Battery system and method for controlling charge and discharge of battery system

Abstract

To provide a battery system capable of suppressing increase of a load applied to a constraint jig, and to provide a charging / discharging control method of the battery system.SOLUTION: A battery system 100 according to the present disclosure comprises a plurality of battery units 10 - N connected in parallel to a common power system 1, and a control part 6. The battery units 10 - N comprise relays 2 - N, current sensors 4 - N, and battery packs 5 - N, respectively. The relays 2 - N and the current sensors 4 - N are arranged between the battery packs 5 - N and the power system. The control part 6 determines whether or not a total discharge integration amount of the respective battery units 10 - N calculated by using current values measured by the current sensors 4 - N of the respective battery units 10 - N is a predetermined value EN or more. The control part 6 prohibits charging / discharging of the battery packs 5 - N of the respectively determined batter units 10 - N by closing the relays 2 - N of the determined battery units 10 - N each whose total discharge integration amount is determined to be the predetermined value EN or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a battery system and a method for controlling charging and discharging of the battery system. [Background technology]

[0002] Patent Document 1 discloses a power storage system including a plurality of battery units connected in parallel to a common power grid and a power regulator. Specifically, an inverter and a sensor unit are connected to the battery units. The inverter is disposed between the battery units and the power grid. The sensor unit has a function of detecting the state of the battery units and sending a signal related to the detected state of the battery units to the power regulator. The power regulator controls the charging and discharging of each battery unit so as to reduce the difference in the deterioration state between the battery units. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-115968 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have discovered the following technical problems. In such a power storage system, each of the battery units may be restrained by a restraining jig. Furthermore, some of the battery units may be deteriorated due to their temperature being higher than the temperature that is desirable for charging and discharging. In such a case, the power regulator reduces the amount of current flowing through some of the battery units while increasing the amount of current flowing through the remaining battery units with lower temperatures in order to suppress the deterioration. As a result, the load is concentrated on the battery units with lower temperatures. This causes the batteries in the battery units to expand, increasing the load on the restraining jig.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and provides a battery system that can suppress an increase in the load on a restraint jig, and a method for controlling charging and discharging of the battery system. [Means for solving the problem]

[0006] The battery system according to the present disclosure comprises: A battery system including a plurality of battery units connected in parallel to a common power system and a control unit, Each battery unit includes a relay, a current sensor, and a battery pack. the relay and the current sensor are disposed between the battery pack and the power grid; the battery pack is restrained by a restraining jig; the control unit determines whether a total accumulated discharge amount of each of the battery units calculated using a current value measured by the current sensor of each of the battery units is equal to or greater than a predetermined value; The control unit closes a relay of a battery unit determined to have a total accumulated discharge amount equal to or greater than a predetermined value, thereby prohibiting charging and discharging of the battery pack of the determined battery unit.

[0007] In the above-described battery system, the predetermined value may be determined using a load value required for the restraining jig to break.

[0008] The charge / discharge control method for a battery system according to the present disclosure includes: A charge / discharge control method for a battery system including a plurality of battery units connected in parallel to a common power system and a control unit, comprising: Each battery unit includes a relay, a current sensor, and a battery pack. the relay and the current sensor are disposed between the battery pack and the power grid; the battery pack is restrained by a restraining jig; determining whether or not a total accumulated discharge amount of each of the battery units calculated using the current values ​​measured by the current sensors of each of the battery units is equal to or greater than a predetermined value; and closing a relay of a battery unit determined to have the total accumulated discharge amount equal to or greater than a predetermined value, thereby prohibiting charging and discharging of the battery pack of the determined battery unit.

[0009] With this configuration, charging and discharging of a specific battery unit whose total accumulated discharge amount is equal to or greater than a predetermined value is stopped, thereby suppressing expansion of the specific battery unit and suppressing an increase in the load on the restraining jig. [Effects of the Invention]

[0010] According to the present disclosure, an increase in the load applied to the restraining jig can be suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing an example of the configuration of a battery system according to a first embodiment. [Figure 2] 1 is a schematic diagram showing a side view of an example of a battery pack according to a first embodiment. [Figure 3] 10 is a graph showing a restraint load relative to a total discharge integrated amount. [Figure 4] 3 is a flowchart showing a charge / discharge control method according to the first embodiment. [Figure 5] 4 is a timing chart showing an example of the operation of the battery system according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0013] <First Embodiment> A first embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a block diagram showing an example of the configuration of a battery system according to the first embodiment. Fig. 2 is a schematic diagram showing a side view of an example of a battery pack of the battery system shown in Fig. 1. Fig. 3 is a graph showing the constraint load relative to the total accumulated discharge amount.

[0014] Naturally, the right-handed XYZ coordinate system shown in Figure 2 is a convenient way to explain the positional relationships of the components. Normally, the positive Z axis is vertically upward, and the XY plane is a horizontal plane, which is common among all drawings.

[0015] 1, battery system 100 includes battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N and a control unit 6. Battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N may all have the same configuration, where N is a natural number of 2 or greater.

[0016] The battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N are connected in parallel to a common power system 1. The power system 1 is connected to a power generation device and a load (not shown). The power system 1 is preferably an AC power system.

[0017] The battery unit 10-1 includes a relay 2-1, a current sensor 4-1, and a battery pack 5-1. Similarly, the battery unit 10-N includes a relay 2-N, a current sensor 4-N, and a battery pack 5-N. The relay 2-1 and the current sensor 4-1 are disposed between the battery pack 5-1 and the power grid 1. Similarly, the relay 2-N and the current sensor 4-N are disposed between the battery pack 5-N and the power grid 1.

[0018] Relays 2-1, 2-2, 2-3, 2-4, ..., 2-N are connected to the control unit 6 so as to be able to receive signals from the control unit 6. Relays 2-1, 2-2, 2-3, 2-4, ..., 2-N perform opening and closing operations in response to the signals received from the control unit 6. By performing this opening and closing operation, relay 2-1 electrically connects and disconnects the battery pack 5-1 to and from the power system 1. Similarly, relay 2-N also performs this opening and closing operation to electrically connect and disconnect the battery pack 5-N to and from the power system 1.

[0019] The current sensor 4-1 measures the current flowing between the battery pack 5-1 and the power grid 1 and generates a current value. Similarly, the current sensor 4-N measures the current flowing between the battery pack 5-N and the power grid 1 and generates a current value.

[0020] The battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N may each include a boost converter 3-1, 3-2, 3-3, 3-4, ..., 3-N.

[0021] The boost converter 3-1 is arranged between the battery pack 5-1 and the power system 1. Specifically, the current sensor 4-1, the boost converter 3-1, and the relay 2-1 are arranged in this order between the battery pack 5-1 and the power system 1. The boost converter 3-1 appropriately boosts the current flowing between the battery pack 5-1 and the power system 1. This prevents current from circulating between the battery pack 5-1 and the power system 1. Similarly, the boost converter 3-N is arranged between the battery pack 5-N and the power system 1. Specifically, the current sensor 4-N, the boost converter 3-N, and the relay 2-N are arranged in this order between the battery pack 5-N and the power system 1. The boost converter 3-N appropriately boosts the current flowing between the battery pack 5-N and the power system 1. This prevents current from circulating between the battery pack 5-N and the power system 1.

[0022] The battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N may include, for example, at least one battery module and may appropriately include a protection circuit, a cooling mechanism, etc. The battery module may include, for example, a lithium ion secondary battery, an all-solid-state battery, etc.

[0023] The battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N are restrained by restraining jigs 7-1, 7-2, 7-3, 7-4, ..., 7-N (not shown), respectively. The restraining jigs 7-1, 7-2, 7-3, 7-4, ..., 7-N may have the same configuration. Specifically, as shown in FIG. 2, the battery pack 5-N is restrained by the restraining jig 7-N. The restraining jig 7-N includes restraining members 7a-N, 7b-N and fastening portions 7c-N, 7d-N. The restraining members 7a-N, 7b-N may be any member capable of restraining the battery pack 5-N, such as a pair of plate-like bodies. The pair of plate-like bodies may have a predetermined rigidity. The fastening portions 7c-N, 7d-N may be any member capable of fastening the restraining members 7a-N, 7b-N, such as a bolt and nut. While the restraining members 7a-N and 7b-N sandwich the battery pack 5-N, the fastening portions 7c-N and 7d-N fasten the restraining members 7a-N and 7b-N together. The battery pack 5-N receives a restraining load from the restraining members 7a-N and 7b-N.

[0024] The control unit 6 is connected to each of the current sensors 4-1, 4-2, 4-3, 4-4, ..., 4-N so as to be able to acquire signals from each of the current sensors 4-1, 4-2, 4-3, 4-4, ..., 4-N. The control unit 6 acquires the current values ​​measured by each of the current sensors 4-1, 4-2, 4-3, 4-4, ..., 4-N from the current sensors 4-1, 4-2, 4-3, 4-4, ..., 4-N.

[0025] The control unit 6 calculates the total accumulated discharge amount of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N using the current values ​​acquired from the current sensors 4-1, 4-2, 4-3, 4-4, ..., 4-N. The total accumulated discharge amount may be obtained, for example, by integrating the current values ​​during discharge from the start to the end of discharge. The control unit 6 determines whether the calculated total accumulated discharge amount is equal to or greater than a predetermined value. The predetermined value may be determined using the load value required to break the restraining jigs 7-1, 7-2, 7-3, 7-4, ..., 7-N.

[0026] The load curve CN shown in FIG. 3 indicates the load applied to the restraining jig 7-N when the accumulated total discharge amount of the battery pack 5-N is changed within a predetermined range. As shown in FIG. 3, the load applied to the restraining jig 7-N is proportional to the accumulated total discharge amount of the battery pack 5-N. When the accumulated total discharge amount of the battery pack 5-N reaches EN, the load applied to the restraining jig 7-N reaches LN, and the restraining jig 7-N breaks. In other words, the load value required to break the restraining jig 7-N is LN. Therefore, EN can be determined as the predetermined value of the accumulated total discharge amount of the current sensor 4-N. If the restraining jigs 7-1, 7-2, 7-3, 7-4, ..., 7-N all have the same configuration, EN can also be determined as the predetermined value of the accumulated total discharge amount of the battery pack 5-N.

[0027] The control unit 6 controls the opening and closing of relays 2-1, 2-2, 2-3, 2-4, ..., 2-N. Specifically, the control unit 6 closes the relay of a battery unit whose total accumulated discharge amount is determined to be equal to or greater than a predetermined value EN, thereby prohibiting charging and discharging of the battery pack of the battery unit. For example, if it is determined that the total accumulated discharge amount of battery unit 10-K is equal to or greater than a predetermined value, the control unit 6 closes relay 2-K of battery unit 10-K, thereby prohibiting charging and discharging of battery pack 5-K of battery unit 10-K. Here, K is at least one natural number selectable from the range of 1 to N.

[0028] In detail, when the control unit 6 determines that the calculated total accumulated discharge amount is equal to or greater than a predetermined value, the control unit 6 may turn on an abnormality occurrence flag. If the abnormality occurrence flag is on, it is assumed that an abnormality has occurred in the battery pack. The control unit 6 may increment an abnormality counter depending on the length of time or number of times that the abnormality occurrence flag is in the on state. If the abnormality counter reaches a threshold value Tr, the control unit 6 may turn on the abnormality determination. If the abnormality determination is on, it is determined that an abnormality has definitely occurred in the battery pack. If the control unit 6 turns on the abnormality determination, it may turn off the relay. The relay being in the off state means that the relay is closed. By having such a configuration, the control unit 6 may be able to prevent erroneous determination that the calculated total accumulated discharge amount is equal to or greater than a predetermined value.

[0029] The battery system 100 may also include a power regulator. The power regulator reduces the amount of current flowing through some of the battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N that have a temperature higher than the preferred temperature for charging and discharging. Simultaneously with this reduction, the power regulator increases the amount of current flowing through the remaining battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N that have a temperature lower than the preferred temperature for charging and discharging. This prevents some of the battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N from deteriorating due to their temperatures being higher than the preferred temperature for charging and discharging.

[0030] <Charge / discharge control method> Next, an example of a charge / discharge control method for the battery system 100 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the charge / discharge control method according to the first embodiment.

[0031] The control unit 6 calculates the total accumulated discharge amount of the battery packs 5-1, 5-2, 5-3, 5-4, . . . , 5-N (step ST1).

[0032] Next, the control unit 6 determines whether or not the total accumulated discharge amount of the battery packs 5-1, 5-2, 5-3, 5-4, . . . , 5-N is equal to or greater than a predetermined value EN (step ST2).

[0033] The control unit 6 determines that the total accumulated discharge amounts of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N are all less than the predetermined value EN (step ST2: NO), and then repeats steps ST1 and ST2.

[0034] On the other hand, the control unit 6 determines that the total accumulated discharge amount of at least one of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N is equal to or greater than the predetermined value EN (step ST2: YES). Then, the control unit 6 prohibits charging or discharging of at least one of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N whose total accumulated discharge amount is determined to be equal to or greater than the predetermined value EN (step ST3). Specifically, for example, when the control unit 6 determines that the total accumulated discharge amount of the battery pack 5-N is equal to or greater than the predetermined value EN, the control unit 6 closes the relay 2-N of the battery pack 5-N. This prohibits charging or discharging of the battery pack 5-N.

[0035] As described above, with the above configuration, charging / discharging of at least one of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N whose total accumulated discharge amount is equal to or greater than a predetermined value is stopped, thereby suppressing expansion of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N and suppressing an increase in the load applied to the restraining jigs 7-1, 7-2, 7-3, 7-4, ..., 7-N.

[0036] The battery system 100 is also preferably equipped with the power regulator. The power regulator increases the amount of current supplied to the remaining battery units 10-1, 10-2, 10-3, 10-4, ..., 10-N whose temperatures are lower than the temperature that is preferable for charging and discharging. If discharging continues, the total accumulated discharge amount of the battery units with increased current reaches a predetermined value. Therefore, charging and discharging of the battery packs of the battery units with increased current is stopped. In other words, the concentration of load on the battery units is suppressed. This suppresses the increase in load on the restraining jigs 7-1, 7-2, 7-3, 7-4, ..., 7-N due to the expansion of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N of the battery units.

[0037] Furthermore, the operation of the battery system 100 in an example of the charge / discharge control method for the battery system 100 according to the first embodiment will be described with reference to Fig. 5. Fig. 5 is a timing chart showing an example of the operation of the battery system according to the first embodiment. The horizontal axis of Fig. 5 represents time, and the vertical axis of Fig. 3 represents the determination of the total discharge accumulated amount, the state of the abnormality occurrence flag, the state of the counter, the abnormality determination, and the operation of the relay.

[0038] 5, at time t0 when charging / discharging of the battery system 100 starts, if it is determined that the total accumulated discharge amount of the battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N is less than the predetermined value EN (step ST2: NO), the total accumulated discharge amount determination is in the OFF state, and the relay 2-N is in the OFF state.

[0039] A predetermined time has passed since time t0, and time t1 is reached. At time t1, it is determined that the total accumulated discharge amount of at least one of battery packs 5-1, 5-2, 5-3, 5-4, ..., 5-N is equal to or greater than a predetermined value EN (step ST2: YES). For example, it is determined that the total accumulated discharge amount of battery pack 5-N is equal to or greater than the predetermined value EN. The determination of the total accumulated discharge amount of battery pack 5-N is in the ON state.

[0040] After that, at time t2, the abnormality occurrence flag is changed from the OFF state to the ON state, and the abnormality counter starts to be incremented.

[0041] After that, at time t3, the abnormality counter reaches the threshold value Tr. Furthermore, the abnormality determination is turned on, and it is determined that an abnormality has definitely occurred in the battery pack.

[0042] After that, at time t4, the relay 2-N is changed from the ON state to the OFF state. The relay 2-N closes, and the electrical connection between the battery pack 5-N and the power grid 1 is cut off. Note that the relay 2-N is a system main relay (SMR), and the OFF state of the relay 2-N may be the OFF state of the system main relay (SMR-OFF).

[0043] Each component in the above-described embodiments may be configured by hardware or software, or both, and may be configured by a single piece of hardware or software, or may be configured by multiple pieces of hardware or software. The function (processing) of each device may be realized by a computer having a CPU (Central Processing Unit), memory, etc. For example, a program for performing a method (e.g., a control method) in the embodiment may be stored in a storage device, and each function may be realized by executing the program stored in the storage device with the CPU.

[0044] These programs can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory)). The programs may also be supplied to a computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable media can supply the programs to a computer via wired communication paths such as electric wires and optical fibers, or via wireless communication paths.

[0045] The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the spirit and scope of the present invention. Furthermore, the present invention may be implemented by appropriately combining the above-described embodiment and examples thereof. [Explanation of symbols]

[0046] 100 Battery System 10-1, 10-2, 10-3, 10-4, 10-N Battery Unit 1 Power system 2-1, 2-2, 2-3, 2-4, 2-N relays 3-1, 3-2, 3-3, 3-4, 3-N Boost Converters 4-1, 4-2, 4-3, 4-4, 4-N Current Sensors 5-1, 5-2, 5-3, 5-4, 5-N Battery Pack 6 Control Unit 7-N restraint jig 7a-N, 7b-N Restraint members 7c-N, 7d-N fastening section LN load value EN (Total discharge accumulated amount) specified value CN load curve Time points t0, t1, t2, t3, and t4

Claims

1. A battery system including a plurality of battery units connected in parallel to a common power system and a control unit, Each battery unit includes a relay, a current sensor, and a battery pack. the relay and the current sensor are disposed between the battery pack and the power grid; the battery pack is restrained by a restraining jig; the control unit determines whether a total accumulated discharge amount of each of the battery units calculated using a current value measured by the current sensor of each of the battery units is equal to or greater than a predetermined value; the control unit closes a relay of a battery unit determined to have a total accumulated discharge amount equal to or greater than a predetermined value, thereby prohibiting charging and discharging of the battery pack of the determined battery unit; The predetermined value is determined using a load value required for the restraint jig to break. Battery system.

2. A charge / discharge control method for a battery system including a plurality of battery units connected in parallel to a common power system and a control unit, comprising: Each battery unit includes a relay, a current sensor, and a battery pack. the relay and the current sensor are disposed between the battery pack and the power grid; the battery pack is restrained by a restraining jig; determining whether or not a total accumulated discharge amount of each of the battery units calculated using the current values ​​measured by the current sensors of each of the battery units is equal to or greater than a predetermined value; and closing a relay of a battery unit determined to have a total accumulated discharge amount equal to or greater than a predetermined value, thereby prohibiting charging and discharging of the battery pack of the determined battery unit, The predetermined value is determined using a load value required for the restraint jig to break. A method for controlling charging and discharging of a battery system.

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