JP2012165580A - Control device of power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that it may be insufficient just to make voltage equalize in a plurality of power storage elements when an ignition switch is turned off.SOLUTION: The control device comprises: a power storage device (10) including a plurality of power storage elements (11) which are electrically connected in series; a voltage sensor (42) which detects the voltage of each power storage element; a discharge circuit (43) which discharges each power storage element; and a controller (30) which controls operation of the discharge circuit. The controller sets a first equalization mode which operates the discharge circuit to equalize the voltage of the plurality of power storage elements when the ignition switch of a vehicle is turned off. In the case that a voltage difference in the plurality of power storage elements is larger than a threshold value when the ignition switch is turned from off to on, the controller sets a second equalization mode which operates the discharge circuit to equalize the voltage of the plurality of power storage elements while the ignition switch is turned on.

Description

  The present invention relates to a control device that equalizes the capacities of a plurality of power storage elements electrically connected in series.

  An assembled battery in which a plurality of unit cells are electrically connected in series is used as a power source for running a vehicle, for example. Depending on charging / discharging of the assembled battery, voltage (in other words, SOC: State Of Charge) may vary among a plurality of single cells. Therefore, an equalization circuit is provided for each unit cell, and the unit cell on the higher voltage side is discharged to suppress voltage variation.

  When the assembled battery is mounted on a vehicle, generally, the equalization process is performed when the ignition switch is off. When the ignition switch is on, charging / discharging of the assembled battery connected to the vehicle's electrical system may cause variations in the polarization state or variations in the amount of voltage drop among multiple cells. As a result, the voltage of the unit cell is changed. In such a state, it is not possible to determine an accurate power storage state of each unit cell.

JP 2006-166615 A JP 2008-193871 A JP 2007-018868 A

  If the equalization process is performed only when the ignition switch is off, the equalization process may be insufficient. If the ignition switch is turned on with insufficient equalization processing, the voltage variation among the plurality of single cells may spread.

  A control device according to the first invention of the present application includes a plurality of power storage elements electrically connected in series, outputs a power storage device that outputs energy used for running the vehicle, and a voltage sensor that detects a voltage of each power storage element And a discharge circuit connected to each power storage element for discharging each power storage element, and a controller for controlling the operation of the discharge circuit. When the ignition switch of the vehicle is off, the controller sets a first equalization mode in which the discharge circuit is operated to equalize the voltages of the plurality of power storage elements. In addition, when the voltage difference between the plurality of power storage elements when the ignition switch is switched from OFF to ON is larger than the threshold value, the controller operates the discharge circuit while the ignition switch is ON to set the voltages of the plurality of power storage elements. A second equalization mode for equalization is set.

  The controller uses a timer to measure the time for which the ignition switch is continuously turned on, and this measurement time is greater than the voltage difference that can be equalized by the equalization process in the first equalization mode. When it is time to generate, the second equalization mode can be set. If a voltage difference larger than the voltage difference that can be equalized by the equalization process in the first equalization mode occurs while the ignition switch is on, the equalization process in the first equalization mode Then, it becomes difficult to suppress variations in voltage. Therefore, in such a case, voltage variation among the plurality of power storage elements can be suppressed by performing equalization processing in the second equalization mode.

  The controller can perform the equalization process in the second equalization mode based on the detection voltage of the voltage sensor obtained at the timing when the charge / discharge current of the power storage device becomes zero. At the timing when the charge / discharge current becomes zero, the voltage (CCV) obtained by the voltage sensor can be regarded as the OCV of the storage element. Thereby, even when the ignition switch is on, the voltage variation among the plurality of power storage elements can be suppressed by the equalization process in the second equalization mode.

  In the equalization process in the second equalization mode, the controller can operate the discharge circuit so as to maintain the voltage difference when the ignition switch is switched from off to on. Specifically, the controller uses the second equalization mode based on at least one of the self-discharge capacity of the plurality of power storage elements and the current consumption of the power storage element accompanying the equalization process in the second equalization mode. The discharge current when performing the equalization process can be determined. The voltage difference can be reduced by maintaining the voltage difference when the ignition switch is on, and performing the equalization process in the first equalization mode next time. Thereby, the voltage difference can be reduced stepwise each time the equalization process is performed in the first equalization mode.

  A second invention of the present application is a control method for outputting energy used for traveling of a vehicle and equalizing voltages in a plurality of power storage elements electrically connected in series, and detecting a voltage of each power storage element Has steps. Here, when the ignition switch of the vehicle is off, a first equalization mode is set in which the discharge circuit for discharging each power storage element is operated to equalize the voltages of the plurality of power storage elements. Further, when the voltage difference between the plurality of power storage elements when the ignition switch is switched from OFF to ON is larger than the threshold value, the discharge circuit is operated while the ignition switch is ON to equalize the voltages of the plurality of power storage elements. A second equalization mode is set.

  According to the present invention, by setting not only the first equalization mode but also the second equalization mode, it is possible to suppress an increase in voltage variation among the plurality of power storage elements.

1 is a schematic diagram showing a configuration of a battery system that is Example 1. FIG. It is a figure which shows the structure of a part of battery system which is Example 1. FIG. 1 is a diagram illustrating a configuration of an equalization circuit in Embodiment 1. FIG. 3 is a flowchart illustrating an equalization process in the first embodiment. It is a figure which shows the change of a battery voltage when the equalization process in Example 1 is performed. In Example 1, it is a flowchart which shows the equalization process in 1st equalization mode. In Example 1, it is a figure explaining the setting method of threshold value Tmax. In Example 1, it is a flowchart which shows the equalization process in 2nd equalization mode. It is a figure which shows the change of a battery voltage when the equalization process in Example 2 is performed.

  Examples of the present invention will be described below.

  The battery system in Example 1 of this invention is demonstrated using FIG. FIG. 1 is a schematic diagram showing the configuration of the battery system in the present embodiment.

  The battery system shown in FIG. 1 is mounted on a vehicle. Such vehicles include hybrid vehicles and electric vehicles. A hybrid vehicle is a vehicle provided with a fuel cell, an internal combustion engine, etc. in addition to the assembled battery as a power source for running the vehicle. An electric vehicle is a vehicle that includes only an assembled battery as a power source for the vehicle.

  The assembled battery (corresponding to a power storage device) 10 is connected to a booster circuit 22 via system main relays 21a and 21b, and the booster circuit 22 boosts the output voltage of the assembled battery 10. An inverter 23 is connected to the booster circuit 22, and the inverter 23 converts DC power from the booster circuit 22 into AC power. The motor / generator (AC motor) 24 receives AC power from the inverter 23 to generate kinetic energy for running the vehicle. The kinetic energy generated by the motor generator 24 is transmitted to the wheels.

  When the vehicle is decelerated or the vehicle is stopped, the motor / generator 24 converts kinetic energy generated during braking of the vehicle into electrical energy. The AC power generated by the motor / generator 24 is converted into DC power by the inverter 23, and the booster circuit 22 steps down the output voltage of the inverter 23 and supplies it to the assembled battery 10. Thereby, regenerative electric power can be stored in the assembled battery 10.

  The controller 30 includes a timer 31 and controls the operations of the system main relays 21 a and 21 b, the booster circuit 22 and the inverter 23. The timer 31 may be provided outside the controller 30.

  When receiving information indicating that the ignition switch is on, the controller 30 switches the system main relays 21a and 21b from off to on, and operates the booster circuit 22 and the inverter 23. When the controller 30 receives information that the ignition switch is OFF, the controller 30 switches the system main relays 21a and 21b from ON to OFF, or stops the operation of the booster circuit 22 and the inverter 23.

  As shown in FIG. 2, the assembled battery 10 includes a plurality of unit cells (corresponding to power storage elements) 11 that are electrically connected in series. The number of unit cells 11 constituting the assembled battery 10 can be appropriately set based on the required output of the assembled battery 10 and the like. The assembled battery 10 may include a plurality of single cells 11 that are electrically connected in parallel. As the cell 11, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor (capacitor) can be used instead of the secondary battery.

  The current sensor 41 detects the current flowing through the assembled battery 10 during charging / discharging and outputs the detection result to the controller 30. A voltage monitoring IC (voltage sensor) 42 is electrically connected in parallel to each unit cell 11. The voltage monitoring IC 42 detects the voltage of the unit cell 11 and outputs the detection result to the controller 30. The voltage monitoring IC 42 operates by receiving power from the corresponding unit cell 11.

  Further, an equalization circuit (corresponding to a discharge circuit) 43 is electrically connected in parallel to each unit cell 11, and the equalization circuit 43 equalizes the voltage (or SOC) in the plurality of unit cells 11. It is used to make it. The operation of the equalization circuit 43 is controlled by the controller 30.

  For example, when the controller 30 determines that the voltage of a specific unit cell 11 is higher than the voltages of other unit cells 11 based on the output of the voltage monitoring IC 42, the equalization circuit 43 corresponding to the specific unit cell 11. Only the specific cell 11 is discharged by operating only the single cell 11. Thereby, the voltage of the specific single battery 11 falls and it can be made substantially equal to the voltage of the other single battery 11.

  A specific configuration (example) of the equalization circuit 43 will be described with reference to FIG. FIG. 3 is a circuit diagram showing the configuration of the unit cell 11 and the equalization circuit 43.

  The equalization circuit 43 includes a resistor 43a and a switch element 43b. The switch element 43b is switched between on and off in accordance with a control signal from the controller 30. When the switch element 43b is switched from OFF to ON, the current of the unit cell 11 flows through the resistor 43a, and the unit cell 11 can be discharged. Thereby, the voltage of each single battery 11 can be adjusted, and the voltage in the several single battery 11 can be equalized.

  In this embodiment, the equalization circuit 43 and the voltage monitoring IC 42 are provided for each unit cell 11, but the present invention is not limited to this. Here, one battery block is constituted by the plurality of single cells 11 electrically connected in series, and the assembled battery 10 can be constituted by electrically connecting the plurality of battery blocks in series. . In this case, an equalization circuit 43 and a voltage monitoring IC 42 can be provided for each battery block. The voltage monitoring IC 42 detects the voltage of the corresponding battery block, and the equalization circuit 43 discharges the corresponding battery block. Here, one battery block corresponds to the power storage element of the present invention.

  Next, the equalization process of the present embodiment will be described with reference to FIGS. FIG. 4 is a flowchart showing the equalization process, and the process shown in FIG. FIG. 5 shows the behavior (one example) of the maximum value and the minimum value among the voltages of the plurality of single cells 11. The vertical axis in FIG. 5 indicates the voltage of the unit cell 11, and the horizontal axis indicates time. In FIG. 5, the dotted line indicates the OCV (Open Circuit Voltage) of the unit cell 11, and the solid line indicates the CCV (Closed Circuit Voltage) of the unit cell 11.

  When the ignition switch is switched from OFF to ON in step S100 in FIG. 4, the controller 30 starts the timer 31 in step S101. The timer 31 is used for measuring the time Ts when the ignition switch is continuously turned on.

  While the ignition switch is on, the voltage (CCV) detected by the voltage monitoring IC 42 changes according to the running state of the vehicle, as shown in FIG. As for the OCV of the unit cell 11, as shown in FIG. 5, the difference between the maximum value and the minimum value of the OCV may widen depending on the traveling state of the vehicle.

  In step S102, the controller 30 determines whether or not the ignition switch has been switched from on to off. If the ignition switch remains on, the time Ts is continuously measured in step S101. On the other hand, when the ignition switch is switched from on to off, the process proceeds to step S103.

  In step S103, the controller 30 sets the first equalization mode. The first equalization mode is a mode for performing equalization processing of the assembled battery 10 when the ignition switch is off.

  In the first equalization mode, the controller 30 detects the voltage (OCV) of the unit cell 11 based on the output of the voltage monitoring IC 42. Specifically, the voltage (OCV) of the unit cell 11 can be detected by discharging the assembled battery 10 in a short time. Then, while the ignition switch is off, the controller 30 detects the OCV at a predetermined cycle. Further, the controller 30 performs equalization processing based on the maximum value and the minimum value of the OCV.

  FIG. 6 shows the equalization process in the first equalization mode. The process shown in FIG. 6 is performed in a cycle in which the OCV of the single battery 11 is detected.

  In step S200 of FIG. 6, the controller 30 acquires the OCV of each single battery 11 based on the outputs of the plurality of voltage monitoring ICs 42, and specifies the maximum value and the minimum value of the OCV.

  In step S201, the controller 30 determines whether or not the difference ΔVmax (OCV) between the maximum value OCV and the minimum value OCV is larger than the threshold value ΔVt (OCV). A specific value of the threshold value ΔVt (OCV) can be set as appropriate from the viewpoint of suppressing voltage variation in the assembled battery 10. Here, as the threshold value ΔVt (OCV) is decreased, the voltage difference ΔVmax (OCV) can be decreased by the equalization process in the first equalization mode.

  In this embodiment, the difference ΔVmax (OCV) between the maximum value OCV and the minimum value OCV is calculated, but the present invention is not limited to this. Specifically, the OCV difference between any two unit cells 11 among the plurality of unit cells 11 can be calculated.

  In step S201, when the voltage difference ΔVmax (OCV) is smaller than the threshold value ΔVt (OCV), this process ends. On the other hand, when the voltage difference ΔVmax (OCV) is larger than the threshold value ΔVt (OCV), equalization processing is performed in step S202.

  In the equalization processing in step S202, the controller 30 operates the equalization circuit 43 by outputting a drive signal to the equalization circuit 43 provided corresponding to the unit cell 11 showing the maximum value OCV. In the equalization circuit 43, the switch element 43b is switched from OFF to ON, and the current of the unit cell 11 flows through the resistor 43a. Thereby, as shown in FIG. 5, the voltage of the single battery 11 which shows the maximum value OCV can be reduced, and the variation in the voltage in the several single battery 11 can be suppressed.

  In step S104 of FIG. 4, the controller 30 determines whether or not the ignition switch has been switched from OFF to ON. If the ignition switch remains off, the process returns to step S103 to monitor the OCV of the unit cell 11, and if necessary, equalization processing in the first equalization mode is performed. On the other hand, when the ignition switch is switched from OFF to ON, the process proceeds to step S105.

  In step S105, the controller 30 determines whether or not the time Ts measured by the timer 31 in step S101 is longer than the threshold value Tmax. The threshold value Tmax can be set as appropriate in consideration of the time until the equalization process in the first equalization mode is completed. As the measurement time Ts becomes longer, the variation in OCV may spread, and even when the equalization process is performed in the first equalization mode, it may be difficult to suppress the variation in OCV. Based on this point, the threshold value Tmax can be set.

  As a method for setting the threshold Tmax, for example, there is a method described below.

  In FIG. 7, 24 hours are divided into a time zone in which the ignition switch is on and a time zone in which the ignition switch is off. A voltage difference (maximum value) at which the equalization process can be completed while the ignition switch is off is ΔV1. The voltage difference ΔV1 can be set based on the discharge current when performing the equalization process.

  Further, while the ignition switch is on, the voltage difference (maximum value) in the plurality of single cells 11 is ΔV2. The voltage difference ΔV2 can be estimated by conducting an experiment or the like in advance.

  Under the condition that the voltage difference ΔV2 is larger than the voltage difference ΔV1, even if the equalization process is performed, the voltage variation among the plurality of single cells 11 cannot be suppressed, and the voltage variation spreads. On the other hand, under the condition that the voltage difference ΔV2 is smaller than the voltage difference ΔV1, the voltage variation among the plurality of single cells 11 can be suppressed by performing the equalization process.

  Under the condition that the voltage difference ΔV2 and the voltage difference ΔV1 are equal, it is possible to specify the time zone in which the ignition switch is on and the time zone in which the ignition switch is off. Here, the time zone in which the ignition switch is on can be set as the threshold value Tmax.

  In step S105 of FIG. 4, when the measurement time Ts is shorter than the threshold value Tmax, this process is terminated, and when the measurement time Ts is longer than the threshold value Tmax, the process proceeds to step S106. In step S106, the controller 30 calculates a voltage difference ΔVmax (OCV) when the ignition switch is switched from off to on.

  Specifically, the controller 30 acquires the maximum value and minimum value of the OCV when the ignition switch is switched from OFF to ON based on the output of the voltage monitoring IC 42. Then, the controller 30 calculates a difference ΔVmax (OCV) between the maximum value OCV and the minimum value OCV. In this embodiment, the difference ΔVmax (OCV) between the maximum value OCV and the minimum value OCV is calculated, but the present invention is not limited to this. Specifically, the OCV difference between any two unit cells 11 among the plurality of unit cells 11 can be calculated.

  In step S106, the controller 30 determines whether or not the voltage difference ΔVmax (OCV) is larger than the threshold value ΔVt (OCV). The threshold value ΔVt (OCV) here is the same as the threshold value ΔVt (OCV) used in step S201 in FIG. Note that the threshold value ΔVt (OCV) used in step S106 may be different from the threshold value ΔVt (OCV) used in step S201.

  In step S106, when the voltage difference ΔVmax (OCV) is smaller than the threshold value ΔVt (OCV), this process ends. When the voltage difference ΔVmax (OCV) is larger than the threshold value ΔVt (OCV), the process proceeds to step S107.

  In step S107, the controller 30 sets the second equalization mode. The second equalization mode is a mode for performing equalization processing while the ignition switch is on. In step S108, the controller 30 performs equalization processing while the ignition switch is on. The equalization process in the second equalization mode will be described with reference to FIG.

  In step S <b> 300 of FIG. 8, the controller 30 monitors the charge / discharge current of the assembled battery 10 based on the output of the current sensor 41. Moreover, in step S301, the controller 30 monitors the voltage (CCV) of each single battery 11 based on the output of each voltage monitoring IC42.

  In step S302, the controller 30 acquires the voltage (CCV) of each unit cell 11 at the timing when the charge / discharge current becomes zero. In this embodiment, the voltage (CCV) of the unit cell 11 when the charge / discharge current becomes zero is regarded as OCV. Further, the controller 30 specifies the maximum value and the minimum value of the CCV, and determines whether or not the difference ΔVmax (CCV) between the maximum value CCV and the minimum value CCV is larger than the threshold value ΔVt (CCV). The threshold value ΔVt (CCV) here is the same as the threshold value ΔVt (OCV) described in step S106 of FIG. Note that the threshold value ΔVt (CCV) may be a value different from the threshold value ΔVt (OCV).

  In this embodiment, the difference ΔVmax (CCV) between the maximum value CCV and the minimum value CCV is calculated in step S302, but the present invention is not limited to this. Specifically, the CCV difference between any two unit cells 11 among the plurality of unit cells 11 can be calculated.

  When the voltage difference ΔVmax (CCV) is smaller than the threshold value ΔVt (CCV), this process ends. On the other hand, when the voltage difference ΔVmax (CCV) is larger than the threshold value ΔVt (CCV), the process proceeds to step S303 and equalization processing is performed.

  In step S303, the controller 30 operates the equalization circuit 43 by outputting a drive signal to the equalization circuit 43 corresponding to the unit cell 11 showing the maximum value CCV. In the equalization circuit 43, the switch element 43b is switched from OFF to ON, and the current of the unit cell 11 flows through the resistor 43a. Thereby, it can suppress that the voltage of the single battery 11 which shows the maximum value CCV rises, and can suppress the dispersion | variation in the voltage in the several single battery 11. FIG.

  According to the present embodiment, the voltage variation in the assembled battery 10 can be suppressed by performing the equalization process in the first equalization mode while the ignition switch is off. In addition, when the ignition switch is off for a short time and it is difficult to suppress the voltage variation by the equalization process in the first equalization mode, the second equalization mode is activated while the ignition switch is on. By performing the equalization process, it is possible to suppress the spread of voltage variation in the assembled battery 10.

  In this embodiment, in step S105 in FIG. 4, it is determined whether or not the time Ts when the ignition switch is continuously turned on is longer than the threshold value Tmax. However, the present invention is not limited to this. Absent. Some vehicles have a measurement time Ts that is likely to be longer than a threshold value Tmax. For example, a taxi tends to have a long time during which the ignition switch is turned on and a short time during which the ignition switch is turned off. In such a vehicle, the process of step S105 of FIG. 4 can be omitted. That is, some vehicles can be treated as satisfying the requirement (Ts> Tmax) of step S105 in FIG.

  On the other hand, even if the measurement time Ts is shorter than the threshold value Tmax in step S105 of FIG. 4, the process of step S106 can be performed. Here, when the measurement time Ts is shorter than the threshold value Tmax, the voltage difference ΔVmax (OCV) can be easily made smaller than the threshold value ΔVt (OCV) by performing the equalization process in the first equalization mode. . In other words, if the voltage difference ΔVmax (OCV) does not become smaller than the threshold value ΔVt (OCV) even if the equalization process in the first equalization mode is performed when the measurement time Ts is shorter than the threshold value Tmax, the unit cell 11 can be determined that an abnormality has occurred. For example, when a short circuit occurs inside the single battery 11, the voltage difference ΔVmax (OCV) may not be smaller than the threshold value ΔVt (OCV) even if the equalization process is performed in the first equalization mode.

  A battery system in Example 2 of the present invention will be described. Here, members having the same functions as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Hereinafter, differences from the first embodiment will be described.

  While the ignition switch is on, the voltage (CCV) of the cell 11 acquired from the voltage monitoring IC 42 may be different from the actual OCV. In this case, if the equalization process in the second equalization mode is performed based on the voltage difference ΔVmax (CCV), the unit cell 11 that is the target of the equalization process may be excessively discharged. There is.

  Therefore, in this embodiment, in the equalization process in the second equalization mode, the maximum voltage difference ΔVmax (OCV) in the plurality of unit cells 11 is changed to the voltage difference ΔVmax (when the ignition switch is switched from OFF to ON). OCV). This will be specifically described below.

  The controller 30 sets the discharge current Ieq when performing the equalization process in the second equalization mode based on the following equation (1).

Ieq = ΔI ₁ + ΔI ₂ (1)

Here, ΔI ₁ indicates a variation in current consumption of the voltage monitoring IC 42 provided corresponding to each unit cell 11, and is a difference in current consumption between the two unit cells 11 to be equalized. If the current consumption of each voltage monitoring IC 42 is specified in advance, ΔI ₁ can be calculated. ΔI ₂ indicates the variation in the self-discharge amount among the plurality of single cells 11, and is the difference between the self-discharge amounts in the two single cells 11 to be subjected to equalization processing. If the self-discharge amount of each unit cell 11 is specified in advance, ΔI ₂ can be calculated.

  As factors that cause voltage variations in the plurality of unit cells 11, variations in current consumption of the voltage monitoring IC 42 and variations in the self-discharge amount of the unit cells 11 can be considered. Since the voltage monitoring IC 42 operates by receiving power from the corresponding unit cell 11, if the current consumption of the voltage monitoring IC 42 varies, the voltage of the plurality of unit cells 11 varies. Similarly, if the self-discharge amount of the unit cells 11 varies, the voltages of the plurality of unit cells 11 vary.

  Therefore, if the discharge is performed in the equalization process by the amount of variation in the consumption current and the amount of self-discharge described above, the variation described above can be canceled, and the voltage difference ΔVmax (OCV) in the plurality of unit cells 11 is widened. Can be suppressed.

In this embodiment, the value obtained by adding ΔI ₁ and ΔI ₂ is set as the discharge current Ieq in the equalization process, but the present invention is not limited to this. For example, only _one of ΔI ₁ and ΔI ₂ can be the discharge current Ieq in the equalization process.

  If the voltage difference ΔVmax (OCV) is maintained while the ignition switch is on, the cells 11 may be excessively discharged in the equalization process in the second equalization mode. Can be prevented. Further, as shown in FIG. 9, every time the ignition switch is switched from on to off, the voltage difference ΔVmax (OCV) can be reduced stepwise by the equalization process in the first equalization mode.

10: assembled battery (power storage device) 11: single battery (power storage element)
21a, 21b: System main relay 22: Booster circuit 23: Inverter 24: Motor generator 30: Controller 31: Timer 41: Current sensor 42: Voltage monitoring IC (voltage sensor)
43: Equalization circuit (discharge circuit)

Claims (10)

A power storage device that includes a plurality of power storage elements electrically connected in series, and that outputs energy used to travel the vehicle;
A voltage sensor for detecting a voltage of each of the storage elements;
A discharge circuit connected to each power storage element and discharging each power storage element;
A controller for controlling the operation of the discharge circuit,
The controller is
When the ignition switch of the vehicle is off, a first equalization mode is set in which the discharge circuit is operated to equalize the voltages of the plurality of power storage elements,
When the voltage difference in the plurality of power storage elements when the ignition switch is switched from OFF to ON is larger than a threshold value, the discharge circuit is operated while the ignition switch is ON to set the voltages of the plurality of power storage elements. A control device that sets a second equalization mode for equalization. The controller is
Using a timer, measure the time that the ignition switch is turned on continuously,
The second equalization mode is set when the measurement time is a time for generating a voltage difference larger than a voltage difference that can be equalized by the equalization process in the first equalization mode. The control device according to claim 1.   The said controller performs the equalization process in the said 2nd equalization mode based on the detection voltage of the said voltage sensor obtained at the timing when the charging / discharging electric current of the said electrical storage apparatus becomes zero. The control device according to 1 or 2.   The controller operates the discharge circuit so as to maintain the voltage difference when the ignition switch is switched from off to on in the equalization processing in the second equalization mode. The control device according to any one of 1 to 3.   In the second equalization mode, the controller is based on at least one of a self-discharge capacity in the plurality of power storage elements and a current consumption of the power storage element accompanying the equalization process in the second equalization mode. The control device according to claim 4, wherein a discharge current when performing the equalization process is determined. A control method for outputting energy used for traveling of a vehicle and equalizing voltages in a plurality of electrical storage elements electrically connected in series,
Detecting a voltage of each power storage element;
When the ignition switch of the vehicle is off, operating a discharge circuit for discharging each of the storage elements to set a first equalization mode for equalizing the voltages of the plurality of storage elements;
When the voltage difference in the plurality of power storage elements when the ignition switch is switched from OFF to ON is larger than a threshold value, the discharge circuit is operated while the ignition switch is ON to set the voltages of the plurality of power storage elements. Setting a second equalization mode for equalization;
A control method characterized by comprising: Using a timer, measure the time that the ignition switch is turned on continuously,
The second equalization mode is set when the measurement time is a time for generating a voltage difference larger than a voltage difference that can be equalized by the equalization process in the first equalization mode. The control method according to claim 6.   The equalization process in the second equalization mode is performed based on a detection voltage of the voltage sensor obtained at a timing when a charge / discharge current of the power storage device becomes zero. The control method described.   9. The equalization process in the second equalization mode, wherein the discharge circuit is operated so as to maintain the voltage difference when the ignition switch is switched from off to on. The control method as described in any one. The equalization process in the second equalization mode based on at least one of the self-discharge capacity in the plurality of power storage elements and the current consumption of the power storage element associated with the equalization process in the second equalization mode The control method according to claim 9, wherein a discharge current when performing is determined.

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