SU783709A1 - Method of measuring oscillatory-circuit parameters - Google Patents

Description

one

The invention is intended to control the parameters of parallel and serial oscillatory circuits in the manufacture of the latter or in scientific experiments.

The known method of measuring parameters of parallel oscillatory circuits 13 is based on comparing the current flowing through the object with active, capacitive and inductive currents flowing through the sample elements, establishing the quadrature dependence between the vector of difference between the TokoB and the vector voltage of the circuit and subsequent adjustments of the capacitive And inductive current to equilibrium. The method has a low quick action, due to the need to make a series of sequential adjustments to the currents.

A known method for measuring the parameters of nonresonant passive three-element two-terminal networks 23 involves converting a two-terminal network into an active value and successively implementing two quasi-equilibrium states by changing the frequency of the supply voltage and then multiplying and dividing the intermediate values. The method has low speed and complexity, in addition, it is characterized by low measurement accuracy.

The closest technical solution to this invention is a method of invariant transformation of the parameters of a bipolar electrical circuit 3, based on the

to the measuring circuit of the step voltage and the subsequent processing of the output signal of the measuring circuit by performing successive operations of differentiation and integration and subtraction of the output signal.

This method has low accuracy due to the large number of analog operations on the output signal.

The purpose of the present invention is to increase the measurement accuracy.

The goal is achieved by the fact that in the method of measuring the parameters of oscillatory circuits, which implies that 25 s feed the measuring unit with step voltage and study the response of the block to the input signal, the measuring unit is simultaneously {O fed with stepwise, linearly measuring; living with

defined weighting coefficients, where the weighting coefficients are set before measurements of each of the parameters, and the values of the measured parameter are determined from the instantaneous values of the output response of the measuring unit at the selected time point.

The measurement of the parameters of the oscillating circuits is carried out as follows: before the measurement, weighting values are established that correspond to the measurement of this parameter and depend on the type of the measured parameter and the selected measurement time point. Then, a step voltage with its own weighting factor, a linearly varying voltage with its own weighting factor, and a parabolic voltage are simultaneously applied to the input of the measuring unit (made up of the oscillatory circuit under study, the DC amplifier and the reference element RQ). weighting factor; the signal taken from the measuring unit is fed to the instantaneous signal meter: at a selected moment in time and from these values a judgment of the measured parameter is taken.

The drawing shows a device for carrying out the proposed method.

The device contains a step voltage shaper 1, a linearly varying voltage shaper 2j, a parabolic voltage shaper 3, a weight setting unit 4, a measurement unit 5 (composed of a certain way included oscillatory circuit under study, a TFT and a reference element Rg), an instantaneous value meter b and synchronization unit 7. In this case, the outputs of the formers of the acting voltages 1-3 are connected to the corresponding inputs of the weight setting unit 4, the output to torogo through the measuring blo fed to measuring the instantaneous values of 6, and outputs the synchronizing unit are connected with the control input of the acting stresses and meter instantaneous values.

Measurement of parameters of the oscillation circuits consider the example of measuring the parameters of a parallel three-element circuit.

Before the measurement, set the weighting coefficients corresponding to the selected measurable one; parameter.

On the Start signal, the input of the synchronizing unit 7, the control inputs of the forg-4iruyaz of voltages 1-3 receives the enabling signal and

the outputs are fed to the inputs of the weight setting block 4, the weight setting block multiplies each voltage by the corresponding weight and then summing them from the weight output of the weight coefficients, the total voltage through the measuring block 5 is fed to the instantaneous value meter b. Weights

selected so that the signal at the input of the instantaneous value meter at the selected time is determined by only one parameter of the oscillating circuit, and the instantaneous value meter records this voltage according to the signal of the synchronizing unit 7. The voltages coming from the formers 1-3, respectively, are

Ut (t)

Uo

Uo (t)

Us t

t) - Uo,

Ur

where t is the current time

Uo IB - single amplitude. The voltage at the output of the block of coefficients 4 has the form and (t) ao + a, t ajt, (2)

where Ed, a, a - weights. The voltage at the output of the measuring unit 5 has the form

 g and (

(t) dl-t) Ly i;

The values of the weighting coefficients hell, a. ,, 89 are set once at the time of tuning and are determined as follows.

They are given by the value of the time moment and the measurement to, at which the measurement is to be taken, and the weighting coefficients are found by solving the following systems of equations. When measuring R

dU (t .-- to) d-t.

I u

(t) dt o

. ° and (t to)

When measuring C

sGiS-L o1, n d

J and (t) dt 0 and (t to)

(five

 0 When measuring L

J ° U (t) dt 1 U (t t

(6

 0: 5)

Substituting the expression (2) in (M. (&}, we get when measuring R

2; j О + t a, to + i

 0

a., to + 1

We obtain a system of three equations with three unknowns. Solve this system with the help of determinants. The determinants of the systems: Otsadd find iC (o.,;. "- m. - I Sij dimensionless value mm. Substituting expression (7) in (2) and M li (t) (-2 + о) Substituting over1 (8) in (3) time to get) - It IJO UQ Accepted for IB. Similarly, when measuring U (t) (–2t} J. (t) t. Where b is the scale factor of UQ and having Ly measured. .. U (,). (3 -, t -. -, cs I ° II I -. I T.,. - tfj. the evaluation c at the exit of the sampling unit is carried out by a command with b the instantaneous value meter measuring the parameters of a luscable circuit with a series of elements, its switching on the feedback circuit, the op amp, and the supporting element at its output. Mathematical calculations for hell, and, and | get similar about .paaoMk The proposed method can be used to measure the parameters -. A ditch of circuits and chains containing less than three elements The use of the proposed method provides the following advantages compared with the known methods. The measurement accuracy is improved, since the proposed method directly measures the signal value at the output of the measuring unit without performing analog differentiation, integration, and subtraction operations on the signal, the errors of which in the prototype are summed up. In addition, according to the proposed method, there is no need to achieve the equality of the constant time of any nodes. There is a possibility of arbitrary selection of the measurement time point, and, consequently, the devices according to the proposed method can theoretically have any speed. of the invention. A method for measuring the parameters of oscillating circuits, consisting in applying a step voltage to a measuring unit and examining the block's response to an input signal, is given so that, in order to improve the measurement accuracy, the measuring unit is simultaneously served stepwise, linearly varying and parabolic voltages with certain weights sr g, the values of the weight coefficients are set before measurements of each of the parameters, and the value of the measured parameter is gnovennym value m output response to the selected measurement blbka time. Sources of information taken into account in the examination 1. The author's certificate of the USSR 467297, cl. G 01 R 27/02, 1973. 2. The author's certificate of the USSR W 234508, cl. G 01 R 27/02, 1968. 3. The author's certificate of the USSR. 421949, class G 01 R 27/00, 15.02.72 (prototype).

Claims (1)

Claim JQ A method of measuring the parameters of the oscillatory circuits, which consists in applying a step voltage to the measuring unit and studying the response of the unit to the input signal, characterized by the fact that, in order to increase the measurement accuracy, a step, linearly varying and parabolic voltage is simultaneously applied to the measuring unit with certain weights, and the weights are set before the measurements of each of the parameters, and the value of the measured parameter is determined by the instantaneous values the output reaction of the measuring unit <5 ka at the selected time instant.