Solution concentration measuring device and method

Abstract

The present application provides a measuring device and a measuring method for solution concentration, wherein the measuring device includes an excitation source, a measuring capacitor, a resistor, a collector and a controller. The excitation source is used to output a pulse voltage. The collector is used to collect the voltage of the measuring capacitor and the charging time for the voltage of the measuring capacitor to reach the trigger voltage from zero, and the controller is used to determine the internal resistance value of the measuring capacitor according to the voltage of the measuring capacitor and the voltage of the excitation source. The measured capacitance value of the measuring capacitor is determined according to the internal resistance value of the measuring capacitor, the resistance value of the resistor, the trigger voltage, the saturation voltage and the charging time. The conductivity of the measuring capacitor is determined according to the internal resistance value, and the measured capacitance value is compensated by the conductivity to obtain the compensated capacitance value, and the concentration of the solution is determined according to the compensated capacitance value. By making the excitation source output a pulse voltage, the electrode polarization effect can be reduced, and by calculating the internal resistance value and conductivity of the measuring capacitor, the influence of temperature on the measured capacitance value is fully considered, and the measurement accuracy of the solution concentration can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of solution concentration measurement, and in particular to a solution concentration measurement device and a solution concentration measurement method. Background Art

[0002] With the popularity of new energy vehicles, new energy vehicles using mixed fuels have attracted widespread attention due to their flexible fuel supply method and the ability to adjust the fuel supply ratio according to demand. During the use of mixed fuels including methanol, it is necessary to detect the methanol content in the fuel and select different combustion strategies at different methanol concentrations to improve power performance. Inaccurate detection of methanol concentration in mixed fuel solutions will affect the performance of new energy vehicles. Summary of the invention

[0003] The present application provides a device and method for measuring solution concentration to solve at least some of the problems in the related art.

[0004] On the one hand, the present application provides a device for measuring solution concentration, comprising:

[0005] An excitation source, used for outputting a pulse voltage;

[0006] Measuring capacitance, connected to the excitation source, for placement in the solution;

[0007] a resistor connected in series with the measuring capacitor;

[0008] A collector, connected to the measuring capacitor, for collecting the voltage of the measuring capacitor and the charging time of the voltage of the measuring capacitor from zero to a trigger voltage, wherein the trigger voltage is lower than the saturation voltage of the measuring capacitor;

[0009] A controller is connected to the excitation source and the collector, and is used to:

[0010] The internal resistance value of the measuring capacitor is determined according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance value of the resistor; the measuring capacitance value of the measuring capacitor is determined according to the internal resistance value of the measuring capacitor, the resistance value of the resistor, the trigger voltage, the saturation voltage, and the charging time; the conductivity of the measuring capacitor is determined according to the internal resistance value, the measuring capacitance value is compensated by the conductivity to obtain the compensated capacitance value, and the concentration of the solution is determined according to the compensated capacitance value.

[0011] Optionally, the measuring device also includes a temperature measuring instrument for measuring the temperature of the solution. The controller is also used to determine a compensation coefficient based on the temperature of the solution, and to compensate the measured capacitance value based on the conductivity and the compensation coefficient to obtain the compensated capacitance value.

[0012] Optionally, the measuring capacitor is a cylindrical capacitor; and / or

[0013] The measuring device further comprises an additional capacitor connected in parallel with the measuring capacitor.

[0014] Optionally, the controller is also used to control the duration of the pulse voltage output by the excitation source; wherein the duration of the pulse voltage is greater than the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero, and the duration of the pulse voltage is less than twice the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero.

[0015] Optionally, the measuring device further comprises a temperature measuring instrument for measuring the temperature of the solution, and the controller is further used for:

[0016] Controlling the excitation source to output a plurality of pulse voltages with different voltages, and obtaining the charging time of the measurement capacitor under the plurality of pulse voltages;

[0017] In a calibration table including a mapping relationship among calibration temperature, calibration voltage value and calibration charging time, at a calibration temperature closest to the temperature of the solution, for a plurality of voltage values ​​of the pulse voltage and corresponding calibration voltage values, respectively compare the charging time and the calibration charging time, and select the voltage value of the pulse voltage corresponding to the charging time closest to the calibration charging time as the selected voltage;

[0018] The excitation source is controlled to output the selected voltage to measure the concentration of the solution.

[0019] Optionally, the calibration table is obtained by a calibration method, and the calibration method includes:

[0020] For a plurality of solutions with different calibration temperatures and different calibration concentrations, the calibration voltage value and the calibration charging time are determined respectively, including:

[0021] For each calibration temperature and calibration concentration, the excitation source is controlled to apply a plurality of test pulse voltages of different voltage values ​​to the measuring capacitor;

[0022] Respectively determine a plurality of charging curves corresponding to a plurality of test pulse voltages with different voltage values;

[0023] Dividing the time interval of the plurality of charging curves from the voltage being zero to the voltage being the saturation voltage into five time constant intervals;

[0024] The test pulse voltage corresponding to the charging curve of the test charging time of the measuring capacitor in the second time constant interval is selected as the calibration voltage value at the calibration temperature and calibration concentration, and the test charging time is used as the calibration charging time. The test charging time is the time it takes for the voltage of the measuring capacitor to charge from zero to reach the trigger voltage.

[0025] On the other hand, the present application provides a method for measuring solution concentration, which is applied to the above solution concentration measuring device, and the measuring method comprises:

[0026] Controlling the excitation source to output a pulse voltage to charge the measuring capacitor placed in the solution;

[0027] collecting the voltage of the measuring capacitor;

[0028] Collecting the charging time for the voltage of the measuring capacitor to reach a trigger voltage from zero, wherein the trigger voltage is lower than the saturation voltage of the measuring capacitor;

[0029] Determining the internal resistance value of the measuring capacitor according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance value of the resistor;

[0030] Determining a measured capacitance value of the measuring capacitor according to an internal resistance value of the measuring capacitor, a resistance value of the resistor, the trigger voltage, a saturation voltage and the charging time;

[0031] The conductivity of the measured capacitor is determined according to the internal resistance value, the measured capacitance value is compensated by using the conductivity to obtain a compensated capacitance value, and the concentration of the solution is determined according to the compensated capacitance value.

[0032] Optionally, the measuring method further includes:

[0033] The temperature of the solution is obtained, a compensation coefficient is determined according to the temperature of the solution, and the measured capacitance value is compensated according to the conductivity and the compensation coefficient to obtain the compensated capacitance value.

[0034] Optionally, controlling the excitation source to output a pulse voltage includes:

[0035] Controlling the duration of the pulse voltage output by the excitation source;

[0036] The duration of the pulse voltage is greater than the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero, and the duration of the pulse voltage is less than twice the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero.

[0037] Optionally, the measuring method further includes:

[0038] Controlling the excitation source to output a plurality of pulse voltages with different voltages, and obtaining the charging time of the measurement capacitor under the plurality of pulse voltages;

[0039] In a calibration table including a mapping relationship among calibration temperature, calibration voltage value and calibration charging time, at a calibration temperature closest to the temperature of the solution, for a plurality of voltage values ​​of the pulse voltage and corresponding calibration voltage values, respectively compare the charging time and the calibration charging time, and select the voltage value of the pulse voltage corresponding to the charging time closest to the calibration charging time as the selected voltage;

[0040] The excitation source is controlled to output the selected voltage to measure the concentration of the solution.

[0041] Optionally, the calibration table is obtained by a calibration method, and the calibration method includes:

[0042] For a plurality of solutions with different calibration temperatures and different calibration concentrations, the calibration voltage value and the calibration charging time are determined respectively, including:

[0043] For each calibration temperature and calibration concentration, the excitation source is controlled to apply a plurality of test pulse voltages of different voltage values ​​to the measuring capacitor;

[0044] Respectively determine a plurality of charging curves corresponding to a plurality of test pulse voltages with different voltage values;

[0045] Dividing the time interval of the plurality of charging curves from the voltage being zero to the voltage being the saturation voltage into five time constant intervals;

[0046] The test pulse voltage corresponding to the charging curve of the test charging time of the measuring capacitor in the second time constant interval is selected as the calibration voltage value at the calibration temperature and calibration concentration, and the test charging time is used as the calibration charging time. The test charging time is the time it takes for the voltage of the measuring capacitor to charge from zero to reach the trigger voltage.

[0047] Compared with the related art, the measuring device of solution concentration provided by the present application, by making the excitation source output pulse voltage, charging the measuring capacitor, can avoid the formation of a stable charge layer on the electrode surface of the measuring capacitor during the charging process, so as to reduce the electrode polarization effect and improve the accuracy of the measurement result. And the voltage of the measuring capacitor and the charging time of the voltage of the measuring capacitor from zero to the trigger voltage are collected by the collector, and the internal resistance value of the measuring capacitor is determined according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance value of the resistor, not only can the measuring capacitance value of the measuring capacitor be determined according to the internal resistance value of the measuring capacitor, the resistance value of the resistor, the trigger voltage, the saturation voltage and the charging time, but also the conductivity of the measuring capacitor can be determined according to the internal resistance value of the measuring capacitor, and the measuring capacitance value is compensated by the conductivity to obtain the compensation capacitance value, and the concentration of the solution is determined according to the compensation capacitance value. By using conductivity compensation, the conductivity of the solution is different when the temperature is different, which causes the problem that the measuring capacitance value of the measuring capacitor is different, so that the true and accurate solution concentration is determined according to the compensation capacitance value. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0049] Figure 1 A schematic diagram of the structure of a device for measuring solution concentration shown in an embodiment;

[0050] Figure 2 A schematic diagram of a charging curve for measuring capacitance;

[0051] Figure 3 A schematic diagram of the structure of a device for measuring solution concentration shown in another embodiment;

[0052] Figure 4 A schematic flow chart of a method for measuring solution concentration shown in an embodiment;

[0053] Figure 5 for Figure 4 A schematic flow chart of an embodiment of step 20 in the method for measuring solution concentration shown;

[0054] Figure 6 for Figure 5 A schematic flow chart of an embodiment of a calibration method in a method for measuring solution concentration is shown.

[0055] Reference numerals:

[0056] Measuring device 1, excitation source 2, measuring capacitor 3, resistor 4, collector 5, controller 6, additional capacitor 7, temperature measuring instrument 8. DETAILED DESCRIPTION

[0057] The present application provides a solution concentration measuring device and a measuring method. The solution concentration measuring device and the measuring method of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0058] In one aspect, an embodiment of the present application provides a device for measuring the concentration of a solution. The device comprises:

[0059] An excitation source, used for outputting a pulse voltage;

[0060] To measure capacitance, connect the excitation source and place it in the solution;

[0061] A resistor, connected in series with the measuring capacitor;

[0062] A collector is connected to the measuring capacitor and is used to collect the voltage of the measuring capacitor and the charging time of the voltage of the measuring capacitor from zero to a trigger voltage, wherein the trigger voltage is lower than the saturation voltage of the measuring capacitor;

[0063] The controller is connected with the excitation source and the collector and is used for:

[0064] The internal resistance value of the measuring capacitor is determined according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance value of the resistor; the measuring capacitance value of the measuring capacitor is determined according to the internal resistance value of the measuring capacitor, the resistance value of the resistor, the trigger voltage, the saturation voltage, and the charging time; the conductivity of the measuring capacitor is determined according to the internal resistance value, the measuring capacitance value is compensated by the conductivity to obtain the compensated capacitance value, and the concentration of the solution is determined according to the compensated capacitance value.

[0065] The solution concentration measuring device provided in the present application can avoid the formation of a stable charge layer on the electrode surface of the measuring capacitor during the charging process by causing the excitation source to output a pulse voltage to charge the measuring capacitor, thereby reducing the electrode polarization effect and improving the accuracy of the measurement result.

[0066] The voltage of the measuring capacitor and the charging time from zero to the trigger voltage are collected by the collector, and the internal resistance of the measuring capacitor is determined according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance of the resistor. Not only can the measured capacitance of the measuring capacitor be determined according to the internal resistance of the measuring capacitor, the resistance of the resistor, the trigger voltage, the saturation voltage, and the charging time, but also the conductivity of the measuring capacitor can be determined according to the internal resistance of the measuring capacitor, and the measured capacitance value is compensated by the conductivity to obtain the compensated capacitance value, and the concentration of the solution is determined according to the compensated capacitance value. The measured resistance value of the measuring capacitor is obtained by calculating the internal resistance of the measuring capacitor and the conductivity of the measuring capacitor, and the measured capacitance value is compensated by the conductivity. The problem that the conductivity of the solution is different at different temperatures, resulting in different measured capacitance values ​​of the measuring capacitor, is fully considered, so that the true and accurate solution concentration is determined according to the compensated capacitance value.

[0067] Please refer to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of a structure of a solution concentration measuring device 1 shown in an embodiment. Figure 1 In the illustrated embodiment, the measuring device 1 includes an excitation source 2 , a measuring capacitor 3 , a resistor 4 , a collector 5 and a controller 6 .

[0068] The excitation source 2 is used to output a pulse voltage. The measuring capacitor 3 is connected to the excitation source 2 and is placed in the solution. The resistor 4 is connected in series with the measuring capacitor 3. The collector 5 is connected to the measuring capacitor 3 and is used to collect the voltage of the measuring capacitor 3 and the charging time for the voltage of the measuring capacitor 3 to reach the trigger voltage from zero, and the trigger voltage is lower than the saturation voltage of the measuring capacitor. The controller 6 is connected to the excitation source 2 and the collector 5, and is used to determine the internal resistance value of the measuring capacitor 3 according to the voltage of the measuring capacitor 3, the voltage of the excitation source 2, and the resistance value of the resistor 4. The measuring capacitance value of the measuring capacitor 3 is determined according to the internal resistance value of the measuring capacitor 3, the resistance value of the resistor 4, the trigger voltage, the saturation voltage and the charging time. The conductivity of the measuring capacitor 3 is determined according to the internal resistance value, and the measuring capacitance value is compensated by the conductivity to obtain the compensated capacitance value, and the concentration of the solution is determined according to the compensated capacitance value.

[0069] The measuring device 1 of the solution concentration provided in the present application determines the concentration of the solution by determining the capacitance value of the measuring capacitor 3 located in the solution. The principle is that the dielectric constants of the same solution of different concentrations are different, and the measuring capacitor 3 includes two plates, and the medium between the two plates is a solution. The concentration of the solution is different, and the dielectric constant of the measuring capacitor 3 composed of the solution and the plate is different, so that the capacitance value of the measuring capacitor 3 is different. By charging the measuring capacitor 3 placed in the solution, the capacitance value of the measuring capacitor 3 can be obtained, and then according to the correspondence between the solution concentration and the capacitance value pre-calibrated, the concentration of the solution is determined according to the capacitance value of the measuring capacitor 3.

[0070] The measuring device 1 of the solution concentration provided by the present application, the excitation source 2 is a pulse voltage source, which is used to output a pulse voltage. By making the excitation source 2 output a pulse voltage to charge the measuring capacitor 3, compared with using a DC voltage to charge the measuring capacitor 3, it is possible to avoid the formation of a stable charge layer on the electrode surface of the measuring capacitor 3 during the charging process, so as to reduce the electrode polarization effect and improve the accuracy of the measurement result. Compared with using an AC voltage to charge the measuring capacitor 3, the dielectric loss of the medium can be reduced, the accuracy of the measurement result can be improved, and the required measuring instrument is small, and only an instrument for collecting voltage value and time is required, without using a complex LCR meter.

[0071] The resistor 4 is connected in series with the measuring capacitor 3. The measuring capacitor 3, the resistor 4 and the excitation source 2 form an RC circuit. When the excitation source 2 outputs a pulse voltage, the excitation source 2 charges the measuring capacitor 3, so that the voltage value of the measuring capacitor 3 increases from zero to the saturation voltage of the measuring capacitor 3. When the excitation source 2 stops charging the measuring capacitor 3, the measuring capacitor 3 is discharged, so that the voltage of the measuring capacitor 3 drops to zero.

[0072] The collector 5 is connected to the measuring capacitor 3, and is used to collect the voltage of the measuring capacitor 3 and the charging time of the voltage of the measuring capacitor 3 from zero to the trigger voltage. The collector 5 has a voltage acquisition function and a time acquisition function. In the present embodiment, the collector 5 is an oscilloscope, which can collect the voltage of the measuring capacitor 3 in real time, and can reflect the time corresponding to each voltage point in the voltage curve of the measuring capacitor 3. Therefore, the collector 5 can collect the charging time of the voltage of the measuring capacitor 3 from zero to the trigger voltage, wherein the trigger voltage is lower than the saturation voltage of the measuring capacitor 3. In other embodiments, the collector 5 includes a voltage collector and a time collector, and the voltage is collected by the voltage collector and the time corresponding to the voltage point is collected by the time collector. This application is not limited to this.

[0073] Please refer to Figure 2 , Figure 2 Schematic diagram of measuring the charging curve of capacitor 3. In the figure, the horizontal axis represents time and the vertical axis represents voltage value. Figure 2 It can be seen from the charging curve shown that during the charging process, the voltage value at both ends of the measuring capacitor 3 rises from zero to the saturation voltage and then stops rising. In the present embodiment, the trigger voltage is 63.2% of the saturation voltage, and the charging time is the charging time for the voltage value of the measuring capacitor 3 to reach 63.2% of the saturation voltage from zero. 63.2% of the saturation voltage is selected as the trigger voltage, because the time point corresponding to 63.2% of the saturation voltage is a significant characteristic point in the capacitor charging process, which can reflect the combined influence of the capacitor and the resistor 4, and this point is relatively early, and it is easy to obtain a stable reading during measurement, avoiding noise and interference that may occur when approaching voltage saturation.

[0074] The internal resistance value of the measuring capacitor 3 is determined by collecting the voltage of the measuring capacitor 3 during the charging process and combining the voltage of the excitation source 2 and the resistance value of the resistor 4. When the voltage value of the measuring capacitor 3 is close to the saturation voltage, the voltage of the excitation source 2 minus the voltage of the measuring capacitor 3 is the voltage across the resistor 4. The internal resistance value of the measuring capacitor 3 can be determined by measuring the proportional relationship between the voltage of the measuring capacitor 3 and the voltage across the resistor 4 and the resistance value of the resistor 4.

[0075] The capacitance value of the measuring capacitor 3 is determined according to the internal resistance value of the measuring capacitor 3, the resistance value of the resistor 4, the trigger voltage, the saturation voltage and the charging time. Specifically, the calculation formula is:

[0076]

[0077] in, is the trigger voltage value, is the saturation voltage value, is the charging time from the voltage of the measuring capacitor 3 from zero to the trigger voltage, is the resistance value of resistor 4, and r is the internal resistance value of measuring capacitor 3. The measuring capacitance value of measuring capacitor 3 is obtained by collecting the saturation voltage value of measuring capacitor 3 and the trigger voltage value of measuring capacitor 3 and the time point corresponding to the trigger voltage value during the charging process, combining the resistance parameter of resistor 4 and the calculated internal resistance value of measuring capacitor 3.

[0078] The internal resistance value of the measuring capacitor 3 is related to the conductivity of the measuring capacitor 3, the area through which the current flows when the measuring capacitor 3 is charged, and the length through which the current flows. Specifically, the internal resistance value of the measuring capacitor 3 is the product of the length through which the current flows divided by the conductivity and the area through which the current flows. When the measuring capacitor 3 is a flat plate capacitor, the length through which the current flows is the spacing between the two pole plates, and the area through which the current flows is the area of ​​the pole plates. When the measuring capacitor 3 is a cylindrical capacitor, the length through which the current flows is the height of the cylinder, and the area through which the current flows is the lateral area of ​​the cylinder with a smaller radius. According to the internal resistance value of the measuring capacitor 3, the structural parameters of the capacitor 3 can be measured, and the conductivity of the measuring capacitor 3 can be calculated.

[0079] The measured capacitance value is compensated by using the conductivity to obtain a compensated capacitance value. Specifically, the compensated capacitance value is the measured capacitance value plus the product of the measured capacitance value multiplied by the compensation coefficient and the conductivity.

[0080] In this patent application, full consideration is given to the problem that the conductivity of the solution is different at different temperatures, resulting in different measured capacitance values ​​of the measuring capacitor 3 at the same concentration. By determining the internal resistance and conductivity of the measuring capacitor, the influence of the temperature factor related to the measured capacitance value can be compensated, so that the compensated capacitance value is only related to the concentration of the solution and has nothing to do with the temperature of the solution, and then the true and accurate solution concentration is determined based on the compensated capacitance value.

[0081] Please refer to Figure 3 , Figure 3 FIG. 1 is a schematic diagram of the structure of a solution concentration measuring device 1 shown in another embodiment. Figure 3 In the embodiment shown, the measuring device 1 further includes a temperature measuring instrument 8 for measuring the temperature of the solution, and the controller 6 is further used to determine the compensation coefficient according to the temperature of the solution, and to compensate the measured capacitance value according to the conductivity and the compensation coefficient to obtain the compensated capacitance value. In this way, different compensation coefficients are determined according to different temperatures, and the measured capacitance value can be compensated more accurately.

[0082] In some embodiments, the measuring capacitor 3 is a cylindrical capacitor. The cylindrical design is relatively simple and easy to manufacture and assemble. The cylindrical capacitor can provide a larger effective contact area, improve the interaction between the solution and the electrode, and enhance the measurement signal.

[0083] exist Figure 3 In the illustrated embodiment, the measuring device 1 further comprises an additional capacitor 7, which is connected in parallel with the measuring capacitor 3. After being connected in parallel with the measuring capacitor 3, it is connected in series with the resistor 4. By setting the additional capacitor 7, and the additional capacitor 7 is connected in parallel with the measuring capacitor 3, the capacitance value after parallel connection is the sum of the capacitance value of the measuring capacitor 3 and the capacitance value of the additional capacitor 7, and the capacitance base of the measurement can be increased. The excitation source 2 is used to charge both the measuring capacitor 3 and the additional capacitor 7, and the collector 5 collects the voltage at both ends of the capacitor after parallel connection and the charging time of the voltage of the capacitor after parallel connection from zero to the trigger voltage, which can make the charging curve of the capacitor after parallel connection slow down, facilitate sampling, and improve sampling accuracy. The parallel capacitor can also effectively filter out high-frequency noise, reduce interference in the signal, improve the purity of the measuring signal, and improve the accuracy and stability of the capacitance value measurement by reducing the influence of noise.

[0084] In some embodiments, the controller 6 is further used to control the duration of the pulse voltage output by the excitation source 2. The duration of the pulse voltage is greater than the duration of the voltage of the measuring capacitor 3 reaching the saturation voltage from zero, and the duration of the pulse voltage is less than twice the duration of the voltage of the measuring capacitor 3 reaching the saturation voltage from zero.

[0085] By making the controller 6 control the duration of the pulse voltage output by the excitation source 2, the duration of the pulse voltage is greater than the duration of the voltage of the measuring capacitor 3 reaching the saturation voltage from zero, so that the duration of the pulse voltage output by the excitation source 2 is not too short, and the voltage of the measuring capacitor 3 cannot reach the saturation voltage. By making the duration of the pulse voltage less than twice the duration of the voltage of the measuring capacitor 3 reaching the saturation voltage from zero, it is possible to avoid the duration of the pulse voltage output by the excitation source 2 being too long, and charging the measuring capacitor 3 for a long time after the measuring capacitor 3 is already fully charged, so that the measuring capacitor 3 is polarized due to the long charging time.

[0086] Because the time required for the measuring capacitor 3 to reach the saturation state in solutions of different concentrations is different, the time required for the measuring capacitor 3 to reach the saturation state in a solution with a high concentration is longer than the time required for the measuring capacitor 3 to reach the saturation state in a solution with a low concentration. In order to enable the measuring device 1 to measure the concentrations of solutions of all concentrations, the duration of the pulse voltage is made longer than the time it takes for the voltage of the measuring capacitor 3 in a solution with a concentration of 100% to reach the saturation voltage from zero, and the duration of the pulse voltage is made shorter than twice the time it takes for the voltage of the measuring capacitor 3 in a solution with a concentration of 100% to reach the saturation voltage from zero.

[0087] In solutions of different concentrations and temperatures, the capacitance value of the measuring capacitor 3 is different. When the capacitance value of the measuring capacitor 3 is small and when the capacitance value is large, the required pulse voltage is also different. When the corresponding measuring capacitor 3 is charged with an appropriate pulse voltage, the point corresponding to the trigger voltage and the charging time in the corresponding charging curve can be located at a place with a larger slope on the curve, which is convenient for sampling.

[0088] In some embodiments, the measuring device 1 further includes a temperature measuring instrument 8 for measuring the temperature of the solution, and the controller 6 is further used to control the excitation source 2 to output a plurality of pulse voltages with different voltages, and obtain the charging time of the measuring capacitor 3 under the plurality of pulse voltages. Specifically, each pulse voltage has a corresponding charging time.

[0089] Obtain the temperature of the solution, and in a calibration table including a mapping relationship between calibration temperature, calibration voltage value and calibrated charging time, at a calibration temperature closest to the temperature of the solution, compare the charging time and the calibrated charging time for multiple pulse voltage values ​​and corresponding calibrated voltage values, and select the voltage value of the pulse voltage corresponding to the charging time closest to the calibrated charging time as the selected voltage.

[0090] Among them, the calibration table includes a calibration temperature, a calibration voltage value and a calibration charging time, and may also include a calibration concentration. Among them, each calibration temperature and each calibration concentration corresponds to a calibration voltage value and a calibration charging time at the calibration voltage value. The calibration voltage value is a suitable charging voltage for measuring the capacitor 3 under a solution of the corresponding calibration temperature and calibration concentration, and the calibration charging time is the charging time at the calibration voltage.

[0091] For the voltage values ​​of multiple pulse voltages and the corresponding calibrated voltage values, the charging time and the calibrated charging time are compared respectively. Among them, the voltage values ​​of multiple pulse voltages can be equal to multiple calibrated voltage values ​​one by one. In this way, according to each pulse voltage value, a calibrated voltage value equal to the pulse voltage value is determined, and the charging time under the pulse voltage value and the calibrated charging time under the calibrated voltage value are compared respectively, and the voltage value of the pulse voltage corresponding to the charging time closest to the calibrated charging time is selected as the selected voltage.

[0092] The voltage values ​​of multiple pulse voltages may not be equal to multiple calibrated voltage values. A calibrated voltage value close to each pulse voltage value can be determined, and the charging time under the pulse voltage value and the calibrated charging time under the calibrated voltage value can be compared respectively. The voltage value of the pulse voltage corresponding to the charging time closest to the calibrated charging time can be selected as the selected voltage.

[0093] When the temperature is close to or equal to the calibration temperature and the pulse voltage value is close to or equal to the calibration voltage value, the charging time is close to the calibrated charging time, which means that the concentration of the solution is also close to the calibrated concentration corresponding to the calibration temperature, the calibrated voltage value and the calibrated charging time. Selecting a pulse voltage suitable for the calibration temperature and the calibrated concentration is also suitable for the solution, which can improve the sampling accuracy and further improve the measurement accuracy.

[0094] In some embodiments, the calibration table is obtained by a calibration method, and the calibration method includes:

[0095] For a plurality of solutions with different calibration temperatures and different calibration concentrations, the calibration voltage value and the calibration charging time are determined respectively, including:

[0096] For each calibration temperature and calibration concentration, the excitation source 2 is controlled to apply a plurality of test pulse voltages with different voltage values ​​to the measuring capacitor 3 respectively.

[0097] A plurality of charging curves corresponding to the test pulse voltages of a plurality of different voltage values ​​are respectively determined.

[0098] The time interval from the voltage being zero to the voltage being saturated voltage of multiple charging curves is divided into five time constant intervals, such as Figure 2 As shown, each τ is a time constant interval.

[0099] The test pulse voltage corresponding to the charging curve of the test charging time of the measuring capacitor 3 in the second time constant interval is selected as the calibration voltage value at the calibration temperature and calibration concentration, and the test charging time is used as the calibration charging time. The test charging time is the time it takes for the voltage of the measuring capacitor 3 to charge from zero to reach the trigger voltage.

[0100] Another aspect of the present application provides a method for measuring solution concentration, which is applied to a device for measuring solution concentration. Figure 4 , Figure 4 FIG. 1 is a flow chart of a method for measuring solution concentration shown in an embodiment. Figure 4 In the illustrated embodiment, the measuring method 10 includes steps 20 to 50 .

[0101] Step 20, controlling the excitation source to output a pulse voltage to charge the measurement capacitor placed in the solution.

[0102] Step 30, collecting and measuring the voltage of the capacitor.

[0103] Step 40 , collecting the charging time for the voltage of the measuring capacitor to reach a trigger voltage from zero, where the trigger voltage is lower than the saturation voltage of the measuring capacitor.

[0104] Step 50, determining the internal resistance of the measuring capacitor according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance of the resistor 4. Determine the measured capacitance of the measuring capacitor according to the internal resistance of the measuring capacitor, the resistance of the resistor, the trigger voltage, the saturation voltage, and the charging time. Determine the conductivity of the measuring capacitor according to the internal resistance, compensate the measuring capacitance value using the conductivity, obtain the compensated capacitance value, and determine the concentration of the solution according to the compensated capacitance value.

[0105] In some embodiments, the measurement method further includes: acquiring the temperature of the solution, determining a compensation coefficient according to the temperature of the solution, and compensating the measured capacitance value according to the conductivity and the compensation coefficient to obtain a compensated capacitance value.

[0106] In some embodiments, controlling the excitation source to output a pulse voltage includes: controlling the duration of the pulse voltage output by the excitation source, wherein the duration of the pulse voltage is greater than the duration for the voltage of the measuring capacitor to reach the saturation voltage from zero, and the duration of the pulse voltage is less than twice the duration for the voltage of the measuring capacitor to reach the saturation voltage from zero.

[0107] Please refer to Figure 5 , Figure 5 for Figure 4 FIG. 1 is a flow chart showing an embodiment of step 20 in the method for measuring the concentration of a solution. Figure 5 In the illustrated embodiment, step 20 controls the excitation source to output a pulse voltage to charge the measuring capacitor placed in the solution, including steps 21 to 23 .

[0108] Step 21, controlling the excitation source to output a plurality of pulse voltages with different voltages, and obtaining the charging time of the measurement capacitor under the plurality of pulse voltages.

[0109] Step 22, in a calibration table including a mapping relationship among calibration temperature, calibration voltage value and calibration charging time, at a calibration temperature closest to the temperature of the solution, for voltage values ​​of multiple pulse voltages and corresponding calibration voltage values, respectively compare the charging time and the calibrated charging time, and select the voltage value of the pulse voltage corresponding to the charging time closest to the calibrated charging time as the selected voltage.

[0110] Step 23, controlling the excitation source to output a selected voltage to measure the concentration of the solution.

[0111] In some embodiments, the calibration table is obtained by a calibration method. Figure 6 , Figure 6 for Figure 5 A flow chart of an embodiment of a calibration method in a method for measuring solution concentration is shown. Figure 6In the illustrated embodiment, the calibration method 60 determines the calibration voltage value and the calibration charging time for a plurality of solutions with different calibration temperatures and different calibration concentrations, respectively, and includes steps 61 to 64 .

[0112] Step 61: for each calibration temperature and calibration concentration, control the excitation source to apply a plurality of test pulse voltages with different voltage values ​​to the measuring capacitor.

[0113] Step 62, respectively determine a plurality of charging curves corresponding to a plurality of test pulse voltages of different voltage values.

[0114] Step 63: Divide the time interval of the multiple charging curves from the voltage being zero to the voltage being the saturation voltage into five time constant intervals.

[0115] Step 64, select the test pulse voltage corresponding to the charging curve of the test charging time of the measuring capacitor within the second time constant interval as the calibration voltage value at the calibration temperature and calibration concentration, and use the test charging time as the calibration charging time. The test charging time is the time it takes for the voltage of the measuring capacitor to charge from zero to reach the trigger voltage.

[0116] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0117] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A device for measuring solution concentration, characterized in that: The measuring device comprises: An excitation source, used for outputting a pulse voltage; Measuring capacitance, connected to the excitation source, for placement in the solution; a resistor connected in series with the measuring capacitor; A collector, connected to the measuring capacitor, for collecting the voltage of the measuring capacitor and the charging time of the voltage of the measuring capacitor from zero to a trigger voltage, wherein the trigger voltage is lower than the saturation voltage of the measuring capacitor; A controller is connected to the excitation source and the collector, and is used to: Determine the internal resistance of the measuring capacitor according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance of the resistor; determine the measured capacitance of the measuring capacitor according to the internal resistance of the measuring capacitor, the resistance of the resistor, the trigger voltage, the saturation voltage, and the charging time; determine the conductivity of the measuring capacitor according to the internal resistance, compensate the measuring capacitance value using the conductivity to obtain a compensated capacitance value, and determine the concentration of the solution according to the compensated capacitance value; The measured capacitance value of the measured capacitor is determined according to the internal resistance value of the measured capacitor, the resistance value of the resistor, the trigger voltage, the saturation voltage and the charging time, as follows: in, is the trigger voltage value, is the saturation voltage value, is the charging time from when the voltage of the measuring capacitor reaches the trigger voltage value from zero, is the resistance value of the resistor, and r is the internal resistance value of the measuring capacitor; The measured capacitance value is compensated by using the conductivity to obtain a compensated capacitance value: the compensated capacitance value is the measured capacitance value plus the product of the measured capacitance value multiplied by a compensation coefficient and the conductivity.

2. The solution concentration measuring device according to claim 1, characterized in that: The measuring device also includes a temperature measuring instrument for measuring the temperature of the solution. The controller is also used to determine a compensation coefficient according to the temperature of the solution, and to compensate the measured capacitance value according to the conductivity and the compensation coefficient to obtain the compensated capacitance value.

3. The solution concentration measuring device according to claim 1, characterized in that: The measuring capacitor is a cylindrical capacitor; and / or The measuring device further comprises an additional capacitor connected in parallel with the measuring capacitor.

4. The solution concentration measuring device according to claim 1, characterized in that: The controller is also used to control the duration of the pulse voltage output by the excitation source; wherein the duration of the pulse voltage is greater than the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero, and the duration of the pulse voltage is less than twice the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero.

5. The solution concentration measuring device according to claim 1, characterized in that: The measuring device further comprises a temperature measuring instrument for measuring the temperature of the solution, and the controller is further used for: Controlling the excitation source to output a plurality of pulse voltages with different voltages, and obtaining the charging time of the measurement capacitor under the plurality of pulse voltages; In a calibration table including a mapping relationship among calibration temperature, calibration voltage value and calibration charging time, at a calibration temperature closest to the temperature of the solution, for a plurality of voltage values ​​of the pulse voltage and corresponding calibration voltage values, respectively compare the charging time and the calibration charging time, and select the voltage value of the pulse voltage corresponding to the charging time closest to the calibration charging time as the selected voltage; The excitation source is controlled to output the selected voltage to measure the concentration of the solution.

6. The solution concentration measuring device according to claim 5, characterized in that: The calibration table is obtained by a calibration method, and the calibration method includes: For a plurality of solutions with different calibration temperatures and different calibration concentrations, the calibration voltage value and the calibration charging time are determined respectively, including: For each calibration temperature and calibration concentration, the excitation source is controlled to apply a plurality of test pulse voltages of different voltage values ​​to the measuring capacitor; Respectively determine a plurality of charging curves corresponding to a plurality of test pulse voltages with different voltage values; Dividing the time interval of the plurality of charging curves from the voltage being zero to the voltage being the saturation voltage into five time constant intervals; The test pulse voltage corresponding to the charging curve of the test charging time of the measuring capacitor in the second time constant interval is selected as the calibration voltage value at the calibration temperature and calibration concentration, and the test charging time is used as the calibration charging time. The test charging time is the time it takes for the voltage of the measuring capacitor to charge from zero to reach the trigger voltage.

7. A method for measuring solution concentration, applied to the device for measuring solution concentration as claimed in claim 1, characterized in that: The measuring method comprises: Controlling the excitation source to output a pulse voltage to charge the measuring capacitor placed in the solution; collecting the voltage of the measuring capacitor; Collecting the charging time for the voltage of the measuring capacitor to reach a trigger voltage from zero, wherein the trigger voltage is lower than the saturation voltage of the measuring capacitor; Determining the internal resistance value of the measuring capacitor according to the voltage of the measuring capacitor, the voltage of the excitation source, and the resistance value of the resistor; Determining a measured capacitance value of the measuring capacitor according to an internal resistance value of the measuring capacitor, a resistance value of the resistor, the trigger voltage, a saturation voltage and the charging time; Determining the conductivity of the measured capacitor according to the internal resistance value, compensating the measured capacitance value using the conductivity to obtain a compensated capacitance value, and determining the concentration of the solution according to the compensated capacitance value; The measured capacitance value of the measured capacitor is determined according to the internal resistance value of the measured capacitor, the resistance value of the resistor, the trigger voltage, the saturation voltage and the charging time, as follows: in, is the trigger voltage value, is the saturation voltage value, is the charging time from when the voltage of the measuring capacitor reaches the trigger voltage value from zero, is the resistance value of the resistor, and r is the internal resistance value of the measuring capacitor; The measured capacitance value is compensated by using the conductivity to obtain a compensated capacitance value: the compensated capacitance value is the measured capacitance value plus the product of the measured capacitance value multiplied by a compensation coefficient and the conductivity.

8. The method for measuring solution concentration according to claim 7, characterized in that: The measuring method further comprises: The temperature of the solution is obtained, a compensation coefficient is determined according to the temperature of the solution, and the measured capacitance value is compensated according to the conductivity and the compensation coefficient to obtain the compensated capacitance value.

9. The method for measuring solution concentration according to claim 8, characterized in that: The controlling the excitation source to output a pulse voltage comprises: Controlling the duration of the pulse voltage output by the excitation source; The duration of the pulse voltage is greater than the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero, and the duration of the pulse voltage is less than twice the time it takes for the voltage of the measuring capacitor to reach the saturation voltage from zero.

10. The method for measuring solution concentration according to claim 7, characterized in that: The measuring method further comprises: Controlling the excitation source to output a plurality of pulse voltages with different voltages, and obtaining the charging time of the measurement capacitor under the plurality of pulse voltages; In a calibration table including a mapping relationship among calibration temperature, calibration voltage value and calibration charging time, at a calibration temperature closest to the temperature of the solution, for a plurality of voltage values ​​of the pulse voltage and corresponding calibration voltage values, respectively compare the charging time and the calibration charging time, and select the voltage value of the pulse voltage corresponding to the charging time closest to the calibration charging time as the selected voltage; The excitation source is controlled to output the selected voltage to measure the concentration of the solution.

11. The method for measuring solution concentration according to claim 10, characterized in that: The calibration table is obtained by a calibration method, and the calibration method includes: For a plurality of solutions with different calibration temperatures and different calibration concentrations, the calibration voltage value and the calibration charging time are determined respectively, including: For each calibration temperature and calibration concentration, the excitation source is controlled to apply a plurality of test pulse voltages of different voltage values ​​to the measuring capacitor; Respectively determine a plurality of charging curves corresponding to a plurality of test pulse voltages with different voltage values; Dividing the time interval of the plurality of charging curves from the voltage being zero to the voltage being the saturation voltage into five time constant intervals; The test pulse voltage corresponding to the charging curve of the test charging time of the measuring capacitor in the second time constant interval is selected as the calibration voltage value at the calibration temperature and calibration concentration, and the test charging time is used as the calibration charging time. The test charging time is the time it takes for the voltage of the measuring capacitor to charge from zero to reach the trigger voltage.

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