System for calculating remaining capacity of energy storage device

• US 7,136,762 B2
• Filed: 01/05/2005
• Issued: 11/14/2006
• Est. Priority Date: 01/14/2004
• Status: Expired due to Fees

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Ono, Mikio
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Desta, Elias
• Application Number:
  US11/030,336
• Publication Number:
  US 20050154544A1
• Time in Patent Office: 678 Days
• Field of Search: 702/60, 702 63- 65, 702 79- 80, 702/182, 702/189, 324/427, 324/428, 324/431, 320/132, 320/136, 361/18, 361/56, 361/79
• US Class Current: 702/63
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

The remaining capacity of a battery obtained by integrating current and that obtained from the estimated open circuit voltage of the battery are weighted with a weight which varies depending on the operating conditions of the battery as needed and the weighted remaining capacities are combined into the final remaining capacity. Thus, the disadvantages of the remaining capacity based on current integration and those of the remaining capacity based on the estimated open circuit voltage cancel each other out and the advantages of the respective remaining capacities can be fully utilized. The uniform calculation accuracy can be ensured and the final remaining capacity can always be obtained with accuracy.

Claims

1. A system for calculating the remaining capacity of an energy storage device, the system comprising:

voltage detection means for detecting the terminal voltage of the energy storage device;

current detection means for detecting the charge and discharge current of the energy storage device;

first calculation means for integrating the charge and discharge current detected by the current detection means to calculate a first remaining capacity;

second calculation means for estimating the open circuit voltage of the energy storage device on the basis of the terminal voltage detected by the voltage detection means, the charge and discharge current detected by the current detection means and the impedance of the equivalent circuit of the energy storage device calculated in correspondence with the moving average of the current and for calculating a second remaining capacity based on the estimated open circuit voltage; and

third calculation means for weighting the first and second remaining capacities with a weight that is set based on the moving average of the current and combining the weighted remaining capacities into the remaining capacity of the energy storage device.

2. The system according to claim 1, wherein the third calculation means determines the weight on the basis of the moving average of the charge and discharge current detected by the current detection means.

3. The system according to claim 1, wherein the second calculation means obtains the second remaining capacity on the basis of the open circuit voltage of the energy storage device and the temperature thereof in accordance with the electrochemical relationship there between in the energy storage device.

4. The system according to claim 2, wherein the second calculation means obtains the second remaining capacity on the basis of the open circuit voltage of the energy storage device and the temperature thereof in accordance with the electrochemical relationship there between in the energy storage device.

5. The system according to claim 1, wherein the second calculation means calculates the impedance on the basis of the moving average of the charge and discharge current detected by the current detection means and the temperature of the energy storage device.

6. The system according to claim 2, wherein the second calculation means calculates the impedance on the basis of the moving average of the charge and discharge current detected by the current detection means and the temperature of the energy storage device.

7. The system according to claim 3, wherein the second calculation means calculates the impedance on the basis of the moving average of the charge and discharge current detected by the current detection means and the temperature of the energy storage device.

8. The system according to claim 4, wherein the second calculation means calculates the impedance on the basis of the moving average of the charge and discharge current detected by the current detection means and the temperature of the energy storage device.

9. The system according to claim 1, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

10. The system according to claim 2, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

11. The system according to claim 3, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

12. The system according to claim 4, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

13. The system according to claim 5, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

14. The system according to claim 6, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

15. The system according to claim 7, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.

16. The system according to claim 8, wherein the first calculation means integrates the charge and discharge current using the remaining capacity, combined by the third calculation means, as a base value to obtain the first remaining capacity.