SU1548658A1

SU1548658A1 - Capacitive displacement transducer

Info

Publication number: SU1548658A1
Application number: SU884433056A
Authority: SU
Inventors: Евгений Николаевич Васильченко
Original assignee: Предприятие П/Я В-2867
Priority date: 1988-05-30
Filing date: 1988-05-30
Publication date: 1990-03-07

Abstract

Изобретение относитс к измерительной технике и может быть использовано дл бесконтактного измерени линейных перемещений. С целью повышени точности за счет увеличени линейности и помехоустойчивости преобразовани в него введены конденсаторы 10, 11, 12, шина 13 нулевого потенциала, двухобмоточный дроссель 14, диоды 5, 19. Генератор 6 выполнен с трем гальванически изолированными выходами, а датчик 1 имеет дополнительный электрод 4, экранирующий измерительный электрод 2. Блок 15 сравнени , управл генератором 6, поддерживает уровень тока через измерительный электрод 2 на заданном уровне. Ток, протекающий через сравнивающие емкости 7, 8 и блок 9 выпр млени , линейно св зан с перемещением. В преобразователе устранено вли ние побочных емкостей и краевых эффектов датчика 1 на линейность прекобразовани воздействи помех на измерительный электрод 2. 1 ил.The invention relates to a measurement technique and can be used for non-contact measurement of linear displacements. In order to increase accuracy by increasing the linearity and noise immunity of the conversion, capacitors 10, 11, 12 are introduced into it, a zero potential bus 13, a two-winding choke 14, diodes 5, 19. The generator 6 is made with three galvanically isolated outputs, and the sensor 1 has an additional electrode 4, the shielding measuring electrode 2. The comparison unit 15, controlled by the generator 6, maintains the current level through the measuring electrode 2 at a predetermined level. The current flowing through the comparison capacitances 7, 8 and rectifier unit 9 is linearly related to movement. The transducer eliminates the effect of side capacitances and edge effects of sensor 1 on the linearity of the pre-formation of interference effects on the measuring electrode 2. 1 sludge.

Description

преобразовател .converter

Преобразователь содержит датчик 1 с измерительными электродами 2 и 3 и дополнительным электродом 4, диод 5, генератор 6 переменного тока, конденсаторы 7 и 8, блок 9 выпр млени , конденсаторы 10-12, шилу 13 нулевого потенциала, двухобмоточный дроссель 14, блок 15 сравнени , резисторы 16 и 17, источник 18 опорного напр жени , диод 19.The converter contains a sensor 1 with measuring electrodes 2 and 3 and an additional electrode 4, a diode 5, an alternator 6, capacitors 7 and 8, rectifying unit 9, capacitors 10-12, potential zero 13, double-wound choke 14, comparison unit 15 , resistors 16 and 17, voltage source 18, diode 19.

Генератор 6 содержит три пары выводов , кажда из которых вл етс выходом генератора 6, гальванически не св занным с другими выходами, и вход управлени амплитудой, к которому подключен выход.блока 15 сравнени .The generator 6 contains three pairs of outputs, each of which is the output of the generator 6, which is not galvanically connected to other outputs, and the amplitude control input to which the output unit 15 of the comparison is connected.

Преобразователь работает следующим образом.The Converter operates as follows.

Высокочастотный ток генератора 6, проход через измерительный электрод 2 датчика 1, выпр мл етс диодами 5 и 19. Переменна составл юща тока заработу преобразовател не вли ют. Синфазные высокочастотные токи, проход через идентичные обмотки дрос сел 14, включенные согласно, взаим15 но компенсируютс . Противофазные выпр мленные токи проход т через обмотки дроссел 14 и поступают на вход блока 15 сравнени .The high frequency current of the generator 6, the passage through the measuring electrode 2 of the sensor 1, is rectified by diodes 5 and 19. The alternating current component of the converter is not affected. The common-mode high-frequency currents passing through identical windings of the village Bros 14, which are connected according to, are mutually compensated. Anti-phase rectified currents pass through the windings of the throttles 14 and are fed to the input of the comparison unit 15.

Использование предлагаемого ем20 костного преобразовател позвол ет более чем на пор док уменьшить погрешность измерений за счет исключе1- ни монтажных емкостей и краевых эффектов в емкости датчике 1, вли 25 ющих на линейность преобразовани , увеличени помехоустойчивости преобразовател , а также обеспечит возможность измерени перемещени объектов , подключенных к шине нулевогоThe use of the proposed bone converter 20 allows, by more than an order of magnitude, to reduce measurement errors by eliminating mounting capacitances and edge effects in the capacitance of sensor 1, which affect the linearity of the transducer, increase the noise immunity of the transducer, and also make it possible to measure the movement of objects connected to bus zero

30 потенциала.30 potential.

Claims

Invention Formula

The capacitive transducer is connected to the bus 13 by capacitors 10 cheeky, containing a sensor, a generator, and I. Constant (rectified) alternating current, the first and second

the operation of the converter is not affected. The common-mode high-frequency currents passing through identical windings of the throttles 14, connected according to, are mutually compensated. Anti-phase rectified currents pass through the windings of the throttles 14 and are fed to the input of the comparison unit 15.

Using the proposed capacitive converter allows reducing the measurement error by more than an order of magnitude by eliminating mounting capacitances and edge effects in the capacitance of sensor 1, affecting the linearity of the conversion, increasing the noise immunity of the converter, and also provides the ability to measure the movement of objects connected to the bus. zero

potential.

Invention Formula

The opposing polarity currents flow through the inductor 14 to the differential input of the comparison unit 15 and are compared in magnitude with the currents flowing through the resistors 16 and 17 connected to the reference voltage source 18. Block 15 comparison, controlling amplitude or frequency

or at the same time, the amplitude and frequency to the control input of the generator, the alternating output voltage of generator 6, maintains the magnitude of the rectified currents at a predetermined level, while the amount of current flowing through the matching capacitances 7 and 8 and rectifier unit 9 varies linearly depending on the movement being measured.

If the measuring and comparing capacitances 7 and 8 are in the same conditions, then the effect of the dielectric constant of the medium on the result of the conversion is eliminated. Additional electrode 4 is equipotential 55

alternating current, in order to improve accuracy, a zero potential bus, third, fourth and fifth capacitors, a two-winding choke and two diodes, an alternator, are made with three pairs of terminals, each of which the output of the generator, galvanically isolated from the other two outputs, and the sensor is made in the form of a first measuring electrode, and the movement is relative to the second measuring electrode.

capacitors, rectifier, comparator, two resistors and a source of voltage, the negative and positive terminals of which through respectively the first and second resistors are connected respectively to the inverting and direct inputs of the comparator, the output of which is connected

to the control input of the generator

five

perpendicular to the planes of both electrodes and an additional electrode, configured to screen the first measuring electrode from the side opposite to the second measuring electrode, which is connected to the zero bus. potential, which through the third, fourth and fifth capacitors is connected to the first terminals of the first, second and third outputs of the generator, alternating current, respectively, the second terminals of which are connected respectively to the additional electrode of the sensor, the cathode of the first diode and

the anode of the second diode, the other electrodes of which are connected to the first measuring electrode of the sensor, the second terminals of the second and third outputs of the alternator through the first and second capacitors respectively to the input of the rectifier whose output is the output of the converter, the first terminals of the second and third outputs of the generator AC, respectively, through the first and second windings of the double-winding throttles are connected respectively to the inverting and direct inputs of the comparison unit.