Battery pack capacity equilibrium method

Abstract

The invention provides a battery pack capacity equilibrium method. The battery pack capacity equilibrium method comprises the steps of recording a charging voltage curve of each single battery in a battery pack; recording the moment that voltage of one single battery reaches to pre-charging cut-off voltage Um as the full-charging moment t0 of the battery pack, and marking the single battery as a single battery 1; recording the voltage of other N-1 single batteries which do not reach the pre-charging cut-off voltage Um at the full-charging moment t0; calculating an estimated value of residual charging time; calculating estimated residual charging electric quantity of the N-1 single batteries; calculating equalizing current IE of an ith single battery according to the estimated residual charging electric quantity CRC of the ith single battery; performing equalization operation. By using the battery pack capacity equilibrium method, all of single batteries can achieve full-charging voltage after the battery pack is equalized, accordingly full equalization of the battery pack is achieved, and the capacity of the battery pack tends to maximum utilization.

Description

technical field [0001] The invention belongs to the technical field of power batteries for vehicles, and in particular relates to a battery pack capacity equalization method. Background technique [0002] In the functional system of pure electric vehicles, due to the limitation of the voltage and capacity of single lithium batteries, hundreds of battery cells must be connected in series and parallel to form a battery pack to provide sufficient power and energy for pure electric vehicles to meet their acceleration and climbing. and mileage requirements. If there is no difference between battery cells, then the battery pack and battery cells of a pure electric vehicle are consistent in terms of service life and safety. However, due to the inconsistency of the manufacturing process and the inconsistency of the use process environment, there is always inconsistency between battery cells. After the battery cells are grouped, their energy density, durability, and safety performa...

AI Technical Summary

Problems solved by technology

The disadvantage of the voltage-based equalization algorithm and the state-of-charge-based equalization algorithm is that the goal is to have the same voltage or state of charge, and due to the lack of information on the capacity of the battery cell, it may lead to over-balance of the battery pack.

Of course, the difficulty based on capacity equalization lies in how to obtain the battery cell capacity and state of charge, which is extremely difficult for online calculation and identification

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