Power storage system

Abstract

To provide a power storage system that can be in standby mode while suppressing battery power consumption.SOLUTION: A discharge FET 37 is always on and in standby mode unless an abnormality occurs. Therefore, even when a power storage device 20 is on standby, a drive current for the discharge FET 37 is always flowing. However, if this drive current is supplied from a battery 34, the capacity of the battery 34 is to be reduced. Therefore, by arranging the discharge FET 37 on the output side (OUT) of the power storage device 20 such that a voltage on the device side higher than the voltage of the battery 34 is input to the output side (OUT) of the power storage device 20, and by arranging the discharge FET 37 on the output side (OUT) of an ideal diode 35, the current for the ideal diode 35 and the discharge FET 37 flows from the device side. This makes it possible to standby while suppressing the power consumption of the battery 34, even when the discharge FET 37 is on during backup standby of the power storage device 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electricity storage system. [Background technology]

[0002] As conventional techniques, techniques such as those disclosed in Patent Documents 1 to 4 have been disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-136163 [Patent Document 2] Japanese Patent Application Publication No. 2018-033256 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-185365 [Patent Document 4] Japanese Patent Application Publication No. 09-046911 Summary of the Invention [Problem to be solved by the invention]

[0004] Although various conventional technologies have been proposed, there is a demand for an electricity storage system that can be in standby mode while suppressing the power consumption of the battery.

[0005] Therefore, an object of the present invention is to provide a power storage system that can be in standby mode while suppressing the power consumption of the battery. [Means for solving the problem]

[0006] The present invention employs the following solutions. Note that the solutions below are merely examples, and the present invention is not limited to these. The present invention can be an invention that includes at least one of the invention-specifying matters shown in the solutions below. Furthermore, each invention-specifying matter shown in the solutions below can be made into a subordinate concept by adding an element that limits the invention-specifying matter, or can be made into a superordinate concept by removing an element that limits the invention-specifying matter.

[0007] The energy storage system of the solution includes, for example, a device and an energy storage device connected to the device, the device including a power supply unit and a load unit that consumes power from the power supply unit, the energy storage device having an input side connected to the power supply unit and an output side connected to the load unit, the energy storage device including a charge control unit, a battery, a discharge control unit, and a backflow prevention unit that prevents current from flowing back from the device to the battery, the voltage on the output side being higher than the voltage of the battery, and the discharge control unit being located on the output side of the backflow prevention unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a power storage system that can be in standby mode while suppressing the power consumption of the battery. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a power storage system 100 according to an embodiment. [Figure 2] 2 is a diagram showing a circuit configuration 30A of a power storage device 20 according to an embodiment. FIG. [Figure 3] FIG. 3 is a diagram showing a circuit configuration 30B of the power storage device 20 according to the embodiment. [Figure 4] FIG. 3 is a diagram showing a circuit configuration 30C of a power storage device 40 of a comparative example. [Figure 5] 10A and 10B are diagrams showing currents flowing out of batteries in each power storage device during standby or shutdown. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are shown as preferred examples of a power storage system, and the embodiments are not limited to these examples.

[0011] FIG. 1 is a block diagram showing a power storage system 100 according to an embodiment. The power storage system 100 includes a device 10 and a power storage device 20 connected to the device 10. The device 10 includes a power supply unit 11 and a load unit 12 that consumes power from the power supply unit 11. The device 10 may be any device, such as a device for a server system or a device for a railway system.

[0012] The power supply unit 11 is a part that serves as a power source for the device 10. The load unit 12 differs depending on the type of the device 10, but may be, for example, a circuit for a server system, a circuit for a railway system, or the like.

[0013] The power storage device 20 is a device that backs up the device 10. The power storage device 20 has an input side (IN) having an input terminal (IN terminal) connected to a power supply unit 11, and an output side (OUT) having an output terminal (OUT terminal) connected to a load unit 12. The voltage on the device 10 side is input to the output side (OUT) of the power storage device 20.

[0014] FIG. 2 is a diagram showing a circuit configuration 30A of the power storage device 20 according to the embodiment. The power storage device 20 can employ a circuit configuration 30A shown in Fig. 2. The power storage device 20 includes a DC / DC converter 31, a 12V-5V circuit 32, a charge FET 33 (charge control unit), a battery 34 (cell), an ideal diode 35 (backflow prevention unit), a control IC 36 (control unit), a discharge FET 37 (discharge control unit), and a drive FET 38 (drive control unit).

[0015] The power storage device 20 includes a control board (not shown), which has a main line formed on it extending from the input side (IN) to the output side (OUT). On the main line, a DC / DC converter 31, a charge FET 33, an ideal diode 35, and a discharge FET 37 are arranged in this order.

[0016] A 12V-5V circuit 32 is disposed between the DC / DC converter 31 and the charging FET 33. A battery 34 is disposed between the charging FET 33 and an ideal diode 35. The ideal diode 35 is connected to a control IC 36, and the discharging FET 37 is connected to a driving FET 38. The battery 34, the control IC 36, and the driving FET 38 are each connected to GND (ground) (G1, G2, G3).

[0017] The DC / DC converter 31 is a device that converts a given direct current into another direct current. The 12V-5V circuit 32 is a circuit that converts an input voltage of 12V into an output voltage of 5V. The charging FET 33 (charging FET (Field Effect Transistor)) is a switching element for charging. The charging FET 33 controls charging of the battery 34. The battery 34 is a power source for the power storage device 20, and includes, for example, four batteries connected in series. The batteries are, for example, nickel-metal hydride batteries.

[0018] Ideal diode 35 is a circuit that prevents current from flowing back from device 10 (see FIG. 1) to battery 34. The control IC 36 is a controller (ORing controller) that controls the ideal diode 35 . The discharge FET 37 (FET for discharging) is a switch element for discharging. The discharge FET 37 controls discharging of the battery 34. The drive FET 38 (a drive FET) is a switch element for driving the discharge FET 37.

[0019] The voltage on the output side (OUT) is higher than the voltage of the battery 34. Furthermore, the discharge FET 37 is disposed closer to the output side (OUT) than the ideal diode 35. In this case, since the voltage on the output side (OUT) is higher than that of the battery 34, the drive current (see arrow A) of the control IC 36 of the ideal diode 35 and the drive current (see arrow B) of the discharge FET 37 are supplied from the output side (OUT). Therefore, the current (leakage current) flowing out of the battery 34 during discharge standby is 0 A.

[0020] The circuit configuration 30A is effective when the power storage system 100 (device 10 and power storage device 20) is not shut down or when the power storage system 100 (device 10 and power storage device 20) is not shut down frequently (for example, once every day to every few days).

[0021] FIG. 3 is a diagram showing a circuit configuration 30B of the power storage device 20 according to the embodiment. The power storage device 20 may also employ a circuit configuration 30B shown in Fig. 3. The circuit configuration 30B differs from the circuit configuration 30A in that the control IC 36 is connected to the drive FET 38. Specifically, the GND (ground line) of the control IC 36 of the ideal diode 35 is connected to the drain of the drive FET 38 of the discharge FET 37. Note that other points are the same as those of the circuit configuration 30A, and therefore description thereof will be omitted.

[0022] In this case, since the voltage of the output side (OUT) is higher than that of the battery 34, the drive current (see arrow C) of the control IC 36 of the ideal diode 35 and the drive current (see arrow D) of the discharge FET 37 are supplied from the output side (OUT).

[0023] 2, if the ground line of the control IC 36 is connected directly to GND (G2), current leaks from the battery 34 to GND during shutdown. However, if the ground line of the control IC 36 of the ideal diode 35 is connected to the drain of the drive FET 38 of the discharge FET 37 as shown in FIG. 3, such current leakage can be avoided. This makes it possible to eliminate current flowing out from the battery 34 during shutdown. Note that shutdown refers to a time when the operation of the power storage system 100 (the device 10 or the power storage device 20) is temporarily stopped or when the battery 34 is not in use, such as when the power storage system 100 (the device 10 or the power storage device 20) is shipped.

[0024] In the case of circuit configuration 30A, the current (several tens of μA) of the control IC 36 of the ideal diode 35 flows from the battery 34 during shutdown, but in the case of circuit configuration 30B, the current of the control IC 36 of the ideal diode 35 does not flow from the battery 34 during shutdown. Therefore, in circuit configuration 30B, the current flowing from the battery 34 during discharge standby and the current flowing from the battery 34 during shutdown can both be set to 0 A. Circuit configuration 30B is effective when the power storage system 100 (device 10 and power storage device 20) is shut down frequently.

[0025] FIG. 4 is a diagram showing a circuit configuration 30C of a power storage device 40 of a comparative example. The power storage device 40 of the comparative example employs a circuit configuration 30C shown in FIG. The circuit configuration 30C differs from the circuit configurations 30A and 30B in that the ideal diode 35 is arranged closer to the output side (OUT) than the discharge FET 37. Note that other points are the same as those of the circuit configuration 30A, and therefore description thereof will be omitted. However, when such a circuit configuration 30C is employed, the drive current for the discharge FET 37 flows from the battery 34, causing a current of several hundred μA to leak from the battery 34 during discharge standby (see arrow E).

[0026] FIG. 5 is a diagram showing the current flowing out of the battery in each power storage device during standby or shutdown. When the circuit configuration 30C (FIG. 4) is used in the power storage device, the current flowing from the battery during standby is several hundred μA, and the current flowing from the battery during shutdown is 0 A.

[0027] When the circuit configuration 30A (FIG. 2) is used in the power storage device, the current flowing from the battery during standby is 0 A, and the current flowing from the battery during shutdown is several tens of μA. When the circuit configuration 30B (FIG. 3) is used in the power storage device, the current flowing from the battery during standby is 0 A, and the current flowing from the battery during shutdown is 0 A.

[0028] From these results, the following can be seen: (1) When focusing on the current flowing out of the battery during standby, circuit configuration 30A (FIG. 2) and circuit configuration 30B (FIG. 3) can reduce the amount of current flowing out more effectively than circuit configuration 30C (FIG. 4). (2) When focusing on the current flowing out of the battery during shutdown, the circuit configuration 30B (FIG. 3) can suppress the current flowing out more effectively than the circuit configuration 30A (FIG. 2). (3) When focusing on the overall current flowing out of the battery, circuit configuration 30A (FIG. 2) and circuit configuration 30B (FIG. 3) can reduce the amount of current flowing out more effectively than circuit configuration 30C (FIG. 4).

[0029] As described above, this embodiment has the following advantages. (1) According to this embodiment, the discharge FET 37 is arranged on the OUT side of the ideal diode 35 (circuit configuration 30A (FIG. 2) or circuit configuration 30B (FIG. 3)), and therefore, it is possible to provide the energy storage system 100 that can be in standby mode while suppressing the power consumption of the battery 34 (while suppressing the current flowing out of the battery 34).

[0030] (2) The discharge FET 37 of the power storage device 20 must be turned ON when discharging is desired. If a momentary voltage drop (instantaneous voltage drop) is not permitted in the backup power storage device 20, the discharge FET 37 is always in an ON standby state unless an abnormality occurs so that the power storage device 20 can discharge to the device 10 at any time. Therefore, even when the power storage device 20 is in standby, a drive current for the discharge FET 37 is always flowing. However, if this drive current is supplied from the battery 34, the capacity of the battery 34 will be reduced. Therefore, by arranging the discharge FET 37 on the output side (OUT) of the power storage device 20 so that a voltage on the device 10 side that is higher than the voltage of the battery 34 is input to the output side (OUT) of the power storage device 20, the current of the ideal diode 35 and the discharge FET 37 flows from the device 10 side. As a result, even when the discharge FET 37 is turned ON during backup standby of the power storage device 20, it is possible to standby while suppressing the power consumption of the battery 34.

[0031] (3) If the ideal diode 35 is placed on the battery 34 side, the current of the control IC 36 of the ideal diode 35 will flow from the battery 34 during shutdown (circuit configuration 30A (FIG. 2)). Therefore, in circuit configuration 30B of this embodiment, the GND of the control IC 36 of the ideal diode 35 is connected to the drain of the drive FET 38 of the discharge FET 37 (FIG. 3). This circuit configuration can eliminate the current flowing out of the battery 34 during shutdown.

[0032] (4) In the case of the backup power storage system 100, if the drive current for the discharge FET 37 is supplied from the battery 34 in a fully charged standby state, the capacity of the battery 34 will decrease. Therefore, by supplying the drive current for the discharge FET 37 from somewhere other than the battery 34 (the device 10 side) in a fully charged standby state, it is possible to eliminate the current supply from the battery 34. Furthermore, according to this embodiment, in a fully charged standby state, the capacity of the battery 34 is unlikely to decrease (circuit configuration 30A (FIG. 2)) or does not decrease (circuit configuration 30B (FIG. 3)), so the recharge interval for the battery 34 can be lengthened.

[0033] (5) According to this embodiment, the charge control unit is the charge FET 33, the discharge control unit is the discharge FET 37, and the backflow prevention unit is the ideal diode 35. Therefore, the arrangement of the charge FET 33, the discharge FET 37, and the ideal diode 35 can simply and efficiently reduce the power consumption of the battery 34 in standby mode.

[0034] (6) When a large current is required, the batteries 34 may be connected in parallel (for example, four in series and six in parallel). According to this embodiment, the power consumption of the batteries 34 in standby mode can be reduced, and therefore, the greater the number of batteries 34 connected in parallel, the greater the effect of reducing the power consumption of the batteries 34.

[0035] (7) Comparison with the above-mentioned patent documents is as follows: The technology of this embodiment is a technology that prevents the battery 34 from decreasing even in the standby state by providing a circuit network that can supply the drive current for the discharge FET 37 from a source other than the battery 34 when the power storage system 100 is in the standby state.

[0036] On the other hand, the technology of Patent Document 1 is a technology for preventing a power drop by using a capacitor, and the method is different from that of the technology of this embodiment. Furthermore, the technology of Patent Document 2 is a technology that suppresses the capacity decrease of the drive battery by using a system that includes a drive battery and an auxiliary battery, and in this respect too, the method is different from that of the technology of this embodiment.

[0037] Furthermore, the technology of Patent Document 3 is a technology in which a relay is operated according to the current value to perform driving, and the current value is suppressed by driving the battery, which is also a technology different from the technology of this embodiment. Furthermore, the technology of Patent Document 4 is a technology for reducing power consumption due to driving by switching the driving element, which is also different from the technology of this embodiment.

[0038] [Modifications] The present invention is not limited to the above-described embodiment, and can be practiced in various modified forms. (1) The charge control unit has been described using the charge FET 33 as an example, but may be other electronic components or circuits. The discharge control unit has been described using the discharge FET 37 as an example, but may be other electronic components or circuits. The backflow prevention unit has been described using the ideal diode 35 as an example, but may be other electronic components or circuits.

[0039] (2) Either circuit configuration 30A or circuit configuration 30B can be adopted depending on the type of device 10. Whichever circuit configuration is adopted, power consumption of battery 34 in the standby state can be reduced more than that of circuit configuration 30C.

[0040] (3) In the circuit configuration 30B of Figure 3, an example has been described in which the GND of the control IC 36 of the ideal diode 35 is connected to the drain of the drive FET 38 of the discharge FET 37. However, other connection configurations may be adopted as long as no current flows from the control IC 36 to the GND during shutdown. [Explanation of symbols]

[0041] 10 equipment 11 Power supply section 12 Load section 20, 40 Electricity storage device 30A, 30B, 30C circuit configuration 31 DC / DC converter 32 12V-5V circuit 33 Charge FET 34 Battery 35 Ideal Diode 36 Control IC 37 Discharge FET 38 Drive FET 100 Energy Storage System

Claims

1. The device, a power storage device connected to the device, the device includes a power supply unit and a load unit that consumes power from the power supply unit; an input side of the power storage device connected to the power supply unit and an output side of the power storage device connected to the load unit; the power storage device includes a charge control unit, a battery, a discharge control unit, and a backflow prevention unit that prevents a current from flowing back from the device to the battery; The voltage on the output side is higher than the voltage of the battery, The power storage system, wherein the discharge control unit is disposed on the output side of the backflow prevention unit.

2. The power storage system according to claim 1, the backflow prevention unit includes a control unit that controls the backflow prevention unit, the discharge control unit includes a drive control unit that drives the discharge control unit, The control unit is connected to the drive control unit.

3. The power storage system according to claim 1, the charge control unit is a charge FET, the discharge control unit is a discharge FET, The power storage system is characterized in that the backflow prevention unit is an ideal diode.

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