Power storage device

Abstract

In a power storage device 10, a control unit 42 controls discharge of a chargeable / dischargeable battery module 40. A power supply circuit 44 supplies power to the control unit 42 on the basis of the power of an external power supply 70. Upon receipt of a trigger signal, the control unit 42 causes the power supply circuit 44 to supply power on the basis of the power of the battery module 40 instead of the power of the external power supply 70.

Description

Power storage device

[0001] The present disclosure relates to a power storage device.

[0002] In a data center, as a countermeasure against power outages, a backup power supply system using a secondary battery is generally used to hold power for several minutes until a generator starts up during a power outage. The backup power supply system includes a power storage device having a secondary battery and a control circuit that controls charging and discharging of the secondary battery. Generally, in a power storage device for a data center, the control circuit is operated by power supply from a higher-level system in order to suppress the current consumption from the secondary battery.

[0003] When the characteristics of the secondary battery deteriorate, it is necessary to discard the power storage device. When discarding the power storage device, it is necessary to discharge the secondary battery. Patent Document 1 discloses a battery discharge device for discharging a storage battery.

[0004] Japanese Patent Translation of PCT International Publication No. 2023-535136

[0005] In the configuration in which the control circuit is operated by power supply from the above-described higher-level system, even when discharging to discard the power storage device, it is necessary to supply power from the outside to the power storage device and operate the internal control circuit. In this case, it is necessary to continuously supply power from the outside until the discharge is completed.

[0006] For example, when discharging a plurality of power storage devices to be discarded, if one external power source is used, other power storage devices cannot be discharged until the discharge of one power storage device is completed, so it takes a long time until the discharge of all power storage devices is completed.

[0007] In order to shorten the time until discharge is completed, it is necessary to prepare an external power source and a discharge device for each of the plurality of power storage devices to be discarded and discharge the plurality of power storage devices in parallel. However, the cost increases because a plurality of external power sources and a plurality of discharge devices are prepared.

[0008] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a technique capable of discharging more efficiently in a power storage device in which a control unit executes control based on power from an external power source.

[0009] To solve the above problems, an energy storage device according to one embodiment of the present disclosure comprises a rechargeable battery module, a control unit that controls the discharge of the battery module, and a power supply circuit that supplies power to the control unit based on the power of an external power source. When the control unit receives a trigger signal, it causes the power supply circuit to supply power based on the power of the battery module instead of the power of an external power source.

[0010] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between devices, systems, methods, computer programs, etc., are also valid forms of this disclosure.

[0011] According to this disclosure, a technology is available that enables more efficient discharge in an energy storage device in which a control unit performs control based on power from an external power source.

[0012] This is a diagram showing the configuration of the energy storage system according to the embodiment. This diagram is for explaining the energy storage system during maintenance. This is a diagram showing the configuration of the energy storage device in Figure 1.

[0013] Figure 1 shows the configuration of an embodiment of the energy storage system 1. The energy storage system 1 is used, for example, as a backup power supply system in a data center. The energy storage system 1 comprises a first energy storage device 10a, a second energy storage device 10b, a third energy storage device 10c, a fourth energy storage device 10d, a fifth energy storage device 10e, a sixth energy storage device 10f, a DC bus 12, and a higher-level system 14. Hereinafter, the first energy storage device 10a, the second energy storage device 10b, the third energy storage device 10c, the fourth energy storage device 10d, the fifth energy storage device 10e, and the sixth energy storage device 10f will be collectively referred to as "energy storage device 10". Here, an example in which six energy storage devices 10 are provided will be described, but the number is not particularly limited.

[0014] Multiple energy storage devices 10 are housed in a rack 20. Each energy storage device 10 can be individually removed from the rack 20. The multiple energy storage devices 10 are electrically connected to a higher-level system 14 and a load 16 via a common DC bus 12. Each energy storage device 10 has a rechargeable battery module, as will be described later.

[0015] The higher-level system 14 has an AC / DC converter (not shown). Under normal conditions when the commercial power grid 18 is not experiencing a power outage, the AC / DC converter converts the AC power input from the commercial power grid 18 into DC power, outputs the DC power to the DC bus 12, and can supply DC power to the load 16 via the DC bus 12. The load 16 operates using the DC power as its power source. The AC / DC converter can also charge each of the battery modules of the multiple energy storage devices 10 via the DC bus 12. The DC power supplied from the AC / DC converter to the DC bus 12 is also used as a power source for the operation of the multiple energy storage devices 10. Therefore, the AC / DC converter can also be called an external power source for the energy storage devices 10. In the event of a power outage, each of the multiple energy storage devices 10 discharges to the backup load 16. The higher-level system 14 also supplies various control signals to the multiple energy storage devices 10 via wiring (not shown).

[0016] Figure 2 is a diagram illustrating the energy storage system 1 during maintenance. Figure 2 shows the situation in which the sixth energy storage device 10f, which has reached the end of its lifespan, is removed from the rack 20, and a new seventh energy storage device 10g is installed in the rack 20.

[0017] Figure 3 shows the configuration of the energy storage device 10 shown in Figure 1. The energy storage device 10 includes an energy storage unit 30, a capacitor C1, and a DC / DC converter 32.

[0018] The positive terminal T1 of the energy storage unit 30 is connected to the DC / DC converter 32. The negative terminal T2 of the energy storage unit 30 is also connected to the DC / DC converter 32. The energy storage unit 30 can supply DC power to the DC / DC converter 32 via the first terminal T1 and the second terminal T2. The energy storage unit 30 can also receive DC power from the DC / DC converter 32 via the first terminal T1 and the second terminal T2.

[0019] The DC / DC converter 32 is capable of converting voltage in both directions. When the energy storage unit 30 is discharging, the DC / DC converter 32 converts the voltage supplied from the energy storage unit 30 to a different voltage and supplies the converted voltage to the DC bus 12. Also, when the energy storage unit 30 is charging, the DC / DC converter 32 converts the voltage of the DC bus 12 to a different voltage and supplies the converted voltage to the energy storage unit 30.

[0020] Furthermore, the DC / DC converter 32 supplies power to the energy storage unit 30 to operate it, based on the power supplied from an external power supply 70 included in the higher-level system 14 via the DC bus 12. The external power supply 70 in the higher-level system 14 corresponds to the AC / DC converter described above.

[0021] The DC / DC converter 32 has a control unit 60. The control unit 60 can output a trigger signal to the energy storage unit 30 based on a control signal received from the higher-level system 14. The trigger signal will be described later.

[0022] One end of capacitor C1 is connected to the connection line between the first terminal T1 of the energy storage unit 30 and the DC / DC converter 32. The other end of capacitor C1 is grounded.

[0023] The energy storage unit 30 includes a battery module 40, a control unit 42, a power supply circuit 44, a discharge circuit 46, a switch unit 48, a voltage detection unit 49, resistors R11, R12, ..., a switch SW10, and diodes D1, D2.

[0024] The battery module 40 includes n (where n is an integer of 2 or more) battery cells S1 to Sn connected in series. The battery cells S1 to Sn are rechargeable batteries, such as lithium-ion batteries.

[0025] The negative terminal of battery cell S1 is connected to the control unit 42. The positive terminal of battery cell S1 is connected to the control unit 42 via resistor R11. The positive terminal of battery cell S2 is connected to the control unit 42 via resistor R12. Although not shown in the diagram, the positive terminals of the other battery cells are also connected to the control unit 42 via resistors.

[0026] The negative terminal of the battery module 40 is connected to the second terminal T2. The positive terminal of the battery module 40 is connected to the first terminal T1 via the switch unit 48.

[0027] The switch unit 48 switches between making electrical contact between the positive terminal of the battery module 40 and the first terminal T1. The switch unit 48 includes a first transistor TR1 and a second transistor TR2. The first transistor TR1 and the second transistor TR2 are connected in series between one end of the battery module 40 and the first terminal T1. The first transistor TR1 is an FET for charge control. The second transistor TR2 is an FET for discharge control.

[0028] The control unit 42 operates using power supplied from the power supply circuit 44. The control unit 42 controls the charging and discharging of the battery module 40 by controlling the switch unit 48. The control unit 42 also monitors the voltages of each battery cell S1 to Sn supplied via resistors R11, R12, etc., and performs known equalization control, etc.

[0029] The power supply circuit 44 supplies power to the control unit 42 based on the DC power of the external power supply 70 supplied from the upper system 14 via the DC / DC converter 32. The power supply circuit 44 includes, for example, a DC / DC converter.

[0030] Diode D1 has an anode to which power is supplied from the DC / DC converter 32 and a cathode connected to the input side of the power supply circuit 44.

[0031] One end of switch SW10 is connected to the positive terminal of battery module 40. The other end of switch SW10 is connected to the anode of diode D2. Switch SW10 is controlled by control unit 42. The cathode of diode D2 is connected to the connection node between the cathode of diode D1 and power supply circuit 44.

[0032] The discharge circuit 46 can discharge the battery module 40 according to the control of the control unit 42. The discharge circuit 46 includes a resistor R1 and a switch SW1. One end of the resistor R1 is connected to the first terminal T1. The other end of the resistor R1 is connected to one end of the switch SW1. The other end of the switch SW1 is connected to the second terminal T2. The switch SW1 is controlled by the control unit 42.

[0033] When the energy storage device 10 is disconnected from the external power supply 70, the DC / DC converter 32 switches the energy storage device 10 to a low-power mode by stopping the power supply to the power supply circuit 44. The low-power mode can also be called a sleep mode, and it is a mode that suppresses the discharge of the battery module 40.

[0034] For example, when the energy storage device 10 is manufactured in the factory, power is supplied to the DC / DC converter 32 from the external power supply of the inspection machine, causing the energy storage device 10 to operate and be inspected by the inspection machine. After the inspection, when the inspection machine is removed and the power supply is stopped, the DC / DC converter 32 stops supplying power to the power supply circuit 44. This allows the product to be set to a low power consumption mode when it is shipped.

[0035] Furthermore, when the energy storage device 10 is removed from the rack 20 during maintenance and the power supply from the external power supply 70 in the higher-level system 14 is stopped, the DC / DC converter 32 stops supplying power to the power supply circuit 44. This allows the system to be set to a low power consumption mode during maintenance.

[0036] The voltage detection unit 49 outputs a voltage drop signal to the control unit 42 when the voltage at the anode of diode D1, i.e., the voltage supplied from the DC / DC converter 32 to the power supply circuit 44, falls below a predetermined lower limit voltage. The output of this signal indicates that the energy storage device 10 has been disconnected from the external power supply 70 and that the power supply from the external power supply 70 has stopped.

[0037] When the control unit 42 receives a signal from the voltage detection unit 49, it turns on the switch SW10. As a result, the output voltage of the battery module 40 is supplied to the input side of the power supply circuit 44 via the diode D2, and the power supply circuit 44 supplies power to the control unit 42 based on the power of the battery module 40. When the control unit 42 receives a signal from the voltage detection unit 49, it controls the switch unit 48 to a non-conducting state by controlling the second transistor TR2 to a non-conducting state, and after discharging the charge on the connection line between the switch unit 48 and the DC / DC converter 32 to the discharge circuit 46, it operates in low power consumption mode. This charge on the connection line includes the charge of the capacitor C1. The control unit 42 monitors the voltage at the first terminal T1, i.e., the voltage at one end of the resistor R1, and when the voltage at the first terminal T1 falls below a predetermined threshold voltage, it operates in low power consumption mode.

[0038] When the control unit 42 receives a trigger signal, it supplies power to the power supply circuit 44 based on the power of the battery module 40 instead of the power of the external power supply 70. The trigger signal is a signal to switch to discard mode. Specifically, when the control unit 42 receives a trigger signal, it turns on the switch SW 10. As a result, the output voltage of the battery module 40 is supplied to the input side of the power supply circuit 44 via the diode D2. The control unit 42 controls the switch SW 10 to a non-conducting state when it does not receive a signal from the voltage detection unit 49 or a trigger signal.

[0039] Furthermore, when the control unit 42 receives a trigger signal, it controls the switch unit 48 to a conductive state by making the second transistor TR2 conduct, and in that state, it causes the battery module 40 to discharge into the discharge circuit 46.

[0040] When disposing of the energy storage device 10, with the energy storage device 10 to be disposed of stored in the rack 20 and connected to the DC bus 12, a user can, for example, operate an operation input unit (not shown) provided in the higher-level system 14 to supply a trigger signal to the energy storage unit 30 of the energy storage device 10 to be disposed of, and the energy storage device 10 will be switched to disposal mode. After this, even if the energy storage device 10 to be disposed of is removed from the rack 20, the energy storage device 10 to be disposed of can continue to operate in disposal mode using the power of the battery module 40.

[0041] Incidentally, the trigger signal may be supplied from an operation input unit (not shown) such as a switch provided in the power storage device 10 when the operation input unit is operated by the user. The trigger signal may be supplied from an inspection device or the like connected to the power storage device 10.

[0042] The control unit 42 and the control unit 60 are each realized by the cooperation of hardware resources and software resources. As hardware resources, a CPU, GPU, DSP, FPGA, and other LSIs can be used. As software resources, programs such as an operating system and applications can be used.

[0043] According to the embodiment, when a trigger signal is received, the power supply circuit 44 is supplied with power based on the power of the battery module 40 instead of the external power supply 70. Therefore, even if the external power supply 70 is removed, the discharge of the battery module 40 can be continued. Therefore, a plurality of power storage devices 10 can be discharged in parallel without using a plurality of external power supplies, and the time until the discharge of the plurality of power storage devices 10 is completed can be shortened.

[0044] Even when the power storage device 10 is switched to the discard mode and discharged while being connected to the rack 20, thereafter, the discharge for discard can be continued by using the internal discharge circuit 46 in a state where the power storage device 10 is removed from the rack. Therefore, when discharging for discard, a replacement power storage device 10 can be attached to the rack 20 without waiting for the completion of the discharge. Also, there is no need to connect an external discharge device to the power storage device 10.

[0045] Therefore, in the power storage device 10 in which the control unit 42 controls the discharge of the battery module 40 based on the power of the external power supply 70, more efficient discharge can be achieved.

[0046] Further, in the discard mode, since the discharge is performed by the discharge circuit 46 used when switching to the low power consumption mode, there is no need to newly provide a dedicated discharge circuit for the discard mode in the power storage device 10. Therefore, an increase in the size, complexity of the configuration, and cost of the power storage device 10 can be suppressed.

[0047] As described above, the present disclosure has been explained based on the embodiments. These embodiments are examples, and it is understood by those skilled in the art that various modifications are possible for each of these components or combinations of each processing process, and such modifications are also within the scope of the present disclosure.

[0048] In addition, the embodiments may be specified by the following items.

[0049] [Item 1] A rechargeable battery module (40), a control unit (42) that controls the discharge of the battery module (40), and a power supply circuit (44) that supplies power to the control unit (42) based on the power of an external power supply (70). The control unit (42) causes the power supply circuit (44) to be supplied with power based on the power of the battery module (40) instead of the power of the external power supply (70) when receiving a trigger signal. A power storage device (10) characterized by this. This enables more efficient discharge.

[0050] [Item 2] The power storage device (10) according to Item 1, further comprising a discharge circuit (46) capable of discharging the battery module (40). The control unit (42) causes the battery module (40) to be discharged to the discharge circuit (46) when receiving the trigger signal. In this case, there is no need to connect an external discharge device to the power storage device.

[0051] [Item 3] The energy storage device (10) according to Item 2, further comprising: a DC / DC converter (32); a switch unit (48) for switching between making a connection between one end of the battery module (40) and the DC / DC converter (32); wherein the control unit (42) controls the switch unit (48) to a non-conductive state when the power supply from the external power source is stopped, discharges the charge of the connection line between the switch unit (48) and the DC / DC converter (32) to the discharge circuit (46), and then operates in a low power consumption mode; and when the control unit (42) receives the trigger signal, controls the switch unit (48) to a conductive state, causing the battery module (40) to discharge to the discharge circuit (46).

[0052] This disclosure can be used in energy storage devices.

[0053] 1...Energy storage system, 10...Energy storage device, 10a...First energy storage device, 10b...Second energy storage device, 10c...Third energy storage device, 10d...Fourth energy storage device, 10e...Fifth energy storage device, 10f...Sixth energy storage device, 10g...Seventh energy storage device, 12...DC bus, 14...Higher-level system, 20...Rack, 30...Energy storage unit, 32...DC / DC converter, 40...Battery module, 42...Control unit, 44...Power supply circuit, 46...Discharge circuit, 48...Switch unit, 49...Voltage detection unit, 60...Control unit, 70...External power supply.

Claims

1. An energy storage device comprising: a rechargeable battery module; a control unit for controlling the discharge of the battery module; and a power supply circuit for supplying power to the control unit based on the power of an external power source, wherein, upon receiving a trigger signal, the control unit causes the power supply circuit to be supplied with power based on the power of the battery module instead of the power of the external power source.

2. The energy storage device according to claim 1, further comprising a discharge circuit capable of discharging the battery module, wherein the control unit, upon receiving the trigger signal, causes the discharge circuit to discharge the battery module.

3. The energy storage device according to claim 2, further comprising: a DC / DC converter; a switch unit for switching between conducting or not conducting between one end of the battery module and the DC / DC converter, wherein the control unit controls the switch unit to a non-conductive state when the power supply from the external power source is stopped, discharges the charge of the connection line between the switch unit and the DC / DC converter to the discharge circuit, and then operates in a low power consumption mode; and when the control unit receives the trigger signal, controls the switch unit to a conductive state and discharges the battery module to the discharge circuit.

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