SU949544A1 - Inductivity measuring device - Google Patents

Description

The invention relates to a measurement technique and "can be used as an analog-digital converter in the construction of information-measuring systems, automatic control systems, where inductive sensors are used to measure and control parameters of physical quantities, as well as to measure the inductance of coils production and use in radio electronic equipment.

A device for measuring inductance is known, which contains an inductance measuring transducer of a tapped RL circuit in a time interval, a time interval converter connected to it in a number-pulse code, a pulse counter connected to the output of the converter in a pulse number code.

A disadvantage of this device is the large measurement error, since the measurement process does not exclude the influence on the measurement accuracy of the active resistance of the supply wires, the inductance itself, the active resistance of the keys and the power supply.

The closest to the invention according to the technical solution and the achievable results is an inductance measuring device comprising a measuring transducer of an inductance of an RL-circuit coil in a time interval with a voltage comparison unit, a time-to-pulse conversion unit

10 code, a pulse counter connected to the output of the converter in the pulse number code, and a digital recorder connected to the output of the pulse counter 23.

15

However, the known device does not provide high accuracy of measurement due to the error due to the influence of parasitic active resistances connected in series with the inductor (active resistance of the communication line, the actual coil, internal resistance of the keys, power supply).

The purpose of the invention is to improve the measurement accuracy.

The goal is achieved by the fact that in a device for measuring inductance, containing a voltage divider from two resistors, clamps for

3Q connecting the measured inductance coil, one of which is connected to the reference resistor, the voltage comparison unit, one input of which is connected to the middle output of the voltage divider, the other input connected to one voltage for connecting the measurable inductance coil, time interval conversion unit The number-pulse code, one input of which is connected to the output of the voltage comparison unit, a pulse counter, a digital recorder and a control unit, is equipped with one additional resistor connected in series a brazing resistor and one key connected in parallel with the sample resistor, another additional resistor connected to the first terminal, share the voltage and another clamp to switch on the measured inductance, another additional key, the first output of which is connected to another terminal to connect the measured: inductance, the second output is connected to another output of the additional resistor and the Splitter, a second voltage comparison unit, the third and fourth keys, a second pulse counter, a block The multiplier, dividing unit, reversible counter, the first bypass of the second block I of the comparison is connected to the common output of the voltage divider and another additional resistor, and the second input with the other input of the first comparison unit, the output of the second conversion unit the time intervals in the pulse code, and the output of the last is connected to the first inputs of the third, fourth, and reversible counter, the outputs of the third and fourth kgochey are connected to the input of the counters, pulses / outputs GOVERNMENTAL, svhodami unit multiplying you move the latter and exit down counter respectively connected to the input of the block division, the output of which is connected to the input of the digital recorder, and a control unit connected with the control key input, the control input of the reversible account snip, dividing and multiplying units. The drawing shows a block diagram of the device. The device contains a unit 1 measuring transducer inductance of the RL-circuit coil in the time interval with inductance coil 2 connected in series with an additional resistor 3 and reference resistor 4, in parallel with which key 5 with switch 6, parsed RL-circuit, voltage divider, which consists of three resistors 7-9, blocks 10, 11 of the voltage comparison, one of the inputs of which is connected to the point a RL circuit, another input of the comparison unit 10 is connected to the point b of the voltage divider, and block 11 to point in divides L voltage) converting section 12 in the time slot number of a pulse code to the inputs of which are connected the outputs of blocks 10 and 11 are comparative; reversible counter 13 / keys 14 and 15, the inputs of which are connected to the output of the time interval conversion unit 12 to the pulse number counter 16 and 17 pulses, the inputs of which are connected to the outputs of keys 14 and 15, respectively; a multiplier 18, the inputs of which are connected to the output of the counters 16 and 17 pulses; block 19, the inputs of which are connected to the output of the reversible pulse counter 13 and the output of multiplication unit 18) digital recorder 20, its input connected to the output of division block 19, and control unit 21. The device works as follows. In the initial state, the keys 5 and 14 are closed, the other keys are open. In order to conduct one measurement cycle, the signal 6 of the control unit 21 is used to close the switch 6. The exponentially varying voltage at point a of the RL-circuit is fed to the input of blocks 10 and 11 of the voltage comparison. At the other input of these blocks, fixed voltages are applied from points b and to the voltage divider, and according to the moment of equality of the voltages at the inputs of the comparison blocks 10 and 11, a time interval is formed from which the known value of the time converter in the 1-pulse code is formed first series of measuring pulses. The signal in the pulse code from the output of block 12 enters the reversible counter 13 and through the public key 14 into the counter 16 pulses, where it is stored. Upon completion of the formation of the first series of measuring pulses according to a predetermined program from the control unit 21, a signal is received to open the keys 5, 6 and 14 and to close the switch 15. The RL circuit is charged, after which the switch 6 and the reversing switch closes from the control unit 21 the counter 13 is switched to subtraction mode. In the described manner, the generated signal in the pulse code from block 12 is fed to the input of a reversible counter 13, which is included in the subtraction mode, and through the key 15 to the input of the pulse counter 17, where it is stored. Upon completion of the formation of the second series of measurement pulses, a command from control unit 21 turns on multiplication unit 18, to the inputs of which the signals in the pulse code come from the outputs of counters 16 and 17. After multiplying the contents of counters 16 and 17, the command from control unit 21 turns on dividing unit 19, to the inputs of which the signal in the pulse number comes from multiplication unit 19 and reversing counter 13. When the division is completed, one measurement cycle ends and the result is displayed on the digital display of recorder 20 measurements in units of measurable inductance in digital form.

Thus, due to the use of additional switches and a block, the result of measuring the inductance does not depend on the active resistance of the communication line, the actual keys of the internal resistance of the keys and the power source, and consequently, the accuracy of the measurement is improved.

Claims (3)

Invention Formula A device for measuring inductance, which contains a voltage divider of two resistors, clamps for connecting a measuring inductor, one of which is connected to a sample resistor, a voltage comparison unit, one input of which is connected to the middle output of a voltage divider, the other input is connected to A smart terminal for connecting a measuring inductor, a time interval conversion unit to a number-pulse code, one input of which is connected to the output of a voltage comparison unit, a pulse counter, digitally recorder, and a control unit, characterized in that, in order to increase the measuring accuracy, it is provided with one further resistor connected in series with a resistor model and one key connected in parallel with the reference resistor, another additional resistor connected to the first output of the voltage divider, and another terminal for connecting the measured inductance with another additional key, the first output of which is connected to another terminal for connecting the measured inductance, the second output is connected to another output additional resistor and voltage divider;,; the second voltage comparison block, the third and fourth keys, the second pulse counter, a block multiply; nor, a division block, a reversible counter The first input of the second comparison unit is connected to the common output of a voltage divider and another additional resistor, and the second input is connected to another input of the first comparison unit, the output of the second one is compared to another input of the time interval converter in the pulse code, and the output of the latter is connected to the first inputs of the third and fourth keys and the reversible counter, the outputs of the third and fourth keys are connected to the inputs of the pulse counters, the outputs connected to the inputs of the multiplication unit, the output after The one and the output of the reversible counter are respectively connected to the inputs of the division unit, the output of which is connected to the input of the digital recorder, and the control unit is connected to the control of the dynamic inputs of the keys that controls the input of the reverse counter, division and multiplication units. Sources of information taken into account in the examination 1. Instruments and control systems No. 2, 1969, pp. 41-43. 2. G-Ya. Mirsky, Radio-electronic measurements, 3., M., 1975, p. 499 505 (prototype).