Power balance method of power battery, battery management system and power electric car

Abstract

The invention discloses an electric quantity equalization method of a power battery, a battery management system and a dynamic electric vehicle. The method comprises the following steps of detecting a battery parameter of each single battery included by a battery pack in predetermined time, wherein the battery parameter at least includes an open-circuit voltage; according to the open-circuit voltage of each single battery, determining at least one single battery to be adjusted in the battery pack and determining an electric quantity which needs to be discharged by each single battery to be adjusted; and based on the electric quantity which needs to be discharged by each single battery to be adjusted, carrying out electric quantity equalization on each single battery to be adjusted. In the prior art, end voltage consistency is taken as an equalization target so as to carry out equalization on an electric quantity of the battery, and the above condition is limited by the state of the battery. In the invention, the above technical problem is solved.

Description

technical field [0001] The invention relates to the field of power balance of batteries, in particular to a method for power balance of power batteries, a battery management system and a power electric car. Background technique [0002] With the aggravation of environmental pollution and energy crisis, electric vehicles have received widespread attention in the automotive industry due to their diversified energy sources. In electric vehicles, multiple batteries are often used in series to obtain the high voltage required by the drive system. When multiple batteries are connected in series, although the current through each battery is the same, due to the difference in the self-discharge rate of each single battery and other losses such as the acquisition loss of the acquisition chip are not exactly the same, after the battery pack is connected in series, After years of cumulative effect, the state of charge of the battery is no longer consistent, resulting in a relatively la...

AI Technical Summary

Problems solved by technology

[0005] The prior art uses terminal voltage consistency as the balancing target to balance batteries, which has the following disadvantages: Since the internal resistance of each battery is not completely consistent, the voltage difference caused by the inconsistency of the internal resistance may exceed that due to The voltage difference caused by OCV inconsistency, under different temperature, current, and remaining power SOC conditions, due to the inconsistency of the internal resistance and the inconsistency of the state of charge, the contribution ratio to the voltage difference is uncertain, and the battery is forced to be balanced by the terminal voltage of the battery. It is equivalent to the default that a battery with a high terminal voltage has a high charge capacity, and a battery with a low terminal voltage has a low charge capacity. Such passive balancing or active balancing may cause the opposite result, that is, a battery with a high terminal voltage and a low OCV Misdischarged, while batteries with low terminal voltage and high OCV are mischarged or not discharged

However, since the measurement of OCV requires the battery to stand still for more than 2 hours in the state of no current at least, it needs to wait for a suitable working condition to be measured. Therefore, the battery’s power balance needs to be measured in real time. The battery is always in the condition of standing for more than 2 hours without current, that is, the vehicle needs to turn on the ignition lock and cannot be used for a long time to wait for the completion of equalization, which causes great inconvenience to vehicle users

[0007] Aiming at the problem that the prior art adopts terminal voltage consistency as the balance target to balance the power of the battery and is limited by the state of the battery, no effective solution has been proposed so far.

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