the fact that the electric drive remains operable regardless of the nature of the load torque — active or reactive. The essence of the invention is that a thyristor switch 2 with a relay control system is included in the rotor circuit of the motor 1. The control system contains two comparators 4 and 9, one of which has a hysteresis loop in the response characteristic, the other does not. The comparator 9 controls the thyristors of the switch 2, the comparator 4 monitors the nature of the load torque indirectly through the sensor 7 of the rotational speed of the electric motor. When the load moment is active, motor 1 is switched to anti-switch mode and the target speed is maintained. 2 Il.

Description

The invention relates to electrical engineering and can be used in electric drives of cranes, coke-moving machinery, coke pushing mechanism, screw feed conveyor.

charge, etc.

The purpose of the invention is to improve the accuracy of controlling the frequency of rotation of the electric motor and to expand its functionality.

FIG. 1 shows a diagram of the drive; in fig. 2 - mechanical characteristics.

The electric drive contains an asynchronous motor 1 with additional resistors in the rotor circuit, a thyristor switch 2 in the rotor circuit, the control input of the command device 6 is supplied with a driving voltage to the direct inputs of the comparators 4 and 9. Since the voltage of the sensor 7 is of frequency, voltage, inverse inputs of comparators 4 and 9, less than the voltage of the task

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Secondly connected to the output of the pulse generator 3, the first comparator 4, the reversing switch 5 in the stator circuit of the electric motor, command equipment 6, the motor speed sensor 7, made in the form of 25 tachogenerator, voltage divider 8, input connected to the output, speed sensor 7 and to the inverted input of the first comparator 4, the second comparator 9 with a hysteresis loop in the response characteristic, the inverse of which is connected to the output of the voltage divider 8, and the direct input is connected to the direct input of the first comp 4 and with the output of the speed setting of the compander 6, the relay, coil 0 of which is connected to the forward output of the second comparator 9, one terminals of the first closing and opening contacts of the relay are connected 40 to the output forward of the controller 6, and the other outputs respectively to the inputs of the reversing switch 5 Forward and Back, one pins of the second short-circuiting and disconnecting 45 clock ticks of the relay are connected to the Back output of the command device (s, and their other pins to the inputs of the reversing switch 5 Back. And Forward, one terminal of the third circuit, Q to guide and NC relay contacts are connected to the input shaper. 3 pulses, and their other views, respectively, to the direct and inverse accessing the direct leads and), signals appear on their direct outputs, and signals O appear on the inverse outputs. The relay with coil 10 turns on. The relay closure contacts connect the Forward and Back outputs of the controller 6, respectively, to the 15 Forward, Back inputs of the reversing switch 5 and the direct output of the comparator 4 to the input of the driver 3 pulses. .Road contacts of the relay disconnect the Forward and Back outputs of the control unit 6, respectively, from the Back, Forward reversing switch 5 inputs and the inverse output of the comparator 4 from the input of the driver 3 pulses. The scheme is ready for. Work.

When switching on the controller 6, for example, to the Forward position, the signal from its output Forward through the first closing contact of the relay turns on the switch 5, which connects the stator windings of the motor 1 to the mains voltage. Tension appears at the terminals of the rotor.

Signal 1 from the direct output of the comparator 4 through the third closing contact of the relay and the driver 3 pulses turns on the thyristor switch 2. Motor 1 is accelerated by mechanical characteristic 11 (Fig. 2). The voltage of the front sensor 7 increases to the voltage value of the task Uj ,, at which the comparator 4 is triggered. At its direct output, O appears, which disables the thyristor switch 2.

Under the action of a positive (reactive) load moment, the electric drive slows down the speed. When the voltage at the inverted input of the comparator 4 becomes less than the setting voltage, a signal 1 reappears at its direct output, which re-turns on the thyristor switch 2, and the process repeats.

Thus, the actuator comparator 4.55 returns in On / Off mode

 works as follows. ria adjustment characteristic 12

at once.

When turning on the power to the control circuit from the output Rear speeds

 t / c- a j o j t-ff-r. ---- j-

(Fig. 2) in the first quadrant. The speed fluctuates around the average value, which is set by the voltage to

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the command device 6 is supplied with a setting voltage to the direct inputs of the comparators 4 and 9. Since the voltage of the sensor ID 7 of the frequency vras, supplied to the inverse inputs of the comparators 4 and 9, is less than the voltage of the task

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25 40 45 Q arriving at the direct wiring and), then signals appear at their direct outputs, and at the inverse signals O signals appear. The relay with coil 10 is turned on. The relay closure contacts connect the Forward and Back outputs of the controller 6, respectively, to the 15 Forward, Back inputs of the reversing switch 5 and the direct output of the comparator 4 to the input of the driver 3 pulses. .Road contacts of the relay disconnect the Forward and Back outputs of the control unit 6, respectively, from the Back, Forward reversing switch 5 inputs and the inverse output of the comparator 4 from the input of the driver 3 pulses. The scheme is ready for. Work.

When switching on the controller 6, for example, to the Forward position, the signal from its output Forward through the first closing contact of the relay turns on the switch 5, which connects the stator windings of the motor 1 to the mains voltage. Tension appears at the terminals of the rotor.

Signal 1 from the direct output of the comparator 4 through the third closing contact of the relay and the driver 3 pulses turns on the thyristor switch 2. Motor 1 is accelerated by the mechanical characteristic 11 (Fig. 2). The voltage of the front sensor 7 increases to the voltage value of the task Uj ,, at which the comparator 4 is triggered. At its direct output, O appears, which disables the thyristor switch 2.

Under the action of a positive (reactive) load moment, the electric drive slows down the speed. When the voltage at the inverse of the comparator 4 becomes less than the voltage of the reference, a signal 1 reappears at its direct output, which re-turns on the thyristor switch 2, and the process is repeated.

Thus, the ra55 actuator turns on or off.

ria adjustment characteristic 12

 t / c- a j o j t-ff-r. ---- j-

(Fig. 2) in the first quadrant. The speed fluctuates around an average value that is given by a voltage of 10

31473062

Device 6. At the same time, the comparator and, consequently, the relays remain connected, since the voltage Idc at the inverse of the input of the comparator 9, which is omitted from the divider 8, does not reach the reference point U of the controller 6.

If the sign of the load moment changes from positive to negative, the drive speed increases. The comparator k and the thyristor switch 2 are turned off. With a further increase in speed to cOj (Fig. 2), under the action of a negative (active) load moment, the voltage DC at the inverse of the input of the comparator 9, removed from the divider 8, becomes greater than the voltage U of reference U, and it turns off.

At the forward output of comparator 9, an O signal appears and the relay with coil 10 is turned off. In this case, the signal Forward of the controller 6 switches the switch 5 from the direction Forward to

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the direction is Back, and the signal 1 from the inverse output of the comparator 4 through the third contact is opened and the driver 3 turns on the thyristor switch 2.

Engine 1 is switched to counter-current mode and decelerated by characteristic 13 (Fig. 2) to a speed determined by the voltage set and command of commander 6. Comparator 4 operates, signal O appears at its inverse output and switch 2 opens the rotor circuit.

Under the action of a negative (active) load moment, the electric drive again increases the speed. When the voltage Od on the inverted input of comparator 4 becomes greater than the voltage of task U, a signal 1 appears in its inverse output, which again turns on the thyristor switch 2, and the process repeats.

Thus, the drive operates in On / Off mode, on the control characteristic 12 in the second quadrant (Fig. 2). In this case, the comparator 9 and, consequently, the relay with the coil 10 remain disconnected, which is ensured by the presence of a hysteresis loop in the response characteristic of the comparator 9. In the case of a change, the sign of the load from negative to positive

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the speed of the drive decreases. The comparator 4 and the thyristor switch 2 are turned off. With a further decrease in speed to the magnitude and (Fig. 2), when the voltage id at the inverse of the comparator 9 becomes less than the voltage of the reference by the magnitude of the hysteresis loop in its characteristic, it triggers and at its direct output a signal appears 1. The relay turns on and translates the actuator to control characteristic 12 in the first quadrant.

The operation of the actuator in the Back direction on the adjustment characteristic 14 (FIG. 2) is similar.

20

25

Thus, the electric drive maintains a given speed with high accuracy when the sign of the load changes from positive to negative and vice versa by introducing a second comparator 9 with a hysteresis loop in the response characteristic, voltage divider 8 and relay with coil 10,

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the invention

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An AC drive containing a three-phase asynchronous motor with a phase-rotor with additional resistors in the rotor circuit and a thyristor switch connected in a triangle circuit to the rotor winding circuit, the control input of the thyristor switch is connected to the output of the pulse former, the first comparator that differs that, in order to extend the functionality by providing reverse and increasing the accuracy of controlling the frequency of rotation of the motor at a variable sign on the load , a reversing switch with Forward and Backward inputs and a command device with Forward, Backward, and Speed reference are entered, an electric motor speed sensor, a second comparator with a hysteresis loop in the response characteristic, a voltage divider, an input connected to the output of the rotational speed sensor and to the inverse input of the first comparator, a relay with a coil and three opening and three closing contacts, direct inputs

the first and second comparators are interconnected and with the output of the command speed setting, and the inverse input of the second comparator is connected to the output of the voltage divider, the relay coil is connected to the forward output of the second comparator, one terminals of the first closing and opening contacts-relays are connected to the output of the forward controller , and other outputs - respectively to the inputs of the reverse Forward and Backward switches, one terminals of the second closing and opening contacts of the relay

are connected to the Back output of the control unit, and their other outputs are respectively to the inputs of the reverse and forward reverse switches, one output of the third closing and opening contacts of the relay are connected to the input of the pulse former, and their other outputs to the direct and inverse outputs of the first comparator, respectively reversing switch is connected to the phases of the stator winding of the electric motor, and the input is intended to be connected to the phases

network.

Claims (1)

30 claims An AC drive containing a three-phase asynchronous motor with a phase rotor with 35 additional resistors in the rotor circuit and a thyristor switch included as a triangle in the rotor winding circuit, the control input of the thyristor switch is connected to the output of the pulse shaper, the first comparator, characterized in that, in order to expand the functionality by providing reverse and increasing the accuracy of regulating the frequency of rotation of the electric motor with a variable .. according to the sign of the load, a reverse switch with inputs Forward and Back and a command device with outputs Forward, Back, and Speed reference ·, a motor speed sensor, a second comparator with a hysteresis loop in the response curve, a voltage divider connected to the output of the speed sensor and to the inverse are introduced into it the input of the first comparator, the relay with a coil and three NC and three NO contacts, the direct inputs of the first and second comparators are interconnected and with the output '' Speed reference ”of the control unit, and the inverse input of the second comparator is connected to the output of the voltage divider, the relay coil is connected to the direct output of the second comparator, some of the outputs of the first make and break contacts are connected to the output u '' Forward of the command device, and the other outputs are connected to the inputs of the reversing switch Forward and Back , some conclusions of the second closing and opening contacts of the relay are connected to the output of the back of the command device, and their other conclusions are respectively to the inputs of the reversing com _{5 of the} mutator Back and Forward ¹ *, some conclusions are t Of their make and break contacts, the relays are connected to the input of the pulse shaper, and their other outputs are connected to the direct and inverse outputs of the first comparator, the output of the reversing switch is connected to the phases of the stator winding of the electric motor, and the input is designed to connect to phases 15 of the network.