Battery pack capacity control system

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

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.

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.

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.