APPARATUS AND METHOD FOR MANAGING BATTERY PACK BY REFLECTING DEGRADATION DEGREE OF SECONDARY CELLS AND BATTERY PACK HAVING THE SAME

• US 20120274281A1
• Filed: 07/16/2012
• Published: 11/01/2012
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: KIM, Cheol-Taek
• Granted Patent: US 9,000,732 B2
• Time in Patent Office: Days
• US Class Current: 320/112
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery

Abstract

The present invention discloses an apparatus for managing a battery pack by reflecting a degradation degree of secondary cells, selecting the secondary cell having a maximum disparate voltage value among calculated disparate voltage values as a degraded cell in the current charging cycle, and updating the information on the degraded cell.

Claims

1. An apparatus for managing a battery pack by reflecting a degradation degree of secondary cells, the apparatus comprising:

a voltage sensing unit for measuring the voltages of a plurality of secondary cells constituting the battery pack;

a first monitoring unit for storing a first voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when all voltages of the plurality of secondary cells are not lower than a minimum reference voltage value in a charging cycle;

a second monitoring unit for storing a second voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when the voltage of one cell among the plurality of secondary cells is not lower than a maximum reference voltage value in the charging cycle; and

a controlling unit for calculating a disparate voltage value being the difference between the first voltage value and the second voltage value, selecting the secondary cell having a maximum disparate voltage value among the calculated disparate voltage values as a degraded cell in the current charging cycle, and updating the information on the degraded cell.

2. The apparatus for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 1, wherein in the case that the difference between a minimum disparate voltage value and the maximum disparate voltage value among the calculated disparate voltage values is not lower than a reference diagnosing value, the controlling unit selects the secondary cell having the maximum disparate voltage value as a degraded cell in the current charging cycle, and updates the information on the degraded cell.

3. The apparatus for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 1,

wherein in the case that the difference between a minimum disparate voltage value and the maximum disparate voltage value among the calculated disparate voltage values is not lower than a reference diagnosing value, the controlling unit outputs an alarm signal, and

wherein the apparatus further comprises a SOC determining unit for determining the SOC of the battery pack based on the voltage value of the degraded cell in the case that the alarm signal is input from the controlling unit.

4. The apparatus for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 3, wherein in the case that the alarm signal is input and then the present state of the battery pack is in a discharging mode, the SOC determining unit determines the lower value between the SOC based on an average voltage value of the plurality of secondary cells and the SOC based on the voltage value of the degraded cell, as a present SOC of the battery pack.

5. The apparatus for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 4, wherein in the case that the alarm signal is input and then the present state of the battery pack is in a charging mode, the SOC determining unit determines the higher value between the SOC based on the average voltage value of the plurality of secondary cells and the SOC based on the voltage value of the degraded cell, as a present SOC of the battery pack.

6. The apparatus for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 3, further comprising a balancing unit for conducting equalization on the remaining secondary cells excluding the degraded cell in the case that the alarm signal is input from the controlling unit.

7. The apparatus for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 1, wherein in the case that the charging cycle progresses in the state that the voltage values of the plurality of secondary cells exceed the minimum reference voltage or the charging cycle ends in the state that none of the plurality of secondary cells reaches the maximum reference voltage, the controlling unit maintains the degraded cell selected in the previous charging cycle as a degraded cell in the current charging cycle.

8. A method for managing a battery pack by reflecting a degradation degree of secondary cells, the method comprising:

a voltage sensing step of measuring the voltages of a plurality of secondary cells constituting the battery pack;

a first storing step of storing a first voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when all voltages of the plurality of secondary cells are not lower than a minimum reference voltage value in a charging cycle;

a second storing step of storing a second voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when the voltage of one cell among the plurality of secondary cells is not lower than a maximum reference voltage value in the charging cycle; and

a controlling step of calculating a disparate voltage value being the difference between the first voltage value and the second voltage value, selecting the secondary cell having a maximum disparate voltage value among the calculated disparate voltage values as a degraded cell in the current charging cycle, and updating the information on the degraded cell.

9. The method for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 8, wherein in the case that the difference between a minimum disparate voltage value and the maximum disparate voltage value among the calculated disparate voltage values is not lower than a reference diagnosing value, in the controlling step, the secondary cell having the maximum disparate voltage value is selected as a degraded cell in the current charging cycle and information on the degraded cell is updated.

10. The method for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 8,

wherein in the case that the difference between a minimum disparate voltage value and the maximum disparate voltage value among the calculated disparate voltage values is not lower than a reference diagnosing value, in the controlling step an alarm signal is output, and

wherein the method further comprises a SOC determining step of determining the SOC of the battery pack based on the voltage value of the degraded cell in the case that the alarm signal is input.

11. The method for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 10, wherein in the case that the alarm signal is input and then the present state of the battery pack is in a discharging mode, in the SOC determining step, the lower value between the SOC based on an average voltage value of the plurality of secondary cells and the SOC based on the voltage value of the degraded cell is determined as a present SOC of the battery pack.

12. The method for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 11, wherein in the case that the alarm signal is input and then the present state of the battery pack is in a charging mode, in the SOC determining step, the higher value between the SOC based on the average voltage value of the plurality of secondary cells and the SOC based on the voltage value of the degraded cell is determined as a present SOC of the battery pack.

13. The method for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 10, further comprising a balancing step of conducting equalization on the remaining secondary cells except of the degraded cell in the case that the alarm signal is input.

14. The method for managing a battery pack by reflecting a degradation degree of secondary cells according to claim 8, wherein in the case that the charging cycle progresses in the state that the voltage values of the plurality of secondary cells exceed the minimum reference voltage or the charging cycle ends in the state that none of the plurality of secondary cells reaches the maximum reference voltage, in the controlling step, the degraded cell selected in the previous charging cycle is maintained as a degraded cell in the current charging cycle.

15. A battery pack comprising a plurality of secondary cells for supplying power by a charging and discharging process and a managing module reflecting a degradation degree of secondary cells, the managing module comprising:

a voltage sensing unit for measuring the voltages of a plurality of secondary cells constituting the battery pack;

a first monitoring unit for storing a first voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when all voltages of the plurality of secondary cells are not lower than a minimum reference voltage value in a charging cycle;

a second monitoring unit for storing a second voltage value being the voltage value that each of the plurality of secondary cells individually represents at the time when the voltage of one cell among the plurality of secondary cells is not lower than a maximum reference voltage value in the charging cycle; and

a controlling unit for calculating a disparate voltage value being the difference between the first voltage value and the second voltage value, selecting the secondary cell having a maximum disparate voltage value among the calculated disparate voltage values as a degraded cell in the current charging cycle, and updating the information on the degraded cell.

16. The battery pack comprising a managing module reflecting a degradation degree of secondary cells according to claim 15, wherein in the case that the difference between a minimum disparate voltage value and the maximum disparate voltage value among the calculated disparate voltage values is not lower than a reference diagnosing value, the controlling unit selects the secondary cell having the maximum disparate voltage value as a degraded cell in the current charging cycle, and updates information on the degraded cell.

17. The battery pack comprising a managing module reflecting a degradation degree of secondary cells according to claim 15,

wherein in the case that the difference between a minimum disparate voltage value and the maximum disparate voltage value among the calculated disparate voltage values is not lower than a reference diagnosing value, the controlling unit outputs an alarm signal, and

wherein the managing module further comprises a SOC determining unit for determining the SOC of the battery pack based on the voltage value of the degraded cell in the case that the alarm signal is input from the controlling unit.

18. The battery pack comprising a managing module reflecting a degradation degree of secondary cells according to claim 17, wherein in the case that the alarm signal is input and then the present state of the battery pack is in a discharging mode, the SOC determining unit determines the lower value between the SOC based on an average voltage value of the plurality of secondary cells and the SOC based on the voltage value of the degraded cell, as a present SOC of the battery pack.

19. The battery pack comprising a managing module reflecting a degradation degree of secondary cells according to claim 18, wherein in the case that the alarm signal is input and then the present state of the battery pack is in a charging mode, the SOC determining unit determines the higher value between the SOC based on the average voltage value of the plurality of secondary cells and the SOC based on the voltage value of the degraded cell as a present SOC of the battery pack.

20. The battery pack comprising a managing module reflecting a degradation degree of secondary cells according to claim 17, wherein the managing module further comprises a balancing unit for conducting equalization on the remaining secondary cells excluding the degraded cell in the case that the alarm signal is input from the controlling unit.

21. The battery pack comprising a managing module reflecting a degradation degree of secondary cells according to claim 15, wherein in the case that the charging cycle progresses in the state that the voltage values of the plurality of secondary cells exceed the minimum reference voltage or the charging cycle ends in the state that none of the plurality of secondary cells reaches the maximum reference voltage, the controlling unit maintains the degraded cell selected in the previous charging cycle as a degraded cell in the current charging cycle.