US 12,332,316 B2
State of charge determination method and apparatus for battery system
Ruijun Ma, Changzhou (CN); Qiang Yun, Changzhou (CN); Fangfang Pan, Changzhou (CN); and Kui Li, Changzhou (CN)
Assigned to CALB Co., Ltd., Jiangsu (CN)
Filed by CALB Co., Ltd., Jiangsu (CN)
Filed on Nov. 8, 2022, as Appl. No. 17/982,525.
Claims priority of application No. 202211061485.6 (CN), filed on Sep. 1, 2022.
Prior Publication US 2024/0077537 A1, Mar. 7, 2024
Int. Cl. G01R 31/36 (2020.01); G01R 31/3842 (2019.01); G01R 31/389 (2019.01)
CPC G01R 31/3648 (2013.01) [G01R 31/3842 (2019.01); G01R 31/389 (2019.01)] 15 Claims
OG exemplary drawing
 
1. A state of charge (SOC) determination method for a battery system equipped in an electric vehicle, comprising:
when a first correspondence between an open-circuit voltage (OCV) and a SOC and a second correspondence between an impedance and the SOC are determined, determining a correction coefficient at a current data collection moment according to the first correspondence, the second correspondence, and an operating current of the battery system at a previous data collection moment before the current data collection moment;
determining the SOC of the battery system at the current data collection moment; and
correcting the SOC at the current data collection moment based on the correction coefficient, such that the electric vehicle travels with the corrected SOC,
wherein the determining the correction coefficient at the current data collection moment according to the first correspondence, the second correspondence, and the operating current of the battery system at the previous data collection moment comprises:
determining a first change slope of the OCV and the SOC and a second change slope of the impedance and the SOC according to the first correspondence and the second correspondence;
determining a product of the second change slope and the operating current of the battery system at the previous data collection moment to obtain a second value; and
determining the correction coefficient at the current data collection moment according to the second value and the first change slope, comprising:
determining the correction coefficient at the current data collection moment through the following formulas:

OG Complex Work Unit Math
where p represents the correction coefficient at the current data collection moment, Ik−1 represents the operating current of the battery system at the previous data collection moment,

OG Complex Work Unit Math
represents the first change slope,

OG Complex Work Unit Math
represents the second change slope, T represents the time period between two adjacent data collection moments, τ represents a time constant of resistor-capacitor (RC) loops comprised in an equivalent circuit of the battery system, and

OG Complex Work Unit Math
represents the second value.