CN-121995256-A - Device for diagnosing state of battery and method thereof

Abstract

An apparatus for diagnosing a state of a battery and a method thereof are capable of accurately diagnosing a state of the battery and a state of each cell constituting the battery by monitoring a charge current of the battery to determine a diagnosis time interval in which a preset current variation value is maintained, determining a first voltage and a second voltage within the diagnosis time interval, determining a time required for each cell voltage of each cell of the battery to reach the second voltage from the first voltage within the diagnosis time interval, and diagnosing the state of the battery based on the time corresponding to each cell.

Inventors

• Bai Yuehan

Assignees

• 现代自动车株式会社
• 起亚株式会社

Dates

Publication Date

20260508

Application Date

20250319

Priority Date

20241104

Claims (18)

1. 1. An apparatus for diagnosing a state of a battery, the apparatus comprising: a current sensor configured to determine a charging current of the battery; A voltage sensor configured to determine a voltage of the battery, and A controller configured to: monitoring the charge current of the battery to determine a diagnostic time interval for maintaining a preset current variation value, Determining a first voltage and a second voltage as a voltage range of the diagnostic time interval, Determining a time required for each cell voltage of each of a plurality of cells of the battery to reach a second voltage from a first voltage within the diagnostic time interval, The state of the battery is diagnosed based on the time corresponding to each cell.
2. 2. The apparatus for diagnosing a state of a battery according to claim 1, wherein the controller is further configured to: Determining the maximum and minimum voltages of each cell during the diagnostic time interval, Determining the highest value of the minimum voltages of the plurality of cells as the first voltage of the diagnostic time interval, The lowest value of the maximum voltages of the plurality of cells is determined as the second voltage of the diagnostic time interval.
3. 3. The apparatus for diagnosing a state of a battery according to claim 1, wherein the controller is further configured to: Determining a standard deviation of times corresponding to the plurality of cells, And diagnosing the state of the battery based on the standard deviation.
4. 4. The apparatus for diagnosing a state of a battery according to claim 1, wherein the controller is further configured to: A plurality of diagnostic time intervals are determined, Determining a first voltage and a second voltage for each diagnostic time interval, The time required for the cell voltages to reach the second voltage from the first voltage is determined for each diagnostic time interval, The state of the battery is diagnosed based on a time corresponding to each cell within each of the plurality of diagnostic time intervals.
5. 5. The apparatus for diagnosing a state of a battery according to claim 4, wherein the controller is further configured to: determining a standard deviation of times corresponding to the plurality of cells within each diagnostic time interval, The state of the battery is diagnosed based on the standard deviation of each diagnostic time interval.
6. 6. The apparatus for diagnosing a state of a battery according to claim 1, wherein the controller is further configured to: the voltage range is divided into a plurality of voltage intervals, The voltage interval time required for each cell voltage to reach the maximum voltage from the minimum voltage in each voltage interval is determined, The state of the battery is diagnosed based on the voltage interval time corresponding to each cell within each voltage interval.
7. 7. The apparatus for diagnosing a state of a battery according to claim 6, wherein the controller is further configured to: determining a standard deviation of voltage interval times corresponding to the plurality of cells within each voltage interval, The state of the battery is diagnosed based on the standard deviation of each voltage interval.
8. 8. The apparatus for diagnosing a state of a battery according to claim 1, wherein the controller is further configured to monitor a charging current of the battery for all time intervals except for a time interval of a state transition between a closed circuit voltage and an open circuit voltage.
9. 9. The apparatus for diagnosing a state of a battery according to claim 1, wherein the controller is further configured to determine a time interval of a constant current having a current variation value of 0 as the diagnosis time interval.
10. 10. A method of diagnosing a state of a battery, the method comprising: determining, by the controller, a diagnostic time interval for maintaining a preset current variation value by monitoring a charging current of the battery; Determining, by a controller, a first voltage and a second voltage as voltage ranges for the diagnostic time interval; Determining, by a controller, a time required for each cell voltage of each of a plurality of cells of a battery to reach a second voltage from a first voltage within the diagnostic time interval; The state of the battery is diagnosed by the controller based on the time corresponding to each cell.
11. 11. The method of claim 10, wherein determining the first voltage and the second voltage comprises: Determining a maximum voltage and a minimum voltage for each cell within the diagnostic time interval; determining a highest value of the minimum voltages of the plurality of cells as a first voltage of the diagnostic time interval; The lowest value of the maximum voltages of the plurality of cells is determined as the second voltage of the diagnostic time interval.
12. 12. The method of claim 10, wherein diagnosing the status of the battery comprises: Determining a standard deviation of times corresponding to the plurality of cells; and diagnosing the state of the battery based on the standard deviation.
13. 13. The method of claim 10, wherein diagnosing the status of the battery comprises diagnosing the status of the battery based on a time corresponding to each cell within each of a plurality of diagnostic time intervals based on determining the plurality of diagnostic time intervals.
14. 14. The method of claim 13, wherein diagnosing the status of the battery comprises: determining a standard deviation of the times corresponding to the respective cells within each diagnostic time interval; the state of the battery is diagnosed based on the standard deviation of each diagnostic time interval.
15. 15. The method of claim 10, wherein diagnosing the status of the battery comprises: Based on dividing the voltage range into a plurality of voltage intervals, a state of the battery is diagnosed based on a voltage interval time corresponding to each cell within each of the plurality of voltage intervals.
16. 16. The method of claim 15, wherein diagnosing the status of the battery comprises: determining a standard deviation of times corresponding to the plurality of cells within each voltage interval; The state of the battery is diagnosed based on the standard deviation of each voltage interval.
17. 17. The method of claim 10 wherein determining the diagnostic time interval includes monitoring a charge current of the battery for all time intervals except for a time interval of a state transition between a closed circuit voltage and an open circuit voltage.
18. 18. The method of claim 10, wherein determining a diagnostic interval comprises determining a time interval of constant current having a current change value of 0 as the diagnostic interval.

Description

Device for diagnosing state of battery and method thereof Cross Reference to Related Applications The present application claims the benefits and priorities of korean patent application No.10-2024-0154580 filed at the korean intellectual property office on 4/11/2024, the entire contents of which are incorporated herein by reference. Technical Field The present application relates to a technique for diagnosing a state of a battery mounted in an electric vehicle with high accuracy. Background Generally, an electric vehicle is a vehicle driven by electric energy, which is equipped with a battery including a plurality of battery cells storing electric energy. Such a battery cell converts chemical energy into electrical energy to supply electrical energy (discharge), or converts electrical energy supplied from the outside into chemical energy to store (charge). Since the electric vehicle is driven using the electric energy stored in the battery as a power source, the performance of the vehicle is significantly affected by the performance of the battery. Therefore, in order to improve the performance of the electric vehicle, the battery needs to be managed to maximize the performance. In recent years, since a battery cell excellent in performance is used to improve the power supply of a vehicle, and the number of battery cells is gradually increased, management of batteries is more required. Such battery management is generally performed by a Battery Management System (BMS). The battery management system measures cell state information (including voltage, current, temperature, etc.) of battery cells from a battery module provided in an electric vehicle, manages the battery cells using the cell state information and option values for controlling the battery cells, and performs cell balancing to maintain balance between the battery cells. Cell balancing is one of control operations of a battery management system for equalizing the voltage or charge of battery cells. Even if the battery cells of the battery module are manufactured under the same manufacturing conditions and environments, each battery cell may have a difference in electrical characteristics. Even if the battery cells of the battery module are mounted and operated in an electric vehicle, each battery cell may also have a difference in electrical characteristics. Due to such a difference in electrical characteristics, even though the battery cells are charged and discharged with the same current, a voltage imbalance or a residual amount imbalance may occur between the battery cells connected to each other, and the voltage imbalance or the residual amount imbalance between the battery cells may result in a reduction in the usable voltage range of the battery cells or a reduction in the charge and discharge cycles. Recently, electric vehicles frequently have a fire when charging a battery. This is caused by an abnormal state of the battery. In order to prevent such a fire, a technique capable of accurately diagnosing the state of a battery mounted in an electric vehicle is required. In some cases, in order to diagnose the state of the battery, a voltage change of the battery is monitored in a first transition section (or time interval) from a Closed Circuit Voltage (CCV) to an Open Circuit Voltage (OCV) and a second transition section (or time interval) from the OCV to the CCV, and the state of the battery is diagnosed based on the monitoring result. However, since the voltage change of the battery is monitored only in the first transition section and the second transition section, which are very short in time, the voltage change of the battery cannot be sufficiently monitored. Therefore, the battery state may not be diagnosed with high accuracy. The matters described in this background section are intended to facilitate an understanding of the background of the application and may include matters not already known to those of ordinary skill in the art. Disclosure of Invention The present application has been made to solve the above-mentioned problems, while maintaining the advantages achieved by the prior art. An aspect of the present application provides an apparatus for diagnosing a state of a battery and a method thereof, which are capable of accurately diagnosing not only the state of the battery but also the state of each cell constituting the battery by monitoring a charge current of the battery to determine or detect a current interval (i.e., a diagnosis time interval) in which a preset current variation value is maintained, determining a first voltage and a second voltage within the current interval, determining or detecting a time required for each cell voltage of each of a plurality of cells of the battery within the current interval to reach the second voltage from the first voltage, and diagnosing the state of the battery based on the time corresponding to each cell. Another aspect of the present application provides an apparatus for diagnos