SU759985A1 - Logometric converter of parametric sensor output value into electric oscillation period - Google Patents

Description

The invention relates to measuring and control technology and is intended for use in monitoring and measuring non-electric quantities using parametric sensors with 5 separate operating and compensation elements.

A device is known for converting the imbalance of differential potentiometric, ’θ capacitive and inductive converters into a time interval containing a comparison unit, an integrator and a primary differential transducer made in the form of a measuring bridge [11.

The disadvantage of the device is its low accuracy, since the parasitic parameters of the constituent elements of a given sensor have a significant influence on the result of the conversion in it.

Closer to the invention is a ratiometric converter of the output value of the parametric sensor during the period of electrical vibrations, containing a comparison unit (one of the inputs and the output of which are interconnected and connected to the integrator input, 30 DC amplifier, supporting element [2].

The disadvantage of this device is also associated with the relatively low conversion accuracy due to the effect on the final result of the residual difference in the active losses of the sensor’s elements.

The purpose of the invention is to increase the accuracy of conversion of the output value of the parametric sensor during the period of electrical vibrations. ^:

To achieve this goal, a parametric sensor output value in the ratiometric converter during the period of electrical oscillations, containing a comparison unit, one of the inputs and output of which are connected and connected to the integrator input, a DC amplifier, a support element, a zero-element is introduced, wherein outputs zero in £ -orga- ^ν integrator and through the working and compensation sensor elements are connected to the input of the DC amplifier, a negative feedback circuit of which is mounted a support member Rin d zero body peklyuchen to the output of the integrator, and the dc amplifier output so759985 one with the other input of the comparator ,.

Figure 1 shows a functional diagram of the proposed device in relation to a capacitive sensor; figure 2, a-e shows the timing diagrams of the signals at the outputs of the individual device blocks,

The converter includes a comparison unit 1, an integrator 2, a parametric sensor 3 with a working element consisting of a resistor 4 (Cp) and a capacitor 5 (Cp), and a compensation element consisting of a resistor b (K _c ) and a capacitor 7 <C _K ), DC amplifier 8, capacitor support element 9 (C _o ), 'null-organ 10.

The operation of the device is as follows. way.

In the steady state, the voltage (Fig. 2, a) with the amplitude V and the period T acts at the output of the comparison unit 1, and a voltage is generated at the output of the null-organ 10 and ₁₀ (Fig. 2, d) with the amplitude ν ₁₀ and the same period, Let at time 1 ₀ the output voltage; block 1 becomes greater than zero. In this case, the integrator 2 generates a linearly varying voltage (Fig. 2, b), in accordance with the expression, the voltage фиг _β (Fig. 2, e) is determined; divisible as

This voltage is supplied to one of the inputs of the comparison unit 1, voltage is supplied to its other input and,.,

At the moment of equality of these stresses, i.e. at time '

1 _g , the output voltage of block 1 abruptly changes its sign to the opposite. Further, the conversion process continues similarly.

Due to the fact that the converter operates in a cyclic mode, the DC component at the output of the DC amplifier 8 for 5-7 periods is set equal to zero. Therefore, at the moments of changing the sign of the voltage at the output of block 1, the component _(the input voltage of the amplifier) turns out to be zero, and for these moments, given that 1, -1 (, = 1 ^ 1, = 7/4 can be written

4 ^ С where ¢ - is the integration constant of integrator 2,

The voltage at the output of the amplifier 8 DC (figure 2, c) under the action of voltage and _g varies

From this period the generated electrical oscillations is determined by where ι and ¹ -ν (· + · -) A 'law' ^and a \ (with a ton?) Th * ^and 40 ·

Simultaneously, the voltage applied to the input zero-body 10. At time 1, corresponding to the transition and _g / through a zero level of voltage and _d .skachkoobrazno ί 45 changes its sign. Under the action of this signal passing through the working element of the sensor 3, the output of the amplifier 8 DC, voltage appears (figure 2, d)> 50

C _l V) ντ »= τ ^ '-k Υι * dimensionless coefficients. The proposed functional construction of the transducer with a slight modification provides the possibility of using inductive parametric sensors.

Here ^; ν, _ο ~ ^ - ^9, component 55 of the output voltage of the amplifier, from the influence of the parasitic 'parameter to _p , filled for the previous' time interval Ts - 1 _° .

Claims (1)

Claim The ratiometric transducer of the output value of the parametric sensor during the period of electrical oscillations, containing a comparison unit, one of the inputs and the output of which are interconnected and connected to the integrator input, a DC amplifier, a reference element, which differs from To increase accuracy, a null organ is introduced into it, and the outputs of the nullorgan and integrator are connected through the working and compensation elements of the sensor to the input of a DC amplifier, in the negative feedback circuit of which ene support member nulgorgana input connected to the output of the integrator, and the dc amplifier output soTakim way, eventually the output "DC amplifier 8 formi759985 one with the other input of the comparator.