MD489Z

MD489Z - Method for measuring the impedance components

Info

Publication number: MD489Z
Application number: MDS20110106A
Authority: MD
Inventors: Виталие НАСТАС
Original assignee: Технический университет Молдовы
Priority date: 2011-06-09
Filing date: 2011-06-09
Publication date: 2012-09-30
Also published as: MD489Y

Abstract

The invention relates to electric and electronic measurements and can be used for high-precision measurement of impedance components.The method consists in the formation of a series measuring circuit from the measured object, output terminals of an impedance converter with separate control of active and reactive components of the reproduced impedance and a signal generator, formation of a non-equilibrium signal from the total voltage drop on the measured object and the output circuit of the converter, control of phase shift between the non-equilibrium signal and reference signals, equilibration of the measuring circuit by regulating the components of the impedance reproduced by the converter and determination of components of the measured impedance from their known dependence on the components of the impedance reproduced by the converter in the equilibrium state. Regulation of components of the impedance reproduced by the converter is performed concomitantly, up to the attainment of a phase shift of 180° or 0° between the non-equilibrium and reference signals, and as reference signals for regulation of active and reactive components are used, respectively, the voltage drops on the reactive and active components of the impedance reproduced by the converter.

Description

Invenţia se referă la domeniul măsurărilor electrice şi electronice şi poate fi utilizată pentru măsurarea cu precizie înaltă a componentelor impedanţei. The invention relates to the field of electrical and electronic measurements and can be used for high-precision measurement of impedance components.

Cea mai apropiată soluţie este metoda de măsurare a componentelor impedanţei, care constă în formarea unui circuit de măsurare din obiectul măsurat şi bornele de ieşire ale unui convertor de impedanţă, controlul semnalului de dezechilibru, obţinut în urma interacţiunii circuitului rezonant cu semnalul de măsurare, echilibrarea circuitului de măsurare prin reglarea componentelor impedanţei reproduse de convertor şi determinarea componentelor impedanţei măsurate din dependenţa lor de componentele impedanţei reproduse de convertor. Reglarea componentelor activă şi reactivă ale impedanţei reproduse de convertor se efectuează în două etape consecutive: la prima etapă se reglează componenta activă, iar la etapa a doua - componenta reactivă [1]. The closest solution is the method of measuring impedance components, which consists in forming a measuring circuit from the measured object and the output terminals of an impedance converter, controlling the unbalance signal, obtained as a result of the interaction of the resonant circuit with the measurement signal, balancing the measuring circuit by adjusting the impedance components reproduced by the converter and determining the measured impedance components from their dependence on the impedance components reproduced by the converter. The adjustment of the active and reactive components of the impedance reproduced by the converter is carried out in two consecutive stages: at the first stage, the active component is adjusted, and at the second stage - the reactive component [1].

Dezavantajul acestei metode constă în timpul considerabil de măsurare din cauza celor două etape consecutive de reglare, ceea ce complică aplicarea practică. The disadvantage of this method lies in the considerable measurement time due to the two consecutive adjustment steps, which complicates practical application.

Problema pe care o rezolvă invenţia este majorarea vitezei de măsurare şi, ca urmare, simplificarea aplicării practice. The problem that the invention solves is increasing the measurement speed and, as a result, simplifying the practical application.

Metoda, conform invenţiei, înlătură dezavantajele menţionate mai sus prin aceea că constă în formarea unui circuit de măsurare în serie din obiectul măsurat, bornele de ieşire ale unui convertor de impedanţă cu reglare independentă a componentelor activă şi reactivă ale impedanţei reproduse şi un generator de semnal, formarea unui semnal de dezechilibru din căderea sumară de tensiune pe obiectul măsurat şi circuitul de ieşire al convertorului, controlul defazajului dintre semnalul de dezechilibru şi semnalele de referinţă, echilibrarea circuitului de măsurare prin reglarea componentelor impedanţei reproduse de convertor şi determinarea componentelor impedanţei măsurate din dependenţa cunoscută a acestora de componentele impedanţei reproduse de convertor în stare de echilibru. Reglarea componentelor impedanţei reproduse de convertor se efectuează concomitent, până la atingerea defazajului de 180° sau 0° dintre semnalul de dezechilibru şi cel de referinţă, iar în calitate de semnale de referinţă pentru reglarea componentelor activă şi reactivă se utilizează respectiv căderile de tensiune pe componentele reactivă şi activă ale impedanţei reproduse de convertor. The method, according to the invention, eliminates the above-mentioned disadvantages by consisting in forming a series measurement circuit from the measured object, the output terminals of an impedance converter with independent adjustment of the active and reactive components of the reproduced impedance and a signal generator, forming an unbalance signal from the sum of the voltage drops on the measured object and the output circuit of the converter, controlling the phase shift between the unbalance signal and the reference signals, balancing the measurement circuit by adjusting the impedance components reproduced by the converter and determining the measured impedance components from their known dependence on the impedance components reproduced by the converter in equilibrium. The adjustment of the impedance components reproduced by the converter is performed simultaneously, until the phase shift of 180° or 0° between the unbalance signal and the reference signal is reached, and the voltage drops on the reactive and active components of the impedance reproduced by the converter are used as reference signals for adjusting the active and reactive components.

Rezultatul invenţiei constă în majorarea vitezei de măsurare a componentelor impedanţei. The result of the invention consists in increasing the measurement speed of impedance components.

Invenţia se explică prin desenele din fig. 1-3, care reprezintă diagramele vectoriale ale procesului de măsurare. The invention is explained by the drawings in Fig. 1-3, which represent the vector diagrams of the measurement process.

Conform metodei propuse obiectul măsurat cu impedanţa ZX, convertorul de impedanţă cu impedanţa de ieşire Zr şi generatorul de semnal cu curentul de ieşire I formează un circuit rezonant în serie. Impedanţa măsurată ZX şi impedanţa de referinţă Zr, reprodusă de convertor, pot fi reprezentate în coordonate carteziene: According to the proposed method, the measured object with impedance ZX, the impedance converter with output impedance Zr and the signal generator with output current I form a series resonant circuit. The measured impedance ZX and the reference impedance Zr, reproduced by the converter, can be represented in Cartesian coordinates:

ZX = RX + jXX\tab\tab\tab\tab\tab\tab\tab(1) ZX = RX + jXX\tab\tab\tab\tab\tab\tab\tab(1)

Zr = Rr + jXr , (2)Zr = Rr + jXr , (2)

unde: RX, XX, Rr, Xr - respectiv, componentele activă şi reactivă ale impedanţelor măsurată şi de referinţă; where: RX, XX, Rr, Xr - respectively, the active and reactive components of the measured and reference impedances;

j - unitatea imaginară. j - imaginary unit.

Semnalul de dezechilibru Ude prezintă suma căderilor de tensiune pe componentele activă (Ux) şi reactivă (Ur) ale impedanţelor măsurată şi de referinţă şi poate fi reprezentat: The unbalance signal Ude presents the sum of the voltage drops on the active (Ux) and reactive (Ur) components of the measured and reference impedances and can be represented:

Ude=Ux +Ur =I(Zx + Zr) =I[(Rx +jXx) + (Rr + jXr)]. \tab(3) Ude=Ux +Ur =I(Zx + Zr) =I[(Rx +jXx) + (Rr + jXr)]. \tab(3)

Impedanţa de referinţă Zr se reproduce de convertorul de impedanţă cu posibilitatea reglării independente a componentelor activă Rr şi reactivă Xr. The reference impedance Zr is reproduced by the impedance converter with the possibility of independent adjustment of the active Rr and reactive Xr components.

Echilibrarea circuitului de măsurare se efectuează prin două operaţii concomitente de reglare. La prima operaţie (vezi fig. 1) se reglează componenta activă Rr a impedanţei de referinţă, reprodusă de convertor, până la valoarea Rr0, căderea de tensiune pe aceasta obţinând valoarea URr0. Acest moment se determină după egalarea cu 180° sau 0° a defazajului dintre semnalele de dezechilibru Ude şi de referinţă UXr. În operaţia a doua, concomitentă cu prima (vezi fig. 2), se reglează componenta reactivă Xr a impedanţei de referinţă până la valoarea Xr0, căderea de tensiune pe aceasta obţinând valoarea UXr0. Acest moment se determină după egalarea cu 180° sau 0° a defazajului dintre semnalele de dezechilibru Ude şi de referinţă URr. La finisarea procesului de echilibrare a circuitului de măsurare (vezi fig. 3): The balancing of the measuring circuit is performed by two simultaneous adjustment operations. In the first operation (see fig. 1) the active component Rr of the reference impedance, reproduced by the converter, is adjusted to the value Rr0, the voltage drop on it obtaining the value URr0. This moment is determined after equalizing the phase shift between the unbalance signals Ude and the reference UXr with 180° or 0°. In the second operation, simultaneous with the first (see fig. 2), the reactive component Xr of the reference impedance is adjusted to the value Xr0, the voltage drop on it obtaining the value UXr0. This moment is determined after equalizing the phase shift between the unbalance signals Ude and the reference URr with 180° or 0°. At the end of the balancing process of the measuring circuit (see fig. 3):

I[(Rx + jXx) + (Rr0 + jXr0)] = 0. \tab\tab\tab\tab(4) I[(Rx + jXx) + (Rr0 + jXr0)] = 0. \tab\tab\tab\tab(4)

Soluţia ecuaţiei (4), care prezintă rezultatul măsurării, este: The solution to equation (4), which presents the measurement result, is:

Rx = -Rr0 , Xx = -Xr0. \tab\tab\tab\tab\tab(5) Rx = -Rr0 , Xx = -Xr0. \tab\tab\tab\tab\tab(5)

După cum rezultă din relaţia (5), la finisarea procesului de măsurare componentele activă şi reactivă ale impedanţei măsurate se exprimă respectiv prin componentele activă şi reactivă ale impedanţei de referinţă şi sunt reprezentate în coordonate carteziene. As follows from relation (5), at the end of the measurement process, the active and reactive components of the measured impedance are expressed respectively by the active and reactive components of the reference impedance and are represented in Cartesian coordinates.

Ca exemplu de implementare practică poate servi măsurarea componentelor impedanţei unei bobine de inductanţă, care conţine componenta reactivă Xx = 10 kΩ şi componenta activă Rx= 1 kΩ. Din inductanţa măsurată şi bornele de ieşire ale convertorului de impedanţă se formează un circuit de măsurare în serie, alimentat cu un curent I = 1 mA. La prima operaţie de echilibrare a circuitului de măsurare se reglează componenta activă a impedanţei de referinţă până la valoarea Rr0 = -1 kΩ. La a doua operaţie de echilibrare se reglează componenta reactivă a impedanţei de referinţă până la valoarea Xr0 = -10 kΩ. Valorile componentelor impedanţei măsurate constituie: RX = -Rr0 =1 kΩ, XX = -Xr0 = 10 kΩ, acesta fiind rezultatul măsurării. As an example of practical implementation, the measurement of the impedance components of an inductance coil, which contains the reactive component Xx = 10 kΩ and the active component Rx = 1 kΩ, can serve. From the measured inductance and the output terminals of the impedance converter, a series measurement circuit is formed, supplied with a current I = 1 mA. During the first balancing operation of the measurement circuit, the active component of the reference impedance is adjusted to the value Rr0 = -1 kΩ. During the second balancing operation, the reactive component of the reference impedance is adjusted to the value Xr0 = -10 kΩ. The values of the measured impedance components are: RX = -Rr0 =1 kΩ, XX = -Xr0 = 10 kΩ, this being the result of the measurement.

1. MD 3577 G2 2008.04.30 1. MD 3577 G2 2008.04.30

Claims

Method for measuring impedance components, which consists of forming a series measurement circuit from the measured object, the output terminals of an impedance converter with independent regulation of the active and reactive components of the reproduced impedance and a signal generator; forming an unbalance signal from the sum of the voltage drops on the measured object and the output circuit of the converter; controlling the phase shift between the unbalance signal and the reference signals; balancing the measurement circuit by adjusting the impedance components reproduced by the converter and determining the measured impedance components from their known dependence on the impedance components reproduced by the converter in a state of equilibrium, characterized in that the adjustment of the impedance components reproduced by the converter is performed simultaneously, until the phase shift of 180° or 0° between the imbalance signal and the reference signal is reached, and as reference signals for adjusting the active and reactive components, the voltage drops on the reactive and active components of the impedance reproduced by the converter are used, respectively.