Balance failure recovery method for electric vehicle power source capable of being charged and discharged in fixed capacity mode

Abstract

The invention relates to a balance failure recovery method for an electric vehicle power source capable of being charged and discharged in a fixed capacity mode. The technical problems that when balancing effects of existing voltage balance modes are influenced by contact internal resistance and the dropout voltage is not high, the electric current for charging and discharging is low, and balancing needs to be conducted for a long time are solved. The balance failure recovery method comprises the steps that (1) the charging cut-off voltage and the discharging cut-off voltage of all batteries are determined; (2) the rated charging and discharging cut-off voltage difference values are set, and the charging capacity and the discharging capacity of each battery are obtained; (3) the expected undercharged capacity, the expected residual discharging capacity, the expected charging cut-off voltage and the expected discharging cut-off voltage of each battery are obtained through charging and discharging curve piecewise linear fitting; and (4) each battery is charged and discharged in a fixed capacity mode, and failure recovery of the to-be-balanced power source is achieved. According to the balance failure recovery method, the batteries are externally charged or discharged in the fixed capacity mode and do not influenced by the contact internal resistance through the certain function relationship between the battery voltage and the battery capacitance in the charging terminal stage and the discharging terminal stage, the balanced current is high, and the time required by balancing is short.

Description

technical field [0001] The invention relates to a method for recovering a balanced fault of an electric vehicle power supply with constant-capacity charge and discharge, and belongs to the technical field of balanced fault recovery of the electric vehicle power supply. Background technique [0002] After the electric vehicle has been used for a period of time, it needs to maintain its power system. The most common fault in the power system is the balance fault, that is, the voltage difference between the battery packs in the static state or the charging and discharging state is greater than the specified value. The main reason is that the capacity and internal resistance of the single cells are inconsistent, or the self-discharge rate of the battery is inconsistent, which will eventually lead to inconsistent charging and discharging between the single cells, which will reduce the overall capacity of the battery pack. At this time, the battery will not be restored. The lifesp...

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Problems solved by technology

[0002] After the electric vehicle has been used for a period of time, it needs to maintain its power system. The most common fault in the power system is the balance fault, that is, the voltage difference between the battery packs in the static state or the charging and discharging state is greater than the specified value. The main reason is that the capacity and internal resistance of the single cells are inconsistent, or the self-discharge rate of the battery is inconsistent, which will eventually lead to inconsistent charging and discharging between the single cells, which will reduce the overall capacity of the battery pack. At this time, the battery will not be restored. The lifetime will accelerate the decay

[0003] At present, there are mainly two methods of equalization in the power management system: active equalization and passive equalization. The equalization effect of the existing voltage equalization method is affected by the contact internal resistance, and when the voltage difference is not large, the charge and discharge current is small, and the equalization takes a long time.

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