A method of multipoint temperature compensation for a pressure sensor

Abstract

This invention discloses a multi-point temperature compensation method for pressure sensors. Real-time compensation for temperature drift is achieved through interpolation and ergodic methods. Furthermore, based on feedback, a nonlinear adjustment module feeds back the output voltage to the input, reusing it as the excitation source for the pressure-sensing component to compensate for its nonlinearity error. This invention solves the problems of temperature drift and nonlinearity in pressure-sensing components.

Description

Technical Field

[0001] This invention belongs to the field of signal processing algorithm technology for aviation pressure sensors, and specifically relates to a multi-point temperature compensation method for pressure sensors. Background Technology

[0002] For signal processors, both domestic and international digital calibration systems can be used for evaluation, but they are prone to the following problems:

[0003] In foreign countries, the calibration results cannot be obtained during the calibration process. Testing is required after all calibrations are completed. If the data is unqualified, all temperature points need to be recalibrated.

[0004] Foreign calibration systems are prone to crashes and garbled calibration data, requiring recalibration, which is very time-consuming.

[0005] Domestic operations are complex, have a high failure rate, and still have many shortcomings. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-point temperature compensation method for pressure sensors. This invention solves the problems of temperature drift and nonlinearity in pressure-sensing components.

[0007] The technical solution of the present invention is: a multi-point temperature compensation method for a pressure sensor, which realizes real-time compensation for temperature drift through interpolation and ergodic methods, and based on feedback, the nonlinear adjustment module feeds back the output voltage to the input terminal, which is then used as the excitation source of the pressure sensing component to compensate for the nonlinear error of the pressure sensing component.

[0008] The aforementioned multi-point temperature compensation method for pressure sensors includes the following steps:

[0009] Step 1: Set the output target voltage V at zero-point pressure P1. ZERO The target output voltage V at full pressure P2 FSD The target output current I is obtained after U / I conversion. ZERO and I FSD ;

[0010] Step 2: Let there be a temperature set T∈{T i |i=1,2...,n},T min <Ti<T max T min T is the minimum operating temperature for the pressure sensor. max This is the maximum operating temperature of the pressure sensor.

[0011] The zero-point pressure P1 and full-point pressure P2 are collected at temperature T1; where the zero-point pressure P1 is the pressure under standard atmospheric pressure, and the full-point pressure P2 is the maximum pressure within the pressure range.

[0012] Step 3: Under ideal linear conditions, acquire the output voltage V of the pressure sensor chip at the zero-point pressure P1. out1 The output voltage V of the pressure sensor chip P2 at full pressure out2 ;

[0013] Step 4: Under full-point pressure P2, according to A g By using a traversal method, we can obtain that GO·GI is greater than A. g The minimum value (GO·GI) min Through the following formula

[0014]

[0015] Get GD, the sequel (GO·GI) min Instead of recalculating, GD is fine-tuned using a traversal method to make V... out The output meets the requirements;

[0016] Step 5: Under zero-point pressure P1, calculate V according to the following formula. Zero-DAC

[0017]

[0018] Step 6: Calculate the actual V′ when P1 is reached. ZERO The actual V′ at P2 FSD ;

[0019] V′ ZERO =V Zero-DAC ·GD·GO

[0020] V′ FSD =(V IN +V coarse-Offset )·GI·GD·GO+V Zero-DAC GD GO;

[0021] Step 7: Collection time Therefore, the nonlinear parameter B under pressure is V for

[0022]

[0023] Step 8: Introduce nonlinear compensation calculation K LIN ;

[0024] Step 9: Use the K obtained in Step 8 LIN The other temperatures T in the temperature set T are calculated. i V after nonlinear compensation out ;

[0025] Step 10: Fill in the temperature set T with adjacent temperature acquisition points T using interpolation. i T i GD and V between -1 Zero-DAC This ensures linear output across the entire temperature range.

[0026] In the aforementioned multi-point temperature compensation method for pressure sensors, in step one, I ZERO and I FSD The corresponding output currents are 4mA and 20mA.

[0027] In the aforementioned multi-point temperature compensation method for pressure sensors, in step three, the ideal linear case is defined as follows: linearity coefficient K LIN =0.

[0028] In the aforementioned multi-point temperature compensation method for pressure sensors, in step three, V out1 V out2 Calculated by the following formula:

[0029]

[0030] Where: V IN This refers to the output voltage of the pressure-sensing component in the pressure sensor. This is the maximum output voltage of the pressure-sensing component in the pressure sensor. V is the minimum output voltage of the pressure-sensing component in the pressure sensor. Coarse-Offset V is the bias voltage, GI is the first-stage input gain, and V is the voltage level. Zero-DAC V is the zero-point bias voltage, GD is the second-stage input gain, GO is the output gain, and V REF K is the reference voltage. EXC This is the incentive coefficient.

[0031] In the aforementioned multi-point temperature compensation method for pressure sensors, in step three, V Coarse-Offset =0; GI preset value is the minimum magnification A1, V Zero-DAC The preset value is the minimum voltage value V. min ;GD is in the range (0.3333, 1), initially represented by coefficient α, and GO is preset to the minimum magnification factor A2; then:

[0032]

[0033] Therefore, the output voltage of the pressure-sensing component at zero-point pressure P1 can be obtained. The output voltage of the pressure sensing element at full pressure P2 Its voltage span S p for

[0034]

[0035] And because the target voltage V ZERO With target voltage V FSD Span S pg for

[0036] S pg =V FSD -V ZERO

[0037] Then the span S of the target voltage pg Relative to the voltage span S obtained from the acquisition p Magnification A g for

[0038]

[0039] In the aforementioned multi-point temperature compensation method for pressure sensors, in step eight,

[0040]

[0041] In the aforementioned multi-point temperature compensation method for pressure sensors, in step eight, V REF The selected parameters are 4.096V and K. EXC The selected parameter is 0.83.

[0042] In the aforementioned multi-point temperature compensation method for pressure sensors, the calculation process for step nine is as follows:

[0043] The output voltage V′ of the pressure sensor chip that collects the zero-point pressure P1 at temperature Ti is obtained. out1 The output voltage V′ of the pressure sensor chip P2 at full pressure out2 Its voltage span S′ p for

[0044] S′ p =V′ out2 -V′ out1

[0045] And because the target voltage V ZERO With target voltage V FSD Span S pg for

[0046] S pg =V FSD -V ZERO

[0047] Then the span S of the target voltage pg Relative to the voltage span S obtained from the acquisition p The magnification factor A(Ti) g for

[0048]

[0049] Under full-point pressure P2, according to A′ g Through the following formula

[0050]

[0051] We obtain GD′;

[0052] Under zero-point pressure P1, V′ is calculated using the following formula. Zero-DAC

[0053] V Zero-DAC (i)=V′ out1 / (GD′·GO)

[0054] GD′, V Zero-DAC (i), K LIN Substituting into the following formula, we obtain V after nonlinear compensation. out :

[0055]

[0056] When condition V is not met out (1-β)<V out <V out When (1+β), the V out The corresponding GD′ and V Zero-DAC (i) Elimination, β is V out The required accuracy of the output.

[0057] The advantages of this invention are:

[0058] This invention is a multi-point temperature compensation algorithm based on pressure sensors. This algorithm addresses the temperature drift and nonlinearity issues of the pressure-sensing component. It achieves real-time compensation for temperature drift through interpolation and ergodic methods. Furthermore, based on feedback, the nonlinear adjustment module feeds back the output voltage to the input terminal, which is then used as the excitation source for the pressure-sensing component to compensate for its nonlinearity error.

[0059] This invention is a multi-point temperature compensation algorithm based on a pressure sensor. It uses calibrated temperature / pressure data to divide the temperature into multiple segments and constructs a set of coefficients for the zero point and range to change with temperature. By collecting data at different temperature points, the zero point and range of the corresponding temperature segment are found in the coefficients, thereby controlling the output of the zero point and full scale, adjusting the zero point bias voltage and the secondary input gain to achieve the temperature compensation effect.

[0060] Based on feedback, the present invention feeds the output voltage back to the input terminal through a nonlinear adjustment module, which is then used as the excitation source for the pressure sensing component to compensate for the nonlinear error of the pressure sensing component.

[0061] Compared to analog output products consisting only of instrumentation operational amplifiers and filter amplifier circuits, which have limited functionality, lack nonlinear compensation and temperature compensation functions, and have inconsistent output equations, making them inconvenient to use, this invention applies the multi-point temperature compensation algorithm of the pressure sensor to a digital calibration system. This enables nonlinear compensation and temperature compensation functions, and standardizes the output equations of different sensor products, meeting their interchangeability requirements in use.

[0062] Compared to other digital products composed of amplification and filtering circuits and microcontrollers, this invention can achieve compensation for temperature error and nonlinear error of the sensor, but it cannot perform precise digital zero-point adjustment of the pressure sensing component. Its accuracy cannot meet the requirements of high precision, or the cost is too high.

[0063] The multi-point temperature compensation algorithm for the pressure sensor of this invention is applied to a digital calibration system, enabling fast, efficient, and high-precision calibration. By correcting the temperature drift error and nonlinearity error of the pressure-sensing component in real time, the accuracy of the output target current obtained after U / I conversion is improved from 1% FS to 0.06% FS. Detailed Implementation

[0064] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0065] Example 1. A multi-point temperature compensation method for a pressure sensor, comprising the following steps:

[0066] Step 1: Set the output target voltage V at zero-point pressure P1. ZERO The target output voltage V at full pressure P2 FSD The target output current I is obtained after U / I conversion. ZERO and I FSD ;

[0067] Step 2: Let there be a temperature set T∈{T i |i=1,2...,n},T min <Ti<T max T min T is the minimum operating temperature for the pressure sensor. max This is the maximum operating temperature of the pressure sensor.

[0068] The zero-point pressure P1 and full-point pressure P2 are collected at temperature T1; where the zero-point pressure P1 is the pressure under standard atmospheric pressure, and the full-point pressure P2 is the maximum pressure within the pressure range.

[0069] Step 3: Under ideal linear conditions, acquire the output voltage V of the pressure sensor chip at the zero-point pressure P1. out1 The output voltage V of the pressure sensor chip P2 at full pressureout2 ;

[0070] Step 4: Under full-point pressure P2, according to A g By using a traversal method, we can obtain that GO·GI is greater than A. g The minimum value (GO·GI) min Through the following formula

[0071]

[0072] Get GD, the sequel (GO·GI) min Instead of recalculating, GD is fine-tuned using a traversal method to make V... out The output meets the requirements;

[0073] Step 5: Under zero-point pressure P1, calculate V according to the following formula. Zero-DAC

[0074]

[0075] Step 6: Calculate the actual V′ when P1 is reached. ZERO The actual V′ at P2 FSD ;

[0076] V′ ZERO =V Zero-DAC ·GD·GO

[0077] V′ FSD =(V IN +V Coarse-Offset )·GI·GD·GO+V Zero-DAC GD GO;

[0078] Step 7: Collection time Therefore, the nonlinear parameter B under pressure is V for

[0079]

[0080] Step 8: Considering the linearity of the pressure-sensing component, nonlinear compensation is introduced, and K is calculated. LIN ;

[0081] Step 9: Use the K obtained in Step 8 LIN The other temperatures T in the temperature set T are calculated. i V after nonlinear compensation out ;

[0082] Step 10: Fill in the temperature set T with adjacent temperature acquisition points T using interpolation. i T i GD and V between -1 Zero-DACThis ensures linear output across the entire temperature range.

[0083] In step one, I ZERO and I FSD The corresponding output currents are 4mA and 20mA.

[0084] In step three, the ideal linear case is defined as follows: linear coefficient K LIN =0.

[0085] In step three, V out1 V out2 Calculated by the following formula:

[0086]

[0087] Where: V IN This represents the output voltage (mV) of the pressure-sensing component in the pressure sensor. This represents the maximum output voltage (mV) of the pressure-sensing component in the pressure sensor. V is the minimum output voltage (mV) of the pressure-sensing component in the pressure sensor. Coarse-Offset V is the bias voltage (mV), GI is the first-stage input gain, and V is the input gain. Zero-DAC V is the zero-point bias voltage (mV), GD is the second-stage input gain, GO is the output gain, and V REF K is the reference voltage. EXC This is the incentive coefficient.

[0088] In step three, V Coarse-Offset The output voltage of the pressure-sensing component is zero when it is between -4.25mV and 4.25mV. Typically, the output voltage of the pressure-sensing component is between -2mV and 2mV. Therefore, V Coarse-Offset =0; GI preset value is the minimum magnification A1, V Zero-DAC The preset value is the minimum voltage value V. min ;GD is in the range (0.3333, 1), initially represented by coefficient α, and GO is preset to the minimum magnification factor A2; then:

[0089]

[0090] Therefore, the output voltage of the pressure-sensing component at zero-point pressure P1 can be obtained. The output voltage of the pressure sensing element at full pressure P2 Its voltage span S p for

[0091]

[0092] And because the target voltage V ZERO With target voltage V FSD Span S pg for

[0093] S pg =V FSD -V ZERO

[0094] Then the span S of the target voltage pg Relative to the voltage span S obtained from the acquisition p Magnification A g for

[0095]

[0096] In step eight,

[0097] In step eight, V REF The selected parameters are 4.096V and K. EXC The selected parameter is 0.83.

[0098] The calculation process for step nine is as follows:

[0099] Temperature T i The output voltage V′ of the pressure sensor chip at the lower zero pressure P1 out1 The output voltage V′ of the pressure sensor chip P2 at full pressure out2 Its voltage span S′ p for

[0100] S p =V out2 -V out1

[0101] And because the target voltage V ZERO With target voltage V FSD Span S pg for

[0102] S pg =V FSD -V ZERO

[0103] Then the span S of the target voltage pg Relative to the voltage span S obtained from the acquisition p The magnification factor A(Ti) g for

[0104]

[0105] Under full-point pressure P2, according to A′ g Through the following formula

[0106]

[0107] We obtain GD′;

[0108] Under zero-point pressure P1, V′ is calculated using the following formula. Zero-DAC

[0109] V Zero-DAC (i)=V′ out1 / (GD′·GO)

[0110] GD′, V Zero-DAC (i), K LIN Substituting into the following formula, we obtain V after nonlinear compensation. out :

[0111]

[0112] When condition V is not met out (1-β)<V out <V out When (1+β), the V out The corresponding GD′ and V Zero-DAC (i) Elimination, β is V out The required accuracy of the output.

[0113] Example 2. A multi-point temperature compensation method for a pressure sensor, comprising the following steps:

[0114] Step 1: Convert the target output voltage of 0.4V at zero pressure (0MPa) and the target output voltage of 2V at full pressure (2.5MPa) using a U / I converter to obtain the target output currents of 4mA and 20mA, respectively.

[0115] Step 2: Let there be a temperature set T∈{Ti|i=1,2,...,n}, -55℃<Ti<125℃, -55℃ is the lowest operating temperature of the pressure sensor, and 125℃ is the highest operating temperature of the pressure sensor;

[0116] The zero-point pressure was 0 MPa and the full-point pressure was 0.4 V at a temperature of 25℃.

[0117] Step 3: In the case of ideal linearity, i.e. (linear coefficient K) LIN When the pressure sensor chip detects zero pressure (0 MPa), its output voltage is 2.501 V; when the pressure sensor chip detects full pressure (2.5 MPa), its output voltage is 2.608 V. out The formula is shown below:

[0118]

[0119] Due to V Coarse-Offset =0; GI preset value is the minimum magnification of 4, V Zero-DAC=1.87V; GD is in the range of (0.3333, 1), initially with a coefficient of 0.668, and GO is preset to the minimum amplification factor of 2; therefore

[0120]

[0121] The output voltage of the pressure sensing element when the zero-point pressure is 0 MPa can be obtained. The output voltage of the pressure sensing element at a full-point pressure of 2.5MPa Its voltage span S p for

[0122]

[0123] And because the target voltage V ZERO With target voltage V FSD Span S pg for

[0124] S pg =V FSD -V ZERO =2 - 0.4 = 1.6V

[0125] Then the span S of the target voltage pg Relative to the voltage span S obtained from the acquisition p Magnification A g for

[0126]

[0127] Step 4: Under full-point pressure P2, according to A g By using a traversal method, we can obtain that GI·GO is greater than A. g The minimum value (G0·GI) min =23.27×3.6=83.772, and GD=0.953827 is obtained through the following formula;

[0128]

[0129] Step 5: Under zero-point pressure of 0 MPa, calculate V according to the following formula. Zero-DAC

[0130]

[0131] Step 6: Calculate the actual V′ at 0 MPa ZERO The actual V′ at 2.5MPa FSD ;

[0132] V′ ZERO =V Zero-DAC ·GD·GO=0.400000V

[0133] V′ FSD =V IN ·GI·GD·GO+V Zero-DAC ·GD·GO=2.039949V

[0134] When condition V is not met out (1-0.3%) < V out <V out When (1+0.3%), the V out The corresponding GD(i) and V Zero-DAC (i) Elimination: Based on GD, iterate through GD-0.1 < GD′ < GD+0.1 with a step size of 0.0005 to obtain the optimal GD′ value.

[0135] GD′=0.93091

[0136] V′Z ERO =V Zero-DAC ·GD′·GO=0.400000V

[0137]

[0138] Step 7: Collection time Therefore, the nonlinear parameter B under pressure is V for

[0139]

[0140] Step 8: Considering the linearity issue of the pressure-sensing component, nonlinear compensation is introduced, V REF The selected parameters are 4.096V and K. EXC If the selected parameter is 0.83, then...

[0141]

[0142] Step 8: Use the K obtained in Step 7 LIN The calculated V values ​​at -55℃, 0℃, 25℃, 70℃, and 125℃, after nonlinear compensation, were obtained. out I is obtained after U / I conversion ZERO and I FSD See Table 1 for details.

[0143] Table 1 Output after compensation by the pressure-sensing component

[0144]

[0145] Table 1 lists the pressure points and their corresponding outputs. After applying this algorithm, the actual output current at multiple temperature points is represented by the percentage difference between the actual output and the theoretical output at a certain temperature and the same pressure point, compared to the theoretical output. According to Table 1, it can achieve an accuracy of 0.06%FS at 25℃.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A multi-point temperature compensation method for a pressure sensor, characterized in that, Real-time compensation for temperature drift is achieved through interpolation and ergodic methods. Based on feedback, the nonlinear adjustment module feeds back the output voltage to the input, using it again as the excitation source for the pressure-sensing component to compensate for its nonlinearity error. The process includes the following steps: Step 1: Set the output target voltage V at zero-point pressure P1. ZERO The target output voltage V at full pressure P2 FSD The target output current I is obtained after U / I conversion. ZERO and I FSD ; Step 2: Let there be a temperature set T∈{T i |i=1,2,...,n},T min <Ti<T max T min T is the minimum operating temperature for the pressure sensor. max This is the maximum operating temperature of the pressure sensor. The zero-point pressure P1 and full-point pressure P2 are collected at temperature T1; where the zero-point pressure P1 is the pressure under standard atmospheric pressure, and the full-point pressure P2 is the maximum pressure within the pressure range. Step 3: Under ideal linear conditions, acquire the output voltage V of the pressure sensor chip at the zero-point pressure P1. out1 The output voltage V of the pressure sensor chip P2 at full pressure out2 ; Step 4: Under full-point pressure P2, according to Obtained through traversal method Greater than minimum value Through the following formula ， get The following Instead of recalculating, fine-tuning is performed using a traversal method. Make The output meets the requirements; Step 5: Under zero-point pressure P1, calculate according to the following formula. , ， Step Six: Calculate the actual value when P1 P2 is the actual ; ， ； Step 7: Collection time Therefore, the nonlinear parameters under pressure for ， Step 8: Introduce nonlinear compensation calculation ; Step Nine: Using the results obtained in Step Eight The other temperatures T in the temperature set T are calculated. i After nonlinear compensation ; Step 10: Fill in the temperature set T with adjacent temperature acquisition points T using interpolation. i T i GD and -1 This ensures linear output across the entire temperature range.

2. The multi-point temperature compensation method for a pressure sensor according to claim 1, characterized in that, In step one, I ZERO and I FSD The corresponding output currents are 4mA and 20mA.

3. The multi-point temperature compensation method for a pressure sensor according to claim 1, characterized in that, In step three, the ideal linear case is defined as follows: linear coefficients .

4. The multi-point temperature compensation method for a pressure sensor according to claim 1, characterized in that, In step three, V out1 V out2 Calculated by the following formula: ， in: This refers to the output voltage of the pressure-sensing component in the pressure sensor. This is the maximum output voltage of the pressure-sensing component in the pressure sensor. This is the minimum output voltage of the pressure-sensing component in the pressure sensor. GI is the bias voltage, and GI is the first-stage input gain. This is the zero-point bias voltage. GO is the second-order input gain, and GO is the output gain. For reference voltage, This is the incentive coefficient.

5. The multi-point temperature compensation method for a pressure sensor according to claim 4, characterized in that, In step three, =0; The default value for GI is the minimum magnification A1. The preset value is the minimum voltage value V. min ; Within the range (0.3333, 1), the initial coefficient is... The default value for GO is the minimum magnification factor A2; therefore: ， Therefore, the output voltage of the pressure-sensing component at zero-point pressure P1 can be obtained. The output voltage of the pressure sensing element at full pressure P2 Its voltage span for ， And because the target voltage V ZERO With target voltage V FSD span for ， The span of the target voltage Relative to the voltage span obtained Magnification for 。 6. The multi-point temperature compensation method for a pressure sensor according to claim 4, characterized in that, In step eight, .

7. The multi-point temperature compensation method for a pressure sensor according to claim 6, characterized in that, In step eight, The selected parameter is 4.096V. The selected parameter is 0.

83.

8. The multi-point temperature compensation method for a pressure sensor according to claim 1, characterized in that, The calculation process for step nine is as follows: Temperature T i The output voltage of the pressure sensor chip at the lower zero point pressure P1 The output voltage of the pressure sensor chip P2 at full pressure Its voltage span for ， And because the target voltage V ZERO With target voltage V FSD span for ， The span of the target voltage Relative to the voltage span obtained Magnification for ， Under full-point pressure P2, according to Through the following formula ， get ; Under zero-point pressure P1, calculate according to the following formula , ， Will , , Substituting into the following formula, we obtain the result after nonlinear compensation. : ， When the conditions are not met At that time, the corresponding and Remove for The required accuracy of the output.

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