RU1817220C - Electric drive with separate control - Google Patents

Abstract

Usage: can be used in electric drives of mechanisms in the machine tool, paper industry. Essence: in this electric drive, when the key 24 is closed, the voltage at the input of the pulse-phase control system 6 at the moment of the end of the established non-current pause decreases abruptly by an amount equal to the backlash of the adjustment characteristic of the inverter 11. Opening the power switches 18, 20 leads to the loss of current of the electric motor 12 immediately after a dead end pause. 1-yl .-. ; .- ... .,

Description

The invention relates to electrofusion, in particular to reversible DC electric drives with separate control of groups of valves of converters, and can be used in electric drives of mechanisms working with frequent reverses of the moment, in machine-tool, paper-making, hoisting, transport, metallurgical, aviation and other industries.

The purpose of the invention is to improve the quality of current and motor speed control by increasing the speed of the speed controller during reverses. Thus, the accuracy of the technological operations and the productivity of the drive mechanism are improved. ; The drawing shows a diagram of the proposed electric drive with separate control, which contains sequentially connected first comparison unit 1, speed controller 2, second comparison unit 3, current controller 4, summing unit 5, pulse-phase control system 6,

the output of which, through the first and second controlled keys 7.8, is connected to the control electrodes of the valve groups forward 9 and back 10 of the reversing valve converter 11, which feeds the core winding with an electromotor 12, speed sensors 13 and current 14 of the electric motor 12, connected by their outputs to the inputs nodes 1 and 3. The speed controller 2 contains an operational amplifier 15, in the feedback circuit of which the resistor 16 and the capacitor 17 are connected next to 6, moreover, a resistor 19 is connected in parallel to the capacitor through the fifth control key 18. A third is connected in parallel to the feedback loop of the controller 2 managed key 20.

The logical switching device 21 controls the operation of the keys 7, 8 and its outputs are connected to their control electrodes, and the inputs are separately connected to the output of the current sensor 13 and to the output of the third comparison unit 22. The constant voltage source 23 is connected to the node 5 summoo

 y u

through the fourth controlled key 24, the control electrode of which is connected to the control electrode of the second controlled key 8.,:

The logic control unit 25 controls the operation of the keys 18,20 and its output is connected to the control electrodes of these keys, and the inputs are connected to the outputs of the logical switching device 21 and the third comparison node 22, respectively.

Separate electroHyd iodine works as follows. .Рас-; See, for example, the operation of a reversible DC direct current electric drive of a general industrial mechanism controlled by an intensity adjuster with three-position logic for switching groups of transducer gates, moreover, the logical control unit implements the following logical function:

UvikhChS OVHZ RPMovhG L ()) V (Uax2A

CUBx3 0)) (UexiyUBxD.

So, the algorithm of operation of the controlled keys is 7.8, 20, 24, formed by the MPI-g 21 and the LPU-25; contains the following operations. Logimetic switching device 21 Monitors the polarity of the speed control error and its magnitude, as well as the presence of current in the root, motor circuit, and when the polarity of the control error signal changes and its value exceeds the set threshold value. -Un i, according to the signal from the logic control unit, are controlled and key 20 and bypasses the feedback loop of the speed controller, and the current reference signal becomes zero, which leads to a forced decrease in the current of the electric motor. When the current decreases to zero and the control error signal corresponds to speed overshoot, the signals at the outputs of the medical facility 21 are blocked and the dead time pause starts, while the controlled keys 7, 8 are open. When the dead time countdown ends at the output of the health facility 21 corresponding to the polarity of the speed overshoot. a signal of a logical unit appears, which leads to the closure of the corresponding keys, that is, the output of the pulse-phase control system 6 is connected to the control electrodes of the corresponding valve group of the converter 11. Simultaneously after the end of the dead-time pause, the controlled keys 20 and 24 and the voltage the output of current controller 4 changes by the amount of play in the control characteristic of converter 11. In addition, speed controller 2 is unloaded and the control system restores its linear traditional structure slave control parameters, where thus formed zero initial conditions for the operation of the next group of valves.

So, let’s say that the speed reference signal at the input of comparison nodes 1, 22 changes according to a triangular diagram and increases up to a constant rate until time t, and decreases similarly after time t. The dynamic current of the motor remains constant, and its speed varies with constant acceleration. : ;;; ; ;:. ; / ... :: v .-. . ..

Until time t, the error in controlling the speed at the output of comparison nodes 1, 22 has a positive polarity and

arrives at the third input of the logical control unit 25 and at the second input of the logical switching device 21, the first input of which receives a signal from the output of the current sensor 114. This error polarity

regulation corresponds to the operation of the group of valves forward when controlling the speed of the electric motor 12. At the first output of the medical facility 21 there is a signal of a logical unit, and at the second - a logical zero.

The signal of a logical unit from the first output of the device. 21 It is supplied to the first input of the logic control unit 25 and to the control input of the key 7, and the signal of the logical Zero from the second output of the device 21 is supplied to the second input of the logic unit 25

control and control inputs of keys 8,

24. (Investigation; this keys 8, 24 are

in the open state, and the key 7 - in; closed. Output control pulses

pulse-phase control systems 6 are fed through a key 7 to the control electrodes of the valve group 9 forward, and

the input of the system 6 receives the output voltage of the current controller 4, since the key 24

open and the constant voltage source 23 is disconnected from the input of the adder 5. The supply of control pulses to the control electrodes of the valve group is blocked back, since the key 8 is open.

Thus, the operation of the proposed electric drive with separate control up to the point in time is no different from the work of the known devices for separate control of a valve converter

in a system of subordinate control of the speed and current of the electric motor in steady-state modes of operation of the electric drive.

At time t, the motor speed reference signal at the input of the comparison nodes 1.22 begins to decrease and causes a change in the polarity of the voltage of the speed control error at the output of the comparison nodes 1, 22. Further, at time tj, the voltage of the speed control error at the output of comparison nodes 1, 22 becomes larger than the set threshold value. As a result of this, a signal for switching the valve groups of the converter 11 appears in the medical facility 21, but the signals at its outputs remain unchanged, since the current of the electric motor 12 is not equal to zero. At the output of the logical control unit, in accordance with its logic of operation, a signal of a logical unit appears, which is supplied to the control inputs of the keys 18, 20, which causes the closure of their power circuits. The voltage at the output of the speed controller 2 decreases stepwise to zero, and the voltage at the output of the current controller 4 decreases stepwise by the value of the proportional component. Therefore, the EMF of the converter 11 becomes smaller than the EMF of the motor and within one interval ;, the discreteness of the valve converter and the motor current forcedly reduced to zero. The closed current loop of the slave control system during the current decay of the motor 1.2 to zero processes the zero reference signal at the input and automatically converts the output voltage of the current regulator to zero initial conditions, that is, to the level at which the average rectified EMF value groups of valves forward of the converter 11 and the EMF of the electric motor 12 are approximately equal to each other. At the same time, the discharge of the capacitor 17 occurs through the feedback circuit of the operational amplifier 15 of the speed controller 2 through the resistor 16 and the controlled key 20, as well as through the resistor 19 and the controlled key 18. That is, the discharge circuit of the capacitor 17 consists of parallel-connected resistors 16.19. The resistance of the resistor 19 is chosen so that the inequality holds:

tn

And Ci7 Ris Ri9 --- Rl6 + Rig

where tn is the duration of the dead time pause;

Civ is the capacitance of the capacitor 17;

Rie R19 - resistance of resistors 1 b, 19;

then, by the time of the dead time, the capacitor 17 is discharged to zero in any operating modes of the electric drive.

If two conditions coincide: the presence of overshoot of the motor speed and the absence of current in its core circuit,

the logical switching device 21 5 changes its state and the voltage at its outputs is logic zero. This voltage is applied to the control inputs of the keys 7, 8, 24 and their power electrodes are open. Thus blocked

0 the output of the pulse-phase control system 6 and the control pulses are not supplied to the converter 11. After the established dead-end pause, which is necessary for reliable locking of the previously working group of valves forward, the medical facility 21 changes its state and a signal of a logical unit appears at its second output. In addition, a logic zero signal appears at the output of the logical control unit 25, which leads to the opening of the keys 18.20, as well as the closure of the controlled keys 8, 24. As a result, the voltage at the outputs of the speed controllers 2 and 4 of the current changes stepwise by the amount

5, the proportional component and the EMF of the converter 11 becomes smaller than the EMF of the electric motor 12 during one discrete interval of the valve converter, and the current in the main circuit arises without delay after the end of the dead time.

When the key 24 is closed, the signal at the output of the adder 5 becomes equal to the sum of the output voltage of the current controller 4 and

5 of the output voltage of the constant voltage source 23, i.e., the voltage at the input of the pulse-phase control system 6, at the moment of termination of the established dead time, decreases stepwise by an amount equal to the clearance of the adjustment characteristic of the converter 11. -. So, at the moment of the end of the deadlock pause as a result of closing the keys 8, 24

5 control pulses from the output of the pulse-phase control system b are fed back to the control electrodes of a group of 10 valves under zero initial conditions formed in the system

0 subordinate regulation for the group of valves back, and the opening of the power electrodes of the keys 18, 20 leads to the appearance of current in the electric motor 12 immediately after the end of the set

5 dead time pause. This eliminates the ambiguous dependence of the output voltage of the converter 11 on the control voltage, and increases the speed of the control system. reduce the dead-time zone to the value of the established dead-time pause and reduce the overshoot during current reversal. Thus, the quality of the motor speed control is improved.

Claims (1)

 The claims Separate control electric drive comprising a motor, serially connected first comparison unit, proportional-integral speed controller, second comparison unit, current controller, adder and pulse-phase control system, the outputs of which are connected separately to the control unit via the first and second controlled keys the main circuit of the corp. Forward and Backward of a reversible valve converter, the output of which is connected to the main winding of the electric motor, speed and current sensors of the electric motor, nnye their respective inputs outputs of the first and second comparing units included in the feedback circuit regulating the speed of the torus third controllable switch, lo- g and h its kb per turn shte e e Arrange Hg in the "outputs are separately connected to yn} 19 equal inputs of the first and second controlled keys, and the first vkhrd is connected to the output of the current sensor, the inputs of the third comparison node are connected to the inputs of the first comparison node, and the output is connected to the second input of the logical switching device and to the third input of the chescoto control unit, first | is still connected to the outputs of the left; xb0 is the key, and there is only one output with the control input of the third controlled) ny through yp1avl m th turn off 1 (bff; with Y1Y | t1br N y this is 1M managing in the tetaiepToro soda controlling emrgb) Shchi with the control circuit h $; JUSCHES AND RYA. U Sh ke ch osh in: a r g | lr u «: to r1 t )  ovagSch n6 Shch - up f & m yuch: p.1aa | Щ1 || p | ly | pack | а1ЩШЩм ;; Щ | Щр | 13 й л ек о г | / Щ || W | :: Trz soy | n; |||| SHCHCHI SHCHCHCH | Y1 R image Sh sv; 1s11; | e ShtVr