Handheld electrolyte solution conductivity measuring system and method

Abstract

The invention discloses a handheld electrolyte solution conductivity measurement system and method, and relates to the technical field of conductivity measurement. The system comprises a detection coil, a reference coil, an analog switch, a signal generating and processing circuit and a processor, parameters of the detection coil and the reference coil are consistent, the detection coil is at the near end of the detected electrolyte solution, and the reference coil is far away from the detection coil and the detected solution and is prevented from being influenced by mutual inductance; the detection coil and the reference coil can be sequentially connected to the signal generation and processing circuit through the analog switch to respectively generate electric signals with corresponding frequencies, and the processor sequentially collects frequency values corresponding to the electric signals generated by the two coils; and then carrying out differential calculation on the frequency values of the two paths of signals to determine the conductivity of the detected electrolyte solution. According to the system, the anti-interference performance of the system is greatly enhanced while the measurement precision of the conductivity of the electrolyte solution is ensured.

Description

Technical Field

[0001] This invention relates to the field of conductivity measurement technology, and in particular to a handheld electrolyte solution conductivity measurement system and method. Background Technology

[0002] Currently, the methods for measuring the conductivity of electrolyte solutions are mainly divided into two categories: ① invasive electrode conductivity measurement method; ② non-invasive electromagnetic induction conductivity measurement method.

[0003] Invasive electrode conductivity measurement involves immersing an electrode in the electrolyte solution to be tested, ensuring direct contact between the electrode and the solution. The electrode forms a circuit within the electrolyte solution, and the conductivity is characterized by the impedance of the solution. Electrode-based measurement systems are relatively simple in structure, and the corresponding measurement circuits are mature, making them widely used. However, electrode-based measurement systems also have unavoidable drawbacks:

[0004] ① The electrodes are easily worn out and have high maintenance costs: Because the electrodes are in direct contact with the electrolyte solution being tested, they are easily contaminated by suspended matter, precipitates, etc. in the solution, and strong acid and strong alkali solutions will corrode the electrodes, causing changes in the conductivity of the electrodes. ②Electrode polarization effect: Since the electrode forms a circuit when current is passed through it in the electrolyte solution, micro-electrolysis will occur near the electrode, affecting the rate and efficiency of the electrode reaction; ③ High temperature sensitivity: Temperature changes significantly affect the degree of ionization, ion migration rate, viscosity, etc. of a solution, thereby altering its conductivity. Improper temperature compensation settings or sensor malfunction will lead to systematic deviations.

[0005] ④ Capacitive effect and cable interference: When AC excitation is used, the double-layer capacitance formed between the electrode and the solution, the distributed capacitance of the lead wire, etc. will introduce additional reactance, causing phase shift of the measurement signal and affecting the accuracy of impedance calculation; this is especially obvious with long cables.

[0006] Electromagnetic induction conductivity measurement is a powerful technology that perfectly solves the core pain points of electrode methods in terms of cost, polarization, corrosion, and contamination, making it particularly suitable for measuring fluids with high conductivity, high corrosivity, and contamination. However, it also has unavoidable drawbacks compared to electrode methods in terms of measurement principle and implementation: The measurement system design is highly complex. Compared to electrode-based measurement systems, electromagnetic induction conductivity measurement systems typically measure the conductivity of a solution indirectly through two coils (one transmitting and one receiving), with the solution forming part of a closed loop. The conductivity value is indirectly reflected by the change in electrical signal parameters caused by changes in the coil parameters. Traditional measurement methods usually measure changes in coil voltage and current. Because the eddy currents generated by the low conductivity of the measured object are very weak, operational amplifier circuits are usually added to obtain more obvious voltage changes. However, since the circuit is excited by a high-frequency AC signal for effective value detection during the measurement process, it is easily affected by power supply ripple and noise interference, thus introducing measurement errors. Summary of the Invention

[0007] Therefore, it is necessary to provide a handheld electrolyte solution conductivity measurement system and method to address the aforementioned technical problems.

[0008] The present invention adopts the following technical solution: This invention provides a handheld electrolyte solution conductivity measurement system, which includes a detection coil, a reference coil, an analog switch, a signal generation and processing circuit, and a processor; the parameters of the detection coil and the reference coil are consistent, and there is a preset distance between the reference coil and the detection coil and the electrolyte solution being measured, with the detection coil located near the electrolyte solution being measured; the preset distance is used to ensure that the reference coil is not affected by the mutual inductance between the electrolyte solution being measured and the detection coil; The processor is used to control an analog switch to sequentially connect the detection coil and the reference coil to the signal generation and processing circuit. The signal generation and processing circuit generates an electrical signal of a certain frequency corresponding to the detection coil when the detection coil is connected, and generates an electrical signal of a certain frequency corresponding to the reference coil when the reference coil is connected. The processor also collects the frequency values ​​of the two electrical signals of the detection coil and the reference coil through an internal counter unit, and performs differential calculation on the frequency values ​​of the two electrical signals to determine the conductivity of the electrolyte solution being tested.

[0009] Optionally, both the detection coil and the reference coil are planar spiral coils made of standard printed circuit boards, with the detection coil placed vertically directly above the horizontal level of the electrolyte solution being tested.

[0010] Optionally, the signal generation and processing circuit includes a signal generation circuit and a signal processing circuit; The signal generation circuit is an LC oscillation circuit. The detection coil or reference coil, as the inductive element of the LC oscillation circuit, is connected to the LC oscillation circuit in sequence through an analog switch to generate a sinusoidal signal of a certain frequency. The processing circuit is a shaping circuit, used to convert the sinusoidal signal into a square wave signal that the processor can recognize. The frequency of the square wave signal is the same as the output frequency of the signal generation circuit.

[0011] Optionally, the frequency of the sinusoidal signal output by the signal generation circuit is: ; in, This is the resonant capacitor of the signal generation circuit. L This is the self-inductance value of the coil. The frequency of the sinusoidal signal is denoted as .

[0012] Optionally, the system also includes a power supply; The power supply powers the analog switches, signal generation and processing circuits, and the processor.

[0013] Optionally, the system also includes a charging / data transfer interface and a display screen; A charging / data transfer interface is used for signal transmission and data exchange with external devices; The display screen is used to show the conductivity of the electrolyte solution being tested.

[0014] This invention provides a handheld method for measuring the conductivity of an electrolyte solution. This method is applied to the system described in any of the above embodiments, and includes: The processor controls the analog switch to connect the detection coil to the signal generation and processing circuit, so that the signal generation and processing circuit generates an electrical signal with a certain frequency that the processor can directly acquire from the detection coil. The processor controls the analog switch to disconnect the detection coil and connects the reference coil to the signal generation and processing circuit through the analog switch, so that the signal generation and processing circuit generates an electrical signal with a certain frequency from the reference coil that can be directly acquired by the processor. The processor performs differential calculations on the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil to determine the conductivity of the electrolyte solution being tested.

[0015] Optionally, the conductivity of the electrolyte solution being tested is determined by differential calculation of the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil, including: The frequency difference value is obtained by calculating the difference between the frequency value corresponding to the electrical signal of the detection coil and the frequency value corresponding to the electrical signal of the reference coil. Obtain the fitting calibration curve; the fitting calibration curve is the relationship between the difference frequency values ​​of various samples and the conductivity of the sample electrolyte solution; The conductivity of the electrolyte solution being tested, corresponding to the difference frequency value, is determined from the fitted calibration curve.

[0016] This invention provides a microcontroller processor, model STM32F103C8T6, which has the function of storing and executing programs. When the program is executed by the processor, it implements the above-mentioned handheld electrolyte solution conductivity measurement method.

[0017] The above-mentioned at least one technical solution adopted in this invention can achieve the following beneficial effects: In this system, the detection coil is close to the electrolyte solution being measured. When the conductivity of the solution changes, the inductance of the detection coil changes, causing a change in the circuit's output frequency. The reference coil maintains a certain distance from both the detection coil and the electrolyte solution to avoid mutual inductance interference, ensuring that the reference coil is only affected by external environmental factors such as temperature changes. During conductivity measurement, the detection coil and reference coil are sequentially connected to the signal generation and processing circuit via analog switches. The signal generation and processing circuit generates electrical signals from the detection coil and the reference coil. These signals do not require amplification or AD conversion and can be directly connected to the processor. The processor acquires the frequency values ​​of the electrical signals from the detection coil and the reference coil, and calculates the difference between the frequencies output by the detection coil and the reference coil. The resulting difference is the frequency differential value between the detection coil and the reference coil, thereby calculating the conductivity of the electrolyte solution being measured. This system converts environmental interference into common-mode signals for suppression, greatly improving the system's anti-interference capability and achieving high-precision conductivity measurement. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 This is a schematic diagram of the structure of a handheld electrolyte solution conductivity measurement system provided by the present invention; Figure 2 A schematic diagram of another handheld electrolyte solution conductivity measurement system provided by the present invention; Figure 3 This is a schematic diagram of a handheld electrolyte solution conductivity measurement method provided by the present invention; Figure 4 A schematic diagram of another handheld electrolyte solution conductivity measurement method provided by the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Detection coil; 2. Reference coil; 3. Analog switch; 4. Signal generation and processing circuit; 5. Processor; 6. Power supply; 7. Charging / data transmission interface; 8. Display screen. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] Among them, the electromagnetic induction conductivity measurement method still has unavoidable drawbacks compared to the electrode method in terms of measurement principle and implementation method: ① Poor measurement performance with low conductivity: The induced current signal in the solution circuit is very weak and directly proportional to the conductivity of the solution. When the conductivity is extremely low (such as in ultrapure water), the intensity of the induced current signal will be close to or even drowned out by ambient noise. In this case, it is often necessary to increase the excitation frequency of the measurement circuit, thereby increasing the complexity of the circuit.

[0023] ② Inherent limitations of the measurement principle: Because the electrical contact is completely isolated, this method can only measure conductivity and cannot be used to measure pH, redox potential (ORP) or perform electrochemical analysis. ③ Similar to electrode-based measurement methods, electromagnetic induction conductivity measurement is more sensitive to the measurement environment (temperature, vibration).

[0024] ④ Specific limitations of application scenarios: Solutions containing magnetic particles: If the solution contains ferromagnetic particles, they will accumulate near the probe, severely interfering with the magnetic field and causing the measurement to be completely inaccurate.

[0025] A novel method and system for measuring seawater conductivity is provided in the prior art. This system achieves electromagnetic induction measurement of seawater conductivity, primarily addressing the AC excitation issue. It acquires the target current and fits a calibration curve, determining the seawater conductivity corresponding to the target current based on the fitted calibration curve. The system employs a dual-coil (one transmitter, one receiver) structure. A high-frequency AC signal is applied to the transmitting coil to generate an alternating electromagnetic field, forming an eddy current loop in the seawater. The target current is then acquired by a resonator at the induction end, and the data processing module uses this data to fit the calibration curve. Based on the fitted calibration curve, the seawater conductivity corresponding to the target current is determined. This measurement method belongs to the traditional fixed-frequency amplitude modulation (AM) measurement circuit. The output signal is a current signal, which is an analog signal. Acquisition first requires converting the current into a voltage signal. Although a high-precision AD conversion module can be used, the current signal induced in the solution loop is very weak, typically requiring an operational amplifier circuit. However, because the circuit is excited by a high-frequency AC signal for effective value detection during the measurement process, it is susceptible to power supply ripple and noise interference, leading to measurement errors. This results in a complex system structure, high power consumption, and is not suitable for the design requirements of handheld measuring devices.

[0026] In another existing technology, a single-coil measurement model based on magnetic resonance and eddy current technology is proposed through analysis of a single-coil magnetic resonance seawater conductivity measurement model. In this single-coil system, the coil acts as both an excitation coil to generate an electromagnetic field and a receiving coil to read the measurement signal, simplifying the structure of the detection unit. Similar to the aforementioned method, this also belongs to the fixed-frequency amplitude modulation measurement circuit, and it also suffers from problems such as requiring many components, complex structure, and high power consumption. Despite using a single-coil structure, it is still susceptible to interference factors in high-frequency environments and the influence of external environmental changes such as temperature on the measurement circuit, leading to significant errors in the measurement results.

[0027] Based on this, the present invention provides a handheld electrolyte solution conductivity measurement system and method. This system has a simple structure, its measurement and transmission can be directly applied to digital technology, it is easy to interface with a computer, and it has advantages such as high accuracy and strong anti-interference capability. When the conductivity of the electrolyte solution being measured changes, the inductance value of the detection coil changes, causing a change in the output frequency of the circuit. This signal can be directly connected to the processor's counter unit to obtain the frequency value without signal amplification or AD conversion module. Then, based on the principle of magnetic coupling resonance, a differential measurement method is used. By introducing a reference coil and the measuring coil into the same measurement circuit and placing them in the same measurement environment, the final output signal is the frequency difference value between the two. This method can convert environmental interference into a common-mode signal for suppression, greatly improving the system's anti-interference capability. High-precision measurement of conductivity is achieved.

[0028] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of a handheld electrolyte solution conductivity measurement system according to the present invention. The system includes: a detection coil 1, a reference coil 2, an analog switch 3, a signal generation and processing circuit 4, and a processor 5. The parameters of the detection coil 1 and the reference coil 2 are identical. There is a preset interval between the detection coil 1, the reference coil 2, and the electrolyte solution being measured. The detection coil 1 is located near the electrolyte solution being measured. The preset interval is used to ensure that the reference coil 2 is not affected by the mutual inductance between the electrolyte solution being measured and the detection coil 1. Both the detection coil 1 and the reference coil 2 are planar spiral coils made on a standard printed circuit board (PCB). The detection coil 1 is placed vertically directly above the horizontal liquid level of the electrolyte solution being measured. When the conductivity of the electrolyte solution being measured changes, the inductance value of the detection coil 1 will change accordingly. Optionally, the interval between the reference coil and the detection coil is not limited to the interval between the reference coil and the electrolyte solution being measured; they can be the same or different and can be set according to requirements. The placement of the reference coil is flexible and is not limited to being placed coaxially with the detection coil, as long as there is sufficient distance between it and the electrolyte solution being measured and the detection coil to ensure that it is not affected by the mutual inductance between the electrolyte solution being measured and the detection coil. The preset interval can be 50mm; when the detection coil 1 and the reference coil 2 change simultaneously, the frequency values ​​of the two are output differentially to achieve the purpose of anti-interference.

[0030] Optionally, the parameters of the reference coil 2 and the detection coil 1 are completely identical: the inner radius r1 is 6.2 mm, the outer radius r2 is 12.2 mm, the coil thickness is 1.6 cm, the number of turns is 9, and the inductance of both coils is 3.3 μH.

[0031] The processor 5 is used to control the analog switch 3 to sequentially connect the detection coil 1 and the reference coil 2 to the signal generation and processing circuit 4. The signal generation and processing circuit 4 generates an electrical signal with a certain frequency corresponding to the detection coil 1 when the detection coil 1 is connected, and generates an electrical signal with a certain frequency corresponding to the reference coil 2 when the reference coil 2 is connected. The processor also collects the frequency values ​​of the two electrical signals corresponding to the detection coil 1 and the reference coil 2 through the internal counter unit, and performs differential calculation on the frequency values ​​of the two electrical signals to determine the conductivity of the electrolyte solution being tested. Signal generation and processing circuit 4 includes a signal generation circuit and a signal processing circuit, such as... Figure 2As shown, the signal generation circuit is an LC oscillation circuit. Detection coil 1 or reference coil 2, as the inductor element of the LC oscillation circuit, is sequentially connected to the LC oscillation circuit through analog switch 3 to generate a sinusoidal signal of a certain frequency. The signal processing circuit is a shaping circuit used to convert the sinusoidal signal into a square wave signal, i.e., an electrical signal, that can be recognized by processor 5. The frequency of this square wave signal is consistent with the output frequency of the signal generation circuit. The shaping circuit can be a comparator capable of converting the sinusoidal signal into a square wave signal that processor 5 can recognize; for example, a dedicated comparator chip or an open-loop or positive feedback operational amplifier.

[0032] In one embodiment, the signal generating circuit is an LC oscillating circuit, and the frequency of the sinusoidal signal output by the signal generating circuit is: in, This is the resonant capacitor of the signal generation circuit. L This is the self-inductance value of the coil. The frequency of the sinusoidal signal is denoted as .

[0033] In one embodiment, please see [link to previous article]. Figure 1 The system also includes a power supply 6, which powers the analog switch 3, signal generation and processing circuit 4, and processor 5. The power supply 6 can be a rechargeable lithium battery, which powers the entire system. The system's dimensions are approximately 40mm wide, 150mm long, and 30mm thick, making it easy to manufacture as a handheld device for portability and flexible application scenarios. Furthermore, the processor is a 32-bit microcontroller, model STM32F103C8T6, thus the system has advantages such as low design cost and ease of mass production.

[0034] In one embodiment, please see [link to previous article]. Figure 1 The system also includes a charging / data transmission interface 7 and a display screen 8; the charging / data transmission interface 7 is used for signal transmission and data exchange with external devices; the display screen 8 is used to display the conductivity of the electrolyte solution being tested.

[0035] Figure 3 This is a flowchart illustrating a handheld electrolyte solution conductivity measurement method according to the present invention. The method is applied to the system described in any of the above embodiments and specifically includes the following steps: S101, the processor controls the analog switch to connect the detection coil to the signal generation and processing circuit, so that the signal generation and processing circuit generates an electrical signal with a certain frequency from the detection coil that can be directly acquired by the processor.

[0036] Specifically, the analog switch can be an analog gating switch. The processor controls the analog gating switch to first connect the detection coil to the signal generation circuit, which generates a sinusoidal signal of a certain frequency. Subsequently, the signal processing circuit converts this signal into a square wave signal that is easy for the processor to recognize. The processor then acquires the frequency value corresponding to the electrical signal output by the detection coil generated by the signal processing circuit. f 1. This frequency value is related to the designed signal generation circuit.

[0037] S102, the processor controls the analog switch to disconnect the detection coil and connects the reference coil to the signal generation and processing circuit through the analog switch, so that the signal generation and processing circuit generates an electrical signal with a certain frequency from the reference coil that can be directly acquired by the processor.

[0038] The processor collected the frequency value f After step 1, the analog gating switch is turned off to disconnect the detection coil, and the reference coil is turned on. Following the same process described above, the processor acquires the signal processing circuit and generates the frequency value corresponding to the electrical signal output by the reference coil. f 2 .

[0039] S103, the processor performs differential calculation on the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil to determine the conductivity of the electrolyte solution being tested.

[0040] In one embodiment, the conductivity of the electrolyte solution to be tested is determined by differential calculation of the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil, including: differential calculation of the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil to obtain the difference frequency value; obtaining a fitting calibration curve; the fitting calibration curve is a curve showing the relationship between the difference frequency signals of various samples and the conductivity of the sample electrolyte solution; and determining the conductivity of the electrolyte solution to be tested corresponding to the difference frequency value from the fitting calibration curve.

[0041] Specifically, the processor will frequency f 1 and frequency f 2 Perform a difference operation to obtain the difference frequency value. f diff = f 1 – f 2 The difference frequency value is the corresponding output frequency for measuring the conductivity of the electrolyte solution to be tested; the processor determines the conductivity of the electrolyte solution to be tested corresponding to the difference frequency value based on the fitted calibration curve.

[0042] like Figure 4As shown, the present invention also provides a handheld method for measuring the conductivity of electrolyte solutions. This embodiment includes: sequentially connecting a detection coil and a reference coil to a signal generation and processing circuit via an analog switch, and acquiring the frequency output by the detection coil. f 1 and the frequency of the reference coil output f 2 The difference frequency value is obtained. f diff =f 1 -f 2 The fitting calibration curve between the difference frequency value and the conductivity of the electrolyte solution being tested is obtained. Based on the fitting calibration curve, the conductivity value corresponding to the output difference frequency value is determined.

[0043] In one specific embodiment, the present invention also provides a handheld method for measuring the conductivity of an electrolyte solution, which includes the following steps: S1, Fitting steps for the calibration curve: Obtain multiple sample difference frequency values ​​and the conductivity of the sample electrolyte solution corresponding to each sample difference frequency value; S2 explains the relationship between the difference frequency signal and the conductivity of the electrolyte solution: S3. When the detection coil is located above the electrolyte solution being tested, its coil impedance value will be affected by parameters such as the coil's own size, signal frequency, distance from the coil to the solution (lifting height), and solution conductivity. When other parameters are fixed and only conductivity is changed, the change in coil impedance is only related to conductivity.

[0044] S4, the change in inductance of the detection coil caused by the conductive liquid on the conductive liquid plane is: in, This represents the change in coil impedance. This represents the change in coil resistance. This represents the change in coil inductance. The imaginary unit; The frequency of the excitation signal; Permeability of free space; The relative permeability of the solution; , Electrical conductivity; , N The number of coil turns. d For coil thickness, r 1 , r 2 These are the inner and outer radii of the coil, respectively. h The height of the coil from the solution being measured; , It is a first-order Bessel function of the first kind; For discrete eigenvalues, by Take boundary values ,but Using the orthogonality of Bessel functions, we can obtain .

[0045] As can be seen from the expression for the impedance change of the coil, when the coil parameters and measurement position are fixed, the change in the coil's inductance is only related to the conductivity of the solution being measured. related.

[0046] S5, In actual measurement, the detection coil and reference coil are sequentially connected to the signal generation circuit via an analog switch to generate a sinusoidal signal of a certain frequency. This signal generation circuit is an LC oscillation circuit, and its frequency output is... The parameters of the detection coil and the reference coil are exactly the same, and the inductance values ​​of the two coils are equal.

[0047] S6, when no solution is being detected, the frequencies output by the two coils through the signal generation circuit are identical. .

[0048] S7, When performing solution conductivity detection, the detection coil is placed vertically directly above the horizontal liquid level of the conductive liquid to be measured. When the conductivity of the solution changes, the inductance of the detection coil will change accordingly, and the corresponding output frequency is... , This refers to the output frequency change caused by the change in coil inductance due to the change in conductivity, as described in the aforementioned coil impedance change formula. For the reference coil, its position is directly above the detection coil at a distance of 50mm to ensure it is unaffected by changes in the conductivity of the test solution or the mutual inductance of the detection coil; its corresponding output frequency remains the same. The processor performs a differential operation on the frequencies of the two signals to obtain the difference frequency value. Based on the fitted calibration curve, determine the solution conductivity corresponding to the calculated difference frequency value.

[0049] S8, Anti-interference capability: When the detection device is subjected to external interference, since the detection coil and the reference coil are in the same environment, their inductance changes are consistent, resulting in consistent output frequency changes. Let it be... Then the frequency of the signal output by the detection coil at this time is The frequency of the reference coil output is The difference frequency signal output of the two is still This achieves the goal of anti-interference.

[0050] S9, Experimental Verification: In the experiment, the detection coil was placed above the horizontal electrolyte solution plane, with a distance of 0.4 mm between the coil and the solution plane. The saline solution plane was much larger than the size of the coil. The parameters of the detection coil and the reference coil were completely identical, with the same inner radius. r 1 It is 6.2mm, outer radius r 2 The coil diameter is 12.2 mm, the coil thickness is 1.6 cm, the number of turns is 9, and the inductance of both coils is 3.3 μH. A Shanghai Leimagnetic conductivity meter (DDS-307A) was used as the reference value. Experimental data are shown in Table 1.

[0051] Table 1 This invention discloses a handheld electrolyte solution conductivity measurement system and method. The system consists of a sampling unit and a data processing unit (processor), and the entire system is powered by a single rechargeable lithium battery. The sampling unit comprises a detection coil, a reference coil, and a signal generation and processing circuit. The detection coil and reference coil are planar spiral coils fabricated on standard printed circuit boards, with identical parameters. Structurally, the detection coil is close to the solution being measured, while the reference coil maintains a certain distance from both to avoid mutual inductance interference, ensuring that the reference coil is only affected by external environmental factors such as temperature changes. During measurement, the detection coil and reference coil are sequentially connected to the signal generation and processing circuit via analog switches. The signal generation and processing circuit employs a high-precision frequency modulation circuit. The output of the sensor coil's detected signal is a frequency signal, which can be directly connected to the processor without amplification or AD conversion. Its advantages include a simple sensor circuit, direct frequency signal output, direct applicability to digital technology, easy computer interfacing, high accuracy, and strong anti-interference capabilities. When the conductivity of the solution changes, the inductance of the detection coil changes, causing a change in the circuit's output frequency. This signal can be directly connected to the processor's counter unit to obtain its frequency value without the need for signal amplification or an AD conversion module. The data processing unit performs differential calculations on the frequencies output by the detection coil and the reference coil to obtain a fitting calibration curve of the difference frequency value and conductivity. Subsequently, the conductivity of the electrolyte solution corresponding to the difference frequency signal can be determined based on the fitting calibration curve.

[0052] This invention is based on the principle of magnetic coupling resonance and employs a differential measurement method. By introducing a reference coil and a measuring coil into the same measurement circuit and placing them in the same measurement environment, the output signal is ultimately the frequency difference between the two. This method can convert environmental interference into a common-mode signal for suppression, greatly improving the system's anti-interference capability. It achieves high-precision measurement of conductivity.

[0053] The processor mentioned in this invention is a common MCU (microcontroller), which can complete the above measurement functions with the help of a specially written program.

[0054] When applying the handheld electrolyte solution conductivity measurement method provided by this invention, it is not necessary to consider... Figure 3 The steps shown are executed in sequence. The specific execution order of each step can be determined as needed, and this invention does not impose any restrictions on it.

[0055] The present invention also provides a processor, which is a 32-bit microcontroller STM32F103C8T6. The processor stores an executable program, which, when executed by the processor, implements the above-mentioned... Figure 3 A handheld method for measuring the conductivity of electrolyte solutions is provided.

[0056] The executable program is stored in the processor's internal flash memory. Functions such as controlling analog switches, acquiring frequency signals, differential calculation, data transmission and display are all implemented by the program.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this invention.

Claims

1. A handheld electrolyte solution conductivity measurement system, characterized in that, The system includes a detection coil, a reference coil, an analog switch, a signal generation and processing circuit, and a processor; the parameters of the detection coil and the reference coil are the same, and there is a preset distance between the reference coil and the detection coil and the electrolyte solution being tested; the detection coil is located near the electrolyte solution being tested. The preset interval is used to ensure that the reference coil is not affected by the mutual inductance between the electrolyte solution being tested and the detection coil; The processor controls the analog switch to sequentially connect the detection coil and the reference coil to the signal generation and processing circuit. The signal generation and processing circuit generates an electrical signal with a certain frequency corresponding to the detection coil when the detection coil is connected, and generates an electrical signal with a certain frequency corresponding to the reference coil when the reference coil is connected. The processor also collects the frequency values ​​of the two electrical signals from the detection coil and the reference coil through an internal counter unit, and performs differential calculation on the frequency values ​​of the two electrical signals to determine the conductivity of the electrolyte solution being tested.

2. The system according to claim 1, characterized in that, Both the detection coil and the reference coil are planar spiral coils made of standard printed circuit boards. The detection coil is placed vertically directly above the horizontal liquid level of the electrolyte solution being tested.

3. The system according to claim 1, characterized in that, Signal generation and processing circuits include signal generation circuits and signal processing circuits; The signal generation circuit is an LC oscillation circuit. The detection coil or reference coil, as the inductive element of the LC oscillation circuit, is connected to the LC oscillation circuit in sequence through an analog switch to generate a sinusoidal signal of a certain frequency. The signal processing circuit is a shaping circuit used to convert a sinusoidal signal into a square wave signal that the processor can recognize. The frequency of the square wave signal is the same as the output frequency of the signal generation circuit.

4. The system according to claim 3, characterized in that, The frequency of the sinusoidal signal output by the signal generation circuit is: ； in, This is the resonant capacitor of the signal generation circuit. L This is the self-inductance value of the coil. The frequency of the sinusoidal signal is denoted as .

5. The system according to claim 1, characterized in that, The system also includes a power supply; The power supply powers the analog switches, signal generation and processing circuits, and the processor.

6. The system according to claim 1, characterized in that, The system also includes a charging / data transmission interface and a display screen; A charging / data transfer interface is used for signal transmission and data exchange with external devices; The display screen is used to show the conductivity of the electrolyte solution being tested.

7. A handheld method for measuring the conductivity of an electrolyte solution, characterized in that, The method is applied to the system according to any one of claims 1-6, and the method includes: The processor controls the analog switch to connect the detection coil to the signal generation and processing circuit, so that the signal generation and processing circuit generates an electrical signal with a certain frequency that the processor can directly acquire from the detection coil. The processor controls the analog switch to disconnect the detection coil and connects the reference coil to the signal generation and processing circuit through the analog switch, so that the signal generation and processing circuit generates an electrical signal with a certain frequency from the reference coil that can be directly acquired by the processor. The processor performs differential calculations on the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil to determine the conductivity of the electrolyte solution being tested.

8. The method according to claim 7, characterized in that, The conductivity of the electrolyte solution being tested is determined by calculating the difference between the frequency values ​​corresponding to the electrical signals of the detection coil and the reference coil, including: The frequency difference value is obtained by calculating the difference between the frequency value corresponding to the electrical signal of the detection coil and the frequency value corresponding to the electrical signal of the reference coil. Obtain the fitting calibration curve; the fitting calibration curve is the relationship between the difference frequency values ​​of various samples and the conductivity of the sample electrolyte solution; The conductivity of the electrolyte solution being tested, corresponding to the difference frequency value, is determined from the fitted calibration curve.

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