SU1762273A1 - Meter of time constant of first order aperiodic unit - Google Patents

Abstract

The use of the device relates to measurement technology and automation and is intended for use as part of information-measuring systems and automated process control systems. The essence of the invention the device contains an input terminal (1) start terminal (2), a control unit (3) two analog storage units (4 5), two integrators (6,7), four scale blocks (8-11), two subtractors (12 13), a dividing unit (14), an indicator (15) with corresponding links 2 un

Description

The invention relates to the field of measurement technology and automation and is intended for use in the composition of information-measuring systems and automated process control systems.

A device for measuring the extinction coefficient of transients (magnitude, inverse time constant) is known, which contains an input terminal, a resistive-capacitive two-port network, and an indicator (1).

In this case, an oscilloscope is used as a time interval meter, which does not provide high accuracy, speed and automation of measurements.

The closest to the claimed technical solution is the first-order aperiodic link constant time meter (2), which contains an input terminal, a start terminal, an analog storage unit, and a read unit, a unit

division indicator integrator and control unit

A disadvantage of the known device is the limited scope, since it serves to study only exponentially falling signals of the form

(L

WITH

U (t) A. e

A t

The aim of the invention is to expand the field of application by examining both exponentially decaying and exponentially increasing signals.

Fig. 1 shows the block diagram of the measurer of the constant time of the aperiodic link of the first order (hereinafter, the measurer), Fig. 2 shows diagrams explaining the principle of the measurer.

The meter contains the input terminal 1, the launch terminal 2, the block 3, occurrence, two

:Yu

 CE

N s

analog storage blocks 4 and 5, two integrators 6 and 7, four large-scale blocks 8.9, 10.11, two blocks 12 and 13 subtraction. 5klok 14 division, indicator 15

Input terminal 1 is connected to the signal inputs of analog storage units 4 and 5 and integrators 6 and 7. The outputs of analog storage units 4 and 5 are connected through the scale units 8 and 9 to the first and second inputs of the subtraction unit 12, and the outputs of integrators b and 7 through scale units 10 and 11, respectively, are connected to the first and second inputs of subtracting unit 13. The outputs of subtraction blocks 12 and 13 are connected respectively to the first and second inputs of dividing unit 14, the output of which is connected to the signal input of indicator 15. Start terminal 2 is connected to the input of control unit 3, the first, second, third, fourth and fifth outputs of which are connected to the control inputs, respectively, of the analog storage units 4 and 5, the integrators b and 7 and the indicator 15, and the sixth output of the control unit 3 is connected to the reset inputs of the integrators 6 and 7.

The principle of operation of the meter is based on performing computational operations with the output signal of the aperiodic link when applying to its input a discontinuous action in the form of a single step function. In this case, the first-order aperiodic transition is described by the expression:

U (t) A (1 - e

-t /

where U (t) is the dependence of the voltage (output signal) at the output of the first-order aperiodic link when an input is applied to its input in the form of a single step function;

And U («) - steady (asymptotic) value of the output signal of the aperiodic link; t is the time, r is the constant of the first order aperiodic link time.

The integral of expression (1) over the time interval from zero to t is equal to:

/ U (t) dt / A (1) dt

oo

 А t - А г 4- А 7 е А t - r «U (t)

The values of the integral (2) for the moments of time t ti and t2 t2 are soe gp g the system of equations:

/ U (t) dt A ti-g U (ti)

one

U (t) dt A 12 - g U (t2). (3)

From the first equation of the system (3) after 10

blowing

A

U (t) dt + r U (12)

ti

(four)

After substituting (4) into the second equation (3), the transformations determine the desired time constant:

g e

ti / U (t) dt - t2 / U (t) dt HCG TTGRTG7 and (t2)

(five)

Expression (5) underlies the work

25 proposed meter.

The meter works as follows.

At the moment of switching on the meter, the control unit 3 generates a pulse Ue (see

30 of FIG. 2) a reset, which sets integrators 6 and 7 to the zero state.

The input voltage U (t) (cM. Fig. 2), which is the output signal of the first-order aperiodic link

35 when a jump action is applied to its input in the form of a single step function, through the input terminal 1 it enters the inputs of the analog storage units 4 and 5 and the integrators 6 and 7.

40 At time t 0, control unit 3 turns on integrators 6 and 7, applying control voltages 1) C and U4 to them, respectively (Fig. 2). Integrator 6 integrates the input over time.

45 0-c and remembers the value of the integral

/ U (t) dt.

50

55

At time ti, the control unit 3 generates a pulse Lh, which is supplied to the analog storage unit 4, which captures the value of the voltage U (ti).

The integrator 7 integrates the input signal during the time O-t.2, so that at the time t2, the value of its output is generated

t2

/ U (t) dt

At time t2, the control unit 3 issues a control pulse U2 (FIG. 2), which is supplied to the analog storage unit 5, which captures the value of the voltage U (t2).

The output voltages of analog storage units 4 and 5 and integrators 6 and 7 are fed to the inputs of scale units 8, 9, 10, 11, respectively. The transfer coefficients of the scale blocks 8,9,10,11 are respectively proportional to the time intervals Ks t2. Kg ti, Kyu t. .

The values of ti and t2 depend on the measurement range of a constant time. In integrators 6 and 7, they respectively determine the upper limit of integration.

From the outputs of scale blocks 8 and 9, the signals go to the direct and subtracting inputs of subtraction unit 12, the output of which forms the denominator of expression (5), and from the outputs of scaling blocks 10 and 11, respectively, to the subtraction and direct inputs of subtraction unit 13, at the output of which the value of the numerator of expression (5) is formed. Further, the output signals of the subtraction blocks 12 and 13 are received respectively at the inputs of the denominator and numerator of the dividing unit 14, the output of which produces a signal equal to the desired value of the time constant.

At the moment of time 15, the control unit 3 outputs a pulse Us (Fig. 2) to the indicator 15, under the influence of which the indicator 15 stores and displays the value of the value of a constant time received from the output of the division unit 14.

After that, at time point te, control unit 3 generates a reset pulse U6, which, arriving at the reset inputs of integrators 6 and 7, sets them to the initial state. The measurement cycle has ended.

The duration of the pulses and and 1) 2 controlling the process of Fixing in analog storage blocks 4 and 5 must be significantly less than the intervals ti and t2, so that during their operation the input voltage U (t) practically remained unchanged, and, on the other hand, they must ensure that the values of U (ti) are memorized and

U (t :) with sufficient accuracy. A correlation between the times of time r ti must also be maintained.

Block 3 controls the presentation of a series of sequentially connected pulse formers and standby multivibrators.

ten

Claims (1)

Invention Formula The first-order aperiodic level constant time meter containing the control unit, the first analog storage unit, the first the integrator, the first subtraction unit, the dividing unit, the indicator, the input terminal and the start terminal, the input terminal connected to the signal inputs of the first analog storage unit and the first integrator, the control inputs of which are connected respectively to the first and third outputs of the control unit, the fifth output connected to the control input of the indicator, the signal input of which is connected to the output of the dividing unit, the first input of which is connected to the output of the first subtraction unit, is connected to the input of the control unit start-up, t. in order to expand the field of application by examining both exponentially decaying and exponentially increasing signals, a second analog storage unit, a second integrator, four scale blocks and a second subtraction block, with the sixth output of the block yn-ravellee being connected to the reset inputs of the first and second integrators, whose outputs are via the third and fourth, respectively the scale units are connected to the first and second inputs of the second subtraction unit, the output of which is connected to the second input of the division unit, the input terminal is connected to the signal inputs of the second integrator, and the second analog storage unit, the outputs of the first and second analog storage units, respectively, through the first and second scale units are connected to the first and second inputs of the first subtraction unit, control inputs The analog storage unit and the second integrator are connected respectively to the second and fourth outputs of the control unit.