CN1948933A - Static pressure influence compensation method of capacitive differential pressure sensor - Google Patents

Abstract

The invention relates to capacitance differential pressure transducer static pressure influence compensating process. It connects the transducer with switching circuit and processing circuit to form differential pressure transmitter. Its features are as follows: while testing transmitter static pressure influence error vale, compensating a fixed capacity value and increasing equivalent capacitance value to compensate extra static pressure influence; confirming compensating capacitance Cb value according to formula Cb=C2*delta C1/ delta C2-C1 and Cb=C1*delta C2/ delta C1-C2; when the static pressure influence is negative value, parallel connecting capacitance Cb with transducer C2; when it is positive value, parallel connecting with the transducer C1; selecting standard capacitance to ensure deviation is less than 0.1 PF for computing Cb. The method has the advantages of simple operation, low cost, greatly increasing capacitive transducer quality price ratio, and good for its volume production.

Description

Static pressure influence compensation method of capacitive differential pressure sensor

Technical field

The present invention relates to sensor manufacturing and signal processing technology thereof, a kind of static pressure influence compensation method of capacitive differential pressure sensor.

Background technology

Capacitor differential pressure transducer is a kind of novel differential pressure pick-up, its core detection part is two different pressures conversion of signals that add each corresponding capacitance variations, the rear portion testing circuit then is converted to electric signal to changes in capacitance, this electric signal is handled detected the differential pressure value that just can obtain impressed pressure.

For differential pressure pick-up, its output and impressed pressure difference sensitivity in the ideal case, variable quantity is unique, and is insensitive to force value, promptly the influence of static pressure of differential pressure pick-up should be very little.But in the actual conditions, have various factors can cause the output signal of differential pressure pick-up can be subjected to the influence of static pressure, the influence of static pressure at this zero point causes a kind of additive error to the measurement result of sensor, directly influences the precision of sensor.

Because influence of static pressure directly influences the measuring accuracy of differential pressure pick-up, in order to improve the precision of differential pressure pick-up, be necessary to reduce the influence of static pressure of differential pressure pick-up, its influence of static pressure of higher precision differential pressure sensor is generally 0.1% at present, and higher reaches 0.05%.

The method of the compensating static influence of in the prior art capacitor differential pressure transducer being taked is: 1, by optimal design and manufacturing process, directly improve the static pressure index of sensor, this method fundamentally improves the static pressure index of sensor, but require higher to Design of Sensor and manufacturing process and even technological equipment, the condition that relies on is stricter, sometimes be difficult under the certain condition realize, and may cause yield rate low.2, adopt soft, hardware compensating technology, improve the static pressure index of capacitive transducer.This method is lower to the requirement of hardware, be easy to realize, can change the capacitive transducer that some influence of static pressure does not meet the demands into satisfactory capacitive transducer by the static pressure compensation technique, thereby improve the static pressure index of sensor, improve yield rate, reduce production cost of products.Content about capacitive transducer influence of static pressure compensation aspect is not seen open report.

Summary of the invention

The object of the invention provides a kind of static pressure influence compensation method of capacitive differential pressure sensor, and by hardware technology measure and software digital processing method, the ratio of adjusting the basic electric capacity of capacitor differential pressure transducer reduces the influence of static pressure of capacitor differential pressure transducer.

Static pressure influence compensation method of capacitive differential pressure sensor is characterized in that the influence of static pressure value of testing sensor according to test value, compensating a constant capacitance at sensor capacitance, increases its equivalent capacitance value, adds the influence of static pressure with compensation; According to formula $\mathrm{Cb}=\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2*\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;C}2}-C1$ With $\mathrm{Cb}=C1*\frac{\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}{\mathrm{\&Delta;C}1}-\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2$ Determine building-out capacitor Cb value; When the influence of static pressure of sensor is negative value, shunt compensation capacitor C b on sensor C2 end, and when the influence of static pressure of sensor be on the occasion of the time, shunt compensation capacitor C b on sensor C1 end, guarantee during selection standard electric capacity with the deviation of calculating Cb less than 0.1PF.

The good effect of the inventive method is: the electric capacity output signal at sensor is partly done improvement, to change-over circuit and not change of treatment circuit, adapts to wide.This method all is suitable for present commercial change-over circuit and treatment circuit.

The design philosophy of the inventive method is to improve the output accuracy of sensor, reduces the static pressure error index of capacitor differential pressure transducer as shown in Figure 1.

The principle of work of common capacitor differential pressure transducer: as shown in Figure 1: sensor has two the input pressure chambeies in positive chamber and negative chamber, and two impressed pressures are expressed as positive cavity pressure P1 and negative cavity pressure P2.

When sensor was not subjected to impressed pressure, promptly during P1=P2=0, the differential pressure that sensor is subjected to was P1-P2=0, and the output capacitance at zero point of capacitive transducer is C1 and C2, and at this moment, sensor is output as S, has

$S=\frac{C1-C2}{C1+\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

When sensor is subjected to a static pressure, the pressure that the positive and negative chamber of sensor is equated simultaneously, it is P1=P2 ≠ 0 o'clock, the differential pressure that sensor is subjected to is P1-P2=0, and this moment, the output capacitance C1 at zero point of capacitive transducer increased Δ C1, and capacitor C 2 increases Δ C2, at this moment, two corresponding electric capacity are respectively (C1+ Δ C1) and (C2+ Δ C2), and at this moment, sensor is output as S ', has

$S^{\&prime;}=\frac{(C1+\mathrm{\&Delta;C}1)-(\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2+\mathrm{\&Delta;C}2)}{(C1+\mathrm{\&Delta;C}1)+(\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2+\mathrm{\&Delta;C}2)}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

The ideal state of capacitive transducer is when static pressure and no static pressure are arranged, and the output of sensor does not change, and promptly S=S ' promptly

$\frac{C1-C2}{C1+\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}=\frac{(C1+\mathrm{\&Delta;C}1)-(\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2+\mathrm{\&Delta;C}2)}{(C1+\mathrm{\&Delta;C}1)+(\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2+\mathrm{\&Delta;C}2)}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

Formula above the conversion has following formula to set up

$\frac{C1}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}=\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

That is, if the capacitor differential pressure transducer capacitance characteristic can satisfy formula (4), then static pressure is to the not influence of output characteristics of differential pressure pick-up.

In the most of products of sensor, may not satisfy formula (4), because at variation delta C1 that adds the output capacitance of capacitor differential pressure transducer under the static pressure and Δ C2 is the self character of sensor,, certainly will to raise the cost if pursue the desirable index of properties of product separately.The inventive method is to change the basic capacitance ratio of sensor, adopts the method to the value fixed capacity in parallel of low C1 of difference or C2, makes it to satisfy formula (4), just can realize the compensation of the influence of static pressure of sensor.This method is simple and easy to operate, and cost is low, and makes common product improve quality scale, makes the electric capacity output valve reach perfect precision.

Description of drawings

Fig. 1 is common capacitor differential pressure transducer synoptic diagram;

Fig. 2 is capacitor differential pressure transducer static pressure parallel capacitive compensation method example 1 synoptic diagram of the present invention;

Fig. 3 is capacitor differential pressure transducer static pressure parallel capacitive compensation method example 2 synoptic diagram of the present invention;

Fig. 4 is electric capacity conversion and treatment circuit synoptic diagram;

Fig. 5 is a static pressure compensating plate synoptic diagram;

Embodiment

Static pressure influence compensation method of capacitive differential pressure sensor, in the time of can being implemented in static pressure and no static pressure, the output of sensor does not change, it is characterized in that not having the basic capacitance C1, the C2 that test out sensor under the static pressure with the LCR capacitance meter, static pressure is being arranged but differential pressure tests out the capacitance of sensor when being zero with the LCR capacitance meter again, the capacitance that records when deducting no static pressure with the capacitance that records that static pressure arranged then, promptly obtain electric capacity added value Δ C1, Δ C2, divide following two kinds of situations to carry out follow-up static pressure compensation process then:

Situation is 1.: see Fig. 1, suppose that the test result of a differential pressure pick-up meets C1/C2＞Δ C1/ Δ C2, at this moment influence of static pressure is a negative value, then can increase C2, realizes the compensation of influence of static pressure.

At this situation, implementation method of the present invention is shunt compensation capacitor C b on sensor capacitance C2, sees shown in Figure 2.Empty frame can be regarded the equivalent capacity differential pressure pick-up that is output as C1 and C2+Cb as among the figure.If realize that sensor does not have influence of static pressure,, require following formula to set up according to formula (4):

$\frac{C1}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2+\mathrm{Cb}}=\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}$

Can release $\mathrm{Cb}=C1*\frac{\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}{\mathrm{\&Delta;C}1}-\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right)$

Under this situation, at the C2 of sensor end capacitor C b in parallel, the capacitance characteristic of Deng Xiao capacitor differential pressure transducer can satisfy formula (4) like this, make the influence of the static pressure signal that the output characteristics of equivalent capacity differential pressure pick-up do not added, promptly realized the static pressure compensation of capacitor differential pressure transducer.

Situation is 2.: as shown in Figure 1, suppose that the test result of a differential pressure pick-up meets C1/C2＜Δ C1/ Δ C2, at this moment influence of static pressure be on the occasion of, then can increase C1, realize the compensation of influence of static pressure.

At situation 2., implementation method of the present invention is shunt compensation capacitor C b on sensor capacitance C1, sees shown in Figure 3.Empty frame can be regarded the equivalent capacity differential pressure pick-up that is output as C1+Cb and C2 as among the figure.If realize that sensor does not have influence of static pressure,, require following formula to set up according to formula (4):

$\frac{C1+\mathrm{<figure-callout\; id="2"\; label="Cb\; C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">Cb</figure-callout>}}{C}=\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}$

Can release $\mathrm{Cb}=\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2*\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;C}2}-C1\&CenterDot;\&CenterDot;\&CenterDot;\left(6\right)$

In this case, if at capacitor C 1 end of sensor capacitor C b in parallel, the capacitance characteristic of Deng Xiao capacitor differential pressure transducer can satisfy formula (4) like this, make the influence of the static pressure signal that the output characteristics of equivalent capacity differential pressure pick-up do not added, promptly realized the static pressure compensation of capacitor differential pressure transducer.

Embodiment 1: the silicon capacitive transducer, numbering 06040134 is as follows with the capacitance of LCR capacitance meter testing sensor under zero static pressure: C1=82.53pF, C2=85.30pF.Under the 10MPa static pressure, as follows with the added value of LCR capacitance meter testing sensor corresponding capacitance: Δ C1=0.84pF, Δ C2=1.02pF then.

Sensor is connected change-over circuit and treatment circuit, form differential pressure transmitter, the influence of static pressure of test transmitter is :-0.4%/10MPa.This error ratio is bigger, adopts to reduce this error in the following method.C1, the C2, Δ C1, the Δ C2 that utilize test to obtain obtain $\frac{C1}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}>\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2},$ At this moment influence of static pressure is a negative value, meets situation 1., can increase C2, both capacitor C b in parallel on C2, principle is seen shown in Figure 2: calculate Cb=14.91pF with formula (5), i.e. the fixed capacity of 14.91pF in parallel on C2, can realize the static pressure compensation, reduce influence of static pressure.The method that realizes is: after static pressure compensating plate shown in Figure 5 being pressed the lead-out terminal 1, lead-out terminal 2, lead-out terminal 3 corresponding welding of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer, get the standard capacitance 15PF close, the position of D4 welding shunt capacitance 15PF on the static pressure compensating plate with Cb=14.91pF; When getting standard capacitance, guarantee to get final product less than 0.1PF with the deviation of calculating Cb.

Behind the shunt capacitance Cb, the influence of static pressure of test transmitter, test figure is as follows:

The static pressure compensation during shunt capacitance, is not promptly carried out in the D4 position on the static pressure compensating plate, tests earlier, and by sensor and conversion circuit and treatment circuit are combined into transmitter, the influence of static pressure that records sensor is-0.4%; When behind D4 position fixed capacity 15pF in parallel on the static pressure compensation compensating plate, the influence of static pressure of corresponding transmitter is+0.025%, and the influence of static pressure of transmitter significantly improves.This example proves that the practical function of the static pressure compensation method that the present invention proposes is fine.

In the superincumbent process of the test, basic capacitance and the capacitance that has under the static pressure under the no static pressure have been tested, can omit in this step real process, promptly according to practical application experience, when the influence of static pressure of transmitter is negative value, generally need be on the C2 of sensor terminal shunt compensation capacitor C b, and when the influence of static pressure of transmitter be on the occasion of the time, generally need be on the C1 of sensor terminal shunt compensation capacitor C b.The numerical values recited of concrete Cb both can also can be passed through the static pressure test process of sensor progressively near ideal value by calculating.

Embodiment 2: the silicon capacitive transducer, numbering 06070221 is assembled into that the actual measurement influence of static pressure is-0.18% behind the transmitter.

Because influence of static pressure is a negative value, need be at the C2 of sensor electric capacity place shunt compensation electric capacity.After the static pressure compensating plate is pressed the lead-out terminal 1, lead-out terminal 2, lead-out terminal 3 corresponding welding of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer as shown in Figure 2, the position of D4 welding shunt capacitance 5pF on static pressure compensating plate shown in Figure 5, the testing sensor influence of static pressure is-0.065%; Shunt capacitance 5pF is welded in the position of D5 on the static pressure compensating plate again, and at this moment total shunt capacitance value reaches 10pF, and the influence of static pressure of testing sensor is+0.105%.Because perfect compensation effect is that influence of static pressure is 0%, so the ideal value of static pressure building-out capacitor Cb should be between 5pF～10pF.

Embodiment 3: the silicon capacitive transducer, and numbering 06050168, actual measurement sensor influence of static pressure is+0.25%.

After static pressure compensating plate shown in Figure 5 being pressed the lead-out terminal 1, lead-out terminal 2, lead-out terminal 3 corresponding welding of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer, the position of D1 welding shunt capacitance 5pF on the static pressure compensating plate, the testing sensor influence of static pressure is+0.125%; Shunt capacitance 5pF is welded in the position of D2 on the static pressure compensating plate again, and at this moment total building-out capacitor value reaches 10pF, and the influence of static pressure of testing sensor is+0.03%.Can judge that thus the ideal value of static pressure building-out capacitor Cb can get 10pF.

Embodiment 4: the silicon capacitive transducer, and numbering 06050166, actual measurement sensor influence of static pressure is+0.26%.

After static pressure compensating plate shown in Figure 5 being pressed the lead-out terminal 1, lead-out terminal 2, lead-out terminal 3 corresponding welding of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer, the position of D1 welding shunt capacitance 5pF on the static pressure compensating plate, the testing sensor influence of static pressure is+0.198%; Shunt capacitance 5pF is welded in the position of D2 on the static pressure compensating plate again, and the influence of static pressure of testing sensor is+0.12%; Shunt capacitance 5pF is welded in the position of D3 on the static pressure compensating plate again, and at this moment total building-out capacitor value reaches 15pF, and the influence of static pressure of testing sensor is+0.043%, and it is satisfied that this value has equated, so static pressure building-out capacitor Cb ideal value can be got 15pF.

Electric capacity conversion and treatment circuit in the differential pressure transmitter of the present invention, it can be commercial standard component, also can be oneself exploitation,, can adopt the present invention to realize the influence of static pressure compensate function as long as possess the due basic function of differential pressure transmitter.Its major function be to the electric capacity of capacitive transducer change, necessary processing, outputting standard signal.Its course of work is the sensor capacitance signal through the temperature signal of electric capacity/frequency inverted or A/D conversion, temperature sensor, manually zero-bit conditioning signal, hand range conditioning signal all are connected with little process chip, and the signal of sending into is output as industrial standard electric signal 4～20mA by the D/A conversion of signals after linearization, temperature compensation, range ability adjustment, transport function, engineering unit, damping, communication and the processing of diagnosis supervisor.

The present invention utilizes static pressure compensating plate shown in Figure 5, conveniently realizes the in parallel of building-out capacitor and sensor capacitance.Its method of attachment be with static pressure compensating plate shown in Figure 5 by the lead-out terminal 1 of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer, lead-out terminal 2, lead-out terminal 3 corresponding welding after, and then with electric capacity input terminal 1, input terminal 2, the input terminal 3 corresponding welding of the lead-out terminal 1 of capacitor differential pressure transducer, lead-out terminal 2, lead-out terminal 3, thereby conveniently realized the in parallel realization of building-out capacitor with sensor capacitance with change-over circuit.

The method of utilizing the present invention to propose also can by increasing the static pressure compensating module therein, reach static pressure compensation application module and realize by revising the handling procedure of treatment circuit.

For intelligent differential pressure transmitter, it adopts digital processing technology that the performance of capacitive transducer is compensated, as shown in Figure 3, its course of work is that change-over circuit carries out conversion to capacitance signal, the value of capacitor C 1 and C2 is converted to proportional with it numerical value Cp1 and Cp2, by the Intelligent treatment circuit this numerical value is carried out digital processing again.

If the differential pressure pick-up static pressure characteristic of front end can not satisfy the requirement of transmitter, can utilize intelligent transducer digital processing program, adopt the static pressure compensation method to improve the precision of differential pressure transmitter.Implementation method is to take the symmetrical figure disposal route, and with respect to formula (5) and formula (6), the symmetrical treatment method is more convenient, is more suitable for digital processing technology and uses.Concrete grammar is:

Set a static pressure compensation rate Cp, according to the requirement of formula (4), Cp should satisfy following formula:

$\frac{\mathrm{Cp}1+\mathrm{Cp}}{\mathrm{Cp}2-\mathrm{Cp}}=\frac{\mathrm{\&Delta;Cp}1}{\mathrm{\&Delta;<figure-callout\; id="2"\; label="Cp"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">Cp</figure-callout>}2}\&CenterDot;\&CenterDot;\&CenterDot;\left(7\right)$

Wherein

Cp1: obtain for smart circuit with capacitor C 1 corresponding numerical value

Cp2: obtain for smart circuit with capacitor C 2 corresponding numerical value

Δ Cp1: be and the corresponding numerical value of Δ C1

Δ Cp2: be and the corresponding numerical value of Δ C2

Can push away

$\mathrm{Cp}=\frac{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2*\mathrm{\&Delta;C}1-C1*\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}{\mathrm{\&Delta;C}1+\mathrm{\&Delta;<figure-callout\; id="2"\; label="C"\; filenames="A20061013413900121.png"\; state="\{\{state\}\}">C</figure-callout>}2}\&CenterDot;\&CenterDot;\&CenterDot;\left(8\right)$

Here Cp difference as the case may be may be on the occasion of also may being negative value.

Method above adopting by certain programming, just can realize the static pressure performance compensation of intelligent differential pressure transmitter very easily, thereby improves the precision of differential pressure transmitter.

Claims (3)

1, a kind of static pressure influence compensation method of capacitive differential pressure sensor is characterized in that the influence of static pressure value of testing sensor according to test value, compensating a constant capacitance at sensor capacitance, increases its equivalent capacitance value, adds the influence of static pressure with compensation; According to formula $\mathrm{Cb}=C2*\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;C}2}-C1$ With $\mathrm{Cb}=C1*\frac{\mathrm{\&Delta;C}2}{\mathrm{\&Delta;C}1}-C2$ Determine building-out capacitor Cb value; When the influence of static pressure of sensor is negative value, shunt compensation capacitor C b on sensor C2 end, and when the influence of static pressure of sensor be on the occasion of the time, shunt compensation capacitor C b on sensor C1 end, guarantee during selection standard electric capacity with the deviation of calculating Cb less than 0.1PF.

2, static pressure influence compensation method of capacitive differential pressure sensor according to claim 1 is characterized in that in mode of operation it being that the capacitance with LCR capacitance meter testing sensor is C1 and C2 under zero static pressure; Then under the 10MPa static pressure, with the capacitance of LCR capacitance meter testing sensor and calculate the added value Δ C1 and the Δ C2 of corresponding electric capacity; By calculating, if $\frac{C1}{C2}>\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;C}2}$ Set up, a fixed compensation capacitor in parallel on capacitive transducer C2 electric capacity then, the building-out capacitor value is according to formula $\mathrm{Cb}=C1*\frac{\mathrm{\&Delta;C}2}{\mathrm{\&Delta;C}1}-C2$ Calculate static pressure building-out capacitor Cb value, after the static pressure compensating plate being pressed the lead-out terminal 1, lead-out terminal 2, lead-out terminal 3 corresponding welding of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer, get the close fixed capacity of Cb numerical value, guarantee and calculate Cb numerical value deviation less than 0.1PF, can be on the static pressure compensating plate position of D4 or D5 or D6 weld this building-out capacitor; If $\frac{C1}{C2}<\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;C}2}$ Set up, a fixed compensation capacitor in parallel on capacitive transducer C1 electric capacity then, the building-out capacitor value is according to formula $\mathrm{Cb}=C2*\frac{\mathrm{\&Delta;C}1}{\mathrm{\&Delta;C}2}-C1$ Calculate static pressure building-out capacitor Cb value, after the static pressure compensating plate being pressed the lead-out terminal 1, lead-out terminal 2, lead-out terminal 3 corresponding welding of pad hole 1, pad hole 2, pad hole 3 and capacitor differential pressure transducer, get the close fixed capacity of Cb numerical value, guarantee and calculate Cb numerical value deviation less than 0.1PF, can be on the static pressure compensating plate position of D1 or D2 or D3 weld this building-out capacitor; Capacitive transducer is connected change-over circuit and treatment circuit, form differential pressure transmitter, the influence of static pressure of test transmitter verifies whether its influence of static pressure reaches compensation effect; If compensation effect is undesirable, can finely tune the numerical value of Cb, finally make the static pressure index of capacitive transducer meet the requirements.

3, a kind of static pressure influence compensation method of capacitive differential pressure sensor is characterized in that the symmetrical treatment method of static pressure compensation value calculation, and computing formula is $\mathrm{Cp}=\frac{C2*\mathrm{\&Delta;C}1-C1*\mathrm{\&Delta;C}2}{\mathrm{\&Delta;C}1+\mathrm{\&Delta;C}2},$ The Cp value that calculates may be on the occasion of also may being negative value; Program module in the modification numerical value treatment circuit realizes the static pressure performance compensation of intelligent differential pressure transmitter so that sensor is exported this Cp value.

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