Battery pack equalization control method and control circuit

Abstract

The invention relates to the technical field of battery balancing and discloses a balancing control method and circuit for a battery pack. The method comprises the steps: during initial charging, detecting the voltage of a plurality of single cells in the battery pack, comparing the detected voltage of the single cells with a set value V1, carrying out voltage balancing on the single cells, of which the detected voltage is higher than or equal to the set value V1, and recording numbers of balanced single cells; during N (N is greater than 1)-time charging, carrying out balancing on the single cells according to the recorded single cell numbers. Balancing can be started at the initial stage of charging, so that the balance time of the battery pack is prolonged by several folds, and the efficiency of balancing is increased greatly.

Description

technical field [0001] The present invention relates to the technical field of battery equalization, in particular, to a battery pack equalization control method. Background technique [0002] With the aggravation of environmental pollution and energy shortage, new energy technologies such as electric vehicles have attracted worldwide attention and developed rapidly, but the energy storage of batteries is still the bottleneck of the development of electric vehicles. [0003] Limited by the voltage and capacity of a single cell, when lithium batteries are used in electric vehicles, energy storage systems and other fields, they must be connected in series and parallel to increase the capacity and voltage of the battery pack. Due to the limitation of the production process, even the single batteries produced in the same batch have different performance parameters such as internal resistance, capacity and self-discharge rate, and with the increase of cycle charge and discharge t...

AI Technical Summary

Problems solved by technology

There are some defects in the actual use of passive equalization, such as: 1) The equalization current of passive equalization is small, the main reason is that passive equalization uses internal resistance to convert battery electric energy into heat energy for equalization, during which heat energy is dissipated, As a result, if the equalization current is too large, the equalization circuit may be burned due to excessive temperature; 2) Passive equalization is generally turned on at the end of charging, the main reason is that the battery terminal voltage changes drastically during the battery discharge process, During the charging process, the battery is at the platform voltage most of the time, the voltage difference is small, and the accuracy and lag of the battery management system BMS detection voltage, etc., may lead to more power consumption during the discharge process and when equalization is turned on on the charging platform. Low cells are equalized, which exacerbates the inconsistency of the battery pack, and the time at the end of the charge is shorter

These two reasons lead to the low efficiency of passive equalization

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