KR101987307B1 - Apparatus and method for measuring electrical conductivity - Google Patents

Abstract

An apparatus and method for measuring electrical conductivity are disclosed. The apparatus and method for measuring electrical conductivity of the present invention include: a waveform generator for generating a measurement signal for measuring electrical conductivity of a target material; An electrode sensor unit including a driving electrode for applying the measurement signal to a target material and a sensing electrode for sensing an electrical signal from the target material and outputting a sensing signal; A synchronous detector for detecting a phase difference between the measurement signal input from the waveform generator and the sensing signal input from the sensing electrode; A minimum reference part and a maximum reference part for receiving the measurement signal outputted from the waveform generator and setting the minimum reference value and the maximum reference value of the detection signal of the synchronous detector, respectively; And a control unit for operating the waveform generating unit and calculating the electric conductivity of the target substance when the detection signal inputted from the synchronous detector is within the reference range set at the minimum reference unit and the maximum reference unit.

Description

[0001] APPARATUS AND METHOD FOR MEASURING ELECTRICAL CONDUCTIVITY [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for measuring electrical conductivity, and more particularly, to an apparatus and method for measuring electrical conductivity using an electrode-type conductivity sensor capable of self-calibration and noise elimination.

Generally, electrical conductivity is the degree to which electrons can pass, which means the degree to which a substance or solution can carry an electric charge. This electric conductivity is represented by the reciprocal of the electrical resistivity. If the resistance of the material is R, the resistivity is ρ, the cross-sectional area is S, and the length is l, then the relation of R = (ρ x l) / S holds.

The electrical conductivity, L, is the inverse of the electrical resistivity and is therefore expressed as L = 1 / ρ = 1 / RS. Metals generally have low electrical resistance and good electrical conductivity. In addition to the concentration of ions, the electric conductivity of the electrolyte solution is affected by the distance between the electrodes, the cross-sectional area of the electrodes, the charge size of the ions, and the temperature.

The international unit of electrical conductivity is S (Siemens) / m. 1 μS / cm = 0.001 dS / m, which is 1 MΩ as a resistance value. Therefore, 0.1 dS / m = 100 k OMEGA and 10 dS / m = 100 OMEGA. There is such a correlation between the electrical conductivity and the resistance value. Using such a correlation, a conventional electric conductivity measuring apparatus measures the resistance value of a substance or a solution and measures a corresponding electric conductivity thereof.

Conventionally, two electrodes are provided in a substance or a solution to be measured. The resistance value is measured through the intensity of the current detected through the two electrodes, and the electric conductivity is measured using the resistance value. However, in the prior art, the electric conductivity measured through a medium such as water, such as boiler water, fresh water, and brine, usually has non-linearity in correlation with an electrical conversion signal.

That is, depending on the state of the electrode and the operation state of the electric circuit, the measurement may be affected by errors and electrical noise.

In addition, due to non-linearity of output characteristics, error type, electrical noise, etc., there is a high possibility of error in measuring the conductivity of medium corresponding to 0 ~ tens μS / cm such as boiler water or supercritical water, There is a problem that the method of performing the above method is very inconvenient.

Background Art [0002] As a background art of the present invention, there is a " Electrical Conductivity Measuring Apparatus ", Korean Patent Registration No. 10-1512107 (registered on Aug.

According to an aspect of the present invention, there is provided an apparatus and method for measuring electrical conductivity using an electrode-type conductivity sensor capable of self-calibration and noise elimination, .

An apparatus for measuring electrical conductivity according to an aspect of the present invention includes: a waveform generator for generating a measurement signal for measuring electrical conductivity of a target material; An electrode sensor unit including a driving electrode for applying the measurement signal to the target material and a sensing electrode for sensing an electrical signal in the target material and outputting a sensing signal; A synchronous detector for detecting a phase difference between the measurement signal input from the waveform generator and the sensing signal input from the sensing electrode; A minimum reference unit and a maximum reference unit which receive the measurement signal output from the waveform generator and set the minimum reference value and the maximum reference value of the detection signal of the synchronous detector, respectively; And a controller for operating the waveform generator and calculating the electrical conductivity of the target material when the detection signal input from the synchronous detector is within a reference range set at the minimum reference part and the maximum reference part .

The present invention further includes a reference sensor unit having a circuit corresponding to the object material and the electrode sensor unit and receiving the measurement signal and outputting a reference sensing signal, And detects an error of the electrode sensor unit based on the comparison and analysis.

The present invention may further comprise: an analog signal multiplexer for selectively switching the measurement signal generated by the waveform generator to the reference sensor unit and the driving electrode; And an analog signal distribution unit for selectively switching the reference sensing signal of the reference sensor unit and the sensing signal of the sensing electrode and providing the sensing signal to the synchronous detector.

In the present invention, the reference sensor unit may include a plurality of capacitors connected in series with a digital variable resistor controlled by the control unit.

In the present invention, the waveform generating unit may include a resonant circuit having a digital variable resistor and a capacitor controlled by the control unit.

The minimum reference unit and the maximum reference unit may include a capacitor connected in series with a digital variable resistor controlled by the control unit to output an electrical signal corresponding to a minimum reference value and a maximum reference value of a reference range of a detection signal, .

In the present invention, the control unit performs an initialization step of initializing the waveform generator, setting a reference resistance value of the reference sensor unit, and setting resistance values of the lowest reference unit and the highest reference unit, respectively, And stores the set setting data.

In the present invention, when the control unit detects an error of the electrode sensor unit through the reference sensor unit or when the detection signal for the measured target substance is less than the minimum reference value or exceeds the maximum reference value, And further comprising:

In the present invention, the electrode sensor unit may further include a temperature sensor for measuring a temperature of the target material, wherein the controller receives the temperature of the target material from the temperature sensor and performs a temperature compensation process.

According to another aspect of the present invention, there is provided an electrical conductivity measuring method comprising: generating a measurement signal for measuring electrical conductivity of a target material by operating a waveform generator; Applying the measurement signal to the target material through a driving electrode of the electrode sensor unit, sensing an electrical signal from the target material through the sensing electrode, and outputting a sensing signal; Detecting a phase difference between a measurement signal input from the waveform generator and a sensing signal input from the sensing electrode; Determining whether a detection signal input from the synchronous detector is included in a reference range set at a minimum reference portion and a maximum reference portion; And calculating the electrical conductivity when the detection signal is within the reference range.

According to the present invention, there is provided a method of detecting a target object, comprising the steps of: receiving a measurement signal from a reference sensor unit having a circuit corresponding to the target material and the electrode sensor unit; And a step of comparing the reference sensing signal with the detection signal and detecting an error of the electrode sensor unit based on the comparison signal.

The analog signal multiplexing unit selectively switching the measurement signal generated by the waveform generator to the reference sensor unit and the driving electrode to provide the analog signal multiplexing unit; And an analog signal distribution unit selectively switching a reference sensing signal of the reference sensor unit and a sensing signal of the sensing electrode and providing the sensing signal to the synchronous detector.

In the step of generating the measurement signal according to the present invention, the waveform generating unit may include a resonant circuit including a digital variable resistor and a capacitor controlled by the control unit.

The minimum reference part and the maximum reference part may include a capacitor connected in series with a digital variable resistor controlled by the control part so that the minimum reference value and the maximum reference value of the reference range of the detection signal, And outputs an electrical signal corresponding to the reference value.

In the present invention, the reference sensor unit may include a plurality of capacitors connected in series with a digital variable resistor controlled by the control unit.

The present invention further includes an initialization step of initializing the waveform generator when the control unit is powered on, setting a reference resistance value of the reference sensor unit, and setting resistance values of the lowest reference unit and the highest reference unit, respectively And the control unit stores the set data set in the initializing step.

In the present invention, when the control unit detects an error of the electrode sensor unit through the output unit or when the detection signal for the measured target substance is less than the minimum reference value or exceeds the maximum reference value, or detects an error of the electrode sensor unit through the reference sensor unit, The method comprising the steps of:

In the present invention, the electrode sensor unit may further include a temperature sensor for measuring a temperature of the target material, wherein the controller receives the temperature of the target material from the temperature sensor and performs a temperature compensation process .

The apparatus and method for measuring electrical conductivity according to an embodiment of the present invention measure the electrical conductivity using an electrode type conductivity sensor capable of self calibration and noise elimination, It is convenient to check the operation status, and the automatic output range is adjusted according to the measurement range setting, thereby improving convenience.

In addition, the diagnosis of faults and the correction of the sensor measured values are automatically performed at an arbitrary time, so that passive fault diagnosis and the number of operation state operations for the sensors are reduced.

In addition, it is possible to acquire the measurement value with less error rate by enhancing the noise filtering function in the surrounding environment, and to obtain the reliable measurement value by confirming the fault condition, malfunctioning, etc., and the high resolution analog- It is possible to measure accurately by applying.

In addition, the apparatus and method for measuring electrical conductivity according to an embodiment of the present invention can be applied to a new industrial environment such as IoT by adding a function of an output unit.

1 is a circuit diagram schematically showing an electric conductivity measuring apparatus according to an embodiment of the present invention.
2 is a circuit diagram showing a waveform generator of an electric conductivity measuring apparatus according to an embodiment of the present invention.
3 is a circuit diagram illustrating a reference sensor unit of an electric conductivity measuring apparatus according to an embodiment of the present invention.
4 is a circuit diagram showing a minimum reference part and a maximum reference part of the electrical conductivity measuring apparatus according to an embodiment of the present invention.
5 is a flowchart illustrating a method of measuring electrical conductivity according to an embodiment of the present invention.

Hereinafter, an apparatus and method for measuring electrical conductivity according to an embodiment of the present invention will be described with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation.

In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

FIG. 1 is a circuit diagram schematically showing an electric conductivity measuring apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a waveform generating unit of an electric conductivity measuring apparatus according to an embodiment of the present invention, 3 is a circuit diagram for explaining a reference sensor unit of an electric conductivity measuring apparatus according to an embodiment of the present invention, and FIG. 4 is a view showing a minimum reference unit and a highest reference unit of the electric conductivity measuring apparatus according to an embodiment of the present invention. The electric conductivity measuring apparatus will be described with reference to FIG.

1, an electric conductivity measuring apparatus according to an embodiment of the present invention includes an electrode sensor unit 1, 6, 7 including a driving electrode 1, a sensing electrode 6, and a temperature sensor 16, 16, the analog signal multiplexing unit 2, the waveform generating unit 3, the reference sensor unit 4, the analog signal distributing unit 5, the synchronous detector 7, the first low pass signal filter 8, The minimum reference section 14, the highest reference section 15, the signal detecting section 17, the second low-pass signal filter 18, the output section 21, the current output section 22, the communication output section 23, And a key input unit 24.

The electrode sensor unit (1, 6, 16) measures the electrical conductivity and temperature of the substance (target substance) to be measured. The electrode sensor units 1, 6, and 16 include a driving electrode 1 for applying a measurement signal to a target material, and a sensing electrode 6 for sensing an electrical signal from the target material and outputting a sensing signal. At this time, the driving electrode 1 is a driving electrode connected to the waveform generating unit 3, and the state of the electric signal generated in the driving electrode 1 is changed through the intermediate medium. Can be sensed by the sensing electrode 6, which is a sensing electrode.

The temperature sensor 16 of the electrode sensor unit 1, 6, 16 measures the temperature of the target substance. At this time, the temperature sensor 16 may be constituted by a resistance type temperature sensor (RTD).

The waveform generator 3 generates a measurement signal for measuring the electrical conductivity of the target material. That is, the waveform generating unit 3 can output an AC signal of a specific frequency to the electrode sensor units 1, 6, 16 by varying the frequency. The waveform generating unit 3 may be constituted by a resonant circuit including a digital variable resistor and a capacitor controlled by the control unit 9, as shown in FIG. That is, the waveform generator 3 can automatically change the frequency according to the control of the control unit 9.

On the other hand, the waveform generator 3 is not limited to the example of FIG. 2, and various frequency generators for generating a specific frequency can be applied.

At this time, the waveform generated in the waveform generating unit 3 is transmitted to the driving electrode 1, and the electrical signal output from the driving electrode 1 changes in accordance with the state of the medium (target material) of the liquid component, And is input to the sensing electrode 6. That is, the waveform generator 3 can output a specific frequency to automatically detect the conductivity and electric / electronic characteristics of the medium of the liquid component to be measured, and automatically generate the frequency through the controller 9, 9 may be input through the input of the key input unit 24 located outside.

In other words, a sinusoidal waveform of a specific frequency and amplitude is generated according to the combination of the resistor and the capacitor assembled in the waveform generating unit 3, and the generated sinusoidal waveform causes a current to flow through the driving electrode 1 to the medium, Depending on the conductivity of the medium, electrons flow to the sensing electrode (6). This can be attributed to the resistance of the medium and the difference in the electrostatic capacitive resistance component. Therefore, depending on the state of the medium, a phase change occurs with respect to the input sinusoidal waveform. The conductivity of the medium, which can be measured by electrodes, is usually in the range of 0 μS / cm to 10,000 μS / cm for boiler water, fresh water, salt water, etc., and the medium may be contained or flowed in a container of water tank type or piping type.

On the other hand, in the above, the frequency phase is changed in accordance with the change of the electrical resistance characteristic, and the signal is changed to the electric voltage signal in the synchronous detector 7. At this time, the synchronous detector 7 detects a phase difference between the measurement signal input from the waveform generator 3 and the sensing signal input from the sensing electrode 6. That is, the synchronous detector 7 can detect the phase difference between the clock (Clock) input from the waveform generator 3 and the AC signal input from the driving electrode 1 and change it to a voltage. The voltage signal output from the synchronous detector 7 may be filtered through the first low pass filter 8 and transmitted to the controller 9. At this time, the first low pass signal filter 8 may be configured as a low pass filter.

The reference sensor unit 4 includes a circuit corresponding to the object material and the electrode sensor units 1, 6 and 16, and receives a measurement signal and outputs a reference sensing signal. In other words, the reference sensor unit 4 realizes the correlation between the driving electrode 1 and the sensing electrode 6 in a circuit in accordance with the state of the medium (target material) And a virtual sensor which defines the correlation between the resistor 6 and the capacitor 6 as a relationship between the resistor and the capacitor.

3, the reference sensor unit 4 may include a plurality of capacitors connected in series with the digital variable resistor controlled by the controller 9 in parallel. In addition, the reference sensor unit 4, the analog signal multiplexing unit 2, and the analog signal distribution unit 5 interlock with each other so that the operation state of the sensor, the failure or the like can be confirmed.

That is, the analog signal multiplexing unit 2 can selectively provide a measurement signal generated in the waveform generating unit 3 to the reference sensor unit 4 and the drive electrode 1, and provide the same. The analog signal multiplexing unit 2 can control the operation of the analog signal multiplexing unit 2 by the control unit 9. The analog signal multiplexing unit 2 multiplexes the measurement signal generated by the waveform generating unit 3 with the reference sensor unit 4 and the driving electrode 1 for a predetermined time However, the present invention is not limited thereto. The analog signal distribution unit 5 may selectively switch the reference sensing signal of the reference sensor unit 4 and the sensing signal of the sensing electrode 6 and provide the sensing signal to the synchronous detector 7. The operation of the analog signal distribution unit 5 can also be controlled by the control unit 9 and the reference sensing signal of the reference sensor unit 4 and the sensing signal of the sensing electrode 6 are switched at predetermined time intervals, 7, but is not limited thereto.

At this time, the control unit 9 receives the reference sensing signal, compares it with the detection signal, and can detect an error of the electrode sensor unit 1, 6, 16 based on the comparison signal.

On the other hand, in this embodiment, as shown in FIG. 4, it includes a minimum reference portion 14 and a maximum reference portion 15. The minimum reference portion 14 and the maximum reference portion 15 can receive the measurement signal output from the waveform generator 3 and set the minimum reference value and the maximum reference value of the detection signal of the synchronous detector 7, respectively. In other words, the minimum reference portion 14 and the highest reference portion 15 can change the magnitude of the variable resistor to set the minimum and maximum measurement ranges for the sensing signal of the sensing electrode 6, respectively. The control portion 9 And a capacitor connected in series with a digital variable resistor controlled by the synchronous detector 7 to output an electrical signal corresponding to the lowest reference value and the highest reference value of the reference range of the detection signal of the synchronous detector 7, have. That is, the control unit 9 can adjust the variable resistor to adjust the automatic output range according to the reference range setting. The minimum reference section 14 and the maximum reference section 15 provide reference data for controlling the control section 9 for a current output of 4 mA to 20 mA or 0 mA to 20 mA, 6 and 16, that is, the sensing electrode 6, by analyzing the input waveform through the reference portion 14 and the highest reference portion 15, Can be generated and provided.

In other words, the control unit 9 determines whether or not the detection signal input from the synchronous detector 7 is included in the reference range set at the minimum reference unit 14 and the highest reference unit 15 and is included in the reference range The electrical conductivity of the target material can be calculated. That is, the control unit 9 sets the reference range by adjusting the variable resistances of the minimum reference unit 14 and the highest reference unit 15, and operates the waveform generating unit 3 to set the minimum reference unit 14 and the maximum reference The controller 15 can perform the data filtering control according to the electrical signal input from the controller 15 to calculate the electrical conductivity.

On the other hand, since the electric conductivity changes depending on the temperature, it is necessary to compensate for the deviation due to the temperature influence. For this purpose, a temperature sensor 16 is provided to measure the temperature of the target material, and the reference temperature for temperature compensation may be, for example, 25 ° C. At this time, the temperature data of the target substance outputted from the temperature sensor 16 is transmitted to the control unit 9 through the signal detecting unit 17 and the second low-pass signal filter 18. Here, the second low pass signal filter 18 may be a low pass filter. That is, the control unit 9 can receive the temperature of the target material from the temperature sensor 16 and perform the temperature compensation process. At this time, the controller 9 may compensate the digital value corresponding to the measured electrical conductivity by applying the temperature value measured by the temperature sensor 16, and may calculate the digital value of the final temperature compensated electrical conductivity It can be converted to electrical conductivity value.

The control unit 9 includes first, second, third and fourth A / D signal converting units 10, 11, 12 and 13, a main processing unit 19 and an output interlocking unit 20, And the output state.

At this time, the first A / D signal converting unit 10 converts the analog voltage signal for the final electrical conductivity inputted from the first low pass signal filter 8 into a digital signal.

The second and third A / D signal conversion units 11 and 12 change the electrical signals input from the minimum reference unit 14 and the highest reference unit 15 to digital values, The unit 13 changes the temperature data input from the second low-pass signal filter 18 to a digital value.

Here, the first, second, third, and fourth A / D signal converters 10, 11, 12, and 13 may be configured as high-resolution analog-digital signal converters (A / D converters) of 16 bits or more.

The main processing unit 19 may be a main processing unit (MPU) for processing control of the input signal and the output signal in accordance with the program stored in the control unit 9. [

The output interlocking unit 20 is built in the control unit 9 so that the signal processed by the main processing unit 19 is linked with the output devices 21, 22, and 23 according to a program.

That is, the control unit 9 may be a microprocessor including a plurality of control input / output terminals or a combination circuit of devices including the same function.

The control unit 9 operates the waveform generating unit 3 so that a measurement signal for measuring the electric conductivity of the target material is generated in the waveform generating unit 3 and is transmitted to the driving electrode 1. [ The control unit 9 receives the detection signal from the synchronous detector 7 that detects the phase difference between the measurement signal input from the waveform generator 3 and the sensing signal input from the sensing electrode 6, Is included in the reference range set at the lowest reference portion 14 and the highest reference portion 15. When the detection signal is within the reference range, the electrical conductivity of the target substance can be calculated. If the detection signal is out of the reference range, the alarm or display indication can be output. The control unit 9 receives the reference sensing signal of the reference sensor unit 4, compares and analyzes the degree of change of the reference sensing signal, and can correct an output value corresponding to the detection signal based on the comparison.

More specifically, when power is applied, the control unit 9 performs an initialization operation of an input / output function, an internal variable, and a memory in accordance with a built-in program.

That is, the controller 9 initializes the waveform generator 3 when the power is applied, sets the reference resistance of the reference sensor unit 4, and sets the resistance of the minimum reference unit 14 and the highest reference unit 15 And an initialization step for setting the respective values. The control unit 9 can store the setting data set in the initialization step in a nonvolatile memory device (not shown) inside the control unit 9. [

The control unit 9 sequentially receives the output states of the reference sensor unit 4, the analog signal multiplexing unit 2, and the analog signal distribution unit 5 at the initialization step after power on and the set time period, And then stores the result in the nonvolatile memory device. At this time, the controller 9 can perform the determination of the failure of the electric conductivity sensor operation and the correction of the output value error based on the comparative analysis data. In the above description, the control unit 9 sequentially receives the output states of the reference sensor unit 4, the analog signal multiplexing unit 2, and the analog signal distribution unit 5 every set time period. However, Do not.

Next, the control unit 9 calculates the temperature sensing values of the electrode sensor units 1, 6, and 16 based on the output signals of the minimum reference unit 14 and the highest reference unit 15, Temperature compensation and data filtering control can be performed.

If the detection signal for the target substance is less than the minimum reference value or exceeds the maximum reference value or if the error of the electrode sensor units 1, 6, 16 is detected through the reference sensor unit 4, An alarm can be generated or displayed on the display unit 21.

In addition, the control unit 9 may convert the temperature compensation and data filtering control results into units corresponding to the conductivity or salinity, and other user's environment, and display them on the output unit 21 as temperature.

At this time, the output unit 21 may include all means for outputting the control result of the control unit 9, such as a color liquid crystal display, an external display, and an alarm generating unit.

In the present embodiment, the current output unit 22 and the communication output unit 23 may further include the measurement result and the temperature converted into a specific unit by the current output unit 22 from 4 mA to 20 mA, 20mA or the like and can be output by the communication output unit 23 in a specific manner such as CAN, RS232, RS485, Bluetooth, or Ethernet.

A digital variable resistor is provided in the reference sensor unit 4, the analog signal multiplexing unit 2, the analog signal distribution unit 5, the minimum reference unit 14 and the maximum reference unit 15, 9, and may be changed according to the input of the key input unit 24 or the procedure of the program built in the control unit 9. [ Here, the key input unit 24 is located outside and can be input by the user, and the form is not limited.

FIG. 5 is a flow chart for explaining a method of measuring electrical conductivity according to an embodiment of the present invention, and a method of measuring electrical conductivity will be described with reference to FIG.

As shown in FIG. 5, in the electric conductivity measurement method according to an embodiment of the present invention, when the controller 9 is powered on, an initialization step is performed (S10).

The control unit 9 initializes the waveform generating unit 3 when the power is applied and sets the reference resistance value of the reference sensor unit 4 and sets the resistance values of the minimum reference unit 14 and the highest reference unit 15 as You can perform an initialization step that sets each one. The control unit 9 can store the setting data set in the initialization step in a nonvolatile memory device (not shown) inside the control unit 9. [

Next, the control unit 9 receives the detection signal from the synchronous detector 7 (S20).

The control unit 9 operates the waveform generating unit 3 so that a measurement signal for measuring the electrical conductivity of the target material is generated in the waveform generating unit 3 and is transmitted to the driving electrode 1. [ The control unit 9 receives a detection signal from the synchronous detector 7 that detects a phase difference between the measurement signal input from the waveform generator 3 and the sensing signal input from the sensing electrode 6.

At this time, the waveform generated in the waveform generating unit 3 is transmitted to the driving electrode 1, and the electrical signal output from the driving electrode 1 changes in accordance with the state of the medium (target material) of the liquid component, And is input to the sensing electrode 6. That is, the waveform generator 3 can output a specific frequency to automatically detect the conductivity and electric / electronic characteristics of the medium of the liquid component to be measured, and automatically generate the frequency through the controller 9, 9 may be input through the input of the key input unit 24 located outside.

Then, the control unit 9 receives the electrical signals of the minimum reference unit 14 and the highest reference unit 15 and performs a comparison process (S30).

The minimum reference portion 14 and the maximum reference portion 15 can receive the measurement signal output from the waveform generator 3 and set the minimum reference value and the maximum reference value of the detection signal of the synchronous detector 7, respectively. In other words, the minimum reference portion 14 and the highest reference portion 15 can change the magnitude of the variable resistor to set the minimum and maximum measurement ranges for the sensing signal of the sensing electrode 6, respectively. The control portion 9 And a capacitor connected in series with a digital variable resistor controlled by the synchronous detector 7 to output an electrical signal corresponding to the lowest reference value and the highest reference value of the reference range of the detection signal of the synchronous detector 7, have. That is, the control unit 9 determines whether or not the detection signal input from the synchronous detector 7 is included in the reference range set at the minimum reference unit 14 and the highest reference unit 15, The electrical conductivity of the material can be calculated. Therefore, the control unit 9 sets the reference range by adjusting the variable resistances of the minimum reference unit 14 and the highest reference unit 15, and operates the waveform generating unit 3 to adjust the minimum reference unit 14 and the maximum reference The controller 15 can perform the data filtering control according to the electrical signal input from the controller 15 to calculate the electrical conductivity.

At this time, the sensing signal input in accordance with the electrical conductivity of the target material and the detection signal of the waveform generator 3 are input to the synchronous detector 7 and converted into a voltage signal proportional to the phase difference, and the first low- The digital signal can be input to the A / D signal conversion unit 10 incorporated in the control unit 9 and converted into digital data. In addition, the converted digital data can be subjected to software filtering processing by separate program processing.

Then, the control unit 9 confirms the reference sensing signal of the reference sensor unit 4 (S40).

Here, the reference sensor unit 4 includes a circuit corresponding to the object material and the electrode sensor units 1, 6, and 16, and receives a measurement signal and outputs a reference sensing signal. In other words, the reference sensor unit 4 realizes the correlation between the driving electrode 1 and the sensing electrode 6 in a circuit in accordance with the state of the medium (target material) And a virtual sensor which defines the correlation between the resistor 6 and the capacitor 6 as a relationship between the resistor and the capacitor.

At this time, the reference sensor unit 4 interlocks with the analog signal multiplexing unit 2 and the analog signal distribution unit 5 so as to check the operation state and the failure of the sensor.

Here, the analog signal multiplexing unit 2 can selectively provide the measurement signal generated in the waveform generating unit 3 to the reference sensor unit 4 and the drive electrode 1, and provide the same. The analog signal multiplexing unit 2 can control the operation of the analog signal multiplexing unit 2 by the control unit 9. The analog signal multiplexing unit 2 multiplexes the measurement signal generated by the waveform generating unit 3 with the reference sensor unit 4 and the driving electrode 1 for a predetermined time However, the present invention is not limited thereto. The analog signal distribution unit 5 may selectively switch the reference sensing signal of the reference sensor unit 4 and the sensing signal of the sensing electrode 6 and provide the sensing signal to the synchronous detector 7. The operation of the analog signal distribution unit 5 can also be controlled by the control unit 9 and the reference sensing signal of the reference sensor unit 4 and the sensing signal of the sensing electrode 6 are switched at predetermined time intervals, 7, but is not limited thereto.

That is, the control unit 9 receives the reference sensing signal, compares the reference sensing signal with the detection signal, and detects errors of the electrode sensor units 1, 6, and 16 based on the reference sensing signal.

Next, the control unit 9 receives temperature measurement values from the temperature sensors 16 of the electrode sensor units 1, 6, and 16 (S50).

At this time, the resistance change of the temperature sensor 16 is converted into a voltage signal, which is also input to the A / D signal conversion unit 13 incorporated in the control unit 9, converted into digital data, The firmware filtering process can be performed.

That is, the control unit 9 performs a temperature compensation process reflecting the measured temperature (S60).

The control unit 9 may compensate the digital value corresponding to the measured electrical conductivity by applying the measured temperature value. At this time, the digital value of the final temperature compensated electric conductivity can be converted into the actual electric conductivity value.

At this time, based on the electrical signals output from the minimum reference part 14 and the highest reference part 15, the temperature measurement value of the temperature sensor 16, and the setting data set at the initialization step, Filtration control can be performed. That is, the control unit 9 stores the result of comparing and analyzing the degree of change of the reference sensing signal in step S40, and can correct the output value corresponding to the detection signal based on the comparison result.

On the other hand, the control unit 9 outputs an alarm or display for the reference range or error detection (S70), displays the measurement result (S80), and outputs current or communication (S90).

At this time, when the detection signal for the target substance is less than the minimum reference value or exceeds the maximum reference value, or when the error of the electrode sensor units 1, 6, 16 is detected through the reference sensor unit 4, An alarm can be generated or displayed on the display unit 21.

In addition, the controller 9 may convert the results of the temperature compensation and the data filtration control into a unit according to the conductivity or saltiness, and other application environments of the user, and display them on the output unit 21.

Further, the converted result value can be output to the outside via the communication device (not shown) or the current output unit 22 built in the control unit 9. [

As described above, the apparatus and method for measuring electrical conductivity according to an embodiment of the present invention measure electrical conductivity using an electrode-type conductivity sensor capable of self-calibration and noise elimination, It is convenient to check the operation status of the apparatus and the automatic output range is adjusted according to the measurement range setting, thereby improving convenience.

In addition, the diagnosis of faults and the correction of the sensor measured values are automatically performed at an arbitrary time, so that passive fault diagnosis and the number of operation state operations for the sensors are reduced.

In addition, it is possible to acquire the measurement value with less error rate by enhancing the noise filtering function in the surrounding environment, and to obtain the reliable measurement value by confirming the fault condition, malfunctioning, etc., and the high resolution analog- It is possible to measure accurately by applying.

In addition, the apparatus and method for measuring electrical conductivity according to an embodiment of the present invention can be applied to a new industrial environment such as IoT by adding a function of an output unit.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand.

Accordingly, the true scope of the present invention should be determined by the following claims.

1: driving electrode 2: analog signal multiplexing unit
3: Waveform generating unit 4: Reference sensor unit
5: analog signal distributor 6: sensing electrode
7: synchronous detector 8: first low pass signal filter
9: control unit 10: first A / D signal conversion unit
11: second A / D signal converting section 12: third A / D signal converting section
13: fourth A / D signal converting section 14: lowest reference section
15: highest reference part 16: temperature sensor
17: Signal detection unit 18: Second low pass filter
19: main processor 20: output interlocking part
21: output section 22: current output section
23: communication output unit 24: key input unit

Claims (18)

A waveform generator for generating a measurement signal for measuring an electrical conductivity of a target material;
An electrode sensor unit including a driving electrode for applying the measurement signal to the target material and a sensing electrode for sensing an electrical signal in the target material and outputting a sensing signal;
A synchronous detector for detecting a phase difference between the measurement signal input from the waveform generator and the sensing signal input from the sensing electrode;
A minimum reference unit and a maximum reference unit which receive the measurement signal output from the waveform generator and set the minimum reference value and the maximum reference value of the detection signal of the synchronous detector, respectively; And
And a control unit for operating the waveform generating unit and calculating the electric conductivity of the target substance when the detection signal inputted from the synchronous detector is within the reference range set at the minimum reference unit and the maximum reference unit,
A reference sensor unit having a circuit corresponding to the object material and the electrode sensor unit and receiving the measurement signal and outputting a reference sensing signal;
An analog signal multiplexing unit for selectively switching the measurement signal generated by the waveform generating unit to the reference sensor unit and the driving electrode at preset time intervals; And
Further comprising an analog signal distribution unit for selectively switching the reference sensing signal of the reference sensor unit and the sensing signal of the sensing electrode to the synchronous detector at preset time intervals.
The method according to claim 1,
Wherein the control unit receives the reference sensing signal, compares the sensing signal with the detection signal, and detects an error of the electrode sensor unit based on the comparison signal.
delete The method according to claim 1,
Wherein the waveform generator comprises:
And a resonance circuit having a digital variable resistor and a capacitor controlled by the control unit.
The method according to claim 1,
The lowest reference part and the highest reference part are,
And a capacitor connected in series with a digital variable resistor controlled by the control unit to output an electrical signal corresponding to a minimum reference value and a maximum reference value of a reference range of the detection signal.
3. The method of claim 2,
The reference sensor unit,
And a plurality of capacitors connected in series with a digital variable resistor controlled by the controller are arranged in parallel.
3. The method of claim 2,
Wherein,
An initialization step of initializing the waveform generating unit, setting a reference resistance value of the reference sensor unit, and setting resistance values of the lowest reference unit and the highest reference unit, and storing the setting data set in the initialization step Characterized in that the electrical conductance measuring device
3. The method of claim 2,
And an output unit for generating or displaying an alarm when the control unit detects that the detected signal for the target substance is less than the minimum reference value or exceeds a maximum reference value or when an error of the electrode sensor unit is detected through the reference sensor unit And an electric conductivity measuring device for measuring electric conductivity.
The method according to claim 1,
The electrode sensor unit may further include a temperature sensor for measuring a temperature of the target material,
Wherein the controller receives the temperature of the target material from the temperature sensor and performs a temperature compensation process.
Generating a measurement signal for measuring the electrical conductivity of the target material by operating the waveform generator;
Applying the measurement signal to the target material through a driving electrode of the electrode sensor unit, sensing an electrical signal from the target material through the sensing electrode, and outputting a sensing signal;
Detecting a phase difference between a measurement signal input from the waveform generator and a sensing signal input from the sensing electrode;
Determining whether a detection signal input from the synchronous detector is included in a reference range set at a minimum reference portion and a maximum reference portion; And
Wherein the controller calculates the electrical conductivity when the detection signal is within the reference range,
A reference sensor unit including the object material and a circuit corresponding to the electrode sensor unit, receiving the measurement signal, and outputting a reference sensing signal;
The analog signal multiplexing unit selectively switching the measurement signal generated by the waveform generating unit to the reference sensor unit and the driving electrode at preset time intervals; And
Wherein the analog signal distribution unit selectively switches the reference sensing signal of the reference sensor unit and the sensing signal of the sensing electrode to the synchronous detector at a set time interval.
11. The method of claim 10,
Wherein the control unit receives the reference sensing signal, compares the reference sensing signal with the detection signal, and detects an error of the electrode sensor unit based on the comparison signal.
delete 11. The method of claim 10,
In the step of generating the measurement signal,
Wherein the waveform generating unit comprises a resonant circuit including a digital variable resistor and a capacitor controlled by the control unit.
11. The method of claim 10,
In the step of determining whether it is included in the reference range,
Wherein the minimum reference unit and the maximum reference unit each include a capacitor connected in series with a digital variable resistor controlled by the control unit to output an electrical signal corresponding to a minimum reference value and a maximum reference value of a reference range of a detection signal, Method of measuring electrical conductivity.
12. The method of claim 11,
The reference sensor unit,
And a plurality of capacitors connected in series with a digital variable resistor controlled by the controller are arranged in parallel.
12. The method of claim 11,
And initializing the waveform generator when the power is applied, setting a reference resistance value of the reference sensor unit, and setting a resistance value of the lowest reference unit and the highest reference unit, respectively,
Wherein the controller stores the set data in the initialization step.
12. The method of claim 11,
Generating or displaying an alarm when the control unit detects an error of the electrode sensor unit through the output unit when the detected signal for the measured object is less than a minimum reference value or exceeds a maximum reference value, Further comprising the step of measuring the electrical conductivity.
11. The method of claim 10,
Wherein the electrode sensor unit includes a temperature sensor for measuring a temperature of the target material,
Wherein the controller receives the temperature of the target material from the temperature sensor and performs a temperature compensation process.

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