DE-102015109454-B4 - SYSTEMS AND METHODS FOR ESTIMATING THE CAPACITY OF A BATTERY STACK DURING CHARGE RETENTION USE

DE102015109454B4DE 102015109454 B4DE102015109454 B4DE 102015109454B4DE-102015109454-B4

Abstract

A method for estimating the capacity of a battery stack, wherein the method comprises: Charge throughput data is received, describing the amount of charge transferred into or out of the battery stack; the received charge throughput data are integrated; the integrated received charge throughput data are stored in a first data basket, which is assigned to increasing charge throughput data where a charge quantity is transferred into the battery stack, or in a second data basket, which is assigned to decreasing charge throughput data where a charge quantity is transferred out of the battery stack, based on a determination of whether the received charge throughput data includes increasing charge throughput data or decreasing charge throughput data; voltage-based state-of-charge movement data is received, which describes a movement of a state of charge of the battery stack based on a voltage of the battery stack; the received voltage-based charge state movement data are integrated; the integrated voltage-based state-of-charge movement data in a third data basket, the increasing voltage-based state-of-charge movement data, where the state of charge of the battery stack increases, is assigned, or is stored in a fourth data basket assigned to decreasing voltage-based state-of-charge motion data where the state of charge of the battery stack decreases, based on a determination of whether the received voltage-based state-of-charge motion data includes increasing voltage-based state-of-charge motion data or decreasing voltage-based state-of-charge motion data; an estimated charging capacity of the battery stack, determined from data during a charging process of the battery stack, based on data stored in the first data basket and the third data basket; and an estimated discharge capacity of the battery stack, determined from data during a discharge process of the battery stack, based on data stored in the second data basket and the fourth data basket.

Inventors

Kurt M. Johnson
Patrick Frost
Joon Hwang
Damon R. Frisch

Assignees

GM Global Technology Operations LLC (n. d. Ges. d. Staates Delaware)

Dates

Publication Date: 20260513
Application Date: 20150615
Priority Date: 20140617

Claims (10)

A method for estimating the capacity of a battery stack, comprising: receiving charge throughput data describing an amount of charge transferred into or out of the battery stack; integrating the received charge throughput data; storing the integrated received charge throughput data in a first data basket associated with increasing charge throughput data, where an amount of charge is transferred into the battery stack, or in a second data basket associated with decreasing charge throughput data, where an amount of charge is transferred out of the battery stack, based on a determination of whether the received charge throughput data includes increasing charge throughput data or decreasing charge throughput data; receiving voltage-based state-of-charge motion data describing a movement of a state of charge of the battery stack based on a voltage of the battery stack; integrating the received voltage-based state-of-charge motion data; The integrated voltage-based state-of-charge (SOC) movement data is stored in a third data basket, which is associated with increasing SOC movement data (where the state of charge of the battery stack increases), or in a fourth data basket, which is associated with decreasing SOC movement data (where the state of charge of the battery stack decreases), based on a determination of whether the received voltage-based SOC movement data includes increasing or decreasing SOC movement data; an estimated charge capacity of the battery stack, determined from data during a battery stack charging process, based on data stored in the first and third data baskets; and an estimated discharge capacity of the battery stack, determined from data during a battery stack discharge process, based on data stored in the second and fourth data baskets.
Procedure according to Claim 1 , the procedure further comprising: determining that a certain threshold set of data is present in the first data basket and is stored in the third data basket before the estimated charging capacity of the battery stack is determined.
Procedure according to Claim 1 , wherein the procedure further includes: determining that a certain threshold amount of data is stored in the second data basket and in the fourth data basket before determining the estimated discharge capacity of the battery stack.
Procedure according to Claim 1 , where determining the estimated charging capacity of the battery stack involves dividing a sum of the data stored in the first data basket by a sum of the data stored in the third data basket.
Procedure according to Claim 1 , wherein determining the estimated discharge capacity of the battery stack involves dividing a sum of the data stored in the second data basket by a sum of the data stored in the fourth data basket.
Procedure according to Claim 1 , where the first, second, third and fourth data baskets each contain multiple data containers.
Procedure according to Claim 6 , wherein the procedure further comprises: determining that a first data container of several data containers, which stores older data, and a second data container of several data containers, which stores newer data, are both full; and deleting the contents of the first data container on the basis of this determination.
System comprising: a battery stack; a first sensor configured to provide charge throughput data connected to the battery stack, describing the amount of charge transferred into or out of the battery stack; a second sensor configured to provide voltage-based state-of-charge movement data connected to the battery stack, describing the movement of the battery stack's state of charge based on a voltage applied to the battery stack; a computer-readable mass storage medium; and battery control electronics coupled communicatively to the first and second sensors and the computer-readable mass storage medium, the battery control electronics being configured to: receive the charge throughput data; integrate the received charge throughput data; to store the integrated received charge throughput data in a first data basket of the computer-readable storage medium, which is assigned to increasing charge throughput data, where a quantity of charge is transferred into the battery stack, or in a second data basket of the computer-readable mass storage medium, which is assigned to decreasing charge throughput data, where a quantity of charge is transferred out of the battery stack, based on a determination of whether the received charge throughput data includes increasing charge throughput data or decreasing charge throughput data; to receive the voltage-based state-of-charge movement data; to integrate the received voltage-based state-of-charge movement data; to store the integrated voltage-based state-of-charge movement data in a third data basket of the computer-readable mass storage medium, which is associated with increasing voltage-based state-of-charge movement data, during which the state of charge of the battery stack increases, or in a fourth data basket of the computer-readable mass storage medium, which is associated with decreasing voltage-based state-of-charge movement data, during which the state of charge of the battery stack decreases, based on a determination of whether the received voltage-based state-of-charge movement data includes increasing voltage-based state-of-charge movement data or decreasing voltage-based state-of-charge movement data; to determine an estimated charge capacity of the battery stack, derived from data during a charging process of the battery stack, based on data stored in the first data basket and in the third data basket; and to determine an estimated discharge capacity of the battery stack, derived from data obtained during a discharge process of the battery stack, based on data stored in the second data basket and the fourth data basket.
System according to Claim 8 , where the first, second, third and fourth data baskets each contain multiple data containers.
System according to Claim 9 , wherein the battery control electronics are further configured to: determine that a first data container of the multiple data containers, which stores older data, and a second data container of the multiple data containers, which stores newer data, are both full; and based on the determination to empty the contents of the first data container.

Description

TECHNICAL AREA This disclosure relates to systems and methods for estimating the capacity of a battery stack. In particular, but not exclusively, the systems and methods disclosed herein relate to estimating the capacity of a vehicle battery stack during operation with charge maintenance. BACKGROUND Passenger vehicles often contain electric batteries to power features of the vehicle's electrical and powertrain systems. For example, vehicles frequently include a 12V lead-acid automotive battery designed to supply electrical power to vehicle starter systems (e.g., a starter motor), lighting systems, and/or ignition systems. In electric vehicles, fuel cell vehicles (FC vehicles), and/or hybrid vehicles, a high-voltage battery system (HV battery system) (e.g., a 360V HV battery system) may be used to power the vehicle's electrical powertrain components (e.g., electric drive motors, etc.). For example, a rechargeable HV energy storage system (ESS) included in a vehicle may be used to power the vehicle's electrical powertrain components. Monitoring the capacity of a battery system can enable more accurate decisions regarding battery system control and/or management, thereby improving overall battery performance. Accurate knowledge of a battery system's capacity can also allow improved diagnostic and/or predictive methods to identify potential battery system problems. However, conventional methods for estimating battery system capacity are not particularly accurate when estimating the capacity of a battery system contained within a vehicle during trickle charging operation. The printed matter DE 10 2013 203 809 A1 A method and a device for determining the electrical capacitance of an energy storage unit are disclosed, in which the energy storage unit is repeatedly partially charged and discharged, and cell voltages are measured. The electrical capacitance is determined from the measured cell voltages. In the printed publication DE 11 2009 001 553 T5 A method for estimating battery capacity is disclosed, in which the battery's state of charge at two different times and the net charge flow to/from the battery between these two times are determined. The battery capacity is calculated as a function of the difference between the states of charge and the net charge flow. The object of the invention is to accurately estimate the capacity of a battery system during relatively small operating fluctuations at a given state of charge of the battery system. This problem is solved by the method according to claim 1 and the system according to claim 8. Specific embodiments are specified in the dependent claims. SUMMARY The systems and methods disclosed herein can provide a more accurate determination and/or more accurate estimate of the capacity of a battery system, thereby improving control, management, and diagnostic decisions for the battery system. Battery capacity can be a measure of how much energy can be stored in a battery system. In certain embodiments, the systems and methods disclosed herein can estimate the capacity of a battery system contained in a vehicle during maintenance charging operation. Specifically, the systems and methods disclosed herein can be used to estimate the capacity of a battery system during relatively small operating fluctuations in the state of charge (SOC) of the battery system. These relatively small operating fluctuations in the SOC can occur during maintenance charging operation of the battery system and/or an associated vehicle. In accordance with embodiments disclosed herein, a charging current throughput and a discharging current throughput can be accumulated separately during operation of a battery system (e.g., during maintenance charging of the vehicle connected to the battery system). Furthermore, an increasing voltage-based state of charge (“SOCv”) and a decreasing SOCv can be accumulated separately. After accumulating a sufficient number of samples, an estimated capacity (i.e., dAh/dSOC) can be calculated. In some embodiments, the estimated capacity can be used by a regression analysis to track changes in capacity over time. In certain embodiments, estimated capacities can be calculated by dividing the charge throughput by the increasing SOCv movement and by dividing the discharge throughput by the decreasing SOCv movement. In certain embodiments, separating the charge and discharge throughput and the increasing and decreasing voltage-based SOC movement into individual integrators (e.g., four total integrators) allows for the comparison of larger datasets, thereby increasing the accuracy of the capacity estimation. In certain embodiments, a method for estimating the capacity of a battery stack may include receiving charge throughput data and voltage-based state-of-charge motion data. The received charge throughput data may be integrated and stored in a first data basket associated with increasing charge throughput data or in a second data basket associated with decreasing charge