Power battery SOH estimation method considering multi-factor influence

Abstract

The invention discloses a power battery SOH estimation method considering multi-factor influence. The method includes taking 25 DEG C, 0.3 C and SOC as standard working conditions at 40-60%, and performing a charging and discharging test under the working conditions so that the number of cycle life cycLife0 under the standard working conditions can be obtained; performing the charging and discharging test under different SOC ranges, different temperatures and different magnification conditions so that the number of the cycle life under different working condition environments can be obtained,and comparing the cycLife0 with the number of the cycle life under different SOC ranges, different temperatures and different magnification conditions so that ratio tables (sTable, tTable and iTable)can be obtained; during the running of an automobile, equivalently converting the number of the cycles under current temperatures, magnification and SOC into the number of the cycles under the standard working conditions according to the ratio tables (sTable, tTable and iTable); and utilizing a cyclic number conversion algorithm to calculate SOH under the equivalent standard working conditions. The method is simple in algorithm and high in calculating precision, and can calculate the SOH of all single cells, and therefore, management on the cells can be realized.

Description

technical field [0001] The invention relates to the technical field of SOH estimation of a power lithium battery system for a new energy vehicle, in particular to a power battery SOH estimation method considering the influence of multiple factors. Background technique [0002] In the battery management system of new energy vehicles, SOH symbolizes the healthy life state of lithium batteries, and is an important indicator for evaluating battery performance and aging. SOH is defined as: under standard conditions, the battery is discharged from the full state constant current discharge to the cut-off voltage as a percentage of its nominal capacity. The standard conditions are generally 0.3C, 25°C, and the nominal capacity is the ex-factory capacity calibrated by the manufacturer, expressed in Ca. When new energy vehicles leave the factory, the SOH is 100%. With the use of the battery, the battery gradually ages and the capacity decays. When the SOH becomes 80%, it means the en...

AI Technical Summary

Problems solved by technology

[0012] 1. The model is too shallow and does not take into account the influence of temperature, discharge depth, discharge rate and other factors on SOH

[0013] 2. Without considering the inconsistency of the battery, only the SOH of the battery pack can be calculated. However, in the actual battery pack, due to the different environments such as the temperature of the single battery and the depth of discharge, the SOH of the single battery will be different.

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