Protection device for power storage device, power storage device, and protection method for power storage device

Abstract

To provide a protection device and a protection method that improve safety of a power storage device while reducing the number of power FETs used.SOLUTION: A protection device for a power storage device 20 includes a cutoff circuit 70 that cuts off a current of a power storage cell 3 of an assembled battery 30, and a control unit 100 that controls the cutoff circuit 70. The interruption circuit 70 includes a first interruption element 71 and a second interruption element 75 connected in series, the first interruption element 71 is a power FET, and the second interruption element 75 is fuse elements 76 and 77 including a heat generation element 78. The power storage cell 3 has two protection regions against overcharge and / or overdischarge, i.e., a degradation region where the performance is degraded due to repeated use, and an unsafe region where it is difficult to guarantee the performance unless the current is interrupted. The control unit 100 protects the deteriorated region by the power FET71 and protects the unsafe region by the fuse elements 76 and 77 including the heating elements 78.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a technique for protecting an electricity storage device. [Background technology]

[0002] One type of protection device for an electricity storage device is a breaker circuit. A relay or a FET may be used in the breaker circuit. Patent Document 1 discloses a breaker circuit using a FET. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-166454 Summary of the Invention [Problem to be solved by the invention]

[0004] When configuring the cutoff circuit of an energy storage device using power FETs, it is common to have two power FETs, 331 and 335, one for cutting off discharge and the other for cutting off charge, connected in series, as shown in Fig. 9. If a current exceeding the withstand capacity flows through the power FETs 331 and 335, the power FETs 331 and 335 must be connected in parallel to avoid thermal breakdown, which poses a problem of increasing the number of power FETs 331 and 335 used.

[0005] In addition, energy storage cells may have two protection regions against overcharging and / or over-discharging: a degradation region where performance deteriorates with repeated use, and an unsafe region where performance cannot be guaranteed unless the current is cut off. It is desirable to improve the safety of energy storage cells that have two protection regions.

[0006] An object of the present invention is to improve the safety of a power storage device while reducing the number of power FETs used. [Means for solving the problem]

[0007] A protection device for an energy storage device including one energy storage cell or two or more energy storage cells connected in series includes an interruption circuit that interrupts current to the energy storage cell and a control unit that controls the interruption circuit. The interruption circuit includes a first interruption element and a second interruption element connected in series, the first interruption element being a power FET, and the second interruption element being a fuse element equipped with a heating element. The energy storage cell has two protection regions against overcharging and / or over-discharging: a degradation region in which performance deteriorates with repeated use, and an unsafe region in which performance is difficult to ensure unless the current is interrupted. The control unit provides protection against the degradation region using the power FET, and protection against the unsafe region using the fuse element equipped with the heating element. [Effects of the Invention]

[0008] The present invention can improve the safety of the power storage device while reducing the number of power FETs used. [Brief explanation of the drawings]

[0009] [Figure 1] Side view of a motorcycle [Figure 2] Block diagram of a motorcycle battery [Figure 3] Exploded perspective view of the battery [Figure 4] Battery Schematic [Figure 5] Illustration of the protected area [Figure 6] Battery Schematic [Figure 7] Battery Schematic [Figure 8] Battery Schematic [Figure 9] Battery circuit diagram (comparison example) DETAILED DESCRIPTION OF THE INVENTION

[0010] (Outline of this embodiment) (1) A protection device for a power storage device including one storage cell or two or more storage cells connected in series includes a shutdown circuit that shuts off current to the storage cell and a control unit that controls the shutdown circuit. The shutdown circuit includes a first shutdown element and a second shutdown element connected in series, the first shutdown element being a power FET, and the second shutdown element being a fuse element equipped with a heating element. The storage cell has two protection regions against overcharging and / or over-discharging: a degradation region in which performance deteriorates with repeated use, and an unsafe region in which performance cannot be guaranteed unless the current is shut off. The control unit protects against the degradation region using the power FET, and protects against the unsafe region using the fuse element equipped with the heating element.

[0011] According to (1), the number of power FETs used can be reduced (halved) compared to a shutdown circuit in which two power FETs are connected in series. This is particularly effective when power FETs are connected in parallel, as the number of power FETs required can be reduced significantly. In addition, the two-stage protection of the power FET and fuse element reduces the risk of the storage cell reaching an unsafe area.

[0012] (2) In the protection device described in (1) above, the power FET may be a switch that cuts off discharge of the storage cell. The control unit may open the power FET when the storage cell falls below a first threshold voltage V1 and reaches a first deterioration region. When the storage cell falls below a second voltage threshold V2 lower than the first threshold voltage V1 and reaches a first unsafe region, the control unit may cause the heating element to generate heat and blow the fuse element.

[0013] According to (2), when the storage cell reaches the first degradation region, the power FET is opened to cut off discharge from the storage cell to the load and dark current. This suppresses a voltage drop in the storage cell and ensures time until the storage cell reaches the first unsafe region. After that, when the storage cell reaches the first unsafe region, the heating element is heated to blow the fuse element. By blowing the fuse element, use of the storage cell that has reached the first unsafe region can be restricted, improving safety. With this configuration, by limiting discharge with the power FET after transition to the first degradation region, the time the storage cell remains in the degradation region can be extended, and when the storage cell transitions to the first unsafe region, the fuse element can shut off the storage cell.

[0014] (3) In the protection device described in (2) above, when the storage cell reaches the first unsafe region, the control unit may store information that the storage cell has reached the first unsafe region in a recording unit or a recording circuit. When a charging voltage is applied from a charger and the voltage of the storage device reaches a voltage capable of melting the fuse element, the control unit may melt the fuse element by applying a voltage to the heating element.

[0015] According to (3), even if the fuse element cannot be blown due to a drop in the voltage of the storage cell (in the case of insufficient heat generation), the voltage recovery due to charging can be used to ensure the heat generation of the heat generating element and blow the fuse element.

[0016] (4) In the protection device described in (2) or (3) above, when the storage cell exceeds a third threshold voltage V3 and reaches a second degradation region, the control unit may notify a charger that charges the storage cell that the storage cell has reached the second degradation region, and stop or limit charging of the storage cell.

[0017] According to (4), when the storage cell reaches the second degradation region, charging of the storage cell is stopped or limited, thereby suppressing an increase in the voltage of the storage cell and suppressing the progression of degradation.

[0018] (5) In the protection device described in (4) above, the control unit may cause the heating element to generate heat and melt the fuse element when the storage cell exceeds a fourth threshold voltage V4 that is higher than the third threshold voltage V3 and reaches a second unsafe area.

[0019] According to (5), if the storage cell reaches the second unsafe area, the fuse element is immediately blown. By blowing the fuse element, the use of the storage cell that has reached the second unsafe area can be restricted, thereby improving safety.

[0020] (6) In the protection device according to any one of (1) to (5), the control unit may open the power FET when the temperature of the power FET reaches a threshold temperature during discharging of the storage cell, and may close the power FET when charging is detected while the power FET is open.

[0021] According to (6), if the power FET reaches the threshold temperature during the discharge of the storage cell, the discharge can be shut off by opening the power FET. Shutting off the discharge prevents the temperature of the power FET from rising further and causing abnormal heat generation. If charging is then detected, the power FET can be immediately closed to prevent charging current from flowing through the parasitic diode of the power FET, which can cause heat generation failure.

[0022] (7) In the protection device described in any one of (1) to (6) above, when the temperature of the power FET reaches a threshold temperature while the storage cell is being charged, the control unit may notify a charger that charges the storage cell that the temperature of the storage cell has reached the threshold temperature, and stop or limit charging of the storage cell.

[0023] According to (7), if the power FET reaches the threshold temperature while the storage cell is being charged, the charging of the storage cell can be stopped or limited to prevent the temperature of the power FET from further increasing and causing abnormal heat generation.

[0024] (8) The protection device described in any one of (1) to (7) above may further include a switch that switches the melting path of the fuse element having the heat generating element between a first path powered by the storage cell and a second path powered by the charger that does not pass through the storage cell.

[0025] According to (8), by selecting the second path, the storage cell can be separated from the melting path of the fuse element. When the storage cell reaches the first unsafe area, it becomes possible to melt the fuse element without charging the storage cell.

[0026] (9) The present invention can be applied to a power storage device including one power storage cell or two or more power storage cells connected in series and the protection devices of (1) to (8). The power storage device may be an auxiliary device mounted on an electric vehicle.

[0027] The techniques described in (1) to (9) can be applied to a method for protecting a power storage device.

[0028] <Embodiment 1> 1. Battery structure explanation 1, a battery 20 (an example of a power storage device) according to this embodiment is for use in a motorcycle and is mounted on a motorcycle 10. The battery 20 has a rated voltage of 12 volts (V) and can be used to replace (for example, as a retrofit) conventional lead-acid batteries.

[0029] As shown in Figure 2, a starter 10A, a vehicle charger 10B such as an alternator, and accessories 10C (headlights, a car navigation system, etc.) mounted on a motorcycle 10 are connected to a battery 20. The battery 20 supplies 12V power to the starter 10A to start the engine. The battery 20 is charged by the vehicle charger 10B while the engine is running. The starter 10A and accessories 10C are loads on the battery 20.

[0030] 3, the battery 20 includes a management unit 53, a plurality of storage cells 3, and a rectangular parallelepiped storage case 40 that houses them. The storage cells 3 may be battery cells such as lithium ion secondary batteries, or may be electrochemical cells such as capacitors.

[0031] Four storage cells 3 are connected in series to form the assembled battery 30. Alternatively, some of the storage cells 3 may be connected in parallel. For example, the assembled battery 30 may have eight storage cells 3 connected in two parallel connections and four in series, or twelve storage cells 3 connected in three parallel connections and four in series.

[0032] The storage case 40 is made of synthetic resin. The storage case 40 includes a case body 41, a lid 42 that closes the opening of the case body 41, a storage section 43 provided in the lid 42, a cover 44 that covers the storage section 43, an inner lid (bus bar frame) 45, and a partition plate 46. The inner lid 45 and the partition plate 46 do not necessarily have to be provided. The energy storage cells 3 are inserted between the partition plates 46 of the case body 41.

[0033] A plurality of metal bus bars 47 (conductive members) are placed on the inner lid 45. The inner lid 45 is placed near the terminal surface on which the cell terminals 32 of the storage cells 3 are provided, and the adjacent cell terminals 32 of adjacent storage cells 3 are connected by the bus bars 47, so that the storage cells 3 are connected in series.

[0034] The storage section 43 is box-shaped and has a protrusion 43a that protrudes outward from the center of one long side in a plan view. A positive terminal (positive external terminal) 51 and a negative terminal (negative external terminal) 52 made of metal such as a lead alloy are provided on both sides of the protrusion 43a on the lid section 42. A management unit 53 is stored in the storage section 43.

[0035] The management unit 53 is connected to the energy storage cells 3 via wiring members and bus bars 47 (not shown). Instead of being housed in the housing 43, the management unit 53 may be disposed adjacent to the assembled battery 30, for example, above or to the side of the assembled battery 30. The management unit 53 may have multiple circuit boards.

[0036] The energy storage cell 3 includes a hollow rectangular parallelepiped case 31 and a pair of cell terminals 32, 32 with opposite polarities provided on one side (terminal surface, top surface) of the case 31. The case 31 accommodates an electrode assembly 33 formed by stacking a positive electrode, a separator, and a negative electrode, and an electrolyte (electrolytic solution) not shown.

[0037] Although not shown in detail, the electrode assembly 33 is constructed by stacking a sheet-shaped positive electrode and a sheet-shaped negative electrode with two sheet-shaped separators in between and winding them (vertical or horizontal). The separators are formed from a porous resin film. Examples of the porous resin film that can be used include porous resin films made of resins such as polyethylene (PE) and polypropylene (PP).

[0038] The positive electrode is an electrode plate in which a positive electrode active material layer is formed on the surface of a long strip-shaped positive electrode substrate made of, for example, aluminum, an aluminum alloy, or the like. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material used in the positive electrode active material layer can be a material capable of absorbing and releasing lithium ions. The positive electrode active material is, for example, LiFePO4, but is not limited thereto, and so-called ternary positive electrode active materials may also be used. The positive electrode active material layer may further contain a conductive additive, a binder, etc.

[0039] The negative electrode is an electrode plate in which a negative electrode active material layer is formed on the surface of a long strip-shaped negative electrode substrate made of, for example, copper or a copper alloy. The negative electrode active material layer contains a negative electrode active material. The negative electrode active material can be a material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include graphite, hard carbon, and soft carbon. The negative electrode active material layer may further contain a binder, a thickener, and the like.

[0040] The electrolyte housed in the housing case 40 together with the electrode assembly 33 can be the same as that used in conventional lithium-ion secondary batteries. For example, an electrolyte containing a supporting salt in an organic solvent can be used. As the organic solvent, for example, an aprotic solvent such as carbonates, esters, or ethers can be used. As the supporting salt, for example, a lithium salt such as LiPF6, LiBF4, or LiClO4 can be suitably used. The electrolyte may contain various additives such as a gas generating agent, a film-forming agent, a dispersant, or a thickener.

[0041] FIG. 3 shows a prismatic lithium ion battery including a wound electrode assembly 33 as an example of the storage cell 3. Alternatively, the storage cell 3 may be a cylindrical lithium ion battery or a laminated (pouch) lithium ion battery. The storage cell 3 may also be a lithium ion battery including a laminated electrode assembly. The storage cell 3 may also be an all-solid-state lithium ion battery using a solid electrolyte.

[0042] 2. Description of the Electrical Configuration of Battery 20 4 is a circuit diagram of the battery 20. The battery 20 includes a battery pack 30, a shunt resistor 60, a cutoff circuit 70, a drive circuit 80, a monitoring IC 100, and a recording unit 105. These circuits 60 to 105 are provided on the management unit 53, for example.

[0043] The battery pack 30 is composed of four storage cells 3 connected in series. The positive electrode of the battery pack 30 is connected to a positive terminal 51 via a power line 53A. The negative electrode of the battery pack 30 is connected to a negative terminal 52 via a power line 53B.

[0044] The battery 20 may be provided with a detection line that detects the voltage of the positive terminal 51. The monitoring IC 100 can detect the connection of an external charger based on the voltage of the positive terminal 51. The external charger is a charger that uses an external power source separate from the vehicle.

[0045] The shunt resistor 60 is disposed on the power line 53A. The shunt resistor 60 is a detection unit that detects the current of the battery 20. It is also possible to determine whether the battery 20 is being charged or discharged based on the polarity of the current.

[0046] The interruption circuit 70 is disposed on the power line 53B and is composed of a power FET 71 and an SCP 75.

[0047] The power FET (field effect transistor) 71 is an N-channel. The power FET 71 has a source connected to the negative electrode of the battery pack 30 and a drain connected to the SCP 75. The power FET 71 has a parasitic diode 72. The parasitic diode 72 charges in the forward direction and discharges in the reverse direction.

[0048] The power FET 71 is a discharge cutoff switch that cuts off the discharge of the battery 20. When the battery 20 is normal, the power FET 71 is controlled to be CLOSE.

[0049] The SCP (self-control protector) 75 is composed of fuse elements 76 and 77 connected in series and a heating element 78. The heating element 78 is, for example, a resistor. One end of the heating element 78 is connected to a connection point A between the fuse elements 76 and 77, and the other end is connected to a drive circuit 80.

[0050] The fuse elements 76 and 77 melt when a current exceeds their tolerance, and when heated by the heating element 78, melts when a current falls below their tolerance.

[0051] The drive circuit 80 is a circuit that drives (energizes and generates heat from) the heating element 78. The battery 20 in FIG. 4 uses a FET 81 in the drive circuit 80. The FET 81 is a P-channel FET, with its source connected to the positive terminal 51 and its drain connected to the heating element 78. When the battery 20 is normal, the drive circuit 80 is controlled to the off state (non-conducting).

[0052] The interrupter circuit 70 is provided with a temperature sensor 73. The temperature sensor 73 is disposed near the power FET 71 and measures the temperature of the power FET 71 or the ambient temperature.

[0053] The monitoring IC 100 monitors the state of the battery 20. Specifically, it is connected to each storage cell 3 of the battery pack 30 via a signal line, and monitors the cell voltage Vs of each storage cell 3. In addition, the current of the battery 20 can be monitored from the voltage across the shunt resistor 60, and the temperature of the power FET 71 can be monitored from the output of the temperature sensor 73.

[0054] When the monitoring IC 100 detects an abnormality in the battery 20, it executes a protection operation (details of which will be described later) to protect the battery 20.

[0055] The monitoring IC 100 is also provided with a recording unit 105. The recording unit 105 is a non-volatile memory such as an EEPROM, and records the history of abnormalities and protective operations of the battery 20. The monitoring IC 100 is also connected to the vehicle charger 10B via a communication line Lc and a communication terminal 55. The monitoring IC 100 is an example of the "control unit" of the present invention.

[0056] 3. Protection area of ​​the energy storage cell FIG. 5 is a diagram showing the protection ranges of the storage cell 3. The storage cell 3 has two protection ranges against overcharging and over-discharging. One is a degradation range in which performance deteriorates with repeated use. The performance deterioration is, for example, a decrease in output due to an increase in internal resistance. The other is an unsafe range in which performance cannot be guaranteed unless the current is cut off. One storage cell with these characteristics is a lithium-ion secondary battery cell.

[0057] As shown in Figure 5, the range from V1 to V3 is the normal operating range. The range from V1 to V2 is the first degradation region, and the range below V2 is the first unsafe region. V1 corresponds to the "first threshold voltage" of the present invention, and V2 corresponds to the "second threshold voltage" of the present invention.

[0058] The range from V3 to V4 is the second deterioration region, and the range above V4 is the second unsafe region. V3 corresponds to the "third threshold voltage" of the present invention, and V4 corresponds to the "fourth threshold voltage" of the present invention. Note that V4>V3>V1>V2.

[0059] 4. Battery protection operation <Over-discharge protection (1st deterioration area)> During discharge, when the cell voltage Vs of any of the storage cells 3 becomes lower than V1, the monitoring IC 100 determines that the first deterioration region has been reached. Then, the monitoring IC 100 sends a blocking signal S2 to the power FET 71, switching the power FET 71 from CLOSE to OPEN.

[0060] This makes it possible to cut off discharge to the loads 10A and 10C and dark current, thereby suppressing a drop in the cell voltage Vs and ensuring time for the battery 20 to reach the first unsafe area. Dark current is current consumed by the battery 20 while the motorcycle 10 is parked, and is caused by standby power of the load 10C and power consumed within the battery.

[0061] Furthermore, if connection of an external charger or charging is detected while the power FET 71 is open, the monitoring IC 100 switches the power FET 71 from open to closed.

[0062] By returning the power FET 71 to CLOSE, it is possible to prevent a charging current exceeding the tolerance of the parasitic diode 72 from flowing and causing the parasitic diode 72 to overheat abnormally.

[0063] <Over-discharge protection (1st unsafe area)> During discharge, if the cell voltage Vs of any of the storage cells 3 falls below V2, the monitoring IC 100 determines that the first unsafe region has been reached. Then, the monitoring IC 100 sends a shutoff signal S1 to the drive circuit 80 to turn on the drive circuit 80. When the drive circuit 80 is turned on, a current flows using the battery pack 30 as a power source, and the heating element 78 generates heat.

[0064] Heat generated by heating element 78 melts fuse elements 76 and 77, cutting off power line 53B of battery 20. Cutting off power line 53B prevents charging and discharging (use is prohibited), protecting battery 20.

[0065] Depending on the number of storage cells 3 connected in series, there is a possibility that a sufficient voltage to blow the fuse elements 76, 77 may not be secured when the voltage of the battery pack 30 drops due to discharge.

[0066] When the monitoring IC 100 detects that the first unsafe area has been reached, the monitoring IC 100 may record in the recording unit 105 information that the first unsafe area has been reached, without immediately outputting the shutoff signal S1 to the drive circuit 80.

[0067] Then, when the voltage of battery 20 recovers to a voltage that can blow fuse elements 76, 77 by charging with an external charger, a cutoff signal S1 may be output to drive circuit 80 to blow fuse elements 76, 77 and cut off power line 53B. This makes it possible to prohibit use of battery 20 that has entered the first unsafe region.

[0068] The voltage of the battery pack 30 may be the voltage of the battery 20, or the voltage of the positive terminal 51 may be the voltage of the battery 20.

[0069] <Overcharge protection (second deterioration area)> During charging, when the cell voltage Vs of any of the storage cells 3 becomes higher than V3, the monitoring IC 100 determines that the second deterioration region has been reached. Then, the monitoring IC 100 notifies the vehicle charger 10B that the second deterioration region has been reached.

[0070] Upon receiving the notification, the vehicle charger 10B stops or limits charging. The limit on charging may be to reduce the charging voltage or the charging current. By stopping or limiting charging, it is possible to suppress a voltage rise in the storage cells 3.

[0071] <Overcharge protection (second unsafe area)> During charging, if the cell voltage Vs of any of the storage cells 3 becomes higher than V4, the monitoring IC 100 determines that the second unsafe region has been reached. Then, the monitoring IC 100 sends a shutoff signal S1 to the drive circuit 80 to turn on the drive circuit 80. When the drive circuit 80 is turned on, current flows using the battery pack 30 as a power source, and the heating element 78 generates heat.

[0072] Heat generated by heating element 78 melts fuse elements 76 and 77, cutting off power line 53B of battery 20. Cutting off power line 53B prevents charging and discharging (disabled state), protecting battery 20.

[0073] <Overcurrent protection> If a current exceeding the tolerance flows through fuse elements 76 and 77 of SCP 75, fuse elements 76 and 77 will blow and cut off power line 53B. In addition, to avoid a failure in short mode of power FET 71, fuse elements 76 and 77 of SCP 75 may be selected to blow before power FET 71 suffers a short circuit failure due to heat generated by the current.

[0074] <Overtemperature protection (during discharge)> If the power FET 71 reaches the temperature threshold during discharge, the monitoring IC 100 sends a shutoff signal S2 and switches the power FET 71 from CLOSE to OPEN, thereby shutting off the discharge current. The temperature threshold may be set by adding a safety factor to the withstand temperature of the power FET 71. By adding a safety factor, the discharge current can be shut off before the power FET 71 reaches the withstand temperature.

[0075] If the monitoring IC 100 detects connection of an external charger or charging while the power FET 71 is open, it switches the power FET 71 from open to closed. By returning the power FET 71 to closed, it is possible to prevent the parasitic diode 72 from generating abnormal heat.

[0076] <Overtemperature protection (when charging)> If the power FET 71 reaches the temperature threshold during charging, the monitoring IC 100 notifies the vehicle charger 10B of the over-temperature. Upon receiving the over-temperature notification, the vehicle charger 10B stops or limits charging. The charging limit may be to reduce the charging voltage or the charging current. By stopping or limiting charging, it is possible to suppress the temperature rise of the power FET 71.

[0077] In the circuit configuration of Figure 4, when the power FET 71 is turned off and the SCP 75 is blown, the monitoring IC 100 and the vehicle charger 10B no longer share a common GND, which may cause communication to become unstable. However, while the power FET 71 is turned off, the battery 20 is on standby for charging, and there is no need to control charging. Also, when the SCP 75 is blown, the battery 20 is in a disabled state. Therefore, even if the communication state between the vehicle charger and the battery is unstable, it is thought that there will be little impact on the battery 20.

[0078] 5.Effects According to the first embodiment, the number of power FETs 71 used can be halved compared to when the interrupter circuit is configured with two power FETs 331, 335 (see FIG. 9). In particular, in applications where a relatively large current flows, such as for starting an engine, when it is necessary to connect power FETs 71 in parallel to reduce the current per transistor, the number of power FETs 71 can be reduced significantly, which is effective.

[0079] Furthermore, the power FET 71 and the SCP 75 provide two-stage protection, that is, protection in the deteriorated region and the unsafe region, thereby reducing the risk that the storage cell 3 will reach the unsafe region. As a result, the safety of the battery 20 is improved.

[0080] <Embodiment 2> In the battery 20 of the first embodiment, the interrupting circuit 70 is disposed at the negative electrode of the assembled battery 30. In the battery 120 of the second embodiment, the interrupting circuit 130 is disposed at the positive electrode of the assembled battery 30.

[0081] 6, the shutoff circuit 130 is made up of a power FET 131 and an SCP 135. The power FET 131 is an N-channel. The drain of the power FET 131 is connected to the shunt resistor 60, and the source of the power FET 131 is connected to the SCP 135.

[0082] The parasitic diode 132 of the power FET 131 has a forward charging direction and a reverse discharging direction. The power FET 131 is a discharge cutoff switch that cuts off the discharge of the battery 20. A temperature sensor 133 measures the temperature of the power FET 131 or the ambient temperature.

[0083] The SCP 135 has a pair of fuse elements 136 and 137 and a heating element 138. The pair of fuse elements 136 and 137 have one end connected to the drain of the power FET 131 and the other end connected to the positive terminal 51.

[0084] 6 uses an FET 141 in the drive circuit 140. The FET 141 is an N-channel FET, with its source connected to the negative terminal 52 and its drain connected to the heating element 138.

[0085] The monitoring IC 100 outputs a shutoff signal (a signal that turns on the FET 141) S1, which energizes the heating element 138 to generate heat, thereby melting the fuse elements 136 and 137.

[0086] Furthermore, the discharge of the battery 20 can be cut off by outputting a cutoff signal S2 from the monitoring IC 100 via the boost circuit (for example, a charge pump) 107 and switching the power FET 131 from CLOSE to OPEN.

[0087] <Embodiment 3> The third embodiment differs from the second embodiment in that a switch 240 is added to the battery 220 and a switch 250 is added to the external charger 10D (see FIG. 7).

[0088] The switch 240 is connected in series with the drive circuit 140. In the third embodiment, a FET 241 is used as the switch 250. The FET 241 is an N-channel FET, and has a drain connected to the source of the drive circuit 140 and a source connected to the negative terminal 52.

[0089] A connection point B between the drive circuit 140 and the switch 240 is connected via a relay terminal 56 to the external charger 10D.

[0090] The switch 250 is provided in the external charger 10D and can switch the connection destination of the external charger 10D between the negative terminal 52 and the relay terminal 56. As shown in Fig. 7, the negative terminal 52 is usually selected as the connection destination of the external charger 10D.

[0091] With the switch 250 selecting the negative terminal 52, when the monitoring IC 100 outputs the shutoff signals S1 and S3 and turns on the drive circuit 140 and the switch 240, as shown in FIG. 7, the heating element 138 is energized via the first path L1 powered by the battery pack 30, thereby melting down the SCP 135.

[0092] Furthermore, as shown in FIG. 8, when the switch 250 selects the relay terminal 56, if the monitoring IC 100 outputs only the shutoff signal S1 to turn on the drive circuit 140 and turn off the switch 240, the heating element 138 is energized via the second path L2 powered by the external charger 10D, and the SCP 135 can be blown out.

[0093] In the battery 220 of the third embodiment, when over-discharge protection is performed (when reaching the first unsafe area is detected), the monitoring IC 100 and the external charger 10D share information and switch to the second path L2, thereby isolating the over-discharged battery pack 30 from the current path. This makes it possible to blow out the SCP 135 using the charger output, regardless of the battery pack 30.

[0094] 7 and 8, the recording unit 105 is omitted, but the battery 220 may be configured to include the recording unit 105, similar to the batteries 20 and 120.

[0095] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0096] (1) In the above-described first to third embodiments, the batteries 20, 120, and 220 are for use in motorcycles. The applications of the batteries 20, 120, and 220 are not limited to motorcycles. They may also be used in four-wheeled vehicles, or as accessories mounted on electric vehicles. They may also be used for applications other than automobiles and vehicles.

[0097] (2) In the above-described first to third embodiments, the batteries 20, 120, and 220 are each a multi-cell battery. However, the batteries 20, 120, and 220 may be a single cell battery.

[0098] (3) In the above embodiment, the power FETs 71 and 131 are used for cutting off discharge. However, the power FETs 71 and 131 may be used for cutting off charge.

[0099] If the power FETs 71, 131 are used to cut off charging, the charging can be cut off by opening the power FETs 71, 131 when the cell voltage Vs reaches V3 during charging (protection against the second degradation region). Furthermore, when the cell voltage Vs reaches V4, the SCPs 75, 135 are blown open, prohibiting the use of the batteries 20, 120, 220 (protection against the second unsafe region). This is thought to be effective for systems or cell characteristics where the second degradation region is narrow and quickly reaches the second unsafe region.

[0100] <Usage example> The auxiliary battery installed in an EV vehicle can be constantly charged by a converter such as a DC-DC converter, so there is little possibility of over-discharging. For the auxiliary battery of an EV vehicle, a cutoff circuit combining a power FET 71 for charge cutoff and an SCP 75 can be used.

[0101] (4) In the first to third embodiments, the recording unit 105 is a nonvolatile memory, but it can be replaced by a hardware latch circuit (recording circuit).

[0102] (5) In the above-described first to third embodiments, the storage cell 3 has a degradation region and an unsafe region with respect to overcharging and overdischarging. The storage cell 3 may have a characteristic of having a degradation region and an unsafe region only with respect to overdischarging (a characteristic of having only either a degradation region or an unsafe region with respect to overcharging), or a characteristic of having a degradation region and an unsafe region with respect to overcharging (a characteristic of having only either a degradation region or an unsafe region with respect to overdischarging). Furthermore, the storage cell 3 is not limited to a lithium-ion secondary battery cell, and any cell having the above-described characteristics may be used. [Explanation of symbols]

[0103] 3 Energy storage cells 20, 120, 220 Battery (storage device) 30 battery packs 60 Shunt resistor 70, 130 Breaking circuit 71, 131 Power FET (first cutoff element) 75, 135 SCP (secondary blocking element) 76, 77, 136, 137 fuse elements 78, 138 Heating element 80, 140 drive circuit 100 Monitoring IC (control unit) 105 Recording section

Claims

1. A protection device for a storage device including one storage cell or two or more storage cells connected in series, an interruption circuit that interrupts the current of the storage cell; a control unit that controls the interruption circuit, the interruption circuit includes a first interruption element and a second interruption element connected in series; the first blocking element is a power FET, the second interrupting element is a fuse element having a heating element, The storage cell is protected against overcharging and / or over-discharging. It has two protection zones: a degradation zone where performance deteriorates with repeated use, and an unsafe zone where performance cannot be guaranteed unless the current is cut off. The control unit provides protection against the deteriorated region by the power FET, and provides protection against the unsafe region by the fuse element including the heating element.

2. The protection device for the storage device according to claim 1, the power FET is a switch that cuts off discharge of the storage cell, the control unit opens the power FET when the voltage of the storage cell falls below a first threshold voltage V1 and reaches a first deterioration region; When the storage cell falls below a second voltage threshold V2 lower than the first threshold voltage V1 and reaches a first unsafe region, the protection device causes the heating element to generate heat and melts the fuse element.

3. The protection device for the storage device according to claim 2, When the storage cell reaches the first unsafe area, the control unit stores information that the storage cell has reached the first unsafe area in a recording unit or a recording circuit, A protection device that applies a charging voltage from a charger and, when the voltage of the storage device reaches a voltage that can melt the fuse element, melts the fuse element by applying a voltage to the heating element.

4. The protection device for the storage device according to claim 2 or 3, When the storage cell exceeds a third threshold voltage V3 and reaches a second degradation region, the control unit notifies a charger that charges the storage cell that the storage cell has reached the second degradation region, and stops or limits charging of the storage cell.

5. The protection device for the storage device according to claim 4, The control unit causes the heating element to generate heat and melts the fuse element when the storage cell exceeds a fourth threshold voltage V4 that is higher than the third threshold voltage V3 and reaches a second unsafe area.

6. The protection device for the storage device according to claim 1, the control unit opens the power FET when the temperature of the power FET reaches a threshold temperature during discharging of the power storage cell; A protection device that closes the power FET when charging is detected while the power FET is open.

7. The protection device for the storage device according to claim 1, When the temperature of the power FET reaches a threshold temperature while the storage cell is being charged, the control unit notifies a charger that charges the storage cell that the temperature of the storage cell has reached the threshold temperature, and stops or limits charging of the storage cell.

8. The protection device for the storage device according to claim 1, a protection device including a switch that switches the melting path of the fuse element having the heating element between a first path powered by the storage cell and a second path powered by a charger that does not pass through the storage cell.

9. An electricity storage device, One storage cell or two or more storage cells connected in series; A power storage device comprising: the protection device according to claim 1 or 2.

10. A method for protecting an electricity storage device, comprising: The power storage device includes one power storage cell or two or more power storage cells connected in series, and an interruption circuit that interrupts a current of the power storage cell, The storage cell has two protection regions against overcharging and / or over-discharging: a degradation region in which performance deteriorates with repeated use, and an unsafe region in which performance cannot be guaranteed unless the current is cut off; the interruption circuit includes a first interruption element and a second interruption element connected in series; the first interrupting element is a power FET, and the second interrupting element is a fuse element having a heat generating element, The protection against the degradation region is provided by the power FET; A method for protecting an electricity storage device, wherein protection against the unsafe area is performed by the fuse element having the heating element.

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