Toyota Jidosha Kabushiki Kaisha

Kabushiki Kaisha Toyota Chuo Kenkyusho

Tetsuya Fuchimoto

Yuji Nishi

Nobuyasu Haga

Shuji Tomura

Takeshi Takemoto

Kenji Takahashi

Takaji Umeno

Yasushi Amano

Tetsuya Sugimoto

A degradation determination device includes: a measuring unit measuring an open-circuit voltage characteristic indicating an open-circuit voltage variation with respect to a lithium ion secondary battery capacity variation; and a determining unit determining a degradation state due to wear and precipitation of lithium using a parameter for identifying the open-circuit voltage characteristic that substantially coincides with the measured open-circuit voltage characteristic. The parameter includes single electrode capacity retention rates expressed by the expressions (I) positive electrode capacity retention rate=degraded positive electrode capacity/initial positive electrode capacity and (II) negative electrode capacity retention rate=degraded negative electrode capacity/initial negative electrode capacity, and a battery capacity variation expressed by the expression (III) battery capacity variation=degraded negative electrode capacity&#xd7;shift of a negative electrode composition axis with respect to a positive electrode composition axis.

Degradation determination device and degradation determination method for lithium ion secondary battery

A battery state estimating unit estimates an internal state of a secondary battery in accordance with a battery model equation in every arithmetic cycle, and estimates a charging rate and a battery current based on a result of the estimation. A parameter estimating unit obtains a battery current measured by a sensor as well as the charging rate and the battery current estimated by the battery state estimating unit. The parameter estimating unit estimates a capacity deterioration parameter such that a rate of change in difference (estimation error) between a summed value of an actual current and a summed value of an estimated current with respect to the charging rate is minimized. A result obtained by estimating the capacity deterioration parameter is reflected in the battery model by the battery state estimating unit.

State estimating device for secondary battery

A control apparatus () estimates a status of charge (SOC) by a first estimation method by temporarily changing the SOC of a battery (B) so that the SOC of the battery (B) falls within a first region in the case a period, during which the estimated value of the status of charge of the battery (B) falls within a second region, exceeds a prescribed period.

Control apparatus for vehicle

An estimation apparatus has a controller which estimates an internal reaction of a secondary battery. The controller calculates a voltage drop amount due to an internal resistance of the secondary battery by using an expression (I): where &#x394;V represents the voltage drop amount, R represents a gas constant, T represents a temperature, &#x3b1; represents an oxidation reduction transfer coefficient (&#x3b1;=0.5) of an electrode, &#x3b2; represents a correction coefficient (0&#x3c;&#x3b2;&#x3c;1), F represents the Faraday constant, I represents a discharge current, Rr represents a component of a reaction resistance included in the internal resistance, and Rd represents a component of a direct-current resistance included in the internal resistance.

Estimation apparatus and estimation method

A hybrid vehicle () includes a battery (-), a motor-generator (-) operable to produce driving force using electric power of the battery (-), a charger () operable to charge the battery (-) by means of an external power supply, and an ECU (). The ECU () stores a given parameter used in battery model expressions. The parameter varies according to the status of the battery (-). During running of the hybrid vehicle () and during charging of the battery (-) with the external power supply, the ECU () collects data related to the status of the battery (-), corrects the parameter based on the data, and calculates a value of charging rate (SOC) of the battery (-). The ECU () controls charge/discharge of the battery (-), based on the calculated SOC value.

Control system of vehicle

A battery state estimating unit estimates an internal state of a secondary battery according to a battery model equation in every arithmetic cycle, and calculates an SOC based on a result of the estimation. A parameter characteristic map stores a characteristic map based on a result of actual measurement performed in an initial state (in a new state) on a parameter diffusion coefficient and a DC resistance in the battery model equation. The parameter change rate estimating unit estimates a DC resistance change rate represented by a ratio of a present DC resistance with respect to a new-state parameter value by parameter identification based on the battery model equation, using battery data measured by sensors as well as the new-state parameter value of the DC resistance corresponding to the present battery state and read from the parameter characteristic map.

State estimating device of secondary battery

A diffusion estimation unit follows a diffusion equation in an active material that is represented by a polar coordinate to estimate a distribution in concentration of lithium in the active material. An open circuit voltage estimation unit obtains an open circuit voltage in accordance with a local SOC(&#x3b8;) based on a concentration of lithium obtained at an interface of the active material as estimated by the diffusion estimation unit. A current estimation unit uses a battery's voltage measured by a voltage sensor, the estimated open circuit voltage, and a parameter value that is set for the battery by a battery parameter value setting unit, and follows a voltage-current relationship model expression simplified from an electrochemical reaction expression to estimate the battery's current density. A boundary condition setting unit sequentially sets a boundary condition for the diffusion equation of the diffusion estimation unit for the active material's interface, as based on the battery's estimated current density. Thus a battery model that allows an internal state to be estimated based on an electrochemical reaction dynamically and can also achieve an alleviated operating load can be used to estimate a state of a secondary battery.

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Nagoya, Japan

Tetsuya Fuchimoto