MD591Z

MD591Z - Method for measurement of impedance component

Info

Publication number: MD591Z
Application number: MDS20120128A
Authority: MD
Inventors: Виталие НАСТАС
Original assignee: Технический университет Молдовы
Priority date: 2012-09-11
Filing date: 2012-09-11
Publication date: 2013-08-31
Also published as: MD591Y

Abstract

The invention relates to the field of electrical and electronic measurements and can be used for high-precision measurement of one impedance component.The method for measurement of impedance component includes the formation of a series measuring circuit, consisting of a measured object, output contacts of an impedance converter and a signal generator, control of the phase shift between the reference signal and disequilibrium signal, formed by the total voltage drop in the measured object and the output circuit of the converter, balancing of the measuring circuit by adjusting the component corresponding to the measured one of the impedance reproduced by the converter, and determination of the value of the measured impedance component of its equity with the value of the regulated component of the impedance reproduced by the converter in the equilibrium state taken with the opposite sign. The reference signal is generated by the phase coinciding with the phase of the measured impedance component. Balancing of the measuring circuit is carried out up to the achievement of a phase shift equal to 90° between the reference signal and disequilibrium signal.

Description

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

Este cunoscută o metodă de măsurare a unei componente a impedanţei, care prevede formarea unui circuit de măsurare în serie, constând dintr-un obiect măsurat, un convertor de impedanţă şi un generator de semnal, formarea unui semnal de referinţă cu faza, care coincide cu faza componentei nemăsurate a impedanţei reproduse de convertor, echilibrarea circuitului de măsurare se efectuează prin reglarea componentei impedanţei reproduse de convertor până la obţinerea unui defazaj de 0 sau 180° între semnalul de dezechilibru şi cel de referinţă şi determinarea componentei măsurate a impedanţei necunoscute din egalitatea ei cu semn opus cu componenta impedanţei reproduse de convertor [1]. A method for measuring an impedance component is known, which provides for the formation of a series measurement circuit, consisting of a measured object, an impedance converter and a signal generator, the formation of a reference signal with the phase, which coincides with the phase of the unmeasured impedance component reproduced by the converter, the balancing of the measurement circuit is performed by adjusting the impedance component reproduced by the converter until a phase shift of 0 or 180° is obtained between the imbalance signal and the reference one and the determination of the measured component of the unknown impedance from its equality with the opposite sign with the impedance component reproduced by the converter [1].

Dezavantajul acestei metode constă în formarea semnalului de referinţă cu faza, care coincide cu faza componentei nemăsurate a impedanţei reproduse de convertor. Aceasta necesită utilizarea unui convertor de impedanţă cu structură complexă, ceea ce complică implementarea practică a metodei. The disadvantage of this method is that the reference signal is formed with a phase that coincides with the phase of the unmeasured impedance component reproduced by the converter. This requires the use of an impedance converter with a complex structure, which complicates the practical implementation of the method.

Problema pe care o rezolvă invenţia constă în simplificarea metodei de măsurare a componentei impedanţei. The problem that the invention solves consists in simplifying the method of measuring the impedance component.

Metoda de măsurare a componentei impedanţei, conform invenţiei, înlătură dezavantajele menţionate prin aceea că include formarea unui circuit de măsurare în serie, constând dintr-un obiect măsurat, contactele de ieşire ale unui convertor de impedanţă şi un generator de semnal, controlul defazajului între semnalul de referinţă şi semnalul de dezechilibru, format din căderea sumară de tensiune pe obiectul măsurat şi circuitul de ieşire al convertorului, echilibrarea circuitului de măsurare prin reglarea componentei corespunzătoare celei măsurate a impedanţei reproduse de convertor, precum şi determinarea valorii componentei măsurate a impedanţei din egalitatea ei cu valoarea componentei reglate a impedanţei reproduse de convertor în starea de echilibru luată cu semn opus. Semnalul de referinţă se formează cu o fază, care coincide cu faza componentei măsurate a impedanţei. Echilibrarea circuitului de măsurare se efectuează până la obţinerea unui defazaj de 90° între semnalul de referinţă şi semnalul de dezechilibru. The method of measuring the impedance component, according to the invention, eliminates the aforementioned disadvantages by including the formation of a series measuring circuit consisting of a measured object, the output contacts of an impedance converter and a signal generator, controlling the phase shift between the reference signal and the imbalance signal, formed by the sum of the voltage drop on the measured object and the output circuit of the converter, balancing the measuring circuit by adjusting the component corresponding to the measured one of the impedance reproduced by the converter, as well as determining the value of the measured impedance component from its equality with the value of the adjusted component of the impedance reproduced by the converter in the equilibrium state taken with the opposite sign. The reference signal is formed with a phase that coincides with the phase of the measured impedance component. The balancing of the measuring circuit is carried out until a phase shift of 90° is obtained between the reference signal and the imbalance signal.

Rezultatul invenţiei constă în asigurarea măsurării cu mare precizie a componentei active sau reactive a impedanţei. The result of the invention consists in ensuring the measurement with high precision of the active or reactive component of the impedance.

Invenţia se explică prin desenele din fig. 1-2, care reprezintă: The invention is explained by the drawings in Fig. 1-2, which represent:

- fig.1, metoda în cazul măsurării componentei active a impedanţei; - fig.1, the method in the case of measuring the active component of the impedance;

- fig.2, metoda în cazul măsurării componentei reactive a impedanţei. - fig.2, the method in the case of measuring the reactive component of the impedance.

Impedanţa măsurată Zx şi impedanţa reprodusă de convertor Zr pot fi reprezentate: The measured impedance Zx and the impedance reproduced by the converter Zr can be represented:

Zx = Rx + jXx (1) Zx = Rx + jXx (1)

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

unde: Rx, Xx, Rr, Xr - respectiv, componentele active şi reactive ale impedanţei măsurate şi celei reproduse de convertor, j - unitate imaginară. where: Rx, Xx, Rr, Xr - respectively, the active and reactive components of the measured impedance and that reproduced by the converter, j - imaginary unit.

Obiectul măsurat cu impedanţa 1 şi convertorul de impedanţă cu impedanţa de ieşire 2 formează un circuit rezonant în serie, alimentat cu semnul de măsurare cu intensitatea curentului I, care formează căderile de tensiune Ux pe impedanţa măsurată şi Ur pe impedanţa de referinţă. The measured object with impedance 1 and the impedance converter with output impedance 2 form a series resonant circuit, supplied with the measurement signal with current intensity I, which forms the voltage drops Ux on the measured impedance and Ur on the reference impedance.

Tensiunea Ude, obţinută în urma interacţiunii curentului I cu circuitul rezonant, este: The voltage Ude, obtained from the interaction of the current I with the resonant circuit, is:

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

În cazul măsurării componentei active Rx a impedanţei Zx (fig. 1) poate fi utilizat un convertor de rezistenţă negativă, pentru care Zr = Rr. Semnalul de referinţă va avea aceeaşi fază, ca şi căderea de tensiune pe impedanţa reprodusă de convertor. În procesul de măsurare se reglează componenta Rr până la obţinerea unui defazaj de 90° între semnalul de dezechilibru şi cel de referinţă. Conform fig. 1, acestei stări îi corespunde: In the case of measuring the active component Rx of the impedance Zx (fig. 1) a negative resistance converter can be used, for which Zr = Rr. The reference signal will have the same phase as the voltage drop across the impedance reproduced by the converter. In the measurement process, the component Rr is adjusted until a 90° phase shift is obtained between the unbalance signal and the reference signal. According to fig. 1, this state corresponds to:

I(Rx + Rr) = 0 (4) I(Rx + Rr) = 0 (4)

Soluţia ecuaţiei (4) este Rx = -Rr, ceea ce constituie rezultatul măsurării. The solution to equation (4) is Rx = -Rr, which is the result of the measurement.

În cazul măsurării componentei reactive Xx a impedanţei Zx (fig. 2) poate fi utilizat un convertor de impedanţă cu caracter reactiv, pentru care Zr = jXr. În procesul de măsurare se reglează componenta Xr până la obţinerea unui defazaj de 90° între semnalul de dezechilibru şi cel de referinţă. Conform fig. 2, acestei stări îi corespunde: In the case of measuring the reactive component Xx of the impedance Zx (fig. 2) an impedance converter with a reactive character can be used, for which Zr = jXr. In the measurement process, the component Xr is adjusted until a phase shift of 90° is obtained between the unbalance signal and the reference one. According to fig. 2, this state corresponds to:

I(Xx + Xr) = 0 (5) I(Xx + Xr) = 0 (5)

Soluţia ecuaţiei (5) este Xx = -Xr, ceea ce constituie rezultatul măsurării. The solution to equation (5) is Xx = -Xr, which is the result of the measurement.

După cum rezultă din (4), (5), la terminarea procesului de măsurare componentele măsurate ale impedanţei necunoscute se exprimă respectiv prin componenta activă sau reactivă a impedanţei reproduse de convertor. As follows from (4), (5), at the end of the measurement process the measured components of the unknown impedance are expressed respectively by the active or reactive component of the impedance reproduced by the converter.

Exemplu de implementare practică. Example of practical implementation.

Măsurarea componentelor impedanţei unei bobine de inductanţă, care conţine componenta reactivă Xx = 10 kΩ şi componenta activă Rx = 1 kΩ decurge în modul următor. Din bobina măsurată şi contactele de ieşire ale convertorului de impedanţă se formează un circuit rezonant de măsurare în serie alimentat de un curent I = 1mA. În cazul măsurării componentei active a impedanţei convertorul reproduce o rezistenţă negativă, care se reglează până la valoarea Rr = -1 kΩ. În cazul măsurării componentei reactive a impedanţei bobinei convertorul reproduce o impedanţă cu caracter reactiv, care se reglează până la valoarea Xx = -10 kΩ. Conform (4), (5), valorile componentelor măsurate ale impedanţei bobinei constituie în primul caz Rx = -Rr = 1 kΩ, iar într-al doilea caz Xx = -Xr = 10 kΩ, care reprezintă rezultatele măsurărilor. 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, proceeds as follows. The measured coil and the output contacts of the impedance converter form a series resonant measuring circuit powered by a current I = 1 mA. In the case of measuring the active component of the impedance, the converter reproduces a negative resistance, which is adjusted to the value Rr = -1 kΩ. In the case of measuring the reactive component of the coil impedance, the converter reproduces an impedance with a reactive character, which is adjusted to the value Xx = -10 kΩ. According to (4), (5), the values of the measured components of the coil impedance are in the first case Rx = -Rr = 1 kΩ, and in the second case Xx = -Xr = 10 kΩ, which represent the measurement results.

1. MD 447 Z 2012.06.30 1. MD 447 Z 2012.06.30

Claims

Method for measuring the impedance component, which includes forming a series measuring circuit, consisting of a measured object, the output contacts of an impedance converter and a signal generator; controlling the phase shift between the reference signal and the unbalance signal, formed by the sum of the voltage drop on the measured object and the output circuit of the converter; balancing the measuring circuit by adjusting the component corresponding to the measured one of the impedance reproduced by the converter; determining the value of the measured impedance component from its equality with the value of the adjusted component of the impedance reproduced by the converter in the equilibrium state taken with the opposite sign, characterized in that the reference signal is formed with a phase that coincides with the phase of the measured impedance component; balancing the measuring circuit is carried out until a phase shift of 90° is obtained between the reference signal and the unbalance signal.