Charging/discharging control device and method for canceling memory effect in secondary battery

• US 6,465,988 B2
• Filed: 04/20/2001
• Issued: 10/15/2002
• Est. Priority Date: 04/28/2000
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ito, Shinichiro, Bito, Seiji, Kimura, Tadao, Murakami, Yusai
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/839,878
• Publication Number:
  US 20010035742A1
• Time in Patent Office: 543 Days
• Field of Search: 320/131, 320/134, 320/136, 320/152, 320/157, 320/158, 320/162, 320/163
• US Class Current: 320/131
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor

Abstract

A device and a method are provided in which memory effects can be cancelled by controlling charging and discharging of a secondary battery during driving of a vehicle. When a memory effect determinator determines that the discharging memory effect has occurred, based on at least one of the following determinations: whether a time of charging/discharging of a secondary battery has reached a predetermined time; whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and whether a voltage per cell has reached a voltage V1 at a lower-limit state of charge in a range of capacity actually used, a discharging controller discharges the secondary battery until the voltage per cell reaches a voltage V3 that is higher than 1.0 V and is lower than the voltage V1 at the lower-limit state of charge.

Claims

1. A charging/discharging control device, comprising:

a secondary battery formed of a battery assembly with a plurality of cells combined with one another;

a memory effect determinator for determining whether a discharging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of the secondary battery has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V1 at a lower-limit state of charge in a range of capacity actually used; and

a discharging controller for discharging the secondary battery until the voltage per cell reaches a voltage V3 that is higher than 1.0 V and is lower than the voltage V1 at the lower-limit state of charge when the memory effect determinator determines that the discharging memory effect has occurred.

2. The charging/discharging control device according to claim 1, further comprising a charging controller for charging the secondary battery until the voltage per cell reaches a voltage V4 that is higher than a voltage V2 at an upper-limit state of charge in the range of capacity actually used after completion of the discharging of the secondary battery by the discharging controller based on the determination by the memory effect determinator that the discharging memory effect has occurred.

3. The charging/discharging control device according to claim 2, wherein discharging and charging of the secondary battery are repeated in this order at least once, wherein the discharging is carried out by the discharging controller until the voltage per cell reaches the voltage V3 from the voltage V4, and the charging is carried out by the charging controller until the voltage per cell reaches the voltage V4 from the voltage V3.

4. The charging/discharging control device according to claim 1, further comprising a charging level corrector for correcting a charging level at the lower-limit state of charge based on a discharging amount when the discharging is carried out until the voltage per cell reaches the voltage V3 from the voltage V1 by the discharging controller.

5. A charging/discharging control device, comprising:

a secondary battery formed of a battery assembly with a plurality of cells combined with one another;

a memory effect determinator for determining whether a discharging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of the secondary battery has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V1 at a lower-limit state of charge in a range of capacity actually used; and

a discharging controller for discharging the secondary battery for a predetermined amount from the lower-limit state of charge when the memory effect determinator determines that the discharging memory effect has occurred.

6. The charging/discharging control device according to claim 5, further comprising a charging controller for charging the secondary battery until the voltage per cell reaches a voltage V4 that is higher than a voltage V2 at an upper-limit state of charge in the range of capacity actually used after completion of the discharging of the secondary battery by the discharging controller based on the determination by the memory effect determinator that the discharging memory effect has occurred.

7. The charging/discharging control device according to claim 6, wherein discharging and charging of the secondary battery are repeated in this order at least once, wherein the discharging is carried out by the discharging controller until the voltage per cell reaches a voltage V3 that is lower than the voltage V1 at the lower-limit state of charge from the voltage V4, and the charging is carried out by the charging controller until the voltage per cell reaches the voltage V4 from the voltage V3.

8. The charging/discharging control device according to claim 5, further comprising a charging level corrector for correcting a charging level at the lower-limit state of charge based on the voltage per cell after the secondary battery is discharged for the predetermined amount from the lower-limit state of charge by the discharging controller.

9. A charging/discharging control device, comprising:

a secondary battery formed of a battery assembly with a plurality of cells combined with one another;

a memory effect determinator for determining whether a charging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of the secondary battery has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V2 at an upper-limit state of charge in a range of capacity actually used; and

a charging controller for charging the secondary battery until the voltage per cell reaches a voltage V4 that is higher than the voltage V2 at the upper-limit state of charge when the memory effect determinator determines that the charging memory effect has occurred.

10. The charging/discharging control device according to claim 9, further comprising a discharging controller for discharging the secondary battery until the voltage per cell reaches a voltage V3 that is lower than a voltage V1 at a lower-limit state of charge in the range of capacity actually used after completion of the charging of the secondary battery by the charging controller based on the determination by the memory effect determinator that the charging memory effect has occurred.

11. The charging/discharging control device according to claim 10, wherein charging and discharging of the secondary battery are repeated in this order at least once, wherein the charging is carried out by the charging controller until the voltage per cell reaches the voltage V4 from the voltage V3, and the discharging is carried out by the discharging controller until the voltage per cell reaches the voltage V3 from the voltage V4.

12. A charging/discharging control device, comprising:

a secondary battery formed of a battery assembly with a plurality of cells combined with one another;

a memory effect determinator for determining whether a charging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of the secondary battery has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V2 at an upper-limit state of charge in a range of capacity actually used; and

a charging controller for charging the secondary battery for a predetermined amount from the upper-limit state of charge when the memory effect determinator determines that the charging memory effect has occurred.

13. The charging/discharging control device according to claim 12, further comprising a discharging controller for discharging the secondary battery until the voltage per cell reaches a voltage V3 that is lower than a voltage V1 at a lower-limit state of charge in the range of capacity actually used after completion of the charging of the secondary battery by the charging controller based on the determination by the memory effect determinator that the charging memory effect has occurred.

14. The charging/discharging control device according to claim 13, wherein charging and discharging of the secondary battery are repeated in this order at least once, wherein the charging is carried out by the charging controller until the voltage per cell reaches a voltage V4 that is higher than the voltage V2 at the upper-limit state of charge from the voltage V3, and the discharging is carried out by the discharging controller until the voltage per cell reaches the voltage V3 from the voltage V4.

15. A charging/discharging control method, comprising:

determining whether a discharging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of a secondary battery formed of a battery assembly with a plurality of cells combined with one another has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V1 at a lower-limit state of charge in a range of capacity actually used; and

discharging the secondary battery until the voltage per cell reaches a voltage V3 that is higher than 1.0 V and is lower than the voltage V1 at the lower-limit state of charge when it is determined that the discharging memory effect has occurred.

16. The charging/discharging control method according to claim 15, further comprising charging the secondary battery until the voltage per cell reaches a voltage V4 that is higher than a voltage V2 at an upper-limit state of charge in the range of capacity actually used after completion of the discharging of the secondary battery based on the determination that the discharging memory effect has occurred.

17. The charging/discharging control method according to claim 16, wherein discharging and charging of the secondary battery are repeated in this order at least once, wherein the discharging is carried out until the voltage per cell reaches the voltage V3 from the voltage V4, and the charging is carried out until the voltage per cell reaches the voltage V4 from the voltage V3.

18. The charging/discharging control method according to claim 15, further comprising correcting a charging level at the lower-limit state of charge based on a discharging amount when the discharging is carried out until the voltage per cell reaches the voltage V3 from the voltage V1.

19. A charging/discharging control method, comprising:

determining whether a discharging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of a secondary battery formed of a battery assembly with a plurality of cells combined with one another has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V1 at a lower-limit state of charge in a range of capacity actually used; and

discharging the secondary battery for a predetermined amount from the lower-limit state of charge when it is determined that the discharging memory effect has occurred.

20. The charging/discharging control method according to claim 19, further comprising charging the secondary battery until the voltage per cell reaches a voltage V4 that is higher than a voltage V2 at an upper-limit state of charge in the range of capacity actually used after completion of the discharging of the secondary battery based on the determination that the discharging memory effect has occurred.

21. The charging/discharging control method according to claim 20, wherein discharging and charging of the secondary battery are repeated in this order at least once, wherein the discharging is carried out until the voltage per cell reaches a voltage V3 that is lower than the voltage V1 at the lower-limit state of charge from the voltage V4, and the charging is carried out until the voltage per cell reaches the voltage V4 from the voltage V3.

22. The charging/discharging control device according to claim 19, further comprising correcting a charging level at the lower-limit state of charge based on the voltage per cell after the secondary battery is discharged for the predetermined amount from the lower-limit state of charge.

23. A charging/discharging control method, comprising:

determining whether a charging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of a secondary battery formed of a battery assembly with a plurality of cells combined with one another has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V2 at an upper-limit state of charge in a range of capacity actually used; and

charging the secondary battery until the voltage per cell reaches a voltage V4 that is higher than the voltage V2 at the upper-limit state of charge when it is determined that the charging memory effect has occurred.

24. The charging/discharging control method according to claim 23, further comprising discharging the secondary battery until the voltage per cell reaches a voltage V3 that is lower than a voltage V1 at a lower-limit state of charge in the range of capacity actually used after completion of the charging of the secondary battery based on the determination that the charging memory effect has occurred.

25. The charging/discharging control method according to claim 24, wherein charging and discharging of the secondary battery are repeated in this order at least once, wherein the charging is carried out until the voltage per cell reaches the voltage V4 from the voltage V3, and the discharging is carried out until the voltage per cell reaches the voltage V3 from the voltage V4.

26. A charging/discharging control method, comprising:

determining whether a charging memory effect has occurred, based on at least one of the following determinations;

whether a time of charging/discharging of a secondary battery formed of a battery assembly with a plurality of cells combined with one another has reached a predetermined time;

whether a charging/discharging amount in the secondary battery has reached a predetermined amount; and

whether a voltage per cell of the plurality of cells has reached a voltage V2 at an upper-limit state of charge in a range of capacity actually used; and

charging the secondary battery for a predetermined amount from the upper-limit state of charge when it is determined that the charging memory effect has occurred.

27. The charging/discharging control method according to claim 26, further comprising discharging the secondary battery until the voltage per cell reaches a voltage V3 that is lower than a voltage V1 at a lower-limit state of charge in the range of capacity actually used after completion of the charging of the secondary battery based on the determination that the charging memory effect has occurred.

28. The charging/discharging control method according to claim 27, wherein charging and discharging of the secondary battery are repeated in this order at least once, wherein the charging is carried out until the voltage per cell reaches a voltage V4 that is higher than the voltage V2 at the upper-limit state of charge from the voltage V3, and the discharging is carried out until the voltage per cell reaches the voltage V3 from the voltage V4.