RU2523772C1 - Two-terminal device parameter bridge meter - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: this bridge meter comprises feed pulse generator with voltage variation during their duration with tⁿ, where n at separate equalisation takes on values of 0, 1, 2, and 3, bridge circuit and zero-indicator. Said bridge circuit comprises two-terminal device with balanced resistors that make the bridge circuit second branch. Also, it comprises extra capacitor and two extra resistors. Note here that all extra elements are interconnected in series. Free terminal of capacitor is connected with pulse generator output. Free terminal of second resistor is grounded while bridge second branch second capacitor is connected to common terminal of extra resistors. Common terminal of 3^rd, 4^th, and 5^th resistors of bridge second branch make the bridge circuit output 2^nd terminal. This terminal is connected with differential input of zero-indicator. Second, fourth and both extra resistors are adjustable. Functional elements make target parameters, that is, first and second resistances of resistors and first and second capacitance of capacitors.

EFFECT: higher precision.

1 dwg

Description

The invention relates to instrumentation, automation and pro-electronics. In particular, it allows you to determine the parameters of four-element bipolar or sensor parameters with a four-element equivalent circuit.

Known bridge meter parameters of multi-element passive two-terminal [Peredelsky GI A.S. 1247762 G01R 17/10, 1986, No. 28], containing a series-connected pulse generator with voltage change over their duration according to the law of power functions, a bridge electrical circuit and a zero indicator.

Its disadvantage is the inability to balance the bridge circuit with grounded exemplary adjustable elements. Ungrounded adjustable elements form a parasitic capacitance relative to the "ground". Exemplary adjustable balancing elements have significantly larger overall dimensions than the dimensions of elements with a constant value of the parameter, therefore, the stray capacitance of these elements relative to the "ground" is also significantly larger. Spurious capacitances predetermine the corresponding component of the measurement error. From the instability of parasitic capacities, an additional component of the measurement error also arises, since they substantially change over time (for example, from aging) and especially strongly with temperature. Non-grounded, adjustable balancing elements are more strongly affected by electrical noise and interference. To mitigate this harmful effect, balancing elements are often shielded, then in the case of non-earthing of these elements, the question arises of which top of the electric bridge is best to connect the screens. Moreover, each of the available options for connecting screens is not perfect. If the above elements are grounded, then it is obvious that the screens should be connected to the "ground". In the case of regulating ungrounded balancing elements by using, for example, a matrix of resistors, electronic keys and control electric signals from the electronic control unit, additional difficulties arise and the need to use decoupling elements (transformers, optocoupler pairs). With grounded balancing elements, such difficulties are absent. In bridge devices, ceteris paribus, preference is given to bridge circuits with the largest number of grounded adjustable balancing elements.

The closest in technical essence and the achieved result to the claimed device is the electric bridge selected as a prototype [G. Peredelsky. A.S. 998967 G01R 17/10, 1983, No. 7], comprising a trapezoidal pulse generator, a bridge circuit and a zero indicator connected in series.

Its disadvantage is that the bridge circuit is balanced by ungrounded exemplary adjustable resistors.

The problem to which the invention is directed, is to increase the number of grounded reference adjustable resistors and bring it to half the total number of adjustable reference elements.

This is achieved by the fact that in a bridge meter of two-terminal parameters, it contains a supply pulse generator, which consists of pulse shapers with voltage changes over their duration according to the law k ₀ t ⁰ , k ₁ t ¹ , k ₂ t ² and k ₃ t ³ , where k ₀ , k ₁ , k ₂ and k ₃ are constant coefficients, t is the current time from the switch, from the power amplifier and synchronization unit, the output of each pulse shaper is connected to one of the inputs of the switch, its output is connected to the input of the power amplifier, the output of which forms the first output of the generator pulses relative to the "ground", the output of the synchronization unit is connected to the input (synchronization input) of each pulse shaper, and its output forms the second output (synchronization output) of the pulse generator relative to the "ground", the common bus of the pulse generator is grounded; the first output of the pulse generator is connected to the input of the bridge circuit, which forms the common output of two parallel connected branches of the bridge, the first branch of the bridge is formed by two terminals connected in series for connecting two-terminal measuring objects and a single resistor, one of the terminals is connected to the first output of the pulse generator, the common output of the other the terminal and the single resistor forms the first output terminal of the bridge circuit, the free terminal of the single resistor is grounded, the two-terminal device of the measurement object, in particular, consists of the first resistor, in parallel with which the first capacitor and the second resistor are connected in series, the second capacitor is connected in parallel to the last, the second branch of the bridge circuit consists of the first and second resistors connected in series, the free output of the first resistor is connected to the first output of the pulse generator, the free output of the second resistor is grounded, parallel to the first resistor is connected an electric circuit of series-connected first capacitor, third and fourth resistor , to the common output of the third and fourth resistors, a circuit is connected from the fifth resistor and the second capacitor connected in series, a null indicator, the first differential input of which is connected to the first output of the bridge circuit output, the null indicator synchronization input is connected to the second output of the pulse generator, a common bus the zero indicator is grounded, an additional capacitor and two additional resistors are introduced, and the inclusion of elements is changed, all additional elements: capacitor, first and second resistors are connected in series with each other, the free output of the additional capacitor is connected to the first output of the pulse generator, the free output of the second additional resistor is earthed, the free output of the second capacitor of the second branch of the bridge circuit is connected to the common output of the two additional resistors, the common output of the third, fourth and fifth resistors of the second branch of the bridge forms the second output terminal of the bridge circuit, this second terminal is connected to the second terminal of the differential input of the null indicator.

The invention is illustrated in the drawing.

The bipolar bridge meter contains a supply generator, an electric bridge measuring circuit, and a null indicator. The supply generator 1 consists of shapers 2, 3, 4, and 5 sequences of rectangular, ramp, quadratic, and cubic pulses and has two outputs formed by three terminals, one of which is grounded. The generator also contains a switch 6, the inputs of which are connected to the outputs of the shapers, and the output is connected to a power amplifier 7, the output of the latter is the first output of the pulse generator relative to the ground, and the synchronization unit 8, the output of which is connected to the synchronization inputs of the shapers, as well as this output is the second output of the pulse generator relative to the "ground" (synchronization output).

The first of the two branches of the electric bridge has two terminals for connecting the two-terminal device of the measurement object and a single resistor 9 (R ₉ ) consecutive with them, one of the terminals is connected to the first output of the pulse generator, the common terminal of the other terminal and single resistor forms the first output terminal of the bridge circuit, the free output of a single resistor is grounded.

The bipolar of the measurement object consists of a resistor 10 (R ₁₀ ), in parallel with which a capacitor 11 (C ₁₁ ) and a resistor 12 (R ₁₂ ) are connected in series, a capacitor 13 (C ₁₃ ) is connected in parallel with the latter.

The second branch of the bridge circuit is formed by series-connected resistors 14 (R ₁₄ ) and 15 (R ₁₅ ). The free output of the resistor 14 is connected to the first output of the pulse generator, the free output of the resistor 15 is grounded. In parallel to the resistor 14, an electric circuit is connected from a series-connected capacitor 16 (C ₁₆ ), resistors 17 (R ₁₇ ) and 18 (R ₁₈ ). A circuit of series-connected resistor 19 (R ₁₉ ) and capacitor 20 (C ₂₀ ) is connected to the common terminal of the resistors.

The first terminal of the differential input of the null indicator 24 is connected to the first terminal of the output of the bridge circuit. The synchronization input of the null indicator is connected to the second output of the pulse generator, the common bus of the null indicator is grounded.

A circuit from series-connected capacitor 21 (C ₂₁ ), resistors 22 (R ₂₂ ) and 23 (R ₂₃ ) is also connected to the first output of the pulse generator. The free terminal of the capacitor 21 is connected to the first output of the generator. The free terminal of the resistor 23 is grounded. To the common terminal of the resistors is connected the free terminal of the capacitor 20.

The common terminal of the resistors 17, 18 and 19 forms the second terminal of the bridge circuit output, this second terminal is connected to the second terminal of the differential input of the null indicator.

A bridge meter for the parameters of bipolar operates as follows. In the initial state, the voltages at the input and output of the four-arm bridge circuit are zero. We apply a rectangular pulse train to the bridge from generator 1. Under the action of the next pulse in the steady state, unchanging voltages are established in the branches of the bridge circuit. The flat peak of the nonequilibrium voltage pulse here depends only on the resistances of the resistors 9, 10, 14 and 15. The first condition for the equilibrium of the bridge circuit is

$$A_{\mathrm{one}}=R_{10}{R}_{\mathrm{fifteen}}-R_9{R}_{\mathrm{fourteen}}=0.(\mathrm{one})$$

By a single adjustment of the resistance value of the reference resistor 15, the flat peak of the impulse nonequilibrium signal is reduced to zero, thereby fulfilling the first equilibrium condition of the bridge circuit (1). The equilibrium of the bridge circuit here and hereinafter is indicated by the zero indicator 24, while the synchronization signal from the second output of the generator 1 to the second input of the zero indicator ensures the stability of its readings.

Next, at the input of the bridge circuit, we feed from the generator 1 a sequence of pulses that vary linearly. When the next such pulse is applied, after the end of the transition process, an impulse non-equilibrium signal with a flat top is established at the output of the bridge circuit. The second condition for the equilibrium of the bridge is

$$A_2=\left(R_{10}{C}_{16}-R_9{C}_{\mathrm{twenty}}\right)V_{\mathrm{one}}-R_9{R}_{10}{R}_{\mathrm{fourteen}}{C}_{\mathrm{eleven}}=0(2)$$

where V ₁ = R ₁₄ R ₁₅ + R ₁₄ R ₁₈ + R ₁₅ R ₁₈ (3)

It is performed by adjusting the resistance value of the reference resistor 18. By adjusting the resistance once, we bring the flat top of the impulse nonequilibrium signal to zero, i.e. we fulfill the second equilibrium condition (2), while the first condition (1) is not violated, since the parameter R ₁₈ regulated here is not included in it.

Then to the input of the bridge circuit we feed from the generator 1 a sequence of quadratic pulses. When the next such pulse is applied, at the end of the transient process, a pulse equilibrium signal with a flat top is established at the output of the bridge circuit. The third condition for the equilibrium of the bridge chain is

$$\begin{array}{l}{A}_3=V_{\mathrm{one}}[R_{10}{R}_{23}{V}_2+R_{12}{C}_{\mathrm{eleven}}(R_{10}{C}_{16}-R_9{C}_{\mathrm{twenty}})+R_9{C}_{\mathrm{twenty}}(R_{19}{C}_{\mathrm{twenty}}-\\ -R_{17}{C}_{16}-R_{10}{C}_{\mathrm{eleven}})]-R_9{R}_{10}{R}_{\mathrm{fourteen}}{C}_{\mathrm{eleven}}[R_{17}{C}_{16}+R_{23}(C_{\mathrm{twenty}}+C_{21})]=0(\mathrm{four})\end{array}$$

Where $$V_2=C_{16}{C}_{\mathrm{twenty}}+C_{16}{C}_{21}+C_{\mathrm{twenty}}{C}_{21}.(5)$$

By a single adjustment of the resistance of the model resistor 23, we bring the flat peak of the impulse nonequilibrium voltage to zero and fulfill the third equilibrium condition (4), while the first two equilibrium conditions (1) and (2) are not violated, since the parameter R ₂₃ regulated here is not included .

Next, at the input of the bridge circuit, we feed from the generator 1 a sequence of cubic pulses. When the next such pulse is applied, after the end of the transition process, an impulse non-equilibrium signal with a flat top is established at the output of the bridge circuit. The fourth condition for the equilibrium of the bridge chain is

By once adjusting the resistance of the model resistor 22, we bring the flat peak of the nonequilibrium voltage pulse to zero and fulfill the fourth equilibrium condition (6), while the first three equilibrium conditions (1), (2) and (4) are not violated, since the parameter R ₂₂ regulated here not included in them.

The above shows that the separate balancing of the bridge circuit should be carried out in the sequence 15, 18, 23, 22. According to the equations of the equilibrium condition (1), (2), (4) and (6), the desired four parameters R ₁₀ , C ₁₁ are counted R ₁₂ , C ₁₃ . The values of the parameters of the elements 9, 14, 16, 17, 19, 20, 21 of the bridge circuit are constant and known. The parameters R ₁₅ , R ₁₈ , R ₂₂ and R ₂₃ are adjustable and also known.

Thus, the task of increasing the number of grounded reference balancing resistors in the bridge circuit, bringing it to half of the total number of adjustable reference resistors in the present invention, is solved. In this case, the property of separate balancing of the measuring bridge is not violated.

Claims (1)

A bridge meter of two-terminal parameters, containing a pulse generator, which consists of pulse shapers with voltage changes over their duration according to the law k ₀ t ⁰ , k ₁ t ¹ , k ₂ t ² and k ₃ t ³ , where k ₀ , k ₁ , k ₂ and k ₃ are constant coefficients, t is the current time from the switch, from the power amplifier and synchronization unit, the output of each pulse shaper is connected to one of the inputs of the switch, its output is connected to the input of the power amplifier, the output of which forms the first output of the pulse generator regarding the "earth", exit the synchronization unit is connected to the input of each pulse shaper (synchronization input), and its output forms the second output (synchronization output) of the pulse generator relative to the ground, the common bus of the pulse generator is grounded, the first output of the pulse generator is connected to the input of the bridge circuit, which forms a common the output of two parallel connected branches of the bridge, the first branch of the bridge is formed by two terminals for connecting the two-terminal device of the measurement object, which, in particular, consists of the first resistor, parallel about it, the first capacitor and the second resistor are connected in series, the second capacitor is connected in parallel to the last, a single resistor is connected in series with two terminals, the first terminal for connecting the two-terminal device of the measurement object is connected to the first output of the pulse generator, the common output of the second terminal and a single resistor forms one of two the outputs of the bridge circuit output, the free output of a single resistor is grounded, the second branch of the bridge circuit consists of a series of connected first and second of the resistors, the free output of the first resistor is connected to the first output of the pulse generator, the free output of the second resistor is earthed, an electric circuit from the first capacitor, the third and fourth resistors connected in series is connected in parallel to the first resistor, a fifth network connected from the fifth is connected to the common output of the third and fourth resistors a resistor and a second capacitor, a null indicator, the first terminal of the differential input of which is connected to the first output terminal of the bridge circuit, the synchronization input of the null indicator is connected to the second output of the pulse generator, the common bus of the null indicator is grounded, characterized in that an additional capacitor and two additional resistors are introduced into it and the inclusion of elements is changed, all additional elements: a capacitor, the first and second additional resistors are connected between by itself, the free output of the additional capacitor is connected to the first output of the pulse generator, the free output of the second additional resistor is grounded, to the common output one additional two resistors is connected to the free terminal of the second capacitor of the second branch of the bridge circuit, the common terminal of the third, fourth and fifth resistors of the second branch of the bridge forms the second terminal of the output of the bridge circuit, this second terminal is connected to the second terminal of the differential input of the null indicator.