CN102662148B - On-line feedback battery state of charge (SOC) predicting method - Google Patents

Abstract

The invention relates to the technical field of storage battery state of charge prediction, and discloses an online feedback storage battery SOC prediction method. During the online operation of the storage battery, the method uses historical data to correct the parameters of the SOC estimation model. The method takes into account temperature, coulomb For the impact of efficiency and self-discharge on battery SOC, it is only necessary to monitor the basic operating parameters of the battery. During battery operation, as long as the conditions are met, the correlation coefficient is corrected, and the coefficient value is repeatedly corrected. As time accumulates, the estimation result of SOC will be more accurate. It is close to the true value, so the accuracy is high, and it can realize online prediction of battery SOC.

Description

Online feedback formula accumulator SOC Forecasting Methodology

Technical field

The present invention relates to storage battery charge state (State of Charge, SOC) electric powder prediction, be specifically related to a kind of online feedback formula accumulator SOC Forecasting Methodology.

Background technology

State-of-charge (the State of Charge of accumulator, SOC) for describing the residual capacity of accumulator, relatively more unified is from electric weight viewpoint definition SOC at present, it is defined as battery under certain discharge-rate, the ratio of rated capacity under residual capacity and the same terms, it is the important parameter in battery use procedure.SOC can effectively learn the use state of accumulator accurately, and the charge status of management of battery makes its equilibrium and prevents from overcharging, crosses and put, and improves the serviceable life of battery pack; Can also reflect more accurately continual mileage for accumulator SOC used for electric vehicle, remind human pilot when charge or change battery.Therefore, the estimation of SOC is a study hotspot of battery management.The Forecasting Methodology of SOC mainly contains following several at present:

(1) infer the size of SOC according to the variation of inside battery parameter, as the concentration of medium of lead-acid battery and SOC have the most direct relation, but battery can not reach balance all the time in charge and discharge process medium concentration, and lead-acid battery is due to its sealing, makes the method be difficult to the estimation online of the SOC that is applied to battery;

(2) open-circuit voltage method, is applied to inside and reaches the accumulator of equilibrium state, and its open-circuit voltage and SOC have good mapping relations, but the method can not be used for estimation online;

(3) ampere-hour integral method, this is the more method of applying at present, simple, its basic thought is that the discharge electricity amount equivalence under different electric currents is become to the discharge electricity amount under certain specific currents, judge SOC according to dump energy again, but discharge coefficient changes with the variation of several factors, be difficult to obtain stable exact value.In addition, how considering the problem of self-discharge of battery and efficiency for charge-discharge in ampere-hour integral method, how to correct because error constantly accumulates, the finally problem of possibility substantial deviation actual value of SOC estimated value, is the difficult point place of improving the accuracy of ampere-hour integral method;

(4) internal resistance method, set up the corresponding relation of the internal resistance of cell and SOC by test, therefore need to set up model and come the internal resistance of estimating battery, obtain SOC according to the internal resistance calculating again, the method calculated amount is larger, and need set up battery model, the accuracy of model must affect the accuracy of the estimation result of SOC;

(5) Kalman filter method, by a series of mathematical formulae recursive descriptions, carrys out the state of estimation procedure by a kind of efficient computing method, and makes to estimate square error minimum.Its basic thought is: adopt the state-space model of signal and noise, utilize the estimated value of previous moment and the observed reading of now to upgrade the estimation to state variable, obtain the estimated value of present moment.The method need to be set up battery model, and the foundation of equation and solve all more complicated, be difficult to practical application.

What be most widely used at present is the SOC estimation based on ampere-hour integral method.Publication number is that the Chinese patent application " assay method of battery charge state " of CN101359036A adopts basic ampere-hour method to add correction function φ (t) to estimate SOC, as shown in the formula:

$\mathrm{SOC}\left(t\right)=\frac{C_0-\underset{0}{\overset{t}{\∫}}i\left(\mathrm{\τ}\right)\mathrm{d\τ}}{C_n}+\mathrm{\φ}\left(t\right)$

Wherein, the mensuration of correction factor φ (t) is adopted with the following method: use formula

calculate the SOC theoretical value SOC in multiple moment _reason, x represents a moment in multiple moment, the SOC actual value SOC recording in the plurality of moment _real, then adopt least square method to calculate for expressing SOC _reasonand SOC _realdifference and between multiple moment used, be related to correction function φ (t).

The method relies on electrical quantity measurement arrangement and determines initial capacity C ₀, accumulator dump energy or electric quantity change amount, i.e. the SOC actual value SOC in described multiple moment _realacquisition and degree of accuracy all depend on additional electrical quantity measurement arrangement;

Publication number is the initial capacity that Chinese patent application " evaluation method of a kind of automobile batteries SOC " the application open-circuit voltage of CN102162836 and historical results are determined battery, with ampere-hour integral method estimation SOC, consideration affects all kinds of factors of SOC proofreaies and correct SOC, and compensation correction Consideration comprises:

1, efficiency for charge-discharge, according to Peukert experimental formula, adopts look-up table to revise the SOC under different electric currents;

2, temperature, gathers lot of experimental data and obtains in advance battery temperature coefficient;

3, the consistance situation of battery, arranges multiple points of battery otherness, according to different discrepancys, SOC is revised;

4, the self discharge of battery, pre-estimates the self discharge situation of accumulator by great many of experiments method, proofread and correct by data lookup table method;

5, aging, SOC _age=(SOC-A _f) (1-A _f), SOC _agefor the SOC value after compensation of ageing, A _ffor senescence-factor.

When battery is full of electricity, directly putting SOC numerical value is 100%, and while utilizing open-circuit voltage method to obtain SOC, if battery context temperature exceedes battery operated ultimate temperature, now SOC is 0, and cuts off charging and discharging circuit with protection battery.But coefficient is by the acquisition of tabling look-up, can not be with the change such as serviceable life, degree of aging of battery, along with the coefficient of its acquisition of accumulation of time can not truly reflect battery the present situation, accuracy meeting is affected; And the acquisition of data need be done a large amount of experiments in table, and with kind, the combined method difference of electric battery, data all will again be done experiment and draw, are difficult to realize.

Patented claim " Method for Measuring SOC of a Battery in a Battery Management System and the Apparatus Thereof " is asked SOC for the method for open-circuit voltage-ampere-hour integration equally, its open-circuit voltage is tried to achieve by building circuit model, and the shortcoming of this method is that the precision of battery capacity estimation depends on the precision of battery model.

To sum up, existing ampere-hour integration modification method or depend on external device (ED), or need lot of experimental data form the basis, and equipment complexity, and coefficient can not be realized adaptively correcting.

Summary of the invention

(1) technical matters that will solve

The technical problem to be solved in the present invention is: how to improve accumulator SOC prediction accuracy.

(2) technical scheme

For solving the problems of the technologies described above, the invention provides a kind of online feedback formula accumulator SOC Forecasting Methodology, comprise the following steps:

S1, by the duty of accumulator be divided into be full of standing, discharge standing, common leaving standstill and four kinds of common operations, the initialization state of juxtaposition accumulator is common operation, described in be full of and leave standstill and refer to that accumulator reaches floating charge condition and keeps a period of time more than; Discharge leave standstill refer to accumulator reach electric discharge lower limit and keep a period of time more than; Common standing finger charging current is less than certain value, and more than not meeting floating charge condition and keeping a period of time, or discharge current is less than certain value, more than not meeting electric discharge lower limit and keeping a period of time; State beyond above three kinds of states is common operation;

S2, collection battery tension U, electric current I, temperature T, then enter step S3;

S3, judge the duty of accumulator, if be full of standingly, enter step S4, if discharge standingly, enter step S5, leave standstill if common, enter step S6, if common operation enters step S7;

S4, refresh state-of-charge SOC, then enter step S8;

S5, refresh SOC, then enter step S9;

S6, common time of repose timing is started, refresh SOC, judge U and U ₀whether difference is greater than set-point, if meet, proofreaies and correct self discharge coefficient, then enters step S10, and wherein U is current time magnitude of voltage, U ₀for entering the magnitude of voltage in common standing moment;

S7, refresh SOC, then enter step S11;

S8, carry out the first state conversion judgement, then return to step S2;

S9, carry out the second state conversion judgement, then return to step S2;

S10, carry out third state conversion judgement, then return to step S2;

S11, carry out the 4th state conversion judgement, then return to step S2;

Wherein, described in step S8, the determination methods of the first state conversion judgement is as follows: judge whether battery current is greater than set-point I ₂and the retention time is greater than set-point t ₃if, meet, put common running status, judge whether to meet electric current simultaneously and be less than set-point I ₁, voltage is less than set-point U ₁and the retention time is greater than set-point t ₄if, meet, put common static condition and record now magnitude of voltage U ₀now moment t ₀.

Preferably, the step that refreshes SOC in step S4, S5, S6, S7 comprises the steps: to judge whether common time of repose is greater than set-point t5, if meet, using current magnitude of voltage as open-circuit voltage values, refresh battery initial capacity value SOC according to following formula (1) ₀, then calculate SOC, if do not meet, directly calculate SOC

SOC ₀＝f(OCV) （1）。

Preferably, in step S4, S5, S6, S7, according to SO C appraising model calculate SOC, described SOC appraising model as shown in Equation (2):

$\mathrm{SOC}={\mathrm{SOC}}_0-\left[\underset{t1}{\overset{t}{\&Integral;}}{K}_1{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HDA00001619791300011.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\mathrm{Idt}\right]/C_B-\underset{t1}{\overset{t}{\&Integral;}}{k}_{\mathrm{dis}}\mathrm{dt}---\left(2\right)$

Wherein, K ₁for coulomb efficiency factor, K ₂for temperature coefficient; K ₁representative is under standard temperature, with normalized current I _bthe electric weight Q emitting _iBfrom the electric weight Q emitting with different discharge current I _iratio, K ₂representative is at standard temperature T _bthe capacity Q of lower accumulator _tBcapacity Q with accumulator under temperature T _tratio, k _disfor self discharge coefficient, C _bfor the rated capacity of accumulator, t1, t represent not in the same time.

Preferably, described in step S9, the determination methods of the second state conversion judgement is as follows: judge whether battery current is greater than set-point I ₂and the retention time is greater than set-point t ₃if, meet, put common running status.

Preferably, the determination methods of the conversion of the third state described in step S10 judgement is as follows: judge that battery current is less than set-point I ₁and voltage reaches sparking voltage value lower limit and the retention time is greater than set-point t ₄if, meet, put static condition, timing finishes, and judges whether battery current is greater than set-point I simultaneously ₂and the retention time is greater than set-point t ₃if, meet, put common running status, timing finishes.

Preferably, described in step S11, the determination methods of the 4th state conversion judgement is as follows:

121, judge whether battery current I is less than I ₁and the retention time is greater than t ₂if, meet, enter step 122;

122, judge whether battery tension reaches float charge voltage value, if meet, enter step 123, otherwise enter step 124;

123, make SOC=100%, SOC ₀=100%, enter step 125;

124, judge whether battery tension reaches electric discharge lower limit, if meet, enter step 128, if do not meet, enter step 129;

125, judge whether that meeting for the first time I is less than I ₁and the retention time is greater than t ₂if, meet, enter step 126, if do not meet, enter step 127;

126, put and be full of static condition;

127, proofread and correct and wait to revise coulomb efficiency related coefficient n, a positive temperature coefficient (PTC) k to be repaired _t, enter step 126;

128, make SOC=0%, SOC ₀=0%, enter step 1210;

129, put common static condition, record now magnitude of voltage U ₀now moment t ₀;

1210, judge whether that meeting for the first time I is less than I ₁and the retention time is greater than t ₂if, meet, enter step 1211, if do not meet, enter step 1212;

1211, put static condition;

1212, correction coefficient n, k _t, enter step 1211.

Preferably, correction coefficient n, k in step 127 and 1212 _tstep be specially: battery enters to be first full of and leaves standstill or while discharging static condition, be designated as t ₀₀in the moment, correspondingly put SOC=SOC ₀=100% or put SOC=SOC ₀=0%, leave standstill or while discharging static condition, be designated as t when again entering to be full of ₁₁in the moment, correspondingly put SOC=SOC ₀=100% or put SOC=SOC ₀=0%, calculate the A value in formula (7):

$\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{\left(\frac{I_i}{I_B}\right)}^{n-1}\&CenterDot;\frac{1}{1+k_T(T_i-20)}\&CenterDot;I_i\&CenterDot;\mathrm{\&Delta;t}=A---\left(7\right)$

A is the determined value calculating, and wherein gets

known n ∈ [1.15,1.42], k _t∈ [0.006,0.008] gets minimum value in n span, and substitution formula (7), obtains k _tif, k _tin span, refresh n, k _tif, k _tnot in span, minimum n value is fixed to step-length and takes off a n value, then substitution formula (7), obtain k _t, repeat said process, until get suitable k _tor n value is got maximal value.

Preferably, in the step of described correction self discharge coefficient, refresh k by formula (8) _disvalue:

$k_{\mathrm{dis}}=\frac{f\left(U_0\right)-f\left(U\right)}{t-t_0}---\left(8\right)$

Wherein, U is current voltage value, and t is current time, U ₀for just entering common magnitude of voltage when standing, t ₀for just entering the common time when standing.

(3) beneficial effect

Method of the present invention is in accumulator on-line operation process, utilize historical data to carry out the correction of SOC appraising model parameter, the method has been considered temperature, coulomb efficiency, the impact of self discharge on battery SOC, only need the basic operating conditions of monitoring accumulator, as long as satisfy condition and just revise related coefficient in battery operation process, correction coefficient value repeatedly, along with the accumulation of time, the estimation result of SOC can approach true value more, and therefore accuracy is high, can realize on-line prediction accumulator SOC.

Accompanying drawing explanation

Fig. 1 is the method flow diagram of the embodiment of the present invention;

Fig. 2 is for calculating SOC process flow diagram;

Fig. 3 is that state conversion judges 1 process flow diagram;

Fig. 4 is that state conversion judges 2 process flow diagrams;

Fig. 5 is that state conversion judges 3 process flow diagrams;

Fig. 6 is that state conversion judges 4 process flow diagrams;

Fig. 7 is correction coefficient process flow diagram.

Embodiment

Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples are used for illustrating the present invention, but are not used for limiting the scope of the invention.

The present invention utilizes historical data to carry out the correction of SOC appraising model parameter, in accumulator on-line operation process, the data such as the electric current (I) of all cells of timing acquiring, voltage (U), temperature (T) storage, and by accumulator operational process be divided into be full of standing, discharge standing, common leaving standstill and four kinds of duties of common operation, more than being full of and leaving standstill and refer to that accumulator reaches floating charge condition and keep a period of time; Discharge leave standstill refer to accumulator reach electric discharge lower limit and keep a period of time more than; Common standing finger charging current is less than certain value, and more than not meeting floating charge condition and keeping a period of time, or discharge current is less than certain value, more than not meeting electric discharge lower limit and keeping a period of time.In the present embodiment, be full of to leave standstill and refer to that battery reaches and is full of (now SOC=100%) and remains full of a period of time, discharge to leave standstill and refer to that battery reaches and discharge (now SOC=0%) and keep discharging a period of time, common when standing, 0%<SOC<100%.The system beginning that powers on, putting original state is common operation, initialization SOC, substitution SOC appraising model parameter initial value, after this proceeds to circular flow.In circular flow process, by analyzing operating condition and data variation, realize the conversion of battery management system duty.Wherein,

Under common running status, refresh SOC value according to SOC appraising model, be full of standing condition if meet, put SOC=SOC ₀=100%, SOC ₀for the initial capacity value of accumulator, the current capability value that SOC is accumulator, juxtaposition duty is standing for being full of; Discharge standing condition if meet, put SOC=SOC ₀=0%, juxtaposition duty is standing for discharging; If meet common standing condition, putting duty is common leaving standstill.

Be full of under static condition, refreshing SOC value; Discharging under static condition, refreshing SOC value; Under common static condition, register system, in the common standing time, refreshes SOC value, while meeting the condition of proofreading and correct self discharge coefficient, proofreaies and correct self discharge coefficient.

The process that refreshes SOC comprises, judges the common standing time of accumulator, if be greater than preset time, measures the now magnitude of voltage of accumulator, as open-circuit voltage OCV(Open Circuit Voltage), according to the given SOC of system ₀obtain SOC with the corresponding relation function f of OCV ₀, refresh initial capacity SOC ₀, then calculate SOC according to SOC appraising model;

Meet to be full of in system and leave standstill conditioned disjunction and discharge and leave standstill when condition, meet certain condition and just revise coulomb efficiency factor and the temperature coefficient in ampere-hour integration.

Referring to Fig. 1, the method for the embodiment of the present invention comprises the steps:

1) start

2) initialization SOC, is coulomb efficiency related coefficient, temperature coefficient, self discharge coefficient initialize, and the initial launch state of putting accumulator is common operation;

3) gather battery tension U, electric current I, temperature T, enter step 4;

4) judge the duty of accumulator, if be full of standingly, enter step 5, if discharge standingly, enter step 6, leave standstill if common, enter step 7, if common operation enters step 8;

5) refresh SOC, enter step 9;

6) refresh SOC, enter step 10;

7) enter common time of repose timing and start, refresh SOC, judge U and U ₀whether difference is greater than set-point, and (U is magnitude of voltage this moment, U ₀for just entering common standing moment magnitude of voltage), if meet, proofread and correct self discharge coefficient.Enter step 11;

8) refresh SOC, enter step 12;

9) state conversion judges 1, returns to step 3;

10) state conversion judges 2, returns to step 3;

11) state conversion judges 3, returns to step 3;

12) state conversion judges 4, returns to step 3;

Further, in step 5,6,7,8, refresh SOC and comprise following process, as shown in Figure 2: judge whether common time of repose is greater than set-point t5, if meet, using cell voltage now as open-circuit voltage values, according to formula (1)

SOC ₀＝f(OCV) （1）

Refresh initial capacity SOC ₀, then press SOC appraising model and calculate SOC, if do not meet, directly press SOC appraising model and calculate SOC; F(OCV) represent the function take OCV as parameter.

Further, described formula (1) is obtained by experiment, under standard temperature, discharges with normalized current, record some open-circuit voltage values, calculate some SOC values of correspondence by ampere-hour integral method, then application of mathematical method is obtained the relation function f of SOC and OCV, for example, can adopt least square method.The funtcional relationship obtaining is deposited in the database of system, in estimation process, obtain SOC by system according to the open-circuit voltage values OCV detecting ₀;

Further, described SOC appraising model is as shown in Equation (2):

$\mathrm{SOC}={\mathrm{SOC}}_0-\left[\underset{t1}{\overset{t}{\&Integral;}}{K}_1{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="HDA00001619791300011.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\mathrm{Idt}\right]/C_B-\underset{t1}{\overset{t}{\&Integral;}}{k}_{\mathrm{dis}}\mathrm{dt}---\left(2\right)$

Wherein K ₁for coulomb efficiency factor, K ₂for temperature coefficient; K ₁representative is under standard temperature, with normalized current I _bthe electric weight Q emitting _iBfrom the electric weight Q emitting with different discharge current I _iratio, K ₂representative is at standard temperature T _bthe capacity Q of lower accumulator _tBcapacity Q with accumulator under temperature T _tratio, k _disfor self discharge coefficient, C _bfor the rated capacity of accumulator, t1, t represent not in the same time, I _bdetermine according to the kind of battery, manufacturer.Further, according to Peukert equation well-known to those skilled in the art, as the formula (3):

I ⁿ·t＝K （3）

Be out of shape to obtain I ^n-1it=K, i.e. I ^n-1q=K, Q is accumulator capacity, has

n is for waiting to revise a coulomb efficiency related coefficient;

experimental formula (4) according to the known temperature correction being most widely used:

Q _T＝Q _TB·[1+k _T·(T-T _B)] （4）

Have

wherein T _bfor standard temperature, for example, get 20 ℃, k _tfor positive temperature coefficient (PTC) to be repaired; Arrange to obtain formula (5):

$\mathrm{SOC}={\mathrm{SOC}}_0-[\underset{t1}{\overset{t}{\&Integral;}}{\left(\frac{I}{I_B}\right)}^{n-1}\&CenterDot;\frac{1}{1+k_T\&CenterDot;(T-20)}\&CenterDot;I\&CenterDot;\mathrm{dt}]/C_B-\underset{t1}{\overset{t}{\&Integral;}}{k}_{\mathrm{dis}}\mathrm{dt}---\left(5\right)$

If Δ t of per interval of system refreshes U, an I, T, formula (5) can be expressed as formula (6):

$\mathrm{SOC}={\mathrm{SOC}}_0-\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{\left(\frac{I_i}{I_B}\right)}^{n-1}\&CenterDot;\frac{1}{1+k_T(I_i-20)}\&CenterDot;I_i\&CenterDot;\mathrm{\&Delta;t}{/C}_B-\mathrm{\&Sigma;}{k}_{\mathrm{dis}}\&CenterDot;\mathrm{\&Delta;t}---\left(6\right)$

Wherein i _i, T _ifor the electric current, the temperature that newly collect at every turn.

Further, the conversion of state described in step 9 judges 1, and shown in Figure 3, determination methods is as follows: judge whether battery current is greater than set-point I ₂and the retention time is greater than set-point t ₃if, meet, put common running status, judge whether to meet electric current simultaneously and be less than set-point I ₁, voltage is less than set-point U ₁and the retention time is greater than set-point t ₄if, meet, put common static condition and record now magnitude of voltage U ₀now moment t ₀;

Further, the conversion of state described in step 10 judges 2, and shown in Figure 4, determination methods is as follows: judge whether battery current is greater than set-point I ₂and the retention time is greater than set-point t ₃if, meet, put common running status;

Further, the conversion of state described in step 11 judges 3, and shown in Figure 5, determination methods is as follows: judge that battery current is less than set-point I ₁and voltage reaches sparking voltage value lower limit and the retention time is greater than set-point t ₄if, meet, put static condition, timing finishes, and judges whether battery current is greater than set-point I simultaneously ₂and the retention time is greater than set-point t ₃if, meet, put common running status, timing finishes;

Further, the conversion of state described in step 12 judges 4, and shown in Figure 6, determination methods is as follows:

121) judge whether battery current I is less than I ₁and the retention time is greater than t ₂if, meet, enter step 122;

122) judge whether battery tension reaches float charge voltage value, if meet, enter step 123, otherwise enter step 124;

123) make SOC=100%, SOC ₀=100%, enter step 125;

124) judge whether battery tension reaches electric discharge lower limit, if meet, enter step 128, if do not meet, enter step 129;

125) judge whether that meeting for the first time I is less than I ₁and the retention time is greater than t ₂if, meet, enter step 126, if do not meet, enter step 127;

126) put and be full of static condition;

127) correction coefficient n, k _t, enter step 126;

128) make SOC=0%, SOC ₀=0%, enter step 1210;

129) put common static condition, record now magnitude of voltage U ₀now moment t ₀;

1210) judge whether that meeting for the first time I is less than I ₁and the retention time is greater than t ₂if, meet, enter step 1211, if do not meet, enter step 1212;

1211) put static condition;

1212) correction coefficient n, k _t, enter step 1211;

Further, correction coefficient n, k described in step 127 and 1212 _t, shown in Figure 7, comprise following process: system enters first and is full of when leaving standstill or discharging static condition, is designated as t ₀₀in the moment, put SOC=SOC ₀=100% or put SOC=SOC ₀=0%, leave standstill or while discharging static condition, be designated as t when system enters to be full of again ₁₁in the moment, put SOC=SOC ₀=100% or put SOC=SOC ₀=0%, can calculate the A value in formula (7):

$\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{\left(\frac{I_i}{I_B}\right)}^{n-1}\&CenterDot;\frac{1}{1+k_T(T_i-20)}\&CenterDot;I_i\&CenterDot;\mathrm{\&Delta;t}=A---\left(7\right)$

A is the determined value calculating, and wherein gets

known n ∈ [1.15,1.42], k _t∈ [0.006,0.008] gets minimum value in n span, and substitution formula (7), obtains kT, if kT, in span, refreshes n, k _tif, k _tnot in span, minimum n value is fixed to step-length and takes off a n value, fixed step size can be set voluntarily, then substitution formula (7), obtains k _t, repeat said process, until get the k that meets span _tor n value is got maximal value.

Further, in the step of described correction self discharge coefficient, refresh k by formula (8) _disvalue:

$k_{\mathrm{dis}}=\frac{f\left(U_0\right)-f\left(U\right)}{t-t_0}---\left(8\right)$

Wherein, f() function of open-circuit voltage and SOC corresponding relation in representation formula (1), U is current voltage value, t is current time, U ₀for just entering common magnitude of voltage when standing, t ₀for just entering the common time when standing.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, do not departing under the prerequisite of the technology of the present invention principle; can also make some improvement and modification, these improve and modification also should be considered as protection scope of the present invention.

Claims (8)

1. A kind of online feedback battery SOC prediction method, is characterized in that, comprises the following steps: S1. Divide the working state of the storage battery into four types: fully charged, static, normal static, and normal operation. The initial working state of the juxtaposed battery is normal operation. Keep it for more than a period of time; rest after discharge means that the battery reaches the lower limit of discharge and keep it for more than a period of time; ordinary rest means that the charging current is less than a certain value, does not meet the floating charge condition and keeps it for a period of time, or, the discharge current is less than a certain value and does not Satisfy the discharge lower limit and maintain it for more than a period of time; the state other than the above three states is normal operation; S2, collect battery voltage U, current I, temperature T, and then enter step S3; S3. Judging the working state of the battery, if it is fully charged, then enter step S4, if it is fully discharged, then enter step S5, if it is normal rest, then enter step S6, if it is normal operation, then enter step S3. S7; S4. Refresh the state of charge SOC, and then enter step S8; S5, refreshing the SOC, and then entering step S9; S6. Start timing the ordinary resting time, refresh the SOC, and judge whether the difference between U and U ₀ is greater than a given value. If it is satisfied, correct the self-discharge coefficient, and then enter step S10, wherein U is the voltage value at the current moment, and U ₀ is the voltage value at the moment of normal rest; S7. Refresh the SOC, and then enter step S11; S8. Perform a first state transition judgment, and then return to step S2; S9. Perform a second state transition judgment, and then return to step S2; S10. Perform a third state transition judgment, and then return to step S2; S11. Perform a fourth state transition judgment, and then return to step S2; Wherein, the judging method of the first state transition judging in step S8 is as follows: judging whether the battery current is greater than a given value I ₂ and the holding time is longer than a given value t ₃ , if it is satisfied, set the normal running state, and judge whether it is satisfied The current is less than the given value I ₁ and the voltage is less than the given value U ₁ and the holding time is greater than the given value t ₄ , if they are satisfied, put it in a normal resting state and record the voltage value U ₀ and the moment t ₀ at this time. 2. The method according to claim 1, characterized in that, the step of refreshing the SOC in the steps S4, S5, S6, S7 comprises the steps of: judging whether the common resting time is greater than a given value t5, if satisfied, then with the current The voltage value of the battery is used as the open circuit voltage value, and the battery initial capacity value SOC ₀ is refreshed according to the following formula (1), and then the SOC is calculated. If it is not satisfied, the SOC is directly calculated. SOC ₀ =f(OCV) (1). 3. The method according to claim 2, characterized in that, in steps S4, S5, S6, and S7, the SOC is calculated according to the SOC estimation model, and the SOC estimation model is shown in formula (2): $\mathrm{<span\; class="notranslate">\; SOC</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; SOC</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; Idt</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; dis</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ Among them, K ₁ is the coulombic efficiency coefficient, K ₂ is the temperature coefficient; K ₁ represents the ratio of the electric quantity Q _IB discharged by the standard current I _B to the electric quantity Q _I discharged by the different discharge current I at the standard temperature, K ₂ represents the ratio of the battery capacity Q _TB at the standard temperature T _B to the battery capacity Q _T at the temperature T, k _dis is the self-discharge coefficient, C _B is the rated capacity of the battery, and t1 and t represent different times. 4. The method according to claim 1, wherein the judgment method of the second state transition judgment in step S9 is as follows: judge whether the battery current is greater than a given value I ₂ and the holding time is greater than a given value t ₃ , If it is satisfied, set the normal running state. 5. The method according to claim 1, wherein the judging method of the third state transition judgment described in step S10 is as follows: judging that the battery current is less than a given value I ₁ and the voltage reaches the lower limit of the discharge voltage value and the holding time is greater than If the given value t ₄ is satisfied, it will be placed in the static state and the timing will end. At the same time, it will be judged whether the battery current is greater than the given value I ₂ and the holding time is longer than the given value t ₃ . If it is satisfied, it will be set to the normal running state. Time out. 6. The method according to claim 2, characterized in that, the judging method of the fourth state transition judgment described in step S11 is as follows: 121. Determine whether the battery current I is less than I ₁ and the holding time is greater than t ₂ , and if so, proceed to step 122; 122. Determine whether the battery voltage reaches the floating charge voltage value, if so, go to step 123, otherwise go to step 124; 123. Let SOC=100%, SOC ₀ =100%, go to step 125; 124. Judging whether the battery voltage reaches the discharge lower limit value, if it is satisfied, then enter step 128, if not, then enter step 129; 125. Judging whether it is satisfied for the first time that I is less than I ₁ and the holding time is greater than t ₂ , if it is satisfied, then enter step 126, if not, then enter step 127; 126. Put it in a static state; 127. Calibrate the coulombic efficiency correlation coefficient n to be corrected and the temperature coefficient k _T to be corrected, and proceed to step 126; 128. Let SOC=0%, SOC ₀ =0%, go to step 1210; 129. Put it in an ordinary static state, and record the voltage value U ₀ and the moment t ₀ at this time; 1210. Judging whether it is the first time that I is less than I ₁ and the holding time is greater than t ₂ , if it is satisfied, go to step 1211, if not, go to step 1212; 1211. After placing it in a static state; 1212. Calibration coefficient n, k _T , go to step 1211. 7. The method according to claim 6, characterized in that the step of correcting the coefficients n and _kT in steps 127 and 1212 is specifically: when the battery first enters the state of being fully charged or left standing, it is recorded as time t ₀₀ , correspondingly set SOC=SOC ₀ =100% or set SOC=SOC ₀ =0%, when it enters the state of being fully charged or fully discharged again, it is recorded as t ₁₁ time, and correspondingly set SOC=SOC ₀ =100 % or set SOC=SOC ₀ =0%, then calculate the A value in the formula (7): $\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$ A is the calculated definite value, where

Given that n∈[1.15, 1.42], k _T ∈ [0.006, 0.008], take the minimum value within the value range of n, substitute it into formula (7), and find kT, if k _T is within the value range, refresh n, k _T , if k _T is not within the value range, take the minimum n value plus a fixed step size to take the next n value, and then substitute it into formula (7) to find k _{T , and get k T that} meets the value range Or, the value of n is taken to the maximum value. 8. The method according to claim 3, characterized in that, in the step of correcting the self-discharge coefficient, refresh the k _dis value according to the formula (8): ${\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; diss</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$ Among them, U is the current voltage value, t is the current time, U ₀ is the voltage value when entering normal rest, and t ₀ is the starting time when entering normal rest.

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