SU855910A1 - Method and device for control of dc electric drive - Google Patents

Description

chick frequency of rotation on the shaft. The armature of the motor is connected to a regulated source of direct voltage, and the field winding is connected to a valve driver, having an integrated regulator of the field current at the input. The device contains the core current and excitation current sensors, the torque value setting unit, the calculating unit of the actual motor torque value, the actual and set torque value comparison unit, the rheostat with the servo motor, which core is connected to the output of the comparison unit, and the rheostat output is connected to the controller setting input excitement 1.

The disadvantage of this method and device that implements it is that they do not take into account the effect of changes in the voltage on the cortex and the excitation current on the commutation. In addition, they do not provide for limiting impacts when selecting gaps in gears and jerks when choosing slacks of ropes, which makes it impossible to use them in the electric drive of drilling rigs and excavators. Known speed control method

DC motor, which provides for the regulation of the excitation current as a function of the core current in a certain zone, which provides for controlling the speed above the nominal mechanical characteristics close to those of a constant-power electric drive vagga 2. The disadvantages of this method are: the need for its implementation use of electric motors with specially selected parameters, as well as the fact that it does not take into account the laws determining the change in the permissible value of and when changing the armature of the motor. In addition, the application of this method is difficult for reversible high-speed electric drives.

There is also known a method which provides for the regulation of an autonomous electric drive of direct current, including a system of a direct current generator - an electric motor. It measures the voltage on the core and the current of the generator, compares these values with 1 settings, multiplies the larger of the compared signals and supports the signal ) Generating at a given level by acting on the generator excitation current and changing the engine excitation current to the generator core current, and also compare the signal proportional to the current excitation of the motor with a signal proportional to the current of the generator core and a differential signal is applied to the control system of the excitation current of the electric motor 3.

However, this method can only be used with a compact arrangement of the generator and engine, since electric motors with a current of 1000-500 kW, required by D1M bzfovyh installations and most excavators and construction cranes, can be performed only at relatively low levels. In addition, the use of individual generators that are imminent when they are performed. Direct current in mechanisms such as drilling rigs, excavators and construction cranes increases the power of the installed equipment and makes redundancy difficult. The disadvantage of this method is that it does not take into account the limitations of the operating modes of the electric drive according to the switching conditions. The implementation of this method will require such a second power source, preferably an alternating current, to power the Excitation current control systems.

The closest to the invention to the technical essence is a method of controlling an electric drive of direct current, according to which the crust current and excitation current of the electric motor, the voltage on its core and the supply voltage are extracted, from which the signal proportional to the amplitude is extracted, while the signal the settings of the maximum permissible current of the core are controlled as a function of the measured signals of the excitation current and voltage on the crust, and the magnitude of the excitation current is controlled as a measured signal of the current of the core, and the limitation of the lower The level of the excitation current is kept constant, and the upper level is varied as a function of the amplitude of the supply voltage 4.

A device for implementing a method of controlling an electric drive of direct current, containing cn {% are converters in the core of an electric motor and its excitation windings, subsequently connected to the reference voltage on the core, voltage regulator and current regulator, to the inputs of which are connected sensors of voltage and current, as well as a regulator with a limiting unit and an excitation current sensor, a limiting unit of the current in the core, connected to the feedback circuit of a voltage regulator, to the control input of which is connected en adder, and two blocks of nonlinearity.

The disadvantage of these methods and devices is incomplete consideration of requirements arising from autonomous power supply or limited power, which must be brought to the work of the organs of the mechanism, while limiting the power supplied to the working organs of the mechanism, or reactive power consumed by the tyrnstor converter its from a synchronous generator of comparable power.

The purpose of the invention is to limit the power consumed by the electric drive of an autonomous power source and limit the power supplied to the working body of the mechanism.

The goal is achieved by the fact that, in a known method, the active and reactive power consumed by the electric drive is additionally compared to the signals that are set to these parameters, and when the active power exceeds the acceptable value, the motor voltage setting signal is limited permissible level limit the signal to the maximum permissible current cor.

In the device, the goal is achieved by the addition of active and reactive power sensors, control devices for the permissible level of active and reactive power, current and voltage transformers, two comparators, a transistor, a diode-bridge circuit, and three resistors. the voltage in the crust is connected to the input of a bridge circuit, the three arms of which are formed by resistors, and the fourth is connected to the diagonal of the alternating current of the diode bridge circuit, the diagonal of the direct current of which includes the collector-emitter transition Ter of the transistor, the base of which is connected to one of the outputs of the first comparator, the second output of which is connected to the emitter of the transistor, the inputs of the first comparator are connected to the outputs of the unit of the admissible level and the active power sensor, the inputs of which are connected to the outputs of current transformers and for example on the AC input of the converter in the core of the electric motor circuit, and the output of the reactive power sensor together with the output of the unit of permissible ur Reactive power is connected to the inputs of the second comparator, the output of which is connected to the input of the adder.

The drawing shows a functional diagram of the device.

The device contains measles 1; a motor; the sensor input 2 of the voltage on the core is connected in series with the sensor input 3 of the circuit current to the output of the thyristor converter 4. The input of the thyristor converter 4 is connected to the output of the current regulator 5 of the core, to the first input of which the sensor output is connected 3 current box To the second input of current regulator 5, a voltage regulator 6 on the crust is connected and one of the ac inputs of a diode bridge circuit 7 that functions as a current limiting unit for the core, the second AC input of which is connected to the input of voltage regulator 6 cortex, to the other inputs of which pj are connected the output of the sensor 2 voltage on the cortex and the output of the bridge circuit, formed by three equal resistors 8-10, and the diagonal of the alternating current of the diode bridge circuit 11. One common point of resistors 8 and 9

Q from the setpoint 12 outputs of the allowable voltage level on the bark. The second output of the setting device 12 is connected to the common point of the resistor 10 and one of the AC inputs of the diode bridge circuit 11, the second input of the AC

5 which, together with one of the terminals of the resistors 8, is connected to the common point of the inputs of the voltage regulator 6. A collector transistor 13 is connected to the positive output of a di-bridge circuit 11; an emigter output of the transistor 13 and one of the outputs of the first comparator 14 are connected to the negative output of a diode-bridge bridge circuit 11. A output of 15 to 5 is connected to the first input of the comparator 14 empty voltage level, the output of the active power sensor 16 is connected to the second input. The inputs of the active sensor 16 and the reactive power sensor 7 are connected to the output of the current transformer 18 and connected to the input of a voltage amplitude sensor 19 supplying a thyristor converter 4. The output of the sensor 17 together with the output of the generator 20 of the allowable level of reactive power is connected to the input of the second comparator 21, the output of which is connected to one of the inputs of the adder 22, to the two other inputs of which are connected the outputs of the non-linearity blocks 23 and 24. The input of the nonlinearity unit 23 is connected to the output of the voltage sensor 2 at the core

and AC inputs of a diode-bridge circuit 25 (excitation current limiting unit), to the positive terminal of which a positive terminal of the sensor 19 is connected and one of the terminals of the resistor 26, the second of which is connected to one of the terminals of the field current regulator 27 and is negative clamp sensor 19. To other inputs of the regulator 27 of the excitation current are connected the negative output of the diode bridge circuit 25, the output of the sensor 28 of the excitation current 28 and the output of the nonlinearity unit 29, the input of which is connected to the output of the sensor 3 of the current cor. To the output of the excitation current controller 27, the input of the controlled converter 30 is connected, to the output

which is connected in series with the input of the sensor 28 of the excitation current 28, the excitation winding 3 of the electric motor 1. The primary winding of the current transformer 18 is connected in series in one phase conductor of the network according to 785

The belt current supplying the converter 3 to the same phase is connected to the input of the voltage amplitude sensor 19. A nonlinearity block 32 is connected between the output of the excitation current controller 27 and the input of the nonlinearity unit 24. The device works as follows. In the absence of a signal at the output of the setting device 12, there is no signal for setting the inputs of the voltage regulator 6 on the core, current regulator 5 of the core and converter 3. There is no signal at the output of the converter 3, at the output of the voltage sensor 2, at the core and on the output of the current transformer 18. Consequently, the excitation current, determined by the voltage at the output of the nonlinear unit 29, is minimal and minimal at the output of the excitation current sensor 28, which determines a small voltage at the output of the adder 22. The absence of a signal at the output of the current transformer 18 causes no signal at the output the sensors 16 and 17 of the active and reactive power of the comparators 14 and 21, the closed state of the transistor 13, which determines the operation of the bridge circuit consisting of resistors 8-10, and the diode bridge circuit 11. as a divider. When a setpoint signal appears at the output of the setting device 12, half of this signal is fed to the input of the voltage regulator 6, the output voltage of which is first limited by a small value due to the low voltage at the output of the adder 22 applied oppositely to the outputs of the direct current diode-bridge circuits 7 Under the action of this voltage, a signal appears at the inputs and outputs of the current regulator 5, the converter 4, the sensors 2 and 3, thereby forming feedbacks necessary for the stable operation of the drive current feedback p and voltage. The appearance of a signal at the output of sensor 3 to select a gap in the gears and slacks in the cables does not lead to a large current, as a result of which the selection of the gaps in the gears takes place with a small moment, i.e. limited impact force after the end of this mode. The occurrence of current in the electric motor corona circuit causes the appearance of a small signal at the output of the current transformer 18 and a small signal at the output of the active power sensor 16 3 electric motor and the reactive power sensor 1 of the electric motor. Since the signals at the output of the sensors 16 and 17 of the active and reactive power in this mode are less than the signals at the output of the adjusters 15 and 20 of the allowable level, respectively, of the active and reactive power at the input of the converter 3, there are no signals at the output of the comparators 14 and 21.

Claims (4)

 The signal at the output of the voltage amplitude sensor 19 supplying the thyristor converter 2 causes current to flow through the resistor 26; a drop from this current blocks the output of the diode bridge circuit 25, so that in this mode there is no connection between the output of the voltage sensor 2 field current torus 27. After the choice of gaps or slacks of ropes is completed, the current in the core circuit of the electric motor 1 becomes more powerful and under the action of this current of the core circuit, an increase in the signal at the output of the nonlinearity unit 29 and, consequently, a signal at the input and output of the excitation regulator 27 and converter 30 occurs. at the output of the controller 27 of the excitation current and the converter 30 in this mode is caused to be lowered (due to the electromagnetic inertia of the motor winding 31 of the motor O by the feedback signal of the current Under the action of the increased voltage at the output of the converter 30, the current in the excitation winding 31 and the signal at the output of the excitation current sensor 28 begin to rise. Simultaneously, the voltage at the output of the nonlinearity unit 32 occurs. Under the action of the increasing signal at the output of the excitation current sensor 28 and block 2 of nonlinearity an increase in the signal at the output of the adder 22 and a further increase in the signals at the output of the regulators 5 n 21 of the main circuit current and the excitation current occurs. As the excitation current increases, the signal at the output of the excitation current sensor 28 increases, and the total signal at the input of the current regulator 27 decreases, which leads to a gradual decrease in the direct effect of the magnitude of the voltage at the output of the excitation current regulator 27 to voltage. at the output of the adder 22. Positive communication acting along the contour; output of current sensors cor 3 - input of nonlinearity unit 29 - output of nonlinearity unit 29 input of excitation current regulator - output of excitation current regulator 27 - nonlinearity 32 block - adder of 22-diode bridge circuit 7 - voltage regulator 6 - current regulator cor - converter 6 - cor 3 current sensor, provides a reliable and fast increase of the excitation current to the current of the corona circuit after the selection of gaps in the gears has been completed. The effect of this positive feedback decreases with decreasing forcing at the output of the regulator 27 of the excitation current due to the effect of stronger feedback on the excitation current supplied from the output of the excitation current sensor 28. Thus, the adaptation of the torque control circuit, i.e. core current and excitation current, and therefore the main flow, to the conditions before and after the end of the choice of the gap. When current increases, the output of converter 3 increases in the first stage of acceleration of the electric motor, the reactive power consumed by the converter, which has a negative effect on the heating of the stator and rotor windings of the generator supplying the converter, and also causes distortion of the voltage, which is dangerous for other converters powered by this generator. This negative phenomenon is eliminated in the present invention as follows. The signal proportional to the reactive power received at the output of the sensor 17 of reactive power is compared at the input of the comparator 21 with the signal determining the maximum allowable value of this power. When powering from this generator only one converter, the reference signal is constant, and in all other cases it is determined by the total reactive power consumed by other converters from this and other generators running in parallel with it. The signal at the output of the comparator 21 is proportional to the excess of the actual consumption of reactive power above a given level and affects the input of the adder 22 in such a way that it limits the voltage at the output of the voltage regulator 6, thus limiting the reactive power consumed by the converter 3. As the motor 1 accelerates, the voltage on its core increases and the power consumed by converter 3 increases. At the same time, the signal at the output of the active power sensor 16 grows. When this signal at the input of the comparator 14 becomes larger than the signal at the output of the setpoint 15 of the permissible active power level, then the output of this comparator appears a voltage proportional to the difference of these signals. Under the action of this voltage applied to the base-emitter junction of transistor 13, the resistance of the emitter-collector junction of this transistor decreases, resulting in a connection between the input of voltage regulator 6 and the output of voltage regulator 12. at the output of the converter 3 and the limitation of the active power consumed by the converter 3. Simultaneously with the acceleration of the electric motor 1 and the voltage rising at the output of the converter 3, the voltage at the output of the nonlinearity unit 23 increases, as a result of which, in accordance with the laws determining the allowable value of the current, the voltage at the output of the adder 22, controller 6 voltage and current of the core of the electric motor 1. Therefore, the signal at the output of the sensor 3 of the current of the core, of the nonlinearity block 29 and the input of the regulator 27 of the excitation current decreases, which, after a decrease in the current of the core, causes Nation dispersal 10 August motor to a speed determined by the minimum drive current value defined by the block 29 of non-linearity. With the beginning of the braking mode, the current of the corona circuit changes its sign. When its value passes through zero, the reference signal at the input of the exciter current regulator 27 disappears, which leads to a further decrease in the excitation current, the voltage at the output of the adder 22 and, therefore, the core current and the moment. Therefore, the signal at the output of the current sensor 3 cor, the nonlinearity unit 29 and the regulator 27 of the excitation current 27 decreases, which causes, after the current drops below the nominal, further acceleration of the electric motor to a speed determined by the minimum value of the excitation current specified by the nonlinearity unit 29. Therefore, the choice of gaps in gears or weak ropes is made at a reduced moment value, which reduces the impact force. After the beginning of the braking mode, the sign of the active power changes and the sign of the signal at the output of the active power sensor 16 begins to coincide with the signal of the setpoint 16 of the permissible active power level, the comparator 14 does not generate a signal on its output that unlocks the transistor 13, and The braking power, which is important for limiting the dynamic forces in the mechanism, is not limited, which makes it possible to significantly reduce the likelihood of breakage of the drill string or gears. The reactive component of the total power in this mode does not change sign and the current limiting by this criterion operates as described. Further braking is determined by the ratio of the signals at the output of the voltage sensors 2 and the voltage amplitude 19. With an excessively fast increase in the EMF of the core 1, the voltage and the current of the circuit, or a deep decrease in the supply voltage, the inverter may overturn. This phenomenon is eliminated due to the fact that if the signal at the output of the dizdab 2 voltage becomes larger than the signal at the output of the voltage amplitude sensor 19, then the output of the direct current of the diode-bridge circuit 25 produces a signal that limits the current. Claim 1. The method of controlling an electric drive with direct current, according to which the core current and the excitation current of the electric motor, the voltage on its core and the supply voltage from which the signal is extracted are measured. proportional to amplitude, with the signal the maximum permissible current of the core is controlled as a function of measured excitation current and voltage signals on the cortex, and the magnitude of the excitation current is measured as a measured current signal of the core, and the limitation of the lower level of the excitation current is kept constant and the upper level is changed in voltage amplitude supply network, characterized in that, in order to limit the amount of power consumed by the electric drive of an autonomous power source and limit the power supplied to the working body of the mechanism, the active and reactive power consumed by the electric drive is divided, the received signals are compared with the reference signals of these parameters, and when the active power exceeds the permissible value they limit the reference voltage signal on the electric motor core, and when the reactive power exceeds the permissible level, the reference signal is limited . 2. A device for implementing the method according to claim 1, comprising controlled converters in the core of an electric motor and its excitation windings, a series-connected voltage source on the core, a voltage regulator and a current regulator, the inputs of which are connected to a cooTBeTCTBetmo voltage and current sensor core, as well as a regulator with a limiting unit and an excitation current sensor, a current limiting unit and a core connected to the feedback circuit of a voltage regulator, to the control input of which I is connected an adder, and two nonlinearity blocks, excl Now, 410, in order to limit the amount of power consumed by the electric drive of an autonomous power source and power, lead to the working body of the mechanism, two active and reactive power sensors are introduced into it, current and voltage transformers, two comparators , a transistor, a diode-bridge circuit and three resistors, while the output is set to the voltage on the bark connected to the input of a bridge circuit, the three arms of which are formed by resistors, and the fourth is the diagonal of the changes The current of the diode-bridge circuit, in the diagonal of the direct current of which the collector-emitter junction of the transistor is connected, the base of which is connected to one of the outputs of the first comparator, the second output of which is connected to the emitter of the transistor, the inputs of the first comparator are connected to the outputs of the allowable level indicator and the active sensor power, the inputs of which, together with the inputs of the reactive power sensor, are connected to the outputs of the current and voltage transformers connected at the AC input of the converter in the circuit to The electric motor, and the output of the reactive power sensor, together with the output of the unit of permissible reactive power level, are connected to the inputs of the second comparator, the output of which is connected to the input of the adder. Sources of information taken into account in the examination 1. The patent of Germany No. 2005680, cl. 21 from 59/35, 1973. 2. Japanese Patent N 49-34406, cl. 55 S 2Sh.Z, N 02 R 7/00, 1974. 3. USSR author's certificate number 341694, cl. B 60 L 11/04, 1965. 4. USSR author's certificate number 568131, cl. H 02 R 5/26, 1976.