JP2011155774A - Control device of power storage element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit deterioration of a power storage element subjected to bypass processing when the power storage element is subjected to bypass processing. <P>SOLUTION: A control device of a power storage element includes a discharge circuit (20) connected in parallel with each power storage element (10) and discharging each power storage element, bypass circuits (41, 42, 43) provided corresponding to the power storage elements and performing bypass processing in order to disconnect the corresponding power storage element from the other power storage elements, and controllers (51, 52) which control operations of the discharge circuit and bypass circuits. The controller controls the bypass circuit to perform bypass processing for each power storage element specified according to the deterioration condition, and controls the discharge circuit to discharge the power storage element subjected to bypass processing when the value indicating the storage state of the power storage element subjected to bypass processing is larger than a reference value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device that performs control for removing a degraded storage element from a connection with another storage element among a plurality of electrically connected storage elements.

  In an assembled battery in which a plurality of unit cells are electrically connected in series, when only one of the unit cells is deteriorated, a technique for removing the deteriorated unit cell from the current path of the assembled battery has been proposed ( For example, see Patent Documents 1 and 2). In the technique described in Patent Document 1, in an assembled battery in which a plurality of battery modules are connected in series, a bypass circuit is connected in parallel to each battery module. The current flows through the bypass circuit corresponding to the battery module.

JP 2008-288109 A JP 2004-015924 A Japanese Patent Laid-Open No. 10-14002 Japanese Patent Laid-Open No. 10-32936 JP 2007-323999 A JP 2008-192607 A JP 2008-253129 A JP 2006-033961 A JP 2009-020991 A JP 2002-272010 A

  If the process of removing the deteriorated unit cell from the current path of the assembled battery (referred to as a bypass process) is performed, it is possible to prevent the deterioration of the unit cell due to charging / discharging of the assembled battery.

  On the other hand, when the bypass process of the single cell is performed while the charge state of the single cell (for example, SOC: State Of Charge) is high, deterioration of the single cell subjected to the bypass process may easily progress. That is, the higher the SOC of the unit cell, the greater the deterioration rate of the unit cell when the unit cell is left by bypass processing.

  Therefore, an object of the present invention is to provide a control device that can suppress deterioration of a bypassed power storage element when performing a bypass process of the power storage element.

  1st invention of this application is a control apparatus which controls the input / output of the some electrical storage element electrically connected in series, Comprising: The discharge circuit connected in parallel with respect to each electrical storage element and discharging each electrical storage element A bypass circuit that is provided corresponding to each power storage element, performs a bypass process for removing the corresponding power storage element from connection with another power storage element, and a controller that controls the operation of the discharge circuit and the bypass circuit. Have. Here, the controller causes the power storage element specified according to the deterioration state of each power storage element to perform bypass processing by the bypass circuit, and a value indicating the power storage state of the power storage element subjected to the bypass processing is a reference value. When the value is larger than the value, the storage element subjected to the bypass process is caused to discharge by the discharge circuit.

  Here, the bypassed storage element can be discharged by the discharge circuit until the value indicating the storage state reaches the reference value. Thereby, deterioration of the electrical storage element by maintaining an electrical storage element in the state where the value which shows an electrical storage state remains high can be suppressed more.

  On the other hand, when the value indicating the storage state is smaller than the reference value, discharge by the discharge circuit can be prohibited for the bypassed storage element. In addition, when the value indicating the storage state is smaller than the reference value and the difference between the value indicating the storage state and the reference value is equal to or greater than a predetermined amount, the storage element that is the target of the bypass process can be charged.

  In addition, when the performance of other power storage elements excluding the power storage element that is the target of the bypass process does not satisfy the required performance, the number of power storage elements that are the target of the bypass process can be limited. Thereby, the bypass process of an electrical storage element can be performed, satisfy | filling required performance.

  The power storage element can include a plurality of power generation elements. For example, the above-described bypass processing and discharge can be performed on a battery module (storage element) in which a plurality of single cells (power generation elements) are electrically connected in series. Moreover, as an electrical storage element, a lithium ion battery (secondary battery) can be used, for example.

  A second invention of the present application is a control method for controlling input / output of a plurality of power storage elements electrically connected in series, and for other power storage elements specified according to the deterioration state of each power storage element, A bypass process for removing from the connection with the power storage element is performed, and when the value indicating the power storage state of the bypassed power storage element is greater than a reference value, the bypassed power storage element is discharged.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the electrical storage element in a degradation state deteriorates further by charging / discharging by performing a bypass process with respect to the electrical storage element in a degradation state. Moreover, in the bypassed power storage element, when the value indicating the power storage state is larger than the reference value, the power storage element can be discharged to suppress deterioration of the power storage element due to maintaining a high power storage state. .

It is a figure which shows the structure of the battery system in Example 1 of this invention. 4 is a flowchart illustrating a bypass process for a single battery in the battery system according to the first embodiment. It is a figure which shows the relationship between internal resistance and SOC in a cell. It is a figure which shows the internal resistance and temperature relationship in a cell. 4 is a flowchart illustrating a process for determining whether or not a single battery can be used in the battery system according to the first embodiment. It is a figure which shows the relationship between five single cells and the deterioration amount of each single cell. It is a flowchart which shows the process which controls charging / discharging of the cell by which the bypass process was performed in the battery system of Example 1. FIG. It is a figure which shows the deterioration rate in a single battery, and the relationship of SOC. It is a figure which shows the relationship between the discharge time and SOC in a single battery.

  Examples of the present invention will be described below.

  A battery system that is Embodiment 1 of the present invention will be described. FIG. 1 is a diagram showing the configuration of the battery system of this example.

  The plurality of single cells (electric storage elements) 10 are electrically connected in series to form an assembled battery. The number of the single cells 10 constituting the assembled battery can be appropriately set based on the output required for the assembled battery. As the unit cell 10, 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. In this embodiment, all the unit cells 10 are electrically connected in series, but the unit cells 10 electrically connected in parallel may be included.

  The assembled battery of the present embodiment can be mounted on, for example, a vehicle, and examples of the vehicle include a hybrid vehicle and an electric vehicle. A hybrid vehicle is a vehicle provided with an internal combustion engine and a fuel cell in addition to an assembled battery as a power source of the vehicle. An electric vehicle is a vehicle that travels using only the output of an assembled battery.

  A positive electrode terminal and a negative electrode terminal of the assembled battery are connected to a load via a wiring 44. When the assembled battery is mounted on a vehicle, a booster circuit can be used as a load. Specifically, the booster circuit boosts the output voltage of the assembled battery and supplies it to the inverter. The inverter converts DC power output from the booster circuit into AC power and outputs the AC power to a motor / generator (for example, a three-phase AC motor), which generates kinetic energy for running the vehicle in the motor / generator. .

  On the other hand, kinetic energy generated during braking of the vehicle is converted into electric energy (AC power) by a motor / generator and supplied to an inverter. The inverter converts AC power from the motor / generator into DC power and supplies it to the booster circuit. The step-up circuit steps down the output voltage of the inverter and supplies it to the assembled battery.

  It is also possible to omit the booster circuit and connect the assembled battery and the inverter directly. Further, when the assembled battery is mounted on a vehicle, power can be supplied to the assembled battery from a power source (external power source) arranged outside the vehicle.

  A discharge circuit 20 is connected in parallel to each unit cell 10, and the discharge circuit 20 is used to adjust the SOC of each unit cell 10 as will be described later. The discharge circuit 20 can be used to equalize the voltage of the unit cell 10 when the unit cell 10 is connected to another unit cell 10. The SOC is a value (ratio) indicating the charged state (power storage state) of the unit cell 10. Note that any parameter other than the SOC can be used as long as the value indicates the state of charge of the unit cell 10.

  The discharge circuit 20 has a switch 21 and a resistor 22, and the switch 21 is turned on and off by an energization control circuit 52. If the switch 21 is on, the corresponding cell 10 is discharged.

  In addition, a voltage sensor 31 is connected to each unit cell 10, and the voltage sensor 31 outputs information on the voltage value of each unit cell 10 to the deterioration state determination circuit 51. Thereby, the deterioration state determination circuit 51 acquires the voltage value of the single battery 10. Each unit cell 10 is provided with a temperature sensor 32, and the temperature sensor 32 outputs information on the temperature of each unit cell 10 to the deterioration state determination circuit 51. Thereby, the deterioration state determination circuit 51 can acquire the temperature of each unit cell 10.

  The temperature sensor 32 only needs to be able to detect the temperature of the unit cell 10 directly or indirectly. As a configuration for directly detecting the temperature of the unit cell 10, for example, the temperature sensor 32 can be brought into contact with the outer surface of the unit cell 10, or the temperature sensor 32 can be arranged inside the unit cell 10. As a configuration for indirectly detecting the temperature of the unit cell 10, for example, the temperature sensor 32 can be disposed in the vicinity of the unit cell 10 and away from the outer surface of the unit cell 10.

  In the present embodiment, the temperature sensor 32 is provided for each unit cell 10, but the present invention is not limited to this. That is, the number of temperature sensors 32 can be made smaller than the number of unit cells 10 constituting the assembled battery. For example, only one temperature sensor 32 can be provided for the assembled battery. Further, the temperature of the plurality of single cells 10 can be collectively detected using one temperature sensor 32.

  The current sensor 33 detects information related to the current value flowing through the assembled battery (unit cell 10), and outputs the detection result to the deterioration state determination circuit 51. Switches (part of a bypass circuit) 41 and 42 are connected to the positive terminal and the negative terminal of each unit cell 10, respectively. The switch 41 is switched between a state connected to the positive terminal of the unit cell 10 and a state connected to the bypass line (a part of the bypass circuit) 43. It is controlled by a control signal output from the control circuit 52. The switch 42 is switched between a state connected to the negative electrode terminal of the unit cell 10 and a state connected to the bypass line 43, and the switching of the switch 42 is output from the energization control circuit 52. Controlled by a control signal.

  When the switches 41 and 42 are respectively connected to the positive electrode terminal and the negative electrode terminal of the unit cell 10, the state in which the unit cell 10 is allowed to be energized, in other words, the state in which the unit cell 10 is allowed to be charged and discharged. Become. Further, when the switches 41 and 42 are connected to the bypass line 43, the energization of the unit cell 10 is prohibited, in other words, the unit cell 10 is in a bypass process.

  As will be described later, the deterioration state determination circuit 51 determines the deterioration state of the unit cell 10 based on the outputs of the voltage sensor 31, the temperature sensor 32, and the current sensor 33. Specifically, the deterioration state determination circuit 51 determines the deterioration state of the unit cell 10 by calculating the amount of deterioration of the unit cell 10.

  The deterioration state determination circuit 51 outputs information related to the deterioration state of each unit cell 10 to the energization control circuit 52. The energization control circuit 52 switches the switches 41 and 42 on and off based on information from the deterioration state determination circuit 51. Further, the energization control circuit 52 switches on and off the switch 21 in each discharge circuit 20 based on the information from the deterioration state determination circuit 51.

  Next, the bypass process of the cell 10 in the present embodiment will be described with reference to the flowchart shown in FIG.

  In step S <b> 101, the deterioration state determination circuit 51 acquires the voltage value of each unit cell 10 based on the output of the voltage sensor 31 connected to each unit cell 10. Further, the deterioration state determination circuit 51 acquires the current value of the assembled battery (each unit cell 10) based on the output of the current sensor 33, and each based on the output of the temperature sensor 32 provided in each unit cell 10. The temperature of the cell 10 is acquired.

  In step S102, the deterioration state determination circuit 51 calculates the internal resistance and SOC of each unit cell 10 based on the voltage value and current value acquired in step S101. In step S103, the deterioration state determination circuit 51 determines the deterioration state of each unit cell 10 based on the temperature acquired in step S101 and the SOC and internal resistance calculated in step S102.

  In this embodiment, the deterioration state of the unit cell 10 is determined based on the internal resistance. Specifically, the internal resistance can be calculated based on the voltage value and current value of each unit cell 10. Here, since the internal resistance of the unit cell 10 varies depending on the SOC and temperature, it is necessary to correct the internal resistance calculated from the voltage value and the current value according to the current SOC and temperature of the unit cell 10. is there.

  FIG. 3 shows a relationship (example) between the internal resistance and the SOC in the unit cell 10. Generally, the internal resistance tends to decrease as the SOC increases. FIG. 4 shows the relationship (example) between the internal resistance and the temperature in the unit cell 10. Generally, the internal resistance tends to decrease as the temperature increases. The deterioration state determination circuit 51 corrects the internal resistance using the information shown in FIGS. 3 and 4 and determines the deterioration state of the unit cell 10.

  In this embodiment, the deterioration state of the unit cell 10 is determined based on the internal resistance of the unit cell 10, but the present invention is not limited to this. That is, a parameter that can determine the deterioration state of the unit cell 10 is set in advance, and the deterioration state of the unit cell 10 may be determined based on this parameter. For example, the frequency at which the voltage of each unit cell 10 exceeds the threshold value is used as the parameter, and the deterioration state of the unit cell 10 can be determined based on the parameter indicating this frequency. In this case, it can be determined that the deterioration of the unit cell 10 progresses as the frequency at which the voltage of the unit cell 10 exceeds the threshold increases.

  In step S104, the deterioration state determination circuit 51 determines whether or not the unit cell 10 can be used based on the deterioration state determined in step S103. In the process of step S104, whether or not the single battery 10 can be used is determined from the viewpoint of preventing the deterioration of the single battery 10 due to charging and discharging of the assembled battery. Details of the processing in step S104 will be described later (see FIG. 5).

  The deterioration state determination circuit 51 transmits information on whether or not the unit cell 10 can be used to the energization control circuit 52. Specifically, the deterioration state determination circuit 51 transmits information on the usable unit cell 10 and information on the unit cell 10 whose use is prohibited to the energization control circuit 52.

  In step S <b> 105, the energization control circuit 52 identifies the unit cell 10 whose use is prohibited based on the information from the deterioration state determination circuit 51, and prohibits the unit cell 10 from being energized. Specifically, the energization control circuit 52 performs bypass processing on the prohibited cell 10 by connecting switches 41 and 42 corresponding to the prohibited cell 10 to the bypass line 43. Thereby, charging / discharging to the single cell 10 determined to be deteriorated is prohibited, and further deterioration of the single cell 10 can be prevented.

  Next, the process of step S104 described above will be described using the flowchart shown in FIG.

  In step S201, the deterioration state determination circuit 51 determines whether or not the deterioration amount of each unit cell 10 is larger than a threshold value. The deterioration amount is an index indicating the deterioration state of the unit cell 10. Here, for example, the internal resistance described in FIG. 2 (step S103) can be used as the deterioration amount.

  In the present embodiment, an average value of the deterioration amount is calculated based on the deterioration amount of all the single cells 10, and a value obtained by adding an allowable value to the calculated average value is used as a threshold value for the deterioration amount. The threshold value is not limited to a value obtained by adding the average value and the allowable value, and can be set as appropriate. For example, an average value of the deterioration amount can be used as the threshold value.

  In step S201, if there is a unit cell 10 having a deterioration amount larger than the threshold value, the process proceeds to step S203, and if not, the process proceeds to step S202. In the process of FIG. 5, it is assumed that there are n unit cells 10 that exhibit a deterioration amount larger than the threshold value.

  The process of step S201 will be specifically described with reference to FIG. FIG. 6 shows the deterioration amount (one example) in the No. 1 to No. 5 unit cells 10. For the cells 10 of Nos. 2, 4, and 5, the amount of deterioration exceeds the average value. The average value is an average value of deterioration amounts in the five unit cells 10. Moreover, the deterioration amount of the cells 10 of No. 2 and 5 is larger than a threshold value (a value obtained by adding an allowable value to the average value). Here, the allowable value can be set as appropriate, and the allowable value may not be provided.

  In the example shown in FIG. 6, the No. 2 and No. 5 cells 10 are specified in the process of step S201, and the processes after step S203 are performed. Here, it is judged that the No. 1, 3, 4 unit cells 10 can be used.

  In step S202, the deterioration state determination circuit 51 determines that all the unit cells 10 are usable, and ends this process. On the other hand, the deterioration state determination circuit 51 sets the count i to 0 in step S203, increments the count i in step S204, and proceeds to step S205.

  In step S205, the deterioration state determination circuit 51 determines the performance of the remaining unit cells 10 (N−i unit cells 10) when the i unit cells 10 are removed from the assembled battery from the larger deterioration amount side. to decide. Here, “N” is the total number of unit cells 10 constituting the assembled battery.

  For example, when the count i is “1”, the performance of the remaining unit cells 10 when the unit cell 10 having the largest deterioration amount is excluded is determined. In the example shown in FIG. 6, the performance when the No. 1, 3 to 5 unit cells 10 are used is determined by removing the No. 2 unit cell 10 from the No. 1 to 5 unit cells 10. Here, as the performance, for example, the output performance in the remaining unit cell 10 can be cited.

  In step S206, the deterioration state determination circuit 51 determines whether or not the performance of the cell 10 determined in step S205 satisfies a predetermined required performance. For example, it is determined whether or not the output when the remaining unit cells 10 excluding i unit cells 10 are higher than the output required for traveling of the vehicle. If it is determined in step S206 that only the remaining unit cells 10 (N-i unit cells 10) do not satisfy the required performance, the process proceeds to step S207, and if not, the process proceeds to step S208.

  In step S207, the deterioration state determination circuit 51 determines that “i−1” unit cells 10 are prohibited from use, and ends this process. For example, when 4 (i = 4) unit cells 10 are excluded, if it is determined that the remaining unit cells 10 alone do not satisfy the required performance, it is determined that three unit cells 10 are prohibited from use. Here, the three unit cells 10 become three unit cells 10 counted from the side with the larger deterioration amount.

  In step S208, the deterioration state determination circuit 51 determines whether or not the count i is n. As described in the process of step S201, n is the number of single cells 10 that exhibit a deterioration amount that is greater than the threshold value. If the count i is not n, the process returns to step S204. If the count i is n, the process proceeds to step S209.

  In the processing from step S204 to step S208, as long as the unit cell 10 satisfies the required performance, the unit cells 10 having a deterioration amount larger than the threshold value are removed in order from the larger deterioration amount side. In step S209, the deterioration state determination circuit 51 determines that n unit cells 10 are prohibited from use, and ends this process. In the process of step S209, it is determined that all the unit cells 10 having a deterioration amount larger than the threshold value are prohibited from being used.

  According to the process described with reference to FIG. 5, the bypass process can be performed for only an appropriate number of unit cells 10 according to the required performance required for the assembled battery. In other words, it is possible to suppress the deterioration of the unit cell 10 while ensuring the required performance for the assembled battery.

  Next, charge / discharge control of the unit cell 10 that has been bypassed will be described with reference to the flowchart shown in FIG. The process shown in FIG. 7 is performed on each unit cell 10 subjected to the bypass process.

  In step S301, the deterioration state determination circuit 51 detects the voltage of the unit cell 10 based on the output of the voltage sensor 31 connected to the unit cell 10 on which the bypass process has been performed. In step S302, the SOC of the bypassed cell 10 is calculated (estimated) based on the detected voltage value.

  In step S303, the deterioration state determination circuit 51 determines whether or not the SOC calculated in step S302 is lower than the first reference value. The first reference value is a value indicating a predetermined SOC, and can be set as appropriate based on the correspondence between the deterioration rate of the single battery 10 and the SOC. FIG. 8 shows the correspondence (example) between the deterioration rate and the SOC in the single battery 10. As shown in FIG. 8, the higher the SOC of the unit cell 10, the higher the deterioration rate of the unit cell 10. Therefore, from the viewpoint of suppressing the deterioration rate of the unit cell 10, the SOC as the first reference value can be set in advance.

  In step S303, if the SOC calculated in step S302 is lower than the first reference value, the process proceeds to step S305, and if not, the process proceeds to step S304. In step S304, the energization control circuit 52 discharges the bypassed unit cell 10 by switching the switch 21 of the discharge circuit 20 from OFF to ON. At this time, the discharge of the unit cell 10 is performed until the SOC of the unit cell 10 reaches the first reference value.

  Here, a correspondence relationship between the discharge time of the unit cell 10 and the SOC of the unit cell 10 can be obtained in advance, and a map showing the correspondence relationship can be stored in the memory. FIG. 9 shows a correspondence relationship (example) between the discharge time and the SOC in the single battery 10. Thereby, the energization control circuit 52 can make the SOC of the unit cell 10 reach the first reference value by monitoring the discharge time of the unit cell 10.

  In the process of step S304 in the present embodiment, the SOC of the bypassed cell 10 is lowered to the first reference value, but the present invention is not limited to this. As shown in FIG. 8, since the deterioration rate of the single cell 10 can be reduced simply by reducing the SOC of the single cell 10, the single cell 10 is discharged and the SOC of the single cell 10 is simply reduced. But you can. That is, it is not necessary to reduce the SOC of the bypassed cell 10 to the first reference value.

  In step S305, the deterioration state determination circuit 51 determines whether or not the SOC calculated in step S302 is lower than the second reference value. The second reference value is a value indicating a predetermined SOC, and is a value lower than the first reference value as shown in FIG. If the SOC of the unit cell 10 is excessively lowered, a malfunction may occur. Therefore, from this viewpoint, the second reference value is set.

  For example, in a structure in which a plurality of unit cells 10 are arranged in one direction and the plurality of unit cells 10 are constrained from both ends in the arrangement direction, due to a change in volume (volume decrease) of the unit cells 10 due to a decrease in SOC, There is a risk that the binding force of the unit cell 10 is reduced. In this case, the second reference value can be set as appropriate from the viewpoint of suppressing a decrease in the binding force of the unit cell 10.

  In step S305, if the calculated SOC is lower than the second reference value, the process proceeds to step S307, and if not, the process proceeds to step S306. In step S306, the bypassed cell 10 is left unattended. In other words, the energization control circuit 52 does not discharge the unit cell 10 subjected to the bypass process using the discharge circuit 20.

  In step S <b> 307, the energization control circuit 52 reconnects the bypassed cell 10 with another cell 10. Specifically, the switches 41 and 42 corresponding to the bypassed unit cell 10 are switched from the connection to the bypass line 43 to the connection to the unit cell 10. Thereby, it becomes possible to charge / discharge with respect to the cell 10 by which the bypass process was carried out.

  In step S308, the energization control circuit 52 charges the assembled battery and raises the SOC of the bypassed unit cell 10 to the first reference value. Here, the correspondence relationship between the charging time and the SOC in the unit cell 10 can be obtained in advance, and a map showing the correspondence relationship can be stored in the memory. Thus, if the charging time is monitored, the SOC of the unit cell 10 can be estimated using the map, and the SOC of the unit cell 10 can reach the first reference value. Note that, after the charging is completed, the voltage value of the unit cell 10 may be detected and the SOC may be calculated (estimated) again.

  In the process of step S308, the SOC of the unit cell 10 is increased to the first reference value, but the present invention is not limited to this. That is, the SOC of the unit cell 10 may be increased by charging. For example, the SOC of the unit cell 10 can be increased to an arbitrary value located between the first reference value and the second reference value.

  On the other hand, after performing the process of step S308, the bypass process can be performed again on the unit cell 10 whose SOC has reached the first reference value.

  According to the present embodiment, the unit cell 10 determined to be in a deteriorated state is removed from the charging / discharging current path by the bypass process, thereby preventing the unit cell 10 from deteriorating due to charging / discharging. can do. Further, when the SOC of the unit cell 10 subjected to the bypass process is higher than the first reference value, the SOC is maintained higher than the first reference value by discharging the unit cell 10 and lowering the SOC. Therefore, the deterioration of the unit cell 10 can be suppressed.

  In addition, in a present Example, although it becomes the structure which can perform a bypass process with respect to each cell 10, it does not restrict to this. For example, you may make it perform a bypass process with respect to the battery module (electric storage element) to which the several cell 10 was connected in series. And the discharge circuit 20 can be connected in parallel with respect to each battery module. Here, the plurality of battery modules are electrically connected in series.

  On the other hand, the unit cell 10 on which the bypass process has been performed can be connected again to the unit cell 10 on which the bypass process has not been performed, depending on the deterioration state of the unit cell 10 on which the bypass process has not been performed. Specifically, when the deterioration state of the bypassed cell 10 and the deterioration state of the cell 10 that has not been bypassed are substantially equal, the bypassed cell 10 has been bypassed. It is possible to perform charging / discharging by connecting to a non-single cell 10. Thereby, in all the single cells 10 constituting the assembled battery, it is possible to continue using the assembled batteries until all the single cells 10 reach the end of their lives while suppressing variation in the deterioration state.

10: single cell (electric storage element) 20: discharge circuit 21: switch 22: resistor 31: voltage sensor 32: temperature sensor 33: current sensor
41, 42: Switch (part of bypass circuit)
43: Bypass line (part of bypass circuit)
51: Degradation state determination circuit (part of controller)
52: Energization control circuit (part of controller)

Claims (12)

A control device for controlling input / output of a plurality of power storage elements electrically connected in series,
A discharge circuit connected in parallel to each of the storage elements, and discharging each of the storage elements;
A bypass circuit that is provided corresponding to each of the storage elements, and performs a bypass process for removing the corresponding storage element from connection with the other storage element;
A controller for controlling the operation of the discharge circuit and the bypass circuit,
The controller is
For the storage element identified according to the deterioration state of each storage element, the bypass process by the bypass circuit is performed,
When the value indicating the power storage state of the power storage element subjected to the bypass process is greater than a reference value, the power storage element subjected to the bypass process is discharged by the discharge circuit,
A control device characterized by that.   2. The controller according to claim 1, wherein the controller causes the storage element that has been bypassed to discharge by the discharge circuit until a value indicating the storage state reaches the reference value. Control device.   2. The controller according to claim 1, wherein when the value indicating the power storage state is smaller than the reference value, the controller prohibits the discharge by the discharge circuit from the bypassed power storage element. Control device.   When the value indicating the power storage state is smaller than the reference value and the difference between the value indicating the power storage state and the reference value is equal to or greater than a predetermined amount, the controller determines the power storage element to be subjected to the bypass process. The control device according to claim 1, wherein charging is performed.   The controller limits the number of power storage elements to be bypassed when the performance of the other power storage elements excluding the power storage elements to be bypassed does not satisfy the required performance. The control device according to any one of claims 1 to 4.   The control device according to claim 1, wherein the power storage element includes a plurality of power generation elements.   The control device according to claim 1, wherein the storage element is a lithium ion battery. A control method for controlling input / output of a plurality of power storage elements electrically connected in series,
For the power storage element identified according to the deterioration state of each power storage element, perform a bypass process to disconnect from the other power storage elements,
When the value indicating the storage state of the bypassed storage element is larger than a reference value, the bypassed storage element is discharged.
A control method characterized by that.   9. The control method according to claim 8, wherein the bypassed storage element is discharged until a value indicating the storage state reaches the reference value.   The control method according to claim 8, wherein when the value indicating the storage state is smaller than the reference value, discharging of the bypassed storage element is prohibited.   When the value indicating the power storage state is smaller than the reference value and the difference between the value indicating the power storage state and the reference value is equal to or greater than a predetermined amount, the power storage element to be subjected to the bypass process is charged. The control method according to claim 8, wherein the control method is performed. 9. The number of power storage elements to be bypassed is limited when the performance of the other power storage elements excluding the power storage elements to be bypassed does not satisfy required performance. The control method according to any one of 11 to 11.

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