Method for evaluating consistency of battery pack

Abstract

The invention relates to the technical field of charging of a battery pack, in particular to a method for evaluating consistency of a rechargeable battery pack. The method comprises the following steps of: charging a battery pack and drawing a battery pack charging curve according to the terminal voltage of the battery pack; calculating direct current internal resistances of all batteries in the battery pack to obtain a charging curve removing ohmic pressure drop; calculating or measuring polarizing voltage to obtain a charging curve removing polarizing voltage influence; singly listing the charging curves of any two batteries; and correcting the two charging curves by adopting the difference of the maximal available capacity of the batteries and the initial state of charge (SOC) to obtain a battery pack charging curve with favorable consistency for finally evaluating the consistency of the battery pack. The corrected battery pack charging curve has favorable consistency; compared with a method for judging the consistency on the basis of singly adopting the outer voltage of the batteries, the difference of performance and a state among the batteries is fixed and is not changed along with the change of charging current and parameters, such as located charge state, and the like, and the problem of no stability brought by a method for evaluating the consistency on the basis of the difference of the applied voltage.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a consistency evaluation method for lithium battery packs. Background technique [0002] In order to achieve a certain voltage, power and energy level, batteries for electric vehicles need to be used in series in groups. Since it is impossible to be completely consistent in the process of production and use, the consistency of the battery pack is relative, and the inconsistency is absolute. Practice has found that even if strict screening and conditioning are carried out when forming a group, in actual use, the performance of a series battery pack in terms of capacity utilization, safety, and life is still far inferior to that of a single battery. The core problem lies in the inconsistency of the battery pack. sex. [0003] The consistency evaluation of battery packs is one of the cores of battery series application technology, which directly affects the safety and ef...

AI Technical Summary

Problems solved by technology

In the prior art, there have been many literatures discussing the consistency evaluation method of the battery pack, and a variety of equalization circuits have been proposed, but most of them are based on the external voltage difference between the batteries for consistency evaluation and implementation of equalization. Control, this evaluation method can not effectively indicate the inherent differences between batteries and lead to the degradation of the balance effect

This makes the capacity, size, cost and heat dissipation of the on-board equalizer difficult to solve; while the off-line equalizer will significantly increase the workload of battery maintenance, and ultimately hinder the large-scale application of electric vehicles

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