CN102662148A - 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 on-line feedback battery state of charge (SOC) predicting method. According to the method, SOC valuation model parameters are corrected according to historical data in the on-line operating process of a storage battery. The influence of temperature, coulomb efficiency and self discharge on battery SOC is considered, basic operating parameters of the storage battery are only required to be monitored, related coefficients are corrected as long as conditions are met in the operating process of the battery, coefficient values are repeatedly corrected, and an SOC estimation result is close to a true value along time, so the accuracy is high and the storage battery SOC can be predicted on line.

Description

On-line Feedback Battery SOC Prediction Method

technical field

The invention relates to the technical field of battery state of charge (State of Charge, SOC) prediction, in particular to an online feedback battery SOC prediction method.

Background technique

The state of charge (State of Charge, SOC) of the battery is used to describe the remaining capacity of the battery. At present, it is relatively unified to define SOC from the perspective of electricity, which is defined as the difference between the remaining capacity of the battery under a certain discharge rate and the rated capacity under the same conditions. Ratio, it is an important parameter in the process of battery use. Accurate SOC can effectively know the use status of the battery, manage the charging and discharging of the battery, balance it and prevent overcharging and overdischarging, and improve the service life of the battery pack; it can also accurately reflect the battery SOC for electric vehicles. Driving range, reminding the driver when to charge or replace the battery. Therefore, the estimation of SOC is a research hotspot in battery management. At present, there are mainly the following methods for predicting SOC:

(1) Infer the size of the SOC according to the change of the internal parameters of the battery. For example, the medium concentration of the lead-acid battery has the most direct relationship with the SOC, but the medium concentration of the battery cannot reach equilibrium in the process of charging and discharging. The tightness makes it difficult to apply this method to the online estimation of the SOC of the battery;

(2) The open-circuit voltage method is applied to the internally balanced battery, and its open-circuit voltage and SOC have a good mapping relationship, but this method cannot be used for online estimation;

(3) The ampere-hour integration method, which is currently the most widely used method, is simple and easy to implement. Its basic idea is to equate the discharge power under different currents to the discharge power under a certain current, and then judge according to the remaining power SOC, but the discharge coefficient varies with many factors, and it is difficult to obtain a stable and accurate value. In addition, how to consider the battery self-discharge and charge-discharge efficiency in the ampere-hour integration method, and how to correct the problem that the SOC estimate may seriously deviate from the actual value due to the accumulation of errors are the difficulties in improving the accuracy of the ampere-hour integration method. ;

(4) Internal resistance method. The corresponding relationship between battery internal resistance and SOC is established through experiments. Therefore, it is necessary to establish a model to estimate the internal resistance of the battery, and then calculate the SOC based on the calculated internal resistance. This method requires a large amount of calculation and needs to be established. Battery model, the accuracy of the model will inevitably affect the accuracy of the SOC estimation results;

(5) Kalman filtering method, described recursively by a series of mathematical formulas, uses an efficient calculation method to estimate the state of the process and minimize the estimated mean square error. The basic idea is: use the state space model of signal and noise, use the estimated value at the previous moment and the observed value at the current moment to update the estimate of the state variable, and find the estimated value at the present moment. This method requires the establishment of a battery model, and the establishment and solution of the equations are complex and difficult to apply in practice.

The most widely used at present is the SOC estimation based on the ampere-hour integration method. The Chinese patent application with the publication number CN101359036A "Measurement method for the state of charge of the battery" uses the basic ampere-hour method plus a correction function φ(t) to estimate the SOC, as follows:

$\mathrm{<span\; class="notranslate">\; SOC</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d\&tau;</span>}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>$

计算多个时刻的SOC理论值SOC_理，x表示多个时刻中的一个时刻，测得在该多个时刻的SOC实际值SOC_实，然后采用最小二乘法计算得到用于表达SOC_理和SOC_实的差值与所用多个时刻之间的关系修正函数φ(t)。Among them, the determination of the correction coefficient φ(t) adopts the following method: use the formula

Calculate the SOC theoretical value SOC _theory at multiple moments, x represents a moment in the multiple moments, measure the SOC actual value SOC _real at the multiple moments, and then use the least square method to calculate and obtain the SOC _theory and SOC _{real value} The relationship correction function φ(t) between the difference of and the number of times used.

This method relies on the power measuring device to determine the initial capacity C ₀ , the remaining power of the storage battery or the amount of power change, that is, the acquisition and accuracy _of the actual SOC value SOC at multiple moments depends on the external power measuring device;

The Chinese patent application with the publication number CN102162836 "A method for estimating the SOC of an automobile battery" uses the open circuit voltage and historical results to determine the initial capacity of the battery, uses the ampere-hour integral method to estimate the SOC, and considers various factors affecting the SOC to correct the SOC. Compensation correction considerations include:

1. Charge and discharge efficiency, according to Peukert's empirical formula, use the look-up table method to correct the SOC under different currents;

2. Temperature, collect a large amount of experimental data to obtain the battery temperature coefficient in advance;

3. For the consistency of the battery, set multiple points of battery difference, and correct the SOC according to different points of difference;

4. The self-discharge of the battery is pre-estimated by a large number of experimental methods, and corrected by the data look-up table method;

5. Aging, SOC _age = (SOC-A _F )/(1-A _F ), SOC _age is the SOC value after aging compensation, and A _F is the aging factor.

When the battery is fully charged, set the SOC value directly to 100%. When the SOC is obtained by the open circuit voltage method, if the battery ambient temperature exceeds the battery operating limit temperature, the SOC is 0 at this time, and the charging and discharging circuit is cut off to protect the battery. However, the coefficients are obtained by looking up the table and cannot change with the service life and aging degree of the battery. Over time, the obtained coefficients cannot truly reflect the current status of the battery, and the accuracy will be affected; and the data in the table needs to be obtained. In addition, with the different types and combinations of battery packs, the data must be obtained through repeated experiments, which is difficult to achieve.

The patent application "Method for Measuring SOC of a Battery in a Battery Management System and the Apparatus Thereof" is also used to obtain SOC by the method of open circuit voltage-ampere-hour integration, and the open circuit voltage is obtained by building a circuit model. The disadvantage of this method is that The accuracy of battery capacity estimation depends on the accuracy of the battery model.

In summary, the existing ampere-hour integral correction methods either rely on external devices, or require a large amount of experimental data as a basis, the equipment is complex, and the coefficients cannot be adaptively corrected.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the invention is: how to improve the prediction accuracy of battery SOC.

(2) Technical solutions

In order to solve the above-mentioned technical problems, the present invention provides an online feedback battery SOC prediction method, comprising 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 has reached 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, 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 resting, 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.

Preferably, the steps of refreshing the SOC in steps S4, S5, S6, and S7 include the following steps: judging whether the ordinary resting time is greater than a given value t5, if satisfied, then using the current voltage value as the open circuit voltage value, according to the following formula ( 1) Refresh the battery initial capacity value SOC ₀ , and then calculate the SOC, if not satisfied, directly calculate the SOC

SOC ₀ =f(OCV) (1).

Preferably, 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):

$\mathrm{<span\; class="notranslate">\; SOC</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; SOC</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="K"\; filenames="HDA00001619791300011.png"\; state="\{\{state\}\}">K</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; Idt</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; dis</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

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.

Preferably, the judgment method of the first state transition judgment in step S8 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 satisfied, set the normal running state, and judge whether Satisfied that the current is less than the given value I ₁ , the voltage is less than the given value U ₁ and the holding time is greater than the given value t ₄ , if satisfied, put it in a normal resting state and record the current voltage value U ₀ and the current moment t ₀ .

Preferably, the judging method of the second state transition judgment in step S9 is as follows: judging whether the battery current is greater than a given value I ₂ and the holding time is greater than a given value t ₃ , and if so, set to a normal running state.

Preferably, the judgment method of the second state transition judgment 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 a given value t ₄ , if satisfied, then place After the static state, the timing ends, and at the same time, it is judged whether the battery current is greater than the given value I ₂ and the holding time is greater than the given value t ₃ , if so, it is set to the normal running state, and the timing ends.

Preferably, the judgment method of the second state transition judgment 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.

Preferably, 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 fully discharged, it is recorded as time t ₀₀ , and correspondingly set SOC=SOC ₀ =100% or Set SOC=SOC ₀ ＝0%, when it enters the state of being fully charged or finished resting again, it is recorded as t ₁₁ time, correspondingly set SOC=SOC ₀ ＝100% or set SOC＝SOC ₀ ＝0%, then Calculate the A value in formula (7):

$\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

已知n∈[1.15，1.42]，k_T∈[0.006，0.008]，在n取值范围内取最小值，代入公式(7)，求出k_T，若k_T在取值范围内，则刷新n、k_T，若k_T不在取值范围内，则将最小n值加固定步长取下一n值，再代入公式(7)，求出k_T，重复上述过程，直到取到合适的k_T或，n值取到最大值。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 k _T , if k _T is within the value range, then Refresh n and k _T , if k _T is not within the value range, take the minimum n value plus a fixed step size to get the next n value, and then substitute it into formula (7) to find k _T , repeat the above process until a suitable The k _T or, n value takes the maximum value.

Preferably, in the step of correcting the self-discharge coefficient, refresh the k _dis value according to formula (8):

${\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; dis</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Among them, U is the current voltage value, t is the current time, U ₀ is the voltage value when it just enters the ordinary rest, and t ₀ is the time when it just enters the ordinary rest.

(3) Beneficial effects

The method of the present invention uses historical data to correct the parameters of the SOC estimation model during the online operation of the battery. The method takes into account the influence of temperature, Coulombic efficiency and self-discharge on the SOC of the battery. During operation, as long as the conditions are met, the correlation coefficient is corrected, and the coefficient value is corrected repeatedly. With the accumulation of time, the estimated result of SOC will be closer to the true value, so the accuracy is high, and online prediction of battery SOC can be realized.

Description of drawings

Fig. 1 is the method flowchart of the embodiment of the present invention;

Fig. 2 is the flow chart of calculating SOC;

Fig. 3 is a flowchart of state transition judgment 1;

Fig. 4 is a flow chart of state transition judgment 2;

Fig. 5 is a flow chart of state transition judgment 3;

Fig. 6 is a flow chart of state transition judgment 4;

Fig. 7 is a flowchart of the correction coefficient.

Detailed ways

The specific implementation manners of the present invention will be described in further detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

The invention uses historical data to correct the parameters of the SOC estimation model. During the online operation of the storage battery, the current (I), voltage (U), temperature (T) and other data of all single batteries are regularly collected and stored, and the battery operation process It is divided into four working states: fully charged, fully discharged, normal static and normal operation. Fully charged and static means that the battery has reached the floating charge condition and maintained for a period of time; fully discharged and static means that the battery has reached the lower limit of discharge and maintained for a period of time. Above; Ordinary standing means that the charging current is less than a certain value, does not meet the floating charge condition and remains for a period of time, or, the discharge current is less than a certain value, does not meet the discharge lower limit and remains for a period of time. In this embodiment, fully charged and standing means that the battery is fully charged (at this time SOC = 100%) and remains fully charged for a period of time, and that the battery is fully discharged (at this time SOC = 0%) and remains fully charged for a period of time, When standing normally, 0%<SOC<100%. When the system is powered on, the initial state is set to normal operation, the SOC is initialized, the initial value of the model parameters is substituted into the SOC, and then it is transferred to cycle operation. During the cycle operation, the working state transition of the battery management system is realized by analyzing the operating conditions and data changes. in,

In the normal running state, the SOC value is refreshed according to the SOC estimation model. If the condition of being fully charged is satisfied, then set SOC=SOC ₀ =100%, SOC ₀ is the initial capacity value of the battery, SOC is the current capacity value of the battery, and set The working state is full and resting; if the resting condition is met, set SOC=SOC ₀ =0%, and set the working state as resting after putting; if the normal resting condition is met, set the working state as ordinary resting .

Refresh the SOC value in the full static state; refresh the SOC value in the static state after discharging; in the normal static state, record the time the system is in the normal static state, refresh the SOC value, and meet the conditions for correcting the self-discharge coefficient , correct the self-discharge coefficient.

The process of refreshing the SOC includes judging the normal standing time of the battery. If it is longer than the given time, measure the voltage value of the battery at this time as the open circuit voltage OCV (Open Circuit Voltage). According to the correspondence between SOC ₀ and OCV given by the system The relationship function f gets SOC ₀ , refreshes the initial capacity SOC ₀ , and then calculates SOC according to the SOC estimation model;

When the system satisfies the condition of being fully charged or fully discharged, the coulombic efficiency coefficient and temperature coefficient in the ampere-hour integration are corrected if certain conditions are met.

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

1) start

2) Initialize the SOC, assign initial values for the coulombic efficiency correlation coefficient, temperature coefficient, and self-discharge coefficient, and set the initial operating state of the battery to normal operation;

3) Collect battery voltage U, current I, temperature T, and enter step 4;

4) Judging the working status of the battery, if it is fully charged, go to step 5, if it is completely discharged, go to step 6, if it is normal, go to step 7, if it is normal operation, go to step 8;

5) Refresh the SOC and go to step 9;

6) Refresh the SOC and go to step 10;

7) Enter the normal resting time and start timing, refresh the SOC, and judge whether the difference between U and U ₀ is greater than a given value (U is the voltage value at the moment, and U ₀ is the voltage value at the moment when it just entered the normal resting time), and if it is satisfied, then correct self-discharge coefficient. Go to step 11;

8) Refresh the SOC and go to step 12;

9) State transition judgment 1, return to step 3;

10) State transition judgment 2, return to step 3;

11) State transition judgment 3, return to step 3;

12) State transition judgment 4, return to step 3;

Further, refreshing the SOC in steps 5, 6, 7, and 8 includes the following process, as shown in Figure 2: judging whether the ordinary resting time is greater than a given value t5, if it is satisfied, then use the battery voltage at this time as the open circuit voltage value, according to formula (1)

SOC ₀ = f(OCV) (1)

Refresh the initial capacity SOC ₀ , and then calculate the SOC according to the SOC estimation model, if not, directly calculate the SOC according to the SOC estimation model; f(OCV) represents a function with OCV as a parameter.

Further, the formula (1) is obtained by experiments, discharge with a standard current at a standard temperature, record some open circuit voltage values, use the ampere-hour integral method to calculate corresponding SOC values, and then apply mathematical methods to obtain the relationship between SOC and OCV The relation function f, for example, may employ the method of least squares. Store the obtained functional relationship in the database of the system. During the estimation process, the system obtains SOC ₀ according to the detected open circuit voltage value OCV;

Further, the SOC estimation model is shown in formula (2):

$\mathrm{<span\; class="notranslate">\; SOC</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; SOC</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="K"\; filenames="HDA00001619791300011.png"\; state="\{\{state\}\}">K</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; Idt</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Integral;</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; dis</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

根据本领域技术人员所熟知的Peukert方程，如式(3)所示：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 capacity Q _TB of the battery at standard temperature T _B to the capacity Q _T of the battery at temperature T, k _dis is the self-discharge coefficient, C _B is the rated capacity of the battery, t1 and t represent different moments, I _B according to It depends on the type of battery and the manufacturer. further,

According to the Peukert equation well known to those skilled in the art, as shown in formula (3):

I ⁿ t=K (3)

n为待修正库伦效率相关系数；

根据已知的应用最为广泛的温度修正的经验公式(4)：Transformed into I ^n-1 · I · t = K, that is, I ^n-1 · Q = K, Q is the capacity of the storage battery, then there is

n is the correlation coefficient of Coulombic efficiency to be corrected;

According to the known empirical formula (4) of the most widely used temperature correction:

Q _T ＝ Q _TB ·[1+k _T ·(TT _B )] (4)

其中TB为标准温度，例如取20℃，k_T为待修正温度系数；整理得公式(5)：then there is

Where TB is the standard temperature, for example, 20°C, and k _T is the temperature coefficient to be corrected; the formula (5) is obtained:

$\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>}}{<span\; class="notranslate">\; (</span>\frac{\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">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</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>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; dt</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">\; 5</span>}<span\; class="notranslate">\; )</span>$

If the system refreshes U, I, and T every time Δt, formula (5) can be expressed as formula (6):

$\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>\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">\; \&Center\; Dot;</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">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Sigma;k</span>}}_{\mathrm{<span\; class="notranslate">\; dis</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

I_i、T_i为每次新采集到的电流、温度。in

I _i and T _i are current and temperature newly collected each time.

Further, the state transition judgment 1 mentioned in step 9, as shown in Fig. 3, the judging method 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 satisfied, set the normal operation At the same time, judge whether the current is less than the given value I ₁ , the voltage is less than the given value U ₁ and the holding time is _greater than the given value t ₄ . time t ₀ ;

Further, the state transition judgment 2 mentioned in step 10, as shown in Fig. 4, the judgment method is as follows: judge whether the battery current is greater than the given value I ₂ and the holding time is greater than the given value t ₃ , if satisfied, set the normal operation state;

Further, the state transition judgment 3 described in step 11, as shown in FIG. 5 , is judged 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 a given value t ₄ , if If it 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 greater than the given value t ₃ .

Further, the state transition judgment 4 described in step 12, as shown in FIG. 6, the judgment method is as follows:

121) Judging whether the battery current I is less than I ₁ and the holding time is greater than t ₂ , if satisfied, enter step 122;

122) Judging whether the battery voltage has reached the floating charge voltage value, if satisfied, enter step 123, otherwise enter step 124;

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

124) Judging whether the battery voltage reaches the discharge lower limit value, if satisfied, then enter step 128, if not satisfied, then enter step 129;

125) Judging whether it is satisfied for the first time that I is less than _I1 and the holding time is greater than _t2 , if satisfied, then enter step 126, if not satisfied, then enter step 127;

126) set full static state;

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

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

129) Put it in an ordinary static state, record the voltage value U ₀ and the moment t ₀ at this time;

1210) 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 1211, if not, then enter step 1212;

1211) After placing the static state;

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

Further, the correction coefficients n and k _T described in steps 127 and 1212, as shown in FIG. 7 , include the following process: when the system first enters the state of being fully charged or resting, record it as time t ₀₀ , and set SOC= SOC ₀ ＝100% or set SOC＝SOC ₀ ＝0%, when the system enters into the state of being fully charged or fully discharged again, it is recorded as _t11 time, set SOC＝SOC ₀ ＝100% or set SOC＝SOC ₀ =0%, then the A value in formula (7) can be calculated:

$\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 20</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

已知n∈[1.15，1.42]，k_T∈[0.006，0.008]，在n取值范围内取最小值，代入公式(7)，求出k_T，若k_T在取值范围内，则刷新n、k_T，若k_T不在取值范围内，则将最小n值加固定步长取下一n值，固定步长可自行设定，再代入公式(7)，求出k_T，重复上述过程，直到取到满足取值范围的kT或，n值取到最大值。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 k _T , if k _T is within the value range, then Refresh n and k _T , if k _T is not within the value range, add the minimum n value plus a fixed step size to get the next n value, the fixed step size can be set by yourself, and then substitute into formula (7) to find k _T , Repeat the above process until kT or n that satisfies the value range is obtained, and the value of n reaches the maximum value.

Further, in the step of correcting the self-discharge coefficient, refresh the k _dis value according to formula (8):

${\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; dis</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Among them, f() represents the function of the corresponding relationship between the open circuit voltage and SOC in formula (1), U is the current voltage value, t is the current time, U ₀ is the voltage value when it just enters normal rest, and t ₀ is the voltage value just entered normal time at rest.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made, these improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (9)

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, 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. Refresh the SOC, and then enter step S9; S6. Start timing the ordinary resting time, refresh the SOC, and judge whether the difference between U and _U0 is greater than a given value. If it is satisfied, then correct the self-discharge coefficient, and then enter step S10, wherein U is the voltage value at the current moment, and _U0 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. 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, wherein, in steps S4, S5, S6, S7, the SOC is calculated according to the SOC estimation model, and the SOC estimation model is as shown in formula (2): 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 first state transition judgment in step S8 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, it will be set to the normal running state, and at the same time judge whether the current is less than the given value I ₁ , the voltage is less than the given value U ₁ and the holding time is greater than the given value t ₄ , if it is satisfied, it will be set to the normal resting state and record this When the voltage value U ₀ and the time t ₀ at this time. 5. 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. 6. The method according to claim 1, wherein the judging method of the second 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 placed in the normal running state. Time out. 7. The method according to claim 2, wherein the judgment method of the second 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. 8. The method according to claim 7, 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, record it as time t ₁₁ , and set SOC=SOC ₀ =100 accordingly % or set SOC=SOC ₀ =0%, then calculate the A value in the formula (7):

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 k _T , if k _T is within the value range, then Refresh n and k _T , if k _T is not within the value range, then add 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 , repeat the above process until it is satisfied The value range of k _T or, n value is taken to the maximum value. 9. method as claimed in claim 3, is characterized in that, in the step of described correction self-discharge coefficient, refreshes _kdis value by formula (8): 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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