Battery System

Abstract

To provide a battery system with which it is possible to increase charge / discharge efficiency and extend the life of a secondary battery.SOLUTION: A battery system 1 is constituted so as to charge and discharge in response to a charge / discharge request from a host system 100, and includes a plurality of secondary batteries 10, a battery state acquisition unit 20, a charge / discharge request acquisition unit 30, a group classification unit 40, a command value derivation unit 50, and a charge / discharge control unit 60. The battery state acquisition unit 20 acquires the battery state of the plurality of secondary batteries 10. The charge / discharge request acquisition unit 30 acquires a charge / discharge request from the host system 100. The group classification unit 40 dynamically classifies the plurality of secondary batteries 10 into a plurality of groups in accordance with the battery state of the plurality of secondary batteries 10 and the charge / discharge request. The command value derivation unit 50 derives a charge / discharge command value that defines distributed electric power for distributing electric power that conforms to the charge / discharge request to each of the groups. Then, the charge / discharge control unit 60 performs charging / discharging of the plurality of secondary batteries 10 on the basis of the charge / discharge command value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery system. [Background technology]

[0002] Battery systems equipped with multiple secondary battery units are widely used as power sources for various devices and vehicles. Because the lifespan of a secondary battery varies depending on how it is used, these battery systems control how the secondary batteries are used to extend their lifespan. Meanwhile, charging and discharging in these battery systems are also controlled to ensure efficient charging and discharging. For example, Patent Document 1 discloses a power supply system capable of controlling the voltage and charge / discharge amount for each secondary battery unit. The system performs charging and discharging for each secondary battery unit while prioritizing the lifespan of the secondary batteries installed in the power supply system, and sets a charging / discharging schedule for each secondary battery unit so as to follow charging / discharging requests from a higher-level system to which the power supply system is connected. This configuration allows charging and discharging to be performed while taking into account both charging / discharging efficiency and the lifespan of the secondary batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-205490 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration disclosed in Patent Document 1, when natural energy such as sunlight is used as the power source, it is difficult to predict the power supply, so the charge / discharge schedule for each secondary battery unit must be updated successively in accordance with changes in the power supply, which makes charge / discharge control complicated and unrealistic. Therefore, there is room for improvement in terms of improving the efficiency of charge / discharge and extending the life of secondary batteries.

[0005] The present invention has been made in view of the above problems, and aims to provide a battery system that can improve the efficiency of charging and discharging and extend the life of secondary batteries. [Means for solving the problem]

[0006] One aspect of the present invention is a battery system (1) configured to perform charging and discharging in response to a charging and discharging request from a host system (100), A plurality of secondary batteries (10); a battery status acquisition unit (20) that acquires the battery status of the secondary battery; a charge / discharge request acquisition unit (30) that acquires the charge / discharge request; a grouping unit (40) that dynamically divides the secondary batteries into a plurality of groups in accordance with the battery states of the secondary batteries acquired by the battery state acquisition unit and the charge / discharge request acquired by the charge / discharge request acquisition unit; a command value derivation unit (50) that derives a charge / discharge command value that defines a distribution power for distributing power according to the charge / discharge request to each of the groups; a charge / discharge control unit (60) that charges and discharges the plurality of secondary batteries based on the charge / discharge command value. 、 the battery state of the secondary battery includes an internal resistance of the secondary battery; the grouping unit divides the secondary batteries into the groups according to the magnitude of the internal resistance of the secondary batteries and the charge / discharge request; the plurality of groups include a first group consisting of the secondary batteries having a predetermined internal resistance, and a second group consisting of the secondary batteries having an internal resistance smaller than the internal resistance of the secondary batteries included in the first group; the command value derivation unit derives the charge / discharge command value so that distributed power distributed to the first group is smaller than distributed power distributed to the second group. in the battery system. Yet another aspect is A battery system (1) configured to perform charging and discharging in response to a charging and discharging request from a host system (100), A plurality of secondary batteries (10); a battery status acquisition unit (20) that acquires the battery status of the secondary battery; a charge / discharge request acquisition unit (30) that acquires the charge / discharge request; a grouping unit (40) that dynamically divides the secondary batteries into a plurality of groups in accordance with the battery states of the secondary batteries acquired by the battery state acquisition unit and the charge / discharge request acquired by the charge / discharge request acquisition unit; a command value derivation unit (60) that derives a charge / discharge command value that defines a distribution power for distributing power according to the charge / discharge request to each of the groups; a charge / discharge control unit (60) that charges / discharges the plurality of secondary batteries based on the charge / discharge command value; the battery state of the secondary battery includes a capacity maintenance rate of the secondary battery; the grouping unit divides the secondary batteries into the groups according to the capacity maintenance rates of the secondary batteries and the charge / discharge request; the plurality of groups include a discharging group group, which is the plurality of groups divided by the group dividing unit when discharging is requested as the charge / discharge request, and a charging group group, which is the plurality of groups divided by the group dividing unit when charging is requested as the charge / discharge request, the discharging group group includes a low capacity retention rate group of the discharging group group consisting of the secondary batteries having a low capacity retention rate, and a high capacity retention rate group of the discharging group group consisting of the secondary batteries having a higher capacity retention rate than the low capacity retention rate group of the discharging group group, and the number of the secondary batteries included in the low capacity retention rate group of the discharging group group is smaller than the number of secondary batteries included in the high capacity retention rate group of the discharging group group, the charging group group includes a low capacity retention rate group of the charging group group consisting of the secondary batteries having a low capacity retention rate, and a high capacity retention rate group of the charging group group consisting of the secondary batteries having a higher capacity retention rate than the low capacity retention rate group of the charging group group, and the number of secondary batteries included in the low capacity retention rate group of the charging group group is greater than the number of secondary batteries included in the high capacity retention rate group of the charging group group, The command value derivation unit is in a battery system that derives the charge / discharge command value so that the distributed power distributed to the low capacity maintenance ratio group of the discharging group group is greater than the distributed power distributed to the high capacity maintenance ratio group of the discharging group group, and derives the charge / discharge command value so that the distributed power distributed to the low capacity maintenance ratio group of the charging group group is less than the distributed power distributed to the high capacity maintenance ratio group of the charging group group. [Effects of the Invention]

[0007] In the battery system, multiple secondary batteries are dynamically grouped according to their battery states and charging / discharging requirements. Each group is charged / discharged using distributed power, which is distributed to each group according to the charging / discharging requirements, and charging / discharging is controlled for each group. This simplifies the charging / discharging control compared to individually controlling the charging / discharging of multiple secondary batteries, and the control is not complicated even when the grouping is performed dynamically as described above. As a result, it is easy to control charging / discharging in real time according to the charging / discharging requirements, and charging / discharging can be made more efficient. Furthermore, because the grouping is performed based on the battery states of the secondary batteries, charging / discharging can be performed taking into account the degree of deterioration of the secondary batteries, thereby extending the life of the secondary batteries.

[0008] As described above, according to the above aspect, it is possible to provide a battery system that can improve the efficiency of charging and discharging and extend the life of the secondary battery.

[0009] In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of a battery system according to a first embodiment. [Figure 2] FIG. 3 is a conceptual diagram for explaining the state of a plurality of secondary batteries in the first embodiment. [Figure 3] FIG. 10 is a conceptual diagram for explaining another state of the plurality of secondary batteries in the first embodiment. [Figure 4] 3 is a conceptual diagram showing a change in power of the battery system in the first embodiment. [Figure 5] FIG. 6 is another conceptual diagram showing changes in power of the battery system in the first embodiment. [Figure 6] 3 is a flow chart showing a control mode of the battery system in the first embodiment. [Figure 7] FIG. 10 is a conceptual diagram for explaining the state of a plurality of secondary batteries in the second embodiment. [Figure 8] FIG. 10 is a conceptual diagram showing dischargeable power for each group in the second embodiment. [Figure 9] FIG. 10 is a flow chart showing a control mode of the battery system in the second embodiment. [Figure 10] FIG. 11 is a conceptual diagram for explaining the state of a plurality of secondary batteries in the third embodiment. [Figure 11] FIG. 11 is a conceptual diagram showing dischargeable power for each group in the third embodiment. [Figure 12] FIG. 11 is a conceptual diagram showing changes in power of a battery system in a third embodiment. [Figure 13] FIG. 11 is a conceptual diagram for explaining the state of remaining capacity for each group in the third embodiment. [Figure 14] FIG. 11 is a flow chart showing a control mode of the battery system in the third embodiment. [Figure 15] FIG. 10 is a conceptual diagram showing changes in power of a battery system in a fourth embodiment. [Figure 16] FIG. 13 is a conceptual diagram for explaining the state of a plurality of secondary batteries in the fifth embodiment. [Figure 17] FIG. 13 is a conceptual diagram showing changes in power of a battery system in a fifth embodiment. [Figure 18] FIG. 13 is a conceptual diagram showing the relationship between charging power and deterioration rate in the fifth embodiment. [Figure 19] FIG. 11 is a flow chart showing a control mode of the battery system in the fifth embodiment. [Figure 20] FIG. 20 is a conceptual diagram for explaining the state of a plurality of secondary batteries in the sixth embodiment. [Figure 21] FIG. 13 is a conceptual diagram showing changes in power of a battery system in a sixth embodiment. [Figure 22] FIG. 13 is a flow chart showing a control mode of the battery system in the sixth embodiment. [Figure 23] FIG. 13 is a block diagram showing the configuration of a battery system according to a seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment 1) An embodiment of the battery system will be described with reference to FIGS. As shown in FIG. 1, the battery system 1 of the first embodiment is configured to perform charging and discharging in response to a charging and discharging request from a host system 100. The battery system 1 includes a plurality of secondary batteries 10, a battery state acquisition unit 20, a charge / discharge request acquisition unit 30, a grouping unit 40, a command value derivation unit 50, and a charge / discharge control unit 60. The battery status acquisition unit 20 acquires the battery status of the multiple secondary batteries 10 . The charge / discharge request acquisition unit 30 acquires a charge / discharge request from the host system 100 . The grouping unit 40 dynamically divides the multiple secondary batteries 10 into multiple groups according to the battery states of the multiple secondary batteries 10 acquired by the battery state acquisition unit 20 and the charge / discharge requests acquired by the charge / discharge request acquisition unit 30. The command value derivation unit 50 derives a charge / discharge command value that defines a distribution power for distributing the power according to the charge / discharge request to each of the groups. The charge / discharge control unit 60 then charges and discharges the multiple secondary batteries 10 based on the charge / discharge command values.

[0012] The battery system 1 of this embodiment will be described in detail below. 1, a battery system 1 of this embodiment is connected to a host system 100 and is used as a power source for the host system 100. The configuration of the host system 100 is not particularly limited, and may be, for example, a large device such as a factory facility, a small device such as a home facility, or a charging / discharging device provided at a charging station, repair facility, or the like.

[0013] The multiple secondary batteries 10 shown in FIG. 1 may be rechargeable batteries, and there are no limitations on their type or battery configuration. In this embodiment, first to seventh secondary batteries 11 to 17 are provided as the multiple secondary batteries 10. The secondary batteries 11 to 17 all have the same configuration. The secondary batteries 11 to 17 may each be composed of a single cell, or may be composed of a battery pack made up of a battery assembly in which multiple battery elements are electrically connected. The secondary batteries 11 to 17 do not necessarily have to have the same configuration, and some of the secondary batteries 11 to 17 may have different battery configurations. In this embodiment, the secondary batteries 10 each constitute a power source for use in a vehicle.

[0014] As shown in Fig. 1, power conditioning systems (PCS) 11a to 17a are connected to the secondary batteries 11 to 17, respectively. The PCSs 11a to 17a individually receive charge / discharge command values ​​from a charge / discharge control unit 60 (described later), and supply power specified by the respective charge / discharge command values ​​to the secondary batteries 11 to 17, thereby charging and discharging the secondary batteries 11 to 17. The PCSs 11a to 17a may be those mounted on charge / discharge devices installed at charge / discharge stations, repair facilities, etc. In this specification, "charge / discharge" includes any of the cases of charging only, discharging only, and both charging and discharging.

[0015] The battery status acquisition unit 20 shown in FIG. 1 acquires the battery status of multiple secondary batteries 10. The battery status may include one or more of the internal resistance, capacity retention rate, remaining capacity, etc. of the secondary batteries 10. In the first embodiment, the battery status acquisition unit 20 acquires the internal resistance and remaining capacity of the multiple secondary batteries 10 as the battery status. The configuration of the battery status acquisition unit 20 can be appropriately set according to the type of battery status to be acquired. In this embodiment, the battery status acquisition unit 20 includes a voltage sensor, a current sensor, and a temperature sensor (not shown) and an internal resistance calculation unit that calculates the internal resistance of the multiple secondary batteries 10 from the acquired voltage and current values ​​to acquire the internal resistance as the battery status. Furthermore, to acquire the remaining capacity of the multiple secondary batteries 10 as the battery status, the battery status acquisition unit 20 may have, for example, a map created in advance that indicates the correspondence between voltage values ​​and remaining capacity. The battery status acquired by the battery status acquisition unit 20 is stored in a storage unit (not shown). The storage unit may be configured with a rewritable nonvolatile memory. The timing at which the battery status acquisition unit 20 acquires the battery status is not limited, but the battery status can be acquired at any time during the period from when the charge / discharge request acquisition unit 30 described below acquires a request to start charging or a request to start discharging until when the charge / discharge request acquisition unit 30 acquires a request to stop charging or discharging.

[0016] The charge / discharge request acquisition unit 30 shown in FIG. 1 acquires a charge / discharge request from the upper system 100. The charge / discharge request includes at least one of a request to start charging the battery system 1, a request to start discharging the battery system 1, and a request to stop charging / discharging. The charge / discharge request may also include information regarding charging power and discharging power. The charge / discharge request may also be based on a power demand forecast or usage plan created in advance. The configuration of the charge / discharge request acquisition unit 30 is not particularly limited, and may be any configuration that can substantially acquire the charge / discharge request transmitted from the upper system 100. The charge / discharge request acquired by the charge / discharge request acquisition unit 30 can be stored in the above-mentioned storage unit (not shown).

[0017] The grouping unit 40 shown in FIG. 1 dynamically divides the secondary batteries 10 into multiple groups based on the battery states of the secondary batteries 10 acquired by the battery state acquisition unit 20 and the charge / discharge requests acquired by the charge / discharge request acquisition unit 30. The grouping unit 40 can be configured by a computing device. "Dynamic division of the secondary batteries 10 into multiple groups" refers to updating the grouping as needed based on changes in the battery states acquired by the battery state acquisition unit 20, changes in the charge / discharge requests acquired by the charge / discharge request acquisition unit 30, and whether the secondary batteries 10 can be charged or discharged. The number of groups can be two or more. The number of secondary batteries belonging to one group can be one or more. Therefore, in this embodiment, which has seven secondary batteries 11 to 17, the secondary batteries 11 to 17 can be divided into a maximum of seven groups.

[0018] The grouping process performed by the grouping unit 40 includes a first process for determining whether each of the plurality of secondary batteries 10 is chargeable or dischargeable; a second process for determining the number of groups into which the plurality of secondary batteries 10 are to be divided; and a third process for dividing the plurality of secondary batteries 10 determined to be chargeable or dischargeable into a plurality of groups. In the first process, the remaining capacities of the plurality of secondary batteries 10 acquired by the battery status acquisition unit 20 are compared with a preset reference value. For example, when a charge / discharge request is a discharge start request, a secondary battery 10 is determined to be dischargeable if its remaining capacity is equal to or greater than the discharge reference value. In this embodiment, as shown in FIG. 2 , among the remaining capacities P1 to P7 of the secondary batteries 11 to 17 that make up the plurality of secondary batteries 10, the seventh secondary battery 17 has a remaining capacity P7 that is lower than the discharge reference value. Therefore, the seventh secondary battery 17 is determined to be undischargeable, as indicated by the symbol ×, while the remaining secondary batteries 11 to 16 are determined to be dischargeable, as indicated by the symbol ◯.

[0019] Next, in the second process, the number of groups into which the secondary batteries 11 to 16 determined to be dischargeable in the first process are divided is determined. The method for determining the number of groups is not limited, and the number of groups can be determined based on the charge / discharge power requested by the host system 100 and the dischargeable power of the secondary batteries 11 to 16 determined to be dischargeable. In the first embodiment, the number of groups is set to 2 because it can be determined that the charge / discharge power requested by the host system 100 is satisfied when the number of groups is set to 2.

[0020] Next, in the third process, for those of the multiple secondary batteries 10 that are determined to be dischargeable in the first process, the internal resistance acquired by the battery state acquisition unit 20 is compared with a resistance reference value. The resistance reference value is not particularly limited, and may be, for example, the average value of the acquired internal resistances, a deviation from the average value, or a preset value. In this embodiment, the average value of the internal resistances of the secondary batteries 11 to 16 of the multiple secondary batteries 10 is set as the resistance reference value. Then, the secondary batteries 11 to 16 having an internal resistance equal to or greater than the resistance reference value are grouped as group A having a high internal resistance, and the secondary batteries having an internal resistance less than the resistance reference value are grouped as group B having a low internal resistance.

[0021] On the other hand, in a first process in the grouping unit 40 when the charge / discharge request is a charge start request, it is determined that the secondary battery 10 is chargeable if the remaining capacity is less than the charge reference value. In this embodiment, as shown in Fig. 3, of the remaining capacities P1 to P7 of the secondary batteries 11 to 17 that make up the multiple secondary batteries 10, the remaining capacity P7 of the seventh secondary battery 17 is higher than the charge reference value, so it is determined that it is not chargeable as indicated by the symbol x, and the other secondary batteries 11 to 16 are chargeable as indicated by the symbol o. Note that the second and third processes in the grouping unit 40 when the charge / discharge request is a charge start request can be performed by replacing "discharge" with "charge" when the charge / discharge request is a discharge start request.

[0022] The command value derivation unit 50 shown in FIG. 1 derives a charge / discharge command value that defines the distribution power for distributing power to each of the groups according to the charge / discharge request. The command value derivation unit 50 can be configured with a computing device. While there are no limitations on the method for defining the distribution power for each group, if the battery information is internal resistance, the distribution power can be defined so that it is inversely proportional to the total internal resistance of each group, regardless of whether the battery is being discharged or charged. For example, in the case shown in FIG. 4, the ratio of the total internal resistances of group A, which has high internal resistance, to group B, which has low internal resistance, is approximately 3:1. Therefore, the system required power Pt is distributed such that the distribution power Pb of group B is three times the distribution power Pa of group A. As a result, in FIG. 4, the distribution power Pa of group A can be represented by curve R, and the distribution power Pb of group B can be represented by the system required power Pt minus the distribution power Pa of group A. Note that the distribution of the distribution power to each secondary battery in each group can be performed inversely proportional to the internal resistances within the group.

[0023] 5, the distributed power Pa of group A, which has a high internal resistance, can be set to a predetermined value, and the variable portion obtained by subtracting the distributed power Pa of group A from the power Pt requested from higher-level system 100 can be set to the distributed power Pb of group B, which has a low internal resistance. Then, at time Ta, when the power Pt required by the system decreases and the distributed power Pb of group B matches the distributed power Pa of group A, the distributed power Pa of group A is set to 0, and only the distributed power Pb of group B remains. Then, when the power Pt required by the system increases again, and at time Tb the distributed power Pb of group B reaches twice the predetermined value of the power Pa of group A, the distributed power Pa of group A is set to the predetermined value, and the remainder is set to the distributed power Pb of group B. Furthermore, when the system required power Pt decreases and the distributed power Pb of group B again matches the distributed power Pa of group A at time Tc, the distributed power Pa of group A is set to 0 and only the distributed power Pb of group B is left, and only the distributed power Pb of group B may be specified until the system required power Pt becomes 0 at time Td.

[0024] The charge / discharge control unit 60 shown in FIG. 1 charges and discharges a plurality of secondary batteries 10 based on a charge / discharge command value. The charge / discharge control unit 60 can be configured with a calculation device. As described above, the charge / discharge command value is defined for each group, so that one or more secondary batteries belonging to the same group are charged and discharged based on the same charge / discharge command value. For example, as shown in FIG. 2, secondary batteries 11, 12, and 13 belonging to group A are discharged based on the same charge / discharge command value, and secondary batteries 14, 15, and 16 belonging to group B are discharged based on the same charge / discharge command value. In this embodiment, the charge / discharge control unit 60 transmits charge / discharge command values ​​to PCSs 11a to 16a connected to the secondary batteries 11 to 16, thereby controlling the charging and discharging of the secondary batteries 11 to 16 via the PCSs 11a to 16a.

[0025] Next, a control flow of charging and discharging by the battery system 1 in the first embodiment will be described in detail with reference to FIG. First, in step S1 shown in Fig. 6, the battery state acquisition unit 20 determines whether or not it has acquired a charge / discharge request from the host system 100. If the battery state acquisition unit 20 has not acquired a charge / discharge request, the process proceeds to No in step S1 and returns to step S1 again. If the battery state acquisition unit 20 has acquired a charge / discharge request from the host system 100 in step S1, the process proceeds to Yes in step S1, and in step S2 it is determined whether or not the charge / discharge request is a request to start discharging. This determination is made by the charge / discharge control unit 60. If it is determined in step S2 that the charge / discharge request is a request to start discharging, the process proceeds to Yes in step S2.

[0026] 6, the battery state acquisition unit 20 acquires the remaining capacity of the secondary batteries 11 to 17. After that, in step S4, the grouping unit 40 compares the remaining capacity with a discharge reference value and extracts those batteries with remaining capacity greater than the discharge reference value as dischargeable secondary batteries 11 to 16. Then, in step S5, the battery state acquisition unit 20 acquires the internal resistance of the dischargeable secondary batteries 11 to 16.

[0027] 6, the grouping unit 40 sets the number of groups based on the charge / discharge power requested by the higher-level system 100 and the dischargeable power of the secondary batteries 10 determined to be dischargeable. In the first embodiment, the number of groups is set to 2. Then, in step S7, the internal resistances of the secondary batteries 11 to 16 determined to be dischargeable are compared with an average resistance which is the average value of these resistances, and of the secondary batteries 11 to 16 determined to be dischargeable, those having an internal resistance equal to or greater than the average resistance are grouped as group A, and those having an internal resistance less than the average resistance are grouped as group B.

[0028] 6, the command value derivation unit 50 derives charge / discharge command values ​​that define the distribution power Pa, Pb for distributing the system required power Pt, which is power corresponding to the charge / discharge request from the host system 100, to each of the groups A and B. After that, in step S9, the charge / discharge control unit 60 starts discharging the secondary batteries 11-16 based on the charge / discharge command values. In this embodiment, as shown in FIG. 4, the ratio of the total values ​​of the internal resistances of the groups A and B is approximately 3:1, so that the system required power Pt corresponding to the charge / discharge request from the host system 100 is distributed in the inverse ratio, i.e., the distribution power Pb of the group B is three times the distribution power Pa of the group A.

[0029] 6, the battery state acquisition unit 20 determines whether or not it has received a request to stop charging / discharging from the upper system 100. If the battery state acquisition unit 20 has not received a request to stop charging / discharging in step S10, the process proceeds to No in step S10, returns to step S2, and repeats step S2 and subsequent steps. On the other hand, if the battery state acquisition unit 20 has received a request to stop charging / discharging in step S10, the charge / discharge control unit 60 stops charging / discharging of the secondary batteries 11-16 via the PCSs 11a-16a, and then proceeds to Yes in step S10, ending the flow.

[0030] On the other hand, if it is determined in step S2 shown in FIG. 6 that the charge / discharge request is not a request to start discharging, the process proceeds to No in step S2. Then, in step S12, it is determined whether the charge / discharge request is a request to start charging. This determination is made by the charge / discharge control unit 60. If it is determined in step S12 that the charge / discharge request is a request to start charging, the process proceeds to Yes in step S12. Thereafter, steps S13 to S19 are performed. Note that steps S13 to S19 are performed by replacing discharging in steps S3 to S19 in the case of discharging described above with charging. Note that if it is determined in step S12 that the charge / discharge request is not a request to start charging, the process proceeds to No in step S12, and step S10 and subsequent steps are performed.

[0031] As described above, according to the control flow of the battery system 1, the distributed power Pa of group A, which has a high degree of resistance degradation and a high internal resistance, is reduced, and the distributed power Pb of group B, which has a low degree of resistance degradation and a low internal resistance, is increased, thereby reducing power loss due to internal resistance and suppressing the progression of deterioration of the secondary batteries of group A, which has a high degree of resistance degradation.

[0032] According to the control flow shown in FIG. 6, in the case of discharging, steps S2 to S9 are repeatedly performed until charging and discharging are stopped, so that grouping is performed as needed. For example, as discharging progresses, a secondary battery 10 whose remaining capacity reaches a discharge reference value is removed from the list of secondary batteries that can be discharged, and the group configuration is updated. Furthermore, if the internal resistance of a secondary battery 10 changes and the result of comparison with the average resistance changes, the group configuration is also updated. Similarly, in the case of charging, steps S12 to S19 shown in FIG. 6 are repeatedly performed, so that grouping is performed as needed. For example, as charging progresses, a secondary battery 10 whose remaining capacity reaches a charge reference value is removed from the list of secondary batteries that can be charged, and the group configuration is also updated. Furthermore, if the internal resistance of a secondary battery 10 changes and the result of comparison with the average resistance changes, the group configuration is also updated. Therefore, according to the control flow of the battery system 1, multiple secondary batteries 10 are dynamically grouped according to their battery states and charging and discharging requests.

[0033] Next, the effects of the battery system 1 of the first embodiment will be described in detail. In the battery system 1 of the first embodiment, multiple secondary batteries 10 are dynamically grouped according to their battery states and charging / discharging requests. Then, power according to the charging / discharging requests is distributed to each group, and each group is charged / discharged using the distributed power, with charging / discharging controlled for each group. This simplifies the charge / discharge control compared to individually controlling the charging / discharging of multiple secondary batteries 10, and the control is not complicated even when the grouping is performed dynamically as described above. As a result, it becomes easier to control charging / discharging in real time according to the charging / discharging requests, thereby improving the efficiency of charging / discharging. Furthermore, because the grouping is performed based on the battery states of the secondary batteries 10, charging / discharging can be performed taking into account the degradation state of the secondary batteries 10, thereby extending the life of the secondary batteries 10.

[0034] Furthermore, in the first embodiment, the battery state acquisition unit 20 acquires the value of internal resistance as a numerical value representing the battery state of the secondary battery 10, and the grouping unit 40 compares the numerical value acquired by the battery state acquisition unit 20 with a reference value to divide the multiple secondary batteries 10 into groups. This allows for more accurate grouping based on the battery state of the secondary batteries 10, making it possible to charge and discharge the secondary batteries 10 while taking into account their degradation state, thereby further extending the lifespan of the secondary batteries 10.

[0035] Furthermore, in the first embodiment, the command value derivation unit 50 determines the power to be distributed to each group based on the battery state of the secondary batteries 10 included in each group. This allows the power to be distributed according to the degree of deterioration of the secondary batteries 10 included in the group, thereby suppressing the progression of deterioration of the secondary batteries 10 and further extending the lifespan of the secondary batteries 10.

[0036] Furthermore, in the first embodiment, the battery state of the secondary battery 10 includes its internal resistance. This allows control to be performed that suppresses power loss due to internal resistance, and improves the efficiency of charging and discharging.

[0037] Furthermore, in the first embodiment, the multiple groups divided by the group division unit 40 include a first group A consisting of secondary batteries 10 having a predetermined internal resistance and a second group B consisting of secondary batteries having an internal resistance smaller than that of the secondary batteries included in the first group A. The command value derivation unit 50 derives the charge / discharge command value so that the first distributed power Pa distributed to the first group A is smaller than the second distributed power Pb distributed to the second group B. This makes it possible to suppress power loss due to internal resistance and to suppress the progression of deterioration of the secondary batteries in group A, thereby further achieving both efficient charging and discharging and a longer lifespan for the secondary batteries 10. .

[0038] As described above, according to the first embodiment, it is possible to provide the battery system 1 that can improve the efficiency of charging and discharging and extend the life of the secondary battery 10.

[0039] (Embodiment 2) In the above-described first embodiment, the internal resistance of the plurality of secondary batteries 10 is used as the battery state, and the grouping unit 40 performs grouping by comparing the internal resistance with an average resistance. However, in the second embodiment, instead, the grouping unit 40 ranks the plurality of secondary batteries 10 based on their battery states, and divides the plurality of secondary batteries 10 into a plurality of groups based on the rank. Note that the internal resistance is also used as the battery state in the second embodiment. Note that the other components are the same as in the first embodiment, and in the second embodiment, components equivalent to those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0040] The grouping unit 40 can rank the secondary batteries 10 in descending order based on the magnitude of the internal resistance acquired by the battery state acquisition unit 20. For example, as shown in FIG. 7, the first secondary battery 11 has the highest internal resistance and is ranked first, while the seventh secondary battery 17 has the lowest internal resistance and is ranked seventh. The grouping unit 40 then divides the secondary batteries 10 into two groups, a first group A with the highest rank and a second group B with the lowest rank. As shown in FIG. 8, the grouping is performed so that the total remaining capacity, which is the dischargeable power for each group, satisfies the discharge power required by the host system 100. For example, as shown in FIGS. 7 and 8, the secondary batteries 11 to 14 belong to the first group A, and the secondary batteries 15 to 17 belong to the second group B. Note that other components are the same as those in the first embodiment, and in the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals and their description is omitted.

[0041] Next, a control flow of charging and discharging in the battery system 1 in the second embodiment will be described in detail with reference to FIG. First, steps S1 to S6 shown in FIG. 9 are the same as those in the first embodiment shown in FIG. 6. Then, after step S6 shown in FIG. 9, the process proceeds to step S70. In step S70, the grouping unit 40 divides the secondary batteries 10 into a first group A and a second group B based on the ranking of their internal resistances. Then, steps S8 to S10 are performed in the same manner as in the first embodiment shown in FIG. 6. Furthermore, steps S12 to S16 shown in FIG. 9 are the same as those in the first embodiment shown in FIG. 6. Then, after step S16 shown in FIG. 9, the process proceeds to step S170. In step S170, the grouping unit 40 divides the secondary batteries 10 into a first group A and a second group B based on the ranking of their internal resistances. Then, steps S18 to S19 are performed in the same manner as in the first embodiment shown in FIG. 6. The control flow of the second embodiment also achieves the same effects as those in the first embodiment.

[0042] (Embodiment 3) In the first and second embodiments, the internal resistance of the secondary battery 10 is used as the battery state. In the third embodiment, the capacity retention rate of the secondary battery 10 is used as the battery state. The capacity retention rate indicates the ratio of the current full charge capacity of the secondary battery 10 to the initial full charge capacity of the secondary battery 10. For example, the capacity retention rate of the first secondary battery 11 shown in FIG. 10 can be calculated as Qb / Qa, which is the ratio of the current full charge capacity Qb to the initial full charge capacity Qa. Since the capacity retention rate decreases as the deterioration of the secondary battery progresses, it can be inferred that a secondary battery with a low capacity retention rate has a high degree of deterioration. Note that the other components are the same as those in the first and second embodiments. In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and their description will be omitted.

[0043] In the third embodiment, the grouping unit 40 performs different grouping during charging and discharging. Grouping during discharging will be described in detail below. In the third embodiment, the grouping unit 40 ranks the multiple secondary batteries 10 as groups during discharging based on the capacity maintenance rate, and divides the multiple secondary batteries 10 into multiple groups based on the rank. The ranking of the multiple secondary batteries 10 by the grouping unit 40 can be assigned in ascending order based on the value of the capacity maintenance rate acquired by the battery state acquisition unit 20.

[0044] The ascending order of capacity maintenance rates of the secondary batteries 11-17 constituting the plurality of secondary batteries 10 is, for example, as shown in FIG. 10, such that the first secondary battery 11 has the lowest capacity maintenance rate and is ranked first, and the seventh secondary battery 17 has the highest capacity maintenance rate and is ranked seventh. The grouping unit 40 then divides the number of groups into three, with the first group A being the highest, the middle group B being the middle group, and the bottom group C being the lowest. As shown in FIG. 11, the secondary batteries 11-17 are divided into groups A-C so that the total remaining capacity, which is the dischargeable power for each group, satisfies the discharge power required by the host system 100. For example, as shown in FIGS. 10 and 11, the secondary batteries 11-13 belong to the first group A, the secondary batteries 14 and 15 belong to the second group B, and the secondary batteries 16 and 17 belong to the third group C. That is, when the deterioration levels of the secondary batteries 10 included in each of the groups A to C are compared on a group-by-group basis, it can be said that the first group A has a high degree of deterioration, the second group B has a medium degree of deterioration, and the third group C has a low degree of deterioration. The number of secondary batteries included in the first group A, which includes the secondary battery 11 with the lowest capacity maintenance rate, is three, which is fewer than the total number of secondary batteries 14 and 15 included in the second group B and secondary batteries 16 and 17 included in the third group C, which is four.

[0045] In the third embodiment, the command value derivation unit 50 determines the power distribution for each of the groups A to C based on the capacity maintenance rate of the secondary batteries 10 included in each of the groups A to C. In the third embodiment, a case where the charge / discharge request from the host system 100 is discharge will be described. As shown in FIGS. 12 and 13(a), in a first section from the discharge start time T0 to the first time T1, the power distribution ratio for the groups A, B, and C is set to 1:0:0, and only the first group A, which is highly deteriorated, is discharged. The first time T1 is defined as the time when the remaining capacity of the secondary batteries belonging to the first group A reaches the dischargeable standard. As shown in FIGS. 12 and 13(b), in a second section from the first time T1 to the second time T2, the distribution ratio is set to 0:1:0, and discharging of the first group A, which is highly deteriorated, is stopped, and only the second group B, which is medium deteriorated, is discharged. The third time T3 is defined as the time when the remaining capacity of the secondary batteries belonging to the second group B reaches the dischargeable standard. 12 and 13(c), in the third interval from the second time T2 to the third time T3, the distribution ratio is set to 0:0:1, discharging of the second group B, which has a medium degree of degradation, is stopped, and only the third group C, which has a low degree of degradation, is discharged. The discharge power of each secondary battery 10 in the group can be distributed so that the larger the remaining capacity, the larger the distribution.

[0046] Next, a control flow of charging and discharging in the battery system 1 according to the third embodiment will be described in detail with reference to FIG. First, steps S1 to S4 shown in Fig. 14 are the same as those in the first embodiment shown in Fig. 6. In step S2, if the charge / discharge request is discharge, the control flow for charge in the fifth or sixth embodiment described below can be implemented.

[0047] In the third embodiment, after step S4 shown in FIG. 14, in step S50, the battery state acquisition unit 20 acquires the capacity maintenance rates of the dischargeable secondary batteries 10. Thereafter, in step S61, the grouping unit 40 sets the number of groups based on the charge / discharge power requested by the upper system 100 and the dischargeable power of the secondary batteries 10 determined to be dischargeable. In the third embodiment, the number of groups is set to three. Then, in step S71, the grouping unit 40 divides the multiple secondary batteries 10 into groups A, B, and C based on the ranking of the capacity maintenance rates. In the third embodiment, as shown in FIG. 10, the grouping is performed in order from the lowest capacity maintenance rate so that each group satisfies the system required power shown in FIG. 11.

[0048] Next, in step S81 shown in Fig. 14, the command value derivation unit 50 derives charge / discharge command values ​​that define the distributed power Pa, Pb, and Pc of groups A to C as shown in Fig. 15, based on the distribution ratio shown in Fig. 12, for power corresponding to a charge / discharge request from the upper system 100. After that, in step S9 shown in Fig. 14, the charge / discharge control unit 60 starts discharging the secondary battery 10 based on the charge / discharge command values.

[0049] 14, it is determined whether the battery state acquisition unit 20 has received a request to stop charging / discharging from the upper system 100. If the battery state acquisition unit 20 has not received a request to stop charging / discharging in step S10, the process proceeds to No in step S10, returns to step S2, and repeats step S2 and subsequent steps. On the other hand, if the battery state acquisition unit 20 has received a request to stop charging / discharging in step S10, the charge / discharge control unit 60 stops charging / discharging of the secondary battery 10 via the PCSs 11a to 17a, and the process proceeds to Yes in step S10, ending the flow.

[0050] According to the control flow of the third embodiment, the secondary batteries 11 to 13 belonging to group A, which have a low capacity maintenance rate, i.e., a high degree of degradation, are preferentially discharged. This makes it possible to shorten the time during which the highly degraded secondary batteries 11 to 13 have a high remaining capacity compared to the other secondary batteries 14 to 17. Since the progress of degradation of secondary batteries accelerates when the remaining capacity is high, shortening the time during which the remaining capacity is high can suppress the progress of degradation of the highly degraded secondary batteries 11 to 13. As a result, the life of the secondary battery 10 can be extended.

[0051] Furthermore, in the third embodiment, steps S2 to S9 are repeated until the discharge is stopped, so that secondary batteries 10 whose remaining capacity has reached the discharge reference value as the discharge progresses are excluded from the secondary batteries that can be discharged, and the group configuration is updated as needed. Therefore, the above grouping is performed dynamically, making it easy to control discharge in real time according to discharge requests, and improving discharge efficiency.

[0052] In the third embodiment, the discharging groups include a first group A including the secondary battery 11 with the lowest capacity maintenance rate, and groups B and C other than the first group A, and the number of secondary batteries included in the first group A is smaller than the number of secondary batteries included in the groups B and C other than the first group A. This allows the secondary batteries 11 to 13 included in the first group A with a low capacity maintenance rate, i.e., with a high degree of degradation, to be discharged early, and the remaining capacity can be reduced from a high state to a low state early, thereby suppressing the progression of degradation and lengthening the life of the secondary batteries 10.

[0053] (Embodiment 4) In the above-described third embodiment, the secondary batteries 10 were divided into groups A to C using the capacity maintenance rates of the secondary batteries 10 as the battery states, and the value of the distribution ratio when distributing the system required power Pt to groups A to C was set to either 0 or 1. Instead, in the fourth embodiment, the distribution ratio is set to the inverse ratio of the capacity maintenance rates of groups A to C, and the distributed powers Pa, Pb, and Pc are set. Note that the capacity maintenance rate of each group can be the sum of the capacity maintenance rates of the secondary batteries included in that group, or the average value of the capacity maintenance rates of the secondary batteries included in that group.

[0054] In the fourth embodiment, the power distribution ratios for groups A to C are set to the inverse ratio of the capacity maintenance rates of groups A to C. As shown in FIG. 15 , from the start to the end of discharge, the distributed power Pa for the first group A, which has the highest degree of degradation, is the highest, the distributed power Pb for the second group B, which has a medium degree of degradation, is the next highest, and the distributed power Pc for the third group C, which has the lowest degree of degradation, is the lowest. This allows the highly degraded secondary batteries 11 to 13 to be actively discharged to reduce their remaining capacity, thereby suppressing the progression of degradation of the secondary batteries 11 to 13. As a result, the life of the secondary battery 10 can be extended. Note that the other components are the same as in the third embodiment, and in the fourth embodiment, the same components as in the fourth embodiment are denoted by the same reference numerals and their description will be omitted. Furthermore, in the control flow of the fourth embodiment, when determining the distributed power in step S81 of the third embodiment shown in FIG. 14 , the power distribution ratio for groups A to C is set to the inverse ratio of the capacity maintenance rates of groups A to C, as described above, and the other steps can be the same as in the third embodiment.

[0055] In the fourth embodiment, the discharging groups include a first group A including the secondary battery 11 with the lowest capacity retention rate and a second group B made up of secondary batteries having a capacity retention rate higher than that of the secondary batteries 11 included in the first group A, and the first distributed power Pa distributed to the first group A is equal to or greater than the second distributed power Pb distributed to the second group B. This allows the secondary batteries 11 to 13 included in the first group A with low capacity retention rates, i.e., with a high degree of degradation, to be discharged early, quickly changing the remaining capacity from a high state to a low state, thereby suppressing the progression of degradation and lengthening the life of the secondary batteries 10.

[0056] (Embodiment 5) The fifth embodiment corresponds to a control mode in which the charge / discharge request from the upper system 100 is charging in the configurations of the above-described third and fourth embodiments. The components in the fifth embodiment are the same as those in the third embodiment, and the same reference numerals as those in the third embodiment are used, and the description thereof will be omitted.

[0057] In the fifth embodiment, the grouping unit 40 ranks the secondary batteries 10 based on the capacity maintenance rate as a battery state of the secondary batteries 10, and divides the secondary batteries 10 into groups based on the rank. The grouping unit 40 can rank the secondary batteries 10 in ascending order based on the value of the capacity maintenance rate acquired by the battery state acquisition unit 20. For example, as shown in FIG. 16 , the ascending order of the capacity maintenance rates of the secondary batteries 11 to 17 constituting the secondary batteries 10 is such that the first secondary battery 11 is ranked first and the seventh secondary battery 17 is ranked seventh. The grouping unit 40 sets the number of groups to two, and sets a first group A with a higher rank and a second group B with a lower rank as charging groups. As a result, the first group A is a group with a high degree of degradation, and the second group B is a group with a low degree of degradation. The grouping unit 40 then divides the four secondary batteries 11-13, which are the first to fourth highest ranked batteries, into a first group A, and the three secondary batteries 14-17, which are the fifth to seventh lowest ranked batteries, into a second group B. As a result, the number of secondary batteries belonging to the first group A is greater than the number of secondary batteries belonging to the second group B. The charge reference value for determining whether charging is possible can be defined as a predetermined value of the state of charge SOC, which is the remaining capacity relative to the current full charge capacity, and it can be determined that charging is possible when the state of charge SOC of the secondary battery 10 is less than the charge reference value.

[0058] In the fifth embodiment, the command value derivation unit 50 can define the distributed power Pa of the first group A having a high degree of degradation and the distributed power Pb of the second group B having a low degree of degradation to be inversely proportional to the capacity maintenance rate of each group. For example, in the case shown in FIG. 17 , the ratio of the capacity maintenance rates of the first group A and the second group B is 3:1, so the distributed power Pb of the second group B is set to three times the distributed power Pa of the first group A, and the system-required discharge power Pt is distributed. Furthermore, since the power during charging and the rate of degradation have the correlation shown in FIG. 18 , in the fifth embodiment, the distributed power Pa of the first group A having a high degree of degradation is controlled to be less than Px, at which the rate of degradation is maintained low, as shown in FIG. 17 .

[0059] Next, a control flow for charging in the battery system 1 in the fifth embodiment will be described in detail. First, in step S2 in Fig. 14 of the above-described third embodiment, after it is determined that the charge / discharge request is not discharge, the process proceeds to symbol A, where steps S12 to S14 shown in Fig. 19 are performed. Steps S12 to S14 in Fig. 19 are equivalent to steps S12 to S14 in the above-described first embodiment shown in Fig. 6.

[0060] 19, the battery state acquisition unit 20 acquires the capacity maintenance rates of the rechargeable secondary batteries 10. Then, in step S161, the grouping unit 40 sets the number of groups based on the charge / discharge power requested by the upper system 100 and the chargeable power of the secondary batteries 10 determined to be chargeable. In the fifth embodiment, the number of groups is set to two. Then, in step S171, the grouping unit 40 divides the multiple secondary batteries 10 into groups A and B based on the ranking of the capacity maintenance rates. This grouping is performed so that each group satisfies the system required power, and the number of secondary batteries belonging to the first group A is greater than the number of secondary batteries belonging to the second group B.

[0061] 19, the command value derivation unit 50 derives a charge / discharge command value for reducing the distributed power Pa of the first group A having a high degree of degradation to less than Px shown in FIG. 17, and distributing the remainder to the second group B having a low degree of degradation, in response to the charge / discharge request from the higher-level system 100. Then, in step S19, the charge / discharge control unit 60 starts charging the secondary battery 10 via the PCSs 11a to 17a based on the charge / discharge command value. Thereafter, the process proceeds to step S10 and subsequent steps in FIG. 14 of the third embodiment described above.

[0062] In the fifth embodiment, the charging groups include a first group A including the secondary battery 11 with the lowest capacity maintenance rate, and a second group B other than the first group A, and the number of secondary batteries included in the first group A is greater than the number of secondary batteries included in the second group B. This makes it easier to maintain low charging power for each secondary battery in the first group A, thereby suppressing the progress of deterioration of the secondary batteries belonging to the first group A, which have a high degree of deterioration, and thereby achieving a longer lifespan.

[0063] Furthermore, in the fifth embodiment, the charging groups include a first group A including the secondary battery 11 with the lowest capacity maintenance rate, and the first distributed power Pa distributed to the first group A is a value within a range that does not promote deterioration of the secondary batteries distributed to the first group A, that is, a value equal to or less than Px at which the rate of deterioration is maintained low. This makes it possible to suppress the progress of deterioration of the secondary batteries 11 to 13 in the first group A, which have a high degree of deterioration, and to extend the life of the secondary battery 10.

[0064] Furthermore, in this fifth embodiment, steps S12 to S19 are repeated until charging is stopped, so that secondary batteries 10 whose SOC has reached the charging reference value as charging progresses are excluded from the list of chargeable secondary batteries, and the group configuration is updated as needed. Therefore, because the grouping is performed dynamically, it becomes easy to control charging in real time in response to charging requests, and charging can be made more efficient.

[0065] (Embodiment 6) The sixth embodiment corresponds to a different control mode from the fifth embodiment when the charge / discharge request from the upper system 100 is discharge in the configurations of the third and fourth embodiments. In the sixth embodiment, the grouping unit 40, like the fifth embodiment, assigns a rank to the secondary batteries 10 based on the capacity maintenance rate as the battery state of the secondary batteries 10, and divides the secondary batteries 10 into a plurality of groups as charging groups based on the rank. In the sixth embodiment, as shown in FIG. 20, the grouping unit 40, like the fifth embodiment, defines the ascending rank of the capacity maintenance rate of the secondary batteries 11 to 17 constituting the plurality of secondary batteries 10. Then, the number of groups is set to 3 The first to third highest ranking charging groups are grouped as a first group A with a high degree of deterioration, the fourth and fifth middle ranking charging groups are grouped as a second group B with a medium degree of deterioration, and the sixth and seventh lowest ranking charging groups are grouped as a third group C with a low degree of deterioration. The determination of whether charging is possible can be made in the same way as in the fifth embodiment.

[0066] In the sixth embodiment, as shown in FIG. 21 , the command value derivation unit 50 defines, in section A, the distributed power Pa of the first group A having a high degree of degradation and the distributed power Pc of the third group C having a low degree of degradation so that the ratio is the inverse of the capacity maintenance rate for each group. Then, in section B, the command value derivation unit 50 replaces the first group A with the second group B having a medium degree of degradation and sets the distributed power Pb of the second group B to the same distribution ratio as the distributed power Pa of the first group A. Then, the charge / discharge control unit 60 switches between section A and section B at a predetermined timing. As a result, charging of the third group C having a low degree of degradation continues throughout the entire period, but charging is alternately switched between the first group A having a high degree of degradation and the second group B having a medium degree of degradation. As a result, a charging pause period is provided for the first group A, which has a high degree of deterioration, and the second group B, which has a medium degree of deterioration, so that the progression of deterioration due to polarization of the electrodes that accompanies continued charging can be suppressed, and a longer lifespan can be achieved. Note that the timing for switching between section A and section B is not limited, and may be, for example, when a preset reference duration is reached, or a map that defines the relationship between the integrated value of the charging duration and power and the switching timing may be prepared, and switching between section A and section B may be performed at a timing according to the map.

[0067] Next, the control flow of charging in the battery system 1 in the sixth embodiment will be described in detail. As in the case of the fifth embodiment, first, in step S2 in FIG. 14 of the third embodiment, it is determined that the charge / discharge request is not a discharge request, and then the process proceeds to symbol A, where steps S12 to S150 shown in FIG. 22 are performed.

[0068] 22, the grouping unit 40 sets the number of groups to three or more based on the charge / discharge power requested by the higher-level system 100 and the chargeable power of the secondary batteries 10 determined to be chargeable. In the sixth embodiment, the number of groups is set to three. Then, in step S171, the grouping unit 40 divides the multiple secondary batteries 10 into groups A, B, and C based on the ranking of the capacity maintenance rates. The grouping is performed in order from the smallest capacity maintenance rate so that each group satisfies the system required power.

[0069] Next, in step S181 shown in FIG. 22, the command value derivation unit 50 defines the power distribution for groups A and C. Then, in step S19, the charge / discharge control unit 60 starts discharging groups A and C. After that, the process proceeds to step S191, where the charge / discharge control unit 60 determines whether the timing for switching from section A to section B has arrived. If it is determined in step S191 that the timing for switching has not arrived, the process proceeds to No in step S191 and executes step S191 again. On the other hand, if it is determined in step S191 that the timing for switching has arrived, the process proceeds to Yes in step S191, where in step S192 the charge / discharge control unit 60 switches the discharge targets to groups A and C and continues discharging. After that, the process proceeds to step S10 and subsequent steps in FIG. 14 of the third embodiment described above.

[0070] In the sixth embodiment, the charging groups include a first group A consisting of the secondary batteries having a predetermined capacity retention rate, a second group B consisting of secondary batteries having a capacity retention rate higher than that of the secondary batteries included in the first group A, and a third group C consisting of secondary batteries having a capacity retention rate higher than that of the secondary batteries included in the second group B. The charge / discharge control unit 60 charges the multiple secondary batteries 10 so that Section A, which is a first charging section for charging the secondary batteries included in the first group A and the third group C, and Section B, which is a second charging section for charging the secondary batteries included in the second group B and the third group C, alternate. As described above, this provides a charging pause period for the first group A, which has a high degree of degradation, and the second group B, which has a medium degree of degradation. This suppresses the progression of deterioration due to electrode polarization that occurs with continued charging, thereby extending the battery life. The sixth embodiment can achieve the same effects as the fifth embodiment.

[0071] (Embodiment 7) In the seventh embodiment, in the configuration of the first embodiment shown in FIG. 1 described above, as shown in FIG. 23, the host system 100 has a demand prediction unit 101 and a charge / discharge plan creation unit 102. The demand prediction unit 101 predicts future charge / discharge required for the battery system 1. The charge / discharge plan creation unit 102 creates a charge / discharge plan for the battery system 1 based on the prediction result by the demand prediction unit 101. Then, the host system 100 transmits a charge / discharge request to the battery system 1 based on the charge / discharge plan. The other configurations are the same as those in the first embodiment, and the same reference numerals as those in the first embodiment are used to omit the description thereof.

[0072] In the present embodiment 7, the same effects as those in the embodiment 1 are achieved. Note that the upper system 100 may have a charge / discharge plan storage unit that stores a charge / discharge plan prepared in advance, instead of including the demand prediction unit 101 and the charge / discharge plan creation unit 102, and the upper system 100 may transmit a charge / discharge request to the battery system 1 based on the charge / discharge plan stored in the charge / discharge plan storage unit.

[0073] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention. [Explanation of symbols]

[0074] 1 Battery System 10, 11~17 Secondary battery 20 Battery status acquisition unit 30 Charge / discharge request acquisition section 40 Group Division 50 Command value derivation section 60 Charge / discharge control unit 100 Upper System 101 Demand Forecasting Department 102 Discharge Planning Department

Claims

1. A battery system (1) configured to perform charging and discharging in response to a charging and discharging request from a host system (100), A plurality of secondary batteries (10); a battery status acquisition unit (20) for acquiring the battery status of the secondary battery; a charge / discharge request acquisition unit (30) that acquires the charge / discharge request; a grouping unit (40) that dynamically divides the secondary batteries into a plurality of groups in accordance with the battery states of the secondary batteries acquired by the battery state acquisition unit and the charge / discharge request acquired by the charge / discharge request acquisition unit; a command value derivation unit (60) that derives a charge / discharge command value that defines a distribution power for distributing power according to the charge / discharge request to each of the groups; a charge / discharge control unit (60) that charges / discharges the plurality of secondary batteries based on the charge / discharge command value; the battery state of the secondary battery includes an internal resistance of the secondary battery; the grouping unit divides the secondary batteries into the groups according to the magnitude of the internal resistance of the secondary batteries and the charge / discharge request; the plurality of groups include a first group consisting of the secondary batteries having a predetermined internal resistance, and a second group consisting of the secondary batteries having an internal resistance smaller than the internal resistance of the secondary batteries included in the first group; The command value derivation unit derives the charge / discharge command value so that distributed power distributed to the first group is smaller than distributed power distributed to the second group.

2. A battery system (1) configured to perform charging and discharging in response to a charging and discharging request from a host system (100), A plurality of secondary batteries (10); a battery status acquisition unit (20) for acquiring the battery status of the secondary battery; a charge / discharge request acquisition unit (30) that acquires the charge / discharge request; a grouping unit (40) that dynamically divides the secondary batteries into a plurality of groups in accordance with the battery states of the secondary batteries acquired by the battery state acquisition unit and the charge / discharge request acquired by the charge / discharge request acquisition unit; a command value derivation unit (60) that derives a charge / discharge command value that defines a distribution power for distributing power according to the charge / discharge request to each of the groups; a charge / discharge control unit (60) that charges / discharges the plurality of secondary batteries based on the charge / discharge command value; the battery state of the secondary battery includes a capacity maintenance rate of the secondary battery; the grouping unit divides the secondary batteries into the groups according to the capacity maintenance rates of the secondary batteries and the charge / discharge request; the plurality of groups include a discharging group group, which is the plurality of groups divided by the group dividing unit when discharging is requested as the charge / discharge request, and a charging group group, which is the plurality of groups divided by the group dividing unit when charging is requested as the charge / discharge request, the discharging group group includes a low capacity retention rate group of the discharging group group consisting of the secondary batteries having a low capacity retention rate, and a high capacity retention rate group of the discharging group group consisting of the secondary batteries having a higher capacity retention rate than the low capacity retention rate group of the discharging group group, and the number of the secondary batteries included in the low capacity retention rate group of the discharging group group is smaller than the number of secondary batteries included in the high capacity retention rate group of the discharging group group, the charging group group includes a low capacity retention rate group of the charging group group consisting of the secondary batteries having a low capacity retention rate, and a high capacity retention rate group of the charging group group consisting of the secondary batteries having a higher capacity retention rate than the low capacity retention rate group of the charging group group, and the number of secondary batteries included in the low capacity retention rate group of the charging group group is greater than the number of secondary batteries included in the high capacity retention rate group of the charging group group, the command value derivation unit derives the charge / discharge command value so that the distributed power distributed to the low capacity maintenance ratio group of the discharging group group is greater than the distributed power distributed to the high capacity maintenance ratio group of the discharging group group, and derives the charge / discharge command value so that the distributed power distributed to the low capacity maintenance ratio group of the charging group group is less than the distributed power distributed to the high capacity maintenance ratio group of the charging group group.

3. the battery state acquisition unit acquires a numerical value representing a battery state of the secondary battery; 3. The battery system according to claim 1, wherein the grouping unit compares the value acquired by the battery state acquisition unit with a reference value to divide the plurality of secondary batteries into the groups.

4. 3. The battery system according to claim 1, wherein the grouping unit ranks the secondary batteries based on the battery states, and divides the secondary batteries into the groups based on the ranks.

5. The battery system according to claim 1 or 2, wherein the command value derivation unit determines the distributed power for each of the groups based on a battery state of the secondary battery included in each of the groups.

6. The battery system of claim 2, wherein the low capacity retention rate group of the discharge group group includes a secondary battery with the lowest capacity retention rate, and the high capacity retention rate group of the discharge group group is one or more groups other than the low capacity retention rate group of the discharge group group.

7. The battery system of claim 2, wherein the low capacity retention rate group of the charging group group includes a secondary battery with the lowest capacity retention rate, and the high capacity retention rate group of the charging group group is one or more groups other than the low capacity retention rate group of the charging group group.

8. the low capacity retention rate group of the discharging group includes a secondary battery with the lowest capacity retention rate, and the high capacity retention rate group of the discharging group is made up of secondary batteries having a capacity retention rate higher than that of the secondary batteries included in the low capacity retention rate group of the discharging group, 3. The battery system of claim 2, wherein a first distributed power distributed to the low capacity retention rate group of the discharge group group is equal to or greater than a second distributed power distributed to the high capacity retention rate group of the discharge group group.

9. the low capacity retention rate group of the charging group includes a secondary battery with the lowest capacity retention rate, and the high capacity retention rate group of the charging group is made up of secondary batteries having a capacity retention rate higher than that of the secondary batteries included in the low capacity retention rate group of the charging group, The battery system of claim 2, wherein the first distributed power distributed to the low capacity retention rate group of the charging group group is a value within a range that does not promote deterioration of the secondary batteries distributed to the low capacity retention rate group of the charging group group.

10. the high capacity retention ratio group of the charging group group includes a first high capacity retention ratio group consisting of secondary batteries having a capacity retention ratio higher than that of the secondary batteries included in the low capacity retention ratio group of the charging group group, and a second high capacity retention ratio group consisting of secondary batteries having a capacity retention ratio higher than that of the secondary batteries included in the first high capacity retention ratio group, 3. The battery system according to claim 2, wherein the charge / discharge control unit charges the plurality of secondary batteries such that a first charging interval in which the secondary batteries included in the low capacity retention ratio group and the second high capacity retention ratio group are charged and a second charging interval in which the secondary batteries included in the low capacity retention ratio group and the first high capacity retention ratio group are charged alternately.

11. The battery system according to any one of claims 1 to 10, wherein the charge / discharge request includes a demand forecast for the battery system prepared in advance or a charge / discharge plan for the battery system created in advance.

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