Battery pack short-circuit protection circuit and method

• US 5,945,809 A
• Filed: 07/31/1997
• Issued: 08/31/1999
• Est. Priority Date: 07/31/1996
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Inaba, Tsutomu, Nishio, Eiji
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US08/903,735
• Time in Patent Office: 761 Days
• Field of Search: 320/125, 320/134, 320/136, 320/145, 320/112
• US Class Current: 320/134
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0036 using connection detecting circuits H02J7/0034 takes precedence

Abstract

A battery pack short-circuit protection circuit and a method whereby fire damage etc. of a battery pack caused by short-circuiting of terminals by metal objects etc., which cannot be prevented simply by an over-current cut-off switch, can be reliably prevented. In a current path between a battery pack charging/discharging terminal of the battery pack and a battery cell in the battery pack, there is provided a switching circuit that effects opening and closing of the current path; a switch drive circuit is provided that drives the switching circuit; the switching circuit closes the current path only when a drive control signal is applied through a control terminal from the charging/discharging device or the main unit of the equipment.

Claims

1. A short-circuit protection circuit for a battery pack build in a terminal device operated by a power supplied from the battery pack, comprising:

switching means provided on a current path between one of charging/discharging terminal exposed to outside of the terminal device to be connected to a charging/discharging device when charging/discharging the battery pack and a battery cell in the battery pack, for opening and closing the current path;

switch driving means for controlling the switching means to close when the switch driving means receives a drive control signal from the charging/discharging device and for controlling the switching means to open when the switch driving means does not receive the drive control signal; and

a control terminal for applying the drive control signal to the switch driving means when the battery pack is attached to the charging/discharging device.

2. A battery pack short-circuit protection circuit according to claim 1 wherein the drive control signal is generated within the charging/discharging device;

the control terminal is connected to the charging/discharging device simultaneously on connection of the charging/discharging terminal of the battery pack to the charging/discharging device; and

the drive control signal generated in the charging/discharging device is applied to the switch driving means through the control terminal.

3. A battery pack short-circuit protection circuit according to claim 1, wherein the drive control signal is generated within an equipment on which the battery pack is mounted;

the control terminal is connected to the equipment when the battery pack is mounted on the equipment; and

the drive control signal generated within the equipment is applied to the switch driving means through the control terminal.

4. A battery pack short-circuit protection circuit according to claim 3, wherein the equipment includes a charging/discharging control switch and, the drive control signal is generated when the charging/discharging control switch is enabled.

5. A battery pack short-circuit protection circuit according to claim 1, wherein the drive control signal is generated within the charging/discharging device and is generated within the equipment on which the battery pack is mounted;

and

the control terminal comprises;

a first control terminal to be connected to the charging/discharging device and a second control terminal to be connected to the equipment; and

application of the drive control signal to the switch driving means is performed from the charging/discharging device through the first control terminal or from the equipment through the second control terminal.

6. A battery pack short-circuit protection circuit according to claim 1, wherein the switching means is provided on a current path that connects a plus terminal of the charging/discharging terminals and a plus terminal of the battery cell.

7. A battery pack short-circuit protection circuit according to claim 1, wherein the switching means is provided on a current path that connects a minus terminal of the charging/discharging terminals and a minus terminal of the battery cell.

8. A battery pack short-circuit protection circuit according to claim 3, wherein, an operating level of the switch driving means is set to a different value in accordance with the type of capacity of the battery cell of the battery pack in which the switch driving means is incorporated, and

the charging/discharging device comprises:

drive control signal generating means for generating drive control signals of a plurality of levels;

decision means for deciding the type of capacity of the battery pack from a level of a drive control signal generated by the drive control signal generating means when the switch driving means is operated; and

charging/discharging control means for controlling charging/discharging of the battery cell of the battery pack in accordance with the type of capacity of the battery pack decided by the decision means.

9. A battery pack build in a terminal device, for supplying a drive power source, comprising:

a battery cell;

a plus charging/discharging terminal connected to a plus terminal of the battery cell through a first current path and exposed to outside of the terminal device that is connected to a charging/discharging device when the battery cell is charged or discharged;

a minus charging/discharging terminal connected to a minus terminal of the battery cell through a second current path and exposed to outside of the terminal device that is connected to the charging/discharging device when the battery cell is charged or discharged;

switching means provided on one of the first current path and the second current path, for opening and closing one of the first current path and the second current path;

switch driving means for controlling the switching means to close when the switch driving means receives a drive control signal from the charging/discharging device and for controlling the switching means to open when the switch driving means does not receive the drive control signal; and

a control terminal for applying the drive control signal to the switch driving means when the battery cell is charged or discharged.

10. A battery pack according to claim 9, wherein the drive control signal is generated within the charging/discharging device;

the control terminal is connected to the charging/discharging device simultaneously on connection of the charging/discharging terminal of the battery pack to the charging/discharging device; and

the drive control signal generated within the charging/discharging device is applied to the switch driving means through the control terminal.

11. A battery pack according to claim 9, wherein the drive control signal is generated within an equipment on which the battery pack is mounted;

the control terminal is connected to the equipment on mounting of the battery pack on the equipment; and

the drive control signal generated within the equipment is applied to the switch driving means through the control terminal.

12. A battery pack according to claim 11, wherein the equipment includes a charging/discharging control switch and, the drive control signal is generated when the charging/discharging control switch is enabled.

13. A battery pack according to claim 9, further comprising an over-current cut-off switch connected in series with the battery cell and whereby a charging/discharging current in respect of the battery cell is cut off if it exceeds a pre-set prescribed value.

14. A battery pack according to claim 9, further comprising:

temperature detection means provided within the battery pack, for detecting a temperature within the battery pack; and

a temperature detection terminal that transmits temperature information indicating the temperature detected by the temperature detection means to the charging/discharging device; and

the charging/discharging device comprises;

charging/discharging interruption controlling means for interrupting charging/discharging of the battery cell of the battery pack when the temperature indicated by the temperature information transmitted through the temperature detection terminal on charging/discharging of the battery cell of the battery pack exceeds a pre-set prescribed value.

15. A battery pack short-circuit protection method wherein a battery pack built in a terminal device is provided with switching means on a current path between a charging/discharging terminal of the battery pack, which is exposed to the outside of the terminal device, to be connected to a charging/discharging device and a battery cell within the battery pack, for opening and closing the current path, and provided with switch driving means for controlling the switching means to close when the switch driving means receives a drive control signal from the charging/discharging device and for controlling the switching means to open when the switch driving means does not receive the drive control signal, the method comprising:

a first step wherein the switching means is controlled to close by application of the drive control signal generated in the charging/discharging device to the switch driving means in a condition in which the battery pack is connected to the charging/discharging device for charging/discharging the battery cell of the battery pack; and

a second step wherein the switching means is controlled to open by the drive control signal generated by the charging/discharging device ceasing to be applied to the switch driving means in a condition in which the connection of the battery pack is removed from the charging/discharging device.

16. A battery pack short-circuit protection method wherein a battery pack built in a terminal device is provided with switching means on a current path between a charging/discharging terminal of the battery pack, which is exposed to the outside of the terminal device, to be connected to a charging/discharging device and a battery cell in the battery pack, for opening and closing the current path, and provided with switch driving means for controlling the switching means to close when the switch driving means receives a drive control signal and for controlling the switching means to open when the switch driving means does not receive the drive control signal, the method comprising:

a first step wherein the switching means is controlled to close by application of the drive control signal generated by an equipment to the switch driving means when the battery pack is connected to the charging/discharging device for charging/discharging of the battery cell of the battery pack in a condition with the battery pack mounted on the equipment; and

a second step wherein the switching means is controlled to open by the drive control signal generated by the equipment ceasing to be applied to the switch driving means on release of the connection of the battery pack from the charging/discharging device.