SU1247767A1 - Device for converting physical quantity to time interval - Google Patents

Abstract

The invention relates to electrical measuring equipment and can be used, for example, to measure the rate of flow of a fluid. The purpose of the invention is to improve the accuracy of conversion. The device comprises a variable reference voltage source 1, a sensor 2, and a voltage converter 10 at a time interval. The implementation of the voltage converter 10 in the time interval on the keys 3, 7 and 9, the integrators 4 and 8, the comparator 5 and the control unit 6 eliminates the errors caused by the deviations of the amplitude and frequency of the supply sensor of physical voltage quantities. 1 il. c (o (l o:

Description

one

The invention relates to electrical measuring technology and can be used, for example, to measure the flow velocity of liquids.

The purpose of the invention is to improve the conversion accuracy by eliminating errors caused by the deviations of the amplitude and frequency of the supply sensor of physical voltage values.

The drawing shows the block diagram of the device.

The device contains a variable reference voltage source 1 connected to the power input of sensor 2, the input of which forms the device input, and the output through the first switch 3 is connected to the first input of the first integrator 4, the output of which through the comparator 5 is connected to the output of the device and to the first input control unit 6, the output of source 1 is connected to the second input of block 6 directly, and to the second input of integrator 4 through a second key 7 connected in series, a second integrator 8 and a third key 9, the first output of block 6 is connected to the control switches 3 and 7, the second output is from the integrator control input 8, and the third output is from the control input of key 9, the blocks 3 9 form the voltage converter 10 in a push-pull integration interval, the first and second inputs of which correspond to the inputs of the first and second keys 3 and 7, and the output - the output of the comparator 5.

I

The Converter operates as follows.

Source 1 generates a reference voltage.

on (t) U ,.

At the output of sensor 2, as a result of the action of an input physical quantity P on it, the voltage in the general case is

and,. (t) and S inJt + and so, where and, and Uy are the in-phase and quadrature components, respectively, defined relative to the reference voltage of source 1.

The conversion takes place in two cycles. During the first measure, keys 3 and 7 are open, and key 9 is closed. The voltage from the output of the sensor 2 is fed to the input of the integrator 4, at the output of ko47767

then to the end of the stroke accumulates voltage

Tl7

five,. and (t,. (o

where f is the time constant of the integrator 2 | f of torus 4;

ten

15

 - period of source signal 1.

uj

At the output of the integrator 8 to the moment t we get

t / 2 Ug (.t,) 4- / U ,,

 So - 8

where LO is the integrator time constant 8.

In the second cycle, block 6 locks keys 3 and 7 and unlocks key 9. The voltage Uo (t) goes to the second input of integrator 4, cutting it to zero for the time t, which is generated by the comparator 5. At the end of the interval t, the block 6 locks key 9 and resets the integra- to zero. torus 8, thus preparing it for the next work cycle.

The time interval t is determined

thirty

of condition

IgJouat .- ..,:

L ,. J u id

.2U,

ujl ,,

40

from where

35

Thus, t depends on the deviation of the amplitude and frequency of the reference voltage of source 1 and is related to the input signal by the expression, where k is the constant conversion coefficient.

Claims (1)

Invention Formula A device for converting a physical quantity into a time interval containing a sensor whose input is an input of a device, a power input connected to a reference alternating voltage source, and an output to a first input of a voltage converter in a push-pull integration time interval whose output is a device output This is because, in order to improve accuracy, the voltage-to-time converter is performed on three keys ,. 3 1247767 4. two integrators, a comparator and .ch through a control unit connected in series, the first input being the second integrator and the third key the voltage converter is inter-connected to the second input of the first time interval via the first switch key, the first output of the block is controlled by the first input of the first integral, connected to the control inputs of the first and second keys, the second the rator is connected to the output converter-output - with the control input of the voltage follower in the time interval of the integrator, the third output - with upp to the first input of the control unit, equalizing the input of the third key, and the second input of which is combined with the input-second input of the converter is the voltage of the second key and forms the second one in the time interval connected to the input of the voltage converter to the output of the source reference variable time interval, the output of the second key voltage.