Method and apparatus for controlling residual battery capacity of secondary battery

• US 6,646,421 B2
• Filed: 06/05/2002
• Issued: 11/11/2003
• Est. Priority Date: 06/07/2001
• 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: Kimura, Tadao, Toyota, Masayoshi
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/163,807
• Publication Number:
  US 20020196026A1
• Time in Patent Office: 524 Days
• Field of Search: 320/132, 320/149, 324/426, 324/427, 324/431, 324/432, 324/433
• US Class Current: 320/132
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3828 using current integration

Abstract

A method for controlling a residual battery capacity of a secondary battery, by which the precision of the energy management of the system can be improved substantially, is provided. A current flowing through the battery is detected and the detected current is multiplied by a predetermined charge efficiency so that an operation on a residual battery capacity is performed at least by current integration (S201), an output voltage from the battery is detected and an average of the output voltages detected for a predetermined time period is calculated (S202), an average of the residual battery capacities obtained by the operation for a predetermined time period is calculated (S203), a reference voltage corresponding to the calculated average of residual battery capacities is referred to (S204), the reference voltage and the average voltage is compared (S205), and the predetermined charge efficiency is set variably based on a result of the comparison (S206).

Claims

1. A method for controlling a residual battery capacity of a secondary battery, comprising:

detecting a current flowing through the secondary battery to perform an operation on a residual battery capacity by multiplying the detected current by a predetermined charge efficiency;

detecting an output voltage from the secondary battery to calculate an average voltage value of output voltages detected for a predetermined period of time;

calculating an average value of residual battery capacities obtained by the operation for the predetermined period of time;

referring to a reference voltage value of the secondary battery corresponding to the calculated average value of residual battery capacities;

comparing the reference voltage value and the average voltage value; and

setting the predetermined charge efficiency variably, based on a result of the comparison.

2. The method for controlling a residual battery capacity of a secondary battery according to claim 1,

wherein an average value of no-load voltages of the secondary battery is calculated for the predetermined period of time, and the calculated average value is set as the average voltage value.

3. The method for controlling a residual battery capacity of a secondary battery according to claim 1,

wherein as the result of the comparison, if the average voltage value is higher than the reference voltage value, then the predetermined charge efficiency is increased,

if the average voltage value is lower than the reference voltage value, then the predetermined charge efficiency is decreased, and

if the average voltage value is equal to the reference voltage value, then the predetermined charge efficiency is not changed.

4. The method for controlling a residual battery capacity of a secondary battery according to claim 3,

wherein the increase or the decrease in the predetermined charge efficiency is conducted by adding, subtracting, or multiplying a constant with respect to the predetermined charge efficiency.

5. The method for controlling a residual battery capacity of a secondary battery according to claim 3,

wherein the increase or the decrease in the predetermined charge efficiency is conducted by adding, subtracting, or multiplying a value corresponding to a difference between the average voltage value and the reference voltage value with respect to the predetermined charge efficiency.

6. The method for controlling a residual battery capacity of a secondary battery according to claim 1,

wherein a temperature of the secondary battery is detected and the predetermined charge efficiency is determined based on the detected temperature and a currently calculated residual battery capacity.

7. The method for controlling a residual battery capacity of a secondary battery according to claim 1,

wherein a temperature of the secondary battery is detected and the reference voltage value is determined based on the detected temperature and the average value of residual battery capacities.

8. A residual battery capacity control apparatus for a secondary battery, comprising:

a current detection unit that detects a current flowing through the secondary battery;

a residual battery capacity operation unit that performs an operation on a residual battery capacity by multiplying a current signal from the current detection unit by a predetermined charge efficiency;

a voltage detection unit that detects an output voltage from the secondary battery;

an average voltage calculation unit that calculates an average voltage value of voltage signals output from the voltage detection unit for a predetermined period of time;

an average residual battery capacity calculation unit that calculates an average value of residual battery capacities obtained by the operation by the residual battery capacity operation unit for a predetermined period of time;

a reference voltage storage unit that stores a reference voltage value of the secondary battery, corresponding to the average value of residual battery capacities obtained from the average residual battery capacity calculation unit;

a comparison unit that compares the average voltage value obtained from the average voltage calculation unit and the reference voltage value obtained from the reference voltage storage unit; and

a charge efficiency setting unit that sets the predetermined charge efficiency variably with respect to the residual battery capacity operation unit, based on a result of the comparison by the comparison unit.

9. The residual battery capacity control apparatus for a secondary battery according to claim 8,

wherein the average voltage calculation unit calculates an average value of no-load voltage signals.

10. The residual battery capacity control apparatus for a secondary battery according to claim 8,

wherein, as the result of the comparison by the comparison unit, if the average voltage value is higher than the reference voltage value, then the charge efficiency setting unit increases the predetermined charge efficiency,

if the average voltage value is lower than the reference voltage value, then the charge efficiency setting unit decreases the predetermined charge efficiency, and

if the average voltage value is equal to the reference voltage value, then the charge efficiency setting unit does not change the predetermined charge efficiency.

11. The residual battery capacity control apparatus for a secondary battery according to claim 10,

wherein the charge efficiency setting unit increases or decreases the predetermined charge efficiency by adding, subtracting, or multiplying a constant with respect to the predetermined charge efficiency.

12. The residual battery capacity control apparatus for a secondary battery according to claim 10,

wherein the charge efficiency setting unit increases or decreases the predetermined charge efficiency by adding, subtracting, or multiplying a value corresponding to a difference between the average voltage value and the reference voltage value with respect to the predetermined charge efficiency.

13. The residual battery capacity control apparatus for a secondary battery according to claim 8, further comprising:

a temperature detection unit that detects a temperature in the secondary battery,

wherein the charge efficiency setting unit comprises a charge efficiency storage unit that stores a charge efficiency corresponding to a temperature signal from the temperature detection unit and a current residual battery capacity from the residual battery capacity operation unit.

14. The residual battery capacity control apparatus for a secondary battery according to claim 8, further comprising:

a temperature detection unit that detects a temperature in the secondary battery,

wherein the reference voltage storage unit stores the reference voltage value corresponding to a temperature signal from the temperature detection unit and an average value of residual battery capacities from the average residual battery capacity calculation unit.

15. A residual battery capacity control apparatus for a secondary battery, comprising:

a battery pack composed of a combination of a plurality of electric cells, each of which is a secondary battery, and used in a middle charged state,

a current detection unit that detects a current flowing through the battery pack;

a residual battery capacity operation unit that performs an operation on a residual battery capacity by multiplying a current signal from the current detection unit by a predetermined charge efficiency;

a voltage detection unit that detects an output voltage from the battery pack;

an average voltage calculation unit that calculates an average voltage value of voltage signals output from the voltage detection unit for a predetermined period of time;

an average residual battery capacity calculation unit that calculates an average value of residual battery capacities obtained by the operation by the residual battery capacity operation unit for a predetermined period of time;

a reference voltage storage unit that stores a reference voltage value of each secondary battery, corresponding to the average value of residual battery capacities obtained from the average residual battery capacity calculation unit;

a comparison unit that compares the average voltage value obtained from the average voltage calculation unit and the reference voltage value obtained from the reference voltage storage unit; and

a charge efficiency setting unit that sets the predetermined charge efficiency variably with respect to the residual battery capacity operation unit, based on a result of the comparison by the comparison unit.

16. The residual battery capacity control apparatus for a secondary battery according to claim 15,

wherein the average voltage calculation unit calculates an average value of no-load voltage signals.

17. A residual battery capacity control apparatus for a secondary battery according to claim 15,

wherein, as the result of the comparison by the comparison unit, if the average voltage value is higher than the reference voltage value, then the charge efficiency setting unit increases the predetermined charge efficiency,

if the average voltage value is lower than the reference voltage value, then the charge efficiency setting unit decreases the predetermined charge efficiency, and

if the average voltage value is equal to the reference voltage value, then the charge efficiency setting unit does not change the predetermined charge efficiency.

18. A residual battery capacity control apparatus for a secondary battery according to claim 17,

wherein the charge efficiency setting unit increases or decreases the predetermined charge efficiency by adding, subtracting, or multiplying a constant with respect to the predetermined charge efficiency.

19. A residual battery capacity control apparatus for a secondary battery according to claim 17,

wherein the charge efficiency setting unit increases or decreases the predetermined charge efficiency by adding, subtracting, or multiplying a value corresponding to a difference between the average voltage value and the reference voltage value with respect to the predetermined charge efficiency.

20. A residual battery capacity control apparatus for a secondary battery according to claim 15, further comprising:

a temperature detection unit that detects a temperature in the secondary battery,

wherein the charge efficiency setting unit comprises a charge efficiency storage unit that stores a charge efficiency corresponding to a temperature signal from the temperature detection unit and a current residual battery capacity from the residual battery capacity operation unit.

21. A residual battery capacity control apparatus for a secondary battery according to claim 15, further comprising:

a temperature detection unit that detects a temperature in the secondary battery,

wherein the reference voltage storage unit stores the reference voltage value corresponding to a temperature signal from the temperature detection unit and an average value of residual battery capacities from the average residual battery capacity calculation unit.