Power storage device and power storage system

Abstract

To provide a power storage system that allows hot-swap of a power storage module.SOLUTION: A power storage module 2010 includes a power storage unit that can be connected in parallel to another power supply device, and a switching unit disposed between a wiring that electrically connects the power storage module and the other power supply device. The switching unit switches the electrical connection between the wiring and the power storage unit depending on whether the voltage between the terminals of the switching unit satisfies a predetermined condition. The power storage module also includes a suppressing unit that includes a capacitive element that is connected in parallel to the switching unit between the wiring and the power storage unit.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to a power storage device and a power storage system.

Background Art

[0002] In a power storage system including a plurality of power storage modules, the power storage modules may be connected in parallel (see, for example, Patent Document 1). Patent Document 2 discloses a power storage system capable of actively inserting and removing a power storage module. (Prior Art Documents) (Patent Documents) (Patent Document 1) Japanese Patent Application Laid-Open No. 11-98708 (Patent Document 2) International Publication No. 2017 / 086349

Summary of the Invention

Means for Solving the Problems

[0003] In a first aspect of the present invention, a power storage device is provided. The power storage device includes a power storage unit of a power storage device configured to be connectable in parallel with another power supply device, and a switching unit disposed between the power storage device and a wiring for electrically connecting the other power supply device. The switching unit switches an electrical connection relationship between the wiring and the power storage unit according to whether a voltage between terminals of the switching unit satisfies a predetermined condition. The power storage device includes a capacitive element connected in parallel with the switching unit between the wiring and the power storage unit.

[0004] The power storage device may further include a current amount limiting unit connected in series with the capacitive element and configured to limit an amount of current flowing through the capacitive element.

[0005] In any of the above power storage devices, the current amount limiting unit may have a resistance.

[0006] Any of the above power storage devices may further include a resistance connected in series with the capacitive element.

[0007] In any of the above-described power storage devices, the switching unit may include a relay disposed between the wiring and the power storage unit. A value obtained by multiplying the resistance value of the resistor by the rated current value of the power storage unit may be less than the minimum arc voltage value of the relay.

[0008] Any of the above-described power storage devices may further include a switching control unit that controls whether the switching unit electrically connects or disconnects the wiring and the power storage unit according to whether the voltage between the terminals of the switching unit satisfies a predetermined condition.

[0009] In any of the above-described power storage devices, the switching control unit may control the switching unit such that (i) when the voltage between the terminals of the switching unit satisfies a predetermined condition, the switching unit electrically connects the wiring and the power storage unit, and (ii) when the voltage between the terminals of the switching unit does not satisfy the predetermined condition, the switching unit electrically disconnects the wiring and the power storage unit.

[0010] In any of the above-described power storage devices, the capacitive element may suppress a back electromotive force generated in the wiring when the switching unit electrically disconnects the wiring and the power storage unit while the capacitive element is storing electrical energy in the power storage unit.

[0011] In any of the above-described power storage devices, the switching unit may include a relay disposed between the wiring and the power storage unit.

[0012] In any of the above-described power storage devices, the capacitance of the capacitive element may be greater than 0.1 μF.

[0013] In the second aspect of the present invention, a power storage system is provided. In the above-described power storage system, a plurality of power storage devices are connected in parallel.

[0014] Note that the above summary of the invention does not list all of the necessary features of the present invention. Also, sub-combinations of these feature groups may also be inventions.

Brief Description of the Drawings

[0015]

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Best Mode for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. Not all combinations of features described in the embodiments are essential for the solution of the invention. Also, the embodiments will be described with reference to the drawings. In the description of the drawings, the same or similar parts may be given the same reference numerals and redundant descriptions may be omitted.

[0017] FIG. 1 schematically shows an example of the system configuration of the power storage system 100. In one embodiment, the power storage system 100 is electrically connected to the load device 12 and supplies power to the load device 12 (which may be referred to as discharging of the power storage system 100). In other embodiments, the power storage system 100 is electrically connected to the charging device 14 and stores electrical energy (which may be referred to as charging of the power storage system). The power storage system 100 is used, for example, in power storage devices, electrical equipment, transportation devices, etc. Examples of transportation devices include electric vehicles, hybrid vehicles, electric motorcycles, railway vehicles, airplanes, elevators, cranes, etc.

[0018] In the present embodiment, the power storage system 100 includes a connection terminal 102, a connection terminal 104, a wiring 106 that electrically connects the connection terminal 102 and the connection terminal 104, a power storage module 110 having a positive electrode terminal 112 and a negative electrode terminal 114, a power storage module 120 having a positive electrode terminal 122 and a negative electrode terminal 124, and a system control unit 140. The power storage module 110 and the power storage module 120 may be an example of a power storage device configured to be connectable in parallel. For example, the power storage module 110 may be an example of a power storage device, and the power storage module 120 may be an example of another power storage device. The power storage device may be an example of a power supply device. The system control unit 140 may be an example of a battery characteristic acquisition unit. The system control unit 140 may be an example of an output unit.

[0019] The power storage system 100 is electrically connected to the load device 12 or the charging device 14 via the connection terminal 102 and the connection terminal 104. In the present embodiment, the power storage module 110 and the power storage module 120 are connected in parallel using the wiring 106. Further, each of the power storage module 110 and the power storage module 120 is detachably held in the housing of the power storage system 100. Thereby, each of the power storage module 110 and the power storage module 120 can be individually replaced.

[0020] In the present embodiment, each of the power storage module 110 and the power storage module 120 can switch the connection relationship between the power storage unit of each power storage module and the wiring 106 based on a control signal from the system control unit 140 or a user operation. For example, each of the power storage module 110 and the power storage module 120 can electrically connect the power storage unit of each power storage module to the wiring 106 or electrically disconnect the power storage unit of each power storage module from the wiring 106 based on a control signal from the system control unit 140 or a user operation.

[0021] Thereby, even when the voltage of the power storage module newly mounted in the power storage system 100 is different from the voltage of the power storage module already mounted in the power storage system 100, each of the plurality of power storage modules included in the power storage system 100 can be individually replaced without worrying about damage or deterioration of the power storage module. The reason is as follows, for example.

[0022] Due to the recent improvement in the performance of lithium-ion batteries, the impedance of lithium-ion batteries has been reduced to about 10 mΩ. Therefore, for example, even when the voltage difference between two power storage modules is only 0.4 V, when the two power storage modules are connected in parallel, a large current of 40 A flows from the power storage module with a higher voltage to the power storage module with a lower voltage. As a result, the power storage module deteriorates or is damaged. Note that the voltage of the power storage module may be the voltage between the positive terminal and the negative terminal of the power storage module (sometimes referred to as the inter-terminal voltage of the power storage module).

[0023] For the purpose of preventing the deterioration or damage of the power storage module during the replacement operation of the power storage module, when individually replacing one of the plurality of power storage modules connected in parallel, before performing the replacement operation of the power storage module, it is conceivable to adjust the voltages of the newly installed power storage module and the already installed power storage module over time until the voltage difference between them becomes extremely small. By making the voltage difference between the newly installed power storage module and the already installed power storage module extremely small, it is possible to prevent a large current from flowing through each power storage module during the replacement of the power storage module. As a result, deterioration or damage of the power storage module can be suppressed. However, as the impedance of the lithium-ion battery decreases, the allowable value of the voltage difference between the newly installed power storage module and the already installed power storage module also decreases, and the time required to adjust the voltage difference may become extremely long.

[0024] On the other hand, according to the power storage system 100 according to the present embodiment, each of the power storage module 110 and the power storage module 120 can switch the connection relationship between the power storage unit of each power storage module and the wiring 106 based on a control signal from the system control unit 140 or an operation of the user. And, for example, the power storage module 110 can be replaced by the following procedure.

[0025] First, the user removes the old power storage module 110 from the power storage system 100. Next, before the user installs the new power storage module 110 into the power storage system 100, the user performs an operation to electrically disconnect the power storage unit of the new power storage module 110 from the wiring 106. For example, the user manually operates a switching element disposed between the positive electrode terminal 112 of the power storage module 110 and the power storage unit to electrically disconnect the positive electrode terminal 112 from the power storage unit.

[0026] After that, the user installs the power storage module 110 in a state where the positive electrode terminal 112 and the power storage unit are electrically disconnected into the power storage system 100. At this time, since the positive electrode terminal 112 and the power storage unit are electrically disconnected, even if the voltage difference between the power storage module 110 and the power storage module 120 is relatively large, no current flows between the power storage module 110 and the power storage module 120. After that, when the voltage difference between the power storage module 110 and the power storage module 120 reaches an appropriate value, the system control unit 140 executes an operation to electrically connect the power storage module 110 and the wiring 106. Details of the system control unit 140 will be described later.

[0027] As described above, according to the power storage system 100 according to the present embodiment, when replacing or installing a power storage module, it is not necessary to precisely adjust the voltage of the power storage module newly installed in the power storage system 100 and the voltage of the power storage module already installed in the power storage system 100. Therefore, the power storage module can be easily and quickly replaced or installed.

[0028] The system control unit 140 controls each part of the power storage system 100. In one embodiment, the system control unit 140 determines the state of the power storage system 100. Examples of the state of the power storage system 100 include a charging state, a discharging state, a standby state, or a stopped state.

[0029] For example, the system control unit 140 receives information regarding charge / discharge events and determines the state of the power storage system 100 based on the information regarding charge / discharge events. Examples of the information regarding charge / discharge events include: (i) a charge request or a discharge request from external devices such as the load device 12 and the charging device 14; (ii) information indicating that an external device is connected; (iii) information indicating the type of the external device; (iv) information indicating the operation of the external device; (v) information indicating the state of the external device; (vi) information indicating a user instruction or operation for the external device; (vii) information indicating a user instruction or operation for the power storage system 100; and (viii) combinations thereof, etc.

[0030] For example, when the system control unit 140 detects the connection of the load device 12 or receives a signal indicating the type of the load device 12, it determines that the power storage system 100 is in a discharge state. When the system control unit 140 receives a signal indicating that power is to be used from the load device 12, it may also determine that the power storage system 100 is in a discharge state. Examples of the signal indicating that power is to be used include a signal indicating that the power supply of the load device 12 is turned on, a signal indicating that the power supply of the load device 12 has been turned on, a signal indicating that the load device 12 is shifted to an operation mode, a signal indicating that the load device 12 has been shifted to the operation mode, etc.

[0031] When the system control unit 140 detects the connection of the charging device 14 or receives a signal indicating the type of the charging device 14, it may determine that the power storage system 100 is in a charging state. When the system control unit 140 receives a signal indicating the start of charging from the charging device 14, it may also determine that the power storage system 100 is in a charging state. When the system control unit 140 receives a signal indicating that a regenerative current is generated or may be generated from the load device 12, it may also determine that the power storage system 100 is in a charging state.

[0032] In other embodiments, the system control unit 140 monitors the states of the power storage module 110 and the power storage module 120. The system control unit 140 may collect information regarding the battery characteristics of the power storage units included in each of the power storage module 110 and the power storage module 120. The information regarding the battery characteristics of the power storage unit may be at least one selected from the voltage value of the power storage unit, the current value flowing through the power storage unit, the battery capacity of the power storage unit, the temperature of the power storage unit, the deterioration state of the power storage unit, and the SOC (State Of Charge) of the power storage unit.

[0033] The information regarding the battery characteristics of the power storage unit (which may be referred to as the battery characteristics of the power storage module. The battery characteristics of the power storage unit may be the battery characteristics of a single unit cell among the plurality of unit cells constituting the power storage module, or may be the battery characteristics of a combination of the plurality of unit cells.) may include at least one of information regarding the specifications of the power storage unit and information regarding the deterioration state of the power storage unit. Examples of the information regarding the specifications of the power storage unit include information regarding the type or model of the power storage unit, the connection state of the power storage unit, the type of charging method by which the power storage unit can be charged, the type of charging method by which the power storage unit cannot be charged, the rated battery capacity (which may be referred to as the rated capacity), the rated voltage, the rated current, the energy density, the maximum charge and discharge current, the charging characteristics, the charging temperature characteristics, the discharge characteristics, the discharge temperature characteristics, the self-discharge characteristics, the charge and discharge cycle characteristics, the equivalent series resistance in the initial state, the battery capacity in the initial state, the SOC [%] in the initial state, the storage voltage [V], etc. Examples of the charging method include the CCCV method, the CC method, the trickle charging method, etc.

[0034] Examples of the connection state of the power storage unit include the type of unit cell constituting the power storage unit, the number of the unit cells, the connection form of the unit cells, etc. Examples of the connection form of the unit cells include the number of unit cells connected in series, the number of unit cells connected in parallel, etc. The energy density may be the volume energy density [Wh / m 3 , or may be the weight energy density [Wh / kg].

[0035] Examples of information regarding the degradation state of the power storage unit include information on the power storage unit at an arbitrary point in time, such as (i) the battery capacity in a fully charged state, (ii) the SOC under predetermined temperature conditions, (iii) SOH (State Of Health), (iv) equivalent series resistance (which may also be referred to as DCR or internal resistance), (v) the usage time, number of charge cycles, charge amount, discharge amount, number of charge-discharge cycles, temperature stress factor, and overcurrent stress factor integrated from the initial state or predetermined timings, etc. Information regarding the battery characteristics of the power storage unit may be stored by associating information regarding the degradation state of the power storage unit with information regarding the time at which the information was acquired. Information regarding the battery characteristics of the power storage unit may store information regarding the degradation state of the power storage unit at multiple times.

[0036] SOH [%] is expressed, for example, as (e.g., the current fully charged capacity) [Ah] ÷ initial fully charged capacity [Ah] × 100 of the fully charged capacity at the time of degradation. The calculation method or estimation method of SOH is not particularly limited. For example, the SOH of the power storage unit is calculated or estimated based on at least one of the DC resistance value and open circuit voltage value of the power storage unit. SOH may be a value converted to a value under predetermined temperature conditions using an arbitrary conversion formula or the like.

[0037] The method for determining the degradation state of the power storage unit is not particularly limited, and a currently known or future-developed determination method can be used. Generally, as the degradation of the power storage unit progresses, the available battery capacity decreases and the equivalent series resistance increases. Therefore, for example, the degradation state of the battery can be determined by comparing the current battery capacity, SOC, or equivalent series resistance with the battery capacity, SOC, or equivalent series resistance in the initial state.

[0038] The SOC [%] is represented, for example, as the remaining capacity [Ah] ÷ the full charge capacity [Ah] × 100. The method for calculating or estimating the SOC is not particularly limited, but the SOC is calculated or estimated based on, for example, at least one of (i) the measurement result of the voltage of the power storage unit, (ii) the I-V characteristic data of the voltage of the power storage unit, and (iii) the integrated value of the current value of the power storage unit. The SOC may be a value converted to a value under predetermined temperature conditions using any conversion formula or the like.

[0039] The information regarding the battery characteristics of the power storage unit may be information regarding at least one of the charging time and the discharging time of the power storage unit. The charging time and the discharging time of the power storage unit may be the charging time and the discharging time of the power storage module including the power storage unit, respectively. Generally, as the deterioration of the power storage unit progresses, the available battery capacity decreases, and at least one of the charging time and the discharging time becomes shorter.

[0040] The information regarding the charging time of the power storage unit may include information indicating the ratio of the charging time of the power storage unit to the charging time of the power storage system 100. The information regarding the charging time of the power storage unit may include information indicating the charging time of the power storage system 100 and information indicating the charging time of the power storage unit. The above charging time may be (i) the time when current or voltage is applied to the power storage system 100 or the power storage unit in one charging operation, or (ii) the sum of the times when current or voltage is applied to the power storage system 100 or the power storage unit in one or more charging operations in a predetermined period.

[0041] The information regarding the charging time of the power storage unit may include information indicating the ratio of the number of charging times of the power storage unit in a predetermined period to the number of charging times of the power storage system 100 in the same period. The information regarding the charging time of the power storage unit may include information indicating the number of charging times of the power storage system 100 in a predetermined period and information indicating the number of charging times of the power storage unit in the same period.

[0042] The information regarding the discharge time of the power storage unit may include information indicating the ratio of the discharge time of the power storage unit to the discharge time of the power storage system 100. The information regarding the discharge time of the power storage unit may include the discharge time of the power storage system 100 and the discharge time of the power storage unit. The above-mentioned discharge time may be (i) the time during which the power storage system 100 or the power storage unit supplies current or voltage in a single discharge operation, or (ii) the sum of the times during which the power storage system 100 or the power storage unit supplies current or voltage in one or more discharge operations within a predetermined period.

[0043] The information regarding the discharge time of the power storage unit may include information indicating the ratio of the number of discharge times of the power storage unit during a predetermined period to the number of discharge times of the power storage system 100 during the same period. The information regarding the discharge time of the power storage unit may include the number of discharge times of the power storage system 100 and the number of discharge times of the power storage unit during a predetermined period.

[0044] The system control unit 140 may transmit at least one of the information regarding the battery characteristics of the power storage unit included in the power storage module 110 and the information regarding the battery characteristics of the power storage unit included in the power storage module 120 to an external device. Thereby, the external device can utilize the information regarding the battery characteristics of the power storage unit. Examples of the external device may include the load device 12, the charging device 14, etc. The external device may be an output device that outputs information to the user. Examples of the output device may include a display device such as a display, or an audio output device such as a microphone. The output device may be an example of the output unit.

[0045] The system control unit 140 may determine the performance of the power storage module based on the information regarding the battery characteristics of the power storage module. When the battery characteristics of the power storage module do not satisfy a predetermined determination condition, the system control unit 140 may output information indicating that the performance of the power storage module is insufficient. The system control unit 140 may determine the determination condition based on the application of the power storage system 100.

[0046] In this embodiment, a case has been described where the system control unit 140 collects at least one of information on the battery characteristics of the power storage unit included in the power storage module 110 and information on the battery characteristics of the power storage unit included in the power storage module 120, and transmits the collected information to an external device. However, the power storage system 100 is not limited to this embodiment. In other embodiments, each of the power storage module 110 and the power storage module 120 may collect information on the battery characteristics of the power storage unit included in each power storage module and transmit the collected information to an external device.

[0047] In this embodiment, the system control unit 140 determines the order in which the power storage units of the respective power storage modules are electrically connected to the wiring 106 based on the voltages of the power storage units of the respective power storage modules. For example, when starting the operation of the power storage system 100, if the state of the power storage system 100 starts from a charged state, the system control unit 140 electrically connects the power storage unit of the power storage module with a lower voltage to the wiring 106. On the other hand, when starting the operation of the power storage system 100, if the state of the power storage system 100 starts from a discharged state, the system control unit 140 electrically connects the power storage unit of the power storage module with a higher voltage to the wiring 106. Note that the system control unit 140 may determine the order in which the power storage units of the respective power storage modules are electrically connected to the wiring 106 based on the inter-terminal voltages of the respective power storage modules.

[0048] In one embodiment, the system control unit 140 may transmit signals for connecting the power storage unit to the wiring 106 to the respective power storage modules in the determined order. In other embodiments, the system control unit 140 may select the power storage module with the lowest voltage or SOC, or the power storage module with the highest voltage or SOC, and transmit a signal for connecting the power storage unit to the wiring 106 only to the selected power storage module.

[0049] The system control unit 140 may be implemented by hardware, software, or a combination of hardware and software. In one embodiment, the system control unit 140 may be implemented by an analog circuit, a digital circuit, or a combination of an analog circuit and a digital circuit. In other embodiments, the system control unit 140 may be realized by executing a program for controlling each part of the system control unit 140 in a general information processing device including a data processing device having a CPU, a ROM, a RAM, a communication interface, and the like.

[0050] The program installed in the computer and causing the computer to function as part of the system control unit 140 according to the present embodiment may include modules that define the operations of each part of the system control unit 140. These programs or modules act on a CPU or the like to cause the computer to function as each part of the system control unit 140.

[0051] The information processing described in these programs functions as a specific means for the software and the various hardware resources described above to cooperate when read by the computer. By these specific means, it is possible to construct a specific device according to the purpose of use by realizing the calculation or processing of information according to the purpose of use of the computer in the present embodiment. The program may be stored in a computer-readable medium or may be stored in a storage device connected to a network.

[0052] Note that "electrically connected" is not limited to the case where a specific element is directly connected to another element. A third element may be interposed between the specific element and the other element. Also, it is not limited to the case where the specific element and the other element are physically connected. For example, the input winding and the output winding of a transformer are not physically connected but are electrically connected. Further, it includes not only the case where a specific element and another element are actually electrically connected, but also the case where a specific element and another element are electrically connected when a power storage cell and a balance correction unit are electrically connected. Also, "connected in series" indicates that a specific element and another element are electrically connected in series, and "connected in parallel" indicates that a specific element and another element are electrically connected in parallel.

[0053] In this embodiment, the case where the power storage system 100 includes two power storage modules connected in parallel has been described. However, the power storage system 100 is not limited to this embodiment. In other embodiments, the power storage system 100 may have three or more power storage modules connected in parallel.

[0054] In this embodiment, the case where, before mounting the power storage module 110 in the power storage system 100, the user performs an operation for electrically connecting the power storage unit of the new power storage module 110 and the wiring 106 has been described. However, the method of mounting or replacing the power storage module 110 is not limited to this embodiment. In other embodiments, the user operates, for example, an input unit (not shown) of the power storage system 100 to input an instruction for starting the replacement work of the power storage module 110. Examples of the input unit include a keyboard, a pointing device, a touch panel, a microphone, a voice recognition system, a gesture input system, and the like.

[0055] When the system control unit 140 receives an instruction to start the replacement operation of the power storage module 110, it may perform an operation to electrically disconnect the power storage unit of the power storage module (in this embodiment, the power storage module 120) connected in parallel with the power storage module 110 and the wiring 106. At this time, the system control unit 140 may also perform an operation to electrically disconnect the power storage unit of the power storage module 110 and the wiring 106. For example, the system control unit 140 transmits a signal for turning off the switching element arranged between the positive electrode terminal of each power storage module and the power storage unit to the switching element.

[0056] When the system control unit 140 detects that the old power storage module 110 has been removed and the new power storage module 110 has been installed, it acquires the voltage of the power storage unit of each power storage module. When the power storage unit of the new power storage module 110 and the wiring 106 are electrically connected, the system control unit 140 operates the power storage system 100 using only the power storage module 110 until the voltage difference between the power storage module 110 and the power storage module 120 becomes an appropriate value. Then, when the voltage difference between the power storage module 110 and the power storage module 120 becomes an appropriate value, the system control unit 140 executes an operation to electrically connect the power storage module 120 and the wiring 106.

[0057] On the one hand, when the power storage unit of the new power storage module 110 and the wiring 106 are not electrically connected, the system control unit 140 determines the order in which the power storage units of the respective power storage modules are to be electrically connected to the wiring 106 based on the voltages of the power storage units of the respective power storage modules. Thereafter, the system control unit 140 electrically connects the power storage units of the respective power storage modules to the wiring 106 in the determined order. When the power storage unit of the new power storage module 110 and the wiring 106 are electrically connected, the system control unit 140 may first electrically disconnect the power storage unit of the new power storage module 110 and the wiring 106. Thereafter, based on the voltages of the power storage units of the respective power storage modules, the order in which the power storage units of the respective power storage modules are to be electrically connected to the wiring 106 is determined, and the power storage units of the respective power storage modules may be electrically connected to the wiring 106 in the determined order.

[0058] [Application Example of Power Storage System 100] As described above, according to the power storage system 100 according to the present embodiment, at least one of the power storage module 110 and the power storage module 120 connected in parallel to the load device 12 or the charging device 14 can be mounted or replaced at an arbitrary timing without worrying about the voltage difference between the two power storage modules. Here, the voltage difference between the power storage module 110 and the power storage module 120 can occur not only due to the difference in the charge state or discharge state of the two power storage modules but also due to the difference in the battery characteristics of the two power storage modules. The battery characteristics of the power storage module may be the same as the battery characteristics of the above-described power storage unit. The battery characteristics of the power storage module may be at least one of the characteristics exemplified as the battery characteristics of the power storage unit.

[0059] Therefore, according to the power storage system 100 according to the present embodiment, even when the battery characteristics of the power storage module 110 and the battery characteristics of the power storage module 120 are different, while preventing deterioration or damage of the power storage module 110 or the power storage module 120, the power storage module 110 and the power storage module 120 can be connected in parallel to the load device 12 or the charging device 14. In the power storage system 100 according to the present embodiment, the battery characteristics of the power storage module 110 and the battery characteristics of the power storage module 120 may be the same or different. When the power storage modules 110 and 120 include secondary batteries, the battery characteristics of the secondary batteries constituting the power storage unit of the power storage module 110 and the battery characteristics of the secondary batteries constituting the power storage unit of the power storage module 120 may be the same or different.

[0060] Also, a power supply system in which a plurality of power supply modules having different battery characteristics can be connected in parallel may be constructed with the same configuration as the power storage system 100. Thereby, while suppressing deterioration or damage of each power supply module, each power supply module can be mounted or replaced at an arbitrary timing. Adopting the same configuration as the power storage system 100 is particularly useful when the power supply system is a system in which an external charging device or load device is electrically connected by two terminals.

[0061] The power supply module may be an example of a power supply device that supplies power to other devices. The power storage module 110 and the power storage module 120 may be examples of power supply modules. The power storage system 100 may be an example of a power supply system configured such that a plurality of power supply devices can be connected in parallel. The power storage unit and the secondary battery may be examples of a power supply unit that serves as a power supply source of the power supply device.

[0062] The battery characteristics of the power supply device vary depending on factors such as (i) the degradation state of the power supply unit, (ii) the type of the power supply unit, and (iii) the balance state of the capacity and SOC. According to one embodiment, a power supply system is provided that can connect a plurality of power supply devices with different degradation states in parallel. Details of the above power supply system will be described later. According to this embodiment, for example, a power supply system can be constructed by using second-hand products (sometimes referred to as used products, recycled products, etc.) of power supply modules.

[0063] According to other embodiments, a power supply system is provided that can connect a plurality of power supply devices with different types in parallel. Thereby, compared with the case where a power supply system is constructed by combining a single type of power supply device, a power supply system excellent in at least one of lifespan, reliability, charging performance, discharging performance, energy efficiency, temperature characteristics, and economy can be constructed. Details of the above power supply system will be described later.

[0064] In the power storage system 100 according to this embodiment, the case where the plurality of power supply modules constituting the power storage system 100 are the power storage module 110 and the power storage module 120 has been described. However, the plurality of power supply modules constituting the power storage system 100 are not limited to this embodiment. In other embodiments, at least one of the plurality of power supply modules may include a primary battery or may include a fuel cell. In other embodiments, at least one of the plurality of power supply modules includes a primary battery or a fuel cell, and at least one of the plurality of power supply modules may include a secondary battery. The power storage unit, the primary battery, and the fuel cell may be an example of the power supply unit.

[0065] In these cases, the power supply module including the primary battery or the fuel cell may switch the connection relationship between the primary battery or the fuel cell of the power supply module and the wiring 106 based on a control signal from the system control unit 140 or a user operation, with the same configuration as that of the power storage modules 110 and 120. For example, when the power supply module receives a signal indicating that a discharge operation has been detected from the system control unit 140, the power supply module electrically connects the primary battery or the fuel cell of the power supply module and the wiring 106. On the other hand, when the power supply module receives a signal indicating that a charging operation has been detected from the system control unit 140, the power supply module disconnects the electrical connection relationship between the primary battery or the fuel cell of the power supply module and the wiring 106. Thereby, damage or deterioration of the primary battery or the fuel cell can be prevented.

[0066] [First Application Example of Power Storage System 100] In one embodiment, the power storage system 100 includes a plurality of power supply devices. The plurality of power supply devices may include two power supply devices with different degradation states of the power supply unit. The plurality of power supply devices may be connected in parallel to the load device 12 or the charging device 14. The power storage system 100 may be electrically connected to the load device 12 or the charging device 14 by two terminals. At least one of the plurality of power supply devices may be detachably held in the housing of the power storage system 100. Thereby, each power supply device can be replaced individually. The power storage system 100 may include at least one power storage module.

[0067] Examples of the power supply devices with different degradation states can include power supply devices with different usage histories. For example, the power storage system 100 has a new power supply device and a reused power supply device. The power storage system 100 may also have a plurality of reused products with different usage histories.

[0068] In recent years, the demand for storage batteries has been rapidly increasing in applications such as (i) power sources for electric vehicles, plug-in hybrid electric vehicles (PHEVs), etc., (ii) output stabilization devices for renewable energy, (iii) energy storage devices for smart grids, (iv) energy storage devices for storing electricity during time periods with low electricity rates, and (v) energy storage devices for applications that temporarily require a large current, such as charging stations. Also, the number of storage batteries reaching their replacement time has been increasing.

[0069] Here, the performance required of a storage battery varies depending on the application. Therefore, even when a storage battery used in a specific application deteriorates and no longer satisfies the required performance in that application, the storage battery may be reused by diverting it to another application. Also, as a result of the improvement in the performance of the storage battery, the life of the storage battery may be longer than the life of the product incorporating the storage battery. Even in such cases, it is desirable to reuse the storage battery instead of discarding it.

[0070] When reusing a storage battery, the state of deterioration varies for each storage battery. Therefore, conventionally, before reusing a storage battery, the battery characteristics of the storage battery have been inspected. Also, based on the inspection results, a power supply system has been constructed by combining storage batteries whose battery characteristics satisfy specific conditions. However, in order to inspect the battery characteristics, it is necessary to fully charge the storage battery and then discharge it, which requires labor and time.

[0071] In contrast, according to the present embodiment, a power storage system 100 in which a plurality of power supply devices having different states of deterioration are connected in parallel can be easily constructed. Also, while operating the power storage system 100, each power supply device can be individually mounted or removed. Furthermore, at least a part of the inspection of the power supply device can be omitted before incorporating the reused power supply device into the power storage system 100.

[0072] According to this embodiment, each power supply device can switch the connection relationship between the power supply unit of each power supply device and the wiring 106 based on a control signal from the system control unit 140 or a user operation. Thereby, even when the battery characteristics of the reused power supply device have not been inspected in advance, the power storage system 100 can be safely operated. Also, while operating the power storage system 100, the battery characteristics of the power supply device can be examined. And when the battery characteristics of the power supply device are insufficient, the power supply device can be easily replaced.

[0073] [Second application example of the power storage system 100] In another embodiment, the power storage system 100 includes a plurality of power supply devices. The plurality of power supply measures may include two power supply devices having different types of power supply units. The plurality of power supply devices may be connected in parallel to the load device 12 or the charging device 14. The power storage system 100 may be electrically connected to the load device 12 or the charging device 14 by two terminals. At least one of the plurality of power supply devices may be detachably held in the housing of the power storage system 100. Thereby, each power supply device can be replaced individually. The power storage system 100 may include at least one power storage module.

[0074] Examples of the type of the power supply unit can include a primary battery, a secondary battery, a fuel cell, etc. Examples of the type of the secondary battery can include a lithium battery, a lithium-ion battery, a lithium-sulfur battery, a sodium-sulfur battery, a lead battery, a nickel-metal hydride battery, a nickel-cadmium battery, a redox flow battery, a metal-air battery, etc. The type of the lithium-ion battery is not particularly limited. Examples of the type of the lithium-ion battery can include a lithium iron phosphate type, a manganese type, a cobalt type, a nickel type, a ternary type, etc.

[0075] When the types of power supply units included in each of two power supply devices are different, the difference in the rated voltages of the two power supply devices may exceed a predetermined value. Also, the difference in at least one of the charging characteristics and discharging characteristics of the two power supply devices may not satisfy predetermined conditions. Conventionally, a power supply system has been constructed by finding power supply devices that meet specific conditions and combining them. Therefore, there has been no idea of connecting such two power supply devices in parallel in the first place.

[0076] On the other hand, according to the present embodiment, a power storage system 100 in which a plurality of power supply devices of different types are connected in parallel can be easily constructed. Also, while operating the power storage system 100, each power supply device can be individually mounted or removed. Furthermore, depending on the type of the power supply unit included in the power supply device, the electrical connection relationship between the power supply unit and the load device 12 or the charging device 14 can be disconnected during the charging operation of the power storage system 100.

[0077] According to the present embodiment, each power supply device can switch the connection relationship between the power supply unit of each power supply device and the wiring 106 based on a control signal from the system control unit 140 or a user operation. Thereby, even when the difference in the rated voltages of the two power supply devices included in the power storage system 100 exceeds a predetermined value, or when the difference in at least one of the charging characteristics and discharging characteristics of the two power supply devices does not satisfy predetermined conditions, the power storage system 100 can be safely operated.

[0078] Further, according to the present embodiment, compared with the case where a power supply system is constructed by combining a single type of power supply device, a power supply system excellent in at least one of lifespan, reliability, charging performance, discharging performance, energy efficiency, temperature characteristics, and economy can be constructed. For example, (i) a power supply module including a lead battery that operates in a relatively wide temperature range but has a relatively low energy efficiency for charge and discharge, and (ii) a power supply module including a lithium-ion battery that has high energy efficiency for charge and discharge but has problems in operating in a low-temperature region and a high-temperature region are combined to construct a power supply system that operates in a wide temperature range and has high energy efficiency.

[0079] FIG. 2 schematically shows an example of the system configuration of the power storage module 110. In the present embodiment, the power storage module 110 includes a power storage unit 210 having a positive electrode terminal 212 and a negative electrode terminal 214, a switching unit 230, a module control unit 240, a protection unit 250, and a balance correction unit 260. Further, in the present embodiment, the power storage unit 210 includes a power storage cell 222 and a power storage cell 224. The switching unit 230 may be an example of a switching element. The module control unit 240 may be an example of a control unit. The module control unit 240 may be an example of a control device. The module control unit 240 may be an example of a battery characteristic acquisition unit. The module control unit 240 may be an example of an output unit.

[0080] The impedance of the power storage unit 210 may be 1 Ω or less, or may be 100 mΩ or less. The impedance of the power storage unit 210 may be 10 mΩ or less, may be 1 mΩ or less, may be 0.8 mΩ or less, or may be 0.5 mΩ or less. The impedance of the power storage unit 210 may be 0.1 mΩ or more. The impedance of the power storage unit 210 may be 0.1 mΩ or more and 1 Ω or less, may be 0.1 mΩ or more and 100 mΩ or less, may be 0.1 mΩ or more and 10 mΩ or less, or may be 0.1 mΩ or more and 1 mΩ or less.

[0081] According to the power storage system 100 according to the present embodiment, for example, when replacing one of a plurality of power storage modules connected in parallel, it is not necessary to match with high accuracy the voltage of the power storage module newly added to the power storage system and the voltages of the other remaining power storage modules. Therefore, even when the impedance of the power storage unit 210 is small, the power storage module 110 can be replaced easily and quickly.

[0082] In the present embodiment, the power storage cells 222 and 224 are connected in series. The power storage cells 222 and 224 may be secondary batteries or capacitors. At least one of the power storage cells 222 and 224 may be a lithium-ion battery. At least one of the power storage cells 222 and 224 may include a plurality of power storage cells connected in series, in parallel, or in a matrix inside the power storage cell.

[0083] In the present embodiment, the positive electrode terminal 212 of the power storage unit 210 is electrically connected to the wiring 106 via the positive electrode terminal 112 of the power storage module 110 and the switching unit 230. On the other hand, the negative electrode terminal 214 of the power storage unit 210 is electrically connected to the wiring 106 via the negative electrode terminal 114 of the power storage module 110. However, the power storage module 110 is not limited to the present embodiment. In other embodiments, the negative electrode terminal 214 of the power storage unit 210 is electrically connected to the wiring 106 via the negative electrode terminal 114 of the power storage module 110 and the switching unit 230. On the other hand, the positive electrode terminal 212 of the power storage unit 210 is electrically connected to the wiring 106 via the positive electrode terminal 112 of the power storage module 110.

[0084] The switching unit 230 is disposed between the wiring 106 and the power storage unit 210. In the present embodiment, the switching unit 230 switches the connection state between the wiring 106 and the power storage unit 210 based on a signal generated by the module control unit 240. Thereby, the power storage unit 210 can be electrically connected to the wiring 106 or electrically disconnected from the wiring 106. When the power storage module 110 is mounted on the power storage system 100, the power storage module 110 may be mounted on the power storage system 100 in a state where the power storage unit 210 and the wiring 106 are electrically disconnected by the switching unit 230. Thereby, damage or deterioration of the power storage module 110 can be prevented.

[0085] The switching unit 230 may be realized by hardware, may be realized by software, or may be realized by a combination of hardware and software. The switching unit 230 may be realized by an analog circuit, a digital circuit, or a combination of an analog circuit and a digital circuit. The switching unit 230 may have one or more elements. The switching unit 230 may have one or more switching elements. Each of the one or more switching elements may be disposed between the positive electrode terminal 112 and the positive electrode terminal 212, or between the negative electrode terminal 114 and the negative electrode terminal 214. Examples of the switching element include a relay, a thyristor, a transistor, and the like. The thyristor may be a bidirectional thyristor (sometimes referred to as a triac). The transistor may be a semiconductor transistor. The semiconductor transistor may be a bipolar transistor or a field effect transistor. The field effect transistor may be a MOSFET.

[0086] The module control unit 240 controls the current flowing between the power storage unit 210 of the power storage module 110 and the wiring 106. In the present embodiment, when the voltage between the terminals of the switching unit 230 (in the present embodiment, it is the voltage between the positive electrode terminal 112 and the positive electrode terminal 212) satisfies a predetermined condition, the module control unit 240 controls the switching unit 230 so that the switching unit 230 electrically connects the power storage unit 210 and the wiring 106. The switching unit 230 may electrically connect the power storage unit 210 and the wiring 106 by electrically connecting the power storage unit 210 and the positive electrode terminal 112.

[0087] On the other hand, when the voltage between the terminals of the switching unit 230 does not satisfy a predetermined condition, the module control unit 240 controls the switching unit 230 so that the switching unit 230 electrically disconnects the power storage unit 210 and the wiring 106 or the positive electrode terminal 112. The switching unit 230 may electrically disconnect the power storage unit 210 and the wiring 106 by electrically disconnecting the power storage unit 210 and the positive electrode terminal 112.

[0088] The predetermined condition may be that the absolute value of the voltage between the terminals of the switching unit 230 is within a predetermined range. The predetermined range may be 3V or less, 1V or less, 0.1V or less, 10mV or less, 1mV or less. Also, the predetermined range may be 0.5mV or more, 1mV or more. The predetermined range may be 0.5mV or more and 3V or less. The predetermined range may be 1mV or more and 3V or less, 1mV or more and 1V or less, 1mV or more and 0.1V or less, 1mV or more and 10mV or less, 10mV or more and 1V or less, 10mV or more and 0.1V or less, 0.1V or more and 1V or less. Note that the voltage between the terminals of the switching unit 230 may be the voltage between the positive electrode terminal 112 and the positive electrode terminal 212, or may be the voltage between the wiring 106 and the power storage unit 210.

[0089] The predetermined range may be set based on the impedance of the power storage unit 210. The predetermined range may be set based on the rated current or allowable current of the power storage unit 210. The predetermined range may be set based on the impedance of the power storage unit 210 and the rated current or allowable current of the power storage unit 210. The predetermined range may be set based on the rated current or allowable current of the element having the smallest rated current or allowable current among the elements constituting the power storage module 110. The predetermined range may be set based on the impedance of the power storage module 110 and the rated current or allowable current of the element having the smallest rated current or allowable current among the elements constituting the power storage module 110.

[0090] Thereby, when replacing the power storage module, until the voltage difference between the newly mounted power storage module and the already mounted power storage module falls within a predetermined range, the state where the wiring 106 and the power storage unit 210 of the newly mounted power storage module are electrically disconnected can be maintained. Then, when the voltage difference between the newly mounted power storage module and the already mounted power storage module falls within a predetermined range due to charging or discharging of the already mounted power storage module, the power storage unit of the newly mounted power storage module is electrically connected to the wiring 106. Thus, according to the present embodiment, a newly mounted power storage module and other power storage modules can be automatically connected.

[0091] In the present embodiment, the module control unit 240 receives a signal from the system control unit 140 indicating that the inter-terminal voltage of the power storage module 110 is smaller than the inter-terminal voltage of other power storage modules. When the module control unit 240 receives the above signal when the power storage system 100 shifts to the charging state, the module control unit 240 controls the switching unit 230 so that the switching unit 230 electrically connects the power storage unit 210 and the wiring 106. Thereby, a plurality of power storage modules 110 connected in parallel can be efficiently charged.

[0092] In this embodiment, the module control unit 240 receives, from the system control unit 140, a signal indicating that the inter-terminal voltage of the power storage module 110 is greater than the inter-terminal voltages of other power storage modules. When the module control unit 240 receives the above signal when the power storage system 100 shifts to a discharging state, the module control unit 240 controls the switching unit 230 so that the switching unit 230 electrically connects the power storage unit 210 and the wiring 106. Thereby, a plurality of power storage modules 110 connected in parallel can be efficiently discharged.

[0093] In this embodiment, the module control unit 240 receives, from the protection unit 250, a signal indicating that the inter-terminal voltage of the power storage cell 222 or the power storage cell 224 is not within a predetermined range. When the module control unit 240 receives the signal, the module control unit 240 controls the switching unit 230 so that the switching unit 230 electrically disconnects the power storage unit 210 and the wiring 106. Thereby, deterioration or damage of the power storage unit 210 due to overcharging or over-discharging can be suppressed.

[0094] In this embodiment, the module control unit 240 receives a user operation and receives an instruction from the user to turn on or off the switching unit 230. When the module control unit 240 receives the user's instruction, the module control unit 240 controls the switching unit 230 according to the instruction.

[0095] In this embodiment, the module control unit 240 may acquire information regarding the battery characteristics of the power storage unit 210. The module control unit 240 may output the information regarding the battery characteristics of the power storage unit 210 to an external device. Thereby, the external device can utilize the information regarding the battery characteristics of the power storage unit 210. Examples of the external device include the load device 12, the charging device 14, and the like. The external device may be an output device that outputs information to the user.

[0096] The module control unit 240 may be implemented by hardware, may be implemented by software, or may be implemented by a combination of hardware and software. In one embodiment, the module control unit 240 may be implemented by an analog circuit, a digital circuit, or a combination of an analog circuit and a digital circuit. In other embodiments, the module control unit 240 may be realized by executing a program for controlling the module control unit 240 in a general information processing device including a data processing device having a CPU, a ROM, a RAM, a communication interface, and the like.

[0097] The program installed in the computer and causing the computer to function as part of the module control unit 240 according to this embodiment may include modules that define the operations of the respective parts of the module control unit 240. These programs or modules act on a CPU or the like to cause the computer to function as each part of the module control unit 240.

[0098] The information processing described in these programs functions as a specific means by which software and the various hardware resources described above cooperate when read into the computer. By these specific means, it is possible to construct a specific device according to the purpose of use by realizing the calculation or processing of information according to the purpose of use of the computer in this embodiment. The program may be stored in a computer-readable medium or may be stored in a storage device connected to a network. The computer-readable medium may be a non-transitory computer-readable medium.

[0099] The protection unit 250 protects the power storage unit 210. In the present embodiment, the protection unit 250 protects the power storage unit 210 from overcharging and overdischarging. When the protection unit 250 detects that the voltage between the terminals of the power storage cell 222 or the power storage cell 224 is not within a predetermined range, it transmits a signal indicating that fact to the module control unit 240. The protection unit 250 may transmit information regarding the voltage between the terminals of the power storage unit 210 to the system control unit 140. The protection unit 250 may be realized by hardware, may be realized by software, or may be realized by a combination of hardware and software. The protection unit 250 may be realized by an analog circuit, a digital circuit, or a combination of an analog circuit and a digital circuit.

[0100] The balance correction unit 260 equalizes the voltages of a plurality of power storage cells. The operating principle of the balance correction unit 260 is not particularly limited, and any balance correction device can be used. When the power storage unit 210 has three or more power storage cells, the power storage module 110 may have a plurality of balance correction units 260. For example, when the power storage unit 210 has n (n is an integer of 2 or more) power storage cells, the power storage module 110 has n - 1 balance correction units 260.

[0101] The balance correction unit 260 may be implemented by hardware, may be implemented by software, or may be implemented by a combination of hardware and software. The balance correction unit 260 may be implemented by an analog circuit, a digital circuit, or a combination of an analog circuit and a digital circuit. In one embodiment, the balance correction unit 260 is an active type balance correction device. The active type balance correction unit may be a balance correction unit that moves charges between two storage cells via an inductor as described in Japanese Patent Application Laid-Open No. 2006-067742, or may be a balance correction unit that moves charges using a capacitor as described in Japanese Patent Application Laid-Open No. 2012-210109. In other embodiments, the balance correction unit 260 may be a passive type balance correction device. The passive type balance correction device discharges excess charges using, for example, an external resistor.

[0102] In this embodiment, the case where the power storage unit 210 has two power storage cells connected in series has been described. However, the power storage unit 210 is not limited to this embodiment. In other embodiments, the power storage unit 210 may have three or more power storage cells connected in series. Further, the power storage unit 210 may have a plurality of power storage cells connected in parallel, or may have a plurality of cells connected in a matrix.

[0103] FIG. 3 schematically shows an example of the system configuration of the module control unit 240. In this embodiment, the module control unit 240 includes a determination unit 310, a reception unit 320, and a signal generation unit 330. The module control unit 240 may further include a module information acquisition unit 340, a module information storage unit 350, and a module information transmission unit 360. The reception unit 320 may be an example of a first signal reception unit, a second signal reception unit, and a third signal reception unit. The module information acquisition unit 340 may be an example of a battery characteristic acquisition unit. The module information transmission unit 360 may be an example of an output unit.

[0104] In this embodiment, a case where the module control unit 240 includes a module information acquisition unit 340, a module information storage unit 350, and a module information transmission unit 360 will be described. However, the power storage system 100 is not limited to this embodiment. In other embodiments, the system control unit 140 may include at least one of a module information acquisition unit 340, a module information storage unit 350, and a module information transmission unit 360.

[0105] The determination unit 310 determines whether the inter-terminal voltage of the switching unit 230 is within a predetermined range. The determination unit 310 transmits a signal indicating the determination result to the signal generation unit 330. The determination unit 310 may be any comparator or comparison circuit. The determination unit 310 may be a window comparator.

[0106] The reception unit 320 receives at least one of a signal from the system control unit 140, a signal from the protection unit 250, and an instruction from the user. The reception unit 320 transmits a signal corresponding to the received information to the signal generation unit 330.

[0107] The signal generation unit 330 receives a signal from at least one of the determination unit 310 and the reception unit 320. The signal generation unit 330 generates a signal for controlling the switching unit 230 based on the received information. The signal generation unit 330 transmits the generated signal to the switching unit 230.

[0108] In one embodiment, when the determination unit 310 determines that the inter-terminal voltage of the switching unit 230 is within a predetermined range, the signal generation unit 330 generates a signal for turning on the switching element of the switching unit 230. In other embodiments, when the determination unit 310 determines that the inter-terminal voltage of the switching unit 230 is not within a predetermined range, the signal generation unit 330 generates a signal for turning off the switching element of the switching unit 230.

[0109] The signal generation unit 330 may generate or transmit a signal after a predetermined time has elapsed since the determination unit 310 determines whether the voltage between the terminals of the switching unit 230 is within a predetermined range. Thereby, malfunction due to noise or the like can be prevented. Also, it is possible to prevent the power storage unit 210 and the wiring 106 from being electrically connected immediately after the power storage module 110 is attached to the power storage system 100.

[0110] In the present embodiment, the signal generation unit 330 generates a signal for controlling the switching element of the switching unit 230 based on the signal received by the reception unit 320. In one embodiment, when the reception unit 320 receives a signal for turning on the switching element of the switching unit 230 from the system control unit 140, the signal generation unit 330 generates a signal for turning on the switching element of the switching unit 230.

[0111] In another embodiment, when the reception unit 320 receives a signal for turning off the switching element of the switching unit 230 from the protection unit 250, the signal generation unit 330 generates a signal for turning off the switching element of the switching unit 230. In still another embodiment, when the reception unit 320 receives a user instruction, the signal generation unit 330 generates a signal for operating the switching element of the switching unit 230 according to the user instruction.

[0112] In the present embodiment, the module information acquisition unit 340 acquires information regarding the battery characteristics of the power storage unit 210. The module information acquisition unit 340 may acquire information regarding the battery characteristics of the power storage unit 210 by measuring the battery characteristics of the power storage unit 210. The module information acquisition unit 340 may acquire information regarding the battery characteristics of the power storage unit 210 input by a manufacturer, a seller, or the like at the time of shipment, inspection, or sale.

[0113] The module information acquisition unit 340 may store information regarding the battery characteristics of the power storage unit 210 in the module information storage unit 350. The specific configuration of the module information acquisition unit 340 is not particularly limited, but the module information acquisition unit 340 may be a controller that controls the reading and writing of data in the module information storage unit 350. In the present embodiment, the module information storage unit 350 stores information regarding the battery characteristics of the power storage unit 210 acquired by the module information acquisition unit 340.

[0114] In the present embodiment, the module information transmission unit 360 transmits information regarding the battery characteristics of the power storage unit 210 acquired by the module information acquisition unit 340 to the system control unit 140. The module information transmission unit 360 may transmit information regarding the battery characteristics of the power storage unit 210 acquired by the module information acquisition unit 340 to an external device. The module information transmission unit 360 may transmit information regarding the battery characteristics of the power storage unit 210 in response to a request from an external device, or may transmit information regarding the battery characteristics of the power storage unit 210 at a predetermined timing. The module information transmission unit 360 may refer to the module information storage unit 350 and transmit information regarding the battery characteristics of the power storage unit 210 to the system control unit 140 or an external device.

[0115] FIG. 4 schematically shows an example of the system configuration of the system control unit 140. In the present embodiment, the system control unit 140 includes a state management unit 410, a module selection unit 420, and a signal generation unit 430. The state management unit 410 may be an example of a battery characteristic acquisition unit. The state management unit 410 may also be an example of an output unit.

[0116] In this embodiment, the state management unit 410 manages the state of the power storage system 100. The state management unit 410 may manage the states of the power storage modules 110 and 120. The state management unit 410 may monitor the respective states of the power storage modules 110 and 120. The state management unit 410 may monitor the power storage modules 110 and 120 to obtain information regarding the battery characteristics of each of the power storage modules 110 and 120. The state management unit 410 may transmit the information obtained by monitoring the power storage modules 110 and 120 to an external device.

[0117] While operating the power storage system 100, the state management unit 410 may measure the battery characteristics of each power storage module. When the battery characteristics of a power storage module do not satisfy a predetermined condition, the state management unit 410 may output, to an output device that outputs information to the user, information indicating that the performance of the power storage module is insufficient. The state management unit 410 may output the identification information of the power storage module and information indicating that the performance of the power storage module is insufficient.

[0118] Thereby, the user can easily identify a power storage module with insufficient performance and replace the power storage module. According to this embodiment, for example, when constructing the power storage system 100 using reused power storage modules, at least a part of the inspection of the reused power storage modules can be omitted.

[0119] In one embodiment, when the power storage system 100 transitions to a charged state, the module selection unit 420 selects the power storage module having the smallest inter-terminal voltage among the plurality of power storage modules included in the power storage system 100. For example, the module selection unit 420 compares the inter-terminal voltages of the power storage modules 110 and 120 and selects the power storage module with the smaller inter-terminal voltage. The module selection unit 420 transmits a signal indicating the selected power storage module to the signal generation unit 430.

[0120] In other embodiments, when the power storage system 100 transitions to a discharging state, the module selection unit 420 selects the power storage module with the largest inter-terminal voltage among the plurality of power storage modules included in the power storage system 100. For example, the module selection unit 420 compares the inter-terminal voltages of the power storage module 110 and the power storage module 120 and selects the power storage module with the larger inter-terminal voltage. The module selection unit 420 transmits a signal indicating the selected power storage module to the signal generation unit 430.

[0121] In this embodiment, the signal generation unit 430 generates a signal for turning on the switching element of the switching unit 230 of the selected power storage module with respect to the power storage module selected by the module selection unit 420. The signal generation unit 430 transmits the generated signal to the module control unit 240. In other embodiments, the signal generation unit 430 may generate a signal for turning off the switching element of the switching unit 230 of the selected power storage module with respect to the power storage module selected by the module selection unit 420.

[0122] FIG. 5 schematically shows an example of the circuit configuration of the power storage module 110. For the purpose of simplifying the description, in FIG. 5, the protection unit 250 and the wiring related to the protection unit 250 are not shown.

[0123] In this embodiment, the switching unit 230 includes a transistor 510, a resistor 512, a resistor 514, a diode 516, a transistor 520, a resistor 522, a resistor 524, and a diode 526. The transistors 510 and 520 may be an example of a switching element. In this embodiment, the case where the transistors 510 and 520 are used as the switching elements of the switching unit 230 will be described. However, the switching elements of the switching unit 230 are not limited to this embodiment. In other embodiments, a single switching element may be used as the switching element of the switching unit 230.

[0124] In this embodiment, the module control unit 240 includes a determination unit 310, a signal generation unit 330, and switches 592 and 594. In this embodiment, the determination unit 310 includes a transistor 530, a resistor 532, a transistor 540, a resistor 542, a resistor 552, and a resistor 554. The signal generation unit 330 includes a transistor 560, a capacitor 570, a resistor 572, and a transistor 580. The switches 592 and 594 may be an example of the reception unit 320.

[0125] Next, the details of each part of the switching unit 230 and the module control unit 240 will be described. In the switching unit 230 of this embodiment, the transistor 510 is a MOSFET. Even when the transistor 510 is off, a current can flow from the positive terminal 212 toward the positive terminal 112 through a parasitic diode (not shown) equivalently formed between the source and drain of the transistor 510. Similarly, the transistor 520 is a MOSFET. Even when the transistor 520 is off, a current can flow from the positive terminal 112 toward the positive terminal 212 through a parasitic diode (not shown) equivalently formed between the source and drain of the transistor 520.

[0126] In this embodiment, the transistors 510 and 520 are set to be off in the initial setting. When the transistor 580 is turned on during charging of the power storage system 100, a current flows from the positive terminal 112 toward the negative terminal 114 through the resistor 512, the resistor 514, and the transistor 580. As a result, a voltage is applied to the gate of the transistor 510, and the transistor 510 is turned on. Thereby, a current can flow from the positive terminal 112 toward the positive terminal 212 through the parasitic diode equivalently formed between the source and drain of the transistor 520.

[0127] On the one hand, when the transistor 580 operates in the on state during the discharge of the power storage system 100, a current flows from the positive terminal 212 toward the negative terminal 214 via the resistor 522, the resistor 524, and the transistor 580. As a result, a voltage is applied to the gate of the transistor 520, and the transistor 520 operates in the on state. Thereby, a current can flow from the positive terminal 212 toward the positive terminal 112 via the parasitic diode equivalently formed between the source and the drain of the transistor 510.

[0128] As the transistor 580 operates in the on state, the voltage applied to the gate of the transistor 510 or the transistor 520 may be an example of a signal for operating the switching element of the switching unit 230 in the on state. Similarly, as the transistor 580 operates in the off state, the voltage applied to the gate of the transistor 510 or the transistor 520 may be an example of a signal for operating the switching element of the switching unit 230 in the off state.

[0129] In the present embodiment, the values of the resistors 512 and 514 are set so that the transistor 510 can be surely turned on / off with low power consumption. Also, the values of the resistors 522 and 524 are set so that the transistor 520 can be surely turned on / off with low power consumption.

[0130] In the present embodiment, a diode 516 is arranged between the resistor 514 and the resistor 524. The diode 516 allows a current to pass in the direction from the resistor 514 toward the resistor 524, but does not allow a current to pass in the direction from the resistor 524 toward the resistor 514. By providing the diode 516, it is possible to prevent a current from leaking from the positive terminal 212 to the positive terminal 112 through the route of the resistors 522, 524, 514, and 512 when the switching unit 230 electrically disconnects the positive terminal 112 and the positive terminal 212.

[0131] In this embodiment, a diode 526 is arranged between a resistor 514 and a resistor 524. The diode 526 allows current to pass in the direction from the resistor 524 to the resistor 514, but does not allow current to pass in the direction from the resistor 514 to the resistor 524. By providing the diode 526, when the switching unit 230 electrically disconnects the positive terminal 112 and the positive terminal 212, it is possible to prevent current from leaking from the positive terminal 112 to the positive terminal 212 through the route of the resistors 512, 514, 524, and 522.

[0132] In the module control unit 240 of this embodiment, the transistors 530 and 540 of the determination unit 310 are set to off in the initial setting. Also, the transistors 560 and 580 of the signal generation unit 330 are set to off in the initial setting.

[0133] According to this embodiment, the value of the resistor 532 is set such that the transistor 530 turns on when the voltage between the terminals of the switching unit 230 is smaller than a predetermined first value with the positive terminal 112 side being positive. The value of the resistor 532 is preferably set such that the current leaking when the switching unit 230 is off is minimized. Also, the value of the resistor 542 is set such that the transistor 540 turns on when the voltage between the terminals of the switching unit 230 is larger than a predetermined second value. The value of the resistor 542 is preferably set such that the current leaking when the switching unit 230 is off is minimized. Note that according to this embodiment, the voltage between the terminals of the switching unit 230 is equal to the voltage difference between the positive terminal 112 and the positive terminal 212.

[0134] When the voltage between the terminals of the switching unit 230 is smaller than a predetermined first value, the transistor 530 turns on, and a voltage is applied from the power storage unit 210 to the base of the transistor 560 via the positive electrode terminal 212, the transistor 530, and the resistor 552, causing the transistor 560 to turn on. Although a voltage from the positive electrode terminal 112 is applied to the base of the transistor 580, the on-operation of the transistor 580 is blocked while the transistor 560 is in the on-operation. As a result, the transistor 580 turns off.

[0135] On the other hand, when the voltage between the terminals of the switching unit 230 is larger than a predetermined second value, the transistor 540 turns on, and a voltage is applied from the positive electrode terminal 112 to the base of the transistor 560 via the transistor 540 and the resistor 554, causing the transistor 560 to turn on. As a result, the transistor 580 turns off.

[0136] In the present embodiment, the value of the resistor 552 is set so as to reduce power consumption within a range where the transistor 560 can be turned on when the transistor 530 is on. The value of the resistor 554 is set so as to reduce power consumption within a range where the transistor 560 can be turned on when the transistor 540 is on.

[0137] The capacitance of the capacitor 570 is set so that the transistor 560 turns on before the transistor 580 turns on when a voltage from the positive electrode terminal 112 is applied to the base of the transistor 580. Thereby, the signal generation unit 330 can generate a signal after a predetermined time has elapsed since the determination unit 310 determines whether or not the voltage between the terminals of the switching element is within a predetermined range.

[0138] On the other hand, when the voltage between the terminals of the switching unit 230 is within the range defined by the first value and the second value, the transistor 530 and the transistor 540 remain off, and the transistor 560 also remains off. Therefore, a voltage is applied from the positive terminal 112 to the base of the transistor 580 via the resistor 572, and the transistor 580 operates in the on state.

[0139] The switch 592 and the switch 594 may be manual switches, or may be switching elements such as relays, thyristors, and transistors. A signal 52 indicating that the switching unit 230 is to be operated in the on state may be input to the switch 592. A signal 54 indicating that the switching unit 230 is to be operated in the off state may be input to the switch 594.

[0140] When the switch 592 operates in the on state, the switching unit 230 can be operated in the on state regardless of whether the transistor 580 is on or off. When the switch 594 operates in the on state, the transistor 580 can be operated in the off state regardless of whether the transistor 560 is on or off. As a result, the switching unit 230 can be operated in the off state.

[0141] FIG. 6 schematically shows an example of the system configuration of the switching unit 630. The switching unit 630 is different from the switching unit 230 described in relation to FIG. 5 in that it has a relay 632 connected in parallel with the transistors 510 and 520. In other respects, it may have the same configuration as the switching unit 230. In the present embodiment, the transistors 510 and 520 may be semiconductor transistors. The transistors 510 and 520 may be field effect transistors (FETs).

[0142] Although the relay circuit has an excellent characteristic that its resistance is small when the circuit is on, its response speed is relatively slow. Therefore, for example, when the load device is a device having a pulsed current pattern such as a motor and the voltage fluctuates greatly in a short time, it is difficult to turn on following the signal from the signal generation unit 330. On the other hand, although the semiconductor transistor has a large power consumption compared with the relay circuit, it has excellent responsiveness. According to the switching unit 630 of the present embodiment, the transistor 510 or the transistor 520 using the semiconductor transistor and the relay 632 using the relay circuit are connected in parallel.

[0143] Therefore, when the switching unit 230 receives a signal for turning on the switching unit 230 from the signal generation unit 330, first, the transistor 510 or the transistor 520 quickly responds and turns on the switching unit 230. Then, with a slight delay, the relay 632 turns on. When the relay 632 is turned on, since the relay 632 with a small resistance is connected in parallel to the transistors 510 and 520, the combined resistance becomes small and the loss can be reduced.

[0144] The power storage module 710 will be described with reference to FIGS. 7 and 8. FIG. 7 schematically shows an example of the system configuration of the power storage module 710. FIG. 8 schematically shows an example of the system configuration of the switching unit 730. In FIG. 8, for the purpose of helping the understanding of the operations of the transistors 510 and 520, the parasitic diode 842 of the transistor 510 and the parasitic diode 844 of the transistor 520 are illustrated.

[0145] The power storage module 710 is different from the power storage module 110 described in relation to FIG. 2 in that it has a switching unit 730 instead of the switching unit 230 and that the signal from the protection unit 250 is transmitted to the switching unit 730 instead of the module control unit 240. For other points, it may have the same configuration as the power storage module 110.

[0146] In this embodiment, the switching unit 730 receives a signal from the module control unit 240 for turning on or off the switching unit 730. Further, the switching unit 730 receives a signal from the protection unit 250 for turning off the switching unit 730.

[0147] According to this embodiment, when a signal 82 for turning on the switching element of the switching unit 730 is input to the logic circuit 852 and a signal 88 indicating that the power storage unit 210 is in an overcharged state is not input, the transistor 510 is turned on. Also, when a signal 82 for turning on the switching element of the switching unit 730 is input to the logic circuit 854 and a signal 86 indicating that the power storage unit 210 is in an overdischarged state is not input, the transistor 520 is turned on.

[0148] FIG. 9 schematically shows an example of the system configuration of the power storage system 900. The power storage system 900 is different from the power storage system 100 in that it includes a plurality of power storage modules 110 connected in a matrix. In other respects, it may have the same configuration as the power storage system 100. In this embodiment, a first block including three power storage modules 110 connected in parallel and a diode 902 and a second block including three power storage modules 110 connected in parallel and a diode 904 are connected in series.

[0149] According to this embodiment, during discharge of the power storage system 900, discharge continues until all of the plurality of power storage modules 110 included in a specific block reach a fully discharged state, and then discharge from that block stops. According to this embodiment, even when discharge from the above block stops, the current can be bypassed by the diode 902. Thereby, the power supply by the power storage system 900 can be continued. Therefore, while the power storage system 900 is discharging power, the output voltage decreases stepwise.

[0150] Similarly, when the power storage system 900 is being charged, among the plurality of power storage modules 110 included in a specific block, the connection with the power storage system 900 is sequentially disconnected from the power storage modules 110 that have reached the fully charged state. And finally, the charging of all the power storage modules 110 is completed.

[0151] According to this embodiment, the diodes 902 and 904 are installed so as to allow current to flow in the direction from the connection terminal 104 toward the connection terminal 102 (which may be referred to as the discharge direction). Therefore, even if the switching units 230 of all the power storage modules 110 included in a specific block are turned off, the current can be maintained. On the other hand, once the switching units 230 of all the power storage modules 110 included in a specific block are turned off, subsequent charging becomes difficult.

[0152] Therefore, according to this embodiment, when charging the power storage system 900, the system control unit 140 first detects the voltage between the terminals of each block and checks for the presence of a block with a voltage between the terminals of 0. When a block with a voltage between the terminals of 0 is found, the system control unit 140 sends a signal for turning on the switching element of the switching unit 230 to one of the plurality of power storage modules 110 included in the block. The system control unit 140 may send a signal for turning on the switching element of the switching unit 230 to the power storage module 110 with the smallest voltage between the terminals among the plurality of power storage modules 110 included in the above-mentioned block. Then, the system control unit 140 starts charging the power storage system 900.

[0153] In this embodiment, the case where the diodes 902 and 904 are installed to allow current to flow in the discharge direction has been described. However, the power storage system 900 is not limited to this embodiment. In other embodiments, the diodes 902 and 904 may be Zener diodes. Thereby, even when the charging of all the power storage modules 110 included in a specific block is completed and all the power storage modules 110 included in the block are disconnected from the power storage system 900, in the power storage system 900, the charging of other blocks connected in series with the above specific block can be continued.

[0154] In this case, when discharging the power storage system 900, before starting the discharge, the system control unit 140 may detect the inter-terminal voltage of each group and check whether there is a group with an inter-terminal voltage of 0. Thereafter, a signal for turning on the switching element of the switching unit 230 may be transmitted to one of the plurality of power storage modules 110 included in the block with an inter-terminal voltage of 0.

[0155] Using FIGS. 10 to 17, other examples of the power storage module 110 will be described. Matters described for the power storage module 110 and its respective parts may be applied to other examples of the power storage module 110 and its respective parts within a technically non-contradictory range. Also, matters described for other examples of the power storage module 110 and its respective parts may be applied to the power storage module 110 and its respective parts. In the description of FIGS. 10 to 17, the description of matters described for the respective parts of the power storage module 110 may be omitted.

[0156] Figure 10 schematically shows an example of the system configuration of the power storage module 1010. In the present embodiment, the power storage module 1010 includes a positive electrode terminal 112, a negative electrode terminal 114, and a power storage unit 210. The power storage module 1010 may include a switching unit 230. The power storage module 1010 may include a protection unit 250. The power storage module 1010 may include a balance correction unit 260. In the present embodiment, the power storage module 1010 includes a current detection element 1020 and a module control unit 1040.

[0157] The power storage module 1010 may be an example of a control device and a control system. The module control unit 1040 may be an example of a control device. The switching unit 230 may be an example of an adjustment unit, a first current adjustment unit, and a second current adjustment unit.

[0158] In the present embodiment, the switching unit 230 adjusts the current flowing between the wiring 106 and the power storage unit 210. In one embodiment, the switching unit 230 electrically connects or disconnects the wiring 106 and the power storage unit 210. In other embodiments, the switching unit 230 increases or decreases the above current, for example, by changing the resistance value of the path between the wiring 106 and the power storage unit 210.

[0159] In the present embodiment, one end of the switching unit 230 is electrically connected to the wiring 106 via the positive electrode terminal 112 and the current detection element 1020. The other end of the switching unit 230 is electrically connected to the positive electrode terminal 212 of the power storage unit 210. Information indicating the voltage between the terminals of the switching unit 230 may be used as information indicating the difference between the potential of the wiring 106 or the voltage applied to the wiring 106 (sometimes simply referred to as the voltage of the wiring 106) and the potential of the terminal of the power storage unit 210 (for example, the positive electrode terminal 212) or the voltage applied to the terminal (sometimes simply referred to as the voltage of the power storage unit 210, the voltage of the terminal, etc.).

[0160] In one embodiment, the switching unit 230 adjusts, at least, the magnitude of the current flowing between the wiring 106 and the power storage unit 210 in the direction from the positive electrode terminal 212 of the power storage unit 210 to the positive electrode terminal 112 (which may be referred to as the discharge direction). In other embodiments, the switching unit 230 adjusts, at least, the magnitude of the current flowing between the wiring 106 and the power storage unit 210 in the direction from the positive electrode terminal 112 to the positive electrode terminal 212 of the power storage unit 210 (which may be referred to as the charging direction). In still other embodiments, the switching unit 230 adjusts the magnitudes of the current flowing in the discharge direction between the wiring 106 and the power storage unit 210 and the current flowing in the charging direction between the wiring 106 and the power storage unit 210.

[0161] In this embodiment, the power storage module 1010 is different from the power storage module 110 in that the power storage module 1010 includes a current detection element 1020. The power storage module 1010 is different from the power storage module 110 in that the power storage module 1010 includes a module control unit 1040 instead of the module control unit 240. With respect to the configuration other than the above differences, the power storage module 1010 may have the same characteristics as the corresponding configuration of the power storage module 110.

[0162] In this embodiment, the current detection element 1020 is used to obtain information indicating the current flowing between the wiring 106 and the power storage unit 210. Examples of the information indicating the current may include the presence or absence of the current, the magnitude of the current, and the direction of the current. In this embodiment, the power storage module 1010 obtains information regarding the current flowing between the wiring 106 and the power storage unit 210 by measuring the voltage across the terminals of the current detection element 1020.

[0163] In this embodiment, the current detection element 1020 is arranged between the positive terminal 112 and the switching unit 230. More specifically, one end of the current detection element 1020 is electrically connected to the switching unit 230. The other end of the current detection element 1020 is electrically connected to the wiring 106 via the positive terminal 112. Note that the current detection element 1020 may be arranged between the switching unit 230 and the positive terminal 212 of the power storage unit 210. Also, a part of the switching unit 230 or an element constituting the switching unit 230 may be used as the current detection element 1020.

[0164] The current detection element 1020 may be an element having an arbitrary resistance value, and its type is not particularly limited. For example, the current detection element 1020 has an appropriate resistance value according to the maximum allowable current of the power storage unit 210. Examples of the current detection element 1020 include a resistor and a Hall sensor. A passive element or an active element having an appropriate resistance value may be used as the above resistor.

[0165] In this embodiment, the module control unit 1040 is different from the module control unit 240 in that it detects the current flowing between the wiring 106 and the power storage unit 210. In this embodiment, the module control unit 1040 is different from the module control unit 240 in that it controls the operation of the switching unit 230 based on (i) the voltage or SOC of the power storage unit 210 and (ii) the current flowing between the wiring 106 and the power storage unit 210. The module control unit 1040 may control the operation of the switching unit 230 based on (i) the voltage or SOC of the power storage unit 210, (ii) the current flowing between the wiring 106 and the power storage unit 210, and (iii) the voltage between the terminals of the switching unit 230. Regarding the configuration other than the above differences, the module control unit 1040 may have the same characteristics as the corresponding configuration of the module control unit 240.

[0166] The method by which the module control unit 1040 detects the current flowing between the wiring 106 and the power storage unit 210 is not particularly limited. In the present embodiment, the module control unit 1040 acquires information indicating the voltage between the terminals of the current detection element 1020 disposed between the positive electrode terminal 112 and the positive electrode terminal 212, and based on this information, detects the current flowing between the wiring 106 and the power storage unit 210. Thereby, the module control unit 1040 can monitor the current flowing between the wiring 106 and the power storage unit 210. The module control unit 1040 may determine the magnitude of the current flowing between the wiring 106 and the power storage unit 210, or may determine the direction of the above current.

[0167] In one embodiment, when the switching unit 230 adjusts or controls at least the magnitude of the current flowing in the discharging direction between the wiring 106 and the power storage unit 210, the module control unit 1040 monitors or detects the current flowing in the charging direction between the wiring 106 and the power storage unit 210. When the switching unit 230 disconnects the electrical connection in the discharging direction between the wiring 106 and the power storage unit 210 (which may be referred to as "electrically disconnected in the discharging direction"), the module control unit 1040 may monitor or detect the current flowing between the wiring 106 and the power storage unit 210. In this case, the current detected by the module control unit 1040 is, as a result, the current flowing in the charging direction between the wiring 106 and the power storage unit 210.

[0168] In another embodiment, when the switching unit 230 adjusts or controls at least the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210, the module control unit 1040 monitors or detects the current flowing in the discharging direction between the wiring 106 and the power storage unit 210. When the switching unit 230 disconnects the electrical connection in the charging direction between the wiring 106 and the power storage unit 210 (which may be referred to as "electrically disconnected in the charging direction"), the module control unit 1040 may monitor or detect the current flowing between the wiring 106 and the power storage unit 210. In this case, the current detected by the module control unit 1040 is, as a result, the current flowing in the discharging direction between the wiring 106 and the power storage unit 210.

[0169] The method by which the module control unit 1040 controls the operation of the switching unit 230 is not particularly limited. As described above, the module control unit 1040 detects the current flowing between the wiring 106 and the power storage unit 210. The module control unit 1040 may control the operation of the switching unit 230 based on the information indicating the current flowing between the wiring 106 and the power storage unit 210. Thereby, when the power storage module 1010 is actively inserted and removed, the interlock of the switching unit 230 can be safely released.

[0170] Similar to the module control unit 240, the module control unit 1040 may acquire information indicating the voltage between the terminals of the switching unit 230. The module control unit 1040 may control the operation of the switching unit 230 based on the information indicating the voltage between the terminals of the switching unit 230. Thereby, the time required for the active insertion and removal of the power storage module 1010 is shortened.

[0171] Similar to the module control unit 240, the module control unit 1040 may acquire information obtained or generated by the protection unit 250 from the protection unit 250. For example, the module control unit 1040 acquires from the protection unit 250 information indicating that the overcharge protection function is enabled, information indicating that the overcharge protection function is not enabled, information indicating that the overdischarge protection function is enabled, information indicating that the overdischarge protection function is not enabled, and the like. The module control unit 1040 may control the operation of the switching unit 230 based on the information obtained or generated by the protection unit 250. Thereby, the switching unit 230 can be appropriately controlled according to the state of the power storage unit 210.

[0172] For example, when the voltage or SOC of the power storage unit 210 is smaller than or equal to the threshold value for over-discharge protection, the over-discharge protection function becomes effective. When the voltage or SOC of the power storage unit 210 is larger than or equal to the threshold value for over-discharge protection, the over-discharge protection function becomes ineffective. Also, for example, when the voltage or SOC of the power storage unit 210 is larger than or equal to the threshold value for over-charge protection, the over-charge protection function becomes effective. When the voltage or SOC of the power storage unit 210 is smaller than or equal to the threshold value for over-charge protection, the over-charge protection function becomes ineffective.

[0173] Similar to the module control unit 240, the module control unit 1040 may acquire information obtained or generated by the system control unit 140 from the system control unit 140. For example, the module control unit 1040 acquires information indicating the battery characteristics of the power storage unit 210 from the system control unit 140. The module control unit 1040 may control the operation of the switching unit 230 based on the information obtained or generated by the system control unit 140. Thereby, the switching unit 230 can be appropriately controlled according to the state of the power storage unit 210.

[0174] [Specific example of the procedure for controlling the operation of the switching unit 230] In one embodiment, the module control unit 1040 controls the operation of the switching unit 230 based on the charge state of the power storage unit 210. In other embodiments, the module control unit 1040 controls the operation of the switching unit 230 based on the voltage across the terminals of the switching unit 230. In still other embodiments, the module control unit 1040 controls the operation of the switching unit 230 based on the current flowing between the wiring 106 and the power storage unit 210. The module control unit 1040 may control the operation of the switching unit 230 based on at least one of the magnitude and direction of the above current.

[0175] More specifically, the module control unit 1040 controls the operation of the switching unit 230 based on (i) the voltage or SOC of the power storage unit 210 and (ii) the current flowing between the wiring 106 and the power storage unit 210. The module control unit 1040 may control the operation of the switching unit 230 based on (i) the voltage or SOC of the power storage unit 210, (ii) the current flowing between the wiring 106 and the power storage unit 210, and (iii) the voltage across the terminals of the switching unit 230.

[0176] For example, when the voltage or SOC of the power storage unit 210 satisfies a predetermined condition, the module control unit 1040 controls the switching unit 230 so that the switching unit 230 electrically connects the wiring 106 and the power storage unit 210. The battery characteristics of the power storage unit 210, the voltage or SOC of the power storage unit 210 may be an example of the battery characteristics of the power storage unit 210. The predetermined condition may be a condition using a predetermined numerical range or threshold value, or a condition using a numerical range or threshold value calculated according to a predetermined procedure. Thereby, for example, deterioration or damage of the power storage unit 210 due to overcharging or over-discharging can be prevented.

[0177] The predetermined condition may be a condition for protecting the power storage unit 210. Examples of the predetermined condition include (i) a condition indicating that the voltage or SOC of the power storage unit 210 is within a specific numerical range, (ii) a condition indicating that the voltage or SOC of the power storage unit 210 is greater than a specific threshold value or equal to or greater than a specific threshold value, (iii) a condition indicating that the voltage or SOC of the power storage unit 210 is less than a specific threshold value or equal to or less than a specific threshold value, (v) a condition combining these, and the like.

[0178] The condition indicating that the voltage or SOC of the power storage unit 210 is within a specific numerical range may be a condition indicating that at least one of the overvoltage protection function and the overdischarge protection function of the power storage module 1010 is not enabled. The condition indicating that the voltage or SOC of the power storage unit 210 is within a specific numerical range may be a condition indicating that the overvoltage protection function and the overdischarge protection function of the power storage module 1010 are not enabled. The condition indicating that the voltage or SOC of the power storage unit 210 is greater than a specific threshold value or equal to or greater than a specific threshold value may be a condition indicating that the overdischarge protection function of the power storage module 1010 is not enabled. The condition indicating that the voltage or SOC of the power storage unit 210 is less than a specific threshold value or equal to or less than a specific threshold value may be a condition indicating that the overcharge protection function of the power storage module 1010 is not enabled.

[0179] According to the present embodiment, when the inter-terminal voltage of the switching unit 230 satisfies a predetermined condition, the module control unit 1040 controls the switching unit 230 so that the switching unit 230 electrically connects the power storage unit 210 and the wiring 106. More specifically, when the difference between the voltage of the wiring 106 and the voltage of the power storage unit 210 is relatively large, the power storage unit 210 and the wiring 106 are electrically disconnected. On the other hand, when the above difference is relatively small, the power storage unit 210 and the wiring 106 are electrically connected. Thereby, rapid active insertion and extraction become possible.

[0180] The predetermined condition may be a condition for realizing rapid active insertion and extraction. Examples of the predetermined condition include (i) a condition indicating that the inter-terminal voltage of the switching unit 230 is within a specific numerical range, (ii) a condition indicating that the inter-terminal voltage of the switching unit 230 is greater than a specific threshold value or equal to or greater than a specific threshold value, (iii) a condition indicating that the inter-terminal voltage of the switching unit 230 is less than a specific threshold value or equal to or less than a specific threshold value, (v) a condition combining these, and the like.

[0181] (Specific example of the procedure for releasing the interlock of overdischarge protection) When the power storage system 100 is discharging with the power storage unit 210 of the power storage module 1010 electrically connected to the wiring 106 of the power storage system 100, for example, when the voltage or SOC of the power storage unit 210 becomes lower than the threshold for over-discharge protection, the protection unit 250 transmits a signal for activating the over-discharge protection function to the module control unit 1040. At this time, the current is flowing in the discharge direction between the wiring 106 and the power storage unit 210. In this case, the discharge direction may be an example of the first direction. Also, the charge direction may be an example of the second direction. Note that in the present embodiment, the discharge direction and the charge direction are opposite to each other.

[0182] When the voltage or SOC of the power storage unit 210 is lower than the threshold for over-discharge protection, it may be an example of a case where the conditions for protecting the power storage unit 210 are not satisfied. In other embodiments, the protection unit 250 may transmit a signal for activating the over-discharge protection function to the module control unit 1040 when the voltage or SOC of the power storage unit 210 is less than or equal to the threshold for over-discharge protection.

[0183] When the module control unit 1040 receives the above signal, it controls the switching unit 230 to electrically disconnect the wiring 106 from the power storage unit 210. If the power storage system 100 continues to discharge after the wiring 106 and the power storage unit 210 are electrically disconnected, a voltage difference will occur between the wiring 106 and the power storage unit 210.

[0184] After the discharge of the power storage system 100 ends and then the charging of the power storage system 100 starts, a voltage difference exists between the wiring 106 and the power storage unit 210. In this case, when the absolute value of the above voltage difference is greater than the threshold for realizing rapid active insertion / extraction, the module control unit 1040 determines that the inter-terminal voltage of the switching unit 230 does not satisfy the conditions for realizing rapid active insertion / extraction. As a result, the charging of the power storage system 100 proceeds with the power storage unit 210 of the power storage module 1010 and the wiring 106 of the power storage system 100 electrically disconnected.

[0185] On the one hand, (i) when the absolute value of the voltage difference at the start of charging of the power storage system 100 is smaller than or equal to the threshold value for realizing rapid active insertion and extraction, or (ii) when the charging of the power storage system 100 progresses and the absolute value of the voltage difference becomes smaller than or equal to the threshold value for realizing rapid active insertion and extraction, the module control unit 1040 controls the switching unit 230 to attempt to electrically connect the wiring 106 and the power storage unit 210. However, at this stage, the voltage or SOC of the power storage unit 210 is smaller than the threshold value for over-discharge protection. Therefore, the interlock mechanism of the module control unit 1040 is activated. As a result, the module control unit 1040 cannot control the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210.

[0186] In order for the module control unit 1040 to control the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210, it is necessary to release the above-mentioned interlock by some logic. The method for releasing the above-mentioned interlock is not particularly limited, but in the present embodiment, the module control unit 1040 determines whether to release the above-mentioned interlock based on the current flowing between the wiring 106 and the power storage unit 210 or information regarding the current, and controls the operation of the switching unit 230.

[0187] Here, as described in relation to FIG. 5, the switching unit 230 includes a transistor 520 that adjusts or controls the magnitude of the current flowing in the discharge direction between the wiring 106 and the power storage unit 210. Examples of the transistor 520 include Si-MOSFET, insulated gate bipolar transistor (IGBT), SiC-MOSFET, GaN-MOSFET, and the like.

[0188] When the rated voltage of the power storage unit 210 is relatively high, the transistor 520 is preferably a SiC-MOSFET. For example, when the maximum value of the rated voltage of the power storage unit 210 is 100 V or more, preferably 200 V or more, more preferably 300 V or more, still more preferably 500 V or more, still more preferably 800 V or more, and still more preferably 1000 V, a SiC-MOSFET is used as the transistor 520. Thereby, it is possible to sufficiently exhibit the advantages of the SiC-MOSFET, such as having excellent breakdown voltage characteristics and low loss. When the maximum value of the rated voltage of the power storage unit 210 is 300 V or more or 500 V or more, the effect of using a SiC-MOSFET as the transistor 520 can be remarkably manifested.

[0189] Also, a parasitic diode is formed between the source and drain of the transistor 520. The parasitic diode allows a current flowing in the charging direction between the wiring 106 and the power storage unit 210 to pass through. On the other hand, the parasitic diode suppresses the current from flowing in the discharging direction between the wiring 106 and the power storage unit 210 through the parasitic diode.

[0190] The transistor 520 may be an example of the first current adjustment unit or the second current adjustment unit. The parasitic diode of the transistor 520 may be an example of the first bypass unit or the second bypass unit. Note that the switching unit 230 may include a rectifier that has the same function as the parasitic diode of the transistor 520 and is connected in parallel with the transistor 520 between the wiring 106 and the power storage unit 210, separately from the parasitic diode of the transistor 520. Examples of the rectifier include (i) a rectifying element such as a diode, and (ii) a rectifying circuit composed of a plurality of elements.

[0191] As described above, according to this embodiment, the switching unit 230 includes (i) a transistor 520 that adjusts the current in the discharging direction, and (ii) a parasitic diode that is arranged in parallel with the transistor 520, allows the current in the charging direction to pass through, and does not allow the current in the discharging direction to pass through. Therefore, when the charging of the power storage system 100 further proceeds and the voltage of the wiring 106 becomes higher than the voltage of the positive electrode terminal 212 of the power storage unit 210, a current flows in the charging direction between the wiring 106 and the power storage unit 210 through the parasitic diode of the transistor 520.

[0192] When preventing deterioration or breakage of the power storage unit 210 due to over-discharge, the module control unit 1040 needs to prevent the current from flowing in the discharging direction, but does not necessarily need to prevent the current from flowing in the charging direction. Therefore, according to this embodiment, the module control unit 1040 monitors the current flowing between the wiring 106 and the power storage unit 210.

[0193] In one embodiment, the module control unit 1040 detects the current flowing in the charging direction between the wiring 106 and the power storage unit 210. In another embodiment, the module control unit 1040 may detect the current flowing between the wiring 106 and the power storage unit 210 when the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 in the discharging direction.

[0194] After the charging of the power storage system 100 is started and until the above current is detected, the module control unit 1040 maintains an interlock for over-discharge protection. On the other hand, when the above current is detected, the module control unit 1040 releases the interlock for over-discharge protection.

[0195] In one embodiment, the module control unit 1040 controls the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210. Generally, the on-resistance value of the transistor 520 is smaller than the resistance value of the parasitic diode. Therefore, according to this embodiment, the charge and discharge efficiency of the power storage unit 210 is improved.

[0196] When the above current is detected in a state where the above voltage difference does not satisfy the conditions for realizing rapid active insertion / extraction, the module control unit 1040 may control the switching unit 230 so that the switching unit 230 electrically connects the wiring 106 and the power storage unit 210 at least until the above voltage difference satisfies the conditions for realizing rapid active insertion / extraction. During the period when the above voltage difference satisfies the conditions for realizing rapid active insertion / extraction, the module control unit 1040 may control the switching unit 230 so that the switching unit 230 electrically connects the wiring 106 and the power storage unit 210.

[0197] In other embodiments, when the above current is detected, the module control unit 1040 may transmit a signal for resetting the over-discharge protection function to the protection unit 250. Then, when receiving the signal for resetting the over-discharge protection function, the protection unit 250 may control the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210.

[0198] After the wiring 106 and the power storage unit 210 are electrically connected and the charging of the power storage system 100 further proceeds, when the voltage or SOC of the power storage unit 210 becomes greater than the threshold value for over-discharge protection, the protection unit 250 may transmit a signal for resetting the over-discharge protection function to the module control unit 1040. When receiving the signal for resetting the over-discharge protection function, the module control unit 1040 may control the switching unit 230 so that the switching unit 230 electrically connects the power storage unit 210 and the wiring 106.

[0199] As described above, when it is determined to activate the over-discharge protection function, the module control unit 1040, for example, (i) electrically disconnects the wiring 106 and the power storage unit 210, or (ii) reduces the magnitude of the current that can flow in the discharge direction between the wiring 106 and the power storage unit 210. Thereby, when the over-discharge protection function is effective, the magnitude of the current that can flow in the discharge direction becomes smaller compared to the case where the over-discharge protection function is ineffective. On the other hand, when it is determined to release the interlock of the over-discharge protection (which may be referred to as invalidating the over-discharge protection function), the module control unit 1040, for example, (i) electrically connects the wiring 106 and the power storage unit 210, or (ii) increases the magnitude of the current that can flow in the discharge direction between the wiring 106 and the power storage unit 210.

[0200] The module control unit 1040 adjusts or controls the magnitude of the current flowing in the discharge direction between the wiring 106 and the power storage unit 210 by adjusting the resistance value or the current-carrying rate (which may be referred to as the duty ratio) of the switching unit 230. In one embodiment, when the switching unit 230 includes the transistor 520 and the transistor 520 is a field-effect transistor, the module control unit 1040 can adjust or control the magnitude of the current flowing in the discharge direction between the wiring 106 and the power storage unit 210 by adjusting the gate voltage (which may be referred to as the input voltage) of the transistor 520. The module control unit 1040 may adjust or control the magnitude of the current flowing in the discharge direction between the wiring 106 and the power storage unit 210 by controlling the operation of the element arranged in the circuit for adjusting the input voltage of the transistor 520.

[0201] In other embodiments, when the switching unit 230 includes the transistor 520 and the transistor 520 is a bipolar transistor, the module control unit 1040 can adjust or control the magnitude of the current flowing in the discharging direction between the wiring 106 and the power storage unit 210 by adjusting the base current of the transistor 520 (which may be referred to as the input current). The module control unit 1040 may adjust or control the magnitude of the current flowing in the discharging direction between the wiring 106 and the power storage unit 210 by controlling the operation of the elements arranged in the circuit for adjusting the input current of the transistor 520.

[0202] The resistance value or current-carrying rate of the switching unit 230 may be the same or different when the over-discharge protection function is enabled and when the over-discharge protection function is disabled. When the switching unit 230 has a switching element, the on-resistance of the switching element may be the same or different when the over-charge protection function is enabled and when the over-charge protection function is disabled. When the switching unit 230 has a variable resistor, the resistance value of the variable resistor may be the same or different when the over-charge protection function is enabled and when the over-charge protection function is disabled. When the over-discharge protection function is enabled, the module control unit 1040 may control the switching unit 230 such that the resistance value of the switching unit 230 becomes larger compared to the case where the over-discharge protection function is disabled. When the over-discharge protection function is enabled, the module control unit 1040 may control the switching unit 230 such that the current-carrying rate of the switching unit 230 becomes smaller compared to the case where the over-discharge protection function is disabled.

[0203] For the purpose of simplifying the description, in this embodiment, when it is determined to activate the over-discharge protection function, the module control unit 1040 electrically disconnects the wiring 106 and the power storage unit 210, and when it is determined to deactivate the over-discharge protection function, the module control unit 1040 electrically connects the wiring 106 and the power storage unit 210. Taking this embodiment as an example, the procedure for the module control unit 1040 to release the interlock of over-discharge protection has been described. However, those skilled in the art who have come into contact with the description of this specification can understand that when it is determined to activate the over-discharge protection function, the module control unit 1040 reduces the magnitude of the current that can flow in the discharge direction between the wiring 106 and the power storage unit 210, and when it is determined to deactivate the over-discharge protection function, the module control unit 1040 increases the magnitude of the current that can flow in the discharge direction between the wiring 106 and the power storage unit 210. In other embodiments, the module control unit 1040 can release the interlock of over-discharge protection by the same procedure as in this embodiment.

[0204] Specifically, when the over-discharge protection function is activated, in this embodiment, the series of operations for the module control unit 1040 to electrically disconnect the wiring 106 and the power storage unit 210 correspond to the series of operations for the module control unit 1040 to reduce the current that can flow between the power storage unit 210 and the wiring 106 in the other embodiments described above. Similarly, when the over-discharge protection function is deactivated, in this embodiment, the series of operations for the module control unit 1040 to electrically connect the wiring 106 and the power storage unit 210 correspond to the series of operations for the module control unit 1040 to increase the current that can flow between the power storage unit 210 and the wiring 106 in the other embodiments described above.

[0205] (Specific example of the procedure for releasing the interlock of overcharge protection) When the power storage system 100 is charging with the power storage unit 210 of the power storage module 1010 electrically connected to the wiring 106 of the power storage system 100, for example, when the voltage or SOC of the power storage unit 210 becomes greater than the threshold for overcharge protection, the protection unit 250 transmits a signal for activating the overcharge protection function to the module control unit 1040. At this time, the current is flowing in the charging direction between the wiring 106 and the power storage unit 210. In this case, the charging direction may be an example of the first direction. Also, the discharging direction may be an example of the second direction. Note that in the present embodiment, the discharging direction and the charging direction are opposite to each other.

[0206] When the voltage or SOC of the power storage unit 210 is greater than the threshold for overcharge protection, it may be an example of a case where the conditions for protecting the power storage unit 210 are not satisfied. In other embodiments, the protection unit 250 may transmit a signal for activating the overcharge protection function to the module control unit 1040 when the voltage or SOC of the power storage unit 210 is equal to or greater than the threshold for over-discharge protection.

[0207] When the module control unit 1040 receives the above signal, it controls the switching unit 230 to electrically disconnect the wiring 106 from the power storage unit 210. If the power storage system 100 continues to charge after the wiring 106 and the power storage unit 210 are electrically disconnected, a voltage difference will occur between the wiring 106 and the power storage unit 210.

[0208] After the charging of the power storage system 100 is completed, and then when the discharging of the power storage system 100 is started, a voltage difference exists between the wiring 106 and the power storage unit 210. In this case, when the absolute value of the above voltage difference is greater than the threshold for realizing rapid active insertion and removal, the module control unit 1040 determines that the voltage between the terminals of the switching unit 230 does not satisfy the conditions for realizing rapid active insertion and removal. As a result, the discharging of the power storage system 100 proceeds with the power storage unit 210 of the power storage module 1010 and the wiring 106 of the power storage system 100 being electrically disconnected.

[0209] On the one hand, (i) when the absolute value of the voltage difference at the start of discharging of the power storage system 100 is smaller than or equal to the threshold value for realizing rapid active insertion and extraction, or (ii) when the charging of the power storage system 100 progresses and the absolute value of the voltage difference becomes smaller than or equal to the threshold value for realizing rapid active insertion and extraction, the module control unit 1040 controls the switching unit 230 to attempt to electrically connect the wiring 106 and the power storage unit 210. However, at this stage, the voltage or SOC of the power storage unit 210 is greater than the threshold value for overcharge protection. Therefore, the interlock mechanism of the module control unit 1040 operates. As a result, the module control unit 1040 cannot control the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210.

[0210] In order for the module control unit 1040 to control the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210, it is necessary to release the above interlock by some logic. The method for releasing the above interlock is not particularly limited, but in the present embodiment, the module control unit 1040 determines whether to release the above interlock based on the current flowing between the wiring 106 and the power storage unit 210 or information regarding the current, and controls the operation of the switching unit 230.

[0211] Here, as described in relation to FIG. 5, the switching unit 230 includes a transistor 510 that adjusts or controls the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210. Examples of the transistor 510 include a Si-MOSFET, an insulated gate bipolar transistor (IGBT), a SiC-MOSFET, a GaN-MOSFET, and the like.

[0212] When the rated voltage of the power storage unit 210 is relatively high, the transistor 510 is preferably a SiC-MOSFET. For example, when the maximum value of the rated voltage of the power storage unit 210 is 100V or more, preferably 200V or more, more preferably 300V or more, further preferably 500V or more, further preferably 800V or more, and further preferably 1000V, a SiC-MOSFET is used as the transistor 510. This makes it possible to fully utilize the advantages of the SiC-MOSFET, that is, the excellent withstand voltage characteristics and the small loss. When the maximum value of the rated voltage of the power storage unit 210 is 300V or more or 500V or more, the effect of using a SiC-MOSFET as the transistor 510 can be significantly achieved.

[0213] In addition, a parasitic diode is formed between the source and drain of transistor 510. The parasitic diode passes a current flowing in the discharging direction between wiring 106 and power storage unit 210. On the other hand, the parasitic diode prevents a current from flowing in the charging direction between wiring 106 and power storage unit 210 via the parasitic diode.

[0214] The transistor 510 may be an example of a first current adjustment unit or a second current adjustment unit. The parasitic diode of the transistor 510 may be an example of a first bypass unit or a second bypass unit. Note that the switching unit 230 may include, in addition to the parasitic diode of the transistor 510, a rectifier that has a function similar to that of the parasitic diode and is connected in parallel to the transistor 510 between the wiring 106 and the power storage unit 210. Examples of the rectifier include (i) a rectifier element such as a diode, and (ii) a rectifier circuit composed of a plurality of elements.

[0215] As described above, according to the present embodiment, the switching unit 230 includes (i) a transistor 510 that adjusts the current in the charging direction, and (ii) a parasitic diode that is arranged in parallel with the transistor 510, allows the current in the discharging direction to pass through, and does not allow the current in the charging direction to pass through. Therefore, when the discharge of the power storage system 100 further progresses and the voltage of the wiring 106 becomes smaller than the voltage of the positive electrode terminal 212 of the power storage unit 210, a current flows in the discharging direction between the wiring 106 and the power storage unit 210 through the parasitic diode of the transistor 510.

[0216] When preventing deterioration or damage of the power storage unit 210 due to overcharging, the module control unit 1040 needs to prevent current from flowing in the charging direction, but does not necessarily need to prevent current from flowing in the discharging direction. Therefore, according to the present embodiment, the module control unit 1040 monitors the current flowing between the wiring 106 and the power storage unit 210.

[0217] In one embodiment, the module control unit 1040 detects the current flowing in the discharging direction between the wiring 106 and the power storage unit 210. In another embodiment, the module control unit 1040 may detect the current flowing between the wiring 106 and the power storage unit 210 when the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 in the charging direction.

[0218] After the discharge of the power storage system 100 is started and until the above current is detected, the module control unit 1040 maintains the interlock for overcharge protection. On the other hand, when the above current is detected, the module control unit 1040 releases the interlock for overcharge protection.

[0219] In one embodiment, the module control unit 1040 controls the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210. Generally, the value of the on-resistance of the transistor 510 is smaller than the resistance value of the parasitic diode. Therefore, according to the present embodiment, the charge and discharge efficiency of the power storage unit 210 is improved.

[0220] When the above-mentioned current is detected in a state where the above-mentioned voltage difference does not satisfy the conditions for realizing rapid active insertion and extraction, the module control unit 1040 may control the switching unit 230 so that the switching unit 230 electrically connects the wiring 106 and the power storage unit 210 at least until the above-mentioned voltage difference satisfies the conditions for realizing rapid active insertion and extraction. During the period when the above-mentioned voltage difference satisfies the conditions for realizing rapid active insertion and extraction, the module control unit 1040 may control the switching unit 230 so that the switching unit 230 electrically connects the wiring 106 and the power storage unit 210.

[0221] In another embodiment, when the above-mentioned current is detected, the module control unit 1040 may send a signal for resetting the overcharge protection function to the protection unit 250. Then, when receiving the signal for resetting the overcharge protection function, the protection unit 250 may control the switching unit 230 to electrically connect the wiring 106 and the power storage unit 210.

[0222] After the wiring 106 and the power storage unit 210 are electrically connected, when the discharge of the power storage system 100 further proceeds, the voltage or SOC of the power storage unit 210 becomes smaller than the threshold value for overcharge protection. When the voltage or SOC of the power storage unit 210 becomes smaller than the threshold value for overcharge protection, the protection unit 250 may send a signal for resetting the overcharge protection function to the module control unit 1040. When receiving the signal for resetting the overcharge protection function, the module control unit 1040 may control the switching unit 230 so that the switching unit 230 electrically connects the power storage unit 210 and the wiring 106.

[0223] Note that, as described above, when it is determined to activate the overcharge protection function, the module control unit 1040, for example, (i) electrically disconnects the wiring 106 and the power storage unit 210, or (ii) reduces the magnitude of the current that can flow in the charging direction between the wiring 106 and the power storage unit 210. Thereby, when the overcharge protection function is effective, the magnitude of the current that can flow in the charging direction becomes smaller compared to the case where the overcharge protection function is ineffective. On the other hand, when it is determined to release the interlock of overcharge protection (which may be referred to as invalidating the overcharge protection function), the module control unit 1040, for example, (i) electrically connects the wiring 106 and the power storage unit 210, or (ii) increases the magnitude of the current that can flow in the charging direction between the wiring 106 and the power storage unit 210.

[0224] The module control unit 1040 adjusts or controls the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210 by adjusting the resistance value or the current-carrying rate (which may be referred to as the duty ratio) of the switching unit 230. In one embodiment, when the switching unit 230 includes a transistor 510 and the transistor 510 is a field effect transistor, the module control unit 1040 can adjust or control the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210 by adjusting the gate voltage (which may be referred to as the input voltage) of the transistor 510. The module control unit 1040 may adjust or control the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210 by controlling the operation of the element arranged in the circuit for adjusting the input voltage of the transistor 510.

[0225] In other embodiments, when the switching unit 230 includes the transistor 510 and the transistor 510 is a bipolar transistor, the module control unit 1040 can adjust or control the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210 by adjusting the base current of the transistor 510 (which may be referred to as the input current). The module control unit 1040 may adjust or control the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210 by controlling the operation of the elements arranged in the circuit for adjusting the input current of the transistor 510.

[0226] The resistance value or current-carrying rate of the switching unit 230 may be the same or different when the overcharge protection function is effective and when the overcharge protection function is ineffective. When the switching unit 230 has a switching element, the on-resistance of the switching element may be the same or different when the overcharge protection function is effective and when the overcharge protection function is ineffective. When the switching unit 230 has a variable resistor, the resistance value of the variable resistor may be the same or different when the overcharge protection function is effective and when the overcharge protection function is ineffective. When the overcharge protection function is effective, the module control unit 1040 may control the switching unit 230 such that the resistance value of the switching unit 230 becomes larger compared to the case where the overcharge protection function is ineffective. When the overcharge protection function is effective, the module control unit 1040 may control the switching unit 230 such that the current-carrying rate of the switching unit 230 becomes smaller compared to the case where the overcharge protection function is ineffective.

[0227] For the purpose of simplifying the description, in this embodiment, when it is determined to activate the overcharge protection function, the module control unit 1040 electrically disconnects the wiring 106 and the power storage unit 210. When it is determined to deactivate the overcharge protection function, the module control unit 1040 electrically connects the wiring 106 and the power storage unit 210. Taking this embodiment as an example, the procedure for the module control unit 1040 to release the overcharge protection interlock has been described. However, those skilled in the art who have come into contact with the description of this specification can understand that when it is determined to activate the overcharge protection function, the module control unit 1040 reduces the magnitude of the current that can flow in the charging direction between the wiring 106 and the power storage unit 210. When it is determined to deactivate the overcharge protection function, in other embodiments where the module control unit 1040 increases the magnitude of the current that can flow in the charging direction between the wiring 106 and the power storage unit 210, the module control unit 1040 can release the overcharge protection interlock by the same procedure as in this embodiment.

[0228] Specifically, when the overcharge protection function is activated, in this embodiment, the series of operations for the module control unit 1040 to electrically disconnect the wiring 106 and the power storage unit 210 correspond to the series of operations for the module control unit 1040 to reduce the current that can flow between the power storage unit 210 and the wiring 106 in the other embodiments described above. Similarly, when the overcharge protection function is deactivated, in this embodiment, the series of operations for the module control unit 1040 to electrically connect the wiring 106 and the power storage unit 210 correspond to the series of operations for the module control unit 1040 to increase the current that can flow between the power storage unit 210 and the wiring 106 in the other embodiments described above.

[0229] As described above, according to this embodiment, the module control unit 1040 can achieve both the active plugging and unplugging function and the protection function of the power storage unit 210 without significantly reducing the charge and discharge efficiency of the power storage module 1010.

[0230] As described in relation to FIG. 1, the power storage module that constitutes part of the power supply of a small-scale system such as a home appliance product has a small number of power storage cells connected in series, and its rated voltage is also about 3.5 to 4.5 V. Therefore, when mounting the power storage module on the power supply or removing the power storage module from the power supply while the system is operating, it may be required to strictly manage the voltage of the power storage module to be actively inserted and removed and the voltage of other power storage modules that make up the power supply. Depending on the specifications of the power storage module, the allowable value of the voltage difference between the power storage module to be actively inserted and removed and other power storage modules that make up the power supply may be managed to be less than 1 V.

[0231] On the other hand, in recent years, the power storage module has been increasing in size. For example, in small to medium-sized electric vehicles such as passenger cars, power storage modules with a rated voltage of about 300 to 400 V are used. Also, in large electric vehicles such as electric buses, power storage modules with a rated voltage of about 500 to 800 V are increasingly being used. As the rated voltage of the power storage module increases, the allowable value of the voltage difference between the power storage module to be actively inserted and removed and other power storage modules that make up the power supply also increases. For example, even if the voltage difference between one power storage module that makes up the power supply and other power storage modules that make up the power supply exceeds 1 V, it may be possible to actively insert and remove the one power storage module.

[0232] Depending on the resistance or impedance of the power storage module targeted for active insertion / removal, when the rated voltage of the power storage module targeted for active insertion / removal is 100 V or more, the voltage difference between the power storage module targeted for active insertion / removal and other power storage modules constituting the power supply may be 30 V or less, may be 10 V or less, may be 5 V or less, may be 3 V or less, may be 2 V or less, or may be 1 V or less. The voltage difference between the power storage module targeted for active insertion / removal and other power storage modules constituting the power supply may be 1 / 5 or less of the rated voltage of the power storage module targeted for active insertion / removal, may be 1 / 10 or less, may be 1 / 20 or less, may be 1 / 30 or less, may be 1 / 50 or less, may be 1 / 100 or less, may be 1 / 200 or less, may be 1 / 300 or less, may be 1 / 500 or less, or may be 1 / 1000 or less.

[0233] In this embodiment, the case where the current detection element 1020 and the switching unit 230 are arranged between the positive electrode terminal 112 of the power storage module 1010 and the positive electrode terminal 212 of the power storage unit 210, and the positive electrode terminal 212 of the power storage unit 210 is electrically connected to the wiring 106 via the switching unit 230 has been described. However, the arrangement of the current detection element 1020 and the switching unit 230 is not limited to this embodiment. In other embodiments, the current detection element 1020 and the switching unit 230 are arranged between the negative electrode terminal 114 of the power storage module 1010 and the negative electrode terminal 214 of the power storage unit 210, and the negative electrode terminal 214 of the power storage unit 210 is electrically connected to the wiring 106 via the switching unit 230.

[0234] FIG. 11 schematically shows an example of the system configuration of the module control unit 1040. In the present embodiment, the module control unit 1040 includes a determination unit 310, a reception unit 320, and a signal generation unit 330. The module control unit 1040 may further include a module information acquisition unit 340, a module information storage unit 350, and a module information transmission unit 360. In the present embodiment, the module control unit 1040 includes a current monitoring unit 1120. In the present embodiment, the current monitoring unit 1120 includes a current detection unit 1122 and a direction determination unit 1124. The signal generation unit 330 may be an example of an operation control unit.

[0235] In the present embodiment, the module control unit 1040 is different from the module control unit 240 in that the module control unit 1040 includes a current monitoring unit 1120. Regarding the configuration other than the above differences, the module control unit 1040 may have the same characteristics as the corresponding configuration of the module control unit 240.

[0236] In the present embodiment, the current monitoring unit 1120 monitors the current flowing between the wiring 106 of the power storage system 100 and the power storage unit 210 of the power storage module 1010. For example, the current monitoring unit 1120 monitors the current flowing between the positive electrode terminal 112 and the positive electrode terminal 212 of the power storage module 1010.

[0237] In the present embodiment, the current detection unit 1122 detects the current flowing between the wiring 106 of the power storage system 100 and the power storage unit 210 of the power storage module 1010. The current detection unit 1122 may determine the magnitude of the above current. The current detection unit 1122 may be configured by any analog circuit or any digital circuit.

[0238] In the present embodiment, the direction determination unit 1124 determines the direction of the current flowing between the wiring 106 of the power storage system 100 and the power storage unit 210 of the power storage module 1010. The direction determination unit 1124 may be configured by any analog circuit or any digital circuit.

[0239] FIG. 12 schematically shows an example of the circuit configuration of the module control unit 1040. FIG. 12 schematically shows an example of the circuit configuration of the switching unit 230. FIG. 12 shows an example of the switching unit 230 and an example of the module control unit 1040 together with the positive electrode terminal 112, the negative electrode terminal 114, the power storage unit 210, the protection unit 250, and the current detection element 1020.

[0240] [Specific Example of the Circuit of the Switching Unit 230] In the present embodiment, one end of the transistor 510 is electrically connected to the wiring 106, and the other end is electrically connected to the power storage unit 210. The transistor 510 is connected in series with the transistor 520 and the parasitic diode 844 between the wiring 106 and the power storage unit 210. In the present embodiment, the transistor 510 adjusts the magnitude of the current flowing in the charging direction between the wiring 106 and the power storage unit 210.

[0241] In the present embodiment, one end of the transistor 520 is electrically connected to the wiring 106, and the other end is electrically connected to the power storage unit 210. The transistor 520 is connected in series with the transistor 510 and the parasitic diode 842 between the wiring 106 and the power storage unit 210. In the present embodiment, the transistor 520 adjusts the magnitude of the current flowing in the discharging direction between the wiring 106 and the power storage unit 210.

[0242] One end of the parasitic diode 842 is electrically connected to the wiring 106, and the other end is electrically connected to the power storage unit 210. The parasitic diode 842 is connected in parallel with the transistor 510 between the wiring 106 and the power storage unit 210. The parasitic diode 842 is connected in series with the transistor 520 and the parasitic diode 844 between the wiring 106 and the power storage unit 210.

[0243] The parasitic diode 842 allows the current flowing in the discharging direction between the wiring 106 and the power storage unit 210 to pass through. On the other hand, the parasitic diode 842 suppresses the current from flowing in the charging direction between the wiring 106 and the power storage unit 210 through the parasitic diode 842.

[0244] The parasitic diode 844 has one end electrically connected to the wiring 106 and the other end electrically connected to the power storage unit 210. The parasitic diode 844 is connected in parallel with the transistor 520 between the wiring 106 and the power storage unit 210. The parasitic diode 844 is connected in series with the transistor 510 and the parasitic diode 842 between the wiring 106 and the power storage unit 210.

[0245] The parasitic diode 842 allows a current flowing in the charging direction between the wiring 106 and the power storage unit 210 to pass through. On the other hand, the parasitic diode 844 suppresses the current from flowing in the discharging direction between the wiring 106 and the power storage unit 210 through the parasitic diode 844.

[0246] The transistor 510 may be an example of one of the first current adjustment unit and the second current adjustment unit. The transistor 520 may be an example of the other of the first current adjustment unit and the second current adjustment unit. The parasitic diode 842 may be an example of one of the first bypass unit and the second bypass unit. The parasitic diode 844 may be an example of the other of the first bypass unit and the second bypass unit. The discharging direction may be an example of one of the first direction and the second direction. The charging direction may be an example of the other of the first direction and the second direction.

[0247] [Specific Example of the Circuit of the Module Control Unit 1040] In the present embodiment, the module control unit 1040 includes a determination unit 310, a signal generation unit 330, and a current monitoring unit 1120. The determination unit 310 may be an example of a first determination unit, a second determination unit, and a third determination unit.

[0248] In the present embodiment, the signal generation unit 330 includes an OR circuit 1260, an AND circuit 1272, an AND circuit 1274, an OR circuit 1282, and an OR circuit 1284. Further, in the present embodiment, a resistor having an appropriate resistance value is arranged as the current detection element 1020 between the positive terminal 112 and the switching unit 230. The resistance value of the current detection element 1020 is determined so that, for example, the current monitoring unit 1120 can surely determine the direction of the current flowing between the wiring 106 and the power storage unit 210.

[0249] In this embodiment, the determination unit 310 determines whether the voltage between the terminals of the switching unit 230 is within a predetermined range. The determination unit 310 transmits a signal indicating the determination result to the signal generation unit 330. The determination unit 310 may be configured by any analog circuit or any digital circuit. The determination unit 310 may include a window comparator. The window comparator can be realized, for example, by using two comparators.

[0250] In this embodiment, the determination unit 310 has two input terminals. The voltage at one end of the switching unit 230 (for example, the end on the positive electrode terminal 112 side) is input to one input terminal of the determination unit 310 (shown as the - terminal in the figure). The voltage at the other end of the switching unit 230 (for example, the end on the power storage unit 210 side) is input to the other input terminal of the determination unit 310 (shown as the + terminal in the figure).

[0251] In this embodiment, the determination unit 310 has two output terminals. As a signal indicating the determination result, the determination unit 310 outputs a signal indicating that the voltage between the terminals of the switching unit 230 is smaller than the first threshold value from one output terminal (shown as the L terminal in the figure). For example, when the voltage between the terminals of the switching unit 230 is smaller than the first threshold value, the determination unit 310 outputs H logic from the L terminal. On the other hand, when the voltage between the terminals of the switching unit 230 is equal to or greater than the first threshold value, the determination unit 310 outputs L logic from the L terminal.

[0252] Also, as a signal indicating the determination result, the determination unit 310 outputs a signal indicating that the voltage between the terminals of the switching unit 230 is greater than the second threshold value from the other output terminal (shown as the H terminal in the figure). In this embodiment, a value larger than the absolute value of the first threshold value is set as the absolute value of the second threshold value. For example, when the voltage between the terminals of the switching unit 230 is greater than the second threshold value, the determination unit 310 outputs H logic from the H terminal. On the other hand, when the voltage between the terminals of the switching unit 230 is equal to or less than the second threshold value, the determination unit 310 outputs L logic from the H terminal.

[0253] In one embodiment, the determination unit 310 can determine, for example, whether the voltage or SOC of the power storage unit 210 meets the first condition. Examples of the first condition include: (i) a condition indicating that the voltage or SOC of the power storage unit is outside a predetermined first numerical range; (ii) a condition indicating that the voltage or SOC of the power storage unit is greater than a predetermined first threshold; (iii) a condition indicating that the voltage or SOC of the power storage unit is equal to or greater than the first threshold. The first condition is, for example, a condition indicating that the power storage unit 210 is overcharged.

[0254] In another embodiment, the determination unit 310 can determine, for example, whether the voltage or SOC of the power storage unit 210 meets the second condition. Examples of the second condition include: (i) a condition indicating that the voltage or SOC of the power storage unit is outside a predetermined second numerical range; (ii) a condition indicating that the voltage or SOC of the power storage unit is less than a predetermined second threshold; (iii) a condition indicating that the voltage or SOC of the power storage unit is equal to or less than the second threshold. Note that the second condition may be different from the first condition. The second condition is, for example, a condition indicating that the power storage unit 210 is overdischarged.

[0255] In still another embodiment, the determination unit 310 can determine, for example, whether the inter-terminal voltage of the switching unit 230 meets the third condition. Examples of the third condition include: (i) a condition indicating that the inter-terminal voltage of the switching unit 230 is within a predetermined third numerical range; (ii) a condition indicating that the inter-terminal voltage of the switching unit 230 is less than a predetermined third threshold; (iii) a condition indicating that the inter-terminal voltage of the switching unit 230 is equal to or less than the third threshold.

[0256] In still other embodiments, the determination unit 310 can, for example, determine whether the voltage between the terminals of the switching unit 230 meets the fourth condition. Examples of the fourth condition include: (i) a condition indicating that the voltage between the terminals of the switching unit 230 is outside a predetermined fourth numerical range; (ii) a condition indicating that the voltage between the terminals of the switching unit 230 is greater than a predetermined fourth threshold value; (iii) a condition indicating that the voltage between the terminals of the switching unit 230 is equal to or greater than the fourth threshold value. The fourth numerical range may be the same as the third numerical range. The upper limit value of the fourth numerical range may be greater than the upper limit value of the third numerical range. The fourth threshold value may be the same as the third threshold value. The fourth threshold value may be greater than the third threshold value.

[0257] In this embodiment, the current monitoring unit 1120 may include a comparator. The current monitoring unit 1120 has, for example, two input terminals and one output terminal. The voltage at one end of the current detection element 1020 (for example, the end on the positive terminal 112 side) is input to one input terminal of the current monitoring unit 1120 (shown as the + terminal in the figure). The voltage at the other end of the current detection element 1020 (for example, the end on the switching unit 230 side) is input to the other input terminal of the current monitoring unit 1120 (shown as the - terminal in the figure).

[0258] For example, when the voltage input to the + terminal is greater than the voltage input to the - terminal, the current monitoring unit 1120 outputs H logic from the output terminal. On the other hand, when the voltage input to the + terminal is less than the voltage input to the - terminal, the current monitoring unit 1120 outputs L logic from the output terminal. Also, when the voltage input to the + terminal is equal to the voltage input to the - terminal, or when the two can be regarded as equal, the current monitoring unit 1120 does not output a signal from the output terminal.

[0259] In this embodiment, when at least one of the transistor 510 and the transistor 520 electrically disconnects the wiring 106 and the power storage unit 210, the current monitoring unit 1120 detects the current flowing between the wiring 106 and the power storage unit 210. In one embodiment, when the overcharge protection function is activated, the current monitoring unit 1120 detects the current flowing in the discharge direction between the wiring 106 and the power storage unit 210. In another embodiment, when the overdischarge protection function is activated, the current monitoring unit 1120 detects the current flowing in the charging direction between the wiring 106 and the power storage unit 210.

[0260] In this embodiment, the signal generation unit 330 may also function as the reception unit 320. For example, the signal generation unit 330 receives a signal 86 from the protection unit 250 to activate the overdischarge protection function. Also, the signal generation unit 330 receives a signal 88 from the protection unit 250 to activate the overcharge protection function. The signal generation unit 330 receives information regarding the voltage between the terminals of the switching unit 230 from the determination unit 310. The signal generation unit 330 receives information regarding the current between the wiring 106 and the power storage unit 210 from the current monitoring unit 1120.

[0261] In this embodiment, based on (i) the voltage or SOC of the power storage unit 210 and (ii) the detection result of the current monitoring unit 1120, the signal generation unit 330 can control the operation of at least one of the transistor 510 and the transistor 520. Based on (i) the voltage or SOC of the power storage unit 210, (ii) the detection result of the current monitoring unit 1120, and (iii) the determination result of the determination unit 310, the signal generation unit 330 can control the operation of at least one of the transistor 510 and the transistor 520. The signal generation unit 330 may control at least one of the transistor 510 and the transistor 520 by outputting a signal for controlling the operation of at least one of the transistor 510 and the transistor 520 to the transistor to be controlled by the signal.

[0262] In the present embodiment, when the determination unit 310 determines that the inter-terminal voltage of the switching unit 230 meets the fourth condition, the signal generation unit 330 may output a signal for causing at least one of the transistors 510 and 520 to perform an operation of electrically disconnecting the wiring 106 and the power storage unit 210, or an operation of reducing the current flowing between the wiring 106 and the power storage unit 210. Thereby, the determination unit 310 can also be used as an overcurrent protection function of the power storage unit 210.

[0263] In the present embodiment, the OR circuit 1260 has two input terminals and one output terminal. The output from the H terminal of the determination unit 310 is input to one input terminal of the OR circuit 1260. The output from the L terminal of the determination unit 310 is input to the other input terminal of the OR circuit 1260.

[0264] The OR circuit 1260 outputs the logical sum of two inputs. For example, when the inter-terminal voltage of the switching unit 230 falls within a specific numerical range, the OR circuit 1260 outputs an L logic. On the other hand, when the inter-terminal voltage of the switching unit 230 falls outside the specific numerical range, the OR circuit 1260 outputs an H logic. For example, as an example of the case where the switching unit 230 meets the above fourth condition, when the inter-terminal voltage of the switching unit 230 is greater than a specific value, an H logic is output from the H terminal of the determination unit 310. In this case, the OR circuit 1260 outputs an H logic.

[0265] In the present embodiment, the AND circuit 1272 has two input terminals and one output terminal. A signal obtained by inverting the output of the OR circuit 1260 is input to one input terminal of the AND circuit 1272. A signal obtained by inverting the signal 88 for enabling the overcharge protection function is input to the other input terminal of the AND circuit 1272.

[0266] The AND circuit 1272 outputs the logical product of two inputs. For example, when the voltage between the terminals of the switching unit 230 falls within a specific numerical range (specifically, when the absolute value of the difference between the voltage of the wiring 106 and the voltage of the power storage unit 210 is less than or equal to a specific threshold value), and when the voltage or SOC of the power storage unit 210 is less than the threshold value for overcharge protection, the AND circuit 1272 outputs H logic. On the other hand, in other cases, the AND circuit 1272 outputs L logic.

[0267] In the present embodiment, the AND circuit 1274 has two input terminals and one output terminal. A signal obtained by inverting the output of the OR circuit 1260 is input to one input terminal of the AND circuit 1274. A signal obtained by inverting a signal 86 for activating the overdischarge protection function is input to the other input terminal of the AND circuit 1274.

[0268] The AND circuit 1274 outputs the logical product of two inputs. For example, when the voltage between the terminals of the switching unit 230 falls within a specific numerical range (specifically, when the absolute value of the difference between the voltage of the wiring 106 and the voltage of the power storage unit 210 is less than or equal to a specific threshold value), and when the voltage or SOC of the power storage unit 210 is greater than the threshold value for overdischarge protection, the AND circuit 1274 outputs H logic. On the other hand, in other cases, the AND circuit 1274 outputs L logic.

[0269] In the present embodiment, the OR circuit 1282 has two input terminals and one output terminal. A signal obtained by inverting the output of the current monitoring unit 1120 is input to one input terminal of the OR circuit 1282. The output of the AND circuit 1272 is input to the other input terminal of the OR circuit 1282.

[0270] The OR circuit 1282 outputs the logical sum of two inputs. For example, when the output of the OR circuit 1282 is at H logic, the transistor 510 turns on, and when the output of the OR circuit 1282 is at L logic, the transistor 510 turns off. In one embodiment, when current is flowing in the discharging direction between the wiring 106 and the power storage unit 210, the OR circuit 1282 outputs H logic. In other embodiments, when the voltage between the terminals of the switching unit 230 falls within a specific numerical range and the voltage or SOC of the power storage unit 210 is less than the threshold for overcharge protection, the OR circuit 1282 outputs H logic.

[0271] In the present embodiment, the OR circuit 1284 has two input terminals and one output terminal. The output of the current monitoring unit 1120 is input to one input terminal of the OR circuit 1284. The output of the AND circuit 1274 is input to the other input terminal of the OR circuit 1284.

[0272] The OR circuit 1284 outputs the logical sum of two inputs. For example, when the output of the OR circuit 1284 is at H logic, the transistor 520 turns on, and when the output of the OR circuit 1284 is at L logic, the transistor 520 turns off. In one embodiment, when current is flowing in the charging direction between the wiring 106 and the power storage unit 210, the OR circuit 1284 outputs H logic. In other embodiments, when the voltage between the terminals of the switching unit 230 falls within a specific numerical range and the voltage or SOC of the power storage unit 210 is less than the threshold for overcharge protection, the OR circuit 1284 outputs H logic.

[0273] [Specific example of the operation of the signal generation unit 330] In one embodiment, when the determination unit 310 determines that the voltage or SOC of the power storage unit 210 meets the first condition, the signal generation unit 330 outputs, for example, a signal to cause the transistor 510 to perform an operation of electrically disconnecting the wiring 106 and the power storage unit 210, or an operation of reducing the current flowing in the charging direction between the wiring 106 and the power storage unit 210. Depending on the content of the first condition, the signal generation unit 330 may also output a signal to the transistor 520.

[0274] In another embodiment, when the determination unit 310 determines that the voltage or SOC of the power storage unit 210 meets the second condition, the signal generation unit 330 outputs, for example, to the transistor 520 a signal for executing an operation of electrically disconnecting the wiring 106 and the power storage unit 210, or an operation of reducing the current flowing in the discharge direction between the wiring 106 and the power storage unit 210. Depending on the content of the second condition, the signal generation unit 330 may output a signal to the transistor 510.

[0275] In still another embodiment, when the determination unit 310 determines that the voltage between the terminals of the switching unit 230 meets the third condition, the signal generation unit 330 outputs, regardless of whether the voltage or SOC of the power storage unit 210 meets the first and second conditions, to the transistor 510 and the transistor 520 a signal for executing an operation of electrically connecting the wiring 106 and the power storage unit 210, or an operation of increasing the current flowing between the wiring 106 and the power storage unit 210. On the other hand, when the determination unit 310 determines that the voltage between the terminals of the switching unit 230 does not meet the third condition, the signal generation unit 330 may output a signal according to the detection result of the current monitoring unit 1120. For example, the signal generation unit 330 outputs a signal as follows.

[0276] [(a) When the determination unit 310 determines that the voltage between the terminals of the switching unit 230 does not meet the third condition, and (b) the current monitoring unit 1120 detects (i) the current flowing in the discharge direction between the wiring 106 and the power storage unit 210 when the overcharge protection function is activated, or (ii) the current flowing between the wiring 106 and the power storage unit 210 when the transistor 510 electrically disconnects the wiring 106 and the power storage unit] In this case, the signal generation unit 330 outputs, regardless of whether the voltage or SOC of the power storage unit 210 meets the first condition, to the transistor 510 a signal for executing an operation of electrically connecting the wiring 106 and the power storage unit 210, or an operation of increasing the current flowing between the wiring 106 and the power storage unit 210.

[0277] [When the determination unit 310 determines that the voltage between the terminals of the switching unit 230 does not meet the third condition, and (c) the current monitoring unit 1120 detects (i) the current flowing in the charging direction between the wiring 106 and the power storage unit 210 when the over-discharge protection function is enabled, or (ii) the current flowing between the wiring 106 and the power storage unit 210 when the transistor 520 electrically disconnects the wiring 106 and the power storage unit]] In this case, regardless of whether the voltage or SOC of the power storage unit 210 meets the second condition, the signal generation unit 330 outputs a signal for causing the transistor 520 to perform an operation of electrically connecting the wiring 106 and the power storage unit 210 or an operation of increasing the current flowing between the wiring 106 and the power storage unit 210.

[0278] In still another embodiment, the module control unit 1040 can suppress the power storage unit 210 from deteriorating or being damaged due to overcurrent. As described above, as an example of the case where the switching unit 230 meets the above fourth condition, when the voltage between the terminals of the switching unit 230 is greater than a specific value, the OR circuit 1260 outputs H logic.

[0279] Therefore, when a current is flowing in the discharging direction between the wiring 106 and the power storage unit 210 and the voltage between the terminals of the switching unit 230 is greater than a specific value, L logic is output from the OR circuit 1282. As a result, the transistor 510 turns off. Similarly, when a current is flowing in the charging direction between the wiring 106 and the power storage unit 210 and the voltage between the terminals of the switching unit 230 is greater than a specific value, L logic is output from the OR circuit 1284. As a result, the transistor 520 turns off.

[0280] According to this embodiment, the constant flow of current through parasitic diode 842 and parasitic diode 844 is suppressed. As a result, it can be considered that the voltage between the terminals of switching unit 230 is proportional to the current flowing through transistors 510 and 520. Therefore, by appropriately setting the resistance value of current detection element 1020 or connecting a resistor having an appropriate resistance value in series with current detection element 1020 between wiring 106 and power storage unit 210, determination unit 310 and signal generation unit 330 can be used as an overcurrent protection circuit.

[0281] FIG. 13 schematically shows an example of the circuit configuration of module control unit 1040. Module control unit 1040 disclosed in FIG. 13 is different from module control unit 1040 described in relation to FIG. 12 in that a resistor 1310 is provided between current detection element 1020 and 120. Regarding the configuration other than the above differences, module control unit 1040 disclosed in FIG. 13 may have the same features as the corresponding configuration of module control unit 1040 described in relation to FIG. 12.

[0282] As described above, by appropriately setting the resistance value of resistor 1310, determination unit 310 and signal generation unit 330 can be used as an overcurrent protection circuit. The resistance value of resistor 1310 is determined so that, for example, determination unit 310 can surely determine whether or not the value of the load current falls within a predetermined numerical range. Further, resistor 1310 may be used as a current detection element instead of current detection element 1020. In this case, power storage module 1010 may not include current detection element 1020.

[0283] FIG. 14 schematically shows an example of the system configuration of power storage module 2010. In this embodiment, power storage module 2010 includes a positive terminal 112, a negative terminal 114, a power storage unit 210, a switching unit 230, and a suppression unit 2000. Power storage module 2010 may include a module control unit 2040. Power storage module 2010 may include a protection unit 250. Power storage module 2010 may include a balance correction unit 260.

[0284] The power storage module 2010 may be an example of a power storage device. The module control unit 2040 may be a series of switching control units.

[0285] In the present embodiment, the switching unit 230 is disposed between the power storage unit 210 and the wiring 106, and switches the electrical connection relationship between the wiring 106 and the power storage unit 210. The switching unit 230 switches the electrical connection relationship between the wiring 106 and the power storage unit 210, for example, according to whether the voltage between the terminals of the switching unit 230 satisfies a predetermined condition. The switching unit 230 electrically connects or disconnects the wiring 106 and the power storage unit 210 according to whether the voltage between the terminals of the switching unit 230 satisfies a predetermined condition. The switching unit 230, according to whether the voltage between the terminals of the switching unit 230 satisfies a predetermined condition, (i) electrically connects the wiring 106 and the power storage unit 210 when the voltage between the terminals of the switching unit 230 satisfies a predetermined condition, and (ii) electrically disconnects the wiring and the power storage unit 210 when the voltage between the terminals of the switching unit 230 does not satisfy a predetermined condition.

[0286] Specifically, the module control unit 2040 controls whether the switching unit 230 electrically connects or disconnects the wiring 106 and the power storage unit 210 according to whether the voltage between the terminals of the switching unit 230 satisfies a predetermined condition. More specifically, the module control unit 2040 (i) electrically connects the wiring 106 and the power storage unit 210 when the voltage between the terminals of the switching unit 230 satisfies a predetermined condition, and (ii) controls the switching unit 230 so that the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 when the voltage between the terminals of the switching unit 230 does not satisfy the predetermined condition. For example, the module control unit 240 controls the switching unit 230 so that the switching unit 230 electrically connects the wiring 106 and the power storage unit 210 when the absolute value of the voltage between the terminals of the switching unit 230 is within a predetermined range, and the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 when the voltage between the terminals of the switching unit 230 is outside the predetermined range.

[0287] The switching unit 230 may include a switching element. Examples of the switching element include a relay. Examples of the switching element also include semiconductor switches such as thyristors and transistors. The semiconductor switch may be, for example, a SiC semiconductor switch. The thyristor may be a bidirectional thyristor (sometimes referred to as a triac). The transistor may be a semiconductor transistor. The semiconductor transistor may be a bipolar transistor or a field-effect transistor. The field-effect transistor may be a MOSFET.

[0288] The suppression unit 2000 is connected in parallel with the switching unit 230 between the wiring 106 and the power storage unit 210. The suppression unit 2000 suppresses the back electromotive force generated in the wiring 106 when the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 while the power storage unit 210 is storing electrical energy.

[0289] When the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 during charging of the power storage unit 210, the current flowing through the wiring 106 rapidly decreases. As a result, a large back electromotive force is generated in the wiring 106. For example, when the inductance included in the wiring 106 is L and the current flowing through the wiring 106 is I, a back electromotive force of L·dI / dt is generated in the wiring 106 when the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210.

[0290] Therefore, when the power storage module 2010 does not have the suppression unit 2000, an excessive voltage is applied to the switching unit 230, and elements such as the switching element included in the switching unit 230 may fail. For example, when the switching element included in the switching unit 230 is a relay, arc discharge may occur between the electrical contacts of the relay due to the back electromotive force generated in the wiring 106. When the switching unit 230 is a semiconductor switch, SOA breakdown may occur because the semiconductor switch operates outside the SOA (Safety Operation Area). On the other hand, when the power storage module 2010 includes the suppression unit 2000, it is possible to suppress the back electromotive force generated in the wiring 106 when the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210. Thereby, it is possible to suppress the failure of elements such as the switching element included in the switching unit 230.

[0291] In the present embodiment, the maximum value of the rated voltage of the power storage unit 210 may be 100V or more. The maximum value of the rated voltage of the power storage unit 210 may be 200V or more. The maximum value of the rated voltage of the power storage unit 210 may be 300V or more. The maximum value of the rated voltage of the power storage unit 210 may be 500V or more. The maximum value of the rated voltage of the power storage unit 210 may be 800V or more. The maximum value of the rated voltage of the power storage unit 210 may be 1000V. The maximum value of the rated voltage of the power storage unit 210 may be 1500V or more. The rated voltage of the power storage unit 210 may also be 48V or more.

[0292] FIG. 15 schematically shows an example of the internal configuration of the suppression unit 2000 and the switching unit 230. In the present embodiment, the switching unit 230 includes a switching element 232 disposed between the wiring 106 and the power storage unit 210. In the present embodiment, the switching element 232 has a relay.

[0293] The suppression unit 2000 includes a capacitive element 2002. The capacitive element 2002 suppresses the back electromotive force generated in the wiring 106 when the switching unit 230 electrically disconnects the wiring 106 and the power storage unit 210 during the storage of electrical energy in the power storage unit 210. The capacitive element 2002 desirably has a capacitance that can make the back electromotive force less than a predetermined value.

[0294] The capacitive element 2002 is a capacitor or the like. The capacitance of the capacitive element 2002 may be 0.1 μF or greater than 0.1 μF. The capacitance of the capacitive element 2002 may be 1 μF or greater than 1 μF. The capacitance of the capacitive element 2002 may be 2.2 μF or greater than 2.2 μF. The capacitance of the capacitive element 2002 may be 4.7 μF or greater than 4.7 μF. The capacitance of the capacitive element 2002 may be 10 μF or greater than 10 μF. The capacitance of the capacitive element 2002 may be 22 μF or greater than 22 μF. The capacitance of the capacitive element 2002 may be 47 μF or greater than 47 μF.

[0295] As described above, when the relay included in the switching element 232 electrically disconnects the wiring 106 and the power storage unit 210 during the charging of the power storage unit 210, the current flowing through the wiring 106 rapidly decreases, generating a large back electromotive force in the wiring 106. As a result, when the power storage module 2010 does not have the suppression unit 2000, even if the electrical contact of the relay included in the switching element 232 is open, arc discharge may occur between the electrical contacts of the relay due to the large back electromotive force generated in the wiring 106. Therefore, the relay included in the switching element 232 may be destroyed by the heat due to the arc discharge.

[0296] In contrast, according to the power storage module 2010, the capacitive element 2002 is connected in parallel to the switching unit 230. Therefore, the back electromotive force generated in the wiring 106 can be absorbed by the capacitive element 2002.

[0297] In this embodiment, the suppression unit 2000 does not have a substantial resistive element connected in series with the capacitive element 2002. Generally, when a capacitive element is connected in parallel with the switching element 232, if the switching element 232 is turned on with a charge accumulated in the capacitive element, an excessive current will flow through the switching element 232, and the switching element 232 may be damaged, for example, by welding of the electrical contacts of the switching element 232. Therefore, usually, the capacitive element 2002 is not connected in parallel with the switching element 232. However, according to this embodiment, the module control unit 2040 causes the switching element 232 to electrically connect the wiring 106 and the power storage unit 210 on the condition that, for example, the absolute value of the voltage between the terminals of the switching element 232 is within a predetermined range. Therefore, the switching element 232 is not turned on in a state where a large amount of charge is accumulated in the capacitive element 2002. Therefore, even if the suppression unit 2000 adopts a circuit configuration that does not have a substantial resistive element connected in series with the capacitive element 2002, the possibility of the switching element 232 being damaged can be significantly reduced.

[0298] FIG. 16 schematically shows another example of the internal configuration of the suppression unit 2000. In this example, the switching unit 230 includes a switching element 232 disposed between the wiring 106 and the power storage unit 210. In this embodiment, the switching element 232 has a relay.

[0299] The suppression unit 2000 includes a capacitive element 2002 and a resistor 2004. The resistor 2004 is connected in series with the capacitive element 2002. The resistor 2004 is an example of a current amount limiting unit that limits the amount of current flowing through the capacitive element 2002.

[0300] Since the suppression unit 2000 includes a resistor 2004 connected in series to the capacitive element 2002, it is possible to limit the current that flows when the switching element 232 turns on and shorts the capacitive element 2002. As an example, the resistance value of the resistor 2004 is 50 mΩ, and when the module control unit 2040 turns on the switching element 232 when the voltage across the terminals of the switching element 232 is 1.5 V or less, the current can be limited to 30 A. Thus, even when it is necessary to provide a resistor 2004 for limiting the current, in the present embodiment, since the module control unit 2040 turns on the switching element 232 when the voltage across the terminals of the switching element 232 is within a predetermined range, it becomes possible to make the resistance value of the resistor 2004 connected in series to the capacitive element 2002 extremely small.

[0301] As an example, the resistance value of the resistor 2004 may be 1 Ω or less than 1 Ω. The resistance value of the resistor 2004 may be 100 mΩ or less than 100 mΩ. The resistance value of the resistor 2004 may be 50 mΩ or less than 50 mΩ. The resistance value of the resistor 2004 may be 20 mΩ or less than 20 mΩ.

[0302] When adopting a form in which a resistor 2004 is connected in series to the capacitive element 2002, when the switching element 232 is turned off during charging of the power storage unit 210, if the resistance value of the resistor 2004 is R, a voltage of IxR can be generated. If this voltage exceeds the minimum arc discharge voltage of the switching element 232, the switching element 232 may fail.

[0303] Therefore, it is preferable that the value obtained by multiplying the rated current value I of the power storage unit 210 by the resistance value of the resistor 2004 is less than the minimum arc voltage value of the switching element 232. The resistance value of the resistor 2004 may be less than 100 / I.

[0304] Thus, according to this embodiment, the resistance value of the resistor 2004 connected in series to the capacitive element 2002 can be made extremely low. As a mere comparison, in some cases, a configuration in which a circuit with a capacitor and a resistor connected in series is connected in parallel to a switch is adopted as a surge absorber (also called a surge killer, etc.). Generally, a resistor with a relatively high resistance value is used for a surge absorber. When a resistor with a low resistance value is used in the circuit configuration of a surge absorber, a large current will flow when the switch is short-circuited. Therefore, it is normal to use a resistor with a high resistance value. In contrast, according to this embodiment, since the switching element 232 is turned on when the voltage between the terminals of the switching element 232 is within a predetermined range by the module control unit 2040, the resistance value of the resistor 2004 can be made extremely low. Furthermore, since the resistance value of the resistor 2004 can be made extremely low, when the switching element 232 is turned off during charging of the power storage unit 210, it becomes easy to design so as not to exceed the arc discharge voltage of the switching element 232.

[0305] In general, a capacitor with a relatively small capacitance is used for a surge absorber. In particular, in a high-voltage system, it is normal to use a capacitor with a small capacitance for a surge absorber. If the capacitance of the capacitor in the surge absorber is increased, a large current will flow when the switch is short-circuited. Therefore, it is normal to use a capacitor with a small capacitance within an applicable range. On the other hand, according to the present embodiment, when the voltage between the terminals of the switching element 232 is within a predetermined range by the module control unit 2040, the switching element 232 is turned on. Therefore, even if a capacitive element 2002 with a large capacitance is used, as long as the charge accumulated in the capacitive element 2002 is discharged to a certain extent and the magnitude of the voltage between the terminals of the switching element 232 does not decrease, the switching element 232 will not turn on. Therefore, it becomes possible to use a capacitive element 2002 with a relatively large capacitance. As a result, in a high-voltage system, it becomes possible to absorb the high back electromotive force generated in the wiring 106 when the switching element 232 is turned off during charging of the power storage unit 210.

[0306] FIG. 17 schematically shows an example of the internal configuration of the module control unit 2040. The module control unit 2040 includes an operational amplifier 2041, an operational amplifier 2042, a reference voltage circuit 2043, a reference voltage circuit 2044, and an AND circuit 2046. The operational amplifier 2041, the operational amplifier 2042, the reference voltage circuit 2043, and the reference voltage circuit 2044 constitute a window comparator.

[0307] One end of the switching unit 230 is connected to the negative electrode of the reference voltage circuit 2043 and the positive electrode of the reference voltage circuit 2044. The positive electrode of the reference voltage circuit 2043 is connected to the non-inverting input terminal of the operational amplifier 2041. The inverting input terminal of the operational amplifier 2041 is connected to the other end of the switching unit 230 of the power storage unit 210 and also to the non-inverting input terminal of the operational amplifier 2042. Therefore, the other end of the switching unit 230 is also connected to the non-inverting input terminal of the operational amplifier 2042. The negative electrode of the reference voltage circuit 2044 is connected to the inverting input terminal of the operational amplifier 2042.

[0308] Assuming that the reference voltages generated by the reference voltage circuits 2043 and 2044 are V, when the inter-terminal voltage of the switching unit 230 is within the range of -V to +V, the signal 2050 output by the operational amplifiers 2041 and 2042 becomes the H level, and when the inter-terminal voltage of the switching unit 230 is outside the range of -V to +V, the signal 2050 output by the operational amplifiers 2041 and 2042 becomes the L level.

[0309] As an example, the reference voltages generated by the reference voltage circuits 2043 and 2044 are 1.5V. The reference voltage may be 3V or lower than 3V. The reference voltage may be 2V or lower than 2V. The reference voltage may be 100mV or lower than 100mV. The reference voltage may be 10mV or lower than 10mV. The reference voltage may be 1mV or lower than 1mV.

[0310] The AND circuit 2046 has two input terminals and one output terminal. The signal 2050 from the output terminals of the operational amplifier 2041 and the operational amplifier 2042 is input to one of the input terminals of the AND circuit 2046. The signal 2090 output from the protection unit 250 is input to the other input terminal of the AND circuit 2046. The signal 2090 is a signal for enabling one of the over-discharge protection (UVP) function and the over-charge protection (OVP) function. When enabling one of the over-discharge protection (UVP) function and the over-charge protection (OVP) function, the protection unit 250 sets the output signal 2090 to the H level, and when not enabling either the over-discharge protection (UVP) function or the over-charge protection (OVP) function, the protection unit 250 sets the output signal 2090 to the L level.

[0311] The output terminal of the AND circuit 2046 outputs the logical product of the signals input to the two input terminals. As a result, the output of the AND circuit 2046 becomes the H logic when the inter-terminal voltage of the switching unit 230 is within the range of -V to +V with the voltages of the reference voltage circuits 2043 and 2044 being V, and neither the UVP function nor the OVP function is enabled, and becomes the L logic in other cases.

[0312] FIG. 18 is a logic value table showing the operation of the switching unit 230. The switching unit 230 operates according to the output of the AND circuit 2046. Specifically, when the output of the AND circuit 2046 is at the H logic level, the switching unit 230 performs an on operation to electrically connect the wiring 106 and the power storage unit 210. When the output of the AND circuit 2046 is at the L logic level, the switching unit 230 performs an off operation to electrically disconnect the wiring 106 and the power storage unit 210.

[0313] Therefore, the on operation of the switching unit 230 is performed only when the magnitude of the voltage between the terminals of the switching unit 230 is equal to or less than a predetermined value (when the first column of the truth table is "1") and neither the UVP function nor the OVP function is enabled (when the second column of the truth table is "0"), and an off operation is performed in other cases.

[0314] As described above, according to the present embodiment, when the switching unit 230 is turned off during charging of the power storage unit 210, it is possible to suppress the influence such as the destruction of the element included in the switching unit 230 due to the back electromotive force generated by the inductance of the wiring 106. Therefore, it becomes easy to use a mechanical switching element such as a relay as the switching unit 230. As a result, the cost is reduced. Further, since the mechanical switching element generally has a low on-resistance, it can also contribute to energy saving. Even when a semiconductor switch is used for the switching unit 230, it becomes possible to use a semiconductor switch with a low SOA.

[0315] The suppression unit 2000 described in relation to FIGS. 14 to 17 can be applied in parallel to the switching unit 230, the switching unit 630, and the switching unit 730 described in relation to other embodiments. At least a part of the configuration of the suppression unit 2000 described in relation to FIGS. 14 to 17 can be applied to the module control unit 240 and the module control unit 1040.

[0316] As described above, the present invention has been described using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiments. Also, within a technically consistent range, the matters described for a specific embodiment can be applied to other embodiments. It is clear from the description of the claims, etc. that forms with such changes or improvements can also be included in the technical scope of the present invention.

[0317] It should be noted that the execution order of each process such as operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, the specification, and the drawings is not explicitly stated as "earlier" or "preceding", etc., and can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flows in the claims, the specification, and the drawings, even if they are described for convenience using "first," "next," etc., it does not mean that it is essential to implement them in this order.

Description of Reference Numerals

[0318] 12 Load device, 14 Charging device, 52 Signal, 54 Signal, 82 Signal, 86 Signal, 88 Signal, 100 Energy storage system, 102 Connection terminal, 104 Connection terminal, 106 Wiring, 110 Energy storage module, 112 Positive terminal, 114 Negative terminal, 120 Energy storage module, 122 Positive terminal, 124 Negative terminal, 140 System control unit, 210 Energy storage unit, 212 Positive terminal, 214 Negative terminal, 222 Energy storage cell, 224 Energy storage cell, 230 Switching unit, 232 Switching element, 240 Module control unit, 250 Protection unit, 260 Balance correction unit, 310 Judgment unit, 320 Receiver, 330 Signal generation unit, 340 Module information acquisition unit, 350 Module information storage unit, 360 Module information transmission unit, 410 State management unit, 420 Module selection unit, 430 Signal generation unit, 510 Transistor, 512 Resistor, 514 Resistor, 516 Diode, 520 Transistor, 522 Resistor, 524 Resistor, 526 Diode, 530 Transistor, 532 Resistor, 540 Transistor, 542 Resistor, 552 Resistor, 554 Resistor, 560 Transistor, 570 Capacitor, 572 Resistor, 580 Transistor, 592 Switch, 594 Switch, 630 Switching unit, 632 Relay, 710 Energy storage module, 730 Switching unit, 842 Parasitic diode, 844 Parasitic diode, 852 Logic circuit, 854 Logic circuit, 900 Energy storage system, 902 Diode, 904 Diode, 1010 Energy storage module, 1020 Current detection element, 1040 Module control unit, 1120 Current monitoring unit, 1122 Current detection unit, 1124 Direction determination unit, 1260 OR circuit, 1272 AND circuit, 1274 AND circuit, 1282 OR circuit, 1284 OR circuit, 1310 Resistor, 2000 Suppression unit, 2002 Capacitance element, 2004 Resistor, 2010 Energy storage module, 2040 Module control unit, 2041 Operational amplifier, 2042 Operational amplifier, 2043 Reference voltage circuit, 2044 Reference voltage circuit, 2046 AND circuit, 2050 Signal, 2090 Signal

Claims

1. A switching unit disposed between a power storage unit of a power storage device configured to be connectable in parallel with another power supply device and a wiring for electrically connecting the power storage device and the other power supply device, the switching unit switching an electrical connection relationship between the wiring and the power storage unit according to whether a voltage between terminals of the switching unit satisfies a predetermined condition; A capacitive element connected in parallel with the switching unit between the wiring and the power storage unit; A power storage device comprising the above.

2. A current limiting unit connected in series with the capacitive element and limiting the amount of current flowing through the capacitive element; The power storage device according to claim 1, further comprising the above.

3. The current limiting unit has a resistance; The power storage device according to claim 2.

4. A resistance connected in series with the capacitive element; The power storage device according to claim 1, further comprising the above.

5. The switching unit has a relay disposed between the wiring and the power storage unit, and A value obtained by multiplying a resistance value of the resistance by a rated current value of the power storage unit is less than a minimum arc voltage value of the relay; The power storage device according to claim 3 or 4.

6. A switching control unit that controls whether the switching unit electrically connects or disconnects the wiring and the power storage unit according to whether a voltage between terminals of the switching unit satisfies a predetermined condition; The power storage device according to claim 3 or 4, further comprising the above.

7. The switching control unit controls the switching unit such that (i) when a voltage between terminals of the switching unit satisfies a predetermined condition, the switching unit electrically connects the wiring and the power storage unit, and (ii) when the voltage between terminals of the switching unit does not satisfy the predetermined condition, the switching unit electrically disconnects the wiring and the power storage unit; The power storage device according to claim 6.

8. The capacitive element suppresses a back electromotive force generated in the wiring when the switching unit electrically disconnects the wiring and the power storage unit while the power storage unit is storing electrical energy; The power storage device according to any one of claims 1 to 4.

9. The switching unit has a relay disposed between the wiring and the power storage unit; The power storage device according to any one of claims 1 to 4.

10. The capacitance of the capacitive element is greater than 0.1 μF; The power storage device according to any one of claims 1 to 4.

11. A power storage system in which a plurality of power storage devices according to any one of claims 1 to 4 are connected in parallel.

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