Protection circuit and battery unit

• US 6,051,955 A
• Filed: 12/01/1997
• Issued: 04/18/2000
• Est. Priority Date: 05/19/1997
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ozawa, Hidekiyo, Saeki, Mitsuo, Takeda, Yoshiro, Tsukuni, Toshiaki
• Primary Examiner(s): Tso, Edward H.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US08/982,937
• Time in Patent Office: 869 Days
• Field of Search: 320/117, 320/119, 320/121, 320/122, 320/162
• US Class Current: 320/121
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection

Abstract

A protection circuit is used for a battery unit which has a plurality of cell parts coupled in parallel, and first and second power supplying terminals, where each of the cell parts includes a plurality of battery cells coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals. The protection circuit includes a plurality of switching elements making an electrical connection to the first terminal of a corresponding one of the cell parts and the first power supplying terminal, and disconnecting the electrical connection in response to an active signal, and a voltage monitoring circuit outputting the active signal to the switching elements when a voltage of at least one battery cell within one cell part falls outside a predetermined range, independently with respect to each of the cell parts.

Claims

1. A protection circuit for use with a battery unit which has a plurality of cell parts coupled in parallel and power supplying terminals, each of the cell parts including a plurality of battery cells coupled in series and terminals respectively coupled to the power supplying terminals, said protection circuit comprising:

a switching element which makes an electrical connection to the power supplying terminal, and disconnects the electrical connection in response to a signal; and

a monitoring circuit which outputs the signal to said switching element when a voltage of at least one battery cell of one cell part falls outside a predetermined range, so that no current is supplied from said one cell part to other cell parts.

2. The protection circuit as claimed in claim 1, wherein said monitoring circuit is provided independently with respect to each of the cell parts, and includes a signal output circuit which outputs a signal to each battery cell of a corresponding one of the cell parts when a voltage of a battery cell of the corresponding cell part falls outside the predetermined range.

3. The protection circuit as claimed in claim 2, wherein said monitoring circuit further includes a logical sum circuit which outputs to said switching element a logical sum of signals output from said signal output circuit with respect to each of the battery cells within the corresponding call part.

4. The protection circuit as claimed in claim 1, wherein said monitoring circuit includes first and second resistors which are connected in series and couple terminals of corresponding battery cells among different cell parts, and a circuit which outputs the signal to said switching element when a voltage at a node which connects said first and second resistors fall outside said predetermined range.

5. The protection circuit as claimed in claim 1, wherein said monitoring circuit includes first and second fuses which are connected in series and couple terminals of corresponding battery cells among different cell parts, and a circuit which outputs the signal to said switching element when a voltage at a node which connects said first and second fuses fall outside said predetermined range.

6. The protection circuit as claimed in claim 2, wherein said switching element is provided with respect to each said monitoring circuit.

7. The protection circuit as claimed in claim 1, wherein said predetermined range is set, based on a tolerable range of at least one of discharging and charging of the battery cells.

8. A protection circuit for use with a battery unit which has a plurality of cell parts coupled in parallel and first and second power supplying terminals, each of the cell parts including a plurality of battery cells coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals, said protection circuit comprising:

a switching element which makes an electrical connection to the first terminal of a corresponding one of the cell parts and to the first power supplying terminal, and disconnects the electrical connection in response to an active signal;

a resistor which couples terminals of corresponding battery cells among different cell parts; and

a circuit which outputs to said switching element a signal which becomes active when a voltage from said resistor falls outside a predetermined range.

9. The protection circuit as claimed in claim 8, wherein said resistor includes first and second resistors which are connected in series and couple the terminals of the corresponding battery cells among the different cell parts, and said circuit outputs to said switching element a signal which becomes active when a voltage at a node connecting said first and second resistors falls outside the predetermined range.

10. A protection circuit for use with a battery unit which has a plurality of cell parts coupled in parallel and first and second power supplying terminals, each of the cell parts including a plurality of battery calls coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals, said protection circuit comprising:

a switching element which makes an electrical connection to the first terminal of a corresponding one of the cell parts and to the first power supplying terminal, and disconnects the electrical connection in response to an active signal;

a fuse which couples terminals of corresponding battery cells among different cell parts; and

a circuit which outputs to said switching element a signal which becomes active when a voltage from said fuse falls outside a predetermined range.

11. The protection circuit as claimed in claim 10, wherein said fuse includes first and second fuses which are connected in series and couple the terminals of the corresponding battery cells among the different cell parts, and said circuit outputs to said switching element a signal which becomes active when a voltage at a node connecting said first and second fuses falls outside the predetermined range.

12. A protection circuit for use with a battery unit which has a plurality of series-connected battery cells coupled in parallel, comprising:

a short-circuit detection circuit which detects a short-circuit of a battery cell with respect to each of the plurality of battery cells; and

a circuit which cuts off a current supply to an arbitrary battery cell from another battery cell when said short-circuit detection circuit detects a short-circuit of said arbitrary battery cell from among the plurality of battery cells.

13. A protection circuit for use with a battery unit which has a plurality of battery calls coupled in parallel, comprising:

a monitoring circuit which monitors a voltage of each of the battery cells; and

a stop circuit which stops discharging or charging of each of the battery cells when said monitoring circuit monitors a voltage which falls outside a predetermined range in an arbitrary battery cell from among the battery cells.

14. The protection circuit as claimed in claim 13, wherein the battery unit has a plurality of battery cell groups coupled in parallel, and each of the battery cell groups includes a plurality of battery cells coupled in series.

15. The protection circuit as claimed in claim 13, which further comprises:

a discharging or charging prevention switch; and

said stop circuit controls said discharging or charging prevention switch.

16. The protection circuit as claimed in claim 15, wherein:

the battery unit has a plurality of battery cell groups coupled in parallel, and each of the battery cell groups includes a plurality of battery cells coupled in series; and

said discharging or charging prevention switch is provided with respect to each of said battery cell groups.

17. The protection circuit as claimed in claim 16, wherein:

said monitoring circuit is provided independently with respect to each of said battery cell groups; and

each of said monitoring circuits notifies a discharging or charging prevention switch which is provided with respect to a battery cell group other than a corresponding battery cell group when a voltage which falls outside the predetermined range is monitored in an arbitrary battery cell of the corresponding battery cell group.

18. A protection circuit for use with a battery unit which has a plurality of cell parts coupled in parallel and power supplying terminals, each of the cell parts including a plurality of battery cells coupled in series and terminals respectively coupled to the power supplying terminals, said protection circuit comprising:

a monitoring circuit which detects whether or not a voltage of at least one of the battery cells of one cell part falls outside a predetermined range.

19. The protection circuit as claimed in claim 18, which further comprises:

a switching element provided between the terminal of each of the cell parts and the power supplying terminal, and

said monitoring circuit controls said switching element.

20. The protection circuit as claimed in claim 19, wherein said monitoring circuit is provided independently with respect to each of the call parts, and comprises:

a signal output circuit which outputs to each battery cell, of a corresponding one of the cell parts, a signal which becomes active when a voltage of a battery cell of the corresponding cell part falls outside the predetermined range; and

a logical sum circuit which outputs to said switching element a logical sum of signals output from said signal output circuit with respect to each of the battery cells within the corresponding cell part.

21. The protection circuit as claimed in claim 18, wherein said predetermined range is set, based on a tolerable range of at least one of discharging and charging of the battery cells.

22. A protection circuit for use with a battery unit which has a plurality of cell parts coupled in parallel and power supplying terminals, each of the cell parts including a plurality of battery cells coupled in series and terminals respectively coupled to the power supplying terminals, said protection circuit comprising:

a resistor which couples terminals of corresponding battery cells among different cell parts; and

a signal output circuit which outputs a signal which becomes active when a voltage from said resistor falls outside a predetermined range and instructs disconnection of an electrical connection between the terminal of the cell parts and the power supplying terminal.

23. A protection circuit for use with a battery unit which has a plurality of cell parts coupled in parallel and power supplying terminals, each of the cell parts including a plurality of battery cells coupled in series and terminals respectively coupled to the power supplying terminals, said protection circuit comprising;

a fuse which couples terminals of corresponding battery cells among different cell parts; and

a signal output circuit which outputs a signal which becomes active when a voltage from said fuse falls outside a predetermined range and instructs disconnection of an electrical connection between the terminal of the cell parts and the power supplying terminal.

24. A protection circuit for use with a battery unit which has a plurality of series-connected battery cells coupled in parallel, comprising:

a short-circuit detection circuit which detects a short-circuit of a battery cell with respect to each of the plurality of battery cells; and

a circuit which outputs a signal which instructs a current supply, to an arbitrary battery cell from another battery cell, to be cut off when said short-circuit detection circuit detects a short-circuit of said arbitrary battery cell from among the plurality of battery cells.

25. A protection circuit for use with a battery unit which has a plurality of battery cells coupled in parallel, comprising:

a monitoring circuit which monitors a voltage of each of the battery cells;

an instruction circuit which outputs an instruction signal which instructs discharge or charging of each of the battery cells to stop when said monitoring circuit monitors a voltage which falls outside a predetermined range in an arbitrary one of the battery cells.

26. The protection circuit as claimed in claim 25, wherein:

the battery unit has a plurality of battery call groups coupled in parallel; and

each of the battery cell groups includes a plurality of battery cells coupled in series.

27. The protection circuit as claimed in claim 25, which further comprises:

a discharging or charging prevention switch,

said instruction circuit controlling said discharge or charging prevention switch by the instruction signal.

28. The protection circuit as claimed in claim 27, wherein:

the battery unit has a plurality of battery cell groups coupled in parallel and each of the battery cell groups includes a plurality of battery cells coupled in series; and

said discharging or charging prevention switch is provided with respect to each of the battery cell groups.

29. The protection circuit as claimed in claim 28, wherein:

said monitoring circuit is provided individually with respect to each of the battery cell groups; and

each said monitoring circuit notifies a discharging or charging prevention switch, which is provided with respect to a battery cell group other than a corresponding battery cell group, when a voltage which falls outside the predetermined range is monitored in an arbitrary battery cell of the corresponding battery cell group.

30. A protection circuit for use with a battery unit which has a plurality of series-connected battery cells coupled in parallel and a resistor coupling battery cells which have identical potentials in parallel, comprising;

a circuit which outputs a signal which instructs discharging or charging of the battery cells to be prohibited when a voltage from said resistor falls outside a predetermined range.

31. A battery unit comprising:

a plurality of cell parts coupled in parallel, each of said cell parts having first and second terminals and a plurality of battery calls coupled in series;

a first power supplying terminal coupled to the first terminal of each of said cell parts;

a second power supplying terminal coupled to the second terminal of each of said cell parts;

a plurality of switching elements, each of said switching elements making an electrical connection to the first terminal of a corresponding one of said cell parts and the first power supplying terminal and disconnecting the electrical connection in response to an active signal; and

a monitoring circuit which outputs a signal to said switching elements, which signal becomes active when a voltage of at least one of the battery cells of one cell part falls outside a predetermined range.

32. The battery unit as claimed in claim 31, wherein said monitoring circuit is provided independently with respect to each of the cell parts and includes a signal output circuit which outputs a signal to each battery cell of a corresponding one of the cell parts when a voltage of a battery cell of the corresponding cell part falls outside the predetermined range.

33. The battery unit as claimed in claim 32, wherein said monitoring circuit further includes a logical sum circuit which outputs, to a corresponding one of said switching elements, a logical sum of signals output from said signal output circuit with respect to each of the battery cells within the corresponding cell part.

34. The battery unit as claimed in claim 31, wherein said monitoring circuit includes first and second resistors which are connected in series and couple terminals of corresponding battery cells among different cell parts, and a circuit which outputs the signal to a corresponding one of said switching elements when a voltage, at a node which connects said first and second resistors, falls outside said predetermined range.

35. The battery unit as claimed in claim 31, wherein said monitoring circuit includes first and second fuses which are connected in series and couple terminals of corresponding battery cells among different cell parts, and a circuit which outputs the signal to a corresponding one of said switching elements when a voltage, at a node which connects said first and second fuses, falls outside said predetermined range.

36. The battery unit as claimed in claim 32, wherein each of said switching elements is provided with respect to each said monitoring circuit.

37. The battery unit as claimed in claim 31, wherein said predetermined range is set based on a tolerable range of at least one of discharging and charging of the battery cells.

38. A battery unit having a plurality of series-connected battery cells coupled in parallel, comprising:

a resistor which couples battery cells, which have identical potentials, in parallel, said resistor limiting a current flow between the battery cells coupled in parallel and preventing a current flow to an arbitrary battery cell from another battery cell when the arbitrary battery cell is short-circuited.

39. A battery unit having a plurality of series-connected battery cells coupled in parallel, comprising:

a fuse which couples battery cells, which have identical potentials, in parallel, said fuse limiting a current flow between the battery cells coupled in parallel and preventing a current flow to an arbitrary battery cell from another battery cell when the arbitrary battery cell is short-circuited.

40. A battery protection method for protecting a battery unit having a plurality of series-connected battery cells coupled in parallel, comprising;

a detection step detecting a short-circuit of a battery cell with respect to each of the battery cells; and

an instruction step instructing a cut off of a current supply to an arbitrary battery cell from another battery cell when said detection detects a short-circuit in the arbitrary battery cell among the plurality of battery cells.

41. A battery protection method for protecting a battery unit having a plurality of battery cells coupled in parallel, comprising:

monitoring a voltage of each of the battery cells; and

instructing an end of discharging or of charging of each of the battery cells when a voltage, which falls outside a predetermined range, is identified when monitoring an arbitrary battery cell.

42. The battery protection method as claimed in claim 41, wherein the battery unit has a plurality of battery cell groups coupled in parallel, and each of the battery cell groups includes a plurality of battery cells coupled in series.

43. The battery protection method as claimed in claim 41, which further comprises:

a discharging or charging prevention step; and

said instructing step controlling said discharging or charging prevention step based on the instruction.

44. The battery protection method as claimed in claim 43, wherein the battery unit has a plurality of battery cell groups coupled in parallel and each of the battery cell groups includes a plurality of battery cells coupled in series, further comprising:

performing said discharge or charging prevention step being carried out with respect to each of said battery cell groups.

45. The battery protection method as claimed in claim 44, further comprising:

performing said monitoring step with respect to each of said battery call groups; and

notifying the discharging or charging prevention step which is carried out with respect to a battery cell group, other than a corresponding battery cell group, when a voltage which falls outside the predetermined range is monitored in the arbitrary battery cell of the corresponding battery cell group.

46. A battery protection method for protecting a battery unit having a plurality of series-connected battery cells coupled in parallel, and a resistor coupling battery cells which have identical potentials in parallel, comprising:

making an instruction prohibiting discharging or charging of each of the battery cells when a voltage from the resistor falls outside a predetermined range.