Protective circuit of battery pack

• US 20060139008A1
• Filed: 11/29/2005
• Published: 06/29/2006
• Est. Priority Date: 11/29/2004
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Park, Tae Heom
• Granted Patent: US 7,638,977 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• 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
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02H 3/20 responsive to excess voltage
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A protective circuit of a battery pack and a method of operating the protective circuit prevents the battery cells from being overcharged by directly detecting overcharge or detecting disconnection of sensing wires, which sense the voltage of battery cells, and instantly shuts off the high current being applied to the battery cells when the sensing wires are disconnected. The protective circuit includes at least one battery cell, and a cell voltage detecting unit adapted to detect the voltage of the battery cell. The protective circuit also includes a switch unit, and a control unit adapted to receive a signal from the cell voltage detecting unit and generate a predetermined control signal based on the signal of the cell voltage detecting unit in order to turn off the switch unit when the battery cell is overcharged or the sensing wire is disconnected.

Claims

1. A protective circuit of a battery pack, the protective circuit comprising:

at least one battery cell;

a cell voltage detecting unit coupled to negative and positive electrodes of the battery cell through a sensing wire so as to detect a voltage of the battery cell;

a switch unit coupled to a high current line in series between one terminal of the battery cell and a first external terminal; and

a control unit adapted to receive a signal from the cell voltage detecting unit and generate a predetermined control signal based on the signal of the cell voltage detecting unit, wherein the signal of the cell voltage detecting unit is based on the detected voltage, in order to operate the switch unit when the sensing wire is disconnected.

2. The protective circuit as claimed in claim 1, wherein the cell voltage detecting unit comprises:

a voltage-dividing resistor coupled to the battery cell;

a reference voltage source coupled to the voltage-dividing resistor; and

a comparator having;

a first input terminal coupled to the voltage-dividing resistor;

a second input terminal coupled to the reference voltage source; and

an output terminal coupled to the control unit.

3. The protective circuit as claimed in claim 1, wherein the cell voltage detecting unit comprises:

at least one voltage-dividing resistor coupled between negative and positive electrodes of the battery cell through the sensing wire;

a reference voltage source coupled to the negative electrode of the battery cell; and

a comparator having;

a non-inverting terminal coupled to the reference voltage source; and

an inverting terminal coupled to the voltage-dividing resistor to send an inverting signal to the control unit when a voltage applied to the non-inverting terminal is higher than a voltage applied to the inverting terminal.

4. The protective circuit as claimed in claim 3, wherein each of a plurality of resistance values of the voltage-dividing resistors coupled to the battery cells are different from each other.

5. The protective circuit as claimed in claim 3, wherein the comparator sends the inverting signal to the control unit upon disconnection of the sensing wire coupled to the battery cell.

6. The protective circuit as claimed in claim 1, wherein the control unit sends the control signal to the switch unit to turn off the switch unit when an inverting signal is transmitted thereto from the cell voltage detecting unit.

7. The protective circuit as claimed in claim 1, further comprising a current detecting unit coupled to the high current line in series between the battery cell and a second external terminal in order to detect a current applied to the battery cell.

8. The protective circuit as claimed in claim 1, wherein the switch unit includes a charge FET device and a discharge FET device, which are coupled to each other in series, and the control signal of the control unit is inputted into gates of the charge FET device and the discharge FET device.

9. The protective circuit as claimed in claim 8, wherein the charge FET device of the switch unit is turned off when the control signal of the control unit is applied to the charge FET device due to a disconnection of the sensing wire.

10. The protective circuit as claimed in claim 1, wherein the switch unit comprises:

a self control protector; and

an FET device for operating the self control protector.

11. The protective circuit as claimed in claim 10, wherein the self control protector comprises:

at least one fuse coupled to the high current line in series between the battery cell and the external terminal; and

a coil aligned between fuses for applying heat to the fuse, in which the coil is coupled to the battery cell through the FET device and a gate of the FET device receives the control signal of the control unit.

12. The protective circuit as claimed in claim 11, wherein the control unit sends the control signal to the gate of the FET device upon the disconnection of the sensing wire, so that the self control protector applies a current to the coil, thereby melting the fuse as a result of heat generated from the coil.

13. The protective circuit as claimed in claim 8, wherein the switch unit comprises a self control protector and an FET device for operating the self control protector.

14. The protective circuit as claimed in claim 1, wherein the cell voltage detecting unit forms an integrated circuit together with the control unit.

15. The protective circuit as claimed in claim 1, wherein the cell voltage detecting unit is fabricated in a form of an integrated circuit separately from the control unit.

16. A protective circuit of a battery pack, the protective circuit comprising:

at least one battery cell;

a cell voltage detecting unit coupled to negative and positive electrodes of the battery cell through a sensing wire so as to detect a voltage of the battery cell;

a switch unit coupled to a high current line in series between one terminal of the battery cell and an external terminal; and

a control unit adapted to receive a signal from the cell voltage detecting unit and generate a predetermined control signal based on the signal of the cell voltage detecting unit, wherein the signal of the cell voltage detecting unit is based on the detected voltage, in order to operate the switch unit when the battery cell is overcharged.

17. The protective circuit as claimed in claim 16, wherein the switch unit includes a charge FET device and a discharge FET device, which are coupled to each other in series, and the control signal of the control unit is inputted into gates of the charge FET device and the discharge FET device.

18. The protective circuit as claimed in claim 17, wherein the charge FET device of the switch unit is turned off when the control signal of the control unit is applied to the charge FET device due to an overcharge of the battery cell.

19. The protective circuit as claimed in claim 16, wherein the control unit sends the control signal to the gate of the FET device upon the overcharge of the battery cell so that the self control protector applies a current to the coil, thereby melting the fuse as a result of heat generated from the coil.

20. A method of determining whether a sensing wire in a protective circuit of a battery pack is disconnected, the method comprising:

detecting a voltage of a battery cell;

receiving a signal indicative of whether a predetermined sensing wire is disconnected, wherein the signal is based on the detected voltage; and

in response to the received signal indicating that the predetermined sensing wire is disconnected, generating a predetermined control signal to stop the charge of the battery cell.

21. A method of determining whether a sensing wire in a protective circuit of a battery pack is overcharged, the method comprising:

detecting a voltage of a battery cell;

receiving a signal indicative of whether the battery cell is overcharged; and

in response to the received signal indicating that the battery cell is overcharged, wherein the signal is based on the detected voltage generating a predetermined control signal to stop the charge of the battery cell.