CN109187657A - A kind of water electric conductivity detection system and detection method - Google Patents
A kind of water electric conductivity detection system and detection method Download PDFInfo
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Abstract
The invention discloses a kind of water electric conductivity detection system and detection methods, including main control module, impedance transformation module, temperature detecting module and conductivity detection module, realize that conductivity detects range automatic identification and switching by impedance transformation module, it remains that detection range works in ideal linearity area, improves the accuracy of water electric conductivity detection；Temperature detecting module is increased, the temperature value that temperature detecting module detects is merged with the measurement amplitude of conductivity measurement module, the automatic compensation of results of conductivity measurement under varying temperature environment is realized, further increases the accuracy of water electric conductivity measurement result；Peripheral circuit is isolated with communication isolation module by power isolation module, reduces interference of the peripheral circuit to measurement, improves the precision and stability of water quality conductivity measurement under severe water body environment.
Description
Technical field
The present invention relates to water quality monitoring technical field more particularly to a kind of water electric conductivity detection systems and detection method.
Background technique
Conductivity gamma is the electricity physical quantity of evaluating water quality electric conductivity, is the inverse of electricalresistivityρ, it may be assumed that the ρ of γ=1/.Water
In quality supervision survey field, the conductivity of water quality is to measure the important indicator of water quality, for example measurement is drunk water conductivity and can be reflected
Electrolyte in water concentration, measurement quality of groundwater conductivity can reflect contaminated degree of water quality etc..Therefore, water electric conductivity
The accuracy of detection and precision are particularly significant.The measurement temperature of usual water electric conductivity is 25 ° of normal temperature, and actual measurement
When, the temperature of water body to be measured is usually to change, and conductivity testing result is understood variation with temperature and changed, therefore, temperature
It corrects very crucial to the accuracy of conductivity testing result.
Summary of the invention
The purpose of the present invention is to provide a kind of water electric conductivity detection system and detection methods, to improve existing water quality
The detection accuracy of conductivity sensing system.
In order to achieve the above object, the present invention provides a kind of water electric conductivity detection systems, including main control module, impedance
Conversion module, temperature detecting module and conductivity detection module are stored with the conductivity detection module in the main control module
It is different detection ranges under calibration factors, the impedance transformation module switch the detection range of the conductivity detection module with
The conductivity detection module is set to detect the conductivity of a water body under optimum detection range, and the main control module is according to
Measurement amplitude of the conductivity detection module under the optimum detection range, the corresponding calibration factor of the optimum detection range and
The temperature value that the temperature detecting module detects is to obtain conductivity of the water body under normal temperature.
Optionally, the calibration factor includes gain coefficient GFx, unbalance of system coefficient NosxAnd conductance correction coefficient Cx, root
According to following formula obtain conductivity gamma of the water body under normal temperature ':
γ=(Nx-Nosx)×GFx
Wherein, NxFor the measurement amplitude of the conductivity detection module；T is the temperature that the temperature detecting module detects
Value；γ is measurement conductivity；K, it is electrode coefficient and conductance thermal constant that β, which is respectively the conductivity detection module,.
Optionally, the water electric conductivity detection system further includes communication isolation module and power isolation module, described logical
Isolation module is believed between a host computer and the main control module and carries out communication isolating, the power isolation module isolation one
The voltage of power conversion module offer is simultaneously converted into operating voltage as the main control module, impedance transformation module, temperature inspection
Survey module, conductivity detection module and communication isolation module power supply.
Optionally, the power conversion module includes level-one conversion circuit and second level conversion circuit, the isolated from power mould
Block includes level-one isolation module and second level isolation module, and the level-one conversion circuit and the second level conversion circuit respectively will always
Galvanic electricity pressure is converted to first voltage signal and second voltage signal, the level-one isolation module and second level isolation module difference
First voltage signal and second voltage signal are converted into the first isolation signals and the second isolation signals.
Optionally, the impedance transformation module includes impedance channel selection circuit and zoom comparison circuit, and the impedance is logical
Road selection circuit is for switching calibration access resistance and measurement access channel, and by the zoom comparison circuit by the conductance
The impedance measurement signal of rate detection module inputs in the main control module.
The present invention also provides a kind of water electric conductivity detection methods, comprising:
S1: the water electric conductivity detection system is provided；
S2: the main control module enters calibration mode after receiving calibration command, and the impedance transformation module selection impedance is logical
Road switches calibration access resistance under each range, and the resistance value of calibration access resistance corresponds to the detection limit of the conductivity detection module
Journey, the main control module obtain each detection according to measurement amplitude of the conductivity detection module under each detection range
The calibration factor of the conductivity detection module and preservation under range；
S3: the main control module enters data acquisition scheme, the conductivity detection module after receiving data acquisition instructions
From the conductivity of detection range water body as described in small and big sequence detection, until the measurement of the conductivity detection module
Amplitude is not spilt over, and using detection range at this time as optimum detection range；
S4: the temperature detecting module detects the temperature of the water body；
S5: the main control module according to measurement amplitude of the conductivity detection module under the optimum detection range,
The temperature value that the corresponding calibration factor of optimum detection range and the temperature detecting module detect is to obtain the water body
Conductivity under normal temperature.
Optionally, the impedance transformation module includes impedance channel selection circuit and zoom comparison circuit, and, the master
Control module institute in the case where the measurement amplitude under each detection range obtains each detection range according to the conductivity detection module
The step of stating the calibration factor of conductivity detection module include:
S21: resistance value is R by impedance channel selection circuit11Calibration access resistance access the anti-of the zoom comparison circuit
It is R by resistance value in feedthrough road21Calibration access resistance access in the reversed input channel of the zoom comparison circuit, the electricity
It is Y that conductance detection module, which obtains reference signal,L1When measurement amplitude NL1；Continue resistance value to be R22Calibration access resistance access
In the reversed input channel of the zoom comparison circuit, it is Y that the conductivity detection module, which obtains reference signal,H1When measurement width
Value NH1, to obtain minimum detection range Q1Calibration factor；
S22: being R by resistance value1xCalibration access resistance access in the feedback channel of the zoom comparison circuit, be by resistance value
R2xCalibration access resistance access in the reversed input channel of the zoom comparison circuit, the conductivity detection module obtains ginseng
Examining signal is YLxWhen measurement amplitude NLx；Continue resistance value to be R2(x+1)Calibration access resistance access the zoom comparison circuit
Reversed input channel in, it is Y that the conductivity detection module, which obtains reference signal,H1When measurement amplitude NH1, to be detected
Range QxCalibration factor；
S23: enabling x=(x+1) and executes step S22, until obtaining the calibration factor of all detection range Q.
Optionally, the calibration factor includes gain coefficient GFx, unbalance of system coefficient NosxAnd conductance correction coefficient Cx, with
And the calibration factor of each detection range is obtained by following formula:
Nosx=Nx-YHx/GFx；
Optionally, resistance value R1xWith resistance value R2xIt is equal, and resistance value R1xWith resistance value R2xIncrease with the increase of x.
Optionally, the precision of each calibration access resistance is all larger than equal to one thousandth.
Beneficial effects of the present invention are as follows:
(1) the detection range of conductivity detection module is made to realize automatic identification and switching by impedance transformation module, always
It keeps detection range to work in ideal linearity area, improves the accuracy of water electric conductivity detection；
(2) temperature detecting module is increased, the temperature value that temperature detecting module is detected and conductivity measurement module
Amplitude fusion is measured, realizes the automatic compensation of results of conductivity measurement under varying temperature environment, further increases water electric conductivity measurement
As a result accuracy；
(3) peripheral circuit is isolated with communication isolation module by power isolation module, reduces peripheral circuit and measurement is done
It disturbs, improves the precision and stability of water quality conductivity measurement under severe water body environment；
(4) whole system uses dual power supply, reduces the distortion of water body conductivity measurement and temperature measurement to greatest extent.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of water electric conductivity detection system provided in an embodiment of the present invention；
Fig. 2 is the circuit diagram of main control module provided in an embodiment of the present invention and impedance transformation module；
Fig. 3 is the circuit diagram of temperature detecting module provided in an embodiment of the present invention；
Fig. 4 is the circuit diagram of power isolation module provided in an embodiment of the present invention；
Fig. 5 is the circuit diagram of communication isolation module provided in an embodiment of the present invention；
Fig. 6 is the flow chart of water electric conductivity detection method provided in an embodiment of the present invention；
Fig. 7 is the flow chart of calibration mode provided in an embodiment of the present invention；
Fig. 8 is the flow chart of data acquisition scheme provided in an embodiment of the present invention.
Specific embodiment
A specific embodiment of the invention is described in more detail below in conjunction with schematic diagram.According to following description and
Claims, advantages and features of the invention will become apparent from.It should be noted that attached drawing is all made of very simplified form and
Using non-accurate ratio, only for the purpose of facilitating and clarifying the purpose of the embodiments of the invention.
Referring to Fig. 1, it is the structural schematic diagram of water electric conductivity detection system provided in this embodiment, as shown in Figure 1,
The water electric conductivity detection system includes main control module 1, impedance transformation module 2, temperature detecting module 4 and conductivity detection mould
Block 3 is stored with calibration factors of the conductivity detection module 3 under different detection ranges, the resistance in the main control module 1
Anti- conversion module 2 switches the detection range of the conductivity detection module 3 so that the conductivity detection module 3 is in optimum detection
Detect the conductivity of a water body under range, and the main control module 1 according to the conductivity detection module 3 in the optimum detection
The temperature that measurement amplitude, the corresponding calibration factor of the optimum detection range and the temperature detecting module 4 under range detect
Angle value is to obtain conductivity of the water body under normal temperature.
Specifically, as shown in Fig. 2, the main control module 1 may include microprocessor 11, reference power source 12 (e.g.
TL431 chip), reset circuit 13 (e.g. MAX809SD chip) and system clock etc., the main control module 1 can with it is upper
Machine 7 carries out communication and signal conversion, realizes booting, standby, calibration, detection and the mode uploaded of water electric conductivity detection system
Switching, for example, power-on command is sent to the microprocessor 11 by the host computer 7, the microprocessor 11 is by Standby sleep
Mode wakeup is to operating mode；Standby command is sent to the microprocessor 11 by the host computer 7, and microprocessor is by Working mould
Formula enters low-power consumption standby sleep pattern；Calibration command is sent to the microprocessor 11, the micro process by the host computer 7
Device 11 executes calibration mode, and control impedance transformation module 2 completes the gain coefficient calculating of each detection range ability, unbalance of system system
Number calculates, conductance correction coefficient calculates and data save；Data acquisition instructions are sent to the microprocessor by the host computer 7
11, after the microprocessor 11 enters data acquisition scheme, the conductivity detection module 3 and the temperature acquisition are controlled respectively
Module 4 completes the acquisition of water body conductivity and temperature, and completes conductivity compensation correction and calculate and result output；Data upload mould
In formula, measurement result (conductivity under measurement conductivity, temperature value, normal temperature) is uploaded to described by the microprocessor 11
Host computer 7.In the present embodiment, the microprocessor 11 uses STM32F407VET6 chip.
Further, the impedance transformation module 2 is main including impedance channel selection circuit 21 and zoom comparison circuit 22, and
The impedance transformation module 2 is connect by an excitation amplifying circuit 23 with the microprocessor 11, the impedance channel selection electricity
The conductivity is examined by the zoom comparison circuit 22 for switching calibration access resistance and measurement access channel on road 21
The measuring signal for surveying module 3 inputs in the microprocessor 11.In the present embodiment, the selection of impedance transformation module 2 access 3
Calibration access resistance to the calibration that reversed input channel and 2 are more than or equal to 1 ‰ precision more than or equal to 1 ‰ precision accesses electricity
Resistance obtains the calibration factor under 2 groups of detection ranges to feedback channel respectively.
Specifically, as shown in Fig. 2, the impedance channel selection circuit 21 is using ADG715 chip (U2), the amplification
Comparison circuit 22 is made of a reversed comparator (U5B), and the excitation amplifying circuit 23 is made of amplifier (U5A), described
The 33rd pin of microprocessor 11 generates pumping signal to the 3rd pin of U5A chip, is exported after the amplification of U5A chip by the 1st pin
To the 12nd pin of ADG715 chip, the 13rd pin, the 15th pin, the 17th pin and the 19th pin, ADG715 chip realizes 3 tunnel schools
(R11-R13, R14-R16, wherein R13 is reserved calibration access resistance) the access selection of quasi- access resistance and measurement access channel
Access selection；The measuring signal of the conductivity detection module 3 is after impedance channel selection and U5B chip are reversely amplified through the 7th
Pin is exported to the 61st pin of microprocessor 11, and microprocessor 11 completes access analysis of Impedance Characteristic and meter using DSP in piece
It calculates, calculated result can be exported to host computer 7.Under data acquisition scheme, the 65th pin of microprocessor 11 and the 66th pin
Acquisition is sent to the 1st pin of ADG715 chip and the 3rd pin, controls the 20th pin and the 19th pin of ADG715 chip
Conducting, the 6th pin are successively connected with the 5th pin, and the 61st pin of microprocessor 11 exports sinusoidal excitation signal to U5A chip
3rd pin, U5A chip amplify sinusoidal signal 1:1, and the 1st pin output voltage of U5A chip is made to follow U5A chip always
3rd pin, completing the detection of uS~mS detection range ability internal conductance rate, (resistance value of R11-R13 is respectively 100 Ω, 1K Ω, 10K
The resistance value of Ω, R14-R16 are respectively 100 Ω, 1K Ω, 10K Ω)；If testing result (measurement amplitude) exceeds the range, micro- place
Reason device 11 continues to send data acquisition command to ADG715 chip, control ADG715 chip the 1st pin and the conducting of the 3rd pin,
20th pin and the conducting of the 19th pin, the 6th pin are connected with the 7th pin, obtain the testing result in mS~S detection range ability
(measurement amplitude), completes the switching of detection range.It is understood that conductivity detection module described in the present embodiment 3 is only set
Two uS~mS, mS~S detection ranges have been set, and has been provided with the quantity and resistance value of calibration access resistance accordingly, but in fact,
The conductivity detection module 3 can also there are two above detection ranges, and school can be arranged by corresponding reduction formula
The quantity and resistance value of quasi- access resistance, no longer illustrate one by one herein.
As shown in figure 3, the temperature detecting module 4 and conductivity detection module 3 are respectively used to detect the temperature of the water body
Degree and conductivity, in the present embodiment, the temperature detecting module 4 includes temperature sensor 41, signal amplification circuit 42 and voltage
Circuit 43 is followed, the temperature sensor 41 is directly contacted with the water body to detect the temperature of water body, and exports small electricity
Analog signals are pressed, through the signal amplification circuit 42 with mutually amplification output to voltage follower circuit 43, voltage follower circuit 43
In the 2nd pin of U3A chip reverse input end be directly connected to the 1st pin of output end, constitute voltage follower so that output electricity
Pressure follows non-inverting input terminal voltage always, and the 1st pin output voltage signal of U3A chip is connect with the 97th pin of microprocessor 11,
With to the 11 input measurement information of microprocessor, microprocessor 11 is converted temperature simulation magnitude by AD conversion high-precision in piece
For actual measurement temperature value.And when needing to acquire water body conductivity, the microprocessor 11 generates the sinusoidal signal of fixed frequency,
Electrode one end of conductivity detection module 3 is applied to after excitation amplification module 23 amplifies, so that the two of conductivity detection module 3
Water body between electrode generates alternating electric field, and impedance transformation module 2 obtains electric current letter from the 3 electrode other end of conductivity detection module
Number, further current signal is converted into voltage and is amplified to be transferred to microprocessor 11；Microprocessor 11 completes impedance analysis meter
It calculates, calculated result is transferred to communication transfer interface module 8 through communication isolation module 51 and is transferred to host computer 7 again.Optionally, the temperature
Sensor 6 uses LM35DZ sensor, and U1 chip uses AD623 chip, the voltage follow in the signal amplification circuit 42
U3A chip uses OP07 chip in circuit 43.
Further, as shown in Figure 4 and Figure 5, the water electric conductivity detection system further includes communication isolation module 51 and electricity
Source isolation module 52, the communication isolation module 51 between the host computer 7 and the main control module 1 and communicated every
From it is described that the power isolation module 52, which is isolated the voltage that a power conversion module 6 provides and is converted into operating voltage,
Main control module 1, impedance transformation module 2, temperature detecting module 4, conductivity detection module 3 and communication isolation module 51 are powered.
Specifically, as shown in figure 4, the power conversion module 6 include level-one conversion circuit 61 and second level conversion circuit 62,
It is described in the present embodiment for the DC voltage within the scope of 5~36V to be converted to first voltage signal and second voltage signal
First voltage signal is 5V, and second voltage signal is 3.3V, and the power isolation module 52 includes level-one isolation module 522 and two
Grade isolation module 521, for the second voltage signal of 3.3V is converted to 3.3V the first isolation signals and 3.3V second every
From signal.As shown in figure 4, DC power supply is used to issue the DC voltage within the scope of 5~36V, anode and one in the present embodiment
The 7th pin connection of U1 chip, power cathode are connect with the pin that electrical symbol in Fig. 4 is labeled as GND in grade conversion circuit 61,
The 16th pin of U4 chip exports the isolation voltage of 3.3V, U3 chip the 1st in second level isolation module 521 in level-one isolation module 522
The isolation voltage of pin output -3.3V is impedance transformation module 2, temperature detecting module 4, microprocessor 11 and communication isolating mould
Block 51 is powered, such as microprocessor 11 needs the operating voltage of 3.3V, just provides the isolation electricity of 3.3V for the microprocessor 11
Pressure, the temperature detecting module 4 need the operating voltage of 5V, just provide the isolation voltage of 5V for the temperature detecting module 4, no
It is limited to this.
Power conversion module 6 has the characteristics that unstability voltage is small, ripple voltage is small, and 52 isolation performance of power isolation module is excellent
It is different, to improve the precision of impedance analysis to greatest extent.Optionally, chip U1 is used in the power conversion module 6
TPS5430 chip, chip U2 uses ASM1117-3.3 chip in the power conversion module 6, in the power isolation module 52
Chip U3 uses TPS60400DBVT chip, and chip U4 uses ADuM5000 chip in the power isolation module 52.
Next, as shown in figure 5, the communication isolation module 51 includes magnetic-type communication isolating chip (U1), micro- place
The signal for managing the output of device 11 is exported into a communication transfer interface module 8 through the communication isolation module 51 isolation and is transferred to described
Host computer 7.The communication isolation module 51 is connect in circuit with host computer 7, the 16th pin of magnetic-type communication isolating chip and power supply
The connection of the 2nd pin of U2 chip, the 5th pin of magnetic-type communication isolating chip and the 6th pin and communication transfer interface module 8 in conversion circuit 6
Connect and compose communication isolating side A；The communication isolation module 51 is connect in circuit with microprocessor 11, magnetic-type communication isolating chip
1st pin is connect with the 16th pin of U4 chip in power isolation module 52, and the 5th pin of magnetic-type communication isolating chip, the 6th are drawn
Foot, the 3rd pin and the 4th pin connect structure with the 85th pin of microprocessor 11, the 86th pin, the 87th pin and the 88th pin respectively
At communication isolating side B, communication isolating side B receives the signal of communication of microprocessor 11 and output is isolated to communication isolating side A, communication
Side of isolation A receives the signal of communication of host computer 7 and output is isolated and prevents upper to communication isolating side B to realize communication isolating
Interference of 7 interference signal of machine through communication interface to microprocessor 11 can also improve impedance transformation module 2 and outer to greatest extent
The electrical isolation performance of circuit is enclosed, interference of the peripheral circuit to impedance transformation module 2 is reduced.Optionally, the communication isolating core
Piece uses ADM2486 chip.The communication transfer interface module 8 turns 485 communication converters using USB.
Based on this, the present embodiment additionally provides a kind of water electric conductivity detection method, comprising:
S1: the water electric conductivity detection system is provided；
S2: the main control module enters calibration mode after receiving calibration command, and the impedance transformation module selection impedance is logical
Road switches calibration access resistance under each range, and the resistance value of calibration access resistance corresponds to the detection limit of the conductivity detection module
Journey, the main control module obtain each detection according to measurement amplitude of the conductivity detection module under each detection range
The calibration factor of the conductivity detection module and preservation under range；
S3: the main control module enters data acquisition scheme, the conductivity detection module after receiving data acquisition instructions
From the conductivity of detection range water body as described in small and big sequence detection, until the measurement of the conductivity detection module
Amplitude is not spilt over, and using detection range at this time as optimum detection range；
S4: the temperature detecting module detects the temperature of the water body；
S5: the main control module according to measurement amplitude of the conductivity detection module under the optimum detection range,
The temperature value that the corresponding calibration factor of optimum detection range and the temperature detecting module detect is to obtain the water body
Conductivity under normal temperature.
Specifically, referring to Fig. 6, being connected after temperature detecting module 4 and conductivity detection module 3 enter water body first
Power supply；Microprocessor 11 executes communication initialization, judges whether the power-on instruction for receiving the transmission of host computer 7, if then upwards
Position machine 7 sends booting response instruction, so that microprocessor 11 is executed temperature, conductivity acquisition initialization, if otherwise entering standby mould
Formula waits.
The microprocessor 11 executes temperature, conductivity acquisition initialization, and the microprocessor 11 judges whether to receive
The calibration command of host computer 7, if then entering calibration mode, if otherwise still entering standby mode.
In the calibration mode, the microprocessor 11 is according to the conductivity detection module 3 under each detection range
Measurement amplitude obtain it is each it is described detection range under the conductivity detection module 3 calibration factor, the specific steps are as follows:
As shown in Fig. 2 and Fig. 7, the microprocessor 11 will using IIC communication interface control impedance channel selection circuit 21
Resistance value is R11The feedback that the calibration access resistance of (R11 in Fig. 2, resistance value are 100 Ω) accesses the zoom comparison circuit 22 is logical
It is R by resistance value in road21The calibration of (R14 in Fig. 2, resistance value are 100 Ω) accesses resistance and accesses the zoom comparison circuit 22
In reversed input channel, it is Y that the conductivity detection module 3, which obtains reference signal,L1When measurement amplitude NL1；Continue resistance value
For R22(R15 in Fig. 2, resistance value are 1k Ω) calibration access resistance accesses in the reversed input channel of the zoom comparison circuit,
It is Y that the conductivity detection module 3, which obtains reference signal,H1When measurement amplitude NH1, to obtain minimum detection range Q1(uS~
MS calibration factor)；
It then, is R by resistance value12The calibration of (R12 in Fig. 2, resistance value are 1k Ω) accesses resistance and accesses the zoom comparison
It is R by resistance value in the feedback channel of circuit 2222The calibration of (R15 in Fig. 2, resistance value are 1k Ω) accesses puts described in resistance access
In the reversed input channel of big comparison circuit 22, it is Y that the conductivity detection module 3, which obtains reference signal,L2When measurement amplitude
NL2；Continue resistance value to be R23The calibration of (R17 in Fig. 2, resistance value are 10k Ω) accesses resistance and accesses the zoom comparison circuit
In 22 reversed input channel, it is Y that the conductivity detection module 3, which obtains reference signal,H2When measurement amplitude NH2, to obtain
Detect range Q2(mS~S) calibration factor, the microprocessor 11 obtains the calibration factor according to following calculation formula:
Automatic calibration is completed, and two detection ranges corresponding calibration factor GF1, GF2, Nos1, Nos2, C1 and C2 are saved
Flash in the piece of microprocessor 11.
It is understood that if the conductivity detection module 3 incessantly there are two the detection range, can according to
Upper method finds the calibration factor of other detection ranges, such as: it is R by resistance value1xCalibration access resistance access the amplification ratio
It is R by resistance value compared in the feedback channel of circuit2xCalibration access resistance access the reversed input channel of the zoom comparison circuit
In, it is Y that the conductivity detection module, which obtains reference signal,LxWhen measurement amplitude NLx；Continue resistance value to be R2(x+1)Calibration
Access resistance accesses in the reversed input channel of the zoom comparison circuit, and the conductivity detection module obtains reference signal and is
YH1When measurement amplitude NH1, to obtain detection range Q by following formulaxCalibration factor；
Nosx=Nx-YHx/GFx； (5)
It enables x=(x+1) and recycles execution above-mentioned steps, until obtaining the calibration factor of all detection range Q.Its
In, resistance value R1xWith resistance value R2xIt is equal, and resistance value R1xWith resistance value R2xIncrease with the increase of x.
Next, into data acquisition scheme, the access measurement access of conductivity detection module 3 channel, the conductivity inspection
Conductivity of the module 3 from detection range Q water body as described in small and big sequence detection is surveyed, until the conductivity detects mould
The measurement amplitude of block 3 is not spilt over, and using detection range at this time as optimum detection range.
Specifically, the temperature detecting module 11 obtains as shown in figure 8, microprocessor 11 executes temperature, conductivity acquisition
The water temperature value t, meanwhile, microprocessor 11 controls impedance channel selection circuit 21 for conductivity using IIC communication interface
The reverse input end of the two electrodes access zoom comparison circuit 22 of detection module 3, and it is switched to Q1Detect range, the conductivity
Detection module 3 obtains measurement amplitude N1, judge N1Whether uS~mS detection range is overflowed, if being then switched to Q2Detecting range (will
Q2Range is detected as optimum detection range), obtain the measurement amplitude N under mS~S range2；If not overflowing, only need by
Q1Range is detected as optimum detection range, microprocessor 11 is by the corresponding measurement amplitude N of optimum detection rangexAccording to formula (7)
It is converted to measurement conductivity gamma, calculated result is stored in the inside Flash of microprocessor 11.
γ=(Nx-Nosx)×GFx (7)
Finally, water temperature value t and measurement conductivity gamma of the microprocessor 11 according to acquisition, in conjunction with optimum detection range pair
Electrode COEFFICIENT K, conductance thermal constant β and the conductance correction coefficient C for the conductivity detection module 3 answeredx, calculated according to formula (8)
Out the conductivity gamma under normal temperature (25 °) ', and this measurement result is exported into host computer 7.
To sum up, in water electric conductivity detection system provided in an embodiment of the present invention and detection method, including main control module,
Impedance transformation module, temperature detecting module and conductivity detection module realize that conductivity detects range by impedance transformation module
Automatic identification and switching remain that detection range works in ideal linearity area, improve the accuracy of water electric conductivity detection；
Temperature detecting module is increased, the measurement amplitude of temperature value and conductivity measurement module that temperature detecting module detects is melted
It closes, realizes the automatic compensation of results of conductivity measurement under varying temperature environment, further increase the accurate of water electric conductivity measurement result
Degree；Peripheral circuit is isolated with communication isolation module by power isolation module, reduces interference of the peripheral circuit to measurement, improves and dislike
The precision and stability of water quality conductivity measurement under bad water body environment；
The above is only a preferred embodiment of the present invention, does not play the role of any restrictions to the present invention.Belonging to any
Those skilled in the art, in the range of not departing from technical solution of the present invention, to the invention discloses technical solution and
Technology contents make the variation such as any type of equivalent replacement or modification, belong to the content without departing from technical solution of the present invention, still
Within belonging to the scope of protection of the present invention.
Claims (10)
1. a kind of water electric conductivity detection system, which is characterized in that including main control module, impedance transformation module, temperature detection mould
Block and conductivity detection module are stored with schools of the conductivity detection module under different detection ranges in the main control module
Quasi- coefficient, the impedance transformation module switches the detection range of the conductivity detection module so that the conductivity detection module
Detect the conductivity of a water body under optimum detection range, and the main control module according to the conductivity detection module described
Measurement amplitude, the corresponding calibration factor of the optimum detection range and temperature detecting module detection under optimum detection range
To temperature value to obtain conductivity of the water body under normal temperature.
2. water electric conductivity detection system as described in claim 1, which is characterized in that the calibration factor includes gain coefficient
GFx, unbalance of system coefficient NosxAnd conductance correction coefficient Cx, electricity of the water body under normal temperature is obtained according to the following formula
Conductance γ ':
γ=(Nx-Nosx)×GFx
Wherein, NxAmplitude is measured for the water electric conductivity of the conductivity detection module；T is that the temperature detecting module detects
Water quality temperature value；γ is measurement conductivity；K, it is that electrode coefficient and conductance temperature are normal that β, which is respectively the conductivity detection module,
Number.
3. water electric conductivity detection system as claimed in claim 2, which is characterized in that the water electric conductivity detection system is also
Including communication isolation module and power isolation module, the communication isolation module is between a host computer and the main control module
And communication isolating is carried out, the power isolation module is isolated the voltage that a power conversion module provides and is converted into work electricity
Pressure is the main control module, impedance transformation module, temperature detecting module, conductivity detection module and communication isolation module power supply.
4. water electric conductivity detection system as claimed in claim 3, which is characterized in that the power conversion module includes level-one
Conversion circuit and second level conversion circuit, the power isolation module include level-one isolation module and second level isolation module, and described one
One DC voltage is converted to first voltage signal and second voltage signal respectively by grade conversion circuit and the second level conversion circuit,
First voltage signal and second voltage signal are converted to first respectively by the level-one isolation module and the second level isolation module
Isolation signals and the second isolation signals.
5. water electric conductivity detection system as described in claim 1, which is characterized in that the impedance transformation module includes impedance
Channel selection circuit and zoom comparison circuit, the impedance channel selection circuit is for switching calibration access resistance and measurement access
Channel, and the impedance measurement signal of the conductivity detection module is inputted by the main control module by the zoom comparison circuit
In.
6. a kind of water electric conductivity detection method characterized by comprising
S1: water electric conductivity detection system according to any one of claims 1 to 5 is provided；
S2: the main control module enters calibration mode after receiving calibration command, and the impedance transformation module selection impedance channel is cut
Calibration access resistance under each range is changed, the resistance value of calibration access resistance corresponds to the detection range of the conductivity detection module, institute
It states main control module and each detection range is obtained according to measurement amplitude of the conductivity detection module under each detection range
Under the conductivity detection module calibration factor and preservation；
S3: the main control module, which receives, enters data acquisition scheme after data acquisition instructions, and the conductivity detection module is from institute
The conductivity of detection range water body as described in small and big sequence detection is stated, until the measurement amplitude of the conductivity detection module
It does not spill over, and using detection range at this time as optimum detection range；
S4: the temperature detecting module detects the temperature of the water body；
S5: the main control module is according to measurement amplitude of the conductivity detection module under the optimum detection range, described
The temperature value that the corresponding calibration factor of optimum detection range and the temperature detecting module detect is being marked with obtaining the water body
Conductivity at quasi- temperature.
7. water electric conductivity detection method as claimed in claim 6, which is characterized in that the impedance transformation module includes impedance
Channel selection circuit and zoom comparison circuit, and, the main control module is according to the conductivity detection module in each detection limit
Measurement amplitude under journey obtain it is each it is described detection range under the conductivity detection module calibration factor the step of include:
S21: resistance value is R by impedance channel selection circuit11Calibration access resistance access the zoom comparison circuit feedback it is logical
It is R by resistance value in road21Calibration access resistance access in the reversed input channel of the zoom comparison circuit, the conductivity
It is Y that detection module, which obtains reference signal,L1When measurement amplitude NL1；Continue resistance value to be R22Calibration access resistance access described in
In the reversed input channel of zoom comparison circuit, it is Y that the conductivity detection module, which obtains reference signal,H1When measurement amplitude
NH1, to obtain minimum detection range Q1Calibration factor；
S22: being R by resistance value1xCalibration access resistance access in the feedback channel of the zoom comparison circuit, by resistance value be R2x's
Calibration access resistance accesses in the reversed input channel of the zoom comparison circuit, and the conductivity detection module is obtained with reference to letter
Number be YLxWhen measurement amplitude NLx；Continue resistance value to be R2(x+1)Calibration access resistance access the anti-of the zoom comparison circuit
Into input channel, it is Y that the conductivity detection module, which obtains reference signal,H1When measurement amplitude NH1, to obtain detection range
QxCalibration factor；
S23: enabling x=(x+1) and executes step S22, until obtaining the calibration factor of all detection range Q.
8. water electric conductivity detection method as claimed in claim 7, which is characterized in that the calibration factor includes gain coefficient
GFx, unbalance of system coefficient NosxAnd conductance correction coefficient Cx, and, the school of each detection range is obtained by following formula
Quasi- coefficient:
Nosx=Nx-YHx/GFx；
9. water electric conductivity detection method as claimed in claim 7, which is characterized in that resistance value R1xWith resistance value R2xIt is equal, and hinder
Value R1xWith resistance value R2xIncrease with the increase of x.
10. water electric conductivity detection method as claimed in claim 9, which is characterized in that each calibration access resistance
Precision is all larger than equal to one thousandth.
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| CN117147974A (en) * | 2023-10-19 | 2023-12-01 | 北京江云智能科技有限公司 | Underground water collecting and quality analyzing device with integrated temperature, water level and conductivity |
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