A method for estimating battery polarization voltage in bms sleep mode

Abstract

The invention discloses an estimation method of the battery polarization voltage in a BMS (battery management system) sleep mode. The estimation method comprises the following steps that (1) a polarization voltage database is built, and a relationship comparison table between the battery polarization voltage U and three parameters including the battery average temperature T<avg>, the battery average voltage V<avg> and the battery average current I<avg> in the unit time duration before de-electrification is generated; (2) when a vehicle is in transient de-electrification, i.e., an BMS is in the sleep mode, the battery average temperature T<avg>, the battery average voltage V<avg> and the battery average current I<avg> in the unit time duration before de-electrification are detected; (3) the polarization voltage database is inquired according to the three parameters detected in the second step, and the battery polarization voltage U is obtained. The estimation method has the advantages that the battery polarization voltage U can be fast obtained, so the battery open circuit voltage U<ocv> is obtained, further, the fast correction on the SOC (state of charge) is realized, the precision of the SOC is favorably improved; the design scheme is simple and efficient, and the realization is easy; the polarization voltage database is dynamically updated, the battery aging influence is avoided, and the precision is higher.

Description

technical field [0001] The invention relates to a method for estimating battery polarization voltage in a BMS sleep mode. Background technique [0002] The electric vehicle power battery is composed of multiple batteries in series. Due to the inconsistency between the battery cells, the voltages after charging cannot be completely consistent, so the BMS is required to balance the battery pack. SOC (state of charge) refers to the state of charge, also known as the remaining capacity. When the battery is used for a period of time or left unused for a long time, the ratio of the remaining capacity to the capacity of the fully charged state is usually expressed as a percentage. SOC=1 means the battery is fully charged. The state of charge of the battery pack must be considered when the BMS balances the battery pack. [0003] During the use of electric vehicles, the SOC of the battery is mainly calculated based on the ampere-hour integral, but there is a certain error in the am...

AI Technical Summary

Problems solved by technology

[0003] During the use of electric vehicles, the SOC of the battery is mainly calculated based on the ampere-hour integral, but there is a certain error in the ampere-hour integral, which will lead to a certain error in the SOC, and the accumulated error will become larger and larger after a period of time