Method of controlling charging and discharging

• US 6,239,580 B1
• Filed: 11/29/1999
• Issued: 05/29/2001
• Est. Priority Date: 12/01/1998
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Toya, Shoichi
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/449,481
• Time in Patent Office: 547 Days
• Field of Search: 320/149, 320/137, 320/116, 320/118, 320/134
• US Class Current: 320/149
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current

Abstract

This method of controlling charging and discharging computes a capacity of a battery array formed from a plurality of series connected rechargeable batteries while charging and discharging the battery array. For each specified time period, charge-discharge capacity is computed and integrated during the specified time period. A first specified time period is followed by a second specified time period, and forced charging or forced discharge is performed during the second specified time period to make the sum of the charge-discharge capacity during the second specified time period plus the charge-discharge capacity during the first specified time period approach zero.

Claims

1. A method of controlling charging and discharging a battery array having a plurality of serially connected rechargeable batteries, said method comprising:

computing and integrating a charge-discharge capacity of the battery array during each of a plurality of time periods, including first and second time periods; and

performing forced charging or forced discharging during the second time period to make a sum of the charge-discharge capacity computed in the first time period and the charge-discharge capacity computed in the second time period approach zero, such that a capacity of the battery array substantially maintains a specified capacity within a range between a battery array full charge capacity and a battery array complete discharge capacity.

2. A method of controlling charging and discharging as recited in claim 1, wherein said computing and integrating of the charge-discharge capacity comprises integrating a charge current or a discharge current.

3. A method of controlling charging and discharging as recited in claim 1, wherein the battery array is a power source for an electric automobile.

4. A method of controlling charging and discharging a battery array having a plurality of serially connected rechargeable batteries, said method comprising:

establishing an upper capacity limit lower than a battery array full charge capacity, a lower capacity limit greater than a battery array complete discharge capacity, and a specified capacity between the upper capacity limit and the lower capacity limit;

computing and integrating a charge-discharge capacity of the battery array during each of a plurality of time periods, including first and second time periods; and

performing forced charging or forced discharging during the second time period to make a sum of the charge-discharge capacity computed in the first time period and the charge-discharge capacity computed in the second time period approach zero; and

revising the charge-discharge capacity when the charge-discharge capacity reaches the upper capacity limit or the lower capacity limit more than a specified number of times, or when a specified time period has elapsed since a last revision.

5. A method of controlling charging and discharging as recited in claim 4, wherein the upper capacity limit is 55% of the battery array full charge capacity.

6. A method of controlling charging and discharging as recited in claim 4, wherein the lower capacity limit is 45% of the battery array full charge capacity.

7. A method of controlling charging and discharging as recited in claim 4, wherein the specified capacity is 50% of the battery array full charge capacity.

8. A method of controlling charging and discharging as recited in claim 4, wherein said revising of the charge-discharge capacity comprises:

charging the battery array until a temperature or a rate of temperature rise of at least one of the plurality of rechargeable batteries reaches a specified value; and

after said charging, writing a capacity tolerance limit lower than the battery array full charge capacity and greater than the upper capacity limit as the charge-discharge capacity.

9. A method of controlling charging and discharging as recited in claim 8, wherein the capacity tolerance limit is 95% of the battery array full charge capacity.

10. A method of controlling charging and discharging as recited in claim 8, further comprising after said revising of the charge-discharge capacity, prohibiting charging of the battery array until the charge-discharge capacity reaches the specified capacity.

11. A method of controlling charging and discharging as recited in claim 4, wherein said revising of the charge-discharge capacity comprises:

charging the battery array until a voltage of at least one of the plurality of rechargeable batteries becomes greater than or equal to a specified voltage; and

after said charging, writing a capacity tolerance limit lower than the battery array full charge capacity and greater than the upper capacity limit as the charge-discharge capacity.

12. A method of controlling charging and discharging as recited in claim 11, wherein the capacity tolerance limit is 95% of the battery array full charge capacity.

13. A method of controlling charging and discharging as recited in claim 11, further comprising after said revising of the charge-discharge capacity, prohibiting charging of the battery array until the charge-discharge capacity reaches the specified capacity.