CN109901083A

CN109901083A - A kind of power battery OCV curve on-line reorganization method

Info

Publication number: CN109901083A
Application number: CN201910256395.4A
Authority: CN
Inventors: 熊瑞; 雷浩
Original assignee: Beijing Institute of Technology BIT
Current assignee: Beijing Institute of Technology BIT
Priority date: 2019-04-01
Filing date: 2019-04-01
Publication date: 2019-06-18
Anticipated expiration: 2039-04-01
Also published as: CN109901083B

Abstract

The present invention provides a kind of power battery OCV curve on-line reorganization methods, based on on-line parameter identification and SOC estimated result, carry out on-line reorganization to OCV curve.Since there are inconsistencies for the OCV curve between each battery cell, and with the aging of the variation of temperature and battery, OCV curve can also change, and therefore, the OCV curve of each battery cell is unknown.Traditional open-circuit voltage test experiments method, it can only obtain OCV curve of the specific monomer under specific environment state, and the present invention can be recognized according to on-line parameter and SOC estimated result carries out on-line reorganization to OCV curve, a large amount of experimental period can not only be saved, and local correction can be carried out to OCV curve online, in time.

Description

A kind of power battery OCV curve on-line reorganization method

Technical field

The present invention relates to the reconstruct of the open circuit voltage curve of electrokinetic cell system administrative skill field, especially power battery Technology.

Background technique

Currently, the power battery state estimation algorithm based on model generallys use open-circuit voltage (OCV) and state-of-charge (SOC) functional relation is modified the SOC estimation that current integration method obtains, therefore SOC estimated accuracy is highly dependent on The precision of OCV-SOC curve.OCV-SOC curve is usually obtained by OCV test experiments, and time-consuming for OCV test experiments, and can only Obtain OCV curve of the specific monomer under specific environment state.And there are inconsistent for the OCV curve between each battery cell Property, and with the aging of the variation of temperature and battery, OCV curve can also change, so each battery cell is in different rings OCV curve under border and ageing state is unknown.Therefore, this field needs one kind that can obtain OCV-SOC function pass online System, the method for reconstructing OCV curve carry out on-line amending and update to OCV curve.

Summary of the invention

For technical problem present in above-mentioned this field, the present invention provides a kind of power battery OCV curves to weigh online Structure method, specifically includes the following steps:

Step 1 rewrites the OCV-SOC functional relation expression formula of polynomial form；

Step 2, real-time online obtain and store the end voltage and current data in power battery operational process；

Step 3 carries out on-line parameter identification, obtains OCV identification result；

Step 4 carries out SOC estimation, obtains SOC estimated result；

Step 5, according to end voltage prediction error, to hold voltage error to be less than setting value as condition, to meeting the item The data point of part is screened and is counted；

Step 6 judges whether the data point accumulated quantity of screening reaches the condition of triggering OCV reconfiguration program, whenever Accumulated quantity reaches the trigger condition, and primary reconstruct is carried out to OCV curve；

Step 7, the parameter identification for carrying out subsequent time and SOC estimation.

Further, the OCV-SOC functional relation expression formula of polynomial form is rewritten in the step 1, specifically It include: that n+1 coefficient is shared for a polynomial of degree n function, then its expression formula can not be mutually overlapped by n+1 in plane Point determines, can rewrite polynomial of degree n function are as follows:

In formula, U_OCIndicate the n+1 point that open-circuit voltage OCV, z indicate that state-of-charge SOC, the OCV curve of battery passes through Coordinate is respectively (x₀,y₀),(x₁,y₁),…,(x_n,y_n), defining these points is control point；z_nIt is SOC from 0 power to n times side The vector of composition, y are the vector of control point ordinate composition, and X is the square that control point abscissa is formed from 0 power to n times side Battle array；The abscissa at control point is the real number being not mutually equal, and can voluntarily be selected according to actual needs.Due to the physical significance of SOC, The abscissa at control point is usually between 0 to 100%；After the abscissa at selected control point, the ordinate at control point be can be used as Initial OCV song can be obtained in the coefficient of the OCV-SOC functional relation expression formula, the initial ordinate vector for obtaining control point Line.

Further, the step 6 specifically includes:

Step 6.1, the SOC value for reading each data point obtained through step 5 screening determines the locating area SOC of its difference Between；

Step 6.2, according to the section SOC, corresponding control point is activated, the ordinate at the control point being activated is selected For variable to be updated, the coordinate at the control point not being activated is then remained unchanged；

Step 6.3, OCV the and SOC data for each data point screened are fitted, update the control point being activated Coordinate, obtain the OCV curve of on-line reorganization.Functional relation based on OCV-SOC can be used to subsequent SOC estimation.

The beneficial effect that the present invention can be generated is: OCV-SOC functional relation is rewritten into and is sat with control point by the present invention It is designated as the form of coefficient, and on-line parameter identification and SOC estimated result are screened according to end voltage prediction error, to pick Except the biggish point of error prevents from generating interference to OCV curve-fitting results；The section SOC according to locating for data point, to corresponding Partial controll point is updated, to realize the on-line reorganization of OCV-SOC；The OCV curve of on-line reorganization, can further apply The SOC of battery estimates.

Detailed description of the invention

Fig. 1 is the flow diagram of method provided by the present invention

Fig. 2 is the benchmark OCV curve that the OCV test data of #4 obtains according to battery cell #1, #2, #3

Fig. 3 is the OCV restructuring procedure of monomer #5 UDDS operating condition at 25 DEG C

Fig. 4 is monomer #5 UDDS operating condition at 10 DEG C, SOC estimated result and its error during OCV on-line reorganization

Fig. 5 is monomer #5 UDDS operating condition at 25 DEG C, SOC estimated result and its error during OCV on-line reorganization

Fig. 6 is monomer #5 UDDS operating condition at 40 DEG C, SOC estimated result and its error during OCV on-line reorganization

Specific embodiment

It is detailed to a kind of power battery OCV curve on-line reorganization method progress provided by the present invention with reference to the accompanying drawing Explanation.

Power battery OCV curve on-line reorganization method provided by the present invention, as shown in Figure 1, specifically including following step It is rapid:

Step 4 carries out SOC estimation, obtains SOC estimated result；

In one embodiment of the invention, selecting nickel-cobalt-manganese ternary lithium battery is research object, and rated capacity is 2Ah, charge and discharge blanking voltage are respectively 4.1V and 3.0V.Experiment condition is Metro cycle operating condition (UDDS).To battery Monomer #1, #2, #3,10 DEG C of #4 progress, 25 DEG C, 40 DEG C of OCV test experiments, the OCV data mean value that experiment is obtained is as base Quasi- OCV curve, as shown in Figure 2.Due to not carrying out any OCV test experiments to monomer #5, the OCV curve of monomer #5 is not Know.With OCV curve on-line reorganization method proposed by the present invention, the OCV curve of #5 is reconstructed under UDDS operating condition, and SOC estimation is carried out, to illustrate the validity of the method on-line reorganization OCV curve.

Fig. 3 show the OCV curve Reconstruction process of monomer #5 UDDS operating condition at 25 DEG C.In this example, often add up 1000 Qualified valid data point carries out an OCV curve Reconstruction, has carried out 17 reconstruct altogether.As seen from Figure 3, exist In UDDS operating condition, with the electric discharge of battery, the restructuring procedure of OCV curve is since the high section SOC, gradually in, the low area SOC Between carry out, finally with the completion of discharge process, the OCV curve in the full section SOC is completed reconstruct.Illustrate that the present invention is mentioned The on-line reorganization of OCV curve may be implemented in the method for confession.

Fig. 4, Fig. 5, Fig. 6 are respectively that monomer #5 UDDS operating condition at 10 DEG C, 25 DEG C, 40 DEG C carries out on-line reorganization to OCV SOC estimated result.In the case that the OCV curve that battery cell #5 be can be seen that by Fig. 4, Fig. 5, Fig. 6 is unknown, the present invention is utilized Institute's providing method carries out the OCV curve that on-line reorganization obtains and carries out SOC estimation, and the maximum that SOC estimates at 10 DEG C to 40 DEG C is accidentally Difference is below 2.5%.Illustrating method provided by the present invention at different temperatures has preferable OCV curve Reconstruction effect, And good SOC estimated accuracy may be implemented.

Basic principles and main features of the invention have been shown and described in above-described specific embodiment.This field Technical staff it should be appreciated that the present invention is not limited to the above embodiments, what is described in the above embodiment and the description is only Illustrate the principle of the present invention, in the case where not departing from spirit of that invention and principle, the present invention also has various change and repairs Change, these change and modification all fall within the protetion scope of the claimed invention.The scope of protection of present invention is by appended power Benefit requires and its equivalent thereof.

Claims

1. a kind of power battery OCV curve on-line reorganization method, it is characterised in that: specifically includes the following steps:

Step 4 carries out SOC estimation, obtains SOC estimated result；

Step 5, according to end voltage prediction error, to hold voltage error to be less than setting value as condition, to meeting the condition Data point is screened and is counted；

Step 6 judges whether the data point accumulated quantity of screening reaches the condition of triggering OCV reconfiguration program, whenever accumulative Quantity reaches the trigger condition, and primary reconstruct is carried out to OCV curve；

2. the method as described in claim 1, it is characterised in that: closed in the step 1 to the OCV-SOC function of polynomial form It is that expression formula is rewritten, specifically includes: for a polynomial of degree n function, sharing n+1 coefficient, then its expression formula can be by The point that n+1 are not overlapped mutually in plane determines, can rewrite polynomial of degree n function are as follows:

In formula, U_OCIndicate the coordinate for the n+1 point that open-circuit voltage OCV, z indicate that state-of-charge SOC, the OCV curve of battery passes through Respectively (x₀,y₀),(x₁,y₁),…,(x_n,y_n), defining these points is control point；z_nIt is formed for SOC from 0 power to n times side Vector, y are the vector of control point ordinate composition, and X is the matrix that control point abscissa is formed from 0 power to n times side；Control point Abscissa be the real number being not mutually equal.

3. method according to claim 2, it is characterised in that: the step 6 specifically includes:

Step 6.1, the SOC value for reading each data point obtained through step 5 screening determines the locating section SOC of its difference；

Step 6.2, according to the section SOC, corresponding control point is activated, the ordinate at the control point being activated is chosen as to more The coordinate of new variable, the control point not being activated then remains unchanged；

Step 6.3, OCV the and SOC data for each data point screened are fitted, update the seat at the control point being activated Mark, obtains the OCV curve of on-line reorganization.Functional relation based on OCV-SOC can be used to subsequent SOC estimation.