Device and method for estimating the inputtable/outputtable power of a secondary battery

• US 7,564,221 B2
• Filed: 11/28/2006
• Issued: 07/21/2009
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Yonezawa, Hideaki, Asai, Hisafumi, Nakamura, Hideo
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US11/605,597
• Publication Number:
  US 20070145953A1
• Time in Patent Office: 966 Days
• Field of Search: 320/107, 320/132, 320/134, 320/136, 320/149, 324/426, 324/427, 324/430, 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 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

An inputtable/outputtable power estimating device and method that can correctly estimate maximum inputtable and/or outputtable power of a secondary battery that can continue for a prescribed period of time. When the secondary battery is continuously charged or discharged for a prescribed period of time, the estimated value of a maximum possible charge and/or discharge current is estimated such that the terminal voltage of the secondary battery reaches a predetermined upper limit voltage or lower limit voltage. The inputtable and/or outputtable power is estimated as the power that can be used to charge the secondary battery or be discharged from it on the basis of the estimated maximum possible current(s) and the respective upper limit voltage or lower limit voltage.

Claims

1. A power estimating device for estimating a power associated with a secondary battery, the power comprising at least one of an inputtable power to charge the battery and an outputtable power discharged from the battery, the device comprising:

a controller including;

a maximum possible current estimating part operable to estimate a maximum possible current through the secondary battery when the terminal voltage of the secondary battery reaches one of an upper limit voltage when the secondary battery is charged continuously for a first period of time and a lower limit voltage when the secondary battery is discharged continuously for a second period of time; and

a power estimating part operable to estimate the power based on the maximum possible current and the one of the upper limit voltage and the lower limit voltage.

2. The device according to claim 1 wherein the maximum possible current estimating part is further operable to estimate at least one of a maximum possible charge current based on a correlation between a first current of the secondary battery after a prescribed charging period and an internal resistance of the secondary battery and the upper limit voltage, and a maximum possible discharge current based on a correlation between a second current of the secondary battery after a prescribed discharge period and the internal resistance of the secondary battery and the lower limit voltage.

3. The device according to claim 2, wherein the maximum possible current estimating part is further operable to:

estimate an estimated internal resistance {circumflex over (K)}(k) by means of a batch estimation performed using a digital filtering operation that uses battery parameters including an internal resistance in a battery model formula expressed by;

4. The device according to claim 1 wherein the controller is operable to estimate a variation in an open-circuit voltage of the secondary battery that occurs during one of charging and discharging at a prescribed current for the respective first or second period of time;

and wherein the maximum possible current estimating part is further operable to estimate the maximum possible current based on the variation in the open-circuit voltage and a respective one of the upper limit voltage and the lower limit voltage.

5. The device according to claim 1 wherein the maximum possible current estimating part is further operable to estimate the maximum possible current based on a correlation between a current of the secondary battery after a prescribed period of one of charging and discharging the secondary battery and an internal resistance of the secondary battery, a variation in an open-circuit voltage of the secondary battery that occurs during the one of charging and discharging at a prescribed current for the prescribed period, and a respective one of the upper limit voltage and the lower limit voltage.

6. The device according to claim 5 wherein the maximum possible current estimating part is further operable to:

estimate an estimated internal resistance {circumflex over (K)}(k) by means of a batch estimation performed using a digital filtering operation that uses battery parameters including an internal resistance in a battery model formula expressed by;

7. The device according to claim 1 wherein the maximum possible current estimating part is further operable to estimate a maximum possible charge current Î

_MAX when the terminal voltage reaches the upper limit voltage V_MAX according to;

8. The device according to claim 1 wherein the maximum possible current estimating part is further operable to estimate a maximum possible charge current Î

_MAX when the terminal voltage reaches the upper limit voltage V_MAX according to;

9. The device according to claim 1 wherein the maximum possible current estimating part is further operable to estimate a maximum possible charge current Î

_MAX when the terminal voltage reaches the upper limit voltage V_MAX according to;

10. The device according to claim 1 wherein the power estimating part is further operable to multiply at least one of the upper limit voltage by a maximum possible charge current to calculate the inputtable power, and the lower limit voltage by a maximum possible discharge current to calculate the outputtable power.

11. The device according to claim 1 wherein the maximum possible current is a maximum possible charge current through the secondary battery when the terminal voltage of the secondary battery reaches the prescribed upper limit voltage when the secondary battery is charged continuously for the prescribed period of time;

and wherein the maximum possible current estimating part is further operable to estimate a maximum possible discharge current through the secondary battery when the terminal voltage of the secondary battery reaches the lower limit voltage when the secondary battery is discharged continuously for the prescribed period of time; and

wherein the power estimating part is further operable to estimate the inputtable power based on the maximum possible charge current and the upper limit voltage and to estimate the outputtable power based on the maximum possible discharge current and the lower limit voltage.

12. The device according to claim 1 wherein the power estimating part is further operable to multiply the upper limit voltage by the maximum possible charge current to calculate the inputtable power, and the lower limit voltage by the maximum possible discharge current to calculate the outputtable power.

13. A power estimating device that estimates at least one of a inputtable and a outputtable power of a secondary battery, comprising:

current estimating means for estimating at least one of a maximum possible charge current when a terminal voltage of the secondary battery reaches an upper limit voltage when the secondary battery is continuously charged for a first period of time, and a maximum possible discharge current when the terminal voltage of the secondary battery reaches a lower limit voltage when the secondary battery is continuously discharged for a second period of time; and

power estimating means for estimating at least one of the inputtable power based on the maximum possible charge current, and the upper limit voltage and the outputtable power based on the maximum possible discharge current and the lower limit voltage.

14. The device according to claim 13 wherein the current estimating means is further operable for estimating the one of the maximum possible charge current based on a correlation between a first current of the secondary battery after a prescribed charging period and an internal resistance of the secondary battery and the upper limit voltage, and the maximum possible discharge current based on a correlation between a second current of the secondary battery after a prescribed discharging period and the internal resistance and the lower limit voltage.

15. The device according to claim 13, further comprising:

means for estimating at least one of a first variation in an open-circuit voltage of the secondary battery that occurs during charging at a first prescribed current for a prescribed charge period, and a second variation in the open-circuit voltage that occurs during discharging at a second prescribed current for a prescribed discharge period; and

wherein the current estimating means is further operable to estimate the one of the maximum possible charge current based on the first variation and the upper limit voltage, and the maximum possible discharge current based on the second variation and the lower limit voltage.

16. The device according to claim 13, further comprising:

means for estimating at least one of a first variation in an open-circuit voltage of the secondary battery that occurs during charging at a charging current for a prescribed charge period, and a second variation in the open-circuit voltage that occurs during discharging at a discharging current for a prescribed discharge period;

means for estimating at least one of a first correlation between a first current of the secondary battery after the prescribed charge period and the internal resistance, and a second correlation between a second current of the secondary battery after the prescribed discharge period and the internal resistance; and

wherein the current estimating means is further operable to estimate the one of the maximum possible charge current based on the first correlation, the first variation and the upper limit voltage, and the maximum possible discharge current based on the second correlation, the second variation and the lower limit voltage.

17. A power estimating method for estimating a power of a secondary battery, the power representing at least one of a charge power and a discharge power of a secondary battery, the method comprising:

estimating a maximum possible current when a terminal voltage of the secondary battery reaches an upper limit voltage when the secondary battery is continuously charged for a first period of time, or a lower limit voltage when the secondary battery is continuously discharged for a second period of time, wherein the maximum possible current is one of a maximum possible charging current and a maximum possible discharging current; and

estimating the charge power based on the maximum possible charging current and the upper limit voltage, or the discharge power based on the maximum possible discharging current and the lower limit voltage.

18. The method according to claim 17, further comprising:

estimating a correlation between a current of the secondary battery after a prescribed period of charging or discharging and an internal resistance of the battery; and

wherein estimating the maximum possible current further comprises;

estimating the maximum possible current based on the correlation and on the upper limit voltage when the correlation is based on the prescribed period of charging, or based on the correlation and the lower limit voltage when the correlation is based on the prescribed period of discharging.

19. The method according to claim 17, further comprising:

estimating a variation in an open-circuit voltage of the secondary battery that occurs during charging or discharging at a prescribed current for the respective first period of time or the second period of time; and

wherein estimating the maximum possible current further comprises;

estimating the maximum possible current based on the variation and on the upper limit voltage when the variation is based on the first period of time, or based on the variation and the lower limit voltage when the variation is based on the second period of time.

20. The method according to claim 17, further comprising:

estimating a correlation between a current of the secondary battery after a prescribed period of charging or discharging and an internal resistance of the battery; and

estimating a variation in an open-circuit voltage of the secondary battery that occurs during charging or discharging at a prescribed current for the respective first period of time or the second period of time; and

wherein estimating the maximum possible current further comprises;

estimating the maximum possible current based on the correlation and the variation and the upper limit voltage when the correlation is based on the prescribed period of charging and when the variation is based on the first period of time, or based on the correlation and the variation and the lower limit voltage when the correlation is based on the prescribed period of discharging and the variation is based on the second period of time.