RU2589273C2 - Device for measuring complex resistance of bridge circuit - Google Patents

Abstract

FIELD: electrical measurement equipment.

SUBSTANCE: invention relates to electrical engineering, and particularly to AC bridge methods of measuring arm complex impedance parameters, and can be used in devices for measuring amount of fuel, in particular for devices for measuring fuel consumption of manned spacecraft to measure low flow rates. Device measuring complex impedance of bridge circuit comprising an adjustable amplifier imbalance element constant frequency generator, a phase shifter, first and second comparators, amplitude, phase sensitive lock first amplifier measuring a bridge transformer filter. Constant frequency generator is connected via a second amplifier and a transformer to input terminals of input transformer measuring bridge diagonal, midpoints of which are connected and grounded. Second input of first amplifier is connected to output terminal of second bridge diagonal of measuring transformer. Between first input of first amplifier and mid-point of bridge transformer there is a measuring resistor. Controlled amplifier and imbalance element are connected in series and connected between second input of first amplifier and mid-point of measuring bridge transformer. Using claimed device for its implementation reduces guarantee reserves of fuel components in tanks of aerospace hardware, thus increasing weight of useful output load of launch vehicles.

EFFECT: broader functional capabilities by enabling measurement of fuel consumption under zero gravity and at low costs and high measurement accuracy.

1 cl, 2 dwg

Description

The invention relates to electrical engineering, and in particular to bridge methods for measuring alternating current parameters of the shoulder complex resistances, and can be used in devices for measuring the amount of fuel, in particular in devices for measuring low flow rates.

Accurate measurement of the consumption of fuel components in rocket and space technology products, in particular, transport cargo ships (TGKs) and Progress and Soyuz transport manned ships (TPKs), is of great importance. Before each launch of the Progress and Soyuz cargo and manned spacecraft, refueling is spent on all dynamic operations prior to docking with the International Space Station (ISS) in combination with regular launch and various launching options in case of a correction system failure. The obtained control values guarantee the sufficiency of fuel on the ship during descent in the most adverse conditions. The fuel consumption measurement on board the ship is performed by the fuel consumption measurement system. In this case, the ball tachometer sensor is a flow meter.

The known method, selected as an analogue "Method for measuring the parameters of three-element bipolar frequency-independent bridges of alternating current" described in patent No. 2144196 class. G01R 17/10, 27/02, consists in balancing the bridge at the first frequency using the sign of the information projection of the unbalance signal at the second frequency, the size of the controlled actions by changing one of the three adjustable parameters of the comparison arm in the definition of the unbalance signal modulus at the second frequency, and their select the direction by the sign of the increment of this module during the trial measurement of the third parameter of the comparison arm relative to its established value.

The known device selected as an analogue "Device for measuring electric capacitance" described in the patent of the Russian Federation No. 2186402, class. G01F 27/02, 17/12, includes a measuring transformer bridge (ITM), a frequency-controlled generator, the first output of which is connected to the midpoint of the primary winding of the ITM differential transformer, a synchronous detector (LED) of the main signal, the first input of which is electrically connected to the input ITM, the second input - with the second input of a frequency-controlled generator, and the output through a series-connected filter and a scaling amplifier of the main signal - with an ITM unbalance indicator.

The disadvantages of analogues include the lack of functionality and low speed measurement of the value of the complex resistance when it is used, for example, in the implementation of a device for measuring the amount of fuel at low costs.

The closest in technical essence and the achieved positive effect to the claimed device relates to a device for measuring the complex resistance of a bridge circuit with close inductive coupling, described in the patent of Russian Federation No. 2224261 "Method for measuring the complex resistance of a bridge circuit with close inductive coupling and a device for its implementation" by Balakin S.V., Dyvaka A.N., Khachaturova Y.V.

A bridge impedance measuring device comprising an adjustable amplifier, an imbalance element, a constant frequency generator connected through a series-connected phase shifter and a first amplitude comparator to the first input of the phase-sensitive latch, the first amplifier, the first input of which is connected to the first terminal of the output diagonal of the bridge measuring transformer, the output of the first amplifier through the filter and the second amplitude comparator is connected to the second input zochuvstvitelnogo latch whose output is an output device.

When measuring the complex resistance of the prototype device, for example, when performing a device for measuring the amount of fuel:

- the prototype is not able to measure low fuel consumption, as structurally close capacitive discrete sensors in the tank of the product of the RCT is not possible to arrange;

- the prototype measures the amount of fuel only under the influence of gravity (overload), and in zero gravity it is not possible to measure fuel consumption.

Thus, the disadvantage of the prototype is the inability to measure the complex resistance of the bridge circuit in zero gravity, and, as a consequence, the measurement of the amount of fuel in zero gravity, as well as the inability to measure low fuel consumption.

The objective of the device for measuring the complex resistance of a bridge circuit is to expand its functionality by providing measurements of fuel consumption in zero gravity and at low costs and to increase the accuracy of measurement.

The technical result is achieved due to the fact that in the device for measuring the complex resistance of a bridge circuit containing an adjustable amplifier, an imbalance element, a constant frequency generator connected through a series-connected phase-shifting device and a first amplitude comparator to the first input of the phase-sensitive latch, the first amplifier, the first input of which is connected to the first terminal of the output diagonal of the bridge measuring transformer, while the output of the first amplifier through the filter and the second the amplitude comparator is connected to the second input of the phase-sensitive latch, the output of which is the output of the device, unlike the prototype, the constant frequency generator is connected through the second amplifier and transformer to the input terminals of the input diagonal of the bridge measuring transformer, the midpoints of which are connected and grounded, the second input of the first amplifier is connected to the second terminal of the output diagonal of the bridge measuring transformer, and between the first input of the first amplifier and the midpoint of the bridge and a measuring transformer a resistor is connected, and an adjustable amplifier and an imbalance element are connected in series and connected between the second input of the first amplifier and the midpoint of the bridge measuring transformer.

A device for measuring fuel consumption of a transported manned spacecraft, in the implementation of which the claimed device is used, is constructed as follows. The primary converter of the fuel consumption measuring system is a flow sensor (ball tachometric sensor together with a magnetic system made in the form of a bridge measuring transformer). In this case, the ball tachometric sensor is a meter of low flow. The operational experience of cargo and manned ships has shown that the ball tachometric sensor, together with the bridge measuring transformer, is subject to mechanical stress. These mechanical effects lead to a distortion of the useful signal from the bridge measuring transformer and, accordingly, to a temporary violation of its performance, which leads to incorrect measurement of fuel consumption. A bridge measuring transformer is installed outside the ball tachometric sensor for measuring fuel consumption welded into the fuel supply pipe to rocket engines. At fuel consumption, the ball begins to move in a circle inside the cochlea and, each time passing near the core of the bridge measuring transformer, introduces losses into its magnetic system. As a result, there is a change in the complex resistances in the compared arms of the bridge measuring transformer due to a change in the inductance of the bridge windings. The complex resistances of the shoulders of the bridge measuring transformer vary within specified limits, alternately transfer the bridge circuit from one nonequilibrium state to another, passing each time the equilibrium state of the bridge. In this case, the fixation of the equilibrium state of the bridge circuit is the output signal of the device for measuring the complex resistance of the bridge circuit, which is the front of the transition from a logical zero state to a unit state or vice versa, and by which the measured value of the complex resistance of the bridge circuit is judged. As a result of one turn of the ball in the cochlea, the bridge measuring transformer passes the equilibrium state twice, forming a single counting pulse, which judges the spent fuel amount, which is equal to 1.65 grams in a particular case. In this case, the pulse duration is determined by the zone of action of the ball on the magnetic system of the bridge measuring transformer. The signs characterizing the connection of a series-connected adjustable amplifier and an imbalance element parallel to the shoulder of the bridge measuring transformer provide a specific value of the complex resistance of the bridge circuit. The set value of the measured complex resistance should be sufficient for conditions under which mechanical stresses and loads on the sensor, leading to a change in the characteristics of the magnetic system of the bridge measuring transformer, would ensure that the bridge measuring transformer is in equilibrium when the ball moves in the cochlea. Thereby, the above features provide improved measurement accuracy. Moreover, during the passage of the ball near the core of the bridge measuring transformer, the complex shoulder resistance is measured by fixing the equilibrium state of the bridge. And the signs characterizing the connection of the output of the frequency generator through the second amplifier and transformer to the input diagonal terminals of the bridge measuring transformer provide a comparison of the phases of the reference frequency signal and the mismatch signal of the bridge measuring transformer. Thus, the set of features presented above increases the accuracy of measuring the complex resistance of the bridge circuit and expands the functionality of the device by providing measurements of fuel consumption in zero gravity and at low costs.

In FIG. 1 is a functional diagram of one embodiment of a device for measuring the complex resistance of a bridge circuit.

In FIG. 2 shows the timing diagrams of the functioning of the device for measuring the complex resistance of the bridge circuit, where:

a) current generator constant frequency;

b) currents of the shoulder bridge circuit;

c) the current signal of the difference of the bridge circuit;

g) the current reference pulses obtained by converting the current signal of a constant frequency generator in the first amplitude comparator;

d) the current of the difference pulses obtained by converting the current of the difference signal in the second amplitude comparator;

e) the pulse current of the counts of the flow sensor, formed by a phase-sensitive latch.

In the diagrams of FIG. 2 shows the ball coverage.

We will explain the essence of the claimed device by the example of its implementation in the fuel consumption measurement system of TGK Progress and TPK Soyuz. The fuel consumption measuring system includes several flow sensors (DR) and an electronic flow pulse shaper (EFIR). DR is made in the form of a ball tachometric sensor and a bridge measuring transformer, the core of which is structurally tangent to the sensor coil, in which the ball moves in a circle around the fuel supply.

The device according to FIG. 1 contains a constant frequency generator 1, an adjustable 2 amplifier, an imbalance element 3, a phase shifter 4 device, a first amplitude 5 comparator, a phase sensitive 6 retainer, a first amplifier 7, a bridge measuring transformer 8, a filter 9, a second amplitude 10 comparator, a second amplifier 11, a transformer 12, resistor 13, ball 14 tachometer sensor, flow sensor 15. Moreover, in the bridge measuring transformer 8, the first output I and second output II windings of the output diagonal are indicated.

The device according to FIG. 1 contains a constant frequency generator 1 connected through a second amplifier 11 and a transformer 12 to the input diagonal of the bridge measuring transformer 8. The output diagonal of the bridge measuring transformer is connected to the input of the amplifier 7, the output of which through a series-connected filter 9 and the second amplitude 10 comparator is connected to one of phase-sensitive inputs of the 6 latch. In addition, the constant frequency generator 1 is connected through a phase-shifting device 4 and a first amplitude 5 comparator connected to a different phase-sensitive input 6 of the latch, the output of which is the output of the device. Moreover, in the diagonal output of the bridge measuring transformer, a resistor 13 is connected in parallel to one of the arms of the bridge circuit, and an adjustable 2 amplifier and an unbalance element 3 are connected in series to the other arm. The bridge measuring transformer 8 and the ball 14 tachometric sensor form a flow sensor 15.

In the initial position of the fuel consumption measurement system, the DR ball can be located anywhere in the cochlea in which the ball moves when fuel is supplied. When fuel is supplied to rocket engines, the ball begins to rotate at a frequency of 80 to 100 Hz. When the ball rotates, a zone appears in the sensor, when moving, the ball makes changes to the magnetic system of the bridge measuring transformer. The bridge measuring transformer is configured in such a way that the changes made by the ball to the magnetic system transfer the bridge measuring transformer from one nonequilibrium state to another, while each time passing through the equilibrium state of the bridge circuit. Thus, at two points at the entrance and exit of the ball (see Fig. 1, Fig. 2), the bridge measuring circuit is in equilibrium. When formulating the features of the invention, the property of the bridge measuring circuit was taken into account, according to which, when passing the equilibrium position, the phase of the carrier frequency of the difference signal changes by 180 °. The output windings of the bridge measuring transformer, comprising the shoulders of the bridge circuit and connected to the input of the amplifier, are turned on in the opposite direction. Accordingly, the shoulder complex currents proportional to the shoulder resistance of the windings are subtracted. According to the results of the ratio of the shoulder complex currents proportional to the shoulder resistances of the bridge measuring transformer, a differential current is generated that is input to the amplifier 7 to measure the complex resistance.

The constant frequency generator 1 is designed to power the bridge 8 of the measuring transformer with alternating current, the supply of which is through the second amplifier 11 and the transformer 12.

In the timing diagram of FIG. 2a shows the current of a constant frequency generator, which is described by the expression

where ψ is the phase shift of the current, in the specific case equal to zero.

In the timing diagram of FIG. 2b shows brachial currents proportional to brachial complex resistances. Moreover, the bridge measuring transformer is configured in such a way that it is in a non-equilibrium state when the ball is either out of range or in range. The bridge transformer reaches equilibrium at the moments of entry and exit of the ball. In the first case, the complex resistance of the first output winding of the bridge measuring transformer is greater than the complex resistance of the second output winding. In the second case, when the ball is in range, on the contrary, the complex resistance of the first output winding of the bridge measuring transformer is less than the complex resistance of the second output winding. The above-described state of the bridge measuring transformer is achieved by the ratio of the turns of the windings, as well as the adjustment, which is carried out by the resistor 13 for the first winding of the transformer and connected in series with an adjustable 2 amplifier and an unbalance element 3 for the second winding of the transformer. A resistor can be used as an imbalance element, and a digital-to-analog converter can be used as an adjustable amplifier, which allows for accurate tuning of the bridge measuring transformer to a specific value of the complex resistance, which will be measured when the ball enters the coverage area by fixing the state of equilibrium of the bridge. Thus, the signs providing the connection to the second output winding of the output diagonal of the bridge of a series-connected adjustable amplifier and an unbalance element provide a specific task of the complex resistance of the bridge circuit.

The bridge measuring transformer is made in sections, the first and second windings of the input and output diagonals of the transformer are wound into different sections. Moreover, the core of the transformer touches the scroll of the sensor, in which the ball moves when fuel is supplied to the engines.

During the fuel supply, the ball moves along the cochlea and, falling into the coverage area, introduces losses into the magnetic system of the bridge measuring transformer. In this case, the inductance of the second winding increases and, accordingly, its complex resistance increases. In FIG. 2 vertical lines indicate the area of action of the ball when moving in the cochlea during fuel supply. In the timing diagram of FIG. 2c shows the current of the difference signal. Moreover, outside the coverage area, the complex resistance of the first winding of the output diagonal of the bridge is greater and the phase of the difference signal coincides with the phase of the current of the second winding. In the area of the ball, the complex resistance of the second winding is greater than the first, so the phase of the difference signal changes by 180 ° and coincides with the phase of the current of the first winding of the output diagonal of the bridge.

The currents formed in the shoulders of the bridge measuring transformer I ₁ , I ₂ change in proportion to the change in shoulder resistance, the value of which depends on the position of the ball in the flow sensor.

The signal current of the bridge difference is determined by the expression

the timing diagram of which is shown in FIG. 2c.

The measurement of the complex resistance of the bridge measuring transformer is carried out by fixing the moment of phase change of the signal of the bridge difference and proceeds as follows.

The formation of the difference signal current is carried out by subtracting the modules and phases of the compared currents of the on-connected shoulder windings in the output diagonal of the transformer 8. Analytically, the difference signal current can be represented by the following expression.

The difference signal in the diagram according to FIG. 2c, before the first time mark t _P and behind the second time mark the equilibrium of the bridge is in phase with the signal of the constant frequency generator (Fig. 2a), and between the first and second marks of equilibrium of the bridge the difference signal is in phase with the signal of the constant frequency generator. The signal from the output of the current generator is fed to the input of the phase shifting device 4, in which its phase is shifted by 90 °. This is done to ensure a phase margin of 90 ° when comparing the phases of the difference signal current and the constant frequency generator current.

The current of the difference signal with the measured phase from the output diagonal of the bridge 8 of the circuit is supplied to the input of the first amplifier 7, where it is amplified with a given coefficient. From the output of amplifier 7, the current of the difference signal enters the filter 9, where the signal is filtered from interference caused by other on-board consumers of the spacecraft. Since filter 9 is an aperiodic unit that has a time delay τ, the current of the difference signal from the output of filter 9 will have some phase shift, which is undesirable for further converting the current of the difference signal, but is taken into account when the phase shift is 90 ° in the phase shifting device 4 . Thus, the current of the difference signal from the output of the filter 9 and the current of the constant frequency signal from the output of the phase-shifting device 4 remain mutually orthogonal before the phase comparison operation. Given that during further processing of these signals, the claimed device uses information only about the state of their phase shifts, they are converted into discrete signals. For this purpose, the signal of the constant frequency generator from the output of the phase shifting device 4 and the difference signal from the output of the filter 9 are supplied to the first 5 and second 10 amplitude comparators, respectively. Amplitude 5 and 10 comparators convert an analog sinusoidal signal to a discrete one. For example, if the amplitude of the sinusoidal signal is negative, then this corresponds to a logical zero, and if the amplitude of the sinusoidal signal is positive, then this corresponds to a logical unit. Thus, in the first amplitude 5 comparator, the current of the constant frequency generator is converted into a sequence of reference pulses according to the diagram of FIG. 2d, in the second amplitude 10 comparator, the current of the difference signal is converted into the sequence of difference pulses shown in the diagram of FIG. 2d Moreover, the sequence of rectangular pulses of the difference signal is shifted relative to the sequence of rectangular reference pulses in phase by 90 °. Both sequences containing information on the phases of the input analog signals from the outputs of the amplitude 5 and 10 comparators are fed to the inputs of the phase-sensitive 6 clamp for phase comparison. The phase-sensitive 6 lock can be made in the form of a dynamic D-trigger, to the D-input of which a sequence of pulses of difference signals containing information about the phase of the difference signal is supplied, and to the counting input, a sequence of reference pulses containing information about the phase of the signal of the constant frequency generator. From the diagrams of FIG. 2d and FIG. 2d (to the equilibrium marks of the bridge circuit t _P ) it follows that the leading edge of the reference pulse corresponds to the duty cycle of the sequence of pulses of the difference signal, i.e. logical zero state. The result of phase comparison of the sequences of rectangular pulses is a logical zero state, which corresponds to the diagram of FIG. 2e. Since the phase-sensitive 6 lock is made in the form of a dynamic D-flip-flop, the result of comparing the phases along the leading edge of the pulse is recorded in trigger 6 as a logical zero and at each reference pulse of the constant-frequency generator. When leaving the ball’s coverage area, the difference impulse takes the value of a logical unit. Then, with the next reference pulse (see Fig. 2d, e), the counting pulse takes the value of a logical unit according to the diagram of FIG. 2e.

Used Books

1. "A method for measuring the parameters of three-element two-terminal circuits by frequency-independent bridges of alternating current", RF patent No. 2144196, cl. G01R 17/10, 27/02.

2. “Device for measuring electric capacity”, RF patent No. 2186402, class. G01F 27/02, 17/12, publ. 07/27/2002.

3. Balakin S.V., Dyvak A.N., Khachaturov Y. V. "A method of measuring the complex resistance of a bridge circuit with close inductive coupling and a device for its implementation." RF patent №2224261, 02.20.2004, bull. No. 5.

4. L.A. Bessonov. Theoretical foundations of electrical engineering. Ed. Higher School, Moscow - 1973, p. 149.

Claims (1)

A bridge impedance measuring device comprising an adjustable amplifier, an imbalance element, a constant frequency generator connected through a series-connected phase shifter and a first amplitude comparator to the first input of the phase-sensitive latch, the first amplifier, the first input of which is connected to the first terminal of the output diagonal of the bridge measuring transformer, the output of the first amplifier through the filter and the second amplitude comparator is connected to the second input a sensitive latch, the output of which is the output of the device, characterized in that the constant frequency generator is connected through the second amplifier and transformer to the input terminals of the input diagonal of the bridge measuring transformer, the midpoints of which are connected and grounded, the second input of the first amplifier is connected to the second terminal of the output diagonal of the bridge measuring a transformer, and a resistor is connected between the first input of the first amplifier and the midpoint of the bridge measuring transformer, and uliruemy amplifier and imbalance element connected in series and connected between the second input of the first amplifier and the mid-point of the bridge measuring transformer.

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