CN105738702A - NTC thermistor test method used for automobile air-conditioner - Google Patents

Abstract

The present invention relates to an NTC thermistor test method used for an automobile air-conditioner. The method comprises the steps of selecting a Steinhart-Hart third order polynomial fitting formula to carry out the fitting analysis on the RT table data values provided by an NTC thermistor manufacturer according to the actual temperature condition of the automobile air-conditioner, comparing the fitted data and the original data, if an obtained residual error exceeds a preset threshold value, prompting to reexamine NTC thermistors; and aiming at the NTC thermistor of little RT table data, adopting a characteristic curve piecewise interpolation mode to correct the RC table data, giving out a set of new RT table data suitable for application after software filtering, and providing reference for selecting NTC thermistors. The method of the present invention can be used to evaluate the validity of the RT table data provide by a thermistor factory, and the set of RT table data suitable for application is also given out.

Description

A kind of NTC thermistor method of testing for air conditioning for automobiles

Technical field

The invention belongs to technical field of automotive electronics, be specifically related to the input of a kind of critesistor being applied in automotive electronics The method of sampling, particularly relate to a kind of NTC thermistor method of testing for air conditioning for automobiles.

Background technology

Critesistor is a kind of resistance different according to temperature different resistance values, is widely used in automobile electronic controller In, especially apply and need to be applied to temperature-sensitive electricity at air conditioning for automobiles, lithium battery management system (BMS) and vehicle-mounted power controller etc. The module of resistance, wherein being most widely used with air conditioning for automobiles.NTC thermistor refers to that resistance value raises with temperature and reduces Resistance, has the advantages such as temperature sensitive, precision is higher, low price, is widely used in various thermometric occasion due to it.But Be resistance and the temperature of NTC thermistor be nonlinear correspondence relation, be relatively difficult to test the most in actual applications.Existing vapour The temperature of the NTC thermistor applied in car air-conditioning obtains mainly two ways, and one is directly to use preferable B25 value And RT value, such shortcoming is that critesistor is not set according to preferable numerical value when actual fabrication, should if actual Carrying out electronic application according to ideal value in will cause product to there is the biggest error.Another kind is directly critesistor system Making in the RT table input automotive air-conditioning controller that manufacturer provides, such shortcoming is the number or very of the RT table that producer is provided Many, need software engineer to input one by one, not only workload is big, and there is also personal error；The number in RT the exterior and the interior face Seldom, centre, directly by linear process, causes there is bigger error value.Therefore, it is necessary to come into operation it at air conditioning for automobiles The front effectiveness being tested to the critesistor used in air conditioning for automobiles test RT table data and guarantee air conditioning for automobiles Possesses higher temperature control precision.

Summary of the invention

It is an object of the invention to provide a kind of NTC thermistor method of testing for air conditioning for automobiles, empty according to automobile Adjust actual temperature conditions that the RT table of critesistor is carried out fitting of a polynomial analysis, assess the RT that critesistor factory is provided The effectiveness of table data, and also provide one group of RT table data being suitable for application.

To achieve these goals, the technical solution used in the present invention is, a kind of NTC thermistor for air conditioning for automobiles Method of testing, chooses three rank fitting polynomial formulas based on Steinhart-Hart equation to NTC thermistor manufacturer The RT table data value provided is fitted analyzing, and gained residual error of the data after matching being made comparisons with initial data is beyond setting in advance During fixed threshold value, this NTC thermistor is checked in prompting；And for the NTC thermistor that RT table data are few, use characteristic curve RT table data are modified by the mode of piecewise interpolation, and provide the RT table number of one group of new applicable application after software filtering According to, for selecting NTC thermistor to provide reference.Specifically include following steps:

(1) the three rank fitting polynomial formulas that the RT table data to NTC thermistor carry out curve fitting are chosen, the most such as Under:

R_T=R₂₅exp[A+BT+CT²+DT³] (1)

Or

$T=\frac{1}{\[A_1+B_1\ln \left(\frac{R_T}{R_{25}}\right)+C_1{\ln }^2\left(\frac{R_T}{R_{25}}\right)+D_1{\ln }^3\left(\frac{R_T}{R_{25}}\right)\]}---\left(2\right)$

Wherein, R_TBeing resistance value during T for temperature, T is Fahrenheit temperature, R₂₅Be resistance value when 25 DEG C for room temperature, A, B, C、D、A₁、B₁、C₁And D₁It is constant；

(2) the RT table data value that NTC thermistor manufacturer provides is converted into constant matrices (T_incar ^{＜ i ＞})_j, wherein I is matrix column number, and j is the line number of matrix, and (T_incar ^{＜ 0 ＞})_j(T can be abbreviated as_incar ^{＜ 0 ＞}) it is the temperature ginseng in RT table data Number；

(3) utilize software to constant matrices (T_incar ^{＜ i ＞})_jCarry out characteristic curve analysis；

(4) utilize software that the temperature parameter of NTC thermistor being carried out, error analysis sees whether meet setting of air conditioning for automobiles Meter requirement；

(5) by (T_incar ^{＜ 0 ＞})_jIt is converted into Fahrenheit temperature Tmp_m(0≤m≤j-1) (can be abbreviated as Tmp):

Tmp:=T_inear ^〈0〉+273.15 (3)

(6) by constant matrices (T_incar ^{＜ i ＞})_jIn except T_incar ^{＜ 0 ＞}Outside data and calculate gained Tmp_mValue is brought into many Item formula fitting formula (2) calculates constant A₁、B₁、C₁、D₁And obtain constant matrices $a_k=\left[\begin{array}{c}{A}_1\\ B_1\\ C_1\\ D_1\end{array}\right],(0\≤k\≤3);$

(7) by Tmp and a_kBring resistance value R calculating the NTC thermistor after matching in following formula (4) into_T(Tmp· K, a_sh)；

$R_T(T,a):=\left|\begin{array}{c}\mathrm{\&alpha;}\&LeftArrow;\frac{a_0-\frac{K}{T}}{2\&CenterDot;a_2}\\ \mathrm{\&beta;}\&LeftArrow;\sqrt{{\left(\frac{a_1}{3\&CenterDot;a_2}\right)}^3+{\mathrm{\&alpha;}}^2}\\ {\left({T_{incar}}^{<1>}\right)}_4\&CenterDot;e^{(\sqrt[3]{\mathrm{\&beta;}-\mathrm{\&alpha;}}-\sqrt[3]{\mathrm{\&beta;}-\mathrm{\&alpha;}})}\end{array}\right.---\left(4\right)$

(8) utilize software to resistance value R through matching gained_T(Tmp k, a_sh) provide with NTC thermistor manufacturer RT table data value make comparisons and carry out residual analysis, when gained residual error exceedes threshold value set in advance, software prompt check This critesistor；

(9) use curve segmentation interpolation RT table data are modified, and after software filtering A/D sampling draw one group new The RT table data of applicable application, for selecting NTC thermistor to provide reference.And in one group of given new applicable application RT table data give the critesistor emergent temperature data as temperature sensor generation wire harness open circuit conditions.

As a modification of the present invention, RT table data are being carried out in curve piecewise interpolation processing procedure, for RT table In data, the resistance value-10～40 DEG C of temperature ranges carries out the unique step data interpolating that step-length is 1, to remaining temperature range Resistance value carries out the unique step data interpolating that step-length is 5.

As a modification of the present invention, the Filtering Formula that software filtering is used is:

$filt=\frac{rem+filt\&divide;\&lsqb;2^{(f\_rate)}-1\&rsqb;+input}{2^{f\_rate}}---\left(5\right)$

Rem=[rem+filt* (2^f_rate-1)+input] & (2^f_rate-1) (6)

Wherein, filt is the circulation filter value of software filtering, and input is the input current value of software filtering, and f_rate is The filtering velocity of software filtering.

As a modification of the present invention, the sampling rate of A/D sampling is 10bit/s.

As a modification of the present invention, described software is Origin software.

Relative to prior art, advantages of the present invention is as follows: carry out the side calculated relative to traditional utilization index formula Method, more identical with measured data within the scope of bigger temperature, the formula comparison that this method is utilized is succinct, the meter of fitting parameter The amount of calculation of calculation amount and equation is all less, and therefore arithmetic speed is faster；The higher computer stored space taken of this method precision Less, in engineer applied, arithmetic speed is faster；Can be used for assessing the having of RT table data that NTC thermistor manufacturer provides Effect property, and whether its precision meet design requirement, and the purchasing management of critesistor is had certain directive function, keep away Exempt from direct employing preferable B25 value or RT value has done the error that product design is brought, also improve critesistor to real simultaneously The error that border product brings.

Accompanying drawing explanation

Fig. 1 is the characteristic curve of the NTC thermistor of the embodiment of the present invention.

Fig. 2 is the constant matrices (T of the embodiment of the present invention_incar ^{＜ i ＞})_jThe error analysis curve of middle resistance value data.

Fig. 3 be the embodiment of the present invention RT table initial data and matching after the comparative analysis result of data.

Fig. 4 is the RT table data of the applicable application given by present invention critesistor based on embodiment.

Detailed description of the invention

In order to deepen the understanding of the present invention and understanding, the invention will be further described with embodiment below in conjunction with the accompanying drawings And introduction.

A NTC thermistor produced for Vishay resistance production firm, its RT table data are as follows:

In upper table, data are less, do not meet the requirement of 1 degree of one test, use NTC thermistor proposed by the invention to survey This resistance is tested by method for testing, and detailed process is as follows:

(1) above-mentioned RT table data value is converted into constant matrices (T_incar ^{＜ i ＞})_j, wherein 0≤i≤3,0≤j≤7, (T_incar ^{＜ 0 ＞})_jOr T_incar ^{＜ 0 ＞}For the temperature parameter in RT table data.

(2) utilize Origin software to constant matrices (T_incar ^{＜ i ＞})_jCarry out characteristic curve analysis and the mistake of resistance value data Difference analysis, the characteristic curve obtained and error analysis curve the most as depicted in figs. 1 and 2, from Fig. 1 and 2, work as Temperature numerical During the temperature value being near the mark, error is less；And deviateing standard temperature value once Temperature numerical, error will increase relatively.

(3) by (T_incar ^{＜ 0 ＞})_jIt is converted into Fahrenheit temperature Tmp_m(0≤m≤7) (can be abbreviated as Tmp):

Tmp:=T_incar ^〈0〉+273.15

Due to (T_incar ^〈0〉)₄=25 have a following relation:

(Tmp)₀=243.15 (Tmp)₄=298.15 (Tmp)₇=353.15

(T_incar ^〈1〉)₀=509.6 (T_incar ^〈1〉)₄=30 (T_incar ^〈1〉)₇=3.758

(4) on the basis of step (3), three rank fitting polynomial formulas based on Steinhart-Hart equation are used:

$\frac{1}{{\mathrm{Tmp}}_0}=a+b\&CenterDot;\ln \&lsqb;\frac{{\left({T_{incar}}^{<1>}\right)}_0}{{\left({T_{incar}}^{<1>}\right)}_4}\&rsqb;+c\&CenterDot;\&lsqb;\ln {\&lsqb;\frac{{\left({T_{incar}}^{<1>}\right)}_0}{{\left({T_{incar}}^{<1>}\right)}_4}\&rsqb;}^3\&rsqb;$

$\frac{1}{{\mathrm{Tmp}}_4}=a+b\&CenterDot;\ln \&lsqb;\frac{{\left({T_{incar}}^{<1>}\right)}_4}{{\left({T_{incar}}^{<1>}\right)}_4}\&rsqb;+c\&CenterDot;\&lsqb;\ln {\&lsqb;\frac{{\left({T_{incar}}^{<1>}\right)}_4}{{\left({T_{incar}}^{<1>}\right)}_4}\&rsqb;}^3\&rsqb;$

$\frac{1}{{\mathrm{Tmp}}_7}=a+b\&CenterDot;\ln \&lsqb;\frac{{\left({T_{incar}}^{<1>}\right)}_7}{{\left({T_{incar}}^{<1>}\right)}_4}\&rsqb;+c\&CenterDot;\&lsqb;\ln {\&lsqb;\frac{{\left({T_{incar}}^{<1>}\right)}_7}{{\left({T_{incar}}^{<1>}\right)}_4}\&rsqb;}^3\&rsqb;$

Carrying out curve fitting above-mentioned RT table data, wherein, the value of given a, b, c is as follows:

A :=0.001 b:=0.001 c:=0001

Make a_sh:=Find (a, b, c) then can obtain following result:

$a_{sh}=\left(\begin{array}{c}3.354\&times;{10}^{-3}\\ 2.324\&times;{10}^{-4}\\ 4.422\&times;{10}^{-6}\end{array}\right)$

(5) by Tmp and a_shBring resistance value R calculating the NTC thermistor after matching in formula (4) into_T(Tmp· K, a_sh)。

$R_T(Tmp\&CenterDot;K,a_{sh})=\left(\begin{array}{c}509.6\\ 237.299\\ 108.009\\ 49.39\\ 30\\ 18.817\\ 6.985\\ 3.758\end{array}\right)$

(6) by the resistance value of the NTC thermistor through matching gained and constant matrices (T_incar ^{＜ i ＞})_jIn resistance data Compare analysis, as it is shown on figure 3, and according to following residual computations formula:

${\mathrm{re}}_1:=\frac{R_T(Tmp\&CenterDot;K,a_{sh})-{T_{incar}}^{<1>}}{{T_{incar}}^{<1>}}$

The residual error calculated between the data after RT table initial data and matching is:

${\mathrm{re}}_1=\left(\begin{array}{c}0\\ 0.098\\ 0.105\\ 0.048\\ 0\\ -0.039\\ -0.064\\ 0\end{array}\right)$

From result above, maximum residual error is 10.54%, has exceeded previously given threshold value 10%, therefore, soft This critesistor is checked in part prompting.

(7) use curve segmentation interpolation that RT table data are modified, be particularly directed in RT table data at-10～40 DEG C The resistance value of temperature range carries out the unique step data interpolating that step-length is 1, except-10～40 DEG C in p-20～80 DEG C of temperature ranges Outer resistance value carries out the unique step data interpolating that step-length is 5.Concrete piecewise interpolation result is as follows:

$\begin{array}{cc}{\mathrm{Temp}}_{input0}:=\left(\begin{array}{c}-30\\ -25\\ -20\\ -15\end{array}\right)& R_T\&lsqb;({\mathrm{Temp}}_{input0}+273.15)\&CenterDot;K,a_{sh}\&rsqb;=\left(\begin{array}{c}509.6\\ 396.325\\ 307.163\\ 237.299\end{array}\right)\end{array}$

$\begin{array}{cc}{\mathrm{Temp}}_{input6}:=\left(\begin{array}{c}45\\ 50\\ 55\\ 60\\ 65\\ 70\\ 75\\ 80\\ 85\end{array}\right)& R_T\&lsqb;({\mathrm{Temp}}_{input6}+273.15)\&CenterDot;K,a_{sh}\&rsqb;=\left(\begin{array}{c}12.274\\ 10.068\\ 8.344\\ 6.985\\ 5.904\\ 5.036\\ 4.333\\ 3.758\\ 3.284\end{array}\right)\end{array}$

(8) owing to signal line existing noise, it is therefore necessary to revised RT data are carried out software filtering, its In, the Filtering Formula that software filtering is used is:

$filt=\frac{rem+filt\&CenterDot;\&lsqb;2^{(f\_rate)}-1\&rsqb;+input}{2^{f\_rate}}$

Rem=[rem+filt* (2^f_rate-1)+input] & (2^f_rate-1)

So if the f_rate=6 $\frac{2^6-1}{2^6}=0.984$

So if thhe f_rate=5 $\frac{2^5-1}{2^5}=0.969$

Soifthef_rate=4 $\frac{2^4-1}{2^4}=0.938$

Data after software filtering are carried out the RT table of A/D sampling one group of new applicable application of output of 10bit/s Data (as shown in Figure 4), for selecting NTC thermistor to provide reference.And provide critesistor conduct in these group RT table data The emergent temperature data (the Default column data in Fig. 4) of temperature sensor generation wire harness open circuit conditions.

Method proposed by the invention carries out the method calculated relative to traditional utilization index formula, in bigger temperature In the range of more identical with measured data, formula comparison that this method is utilized is succinct, the amount of calculation of fitting parameter and the meter of equation Calculation amount is all less, and therefore arithmetic speed is faster；The higher computer stored space taken of this method precision is less, at engineer applied Middle arithmetic speed is faster；Can be used for assessing the effectiveness of the RT table data that NTC thermistor manufacturer provides, and its precision Whether meet design requirement, and the purchasing management of critesistor is had certain directive function, it is to avoid directly use reason The B25 value thought or RT value do the error that product design is brought, and also improve the mistake that critesistor brings to actual product simultaneously Difference.

It should be noted that above-described embodiment, be not used for limiting protection scope of the present invention, in technique scheme Equivalents or replacement done by the basis of each fall within the scope that the claims in the present invention are protected.In the claims, no Any reference marks that should will be located between bracket is configured to limitations on claims.

Claims (6)

1. the NTC thermistor method of testing for air conditioning for automobiles, it is characterised in that: choose based on Steinhart-Hart The RT table data value that NTC thermistor manufacturer is provided by three rank fitting polynomial formulas of equation is fitted analyzing, will Data after matching are made comparisons with initial data, when gained residual error is beyond threshold value set in advance, and this NTC temperature-sensitive electricity of prompting check Resistance；And for the NTC thermistor that RT table data are few, use the mode of characteristic curve piecewise interpolation that RT table data are repaiied Just, and after software filtering, provide the RT table data of one group of new applicable application, for selecting NTC thermistor to provide reference.

A kind of NTC thermistor method of testing for air conditioning for automobiles, it is characterised in that the party Method specifically includes following steps:

(1) the three rank fitting polynomial formulas that the RT table data to NTC thermistor carry out curve fitting are chosen, specific as follows:

R_T=R₂₅exp[A+B/T+C/T²+D/T³] (1)

Or

(2)

Wherein, R_TBeing resistance value during T for temperature, T is Fahrenheit temperature, R₂₅Be resistance value when 25 DEG C for room temperature, A, B, C, D, A₁、B₁、C₁And D₁It is empirical；

(2) the RT table data value that NTC thermistor manufacturer provides is converted into constant matrices (T_incar ^<i>)_j, wherein i is square The columns of battle array, j is the line number of matrix, and (T_incar ^<0>)_j(it is abbreviated as T_incar ^<0>) it is the temperature parameter in RT table data；

(3) utilize software to constant matrices (T_incar ^<i>)_jCarry out characteristic curve analysis；

(4) software is utilized the temperature parameter of NTC thermistor to carry out error analysis and judges whether to meet setting of air conditioning for automobiles Meter requirement；

(5) by (T_incar ^<0>)_jIt is converted into Fahrenheit temperature Tmp_m(0≤m≤j-1) (being abbreviated as Tmp):

Tmp:=T_incar ^〈0〉+273.15 (3)

(6) by constant matrices (T_incar ^<i>)_jIn except T_incar ^<0>Outside data and calculate gained Tmp_mValue brings multinomial into Fitting formula calculates constant A in (2)₁、B₁、C₁、D₁And obtain constant matrices

(7) by Tmp and a_kBring resistance value R calculating the NTC thermistor after matching in following formula (4) into_T(Tmp K, a_sh)；

(8) utilize software to resistance value R through matching gained_T(Tmp K, a_sh) and the RT of NTC thermistor manufacturer offer Table data value is made comparisons and carries out residual analysis, and when gained residual error exceedes threshold value set in advance, software prompt checks this heat Quick resistance；

(9) use curve segmentation interpolation that RT table data are modified, and A/D sampling draws one group of new fitting after software filtering Close the RT table data of application, for selecting NTC thermistor to provide reference.

A kind of NTC thermistor method of testing for air conditioning for automobiles, it is characterised in that right RT table data carry out in curve piecewise interpolation processing procedure, for resistance value-10～40 DEG C of temperature ranges in RT table data Carry out the unique step data interpolating that step-length is 1, the resistance value of remaining temperature range is carried out the unique step data that step-length is 5 and inserts Value.

A kind of NTC thermistor method of testing for air conditioning for automobiles, it is characterised in that soft The Filtering Formula that part filtering is used is:

Rem=[rem+filt* (2 ∧ f_rate-1)+input] & (2 ∧ f_rate-1) (6).

A kind of NTC thermistor method of testing for air conditioning for automobiles, it is characterised in that A/D adopts The sampling rate of sample is 10bit/s.

A kind of NTC thermistor method of testing for air conditioning for automobiles, it is characterised in that described Software is Origin software.