Battery pack capacity control system

• US 20060152195A1
• Filed: 07/26/2004
• Published: 07/13/2006
• Est. Priority Date: 07/29/2003
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Ishishita, Teruo
• Granted Patent: US 7,439,710 B2
• Time in Patent Office: Days
• 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: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

If the capacity variation is greater than a pre-stored value, the SOC converted from Qmin sometimes cannot recover to a control center value. In such a case, inconveniences including the continuation of an event where the HVECU cannot output a command to stop the charging are prevented by computing an apparatus SOC and reporting the SOC to the HVECU. The apparent SOC is computed by increasing the value of SOC in accordance with the magnitude of the capacity variation. The thus-computed apparent SOC is reported to the HVECU by the battery ECU, so that it can be determined that the control center value has been exceeded. Thus, it becomes possible to provide battery control apparatus, method and program and a battery control system for a battery pack which are capable of controlling the charging/discharging of the battery pack with an improved accuracy despite capacity variation.

Claims

1-21. -21. (canceled)

22. A battery pack charge/discharge control apparatus for controlling charge/discharge of a battery pack that is formed by combining a plurality of unit batteries of a secondary battery type, comprising:

charge/discharge restriction device for restricting the charge/discharge based on at least one of a capacity upper limit value and a capacity lower limit value of the unit batteries constituting the battery pack;

remaining capacity detection device for detecting remaining capacities of unit batteries constituting the battery pack;

control value computation device for computing a control state-of-charge value based on at least one of a minimum value and a maximum value of the detected remaining capacities;

capacity difference computation device for computing, as a capacity difference, a remaining capacity difference between the remaining capacity of a first unit battery and the remaining capacity of a second unit battery among the unit batteries whose remaining capacities have been detected, the remaining capacity of the second unit battery being less than the remaining capacity of the first unit battery;

storage device for storing a correlation between the capacity difference and an apparent state-of-charge value that is different from the control state-of-charge value;

apparent state-of-charge value computation device for computing an apparent state-of-charge value with reference to the correlation based on the capacity difference; and

apparent state-of-charge value adoption device for adopting the apparent state-of-charge value if the capacity difference is at least a predetermined capacity difference that is stored beforehand

23. The battery pack charge/discharge control apparatus according to claim 22, wherein the capacity difference computation device includes maximum remaining capacity detection device for detecting a unit battery having a maximum remaining capacity in the battery pack, and minimum remaining capacity detection device for detecting a unit battery having a minimum remaining capacity in the battery pack, and computes a remaining capacity difference between the maximum remaining capacity and the minimum remaining capacity as a capacity difference.

24. The battery pack charge/discharge control apparatus according to claim 22, further comprising control state-of-charge value adoption device for adopting the minimum remaining capacity of the unit batteries constituting the battery pack or a percentage of the minimum remaining capacity to a fully charged capacity value, as a control state-of-charge value for controlling the battery pack, if the capacity difference is less than a pre-stored predetermined capacity difference.

25. The battery pack charge/discharge control apparatus according to claim 22, wherein if the capacity difference is at least a pre-stored predetermined capacity difference maximum value, the predetermined capacity difference maximum value is adopted instead of the capacity difference.

26. The battery pack charge/discharge control apparatus according to claim 22, wherein the correlation is expressed by Mathematical Expression (1):

27. The battery pack charge/discharge control apparatus according to claim 26, wherein if in Mathematical Expression (1), the denominator on the right-hand side which is presented as Mathematical Expression (2) is at most a predetermined zero-cross reduction preventative value, the zero-cross reduction preventative value is adopted in place of the denominator expressed by Mathematical Expression (2):

Qhigh Qlow Qd 

 

(2)

28. The battery pack charge/discharge control apparatus according to claim 26, wherein if in Mathematical Expression (1), SOC becomes greater than a maximum guard value, the maximum guard value is adopted in place of the term on the left-hand side in Mathematical Expression (1).

29. The battery pack charge/discharge control apparatus according to claim 26, wherein if in Mathematical Expression (1), SOC becomes less than a minimum guard value, the minimum guard value is adopted in place of the term on the left-hand side in Mathematical Expression (1).

30. A battery pack charge/discharge control apparatus for controlling charge/discharge of a battery pack that is formed by combining a plurality of unit batteries of a secondary battery type, comprising:

remaining capacity detector that detects remaining capacities of unit batteries constituting the battery pack; and

controller that restricts the charge/discharge based on at least one of a capacity upper limit value and a capacity lower limit value of the unit batteries constituting the battery pack,

computes a control state-of-charge value based on at least one of a minimum value and a maximum value of the detected remaining capacities,

computes as a capacity difference, a remaining capacity difference between the remaining capacity of a first unit battery and the remaining capacity of a second unit battery among the unit batteries whose remaining capacities have been detected, the remaining capacity of the second unit battery being less than the remaining capacity of the first unit battery,

stores a correlation between the capacity difference and an apparent state-of-charge value that is different from the control state-of-charge value,

computes an apparent state-of-charge value with reference to the correlation based on the capacity difference, and the controller

adopts the apparent state-of-charge value if the capacity difference is at least a predetermined capacity difference that is stored beforehand.

31. The battery pack charge/discharge control apparatus according to claim 30, wherein the controller detects a unit battery having a maximum remaining capacity in the battery pack and a unit battery having a minimum remaining capacity in the battery pack, and computes a remaining capacity difference between the maximum remaining capacity and the minimum remaining capacity as a capacity difference.

32. The battery pack charge/discharge control apparatus according to claim 30, wherein the controller adopts the minimum remaining capacity of the unit batteries constituting the battery pack or a percentage of the minimum remaining capacity to a fully charged capacity value, as a control state-of-charge value for controlling the battery pack, if the capacity difference is less than a pre-stored predetermined capacity difference.

33. The battery pack charge/discharge control apparatus according to claims 30, wherein if the capacity difference is at least a pre-stored predetermined capacity difference maximum value, the predetermined capacity difference maximum value is adopted instead of the capacity difference.

34. The battery pack charge/discharge control apparatus according to claim 30, wherein the correlation is expressed by Mathematical Expression (1):

35. The battery pack charge/discharge control apparatus according to claim 34, wherein if in Mathematical Expression (1), the denominator on the right-hand side which is presented as Mathematical Expression (2) is at most a predetermined zero-cross reduction preventative value (Q3), the zero-cross reduction preventative value is adopted in place of the denominator expressed by Mathematical Expression (2):

Qhigh Qlow Qd 

 

(2)

36. The battery pack charge/discharge control apparatus according to claim 34, wherein if in Mathematical Expression (1), SOC becomes greater than a maximum guard value, the maximum guard value is adopted in place of the term on the left-hand side in Mathematical Expression (1).

37. The battery pack charge/discharge control apparatus according to claim 34, wherein if in Mathematical Expression (1), SOC becomes less than a minimum guard value, the minimum guard value is adopted in place of the term on the left-hand side in Mathematical Expression (1).

38. A battery pack charge/discharge control method for controlling charge/discharge of a battery pack that is formed by combining a plurality of unit batteries of a secondary battery type, comprising the following steps of:

restricting the charge/discharge based on at least one of a capacity upper limit value and a capacity lower limit value of the unit batteries constituting the battery pack;

detecting remaining capacities of unit batteries constituting the battery pack;

computing a control state-of-charge value based on at least one of a minimum value and a maximum value of the detected remaining capacities;

computing, as a capacity difference, a remaining capacity difference between the remaining capacity of a first unit battery and the remaining capacity of a second unit battery among the unit batteries whose remaining capacities have been detected, the remaining capacity of the second unit battery being less than the remaining capacity of the first unit battery;

storing a correlation between the capacity difference and an apparent state-of-charge value that is a state-of-charge value different from the control state-of-charge value;

computing an apparent state-of-charge value with reference to the correlation based on the capacity difference; and

adopting an apparent state-of-charge value if the capacity difference is at least a predetermined capacity difference that is stored beforehand.

39. A battery pack charge/discharge control program that is read into a computer so as to control charge/discharge of a battery pack that is formed by combining a plurality of unit batteries of a secondary battery type, comprising:

restricting the charge/discharge based on at least one of a capacity upper limit value and a capacity lower limit value of the unit batteries constituting the battery pack;

detecting remaining capacities of unit batteries constituting the battery pack;

computing a control state-of-charge value based on at least one of a minimum value and a maximum value of the detected remaining capacities;

computing, as a capacity difference, a remaining capacity difference between the remaining capacity of a first unit battery and the remaining capacity of a second unit battery among the unit batteries whose remaining capacities have been detected, the remaining capacity of the second unit battery being less than the remaining capacity of the first unit battery; and

computing an apparent state-of-charge value that is different from the control state-of-charge value, with reference to a correlation between the capacity difference and the apparent state-of-charge value.