RU2066757C1 - Method for automatic speed control over feed of coal miners and device for implementing the same - Google Patents

Abstract

FIELD: mining. SUBSTANCE: load current and cutoff current as a function of voltage are set on terminals of electric motor of miner cutting drive. Mean consumption current I_m, mean square current deviation σ_I and probable value of maximum current I_max are determined in the presented mathematical expression. I_m and I_max are compared with preset values and keep them at the level that is not higher than set points by adjusting speed of the coal miner. Device for implementing the method contains two adjusting channels. One channel has current sensor and aperiodic link connected in series. The second channel contains current sensor, adder, quadrator, aperiodic link, square root evaluator, the first proportional link, and the second proportional link with adjustable dead zone connected in series. Inputs of the two channels are connected to control system by miner feed mechanism. EFFECT: high capacity. 2 cl, 2 dwg

Description

 The alleged invention relates to a system for automatically controlling the process of coal mining by combines and is intended, in particular, for automatically controlling the feed rate of a coal combine.

 Known methods of regulating the load of the cutting engine of a coal combine.

 There is a method of automatic load control using the IPIR-3M controller (see the book by B.M. Starikov, V.L. Azarh, Z.M. Rabinovich "Asynchronous electric drive of shearers". M. Nedra, 1981, p. 187, fig. X.5). The method is based on the principle of maintaining the constant power of the cutting drive of a coal processor, using the linear dependence of the power on the motor shaft on the feed speed. In this case, it is not power that is measured, but the instantaneous value of the current consumed by the motor. Under the conditions of mine networks and an abruptly variable load, there is no linear relationship between the power consumption and the current consumed, as a result of which regulation is accompanied by the appearance of self-oscillations in the feed rate of the combine.

 A known method of controlling a mining machine (AS N 1105640, class E 21C 35/24), providing adjustable loads by changing the feed rate, including setting the current setting corresponding to the rated load, and the cut-off setting corresponding to the idling current of the electric motor, continuous measurement of the instantaneous current of the electric motor in a given frequency range, its comparison with the current setpoint and cutoff setpoint. In this control method, the variability of the resistance to cutting of the destructible coal is not taken into account, and in addition, the derivative of the current must be determined.

 Closest to the proposed method is a control method through a currently commercially available load regulator of the Uranus type developed at the Donavtomatgormash Institute (see the book B. Asarikov, V. L. Azarh, Z. M. Rabinovich, Asynchronous electric drive of shearers ". M. Nedra, 1981, p. 195, Fig. X.9), which includes setting the nominal current and cut-off current, continuous measurement of the instantaneous current of the cutting motor of a mining combine cutting drive. Due to the wide range of frequencies of changes in the current consumption and the low speed of the actuating device for controlling the feed rate, self-oscillations of the feed rate of the coal processor occur.

 Device by A.S. N 1105640 includes a unit for setting the current setpoint corresponding to the rated load, and a cut-off setpoint corresponding to the no-load current of the electric motor, a unit for measuring the motor current in a given frequency range, a unit for comparing with the current setpoint and the cut-off setpoint.

 This device does not take into account the functional relationship between the motor current and the feed rate.

 Closest to the claimed is the Uranus device (B.Ya. Starikov, VL Azarh, ZM Rabinovich "Asynchronous electric drive of shearers". M. Nedra, 1981, p. 195, Fig. X.9) containing current and feed rate sensors, elements for comparing actual and target current and feed rates. This device, due to the low speed and high frequency of changes in the current consumption of the cutting motor, causes the oscillation of the feed rate of the combine and, as a result, shutting it off by cutoff.

 The aim of the proposed invention is to increase the reliability of the automatic control system for the feed rate and the cutting motor of a coal combine.

среднеквадратичное отклонение потребляемого тока по формуле

вероятное значение максимального тока двигателя по формуле
I_max= I_cp+βσ_I
где i(t) текущее мгновенное значение потребляемого тока;
I_ср средний ток;
σ_I среднеквадратичное отклонение тока;
I_max вероятный максимальный ток;
β задаваемое относительное уклонение;
T₁, T₂ постоянные времени апериодических звеньев, величина которых должна быть в 10-20 раз больше постоянной времени затухания корреляционной функции графика тока,
и сравнивают I_ср c заданным значением тока двигателя, регулируя скорость подачи, в функции разности тока уставки и I_ср I_max сравнивают с заданным значением тока отсечки, устанавливаемым автоматически в функции уровня напряжения на зажимах двигателя, и заданной вероятностью b отсутствия опрокидывания двигателя, снижая скорость подачи при вероятном максимальном токе, превышающем зону нечувствительности нелинейного элемента. Таким образом, в схеме имеются элементы, прогнозирующие вероятность превышения нагрузки двигателя резания выше допустимой и опережающие снижение скорости подачи комбайна при повышении вероятности опрокидывания его двигателя резания.This goal is achieved in that in a method for automatically controlling the feed rate of coal combines, including setting the current setting corresponding to the rated load, the cut-off setting corresponding to the maximum allowable current of the engine, continuous measurement of the instantaneous current of the motor of an electric motor cutting a mountain combine, determine
average current consumption according to the formula

standard deviation of the consumed current according to the formula

the probable value of the maximum motor current according to the formula
I _max = I _cp + βσ _I
where i (t) is the current instantaneous value of the consumed current;
I _cf average current;
σ _I rms current deviation;
I _max probable maximum current;
β preset relative deviation;
T ₁ , T ₂ time constants of aperiodic links, the value of which should be 10-20 times greater than the decay time constant of the correlation function of the current graph,
and compare I _cf with the set value of the motor current, adjusting the feed rate, as a function of the difference of the set current and I _cf I _max compare with the set value of the cut-off current set automatically as a function of the voltage level at the motor terminals and the set probability b of the absence of motor overturn, feed rate at the probable maximum current exceeding the deadband of the nonlinear element. Thus, the diagram contains elements that predict the probability of exceeding the load of the cutting motor above the permissible one and outstripping the decrease in the feed rate of the combine with an increase in the likelihood of the overturning of its cutting engine.

 This goal is also achieved by the fact that in the device containing a series-connected current sensor and a low-pass filter, two comparison elements, a voltage sensor is introduced, elements including the average value of the consumed current and its standard deviation are introduced two control channels, the first channel containing a sensor current, the output of which is connected to the input of the aperiodic link, the output of which is connected to the input of the adder, and the second input of the adder is connected to the output of the current sensor, the output of the adder is connected to the first and second inputs of the quadrator, the output of which is connected to the input of the aperiodic link, the output of which is connected to the input of the square root calculator, the output of which is connected to the input of the proportional link, the output of which is connected to the first input of the adder, the second input of which is connected to the output of the aperiodic link, and the output the adder is connected to the first input of the proportional link with a dead zone, the second input of which is connected to the output of the voltage sensor, and the output is connected to the input of the adder of the second channel Hovhan, a second input coupled to a motor current reference element, and the output of the adder is connected to the second input of the adder of the first channel regulation, whose output is connected to the input of the hydraulic pump control circuit harvester feeder.

 The claimed technical solution meets the criterion of "significant differences", since although the applied elements carrying out mathematical operations are known in science and technology, but thanks to the proposed method of their use, system parameters are determined that do not coincide with the properties of the known technical solutions.

 The essence of the alleged invention is illustrated by the following description and drawings, where in FIG. 1 shows a functional diagram of the device, and in FIG. 2 shows a diagram of the implementation of the device on serial microcircuits.

 The proposed device, FIG. 1, contains on the first channel a series-connected current sensor 1 and an aperiodic link 2 for averaging the current consumption value; on the second channel, a current sensor 1, an adder 3, centering the deviation of the instantaneous current value relative to its average value, a quadrator 4, an aperiodic link 5, a square root extraction unit 6, a proportional link 7 are connected in series. The outputs of the first and second channels are connected to the corresponding inputs of the adder 8 whose output is connected to the first input of the proportional link 9 with a dead zone proportional to the maximum permissible motor current, the second input of this link is connected to the output of the sensor voltage 10, which signal is proportional to the voltage at the motor terminals, determines the magnitude of the dead zone, and thus the magnitude of the maximum motor current, which determines the maximum motor torque of the conditions to prevent its overturning. The output of link 9 is connected to the second input of the comparison element 11, to the first input of which a signal of a given current of the cutting motor is applied. The output of link 11 is connected to the second input of the comparison element 12, which adjusts the speed of the feed mechanism of the combine 13 and thereby the average current consumption of the cutting motor 14.

 In FIG. 1 indicates the elements of the functional diagram of the coal processor. These elements are immutable both in the prototype and in the present invention.

K ₁ , K _{2 are} the proportionality coefficients between, respectively, V _p (p) feed rate and the moment of resistance M _s (p). The link indicated by 1 / J _p , together with M _c (p) and M (p) is the equation of motion of the rotor of the engine in the operator form of writing. All marked with a sign (p) represent the operation parameters of the coal processor electric motor: current, torque, rotational speed in the operator recording form, which is generally accepted in the electric drive when designating input and output parameters of functional circuit elements.

 The essence of the proposed method is illustrated by the following description and Fig. 1.

Measured by the current sensor (I), the current I (p) consumed by the motor is averaged over the aperiodic link (2) with a time constant 10.20 times longer than the correction function decay time of the current harvester consumed by the cutting motor. On the adder (3), the mathematical operation DI = I (t) -I _{cp of} centering the instantaneous value of the actual current consumption relative to it is the average value. On the quadrator (4), the centered value of the current is squared and averaged on the aperiodic link (5). The output of this link is the dispersion of the current consumption (D _I ). Removing the square root (6) from the dispersion of the consumed current, the root-mean-square deviation of the consumed current (σ _I ) is obtained at the output of the link (6). Multiplying the proportional link (7) by the standard deviation (σ _I ) by the relative deviation β 2.5.3, we set the probable absolute deviation of the maximum current from its average value. Given the relative deviation b 2.5.3, we predict that the maximum current consumption with a probability of 0.98.0.995, respectively, will not exceed
I _max ≅I _cp + βσ _I.
The value of I _{max is} determined on the adder (8) and, if this value exceeds the deadband of element (9), which is equal to the maximum permissible motor current setting (setting), then from the output of element (9) a signal proportional to the difference I _max -I _set = ΔI6 will reduce the set motor current I _ass . At the same time, on the adder (12), the set motor current is compared with its average value taken from link (2), and when I _cf > I _ass, the feedrate of the combine is proportionally reduced to the equality I _cf I _ass . Since the overload capacity of the motor in current is proportional to the voltage at its terminals, the deadband of link 9 (maximum cut-off current setting) is automatically set proportionally to the voltage at the motor terminals using a voltage sensor (DN) link 10.

 Using the proposed method and device will improve the reliability of the electric drive cutting the harvester, eliminate the occurrence of self-oscillations in the feed rate associated with the mismatch of the control methods implemented using the Uran load regulator and the characteristics of the combine system destructible material.

Claims (2)

1. A method for automatically controlling the feed rate of coal combines, including setting a current setting corresponding to the rated engine load, a cut-off setting corresponding to the maximum allowable engine current, continuous measurement of the current value of the consumed current i (t) of the mining machine cutting electric drive, characterized in that it is determined values of the average value of the consumed current I _{c p} , the standard deviation of the consumed current σ _I and the probable value of the maximum motor current I _{m a x} by formulas
I _{with p} i (t) • (1 e ^{- t / T} ₁ ;

I _max = I _cf + β • σ _I ,
where β is the specified relative deviation;
T ₁ T ₂ time constants of aperiodic links, the value of which should be 10 20 times the decay time of the correlation function of the current graph,
and compare the value of I _{with p} with a given setpoint of the motor current and automatically adjust the feed rate as a function of their difference, and the value of I _{m a x is} compared with the cutoff set automatically as a function of the magnitude of the voltage at the motor terminals and reduce the set current setpoint at I _{m a x} exceeding the cutoff setting.  2. A device for automatically controlling the feed rate of coal combines, comprising a current sensor and a setpoint controller for current settings, two comparison elements and a feed mechanism for the combine, characterized in that it is equipped with a voltage sensor, two adders, two aperiodic links, a quadrator, the first proportional link, and the second proportional a link with a dead zone and a square root calculator, and the output of the current sensor is connected to the input of the first aperiodic link, the output of which is connected to the input of the first a matator, the second input of which is connected to the output of the current sensor, and the output of the first adder is connected to the first and second inputs of the quadrator, the output of which is connected to the input of the second aperiodic link, the output of which is connected to the input of the square root calculator, the output of which is connected to the input of the first proportional link, the output of which is connected to the first input of the second adder, the second input of which is connected to the output of the first aperiodic link, and the output of the second adder is connected to the first input of the second proportional a dead band, the second input of which is connected to the output of the voltage sensor, and the output is connected to the input of the first comparison element, the second input of which is connected to the setpoint generator of the current, and the output of the first comparison element is connected to the first input of the second comparison element, to the second input of which the output of the first aperiodic link, the output of the second comparison element is connected to the input of the feed mechanism of the combine.

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