Device and method for estimating battery state
A battery-state estimating device for accurately estimating a battery state of a battery includes: an OCV calculating unit calculating an OCV from the detected values; a charge state estimating unit deriving charge state parameters on the basis of the calculated OCV and an Ah (integrated current value)-OCV map; a map adjusting unit adjusting the Ah-OCV map, wherein the map adjusting unit derives a model equation of the Ah-OCV map on the basis of a first OCV at a first time-point and a second OCV at a second time-point calculated by the OCV calculating unit, and the difference between the integrated current values, wherein the difference has been generated by current flowing through the secondary battery 1 during the first time-point and the second time-point; and adjusts the Ah-OCV map using the model equation.
1. A device for estimating a battery state, comprising:
a current detecting unit configured to detect a charge/discharge current of a battery;
a voltage detecting unit configured to detect an inter-terminal voltage of the battery;
an OCV calculating unit configured to calculate an OCV (Open Circuit Voltage) on a basis of the charge/discharge current detected and the inter-terminal voltage detected of the battery and an internal resistance of the battery at times of charge and discharge;
a charge state estimating unit configured to derive a charge state parameter on a basis of the OCV calculated and a charge state parameter-OCV map;
and a map adjusting unit configured to adjust the charge state parameter-OCV map, wherein
the map adjusting unit is configured to:
derive a model equation for the charge state parameter-OCV map on a basis of a combination of a first OCV calculated by the OCV calculating unit at a first time-point, a second OCV calculated by the OCV calculating unit at a second time-point, and a difference between integrated current values, the difference generated by current flowing through the battery during the first time-point and the second time-point;
adjust the charge state parameter-OCV map using the model equation derived;
include a gradient deriving unit configured to derive a gradient indicating a variation of the OCV with respect to the charge state parameter as a gradient value;
pre-determine a value range which the gradient may take; and
adjust the model equation when the gradient derived by the gradient deriving unit is out of the value range pre-determined.
2. The device for estimating a battery state according to claim 1 , wherein
the map adjusting unit is configured to:
include a storage unit configured to store one or more combinations of the first OCV, the second OCV, and the difference between the integrated current values; and
retrieve the one or more combinations of the first OCV, the second OCV, and the difference between the integrated current values to adjust the charge state parameter-OCV map.
3. The device for estimating a battery state according to claim 2 , wherein the gradient deriving unit changes the value range over which the gradient value can take, in accordance to a deterioration state of the battery.
4. The device for estimating a battery state according to claim 1 ,
further comprising a battery temperature detecting unit configured to detect a temperature of the battery, wherein
the map adjusting unit adjusts the charge state parameter-OCV map for each of the detected temperature of the battery.
5. A method for estimating a battery state, comprising:
a current detecting step of detecting a charge/discharge current of a battery;
a voltage detecting step of detecting an inter-terminal voltage of the battery;
an OCV calculating step of calculating an OCV (Open Circuit Voltage) on a basis of the charge/discharge current detected and the inter-terminal voltage of the battery detected and an internal resistance of the battery at a time of charge and discharge;
a charge state estimating step of deriving a charge state parameter on a basis of the OCV calculated and a charge state parameter-OCV map;
and a map adjusting step of adjusting the charge state parameter-OCV map, wherein
the map adjusting step includes:
deriving a model equation for the charge state parameter-OCV map on a basis of a set of a first OCV calculated by the OCV calculating step at a first time-point, a second OCV calculated by the OCV calculating step at a second time-point, and a difference between integrated current values, the difference generated by current flowing through the battery during the first time-point and the second time-point;
adjusting the charge state parameter-OCV map using the model equation;
deriving a gradient indicating a variation of the OCV with respect to the charge state parameter as a gradient value;
making a pre-determination of a value range which the gradient may take; and
adjusting the model equation when the gradient derived by the deriving step is out of the value range pre-determined.