SU1437799A1 - Digital meter of impedance parameters - Google Patents

Abstract

This invention relates to the field of digital electrical measuring technology. The digital impedance parameter meter contains a sinusoidal voltage generator 1, a power amplifier 2, a sample resistor 3, a measured impedance 4, switches 6.1 - 6.4 type of work, an operational amplifier 5, digital from

Description

4ib O9 ×

F

counting unit 22, integrating analog-time converter 14, exemplary frequency generator 11, quadratic converter 7, phase inverter 8, multiplier 10, switch 9, bias voltage source 12, and n-phase converter 13, elements 15 And 18 , 24; 30, triggers 16, 17, 23, counters

19, 31, reversible counter 21, rewriting unit 20, forming 25, 26 pulses, amplifiers 27, 28, phaeo-splitting unit 29. A digital parameter meter provides high measurement accuracy in a wide frequency range by eliminating the effect on measure the 1H1 additive component of the error. 2 w

one

The invention relates to a digital electrical measuring technique and can be used in the construction of meters of R, L and C parameters,

The purpose of the invention is to improve the measurement accuracy in the frequency range.

. Fig. 1 shows a block diagram of a digital meter, impedance parameters j in Fig. 2, timing diagrams explaining its operation.

The digital meter contains a sinusoidal voltage generator 1, a power amplifier 2, a sample resistor -3, a measured impedance 4, an operational amplifier 5, switches 6 „1-6.4 kind of work, quadratic converter 7 ,, fa. zoinverter 8, switch 9, multiplier 10, generator 11 sample frequency, bias voltage source 12, digital-to-analog converter (D / A converter) 13, integrate 111 First analog-time converter 14, first element 15 and 15 first and second 17 triggers, second element I 18, first counter 19 rewriting unit 20, reversible counter 21; digital from ™ computer unit 22, third trigger 23 third element AND 245 first 25 and second 26 pulse shapers, amplifiers 27 and 28, phase splitting block 29, fourth element AND 30 and BTopofj counter 31.

The output of the sinusoidal voltage generator 1 through the power amplifier 2 is connected to the first input of the integrated analog-time converter 14, the first contact of the switch 6.3, the first contact of the switch 6.2, the first K (:

switch 9, the input of the square converter 7 and the input of the phase inverter 8, the code of which is connected to the second contact of the switch 9, the output of which is connected to the first input of the phase-splitting flea 29 and the input of the amplifier 28, the output of which is connected to the third input of the switch 6 ,one. The input of the operandial amplifier 5 is connected to the second input of the switch 6.3j, the second input of the switch 6v2, the input of the amplifier 27 and the second input of the phase-splitter unit 29, the second output of which is connected to the second input of the switch 6.1, and the first to the fourth input of the switch 6.1, the first input junction: listener 6.1 is connected to the output of amplifier 27. Two switch outputs are connected to two inputs respectively

multiplier 10 ,. out, g; with the second input of the hybrid analogue-time converter 14 through source 12 and p; The output of the quadrant ripeo6pazovatel 7 podkl occhep to the first input of transpeater 6.4 and the input. PPA 13 output, which is connected to the second. To .. vkg-r - home switch 6.4, the output of peredyyyuchel 6.4 connected to T1: Another input of an integrated analog-variable converter 14 "Vko / t pen; 1 switch 6.2 is connected to the first terminal of the reference resistor 3 of the second connector of which is connected 11 not to the 1st connection of the operational amplifier 5 and with the first terminal of the measured impedance 4, the second terminal of which is connected to the FIRTH INLET switch 6, 3 "Pervg converter 14 is connected to the input of the device

The second trigger 17 and the reset inputs of the counter n 31 and digital from the counting unit 22. The second output of the converter 14 is connected to the second input of the third element H 24 and the first input of the fourth element And 30, the second input of which is connected to the output of the generator 11 of the reference frequency and the second input the first element AND 15, the first input of which is connected to the third output of the converter 14, the recording input of the DAC 13 and the input of the first trigger 16, the output of which is connected to the control input of the switch 9. The output of the fourth element I 30 is connected to the input The electronic sensor 31, whose information output is connected to the information input of the DAC 13. The output of the second trigger 17 is connected to the second input of the second element AND 18 and the first input of the third element And 24, the output of which is connected to the input of the rewriter unit 20 and the input of the second driver through the LRV 26 pulses, the output of which is connected to the reset inputs of the counter 19 and the third trigger 23, the output of which is connected to the control input of the reversible counter 21, the information output of the counter 21 is connected to the information input digital The second counting unit 22. The output of the element 15 is connected to the counting input of the counter 19 and the first input of the elements 18 whose output is connected to the counting input of the reversible counter 21. The information outputs of the counter 19 are connected to the information inputs of the rewriting unit 20, the outputs of which are connected to the inputs recording the reverse counter 21, the output of the counter 21 is connected to the input of the trigger setup 23. The non-inverting input of the operational amplifier 5 is connected to the common bus. The control inputs of switches 6.1, 6.2, 6.3 and 6.4 of the type of operation are interconnected. The information output of the counter 19 is connected to the information output of the rewriting unit 20, the information output of which is connected to the information input of the reversible counter 21.

Digital meter paGoTaef in the following way.

When measuring the common-mode component of the resistance of the serial RjijLjj-cxeMb switch

the works are in the following position: 6.2 - at the bottom, 6.1 - D at the top; 6.3 - in BepxHehf, 6.4 - in the bottom. Counters 19, 21, and 31 and triggers 16, 17, and 23 are set to zero. Switch 9 is in the upper position. Elements 24 and 30 are closed by the signal from the third and second outputs of the converter 14, element 18 is closed by a signal, from the output of the trigger 17.

Voltage at output of power 2

U (t) U sinut, (.1)

where and are amplitudes

o) - circular frequency; t - time

From this voltage, which is fed to the first input of the converter 14, a time interval is formed (see Fig. 2e), a multiple of the period T of the voltage U (t), i.e. -t, pt (n 1, 2, 3, ...).

The switch 9 and the amplifier 28 with the gain factor K and the phase shift if receive the second input of the multiplier 10

U ,, (t) K and) t + if). (2)

There is a voltage at the output of the op amp.

U (t) U (t). |

 f and sin (wt + t /).

To

(3)

where (is the phase shift between voltage and () and UjCt) caused by the reactivity of Z.

The voltage Uj- (t) is amplified by usi; A switch 27 with a gain factor K and a phase shift i /, as in amplifier 28, due to the identity of their characteristics. Therefore, the first input of the multiplier 10 receives a voltage:

U ,, (t)

H

Z sin (cJt +% + 4). (four)

By multiplying U, (t) and U, (t), the output of multiplier 10 is

and

AR

U ,, (t) Uftp + K, U ,, (t) .U, (t) + Kp-K Ui-Zx (; cosvrcos 2 (wt-nf,) + t /,

2R,

where RQ is an exemplary resistance n input of the operational amplifier j CDR, K is the drift zero and the coefficient

transmitting the multiplier 10. The voltage U ,, (t) (Fig. 2a, time O - tj, is integrated in the converter 14 over time tft (Fig. 26, time tf-t). At the time, AND 30 is opened and by the time tj in the counter 31 will fix the code number

Nf c T f.-n-T.

(6)

/ - from 1 3

At time t i, at the third output of the converter 14, the leading edge of a pulse of duration t t (FIG. 2d) is formed, which at time t – j rewrites the number N in the DAC 13, the conversion function of which is described by the expression:

UBWIC - Klo and Bx Njo

(7)

and

bh

de Ktsdp transfer ratio DAC, 25 N - code 4Hanaj incoming

to the control bus, i.e. N x Ni; - voltage applied

to the input from the output of the quadratic 30 converters 7 with the conversion function

and

boo

  you lp

Urn

where K | - transfer coefficient of quadratic converter 7.

At time t, voltage

byk -K ,,,

and

f. U

comes from the output of the transponder 6.4 to the third input of the converter 14, which leads to a reverse integration in the converter 14 to the zero level determined by the trigger threshold of the converter 14 (moments t j-tj j of fig. 26),

In the process of push-pull voltage conversion U ,, (t), together with the voltage U d, of the source 12 in the converter 14 in the time inter

K-Kn U m-Z.

2R,

 costf-cos 2 (wt + q) -i- .f dt

1 5 Г i К ,,, „- К ,, - f.n-T-dt и ,.

one

(9)

At the third output of the converter 14, a time interval is obtained.

... .. Uc-r- (UAp + UcM) Ti

L tj-tj -

K2 Kn

.V f t

  "P 2 - about 1

f -o-Kn n K gp-f 0

Z COS c /,

(ten)

because

-I

 "

K Kn U Zx 2Rn

-C о s -e (u t + (f) + tf (

at

Ha time., Element 15 is opened and the number of pulses is fed to the input of counter 19

to -f Ct-f} - forUc-c- (U p + UcM) Ti iM -

 and, lp

, -K ,, 14i f, -T,

K2. K

 E c.lp qp

Z, cosi.

(eleven)

At the moment t J, the pulse from the output of the converter 14 (Fig. 2c) overturns the trigger 17 into the unit state (Fig. 2g), which then remains in this position, and opens the element I 18 at the second input. In addition, the unit signal the time t.-, from the first output of the converter 14 resets to the counter 31. At the time of a positive pulse front (tj-t ;;), the trigger 16 tilts into one state and switches the switch 9 to the lower position. The signal from the output of phase inverter 8

Uj and sin (; ot-H80)

enters the input of the amplifier 28 and from its output through the switch 6.1 to the second input of the inverter

Uii (t) KU sin (LJt +. (12)

The voltages (11) to (12) of the alternator-joTCH in alternator; the tunic 10, as a result, is obtained (Fig. 2a, moments t.

H

and

Un (t), U2, (t) J, (t) K, v K2- Ur Zx

AP

2R.

 --cos L / +

+ (cjt-i-Cf) - (- M,

(13)

In the converter 14 in the process of push-pull conversion U ni (t) +

+ and

-c „at tg-t4 t -t7 n

tq

 .V

, +

 VI-Z, 2R.

-cosef +

osl2 (wt + (fj,) + tie

1 (I112

- K f - t t- - n

f j -6 -I Jc.

I j ..

t g

Given that

(u) t + q)

we get

four

(U4p + U cm) T,

central processing unit 2

Ui,

f. T

 оi 1

K.Kp

 o I, An kp-e

Zx COSLf.

(14)

At time t, the first driver 25 is triggered, which, at time 1, gives a pulse to rewriting unit 20, rewriting the code of the number N from counter 19 to the reversible counter 21. At time t, the driver 26 triggers, which for a time (tg-t-,) the pulse and resets the counter 19 and the trigger 23 to zero. At the moment tg the pulse from the first output of the converter 14 writes the code of the number N, the counter 31 in the DAC 13.

During the time t from the output element I 15 to the input of the counter 19 and through e ;; element I 18 to the subtracting input of the counter 21 receives the number of pulses

-tq) f,

(IDR + USM) T,

TO

NLP

to f T KP T -o - h

Cr-k

, Ln i

Z. COS (f.

(15)

At the moment in the counter 21 received

2Kp K

-

to

SHAP ko about

Z cos ip

R

X

(sixteen)

where R. / is the resistance value in a series circuit. From the expression (16) it can be seen that the measurement result does not depend on the value of Uc ,,,,, and P. T, fc

elements of the analog-to-gf transformation circuit. Their stability is required to be ensured at the time of measurement, which is technically easy to implement. By the time t d in the counter 21, the code of the number is fixed, defined by the expression (16), which at 2K, rK2

 fo

 Yu (where,}, 2,3, ...)

proportional to the resistance value R. In the counter 19, the code of the number N is memorized. Result N -N, 2 НN led In the digital reading unit

ke 22.

To reduce the dynamic error due to the multi-time conversion in the third cycle, the code of the number N fJ is obtained. By the time of its arrival in the reversible counter 21 of counter 19, the code of the number N was rewritten,; N, j. Therefore, with the arrival of the number N, of pulses in N, j, the counter 21 goes to the zero state, tilting, gives the trigger 23 to the one state, which leads to the conversion of the reversible counter 21 to the summation mode. Subsequent

N, i-Nn

K g, -K

Ktsp TsLP-RO

R

the pulses are fixed in the counter 21. Similarly, it occurs in subsequent cycles, i.e. in each cycle

The conversion in the continuous number reading unit 22 results in the measurement.

When measuring the reactive component of the resistance of the serial RyLj, -uenn switches of the type

the works are in the following position: 6.2 - at the bottom, - 6.1 - at 1 level 6.3 - at the top} 6.4 - at the top. Counters 19, 21, 31, triggers 16,

17, 23 reset to zero. Switch 9 is in the upper position. Elements And 24 and 30 are closed by the signal from the third output of the Converter 14, the element And 18 is closed

the signal from the output of the trigger 17, the voltage described by the formula (l), from the output of the power amplifier 2 through the switch 9 is fed to the first input of the phase-splitting unit 29,

the second input of which receives the voltage described by the formula (3) from the output of the operational amplifier 5. At the output of the phase-splitting unit 29, we obtain two voltages:

K U.sinCwt-i-tf);

If TI 7 „

(17)

O sin (oot + V P + 90),

R.

shifted out of phase by an angle (90 i-tf), Depending on the frequency, one phase shift is made (f and the signal is amplified equally with, and (t) and U, j (t) with a gain factor K. Amplification is necessary in order to match the voltage at the input of the multiplier and the signals of the object under study.

The voltages U ,, (t) and U (t) are multiplied in the multiplier 10, as a result of which a voltage is obtained at its output

UnH (.P

.b | iJli.Z, rsin, - (ut + (f) +9 (f +,

which stacks with voltage

and

with

source 12 bias voltage

nor in the future, as in the conversion of Uni (t:) + Uc / HB exaggeration (9) when measuring the in-phase component

1 Si h-P + tK -Ct,

T 1 iu p- M + -2R; - "

((o) tH-t / |,) + 90 ° + g jjdt + 13

+ 7 K. Uc (18)

converted to pulses

f,

  f, (tj - t)

CUci :-( UAp + UcM) Tj

Ktsp- (Ui, / 2) f about Kp to -T 1

KKO 0

Z sint /,

(nineteen)

as H

Y (-1) cosf2 (iot + tf,) + 90 ° + t О

r1

with -t - - 11 n -T.

This process differs only in that, as the discharge voltage, the output voltage of the Quadratic converter 7 is used, which through a switch 6.4 goes to the third input of the converter 14.

From the moment t / j, the switch 9 is in the lower position, the inputs 17 to the input of the phase-splitting unit 29)

,

B - a1437799 O

The voltage defined by expression (12) and (t) is 180 degrees out of phase with respect to voltage by expression (1). At the same time, the output of phase-splitting unit 29 has two voltages:

i and; , (t) C.and „sin (u),

10 Uj (t) sin (u), + (f + 270 °),

shifted in phase by an angle of 270 + t-f.

The output of the multiplier 10 appears voltage

P C g 1-11 + 2 ll i5 i JL y

UfTjO Ivty-Urtp + otp-

„L about y -sinif-cos 2 (wt + (|) +270 + (f, (20)

20 which is summed with U (-, and push-pull conversion is analogous to the expression (18); i is the number of pulses

N "fo (t

  10 -, f o K p K kp

insofar as

U

h foruj r) - (+ UCM) T, J

 )

Z S in o-,

(21)

 (-1) cosi2 (wt i / J + 270 + Q dt O

 H at.

In counter 21, the difference in numbers is fixed.

i, -N, K, - K. G, K R-0

Z sin with, (22)

because

40

211

 - L ,,, T, p T,

this expression (22) is simplified

N1, -N,

2fo Kp-K2. p-t

. Cr-H. pt,

KKH-RC

KUH-RO

T - (23)

and does not depend on the value of the parameters

50 sec. 9 Ap cm of the analog 1DIFFORM conversion circuit. Their stability is required only for the duration of the measurement. The independence of the measurement result (23) from the frequency and a ffl of the oscillations of the voltage; e and U (t) and 1 sinuj t allows to make highly accurate measurements of L t in the frequency range. In expression (23)

55

4fo-Kn-K p1G K ,,; R,

 ten,

where, 1,2,3, ....

When measuring parameters of a parallel R Cj circuit, the following measurements are made. The circuit should measure the in-phase component of the conducted Ti- :.

When measuring the in-phase conductivity component, the switches of the type of operation are in the following position: 6.2 - in the upper 6.1 - in the upper J 6.3 - in the lower 6.A - in the lower.

When measuring the capacitance of parallel, (- the circuit switches of the type of work are in the following position: 6.2 - in the upper, 6.1 - in the lower, 6.3 - in the lower; 6.4 - in the upper

The proposed RLC-parameter meter provides high accuracy of measurements in a wide frequency range by eliminating the effect on the measurement result of the additive component of the error.

Formula of invention

Digital impedance parameter meter containing a sinusoidal voltage generator, power amplifier, reference resistor, measured impedance, type of work switch, operational amplifier, digital readout unit, integrated;; analog time converter, reference frequency generator in which the output of a sinusoidal voltage generator is connected to the input of a power amplifier, the output of which is connected to fixed contacts of a switch of the type of work of the third and second The direction switch of the third direction is connected to the first terminal of the measured impedance, the second terminal of which is connected to the inverting input of the first amplifier and the first terminal of the reference resistor, the second terminal of which is connected to the output of the second direction type of switch, the non-inverted input of the opio1pyuo amplifier is connected to the common bus,

The SL output is connected to the second inputs. ochatel kind of work third

and the second direction, which is different from the fact that, in order to improve measurement accuracy in the frequency range, a quadratic converter, phase inverter, multiplier, switch, bias voltage source, digital-to-analog converter, And, three flip-flops, two counters, a reversible counter, a rewriter unit, two pulse drivers, two amplifiers and a phase splitter unit, the output of a power amplifier

connected to the first input of the integrating voltage converter in the time interval, the first input of the switch, the input of the quadratic converter and the input of the phase inverter, the output of which is connected to the second input of the switch, the control of which is connected to the output of the first trigger, the output of the switch is connected to the input of the second booster

and the first phase-splitting input

block whose second input is connected

with an operational amplifier output and

the input of the first amplifier, the output of the first amplifier is connected to the first input of a switch of the type of operation of the first direction, the second input of which is connected to the second output of the phase-splitting circuit, the third input is from the output of the second amplifier, the fourth by the first output of the phase-splitting circuit, and two outputs of the switch type: the work of the first direction is connected to two inputs of the multiplier, the code of which is connected to the first output

voltage source, bias, the second output of the source, for example. The offset bias is connected to the second input of the integrated analog-time converter, the third input of which is connected

with the output of the switch of the type of work of the fourth direction, the first input of the switch, the type of work of the fourth direction is connected to the output of the quadratic converter and the input

the digital-to-analog converter, and the second input - with the output of the digital-analog converter, whose information input is connected to the information output of the second counter,

and the number record control input is connected to the counting input of the first trigger, the first input of the first element And, and the third output of the integrating analog-time converter, the second output of which is connected to the second input of the third element And and the first input of the fourth element And, the second input of which is connected with the output of the generator of the reference frequency and the second input of the first element I, and the output with the counting input of the second counter, the reset input of which is connected to the control input of the digital reading device, the first output m integral of the first analog-time converter and the input of the second trigger, the output of the second trigger is connected to the second input of the second element AND and the first input of the third element AND whose output is connected to the input of the first driver, the output of the first driver is connected to the control input of the rewriting circuit and the input of the second shaper output

but

ADDL

which is connected to the reset inputs of the first counter and the third trigger; the installation input of the third trigger is connected to the output of the reversible counter; the block, the counting input is connected to the output of the second element I, the information input of the number record is connected to the information output of the rewriting unit, the information input 1 of which is connected to the information output of the first counter control inputs of the switch of the type of operation of all pex directions of the connection; melodiously

fuirui

Claims (1)

Claim A digital complex resistance parameter meter comprising a sinusoidal voltage generator, a power amplifier, a reference resistor, a measured complex resistance, a type of operation switch, an operational amplifier, a digital readout unit integrating an analog-time converter, a reference frequency generator, in which the output of the sinusoidal voltage generator is connected to the input of the power amplifier, the output of which is connected to the fixed contacts of the switch of the kind of work of the third and second voltage of equations, the output of the third-order type of operation switch is connected to the first terminal of the measured complex resistance, the second terminal of which is connected to the inverting input of the operational amplifier and the first terminal of the reference resistor, the second terminal of which is connected to the output of the second-order type of operation switch, the non-inverting input of the operational amplifier to the common bus, and the output is connected to the second inputs of the switch of the kind of work of the third and second direction, distinguishing it with the fact that, in order to increase To measure the accuracy of the measurement in the frequency range, a quadratic converter, a phase inverter, a multiplier, a switch, a bias voltage source, a digital-to-analog converter, four I elements, three triggers, two counters, a reversible counter, a rewriting unit, two pulse shapers, are additionally introduced into it, two amplifiers and a phase splitting unit, the output of the power amplifier 15 is connected to the first input of the integrating voltage converter in the time interval, the first input of the switch *, the input of the quadratic pre the browser and the input of the phase inverter20, the output of which is connected to the second input of the switch, the control input of which is connected to the output of the first trigger, the output of the switch is connected to the input of the second amplifier 25 and the first input of the phase splitting unit, the second input of which is connected to the output of the operational amplifier and the input of the first amplifier, output per. Vågå amplifier connected to the first WMOs · ³⁰ January kind home switch of the first direction, a second input coupled to the second output fazorasscheplyayuschey circuit, the third input - with the output of the second amplifier, a fourth input * fazorasscheplyayuschey the first output circuit, and two kinds of outputs of the switch. works of the first direction are connected to two inputs of the multiplier, the output of which is connected to the first output 4Q of the voltage source, bias, the second output of the bias voltage source is connected to the second input of the integrating analog-time converter ¹ , the third input of which is connected 45 to the output of the fourth kind of work switch direction, the first input of the switch, the type of work of the fourth direction is connected to the output of the quadratic converter and the input of the digital-to-analog converter, and the second input to the output digital-to-analog converter, the information input of which is connected to the information output of the second counter, and the input for recording the number is connected to the counting input of the first trigger, the first input of the first AND element, and the third output of the integrating analog-time converter 1437799, the second output of which is connected to the second input of the third element And the first input of the fourth element And, the second input of which is _f- divine with the output of the model frequency generator and the second input of the first element And, and the output is with a counting input the house of the second counter, the reset input of which is connected to the control input of the digital readout device, the first output of the integrating analog-time converter and the input of the second trigger, the output of the second trigger is connected to the second input _{of the} second And element and the first input of the third And element, the output of which is connected to the input of the first shaper, the output of the first shaper is connected to the control input of the rewrite circuit j and the input of the second shaper, the output 1 4 of which is connected to the reset inputs of the first counter and the third trigger, the installation input of the third trigger is connected to the output of the reverse counter, and the output to the control input of the operating mode of the reverse counter, the information output of which is connected to the input of the digital reading / 0 block, the counting input is connected to by the output of the second element AND, the information input of the number record is connected to the information output of the rewriting unit, the information 'inputs of which 5 are connected to the information outputs of the first counter, the count input is about the counter is connected. with the first input of the second element And and the output of the first element and, and the control inputs IQ of the switch of the kind of work of all four directions are connected between the subwoofer. and δ g d e Fi-z. 2