JP5418417B2 - 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.

  Normally, the charging control of the secondary battery is performed around the remaining capacity target value by setting the remaining capacity target value within the appropriate remaining capacity range. Specifically, when the remaining capacity of the secondary battery is smaller than the target remaining capacity value, the secondary battery is charged. When the remaining capacity of the secondary battery is larger than the target remaining capacity value, the secondary battery is charged. Charging of the battery is stopped or the amount of charge is limited.

  For example, in Patent Documents 1 to 3, a remaining capacity target value is set based on the temperature, voltage, and current of the secondary battery so that the output of the secondary battery can be stably supplied. A technique for performing charging control of a secondary battery around a target value is disclosed.

JP 2002-345165 A JP 2003-47108 A Japanese Patent Laid-Open No. 2005-261034

  By the way, in a normal secondary battery, gas generation occurs in the secondary battery as the voltage of the secondary battery increases, and the charging efficiency decreases. For this reason, it is preferable to control charging of the secondary battery in consideration of charging efficiency and suppress a decrease in charging efficiency.

  Accordingly, an object of the present invention is to provide a charge control method and a charge control device for a secondary battery that can suppress a decrease in charge efficiency of the secondary battery.

  The present invention is a secondary battery charge control method for controlling the charge of a secondary battery centering on a remaining capacity target value, the step of calculating the charge efficiency of the secondary battery, and the remaining capacity of the secondary battery Calculating a first charging efficiency determination value based on the temperature and the temperature; and, if the charging efficiency is equal to or higher than the first charging efficiency determination value, reducing the remaining capacity target value by a predetermined amount; Is provided.

  In the secondary battery charge control method, in the step of lowering the remaining capacity target value by a predetermined amount, the predetermined amount is determined according to a difference between the charge efficiency and the first charge efficiency determination value. Is preferred.

  In the secondary battery charge control method, a step of calculating a second charge efficiency determination value smaller than the first charge efficiency determination value based on a remaining capacity and temperature of the secondary battery; When the charging efficiency is equal to or lower than the second charging efficiency determination value, it is preferable to include a step of reducing the remaining capacity target value by reducing the remaining capacity target value by a predetermined amount.

  Further, the present invention is a secondary battery charge control device for controlling the charging of the secondary battery so as to become a preset remaining capacity target value, the means for calculating the charging efficiency of the secondary battery, Based on the remaining capacity and temperature of the secondary battery, the means for calculating the first charging efficiency determination value, and when the charging efficiency is equal to or higher than the first charging efficiency determination value, the remaining capacity target value is Means for lowering the predetermined amount.

  In the secondary battery charge control device, the means for lowering the remaining capacity target value by a predetermined amount determines the predetermined amount according to a difference between the charge efficiency and the first charge efficiency determination value. Is preferred.

  Further, in the secondary battery charge control device, a means for calculating a second charge efficiency determination value smaller than the first charge efficiency determination value based on the remaining capacity and temperature of the secondary battery; When charging efficiency is less than or equal to the second charging efficiency determination value, it is preferable to include means for recovering the lowered remaining capacity target value by means for lowering the remaining capacity target value by a predetermined amount.

  ADVANTAGE OF THE INVENTION According to this invention, the charging control method and charging control apparatus of a secondary battery which can suppress the fall of the charging efficiency 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 voltage between electrode plates of a secondary battery and charging efficiency. It is a map showing the relationship between the remaining capacity of a secondary battery and a 1st charging efficiency determination value. It is a map showing the relationship between the remaining capacity of a secondary battery and the 2nd charging efficiency determination value set smaller than the 1st charging efficiency determination value. It is a map showing the relationship between the remaining capacity of a secondary battery, a 1st charging efficiency determination value, and a 3rd charging efficiency determination value. It is a map showing the relationship between the temperature of a secondary battery or the vehicle speed of a vehicle, and a remaining capacity target value. It is a map showing the relationship between the temperature of a secondary battery or the vehicle speed of a vehicle, and a remaining capacity target value. It is a map showing the relationship between the temperature of a secondary battery or the vehicle speed of a vehicle, and a remaining capacity target value. 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.

  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) equipped with a secondary battery. The vehicle power unit 1 shown in FIG. 1 is 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 charging of the secondary battery 14. A functioning ECU 18 is provided. 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 whose charge is controlled by the charge control device according to the present embodiment can be applied to any secondary battery 14, but when charged at a high voltage, temperature, or the like, it is charged. A nickel metal hydride secondary battery in which gas is generated due to a side reaction different from the reaction and the charging efficiency tends to decrease is suitable.

  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.

  Normally, the ECU 18 sets a remaining capacity target value within the appropriate remaining capacity range in order to maintain the remaining capacity of the secondary battery 14 within the appropriate remaining capacity range defined by the control upper limit value and the control lower limit value. The charging control of the secondary battery 14 is performed around the capacity target value. For example, the control upper limit value is 80% of the remaining capacity of the secondary battery 14, the control lower limit value is 20% of the remaining capacity of the secondary battery 14 (that is, the appropriate remaining capacity range is 20 to 80%), The target capacity value is set to 60% as the remaining capacity of the secondary battery 14. When the remaining capacity of the secondary battery 14 is lower than 60%, the electric energy supplied from the motor generator 10 is supplied to the secondary battery 14 and the charging of the secondary battery 14 is advanced. If the remaining capacity of the secondary battery 14 is higher than 60%, the electric energy supplied from the motor generator 10 is limited and supplied to the secondary battery 14 (the supply of electric energy may be stopped). The charge amount of the secondary battery 14 is limited (or stopped). The upper limit limit is set in a range where the secondary battery 14 may be overcharged, and the lower limit limit is set in a range where the secondary battery 14 may be overdischarged.

  Normally, the ECU 18 performs the charging control of the secondary battery 14 as described above. Furthermore, in the present embodiment, the remaining capacity target value is changed based on the charging efficiency of the secondary battery 14, and the secondary battery 14 is changed. Charge control. The control will be described below.

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 electrode plates of the secondary battery 14 VB: Terminal voltage of the secondary battery 14 IB: Current value of the secondary battery 14 (the charging side is negative)
R: Internal resistance of the secondary battery 14

  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. The above method is a method that can easily and accurately obtain the voltage between the electrode plates, but is not necessarily limited thereto. For example, the voltage sensor 20 is installed on the positive electrode and the negative electrode, and the secondary voltage is directly obtained. For example, the voltage between the electrodes of the battery 14 may be detected.

  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 electrode plate voltage. 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. 2 is used. Here, the charging efficiency is the ratio of the amount of electricity actually stored with respect to the amount of charge (η) 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., a map (see FIG. 2A) showing the relationship between the voltage between the electrode plates and the charging efficiency when the temperature is 40 ° C. by the ECU 18 is used. 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. 2B) 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.

  The ECU 18 calculates a first charging efficiency determination value based on the remaining capacity and temperature of the secondary battery 14. For example, a map representing the relationship between the remaining capacity of the secondary battery 14 and the first charging efficiency determination value as shown in FIG. 3 is used to calculate the first charging efficiency determination value. Here, since the charging efficiency of the secondary battery 14 depends on the temperature, the first charging efficiency determination value also needs to depend on the temperature. For example, as shown in FIG. As in the case of 30 ° C., 40 ° C., etc., a map is prepared that represents the relationship between the remaining capacity of the secondary battery 14 and the first charging efficiency judgment value at the temperature of several secondary batteries 14.

  For example, when the temperature detected by the temperature sensor 24 is 40 ° C., a map (see FIG. 3) showing the relationship between the remaining capacity of the secondary battery 14 and the first charging efficiency determination value when the temperature is 40 ° C. by the ECU 18. The first charging efficiency determination value is calculated by applying the remaining capacity of the secondary battery 14 at that time. Further, when the temperature detected by the temperature sensor 24 is other than the temperature of the map, for example, the first charging efficiency determination value can be obtained by correcting the map by a linear interpolation method or the like. Further, when calculating the first charging efficiency determination value more accurately, the temperature interval is set finely (for example, every 1 ° C.) between the remaining capacity of the secondary battery 14 and the first charging efficiency determination value. You may prepare the map showing a relationship.

  Further, when a plurality of temperature sensors 24 are installed, the highest temperature among the temperatures detected from each temperature sensor 24 can be adopted in that the charging control of the secondary battery 14 can be performed efficiently. preferable.

  The detection of the remaining capacity of the secondary battery 14 is not particularly limited by a conventionally known method. For example, the voltage-current characteristics (IV characteristics) and the remaining capacity of the secondary battery 14 at the time of charging are used. And a detection method using the relationship between the charging current and a method of detecting by integrating the charging current.

  The ECU 18 compares the calculated charging efficiency of the secondary battery 14 with the first charging efficiency determination value, and when the charging efficiency of the secondary battery 14 is equal to or higher than the first charging efficiency determination value, the remaining capacity target The value is reduced by a predetermined amount (first predetermined amount). Here, the first predetermined amount may be defined in advance (for example, 10%). However, the larger the difference between the charging efficiency of the secondary battery 14 and the first charging efficiency determination value, the first place. It is desirable to determine the first predetermined amount according to the difference between the charging efficiency of the secondary battery 14 and the first charging efficiency determination value, such as increasing the fixed amount.

  Then, the charging control of the secondary battery 14 is performed around the lowered remaining capacity target value. That is, when the remaining capacity target value is reduced from 60% to 50%, if the remaining capacity of the secondary battery 14 is lower than 50%, the electric energy supplied from the motor generator 10 is supplied to the secondary battery 14. Then, the secondary battery 14 is charged. If the remaining capacity of the secondary battery 14 is higher than 50%, the electric energy supplied from the motor generator 10 is limited and supplied to the secondary battery 14 (the supply of electric energy may be stopped). The charge amount of the secondary battery 14 is limited (or stopped). In this way, by setting a determination criterion for charging efficiency and changing the remaining capacity target value based on the determination, deterioration of the charging efficiency of the secondary battery 14 can be suppressed and the secondary battery 14 can be protected. it can.

  Further, the ECU 18 calculates a second charging efficiency determination value smaller than the first charging efficiency determination value based on the remaining capacity and temperature of the secondary battery 14. In calculating the second charging efficiency determination value, for example, the relationship between the remaining capacity of the secondary battery 14 and the second charging efficiency determination value set smaller than the first charging efficiency determination value as shown in FIG. A map that represents is used. Here, although explanation in the figure is omitted, it is necessary to make the second charging efficiency judgment value dependent on the temperature as well as the first charging efficiency judgment value. For example, the temperature of the secondary battery 14 is 30 ° C. As in the case of 40 ° C., etc., a map is prepared that represents the relationship between the remaining capacity of the secondary battery 14 and the second charging efficiency determination value at the temperature of several secondary batteries 14.

  For example, when the temperature detected by the temperature sensor 24 is 40 ° C., the ECU 18 displays a map (see FIG. 4) showing the relationship between the remaining capacity of the secondary battery 14 and the second charging efficiency determination value when the temperature is 40 ° C. By applying the remaining capacity of the secondary battery 14, a second charging efficiency determination value is calculated. Further, when the temperature detected by the temperature sensor 24 is other than the temperature of the map, for example, the second charging efficiency determination value is obtained by correcting the map by a linear interpolation method or the like.

  Then, the ECU 18 compares the calculated charging efficiency of the secondary battery 14 with the second charging efficiency determination value, and reduces the charging efficiency when the charging efficiency of the secondary battery 14 is equal to or lower than the second charging efficiency determination value. The remaining target capacity value is restored to the normal remaining capacity target value. That is, the charging control of the secondary battery 14 is performed around the normal remaining capacity target value.

  Until now, the reduction of the target remaining capacity value of the secondary battery 14 has been determined based on one charging efficiency determination value, but the present invention is not necessarily limited to this and is used to reduce the target remaining capacity value. A plurality of charging efficiency determination values may be set. For example, the ECU 18 calculates a first charging efficiency determination value and a third charging efficiency determination value larger than the first charging efficiency determination value based on the remaining capacity and temperature of the secondary battery 14. For the calculation of the first and third charging efficiency determination values, for example, the relationship between the remaining capacity of the secondary battery 14 and the first charging efficiency determination value and the third charging efficiency determination value as shown in FIG. A map that represents is used. Here, although explanation in the figure is omitted, the first and third charging efficiency determination values also need to depend on the temperature, as described above. For example, the temperature of the secondary battery 14 is 30 ° C. or 40 ° C. As in the case of time, a map representing the relationship between the remaining capacity of the secondary battery 14 at the temperature of several secondary batteries 14 and the first and third charging efficiency determination values is prepared.

  For example, when the temperature detected by the temperature sensor 24 is 40 ° C., a map representing the relationship between the remaining capacity of the secondary battery 14 and the first and third charging efficiency determination values when the temperature is 40 ° C. by the ECU 18 (FIG. 5). The first and third charging efficiency determination values are calculated by applying the remaining capacity of the secondary battery 14 at that time to the reference). Further, when the temperature detected by the temperature sensor 24 is other than the temperature of the map, for example, the first and third charging efficiency determination values are obtained by correcting the map by a linear interpolation method or the like.

  Then, the ECU 18 compares the calculated charging efficiency of the secondary battery 14 with the first and third charging efficiency determination values. When the charging efficiency of the secondary battery 14 is not less than the first charging efficiency determination value and less than the third charging efficiency determination value, the remaining capacity target value is lowered by a first predetermined amount (for example, 5%). When the charging efficiency of the secondary battery 14 is equal to or higher than the third charging efficiency determination value, the remaining capacity target value is lowered by a second predetermined amount (for example, 10%) that is larger than the first predetermined amount. Then, the charging control of the secondary battery 14 is performed around the lowered remaining capacity target value. Thus, by setting the determination criteria for the charging efficiency in detail, the deterioration of the charging efficiency of the secondary battery 14 can be suppressed more efficiently and the secondary battery 14 can be protected.

  In the present embodiment, the remaining capacity target value (for example, 60%) before the reduction is constant regardless of the temperature or the like, but is not necessarily limited to this. If there is, the remaining capacity target value may be changed according to the vehicle speed or the like. Specifically, a map or the like representing the relationship between the temperature of the secondary battery 14 or the vehicle speed of the vehicle and the remaining capacity target value as shown in FIG. 6 is stored in the ECU 18, according to the temperature and the vehicle speed of the secondary battery 14. Thus, the remaining capacity target value before the reduction is changed. At that time, for example, when the charging efficiency of the secondary battery 14 is equal to or higher than the first charging efficiency determination value, the first predetermined amount (from the remaining capacity target value determined according to the temperature of the secondary battery 14 and the vehicle speed ( For example, it is reduced by 5% (dotted line shown in FIG. 6).

  In the present embodiment, the predetermined amount for reducing the remaining capacity target value is set in advance or determined according to the difference between the charging efficiency of the secondary battery 14 and the first charging efficiency determination value. This is not a limitation. For example, the predetermined amount for lowering the remaining capacity target value may be changed according to the temperature of the secondary battery 14, the vehicle speed of the vehicle, and the like. Specifically, as shown in FIG. 7, in the high temperature range of the secondary battery 14 with poor charging efficiency and the high speed range of the vehicle in which the amount of regenerative electricity increases, the predetermined amount for lowering the remaining capacity target value is increased to increase the remaining capacity. The capacity target value may be set low. That is, when the charging efficiency of the secondary battery 14 is equal to or higher than the first charging efficiency determination value and the secondary battery 14 is in a high temperature range or a vehicle high speed range, it is reduced by, for example, 10% from the remaining capacity target value. Even when the charging efficiency of the secondary battery 14 is equal to or higher than the first charging efficiency judgment value, if the secondary battery 14 is not in a high temperature range or a high speed range of the vehicle, it is only 5% from the remaining capacity target value. It is also possible to set so as to lower. Such a setting is suitable when the remaining capacity target value before the reduction is set to be constant without depending on the temperature of the secondary battery 14 or the vehicle speed.

  On the other hand, when the remaining capacity target value before the reduction is set so as to decrease as the temperature of the secondary battery 14 and the vehicle speed increase, as shown in FIG. A predetermined amount for lowering the remaining capacity target value may be reduced in a range so that the remaining capacity target value does not become too low. That is, when the charging efficiency of the secondary battery 14 is equal to or higher than the first charging efficiency determination value and the secondary battery 14 is in a high temperature range or a high speed range of the vehicle, it is reduced by, for example, 5% from the remaining capacity target value. Even when the charging efficiency of the secondary battery 14 is equal to or higher than the first charging efficiency determination value, if the secondary battery 14 is not in the high temperature range or the high speed range of the vehicle, it is only 10% from the remaining capacity target value, for example. It is preferable to set so as to lower.

  In the charge control method of the present embodiment, the charging efficiency determination value and the like are sequentially calculated at predetermined time intervals, and the charging efficiency of the secondary battery 14 is compared with the charging efficiency of the secondary battery 14 and the charging efficiency determination value. The charging efficiency determination value or the like may be calculated in a state where the charging efficiency of the secondary battery 14 is likely to deteriorate, for example, in the high temperature range of the secondary battery 14 or in the high speed range of the vehicle. The charging efficiency of the secondary battery 14 may be controlled by comparing the charging efficiency and the charging efficiency determination value.

  FIG. 9 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. 9, 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 S <b> 14, the ECU 18 displays a map (see FIG. 2A) representing the relationship between the voltage between the electrode plates and the charging efficiency (η or β) at each temperature of the secondary battery 14 and each current value of the secondary battery 14. In the map (see FIG. 2B) showing the relationship between the voltage between the electrode plates and the charging efficiency (η or β) in FIG. 2, the detected temperature or current value of the secondary battery 14 and the calculated voltage between the electrode plates. Is applied to calculate the charging efficiency.

  In step S16, the ECU 18 calculates the remaining capacity of the secondary battery 14. In step S18, the map of the relationship between the remaining capacity of the secondary battery 14 at each temperature and the first charging efficiency determination value (see FIG. 3) is displayed on the temperature of the secondary battery 14 and the calculated value of the secondary battery 14. A first charging efficiency determination value is calculated by applying the remaining capacity.

  Then, the ECU 18 compares the calculated charging efficiency with the first charging efficiency determination value. If the calculated charging efficiency is equal to or higher than the first charging efficiency determination value, the ECU 18 proceeds to step S20 and sets the remaining capacity target value. Reduce by a predetermined amount (for example, 10%). The charging control of the secondary battery 14 is performed centering on the lowered remaining capacity target value (or the initial remaining capacity target value).

  As described above, by performing charging control of the secondary battery in consideration of the charging efficiency of the secondary battery, it is possible to suppress the deterioration of the charging efficiency of the secondary battery and protect the secondary battery.

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

Claims (6)

A charge control method for a secondary battery that controls the charge of the secondary battery around the remaining capacity target value,
Calculating the charging efficiency of the secondary battery;
Calculating a first charging efficiency determination value based on the remaining capacity and temperature of the secondary battery;
And a step of lowering the remaining capacity target value by a predetermined amount when the charging efficiency is equal to or higher than the first charging efficiency determination value.   2. The secondary battery charge control method according to claim 1, wherein in the step of lowering the remaining capacity target value by a predetermined amount, the predetermined amount is determined according to a difference between the charging efficiency and the first charging efficiency determination value. A charge control method for a secondary battery, wherein: The secondary battery charging control method according to claim 1 or 2, wherein the second charging efficiency determination value is smaller than the first charging efficiency determination value based on the remaining capacity and temperature of the secondary battery. Calculating steps,
A step of lowering the remaining capacity target value by a predetermined amount when the charging efficiency is equal to or lower than the second charging efficiency determination value, and a step of recovering the lowered remaining capacity target value. Secondary battery charge control method. A charging control device for a secondary battery that controls charging of the secondary battery so as to be a preset remaining capacity target value,
Means for calculating the charging efficiency of the secondary battery;
Means for calculating a first charging efficiency determination value based on the remaining capacity and temperature of the secondary battery;
Means for lowering the remaining capacity target value by a predetermined amount when the charging efficiency is equal to or higher than the first charging efficiency determination value.   5. The charging control device for a secondary battery according to claim 4, wherein the means for lowering the remaining capacity target value by a predetermined amount is configured to reduce the predetermined amount according to a difference between the charging efficiency and the first charging efficiency determination value. A charge control device for a secondary battery, wherein 6. The secondary battery charge control device according to claim 4, wherein the second charge efficiency determination value is smaller than the first charge efficiency determination value based on a remaining capacity and a temperature of the secondary battery. Means for calculating
Means for reducing the remaining capacity target value by a means for reducing the remaining capacity target value by a predetermined amount when the charging efficiency is equal to or less than the second charging efficiency determination value, Secondary battery charge control device.

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