SU1241166A1 - Device for identifying non-linear elements by parameters of volt-ampere characteristics - Google Patents

Abstract

This invention relates to instrumentation technology. The purpose of the invention is to increase the reliability of the registration of non-linearity of the current-voltage characteristics. The device contains a linearly varying voltage generator 1, a matching unit 3, a registration unit 5 and terminals for connecting the test element 2. The introduction of an analog differentiator unit 4 allows the device to register the output from the current-voltage characteristic of the voltage, i.e. due to the transition from the comparison of nonlinear elements according to the norms of meters of the actual current-voltage characteristic to the comparison according to the standards of parameters, its derivative. 1 il. th 4 od od

Description

The invention relates to the control and measurement technology and can be used to control and reequip elements with nonlinear current-voltage characteristics.

The purpose of the invention is to increase the accuracy of registering non-linearities of current-voltage characteristics by registering derivatives of current-voltage characteristics with respect to voltage, i.e. by passing from a comparison of nonlinear elements according to the norms of the parameters of the current-voltage characteristic itself to a comparison according to the norms of the parameters of its derivative.

The drawing shows a block diagram of the proposed device.

The device contains a series-connected generator 1 li-. linearly varying voltage, terminals for connecting test element 2, matching unit 3, unit 4 of pledged dufferi- iatr and unit 5 of registration, the second input of which is connected to the output of generator 1.

The device works as follows.

 From the output of generator 1, the linearly varying voltage U (t)

 EO + E - () enters on

Test Subject 2. The variation of the values of E and E makes it possible to select the required identification part of the current-voltage characteristics. The response signal of the test element 2 to the input voltage U (t) is supplied to the matching unit 3, which serves to harmonize the dynamic ranges of the test element and the first analogue differentiator of unit 4. The matching unit is also designed to linearly convert the current through the test element 2 to the voltage . When testing an element having a current-voltage characteristic I F (and), the voltage Ue. (T) at the output of the matching unit Ue (t) KF (EP + Е), where K is the coefficient

transfer matching unit 3.

The first of the analog differentiators of block 4 provides a voltage at its output that is proportional to the derivative of the output voltage of the matching block 3.

-RC

dUc (t)

dt

-HCKSM.

V dU (t) .. „,, dF Ed.

 dG -.- du F

dF

where Y is the derivative of the current-voltage characteristic of the test element with respect to voltage.

When differentiators 4 are used in a block of one analog differentiator (p I), its output voltage is fed to the input of registration block 5, the second input of which receives a signal from the output of the linearly generated generator - voltage 1. The registration block 5 in this case serves for comparison, the current values are dF. , .:, with given norms. As

The registration unit can use an oscilloscope, on whose screen a mask is applied, the slots in which correspond to the specified standards on the

dF, ti (t) depending on the

 dU. . , yarn, pr) and1ozhenNrgo to the test item. ,

The volt-ampere characteristic of the test element is described by the expression

F (u)

al (U - UV).

The small-scale nonlinearity of the current-voltage characteristics in the JE interval can be described by the law:

| W. ,

a, (C - IO 2-at (U - Uc). VMtf-t-:

where K 0; one; 2, etc. Then niJH constant Relative error (the value of which is determined by the characteristics of the registration unit) absolute error of comparison with 1 standard of values of the current-voltage characteristic (d F) and its first derivative (l F) is determined by the expressions:

A F (U - Uo

 ("Di--

4F (and - U)

u4

3

Comparison of these expressions makes it possible to achieve a higher degree of fidelity errors with the norms of the recorded

:

DR

, 7

., d F ao

An even greater increase in the reliability of identification is achieved when two or more analog differentiators connected in series are connected in the device, the input of the first differentiator is connected to the output of the matching block and the output of the last differentiator is connected to the registration unit.

The win due to a decrease in the absolute error when using two analog differentiators is described by the expressions:

where is uf

If

- absolute error of comparison with the norms of the second derivative of the wave & t-ampere characteristic In the signal at the output of the second differentiator, there is no constant and linear component of the expression describing the current-voltage characteristic. Thus, the voltage value at the output of the second differential of the oscillator completely describes the non-linearity of the current-voltage characteristic of the test element and can be used for its absolute evaluation,

Similarly, an increase in the reliability of identification of nonlinear elements can be illustrated when a large number of series-connected differentiators are included in the device, the optimal number of which is; determined by the specific type

to

15

2o

five

0

50

current-voltage characteristics of the tested elements and requirements for the accuracy of identification.

The specific values of the parameters of the device blocks {voltage E and t. The transfer coefficient of the matching block K, the duration of the impulses of the linearly increasing voltage T and. The standalone differentiations of the RC differentials are chosen taking into account the type of the current-voltage characteristic of the test element and the matching of the dynamic ranges of the device blocks,

An oscilloscope sweep generator used as a recording unit can be used as a linearly measuring voltage generator, a current-voltage converter made on an operational amplifier as a matching unit, and differentiators on operating amplifiers x

F o rmu l invention

A device for identifying nonlinear cells by parameters of current-voltage characteristics, comprising a voltage generator, the output of which is connected to one terminal for connecting the test element and the first terminal of the input of the registration unit, and the other terminal is long. connection of the test element is connected to the input of the matching unit, characterized in that, in order to increase the reliability of identification of nonlinear elements, a block n (1, 2, 3,. ,,.) of serially connected analog differentiators is inserted in it, the input of which is connected to you by the stroke of the matching unit, and the output is connected to the second input terminal of the registration unit, while the voltage generator is made in. the form of a generator of linearly varying voltage.

Compiled by V. Maslovskiy. Editor A. Lezhnin. Tehred L. Oleynik Proofreaders, Sharoshi

3484/40

Circulation 728 Subscription

VNIISH State Committee of the USSR

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab ,, d, 4/5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

Claim A device for identifying nonlinear elements according to the parameters of the current-voltage characteristics, comprising a voltage generator, the output of which is connected to one terminal for connecting the test element and to the first input terminal of the registration unit, and the other terminal for. connecting the test element is connected to the input of the matching unit, characterized in that, in order to increase the reliability of identification of non-linear elements, a block η (1, 2, 3, ..,.) of series-connected analog differentiators is inserted into it, the input of which is connected to the output of the matching unit, and the output is connected to the second input terminal of the registration unit, while the voltage generator is made in. a form of a ramp generator.