Low voltage compensation method for zirconia humidity sensor

Abstract

The present application relates to a kind of zirconium oxide humidity sensor low pressure compensation method, the method includes the following steps, step 1: first need to the current calibration of sensor, ensure the consistency of sensor, the current of sensor in different states is measured and calibrated to target current;Step 2: measure current pressure or user input current pressure P, standard atmospheric pressure atm is calculated to obtain oxygen vector [K,B];Step 3: the coherence of humidity and oxygen is analyzed using PLSR algorithm, and the principal component regression of PLSR algorithm is obtained to exist interference parameter, and more parameter is used to fit PLS model coefficient [A,B,C,D,E] with pressure;Step 4: oxygen concentration and humidity are calculated by the vector obtained in step 2 and 3;Step 5: in different pressure environment, the same coefficient can also be measured accurately oxygen concentration and humidity;Step 6: when sensor batch changes, only current calibration is needed, and the vector of step 2,3 is also applicable.

Description

TECHNICAL FIELD

[0001] The application relates to a compensation method, in particular to a zirconia humidity sensor low-pressure compensation method, and belongs to the technical field of humidity measurement. BACKGROUND

[0002] Humidity measurement is widely used in various industries. In industrial applications, the temperature and pressure are relatively extreme. Generally, the temperature is above 120 DEG C, and due to different locations and working conditions, the pressure can be as low as 70 kPa or even lower. Ordinary sensors cannot withstand high temperatures, and the zirconia limit current sensor measurement principle well solves the temperature problem. Current zirconia humidity sensors obtain corresponding currents by catalyzing oxygen molecules and water molecules into oxygen ions under different voltages. The pure oxygen concentration and water-oxygen mixed concentration are calculated through a fitting formula, and finally the humidity is calculated by subtraction. Most current technologies obtain calibration coefficients through calibration under standard atmospheric pressure. The concentration in a certain pressure range can be corrected through a simple pressure quadratic compensation formula, but if the pressure difference is too large, recalibration is required. Under the existing calibration algorithm, in different application scenarios and different regions, there is a large pressure difference, which can cause nonlinearity between the measured humidity and the standard humidity. The pressure causes nonlinearity of the concentration, and the coherence between water and oxygen also changes. The ordinary quadratic fitting algorithm cannot solve the problem of inaccurate measurement results. To solve this problem, we abandon the existing calibration algorithm and compensation formula. The current is calibrated instead of directly calibrating humidity and oxygen. The relationship between pressure and conversion coefficient is calculated, oxygen is linearly fitted, and humidity is PLS calculated, thereby effectively solving the nonlinearity problem in different pressure environments. SUMMARY

[0003] The present application is exactly aimed at the problems existing in the prior art, and provides a zirconia humidity sensor low-pressure compensation method. The technical scheme solves the nonlinearity problem of humidity and oxygen in different pressure environments, and reduces unnecessary secondary calibration during production or use.

[0004] In order to achieve the above purpose, the technical scheme of the present application is as follows: a zirconia humidity sensor low-pressure compensation method, the method comprising the following steps:

[0005] Step 1: First, calibrate the current of the sensor to ensure the consistency of the sensor. Measure the current of the sensor under different conditions and calibrate it to the target current. At this time, it is a secondary calibration a, b and c are constants; the calibrated oxygen current is obtained and I 总 ;

[0006] Step 2: Measure the current pressure or input the current pressure P (standard atmospheric pressure atm) as input by the user;

[0007] The oxygen vector [K,B] is calculated as follows:

[0008]

[0009]

[0010] Where a k b k c k for The quadratic fitting constant with respect to K, a b b b c b for The quadratic fitting constant with B;

[0011] Step 3: To further separate the interference of pressure on humidity, the PLSR algorithm was used to analyze the cross-interference between humidity and oxygen. Principal component regression using the PLSR algorithm identified the parameters exhibiting interference.

[0012] Similarly, the ratio of actual pressure to current pressure was used to fit the PLS model coefficients [A,B,C,D,E] to obtain the following results:

[0013]

[0014]

[0015]

[0016]

[0017]

[0018] Where a A b A c A for The quadratic fitting constant of A, a B b B c B for The quadratic fitting constant with B, a C b C c C for The quadratic fitting constant a with respect to C D b D c D for The quadratic fitting constant a with respect to D E bE 、c E for the quadratic fitting constant of E;

[0019] Step 4: Calculate the oxygen vector [K, B] by the oxygen vector [K, B] obtained in steps 2 and 3 and the humidity PLS model coefficient [A, B, C, D, E]

[0020] Step 5: When the measurement environment changes or the pressure changes, substitute the new pressure into the above steps 2, 3, 4 formulas, and finally obtain the measured oxygen concentration and humidity value.

[0021] Step 6: When a new device needs to be produced, only the sensor current calibration is needed to obtain and I 总 , which is also applicable to steps 2, 3, 4.

[0022] Compared with the prior art, the advantages of the present application are as follows: the scheme provides a zirconia humidity sensor low pressure compensation method, which solves the nonlinearity problem of humidity and oxygen without pressure environment, reduces unnecessary secondary calibration during production or use, and the accuracy of data when the environmental pressure changes or the environment changes. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the overall flowchart of the present application. DETAILED DESCRIPTION

[0024] In order to deepen the understanding of the present application, the following will be described in detail in combination with the drawings.

[0025] Example 1: Referring to Figure 1 , a zirconia humidity sensor low pressure compensation method, the method comprising the following steps:

[0026] Step 1: First, select 8 batches of zirconia sensors, calibrate the current of the sensor to ensure the consistency of the sensor, and measure the current of the sensor under different conditions to calibrate to the target current, which is the second calibration a, b, c are constants; obtain the calibrated oxygen current and I 总 ;

[0027] Step 2: Measure the current pressure or user input current pressure P, standard atmospheric pressure atm;

[0028] Calculate the oxygen vector [K, B]:

[0029]

[0030]

[0031] Where a k b k c k for The quadratic fitting constant with respect to K, a b b b c b for The quadratic fitting constant with B;

[0032] Step 3: To further separate the interference of pressure on humidity, the PLSR algorithm was used to analyze the cross-interference between humidity and oxygen. Principal component regression using the PLSR algorithm identified the parameters exhibiting interference.

[0033] Similarly, the ratio of actual pressure to current pressure was used to fit the PLS model coefficients [A,B,C,D,E] to obtain the following results:

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] Where a A b A c A for The quadratic fitting constant of A, a B b B c B for The quadratic fitting constant with B, a C b C c C for The quadratic fitting constant a with respect to C D b D c D for The quadratic fitting constant a with respect to D E b E c E for The quadratic fitting constant with respect to E;

[0040] Step 4: Calculate the oxygen vector [K,B] obtained from Steps 2 and 3. And humidity PLS model coefficient [A, B, C, D, E] is calculated

[0041] Step 5: measure the sensor current under different pressure conditions; and perform the calibration operation of step 1;

[0042] Step 6: substitute the calibrated oxygen current and pressure value into the same set of oxygen [K, B], a k , b k , c k and a b , b b , c b ; Substitute the oxygen current, total current, pressure value into the PLS model coefficient [A, B, C, D, E] and a A , b A , c A , a B , b B , c B , a C , b C , c C , a D , b D , c D , a E , b E , c E ; Obtain oxygen concentration and humidity.

[0043]

[0044] Table 1

[0045] From the actual measurement, the oxygen receives the pressure effect in a certain proportion without compensation, but the humidity is affected by the pressure and the interference caused by the change of oxygen at the same time, and this algorithm solves the change of oxygen concentration caused by the change of pressure.

[0046] At the same time, fully considering the cross interference between oxygen and water vapor, the PLS algorithm solves the cross interference change caused by the change of pressure, and obtains accurate humidity.

[0047] It should be noted that the above embodiments are not intended to limit the scope of protection of the present application, and any equivalent transformation or substitution made on the basis of the above technical solutions falls within the scope of protection of the claims of the present application.

Claims

1. A method of low pressure compensation for a zirconium oxide humidity sensor, characterized in that, The method comprises the following steps, Step 1: First need to calibrate the current of the sensor, to ensure the consistency of the sensor, measure the current of the sensor under different states and calibrate to the target current, which is the secondary calibration at this time , a, b, c are constants; get the calibrated oxygen current I O2 and I 总 ; Step 2: measuring the current pressure or user input current pressure P, standard atmospheric pressure atm, calculating the oxygen vector [K, B]; Step 3: the coherence of humidity and oxygen is analyzed by using PLSR algorithm, the existing interference parameters are obtained by principal component regression of PLSR algorithm, and the PLS model coefficients [A, B, C, D, E] are fitted according to the parameters by pressure; Step 4: the oxygen concentration and humidity are calculated by the vector obtained in step 2 and the model coefficients obtained in step 3; Step 5: under different pressure environment, the same coefficient can also measure accurate oxygen concentration and humidity; Step 6: when the sensor batch changes, only the current needs to be calibrated, substituted into steps 2, 3 and 4, without modifying the oxygen vector and humidity PLS model; In step 3, the cross interference of humidity and oxygen is analyzed by using PLSR algorithm, and the existing interference parameters are obtained by principal component regression of PLSR algorithm O2 、 、 、I 总 ·I O2 、1; The PLS model coefficients [A, B, C, D, E] are fitted by using the ratio of actual pressure to current pressure as follows: A = a A • (P / atm) 2 + b A • (P / atm) + c A ; B = a B • (P / atm) 2 + b B • (P / atm) + c B ; C = a C • (P / atm) 2 + b C • (P / atm) + c C ; D = a D • (P / atm) 2 + b D • (P / atm) + c D ; E = a E • (P / atm) 2 + b E • (P / atm) + c E ; where a A , b A , c A are quadratic fit constants for P / atm vs. A, a B , b B , c B are quadratic fit constants for P / atm vs. B, a C , b C , c C are quadratic fit constants for P / atm vs. C, a D , b D , c D are quadratic fit constants for P / atm vs. D, and a E , b E , c E are quadratic fit constants for P / atm vs. E.

2. The zirconium oxide humidity sensor low pressure compensation method of claim 1, wherein, Step 2 is specifically: measuring the current pressure or user input current pressure P, standard atmospheric pressure atm; The oxygen vector [K, B] is calculated as follows: K = a k • (P / atm) 2 + b k • (P / atm) + c k ; B = a b • (P / atm) 2 + b b • (P / atm) + c b ; where a k , b k , c k are quadratic fit constants for P / atm vs. K, and a b , b b , c b are quadratic fit constants for P / atm vs. B.

3. The zirconium oxide humidity sensor low pressure compensation method of claim 1, wherein, Step 4 is specifically: the oxygen vector obtained in step 2 and the model coefficients obtained in step 3 are used to calculate: Oxygen concentration O2= K I O2 + B, Humidity .

4. The zirconium oxide humidity sensor low pressure compensation method of claim 3, wherein, Step 5 is specifically: when the measurement environment changes or the pressure changes, according to the new pressure, substitute into the above steps 2, 3 and 4 formulas, finally get the measured oxygen concentration and humidity value.

5. The zirconium oxide humidity sensor low pressure compensation method of claim 4, wherein, Step 6 is in particular: when a new device needs to be produced, only the sensor current needs to be calibrated to get I O2 and I 总 , which are plugged into steps 2, 3, 4 without modifying the oxygen vector and humidity PLS models.

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