SU855909A1 - Method and device for control of dc electric drive mechanism with pulsating load on the shaft - Google Patents

Description

(54) METHOD FOR CONTROLLING THE ELECTRIC DRIVE OF THE MECHANISM WITH A PULSING LOAD ON THE BUNCH AND A DEVICE FOR ITS IMPLEMENTATION These pumps are characterized by working on a complex hydraulic system, often of a large extent and requiring a large range of adjustment of the hydraulic regime with high demands on its stability, including a limited amplitude of pressure pulsations, which is due to uneven flow with uniform rotation of the working pump shaft. For pumps, which work in drilling and hydraulic opening, characteristic is also limited active power of power sources, such as diesel generators. In addition, in the opposite case, fluid circulation is required after pumping the pump and sludge settling in the hydraulic system, and circulation is restored faster with pressure pulsations at the pump discharge. For these pumps, after the circulation has been restored, it is possible to limit the level of pulsations to 2-5 /. The closest in technology to the invention is a method for controlling the direct current drive of a pulsed load mechanism on a shaft, such as a piston pump, according to which the rotation frequency of the electric motor is controlled by varying the voltage on the core and 1G of the excitation current as a function of the core current, and This is the maximum value of the core current as a function of the magnitude of the excitation current and the magnitude of the voltage on the core. This method solves the problem of controlling the speed with a mechanical characteristic close to the constant power characteristic. The soft mechanical characteristic of an electric drive with this method of control provides a satisfactory suppression of forced oscillations 1. A device is known for implementing a method for controlling the direct current drive of a mechanism with a pulsating load la to a shaft, which contains adjustable valve converters connected to the main winding and excitation winding of a direct current electric motor, series-connected voltage regulator and current regulator in the control circuit of the drive controller The inputs of which are connected respectively to the voltage sensors and the core current, the exciter current controller in the motor excitation control circuit, to the input of which the excitation current sensor is connected, the first module selector whose input is connected to the core current sensor and the output through the first block of nonlinearity to the input of the excitation current regulator, the second module selector, the input of which is connected to the core voltage sensor, and the output to one of the inputs of the adder, the second input of which is connected via the second nonlinearity unit to the output an excitation current sensor, and an output of the adder is connected to the control input of an adjustable limiting unit in the feedback loop of the regulator. The disadvantage of this method and device for its implementation is the delay in the change of speed when the torque is pulsed on the shaft, which can lead to a dynamic SUSTAINABILITY. The purpose of the invention is to increase the dynamic stability of the electric drive by improving the smoothing of the electric load diagram. The goal is achieved by the method of controlling the direct current drive of the mechanism with a pulsating load on the shaft, in addition to setting the power consumed by the electric motor and the average parameter value characterizing the mode of operation of the mechanism, measuring the actual value of this parameter, measuring the angle of rotation of the working shaft of the mechanism and the amount of power consumed by the motor, while comparing the specified average value of the parameter characterizing the mode of operation of the mechanism, with its action In this case, the comparison result is adjusted in terms of the angle of rotation of the working shaft of the mechanism and the specified power consumed by the electric motor; the corrected signal is limited as a function of the power consumed by the electric motor and used to set the voltage on the electric motor core. Moreover, as a parameter characterizing the mode of operation of the mechanism, use the value of the flow rate of the pumped substance or the pressure of the pumped substance. To achieve the goal, a controller and a control unit and a sensor of the average value of a parameter characterizing the mode of operation of the mechanism, the sensor position of the shaft of the mechanism, the sensor consumed by the electric motor, are added to the device for implementing the method of controlling the direct current drive of the mechanism with a pulsating load. the limiting unit, the multiplication unit, the adder and the phase-sensitive rectifier, with the output of the setpoint generator of the average value of the parameter characterizing the mode of operation The mechanism is connected to the inputs of the adder and the shaft position sensor, the output of the shaft position sensor is connected via the phase sensitive rectifier to the second input of the adder and to its own input, and the output of the adder is connected to one of the inputs of the multiplication unit, the second input of which is connected to the output of the parameter controller, which characterizes the mode of operation of the mechanism, and the output - to the input of the limiting unit, the control input of which is connected to the sensor consumed by the electric motor, and the output to the input of the voltage regulator. This slogan is as follows. The signal specifying the hydraulic mode of operation of the mechanism (for example, the pressure value for hydraulic opening pumps or the flow rate of the pumped substance of drilling rig pumps) as proportional to the required value of the DC voltage parameter is compared with the DC voltage signal proportional to the average value of the monitored parameter . This difference is amplified and modulated by oscillations associated with the process of uneven feeding of a piston pump. To this end, the reference signal is converted into an alternating voltage 1P1e and then the dependence of the amplitude and phase of the alternating voltage on the angle of rotation of the working shaft of the mechanism is formed using, for example, a rotating transformer. This voltage is converted into a constant voltage of alternating polarity and amplitude by means of a phase-sensitive rectifier, and the phase shift of this voltage can be regulated by changing the relative position of the pump shaft and the moving part of the rotating transformer. The amplitude voltage thus obtained is proportional to the reference signal, i.e. is unambiguously related to the average output 1p 1 by the parameters characterizing the mode of operation of the mechanism, and through the position of the moving part from the rotary transformer the received signal is determined by the function., i.e. the product of the signal of the function of the rotation angle U3-f (a), and

where Ufhv is the voltage at the output of the phase-sensitive amplifier; Us is the voltage of a signal specifying a parameter characterizing the mode of operation of the mechanism; f (a) is an alternating function; and - the angle. rotation of the working shaft

mechanism.

The resulting value, oscillatingly changing the noise with the angle of rotation of the working shaft of the mechanism, is summed with the reference signal and the resulting sum is multiplied with the difference between the specifying signal and the feedback signal. A complex signal is obtained, depending on Uj and Us. Such a quadratic dependence increases the drive speed at large mismatches and facilitates the formation of dynamic modes due to their asymptotic stability. The resulting work is used to set the operating modes of the motor mechanism. In this case, the value of the task is limited by the conditions of operation of the source of energy as a function of the power consumed and by the maximum voltage level on the electric motor bark. The presence of a controlled phase shift in the signal for a sinusoidal component allows to impose on the voltage and current of the electric motor, and consequently, on the frequency of rotation of its core oscillations, allowing to reduce the flow of the pumped substance at the position of the working shaft of the mechanism corresponding to the maximum flow at a constant rotational speed, and increase the flow rate when the working shaft of the mechanism corresponds to the minimum flow rate at a constant rush frequency. This suppresses the fundamental harmonic component of the flow or pressure fluctuations. The suppression of this component is facilitated by the choice of the angle with some lead and the coefficient K in the equation. In case of serious violations of the circulation of the pumped substance, the signal for setting the operating modes of the electric motor is limited and thus eliminates the variable component in it, which allows using the pressure pulses to accelerate the restoration of the circulation. Since the flow and pressure at the outlet of the pump are a function of Us, the coefficient Uj compensates for the effect of a constant motor time (electromagnetic constant time1 and electromechanical constant time) on the amplitude of forced oscillations imposed on the rotational frequency of the pump shaft. The drawing shows a diagram of the device. Anchor 1 of the electric motor with the input of the sensor 2 voltage on the bark in series with the sensor 3 of the core current

connected to the output of the valve converter 4. The output of the converter 4 is connected to the output of the current regulator 5, the first input of which is connected to the output of the voltage regulator 6 and the first input of the limiting unit 7, made in the form of a diode-bridge circuit torus 5 of the current box is connected to the output of the sensor 3 of the current box and the input of the selector 8 of the current box module. The output of the extractor 8 of the current core module is connected to the first input of the power sensor 9 and to the input of the nonlinearity unit 10, the output of which is connected to the first input of the excitation current controller 11, to the second input of which the output of the excitation current sensor 12 and the input of the nonlinearity unit 13 are connected. The input of the excitation current sensor 12 is connected between the motor excitation winding 14 and the output of the valve converter 15, the input of which is connected to the output of the excitation current regulator 11. The output of the voltage sensor 2 is connected to the first input of the regulator 6 voltage and to the input of the selector 16 module. The output of the module 16 is connected to the second input of the power sensor 9 and to the first input of the adder 17, to the second input of which the output of the nonlinearity unit 13 is connected, and the DC output of the diode bridge circuit is connected to the opposite output, the second AC input of this circuit is connected to the third input of the regulator 6, the second input of which is connected to the output of the limitation unit 18, the first input of which is connected to the output of the power sensor 9, and the second input is connected to the output of the multiplication unit 19. To the first input of the multiplication unit 19 is connected the output of the regulator 20 of the parameter characterizing the mode of operation of the mechanism, to the first input of which the output of the sensor 21 of the average value of the parameter is connected. The output of the setpoint generator 22 of the average value of the parameter characterizing the mode of operation of the mechanism is connected to the second input of the controller 20 of the parameter characterizing the mode of operation of the mechanism, to the input of the constant-voltage converter 23 and to the first input of the adder 24. The output of the converter 23 is connected to the contactless input sensor 25 of the position of the working shaft of the mechanism and the first input of the phase-sensitive rectifier 2 The output of the sensor 25 of the position of the working shaft of the mechanism is connected to the second input of the rectifier 26, the output of which is connected to the second input of the adder 24, the output of which is connected to the input of the multiplier block 19.

The device works as follows.

Claims (4)

Specifies the signal from the output of the gauge 22 parameter characterizing the mode of operation IU. of the pump, goes to both inputs of the multiplication unit 19, with the first input through the parameter controller 20, and the second directly. The reference signal at the input of the parameter controller 20 is compared with the feedback signal generated at the output of the sensor 21 of an average parameter value, such as an average pressure sensor or average flow rate, which provides proportional control of the mechanism or regulation of the mechanism of a different, more complex to the law. Until the power consumed by the electric motor 1 reaches the maximum permissible magnitude, the signal at the output of the limiting unit 18 is determined by the voltage at the output of the sensor 9 of the power consumed by the electric motor. When the power consumed by an electric motor exceeds the value allowed by the operating conditions of the power source, such as an autonomous diesel generator, the voltage at the output of the limiting unit 18 and, therefore, the voltage at the input of the regulator 6 is limited, which leads to the limitation of voltage and current box electrode. Further consideration of the above operation of the device is carried out separately through the high-speed control channel (bandwidth 10-15 Hz) and the slow-acting channel (f - 4-5 Hz). The high-speed control channel includes regulator 6, voltage, current regulator 5, valve converter 4, current sensor 3, sensor 2, measles 1 h; motor, selectors 8 and 16 of the signal module, adder 17, block 7 The slow acting channel, whose passband is small due to the significant inductance of the excitation winding 14, contains nonlinearity blocks 10 and 13, the excitation current regulator G1, the valve converter 15 and the excitation current sensor 12. The voltage reference signal at the second input of the regulator 6 contains a relatively constant component that determines the required average mode of operation of the mechanism and a relatively rapidly oscillating component (f 5-7 Hz) associated with a change in the position of the working shaft of the mechanism and serves to create fluctuations in the frequency of rotation of the motor 1, compensating for the unevenness of the filed at a constant speed. Both components at the input of the voltage regulator 6 are compared with the signal taken from the output of the voltage sensor 2, and with the help of the voltage regulator 6, the cor current current signal is generated, which at the input of the current regulator 5 is compared with citrHanoM, removed from the output of the sensor 3 current box. The signal from the output of the regulator 6 is limited as a function of parameters affecting switching by means of a node consisting of block 7, adder 17, a selector module 16, a nonlinearity block 13, voltage sensors 2 and 12 excitation currents. A signal is generated at the output of the current regulator 5 of the core, which is amplified by a valve converter and forms the law of change of the current of the electric motor, providing compensation for the unevenness of the mechanism feed. In the limiting modes, for example, when using the invention in control systems of a drilling pump in the circulating mode, the signal at the output of the sensor 21, which uses an average flow sensor, is minimal, which causes the maximum signal at the output of the parameter regulator 20. In this mode, the variable component is cut off by the restriction unit 18 and, at the outlet of the pump, facilitates the restoration of circulation. In this way, the rotational speed is controlled with adaptive changes in the drive coupling, which is not possible in the known compensating devices. The unit for the slow channel mode is sensor 3 for the core current. Using the selector 8 of the module, the absolute value of the signal at the output of the current sensor 3 of the core is determined, and then using the nonlinearity unit 10, a reference signal is generated at the input of the regulator And the excitation current, where it is compared with the feedback signal taken from the output of the excitation current sensor 12 . The nonlinearity unit 10 performs the functions of forming an energy dependence optimal in terms of energy, the main current excitation current, as well as limiting the maximum and minimum excitation values. The mechanical characteristic in this case is hyperbolic, i.e. optimal in autonomous electric drive. On the whole circuit: sensor 3 of the core current - selector 8 module - nonlinearity unit 10 - excitation current regulator 11 - converter 15 output, oscillations of the output signal caused by the action of the sensor 25 of the shaft of the mechanism act. These oscillations are absent in the signal at the output of the excitation current sensor 12, since the time constant of the motor excitation winding is greater than or equal to 1 s, and the converter 15 for pump drives is selected with a small voltage margin. However, voltage fluctuations at the input of the non-linearity unit 10 at small values of the core current are partially detected, which leads to an increase in the flow of the electric motor and to facilitate the development of these oscillations by the motor core. The signal taken from the output of the excitation current sensor 12 along the circuit: nonlinearity block 13 — adder 17 — block 7, is used to limit the current of core 1, based on the switching conditions of the motor core. Thus, as a result of the application of this invention, the parameters at the output of the mechanism are adaptively stabilized, the power consumed from the prime mover is limited, and the mode of the DC motor is limited. Claim 1. Method of controlling the direct current drive of a mechanism with a pulsating load on a shaft, such as a piston pump, according to which the frequency of rotation of the motor is controlled by varying the voltage on the core and changing the excitation current in the function of the current of the core, while limiting the maximum value of the current of the core as a function of the magnitude of the excitation current and the magnitude of the voltage on the cortex, which is different in order to increase the dynamic stability of the electric drive due to the improvement of load smoothing The diagrams additionally set the power consumed by the electric motor and the average value of the parameter characterizing the mode of operation of the mechanism, measure the actual value of this parameter, measure the angle of rotation of the working shaft of the mechanism and the beam; shrink the power consumed by the electric motor, and compare the specified average value the parameter characterizing the mode of operation of the mechanism, with its actual value, the result of the comparison is corrected as a function of the angle of rotation of the working shaft of the mechanism and the specified value The power consumed by the motor, the corrected signal is limited as a function of the amount of power consumed by the motor, and is used to set the voltage on the core of the motor. 2. The method according to p. 1, about tl and h and y with the fact that as a parameter characterizing the mode of operation of the mechanics, use the value of the flow rate of the pumped substance. 3. The method according to p. 1, about tl and h and y with the fact that as a parameter characterizing the mode of operation of the mechanism, use the pressure of the pumped substance. 4. A device for implementing the method according to claim 1, comprising adjustable valve converters connected to the core winding and excitation winding of a DC motor, voltage regulator connected in series, and a current regulator in a control circuit of a converter circuit, to the inputs of which are connected respectively voltage and current sensors, field current regulator in the motor excitation control circuit, to the input of which the field current sensor is connected, the first selector module, the input to which It is connected to the current sensor core, and the output is via the first nonlinearity unit to the input of the field current controller, the second module selector, the input of which is connected to the core voltage sensor, and the output to one of the adder, the second input of which is through the second nonlinearity unit connected to the output of the sensor current excitation, and the output of the adder is connected to the control input of the adjustable limiting unit in the feedback circuit of the voltage regulator, characterized in that, in order to improve the smoothing of the load diagram, The puller and the setpoint adjuster and rtchik of the average value of the parameter connected to its inputs, characterizing -1 o the operating mode of the mechanism, the position sensor of the working shaft, the sensor consumed by the electric motor, the limiting unit, the multiplication unit, the adder and the phase-sensitive rectifier, and the output of the setpoint average the value of the parameter characterizing the mode of operation of the mechanism is connected to the inputs of the adder and the shaft position sensor; the output of the shaft position sensor is connected to the second input via the photoelectric rectifier. torus to its own input, and the output of the adder to one of the inputs of the multiplication unit, the second input of which is connected to the output of the parameter controller characterizing the mode of operation of the mechanism, and the output to the input of the restriction unit, the control input of which is connected to the date of consumption power output, and the output is at the input of a voltage regulator. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 56813J, cl. H 02 R 5/26, 1976.