CN108254699A - The SOC estimation method of lithium battery - Google Patents
The SOC estimation method of lithium battery Download PDFInfo
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- CN108254699A CN108254699A CN201810083576.7A CN201810083576A CN108254699A CN 108254699 A CN108254699 A CN 108254699A CN 201810083576 A CN201810083576 A CN 201810083576A CN 108254699 A CN108254699 A CN 108254699A
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- lithium battery
- state
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- charge
- battery
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
Abstract
The invention discloses a kind of SOC estimation method of lithium battery, including obtain lithium battery to be analyzed can not electricity consumption and open-circuit voltage and state-of-charge curve；Obtain the state-of-charge initial value of lithium battery；Estimation on line is carried out to the state-of-charge of lithium battery using ampere-hour method.The SOC estimation method of this lithium battery provided by the invention, by to lithium battery can not electricity consumption calculating and be added into the calculating of state-of-charge, so that the method for the present invention can more accurately estimate the state-of-charge of lithium battery, and the method for the present invention is simple and reliable.
Description
Technical field
Present invention relates particularly to a kind of SOC estimation methods of lithium battery.
Background technology
With the development of economic technology, battery technology has also obtained significant progress.Battery energy management is as in recent years
One of technology of rapid development, importance are self-evident.Battery charge state (State of Charge, SOC) is battery institute
The ratio of residual electricity amount and specified electric quantity is one of key technology of battery energy management.
At present, the SOC methods of estimation that domestic and international researcher proposes focus on two kinds in form.One kind is based on battery circuit
The SOC methods of estimation of model, i.e. Physical.Such as ampere-hour method, open circuit voltage method.Another kind is intelligent method, and complexity is high.Such as card
Kalman Filtering method, support vector regression algorithm etc..
Ampere-hour method, i.e. Ah counting method refer to the method that SOC is estimated by the time integral of load current in discharge time.
The algorithm can increase with the accumulation of discharge time, initial SOC value cumulative errors, influence SOC estimated accuracies, and have ignored electricity
The capacity fluctuation problem that the non-constancy and different temperatures of the unavailable capacity in pond are brought.
Open circuit voltage method is to obtain certain moment using open-circuit voltage (OCV) during battery standing and certain functional relation of SOC
SOC value.In the case of the unknown SOC initial values of people, which can effectively estimate SOC value.Although obtaining OCV-
Before SOC curves, which needs through a large amount of actual tests, and power battery is needed to stand centainly during experiment
Time can just obtain the relational expression of OCV and SOC.
Kalman filtering method is one of Typical Representative of intelligent method, is commonly used for State Observer.Common karr
Graceful filtering algorithm is built upon on the basis of battery status model, obtains model parameter and the correspondence of SOC.Work as electric vehicle
When travelling on complex working condition, power battery curent change is violent, and Kalman filtering method estimation SOC has higher precision, but whole
A calculating process operand is big, complexity is high.In addition, the algorithm needs high-precision battery model, so system modelling difficulty
Greatly, the foundation of state space equation also acquires a certain degree of difficulty.
Support vector regression algorithm needs to acquire a large amount of experimental data and measured data carries out recurrence inquiry learning, until
To optimal objective.Moreover, the algorithm is equally high to training method requirement and needs to be continuously updated training method.Although
Support vector regression algorithm learning ability is strong, precision is high, and still, the algorithm is not mature enough at present, is still a very new calculation
Method, opposite complexity is excessively high, and practical application is poor, still needs to further improve.
Invention content
The purpose of the present invention is to provide a kind of SOC estimations are accurate, and the SOC estimations of the simple and reliable lithium battery of method
Method.
The SOC estimation method of this lithium battery provided by the invention, includes the following steps：
S1. obtain lithium battery to be analyzed can not electricity consumption；
S2. the open-circuit voltage of lithium battery to be analyzed and the curve of state-of-charge are obtained；
S3. according to the open-circuit voltage of the obtained lithium batteries of step S2 and the curve of state-of-charge, the charged of lithium battery is obtained
State initial value；
S4. estimation on line is carried out to the state-of-charge of lithium battery using ampere-hour method.
Acquisition lithium battery to be analyzed described in step S1 can not electricity consumption, specially according to KiBaM battery models
Characteristic, at room temperature, in time zone [t0,t1] in, it is discharged using constant current I lithium battery to be analyzed, so as to obtain this
Lithium battery can not electricity consumption expression formula.
The lithium battery can not electricity consumption, specially calculated using following formula：
C in formulaun(t) for lithium battery t moment can not electricity consumption, Cun(t0) for electric discharge initial time Cun(t) value,
Cun(t1) it is the C for standing initial timeun(t) value, k'=k/ [c (1-c)], k are rate constant, and c is the capacity ratio of battery, and I is
Constant current.
Estimation on line is carried out to the state-of-charge of lithium battery using ampere-hour method described in step S4, is specially calculated using following
Formula is estimated：
State-of-charges of the SOC (t) for the lithium battery of t moment, SOC in formulainThe SOC value for original state of discharging for lithium battery,
CmaxFor battery rated capacity, Cun(t) for lithium battery in t moment can not electricity consumption.
The SOC estimation method of this lithium battery provided by the invention, by lithium battery can not electricity consumption calculating simultaneously
It is added into the calculating of state-of-charge, so that the method for the present invention can more accurately estimate the charged shape of lithium battery
State, and the method for the present invention is simple and reliable.
Description of the drawings
Fig. 1 is the method flow diagram of the method for the present invention.
The schematic diagram according to KiBaM battery models of Fig. 2 positions the method for the present invention.
Fig. 3 is surveyed the comparison figure of terminal voltage by the method for the present invention, single order mixing PNGV models with experiment.
Fig. 4 is surveyed the comparison figure of SOC by the method for the present invention, single order mixing PNGV models with experiment.
Specific embodiment
It is the method flow diagram of the method for the present invention as shown in Figure 1：The SOC estimation sides of this lithium battery provided by the invention
Method includes the following steps：
S1. obtain lithium battery to be analyzed can not electricity consumption；Specially according to characteristic (its mould of KiBaM battery models
Type figure is as shown in Figure 2), at 25 DEG C of room temperature, in time zone [t0,t1] in, using constant current I to lithium battery to be analyzed
Electric discharge, so as to obtain the lithium battery can not electricity consumption expression formula；
It is described can not electricity consumption expression formula, be calculated using following process：
C (0 ＜ c ＜ 1) is the capacity ratio of battery, and available power accounts for the ratio of total electricity when representing battery original state；K tables
Show constraint rate constant of the electricity source stream to available power source；Two source height h1=y1/ c, h2=y2/ (1-c), y1And y2Respectively
The total electricity of two power supplys, the differential equation are as follows：
In time domain [t0,t1] in, it is discharged using constant current I, Laplace transform is carried out to upper two formula respectively, after calculation processing
As shown in formula：
The calculation formula of two source height difference δ (t) is as follows：
Initial state y1(t0)=y1,0=cC, y2(t0)=y2,0=(1-c) C, y0=y1,0+y2,0, C is that battery is always electric
Amount；According to above-mentioned formula, two power supply total electricity equations after Laplace transform are brought into two source height eikonal equations, so as to obtain
Following formula：
δ (t in formula0) and δ (t1) it is δ (t) values for discharging and standing initial time,WithThe Central Military Commission
Zero input response；
Then, by δ (t) with can not electricity consumption Cun(t) relationship is then shown below：
Cun(t)=(1-c) δ (t)
Then, by above-mentioned expression formula, you can obtaining can not electricity consumption Cun(t) expression formula is：
C in formulaun(t) for lithium battery t moment can not electricity consumption, Cun(t0) for electric discharge initial time Cun(t) value,
Cun(t1) it is the C for standing initial timeun(t) value, k'=k/ [c (1-c)] (k is rate constant), c are the capacity ratio of battery；I is
Constant current；
S2. the open-circuit voltage of lithium battery to be analyzed and the curve of state-of-charge are obtained；
S3. according to the open-circuit voltage of the obtained lithium batteries of step S2 and the curve of state-of-charge, the charged of lithium battery is obtained
State initial value；
S4. estimation on line is carried out to the state-of-charge of lithium battery using ampere-hour method, is specially estimated using following formula
It calculates：
State-of-charges of the SOC (t) for the lithium battery of t moment, SOC in formulainThe SOC value for original state of discharging for lithium battery,
CmaxFor battery rated capacity, Cun(t) for lithium battery in t moment can not electricity consumption.
Fig. 2 and Fig. 3 is surveyed the comparison figure of terminal voltage and SOC value by the method for the present invention, single order mixing PNGV models with experiment；
Below with the advantage of a description of test the method for the present invention：
Experimental study object is the pure electric vehicle LiFePO of the model LAF288V70Ah of domestic certain producer production4Battery
Packet carries out charge-discharge test, charge cutoff voltage 350.4V, rated voltage 288V, discharge cut-off voltage 240V, rated capacity
70Ah, maximum duration discharge current 2C, capacity is than c=0.91731, k '=0.000436.It it is 25 DEG C in Cell Experimentation An environment
Under the conditions of, constant-current discharge is carried out to SOC as 0.95 using 1C electric currents first, stands 1 hour later, it is real to carry out a HPPC pulse
It tests, constant-current discharge is then carried out to SOC as 0.9 using 1C electric currents again, a HPPC pulse test is carried out again after standing 1 hour.Together
Sample, according to above step SOC be respectively 0.85,0.8,0.75 ..., in turn carry out HPPC pulse tests at 0.05.It utilizes
Cftool tool boxes in MATLAB simulation softwares, carry out curve fitting to collected device parameter values, and fit procedure makes
Filter out optimal matched curve with least square method, i.e. curves of the R-square closest to 1.After the completion of modeling, to lithium battery
Carry out 1C constant current periodic discharges, during Fig. 2 and Fig. 3 are discharge test, the method for the present invention, single order mixing PNGV models and
What terminal voltage was surveyed in experiment must compare figure with SOC value.It can be seen that the method for the present invention has good terminal voltage and SOC estimation essences
Degree.
Claims (4)
1. a kind of SOC estimation method of lithium battery, includes the following steps：
S1. obtain lithium battery to be analyzed can not electricity consumption；
S2. the open-circuit voltage of lithium battery to be analyzed and the curve of state-of-charge are obtained；
S3. according to the open-circuit voltage of the obtained lithium batteries of step S2 and the curve of state-of-charge, the state-of-charge of lithium battery is obtained
Initial value；
S4. estimation on line is carried out to the state-of-charge of lithium battery using ampere-hour method.
2. the SOC estimation method of lithium battery according to claim 1, it is characterised in that the acquisition described in step S1 is to be analyzed
Lithium battery can not electricity consumption, specially according to the characteristic of KiBaM battery models, at room temperature, in time zone [t0,t1]
In, discharged using constant current I lithium battery to be analyzed, so as to obtain the lithium battery can not electricity consumption expression formula.
3. the SOC estimation method of lithium battery according to claim 2, it is characterised in that the lithium battery can not electricity consumption
Amount is specially calculated using following formula：
C in formulaun(t) for lithium battery t moment can not electricity consumption, Cun(t0) for electric discharge initial time Cun(t) value, Cun(t1)
To stand the C of initial timeun(t) value, k'=k/ [c (1-c)], k are rate constant, and c is the capacity ratio of battery, and I is constant electricity
Stream.
4. the SOC estimation method of lithium battery according to claim 3, it is characterised in that the use ampere-hour method described in step S4
Estimation on line is carried out to the state-of-charge of lithium battery, is specially estimated using following formula：
State-of-charges of the SOC (t) for the lithium battery of t moment, SOC in formulainThe SOC value for original state of discharging for lithium battery, CmaxFor
Battery rated capacity, Cun(t) for lithium battery in t moment can not electricity consumption.
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Citations (3)
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| CN105116346A (en) * | 2015-09-15 | 2015-12-02 | 盐城工业职业技术学院 | Series-connected battery system and method for estimating state of charge thereof |
| CN105548898A (en) * | 2015-12-25 | 2016-05-04 | 华南理工大学 | Lithium battery SOC estimation method of off-line data segmentation correction |
| CN106872901A (en) * | 2017-02-21 | 2017-06-20 | 山东大学 | KiBaM fractional orders equivalent circuit comprehensive characteristics battery model and parameter identification method |
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- 2018-01-29 CN CN201810083576.7A patent/CN108254699A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105116346A (en) * | 2015-09-15 | 2015-12-02 | 盐城工业职业技术学院 | Series-connected battery system and method for estimating state of charge thereof |
| CN105548898A (en) * | 2015-12-25 | 2016-05-04 | 华南理工大学 | Lithium battery SOC estimation method of off-line data segmentation correction |
| CN106872901A (en) * | 2017-02-21 | 2017-06-20 | 山东大学 | KiBaM fractional orders equivalent circuit comprehensive characteristics battery model and parameter identification method |
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| 李欣然等: "锂离子电池容量的预测建模及其仿真研究", 《系统仿真学报》 * |
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