JP5527001B2 - Charge control method and charge control device for secondary battery - Google Patents

Description

  The present invention relates to a secondary battery charge control method and a charge control device technology.

  An electric vehicle (including a hybrid vehicle) equipped with an electric motor drives the electric motor with electric power stored in a secondary battery. There is regenerative braking as a characteristic function of such an electric vehicle. In regenerative braking, the motor is made to function as a generator during vehicle braking, so that the kinetic energy of the vehicle is converted into electric energy and braking is performed. The obtained electrical energy is charged in the secondary battery and reused when accelerating or the like.

  In the secondary battery, gas is generated due to a side reaction of charging as the voltage increases during charging, and the internal pressure of the secondary battery increases. For example, in a nickel metal hydride secondary battery, oxygen gas is mainly generated and the internal pressure rises.

  Conventionally, a technique for protecting a secondary battery by performing charge control as the internal pressure of the secondary battery increases has been disclosed.

  For example, Patent Document 1 discloses that a physical quantity of a secondary battery that affects the internal pressure of the secondary battery and an index (characteristic change index) representing a change in the internal pressure characteristics of the secondary battery calculated based on the physical quantity. A technique for estimating the internal pressure of a secondary battery and performing charge control of the secondary battery based on the estimated internal pressure of the secondary battery is disclosed.

  In addition, for example, in Patent Document 2, vibration generated when the secondary battery is charged is measured, and when the measured value is larger than a predetermined value, it is determined that gas is generated in the secondary battery, A technique for performing control to stop charging of the secondary battery or to lower the charging current value of the secondary battery is disclosed.

  Further, for example, in Patent Document 3, the secondary battery is charged at the first rate with the first current until the internal pressure of the secondary battery rises, and after the internal pressure of the secondary battery starts to rise, A control technique for charging a secondary battery at a second rate lower than the first rate by a second current lower than the first current is disclosed.

JP 2007-53058 A JP 11-329510 A JP 2002-27681 A

  By the way, normally, the gas generated in the secondary battery is absorbed by the electrode on the opposite side of the gas generating electrode. For example, in a nickel metal hydride secondary battery, oxygen gas is generated at the positive electrode, and the generated oxygen gas returns to water by a recombination reaction with hydrogen at the negative electrode, and the internal pressure of the increased secondary battery decreases.

  However, the gas absorption reaction such as the recombination reaction as described above depends on the internal pressure and temperature of the secondary battery, and the reaction is delayed when the temperature of the secondary battery is low. Therefore, in the method of performing the control to limit the charging power of the secondary battery based on the estimated internal pressure of the secondary battery, it is possible to reduce the internal pressure of the increased secondary battery, but the Since it takes time until the internal pressure recovers, control for limiting the charging power of the secondary battery over a long period of time is performed, and the recovery rate of electric energy by regenerative braking may decrease.

  Then, this invention is providing the charge control method and charge control apparatus of a secondary battery which can relieve and suppress the internal pressure rise of a secondary battery.

The charge control method for a secondary battery according to the present invention is based on the voltage between the electrodes of the secondary battery, and the first charge power is set so that the voltage does not rise to the gas generation potential at which gas is generated in the secondary battery. A step of calculating a limit value, a step of calculating a second charge power limit value set so as not to increase to an internal pressure at which the safety valve of the secondary battery operates based on the internal pressure of the secondary battery, and the secondary battery The step of selecting the first charging power limit value or the second charging power limit value according to the internal pressure of the battery and limiting the charging power of the secondary battery, and the current value and charging efficiency of the secondary battery A step of calculating an oxygen gas generation amount in the secondary battery, a step of calculating an oxygen gas decrease amount in the secondary battery based on the temperature of the secondary battery, the oxygen gas generation amount and the oxygen Based on the amount of gas reduction, the oxygen pressure of the secondary battery And calculating the equilibrium hydrogen pressure of the secondary battery based on the temperature of the secondary battery, and the internal pressure of the secondary battery includes the calculated oxygen pressure and the equilibrium hydrogen pressure. It is calculated by the sum of

  In the secondary battery charging control method, in the step of limiting the charging power of the secondary battery, when the internal pressure of the secondary battery exceeds a predetermined value, the first charging power limit value and the It is preferable to select the lower charging power limit value of the second charging power limit values to limit the charging power of the secondary battery.

  In the secondary battery charge control method, the predetermined value is preferably set based on a temperature of the secondary battery.

  In the secondary battery charge control method, the gas generation potential is preferably defined based on a temperature of the secondary battery.

Further, the charge control device for a secondary battery according to the present invention is configured so that the voltage does not rise to a gas generation potential at which gas is generated in the secondary battery based on the voltage between the electrode plates of the secondary battery. Means for calculating a charge power limit value; means for calculating a second charge power limit value set so as not to increase to an internal pressure at which the safety valve of the secondary battery operates based on the internal pressure of the secondary battery; Means for selecting the first charging power limit value or the second charging power limit value in accordance with the internal pressure of the secondary battery and limiting the charging power of the secondary battery; and the current value and charging of the secondary battery Means for calculating an oxygen gas generation amount in the secondary battery based on the efficiency; means for calculating an oxygen gas decrease amount in the secondary battery based on the temperature of the secondary battery; and Means for calculating an oxygen pressure of the secondary battery based on the oxygen gas reduction amount; Means for calculating the equilibrium hydrogen pressure of the secondary battery based on the temperature of the secondary battery, and the internal pressure of the secondary battery is determined by the sum of the calculated oxygen pressure and the equilibrium hydrogen pressure. It is done .

  Further, in the secondary battery charge control device, the means for limiting the charging power of the secondary battery is configured such that when the internal pressure of the secondary battery exceeds a predetermined value, the first charging power limit value and the It is preferable to select the lower charging power limit value of the second charging power limit values to limit the charging power of the secondary battery.

  In the secondary battery charge control apparatus, the predetermined value is preferably set based on a temperature of the secondary battery.

  In the charge control device for the secondary battery, it is preferable that the gas generation potential is defined based on a temperature of the secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the charge control method and charge control apparatus of a secondary battery which can relieve | moderate and suppress the internal pressure rise of a secondary battery can be provided.

It is a schematic diagram which shows an example of a structure of the power unit of the vehicle by which the charging control apparatus of the secondary battery which concerns on this embodiment is mounted. It is a map showing the relationship between the temperature of a secondary battery, and gas generation potential. It is a map showing the relationship between the electrode plate voltage of a secondary battery, and the 1st charging power limit value. It is a map showing the relationship between the internal pressure of a secondary battery, and the 2nd charging power limit value. It is a map showing the relationship between the voltage between electrode plates of a secondary battery and charging efficiency. It is a map showing the relationship between the oxygen pressure in a secondary battery, and the amount of oxygen gas reduction per unit time. It is a map showing the relationship between the temperature of a secondary battery, and the equilibrium hydrogen pressure in a secondary battery. It is a flowchart which shows an example of operation | movement of the charge control apparatus of the secondary battery which concerns on this embodiment. It is a flowchart which shows an example of the estimation method of the internal pressure of the secondary battery which concerns on this embodiment.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic diagram illustrating an example of a configuration of a power unit of a vehicle in which the secondary battery charge control device according to the present embodiment is mounted. The charge control device according to the present embodiment can be applied to a vehicle such as an electric vehicle (including a hybrid vehicle) on which the secondary battery 14 is mounted. A vehicle power unit 1 shown in FIG. 1 includes a motor generator 10, an inverter 12 connected to the motor generator 10, a secondary battery 14 connected to the inverter 12, and a charge control device for controlling the charging power of the secondary battery 14. ECU18 which functions as. The ECU 18 is electrically connected to the motor generator 10, the inverter 12, and the secondary battery 14.

  The motor generator 10 generates a driving force by the electric power supplied from the secondary battery 14 or the like. Further, when the vehicle is under regenerative control, it operates as a generator, converts the kinetic energy of the vehicle into electrical energy, and charges the secondary battery 14.

  Inverter 12 converts a direct current supplied from secondary battery 14 or the like into an alternating current, and drives motor generator 10. Further, the alternating current generated by the motor generator 10 is converted into a direct current, and the secondary battery 14 is charged.

  Usually, the secondary battery 14 is configured as a battery module in which a plurality of cells are connected in series in order to ensure a certain voltage. The secondary battery 14 that is charge-controlled by the charge control device of the present embodiment can be applied to any type of secondary battery 14, but a nickel-hydrogen secondary battery is suitable. When a nickel hydride secondary battery is charged at a high voltage, temperature, etc., gas is generated due to a side reaction different from the charging reaction, and the charging efficiency is lowered. However, in the charge control method of the present embodiment, as will be described later, the charging power is limited so that the voltage between the electrode plates of the secondary battery 14 does not increase to the gas generation potential, so the increase in the internal pressure of the secondary battery 14 is mitigated. -It can suppress and can charge the secondary battery 14 efficiently. On the other hand, in the conventional control method such as limiting the charging power of the secondary battery 14 based on the estimated internal pressure of the secondary battery 14, it is possible to reduce the increased internal pressure of the secondary battery 14. However, since it takes time until the internal pressure of the raised secondary battery 14 recovers, control for limiting the charging power of the secondary battery 14 is performed for a long time, and the recovery rate of electric energy by regenerative braking is reduced. In some cases, the secondary battery 14 cannot be charged efficiently.

  The secondary battery 14 includes a voltage sensor 20 that detects a terminal voltage of the secondary battery 14, a current sensor 22 that detects a current flowing through the secondary battery 14, and the temperature of the secondary battery 14 at a plurality of locations of the secondary battery 14. A temperature sensor 24 to detect is installed. Each sensor is electrically connected to the ECU 18, and data detected by each sensor is transmitted to the ECU 18.

The ECU 18 calculates the voltage between the electrode plates of the secondary battery 14. Here, the voltage between the plates of the secondary battery 14 is the voltage between the positive and negative electrodes of the secondary battery 14, and flows from the terminal voltage of the secondary battery 14 detected by the voltage sensor 20 to the secondary battery 14. It is obtained by excluding the IR component of the current and the internal resistance of the secondary battery 14 (see the following formula (1)).
V ₀ = VB + (IB × R) (1)
V ₀ : Voltage between the plates of the secondary battery VB: Terminal voltage of the secondary battery IB: Current value of the secondary battery (the charging side is negative)
R: Internal resistance of the secondary battery

  The calculation of the internal resistance of the secondary battery 14 is not particularly limited. For example, a plurality of current values and voltage values are plotted on the voltage / current coordinates, and a primary approximate expression is plotted along each plotted point. Then, the slope of the straight line represented by this approximate expression is calculated as the internal resistance. Further, since the internal resistance changes depending on the temperature of the secondary battery 14, a map representing the relationship between the internal resistance and the temperature of the secondary battery 14 is stored in the ECU 18 and detected by the temperature sensor 24. The internal resistance may be calculated by applying temperature data to the map.

  The voltage between the electrode plates is obtained by applying the terminal voltage and current value detected by the current sensor 22 and the voltage sensor 20 and the calculated internal resistance to the equation (1) by the ECU 18. When calculating the voltage between the electrode plates, for example, it is preferable to set an annealing (filter) of about several seconds in each sensor or ECU 18 to remove the influence of noise or the like. In addition, when a plurality of voltage sensors 20 are installed, the highest voltage among the voltages detected from the plurality of voltage sensors 20 is set between the electrode plates in that the charging control of the secondary battery 14 can be performed efficiently. It is preferable to use for calculation of voltage. In addition, although the said method can obtain | require the voltage between electrode plates simply and accurately, it is not necessarily restricted to this, For example, the voltage sensor 20 is installed in a positive electrode and a negative electrode, and the secondary battery 14 of direct For example, the voltage between the electrode plates may be detected.

  The ECU 18 calculates a gas generation potential at which gas is generated in the secondary battery 14. Since the gas generation potential depends on the temperature of the secondary battery 14, it is desirable to prepare a map representing the relationship between the temperature of the secondary battery 14 and the gas generation potential, as shown in FIG. For example, the ECU 18 calculates the gas generation potential by applying the temperature of the secondary battery 14 detected by the temperature sensor 24 to a map representing the relationship between the temperature of the secondary battery 14 and the gas generation potential. Since the gas generation potential depends on the temperature of the secondary battery 14, it is desirable to calculate by the above method. However, the gas generation potential is not necessarily limited to setting the gas generation potential based on the temperature, and the gas generation potential is set in advance. A predetermined predetermined value (fixed value), for example, the lowest gas generation potential expected from the operating temperature of the secondary battery 14 may be used as the predetermined value (fixed value).

The ECU 18 is a first charging power limit that is set so that the voltage of the secondary battery 14 does not rise to the gas generation potential at which gas is generated in the secondary battery 14 based on the voltage between the plates of the secondary battery 14. Calculate the value. Specifically, as shown in the map of FIG. 3, the charging power is reached after the voltage between the electrode plates of the secondary battery 14 reaches a value obtained by subtracting a predetermined value (Y ₁ ) from the gas generation potential calculated or specified above. (The charging power is limited), and when the voltage between the electrodes of the secondary battery 14 reaches a value obtained by subtracting a predetermined value (X ₁ ) from the gas generation potential, the charging power is made zero. A map is prepared, and the voltage between the electrode plates of the secondary battery 14 is applied to the map to calculate the first charging power limit value. Further, in the present embodiment, as long as a charging power limit value that does not increase the voltage between the electrode plates of the secondary battery 14 to the gas generation potential by charging is specified, the map is not limited to the map shown in FIG. . Further, for example, as low temperature range (e.g., 0 ℃ below), the predetermined value X ₁ becomes large, so that the high temperature range (e.g. 40 ° C. or higher), the predetermined value X ₁ becomes smaller, depending on the temperature of the secondary battery 14 The map may be changed.

The ECU 18 is set based on the internal pressure of the secondary battery 14 so that the internal pressure of the secondary battery 14 does not increase up to the internal pressure at which the safety valve of the secondary battery 14 attached to relieve the internal pressure of the secondary battery 14 operates. The second charging power limit value is calculated. Specifically, as shown in the map of FIG. 4, the internal pressure of the detected or calculated secondary battery 14, a value obtained by subtracting a predetermined value from the internal pressure relief valve of the secondary battery 14 is operated (Y ₂₎ (P _B ), The charging power is decreased (charging power is limited), and a value (P ₀ ) obtained by subtracting a predetermined value (X ₂ ) from the internal pressure of the secondary battery 14 at which the safety valve of the secondary battery 14 operates. When reaching the above, a map for reducing the charging power to zero is prepared, and the internal pressure of the secondary battery 14 is applied to the map to calculate the second charging power limit value. In the present embodiment, the map is not limited to the map shown in FIG. 4 as long as the charging power limit value that does not increase the internal pressure of the secondary battery 14 to the internal pressure at which the safety valve operates by charging is specified. Further, for example, as low temperature range (e.g., 0 ℃ below), the predetermined value X ₂ increases, so that the high temperature range (e.g. 40 ° C. or higher), the predetermined value X ₂ is reduced, depending on the temperature of the secondary battery 14 The map may be changed.

Next, the ECU 18 selects the calculated first charging power limit value and the second charging power limit value according to the internal pressure of the secondary battery 14 and limits the charging power of the secondary battery 14. For example, in the map shown in FIG. 4, when the internal pressure of the rechargeable battery 14 in the case of less than the predetermined value P _A is the without taking limit charging power, the internal pressure of the rechargeable battery 14 is equal to or greater than a predetermined value P _A Then, the lower one of the first charging power limit value and the second charging power limit value is selected, and the charging power of the secondary battery 14 is limited based on the charging power limit value.

Also, when the internal pressure of the rechargeable battery 14 is equal to or greater than a predetermined value P _A, select the first limit charging power may limit the charging power of the secondary battery 14. In this case, when the predetermined value P _A, it is necessary to have reached the area where the charging power is limited in the map shown in FIG. 3 (a predetermined value from the gas evolution potential (Y ₁₎ value after the region minus).

Further, for example, in the map shown in FIG. 4, when the internal pressure of the rechargeable battery 14 is less than the predetermined value P _A, but not to limit the charging power, charging power internal pressure of the rechargeable battery 14 is from less than a predetermined value P _A using the map with a limited, if the internal pressure of the rechargeable battery 14 is less than the predetermined value P _a, select the second limit charging power, become the internal pressure of the rechargeable battery 14 is equal to or larger than a predetermined value P _a In this case, the lower charging power limit value of the first charging power limit value and the second charging power limit value may be selected to limit the charging power. This predetermined value P _A is set as appropriate, effectively to allow the charge control of the secondary battery 14, it is preferable to change the temperature of the secondary battery 14.

  Next, a method for estimating the internal pressure of the secondary battery 14 will be described. In the present embodiment, it is preferable to adopt the internal pressure estimation method described below in terms of high estimation accuracy of the internal pressure of the secondary battery 14, but the present invention is not necessarily limited thereto, and the secondary battery 14 is not necessarily limited thereto. The internal pressure of the secondary battery 14 may be detected by a sensor that can directly detect the internal pressure of the secondary battery 14.

  First, in estimating the internal pressure of the secondary battery 14, the ECU 18 calculates the charging efficiency of the secondary battery 14 based on the temperature or current value of the secondary battery 14 and the voltage between the electrodes. For calculation of the charging efficiency of the secondary battery 14, for example, a map representing the relationship between the voltage between the electrodes of the secondary battery 14 and the charging efficiency as shown in FIG. 5 is used. Here, the charging efficiency is the ratio (η) of the amount of electricity actually stored to the chargeable charge amount or the ratio of the amount of electricity that could not be stored due to gas generation (β = 1−η).

  Since the relationship between the voltage between the electrode plates of the secondary battery 14 and the charging efficiency depends on the temperature or current value of the secondary battery 14, for example, as shown in FIG. Prepare a map showing the relationship between the voltage between the electrode plates and the charging efficiency at the temperature of several secondary batteries 14 as in the case of 40 ° C., 50 ° C., 60 ° C., or the like. ), For example, when the current value of the secondary battery 14 is 5A, 25A, 50A, etc. It is desirable to prepare a map that represents the relationship.

  For example, when the temperature detected by the temperature sensor 24 is 40 ° C., the ECU 18 calculates the above calculated poles on a map (see FIG. 5A) that represents the relationship between the electrode plate voltage and the charging efficiency at 40 ° C. By applying the inter-plate voltage, the charging efficiency is calculated. Further, for example, when the current value detected by the current sensor 22 is 5A, the ECU 18 calculates the above in a map (see FIG. 5B) that represents the relationship between the electrode plate voltage and the charging efficiency at 5A. By applying the voltage between the electrode plates, the charging efficiency is calculated. In addition, when the temperature detected by the temperature sensor 24 or the current value detected by the current sensor 22 is other than the temperature or current value of the map, for example, charging is performed by correcting the map by a linear interpolation method or the like. Efficiency can be sought. In order to calculate the charging efficiency more accurately, prepare a map that shows the relationship between the voltage between the electrodes and the charging efficiency with finely set intervals of temperature or current (for example, every 1 ° C., every 1A). May be.

  Further, when a plurality of temperature sensors 24 are installed, the charging efficiency at the temperature detected from each temperature sensor 24 is calculated in that the charging control of the secondary battery 14 can be efficiently performed, It is preferable to employ the maximum charging efficiency. Note that the calculation method of the charging efficiency is not necessarily limited to the above method, and any conventionally known calculation method or detection method can be employed.

Next, the ECU 18 calculates the amount of oxygen gas generated per unit time based on the charging efficiency and current value of the secondary battery 14. Specifically, it is calculated by the following formula (2) or (3).
α = (− IB) × β × K _α (2)
α = (− IB) × (1−η) × K _α (3)
α: Oxygen gas generation amount per unit time ΔT IB: Current of secondary battery (charge side is negative)
β, η: charging efficiency K _α : a predetermined constant (which is appropriately selected depending on the unit of α. For example, when α is expressed in moles, if the unit time ΔT is 1 sec, the Faraday constant (Reciprocal of ÷ 4)

  In the secondary battery 14, oxygen gas is generated by a side reaction during charging. On the other hand, oxygen gas is absorbed by an electrode opposite to the gas generating electrode. Based on the oxygen pressure in the secondary battery 14, the oxygen gas decrease amount is calculated.

  For example, a map representing the relationship between the oxygen pressure in the secondary battery 14 and the oxygen gas reduction amount per unit time is used to calculate the oxygen gas reduction amount of the secondary battery 14 calculated by the ECU 18. However, since the relationship between the oxygen pressure in the secondary battery 14 and the amount of oxygen gas decrease per unit time depends on the temperature of the secondary battery 14, for example, as shown in FIG. Prepare a map showing the relationship between the oxygen pressure in the secondary battery 14 and the amount of oxygen gas reduction per unit time at several secondary battery 14 temperatures, such as when the temperature is 40 ° C. or 50 ° C. Is preferred.

The ECU 18 estimates the oxygen pressure based on the difference between the oxygen gas generation amount and the oxygen gas decrease amount, that is, the oxygen gas amount in the secondary battery 14 every unit time. Specifically, it is calculated by the following equation (4).
P ₀ = P _x + K _p × (α−γ) × ΔT (4)
P ₀ : Oxygen pressure P _x : Previously calculated oxygen pressure α: Oxygen gas generation amount γ: Oxygen gas decrease amount K _p : Predetermined constant (a constant for converting the oxygen gas amount in the secondary battery 14 into the oxygen pressure) .)

Here, as the initial oxygen pressure P ₀ , the previously calculated oxygen pressure estimated value (P _x ) is set as a predetermined value (for example, atmospheric pressure), and the oxygen pressure in the secondary battery 14 and per unit time are set. The value calculated by applying a predetermined value set to atmospheric pressure or the like to a map (see FIG. 6) showing the relationship between the oxygen gas decrease amount and the oxygen gas decrease amount is calculated by the above equation (4) as the oxygen gas decrease amount (γ). The Next, for the oxygen pressure P ₀ after ΔT, the previously calculated oxygen pressure is P _x, and the map represents the relationship between the oxygen pressure in the secondary battery 14 and the amount of oxygen gas decrease per unit time (FIG. 6). The value calculated by applying the previously calculated oxygen pressure (P _x ) to the oxygen gas decrease amount (γ) is calculated by the above equation (4).

  In the above example, the oxygen gas decrease amount is calculated from the map (see FIG. 6) showing the relationship between the oxygen pressure in the secondary battery 14 corresponding to the temperature of the secondary battery 14 and the oxygen gas decrease amount per unit time. However, it is not necessarily limited to this. Since the oxygen gas reduction amount depends on the temperature, the oxygen gas reduction amount is calculated by applying the temperature of the secondary battery 14 to a map representing the relationship between the temperature of the secondary battery 14 and the oxygen gas reduction amount per unit time. You may do. That is, in the present embodiment, there is no particular limitation as long as the oxygen gas reduction amount is calculated based on at least the temperature of the secondary battery 14.

  Further, when a plurality of temperature sensors 24 are installed, the amount of oxygen gas decrease at the temperature detected from each temperature sensor 24 is calculated in that the charging control of the secondary battery 14 can be performed efficiently. Of these, it is preferable to employ the minimum oxygen gas reduction amount.

  The ECU 18 calculates the equilibrium hydrogen pressure in the secondary battery 14 and calculates the internal pressure in the secondary battery 14 by the sum of the calculated equilibrium hydrogen pressure and oxygen pressure. Here, since the equilibrium hydrogen pressure in the secondary battery 14 depends on the temperature of the secondary battery 14, the map showing the relationship between the temperature of the secondary battery 14 and the equilibrium hydrogen pressure in the secondary battery 14 shown in FIG. 7. The equilibrium hydrogen pressure of the secondary battery 14 is calculated by applying the temperature of the secondary battery 14 to the secondary battery 14.

  The charge control method of the present embodiment can be used in combination with a conventional control method such as, for example, limiting the charge power based on the storage amount and temperature of the secondary battery 14. When used together with the conventional control method, for example, the charging power limited in the present embodiment is compared with the charging power limited in the conventional control method, and the smallest charging power is adopted. It is preferable to limit the charging power. In addition, for example, a conventional control method such as limiting the charging power based on the storage amount and temperature of the secondary battery 14 in a certain situation is adopted, and a charging control method according to the present embodiment is adopted in another situation. Is possible. For example, in the state where the gas absorption reaction is very fast even when gas is generated (for example, the temperature of the secondary battery 14 is high), the conventional control method is adopted, and the gas absorption reaction is very slow (for example, the secondary battery). In a state where the temperature of 14 is low), the charging power may be limited by adopting the charging control method of the present embodiment. Specifically, the conventional control method is adopted if the temperature of the secondary battery 14 is equal to or higher than a predetermined value, and the charge control method of the present embodiment is adopted if the temperature of the secondary battery 14 is less than the predetermined value.

FIG. 8 is a flowchart showing an example of the operation of the charge control device for the secondary battery 14 according to the present embodiment. As shown in FIG. 8, in step S10, the voltage sensor 20 and the current sensor 22 detect the terminal voltage and current value of the secondary battery 14, and further detect the internal resistance based on the terminal voltage and current value. At this time, the internal resistance may be calculated by applying temperature data from the temperature sensor 24 to a map representing the relationship between the internal resistance and the temperature. In step S12, the ECU 18 applies the terminal voltage, current value, and internal resistance of the secondary battery 14 to the above equation (1) to calculate the voltage between the electrode plates of the secondary battery 14. In step S14, the ECU 18 applies the detected temperature of the secondary battery 14 to a map (see FIG. 2) representing the relationship between the temperature of the secondary battery 14 and the gas generation potential (V _G ), thereby generating the gas generation potential. Is calculated. In step S16, the ECU 18 defines a relationship between the voltage between the electrodes of the secondary battery 14 and the charge power limit value set so that the voltage of the secondary battery 14 does not increase to the gas generation potential (see FIG. 3). ) And the calculated inter-electrode voltage of the secondary battery 14 to calculate the first charging power limit value. In step S18, the ECU 18 calculates the internal pressure of the secondary battery 14 (details will be described later). In step S20, the calculated second power is calculated on a map (see FIG. 4) that defines the relationship between the internal pressure of the secondary battery 14 and the charge power limit value set so as not to increase to the internal pressure at which the safety valve of the secondary battery 14 operates. The second charging power limit value is calculated by applying the internal pressure of the secondary battery 14.

Then, ECU 18, when the internal pressure of the estimated secondary battery 14 is less than the predetermined value P _A is not multiplied by the limit of the charging power flow proceeds to step S22, when the internal pressure of the rechargeable battery 14 is a predetermined value or more P _A In step S24, the lower charging power limit value of the first charging power limit value and the second charging power limit value is selected, and the secondary battery 14 is charged based on the charging power limit value. Limit power. Note that, as explained above, for example, in the case the internal pressure of the rechargeable battery 14 is a predetermined value or more P _A selects a first charge power limit value, etc. which limits the charging power of the secondary battery 14 Alternatively, the calculated first charging power limit value and the second charging power limit value are selected according to the internal pressure of the secondary battery 14, and the charging power of the secondary battery 14 is limited.

  As described above, by controlling the charging of the secondary battery, the increase in internal pressure in the secondary battery can be mitigated / suppressed, so the charging power of the secondary battery can be limited in a short time, and regenerative braking The recovery rate of electrical energy can be improved.

  FIG. 9 is a flowchart illustrating an example of a method for estimating the internal pressure of the secondary battery 14 according to the present embodiment. As shown in FIG. 9, in step S <b> 30, the ECU 18 displays a map (see FIG. 5 (A)) or a two-dimensional relationship that represents the relationship between the electrode plate voltage and the charging efficiency (η or β) at each temperature of the secondary battery 14. In the map (see FIG. 5B) showing the relationship between the voltage between the electrode plates and the charging efficiency (η or β) at each current value of the secondary battery 14, the detected temperature or current value of the secondary battery 14, and The charging efficiency is calculated by applying the calculated electrode plate voltage. In step S32, the ECU 18 applies the charging efficiency and current value of the secondary battery 14 to the above formula (2) or (3) to calculate the oxygen gas generation amount per unit time. In step S34, the ECU 18 sets a predetermined value such as atmospheric pressure on a map (see FIG. 6) that represents the relationship between the oxygen pressure in the secondary battery 14 at each temperature of the secondary battery 14 and the amount of oxygen gas decrease per unit time. The value is applied to calculate the oxygen gas reduction amount (β). In step S36, the ECU 18 calculates the oxygen pressure by applying predetermined values such as the oxygen gas generation amount, the oxygen gas decrease amount, and the atmospheric pressure to the above equation (4). Based on this, the ECU 18 repeats steps S30 to S36 to estimate the oxygen pressure for every predetermined time (ΔT). In step S <b> 38, the ECU 18 applies the detected temperature of the secondary battery 14 to a map (see FIG. 7) that represents the relationship between the temperature of the secondary battery 14 and the equilibrium hydrogen pressure in the secondary battery 14. The equilibrium hydrogen pressure in 14 is calculated. In step S40, the ECU 18 calculates the internal pressure in the secondary battery 14 based on the sum of the calculated equilibrium hydrogen pressure and oxygen pressure. As described above, the internal pressure in the secondary battery can be accurately estimated.

  1 power unit, 10 motor generator, 12 inverter, 14 secondary battery, 18 ECU, 20 voltage sensor, 22 current sensor, 24 temperature sensor.

Claims (8)

Calculating a first charging power limit value set so as not to increase the voltage to the gas generation potential at which gas is generated in the secondary battery based on the voltage between the electrode plates of the secondary battery;
Calculating a second charging power limit value set so as not to increase to an internal pressure at which the safety valve of the secondary battery operates based on the internal pressure of the secondary battery;
Selecting the first charging power limit value or the second charging power limit value according to the internal pressure of the secondary battery, and limiting the charging power of the secondary battery;
Calculating the amount of oxygen gas generated in the secondary battery based on the current value and charging efficiency of the secondary battery, and calculating the amount of oxygen gas decrease in the secondary battery based on the temperature of the secondary battery Calculating the oxygen pressure of the secondary battery based on the oxygen gas generation amount and the oxygen gas decrease amount; calculating the equilibrium hydrogen pressure of the secondary battery based on the temperature of the secondary battery; , And the internal pressure of the secondary battery is obtained by the sum of the calculated oxygen pressure and the equilibrium hydrogen pressure.   2. The method for controlling charging of a secondary battery according to claim 1, wherein in the step of limiting the charging power of the secondary battery, the first charging power when the internal pressure of the secondary battery exceeds a predetermined value. A charging control method for a secondary battery, wherein a charging power limiting value of a lower one of the limiting value and the second charging power limiting value is selected to limit the charging power of the secondary battery. 3. The secondary battery charge control method according to claim 2 , wherein the predetermined value is set based on a temperature of the secondary battery.   The secondary battery charging control method according to claim 1, wherein the gas generation potential is defined based on a temperature of the secondary battery. Charge control method. Means for calculating a first charging power limit value set so as not to increase the voltage to the gas generation potential at which gas is generated in the secondary battery based on the voltage between the electrode plates of the secondary battery;
Means for calculating a second charging power limit value set so as not to increase to an internal pressure at which the safety valve of the secondary battery operates based on the internal pressure of the secondary battery;
Means for selecting the first charging power limit value or the second charging power limit value according to the internal pressure of the secondary battery and limiting the charging power of the secondary battery;
Means for calculating the amount of oxygen gas generated in the secondary battery based on the current value and charging efficiency of the secondary battery, and means for calculating the amount of oxygen gas decrease in the secondary battery based on the temperature of the secondary battery Means for calculating the oxygen pressure of the secondary battery based on the oxygen gas generation amount and the oxygen gas decrease amount, and means for calculating the equilibrium hydrogen pressure of the secondary battery based on the temperature of the secondary battery; , And the internal pressure of the secondary battery is obtained by the sum of the calculated oxygen pressure and the equilibrium hydrogen pressure.   6. The secondary battery charging control apparatus according to claim 5, wherein the means for limiting the charging power of the secondary battery is configured to reduce the first charging power when an internal pressure of the secondary battery exceeds a predetermined value. A charging control device for a secondary battery, wherein a charging power limiting value of a lower one of the limiting value and the second charging power limiting value is selected to limit the charging power of the secondary battery. 7. The secondary battery charge control device according to claim 6 , wherein the predetermined value is set based on a temperature of the secondary battery.   The secondary battery charge control device according to any one of claims 5 to 7, wherein the gas generation potential is defined based on a temperature of the secondary battery. Charge control device.

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