SU1651239A1 - Converter of pickup informative parameter to frequency - Google Patents

Description

FIG. one

The invention relates to electrical measuring equipment, namely, the conversion of an informative parameter of a capacitive sensor, and can be used to convert an informative parameter of various sensors into a frequency.

The purpose of the invention is to expand the functionality by ensuring the independence of the initial frequency and sensitivity adjustment.

Figure 1 shows the functional diagram of the converter of the informative parameter of the sensor into frequency; Fig. 2 shows possible sensor replacement circuits.

The converter consists of generator 1, sensor 2, terminals 3-5 for connecting the sensor, model (informative) 6, and informative (model) 7 sensor elements, amplifier 8, phase shifter 9, rectifiers 10 - 12-, circuit 13 with - Neni, resistors 14 - 17 (R1 jf-Rl7), amplifier 18.

The converter works as follows.

The voltage VQ from the output of the generator 1 is fed to the input of the amplifier 8, the output voltage of which is determined by the exemplary 6 (7) and informative 7 (b) sensor parameters. In the case of a serial replacement circuit for sensor 2 shown in Fig. 2a, the output voltage of amplifier 8 is equal to

U -U,

WITH,

J ° cx

tf

+ -. If the phase shifter 9 is a differentiator, then the output voltage of the phase shifter IL is described to be equalized with the rectifier 11 and fed to the second input of the comparison circuit 13. The first input of the comparison circuit 13 is supplied with the rectified output voltage of the generator 1 (U0). The third input of the comparison circuit supplies the rectified output voltage of the phase shifter 9, which shifts the phase of the output voltage of the generator to

living

i -UOJCORC.

where R C is the differentiation time constant.

The output voltage of the comparison circuit 13 changes the frequency of the generator 1 until the sum of the currents flowing through the resistors 14-16 of the comparison circuit 13 is zero,

T-16 - «° - and the directions of the currents is I / g correspond to the polarity of the output voltages of the rectifiers 10 - 12. Currents 1c4 N) 1 & are defined as follows

-14Ui t

 UnCD RC

R

6

and their sum

TS2SH.Ј VJL Rtfe CX R15 R 4From the expression for the frequency view

  f Ј A.. 1- + J-)

about #V T) r t g TU

21TR With VR

5 С X

R

"4 In the case of the sensor replacement circuit shown in Fig. 26, the expression for the frequency of the output voltage of the generator 1 is

f Ј & Y -A.L, + -1-),

2 iTRC

% L 0 Ri5

44

0

35

and in the case of the sensor replacement circuit shown in Fig. 2c, we obtain

 -RlЈ. 21TRC

/1.p. one

p in CH P

K0K (5 K14

If in the replacement circuits of FIG. 2, swapping the model and informative elements, then in the expressions for the frequencies obtained above, it is also necessary to swap the model and informative parameters of the sensor.

If, on the other hand, an integrator is used as the phase shifter, the output value will be the period of the output voltage of the generator and for the sensor replacement circuits shown in Fig. 2 we have

2frR

 +

K | 5 Cx

one

T - 2frR, 6RC (0L0 RI5

&

t

 0

one

(DG - Kx + -1-)

the presence of a multiplier in front of C, L%, Ry in the form of resistance allows independent adjustment of the sensitivity of the converter, and the resistance E 4 MAY set the initial frequency. This allows obtaining the normalized output signal of the converter when sensors are connected to it with different values of the model and informative elements.

The converter also provides for the conversion of the informative pair -: atra of the sensor even in the case when some of its elements have a sequential or parallel two-element replacement scheme, provided that the loss tangent of the informative and exemplary elements is the same.

The device provides direct or inversely proportional conversion of the relative change in capacitance, inductance, and resistance of the sensors to the frequency of the output voltage of the generator, both in one- and two-element replacement circuits for the informative and exemplary sensor elements.

Claims (1)

Invention formula) The converter of the informative parameter of the sensor into frequency, containing a generator, amplifier, phase shifter, comparison circuit, the generator output is connected to the amplifier input via a sensor, the information element of which forms the amplifier feedback circuit that, in order to expand the functionality, three rectifiers were additionally introduced into it, the input of the first rectifier is connected to the output of the generator, and its output is connected to the input of the comparison circuit, the input of the second rectifier connects The output of the third rectifier is connected to the output of the phase shifter, and its output is connected to the third input of the comparison circuit:: the output of the comparison circuit is connected to the control input of the generator.