CN104502844A - Power lithium battery deterioration degree diagnosis method based on AC impedance - Google Patents

Abstract

The invention relates to a power lithium battery deterioration degree diagnosis method based on AC impedance. The method comprises steps that, a power lithium ion battery AC impedance base curve database is established, and an AC impedance curve of a to-be-detected power lithium ion battery is acquired and is analyzed to acquire charge transmission impedance of the to-be-detected power lithium ion battery. According to the method, the AC impedance curve of the to-be-detected power lithium ion battery is acquired, combining an intelligent curve matching model, intelligent matching of the power lithium ion battery AC impedance base curve database is carried out to acquire a corresponding battery deterioration degree, further combining a charge transmission impedance model, the battery deterioration degree is acquired, and the battery deterioration degree is finally outputted through an integrated evaluation model. Through the power lithium battery deterioration degree diagnosis method, the battery deterioration degree can be acquired, optimization use of the power lithium battery can be guided, the utilization rate of the power lithium battery can be improved, and service life of the power lithium battery is prolonged.

Description

A kind of dynamic lithium battery degradation diagnostic method based on AC impedance

Technical field

The present invention relates to a kind of dynamic lithium battery degradation diagnostic method, particularly relate to a kind of dynamic lithium battery degradation diagnostic method based on AC impedance, belong to lithium battery technical field of measurement and test.

Background technology

The significant advantages such as specific energy is high, specific power is high because having for lithium ion battery, have extended cycle life, efficiency for charge-discharge is high, are widely used in the large-scale energy storage system such as electric automobile, energy-accumulating power station.The state-of-charge of battery and the degradation of battery are the important performance characteristic in battery use procedure, the residual capacity of difference characterizing battery and residual life.Rationally estimating battery degradation exactly, is conducive to the degree of aging grasping battery, for the maintenance of stack battery and screening provide authentic communication, extends the serviceable life of battery.The more important thing is, the attenuation degree that can be accurate estimating battery each ageing step lays the foundation, and prevents from overcharging or overdischarge, ensures the safe handling of battery.As far back as 1998, F.Huet just reviews about AC impedance spectrometry estimation plumbic acid and the state-of-charge of nickel-cadmium battery system battery, the research of deterioration of battery degree, and be AC impedence method provide strong reference value in application of lithium ion battery evaluation battery charge state and degradation for this.But current industry still compares the method lacking and utilize AC impedance to evaluate battery charge state and degradation.

Therefore, the Changing Pattern about electrochemical alternate impedance spectrum, inside battery ohm, activation polarization and ion diffuse impedance that the present invention utilizes great many of experiments analysis to obtain, a kind of dynamic lithium battery degradation diagnostic method based on AC impedance is proposed, the method can be assessed the degradation of dynamic lithium battery effectively, and then instruct optimization to use dynamic lithium battery, improve dynamic lithium battery utilization factor.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of dynamic lithium battery degradation diagnostic method based on AC impedance, this diagnostic method can carry out comprehensive evaluation by the data analyzing AC impedance curve and charge transfer impedance, thus the degradation of simple and effective judgement power lithium-ion battery.

Technical scheme of the present invention is,

A kind of dynamic lithium battery degradation diagnostic method based on AC impedance, comprise and set up power lithium-ion battery AC impedance base curve storehouse, gather the AC impedance curve of power lithium-ion battery to be checked, analyze the charge transfer impedance obtaining power lithium-ion battery to be checked.

Described method is by gathering the AC impedance curve of power lithium-ion battery to be checked, binding curve Intelligent Matching model carries out Intelligent Matching to power lithium-ion battery AC impedance base curve storehouse and obtains corresponding deterioration of battery degree, obtain deterioration of battery degree in conjunction with charge transfer impedance model simultaneously, finally export the degradation of this battery through comprehensive evaluation model.

Described power lithium-ion battery AC impedance base curve storehouse of setting up is that based on AC impedance curve by the power lithium-ion battery of different degradation, curve puts into curve library; Described charge transfer impedance obtains by the AC impedance curve of power lithium-ion battery.

Described curve Intelligent Matching model is the related coefficient calculating base curve in mesuring battary AC impedance curve and curve library one by one, obtains required match curve and be classified as first kind base curve by the matched rule of related coefficient; Calculate the Euclidean distance of AC impedance curve to be measured and first kind base curve more one by one, obtain required match curve by the matched rule of Euclidean distance, calculate the degradation of lithium battery to be measured according to match curve.

The matched rule of described related coefficient is the typical curve of related coefficient within the scope of 0.95-1 is match curve, and the matched rule of described Euclidean distance is the minimum euclidean distance between curve.

Described match curve is the base curve in curve library under matched rule, if match curve quantity is zero, then choose the maximum base curve of related coefficient as final required match curve, the deterioration of battery degree that this curve is corresponding is the degradation that Curve Matching model obtains; If match curve quantity is greater than 1, then the mean value of the corresponding degradation of each match curve is the degradation S1 that Curve Matching model obtains.

Described related coefficient is pressed following formula (1) and is calculated and obtain:

$G1\{Z_i\left(r_j\right),Z^0\left(r_j\right)\}=\frac{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}\left\{\right|[Z_i\left(r_j\right)-\stackrel{\‾}{Z_i\left(r_j\right)}]|\×|[Z^0\left(r_j\right)-\stackrel{\‾}{Z^0\left(r_j\right)}]\left|\right\}}{\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z_i\left(r_j\right)-\stackrel{\‾}{Z_i\left(r_j\right)}]}^2}\×\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z^0\left(r_j\right)-\stackrel{\‾}{Z^0\left(r_j\right)}]}^2}}----\left(1\right)$

Described Euclidean distance is pressed following formula (2) and is calculated and obtain:

$G2\{Z_i\left(r_j\right),Z^0\left(r_j\right)\}=\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z_i\left(r_j\right)-Z^0\left(r_j\right)]}^2}---\left(2\right)$

Wherein, Z _i(r _j) represent i-th base curve impedance real part r in curve library _jcorresponding imaginary values, i is less than or equal to the curve number in curve library; Z ⁰(r _j) represent the impedance curve impedance real part r of lithium battery to be measured _jcorresponding imaginary values; represent the mean value of i-th all imaginary values of base curve in curve library; represent the mean value of all imaginary values of lithium battery to be measured; r _jrepresent the impedance real part value of curve jth point; M represents that curve data is counted, 1≤j≤m.

Described charge transfer impedance model is S2=a × R ²+ b × R+c, a, b, c are the characteristic parameter of charge transfer impedance model.

Described charge transfer impedance obtains by the AC impedance curve of Zsimpwin software analysis power lithium-ion battery.

Described comprehensive evaluation model is that the deterioration of battery degree by exporting Intelligent Matching model and charge transfer impedance model is weighted evaluation, finally obtains the degradation of dynamic lithium battery to be measured.Account form is as follows:

S＝w ₁×S1+w ₂×S2，w ₁+w ₂＝1，0≤w ₁,w ₂≤1。

The invention has the beneficial effects as follows, a kind of dynamic lithium battery degradation diagnostic method based on AC impedance provided by the invention, can by analyzing the data of AC impedance curve and charge transfer impedance, and carry out comprehensive evaluation, and then the degradation of simple and effective judgement power lithium-ion battery, in real world applications environment, the deterioration of battery degree that can be obtained by the method is instructed to optimize and uses dynamic lithium battery, improve dynamic lithium battery utilization factor, extend the serviceable life of dynamic lithium battery.

The present invention is applicable to the diagnosis of dynamic lithium battery degradation.

Accompanying drawing explanation

Fig. 1 is degradation diagnostic method main flow block diagram of the present invention;

Fig. 2 is curve matching algorithm FB(flow block);

Fig. 3 is the AC impedance base curve of the different degradation of dynamic lithium battery.

Embodiment

The present invention is further described below in conjunction with drawings and Examples.

With reference to Fig. 1, based on a dynamic lithium battery degradation diagnostic method for AC impedance, comprise and set up power lithium-ion battery AC impedance base curve storehouse, gather the AC impedance curve of power lithium-ion battery to be checked, analyze the charge transfer impedance obtaining power lithium-ion battery to be checked; Described power lithium-ion battery AC impedance base curve storehouse of setting up is that based on AC impedance curve by the power lithium-ion battery of different degradation, curve puts into curve library; Described charge transfer impedance obtains by the AC impedance curve of power lithium-ion battery.Method provided by the invention comprises curve Intelligent Matching model, charge transfer impedance model and comprehensive evaluation model, the method is that the AC impedance curve by gathering power lithium-ion battery to be checked carries out to power lithium-ion battery AC impedance base curve storehouse the deterioration of battery degree that Intelligent Matching obtains correspondence, obtain deterioration of battery degree in conjunction with charge transfer impedance model, the final degradation exporting this battery after comprehensive evaluation simultaneously.

The method is specifically divided into following steps:

The first step: set up power lithium-ion battery AC impedance base curve storehouse, as shown in Figure 3.

Second step: the AC impedance curve gathering power lithium-ion battery to be checked.

3rd step: Intelligent Matching, calculates the related coefficient of base curve in mesuring battary AC impedance curve and curve library one by one, obtains required match curve and be classified as first kind base curve by the matched rule of related coefficient; Calculate the Euclidean distance of AC impedance curve to be measured and first kind base curve more one by one, obtain required match curve by the matched rule of Euclidean distance.The matched rule of described related coefficient is the typical curve of related coefficient within the scope of 0.95-1 is match curve, and the matched rule of described Euclidean distance is the minimum euclidean distance between curve.

4th step: if match curve quantity is zero, then choose the maximum base curve of related coefficient as final required match curve, the deterioration of battery degree that this curve is corresponding is the degradation that Curve Matching model obtains; If match curve quantity is greater than 1, then the mean value of the corresponding degradation of each match curve is the degradation that Curve Matching model obtains.Matched rule as shown in Figure 2.

Described related coefficient is pressed following formula (1) and is calculated and obtain:

$G1\{Z_i\left(r_j\right),Z^0\left(r_j\right)\}=\frac{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}\left\{\right|[Z_i\left(r_j\right)-\stackrel{\‾}{Z_i\left(r_j\right)}]|\×|[Z^0\left(r_j\right)-\stackrel{\‾}{Z^0\left(r_j\right)}]\left|\right\}}{\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z_i\left(r_j\right)-\stackrel{\‾}{Z_i\left(r_j\right)}]}^2}\×\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z^0\left(r_j\right)-\stackrel{\‾}{Z^0\left(r_j\right)}]}^2}}----\left(1\right)$

Described Euclidean distance is pressed following formula (2) and is calculated and obtain:

$G2\{Z_i\left(r_j\right),Z^0\left(r_j\right)\}=\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z_i\left(r_j\right)-Z^0\left(r_j\right)]}^2}---\left(2\right)$

Wherein, Z _i(r _j) represent i-th base curve impedance real part r in curve library _jcorresponding imaginary values, i is less than or equal to the curve number in curve library; Z ⁰(r _j) represent the impedance curve impedance real part r of lithium battery to be measured _jcorresponding imaginary values; represent the mean value of i-th all imaginary values of base curve in curve library; represent the mean value of all imaginary values of lithium battery to be measured; r _jrepresent the impedance real part value of curve jth point; M represents that curve data is counted, 1≤j≤m.

5th step: and then the degradation S1 of corresponding battery is obtained by Intelligent Matching model.

6th step: the degradation S2 being calculated battery by the charge transfer impedance of charge transfer impedance model, lithium battery to be measured, i.e. S2=a × R ²+ b × R+c, a, b, c are the characteristic parameter of charge transfer impedance model.

7th step: utilize comprehensive evaluation model finally to obtain the degradation S of dynamic lithium battery to be measured.Account form is as follows:

S＝w ₁×S1+w ₂×S2，w ₁+w ₂＝1，0≤w ₁,w ₂≤1。

8th step: the degradation S exporting dynamic lithium battery to be measured.

Claims (8)

1., based on a dynamic lithium battery degradation diagnostic method for AC impedance, it is characterized in that,

Described method establishment power lithium-ion battery AC impedance base curve storehouse, gathers the AC impedance curve of power lithium-ion battery to be checked, analyzes the charge transfer impedance obtaining power lithium-ion battery to be checked;

Described method is by gathering the AC impedance curve of power lithium-ion battery to be checked, binding curve Intelligent Matching model carries out Intelligent Matching to power lithium-ion battery AC impedance base curve storehouse and obtains corresponding deterioration of battery degree, obtain deterioration of battery degree in conjunction with charge transfer impedance model simultaneously, finally export the degradation of this battery through comprehensive evaluation model.

2. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 1, it is characterized in that, described power lithium-ion battery AC impedance base curve storehouse of setting up is that based on AC impedance curve by the power lithium-ion battery of different degradation, curve puts into curve library; Described charge transfer impedance obtains by the AC impedance curve of power lithium-ion battery.

3. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 1, it is characterized in that, described curve Intelligent Matching model is the related coefficient calculating base curve in mesuring battary AC impedance curve and curve library one by one, obtains required match curve and be classified as first kind base curve by the matched rule of related coefficient; Calculate the Euclidean distance of AC impedance curve to be measured and first kind base curve more one by one, obtain required match curve by the matched rule of Euclidean distance, calculate the degradation of lithium battery to be measured according to match curve.

4. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 1, it is characterized in that, described charge transfer impedance model is S2=a × R ²+ b × R+c, a, b, c are the characteristic parameter of charge transfer impedance model, and wherein S2 represents the degradation obtained by charge transfer impedance model, and R represents charge transfer impedance.

5. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 1, it is characterized in that, described comprehensive evaluation model is that the deterioration of battery degree by exporting Intelligent Matching model and charge transfer impedance model is weighted evaluation, finally obtains the degradation of dynamic lithium battery to be measured;

Account form is as follows:

S＝w ₁×S1+w ₂×S2，w ₁+w ₂＝1，0≤w ₁,w ₂≤1；

Wherein, S represents deterioration of battery degree, and S1 represents the degradation obtained by Intelligent Matching, and S2 represents the degradation obtained by charge transfer impedance model; w ₁and w ₂represent the weight coefficient of two kinds of methods respectively.

6. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 3, it is characterized in that, the matched rule of described related coefficient is the typical curve of related coefficient within the scope of 0.95-1 is match curve, and the matched rule of described Euclidean distance is the minimum euclidean distance between curve.

7. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 3, it is characterized in that, described match curve is the base curve in curve library under matched rule, if match curve quantity is zero, then choose the maximum base curve of related coefficient as final required match curve, the deterioration of battery degree that this curve is corresponding is the degradation that Curve Matching model obtains; If match curve quantity is greater than 1, then the mean value of the corresponding degradation of each match curve is the degradation S1 that Curve Matching model obtains.

8. a kind of dynamic lithium battery degradation diagnostic method based on AC impedance according to claim 3, is characterized in that, described related coefficient calculates by formula (1) and obtains:

$G1\{Z_i\left(r_j\right),Z^0\left(r_j\right)\}=\frac{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}\left\{\right|[Z_i\left(r_j\right)-\stackrel{\‾}{Z_i\left(r_i\right)}]|\×{\left|\right[Z}^0\left(r_j\right)-\stackrel{\‾}{Z^0\left(r_j\right)}]\left|\right\}}{\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z_i\left(r_j\right)-\stackrel{\‾}{Z_i\left(r_j\right)}]}^2}\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{\left[Z^0\left(r_j\right)-\stackrel{\‾}{Z^0\left(r_j\right)}\right]}^2}}----\left(1\right)$

Described Euclidean distance calculates by formula (2) and obtains:

$G2\{Z_i\left(r_j\right),Z^0\left(r_j\right)\}=\sqrt{\frac{1}{m}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[Z_i\left(r_j\right)-Z^0\left(r_j\right)]}^2}---\left(2\right)$

Wherein, Z _i(r _j) represent i-th base curve impedance real part r in curve library _jcorresponding imaginary values, i is less than or equal to the curve number in curve library; Z ⁰(r _j) represent the impedance curve impedance real part r of lithium battery to be measured _jcorresponding imaginary values; represent the mean value of i-th all imaginary values of base curve in curve library; represent the mean value of all imaginary values of lithium battery to be measured; r _jrepresent the impedance real part value of curve jth point; M represents that curve data is counted, 1≤j≤m.