CN102519666A - Digital temperature compensation system and method - Google Patents

Abstract

The invention belongs to the field of pressure measurement, particularly to a digital temperature compensation system and a method. The temperature compensation system includes a constant-current source (1), a pressure sensing module (3), a pressure signal amplifier (5), a temperature signal amplifier (8), a multiplexing switch (9), an A/D conversion module (6) and a processor (7). The method includes steps including system calibration, storage of system temperature calibration results, and the measurement temperature compensation. According to the invention, in the digital temperature compensation system, a temperature compensation resistor is additionally arranged at a pressure sensor through the design of the pressure sensing module to amplify the temperature characteristic of the pressure sensor and realize the automatic temperature compensation, so that the installation and maintenance are convenient, and the function of serving as the pressure sensor and the temperature sensor at the same time are realized. The digital temperature compensation method provided by the invention realizes the automatic temperature compensation at any temperature and any pressure, has higher measuring accuracy, improves the pressure measuring accuracy, and has the full range error smaller than 0.02% or lager than minus 0.02%.

Description

A kind of digital temperature bucking-out system and method

Technical field

The invention belongs to the pressure survey field, particularly relate to a kind of digital temperature bucking-out system and method.

Background technology

For a pressure-measuring system, precision is a very important index.In order effectively to improve measuring accuracy, aspect temperature compensation, generally consider: be the influence of integrated temperature drift on the one hand measured value from two aspects; Be that the sensor output characteristics is compensated on the other hand.Because sensor material often has transition effects, especially most materials has the temperature transition effect, and promptly properties of materials is with temperature variation or the like.To the optimal design and raising technology of sensor, can only eliminate the limited accuracy error.From another point of view, neither clearly be difficult to improve measuring accuracy through software processes or Calibration Method again through the temperature variant gradient characteristic of optimizing of pressure transducer.At present, the mode of hardware compensating is extensively adopted in temperature compensation, promptly uses thermistor compensation.But well-known, the output of pressure transducer is non-linear, adopts the measuring error of the compensation transmitter of common hardware can only reach 0.5%-0.1%, is difficult to again measuring accuracy improved a magnitude.Therefore, compensation effect is still general, can not satisfy the technical indicator of high-precision pressure measuring system.

Summary of the invention

The objective of the invention is: in order to solve the not high problem of conventional digital temperature-compensated system precision, the present invention provides a kind of digital temperature bucking-out system and method.

Technical scheme of the present invention is: a kind of digital temperature bucking-out system; Said temperature-compensated system is made up of constant current source 1, pressure sensing module 3, pressure signal amplifier 5, temperature signal amplifier 8, multiplexer switch 9, A/D modular converter 6 and processor 7; Pressure sensing module 3 is made up of pressure transducer 2 and thermo-compensator 4, and said thermo-compensator 4 is connected in the excitation end of pressure transducer 2; Constant current source 1 two ends load on the excitation end of pressure sensing module 3; Said temperature signal amplifier 8 is connected in the excitation end of pressure sensing module 3; Pressure signal amplifier 5 is connected in the signal output part of pressure sensing module 3; Said pressure signal amplifier 5 and temperature signal amplifier 8 are connected in A/D modular converter 6 through multiplexer switch 9, and A/D modular converter 6 is connected in processor 7;

Constant current source 1 provides exciting current for pressure transducer 2; 2 pairs of pressure transducers of thermo-compensator 2 carry out temperature compensation; Pressure sensing module 3 detected pressures and temperature signal also are converted into voltage signal; Pressure signal amplifier 5 amplifies pressure, temperature signal with temperature signal amplifier 8, and A/D modular converter 6 is converted into digital signal with simulating signal and sends in the processor 7, and 7 pairs of signals of processor are handled.

Said constant current source 1 is made up of reference voltage source 10, OP400 chip 11.

A kind of digital temperature compensating method uses above-mentioned a kind of digital temperature bucking-out system, may further comprise the steps:

Step 1: the demarcation of system: set up the calibration value tables of data simultaneously and demarcate the binary value tables of data:

Set up the calibration value tables of data:

(1) definite scope T that demarcates temperature ₀～T _n, T _nFor demarcating temperature spot, temperature interval Δ T, T _n=T ₀+ Δ T* (n-1), the definite temperature tolerance and environment for use that need to combine the digital temperature bucking-out system of temperature range, preferably-20～60 ℃, temperature interval Δ T is definite with accuracy requirement according to the resolution of system, preferably 1 ℃≤Δ T≤10 ℃;

(2) confirm nominal pressure scope P ₀～P _m, P _mBe the nominal pressure point, pressure intervals Δ P, P _m=P ₀+ Δ P* (n-1), pressure limit normal root really confirms that according to the range of selected pressure transducer pressure intervals Δ P requires to confirm according to system accuracy;

(3) set up the calibration value tables of data:

T 0	T 1	T 2	T 3	T i	T n
						P 0	P 0	P 0	P 0	P 0	P 0

P 1	P 1	P 1	P 1	P 1	P 1
						P 2	P 2	P 2	P 2	P 2	P 2
P j	……	……	……	P j	……
						P m	P m	P m	P m	P m	P m

Set up and demarcate the binary value tables of data:

The demarcation binary value TC of the temperature that obtains according to actual acquisition _nAnd the demarcation binary value PC of pressure _NmSet up and demarcate the binary value tables of data

TC 0	TC 1	TC 2	TC 3	TC i	TC n
						PC 0·0	PC 1·0	PC 2·0	PC 3·0	……	PC n·0
PC 0·1	PC 1·1	PC 2·1	PC 3·1	……	PC n·1
						PC 0·2	PC 1·2	PC 2·2	PC 3·2	……	PC n·2
PC 0·j	……	……	……	PC i·j	……
						PC 0·m	PC 1·m	PC 2·m	PC 3·m	……	PCn·m

Wherein, TC _nBe to demarcate temperature spot T _nCorresponding temperature binary value, PC _NmFor demarcating temperature spot T _nUnder nominal pressure point P _mCorresponding pressure binary value;

Step 2: the storage of system temperature calibration result:

With the calibration value tables of data and demarcate the binary value data table stores in the inner FLASH storer of the processor [7] of digital temperature bucking-out system;

Step 3: measure Temperature Compensation:

Systematic survey obtains measuring temperature binary value TC and gaging pressure binary value PC, and corresponding measurement temperature and gaging pressure are respectively T, P;

(1) when TC is the demarcation temperature spot, also promptly in demarcating the binary value tables of data, there is TC _iPoint equals TC, then T _iBe T, look into and demarcate the binary value tables of data:

If demarcate in the binary value tables of data PC arranged _IjEqual PC, then P is the P in the calibration value tables of data _j

If demarcate in the binary value tables of data and do not have PC _IjEqual PC, then search and immediate two values of PC numerical value, PC _IkAnd PC _{I (k+1)}, and PC _Ik≤PC≤PC _{I (k+1)}, PC _IkAnd PC _{I (k+1)}Corresponding nominal pressure point in the calibration value tables of data is respectively P _kAnd P _(k+1), then utilize formula (1) to calculate P:

$P=\frac{1}{{\mathrm{PC}}_{i\·(k+1)}-{\mathrm{PC}}_{i\·k}}[(\mathrm{PC}-{\mathrm{PC}}_{i\·k})P_{(k+1)}-(\mathrm{PC}-{\mathrm{PC}}_{i\·(k+1)}{P}_k)].........\left(1\right)$

If exceeding, PC numerical value demarcates the binary value tables of data; If then PC is less than the minimum value of demarcating in the binary value tables of data; Then the force value of this minimum value correspondence on the calibration value tables of data is P; If PC is greater than the maximal value of demarcating in the binary value tables of data, then the force value of this maximal value correspondence on the calibration value tables of data is P;

(2) when TC is not the demarcation temperature spot, promptly in demarcating the binary value tables of data, there is not TC yet _iPoint equals TC; Then search and immediate two values of TC numerical value, TC _kAnd TC _(k+1), and TC _k≤TC≤TC _(k+1)

According to formula (1), calculate PC at TC _kP under the temperature _lWith PC at TC _(k+1)P under the temperature _(l+1), then

$P=\frac{1}{{\mathrm{TC}}_{(l+1)}-{\mathrm{TC}}_l}[(\mathrm{TC}-{\mathrm{TC}}_l)P_{(l+1)}-(\mathrm{TC}-{\mathrm{TC}}_{(1+1)})P_1].........\left(2\right)$

(3) when exceeding, TC numerical value demarcates the binary value tables of data; If then TC is less than the minimum value of demarcating in the binary value tables of data; Then the temperature value of this minimum value correspondence on the calibration value tables of data is T; If TC is greater than the maximal value of demarcating in the binary value tables of data, then the force value of this maximal value correspondence on the calibration value tables of data is T, then utilizes formula (1) to calculate P.

Advantage of the present invention is: a kind of digital temperature bucking-out system of the present invention is through the pressure sensing Module Design; Pressure transducer is increased thermo-compensator amplifies its temperature characterisitic; Realized auto thermal compensation; Both be convenient to installation and maintenance, and realized not only being pressure transducer but also being the function of temperature sensor.A kind of digital temperature compensating method of the present invention; Utilized the temperature transition effect of pressure sensing module to do as the temperature compensation basis; Realize the auto thermal compensation under arbitrary temp, the pressure condition; Make it have higher measuring accuracy, improved pressure measurement accuracy, full scale error is less than ± 0.02%.

Description of drawings

Fig. 1 is a kind of digital temperature bucking-out system of the present invention schematic diagram;

Fig. 2 is a constant current source schematic diagram in a kind of digital temperature bucking-out system of the present invention.

Embodiment

Below in conjunction with accompanying drawing and through embodiment the present invention is done further detailed description, see also Fig. 1 and Fig. 2.

See also Fig. 1; A kind of digital temperature bucking-out system; Said temperature-compensated system is made up of constant current source 1, pressure sensing module 3, pressure signal amplifier 5, temperature signal amplifier 8, multiplexer switch 9, A/D modular converter 6 and processor 7; It is characterized in that pressure sensing module 3 is made up of pressure transducer 2 and thermo-compensator 4, said thermo-compensator 2 is connected in the excitation end of pressure transducer 2; Constant current source 1 two ends load on the excitation end of pressure sensing module 3; Said temperature signal amplifier 8 is connected in the excitation end of pressure sensing module 3; Pressure signal amplifier 5 is connected in the signal output part of pressure sensing module 3; Said pressure signal amplifier 5 and temperature signal amplifier 8 are connected in A/D modular converter 6 through multiplexer switch 9, and A/D modular converter 6 is connected in processor 7;

Constant current source 1 provides exciting current for pressure transducer 2; 2 pairs of pressure transducers of thermo-compensator 2 carry out temperature compensation; Pressure sensing module 3 detected pressures and temperature signal also are converted into voltage signal; Pressure signal amplifier 5 amplifies with temperature signal amplifier 8 pressure, temperature signal, and A/D modular converter 6 is converted into digital signal with simulating signal and sends in the processor 7, and 7 pairs of signals of processor are handled.

Preferably, said constant current source 1 is made up of reference voltage source 10, OP400 chip 11.

A kind of digital temperature bucking-out system of the present invention has been utilized the temperature transition characteristic of pressure transducer 2 on hardware designs, at the excitation end adding thermo-compensator 4 of sensor.After adding thermo-compensator 4, though pressure transducer 2 inner bridge resistors do not have too big variation, the impedance of whole excitation end has obvious variation with temperature variation.Because voltage=electric current * resistance, so this moment, driving voltage just changed with temperature variation, just can handle driving voltage this moment as the temperature correlation parameter, saved traditional thermistor temperature detecting degree.2 pairs of temperature of pressure sensor module 3 specific pressure sensors of this moment are responsive more, make pressure sensor module 3 not only as pressure transducer but also as temperature sensor, and temperature value measured is more accurate compared with classic method as temperature compensation value like this.Adopt temperature calibration to realize that wider precision improves again, the method need not be built temperature acquisition system in addition simultaneously, so hardware is simpler.

Instance:

A kind of digital temperature bucking-out system, pressure transducer 2 selection ± 30kPa range pressure sensors, selected pressure transducer 2 required exciting currents are 1.5mA.Native system constant current source 1 is made up of reference voltage source 10, OP400 chip 11, and wherein, reference voltage source 10 adopts the MAX6225AESA chip, is connected with OP400 chip 11, for OP400 chip 11 provides 2.5V reference voltage; OP400 chip 11 is connected with pressure sensor module 3 again, and to convert reference voltage into reference current be that pressure sensor module 3 provides 1.5mA exciting current.The current conversion resistance R is 1.6667K Ω.The difference output that pressure signal amplifier 5 adopts AD620 to realize 1: 100.The difference output that temperature signal amplifier 8 adopts AD620 to realize 1: 1.Multiplexer switch 9 adopts MAX307 to realize the channel selecting of temperature value and force value.It is digital signal with analog signal conversion that A/D modular converter 6 adopts the MAX1132 chip.Processor 7 adopts the EM9160 processor, realizes the intelligent management of collection, storage and the system of data.The selection outbalance of thermo-compensator 4, specifically as shown in stating:

Choosing of resistance; The excitation end output voltage of pressure sensor module 3 (promptly; Temperature signal voltage) can not surpass the supply voltage 15V of generation exciting current OP400 and the slew rate 12V of MAX1132 chip, and the enlargement factor of temperature signal amplifier 8 is 1, taking all factors into consideration above-mentioned condition then has:

(R _S+R _t)·1.5mV＜12V

Wherein, R _sBe pressure transducer 2 excitation end internal resistances, resistance is about 3.6K Ω.

Then, R _t＜4.4K Ω

In addition, select for use temperature to float and be 100ppm resistance (that is, 1 degree centigrade of the every variation of temperature, change in resistance parts per million (ppm)).

Temperature is floated coefficients R _T=Δ TR _t

ΔV＝R _T·I

Wherein, Δ T is a temperature variation, R _tBe the resistance size of selected thermo-compensator 4, the variable quantity of voltage on the Δ V resistance, I is ohmically current value, is exciting current value I=1.5mA.

Because the MAX1132 chip is 16 chips in the system, and output voltage range be-12V～+ 12V, the minimum resolution voltage of MAX1132 chip is 24V/65536=0.366mV.The enlargement factor of account temperature signal amplifier 8 is 1 again, if require T=1 ℃ of temperature variation Δ, output voltage variation delta V can be differentiated, and then requires this voltage variety Δ V at least otherwise less than 0.366mV, promptly have

Δ V1 times=Δ TR _tI1 doubly>=0.366mV promptly, $1.5\left(\mathrm{MA}\right)\·\frac{{10}^2}{{10}^6}\·R_t\≥0.366\left(\mathrm{MV}\right)$

Then, R _t>=2.4K Ω

If require T=10 ℃ of temperature variation Δ, in like manner can calculate R _t>=0.24K Ω.

If require T=0.5 ℃ of temperature variation Δ, in like manner can calculate R _t>=4.8K Ω.

Can find out that the resolution of the wide more temperature of the scope of resistance value is low more.

In the reality, be difficult to environment temperature is stabilized in 1 ℃, the desired temperature bucking-out system has higher temperature resolution again, comprehensive above-mentioned analysis, and native system adopts R _t=2.4K Ω.

Use the digital temperature compensating method that above-mentioned digital temperature bucking-out system realizes:

Step 1: the demarcation of system: set up the calibration value tables of data simultaneously and demarcate the binary value tables of data:

Set up the calibration value tables of data:

(1) definite scope T that demarcates temperature ₀～T _n, n=0,1,2,3......, T _nFor demarcating temperature spot, temperature interval Δ T, T _n=T ₀+ Δ T* (n-1) is because the definite of temperature range needs to combine the temperature tolerance of digital temperature bucking-out system promptly to use environment.Digital temperature bucking-out system in the instance all adopts technical grade chip temperature resistant range to be generally-40～85 ℃; And the environment for use temperature of this digital temperature bucking-out system is generally 0～50 ℃; Comprehensive these 2 considerations; We stay a part of temperature surplus again, so temperature range is selected-20～60 ℃, temperature interval Δ T confirms according to the resolution and the accuracy requirement of system.Thermo-compensator employing 100ppm resistance is 2.4K Ω for example, then has:

$\mathrm{\Δ\; T}\·2.4\mathrm{K\Ω}\·\frac{100}{{10}^6}\·1.5\mathrm{MV}\≥0.366\mathrm{MV},$ Δ T>=1 ℃ then

The output of pressure sensing module 3 in whole temperature range is non-linear in the instance; And Δ T more little the count precision of many temperature curves match more of temperature of promptly demarcating in temperature interval is high more; Calibration process and detection algorithm are more complicated but the demarcation temperature is counted; And the processor that needs has bigger data space and processing power, and the performance of processor EM9160 is 16M with its FLASH storer.Therefore, preferred temperature interval Δ T is 5 ℃.

(2) confirm nominal pressure scope P ₀～P _m, P _mBe the nominal pressure point, pressure intervals Δ P, P _n=P ₀+ Δ P* (n-1), pressure limit normal root is really confirmed according to the range of selected pressure transducer.Pressure transducer 2 selection ± 30kPa range pressure sensors, thus the pressure limit of this method is-30kPa～+ 30kPa.Pressure intervals Δ P confirms according to accuracy requirement.The output of pressure transducer 2 in whole range ability is non-linear; And pressure intervals Δ P more little be that the count precision of multiple pressure force curve match more of nominal pressure is high more; Calibration process and detection algorithm are more complicated but nominal pressure is counted, and the processor that needs has bigger data space and processing power, consider that the performance of processor EM9160 and its FLASH storer are 16M; Therefore, preferred pressure is spaced apart 5kPa.

(3) it is following to set up the calibration value tables of data: (following table is the partial content of calibration value tables of data)

T0＝0

T 1＝5

T 2＝10

T 3＝15

……

T 9＝45

T 10＝50

P 0＝-30

P 0＝-30

P 0＝-30

P 0＝-30

……

P 0＝-30

P 0＝-30

P 1＝-25

P 1＝-25

P 1＝-25

P 1＝-25

……

P 1＝-25

P 1＝-25

……

……

……

……

……

……

……

P 6＝0

P 6＝0

P 6＝0

P 6＝0

……

P 6＝0

P 6＝0

P 7＝5

P 7＝5

P 7＝5

P 7＝5

……

P 7＝5

P 7＝5

……

……

……

……

……

……

……

P 11＝25

P 11＝25

P 11＝25

P 11＝25

……

P 11＝25

P 11＝25

P 12＝30

P 12＝30

P 12＝30

P 12＝30

……

P 12＝30

P 12＝30

Wherein the unit of temperature is ℃, and the unit of pressure is kPa.

Set up and demarcate the binary value tables of data:

The demarcation binary value TC of the temperature that obtains according to actual acquisition _nAnd the demarcation binary value PC of pressure _NmIt is following to set up demarcation binary value tables of data: (following table is for demarcating the partial content of binary value tables of data)

TC 0＝26134

TC 1＝26288

TC 2＝26461

TC 3＝26633

……

TC 9＝27717

TC 10＝27906

PC 0·0＝-24311

PC 1·0＝-24337

PC 2·0＝-24371

PC 3·0＝-24383

……

PC 9·0＝-24442

PC 10·0＝-24435

PC 0·1＝-20261

PC 1·1＝-20290

PC 2·1＝--20327

PC 3·1＝-20339

……

PC 9·1＝-20394

PC 10·1＝-20385

……

……

……

……

……

……

……

PC 0·6＝-51

PC 1·6＝-93

PC 2·6＝-140

PC 3·6＝-169

……

PC 9·6＝-210

PC 10·6＝-195

PC 0·7＝3985

PC 1·7＝3939

PC 2·7＝3889

PC 3·7＝3857

……

PC 9·7＝3814

PC 10·7＝3832

……

……

……

……

……

……

……

PC 0·11＝19995

PC 1·11＝19929

PC 2·11＝19863

PC 3·11＝19823

……

PC 9·11＝19766

PC 10·11＝19787

PC 0·12＝23960

PC 1·12＝23892

PC 2·12＝23822

PC 3·12＝23779

……

PC 9·12＝23717

PC 10·12＝23738

TC wherein ₁₀Be to demarcate temperature spot T ₁₀Corresponding temperature binary value, PC ₁₀₁₂For demarcating temperature spot T ₁₀Under nominal pressure point P ₁₂Corresponding pressure binary value, other data and the like.

Step 2: the storage of system temperature calibration result;

With the calibration value tables of data of setting up in the step 1 and demarcate the binary value data table stores in the inner FLASH storer of the EM9160 processor of digital temperature bucking-out system;

Step 3: measure Temperature Compensation:

Measurement temperature binary value TC that systematic survey obtains and gaging pressure binary value PC, corresponding measurement temperature and gaging pressure are respectively T, P;

(1) when TC is the demarcation temperature spot, establishes TC=TC ₃=26633, look into and demarcate the binary value tables of data:

If pressure binary value PC is a nominal pressure point binary value, establish PC=PC ₃₇=3857, then correspond in the calibration value tables of data gaging pressure P=5kPa.

If pressure binary value PC is not a nominal pressure point binary value, establish PC=3600, then find immediate two value PC with PC ₃₆=-169 and PC ₃₇=3857, and PC ₃₆≤PC≤PC ₃₇, PC ₃₆And PC ₃₇Corresponding to the nominal pressure point P that demarcates numerical tabular ₆=0kPa and P ₇=5kPa, calculate P:

$P=\frac{1}{3857-(-169)}[(3600-(-169))\×5-(3600-3857)\×0]=4.68\mathrm{kPa}$

Demarcate the binary value tables of data if pressure binary value PC exceeds, if PC less than the minimum value of the pressure binary value under the TC temperature in the binary value tables of data, establishing PC=-25000 is PC≤PC ₃₀=-24383, P=P ₀=-30kPa; If PC is greater than the maximal value of the pressure binary value under the TC temperature in the binary value tables of data, establishing PC=24000 is PC>=PC ₃₁₂=23779, P=P ₁₂=30kPa.

(2) when TC is not the demarcation temperature spot, establish TC=26500, PC=21000; Search and immediate two the value TC of TC numerical value ₂=26461 and TC ₃=26633, and TC ₂≤TC≤TC ₃

Look into demarcation binary value tables of data and can know that PC is at TC ₂Under the temperature PC is arranged ₂₁₁≤PC≤PC ₂₁₂, PC wherein ₂₁₁=19863, PC ₂₁₂=23822.PC ₂₁₁And PC ₂₁₂Corresponding to the nominal pressure point P that demarcates numerical tabular ₁₁=25kPa and P ₁₂=30kPa. calculates PC at TC according to formula (1) ₂Pressure measuring value P under the temperature _l:

$P_l=\frac{1}{23822-19863}[(21000-19863)\×30-(21000-23822)\×25]=26.436\mathrm{kPa}$

In like manner, look into demarcation binary value tables of data and can know that PC is at TC ₃Under the temperature PC is arranged ₃₁₁≤PC≤PC ₃₁₂, PC wherein ₃₁₁=19823, PC ₃₁₂=23779.PC ₂₁₁And PC ₂₁₂Corresponding to the nominal pressure point P that demarcates numerical tabular ₁₁=25kPa and P ₁₂=30kPa. calculates PC at TC according to formula (1) ₃Pressure measuring value P under the temperature _(l+1):

$P_{(1+1)}=\frac{1}{23779-19823}[(21000-19823)\×30-(21000-23779)\×25]=26.488\mathrm{kPa}$

According to formula (1), then have

$P=\frac{1}{26633-26461}[(26500-26461)\×26.488-(26500-26633)\×26.436]=26.448\mathrm{kPa}$

(3) degree binary value TC exceeds demarcation binary value tables of data, if TC is less than the minimum value TC of the temperature binary value in the binary value tables of data ₀=26134, establishing TC=25000 is TC≤TC ₀, then assert TC=TC ₀=25000, T=T ₀=0 ℃; If TC greater than the temperature binary value in the binary value tables of data maximum of T C ₁₀=27906, establishing TC=28000 is TC>=TC ₁₀, then assert TC=TC ₀=27906, T=T ₀=50 ℃.

The implementation result of the method:

Give normal pressure input value of system, can obtain the measured value of a correspondence behind the temperature-compensated system auto thermal compensation, this two class values comparing result is as shown in the table:

Standard value (kPa)	Measured value (kPa)	Error
			-30	30.001	-0.002％
-27	-27	0
			20	--20.001	-0.002％

Standard value (kPa)	Measured value (kPa)	Error
			-12	-12.007	-0.012％
-10	-10.002	-0.003％
			-3	-3.008	-0.013％
0	0.001	0.002％
			3	2.993	-0.012％
10	10	0.000％
			12.001	12	0.002％
20	20	0％
			27.008	27	0.013％
30.002	30	0.003％

Wherein, standard value is exactly the accurate pressure input value of index.Error is the full scale error of systematic survey pressure, and error

The present invention has utilized the temperature transition effect of pressure sensing module 3 to do as the temperature compensation basis in sum; Pressure transducer 2 is increased thermo-compensator 4 its temperature characterisitic is amplified, realized auto thermal compensation, improved pressure measurement accuracy, full scale error is less than ± 0.02%.

Claims (3)

1. digital temperature bucking-out system; Said temperature-compensated system is made up of constant current source [1], pressure sensing module [3], pressure signal amplifier [5], temperature signal amplifier [8], multiplexer switch [9], A/D modular converter [6] and processor [7]; It is characterized in that; Pressure sensing module [3] is made up of pressure transducer [2] and thermo-compensator [4], and said thermo-compensator [4] is connected in the excitation end of pressure transducer [2]; Constant current source [1] two ends load on the excitation end of pressure sensing module [3]; Said temperature signal amplifier [8] is connected in the excitation end of pressure sensing module [3]; Pressure signal amplifier [5] is connected in the signal output part of pressure sensing module [3]; Said pressure signal amplifier [5] and temperature signal amplifier [8] are connected in A/D modular converter [6] through multiplexer switch [9], and A/D modular converter [6] is connected in processor [7];

Constant current source [1] provides exciting current for pressure transducer [2]; Thermo-compensator [2] carries out temperature compensation to pressure transducer [2]; Pressure sensing module [3] detected pressures and temperature signal also is converted into voltage signal; Pressure signal amplifier [5] and temperature signal amplifier [8] amplify pressure, temperature signal, and A/D modular converter [6] is converted into digital signal with simulating signal and sends in the processor [7], and processor [7] is handled signal.

2. a kind of digital temperature bucking-out system according to claim 1 is characterized in that, said constant current source [1] is made up of reference voltage source [10], OP400 chip [11].

3. a digital temperature compensating method uses claim 1 or 2 described a kind of digital temperature bucking-out systems, it is characterized in that, may further comprise the steps:

Step 1: the demarcation of system: set up the calibration value tables of data simultaneously and demarcate the binary value tables of data:

Set up the calibration value tables of data:

(1) definite scope T that demarcates temperature ₀～T _n, T _nFor demarcating temperature spot, temperature interval Δ T, T _n=T ₀+ Δ T* (n-1), the definite temperature tolerance and environment for use that need to combine the digital temperature bucking-out system of temperature range, preferably-20～60 ℃, temperature interval Δ T is definite with accuracy requirement according to the resolution of system, preferably 1 ℃≤Δ T≤10 ℃;

(2) confirm nominal pressure scope P ₀～P _m, P _mBe the nominal pressure point, pressure intervals Δ P, P _m=P ₀+ Δ P* (n-1), pressure limit normal root really confirms that according to the range of selected pressure transducer pressure intervals Δ P requires to confirm according to system accuracy;

(3) set up the calibration value tables of data:

T ₀ T ₁ T ₂ T ₃ T _i T _n P ₀ P ₀ P ₀ P ₀ P ₀ P ₀ P ₁ P ₁ P ₁ P ₁ P ₁ P ₁ P ₂ P ₂ P ₂ P ₂ P ₂ P ₂ P _j …… …… …… P _j …… P _m P _m P _m P _m P _m P _m

Set up and demarcate the binary value tables of data:

The demarcation binary value TC of the temperature that obtains according to actual acquisition _nAnd the demarcation binary value PC of pressure _NmSet up and demarcate the binary value tables of data

TC ₀ TC ₁ TC ₂ TC ₃ TC _i TC _n PC _0·0 PC _1·0 PC _2·0 PC _3·0 …… PC _n·0 PC _0·1 PC _1·1 PC _2·1 PC _3·1 …… PC _n·1 PC _0·2 PC _1·2 PC _2·2 PC _3·2 …… PC _n·2 PC _0·j …… …… …… PC _i·j …… PC _0·m PC _1·m PC _2·m PC _3·m …… PC _n·m

Wherein, TC _nBe to demarcate temperature spot T _nCorresponding temperature binary value, PC _NmFor demarcating temperature spot T _nUnder nominal pressure point P _mCorresponding pressure binary value;

Step 2: the storage of system temperature calibration result:

With the calibration value tables of data and demarcate the binary value data table stores in the inner FLASH storer of the processor [7] of digital temperature bucking-out system;

Step 3: measure Temperature Compensation:

Systematic survey obtains measuring temperature binary value TC and gaging pressure binary value PC, and corresponding measurement temperature and gaging pressure are respectively T, P;

(1) when TC is the demarcation temperature spot, also promptly in demarcating the binary value tables of data, there is TC _iPoint equals TC, then T _iBe T, look into and demarcate the binary value tables of data:

If demarcate in the binary value tables of data PC arranged _IjEqual PC, then P is the P in the calibration value tables of data _j

If demarcate in the binary value tables of data and do not have PC _IjEqual PC, then search and immediate two values of PC numerical value, PC _IkAnd PC _{I (k+1)}, and PC _Ik≤PC≤PC _{I (k+1)}, PC _IkAnd PC _{I (k+1)}Corresponding nominal pressure point in the calibration value tables of data is respectively P _kAnd P _(k+1), then utilize formula (1) to calculate P:

$P=\frac{1}{{\mathrm{PC}}_{i\·(k+1)}-{\mathrm{PC}}_{i\·k}}[(\mathrm{PC}-{\mathrm{PC}}_{i\·k})P_{(k+1)}-(\mathrm{PC}-{\mathrm{PC}}_{i\·(k+1)}{P}_k)].........\left(1\right)$

If exceeding, PC numerical value demarcates the binary value tables of data; If then PC is less than the minimum value of demarcating in the binary value tables of data; Then the force value of this minimum value correspondence on the calibration value tables of data is P; If PC is greater than the maximal value of demarcating in the binary value tables of data, then the force value of this maximal value correspondence on the calibration value tables of data is P;

(2) when TC is not the demarcation temperature spot, promptly in demarcating the binary value tables of data, there is not TC yet _iPoint equals TC; Then search and immediate two values of TC numerical value, TC _kAnd TC _(k+1), and TC _k≤TC≤TC _(k+1)

According to formula (1), calculate PC at TC _kP under the temperature _lWith PC at TC _(k+1)P under the temperature _(l+1), then

$P=\frac{1}{{\mathrm{TC}}_{(l+1)}-{\mathrm{TC}}_l}[(\mathrm{TC}-{\mathrm{TC}}_l)P_{(l+1)}-(\mathrm{TC}-{\mathrm{TC}}_{(1+1)})P_1].........\left(2\right)$

(3) when exceeding, TC numerical value demarcates the binary value tables of data; If then TC is less than the minimum value of demarcating in the binary value tables of data; Then the temperature value of this minimum value correspondence on the calibration value tables of data is T; If TC is greater than the maximal value of demarcating in the binary value tables of data, then the force value of this maximal value correspondence on the calibration value tables of data is T, then utilizes formula (1) to calculate P.