APPARATUS AND METHOD FOR DIAGNOSING ABNORMALITY IN CELL BALANCING CIRCUIT

• US 20110285539A1
• Filed: 08/01/2011
• Published: 11/24/2011
• Est. Priority Date: 02/22/2010
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: LEE, Sang-Hoon, Kim, Jee-Ho, Lee, Dal-Hoon
• Granted Patent: US 8,643,500 B2
• Time in Patent Office: Days
• US Class Current: 340/636.1
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Provided are an apparatus and a method for diagnosing an abnormality in a cell balancing circuit. The apparatus may include a floating capacitor charged with voltage of a battery cell, a cell balancing circuit for discharging the floating capacitor, a voltage measuring unit for measuring the battery cell voltage of the charged floating capacitor and a residual voltage of the discharged floating capacitor, and a control unit for determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor.

Claims

1. An apparatus for diagnosing an abnormality in a cell balancing circuit, the apparatus comprising:

a floating capacitor charged with voltage of a battery cell;

a cell balancing circuit for discharging the floating capacitor;

a voltage measuring unit for measuring the battery cell voltage of the charged floating capacitor and a residual voltage of the discharged floating capacitor; and

a control unit for determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor.

2. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 1, further comprising:

a first switch for establishing a connection between the floating capacitor and the battery cell or for releasing the connection; and

a second switch for establishing a connection between the floating capacitor and the voltage measuring unit or for releasing the connection.

3. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 2,

wherein the control unit charges the floating capacitor with the voltage of the battery cell by turning on the first switch and turning off the second switch, and

wherein the control unit applies the battery cell voltage of the charged floating capacitor or the residual voltage of the discharged floating capacitor to the voltage measuring unit by turning off the first switch and turning on the second switch.

4. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 1,

wherein the cell balancing circuit further includes:

a discharge resistor connected to the floating capacitor at each terminal for discharging the floating capacitor; and

a third switch for establishing a connection between the floating capacitor and the discharge resistor or for releasing the connection, and

wherein the control unit controls the third switch to discharge the floating capacitor.

5. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 2,

wherein the battery cell is plural, and

wherein the floating capacitor, the first and second switches, and the cell balancing circuit are provided at each battery cell.

6. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 5,

wherein the control unit simultaneously or sequentially turns on the first switches respectively corresponding to the battery cells, to charge the corresponding floating capacitors with the voltages of the battery cells.

7. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 5,

wherein the control unit simultaneously or sequentially turns on the second switches respectively corresponding to the battery cells, to apply the battery cell voltages of the charged floating capacitors or the residual voltages of the discharged floating capacitors to the voltage measuring unit.

8. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 5,

wherein the control unit simultaneously or sequentially turns on the third switches included in the cell balancing circuits respectively corresponding to the battery cells, to discharge the charged floating capacitors.

9. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 2,

wherein the control unit further includes:

a switch control module for controlling the operation of the first to third switches;

an A/D conversion module for converting an analog voltage signal outputted from the voltage measuring unit into a digital voltage signal; and

a central processing module for receiving the digital voltage signal from the A/D conversion module and determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor.

10. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 1,

wherein the control unit determines that there is an abnormality in the cell balancing circuit when the residual voltage of the discharged floating capacitor exceeds a preset reference voltage.

11. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 1,

wherein the control unit determines that there is an abnormality in the cell balancing circuit when a voltage difference between the battery cell voltage of the charged floating capacitor and the residual voltage of the discharged floating capacitor is less than a preset reference voltage.

12. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 1,

wherein the control unit further includes an abnormality alarm for visually or audibly outputting an abnormality in the cell balancing circuit, and

wherein the control unit controls the abnormality alarm to visually or audibly inform an abnormality in the cell balancing circuit when there is the abnormality in the cell balancing circuit.

16. A battery management system comprising the apparatus for diagnosing an abnormality in a cell balancing circuit defined in claim 1.

17. A battery operating system comprising the apparatus for diagnosing an abnormality in a cell balancing circuit defined in claim 1.

18. A battery pack comprising the apparatus for diagnosing an abnormality in a cell balancing circuit defined in claim 1.

13. An apparatus for diagnosing an abnormality in a cell balancing circuit, the apparatus comprising:

a floating capacitor charged with voltage of a battery cell;

a cell balancing circuit connected to the battery cell for balancing the voltage of the battery cell and discharging the floating capacitor;

a voltage measuring unit for measuring a residual voltage of the discharged floating capacitor; and

a control unit for determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor.

14. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 13,

wherein the control unit determines that there is an abnormality in the cell balancing circuit when the residual voltage of the discharged floating capacitor exceeds a preset reference voltage.

15. The apparatus for diagnosing an abnormality in a cell balancing circuit according to claim 13,

wherein the voltage measuring unit further measures the battery cell voltage of the charged floating capacitor, and

wherein the control unit determines that there is an abnormality in the cell balancing circuit when a voltage difference between the battery cell voltage of the charged floating capacitor and the residual voltage of the discharged floating capacitor is less than a preset reference voltage.

19. A method for diagnosing an abnormality in a cell balancing circuit, the method comprising:

charging a floating capacitor with voltage of a battery cell;

measuring the battery cell voltage of the charged floating capacitor through a voltage measuring unit;

discharging the floating capacitor using a cell balancing circuit;

measuring a residual voltage of the discharged floating capacitor through the voltage measuring unit; and

determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor.

20. The method for diagnosing an abnormality in a cell balancing circuit according to claim 19,

wherein the battery cell is plural, and

wherein the steps are simultaneously or sequentially performed on the plurality of battery cells.

21. The method for diagnosing an abnormality in a cell balancing circuit according to claim 19, further comprising:

controlling the operation of a first switch, a second switch, and a third switch;

converting an analog voltage signal outputted from the voltage measuring unit into a digital voltage signal; and

receiving the digital voltage signal and determining an abnormality in the cell balancing circuit based on the residual voltage of the discharged floating capacitor,

the first switch for establishing a connection between the floating capacitor and the battery cell or for releasing the connection;

the second switch for establishing a connection between the floating capacitor and the voltage measuring unit or for releasing the connection; and

the third switch for starting or ending the discharging of the cell balancing circuit.

22. The method for diagnosing an abnormality in a cell balancing circuit according to claim 19,

wherein the determining of an abnormality in the cell balancing circuit comprises determining that there is an abnormality in the cell balancing circuit when the residual voltage the discharged floating capacitor exceeds a preset reference voltage.

23. The method for diagnosing an abnormality in a cell balancing circuit according to claim 19,

wherein the determining of an abnormality in the cell balancing circuit comprises determining that there is an abnormality in the cell balancing circuit when a voltage difference between the battery cell voltage of the charged floating capacitor and the residual voltage of the discharged floating capacitor is less than a preset reference voltage.

24. The method for diagnosing an abnormality in a cell balancing circuit according to claim 19, further comprising:

visually or audibly informing an abnormality in the cell balancing circuit when there is the abnormality in the cell balancing circuit.