Disclosure of Invention
The invention aims to solve the problem of consistency of battery packs and ensure safe and stable running of new energy vehicles, and provides a method for judging battery core abnormity of a battery pack.
The invention achieves the above purpose through the following technical scheme:
a method for judging battery cell abnormity of a battery pack comprises the following steps:
s1, charging a battery pack until the battery pack is fully charged, and recording voltage data V of each battery cell i of the battery pack and the charged electric quantity Q of the battery pack in the charging process;
s2, based on V andq calculating each cell i
Value and establish
Corresponding relation with V, and then according to each power saving core
Maximum value of
Corresponding to the obtained voltage
S3, calculating all battery cells
Median V of
med Is then based on V
med Calculating to obtain a converted median absolute deviation CMAD;
s4, dividing each battery cell i
And K times CMAD and voltage threshold V
0 The greater of the values of (a) and (b) is compared,
the bigger electric core is unusual electric core, otherwise is normal electric core.
As a further optimization scheme of the present invention, in step S1, the battery pack is charged with a constant current.
As a further optimization scheme of the invention, in step S2, the calculation of each battery cell i is carried out based on V and Q
Value and establish
The method of the corresponding relation with V is as follows:
s21, calculating voltage interval
Wherein V
max Is the maximum voltage, V, occurring during the entire charging process
min Is the minimum voltage value in the whole charging process, M is the number of interval parts, all the voltage data V of each cell i obtained in the step S1 in the charging process are divided into M interval voltage data sets, and the interval nodes are respectively V
min 、V
min +ΔV、V
min +2ΔV、……、V
max -ΔV、V
max ;
S22, calculating the electric quantity charged by each section of battery cell i at each interval
Then calculate out
Namely, it is
Corresponding to a voltage V of V
min + (n-0.5) x Δ V, wherein m is the interval number;
s23, taking the voltage V as an abscissa, and
for the ordinate, establish
Versus voltage V.
As a further optimized scheme of the present invention, in step S22, the amount of electricity charged into each cell i at each interval
The calculation method comprises the following steps: acquiring the electric quantity Q corresponding to each two end nodes at intervals, wherein the difference of the electric quantities Q of the two end nodes is the difference
As a further optimization scheme of the present invention, in step S3, all the battery cells are used
Median V of
med The calculation of the median absolute deviation CMAD in conversion is performed as N scalar observations that make up the random variable vector a:
s31, calculating the median absolute deviation MAD of A:
MAD = mean (Ai-mean (a)), where i =1,2,.., N;
s32, calculating the absolute deviation CMAD of the converted median:
CMAD=c*MAD
wherein
erfcinv is an inverse complement error function.
The invention has the beneficial effects that:
1) According to the invention, charging voltage curves which are difficult to compare are converted into visual curves by a differentiation method, and differences among charging curves of different battery cores are quantized by a method of calculating and converting median absolute deviation, so that automatic judgment by a computer is facilitated;
2) The judgment method is simple to implement, high in result accuracy and easy to popularize.
Detailed Description
The present application will now be described in further detail with reference to the drawings, and it should be noted that the following detailed description is given for purposes of illustration only and should not be construed as limiting the scope of the present application, as these numerous insubstantial modifications and variations can be made by those skilled in the art based on the teachings of the present application.
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention; in the description of the present invention, the meaning of "a plurality" or "a plurality" is two or more unless otherwise specified.
Example 1
As shown in fig. 1 to 3, a method for determining battery cell abnormality includes the following steps:
s1, charging a battery pack to full charge by using constant current, acquiring voltage data V of each battery cell i in the charging process, and simultaneously recording the charged electric quantity Q of the battery pack;
s2, calculating each cell i based on V and Q
Value and establish
A correspondence with V; the specific method comprises the following steps:
s21, calculating voltage interval
Wherein V
max Is the maximum voltage, V, occurring during the entire charging process
min Is the minimum voltage value occurring in the whole charging process, M is the number of interval parts, and all the voltage data V of each section of the battery cell i obtained in the step S1 in the charging process are divided into M interval voltage data setsThe interval nodes are respectively V
min 、V
min +ΔV、V
min +2ΔV、……、V
max -ΔV、V
max ;
S22, calculating the electric quantity charged by each section of battery cell i at each interval
Then calculate out
Namely, it is
Corresponding to a voltage V of V
min + (n-0.5) x Δ V, wherein m is the interval number;
the electric quantity charged by each section of battery cell i at each interval
The calculation method comprises the following steps: acquiring the electric quantity Q corresponding to each two end nodes at intervals, wherein the difference of the electric quantities Q of the two end nodes is the difference
S23, taking the voltage V as an abscissa, and
for the ordinate, establish
Voltage V;
s3, finding out each power saving core
Maximum value of
And recording the voltage at which the maximum occurs
S4, calculating all battery cells
Median V of
med Is then based on V
med Calculating to obtain a conversion median absolute deviation CMAD; the specific method comprises the following steps:
s41, calculating the median absolute deviation MAD of A:
MAD = mean (Ai-mean (a)), where i =1,2,.., N;
s42, calculating the absolute deviation CMAD of the converted median:
CMAD=c*MAD
wherein
erfcinv is an inverse complement error function;
s5, deltaV of each battery cell i
i And K times CMAD and voltage threshold V
0 The larger of the values of (a) to (b) is compared,
if deltaV
i Greater than K times CMAD and voltage threshold V
0 If the value is larger, the corresponding battery cell is considered to be abnormal; otherwise, the battery cell is considered to be not abnormal.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention.