CN101458310A - Battery consistency evaluating method - Google Patents

Abstract

The invention is a method for evaluating the consistence of a battery. The method is characterized in that the consistence indicator for evaluating the usability and the consistence indicator for evaluating the storability are considered as the consistence indicator of the battery, the two standard deviations are integrated to obtain a battery group with good use and storage consistence. By the evaluation method, based on the reality, the battery group with two good consistence indicators of storage performance and usage performance is obtained.

Description

A kind of evaluation method of battery consistency

Technical field

The present invention relates to accumulator

Background technology

Along with petroleum resources are day by day nervous, air pollution is on the rise, and the serial power electric battery more and more is subject to people's attention as secondary energy.But the individual difference of battery cell can produce serious overcharging and collect and the overdischarge problem in electric battery is used, even causes the damage of total system.This is because the terminal voltage of electric battery does not also reach the termination charge condition, and a part of cell termination of having charged, and continues that this part cell must be in overcharge condition in the charging process, the problem thereby generation is overcharged; Another kind of situation is that the electric battery terminal voltage does not reach the termination discharging condition, and ends of discharging in advance of a part of battery, thereby cause this part cell to be in over-discharge state, thus generation overdischarge problem.For electric battery, overcharge or overdischarge all can the grievous injury electric battery, reduce life-span of electric battery and safe in utilization greatly, and seriously hindered application and the development of electric battery as power.

Advantages such as lithium battery has that sparking voltage is stable, operating temperature range is wide, self-discharge rate is low, storage life is long, memory-less effect, volume is little, in light weight and public hazards are little, alternative gradually at present lead-acid battery becomes the main flow of electrokinetic cell.Yet lithium battery is very high to discharging and recharging requirement, and after being composed in series power battery pack, nature requires higher to the harmony that discharges and recharges.Also separating matter when taking place when overcharging can be decomposed and make the temperature and pressure rising of inside battery; Electrolysis material copper can melt and causes internal short-circuit in the negative pole when overdischarge takes place, and elevates the temperature; When external circuit short circuit or discharge current were excessive, because the characteristic inside battery power consumption of high internal resistance increases, temperature also can rise, and can cause the oxidation or the decomposition of electrolytic solution, causes shorter battery life; Overcharge or over-discharge situation can cause battery pressure and temperature to increase sharply when serious, be easy to generate spark, cause burning even blast.Therefore how effectively to address these problems the gordian technique that has become the operation of dynamic lithium battery group efficient stable.

Existing technology proposes the technical scheme of a series of relevant series battery charge and discharge balancing problems.Although these schemes have all proposed many constructive imaginations, integrate and see, most up to now equalizing circuits that adopt, thus by discharging the loop voltage drop that is in the battery of high voltage state is got off to reach balanced.If when being composed in series power battery pack, each cell is carried out the consistance evaluation, be more succinct effective method to avoid operating instability.

Existing method for evaluating consistency is: to cell, calculate the standard deviation of monomer capacity; For battery module, be the standard deviation of the final discharging voltage of computing module.The detection of battery capacity all is that the standard according to GB18287-2000 or QB/T2502-2000 lithium-ions battery general specification detects under the condition of 0.2CsA or 1CA electric current at present.If use the 0.2CsA current detecting, tested an about 6-8 of battery required time hour, use 1CsA testing current required time about 3-4 hour.Therefore battery production producer must be equipped with a large amount of testing apparatuss in the production process of battery, takies bigger plant area.Simultaneously in order to keep the temperature of test environment, must be at the test environment equipment that installs an air-conditioner, the electric weight that above-mentioned method of testing consumes is big.In the production process of entire cell, the test of battery capacity will spend the long time, is a big manpower simultaneously, the investment of material resources, and this present method directiveness is poor, can not accurately estimate the consistance of battery.

Summary of the invention

The objective of the invention is to propose a kind of conforming method of accurate evaluation battery, this evaluation method is from practical situations, propose storge quality and two coincident indicator of usability, estimate the consistance of battery according to the test curve registration of battery under different condition.

For realizing purpose of the present invention, a kind of evaluation method of battery consistency is proposed, this method will be estimated the coincident indicator of usability and estimate the coincident indicator of the coincident indicator of storage characteristics as battery, and the good electric battery of consistance is used and stored to comprehensive above two standard deviations.

Wherein, the evaluation method of the coincident indicator of usability comprises step:

(1) with battery by measure, internal resistance, voltage after sorting, combo, determine rated capacity C;

(2) according to C=It (Ah), P=UI calculates rated power P;

(3) selected respectively 80%P, 100%P, 108%P performance number are carried out permanent power discharge, are PI, the PU curve;

(4) battery discharge compares t discharge time of equal-wattage behind the voltage terminal point;

(5) calculate the standard deviation δ of the identical permanent power discharge time t of each battery by following standard deviation formula,

$\mathrm{\δ}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\Σ}}}{(t_n-\stackrel{\‾}{t})}^2}{n-1}}$ T unit is hour

According to the standard deviation δ that calculates, estimate the coincident indicator of the usability of this batch battery, less than 0.1698 o'clock, it was good to estimate this batch battery usability in described δ value.

The method of estimating the coincident indicator of storage characteristics comprises step:

(1) selects different discharge- rate 2C, 1C, 0.5C, the discharge of 0.2C discharge-rate, do the voltage-capacity curve of each cell;

(2) at identical voltage place, write down the capability value C of each cell, form matrix A, the volume write that same electrical is depressed is at the row of matrix.Calculate the standard deviation of each cell capacity:

$A=\left[\begin{array}{cccc}{C}_{11}& C_{12}& C_{13}& C_{14}\\ C_{21}& C_{22}& C_{23}& C_{24}\\ C_{31}& C_{32}& C_{33}& C_{34}\\ C_{41}& C_{42}& C_{43}& C_{44}\end{array}\right]$

Wherein, C during 2C ₁₁, C ₁₂, C ₁₃, C ₁₄C during IC ₂₁, C ₂₂, C ₂₃, C ₂₄

The standard deviation of capacity when the registration of the cell voltage-capacity curve during (3) according to different discharge-rate is judged identical voltage, the standard deviation δ of the every row of this matrix A as follows:

$\mathrm{\δ}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\Σ}}}{(C_n-\stackrel{\‾}{C})}^2}{n-1}}$ C is a volume percent

According to the standard deviation δ that calculates, estimate the storge quality coincident indicator of this batch battery, the δ value was less than 0.0176 o'clock, and the storge quality that can estimate this batch battery is good.

Description of drawings

Fig. 1 and Fig. 2 are to use the PU and the PI curve of the permanent power discharge of rated power;

Voltage-capacity curve when Fig. 3 is different discharge-rate with Fig. 4.

Embodiment

The coincident indicator of battery of the present invention comprises the coincident indicator of estimating usability and the coincident indicator of estimating storage characteristics

1. estimate the coincident indicator of usability:

Battery by measure, internal resistance, voltage after sorting, combo, determine rated capacity C, again according to C=It (Ah), P=UI calculates rated power P, U is a rated voltage.

Respectively with 80%P, 100%P, the permanent power discharge of 108%P value rated power.Be PI, the PU curve.These two kinds of curves as depicted in figs. 1 and 2, battery discharge behind the voltage terminal point, t discharge time of equal-wattage relatively.Calculate the standard deviation δ of the identical permanent power discharge time t of each battery, the standard deviation formula is:

$\mathrm{\δ}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\Σ}}}{(t_n-\stackrel{\‾}{t})}^2}{n-1}}---\left(1\right)$

T unit is hour

According to the standard deviation δ that calculates, the conforming index of estimating this batch battery is:

δ＜0.1698 o'clock, this Battery pack usability is good.

2. estimate the coincident indicator of storage characteristics:

Storge quality is the standard deviation of the registration of the cell voltage-capacity curve during according to different discharge-rate capacity when judging identical voltage.

The set point value of multiplying power n can be relevant with battery applications, as when being used for EV, HEV or electric tool, the n value is different.Now, do voltage-capacity curve with 2C, 1C, 0.5C, the discharge of 0.2C discharge-rate.Fig. 3 and Fig. 4 are respectively voltage-capacity curves of Cell 1 and Cell 2.

At identical voltage place, calculate Cell 1, Cell 2 ... the standard deviation of capacity: C during 2C ₁₁, C ₁₂, C ₁₃, C ₁₄C during 1C ₂₁, C ₂₂, C ₂₃, C ₂₄ Form matrix A:

$A=\left[\begin{array}{cccc}{C}_{11}& C_{12}& C_{13}& C_{14}\\ C_{21}& C_{22}& C_{23}& C_{24}\\ C_{31}& C_{32}& C_{33}& C_{34}\\ C_{41}& C_{42}& C_{43}& C_{44}\end{array}\right]---\left(2\right)$

The standard δ of the every row of this matrix A is as follows:

$\mathrm{\δ}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\Σ}}}{(C_n-\stackrel{\‾}{C})}^2}{n-1}}---\left(3\right)$

C is a volume percent

δ＜0.0176 o'clock, the storge quality of this batch battery is good.

The good electric battery of consistance can be used and be stored to comprehensive above two standard deviations.

Claims (5)

1. the evaluation method of a battery consistency is characterized in that, will estimate the coincident indicator of usability and estimate the coincident indicator of the coincident indicator of storage characteristics as battery, and the good electric battery of consistance is used and stored to comprehensive above two standard deviations.

2. evaluation method according to claim 1 is characterized in that, the evaluation method of the coincident indicator of usability comprises step:

(1) with battery by measure, internal resistance, voltage after sorting, combo, determine rated capacity C;

(2) according to C=It (Ah), P=UI calculates rated power P;

(3) selected respectively 80%P, 100%P, 108%P performance number are carried out permanent power discharge, are PI, the PU curve;

(4) battery discharge compares t discharge time of equal-wattage behind the voltage terminal point;

(5) calculate the standard deviation δ of the identical permanent power discharge time t of each battery by following standard deviation formula,

$\mathrm{\δ}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\Σ}}}{(t_n-\stackrel{\‾}{t})}^2}{n-1}}$ T unit is hour

According to the standard deviation δ that calculates, estimate the coincident indicator of the usability of this batch battery.

3. evaluation method according to claim 1 and 2 is characterized in that, the method for the coincident indicator of described evaluation storage characteristics comprises step:

(1) selects different discharge-rate 2C, 1C, 0.5C, the discharge of 0.2C discharge-rate, do the voltage-capacity curve of each cell;

(2) at identical voltage place, write down the capability value C of each cell, form matrix A, the volume write that same electrical is depressed is at the row of matrix.Calculate the standard deviation of each cell capacity:

$A=\left[\begin{array}{cccc}{C}_{11}& C_{12}& C_{13}& C_{14}\\ C_{21}& C_{22}& C_{23}& C_{24}\\ C_{31}& C_{32}& C_{33}& C_{34}\\ C_{41}& C_{42}& C_{43}& C_{44}\end{array}\right]$

Wherein, C during 2C ₁₁, C ₁₂, C ₁₃, C ₁₄C during 1C ₂₁, C ₂₂, C ₂₃, C ₂₄

The standard deviation of capacity when the registration of the cell voltage-capacity curve during (3) according to different discharge-rate is judged identical voltage, the standard deviation δ of the every row of this matrix A as follows:

$\mathrm{\δ}=\sqrt{\frac{\underset{n=1}{\overset{n}{\mathrm{\Σ}}}{(C_n-\stackrel{\‾}{C})}^2}{n-1}}$ C is a volume percent

According to the standard deviation δ that calculates, estimate the storge quality coincident indicator of this batch battery.

4. evaluation method according to claim 2 is characterized in that, described δ value was less than 0.1698 o'clock, and it is good to estimate this batch battery usability.

5. evaluation method according to claim 3 is characterized in that, described δ value was less than 0.0176 o'clock, and the storge quality that can estimate this batch battery is good.

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