Battery shut-off unit and battery shut-off method

Abstract

A battery shut-off unit (100) comprises a battery positive electrode side terminal (t1) to which a positive electrode terminal of a battery is connected; a load positive electrode side terminal (t2) to which a positive electrode terminal of a load is connected; a battery negative electrode side terminal (t3) to which a negative electrode terminal of the battery is connected; a load negative electrode side terminal (t4) to which a negative electrode terminal of the load is connected; a pyro fuse (10) and a melting fuse (20) that are disposed between the battery positive electrode side terminal (t1) and the load positive electrode side terminal (t2) or between the battery negative electrode side terminal (t3) and the load negative electrode side terminal (t4) and that are mutually connected in series; a sensing part (120) that senses a voltage that includes a voltage across the melting fuse (20); and an ignition control part (110) that controls the output of an ignition signal to the pyro fuse (10) on the basis of sensing results from the sensing part (120).

Description

Battery cutoff unit and battery cutoff method

[0001] The present disclosure relates to a battery disconnection unit and a battery disconnection method.

[0002] Patent Document 1 discloses a technique in which a pyrofuse and a relay are provided in a current path, and the pyrofuse is driven in response to electromagnetic repulsion of the relay.

[0003] US Patent Application Publication No. 2019 / 0299787

[0004] The technology disclosed in Patent Document 1 utilizes the electromagnetic repulsion behavior of a relay to drive a pyrofuse. However, because the electromagnetic repulsion behavior is affected by the rate of increase / decrease of the current and variations in the mechanical operation of the relay, it is difficult to accurately detect the electromagnetic repulsion. Furthermore, the voltage generated by the electromagnetic repulsion is lower than the circuit voltage and contains noise, which may lead to false detection of the electromagnetic repulsion. Furthermore, when an impact occurs and the movable terminal of the relay moves, behavior similar to electromagnetic repulsion is exhibited, which may lead to false detection of the electromagnetic repulsion. In other words, when the electromagnetic repulsion behavior of a relay is utilized to drive a pyrofuse, there is a risk of the pyrofuse malfunctioning.

[0005] The battery cutoff unit according to the present disclosure comprises a battery positive terminal to which the positive terminal of the battery is connected, a load positive terminal to which the positive terminal of the load is connected, a battery negative terminal to which the negative terminal of the battery is connected, a load negative terminal to which the negative terminal of the load is connected, a pyro-fuse and a blown fuse that are arranged between the battery positive terminal and the load positive terminal or between the battery negative terminal and the load negative terminal and are connected in series, a voltage detection unit that detects a voltage including the voltage across the blown fuse, and an ignition control unit that controls the output of an ignition signal to the pyro-fuse based on the detection result of the voltage detection unit.

[0006] The battery cutoff method according to the present disclosure is a battery cutoff method executed by a battery cutoff unit, the battery cutoff unit including a battery positive terminal to which the positive terminal of a battery is connected, a load positive terminal to which the positive terminal of a load is connected, a battery negative terminal to which the negative terminal of the battery is connected, a load negative terminal to which the negative terminal of the load is connected, and a pyro-fuse and a blown fuse connected in series between the battery positive terminal and the load positive terminal or between the battery negative terminal and the load negative terminal, the battery cutoff method including a voltage detection step of detecting a voltage including the voltage across the blown fuse, and an ignition control step of controlling the output of an ignition signal to the pyro-fuse based on the detection result in the voltage detection step.

[0007] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to a battery cutoff unit according to one aspect of the present disclosure, malfunction of a pyro-fuse can be suppressed.

[0009] Fig. 1 is a configuration diagram showing an example of a battery cutoff unit according to embodiment 1. Fig. 2 is a diagram for explaining that the arc period becomes longer when a pyrofuse and an ignition control unit are not arranged. Fig. 3 is a diagram for explaining that the arc period becomes shorter when a pyrofuse and an ignition control unit are arranged. Fig. 4 is a configuration diagram showing an example of a battery cutoff unit according to embodiment 2. Fig. 5 is a flowchart showing an example of the operation of the battery cutoff unit according to embodiment 2. Fig. 6 is a flowchart showing an example of a battery cutoff method according to another embodiment.

[0010] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0011] The embodiments described below are all comprehensive or specific examples, and the numerical values, shapes, materials, components, arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0012] (First embodiment) A battery shutoff unit (BDU) according to a first embodiment will be described below.

[0013] FIG. 1 is a configuration diagram showing an example of a battery cutoff unit 100 according to a first embodiment. The battery cutoff unit 100 is used in a vehicle (transportation equipment) that includes a battery, an electronic control unit (ECU), and a load. The ECU is a device for controlling a battery 200, a load 300, and various other components (such as steering, various sensors, communication equipment, and IVI (In Vehicle Infotainment)) that are provided in the vehicle. In addition to the battery cutoff unit 100, FIG. 1 also shows the battery 200, an LV battery 400, an ECU 500, and the load 300 that are provided in the vehicle. The battery cutoff unit 100 is used in a vehicle such as a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), or a fuel cell vehicle (FCV).

[0014] The battery 200 is a battery that can apply a high voltage of, for example, several hundred volts to the load 300. For example, the battery 200 is a main battery (for example, a lithium ion battery) in an electric vehicle.

[0015] The load 300 is, for example, a motor and an inverter of an electric vehicle. The electric vehicle is propelled by power supplied from the battery 200 to the load 300. In the event of an accident or the like, a large current may flow due to a short circuit in the current path connecting the battery 200 and the load 300, which may cause the battery 200 to smoke or catch fire. Therefore, the battery cutoff unit 100 is used in the vehicle.

[0016] The LV battery 400 is a battery that can apply a low voltage of, for example, several tens of volts to auxiliary equipment, etc. For example, the LV battery 400 is a sub-battery in an electric vehicle and is a lead-acid battery. The LV battery 400 may also be a lithium-ion battery.

[0017] The ECU 500 is a device for controlling the LV battery 400. For example, the ECU 500 is connected to the LV battery 400 and can control the power supply to devices connected to the LV battery 400.

[0018] The battery cutoff unit 100 is a unit for cutting off the current path connecting the battery 200 and the load 300. The current path can be cut off by cutting a wiring (e.g., a bus bar) through which current flows using a pyrotechnic fuse (pyrotechnic fuse, pyrotechnic cutoff device) 10, or by cutting off a blowout fuse 20 that is inserted in the current path and forms part of the current path.

[0019] The battery cutoff unit 100 includes a pyro fuse (active fuse) 10, a blown fuse (passive fuse) 20, relays 30 and 40, a current sensor 50, an ignition control unit (cutoff control unit) 110, and a detection unit (voltage detection unit) 120.

[0020] Pyro fuse 10 is a fuse for cutting off a current path connecting battery 200 and load 300 when a large current flows through the current path due to a short circuit abnormality. Pyro fuse 10 contains an explosive and ignites the explosive based on an ignition signal from outside pyrofuse 10, thereby irreversibly cutting off the current path with the explosive force generated by the ignition of the explosive. Pyro fuse 10 cuts off the current path in response to an ignition signal from ignition control unit 110. Pyro fuse 10 is also called a pyro switch, pyrotechnic switch, or pyroelectric switch.

[0021] The blow fuse 20 is a fuse for cutting off the current path when a large current due to a short circuit occurs in the current path connecting the battery 200 and the load 300. The blow fuse 20 is inserted into the current path to form part of the current path, and when a large current flows in the current path, that is, when a large current flows in the blow fuse 20, an internal element melts to cut off the current path.

[0022] Pyro fuse 10 and blow fuse 20 are connected in series with each other. Pyro fuse 10 and blow fuse 20 are disposed between a battery positive terminal t1 to which the positive terminal of battery 200 is connected and a load positive terminal t2 to which the positive terminal of load 300 is connected, or between a battery negative terminal t3 to which the negative terminal of battery 200 is connected and a load negative terminal t4 to which the negative terminal of load 300 is connected. As shown in Fig. 1 , pyrofuse 10 and blow fuse 20 are disposed, for example, between the battery positive terminal t1 and the load positive terminal t2.

[0023] The relays 30 and 40 are controlled by the vehicle's ECU 500 to switch the current path between conductive and non-conductive. The relays 30 and 40 are operated by receiving power from the LV battery 400. For example, the relays 30 and 40 are in a conductive state when the vehicle ignition is on, and in a non-conductive state when the vehicle is parked. The ECU 500 can control the relays 30 and 40 by controlling the supply of power from the LV battery 400 to the relays 30 and 40. The relay 30 is disposed between the battery positive terminal t1 and the load positive terminal t2, and the relay 40 is disposed between the battery negative terminal t3 and the load negative terminal t4.

[0024] The current sensor 50 is a sensor that detects the current value of a current flowing through a current path connecting the battery 200 and the load 300. For example, the current sensor 50 is a shunt-type sensor (e.g., a shunt resistor) or a sensor such as a Hall element. The current sensor 50 outputs the detection result (e.g., a current value (analog value)) to the detection unit 120.

[0025] The current sensor 50 is disposed between the battery positive terminal t1 and the load positive terminal t2, or between the battery negative terminal t3 and the load negative terminal t4. As shown in Fig. 1, the current sensor 50 is disposed, for example, between the battery negative terminal t3 and the load negative terminal t4.

[0026] The reference potential of the detection unit 120 (also referred to as a sensing board), to which the detection result of the current sensor 50 is output, is often set to the potential of the battery negative terminal t3. For this reason, the current sensor 50 is often disposed between the battery negative terminal t3 and the load negative terminal t4. This is because if the current sensor 50 were disposed between the battery positive terminal t1 and the load positive terminal t2, a high voltage would be applied between the reference potential of the sensing board and the current sensor 50. In other words, from a fail-safe perspective, the reference potential of the sensing board is set to the potential of the battery negative terminal t3, and the current sensor 50 is disposed between the battery negative terminal t3 and the load negative terminal t4. Furthermore, the potential of the battery positive terminal t1 may fluctuate due to deterioration of the battery 200, and depending on the system in which the battery 200 is installed, the potential of the battery negative terminal t3 may be used as a ground potential. Therefore, the reference potential of the sensing board is often set to the potential of the battery negative terminal t3.

[0027] Because current sensor 50 generates heat, if current sensor 50 is disposed between battery negative terminal t3 and load negative terminal t4, and pyrofuse 10 and blown fuse 20 are also disposed between battery negative terminal t3 and load negative terminal t4, pyrofuse 10 and blown fuse 20 may become too hot. One possible solution to the heat generation of current sensor 50 would be to increase the distance between pyrofuse 10 and blown fuse 20 and current sensor 50, but this would require a larger space, resulting in an increase in the size of battery cutoff unit 100. Therefore, by disposing pyrofuse 10 and blown fuse 20 between battery positive terminal t1 and load positive terminal t2, where current sensor 50 is not disposed, it is possible to both miniaturize battery cutoff unit 100 and take measures to prevent heat generation by current sensor 50.

[0028] In addition, the pyroelectric fuse 10 and the blown fuse 20 may be arranged between the battery negative terminal t3 and the load negative terminal t4, and the current sensor 50 may be arranged between the battery positive terminal t1 and the load positive terminal t2.

[0029] Even in this case, by arranging the pyro fuse 10 and the blown fuse 20 between the battery negative terminal t3 and the load negative terminal t4, where the current sensor 50 is not arranged, it is possible to achieve both miniaturization of the battery cut-off unit 100 and measures against heat generation by the current sensor 50.

[0030] Detection unit 120 detects a voltage including at least the voltage across blow fuse 20. Detection unit 120 is an example of a voltage detection unit. As shown in Fig. 1 , detection unit 120 detects, for example, the voltage across a series circuit configured from pyrofuse 10 and blow fuse 20. This makes it possible to detect the voltage across the series circuit, including the voltage across blow fuse 20, even after pyrofuse 10 has ignited.

[0031] The detection unit 120 may convert the voltage detection result into a digital value. Alternatively, the detection unit 120 may acquire the detection result of the current sensor 50 and convert the current detection result into a digital value. The detection unit 120 outputs the detection result (e.g., digital values ​​of the voltage and current) to the ignition control unit 110.

[0032] Ignition control unit 110 controls the output of an ignition signal to pyrofuse 10 based on the detection result of detection unit 120. Specifically, it controls the output of the ignition signal based on the voltage detection result of detection unit 120 and the current detection result of current sensor 50. Ignition control unit 110 is also called a squib module.

[0033] The ignition control unit 110 and the detection unit 120 are realized by, for example, a microcontroller unit (MCU) or the like. Alternatively, the ignition control unit 110 and the detection unit 120 may be realized by, for example, an application specific integrated circuit (ASIC).

[0034] By driving the pyrofuse 10 using both the voltage across the blown fuse 20 and the current flowing in the current path, the pyrofuse 10 can be driven more accurately when an overcurrent occurs, and malfunction of the pyrofuse 10 can be suppressed.

[0035] For example, ignition control unit 110 may output an ignition signal when the product of the voltage value indicated by the detection result of detection unit 120 and the current value indicated by the detection result of current sensor 50 satisfies a predetermined condition. This allows pyrofuse 10 to be driven when the product of the voltage across blow fuse 20 and the current flowing in the current path, i.e., the power generated in blow fuse 20, becomes large. Note that the predetermined condition for this product is set according to the power generated in blow fuse 20 when a large current flows in the current path and the current path should be interrupted.

[0036] For example, ignition control unit 110 may output an ignition signal when the integral of the product of the voltage value indicated by the detection result of detection unit 120 and the current value indicated by the detection result of current sensor 50 satisfies a predetermined condition. This makes it possible to drive pyro-fuse 10 when the integral of the product of the voltage across fuse 20 and the current flowing through the current path, i.e., the amount of power generated in blown fuse 20, becomes large. Note that the predetermined condition for the integral is set according to the amount of power generated in blown fuse 20 when a large current flows through the current path and the current path should be interrupted.

[0037] For example, ignition control unit 110 may output an ignition signal when the change per unit time of the product of the voltage value detected by detection unit 120 and the current value detected by current sensor 50 satisfies a predetermined condition. This allows pyrofuse 10 to be activated when the change per unit time of the product of the voltage across fuse 20 and the current flowing through the current path, i.e., the change per unit time of the power generated in fuse 20, increases. For example, it is possible to estimate that the power generated in fuse 20 will increase in the future from the change per unit time of the power generated in fuse 20. In other words, it is possible to activate pyrofuse 10 in advance, assuming that the power generated in fuse 20 will increase in the future, before the power generated in fuse 20 actually increases. The predetermined condition for the change is set according to the change per unit time of the power generated in fuse 20 when a large current flows through the current path and the current path should be interrupted.

[0038] Ignition control unit 110 may control the output of the ignition signal based on an instruction signal from a vehicle equipped with battery 200 and load 300. This allows pyrofuse 10 to be driven by an instruction from the vehicle. For example, even if no large current is flowing through the current path, pyrofuse 10 can be driven by an instruction from the vehicle when it is determined that the current path should be interrupted.

[0039] Next, the effect achieved by interrupting a current path using pyrofuse 10 will be described with reference to FIGS. 2 and 3. FIG.

[0040] Fig. 2 is a diagram for explaining that the arc period becomes longer when pyrofuse 10 and ignition control unit 110 are not provided. The upper part of Fig. 2 shows the current flowing through the current path and the voltage across blow fuse 20 when pyrofuse 10 is not provided, and the lower part of Fig. 2 shows the power generated in blow fuse 20 when pyrofuse 10 is not provided.

[0041] As shown in the top of Figure 2, as the current flowing in the current path increases due to a short-circuit anomaly, blow fuse 20 begins to blow. As a result, the voltage across blow fuse 20 rises, and the power generated in blow fuse 20 increases. After that, blow fuse 20 begins to blow, making it difficult for current to flow in the current path, reducing the power generated in blow fuse 20, and the voltage across blow fuse 20 becomes the same as the voltage of battery 200. In other words, current stops flowing in the current path, and blow fuse 20 completes the interruption of the current path. As shown in Figure 2, when pyrofuse 10 is not provided, it can be seen that the period from when blow fuse 20 begins to blow to when the current path is completely interrupted (called the arc period) is longer.

[0042] Fig. 3 is a diagram for explaining that the arc period is reduced when pyrofuse 10 and ignition control unit 110 are provided. The upper part of Fig. 3 shows the current flowing in the current path when pyrofuse 10 is provided and the voltage across the series circuit formed by pyrofuse 10 and blow fuse 20, and the lower part of Fig. 3 shows the power generated in blow fuse 20 when pyrofuse 10 is provided.

[0043] As shown in the upper part of Figure 3, as the current flowing through the current path increases due to a short-circuit anomaly, blowout fuse 20 begins to blow. This causes the voltage across blowout fuse 20 to rise, increasing the power generated across blowout fuse 20. Thereafter, when the power generated across blowout fuse 20 satisfies a predetermined condition (e.g., when the power generated across blowout fuse 20 reaches a threshold), ignition control unit 110 activates pyrofuse 10. This instantaneously interrupts the current path, preventing current from flowing through the current path. This reduces the power generated across blowout fuse 20, and the voltage across the series circuit becomes the same as the voltage of battery 200. In other words, current stops flowing through the current path, and pyrofuse 10 completes the interruption of the current path. As shown in Figure 3, when pyrofuse 10 is installed, the arc period from when blowout fuse 20 begins to blow until the current path is completely interrupted is shorter.

[0044] As described above, the voltage across blow fuse 20 rises sharply only when an overcurrent occurs. In other words, the voltage changes significantly when an overcurrent occurs. This makes it easy to detect the voltage across blow fuse 20, reducing the possibility of erroneous detection of the voltage across blow fuse 20. Therefore, by using the voltage across blow fuse 20 to drive pyrofuse 10, pyrofuse 10 can be driven accurately when an overcurrent occurs. This prevents malfunctions of pyrofuse 10, such as pyrofuse 10 not igniting when an overcurrent occurs or pyrofuse 10 igniting even when no overcurrent is occurring. Furthermore, when the current path is interrupted solely by blow fuse 20, it takes time from the start to the completion of interruption of the current path when an overcurrent occurs. However, by providing pyrofuse 10 in addition to blow fuse 20, the current path can be instantaneously interrupted by pyrofuse 10. In other words, a safe state can be achieved more quickly.

[0045] Second Embodiment Next, a battery shutoff unit (BDU) according to a second embodiment will be described.

[0046] FIG. 4 is a configuration diagram showing an example of a battery cutoff unit 100a according to the second embodiment.

[0047] The battery cutoff unit 100a differs from the battery cutoff unit 100 in that, in addition to the components included in the battery cutoff unit 100, the battery cutoff unit 100a includes a short circuit 60, a short circuit control unit 130, and an OBD (On Board Diagnostics) 140. Since the other features are the same as those in the battery cutoff unit 100, the following description will focus on the differences.

[0048] The short circuit 60 is connected in parallel with the series circuit composed of the pyrofuse 10 and the blowout fuse 20, and is a circuit for short-circuiting both ends of the series circuit. The short circuit 60 is a relay or a pyroelectric short-circuiter. A pyroelectric short-circuiter contains explosives and ignites the explosives based on an ignition signal from outside the pyroelectric short-circuiter, irreversibly turning an insulated path into a conductive state due to the explosive force generated by the explosive ignition. A pyroelectric short-circuiter performs the opposite operation to a pyrofuse. A pyroelectric short-circuiter is also called a current short-circuiter, pyrocloser, or pyrotechnic short-circuiter. The short circuit 60 is controlled by the short circuit control unit 130.

[0049] When at least one of pyrofuse 10 and blown fuse 20 is in a non-conductive state, short circuit control unit 130 causes short circuit 60 to short both ends of the series circuit. For example, when detection unit 120 detects that the voltage across the series circuit is approximately the same as the voltage of battery 200, short circuit control unit 130 determines that at least one of pyrofuse 10 and blown fuse 20 is in a non-conductive state, and sends a signal to short circuit 60 to short both ends of the series circuit (specifically, a signal to turn on a relay or an ignition signal to drive a pyro-shorter). Short circuit control unit 130 is realized, for example, by a microcomputer or the like.

[0050] OBD 140 is a fault diagnosis device mounted on a vehicle (transportation equipment) equipped with battery 200 and load 300, and diagnoses the vehicle's fault state. OBD 140 can diagnose whether there is fatal damage to the vehicle's high-voltage circuit (HV circuit) or ECU, and whether various sensing data mounted on the vehicle is normal. For example, if pyrofuse 10 or blown fuse 20 becomes non-conductive but the vehicle is not faulty, it can determine that pyrofuse 10 or blown fuse 20 has malfunctioned, and both ends of the series circuit can be short-circuited to supply power to load 300.

[0051] The short circuit control unit 130 causes the short circuit 60 to short-circuit both ends of the series circuit based on the diagnosis result of the OBD 140. For example, the short circuit control unit 130 is controlled by the ECU 600, and the ECU 600 controls the short circuit control unit 130 based on the diagnosis result of the OBD 140, causing the short circuit control unit 130 to short-circuit both ends of the series circuit with the short circuit 60.

[0052] Note that the short circuit control unit 130 may display a warning to an occupant of a vehicle in which the battery 200 and the load 300 are mounted before short-circuiting both ends of the series circuit with the short circuit 60, and may short-circuit both ends of the series circuit with the short circuit 60 only if the occupant performs an operation to permit short-circuiting both ends of the series circuit after the warning is displayed. In this way, both ends of the series circuit can be short-circuited and power can be supplied to the load 300 only with the final permission of the vehicle occupant. The permission of the occupant is not limited to the occupant, but may also be given by remote control by someone who has the authority to control the vehicle.

[0053] Next, the operation of the battery cutoff unit 100a when short-circuiting both ends of the series circuit will be described with reference to FIG.

[0054] FIG. 5 is a flowchart showing an example of the operation of the battery cutoff unit 100a according to the second embodiment.

[0055] For example, if the vehicle experiences a minor crash or if a signal is obtained indicating that pyro-fuse 10 or blown fuse 20 has malfunctioned, at least one of pyro-fuse 10 and blown fuse 20 will become non-conductive (step S101).

[0056] The OBD 140 determines whether or not there is fatal damage to the HV circuit or the ECU (step S102).

[0057] If there is fatal damage to the HV circuit or ECU (Yes in step S102), running the vehicle may result in a dangerous situation, so the short circuit 60 does not short-circuit both ends of the series circuit, and the vehicle cannot be run.

[0058] If there is no fatal damage to the HV circuit or the ECU (No in step S102), the OBD 140 determines whether the various sensing data are normal (step S103).

[0059] If the various sensing data are abnormal (No in step S103), an error message is notified to the vehicle occupants (step S104), and since driving the vehicle could result in a dangerous situation, the short circuit 60 does not short-circuit both ends of the series circuit, and the vehicle cannot be driven.

[0060] If the various sensing data are normal (Yes in step S103), a warning is displayed to the vehicle occupants informing them that both ends of the series circuit will be short-circuited to enter emergency driving mode (step S105).

[0061] The user's intention as to whether or not to enter the emergency driving mode is confirmed (step S106), and if the emergency driving mode is not to be entered (No in step S106), the vehicle remains stopped.

[0062] If an operation to permit entry into the emergency driving mode is performed (Yes in step S106), the short-circuit control unit 130 short-circuits both ends of the short-circuit circuit 60 (step S107), and the vehicle enters the emergency driving mode.

[0063] As described above, the provision of short circuit 60 in battery cutoff unit 100a increases redundancy and improves safety in the event of a malfunction of pyrofuse 10. For example, if pyrofuse 10 malfunctions, the vehicle will be unable to run, but by shorting both ends of the series circuit, it is possible to supply power to the vehicle and allow the vehicle to run.

[0064] (Other Embodiments) As described above, the embodiments have been described as examples of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. For example, the following modifications are also included in one embodiment of the present disclosure.

[0065] For example, in the above embodiment, an example has been described in which the battery cutoff unit includes the current sensor 50, but the battery cutoff unit does not have to include the current sensor 50. In this case, the ignition control unit 110 controls the output of the ignition signal to the pyrofuse 10 based on the voltage detection result of the detection unit 120.

[0066] For example, in the above embodiment, an example has been described in which the battery cutoff unit includes the relays 30 and 40 , but the battery cutoff unit does not necessarily have to include at least one of the relays 30 and 40 .

[0067] For example, in the first embodiment, the detection unit 120 detects the voltage across the series circuit configured from the pyrofuse 10 and the blown fuse 20. However, this is not limiting. For example, the detection unit 120 may detect the voltage across the blown fuse 20.

[0068] For example, in the second embodiment, the battery cutoff unit 100a includes the OBD 140, but the OBD 140 does not have to be a component of the battery cutoff unit 100a.

[0069] For example, the present disclosure can be realized not only as a battery cutoff unit, but also as a battery cutoff method including steps (processing) performed by components that make up the battery cutoff unit.

[0070] FIG. 6 is a flowchart showing an example of a battery cutoff method according to another embodiment.

[0071] The battery cutoff method is a battery cutoff method executed by a battery cutoff unit, and the battery cutoff unit is arranged between a battery positive terminal t1 to which the positive terminal of the battery 200 is connected and a load positive terminal t2 to which the positive terminal of the load is connected, or between a battery negative terminal t3 to which the negative terminal of the battery 200 is connected and a load negative terminal t4 to which the negative terminal of the load is connected, and includes a pyro-fuse 10 and a blown fuse 20 connected in series to each other, and as shown in Figure 6, the battery cutoff method includes a voltage detection step (step S11) of detecting a voltage including at least the voltage across both ends of the blown fuse 20, and an ignition control step (step S12) of controlling the output of an ignition signal to the pyro-fuse 10 based on the detection result in the voltage detection step.

[0072] For example, the present disclosure can be realized as a program for causing a computer (processor) to execute the steps included in the battery cutoff method. Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

[0073] For example, when the present disclosure is realized as a program (software), each step is performed by running the program using hardware resources such as a computer's CPU, memory, input / output circuits, etc. In other words, each step is performed by the CPU acquiring data from memory or input / output circuits, etc., performing calculations, and outputting the calculation results to memory or input / output circuits, etc.

[0074] In the above-described embodiment, each component included in the battery cutoff unit may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0075] Some or all of the functions of the battery cutoff unit according to the above embodiments are typically realized as an LSI, which is an integrated circuit. These may be individually integrated into single chips, or some or all of them may be integrated into a single chip. Furthermore, the integrated circuit is not limited to an LSI, and may be realized using a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array), which can be programmed after LSI manufacturing, or a reconfigurable processor, which can reconfigure the connections and settings of circuit cells within the LSI, may also be used.

[0076] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, that technology may naturally be used to integrate each component included in the battery cutoff unit.

[0077] In addition, this disclosure also includes forms obtained by making various modifications to the embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in each embodiment within the scope of the present disclosure.

[0078] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0079] (Technology 1) A battery cutoff unit comprising: a battery positive terminal to which the positive terminal of a battery is connected; a load positive terminal to which the positive terminal of a load is connected; a battery negative terminal to which the negative terminal of the battery is connected; a load negative terminal to which the negative terminal of the load is connected; a pyro-fuse and a blown fuse that are arranged between the battery positive terminal and the load positive terminal or between the battery negative terminal and the load negative terminal and are connected in series; a voltage detection unit that detects a voltage including the voltage across the blown fuse; and an ignition control unit that controls the output of an ignition signal to the pyro-fuse based on the detection result of the voltage detection unit.

[0080] The voltage across the blown fuse rises sharply only when an overcurrent occurs; in other words, the voltage changes significantly when an overcurrent occurs. This makes it easy to detect the voltage across the blown fuse, reducing the possibility of erroneous detection of the voltage across the blown fuse. Therefore, by using the voltage across the blown fuse to drive the pyrofuse, the pyrofuse can be driven accurately when an overcurrent occurs. This prevents pyrofuse malfunctions, such as the pyrofuse not igniting when an overcurrent occurs or igniting even when no overcurrent is occurring. Furthermore, when the current path is interrupted solely by a blown fuse, it takes time from the start to the completion of interruption of the current path when an overcurrent occurs. However, by providing a pyrofuse in addition to the blown fuse, the current path can be interrupted instantly by the pyrofuse. In other words, a safe state can be achieved more quickly.

[0081] (Technology 2) The battery cutoff unit according to Technology 1, further comprising a current sensor arranged between the positive terminal of the battery and the positive terminal of the load, or between the negative terminal of the battery and the negative terminal of the load.

[0082] This makes it possible to detect the current flowing through the current path.

[0083] (Technology 3) The battery cutoff unit according to Technology 2, wherein the ignition control unit controls the output of the ignition signal based on the detection result of the voltage detection unit and the detection result of the current sensor.

[0084] This allows the pyro-fuse to be driven using both the voltage across the blown fuse and the current flowing through the current path, thereby enabling the pyro-fuse to be driven more accurately when an overcurrent occurs, further suppressing malfunction of the pyro-fuse.

[0085] (Technology 4) The battery cut-off unit described in Technology 3, wherein the ignition control unit outputs the ignition signal when the product of the voltage value indicated by the detection result of the voltage detection unit and the current value indicated by the detection result of the current sensor satisfies a predetermined condition.

[0086] This allows the pyro-fuse to be driven when the product of the voltage across the blown fuse and the current flowing through the current path, that is, the power generated in the blown fuse, becomes large.

[0087] (Technology 5) The battery cut-off unit described in Technology 3, wherein the ignition control unit outputs the ignition signal when the integral value of the product of the voltage value indicated by the detection result of the voltage detection unit and the current value indicated by the detection result of the current sensor satisfies a predetermined condition.

[0088] This allows the pyro-fuse to be driven when the integral value of the product of the voltage across the blown fuse and the current flowing through the current path, i.e., the amount of power generated in the blown fuse, becomes large.

[0089] (Technology 6) The battery cut-off unit described in Technology 3, wherein the ignition control unit outputs the ignition signal when the change per unit time of the product of the voltage value indicated by the detection result of the voltage detection unit and the current value indicated by the detection result of the current sensor satisfies a predetermined condition.

[0090] This allows the pyro-fuse to be activated when the change per unit time in the product of the voltage across the fuse and the current flowing through the current path, i.e., the change per unit time in the power generated in the fuse, increases. For example, it is possible to estimate that the power generated in the fuse will increase in the future from the change per unit time in the power generated in the fuse. In other words, before the power generated in the fuse actually increases, the pyro-fuse can be activated in advance, anticipating this future increase.

[0091] (Technology 7) A battery cutoff unit according to any one of technologies 2 to 6, wherein the pyroelectric fuse and the blown fuse are arranged between the positive terminal of the battery and the positive terminal of the load, and the current sensor is arranged between the negative terminal of the battery and the negative terminal of the load.

[0092] The reference potential of the sensing board, which outputs the detection results of the current sensor, is often set to the potential of the battery's negative terminal. For this reason, the current sensor is often placed between the battery's negative terminal and the load's negative terminal. This is because if the current sensor were placed between the battery's positive terminal and the load's positive terminal, a high voltage would be applied between the reference potential of the sensing board and the current sensor. In other words, from a fail-safe perspective, the reference potential of the sensing board is set to the potential of the battery's negative terminal, and the current sensor is placed between the battery's negative terminal and the load's negative terminal. Furthermore, the potential of the battery's positive terminal may fluctuate due to battery deterioration, etc., and depending on the system in which the battery is installed, the potential of the battery's negative terminal may be used as a ground potential. Therefore, the reference potential of the sensing board is often set to the potential of the battery's negative terminal.

[0093] Because the current sensor generates heat, if the current sensor is disposed between the negative terminal of the battery and the negative terminal of the load, and the pyroelectric fuse and blown fuse are also disposed between the negative terminal of the battery and the negative terminal of the load, the pyroelectric fuse and blown fuse may become too hot. One possible solution to the heat generation of the current sensor would be to increase the distance between the pyroelectric fuse and blown fuse and the current sensor, but this would require a large space and increase the size of the battery cutoff unit. Therefore, by disposing the pyroelectric fuse and blown fuse between the positive terminal of the battery and the positive terminal of the load, where no current sensor is disposed, it is possible to both miniaturize the battery cutoff unit and address the heat generation of the current sensor.

[0094] (Technology 8) A battery cutoff unit according to any one of technologies 2 to 6, wherein the pyro-fuse and the blown fuse are arranged between the negative terminal of the battery and the negative terminal of the load, and the current sensor is arranged between the positive terminal of the battery and the positive terminal of the load.

[0095] Because the current sensor generates heat, if the current sensor is disposed between the battery positive terminal and the load positive terminal, and the pyroelectric fuse and blown fuse are also disposed between the battery positive terminal and the load positive terminal, the pyroelectric fuse and blown fuse may become too hot. One possible solution to the heat generated by the current sensor would be to increase the distance between the pyroelectric fuse and blown fuse and the current sensor, but this would require a large amount of space, resulting in an increased size of the battery cutoff unit. Therefore, by disposing the pyroelectric fuse and blown fuse between the battery negative terminal and the load negative terminal, where no current sensor is disposed, it is possible to both miniaturize the battery cutoff unit and address the heat generated by the current sensor.

[0096] (Technology 9) A battery cutoff unit described in any one of Technologies 1 to 8, wherein the ignition control unit further controls the output of the ignition signal based on an instruction signal from a vehicle in which the battery and the load are mounted.

[0097] This allows the pyro-fuse to be activated by a command from the vehicle.

[0098] (Technology 10) A battery cutoff unit according to any one of technologies 1 to 9, wherein the voltage detection unit detects the voltage across a series circuit formed by the pyro-fuse and the blown fuse.

[0099] This makes it possible to detect the voltage across the series circuit, including the voltage across the blown fuse, even after the pyro-fuse has ignited.

[0100] (Technology 11) The battery cutoff unit according to Technology 10, further comprising a short circuit connected in parallel with the series circuit for short-circuiting both ends of the series circuit.

[0101] This increases redundancy in the event of a pyroelectric fuse malfunction, thereby improving safety. For example, if a pyroelectric fuse malfunctions, the vehicle will be unable to run, but by shorting both ends of the series circuit, power can be supplied to the vehicle, allowing the vehicle to run.

[0102] (Technology 12) The battery cutoff unit according to technology 11, wherein the short circuit is a relay or a pyroelectric short circuit.

[0103] This allows both ends of the series circuit to be shorted by a relay or pyroelectric short circuit.

[0104] (Technology 13) The battery cutoff unit described in Technology 11 or 12 further includes a short-circuit control unit that short-circuits both ends of the series circuit to the short circuit when at least one of the pyro-fuse and the blown fuse is in a non-conductive state.

[0105] This allows power to be supplied to the load by short-circuiting both ends of the series circuit when the pyro-fuse or blown fuse is in a non-conducting state.

[0106] (Technology 14) The battery cut-off unit described in Technology 13 further includes a fault diagnosis device mounted on a vehicle in which the battery and the load are mounted and which diagnoses a fault condition of the vehicle, and the short circuit control unit further shorts both ends of the series circuit to the short circuit based on the diagnosis result of the fault diagnosis device.

[0107] According to this, if the pyro-fuse or blown fuse becomes non-conductive but the vehicle is not malfunctioning, it can be determined that the pyro-fuse or blown fuse has malfunctioned, and both ends of the series circuit can be short-circuited to supply power to the load.

[0108] (Technology 15) A battery cut-off unit as described in Technology 13 or 14, in which the short-circuit control unit displays a warning to an occupant of a vehicle in which the battery and the load are mounted before short-circuiting both ends of the series circuit with the short circuit, and short-circuits both ends of the series circuit with the short circuit only if the occupant performs an operation to allow short-circuiting both ends of the series circuit after displaying the warning.

[0109] This allows both ends of the series circuit to be short-circuited and power to be supplied to the load only with the final permission of the vehicle occupant.

[0110] (Technology 16) A battery shut-off method executed by a battery shut-off unit, the battery shut-off unit including: a battery positive terminal to which a positive terminal of a battery is connected; a load positive terminal to which a positive terminal of a load is connected; a battery negative terminal to which a negative terminal of the battery is connected; a load negative terminal to which the negative terminal of the load is connected; and a pyro-fuse and a blown fuse that are arranged between the battery positive terminal and the load positive terminal or between the battery negative terminal and the load negative terminal and are connected in series, the battery shut-off method including: a voltage detection step of detecting a voltage including a voltage across the blown fuse; and an ignition control step of controlling output of an ignition signal to the pyro-fuse based on a detection result in the voltage detection step.

[0111] This provides a battery cutoff method that can suppress malfunction of the pyrofuse.

[0112] The present disclosure can be applied to a system that cuts off a current path by activating a pyrofuse.

[0113] 10 Pyro fuse (pyrotechnic fuse, pyrotechnic cutoff device) 20 Melting fuse 30, 40 Relay 50 Current sensor 60 Short circuit 100, 100a Battery cutoff unit 110 Ignition control unit 120 Detection unit (voltage detection unit) 130 Short circuit control unit 140 OBD 200 Battery 300 Load 400 LV battery 500, 600 ECU t1 Battery positive terminal t2 Load positive terminal t3 Battery negative terminal t4 Load negative terminal

Claims

1. A battery cutoff unit comprising: a battery positive terminal to which a positive electrode terminal of a battery is connected; a load positive terminal to which a positive electrode terminal of a load is connected; a battery negative terminal to which a negative electrode terminal of the battery is connected; a load negative terminal to which a negative electrode terminal of the load is connected; a pyro fuse and a fuse disposed between the battery positive terminal and the load positive terminal or between the battery negative terminal and the load negative terminal and connected in series with each other; a voltage detection unit that detects a voltage including the voltage across the fuse; and an ignition control unit that controls the output of an ignition signal to the pyro fuse based on the detection result of the voltage detection unit.

2. The battery cutoff unit according to claim 1, further comprising a current sensor disposed between the battery positive terminal and the load positive terminal or between the battery negative terminal and the load negative terminal.

3. The battery cutoff unit according to claim 2, wherein the ignition control unit controls the output of the ignition signal based on the detection result of the voltage detection unit and the detection result of the current sensor.

4. The battery cutoff unit according to claim 3, wherein the ignition control unit outputs the ignition signal when the product of the voltage value indicated by the detection result of the voltage detection unit and the current value indicated by the detection result of the current sensor satisfies a predetermined condition.

5. The battery cutoff unit according to claim 3, wherein the ignition control unit outputs the ignition signal when the integrated value of the product of the voltage value indicated by the detection result of the voltage detection unit and the current value indicated by the detection result of the current sensor satisfies a predetermined condition.

6. The battery cutoff unit according to claim 3, wherein the ignition control unit outputs the ignition signal when the amount of change per unit time of the product of the voltage value indicated by the detection result of the voltage detection unit and the current value indicated by the detection result of the current sensor satisfies a predetermined condition.

7. The battery cutoff unit according to any one of claims 2 to 6, wherein the pyro fuse and the fuse are disposed between the battery positive terminal and the load positive terminal, and the current sensor is disposed between the battery negative terminal and the load negative terminal.

8. The pilot fuse and the fuse are arranged between the battery negative terminal and the load negative terminal, and the current sensor is arranged between the battery positive terminal and the load positive terminal. The battery cutoff unit according to any one of claims 2 to 6.

9. The ignition control unit further controls the output of the ignition signal based on an instruction signal from a vehicle on which the battery and the load are mounted. The battery cutoff unit according to any one of claims 1 to 8.

10. The voltage detection unit detects the voltage across both ends of a series circuit composed of the pilot fuse and the fuse. The battery cutoff unit according to any one of claims 1 to 9.

11. The battery cutoff unit further includes a short-circuit circuit connected in parallel with the series circuit for short-circuiting both ends of the series circuit. The battery cutoff unit according to claim 10.

12. The short-circuit circuit is a relay or a pilot short-circuit device. The battery cutoff unit according to claim 11.

13. The battery cutoff unit further includes a short-circuit control unit that short-circuits both ends of the series circuit to the short-circuit circuit when at least one of the pilot fuse and the fuse is in a non-conductive state. The battery cutoff unit according to claim 11 or claim 12.

14. The battery cutoff unit is further mounted on a vehicle on which the battery and the load are mounted, and includes a fault diagnosis device for diagnosing the fault state of the vehicle. The short-circuit control unit further short-circuits both ends of the series circuit to the short-circuit circuit based on the diagnosis result of the fault diagnosis device. The battery cutoff unit according to claim 13.

15. The short-circuit control unit displays a warning to the passengers of the vehicle on which the battery and the load are mounted before short-circuiting both ends of the series circuit to the short-circuit circuit, and short-circuits both ends of the series circuit to the short-circuit circuit only when an operation is performed by the passengers to permit short-circuiting both ends of the series circuit after the warning is displayed. The battery cutoff unit according to claim 13 or claim 14.

16. A battery cutoff method executed by a battery cutoff unit, wherein the battery cutoff unit includes a battery positive terminal side terminal to which a positive electrode terminal of a battery is connected, a load positive terminal side terminal to which a positive electrode terminal of a load is connected, a battery negative terminal side terminal to which a negative electrode terminal of the battery is connected, a load negative terminal side terminal to which a negative electrode terminal of the load is connected, and a pyro fuse and a fusing fuse that are arranged between the battery positive terminal side terminal and the load positive terminal side terminal or between the battery negative terminal side terminal and the load negative terminal side terminal and are connected in series with each other, and the battery cutoff method includes a voltage detection step of detecting a voltage including a voltage across both ends of the fusing fuse, and an ignition control step of controlling output of an ignition signal to the pyro fuse based on a detection result in the voltage detection step.

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