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CN-121978560-A - Battery SOC calculation method

CN121978560ACN 121978560 ACN121978560 ACN 121978560ACN-121978560-A

Abstract

The invention provides a battery SOC calculation method, which comprises the steps of calculating the lowest monomer SOC and the highest monomer SOC of a current calculation cycle by adopting an ampere-hour integration method when the battery SOC is in a full-discharge correction section and is not in a full-charge correction section, calculating the lowest monomer SOC of the current calculation cycle by adopting a full-discharge voltage correction method when the battery SOC is in a discharge state and is in the full-discharge correction section, calculating the highest monomer SOC of the current calculation cycle by adopting a full-charge voltage correction method when the battery SOC is in a charge state and is in the full-charge correction section, and calculating the battery SOC of the current calculation cycle by adopting a weight calculation based on the lowest monomer SOC and the highest monomer SOC of the current calculation cycle. This can improve the calculation accuracy of the battery SOC.

Inventors

  • LIU HUCHENG

Assignees

  • 科博达技术股份有限公司
  • 浙江科博达工业有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (11)

  1. 1. A battery SOC calculation method, the battery including a plurality of unit cells, comprising: When the power consumption during the sleep stage is started, the power consumption during the sleep stage is calculated, and the sleep error correction is carried out on the lowest monomer SOC based on the power consumption during the sleep stage to obtain the initial value of the lowest monomer SOC of the current working cycle; When the full charge correction section is not reached and the full charge correction section is also not reached, calculating the lowest monomer SOC of the current calculation cycle by adopting an ampere-hour integration method based on the lowest monomer SOC obtained in the previous calculation cycle, and calculating the highest monomer SOC of the current calculation cycle by adopting the ampere-hour integration method based on the highest monomer SOC obtained in the previous calculation cycle; When the state of discharge is in a full discharge correction section, calculating to obtain the lowest monomer SOC of the current calculation cycle by adopting a full discharge voltage correction method, and calculating the highest monomer SOC of the current calculation cycle by adopting an ampere-hour integration method based on the highest monomer SOC obtained in the previous calculation cycle; when the battery is in a charging state and reaches a full charge correction section, calculating to obtain the highest monomer SOC of the current calculation cycle by adopting a full charge voltage correction method, and calculating the lowest monomer SOC of the current calculation cycle by adopting an ampere-hour integration method based on the lowest monomer SOC obtained in the previous calculation cycle; And carrying out weight calculation based on the lowest monomer SOC and the highest monomer SOC of the current calculation cycle to obtain the battery SOC of the current calculation cycle.
  2. 2. The battery SOC calculation method according to claim 1, characterized in that it further comprises: the battery SOC is output after smoothing filtering, Multiple calculation cycles are performed during the current duty cycle, each calculation cycle calculating the lowest and highest monomer SOCs for the current calculation cycle.
  3. 3. The battery SOC calculation method according to claim 1, wherein the battery SOC of the current calculation cycle is weighted based on the lowest and highest individual SOCs of the current calculation cycle as: SOC ctrl =k*SOC maxraw +(1-k)*SOC minraw ; Wherein SOC minraw is the lowest monomer SOC of the current calculation cycle, SOC maxraw is the highest monomer SOC of the current calculation cycle, SOC ctrl is the battery SOC of the current calculation cycle, k is the proportion of the highest monomer SOC, k is smaller when the discharging current is higher, and k is higher when the charging current is lower.
  4. 4. The battery SOC calculation method according to claim 3, wherein, When the current is 0.1C, k is 100%, and when the current is 0, k is 50%, wherein 1C is a unit of charge/discharge rate of the battery, and is a current intensity required to completely fill or discharge the battery in 1 hour based on the rated capacity of the battery.
  5. 5. The method for calculating the battery SOC according to any one of claims 1 to 4, wherein, The initial value of the lowest monomer SOC mininit for the current duty cycle is: SOC mininit =SOC NVMmin -∆SOC sleep ; the initial value of the highest monomer SOC for the current duty cycle, SOC maxinit , is: SOC maxinit =SOC NVMmax -∆SOC sleep ; The SOC mininit is an initial value of the lowest monomer SOC of the current working cycle, the SOC NVMmin is a stored value of the lowest monomer SOC of the last working cycle, the SOC maxinit is an initial value of the highest monomer SOC of the current working cycle, the SOC NVMmax is a stored value of the highest monomer SOC of the last working cycle, and the SOC sleep is the variation of the SOC during the sleep period.
  6. 6. The battery SOC calculation method according to claim 5, wherein, The power consumption during sleep includes power consumption Q sleep during normal sleep and power consumption Q deepsleep during deep sleep, Q sleep =I AFE /N inspection *T sleep ; Wherein Q sleep is power consumption during normal dormancy, I AFE is current accumulated during inspection during normal dormancy, N inspection is the number of inspection during normal dormancy, and T sleep is normal dormancy time; Q deepsleep =I constant *T deepsleep ; Wherein Q deepsleep is power consumption during deep sleep, I constant is deep sleep current, and T deepsleep is deep sleep time.
  7. 7. The battery SOC calculation method according to claim 6, wherein, ∆SOC sleep =(Q sleep +Q deepsleep )/C bat ; Wherein, the SOC sleep is the variation of the SOC in the sleep period, and C bat is the battery capacity at the current moment, C bat =C BOL *S OH *α temp ; Wherein, C BOL is the initial capacity of the battery, S OH is the health of the battery, and alpha temp is the temperature coefficient.
  8. 8. The method for calculating the battery SOC according to any one of claims 1 to 4, wherein, The highest monomer SOC of the current calculation cycle is calculated by adopting an ampere-hour integration method and is as follows: SOC maxraw =SOC maxlast +(I*dt/C bat ) ; Wherein SOC maxraw is the highest monomer SOC of the current calculation cycle, SOC maxlast is the highest monomer SOC of the previous calculation cycle, I is the battery current, I has a direction, charging is positive, power supply is negative, dt is the function execution period, The lowest monomer SOC of the current calculation cycle is calculated by adopting an ampere-hour integration method and is as follows: SOC minraw =SOC minlast +(I*dt/C bat ) ; Wherein SOC minraw is the lowest monomer SOC of the current calculation cycle, and SOC minlast is the lowest monomer SOC of the last calculation cycle.
  9. 9. The method for calculating the battery SOC according to any one of claims 1 to 4, wherein, If the minimum monomer voltage is lower than the preset minimum voltage and the minimum monomer SOC is higher than the preset minimum voltage corresponding SOC, calculating the minimum monomer SOC of the current calculation cycle by adopting a second full discharge voltage correction method; If the highest monomer voltage is higher than the preset highest voltage and the highest monomer SOC is smaller than the preset highest voltage corresponding SOC, the highest monomer SOC of the current calculation cycle is calculated by adopting a first full charge voltage correction method, and if the highest monomer SOC is higher than the preset highest voltage corresponding SOC and the highest monomer SOC of the current calculation cycle is calculated by adopting a second full charge voltage correction method.
  10. 10. The battery SOC calculation method according to claim 9, wherein, The calculation formula of the second full charge voltage correction method is as follows: SOC maxraw =k 1 *V cellmax +b 1 ; k 1 =(100%-SOC ChagCorrect )/(V fullchag -V cellmaxbase ); b 1 =((V fullchag *SOC ChagCorrect )-V cellmaxbase )/(V fullchag -V cellmaxbase ); The SOC maxraw is the highest monomer SOC of the current calculation cycle, the SOC ChagCorrect is the corresponding SOC of the preset highest voltage, the V cellmaxbase is equal to the preset highest voltage, the V fullchag is the full charge voltage of the battery, and the V cellmax is the highest monomer voltage; the calculation formula of the first full charge voltage correction method is as follows: SOC maxraw =SOC maxlast +N*(I*dt/C bat ), Wherein N is a multiplier factor related to the father SOC, father soc=soc ChagCorrect -SOC maxlast ,SOC maxraw is the highest monomer SOC of the current calculation cycle during charging, SOC maxlast is the highest monomer SOC of the previous calculation cycle, I is battery current, charging is positive, power supply is negative, dt is a function execution period, and C bat is battery capacity at the current moment.
  11. 11. The battery SOC calculation method according to claim 9, wherein, The calculation formula of the first full discharge voltage correction method is as follows: SOC minraw =k 2 *V cellmin +b 2 ; k 2 =SOC DischagCorrect /(V cellminbase -V fullDischag ); b 2 =(V fullDischag *SOC DischagCorrect )/(V fullDischag -V cellminbase ), The SOC mintraw is the lowest monomer SOC of the current calculation period, the SOC DischagCorrect is the corresponding SOC of the preset lowest voltage, the V cellminbase is equal to the preset lowest voltage, the V fullDischag is the full battery discharge voltage, and the V cellmin is the lowest monomer voltage; the calculation formula of the second full discharge voltage correction method is as follows: SOC minraw =SOC minlast +N*(I*dt/C bat ), Wherein N is a multiplier factor related to father SOC, father soc=soc minlast -SOC DischagCorrect when discharging, I is battery current, charge positive, power supply negative, dt is a function execution period, SOC minlast is the lowest monomer SOC of the last calculation period, and C bat is battery capacity at the current moment.

Description

Battery SOC calculation method Technical Field The invention relates to the field of batteries, in particular to a battery SOC (State of Charge) computing method. Background The existing SOC calculation method of the lithium ion battery mainly comprises an open circuit voltage method, an ampere-hour integration method, an internal resistance method, a Kalman filtering method, a neural network method and the like. However, these methods all face some challenges in practical applications. Open circuit voltage method the method estimates SOC by measuring the open circuit voltage of the battery. However, the relationship between the open circuit voltage and the SOC is affected by various factors such as the battery temperature, the degree of aging, and the charge-discharge history, resulting in an inaccurate estimation result. And an ampere-hour integration method, which estimates the SOC by accumulating the charge-discharge current of the battery. However, errors in the initial SOC, accuracy of the current sensor, and accumulated errors in the integration process all result in deviations in the SOC estimation. The internal resistance method is to estimate the internal resistance of the battery by using the relation between the internal resistance and the SOC. However, the internal resistance of the battery is affected by various factors such as temperature, current magnitude, and aging degree of the battery, and thus the estimation accuracy of the internal resistance method is limited. The Kalman filtering method is that the state space model of the battery is established, and the Kalman filtering algorithm is utilized to carry out SOC estimation. However, the accuracy of the model and the parameter setting of the filtering algorithm have great influence on the estimation result, and the calculation complexity is high. The neural network method is that the neural network is utilized to learn the historical data of the battery, and the mapping relation between the SOC and the battery parameter is established. However, training of the neural network requires a large amount of data support, and the generalization ability of the model is greatly affected by the training data. In summary, the existing lithium ion battery SOC calculation methods have defects of different degrees, and the requirements of the lithium ion battery SOC calculation in practical application on precision, instantaneity, stability and economy cannot be balanced. Disclosure of Invention To solve or at least partially solve the above technical problems, embodiments of the present invention provide an improved battery SOC calculating method. According to one aspect of the invention, the embodiment of the invention provides a battery SOC calculation method, which comprises the steps of calculating power consumption during sleep when the battery is initialized after the battery exits from the sleep stage, and carrying out sleep error correction on the lowest monomer SOC based on the power consumption during sleep to obtain an initial value of the lowest monomer SOC of a current working cycle; When the charge state is in a full charge correction stage, the lowest monomer SOC of the current calculation cycle is calculated by adopting an ampere-hour integration method based on the lowest monomer SOC of the previous calculation cycle, and the highest monomer SOC of the current calculation cycle is calculated by adopting the ampere-hour integration method based on the highest monomer SOC of the previous calculation cycle; When the charge state is reached and the full charge correction section is reached, the full charge pressure correction method is adopted to calculate the highest monomer SOC of the current calculation cycle, and the ampere-hour integration method is adopted to calculate the lowest monomer SOC of the current calculation cycle based on the lowest monomer SOC obtained in the previous calculation cycle; and calculating the battery SOC of the current calculation cycle by weight based on the lowest monomer SOC and the highest monomer SOC of the current calculation cycle. Compared with the prior art, the method can improve the estimation accuracy of the battery SOC through sectional calculation. Drawings In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein: fig. 1 is a flowchart of a battery SOC calculating method according to an embodiment of the present invention. Detailed Description In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the