JP5870907B2 - Power storage system - Google Patents

Description

  The present invention relates to a power storage system that charges a power storage block while confirming an operating state of the current circuit breaker in a power storage block in which a plurality of power storage elements each having a current circuit breaker are connected in parallel.

  In the assembled battery described in Patent Document 1, in a configuration in which a plurality of batteries are connected in parallel, a fuse (current breaker) is connected to each of the cells connected in parallel. The fuse cuts off the current path by fusing when an excessive current flows. In the technique described in Patent Document 2, the operation of a current interrupt mechanism included in the battery is detected based on a change in the internal resistance of the battery.

JP 2008-220110 A Japanese Patent Application Laid-Open No. 08-017477

  In a configuration in which a plurality of batteries are connected in parallel, the value of the current flowing through the battery in which the current breaker is not operating varies depending on the number of activations of the current breaker. Specifically, when the number of operation of the current breaker increases, the value of the current flowing through the battery in which the current breaker is not operating increases, and the current load on the battery increases. Therefore, in order to control charging / discharging of the battery, it is necessary to detect the operation of the current breaker. In the present invention, the operation of the current breaker is detected by a method different from the technique described in Patent Document 2.

  The power storage system according to the first invention of the present application includes a power storage device having a plurality of power storage blocks connected in series, a voltage sensor for detecting a voltage value of each power storage block, and each power storage based on a detection result of the voltage sensor. A controller for estimating the SOC of the block. The power storage block has a plurality of power storage elements connected in parallel, and each power storage element is provided with a current breaker that interrupts a current path inside each power storage element.

  The controller determines the breaking state of the current breaker using the correspondence relationship between the first ratio and the second ratio. Here, the first ratio is a ratio between the amount of change in SOC in each power storage block and the amount of change in SOC in a power storage block that does not include a current breaker in a cut-off state. The second ratio is a ratio between the total number of power storage elements constituting the power storage block and the total number of current breakers that are not in a cut-off state.

After starting the charging of the power storage device, the controller changes the total number of current breakers in the cutoff state when calculating the second ratio from the larger side to the smaller side in accordance with the increase in the SOC of the power storage block. However, the interruption state is determined using the correspondence relationship. Here, every time it is determined that the current breaker is not in the cut-off state, the current value for charging the power storage device is increased.

  The determination as to whether or not the current breaker is in a cut-off state can be made using the correspondence relationship described above. In the power storage block, since a plurality of power storage elements are connected in parallel, if the current breaker is cut off, the number of power storage elements that are energized decreases, and the full charge capacity of the power storage block decreases. If the full charge capacity of the power storage block decreases, the SOC of the power storage block changes. Therefore, if the first ratio described above is calculated, the total number of current breakers in the cut-off state can be specified.

  Here, the SOC of the power storage block is estimated based on the detection result by the voltage sensor, but if the detection error by the voltage sensor is included, the amount of change in the SOC in the power storage block changes. In particular, when the change amount of the SOC is small, the influence due to the detection error of the voltage sensor becomes large, and it becomes difficult to specify the total number of current breakers in the breaking state based on the first ratio. On the other hand, if the total number of current breakers in the interrupted state is large, the influence of the detection error of the voltage sensor is reduced, and the total number of current breakers in the interrupted state can be easily specified based on the first ratio.

  Therefore, in the first invention of this application, the interruption state is determined while changing the total number of current breakers in the interruption state from the larger side to the smaller side in accordance with the increase in the SOC of the power storage block. If the SOC of the power storage block increases, the amount of change in SOC can be increased, and the influence of detection errors on the amount of change in SOC can be reduced. Accordingly, it becomes easier to specify the total number of current breakers in the breaking state based on the first ratio.

  According to the first invention of the present application, the power storage device can be charged while checking the total number of current breakers in a cut-off state. And whenever it determines with a current circuit breaker not being in the interruption | blocking state, charging time can be shortened by raising a charging current value.

  Here, when charging of the power storage device is started, the allowable current value of the power storage element can be set as the charging current value of the power storage device. As a result, even if only one power storage element is energized in the power storage block, only a charging current having an allowable current value flows through the power storage element. Current flow can be suppressed.

  Each time it is determined that the current breaker is not in the breaker state, the charge current value of the power storage device is set so that the charge current of the allowable current value flows to the power storage element corresponding to the current breaker that is not in the breaker state. can do. If it is determined that the current breaker is not in the breaking state, a charging current having an allowable current value can be supplied to the power storage element corresponding to the current breaker that is not in the breaking state. When the charging of the power storage device is started, when the allowable current value of the power storage element is set as the charging current value of the power storage device, the charge of the power storage device is determined each time it is determined that the current breaker is not in the cut-off state. The current value can be increased. Thereby, the charge time of an electrical storage apparatus can be shortened.

  On the other hand, when it is determined that the current breaker is in the cut-off state, the charging current value of the power storage device can be fixed. When it is determined that the current breaker is in the cut-off state, if the charging current value of the power storage device is increased, an excessive current flows through the power storage element. Therefore, by fixing the charging current value of the power storage device, it is possible to suppress an excessive current from flowing through the power storage element.

  A power storage system according to a second invention of the present application includes a power storage device having a plurality of power storage blocks connected in series, a voltage sensor for detecting a voltage value of each power storage block, and a power storage system based on a detection result of the voltage sensor. A controller for estimating the SOC of the block. The power storage block has a plurality of power storage elements connected in parallel, and each power storage element is provided with a current breaker that interrupts a current path inside each power storage element.

  The controller determines the breaking state of the current breaker using the correspondence relationship between the first ratio and the second ratio. Here, the first ratio is a ratio between the amount of change in SOC in each power storage block and the amount of change in SOC in a power storage block that does not include a current breaker in a cut-off state. The second ratio is a ratio between the total number of power storage elements constituting the power storage block and the total number of current breakers that are not in a cut-off state.

After starting the charging of the power storage device, the controller changes the total number of current breakers in the cutoff state when calculating the second ratio from the larger side to the smaller side in accordance with the increase in the SOC of the power storage block. However, the interruption state is determined using the correspondence relationship. Here, every time it is determined that the current breaker is not in the cut-off state, the amount of decrease in the full charge capacity in the power storage block is changed.

  According to the second invention of the present application, as in the first invention of the present application, it is possible to determine the total number of current breakers in the breaking state while considering the detection error by the voltage sensor. Here, the amount of decrease in the full charge capacity in the power storage block changes according to the total number of current breakers in the cut-off state. For this reason, the full charge capacity decreases every time when the interrupting state is determined while changing the total number of current breakers in the breaking state from the large side to the small side, and it is determined that the current breaker is not in the breaking state. By changing the amount, the reduction amount of the full charge capacity can be brought close to the actual reduction amount.

  Specifically, the amount of decrease in the full charge capacity can be reduced as the total number of current breakers in the interrupted state is reduced by the determination of the interrupted state. As the total number of current breakers in the cut-off state becomes smaller, the amount of decrease in the full charge capacity is less likely to increase. As described above, the amount of decrease in the full charge capacity can be reduced. Usually, the storage element can be used until the amount of decrease in the full charge capacity reaches the allowable amount. Therefore, the amount of decrease in the full charge capacity decreases as the total number of current breakers in the interrupted state decreases. Thus, the power storage device can be continuously charged.

  When the charging of the power storage device is started, the charging current value of the power storage device can be set so that the allowable current value flows through all the power storage elements constituting the power storage block. Thereby, the charge time of an electrical storage apparatus can be shortened.

  When calculating the decrease amount of the full charge capacity, the correspondence relationship between the charge time and the decrease amount of the full charge capacity can be used. For this reason, if the charging time of the power storage device is measured, the amount of decrease in the full charge capacity can be calculated. The correspondence relationship between the charging time and the amount of decrease in the full charge capacity can be obtained in accordance with the total number of current breakers in the breaking state.

  The determination of the breaking state of the current breaker can be performed based on the following formula (I).

  In the above formula (I), ΔSOC_b is the amount of change in the SOC in each power storage block, and ΔSOC_r is the amount of change in the SOC in the power storage block that does not include the current breaker in the cut-off state. N is the total number of power storage elements constituting the power storage block, and m is the total number of current circuit breakers in the cutoff state.

  Normally, a plurality of power storage blocks include a power storage block including a current breaker that is in a cut-off state and a power storage block including a current breaker that is not in a cut-off state. For this reason, by comparing the two power storage blocks, the total number of current breakers in the cut-off state can be specified.

  The determination of the breaking state of the current breaker can be made based on the following formula (II).

  In the above formula (II), ΔSOC_b is the amount of change in SOC in each power storage block, and ΔSOC_r is the amount of change in SOC in the power storage block that does not include a current breaker that is in a cut-off state. n, n−k (1 <k <n) is the number of times the power storage device has been charged, N is the total number of power storage elements constituting the power storage block, and m is a current breaker in a cut-off state. The total number of

  According to the above formula (II), since the ratio of ΔSOC_b (n) and ΔSOC_b (n−1) is calculated, the full charge capacity in the power storage block indicating ΔSOC_b can be canceled. Further, according to the above formula (II), since the ratio of ΔSOC_r (n) and ΔSOC_r (n−1) is calculated, the full charge capacity in the power storage block indicating ΔSOC_r can be canceled. As a result, even if variations occur in the full charge capacities of the two power storage blocks, this variation can be ignored in calculating several meters.

  Further, according to the above formula (II), since the ratio of ΔSOC_b (n) and ΔSOC_r (n) is calculated, the charge amount in the nth external charge can be canceled. Further, according to the above formula (II), since the ratio of ΔSOC_b (n−1) and ΔSOC_r (n−1) is calculated, it is possible to cancel the charge amount in the “n−1” th external charge. it can. Thereby, even if the charge amount in the n-th time and the “n−1” -th time is different from each other, the variation in the charge amount can be ignored in calculating the number m.

  As the current breaker, a fuse, a PTC element, or a current cutoff valve can be used. The fuse interrupts the current path by fusing. The PTC element cuts off the current path due to an increase in resistance accompanying a temperature rise. The current cutoff valve is deformed in response to an increase in the internal pressure of the power storage element and cuts off the current path.

It is a figure which shows the structure of the battery system which is Example 1. FIG. 1 is a diagram illustrating a configuration of an assembled battery in Example 1. FIG. 1 is a diagram showing a configuration of a single cell in Example 1. FIG. It is a figure explaining the area | region which can determine the number of interruption | blocking, and the area | region where determination of the number of interruption | blocking is impossible. In Example 1, it is a flowchart which shows the process which performs external charge of an assembled battery. In Example 1, it is a figure explaining the change of the charge rate in external charging. FIG. 6 is a diagram illustrating a configuration of a battery system that is a modification of the first embodiment. In the modification of Example 1, it is a figure which shows the structure of an assembled battery. In Example 3, it is a flowchart which shows the process which performs external charge of an assembled battery. In Example 3, it is a figure which shows the relationship between charging time and a capacity | capacitance fall amount. It is a figure which shows the relationship between a charge rate and a capacity | capacitance fall rate. In Example 3, it is a figure which shows the behavior of a capacity | capacitance fall amount (assumed value).

  Examples of the present invention will be described below.

  A battery system (corresponding to the power storage system of the present invention) that is Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a battery system. The battery system of this embodiment is mounted on a vehicle.

  Vehicles include hybrid cars and electric cars. The hybrid vehicle includes an engine or a fuel cell as a power source for running the vehicle in addition to the assembled battery described later. The electric vehicle includes only an assembled battery described later as a power source for running the vehicle.

  A system main relay SMR-B is provided on the positive electrode line PL connected to the positive electrode terminal of the assembled battery (corresponding to the power storage device of the present invention) 10. System main relay SMR-B is switched between ON and OFF by receiving a control signal from controller 40. A system main relay SMR-G is provided on the negative electrode line NL connected to the negative electrode terminal of the assembled battery 10. System main relay SMR-G is switched between on and off by receiving a control signal from controller 40.

  A system main relay SMR-P and a current limiting resistor R are connected in parallel to the system main relay SMR-G. System main relay SMR-P and current limiting resistor R are connected in series. System main relay SMR-P is switched between on and off by receiving a control signal from controller 40.

  The current limiting resistor R is used to suppress an inrush current from flowing through the capacitor C when the assembled battery 10 is connected to a load (specifically, a booster circuit 31 described later). Capacitor C is connected to positive electrode line PL and negative electrode line NL, and is used to smooth the voltage between positive electrode line PL and negative electrode line NL.

  When connecting the assembled battery 10 to a load, the controller 40 switches the system main relays SMR-B and SMR-P from off to on. As a result, a current can flow through the current limiting resistor R, and an inrush current can be prevented from flowing through the capacitor C. Here, when the ignition switch of the vehicle is switched from OFF to ON, the assembled battery 10 is connected to the load. Information relating to turning on and off the ignition switch is input to the controller 40.

  Next, the controller 40 switches the system main relay SMR-G from off to on and switches the system main relay SMR-P from on to off. Thereby, connection of the assembled battery 10 and load is completed, and the battery system shown in FIG. 1 will be in a starting state (Ready-On). On the other hand, when cutting off the connection between the assembled battery 10 and the load, the controller 40 switches the system main relays SMR-B and SMR-G from on to off. Thereby, the battery system shown in FIG. 1 is in a stopped state (Ready-Off). Here, when the ignition switch is switched from on to off, the connection between the assembled battery 10 and the load is cut off.

  The booster circuit 31 boosts the output voltage of the assembled battery 10 and outputs the boosted power to the inverter 32. Further, the booster circuit 31 can step down the output voltage of the inverter 32 and output the lowered power to the assembled battery 10. The booster circuit 31 operates in response to a control signal from the controller 40. In the battery system of the present embodiment, the booster circuit 31 is used, but the booster circuit 31 may be omitted.

  The inverter 32 converts the DC power output from the booster circuit 31 into AC power, and outputs the AC power to the motor / generator 33. Further, the inverter 32 converts AC power generated by the motor / generator 33 into DC power and outputs the DC power to the booster circuit 31. As the motor generator 33, for example, a three-phase AC motor can be used.

  The motor / generator 33 receives the AC power from the inverter 32 and generates kinetic energy for running the vehicle. When the vehicle is driven using the output power of the battery pack 10, the kinetic energy generated by the motor / generator 33 is transmitted to the wheels.

  When the vehicle is decelerated or stopped, the motor / generator 33 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 32 converts the AC power generated by the motor / generator 33 into DC power and outputs the DC power to the booster circuit 31. The booster circuit 31 outputs the electric power from the inverter 32 to the assembled battery 10. Thereby, regenerative electric power can be stored in the assembled battery 10.

  FIG. 2 shows the configuration of the assembled battery 10. The assembled battery 10 has a plurality of battery blocks (corresponding to the storage block of the present invention) 11 connected in series. By connecting a plurality of battery blocks 11 in series, the output voltage of the assembled battery 10 can be secured. Here, the number of battery blocks 11 can be appropriately set in consideration of the voltage required for the assembled battery 10.

  Each battery block 11 has a plurality of single cells (corresponding to the storage element of the present invention) 12 connected in parallel. By connecting a plurality of single cells 12 in parallel, the full charge capacity of the battery block 11 (the assembled battery 10) can be increased, and the distance when the vehicle is driven using the output of the assembled battery 10 can be increased. it can. The number of single cells 12 constituting each battery block 11 can be appropriately set in consideration of the full charge capacity required for the assembled battery 10.

  Here, the total number of single cells 12 constituting the battery block 11 is N. The total number N of single cells 12 constituting each battery block 11 can be made equal in the plurality of battery blocks 11 constituting the assembled battery 10.

  Since the plurality of battery blocks 11 are connected in series, an equal current flows through each battery block 11. Further, in each battery block 11, a plurality of unit cells 12 are connected in parallel. Therefore, the current value flowing through each unit cell 12 is the same as the current value flowing through the battery block 11. The current value divided by the number (total number N) of.

  Specifically, when the total number of single cells 12 constituting the battery block 11 is N and the current value flowing through the battery block 11 is Ib, the current value flowing through each single cell 12 is Ib / N. . Here, it is assumed that variations in internal resistance do not occur in the plurality of single cells 12 constituting the battery block 11.

  As the unit cell 12, 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. For example, as the single battery 12, a 18650 type battery can be used. The 18650 type battery is a so-called cylindrical battery, which has a diameter of 18 [mm] and a length of 65.0 [mm]. In a cylindrical battery, a battery case is formed in a cylindrical shape, and a power generation element for charging and discharging is accommodated in the battery case.

  As shown in FIG. 3, the unit cell 12 includes a power generation element 12 a and a current breaker 12 b. The power generation element 12a and the current breaker 12b can be housed in a battery case that constitutes the exterior of the unit cell 12. The power generation element 12a is an element that performs charging and discharging, and includes a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a current collector plate and a positive electrode active material layer formed on the surface of the current collector plate. The negative electrode plate has a current collector plate and a negative electrode active material layer formed on the surface of the current collector plate. The positive electrode active material layer includes a positive electrode active material and a conductive agent, and the negative electrode active material layer includes a negative electrode active material and a conductive agent.

When a lithium ion secondary battery is used as the single battery 12, for example, the current collector plate of the positive electrode plate can be made of aluminum, and the current collector plate of the negative electrode plate can be made of copper. As the positive electrode active material, for example, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ can be used, and as the negative electrode active material, for example, carbon can be used. An electrolyte solution is infiltrated into the separator, the positive electrode active material layer, and the negative electrode active material layer. Instead of using the electrolytic solution, a solid electrolyte layer may be disposed between the positive electrode plate and the negative electrode plate. When using a solid electrolyte layer, the separator is omitted.

  The current breaker 12b is used to cut off the current path inside the unit cell 12. That is, when the current breaker 12b operates, the current path inside the unit cell 12 is cut off. For example, a fuse, a PTC (Positive Temperature Coefficient) element, or a current cutoff valve can be used as the current breaker 12b. These current breakers 12b can be used individually or in combination.

  The fuse as the current breaker 12b is blown according to the current flowing through the fuse. By blowing the fuse, the current path inside the unit cell 12 can be mechanically interrupted. Thereby, it can prevent that an excessive electric current flows into the electric power generation element 12a, and can protect the cell 12 (electric power generation element 12a). The fuse as the current breaker 12b can be accommodated in the battery case or can be provided outside the battery case. When a fuse is provided outside the battery case, a fuse is provided for each cell 12, and the fuse is connected in series with the cell 12.

  The PTC element as the current breaker 12b is arranged in the current path of the unit cell 12, and increases the resistance according to the temperature rise of the PTC element. When the current flowing through the PTC element increases, the temperature of the PTC element rises due to Joule heat. As the resistance of the PTC element increases as the temperature of the PTC element rises, current can be cut off in the PTC element. Thereby, it can prevent that an excessive electric current flows into the electric power generation element 12a, and can protect the cell 12 (electric power generation element 12a).

  The current cut-off valve as the current breaker 12b is deformed in accordance with the increase in the internal pressure of the unit cell 12, and can cut off the current path inside the unit cell 12 by breaking the mechanical connection with the power generation element 12a. it can. The inside of the unit cell 12 is in a sealed state, and when gas is generated from the power generation element 12a due to overcharging or the like, the internal pressure of the unit cell 12 increases. When gas is generated from the power generation element 12a, the unit cell 12 (power generation element 12a) is in an abnormal state. The mechanical connection with the power generation element 12a can be broken by deforming the current cutoff valve in response to the increase in the internal pressure of the unit cell 12. Thereby, it can block | prevent that charging / discharging electric current flows into the electric power generation element 12a in an abnormal state, and can protect the cell 12 (electric power generation element 12a).

  A monitoring unit (corresponding to a voltage sensor of the present invention) 20 shown in FIG. 1 detects the voltage of each battery block 11 and outputs the detection result to the controller 40. The current sensor 21 detects the value of the current flowing through the assembled battery 10 and outputs the detection result to the controller 40. In the present embodiment, when the battery pack 10 is being discharged, a positive value is used as the current value detected by the current sensor 21. Further, when the battery pack 10 is being charged, a negative value is used as the current value detected by the current sensor 21.

  The current sensor 21 only needs to be able to detect the value of the current flowing through the assembled battery 10 and can be provided not on the positive electrode line PL but on the negative electrode line NL. A plurality of current sensors 21 can also be used. In consideration of cost, physique, and the like, it is desirable to provide one current sensor 21 for one assembled battery 10 as in the present embodiment.

  The controller 40 has a built-in memory 41, and the memory 41 stores a program for operating the controller 40 and specific information. Note that the memory 41 can also be provided outside the controller 40.

  A charger 34 is connected to the positive electrode line PL and the negative electrode line NL via a charging relay CHR. The charger 34 is used to supply power from the external power source to the assembled battery 10. The external power source is a power source provided outside the vehicle, and an example of the external power source is a commercial power source. Here, charging the assembled battery 10 using an external power supply is called external charging. Charging relay CHR receives a control signal from controller 40 and switches between on and off. When performing external charging, the controller 40 switches the charging relay CHR from off to on.

  An inlet 35 is connected to the charger 34. By connecting a plug connected to an external power source via a cable to the inlet 35, the power of the external power source can be supplied to the charger 34. The charger 34 converts AC power from an external power source into DC power, and supplies the DC power to the assembled battery 10. Here, the charger 34 can also convert the voltage of the external power source into another voltage. The controller 40 can control the operation of the charger 34, and can adjust, for example, a current value (charging current) supplied from the charger 34 to the assembled battery 10.

  In the present embodiment, the charger 34 is mounted on the vehicle, but is not limited thereto. Specifically, a charger (referred to as an external charger) can be installed outside the vehicle. In this case, the controller 40 can control the operation of the external charger by communication (wireless or wired) between the controller 40 and the external charger.

  In the present embodiment, a wired (cable) is used as means for supplying power from the external power source to the assembled battery 10, but the present invention is not limited to this. Specifically, by using electromagnetic induction or a resonance phenomenon, power from an external power source can be supplied to the assembled battery 10 in a non-contact manner. In this case, a power feeding device that supplies power from the external power source to the vehicle and a power receiving device that receives power from the power feeding device may be used.

  In the present embodiment, as described with reference to FIG. 3, the current breaker 12b is provided for each single cell 12, and it is necessary to determine the operating state of the current breaker 12b. Here, as shown in FIG. 2, each battery block 11 includes a plurality of single cells 12 connected in parallel. For this reason, in some of the single cells 12 included in the battery block 11, even if the current breaker 12 b operates, current continues to flow through the battery block 11, and the voltage value of the battery block 11 does not change.

  If the current continues to flow through the battery block 11 even after the current breaker 12b has been activated, the unit cell 12 in which the current breaker 12b has not been activated will flow to the cell 12 in which the current breaker 12b has been activated. The current that is also flows. Thereby, the electric current value which flows into the cell 12 in which the current circuit breaker 12b is not operating will rise.

  Specifically, when the current value flowing through the battery block 11 is Ib, the current value flowing through the single battery 12 in which the current breaker 12b is not operating is Ib / (N−m). N is the total number of single cells 12 constituting the battery block 11, and m is the number of single cells 12 in which the current breaker 12b is operating. Since the value of “N−m” is smaller than the value of “N”, the value of the current flowing through the unit cell 12 in which the current breaker 12b is not operating increases.

  When the value of the current flowing through the unit cell 12 increases, in other words, when the current load on the unit cell 12 increases, high-rate deterioration may occur. Further, when a lithium ion secondary battery is used as the single battery 12, lithium may be deposited. Furthermore, when the value of the current flowing through the unit cell 12 increases, the current breaker 12b may be easily activated.

  Therefore, in each battery block 11, it is necessary to determine whether or not the current breaker 12b is operating. Specifically, it is possible to determine whether or not the current breaker 12b is operating in each battery block 11 by the method described below.

  The operation of the current breaker 12b does not normally occur frequently. Therefore, a plurality of battery blocks 11 constituting the assembled battery 10 include a battery block 11 including the current breaker 12b in the active state and a battery block 11 not including the current breaker 12b in the active state. There is. Here, the battery block 11 including the current breaker 12b in the operating state is referred to as an abnormal battery block 11, and the battery block 11 not including the current breaker 12b in the operating state is referred to as a normal battery block 11. .

  Considering the situation described above, the operating state of the current breaker 12b can be determined by comparing the SOC (State of Charge) in the two battery blocks 11. The SOC is the ratio of the current charge capacity to the full charge capacity. The SOC of each battery block 11 can be estimated from the OCV (Open Circuit Voltage) of each battery block 11. Since OCV and SOC are in a correspondence relationship, using this correspondence relationship, the SOC can be specified (estimated) from the OCV. The correspondence relationship between the OCV and the SOC can be obtained in advance by an experiment or the like, and can be stored in the memory 41.

  When the single battery 12 (battery block 11) is being charged / discharged, polarization occurs in the power generation element 12a. Here, when a lithium ion secondary battery is used as the unit cell 12, the polarization depends on the Li concentration distribution in the active material and the Li salt concentration distribution in the electrolytic solution. If the single cell 12 is left without charging / discharging the single cell 12 (battery block 11), the polarization of the power generation element 12a is alleviated. If the voltage of the unit cell 12 (battery block 11) is detected in a state where the polarization is relaxed, the OCV of the unit cell 12 (battery block 11) can be obtained. That is, the voltage value (CCV: Closed Circuit Voltage) of the battery block 11 detected by the monitoring unit 20 can be regarded as the OCV of the battery block 11.

  By using the following formula (1), it is possible to determine the operating state of the current breaker 12b. According to the following formula (1), in each battery block 11, the total number (referred to as the number of interruptions) of the current breakers 12b in the operating state can be specified.

  In the above equation (1), ΔSOC_b is the amount of change in SOC in the battery block 11 that is the target for determining the operating state of the current breaker 12b, and ΔSOC_r is the amount of change in SOC in the battery block 11 in the normal state. N is the total number of single cells 12 constituting the battery block 11, and m is the number of cut-offs. The value of “N−m” is the total number of current breakers 12b that are not in an operating state.

  Here, the above formula (1) will be described. When the full charge capacity of the battery block 11 is Cf, the SOC change amount ΔSOC of the battery block 11 is expressed by the following formula (2). ΣI shown in the following formula (2) is an integration (current integration value) of current values flowing through the battery block 11 while the change amount ΔSOC is generated. In the following formula (2), Cf_r represents the full charge capacity of the battery block 11 in the normal state, and Cf_b represents the full charge capacity of the battery block 11 in the abnormal state.

  When the current breaker 12b is operating, the full charge capacity Cf of the battery block 11 changes according to the number of breaks m. Since the battery block 11 is composed of a plurality of single cells 12 connected in parallel, the full charge capacity Cf of the battery block 11 is a value obtained by summing up the full charge capacities of the single cells 12 constituting the battery block 11. It becomes.

  Here, when the current breaker 12b is activated, the cell 12 corresponding to the activated current breaker 12b is disconnected from the parallel connection with the other cell 12. That is, the number of single cells 12 constituting the battery block 11 is reduced by the number of cut-offs m, and the full charge capacity Cf of the battery block 11 is also reduced by the amount of reduction of the number of single cells 12. Considering this point, the full charge capacities Cf_r and Cf_b have a relationship represented by the following formula (3).

  Based on the above formulas (2) and (3), the above formula (1) can be derived.

  When calculating ΔSOC_r and ΔSOC_b shown in the above formula (1), the OCV for specifying (estimating) the SOC of the battery block 11 includes a detection error by the monitoring unit 20. For this reason, there is a possibility that the calculation accuracy of ΔSOC_r and ΔSOC_b may be reduced due to the detection error of the monitoring unit 20. In particular, as ΔSOC_r and ΔSOC_b become smaller, the influence of the detection error of the monitoring unit 20 on ΔSOC_r and ΔSOC_b tends to increase, and the calculation accuracy of ΔSOC_r and ΔSOC_b tends to decrease.

  If the calculation accuracy of ΔSOC_r and ΔSOC_b is lowered, it is difficult to specify the number m of cut-offs based on the above equation (1). In particular, the smaller the actual number of interruptions, the more difficult it is to specify the number m of interruptions based on the ratio of ΔSOC_r and ΔSOC_b shown in the above equation (1).

  FIG. 4 shows a region where the blockage number m can be determined and a region where the blockage number m cannot be determined. In FIG. 4, a boundary line BL indicates a boundary between a region where the number of blocks m can be determined and a region where the number of blocks m cannot be determined. Here, in the area on the left side of the boundary line BL, the blockage number m cannot be determined, and in the area on the right side of the boundary line BL, the blockage number m can be determined.

  As shown in FIG. 4, the larger the ΔSOC (ΔSOC_r, ΔSOC_b), the smaller the influence of the detection error of the monitoring unit 20 that occupies ΔSOC. That is, since the detection error of the monitoring unit 20 is constant, the influence of the detection error on ΔSOC decreases as ΔSOC increases. In this case, it becomes easy to specify the number of cut-offs m based on the above formula (1).

  On the other hand, the smaller the ΔSOC, the greater the influence of the detection error of the monitoring unit 20 that occupies ΔSOC. Therefore, it becomes difficult to specify the number of cut-offs m based on the above equation (1). However, if the cutoff number m increases, the difference between ΔSOC_r and ΔSOC_b shown in the above equation (1) tends to increase, and the ratio between ΔSOC_r and ΔSOC_b shown in the above equation (1) easily changes.

  Thus, the influence of the detection error of the monitoring unit 20 on the ratio of ΔSOC_r and ΔSOC_b is reduced. Therefore, even if ΔSOC decreases, if the number m of interruptions increases, the number m of interruptions can be determined.

  Next, a process for externally charging the assembled battery 10 in the battery system of the present embodiment will be described. FIG. 5 is a flowchart showing processing when external charging is performed, and the processing shown in FIG. In this embodiment, when external charging is performed, the number m of cut-offs is determined.

  In step S101, the controller 40 measures the OCV (OCV_s) of each battery block 11 when starting external charging. Specifically, in a state where the assembled battery 10 is not connected to the booster circuit 31, each monitoring unit 20 causes each battery block to flow by passing a weak current that hardly generates a voltage change amount due to polarization to the assembled battery 10. Eleven OCV_s can be detected.

  The OCV_s detected by the monitoring unit 20 is output to the controller 40. The controller 40 can specify SOC_s corresponding to OCV_s by using the correspondence relationship between OCV and SOC. That is, the controller 40 can estimate the SOC_s of each battery block 11 before starting external charging.

  In step S <b> 102, the controller 40 starts external charging of the assembled battery 10. Specifically, the controller 40 operates the charger 34 in a state where the plug is connected to the inlet 35. Here, when performing external charging, the assembled battery 10 can be charged with a constant current. Further, the controller 40 sets an upper limit value (allowable upper limit rate) of the current rate that can be passed through the single cell 12 as a current rate (charging rate) when charging the assembled battery 10.

  The allowable upper limit rate can be set based on the maximum current value (allowable current value) I_max that can be passed through one single battery 12. If the charging rate is set in this way, the charging current at the allowable upper limit rate flows through each battery block 11. Here, since each battery block 11 is configured by a plurality of single cells 12 connected in parallel, each single cell 12 constituting each battery block 11 is smaller than the current value at the allowable upper limit rate. Value current flows.

  That is, when the battery block 11 does not include the activated current circuit breaker 12b, the current of the value obtained by dividing the current value at the allowable upper limit rate by the total number N flows to each single cell 12 constituting the battery block 11. It will be. Further, when the battery block 11 includes the activated current breaker 12b, each cell 12 constituting the battery block 11 has a value obtained by dividing the current value at the allowable upper limit rate by the number “N−m”. Current will flow.

  Thus, each unit cell 12 constituting the battery block 11 has a current value obtained by dividing the current value at the allowable upper limit rate by the total number N or the number “N−m”. The flowing current value is smaller than the current value at the allowable upper limit rate. If the interruption number m is “N−1”, the charging current flows only to one unit cell 12, but the current value at this time becomes the above-described allowable current value I_max. Therefore, it is possible to prevent an excessive current from flowing. Note that the charge rate set in the process of step S102 can also be set based on a current value lower than the allowable current value I_max.

  In step S <b> 103, the controller 40 determines whether or not the charge amount of the battery block 11 has reached a charge amount that allows determination of the cutoff number m. The amount of charge of the battery block 11 can be calculated by integrating the current value detected by the current sensor 21 during external charging. The amount of charge that can be determined for the number of interruptions m corresponds to ΔSOC shown in FIG. 4, and ΔSOC changes according to the number of interruptions m that can be determined, as indicated by the boundary line BL in FIG.

  The ΔSOC shown in FIG. 4 can be calculated from the full charge capacity of the battery block 11 in a normal state and the integrated current value associated with external charging. For this reason, if the current integrated value accompanying external charging is monitored, it is possible to determine whether or not a charge amount that can determine the number m of interruptions has been reached.

  As the external charging continues, ΔSOC increases. Here, as described with reference to FIG. 4, the smaller the ΔSOC, the more difficult it is to determine the number m of interruptions. However, if the actual number of interruptions is large, the number m of interruptions is specified even if ΔSOC is small. Can do. Immediately after the start of external charging, ΔSOC decreases, but even with such ΔSOC, if the number of interruptions m is large, determination of the number of interruptions m can be made. Therefore, after the external charging is started, it is possible to determine the cutoff number m from the side where the cutoff number m is large.

  In step S103, if the amount of charge of the battery block 11 has reached the amount of charge that can be determined for the cutoff number m, the controller 40 performs the process of step S104. On the other hand, if the amount of charge of the battery block 11 has not reached the amount of charge that can be determined for the cutoff number m, the controller 40 continues external charging.

  In step S <b> 104, the controller 40 controls the operation of the charger 34 to temporarily stop external charging of the assembled battery 10. If external charging of the assembled battery 10 is stopped, the polarization of the assembled battery 10 (battery block 11) can be relaxed, and the OCV (OCV_m) of the battery block 11 can be measured using the monitoring unit 20. . Here, it is preferable to measure the OCV_m of the battery block 11 after a predetermined time has elapsed since external charging was stopped.

  As the time for stopping energization (charging / discharging) of the assembled battery 10 (battery block 11) becomes longer, the polarization of the assembled battery 10 (battery block 11) is more easily eliminated. The time until the polarization is eliminated can be obtained in advance by an experiment or the like. Further, by measuring OCV_m of battery block 11, it is possible to specify (estimate) SOC_m corresponding to OCV_m using the correspondence relationship between OCV and SOC.

  In step S105, the controller 40 determines the number of cut-offs m. Specifically, the controller 40 calculates ΔSOC of each battery block 11 using SOC_s obtained by the process of step S101 and SOC_m obtained by the process of step S104. And the controller 40 determines the interruption | blocking number m using said Formula (1).

  If the ΔSOC of the battery block 11 is calculated, the number of interruptions m that can be determined in the current ΔSOC can be specified using the information shown in FIG. When the current ΔSOC (ΔSOC_r, ΔSOC_b) of the battery block 11 and the shut-off number m specified using FIG. 4 satisfy the relationship of the above formula (1), the controller 40 in the battery block 11 indicating ΔSOC_b, It can be determined that the current breaker 12b is operating by the specified number of breaks m. On the other hand, when the current ΔSOC and the specified number of interruptions m do not satisfy the relationship of the above formula (1), the controller 40 causes the battery block 11 indicating ΔSOC_b to cut off the current by the specified number of interruptions m. It can be determined that the device 12b is not operating.

  Note that in all the single cells 12 included in the battery block 11, when the current breaker 12 b is operating, no current flows through the battery block 11, and as a result, no current flows through the assembled battery 10. Therefore, all current breakers 12b included in the battery block 11 are in operation if the current sensor 21 detects that no current is flowing through the battery pack 10 despite external charging. Can be determined. Therefore, when the above equation (1) is used, the cutoff number m can be specified when the cutoff number m is not the number N.

  In step S106, the controller 40 determines whether or not the current breaker 12b is operating based on the determination result in the process of step S105. Here, if the interruption number m is 1 or more, the current breaker 12b is in operation. When it is determined that the current breaker 12b is activated, the controller 40 performs the process of step S107. When it is determined that the current breaker 12b is not activated, the controller 40 performs the process of step S108.

  In step S <b> 107, the controller 40 restarts external charging of the assembled battery 10. In the process of step S107, since the current breaker 12b is operating, the controller 40 restarts external charging of the assembled battery 10 without changing the charging rate. That is, the charge rate set in the process of step S107 is the same as the charge rate set immediately before the process of step S107 is performed.

  In the process of step S105, it is preferable not to change the charge rate when it is determined that the current breaker 12b is operating by the number of interruptions m. That is, if the charge rate is increased, an excessive current may flow to the unit cell 12 in which the current breaker 12 is not operating. Therefore, the charge rate is not changed in the process of step S107.

  For example, when the process of step S107 is performed immediately after the start of external charging, the charge rate set in the process of step S107 is the charge rate set in the process of step S102. On the other hand, as will be described later, when the process of step S107 is performed after increasing the charge rate, the charge rate set in the process of step S107 is the charge rate set immediately before.

  After resuming external charging in the process of step S107, in step S109, the controller 40 determines whether or not to complete external charging. When performing external charging, a voltage value (charging completion voltage value) for completing external charging can be set, and when the voltage value of the battery block 11 reaches the charging completion voltage value, external charging can be completed. . For this reason, in the process of step S109, the controller 40 determines whether or not the voltage value of the battery block 11 detected by the monitoring unit 20 has reached the charging completion voltage value.

  In addition, it can also be determined whether external charging is completed by determining whether the voltage value of the assembled battery 10 has reached the voltage value which completes external charging. In this case, the voltage value for completing external charging is set based on the voltage value of the assembled battery 10. Further, the voltage value of the assembled battery 10 can be detected by the monitoring unit 20.

  When it is determined that the external charging is completed, the controller 40 ends the process shown in FIG. On the other hand, when it is determined that the external charging is not completed, the controller 40 continues the external charging until the voltage value of the battery block 11 (or the assembled battery 10) reaches the charging completion voltage value. Here, the charge rate remains the charge rate set in step S107.

  In step S108, the controller 40 restarts external charging of the assembled battery 10. In the process of step S108, since the current breaker 12b is not operating, the controller 40 can increase the charging rate. When the process proceeds from the process of step S106 to the process of step S108, it is confirmed that the current breaker 12b is not operated by the number of breaks m corresponding to the current ΔSOC (the number of breaks m specified using FIG. 4). Can be confirmed.

  That is, in the process of step S108, the controller 40 can confirm that the current breaker 12b is not operating at least for the number m of breaks corresponding to the current ΔSOC. In other words, the controller 40 can confirm that the actual number of interruptions is smaller than the number of interruptions m corresponding to the current ΔSOC even if the current breaker 12b is operating.

  Therefore, even if the charging rate is increased, the current value flowing through each battery cell 12 included in the battery block 11 is less likely to exceed the allowable current value I_max that can be passed through the battery cell 12. When increasing the charging rate, the charging rate can be set in consideration of the number of single cells 12 in which the current breaker 12b is not operating.

  In the process of step S106, when it is determined that no interruption at the interruption number m has occurred, it can be confirmed that the current breaker 12b is not operating for at least “N−m” unit cells 12. . Specifically, when the process proceeds from the process of step S106 to the process of step S108, it can be confirmed that the current breaker 12b is not operating for at least two unit cells 12.

  Therefore, the battery block 11 (the assembled battery 10) can be supplied with a current that is at least twice the allowable current value I_max that can be supplied to the single battery 12. Specifically, when it is confirmed that the current breaker 12b is not operating for the “N−m” number of single cells 12, the battery is set to the current value obtained by multiplying the allowable current value I_max by “N−m”. A current can be passed through the block 11.

  Even if the current value “I_max × (N−m)” is set as the charging current value of the battery block 11, no current exceeding the allowable current value I_max flows through the single cells 12 included in the battery block 11. . If a charging current having a current value “I_max × (N−m)” is allowed to flow through the battery block 11, the charging current flows through at least “N−m” unit cells 12. Here, a current having a value obtained by dividing the current value “I_max × (N−m)” by at least “N−m” flows through each cell 12. Therefore, the current exceeding the allowable current value I_max does not flow through the single battery 12, and an excessive current can be prevented from flowing through the single battery 12.

  By increasing the charging rate by the process of step S108, the time for performing external charging can be shortened. Further, as described above, even if the charging rate is increased, it is possible to prevent an excessive current exceeding the allowable current value I_max from flowing into the single battery 12.

  After resuming external charging in the process of step S108, in step S110, the controller 40 determines whether or not to complete external charging. The process of step S110 is the same as the process of step S109. In step S110, when the external charging is not completed, the controller 40 performs the process of step S103 again. On the other hand, when completing the external charging, the controller 40 ends the process shown in FIG.

  When the process returns from the process of step S110 to the process of step S103, it is determined in the process of step S103 whether or not the charge amount of the battery block 11 has reached a charge amount at which the number of interruptions m can be determined. Here, the amount of charge of the battery block 11 is the amount of charge since the start of external charging. For this reason, the amount of charge of the battery block 11 used in the process of step S103 increases as external charging progresses.

  According to the processing shown in FIG. 5, the charging rate can be changed as shown in FIG. FIG. 6 shows the SOC behavior of the battery block 11 from the start to the completion of external charging. In FIG. 6, the horizontal axis indicates the charging time, and the vertical axis indicates the SOC of the battery block 11.

  In FIG. 6, at each of times t11, t12, and t13, the determination of the blocking number m described in the process of step S105 in FIG. 5 is performed. Here, as described with reference to FIG. 4, ΔSOC at time t11 is the smallest, and the number of cutoffs m determined at time t11 is the largest. Then, as the charging time elapses in the order of times t11, t12, and t13, ΔSOC increases, so the number of cut-off numbers m to be determined decreases.

  At time t0, external charging is started, and the charging rate is set to K1 [C] from time t0 to time t11. Here, the charging rate K1 corresponds to the allowable current value I_max of the unit cell 12, and the charging current of the charging rate K1 flows through each battery block 11. At time t11, when the number of interruptions m is determined and it can be confirmed that the current breaker 12b is not operating, the charging rate is changed from K1 [C] to K2 [C]. Here, the charging rate K2 is higher than the charging rate K1.

  After time t11, external charging is performed at the charging rate K2, and at time t12, the number of cut-offs m is determined. The blocking number m determined at time t12 is smaller than the blocking number m determined at time t11. In the determination at time t12, if it can be confirmed that the current breaker 12b is not operating, the charging rate is changed from K2 [C] to K3 [C]. Here, the charging rate K3 is higher than the charging rate K2.

  After time t12, external charging is performed at the charging rate K3, and at time t13, the number of cut-offs m is determined. The blocking number m determined at time t13 is smaller than the blocking number m determined at time t12. In the determination at time t13, if it can be confirmed that the current breaker 12b is not operating, the charging rate is changed from K3 [C] to K4 [C]. Here, the charging rate K4 is higher than the charging rate K3.

  At time t14, the voltage value of the battery block 11 (or the assembled battery 10) has reached the charging completion voltage value, and external charging is completed at time t14. According to the present embodiment, as ΔSOC increases due to external charging, the number of cut-offs m is determined from the larger side of the cut-off number m toward the smaller side. Each time it is confirmed that the current breaker 12b is not operating, the charging rate is increased.

  By increasing the charging rate, the time for external charging can be shortened. If external charging is continued while the charging rate remains K1 [C], external charging is completed at time t15 as shown in FIG. In this embodiment, since the charging rate is increased stepwise, the time for external charging can be shortened by the time between time t14 and time t15.

  If it is confirmed that the current breaker 12b is operating at any time from time t11 to time t13, the process for increasing the charge rate is not performed. That is, the charge rate is fixed to the charge rate set immediately before confirming that the current breaker 12b is operating. For example, if it is confirmed by the determination of the number of interruptions m at time t12 that the current breaker 12b is operating, the charging rate is fixed at K2 [C] from time t12 until external charging is completed.

  In the process shown in FIG. 5, external charging is temporarily stopped, and after determining the number of cut-offs, external charging is resumed. That is, external charging is temporarily stopped at times t11, t12, and t13. Here, the determination of the blocking number m is performed by the arithmetic processing using the above formula (1), so that the time required for determining the blocking number m is very short. Therefore, even if external charging is stopped and the number m of interruptions is determined, there is little influence on the time for performing external charging, and the time for performing external charging is difficult to extend.

  Further, in this embodiment, as shown in the above formula (1), the number of cut-offs m is determined based on ΔSOC. However, the present invention is not limited to this. As described above, since SOC and OCV are in a correspondence relationship, OCV can be used instead of SOC. That is, it is possible to determine the cutoff number m based on the OCV difference ΔOCV (corresponding to ΔSOC).

  In the battery system of the present embodiment, only the assembled battery 10 shown in FIG. 2 is used, but the present invention is not limited to this. Specifically, as shown in FIG. 7, two types of assembled batteries 10 and 50 can be used. FIG. 7 shows a configuration of a battery system which is a modification of the present embodiment, and corresponds to FIG. In FIG. 7, a system for charging the assembled batteries 10 and 50 with an external power source is omitted, but external charging can be performed on at least one of the assembled batteries 10 and 50 as in the present embodiment.

  The assembled battery 10 is connected to the inverter 32 via system main relays SMR-B1, SMR-G1, and SMR-P1. Here, the controller 40 switches each system main relay SMR-B1, SMR-G1, SMR-P1 between ON and OFF. The assembled battery 50 is connected to the inverter 32 via system main relays SMR-B2, SMR-G2, and SMR-P2. Here, the controller 40 switches each system main relay SMR-B2, SMR-G2, SMR-P2 between ON and OFF.

  The assembled batteries 10 and 50 are connected in parallel to the inverter 32. In the battery system shown in FIG. 7, the booster circuit 31 is omitted, but the booster circuit 31 may be provided. Specifically, the booster circuit 31 can be provided in a current path between at least one of the assembled batteries 10 and 50 and the inverter 32. According to the battery system shown in FIG. 7, by preparing the two types of assembled batteries 10 and 50, the two types of assembled batteries 10 and 50 can be used properly according to the traveling pattern of the vehicle.

  The assembled battery 10 shown in FIG. 7 is the assembled battery 10 described in the present embodiment. As shown in FIG. 8, the assembled battery 50 includes a plurality of single cells 51 connected in series. Here, a high-capacity battery can be used as the single battery 12 constituting the assembled battery 10, and a high-power battery can be used as the single battery 51 constituting the assembled battery 50. The high-power battery (unit cell 51) is a battery that can be charged and discharged with a larger current than the high-capacity battery. The high-capacity battery (single cell 12) is a battery having a larger storage capacity than the high-power battery.

  For example, when extending the travel distance of the vehicle, the assembled battery 10 composed of a high-capacity battery (unit cell 12) can be used. On the other hand, for example, when traveling according to the operation of the accelerator pedal, the assembled battery 50 composed of a high-power battery (unit cell 51) can be used.

  In the battery system shown in FIG. 7, the determination of the number of cut-offs m described in the present embodiment can be performed on the battery block 11 included in the assembled battery 10. Here, in the assembled battery 50, since the plurality of single cells 51 are connected in series, one current breaker may be provided in the current path of the assembled battery 50.

  Next, a second embodiment of the present invention will be described. In the present embodiment, the same members 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 mainly described.

  In Example 1, ΔSOC (ΔSOC_b, ΔSOC_r) in the two battery blocks 11 is compared as shown in the above formula (1). In the above formula (1), it is assumed that the full charge capacities of the two battery blocks 11 are equal to each other. However, the full charge capacity of the two battery blocks 11 may vary. In other words, variations in full charge capacity may occur due to variations in deterioration of the two battery blocks 11. The variation in deterioration occurs due to variations in the temperatures of the two battery blocks 11.

  If the full charge capacities of the two battery blocks 11 vary, it may not be possible to determine the number of cut-offs m using the above formula (1). If the full charge capacities of the two battery blocks 11 are different from each other, ΔSOC in the two battery blocks 11 is equal to each other even if the charge amount (ΣI shown in the above formula (2)) is the same for the two battery blocks 11. It will be different. In this case, even if the current breaker 12b is not activated, it may be determined that the current breaker 12b is activated due to variations in ΔSOC.

  Therefore, in this embodiment, the number of cut-offs m is determined based on the following formula (4).

  In the above equation (4), ΔSOC_b (n) is the SOC change amount when the nth external charge is performed in the battery block 11 that is the target of determination of the operating state of the current breaker 12b. ΔSOC_b (n−1) is the SOC change amount when the battery block 11 to be determined is subjected to the “n−1” th external charge. The n-th and "n-1" external chargings were performed for the n-th external charging and the "n-1" -th external charging when a plurality of external chargings were performed at different times. Indicates external charging.

  ΔSOC_r (n) is the SOC change amount when the battery block 11 in the normal state performs the nth external charge. ΔSOC_r (n−1) is the SOC change amount when the battery block 11 in the normal state performs the “n−1” external charging. In the above formula (4), the n-th and “n−1” times are compared, but the present invention is not limited to this, and the n-th and “n-k” times can also be compared. Here, k is an integer larger than 1 and smaller than n. That is, ΔSOC_b and ΔSOC_r when external charging is performed at different times may be compared.

  According to the above equation (4), since the ratio of ΔSOC_b (n) and ΔSOC_b (n−1) is calculated, the full charge capacity Cf_b (see the above equation (2)) of the battery block 11 to be determined is calculated. Can be canceled. Further, according to the above equation (4), since the ratio of ΔSOC_r (n) and ΔSOC_r (n−1) is calculated, the full charge capacity Cf_r in the battery block 11 in the normal state (see the above equation (2)) Can be canceled.

  Thus, even if the full charge capacities Cf_b and Cf_r shown in the above formula (2) are different from each other, the number of shut-offs can be obtained using the above formula (4) without considering the variation of the full charge capacities Cf_b and Cf_r. m can be calculated. According to the above equation (4), the value of the left side shown in the above equation (4) is 1 if the current breaker 12b is not operating at the n-th and “n−1” -th times. That is, the cutoff number m shown in the above equation (4) is zero.

  On the other hand, when the current breaker 12b is activated for the first time at the n-th time, the value of the left side shown in the above equation (4) becomes smaller than 1. That is, the cutoff number m shown in the above formula (4) is 1 or more. Along with this, the cutoff number m can be calculated from the above equation (4).

  In addition, in the n-th and “n−1” -th external charging, if the ΔSOC in one battery block 11 is compared, the cutoff number m can be calculated without considering the variation of the full charge capacity. Specifically, the number of cut-offs m can be calculated based on the following formula (5).

  According to the above formula (5), when the current breaker 12b is not activated in the “n−1” external charging and the current breaker 12b is activated in the nth external charging, m can be calculated. Here, when calculating the cutoff number m using the above equation (5), the charge amount (ΣI shown in the above equation (2)) when performing the “n−1” th external charge, and the nth time It is necessary to make the charge amount (ΣI shown in the above formula (2)) equal when performing external charging.

  That is, if the charge amounts at the n-th time and the “n−1” -th time are different from each other, it is difficult to specify the number of cut-offs m even when ΔSOC_b (n) and ΔSOC_b (n−1) are compared. When there is a difference in the charge amount between the nth time and the “n−1” th time, there is a possibility that the number of interruptions m corresponding to this difference may be calculated, and the current breaker 12b is actually operating. It becomes difficult to distinguish.

  Here, assuming that the external charging is actually performed, the SOC of the battery block 11 when the external charging is started changes depending on the use state (charge / discharge history) of the assembled battery 10. If the SOC at the start of external charging changes, the amount of charge until external charging is completed changes.

  As described in the first embodiment, external charging is performed until the voltage value of the battery block 11 or the assembled battery 10 reaches the charging completion voltage value. For this reason, if the SOC of the battery block 11 or the assembled battery 10 when starting external charging is different, the amount of charge until the external charging is completed will be different. Thus, if the amount of charge when external charging is performed differs between the n-th time and the “n−1” -th time, it becomes difficult to specify the number m of interruptions using the above formula (5).

  According to the above equation (4), since the ratio of ΔSOC_b (n) and ΔSOC_r (n) is calculated, it is possible to cancel the charge amount (ΣI shown in the above equation (2)) in the nth external charge. it can. Further, according to the above equation (4), since the ratio of ΔSOC_b (n−1) and ΔSOC_r (n−1) is calculated, the charge amount in the “n−1” th external charge (the above equation (2 ΣI) shown in FIG. For this reason, even when the charge amounts at the n-th time and the “n−1” -th time are different from each other, the variation in the charge amount can be ignored in calculating the cutoff number m.

  As described above, by using the above equation (4), it is possible not to consider the variation in the amount of charge when external charging is performed, and without considering the variation in the full charge capacity in the two battery blocks 11. The number m of interruptions can be calculated. The determination of the blocking number m using the above equation (4) can be performed by the process of step S105 shown in FIG.

  Next, Embodiment 3 of the present invention will be described. In the present embodiment, the same members 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 and second embodiments will be mainly described.

  In Example 1, the number m of interruptions is determined, and the charge rate is increased every time it is confirmed that the current breaker 12b is not operating. Here, in the actual use state of the assembled battery 10, the current breaker 12b rarely operates. Therefore, in each battery block 11, it is possible to perform external charging of the assembled battery 10 (battery block 11) on the assumption that the current breakers 12b for all the unit cells 12 are not activated.

  In this case, the battery block 11 can be charged such that a charging current having an allowable current value I_max flows through each single battery 12 included in the battery block 11. Here, since the battery block 11 includes a plurality of single cells 12 connected in parallel, the total number of the single cells 12 constituting the battery block 11 with respect to the allowable current value I_max is included in the battery block 11. A current value multiplied by N can be passed.

  Thus, the charging time of the battery block 11 (single battery 12) can be shortened by supplying a charging current having an allowable current value I_max to each single battery 12 constituting the battery block 11.

  When external charging is started at the above-described charging rate, if there is a unit cell 12 in which the current breaker 12b is operating, it is connected in parallel with the unit cell 12 as described in the first embodiment. More current flows through the other unit cells 12. As described above, when the current load on the other unit cell 12 increases, an irreversible reaction such as formation of a film on the negative electrode occurs, and the full charge capacity of the unit cell 12 decreases.

  Here, when the unit cell 12 is used, the unit cell 12 can continue to be used until the amount of decrease in the full charge capacity of the unit cell 12 (referred to as capacity decrease amount) reaches a threshold value. If external charging is continued at the above-described charging rate in the state where the current breaker 12b is operating, the capacity reduction amount increases and the threshold value is easily reached.

  Therefore, in the present embodiment, while the external charging of the assembled battery 10 (battery block 11) is performed at the above-described charging rate, the interruption number m is determined while confirming that the capacity reduction amount does not reach the allowable amount. I have to. Here, the allowable amount can be set to a value smaller than the threshold value of the capacity reduction amount described above. Further, when determining the number of interruptions m, as in the first embodiment, the number of interruptions m is determined from the larger number of interruptions m toward the smaller side in accordance with the increase in the amount of charge accompanying external charging. be able to.

  In the present embodiment, as described above, external charging is started so that the charging current at the allowable current value I_max flows to each single cell 12 included in the battery block 11. Here, when external charging is started, if the interruption number m is already “N−1”, a charging current flows through one unit cell 12 included in the battery block 11. That is, a current exceeding the allowable current value I_max flows through one unit cell 12, and the capacity reduction amount increases.

  Therefore, in this embodiment, when external charging is started, it is assumed that a capacity reduction amount occurs when the cutoff number m is “N−1”. That is, when external charging is started, it is assumed that the capacity decrease amount is most likely to increase. Here, the capacity reduction amount increases as the charging time becomes longer. Therefore, if the relationship between the charging time and the capacity reduction amount is obtained in advance, the capacity reduction amount corresponding to the charging time can be estimated.

  As described in the first embodiment, if ΔSOC increases with the progress of external charging, it can be determined whether or not the cutoff number m is “N−1”. Here, if it can be determined that the interruption number m is not “N−1”, the actual capacity reduction amount changes along with the capacity reduction amount (assumed value) when the interruption number m is “N−1”. I can confirm that I have not done it. That is, it can be confirmed that the actual capacity reduction amount is smaller than the capacity reduction amount (assumed value).

  If it can be determined that the block number m is not “N−1”, the actual block number may be “N−2” or less. Therefore, it can be assumed that a capacity reduction amount occurs when the cutoff number m is “N−2”. And based on this assumption, the amount of capacity reduction (assumed value) corresponding to the charging time can be calculated.

  If ΔSOC further increases with the progress of external charging, it can be determined whether or not the cutoff number m is “N−2”. Here, if it can be determined that the interruption number m is not “N−2”, the actual capacity decrease amount changes along with the capacity decrease amount (assumed value) when the interruption number m is “N−2”. I can confirm that I have not done it. That is, it can be confirmed that the actual capacity reduction amount is smaller than the capacity reduction amount (assumed value).

  Thus, every time it is confirmed that the current breaker 12b is not operating, the capacity decrease amount (assumed value) is less likely to reach the allowable amount by decreasing the capacity decrease amount (assumed value). That is, external charging can be continued at the maximum charging rate until the capacity reduction amount (assumed value) reaches the allowable amount. In this way, the external charging time can be shortened by continuing the external charging at the maximum charging rate while confirming that the capacity decrease amount (assumed value) does not reach the allowable amount.

  Processing when external charging is performed in this embodiment will be described with reference to the flowchart shown in FIG. The process shown in FIG. 9 is executed by the controller 40. In the process shown in FIG. 9, the number m of interruptions is determined while performing external charging.

  In step S201, the controller 40 measures the OCV (OCV_s) of each battery block 11 when starting external charging. Further, by measuring OCV_s, it is possible to identify SOC_s corresponding to OCV_s. The process of step S201 is the same as the process of step S101 shown in FIG.

  In step S <b> 202, the controller 40 starts external charging of the assembled battery 10. Specifically, the controller 40 operates the charger 34 in a state where the plug is connected to the inlet 35. Here, when external charging is performed, charging can be performed with a constant current. Further, the controller 40 sets an upper limit value (allowable upper limit rate) of the current rate that can be passed through the battery block 11 as a current rate (charging rate) when charging the assembled battery 10.

  As described above, the allowable upper limit rate is set so that the allowable current value I_max flows in all the unit cells 12 included in each battery block 11 on the assumption that the cutoff number m is zero. That is, the current value at the allowable upper limit rate is a value obtained by multiplying the allowable current value I_max by the total number N of the single cells 12 constituting the battery block 11. In the process of step S202, the charge rate can also be set so that a current value lower than the allowable current value I_max flows for all the cells 12 constituting the battery block 11.

  In step S202, the controller 40 starts calculating the amount of capacity reduction (assumed value). Specifically, a map (an example) shown in FIG. 10 is prepared in advance, and the controller 40 calculates a capacity reduction amount (assumed value) using the map shown in FIG. As shown in FIG. 10, the capacity reduction amount increases as the charging time elapses. Therefore, the controller 40 can specify the amount of capacity reduction corresponding to the measurement time (charging time) by measuring the charging time.

  In FIG. 10, the relationship between the capacity reduction amount and the charging time is a linear function, but is not limited thereto. That is, the relationship between the capacity reduction amount and the charging time is a relationship obtained in advance by experiments or the like.

  The change rate of the capacity reduction amount shown in FIG. 10 changes according to the change in the number of interruptions m. The change rate of the capacity decrease amount indicates the change amount of the capacity decrease amount with respect to a predetermined charging time. Here, the rate of change in the amount of decrease in capacity increases as the number of interruptions m increases. In other words, the rate of change in the amount of decrease in capacity decreases as the number of interruptions m decreases. The larger the interruption number m, the greater the current load on the unit cell 12 in which the current breaker 12b is not operating.

  Here, as shown in FIG. 11, the rate of decrease in capacity increases as the charging rate increases. For this reason, in the single battery 12 in which the current breaker 12b is not operated, the charging rate increases and the capacity reduction amount tends to increase as the number of interruptions m increases. The map shown in FIG. 10 can be prepared for each blockage number m. Then, as will be described later, the map used for calculating the capacity decrease amount (assumed value) is changed according to the determination of the number of interruptions m.

  For example, immediately after the start of external charging, the determination of the number of interruptions m is not performed, and the charging rate is set so that the allowable current value I_max flows for all the unit cells 12 constituting the battery block 11. ing. In this case, the capacity decrease amount (assumed value) is calculated using a map showing the behavior of the capacity decrease amount when the number of interruptions m is “N−1”.

  On the other hand, when the determination of the shut-off number m is made, the capacity decrease amount (assumed value) is calculated based on a number that is one less than the judged shut-off number m. For example, when it is determined that the interruption number m is not “N−1”, the capacity reduction amount (assumed value) is used using a map indicating the behavior of the capacity reduction amount when the interruption number m is “N-2”. ) Is calculated.

  In step S203, the controller 40 determines whether or not to complete external charging. Specifically, the controller 40 determines whether or not the voltage value of the battery block 11 (or the assembled battery 10) has reached the charging completion voltage value. Here, when the external charging is completed, the controller 40 ends the processing shown in FIG. On the other hand, when the external charging is not completed, the controller 40 performs the process of step S204.

  In step S <b> 204, the controller 40 determines whether or not the charge amount of the battery block 11 has reached a charge amount that allows determination of the cutoff number m. The amount of charge of the battery block 11 can be calculated by integrating the current value detected by the current sensor 21 during external charging. The amount of charge that can be determined for the number of interruptions m corresponds to ΔSOC shown in FIG. 4, and ΔSOC changes according to the number of interruptions m that can be determined, as indicated by the boundary line BL in FIG.

  Similar to the first embodiment, if the current integrated value associated with external charging is monitored, it is possible to determine whether or not the charging amount at which the number of interruptions m can be determined has been reached. If the amount of charge of the battery block 11 has reached the amount of charge that can be determined as the number of interruptions m, the controller 40 performs the process of step S205. On the other hand, if the amount of charge of the battery block 11 has not reached the amount of charge that can be determined for the cutoff number m, the controller 40 performs the process of step S203.

  In Step S <b> 205, the controller 40 temporarily stops the external charging of the assembled battery 10 by controlling the operation of the charger 34. If external charging of the assembled battery 10 is stopped, the polarization of the assembled battery 10 (battery block 11) can be relaxed, and the OCV (OCV_m) of the battery block 11 can be measured using the monitoring unit 20. .

  By measuring OCV_m of battery block 11, it is possible to specify (estimate) SOC_m corresponding to OCV_m using the correspondence relationship between OCV and SOC. Here, as in the process of step S104 shown in FIG. 5, it is preferable to measure the OCV_m of the battery block 11 after a predetermined time has elapsed since the external charging was stopped.

  In step S206, the controller 40 determines the cutoff number m. Specifically, the controller 40 calculates ΔSOC of each battery block 11 using the SOC_s obtained by the process of step S201 and the SOC_m obtained by the process of step S205. And the controller 40 determines the interruption | blocking number m using said Formula (1). Note that the number m of interruptions can be determined by the method described in the second embodiment.

  If the ΔSOC of the battery block 11 is calculated, the number of interruptions m that can be determined in the current ΔSOC can be specified using the information shown in FIG. When the current ΔSOC (ΔSOC_r, ΔSOC_b) of the battery block 11 and the shut-off number m specified using FIG. 4 satisfy the relationship of the above formula (1), the controller 40 in the battery block 11 indicating ΔSOC_b, It can be determined that the current breaker 12b is operating by the specified number of breaks m.

  On the other hand, when the current ΔSOC (ΔSOC_r, ΔSOC_b) and the specified cutoff number m do not satisfy the relationship of the above formula (1), the controller 40 determines the specified cutoff number m in the battery block 11 indicating ΔSOC_b. It can be determined that the current breaker 12b is not activated by the amount.

  In step S207, the controller 40 determines whether or not the current breaker 12b is operating based on the determination result in the process of step S206. Here, if the interruption number m is 1 or more, the current breaker 12b is in operation. When it is determined that the current breaker 12b is activated, the controller 40 performs the process of step S208. When it is determined that the current breaker 12b is not activated, the controller 40 performs the process of step S211.

  In step S208, the controller 40 determines whether or not the capacity decrease amount (assumed value) has reached an allowable amount. The controller 40 uses the map shown in FIG. 10 to measure the amount of decrease in capacity (assumed that the external charging is started by the process of step S202 until the external charging is stopped by the process of step S205. Value) can be calculated. Here, the time during which external charging is performed can be measured using a timer.

  Then, the controller 40 determines whether or not the calculated capacity reduction amount (assumed value) has reached an allowable amount. When the capacity reduction amount (assumed value) reaches the allowable amount, the controller 40 performs the process of step S209. On the other hand, when the capacity reduction amount (assumed value) does not reach the allowable amount, the controller 40 performs the process of step S210.

  In step S209, the controller 40 restarts external charging of the assembled battery 10 in a state where the charging rate is lowered. In the process of step S209, the charge rate is set to a value lower than the charge rate set before performing the process of step S209. For example, when the charge rate is set by the process of step S202, the charge rate is set to a value lower than the charge rate. Further, when the charge rate is already lowered, the charge rate is set to a value lower than this charge rate.

  By reducing the charging rate, the current load on the single battery 12 can be reduced, and the increase in the capacity reduction amount can be suppressed. That is, after the capacity reduction amount (assumed value) reaches the allowable amount, the capacity reduction amount can hardly reach the threshold value (capacity reduction amount) described above.

  After resuming external charging by the process of step S209, the controller 40 performs the process of step S203. On the other hand, in step S210, the controller 40 restarts external charging of the assembled battery 10 without changing the charging rate. When the process proceeds to step S210, the current breaker 12b is in operation for the determined number of breaks m.

  For this reason, if the charge rate is increased, the capacity reduction amount is increased. Therefore, in the process of step S210, the charge rate is not changed. In the process of step S210, the charge rate can be reduced. After resuming external charging by the process of step S210, the controller 40 performs the process of step S203.

  In step S211, the controller 40 restarts external charging of the assembled battery 10. Here, when the process proceeds from the process of step S207 to the process of step S211, the current breaker 12b is activated by the number of interruptions m (the interruption number m specified using FIG. 4) corresponding to the current ΔSOC. You can be sure that it is not.

  In other words, even if the current breaker 12b is operating, it can be confirmed that the actual number of breaks is smaller than the number m of breaks corresponding to the current ΔSOC. If the actual number of interruptions is smaller than the number of interruptions used to calculate the capacity reduction amount (assumed value), the actual capacity reduction amount is smaller than the currently calculated capacity reduction amount (assumed value). . Therefore, the controller 40 reduces the capacity decrease amount (assumed value) by the amount (excess amount) of the capacity decrease amount (assumed value) that is excessively estimated from the current capacity decrease amount (assumed value).

  In the process of step S207, when the interruption at the interruption number m does not occur, it can be confirmed that the current breaker 12b is not operating for at least “N−m” unit cells 12. Specifically, when the process proceeds from the process of step S207 to the process of step S211, it can be confirmed that the current breaker 12b has not been operated by at least the number of interruptions m.

  Therefore, the controller 40 changes a map (map shown in FIG. 10) for specifying the capacity decrease amount (assumed value). Specifically, the controller 40 assumes that the current circuit breaker 12b may be operated by the number of interruptions m that is one smaller than the current interruption number m, and displays a map corresponding to the interruption number. Use it to recalculate the capacity drop (assumed value). After performing the process of step S211, the controller 40 performs the process of step S203.

  According to the process shown in FIG. 9, the capacity reduction amount (assumed value) can be changed as shown in FIG. FIG. 12 shows the behavior of the capacity decrease amount (assumed value) after starting external charging. In FIG. 12, the horizontal axis indicates the charging time, and the vertical axis indicates the capacity decrease amount (assumed value). FIG. 12 shows the behavior of the capacity decrease when the number of interruptions m is “N−1”, “N-2”, “N-3”, “N-4”, “N-5”. Yes. The behavior of the capacity reduction amount is specified by the map shown in FIG.

  After external charging is started at time t0, the capacity reduction amount (corresponding to the map shown in FIG. 10) based on the behavior of the capacity reduction amount when it is assumed that the cutoff number m is “N−1” ( (Assumed value) is calculated. Here, the capacity reduction amount (assumed value) increases as the charging time increases.

  At time t21, the number of interruptions m is determined, and if it is confirmed that the current breaker 12b is not operated by the number of interruptions m, a map used for calculating the capacity reduction amount (assumed value) (FIG. 10) is changed. Specifically, the capacity decrease amount (assumed value) is calculated based on the behavior of the capacity decrease amount (corresponding to the map shown in FIG. 10) when it is assumed that the shut-off number m is “N-2”. Try again. Here, the change rate of the capacity decrease amount when the interruption number m is “N−2” is lower than the change rate of the capacity decrease amount when the interruption number m is “N−1”.

  For this reason, the surplus part is reset among the capacity | capacitance fall amount (assumed value) calculated by time t21 at the time t21. Specifically, at time t21, the capacity reduction amount (assumed value) when the interruption number m is “N−2” from the capacity reduction amount (assumed value) when the interruption number m is “N−1”. ). Then, after time t21, the capacity reduction amount (assumed value) corresponding to the charging time is calculated based on the behavior of the capacity reduction amount when it is assumed that the interruption number m is “N-2”.

  At time t22, the determination of the number of interruptions m is made, and if it is confirmed that the current breaker 12b is not operated by the number of interruptions m, a map used for calculating the capacity reduction amount (assumed value) (see FIG. 10) is changed. Specifically, the capacity decrease amount (assumed value) is calculated based on the behavior of the capacity decrease amount (corresponding to the map shown in FIG. 10) when it is assumed that the shut-off number m is “N-3”. Try again. Here, the rate of change of the capacity decrease when it is assumed that the interruption number m is “N-3” is the rate of change of the capacity reduction amount when the interruption number m is assumed to be “N-2”. Also lower.

  For this reason, at time t22, the surplus is reset among the amount of capacity decrease (assumed value) calculated up to time t22. Specifically, at time t22, the capacity reduction amount (assumed value) when the interruption number m is "N-3" from the capacity reduction amount (assumed value) when the interruption number m is "N-2". ). Then, after time t22, the capacity decrease amount (assumed value) corresponding to the charging time is calculated based on the behavior of the capacity decrease amount when it is assumed that the interruption number m is “N-3”.

  At times t23 and t24, processing similar to that at times t21 and t22 is performed. And if it is confirmed by the determination of the number of interruptions m that the current breaker 12b is not operating, the map (map shown in FIG. 10) used for calculating the capacity reduction amount (assumed value) is changed. Here, every time it is confirmed that the current breaker 12b is not operating, the map shown in FIG. 10 is a map in which the rate of change of the capacity reduction amount (assumed value) is low.

  According to the present embodiment, as shown in FIG. 12, it is possible to perform external charging while assuming that the capacity reduction amount is assumed and the capacity reduction amount (assumed value) has not reached the allowable amount. . As described with reference to FIG. 4, as the external charging progresses, ΔSOC can be increased, and the determination of the smaller cutoff number m can be performed. Each time it is confirmed that the shut-off number m is small, the capacity decrease amount (assumed value) can be reset by the surplus amount, so it is confirmed that the capacity decrease amount (assumed value) does not reach the allowable amount. However, external charging can be continued at a preset charging rate.

10: assembled battery (power storage device), 11: battery block (power storage block),
12: single cell (storage element), 12a: power generation element, 12b: current breaker,
20: monitoring unit (voltage sensor), 21: current sensor, 31: booster circuit,
32: Inverter, 33: Motor generator, 34: Charger, 35: Inlet,
40: Controller, 41: Memory, PL: Positive line, NL: Negative line,
R: current limiting resistor, SMR-B, SMR-G, SMR-P: system main relay

Claims (11)

A power storage device in which a plurality of power storage blocks each having a plurality of power storage elements connected in parallel are connected in series ;
A current breaker that cuts off a current path inside each of the storage elements ;
A voltage sensor for detecting a voltage value before Symbol respective storage block,
A controller that estimates the SOC of each power storage block based on the detection result of the voltage sensor;
The controller is
Wherein a first ratio is the ratio of the SOC variation amount in the power storage block not including the current breaker in the amount of change and shielding disconnection state of SOC of each power storage block, the storage element constituting the power storage block Using the correspondence relationship with the second ratio , which is the ratio of the total number of current breakers and the total number of current breakers that are not in a break state,
After starting the charging of the power storage device, the total number of the current breakers in the cut-off state when calculating the second ratio is changed from the larger side to the smaller side in accordance with the increase in the SOC of the power storage block While determining the blocking state using the correspondence,
A power storage system characterized by increasing a current value when charging the power storage device each time it is determined that the current breaker is not in a cut-off state.
  The power storage system according to claim 1, wherein the controller sets an allowable current value of the power storage element as a charging current value of the power storage device when charging of the power storage device is started.   Each time the controller determines that the current breaker is not in a breaker state, the storage element corresponding to the current breaker that is not in a breaker state allows a charging current of an allowable current value to flow. The power storage system according to claim 2, wherein a charging current value of the power storage device is set.   The power storage system according to claim 1 or 2, wherein the controller fixes a charging current value of the power storage device when it is determined that the current breaker is in a cut-off state. A power storage device in which a plurality of power storage blocks each having a plurality of power storage elements connected in parallel are connected in series ;
A current breaker that cuts off a current path inside each of the storage elements ;
A voltage sensor for detecting a voltage value before Symbol respective storage block,
A controller that estimates the SOC of each power storage block based on the detection result of the voltage sensor;
The controller is
Wherein a first ratio is the ratio of the SOC variation amount in the power storage block not including the current breaker in the amount of change and shielding disconnection state of SOC of each power storage block, the storage element constituting the power storage block Using the correspondence relationship with the second ratio , which is the ratio of the total number of current breakers and the total number of current breakers that are not in a break state,
After starting the charging of the power storage device, the total number of the current breakers in the cut-off state when calculating the second ratio is changed from the larger side to the smaller side in accordance with the increase in the SOC of the power storage block While determining the blocking state using the correspondence,
Each time it is determined that the current breaker is not in a cut-off state, the amount of decrease in the full charge capacity in the power storage block is changed.   6. The power storage system according to claim 5, wherein the controller reduces the amount of decrease in the full charge capacity as the total number of the current breakers in the cut-off state becomes smaller by determining the cut-off state.   When the controller starts charging the power storage device, the controller sets a charging current value of the power storage device so that an allowable current value flows through all of the power storage elements constituting the power storage block. The power storage system according to claim 5 or 6. The controller is
Measure the charging time of the power storage device,
The amount of decrease in the full charge capacity corresponding to the measured charge time is calculated using the correspondence relationship between the charge time and the amount of decrease in the full charge capacity, according to any one of claims 5 to 7, Power storage system. The controller determines the breaking state of the current breaker based on the following formula (I):
In the above formula (I), ΔSOC_b is the amount of change in SOC in each power storage block, ΔSOC_r is the amount of change in SOC in the power storage block that does not include the current breaker in a cut-off state, and N is The total number of power storage elements constituting the power storage block, and m is the total number of the current breakers in a cut-off state.
The power storage system according to any one of claims 1 to 8, wherein The controller determines the breaking state of the current breaker based on the following formula (II):
In the above formula (II), ΔSOC_b is the amount of change in SOC in each power storage block, ΔSOC_r is the amount of change in SOC in the power storage block that does not include the current breaker in the cut-off state, and n, n -K (1 <k <n) is the number of times the power storage device has been charged, N is the total number of the power storage elements constituting the power storage block, and m is the current cutoff in the cutoff state The total number of vessels,
The power storage system according to any one of claims 1 to 8, wherein   The current breaker is a fuse that cuts off the current path by fusing, a PTC element that cuts off the current path due to an increase in resistance due to a temperature rise, or a deformation in response to an increase in internal pressure of the power storage element, The power storage system according to any one of claims 1 to 10, wherein the power storage system is a current cutoff valve that blocks a current path.