Battery cut-off unit

Abstract

Provided is a battery cut-off unit (100) for use in transportation equipment comprising a battery (200) and a load (400). The battery cut-off unit (100) comprises: a pyro-fuse (20); a mechanical relay (30) having a first contact (305) and a second contact (306); a current sensor (40); and a cut-off control circuit (10) connected to the current sensor (40) and the pyro-fuse (20). The current sensor (40) outputs, to the cut-off control circuit (10), a current value of current flowing in a current path between the battery (200) and the load (400). The cut-off control circuit (10) outputs an ignition signal to the pyro-fuse (20) on the basis of the current value. The pyro-fuse (20) cuts off the current path on the basis of the ignition signal. The mechanical relay (30) is turned on / off according to a control signal from outside the battery cut-off unit (100).

Description

Battery Cut-Off Unit

[0001] The present disclosure relates to a battery disconnect unit for use in transportation equipment.

[0002] Patent Document 1 describes a system that causes a fuse to break a current path based on a current value detected by a current sensor.

[0003] JP 2015-91199 A

[0004] The system described in Patent Document 1 may not be able to safely interrupt the current path in transportation equipment such as an electric vehicle equipped with a large-capacity battery.

[0005] Therefore, the present disclosure provides a battery cutoff unit that can safely cut off a current path in a transportation device equipped with a large-capacity battery.

[0006] A battery cutoff unit according to one aspect of the present disclosure is a battery cutoff unit used in transportation equipment having a battery and a load, the battery cutoff unit comprising a pyroelectric fuse, a mechanical relay having a first contact and a second contact, a current sensor, and a cutoff control circuit connected to the current sensor and the pyroelectric fuse, the current sensor outputs a current value of a current flowing in a current path between the battery and the load to the cutoff control circuit, the cutoff control circuit outputs an ignition signal to the pyroelectric fuse based on the current value, the pyroelectric fuse cuts off the current path by the ignition signal, and the mechanical relay is turned ON / OFF by a control signal from outside the battery cutoff unit.

[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 an aspect of the present disclosure, a current path can be safely cut off in a transport device equipped with a large-capacity battery.

[0009] It is an appearance diagram showing an example of a battery cutoff unit according to an embodiment. It is a configuration diagram showing an example of a battery cutoff unit according to an embodiment. It is a cross-sectional view showing an example of a pyrofuse according to an embodiment. It is a diagram showing current-voltage characteristics of a battery cutoff unit in an embodiment. It is a side view showing an example of a mechanical relay according to an 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] (Embodiment) A battery cutoff unit according to an embodiment will be described below.

[0013] Fig. 1 is an external view showing an example of a battery cutoff unit 100 according to an embodiment. Note that in the external view shown in Fig. 1, terminals, wiring, etc. are omitted from the illustration, and each component is also shown as a schematic rectangular parallelepiped.

[0014] The battery cutoff unit 100 includes a pyro-fuse (ignition-type cutoff device) 20 , a mechanical relay 30 , a current sensor 40 , a cutoff control circuit 10 , and one rigid part 110 .

[0015] Rigid body portion 110 secures pyrofuse 20, mechanical relay 30, current sensor 40, and shutdown control circuit 10. Rigid body portion 110 is, for example, a base on which pyrofuse 20, mechanical relay 30, current sensor 40, and shutdown control circuit 10 are placed. Rigid body portion 110 may be a metal plate or the like, and may dissipate heat as a heat sink. For example, no components other than those related to pyrofuse 20, mechanical relay 30, current sensor 40, and shutdown control circuit 10 are secured to rigid body portion 110.

[0016] For example, the shutoff control circuit 10 is formed on a substrate or the like, and in the example shown in FIG. 1, the substrate on which the shutoff control circuit 10 is formed is fixed upright on the end of the rigid part 110 .

[0017] For example, the battery cutoff unit 100 includes a lid 120, which covers the pyrofuse 20, the mechanical relay 30, and the current sensor 40. For example, as shown in FIG. 1 , the lid 120 does not have to cover the shutdown control circuit 10, and the shutdown control circuit 10 may form a wall of the battery cutoff unit 100. In the battery cutoff unit 100 shown in FIG. 1 , the pyrofuse 20, the mechanical relay 30, and the current sensor 40 are covered by the lid 120 and a substrate that forms the shutdown control circuit 10. For example, as shown in FIG. 1 , holes may be provided on the top surface of the lid 120, which can improve heat dissipation. For example, the lid 120 may be made of resin.

[0018] In this way, the battery cutoff unit 100 is a single unit centered around one rigid part 110. The rigid part 110 may be a housing that covers and fixes the pyrofuse 20, the mechanical relay 30, the current sensor 40, and the cutoff control circuit 10.

[0019] FIG. 2 is a configuration diagram showing an example of a battery cutoff unit 100 according to an embodiment. The battery cutoff unit 100 is used in a transportation device including an electronic control unit (ECU) 300, a battery 200, and a load 400. In addition to the battery cutoff unit 100, FIG. 2 also shows the battery 200, a battery pack 500 covering the battery 200, the ECU 300, and the load 400, all of which are included in the transportation device. As shown in FIG. 2, the battery 200, the ECU 300, and the load 400 are provided outside the battery cutoff unit 100. In FIG. 2, the lines connecting the battery 200 and the load 400 indicate the flow of current (power), and the arrows indicate the flow of signals. The ECU 300 is connected to the battery 200 and the load 400 without being connected to the current sensor 40, and outputs a control signal. The battery cutoff unit 100 is used in transportation devices such as electric vehicles.

[0020] Battery 200 is, for example, a battery capable of applying a high voltage to load 400. For example, battery 200 is a main battery (e.g., a lithium-ion battery) in an electric vehicle, and is not a sub-battery such as a lead-acid battery also used in transportation equipment equipped with a gasoline engine. Battery 200 is covered by a battery pack 500.

[0021] The load 400 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 400. 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 400, which may cause the battery 200 to emit smoke or catch fire. Therefore, the battery cutoff unit 100 is used in transportation equipment.

[0022] The ECU 300 is a device for controlling the battery 200, the load 400, and various other components (such as steering, various sensors, communication devices, and IVI (In Vehicle Infotainment)) of the transportation equipment. Here, one ECU 300 is shown, but the ECU 300 may be composed of multiple ECUs. For example, the ECU 300 is connected to the battery 200, can exchange signals with the battery 200, and can monitor the state of the battery 200. For example, the ECU 300 is connected to the load 400, can exchange signals with the load 400, and can monitor the state of the load 400. Furthermore, for example, the ECU 300 controls the mechanical relay 30 and the like provided in the battery cutoff unit 100. That is, the mechanical relay 30 is turned ON / OFF by a control signal from outside the battery cutoff unit 100 (specifically, a control signal from the ECU 300). For example, the mechanical relay 30 is turned on / off by a control signal based on information acquired by the ECU 300 from the battery 200 or the load 400 .

[0023] The battery cutoff unit 100 is a unit for cutting off a current path connecting the battery 200 and the load 400. The current path connecting the battery 200 and the load 400 may be a path connecting the positive terminal of the battery 200 and the positive terminal of the load 400, or may be a path connecting the negative terminal of the battery 200 and the negative terminal of the load 400. Note that the current path can be cut off by cutting a wiring (e.g., a bus bar) through which a current flows, or by turning off a relay that is inserted in the current path and forms part of the current path.

[0024] The battery cutoff unit 100 includes a cutoff control circuit 10, a pyro-fuse 20, a mechanical relay 30, a pre-charge relay 31, a pre-charge resistor 32, and a current sensor 40. As shown in Fig. 2, the battery cutoff unit 100 may include a plurality of mechanical relays 30. For example, the battery cutoff unit 100 is covered by a battery pack 500 together with the battery 200, but may be provided separately from the battery pack 500.

[0025] Shutdown control circuit 10 is connected to current sensor 40 and pyrofuse 20. Current sensor 40 outputs the current value of the current flowing in the current path between battery 200 and load 400 to shutdown control circuit 10, shutdown control circuit 10 outputs an ignition signal to pyrofuse 20 based on the current value, and pyrofuse 20 shuts off the current path in response to the ignition signal.

[0026] For example, the cutoff control circuit 10 may recognize that an arc discharge is occurring in the mechanical relay 30 based on a change in the current value from the current sensor 40 , and output an ignition signal to the pyro-fuse 20 .

[0027] For example, the shutoff control circuit 10 may store a first time period from the output of the ignition signal to the occurrence of arc discharge in the pyrofuse 20, and use multiple current values ​​measured at different times input from the current sensor 40 and the first time to predict the time when the current value of the current flowing in the current path will exceed a threshold current, and based on the prediction, output an ignition signal to the pyrofuse 20 so that an arc discharge will occur in the pyrofuse 20 after an arc discharge occurs in the mechanical relay 30, and so that the period in which an arc discharge occurs in the mechanical relay 30 overlaps with the period in which an arc discharge occurs in the pyrofuse 20.

[0028] For example, when a current exceeding the threshold current flows through the current path (including when a current exceeding the threshold current actually flows through the current path and when a current exceeding the threshold current is predicted to flow through the current path), the cutoff control circuit 10 cuts off the connection between the load 400 and the battery 200 by outputting an ignition signal to the pyrofuse 20 after contact 305 (see Figure 5 described later) and contact 306 (see Figure 5 described later) of the mechanical relay 30 are separated and an arc discharge occurs, and an arc discharge occurs both between the first contact and the second contact and at the part of the current path that is divided by the pyrofuse 20.

[0029] Fig. 3 is a cross-sectional view showing an example of pyrofuse 20 according to an embodiment. Fig. 3(a) shows the state before bus bar 204 constituting the current path is severed, and Fig. 3(b) shows the state after bus bar 204 is severed. Note that pyrofuse 20 shown in Fig. 3 is merely an example.

[0030] As shown in (a) of Figure 3, the pyrofuse 20 has a casing portion 201 that forms the outer shell of the pyrofuse 20, a piston 203 that is movable in a first direction d1, an ignition portion 202 that activates the piston 203, and a busbar 204 that is inserted into the current path and becomes part of the current path.

[0031] The casing 201 has a cylindrical shape and is disposed along the first direction d1. A central portion of the bus bar 204, the piston 203, and the ignition unit 202 are disposed inside the casing 201. Both ends of the bus bar 204 are disposed outside the casing 201. The bus bar 204 is a linear, flat conductor and is disposed along a second direction d2 that intersects with the first direction d1. In this example, the second direction d2 is perpendicular to the first direction d1. The bus bar 204 extending in the second direction d2 penetrates the side surface of the casing 201, and both ends of the bus bar 204 protrude outward from the side surface of the casing 201.

[0032] 3A, ignition unit 202 is provided inside casing unit 201. When an overcurrent occurs, that is, when ignition unit 202 receives an ignition signal output from shutoff control circuit 10, ignition unit 202 activates piston 203. Specifically, ignition unit 202 ignites gunpowder to rapidly expand gas inside casing unit 201, thereby moving piston 203 at high speed in first direction d1.

[0033] Piston 203 has a cylindrical shape and is disposed inside casing 201 so as to extend along first direction d1. When ignition unit 202 is ignited, piston 203 moves in first direction d1 and severs busbar 204 (see (b) of FIG. 3). When piston 203 severs busbar 204, it collides with busbar 204 or a part of casing 201, generating vibration in first direction d1.

[0034] Pyro fuse 20 is a fuse for cutting off a current path connecting battery 200 and load 400 when a large current due to a short circuit occurs in the current path. Pyro fuse 20 contains an explosive and ignites the explosive based on a signal from outside pyro fuse 20, thereby irreversibly cutting off the current path with the explosive force generated by the ignition of the explosive. Pyro fuse 20 cuts off the current path in response to an ignition signal from shutoff control circuit 10. For example, pyro fuse 20 is provided in the current path connecting the positive terminal of battery 200 and the positive terminal of load 400, and cuts off the current path in response to an ignition signal from shutoff control circuit 10.

[0035] For example, pyrofuse 20 can continuously pass a current of 500 A or less, and can pass a current of about 1200 A for several seconds to several tens of seconds. Furthermore, for example, pyrofuse 20 can interrupt a current path through which a voltage of 500 V to 1000 V or less flows and a current of 16000 A to 25000 A or less flows. In pyrofuse 20, the current path (current path) and the ignition signal path are insulated from each other to prevent high voltage from being applied to the ignition signal path.

[0036] Next, a detailed description will be given of the timing at which the cutoff control circuit 10 sends an ignition signal to the pyro-fuse 20. Note that although the following description will be given using the mechanical relay 30 as an example, the same operation can also be performed for the precharge relay 31.

[0037] FIG. 4 is a diagram showing the current-voltage characteristics of the battery cutoff unit 100 according to the embodiment of the present disclosure, and is a diagram showing the change in current monitored by the current sensor 40.

[0038] The current value monitored by the current sensor 40 is sent to the tripping control circuit 10, and at time T0 the current I begins to rise. At time T1, the current value exceeds the short-circuit withstand current (threshold current) of the mechanical relay 30, and an overcurrent flows. This causes the contacts 305 and 306 to separate from each other, and an arc discharge occurs between the contacts 305 and 306 (at time T1 in FIG. 4 , the voltage of the mechanical relay 30 rises).

[0039] Time T1 is the timing at which arc discharge starts in mechanical relay 30. At this time, the current path is not interrupted by pyrofuse 20, and no arc discharge occurs in pyrofuse 20. Note that ECU 300 may provide an interruption signal (OFF signal) to mechanical relay 30 around time T1.

[0040] Next, during the period from time T1 to time T2, an arc discharge occurs between contacts 305 and 306, and the current value continues to rise even after exceeding the short-circuit withstand current (threshold current), and then the current value decreases.

[0041] Next, at time T2 (around time T2), shutoff control circuit 10 sends an ignition signal to pyrofuse 20 based on the current value (monitoring current information) from current sensor 40. As a result, pyrofuse 20 cuts off the current path, and an arc discharge also occurs at the part of the current path cut by pyrofuse 20 (at time T2 in FIG. 4 , the voltage of pyrofuse 20 (voltage at the cut part) rises).

[0042] Next, from time T2 to time T3, an arc discharge occurs in both the mechanical relay 30 (specifically, between contacts 305 and 306) and the pyrofuse 20 (specifically, the portion of the current path that is cut by the pyrofuse 20).

[0043] The period from time T2 to time T3 is a period in which the current value decreases following the period from time T1 to time T2, but the rate of decrease in the current value from time T2 to time T3 is greater than the rate of decrease in the current value from time T1 to time T2.

[0044] In other words, the shutdown control circuit 10 sends an ignition signal to the pyro-fuse 20 based on the current value (current information) from the current sensor 40 at the timing of time T2 (or the period from time T2 to time T3) based on the current value (current information) from the current sensor 40.

[0045] As an example of the decision by the shutdown control circuit 10 to output an ignition signal, the shutdown control circuit 10 stores the time (called the first time) from the output of the ignition signal to the occurrence of arc discharge in pyrofuse 20, and predicts the time when the short circuit withstand current (threshold current) will be exceeded using multiple current values ​​(current information) with different times (called measurement times) for measuring the current value input from current sensor 40 and the first time, and outputs an ignition signal to pyrofuse 20 based on the prediction so that arc discharge will occur in pyrofuse 20 after arc discharge in mechanical relay 30, and so that the period when arc discharge occurs in mechanical relay 30 overlaps with the period when arc discharge occurs in pyrofuse 20.

[0046] It should be noted that shutoff control circuit 10 may use another method for determining the timing to send an ignition signal to pyrofuse 20. For example, the current value may increase and exceed a current value greater than the short-circuit withstand current (threshold current), then increase further, reach a maximum value after a while, and then decrease, and the ignition signal may be sent to pyrofuse 20 at the timing (time T2 in FIG. 4 ) when it is recognized that the rate of current decrease has changed.

[0047] Furthermore, as another example, the timing for sending an ignition signal to pyro-fuse 20 may be the timing when the current value rises to a value exceeding a current value greater than the short-circuit withstand current (threshold current), reaches a maximum value after a while, and then decreases until it is recognized to be lower than a certain value (reference value for determining whether to cut off).

[0048] In other words, by monitoring the change in the current value, the shutdown control circuit 10 can recognize that an arc discharge has occurred in the mechanical relay 30, and therefore the shutdown control circuit 10 can output an ignition signal to the pyro-fuse 20 based on the change in the current value from the current sensor 40.

[0049] Next, pyroelectric fuse 20 receives an ignition signal and interrupts the current path, causing the potential difference between one end and the other end of the interrupted portion of the current path to increase. This potential difference then decreases, and at time T3, current I begins to decrease rapidly. Then, at time T4, the current flowing between battery 200 and load 400 is completely interrupted.

[0050] As described above, the battery cutoff unit 100 according to this embodiment is characterized in that the cutoff instructions to the mechanical relay 30 and the pyro-fuse 20 are sent from separate circuits (specifically, the ECU 300 and the cutoff control circuit 10).

[0051] That is, the ECU 300 mounted on the transportation equipment sends a signal to the mechanical relay 30, thereby turning off the mechanical relay 30. For example, when various faults other than a fault that causes an overcurrent flow occur in the transportation equipment, the mechanical relay 30 is turned off. In this way, the battery cutoff unit 100 can cut off (turn on / off) the current path by the mechanical relay 30 multiple times (repeatedly).

[0052] On the other hand, the battery cut-off unit 100 of this embodiment is capable of cutting off the pyro-fuse 20 by an ignition signal from the cut-off control circuit 10 when an overcurrent occurs based on the current value (monitoring current information) from the current sensor 40.

[0053] In other words, a signal is sent to the mechanical relay 30 from the transportation equipment's ECU 300 (outside the battery cut-off unit 100), and a signal is sent to the pyro-fuse 20 from the cut-off control circuit 10 within the battery cut-off unit 100, thereby enabling appropriate cut-off in a variety of situations.

[0054] Furthermore, in the battery cutoff unit 100 according to this embodiment, the cutoff control circuit 10 provided within the battery cutoff unit 100 is not connected to the ECU 300 provided outside the battery cutoff unit 100, and there is no need for information to be shared (sharing determination) between the cutoff control circuit 10 and the ECU 300. Furthermore, the current sensor 40 provided within the battery cutoff unit 100 is not connected to the ECU 300 provided outside the battery cutoff unit 100, and the ECU 300 does not need to recognize the current value (current information) from the current sensor 40. In other words, whether or not the overcurrent is exceeded, appropriate cutoff can be performed using the mechanical relay 30 and the pyro-fuse 20.

[0055] In addition, the battery cutoff unit 100 uses a pyro fuse 20 instead of a blow fuse because it is difficult for a blow fuse to achieve both response time and durability, whereas a pyro fuse 20 can achieve both.

[0056] 5 is a side view showing an example of a mechanical relay 30 according to an embodiment. As shown in FIG. 5, the mechanical relay 30 includes a first circuit unit 301, a second circuit unit 302, a movable terminal 303, a fixed terminal 304, a contact 305, a contact 306, and a movable unit 307. The mechanical relay 30 controls the movable terminal 303 and the fixed terminal 304 to be in contact or separated from each other in order to electrically connect or disconnect the first circuit unit 301 and the second circuit unit 302. The contact 305 is an example of a first contact, and the contact 306 is an example of a second contact. It is more preferable that the precharge relay 31 also have the configuration shown in FIG. 5.

[0057] The mechanical relay 30 is a switch that switches ON / OFF the supply of power from the battery 200 to the load 400. The mechanical relay 30 is turned ON / OFF by a control signal from the ECU 300. For example, when the transportation equipment is started, the control signal from the ECU 300 turns the mechanical relay 30 ON, and the supply of power to the load 400 begins. The control signal from the ECU 300 turns the mechanical relay 30 OFF.

[0058] For example, the control signal from ECU 300 to mechanical relay 30 may be a signal generated based on the detection result of a fault in the transportation equipment. For example, ECU 300 detects a fault in the transportation equipment. For example, the fault in the transportation equipment is a fault outside of battery cutoff unit 100. For example, the fault in the transportation equipment is a fault other than a fault in which an overcurrent flows in the current path (e.g., a fault in battery 200 or load 400). For example, if power supply to load 400 continues even after the output of battery 200 is turned OFF (including when the driver turns it OFF by operating the start button) while mechanical relay 30 is ON, ECU 300 detects a fault in the transportation equipment, generates a control signal to turn mechanical relay 30 OFF, and outputs the control signal to mechanical relay 30. As a result, in transportation equipment in which a fault other than a fault in which an overcurrent flows in the current path has occurred, the mechanical relay 30 can cut off the current path.

[0059] In this way, the ECU 300, which can monitor various states of the transportation equipment, such as the states of the battery 200 and the load 400, can cut off the current path by turning off the mechanical relay 30 in response to a failure in the transportation equipment.

[0060] 2, the mechanical relay 30 is provided on each of the current path connecting the positive terminal of the battery 200 and the positive terminal of the load 400, and the current path connecting the negative terminal of the battery 200 and the negative terminal of the load 400. For example, the pyro-fuse 20 is provided on the current path closer to the battery 200 than the mechanical relay 30.

[0061] For example, a high voltage of 100 V or more can be applied to the mechanical relay 30, and the mechanical relay 30 can be repeatedly turned on and off tens of thousands of times or more. For example, the mechanical relay 30 can continuously pass a current of 300 A or less and can interrupt (turn on and off) a current path through which a current of 300 A or less flows multiple times. Furthermore, for example, the mechanical relay 30 can be applied with a voltage of 1000 V or less and interrupt the current path through which a current of 2000 A or less flows.

[0062] The battery cutoff unit 100 uses a mechanical relay 30 rather than a semiconductor relay because, in order to make a semiconductor relay have a small current resistance like the mechanical relay 30, it is necessary to connect many semiconductor relays in parallel, which has disadvantages in terms of cost and size.

[0063] If the mechanical relay 30 is turned on when the transportation equipment is started, an inrush current will flow. Therefore, the battery cutoff unit 100 is provided with a precharge relay 31 and a precharge resistor 32 as a countermeasure against the inrush current. The precharge relay 31 is turned on / off by a signal from the ECU 300.

[0064] The pre-charge relay 31 and the pre-charge resistor 32 are connected in series, and the circuit in which the pre-charge relay 31 and the pre-charge resistor 32 are connected in series is connected in parallel with the mechanical relay 30. For example, when starting the vehicle, the mechanical relay 30 provided in the current path on the positive terminal side is turned off, the pre-charge relay 31 is turned on, and the mechanical relay 30 provided in the current path on the negative terminal side is turned on. This allows current to flow to the load 400 via the pre-charge resistor 32, thereby suppressing the occurrence of inrush current. For example, in about 0.3 seconds, the voltage of the smoothing capacitance of the load 400 becomes approximately the same as the voltage of the battery 200, and the mechanical relay 30 provided in the current path on the positive terminal side is turned on, thereby starting normal operation.

[0065] It is more preferable that the precharge relay 31 is of the same type as the mechanical relay 30. Also, the precharge relay 31 can have the same configuration as the mechanical relay 30. On the other hand, the precharge relay 31 may be a semiconductor relay.

[0066] The current sensor 40 is a sensor that detects the current value of a current flowing through a current path connecting the battery 200 and the load 400. For example, the current sensor 40 can continuously pass a current of 300 A or less. For example, the current sensor 40 is a shunt-type sensor (e.g., a shunt resistor: e.g., approximately 20 μΩ to 80 μΩ). The current sensor 40 outputs the detected current value (analog value) to the shutoff control circuit 10. The current sensor 40 may also be a sensor such as a Hall element.

[0067] If a large current continues to flow through the current path, it may cause a malfunction in the pyro-fuse 20, the mechanical relay 30, or the current sensor 40. For example, if a large current continues to flow through the current path, the mechanical relay 30 may explode.

[0068] Here, the failure characteristics of the mechanical relay 30 will be described. If a current of 500 A flows through the current path, the mechanical relay 30 will not fail (e.g., explode) even if the current continues to flow through the current path for 100,000 ms. However, if the current continues to flow for 100,000 ms or more, the mechanical relay 30 will fail. Furthermore, if a current of 6,000 A, which is greater than 500 A, flows through the current path, the mechanical relay 30 will fail if the current continues to flow for 200 ms or more. Thus, if the current flowing through the current path is small, the mechanical relay 30 is unlikely to fail even if the current continues to flow for a long time. However, if the current flowing through the current path is large, the mechanical relay 30 will fail even if the current flows for a short time. Therefore, the interruption control circuit 10 determines whether the current flowing through the current path is an overcurrent based on the current value of the current flowing through the current path, and outputs an ignition signal to the pyrofuse 20. If the current flowing through the current path is an overcurrent, the pyrofuse 20 will interrupt the current path.

[0069] The shutoff control circuit 10 is a circuit that shuts off a current path by driving the pyrofuse 20. The shutoff control circuit 10 is realized, for example, by a microcontroller unit (MCU). The shutoff control circuit 10 may also be realized, for example, by an application specific integrated circuit (ASIC). The shutoff control circuit 10 includes a current acquisition unit 11, a shutoff determination unit 12, and an ignition control unit 14. For example, the current acquisition unit 11 and the shutoff determination unit 12 are realized by a microcontroller 13, and the ignition control unit 14 is realized by an ASIC 15.

[0070] The current acquiring unit 11 is an AD converter that acquires a current value (analog value) of the current flowing through the current path detected by the current sensor 40 and converts it into a digital value (referred to as an AD value). The current acquiring unit 11 outputs the AD value to the interruption determination unit 12. For example, the current acquiring unit 11 converts the current value detected by the current sensor 40 into an AD value at regular time intervals and outputs the AD value to the interruption determination unit 12.

[0071] The interruption determination unit 12 determines whether the current flowing through the current path is an overcurrent. Specifically, the interruption determination unit 12 determines whether to drive the pyro-fuse 20 (i.e., to interrupt the current path) based on whether the current value detected by the current sensor 40 (specifically, the AD value acquired from the current acquisition unit 11) is an overcurrent.

[0072] When cutoff determination unit 12 determines that the current flowing through the current path is an overcurrent (i.e., when it determines that pyrofuse 20 should be activated), ignition control unit 14 outputs an ignition signal to pyrofuse 20 to activate pyrofuse 20. This makes it possible to cut off the current path.

[0073] The method by which the trip determination unit 12 determines whether the current flowing in the current path is an overcurrent is not particularly limited. However, it is necessary to distinguish whether the current flowing in the current path is noise or an overcurrent. Therefore, for example, the trip determination unit 12 may be provided with a filter that removes noise. Furthermore, for example, the trip determination unit 12 may average the current value detected by the current sensor 40 over a certain period and determine whether the current flowing in the current path is an overcurrent depending on whether the average value is equal to or greater than a predetermined value.

[0074] In this way, the cutoff determination unit 12 can determine whether the overcurrent is not a temporary one caused by noise but is flowing continuously in the current path, and if an overcurrent is flowing continuously, the current path can be cut off by driving the pyro-fuse 20 via the ignition control unit 14.

[0075] Once the pyrofuse 20 is activated, the transportation equipment cannot be restored unless the pyrofuse 20 is replaced. Therefore, it is very important to prevent the pyrofuse 20 from being erroneously activated. Therefore, the battery cutoff unit 100 may be equipped with two current sensors 40. For example, the current sensors 40 may be provided in the current path so that they detect the same current value, and the cutoff determination unit 12 may detect a failure of the current sensor 40 using the two AD values. If the two AD values ​​are different, the cutoff determination unit 12 can determine that at least one of the two current sensors 40 is faulty. The two AD values ​​should be the same, but if they are different, it is highly likely that at least one of the two current sensors 40 is faulty. For example, if it is determined that at least one of the two current sensors 40 is faulty, a notification to that effect is sent to the user or manager of the transportation equipment, and the current sensor 40 is repaired. This makes it possible to suppress malfunctions of devices such as the mechanical relay 30 provided in the current path, while also suppressing erroneous activation of the pyrofuse 20 due to a malfunction of the current sensor 40. In particular, when determining an overcurrent using a time integral value, it is possible to suppress malfunctions of devices such as the mechanical relay 30 provided in the current path, while also suppressing erroneous activation of the pyrofuse 20 due to a malfunction of the current sensor 40.

[0076] The pyro-fuse 20 has the disadvantage that once it has been activated, the transportation equipment cannot be restored unless it is replaced, while the mechanical relay 30 has the advantage that it can be repeatedly turned on and off after the abnormality has been corrected or if there was no failure in the first place. Therefore, any failure other than a failure in which an overcurrent flows in the current path is detected by the ECU 300, and the mechanical relay 30 is turned on and off based on the detection result of this failure.

[0077] The present disclosure is applicable to transportation equipment such as hybrid vehicles that are also equipped with engines, but is preferably used in pure electric vehicles that require larger capacity batteries than hybrid vehicles.

[0078] As described above, in transportation equipment equipped with a large-capacity battery 200, such as an electric vehicle, an extremely large current can flow in the current path connecting the battery 200 and the load 400 in the event of an abnormality. Because pyrofuse 20 can interrupt the current path even when a large current of tens of thousands of amperes flows through the current path, battery cutoff unit 100 equipped with pyrofuse 20 can safely cut off the current path. Furthermore, because pyrofuse 20 and cutoff control circuit 10, which outputs an ignition signal to pyrofuse 20, are provided in a single rigid body 110, if cutoff control circuit 10 determines that the current flowing through the current path is an overcurrent, the cutoff control circuit 10, which is provided in close proximity to one another and therefore is provided in a single rigid body 110, can instantly transmit an ignition signal to pyrofuse 20. Therefore, in transportation equipment equipped with a large-capacity battery 200, the current path can be quickly and safely cut off.

[0079] Furthermore, since the mechanical relay 30 can improve the interruption performance without increasing the size and cost compared to a semiconductor relay, it is possible to prevent the battery cutoff unit 100 from increasing in size and cost in a transportation device equipped with a large-capacity battery 200 through which a large current can flow. Furthermore, since the ECU 300 can detect faults in the transportation device, it can cut off the current path by turning off the mechanical relay 30 for faults other than those in which an overcurrent flows in the current path.

[0080] (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.

[0081] Each of the components included in the shutoff control circuit 10 of the above embodiment may be realized as a dedicated or general-purpose circuit.

[0082] Furthermore, each of the components included in the shutoff control circuit 10 of the above embodiment may be realized as an LSI (Large Scale Integration) which is an integrated circuit (IC).

[0083] Furthermore, the integrated circuit is not limited to an LSI, and may be realized by a dedicated circuit or a general-purpose processor. A programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor in which the connections and settings of circuit cells within the LSI can be reconfigured may also be used.

[0084] Furthermore, if an integrated circuit technology that can replace LSIs emerges due to advances in semiconductor technology or other derivative technologies, it is natural that each component included in the shutdown control circuit 10 can be integrated using that technology.

[0085] 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.

[0086] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0087] (Technology 1) A battery cutoff unit used in transportation equipment that includes a battery and a load, the battery cutoff unit including a pyro fuse, a mechanical relay having a first contact and a second contact, a current sensor, and a cutoff control circuit connected to the current sensor and the pyro fuse, the current sensor outputs a current value of a current flowing in a current path between the battery and the load to the cutoff control circuit, the cutoff control circuit outputs an ignition signal to the pyro fuse based on the current value, the pyro fuse cuts off the current path by the ignition signal, and the mechanical relay is turned ON / OFF by a control signal from outside the battery cutoff unit.

[0088] In transportation equipment equipped with large-capacity batteries, such as electric vehicles, an extremely large current can flow in the current path connecting the battery and the load in the event of an abnormality. Because pyrofuses can interrupt the current path even when a large current of tens of thousands of amperes flows through the current path, a battery cutoff unit equipped with a pyrofuse can safely cut off the current path. Therefore, the current path can be safely cut off in transportation equipment equipped with large-capacity batteries.

[0089] Furthermore, compared to semiconductor relays, mechanical relays can improve interruption performance without increasing the size and cost, which makes it possible to prevent the battery interruption unit from becoming larger and more expensive in transportation equipment equipped with large-capacity batteries through which large currents can flow.

[0090] Furthermore, if an abnormality occurs in the transportation equipment, the current path can be cut off by turning off the mechanical relay using a control signal from an electronic control unit or the like provided outside the battery cutoff unit.

[0091] (Technology 2) The battery cutoff unit according to Technology 1, wherein the cutoff control circuit recognizes that an arc discharge is occurring in the mechanical relay based on a change in the current value from the current sensor, and outputs the ignition signal to the pyro fuse.

[0092] In this way, by monitoring the change in the current value, the shutoff control circuit can recognize that an arc discharge has occurred in the mechanical relay, and the shutoff control circuit can output an ignition signal to the pyro-fuse based on the change in the current value of the current sensor 4.

[0093] (Technology 3) The battery cutoff unit according to Technology 1 or 2, wherein the cutoff control circuit stores a first time period from the output of the ignition signal to the occurrence of arc discharge in the pyro-fuse, and predicts the time when a threshold current will be exceeded using the first time and a plurality of current values ​​measured at different times input from the current sensor, and outputs the ignition signal to the pyro-fuse based on the prediction so that an arc discharge will occur in the pyro-fuse after an arc discharge occurs in the mechanical relay, and so that a period during which an arc discharge occurs in the mechanical relay and a period during which an arc discharge occurs in the pyro-fuse overlap.

[0094] In this way, the current path may be blocked based on a prediction of when the current value of the current flowing through the current path will exceed the threshold current.

[0095] (Technology 4) A battery cutoff unit according to any one of Technologies 1 to 3, wherein, when a current exceeding a threshold current flows through the current path, the cutoff control circuit cuts off the connection between the load and the battery by outputting the ignition signal to the pyro-fuse after the first contact and the second contact are separated and an arc discharge occurs, and the arc discharge occurs both between the first contact and the second contact and at the portion of the current path that is separated by the pyro-fuse.

[0096] In this way, in the battery cutoff unit, an ignition signal is output to the pyro-fuse to cut off the connection between the load and the battery, and then an arc discharge occurs in the mechanical relay and the pyro-fuse.

[0097] (Technology 5) The transportation equipment includes an electronic control unit that is provided outside the battery cutoff unit, is connected to the battery and the load without being connected to the current sensor, and outputs the control signal, and the mechanical relay is turned ON / OFF by the control signal based on information from the battery or the load. This is a battery cutoff unit described in any of Technologies 1 to 4.

[0098] The electronic control unit installed outside the battery cut-off unit can monitor abnormalities in the battery or load in the transportation equipment, and if an abnormality occurs in the battery or load, the current path can be cut off by turning off the mechanical relay.

[0099] (Technology 6) The battery cutoff unit according to Technology 5, wherein the control signal is a signal generated based on the detection result of a fault in the transportation equipment.

[0100] The electronic control unit generates a control signal based on the detection result of a fault in the transportation equipment and outputs the control signal to the mechanical relay, so that the mechanical relay can be turned ON / OFF depending on the detection result of the fault in the transportation equipment.

[0101] (Technology 7) The pyro fuse is capable of continuously passing a current of 500 A or less, and is capable of interrupting the current path through which a voltage of 1000 V or less is applied and a current of 25000 A or less flows. A battery cutoff unit according to any one of technologies 1 to 6.

[0102] Because pyrofuses have this type of performance, they can cut off a current path even when a large current of tens of thousands of amperes flows through the current path.

[0103] (Technology 8) A battery cutoff unit according to any one of technologies 1 to 7, wherein the mechanical relay is capable of continuously conducting a current of 300 A or less, and is capable of interrupting the current path through which a voltage of 1000 V or less is applied and a current of 2000 A or less flows.

[0104] Such performance of the mechanical relay allows repeated ON / OFF of the current path in transportation equipment equipped with a large-capacity battery.

[0105] (Technology 9) A battery cutoff unit according to any one of technologies 1 to 8, wherein the current sensor is capable of continuously passing a current of 300 A or less.

[0106] The current sensor having such performance makes it possible to detect the current flowing in the current path in transportation equipment equipped with a large-capacity battery.

[0107] (Technology 10) A battery cutoff unit described in any of Technologies 1 to 9, wherein the battery cutoff unit includes two or more current sensors, and the cutoff control circuit detects failures of two or more current sensors based on the current values ​​of the two or more current sensors.

[0108] Two current sensors are provided in the current path so that each detects the same current value, and if the two current values ​​are different, it can be determined that at least one of the two current sensors is faulty.

[0109] (Technology 11) The battery cutoff unit according to any one of technologies 1 to 10, wherein the pyro fuse is provided closer to the battery than the mechanical relay in the current path.

[0110] This allows the current path to be cut off by the pyro-fuse at a position closer to the battery, thereby improving safety.

[0111] (Technology 12) A battery cutoff unit according to any one of technologies 1 to 11, wherein the current sensor is a shunt-type sensor.

[0112] Shunt-type current sensors can detect large currents, so even if a large current flows through a current path in a transportation device equipped with a large-capacity battery, the shunt-type current sensor can detect the current flowing through the current path.

[0113] (Technology 13) A battery cutoff unit according to any one of technologies 1 to 12, wherein the cutoff control circuit has a current acquisition unit, a cutoff determination unit, and an ignition control unit, the current acquisition unit acquires the current value of the current flowing in the current path, the cutoff determination unit determines whether the current flowing in the current path is an overcurrent, and the ignition control unit outputs the ignition signal to the pyro-fuse when it is determined that the current flowing in the current path is an overcurrent.

[0114] In this way, the current acquiring unit, the cutoff determining unit, and the ignition control unit can realize a cutoff control circuit.

[0115] The present disclosure can be applied to a system that cuts off a current path by activating a pyrofuse.

[0116] REFERENCE SIGNS LIST 10 Shutdown control circuit 11 Current acquisition unit 12 Shutdown determination unit 13 Microcomputer 14 Ignition control unit 15 ASIC 20 Pyro fuse 30 Mechanical relay 31 Precharge relay 32 Precharge resistor 40 Current sensor 100 Battery shutoff unit 110 Rigid body unit 120 Lid 200 Battery 201 Casing unit 202 Ignition unit 203 Piston 204 Bus bar 300 ECU 301 First circuit unit 302 Second circuit unit 303 Movable terminal 304 Fixed terminal 305 Contact (first contact) 306 Contact (second contact) 307 Movable unit 400 Load

Claims

1. A battery cutoff unit for use in a transportation device including a battery and a load, The battery cutoff unit includes: Pyro fuse and a mechanical relay having a first contact and a second contact; a current sensor; a shutoff control circuit connected to the current sensor and the pyrofuse, the current sensor outputs a current value of a current flowing through a current path between the battery and the load to the cutoff control circuit; the cutoff control circuit outputs an ignition signal to the pyro-fuse based on the current value; the pyro-fuse interrupts the current path in response to the ignition signal; The mechanical relay is turned on / off by a control signal from outside the battery cutoff unit. Battery disconnect unit.

2. The cutoff control circuit recognizes that an arc discharge is occurring in the mechanical relay based on a change in the current value from the current sensor, and outputs the ignition signal to the pyro-fuse.

2. The battery shutoff unit of claim 1.

3. The shutoff control circuit includes: storing a first time period from the output of the ignition signal to the occurrence of arc discharge in the pyro-fuse; predicting a time when the current value of the current flowing through the current path will exceed a threshold current by using the plurality of current values ​​measured at different times input from the current sensor and the first time; outputting the ignition signal to the pyro-fuse so that, based on the prediction, an arc discharge occurs in the mechanical relay followed by an arc discharge in the pyro-fuse, and so that a period during which an arc discharge occurs in the mechanical relay and a period during which an arc discharge occurs in the pyro-fuse overlap with each other; 2. The battery disconnect unit of claim 1.

4. The shutoff control circuit includes: When a current exceeding a threshold current flows through the current path, the first contact and the second contact are separated to generate an arc discharge, and then the ignition signal is output to the pyro-fuse to disconnect the load from the battery, and the arc discharge occurs both between the first contact and the second contact and at the portion of the current path that is divided by the pyro-fuse.

2. The battery disconnect unit of claim 1.

5. the transportation equipment further includes an electronic control unit that is provided outside the battery cutoff unit, that is not connected to the current sensor but is connected to the battery and the load, and that outputs the control signal; the mechanical relay is turned on / off by the control signal based on information from the battery or the load; 2. The battery disconnect unit of claim 1.

6. The control signal is a signal generated based on a detection result of a failure in the transportation equipment.

6. The battery shutoff unit of claim 5.

7. The pyro fuse is A current of 500 A or less can be continuously applied. It is possible to interrupt the current path through which a voltage of 1000 V or less is applied and a current of 25000 A or less flows.

2. The battery disconnect unit of claim 1.

8. The mechanical relay comprises: A current of 300 A or less can be continuously applied. It is possible to interrupt the current path through which a voltage of 1000 V or less is applied and a current of 2000 A or less flows.

2. The battery disconnect unit of claim 1.

9. The current sensor is capable of continuously passing a current of 300 A or less.

2. The battery disconnect unit of claim 1.

10. the battery cutoff unit includes two of the current sensors; the shutoff control circuit detects failures of two or more of the current sensors based on the current values ​​of the two current sensors; 2. The battery disconnect unit of claim 1.

11. The pyro-fuse is provided on the battery side of the mechanical relay in the current path.

2. The battery disconnect unit of claim 1.

12. The current sensor is a shunt type sensor.

2. The battery disconnect unit of claim 1.

13. The shutoff control circuit includes a current acquisition unit, a shutoff determination unit, and an ignition control unit, the current acquisition unit acquires a current value of a current flowing through the current path; the interruption determination unit determines whether a current flowing through the current path is an overcurrent; The ignition control unit outputs the ignition signal to the pyro-fuse when it is determined that the current flowing through the current path is an overcurrent. A battery cut-off unit according to any one of claims 1 to 12.