Method for balancing states of charge of a battery having a plurality of battery cells as well as a corresponding battery management system and a battery

Abstract

The invention presents a method for balancing states of charge of N individual battery cells of a battery, which method first of all comprises the step of determining the individual cell capacities Capn of all n=1 to N cells (S1). This is followed by the determination of a k-th cell having the smallest cell capacity Capk (S2) and the determination of the individual states of charge SOCn (S3). The depth of discharge DODn is then determined (S4). In a further step, a target depth of discharge DODtarget,n is then determined, where D0Dtarget,n = Capn / 2+DODk-Capk / 2 (S5). The target depth of discharge is used to determine the target state of charge SOCtarget,n from SOCtarget,n = 1-DODtarget,n / Capn (S6). The deviation of the state of charge SOCn of a cell from the target state of charge SOCtarget,n thereof is then determined from [delta]SOCtarget,n=SOCn-SOCtarget,n (S7). In a further step, the minimum deviation [delta]SOCmin of the state of charge SOCn of a cell from the target state of charge SOCtarget,n thereof is determined from [delta]SOCmin = min ([delta]SOCtarget,n) (S8). At least one of the n=1 to N cells, to which [delta]SOCtarget,n-[delta]SOCmin > X applies, where X is a parameter with X>=0, is discharged (S9). If [delta]SOCtarget,n-[delta]SOCmin<=X now applies to all cells, the method is ended (S10 / S11). However, if this does not apply to all cells, the method returns to the step of determining the individual states of charge (S3) and the following steps are repeated (S4-S9).

Description

technical field [0001] The invention relates to a method for equalizing the state of charge of an accumulator having a plurality of accumulator cells, an accumulator management system comprising the method according to the invention, an accumulator, in particular a lithium-ion accumulator, having a battery according to the invention A battery management system for a battery, a motor vehicle with a battery according to the invention. The battery can be used in particular to drive a motor vehicle. Background technique [0002] For the future, it is expected that more battery systems can be used not only in stationary applications (such as wind turbines, backup power supply units or independent power networks), but also in vehicles (such as hybrid or pure electric vehicles). These battery systems place high demands on usable energy storage, charge-discharge-efficiency and reliability. [0003] In order to fulfill the requirements regarding the usable energy storage capacity, ...

AI Technical Summary

Problems solved by technology

However, for units with different capacities (such as due to production deviations and aging), this equalization strategy will cause unnecessary energy loss by equalization

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