SU1674086A1 - Program control device - Google Patents

Abstract

The invention relates to a technique for automatic software control, in particular temperature control. The purpose of the invention is to improve the accuracy of the device. The device for software control contains a pulse generator 1, a frequency divider 2, an RS trigger 3, element 4, a digital-to-analog converter (D / A converter) 5, a parameter measuring block 6, a comparison element 7, an adjustment element 8, an actuating element 9, the first key 10, decoupling diode 11, capacitor 12, Schmitt trigger 13, second switch 14, first counter 15, multiplier-dividing unit 16, code-controlled power supply 17, second counter 18. With input to the software for controlling the RS flip-flop, element I, Schmitt trigger, differential capacitor decoupling diode, the first and second keys, the first and second counters, and the multiplier-divider unit improve the reproducibility of the control program by eliminating the need to measure the deviation of the current value of the controlled parameter from the value specified by the control program when In this case, the regulation is carried out at the moment when the adjustable parameter reaches the programmed value in proportion to the ratio of the time interval for which the adjustable parameter has reached the set value, to the time interval specified by the program for reaching this value. 4 il.

Description

This invention relates to automatic program control, in particular to temperature control.

The purpose of the invention is to improve the accuracy of the device.

FIG. 1 shows a functional diagram of the device; in fig. 2 is a schedule of operation of the device on the example of temperature control; in fig. 3 is a timing diagram of the operation of the component parts of the device in the first mode; in fig. 4 is a diagram of the operation of the component parts of the device in the second and third modes.

The device contains a pulse generator 1, a divider 2 frequencies, an RS trigger 3, element 4, a digital-to-analog converter (DAC) 5, a parameter measurement block 6, a comparison element 7, a regulating element 8, an actuating element 9. the first key 10, the decoupling diode 11, a differentiating capacitor 12, a Schmitt trigger 13, a second key 14, a first counter 15, a multiplier-divider unit 16, a co-controlled power supply 17 and a second counter 18.

The device works as follows (for example, temperature control).

It is known that in order to change the temperature of an object by degrees L T, it is necessary to bring to it during heating (to cool) some amount of heat Q when cooling, i.e.

Q ton LT, (1)

where m is the mass of the body, the temperature of which varies by DT °;

c is the specific heat capacity of the body material.

This amount of heat is also equal to

Q P- r (2), where P is the power of the energy source:

t is the time of exposure of the source with power P to heat.

Consequently

tsLT Rt (3).

Thus, it is possible to change the body temperature with the mass t, the specific heat capacity C by the same value of AT in two ways: 1) with a small value of power P1 for a comparatively long time effect T 1; 2) with a large value of power P2, but for a shorter period of time r2. Respectively

P1g 1 P2g 2.

Then

, r1

P2-P1

F2

(four)

Based on the specified adjustment accuracy, the curvilinear adjustment program (in Fig. 2, the conditional program is represented) by the piecewise linear approximation method can be represented as a sequence of straight lines. FIG. 2 curve OABCDF replaced by five segments OA, AB, BC. CD and DF. The program change is carried out in steps.

varying voltage with a constant step change D U. In this case, the rate of change of the program is determined by the frequency of the steps D U and in the limits of each of the straight line segments the frequency of the sequence is strictly constant. So. in fig. The second section of the OA program with a smaller steepness corresponds to a lower frequency;

Change the voltage setting on

Di and within the entire control program corresponds to a strictly defined temperature increment. D T.

The time intervals r1 and r2 are measured by the number of pulses n and N. coming from the output of generator 1 for the duration of these intervals. Thus, in the formula (4) the time intervals r 1 i 2 are replaced by proportional

number of pulses

P2 P1

(five)

Since the time interval r 2, specified by the control program, at a given rate of temperature imbalance, is a constant value, in formula (5) the result

tat depends on the ratio mt equal to the ratio of the values of the intervals r 1ig 2, and not

from their absolute values, then. obviously, the numbers n and N can be any arbitrary numbers satisfying this requirement. Consequently, the number of pulses N, determining the time interval g

2, at any rate of change of temperature may be unchanged. The criteria for selecting the number of pulses N is the specified control accuracy and the time constant of the device.

Before starting work, the installation inputs D1 - Dn of the second counter 18 are supplied and recorded at its output a code of number N. The diagrams (Figs. 3, 4) of the operation of the component parts of the device are limited to the case N

 100.

The output of the multiplier-divider unit 16, in accordance with the control program, is the code of the calculated power value, which sets to

The output of the code-controlled power supply source 17 is the power value P1 (Fig. 3 and 4, U 10) corresponding to this code. At the same time, this code is fed to the information input C of the multiplying-dividing block 16. At the output of the RS flip-flop 3, a level O (U 3) is in effect, keeping the second key 14 in the closed state. At the output of the generator 1, a pulse frequency (U 1) is set to provide the necessary rate of temperature change. The first counter 15 is reset (U 11).

At the output of the parameter measurement unit 6, a voltage U 7 is linearly dependent on temperature.

The setting of the current intermediate temperature value at the output of the DAC 5 is performed by a linear stepwise varying voltage U 5 with a constant (L U) step change.

In the initial state, the output voltage of the DAC sets the first voltage level U 5 of the reference to the intermediate value of the temperature T1.

With the start-up of the device at the output of the comparison element 7, the error voltage U 6, including the regulating element 8, acts and the actuating element 9 is supplied with a voltage (U 10) from the output of the co-controlled power source 17, which develops a power P 1 at the actuator.

The temperature of the object, and with it, and the voltage U 7 at the output of the parameter measurement block B, change at a rate proportional to the output power P1 of the code-controlled power source 17. At the same time, the voltage U 6 from the output of the comparison element 7 transfers the output of the Schmitt trigger 13 to the state O (U 8), which, being fed to the control input of the first key 10, opens it. Through the open first key, the pulses U 1 from the generator output arrive at the input of the direct count of the first counter 15.

Depending on the power level P1 in the operation of the device, three cases are possible:

I. The temperature reaches a predetermined intermediate value T1 during the arrival time of n N pulses, i.e. the rate of temperature change is lower than the set one (Fig. 3, U 7).

At time t 1, i.e., when the 1 N-th pulse arrives from the generator output. At the output of divider 2, a pulse U 2 is generated, which is fed to the input PE of the read resolution of the second counter 18 and provides for rewriting the code of the number N from its inputs D1 - Dn to its output (U 12). At the same time, the impulse U 2 transfers the RS Grigg 3 to state 1 (U 3). arriving at the first input element And 4

At time t1, the temperature did not reach the specified value 1 1 (U 7) at

The output of the reference element 7 is a voltage U 6, different from or zero. Therefore, the output of the Schmitt trigger 13 and. accordingly, at the output of the element And 4, the levels of O are maintained. Thanks to this, the voltage U

The 5 temperature setting remains at the same K1 level and does not change its value until the temperature reaches the T1 level.

Under the influence of voltage About U 8 s

the output of the Schmitt trigger 13, the first key 10 remains in the open state, and the pulses U 1 from the output of the generator 1 continue to flow to the direct counting inputs of the first counter 15.

Upon reaching a predetermined temperature level (time t2, fig. 3), the number of pulses entering the first counter 15 is n N + t, where m is the number of pulses received during the interval t1 - t2, i.e.

the moment of appearance at the output of the divider 2 pulse frequency U2. On the diagram (fig. 3) m - 25 and. therefore, n is 125 (U 11).

Thus, after adjusting the power value

Р2 Р1 And Р1 НЫ + т Vi H1 N P1 N

Obviously, the power of P2 provides in

the next cycle of the device operation (from the intermediate temperature value T1 to the value T2) temperature change during the time interval corresponding to N pulses. Thus, the rate of temperature change will correspond to a given program. However, since the T1 temperature level was reached with a delay of t 1 - t 2, corresponding to m pulses, the device will enter the next temperature level T2 with the same delay, although with the programmed speed. The course of temperature change in this case is shown in the diagram (Fig. 3) of U 7 by a dashed line.

In order to eliminate the time bias t1 -12 of the control program, an RZ power must be supplied to the actuating element 9, which is capable of providing a change in temperature from the T1 level.

to the level of T2 for the interval t 2 - t 3 (N - m).

Obviously, the amount of energy received from a kodoopravlivaemya source 17 power with an output power of P2 for the time interval corresponding to N pulses is proportional to N - P2

to ensure the supply of this amount of energy over the interval t2 - t 3 (N - m), it is necessary to increase the output power of the code-controlled power source 17 to the value of the RE.

In this way.

P3 (N - m) P2N.

Then

,

N

 P1

N + t

N m N t

Therefore, in order to eliminate the time offset t 1 - t 2 of the control program, it is necessary instead of the number N recorded at the output of the second counter 18 of the code at the time t 2 to enter the code N - t.

For this purpose, starting from the moment of time t 1, the output voltage U 3, arriving at the control input of the second key 14, opens it. The pulses U 1 through the open first and second keys arrive at the counting subtractive input of the second counter 18.

At time t 2, the temperature reaches the set value T1. The output voltage U 7 of the parameter measurement unit 6 compensates for the action of the voltage U 5 of the reference. The voltage U 6 at the output of the reference element 7 becomes zero. In this case, the regulating element 8 is turned off, at the output of the Schmitt trigger 13 a voltage U 8 1 is set, which closes the first key 10, interrupting the flow of the pulses U 1 to the counting inputs of the first and second counters.

At the output of the second counter 18, the code N - m (U 12) is set, and at the output of the first counter 15 - the code N + m (U 11) of pulses.

At the same time, the voltage U 8 1 from the output of the Schmitt trigger 13 is fed to the input WE of the recording resolution of the multiplier-dividing block 16 and gives permission to enter into it through information input A of the number N + t, through input B - the numbers N - t, through input C - code of the calculated power P1 from the output of the multiplier-divisor unit 16

In the multiplication-division block 16, in accordance with formula (5), arithmetic operations are performed with the numbers entered.

The voltage U 8 1 simultaneously arrives at the second input of the element And 4. At the first input of which the voltage U 3 1 acts from the output of the RS flip-flop Z. As a result, the output of the element And 4 sets the level 1 (U 4) and the voltage U 5 The tasks at the output of the DAC 5 abruptly change by the amount Di. As a result

sets the next intermediate level temperature K2.

At the output of the comparison element 7, the error voltage U 6 is set. which returns the trigger 13 of Schmitt to its original state. At the moment when the output voltage U 8 of the Schmitt trigger 13 decays from level 1 to O using a circuit consisting of a decoupling diode 11 and

of the differentiating capacitor 12, a voltage pulse U 9 is generated, by which the RS flip-flop Z returns to the state O, closing the second key 14, is output to the input of the multiplier-splitter 16

the result of arithmetic operations performed in it. and reset the first counter. 15. The digital code from the output of the multiplier-separating unit is fed to the input of the code-controlled power source 17 and sets the output voltage U 10

РЗ Р1

N + t N-m

which through the regulating element 8. switched on by the voltage U 6 of the error, goes to the actuating element 9.

0The brought power of the relay ensures that the temperature level T2 is reached during the time interval t 2 - t 3. Thus, the time shift that occurred in the previous cycle of the device operation is eliminated.

With the establishment (time t 2) at the output of the Schmitt trigger 13 level 0 (U 8) at the output of the element 4, the level O (U 4) is established, the first key 10 opens and the next cycle of the device operation begins.

At time t 3, the control temperature reaches the value T2, at the output of the comparison element 7, the voltage U 6 is set to zero, the trigger

5 Schmitt 13 overturns and the voltage U 8 1 acts on its output, the first key 10 closes, the flow of pulses U 1 to the first counter 15 stops. Obviously, during the interval t 2 - t 3 to the first counter 15

0 Receives N-m pulses.

At the same moment, 13 at the output of the frequency divider 2, an impulse (U 2) is generated, which, arriving at the input (RE) of recording the second counter 18, gives the command to

5 overwrites the number N from its inputs D1 - Dn to its output and overturns RS flip-flop Z. At the inputs of element 4, a voltage (U 3) 1 is output from the RS flip-flop Z and a voltage (U 8) T from the Schmitt trigger output 13. At the output of the element 4, the voltage is set (U 4) 1. At the output of the DAC 5, the voltage U 5 of the reference rises abruptly to the fault level. which again leads to the appearance of a voltage U 6 at the output of the reference element and the tipping of the Schmitt trigger 13 to the state O.

Subsequently, the entire operation of the device proceeds as described, with the difference that the multiplier dividing unit 16 at t 3 (the output of the first counter 15 introduces the number N - m pulses (U 11), since the work cycle is completed during the interval t 2 - 13 and from the output of the second counter 18 is the number of N pulses (U 12), since the operation cycle ends at the moment of arrival of the pulse U 2 from the output of the frequency divider 2 and the value N. recorded at the output of the second counter 18 remains unchanged.

Thus, after the output of the result of arithmetic operations with numbers N - t, N and RH in accordance with the formula (5). at the output of the code control of the power source 17, power is set (U 10)

  P1N + M

N

that ensures the temperature change of the object with the programmed speed, but without the program’s time offset. In the future, the temperature change takes place in accordance with the programmed

II. The temperature reaches a predetermined intermediate value T1 during the arrival time of n N pulses, i.e., the rate of temperature change is higher than the predetermined temperature (Fig. 4).

In this mode of operation, the number of pulses n (U 11) received at the direct count input of the first counter 15 is less than N, since the temperature level T1 (L) 7) is set to the time t 1, i.e. before the end of the interval g 2 given the program. At time t 1, the output of the Schmitt trigger 13 is set to level 1 (U 8), which closes the first key 10. Diagram U 11 is for case n 75.

Thus, the numbers l N. N and P1 are entered into the multiplication-divisor unit 16. As a result, a voltage (U 10) with a power P2 P1 is set at the output of the codooperative of its power supply 17, providing a temperature change with a programmed speed.

The operation of the component parts of the device proceeds as described for mode I.

III. The temperature reaches a predetermined intermediate value in accordance with

programmed speed, i.e., for the time corresponding to N pulses, n N, (Fig 4, time interval t 2 t 3)

In this mode of operation, the processes proceeding in the device are similar to those described for mode I.

equal n - N. The ratio of rm is 1 and

s

according to formula (5), the power value (U 10) at the output of the code-controlled power source 17 remains at the same level

The process of temperature change in the interval t 3 - t 4 is at the same rate, with

5 what was the previous (interval 12 - 13) x cycle of work

Thus, with the input to the device for software control of the RS-trigger, the element And, the Schmitt trigger, the differential capacitor,

the first and second keys of the first and second counters, and the multiply separating block, increases the accuracy of the control program by eliminating the need to measure the deviation of the current value of the controlled parameter from the value specified in the adjustment npoi frame 0 The process is carried out at the moment when the adjustable parameter reaches the programmed value in proportion to the ratio of the time interval during which the adjustable parameter is Teague specified

5 values, to the time interval specified by the program to achieve this value

The proposed device can be used in all cases where the speed

The 0 change of the controlled parameter depends on the quality of the input energy. For example, when regulating the temperature, rotational speed of an electric motor, regulating the flow of a liquid, gas, etc.

Claims (1)

5 Formula of Invention A device for software control comprising a series-connected pulse generator and a frequency divider connected in series 0 a parameter measurement unit and a comparison element, to the second input of which the output of a digital-to-analog converter is connected, to the output of the comparison element a control input of the regulating element is connected, 5 information input associated with the output of the code-controlled power source, and output with an actuating element, characterized in that, in order to improve the accuracy of the device, it contains serially connected An RS trigger and an And element, a Schmitt trigger connected in series, a differentiating capacitor and a decoupling diode, the first and second keys connected in series, as well as the first and second counters and a multiplier-dividing unit, the first input of the RS flip-flop connected to the output of the frequency divider, the second input of the RS flip-flop with the free electrode of the isolating diode and the control input of the first counter, the direct count input of which is connected to the output of the first key, the control input of which is connected to the output of the Schmitt trigger, with the second input of the element And and the input of the write resolution of the multiplying-dividing block, the input of the read resolution of which It is connected to the anode of the decoupling diode, and the information inputs to the outputs of the first and second counters and the output of the multiplex-separating unit, connected to the control input of the code-matching power source, the information input of the first key, connected to the output of the pulse generator the second key is connected to the output of the RS flip-flop, and the output is connected to the counting input of the second counter, the read enable input of which is connected to the output of the frequency divider, the Schmitt trigger input is connected to the output of the reference element, and you the course of the element And is connected to the input of the digital-to-analog converter. T Fm.g to with s ctc § T2 (N) Y / D lt1, P P P ..- P P ... P il t2 P P V - .. fl P -.- P t N N t3 P and P ... P P ... P f