EP-4737930-A2 - BATTERY MANAGEMENT SYSTEM, BATTERY PACK, ELECTRIC VEHICLE AND BATTERY MANAGEMENT METHOD

EP4737930A2EP 4737930 A2EP4737930 A2EP 4737930A2EP-4737930-A2

Abstract

A battery management system according to the present disclosure includes a battery monitor, a balancer and a control circuit to control the balancer. The control circuit determines a first voltage value indicating a no-load voltage of each battery, compensates the first voltage value of each battery using a balancing capacity of each battery by a balancing operation for a latest reference time, determines a voltage deviation which is a difference between the compensated first voltage value of each battery and a reference voltage value, and detects an internal short circuit fault in each battery by comparing a change amount of the voltage deviation of each battery for the reference time with a threshold.

Inventors

PARK, HEE JU
KIM, CHEOL-TAEK
SUNG, YONG-CHUL

Assignees

LG Energy Solution, Ltd.

Dates

Publication Date: 20260506
Application Date: 20220726

Claims (15)

A battery management system, comprising: at least one processor; and a memory storing a program executable by the at least one processor, wherein the program, when executed by the at least one processor, causes the at least one processor to: acquire a no-load voltage value of each of a plurality of batteries, compensate, in a state in which a balancing operation for the plurality of batteries is being stopped, the no-load voltage value of each battery using a balancing capacity of each battery resulting from a past-performed balancing operation, determine a voltage difference between the compensated no-load voltage value of at least one battery among the plurality of batteries and a reference voltage value, and detect a fault in the at least one battery based on a change amount of the voltage difference of the at least one battery.
The battery management system according to claim 1, wherein the program, when executed by the at least one processor, causes the at least one processor to: increase a fault count of the at least one battery by 1 when the change amount of the voltage difference of the at least one battery is equal to or larger than a threshold, and detect the fault in the at least one battery when the fault count of the at least one battery is equal to or larger than a predetermined value.
The battery management system according to claim 1, wherein the reference voltage value is an average or median of the compensated no-load voltage values of at least two of the plurality of batteries.
The battery management system according to claim 1, wherein the program, when executed by the at least one processor, causes the at least one processor to compensate the no-load voltage value of each battery using a balancing capacity of each battery resulting from the past-performed balancing operation performed for a reference time, and wherein the reference time is longer than a duration of the balancing operation.
The battery management system according to claim 1, wherein the program, when executed by the at least one processor, causes the at least one processor to determine the balancing capacity of each battery by accumulating the discharge capacity of each battery by each balancing operation within a period of a reference time.
The battery management system according to claim 5, wherein the program, when executed by the at least one processor, causes the at least one processor to determine the discharge capacity of each battery by each balancing operation by applying a capacity estimation function to first balancing data associated with each balancing operation, and wherein the first balancing data includes the no-load voltage value of each battery at a start of the balancing operation and a duration of the balancing operation.
The battery management system according to claim 5, wherein the program, when executed by the at least one processor, causes the at least one processor to determine the discharge capacity of each battery by each balancing operation by applying a state of charge (SOC)-open circuit voltage (OCV) map to second balancing data of each balancing operation, and wherein the second balancing data includes the no-load voltage value of each battery at a start of the balancing operation and the no-load voltage value of each battery at an end of the balancing operation.
The battery management system according to claim 1, wherein the program, when executed by the at least one processor, causes the at least one processor to: determine an estimated SOC of each battery by applying a SOC-OCV map to the no-load voltage value of each battery, compensate the estimated SOC of each battery by adding a SOC change amount corresponding to the balancing capacity to the estimated SOC of each battery, and determine the compensated no-load voltage value by applying the SOC-OCV map to the compensated estimated SOC of each battery.
A battery pack comprising the battery management system according to any one of claims 1 to 8.
An electric vehicle comprising the battery pack according to claim 9.
A battery management method, comprising: acquiring a no-load voltage value of each of a plurality of batteries; compensating, in a state in which a balancing operation for the plurality of batteries is being stopped, the no-load voltage value of each battery using a balancing capacity of each battery resulting from a past-performed balancing operation; determining a voltage difference between the compensated no-load voltage value of at least one battery among the plurality of batteries and a reference voltage value; and detecting a fault in the at least one battery based on a change amount of the voltage difference of the at least one battery.
The battery management method according to claim 11, wherein detecting the fault in the at least one battery comprises: increasing a fault count of the at least one battery by 1 when the change amount of the voltage difference of the at least one battery is equal to or larger than the threshold; and detecting the fault in the at least one battery when the fault count of the at least one battery is equal to or larger than a predetermined value.
The battery management method according to claim 11, wherein the reference voltage value is an average or median of the compensated no-load voltage values of at least two of the plurality of batteries.
The battery management method according to claim 11, wherein compensating the no-load voltage value of each battery comprises: determining an estimated state of charge (SOC) of each battery by applying a SOC-open circuit voltage (OCV) map to the no-load voltage value of each battery; compensating the estimated SOC of each battery by adding a SOC change amount corresponding to the balancing capacity to the estimated SOC of each battery; and determining the compensated no-load voltage value by applying the SOC-OCV map to the compensated estimated SOC of each battery.
A program for performing the battery management method according to any one of claims 11 to 14, when the program is executed by at least one processor.

Description

TECHNICAL FIELD The present disclosure relates to internal short circuit fault detection of battery. The present application claims the benefit of Korean Patent Application No. 10-2021-0098141 filed on July 26, 2021 with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND ART Recently, there has been a rapid increase in the demand for portable electronic products such as laptop computers, video cameras and mobile phones, and with the development of electric vehicles, batteries for energy storage, robots and satellites, many studies are being made on high performance batteries that can be repeatedly recharged. Currently, commercially available batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries and the like, and among them, lithium batteries have little or no memory effect, and thus they are gaining more attention than nickel-based batteries for their advantages that recharging can be done whenever it is convenient, the self-discharge rate is very low and the energy density is high. To meet the high voltage and high capacity requirements of applications such as electric vehicles, a battery system (for example, a battery pack) including at least one battery group (i.e., a series connection structure of batteries) is widespread. In the battery system, there is a high possibility that a fault in a certain battery will adversely affect the overall performance and safety of the battery system. Accordingly, in the management of the battery system, it is important to accurately detect a fault in the individual battery. There may be differences in characteristics between batteries due to the internal/external factors in the manufacturing process and/or while in use. The differences in characteristics between batteries cause voltage imbalances. A balancer is widely used to mitigate the voltage imbalances between batteries by performing the balancing (for example, discharging) operation for each battery. Meanwhile, among battery fault types, an internal short circuit fault is the main fault that directly/indirectly affects fires. The internal short circuit fault occurs when a path of a leakage current is formed by side reactions in batteries and/or infiltration of impurities into batteries. The voltage imbalances between batteries have been used to detect a battery in an internal short circuit fault among the batteries. However, when the balancing operation is performed, the voltage imbalances between batteries which are important information for the internal short circuit fault detection are mitigated. That is, in the detection of the battery in an internal short circuit fault among the batteries, the balancing operation performed in the past acts as a hindering factor. DISCLOSURE Technical Problem The present disclosure is designed to solve the above-described problem, and therefore the present disclosure is directed to providing a battery management system, a battery pack, an electric vehicle and a battery management method for accurately detecting a battery in an internal short circuit fault among batteries in the absence of voltage imbalances between the batteries by the balancing operation. These and other objectives and advantages of the present disclosure may be understood by the following description and will be apparent from an embodiment of the present disclosure. In addition, it will be readily understood that the objectives and advantages of the present disclosure may be realized by the means set forth in the appended claims and a combination thereof. Technical Solution A battery management system according to an aspect of the present disclosure includes a battery monitor configured to detect a voltage of each of a plurality of batteries connected in series; a balancer configured to perform a balancing operation for each battery; and a control circuit configured to control the balancer based on the voltage of each battery detected by the battery monitor. The control circuit is configured to determine a first voltage value indicating a no-load voltage of each battery. The control circuit is configured to compensate the first voltage value of each battery using a balancing capacity of each battery by the balancing operation for a latest reference time. The control circuit is configured to determine a voltage deviation which is a difference between the compensated first voltage value of each battery and a reference voltage value. The control circuit is configured to detect an internal short circuit fault in each battery by comparing a change amount of the voltage deviation of each battery for the reference time with a threshold. The control circuit may be configured to increase a fault count of each battery by 1 when the change amount of the voltage deviation of each battery is equal to or larger than the threshold. The control circuit is configured to detect the internal s