CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202010011610.7 filed on Jan. 6, 2020 in the China Intellectual Property Office, the contents of which are incorporated by reference herein.

FIELD

The disclosure relates to batteries, and more particularly, to a method for updating voltage difference of battery, a method for estimating state of charge of the battery, an electronic device, and a storage unit.

BACKGROUND

Lithium ion batteries have advantages like high energy density, high power, high numbers of charging and discharging cycles, long storage time etc. The lithium ion batteries have wide application in electronic equipment, such as electric vehicles, energy storage facilities, and so on. Lithium ion batteries play an important role in global problems such as energy storage, and in environmental concerns.

Voltage difference of the lithium ion battery vs. state of charge curves (hereinafter VD vs. SOC curves) are of interest in usage of the batteries. However, the VD vs. SOC curves are measured in a laboratory environment. In everyday operation, actual voltage difference of the lithium ion battery vs. state of charge curves may be different from the VD vs. SOC curves in the laboratory because of various factors in the environment of use, thus a determination of the actual state of the battery in everyday usage may not follow the laboratory standard.

SUMMARY

An embodiment of the present application provides a method for updating voltage difference of battery, a method for estimating state of charge, an electronic device, and a storage unit for updating a first relation model table.

An embodiment of the present application provides a method for updating voltage difference of battery. The method for updating voltage difference of battery includes presetting a relationship of voltage difference vs. state of charge (hereinafter VD vs. SOC relationship), and detecting a state of charge-1 of the battery (hereinafter SOC-1); determining a first voltage difference of the battery according to the SOC-1; and updating the VD vs. SOC relationship according to the first voltage difference of the battery.

According to some embodiments of the present application, determining a first voltage difference of the battery according to the SOC-1 includes: determining the first voltage difference of the battery when the battery is discharged at a plurality of different rates according to the SOC-1.

According to some embodiments of the present application, determining a first voltage difference of the battery according to the SOC-1 includes determining the first voltage difference of the battery during the battery discharging period according to the SOC-1.

According to some embodiments of the present application, the method for updating voltage difference of battery further includes detecting a state of charge-2 of the battery (hereinafter SOC-2) and an actual capacity-1 of the battery; determining a first state of charge (hereinafter first SOC) according to the SOC-2 and the actual capacity-1 of the battery; and determining the SOC-1 according to the first SOC.

According to some embodiments of the present application, the method for updating voltage difference of battery further includes determining a second state of charge (hereinafter second SOC) according to the SOC-2; and determining a state of charge-3 of the battery (hereinafter SOC-3) according to the first SOC and the second SOC.

According to some embodiments of the present application, the SOC-2 is an initialized state of charge (hereinafter initialized SOC) and the actual capacity-1 of the battery is a preset capacity when the first SOC is determined for the first time.

According to some embodiments of the present application, the method for updating voltage difference of battery further includes: determining a first open circuit voltage (hereinafter first OCV); and determining the initialized SOC according to the first OCV.

According to some embodiments of the present application, determining the first OCV includes: determining that the first OCV is a current battery voltage.

According to some embodiments of the present application, determining the initialized SOC according to the first OCV includes: querying the VD vs. SOC relationship to determine the initialized SOC according to the first OCV.

According to some embodiments of the present application, determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery includes: determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery via a coulomb counting method.

According to some embodiments of the present application, determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery via a coulomb counting method includes: determining the first SOC according to the SOC-2, a current battery current, a difference between current time and a previous time (a sampling interval) of obtaining the battery current, and the actual capacity-1 of the battery via the coulomb counting method.

According to some embodiments of the present application, the coulomb counting method includes: SOC1=SOC0+Ibat×Δt/Qabs; wherein SOC1is the first SOC, SOC0is a SOC-2, Ibatis a current battery current, Δt is a sampling interval of obtaining the battery current, and Qabsis an actual capacity-1 of the battery.

According to some embodiments of the present application, determining the first voltage difference of the battery during the battery discharging period according to the SOC-1 includes: determining a second open circuit voltage (hereinafter second OCV) according to the SOC-1; and determining the first voltage difference of the battery during the battery discharging period according to the second OCV.

According to some embodiments of the present application, determining a second OCV according to the SOC-1 includes: querying the VD vs. SOC relationship to determine the second OCV according to the SOC-1.

According to some embodiments of the present application, determining the first voltage difference of the battery during the battery discharging period according to the second OCV includes: determining that the first voltage difference of the battery during the battery discharging period is a value of difference between the second OCV and the current battery voltage.

According to some embodiments of the present application, updating the VD vs. SOC relationship according to the first voltage difference of the battery includes: processing the first voltage difference of the battery via a monadic linear regression method to determine a second voltage difference of the battery; and updating the VD vs. SOC relationship according to the second voltage difference of the battery.

According to some embodiments of the present application, before updating the VD vs. SOC relationship according to the second voltage difference of the battery, the method for updating voltage difference of battery includes: determining that an absolute value of a difference between the second voltage difference of the battery and the third voltage difference of the battery is less than an allowable maximum voltage difference.

According to some embodiments of the present application, presetting a VD vs. SOC relationship includes: presetting the VD vs. SOC relationship at each of a plurality of different temperatures; the method for updating voltage difference of battery further includes: detecting a current battery temperature; updating the VD vs. SOC relationship according to the first voltage difference of the battery includes: updating the VD vs. SOC relationship at each of the plurality of different temperatures according to the first voltage difference of the battery and the battery temperature.

An embodiment of the present application provides a method for estimating state of charge, the method for estimating state of charge includes: presetting a VD vs. SOC relationship; detecting a SOC-1; determining a first voltage difference of the battery according to the SOC-1; updating the VD vs. SOC relationship according to the first voltage difference of the battery; determining a variation of the state of charge (hereinafter SOC) of the battery when the battery gets fully discharged via simulation and according to the updated VD vs. SOC relationship; and estimating a residual capacity of the battery according to the variation of the SOC of the battery.

According to some embodiments of the present application, determining a first voltage difference of the battery according to the SOC-1 includes: determining the first voltage difference of the battery when the battery is discharged at a plurality of different rates according to the SOC-1.

According to some embodiments of the present application, determining a first voltage difference of the battery according to the SOC-1 includes: determining the first voltage difference of the battery during the battery discharging period according to the SOC-1.

According to some embodiments of the present application, the method for estimating state of charge further includes: detecting a SOC-2 and an actual capacity-1 of the battery; determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery; and determining the SOC-1 according to the first SOC.

According to some embodiments of the present application, the method for estimating state of charge further includes: determining a second SOC according to the SOC-2; and determining a SOC-3 according to the first SOC and the second SOC.

According to some embodiments of the present application, the SOC-2 is an initialized SOC and the actual capacity-1 of the battery is a preset capacity when the first SOC is determined for the first time.

According to some embodiments of the present application, the method for estimating state of charge further includes: determining a first OCV; and determining the initialized SOC according to the first OCV.

According to some embodiments of the present application, determining a first OCV includes: determining that the first OCV is a current battery voltage.

According to some embodiments of the present application, determining the initialized SOC according to the first OCV includes: querying the VD vs. SOC relationship to determine the initialized SOC according to the first OCV.

According to some embodiments of the present application, determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery includes: determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery via a coulomb counting method.

According to some embodiments of the present application, determining a first SOC according to the SOC-2 and the actual capacity-1 of the battery and via a coulomb counting method includes: determining the first SOC according to the SOC-2, a current battery current, a sampling interval of obtaining the battery current, and the actual capacity-1 of the battery via the coulomb counting method.

According to some embodiments of the present application, the coulomb counting method includes: SOC1=SOC0+Ibat×Δt/Qabs; wherein SOC1is the first SOC, SOC0is a SOC-2, Ibatis a current battery current, Δt is a sampling interval of obtaining the battery current, and Qabsis an actual capacity-1 of the battery.

According to some embodiments of the present application, determining the first voltage difference of the battery during the battery discharging period according to the SOC-1 includes: determining a second OCV according to the SOC-1; and determining the first voltage difference of the battery during the battery discharging period according to the second OCV.

According to some embodiments of the present application, determining a second OCV according to the SOC-1 includes: querying the VD vs. SOC relationship to determine the second OCV according to the SOC-1.

According to some embodiments of the present application, determining the first voltage difference of the battery during the battery discharging period according to the second OCV includes: determining that the first voltage difference of the battery during the battery discharging period is a value of difference between the second OCV and the current battery voltage.

According to some embodiments of the present application, updating the VD vs. SOC relationship according to the first voltage difference of the battery includes: processing the first voltage difference of the battery via a monadic linear regression method to determine a second voltage difference of the battery; and updating the VD vs. SOC relationship according to the second voltage difference of the battery.

According to some embodiments of the present application, before updating the VD vs. SOC relationship according to the second voltage difference of the battery, the method for estimating state of charge includes: determining that an absolute value of a difference between the second voltage difference of the battery and the third voltage difference of the battery is less than an allowable maximum voltage difference.

According to some embodiments of the present application, presetting a VD vs. SOC relationship includes: presetting the VD vs. SOC relationship at a plurality of different temperatures; the method for estimating state of charge further includes: detecting a current battery temperature; updating the VD vs. SOC relationship according to the first voltage difference of the battery includes: updating the VD vs. SOC relationship at each of the plurality of different temperatures according to the first voltage difference of the battery and the battery temperature.

According to some embodiments of the present application, determining a variation of the SOC of the battery when the battery gets fully discharged via simulation and according to the updated VD vs. SOC relationship includes: updating a ratio coefficient table at a preset discharge rate between the first voltage difference of the battery corresponding to each of the plurality of different SOCs of the battery at each of the plurality of different temperatures and the first voltage difference of the battery corresponding to each of the plurality of different SOCs of the battery at preset temperature according to the updated VD vs. SOC relationship; determining the variation of the SOC of the battery when the battery gets fully discharged via simulation and according to the updated ratio coefficient table.

According to some embodiments of the present application, determining the variation value of the SOC of the battery when the battery gets fully discharged via simulation and according to the updated ratio coefficient table includes: determining a current SOC of the battery; estimating a current voltage of the battery according to the current SOC of the battery, a current temperature of the battery, and an updated ratio coefficient table; determining whether the current voltage of the battery is less than or equal to a voltage when the battery gets fully discharged; if the current voltage of the battery is greater than the voltage when the battery gets fully discharged, continuing to determine the current SOC of the battery, and estimate the current voltage of the battery according to the current SOC of the battery, the current temperature of the battery, and the updated ratio coefficient table until the current voltage of the battery is less than or equal to the voltage when the battery gets fully discharged; and if the current voltage of the battery is less than or equal to the voltage when the battery gets fully discharged, determining the variation value of the SOC of the battery when the battery gets fully discharged.

According to some embodiments of the present application, determining a current SOC of the battery includes: detecting a previous SOC of the battery; and estimating a current SOC of the battery according to the previous SOC of the battery.

According to some embodiments of the present application, when the current voltage of the battery is estimated for a first time: detecting the previous SOC of the battery includes: detecting the SOC of the battery at a beginning of the simulation; and estimating the current SOC of the battery according to the previous SOC of the battery includes: estimating the current SOC of the battery according to the SOC of the battery at the beginning of the simulation.

According to some embodiments of the present application, estimating the current voltage of the battery according to the current SOC of the battery, the current temperature of the battery, and an updated ratio coefficient table includes: estimating a current open circuit voltage (hereinafter OCV) according to the current SOC of the battery; estimating a current voltage difference of the battery according to the current SOC of the battery, the current temperature of the battery, and the updated ratio coefficient table; estimating the current voltage of the battery according to the current OCV and the current voltage difference of the battery.

According to some embodiments of the present application, estimating the current voltage difference of the battery according to the current SOC of the battery, the current temperature of the battery, and the updated ratio coefficient table includes: estimating a voltage difference coefficient at a discharge current of the battery according to the updated ratio coefficient table; and estimating the current voltage difference of the battery according to the current SOC of the battery, the current temperature of the battery, and the voltage difference coefficient.

According to some embodiments of the present application, estimating the voltage difference coefficient at the discharge current of the battery according to the updated ratio coefficient table includes: estimating the voltage difference coefficient at the discharge current of the battery according to an equation

k=K⁡(SOC,T)×IMC,
wherein k is the voltage difference coefficient at the discharge current of the battery, K(SOC, T) is the updated ratio coefficient table, I is the discharge current of the battery, and MC is a preset discharge rate.

According to some embodiments of the present application, estimating a current voltage difference of the battery according to the current SOC of the battery, the current temperature of the battery, and the voltage difference coefficient includes: estimating a current voltage difference of the battery according to an equation ΔV(SOC,T,I)=ΔV(SOC,N° C.)×k, wherein ΔV(SOC,T,I) is the current voltage difference of the battery, ΔV(SOC,N° C.) is a VD vs. SOC relationship at a preset temperature and at a preset discharge rate, N° C. is a preset temperature, and k is a voltage difference coefficient at a discharge current of the battery.

According to some embodiments of the present application, before estimating the current voltage difference of the battery according to the current SOC of the battery, the current temperature of the battery, and the updated ratio coefficient table, the method for estimating state of charge further includes: estimating the current temperature of the battery.

According to some embodiments of the present application, estimating the current temperature of the battery includes: detecting a previous temperature of the battery; estimating a current variation value of the temperature of the battery; and estimating the current temperature of the battery according to the previous temperature of the battery and the current variation value of the temperature of the battery.

According to some embodiments of the present application, estimating the current variation value of the temperature of the battery includes: estimating the current variation value of the temperature of the battery according to an equation

⁢c×m×d⁢Td⁢t=I2×R+I×T×∂E∂T-h×S×(T-Tenv),
wherein c is a specific heat capacity of the battery, m is a quality of the battery,

d⁢Td⁢t
is a variation value of the temperature of the battery, I is a discharge current of the battery, R is a current impedance of the battery, T is a previous temperature of the battery,

∂E∂T
is an entropy coefficient of the battery, h is a heat transfer coefficient of the battery, S is a surface area of the battery, and Tenv is an environment temperature.

According to some embodiments of the present application, before estimating the current variation value of the temperature of the battery according to the equation

c×m×d⁢Td⁢t=I2×R+I×T×∂E∂T-h×S×(T-Tenv),
the method for estimating state of charge further includes: querying an updated VD vs. SOC relationship to estimate a terminal voltage of the battery according to the current SOC of the battery; and estimating the current impedance of the battery according to an equation

R=VI,
wherein R is the current impedance of the battery, V is the terminal voltage of the battery, and I is a discharge current of the battery.

According to some embodiments of the present application, estimating a residual capacity of the battery according to the variation value of the SOC of the battery includes: estimating the residual capacity of the battery according to an equation Qres=ΔSOC×Qabs, wherein Qresis the residual capacity of the battery, ΔSOC is the variation value of the SOC of the battery, and Qabsis an actual capacity-2 of the battery.

According to some embodiments of the present application, after estimating the residual capacity of the battery according to the variation value of the SOC of the battery, the method for estimating state of charge includes: estimating a full charge capacity of the battery; and estimating the residual SOC of the battery according to the residual capacity of the battery and the full charge capacity of the battery.

According to some embodiments of the present application, estimating the full charge capacity of the battery includes: estimating the full charge capacity of the battery via an equation FCC=Qstar+Qpast+Qres, wherein FCC is the full charge capacity of the battery, Qstaris a discharge capacity at the SOC after the full charge of the battery and before the first charge and discharge cycle, Qpastis a discharge capacity after the SOC and before the beginning of the simulation, and Qresis the residual capacity of the battery.

According to some embodiments of the present application, estimating the residual SOC of the battery according to the residual capacity of the battery and the full charge capacity of the battery includes: estimating the residual SOC of the battery according to an equation

R⁢S⁢O⁢C=Qr⁢e⁢sFCC,
wherein RSOC is the residual SOC of the battery, Qresis the residual capacity of the battery, and FCC is the full charge capacity of the battery.

An embodiment of the present application also provides an electronic device, the electronic device includes a battery, at least one processor, and a storage system storing one or more programs that when executed by the at least one processor, causes the at least one processor to preset a VD vs. SOC relationship, detect a SOC-1, determine a first voltage difference of the battery according to the SOC-1, and update the VD vs. SOC relationship according to the first voltage difference of the battery.

An embodiment of the present application also provides a non-transitory storage unit, the non-transitory storage unit having stored thereon instructions that when executed by a processor of a terminal device, cause the processor to perform a method for updating voltage difference of battery, the electronic device comprising a battery, the method comprising the presetting of a VD vs. SOC relationship, detecting a SOC-1, determining a first voltage difference of the battery according to the SOC-1, and updating the VD vs. SOC relationship according to the first voltage difference of the battery.

The method for updating voltage difference of battery, the method for estimating state of charge, the electronic device, and the storage unit provided by the present disclosure require the presetting of a VD vs. SOC relationship, the detecting of a SOC-1, the determining of a first voltage difference of the battery according to the SOC-1, and the updating of the VD vs. SOC relationship according to the first voltage difference of the battery. Thus, the method for updating voltage difference of battery, the method for estimating state of charge, the electronic device, and the storage unit provided by the present disclosure work together to update the VD vs. SOC relationship.

