Power storage monitoring system

Abstract

To provide a technique for easily preventing continuation of a state in which a voltage of a battery cell is an overvoltage.SOLUTION: A power storage monitoring system 1 includes a power storage unit 3 having a configuration in which a plurality of battery cells 10 are connected in series, a charging switch unit 5 that cuts off a charging current supplied from a power supply unit 2 to the power storage unit 3, a discharge unit 20 that performs an individual discharge operation of selectively discharging some of the plurality of battery cells 10, a first control unit 31 that causes the discharge unit 20 to perform the individual discharge operation to adjust a voltage of each battery cell 10, and a second control unit 33 provided separately from the first control unit 31. The discharge unit 20 performs a full discharge operation of discharging all the battery cells 10. When it is determined that the voltage of any battery cell 10 has become overvoltage, the second control unit 33 controls the charging switch unit 5 to be in the OFF state and causes the discharge unit 20 to perform the full discharge operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power storage monitoring system. [Background technology]

[0002] Patent Document 1 discloses a charging device. This charging device includes a DC power supply connected across multiple batteries connected in series, and multiple charging control circuits connected in parallel to each battery. Each charging control circuit turns on a switch element when the terminal voltage of each battery reaches a safe charging voltage, and turns off the switch element when the terminal voltage of each battery drops below the optimal charging voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-191574 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration of Patent Document 1, if the charge control circuit stops operating normally, there is a risk that charging will continue even if the terminal voltage of each battery exceeds the safe charging voltage.

[0005] An object of the present disclosure is to provide a technology that can easily prevent a battery cell from continuing to have an overvoltage state. [Means for solving the problem]

[0006] The electricity storage monitoring system of the present disclosure includes: a power storage unit configured by connecting a plurality of battery cells in series; a charging switch unit that cuts off a charging current supplied from a power supply unit to the power storage unit; a discharge unit that performs an individual discharge operation to selectively discharge some of the plurality of battery cells; a first control unit that controls the discharge unit to perform the individual discharge operation to adjust the voltage of each of the battery cells; a second control unit provided separately from the first control unit, the discharge unit performs a full discharge operation to discharge all of the battery cells, When the second control unit determines that the voltage of any of the battery cells has become an overvoltage, the second control unit controls the charging switch unit to an OFF state and causes the discharging unit to perform the full discharging operation. [Effects of the Invention]

[0007] The technology according to the present disclosure makes it easy to prevent the battery cell voltage from continuing to be in an overvoltage state. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram of the electricity storage monitoring system of the first embodiment. [Figure 2] FIG. 2 is an explanatory diagram conceptually showing the charging operation of the first embodiment. [Figure 3] FIG. 3 is an explanatory diagram conceptually showing the full discharge operation of the first embodiment. [Figure 4] FIG. 4 is a timing chart showing the voltage of each battery cell, the on / off state of the charge switch section, and the execution state of the full discharge operation when the voltage of the battery cell becomes an overvoltage in the first embodiment. [Figure 5] FIG. 5 is a configuration diagram of the electricity storage monitoring system of the second embodiment. [Figure 6] FIG. 6 is a configuration diagram of the electricity storage monitoring system of the third embodiment. [Figure 7] FIG. 7 is a timing chart showing the voltage of each battery cell, the on / off state of the charge switch section, and the execution state of the full discharge operation when the voltage of the battery cell becomes an overvoltage in the third embodiment. [Figure 8] FIG. 8 is a configuration diagram of a power storage monitoring system according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] In the following, embodiments according to the present disclosure are listed and illustrated.

[0010] [1] A power storage unit configured by connecting a plurality of battery cells in series; a charging switch unit that cuts off a charging current supplied from a power supply unit to the power storage unit; a discharge unit that performs an individual discharge operation to selectively discharge some of the plurality of battery cells; a first control unit that controls the discharge unit to perform the individual discharge operation to adjust the voltage of each of the battery cells; a second control unit provided separately from the first control unit, the discharge unit performs a full discharge operation to discharge all of the battery cells, When it is determined that the voltage of any of the battery cells has become an overvoltage, the second control unit controls the charging switch unit to an off state and causes the discharging unit to perform the full discharging operation. Energy storage monitoring system.

[0011] With this configuration, the first control unit can adjust the voltage of each battery cell. Even if the first control unit does not operate normally and the voltage of any battery cell becomes an overvoltage, the second control unit controls the charging switch unit to the off state to stop charging of the power storage unit. Moreover, the second control unit causes the discharge unit to perform a full discharge operation, thereby discharging all battery cells. Therefore, with this configuration, it is easy to prevent the battery cell voltage from remaining in an overvoltage state.

[0012] [2] The discharge unit has individual discharge units provided individually corresponding to each of the battery cells, Each individual discharge unit is connected in parallel to the corresponding battery cell, and has a configuration in which a discharge switch unit and a resistor unit are connected in series, and discharges the corresponding battery cell when the discharge switch unit is turned on; the first control unit controls the discharge switch unit of each of the individual discharge units individually to cause the discharge units to perform the individual discharge operation; The second control unit controls the discharge switch units of all the individual discharge units to an on state, thereby causing the discharge units to perform the full discharge operation. The power storage monitoring system according to [1].

[0013] According to this configuration, the individual discharge units that perform the individual discharge operations can be used to perform the full discharge operation, which simplifies the configuration of the discharge units.

[0014] [3] The discharge unit is a first discharge portion; a second discharge section provided separately from the first discharge section, the first discharge unit performs the individual discharge operation, The second discharge unit performs the full discharge operation, the first control unit controls the first discharge unit to cause the discharge unit to perform the individual discharge operation; The second control unit controls the second discharge unit to cause the discharge unit to perform the full discharge operation. The power storage monitoring system according to [1].

[0015] With this configuration, even if the first discharge unit does not operate normally and the voltage of any battery cell becomes an overvoltage, the second control unit can discharge all battery cells by controlling the second discharge unit.

[0016] [4] The first discharge unit includes an individual discharge unit provided individually corresponding to each of the battery cells, Each of the individual discharge units is connected in parallel to the corresponding battery cell, and has a configuration in which a first discharge switch unit and a first resistor unit are connected in series, and discharges the corresponding battery cell when the first discharge switch unit is in an on state; the first control unit controls the first discharge switch unit of each of the individual discharge units individually to cause the discharge units to perform the individual discharge operation; the second discharge unit is connected in parallel to the power storage unit, has a configuration in which a second discharge switch unit and a second resistor unit are connected in series, and discharges the power storage unit when the second discharge switch unit is in an on state; The second control unit controls the second discharge switch unit to an on state, thereby causing the discharge unit to perform the full discharge operation. The electricity storage monitoring system according to [3].

[0017] According to this configuration, the second discharge section is provided separately from the first discharge section that performs the individual discharge operation, and yet the configuration of the second discharge section can be simplified.

[0018] [5] After causing the discharge unit to perform the full discharge operation, the second control unit stops the full discharge operation by the discharge unit when the voltages of all the battery cells become equal to or lower than a discharge stop voltage. The power storage monitoring system according to any one of [1] to [4].

[0019] This configuration can prevent the voltage of each battery cell from dropping too low.

[0020] [6] The discharge stop voltage is set to a value smaller than the upper limit voltage of the battery cell. The electricity storage monitoring system according to [5].

[0021] According to this configuration, the voltage of each battery cell can be reduced below the upper limit voltage by the full discharge operation, while preventing the voltage of each battery cell from decreasing too much.

[0022] [7] An overvoltage detection circuit is provided corresponding to each of the battery cells, each of the overvoltage detection circuits outputs an OFF signal when the voltage of the battery cell corresponding to the overvoltage detection circuit is equal to or lower than a threshold, and outputs an ON signal when the voltage of the battery cell corresponding to the overvoltage detection circuit exceeds the threshold; The second control unit has an OR circuit that outputs an ON signal to all of the discharge switch units when an ON signal is output from at least one of the overvoltage detection circuits, and a latch circuit that maintains a state in which an OFF signal is output to the charge switch units when an ON signal is output from the OR circuit. The power storage monitoring system according to [2].

[0023] According to this configuration, after detecting that the voltage of any battery cell has exceeded the threshold, it is possible to quickly discharge all battery cells and stop charging.

[0024] [8] The OR circuit outputs an OFF signal to all of the discharge switch units when an OFF signal is output from all of the overvoltage detection circuits; the second control unit has a threshold setting circuit that sets the threshold, The threshold setting circuit sets a charging stop voltage as the threshold when all of the overvoltage detection circuits are outputting an OFF signal, and changes the threshold to a discharging stop voltage that is lower than the charging stop voltage when an ON signal is output from at least one of the overvoltage detection circuits. The electricity storage monitoring system according to [7].

[0025] According to this configuration, when an ON signal is output from at least one overvoltage detection circuit, the threshold setting circuit changes the threshold to a discharge stop voltage that is lower than the charge stop voltage. Therefore, the power storage monitoring system can continue discharging the battery cells even if the voltage of all battery cells drops below the charge stop voltage as a result of discharging all battery cells after the voltage of any battery cell exceeds the charge stop voltage. Furthermore, when the voltage of all battery cells drops below the discharge stop voltage, the power storage monitoring system stops all discharge operations by the discharge unit, thereby preventing the voltage of each battery cell from dropping too low.

[0026] [9] An overvoltage detection circuit is provided corresponding to each of the battery cells, each of the overvoltage detection circuits outputs an OFF signal when the voltage of the battery cell corresponding to the overvoltage detection circuit is equal to or lower than a threshold, and outputs an ON signal when the voltage of the battery cell corresponding to the overvoltage detection circuit exceeds the threshold; The second control unit has an OR circuit that outputs an ON signal to the second discharge switch unit when an ON signal is output from at least one of the overvoltage detection circuits, and a latch circuit that maintains a state in which an OFF signal is output to the charge switch unit when an ON signal is output from the OR circuit. The power storage monitoring system according to [4].

[0027] According to this configuration, after detecting that the voltage of any battery cell has exceeded the threshold, it is possible to quickly discharge all battery cells and stop charging.

[0028]

[10] The OR circuit outputs an OFF signal to all of the second discharge switch units when an OFF signal is output from all of the overvoltage detection circuits; the second control unit has a threshold setting circuit that sets the threshold, The threshold setting circuit sets a charging stop voltage as the threshold when all of the overvoltage detection circuits are outputting an OFF signal, and changes the threshold to a discharging stop voltage that is lower than the charging stop voltage when an ON signal is output from at least one of the overvoltage detection circuits. The electricity storage monitoring system according to [9].

[0029] According to this configuration, when an ON signal is output from at least one overvoltage detection circuit, the threshold setting circuit changes the threshold to a discharge stop voltage that is lower than the charge stop voltage. Therefore, the power storage monitoring system can continue discharging the battery cells even if the voltage of all battery cells drops below the charge stop voltage as a result of discharging all battery cells after the voltage of any battery cell exceeds the charge stop voltage. Furthermore, when the voltage of all battery cells drops below the discharge stop voltage, the power storage monitoring system can stop the full discharge operation by the second discharge unit, thereby preventing the voltage of each battery cell from dropping too low.

[0030]

[11] When it is determined that the voltage of any of the battery cells has become an overvoltage, the second control unit controls the charging switch unit to an OFF state, causes the second discharging unit to perform the full discharging operation, and controls all of the first discharging switch units to an ON state. The power storage monitoring system according to [4].

[0031] With this configuration, all of the battery cells can be discharged from both the first discharge section and the second discharge section.

[0032] [Details of the embodiments of the present disclosure] 1. First embodiment 1 is a system mounted on a vehicle, for example. The power storage monitoring system 1 includes a power supply unit 2, a power storage unit 3, a power path 4, and a charging switch unit 5.

[0033] The power supply unit 2 is, for example, a power supply that outputs a DC voltage. The power supply unit 2 may be, for example, a battery or a DC-DC converter.

[0034] The power storage unit 3 is configured by connecting a plurality of battery cells 10 in series. Each battery cell 10 is configured by, for example, a lithium ion capacitor. The plurality of battery cells 10 includes battery cells 10A, 10B, 10C, and 10D.

[0035] The power path 4 is provided between the power supply unit 2 and the power storage unit 3. The power path 4 supplies power from the power supply unit 2 to the power storage unit 3.

[0036] The charging switch unit 5 is provided on the power path 4. The charging switch unit 5 switches between an ON state, which allows a charging current to be supplied from the power supply unit 2 to the power storage unit 3, and an OFF state, which cuts off the charging current supplied from the power supply unit 2 to the power storage unit 3.

[0037] The power storage monitoring system 1 includes a discharge unit 20. The discharge unit 20 performs an individual discharge operation to selectively discharge some of the multiple battery cells 10. The discharge unit 20 has an individual discharge unit 21 provided individually for each battery cell 10. Each individual discharge unit 21 is connected in parallel to its corresponding battery cell 10. Each individual discharge unit 21 is configured with a discharge switch unit 22 and a resistor unit 23 connected in series. Each individual discharge unit 21 cuts off discharge of the battery cell 10 through itself when its discharge switch unit 22 is in the off state. Each individual discharge unit 21 discharges its corresponding battery cell 10 through itself when its discharge switch unit 22 is in the on state. The discharge unit 20 performs a full discharge operation to discharge all of the battery cells 10. The discharge unit 20 enters a state where it is performing a full discharge operation when the discharge switch units 22 of all individual discharge units 21 are in the on state.

[0038] The electricity storage monitoring system 1 includes a voltage detection unit 30, a first control unit 31, an overvoltage detection circuit 32, and a second control unit 33.

[0039] A voltage detection unit 30 is provided individually for each battery cell 10. Each voltage detection unit 30 detects the voltage of the corresponding battery cell 10. Specifically, each voltage detection unit 30 detects the potential difference between both ends of the corresponding battery cell 10. Each voltage detection unit 30 is configured, for example, by a known voltage detection circuit.

[0040] The first control unit 31 includes, for example, a microcomputer. The first control unit 31 controls the charge switch unit 5. When a charge start condition is met, the first control unit 31 switches the charge switch unit 5 to the ON state, as shown in FIG. 2, to charge the power storage unit 3. While the first control unit 31 controls the charge switch unit 5 to the ON state, the first control unit 31 controls the discharge unit 20 to perform an individual discharge operation, thereby adjusting the voltage of each battery cell 10. The first control unit 31 controls the discharge switch unit 22 of each individual discharge unit 21 individually to cause the discharge unit 20 to perform the individual discharge operation. A signal indicating the detection result of each voltage detection unit 30 is input to the first control unit 31. When the voltage of each battery cell 10 exceeds a predetermined adjustment upper limit voltage, the first control unit 31 switches the discharge switch unit 22 to the ON state. When the voltage of each battery cell 10 becomes equal to or lower than a predetermined adjustment lower limit voltage, the first control unit 31 switches the discharge switch unit 22 to the OFF state. As a result, the voltage of each battery cell 10 is adjusted between the adjustment lower limit voltage and the adjustment upper limit voltage.

[0041] An overvoltage detection circuit 32 is provided individually for each battery cell 10. Each overvoltage detection circuit 32 determines whether the voltage of the corresponding battery cell 10 has become an overvoltage. Each overvoltage detection circuit 32 determines that an overvoltage has occurred when, for example, the voltage of the corresponding battery cell 10 exceeds a threshold value.

[0042] The second control unit 33 is provided separately from the first control unit 31. The second control unit 33 is configured, for example, by a hardware circuit. The second control unit 33 controls the charge switch unit 5 and the discharge unit 20. The second control unit 33 controls the on / off of all the discharge switch units 22 collectively. A signal indicating the determination result of each overvoltage detection circuit 32 is input to the second control unit 33. When the second control unit 33 determines that the voltage of any battery cell 10 has become an overvoltage, as shown in FIG. 3 , the second control unit 33 controls the charge switch unit 5 to the off state and causes the discharge unit 20 to perform a full discharge operation. In other words, the second control unit 33 interrupts the control by the first control unit 31 and controls the discharge switch units 22 of all the individual discharge units 21 to the on state, thereby causing the discharge unit 20 to perform a full discharge operation.

[0043] As described above, when the power storage unit 3 is being charged, the first control unit 31 normally adjusts the voltage of each battery cell 10 between the adjustment lower limit voltage and the adjustment upper limit voltage. However, if the first control unit 31 does not operate normally, the voltages VA, VB, VC, and VD of each battery cell 10A, 10B, 10C, and 10D may fall outside the adjustment range. For example, in the example shown in FIG. 4, the voltages VA, VB, and VC of the battery cells 10A, 10B, and 10C exceed the adjustment upper limit voltage during the period from timing T1 to T2. When the voltage VA of the battery cell 10A exceeds the charging stop voltage at timing T2, the second control unit 33 controls the charging switch unit 5 to the OFF state and causes the discharge unit 20 to perform a full discharge operation. As a result, the voltages VA, VB, VC, and VD of each battery cell 10A, 10B, 10C, and 10D are discharged via the discharge unit 20, as shown in FIG. 3. The charge stop voltage is set to a value greater than the adjusted upper limit voltage. For example, the charge stop voltage is set to a value greater than the upper limit voltage of the battery cell 10. The upper limit voltage of the battery cell 10 is the upper limit voltage of the battery cell 10 specified by the manufacturer.

[0044] According to this power storage monitoring system 1, the first control unit 31 can adjust the voltage of each battery cell 10. Even if the first control unit 31 does not operate normally and the voltage of any battery cell 10 becomes an overvoltage, the second control unit 33 controls the charging switch unit 5 to the off state to stop charging of the power storage unit 3. Moreover, the second control unit 33 causes the discharge unit 20 to perform a full discharge operation, thereby discharging all of the battery cells 10. Therefore, this configuration makes it easy to prevent the battery cell 10 from continuing to have an overvoltage state.

[0045] Furthermore, according to this electricity storage monitoring system 1, the individual discharge unit 21 that performs the individual discharge operation can be used to perform the full discharge operation, which allows the configuration of the discharge unit 20 to be simplified.

[0046] 2. Second embodiment In the second embodiment, a configuration including a second discharge unit that performs a full discharge operation separately from the individual discharge unit will be described. Note that in the second embodiment, the same components as those in the first embodiment will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0047] 5 includes a discharge unit 220 instead of the discharge unit 20 described in the first embodiment. In other respects, the power storage monitoring system 201 is common to the power storage monitoring system 1 of the first embodiment.

[0048] The discharge section 220 has a first discharge section 220A and a second discharge section 220B.

[0049] The first discharge unit 220A performs an individual discharge operation to selectively discharge some of the multiple battery cells 10. The first discharge unit 220A includes an individual discharge unit 221 provided individually corresponding to each battery cell 10. Each individual discharge unit 221 is connected in parallel to its corresponding battery cell 10. Each individual discharge unit 221 has a configuration in which a first discharge switch unit 222 and a first resistor unit 223 are connected in series. Each individual discharge unit 221 cuts off discharge of the battery cell 10 via itself when its own first discharge switch unit 222 is in the OFF state. Each individual discharge unit 221 discharges its corresponding battery cell 10 via itself when its own first discharge switch unit 222 is in the ON state.

[0050] The second discharge unit 220B is provided separately from the first discharge unit 220A. The second discharge unit 220B is connected in parallel to the power storage unit 3. The second discharge unit 220B has a configuration in which a second discharge switch unit 224 and a second resistor unit 225 are connected in series. The second discharge unit 220B cuts off discharge of the power storage unit 3 via itself when the second discharge switch unit 224 is in the off state. The second discharge unit 220B performs a full discharge operation in which all battery cells 10 are discharged via itself when the second discharge switch unit 224 is in the on state.

[0051] The first control unit 31 individually controls the first discharge switch unit 222 of each individual discharge unit 221, thereby causing the discharge unit 220 to perform an individual discharge operation. The first control unit 31 stops the individual discharge operation by the discharge unit 220 by controlling all of the first discharge switch units 222 to an OFF state. The second control unit 33 controls the second discharge switch unit 224 to an ON state, thereby causing the discharge unit 220 to perform a full discharge operation. The second control unit 33 stops the full discharge operation by the discharge unit 220 by controlling the second discharge switch unit 224 to an OFF state.

[0052] According to the second embodiment of the power storage monitoring system 201, even if the first discharge unit 220A does not operate normally and the voltage of any of the battery cells 10 becomes an overvoltage, the second control unit 33 can discharge all of the battery cells 10 by controlling the second discharge unit 220B.

[0053] According to the power storage monitoring system 201 of the second embodiment, even though the second discharge unit 220B is provided separately from the first discharge unit 220A that performs the individual discharge operation, the configuration of the second discharge unit 220B can be simplified.

[0054] 3. Third embodiment In the third embodiment, a configuration is described in which, after the discharge unit has performed a full discharge operation, if the voltages of all battery cells fall below the discharge stop voltage, the full discharge operation by the discharge unit is stopped. Note that in the third embodiment, the same components as in the first embodiment are designated by the same reference numerals, and detailed descriptions are omitted.

[0055] The power storage monitoring system 301 of the third embodiment shown in FIG. 6 includes an overvoltage detection circuit 332 and a second control unit 333 instead of the overvoltage detection circuit 32 and the second control unit 33 described in the first embodiment.

[0056] The second control unit 333 is provided separately from the first control unit 31. The second control unit 333 is configured, for example, by a hardware circuit. The second control unit 333 controls the charge switch unit 5 and the discharge unit 20. The second control unit 333 controls the on / off of all the discharge switch units 22 collectively. A signal indicating the determination result of each overvoltage detection circuit 332 is input to the second control unit 333. When the second control unit 333 determines that the voltage of any battery cell 10 has become an overvoltage, the second control unit 333 controls the charge switch unit 5 to the off state and causes the discharge unit 20 to perform a full discharge operation. In other words, the second control unit 333 interrupts the control by the first control unit 31 and controls the discharge switch units 22 of all the individual discharge units 21 to the on state, thereby causing the discharge unit 20 to perform a full discharge operation. After causing the discharge unit 20 to perform a full discharge operation, if the voltages of all the battery cells 10 become equal to or lower than the discharge stop voltage, the second control unit 333 interrupts the control by the first control unit 31 and stops the full discharge operation by the discharge unit 20.

[0057] The discharge stop voltage is set, for example, to a value smaller than the upper limit voltage of the battery cell 10. The upper limit voltage of the battery cell 10 is the upper limit voltage of the battery cell 10 specified by the manufacturer. The discharge stop voltage is set, for example, to a value larger than the lower limit voltage of the battery cell 10. The lower limit voltage of the battery cell 10 is the lower limit voltage of the battery cell 10 specified by the manufacturer. The discharge stop voltage is set, for example, to a value smaller than the adjusted upper limit voltage. The discharge stop voltage is set, for example, to a value larger than the adjusted lower limit voltage.

[0058] Specifically, an overvoltage detection circuit 332 is provided corresponding to each battery cell 10. Each overvoltage detection circuit 332 includes a voltage detection unit 332A and a comparator 332B. Each voltage detection unit 332A detects the potential difference across the corresponding battery cell 10. Each voltage detection unit 332A is configured, for example, by a known voltage detection circuit. A signal indicating the detection result by the corresponding voltage detection unit 332A is input to the non-inverting input terminal of each comparator 332B. A signal indicating a threshold value is input to the inverting input terminal of each comparator 332B. Each comparator 332B determines whether the voltage of the corresponding battery cell 10 exceeds the threshold value. Each comparator 332B outputs an OFF signal when the voltage of the corresponding battery cell 10 is equal to or lower than the threshold value. Each comparator 332B outputs an ON signal when the voltage of the corresponding battery cell 10 exceeds the threshold value.

[0059] The second control unit 333 includes an OR circuit 334, a latch circuit 335, and a threshold setting circuit 336. The OR circuit 334 outputs an OFF signal when all of the overvoltage detection circuits 332 output OFF signals. The OR circuit 334 outputs ON signals to all of the discharge switch units 22 when at least one of the overvoltage detection circuits 332 outputs ON signals. The latch circuit 335 outputs ON signals to the charge switch unit 5 when the OR circuit 334 outputs OFF signals. The latch circuit 335 maintains a state in which it outputs OFF signals to the charge switch unit 5 when the OR circuit 334 outputs ON signals. The threshold setting circuit 336 sets the charging stop voltage as the threshold for all of the overvoltage detection circuits 332 when all of the overvoltage detection circuits 332 output OFF signals. When at least one of the overvoltage detection circuits 332 outputs ON signals, the threshold setting circuit 336 changes the thresholds of all of the overvoltage detection circuits 332 to a discharging stop voltage that is lower than the charging stop voltage. The changed state continues as long as the latch circuit 335 outputs the ON signal.

[0060] In the initial state, the threshold setting circuit 336 sets the threshold of each overvoltage detection circuit 332 to the charging stop voltage. Therefore, each overvoltage detection circuit 332 determines whether the voltage of its corresponding battery cell 10 has exceeded the charging stop voltage. Each overvoltage detection circuit 332 outputs an OFF signal until it determines that the voltage of its corresponding battery cell 10 has exceeded the charging stop voltage. Each overvoltage detection circuit 332 outputs an ON signal when it determines that the voltage of its corresponding battery cell 10 has exceeded the charging stop voltage. When an ON signal is output from at least one overvoltage detection circuit 332, the OR circuit 334 outputs an ON signal to all discharge switch units 22. As a result, all discharge switch units 22 are switched to the ON state, and full discharge operation is performed. Furthermore, the latch circuit 335 maintains its state of outputting an OFF signal to the charging switch unit 5. This switches the charging switch unit 5 to the OFF state. Furthermore, the threshold setting circuit 336 changes the threshold of each overvoltage detection circuit 332 to the discharging stop voltage. As a result, even if the voltages of all battery cells 10 fall below the charge stop voltage due to the full discharge operation, if the voltage of any battery cell 10 exceeds the discharge stop voltage, the overvoltage detection circuit 332 corresponding to that battery cell 10 continues to output an ON signal. After that, if the full discharge operation continues and the voltages of all battery cells 10 fall below the discharge stop voltage, all overvoltage detection circuits 332 output OFF signals and the full discharge operation is stopped.

[0061] 7, the voltages VA, VB, and VC of the battery cells 10A, 10B, and 10C exceed the adjustment upper limit voltage during the period from timing T11 to T12. Then, at timing T12, the voltage VA of the battery cell 10A exceeds the charge stop voltage. In response to this, the second control unit 333 controls the charge switch unit 5 to the OFF state and causes the discharge unit 20 to perform a full discharge operation. After that, when the voltages of all the battery cells 10 fall below the discharge stop voltage, the second control unit 333 switches all the discharge switch units 22 to the OFF state while maintaining the charge switch unit 5 in the OFF state, thereby stopping the full discharge operation.

[0062] According to the power storage monitoring system 301 of the third embodiment, the voltage of each battery cell 10 can be reduced below the upper limit voltage by the full discharge operation, while preventing the voltage of each battery cell 10 from decreasing too much.

[0063] According to the power storage monitoring system 301, after detecting that the voltage of any battery cell 10 has exceeded the threshold, it is possible to quickly perform operations from discharging all battery cells 10 to stopping charging.

[0064] According to the power storage monitoring system 301, the threshold setting circuit 336 changes the threshold to a discharge stop voltage that is lower than the charge stop voltage when an ON signal is output from at least one overvoltage detection circuit 332. Therefore, the power storage monitoring system 301 can continue discharging the battery cells 10 even if the voltage of all the battery cells 10 becomes equal to or lower than the charge stop voltage as a result of discharging all the battery cells 10 after the voltage of any one of the battery cells 10 exceeds the charge stop voltage. Moreover, when the voltage of all the battery cells 10 becomes equal to or lower than the discharge stop voltage, the power storage monitoring system 301 stops all the discharging operations by the discharge unit 20, thereby preventing the voltage of each battery cell 10 from dropping too low.

[0065] 4. Fourth embodiment In the fourth embodiment, a configuration will be described in which the OR circuit, latch circuit, and threshold setting circuit described in the third embodiment are applied to the configuration of the second embodiment. Note that in the fourth embodiment, the same components as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0066] 8 includes the overvoltage detection circuit 332 described in the third embodiment instead of the overvoltage detection circuit 32. The power storage monitoring system 401 also includes a second control unit 433 instead of the second control unit 33. In other respects, the power storage monitoring system 401 is common to the power storage monitoring system 201 of the second embodiment.

[0067] The second control unit 433 has an OR circuit 434, the latch circuit 335 described in the third embodiment, and the threshold setting circuit 336 described in the third embodiment. The OR circuit 434 outputs an OFF signal when all of the overvoltage detection circuits 332 output OFF signals. The OR circuit 434 outputs ON signals to the second discharge switch unit 224 and all of the first discharge switch units 222 when at least one of the overvoltage detection circuits 332 outputs ON signals. The latch circuit 335 outputs ON signals to the charge switch unit 5 while the OR circuit 434 outputs OFF signals. The latch circuit 335 maintains a state in which it outputs OFF signals to the charge switch unit 5 when the OR circuit 434 outputs ON signals.

[0068] When the OR circuit 434 outputs an ON signal, the second discharge switch unit 224 switches to the ON state, and the second discharge unit 220B performs a full discharge operation. All of the first discharge switch units 222 switch to the ON state, and the first discharge unit 220A performs a full discharge operation. The latch circuit 335 maintains a state in which it outputs an OFF signal to the charge switch unit 5. This switches the charge switch unit 5 to the OFF state. The threshold setting circuit 336 also changes the threshold of each overvoltage detection circuit 332 to the discharge stop voltage. As a result, even if the voltages of all battery cells 10 fall below the charge stop voltage as a result of the full discharge operation, as long as the voltage of any battery cell 10 exceeds the discharge stop voltage, the overvoltage detection circuit 332 corresponding to that battery cell 10 continues to output an ON signal. Thereafter, the full discharge operation continues, and when the voltages of all battery cells 10 become equal to or lower than the discharge stop voltage, an off signal is output from all overvoltage detection circuits 332, and the full discharge operation by the first discharge unit 220A and the second discharge unit 220B is stopped.

[0069] According to the power storage monitoring system 401 of the fourth embodiment, the voltage of each battery cell 10 can be reduced below the upper limit voltage by the full discharge operation, while preventing the voltage of each battery cell 10 from decreasing too much.

[0070] According to the power storage monitoring system 401, after detecting that the voltage of any battery cell 10 has exceeded the threshold, it is possible to quickly perform operations from discharging all battery cells 10 to stopping charging.

[0071] According to the power storage monitoring system 401, the threshold setting circuit 336 changes the threshold to a discharge stop voltage that is lower than the charge stop voltage when an ON signal is output from at least one overvoltage detection circuit 332. Therefore, the power storage monitoring system 401 can continue discharging the battery cells 10 even if the voltages of all the battery cells 10 become equal to or lower than the charge stop voltage as a result of all the battery cells 10 being discharged after the voltage of any one of the battery cells 10 exceeds the charge stop voltage. Moreover, when the voltages of all the battery cells 10 become equal to or lower than the discharge stop voltage, the power storage monitoring system 401 stops all the discharging operations by the first discharging unit 220A and the second discharging unit 220B, thereby preventing the voltage of each battery cell 10 from dropping too low.

[0072] According to the power storage monitoring system 401, all of the battery cells 10 can be discharged from both the first discharge section 220A and the second discharge section 220B.

[0073] <Other embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or following embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or following embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiment may be modified as follows.

[0074] The power storage monitoring system 201 of the second embodiment may be configured to stop all discharging operations when the voltages of all the battery cells 10 reach the discharge stop voltage, similarly to the third embodiment.

[0075] The overvoltage detection circuit 332 of the power storage monitoring system 301 of the third embodiment may detect an overvoltage by using the voltage detection unit 30 described in the first embodiment.

[0076] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is intended to include all modifications within the scope indicated by the claims or the scope equivalent to the claims. [Explanation of symbols]

[0077] 1. Energy storage monitoring system 2…Power supply section 3...Storage unit 4…Power line 5...Charging switch 10...Battery cell 10A…battery cell 10B...battery cell 10C...battery cell 10D...Battery cell 20…Discharge part 21...Individual discharge section 22...Discharge switch section 23...Resistance part 30...Voltage detection unit 31...First control section 32...Overvoltage detection circuit 33...Second control section 201...Electricity storage monitoring system 220…Discharge part 220A...First discharge section 220B…Second discharge section 221...Individual discharge section 222...First discharge switch section 223...1st resistance section 224...Second discharge switch section 225…Second resistance section 301...Electricity storage monitoring system 332...Overvoltage detection circuit 332A...Voltage detection unit 332B...Comparator 333...Second control section 334...OR circuit 335...Latch circuit 336...Threshold setting circuit 401...Electricity storage monitoring system 433...Second control section 434...OR circuit VA: Battery cell voltage at 10A VB: Voltage of battery cell 10B VC: Battery cell voltage at 10C VD: Voltage of battery cell 10D

Claims

1. a power storage unit configured by connecting a plurality of battery cells in series; a charging switch unit that cuts off a charging current supplied from a power supply unit to the power storage unit; a discharge unit that performs an individual discharge operation to selectively discharge some of the plurality of battery cells; a first control unit that controls the discharge unit to perform the individual discharge operation to adjust the voltage of each of the battery cells; a second control unit provided separately from the first control unit, the discharge unit performs a full discharge operation to discharge all of the battery cells, When it is determined that the voltage of any of the battery cells has become an overvoltage, the second control unit controls the charging switch unit to an OFF state and causes the discharging unit to perform the full discharging operation. Energy storage monitoring system.

2. the discharge unit includes an individual discharge unit provided individually corresponding to each of the battery cells, Each individual discharge unit is connected in parallel to the corresponding battery cell, and has a configuration in which a discharge switch unit and a resistor unit are connected in series, and discharges the corresponding battery cell when the discharge switch unit is turned on; the first control unit controls the discharge switch unit of each of the individual discharge units individually to cause the discharge units to perform the individual discharge operation; The second control unit controls the discharge switch units of all the individual discharge units to an on state, thereby causing the discharge units to perform the full discharge operation. The electricity storage monitoring system according to claim 1 .

3. The discharge unit is a first discharge unit; a second discharge section provided separately from the first discharge section, the first discharge unit performs the individual discharge operation, The second discharge unit performs the full discharge operation, the first control unit controls the first discharge unit to cause the discharge unit to perform the individual discharge operation; The second control unit controls the second discharge unit to cause the discharge unit to perform the full discharge operation. The electricity storage monitoring system according to claim 1 .

4. the first discharge unit includes an individual discharge unit provided individually corresponding to each of the battery cells, Each individual discharge unit is connected in parallel to the corresponding battery cell, and has a configuration in which a first discharge switch unit and a first resistor unit are connected in series, and discharges the corresponding battery cell when the first discharge switch unit is in an on state; the first control unit controls the first discharge switch unit of each of the individual discharge units individually to cause the discharge units to perform the individual discharge operation; the second discharge unit is connected in parallel to the power storage unit, has a configuration in which a second discharge switch unit and a second resistor unit are connected in series, and discharges the power storage unit when the second discharge switch unit is in an on state; The second control unit controls the second discharge switch unit to an on state, thereby causing the discharge unit to perform the full discharge operation. The electricity storage monitoring system according to claim 3 .

5. The second control unit stops the full discharge operation by the discharge unit when the voltages of all the battery cells become equal to or lower than a discharge stop voltage after the discharge unit has performed the full discharge operation. The electricity storage monitoring system according to any one of claims 1 to 4.

6. The discharge cut-off voltage is set to a value lower than the upper limit voltage of the battery cell. The electricity storage monitoring system according to claim 5 .

7. an overvoltage detection circuit provided corresponding to each of the battery cells; each of the overvoltage detection circuits outputs an OFF signal when the voltage of the battery cell corresponding to the overvoltage detection circuit is equal to or lower than a threshold, and outputs an ON signal when the voltage of the battery cell corresponding to the overvoltage detection circuit exceeds the threshold; The second control unit has an OR circuit that outputs an ON signal to all of the discharge switch units when an ON signal is output from at least one of the overvoltage detection circuits, and a latch circuit that maintains a state in which an OFF signal is output to the charge switch units when an ON signal is output from the OR circuit. The electricity storage monitoring system according to claim 2 .

8. the OR circuit outputs an OFF signal to all of the discharge switch units when an OFF signal is output from all of the overvoltage detection circuits; the second control unit has a threshold setting circuit that sets the threshold, The threshold setting circuit sets a charging stop voltage as the threshold when all of the overvoltage detection circuits are outputting an OFF signal, and changes the threshold to a discharging stop voltage that is lower than the charging stop voltage when an ON signal is output from at least one of the overvoltage detection circuits. The electricity storage monitoring system according to claim 7.

9. an overvoltage detection circuit provided corresponding to each of the battery cells; each of the overvoltage detection circuits outputs an OFF signal when the voltage of the battery cell corresponding to the overvoltage detection circuit is equal to or lower than a threshold, and outputs an ON signal when the voltage of the battery cell corresponding to the overvoltage detection circuit exceeds the threshold; The second control unit has an OR circuit that outputs an ON signal to the second discharge switch unit when an ON signal is output from at least one of the overvoltage detection circuits, and a latch circuit that maintains a state in which an OFF signal is output to the charge switch unit when an ON signal is output from the OR circuit. The electricity storage monitoring system according to claim 4 .

10. the OR circuit outputs an OFF signal to all of the second discharge switch units when an OFF signal is output from all of the overvoltage detection circuits; the second control unit has a threshold setting circuit that sets the threshold, The threshold setting circuit sets a charging stop voltage as the threshold when all of the overvoltage detection circuits are outputting an OFF signal, and changes the threshold to a discharging stop voltage that is lower than the charging stop voltage when an ON signal is output from at least one of the overvoltage detection circuits. The electricity storage monitoring system according to claim 9 .

11. When it is determined that the voltage of any of the battery cells has become an overvoltage, the second control unit controls the charging switch unit to an OFF state, causes the second discharging unit to perform the full discharging operation, and controls all of the first discharging switch units to an ON state. The electricity storage monitoring system according to claim 4 .

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