Secondary battery system and SOC estimation method for secondary battery
AssigneesToyota Jidosha Kabushiki Kaisha, Panasonic Holdings Corporation
InventorsTatsuya Koga, Hiroki Nagai, Mina Nishigaki, Daisuke Nishide, Ryushiro Tokunaga
Life of this patent
Estimating the term…
Abstract
An ECU is configured to execute SOC estimation control for estimating an SOC of a battery. The ECU obtains “first voltage” indicating an OCV of the battery in the SOC estimation control. The ECU controls an engine and a PCU such that the battery is charged with an amount of electric power equal to or larger than a prescribed amount, when the first voltage is within a voltage range where hysteresis occurs. The ECU obtains “second voltage” indicating an OCV of the charged battery, and estimates the SOC of the battery from the second voltage.
Claims10
A secondary battery system comprising:
- a secondary battery where hysteresis occurs, the hysteresis being a phenomenon in which a state of charge (SOC) corresponding to an open circuit voltage (OCV) during charging is different from that during discharging;
- a charger configured to charge the secondary battery;
- and
- a controller configured to control the charger and to estimate an SOC of the secondary battery,
- the controller being configured to:
- obtain a first voltage that is an OCV of the secondary battery;
- in response to a determination that the first voltage is within a voltage range where the hysteresis occurs, perform a hysteresis control process that comprises:
- determining a prescribed amount of electric power to apply to the secondary battery that suppresses an error voltage to a requested magnitude of the error voltage based on a predetermined relation between amounts of change in SOC and error voltage magnitudes, wherein the error voltage represents a difference between the first voltage and an OCV on a charging curve;
- and
- controlling the charger such that the secondary battery is charged with an amount of electric power larger than the prescribed amount of electric power;
- obtain a second voltage that is an OCV of the charged secondary battery;
- and
- estimate the SOC of the secondary battery from the second voltage according to a relation between the SOC and the OCV of the secondary battery.
A state of charge (SOC) estimation method for a secondary battery, for estimating an SOC of the secondary battery where hysteresis occurs, the hysteresis being a phenomenon in which an SOC corresponding to an open circuit voltage (OCV) during charging is different from that during discharging, the SOC estimation method for the secondary battery comprising:
- obtaining a first voltage that is an OCV of the secondary battery;
- in response to a determination that the first voltage is within a voltage range where the hysteresis occurs, perform a hysteresis control process that comprises:
- determining a prescribed amount of electric power to apply to the secondary battery that suppresses an error voltage to a requested magnitude of the error voltage based on a predetermined relation between amounts of change in SOC and error voltage magnitudes, wherein the error voltage represents a difference between the first voltage and an OCV on a charging curve;
- and
- charging the secondary battery with an amount of electric power equal to or larger than the prescribed amount of electric power;
- obtaining a second voltage that is an OCV of the secondary battery after performing the charging;
- and
- estimating the SOC of the secondary battery from the second voltage according to a relation between the SOC and the OCV of the secondary battery.
Dependencies are inferred from the claim text.