Current breaking device

Abstract

To provide a current breaking device capable of appropriately breaking current by suppressing consumption of a battery.SOLUTION: A current breaking device 1 has a hall element 2 detecting a current value of a power source line 13 supplying power to a motor 12 from a battery 11, a breaking part 3 breaking the power source line 13, and a breaking control part 4 breaking the power source line 13 by operating the breaking part 3 based on a detection signal of the hall element 2. The breaking control part 4 has a voltage current conversion part 41 outputting current according to an output voltage value of the hall element 2, a capacitor 42 charged according to the output current of the voltage current conversion part 41, and a breaking signal output part 43 outputting a breaking signal Vcpm to the breaking part 3 when the voltage of the capacitor 42 exceeds a threshold value Vref.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a current interrupting device.

Background Art

[0002] Conventionally, as a current interrupting device, for example, as described in Patent Document 1, a current interruption system that interrupts the current flowing from a battery to a load is known. This current interruption system includes a shunt resistor that measures the current value flowing from the battery to the load, and when the current value measured by the shunt resistor exceeds a preset threshold value, it cuts the base material between the battery and the load to interrupt the current and protect the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described system, there is room for improvement in that the battery consumption is large. That is, in the above-described system, it is necessary to constantly flow a current through the shunt resistor to measure the current value, resulting in a large battery consumption.

[0005] Therefore, an object of the present invention is to provide a current interrupting device that can suppress the battery consumption and appropriately interrupt the current.

Means for Solving the Problems

[0006] That is, the current cutoff device according to the present invention includes a Hall element that detects the current value of a power supply line that supplies power from a battery to a load, a cutoff unit that cuts off the power supply line, and a cutoff control unit that operates the cutoff unit based on the detection signal of the Hall element to cut off the power supply line. The cutoff control unit includes a voltage-current conversion unit that outputs a current corresponding to the output voltage value of the Hall element, a capacitor that is charged according to the output current of the voltage-current conversion unit, and a cutoff signal output unit that outputs a cutoff signal to the cutoff unit when the voltage of the capacitor exceeds a threshold value.

Advantages of the Invention

[0007] According to the current cutoff device of the present invention, it is possible to suppress the consumption of the battery and appropriately cut off the current.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by these embodiments. Also, the components in the following embodiments include those that can be replaced by those skilled in the art and are easy to replace, or those that are substantially the same.

[0010] [Embodiment] This embodiment relates to a current interruption device. As shown in FIG. 1, the current interruption device 1 according to the first embodiment is a device that interrupts the power line 13 for supplying power from the battery 11 to the motor 12, and is mounted and used in an electric vehicle or a hybrid vehicle having the motor 12 as a drive source. The current interruption device 1 detects, for example, an overcurrent or a short circuit in the power line 13 connected to the high-voltage battery 11, and interrupts the power line 13 at the time of detection.

[0011] The battery 11 and the motor 12 are connected by the power line 13. As the battery 11, a battery that outputs power capable of driving the motor 12 is used. The motor 12 is a load that operates by receiving power supply from the battery 11. The power line 13 is a transmission line for supplying power from the battery 11 to the motor 12, and for example, a coated wire in which a conductor is coated with an insulator is used. The power line 13 is provided with a cut portion 14 and a relay 15. The cut portion 14 is a component that interrupts the current in the power line 13 when cut, and for example, a bus bar is used. The cut portion 14 is cut when the power line 13 is short-circuited or an overcurrent equal to or greater than a predetermined current value flows through the power line 13. The relay 15 is a main relay for turning on and off the power supply to the motor 12.

[0012] The current interruption device 1 includes a Hall element 2, a cut-off portion 3, and a cut-off control portion 4. The Hall element 2 is a current detection unit that detects the current value flowing through the power line 13. For example, the Hall element 2 receives the current of the constant current source 21, detects the magnetic field formed around the power line 13, and detects the current value flowing through the power line 13. Since the Hall element 2 can be used without passing the current from the battery 11 like a shunt resistor, the power consumption of the battery 11 can be suppressed.

[0013] The cutoff unit 3 is a unit that cuts off the power line 13. For example, it operates upon receiving the cutoff signal from the cutoff control unit 4, cuts off the cut-off part 14, and cuts off the power line 13. The cutoff unit 3 has, for example, an ignition unit 31, a gunpowder storage unit 32, and a cutting unit 33. The ignition unit 31 is a component that ignites the gunpowder stored in the gunpowder storage unit 32 upon receiving the cutoff signal. For example, the ignition unit 31 receives the cutoff signal via a switching element or the like and ignites the gunpowder stored in the gunpowder storage unit 32. The gunpowder storage unit 32 is a container that stores gunpowder. The cutting unit 33 is a component that cuts off the cut-off part 14 and cuts off the power line 13. For example, it operates by the explosive force generated by the ignition of gunpowder, abuts against the cut-off part 14, and cuts off the cut-off part 14.

[0014] The cutoff control unit 4 is a cutoff control unit that operates the cutoff unit 3 based on the detection signal of the Hall element 2 to cut off the power line 13. For example, it is composed of a cutoff control circuit. The cutoff control unit 4 has a voltage-current conversion unit 41, a capacitor 42, and a cutoff signal output unit 43.

[0015] The voltage-current conversion unit 41 is a voltage-current conversion circuit that outputs a current corresponding to the output voltage value of the Hall element 2. For example, the voltage-current conversion unit 41 is connected to the output side of the Hall element 2 via an amplifier circuit 44. The amplifier circuit 44 is a circuit that amplifies the detection signal of the Hall element 2. The voltage-current conversion unit 41 inputs the voltage amplified by the amplifier circuit 44 for the detection signal of the Hall element 2, converts the amplified voltage into a current, and outputs it. The voltage-current conversion unit 41 is composed of, for example, a differential amplifier, and a transistor 45 is connected to the output side of the differential amplifier.

[0016] The capacitor 42 is a capacitor charged in response to the output of the Hall element 2. For example, the capacitor 42 is connected to the output side of the voltage-current conversion unit 41 via a first current mirror circuit 46. The first current mirror circuit 46 is a circuit that outputs a current having the same current value as the current output from the voltage-current conversion unit 41. For example, the capacitor 42 is charged by a current having the same current value as the output current of the voltage-current conversion unit 41 via the first current mirror circuit 46. The larger the current output from the voltage-current conversion unit 41, the faster the capacitor 42 is charged, and the longer the output current of the voltage-current conversion unit 41 continues to be output, the larger the charging voltage becomes.

[0017] Also, the capacitor 42 is discharged by a constant current by a constant current circuit 47. For example, the capacitor 42 is connected to the output side of the constant current circuit 47 via a second current mirror circuit 48. Therefore, the capacitor 42 is discharged by a current having the same current value as the output current of the constant current circuit 47 via the second current mirror circuit 48. As a result, when the capacitor 42 is not charged by a current larger than the output current of the constant current circuit 47, the voltage value does not increase.

[0018] The voltage Vc of the capacitor 42 is input to the cutoff signal output unit 43. The cutoff signal output unit 43 is an output circuit that outputs a cutoff signal to the cutoff unit 3 when the voltage Vc of the capacitor 42 exceeds the threshold value Vref to the cutoff unit 3. For example, a comparator is used as the cutoff signal output unit 43. The threshold value Vref is, for example, a voltage set by a constant voltage circuit 49. When the voltage Vc of the capacitor 42 exceeds the threshold value Vref, the cutoff signal output unit 43 outputs a cutoff signal to the switching element 34 of the cutoff unit 3 to activate the ignition unit 31.

[0019] Next, the operation of the current cutoff device 1 according to the first embodiment will be described.

[0020] Figure 2 is a timing chart showing the operation of the current interrupting device 1. The horizontal axis represents time, and the vertical axis represents the current I in the power line 13, the voltage Vc of the capacitor 42, and the output signal Vcmp of the interruption signal output section 43. The 100% value shown in Figure 2 is the current value of the current I that charges the capacitor 42. That is, when the current I in the power line 13 exceeds the 100% value, the capacitor 42 starts to be charged.

[0021] In Figure 2, when the current I flowing through the power line 13 is an overcurrent exceeding the 100% value, as shown in the time t1 - t2, the voltage Vc of the capacitor 42 rises. That is, in Figure 1, a detection signal is output from the Hall element 2, the detection signal is amplified by the amplifier circuit 44, and is converted into a current by the voltage - current conversion section 41. Then, a current having the same current value as the output current of the voltage - current conversion section 41 is output from the first current mirror circuit 46 and charges the capacitor 42. At this time, the capacitor 42 is discharged at the same current value as the output current of the constant - current circuit 47. Therefore, when the charging current of the capacitor 42 becomes larger than the discharging current, the voltage Vc of the capacitor 42 starts to rise (time t1).

[0022] However, if the current I in the power line 13 becomes small before the voltage Vc of the capacitor 42 reaches the threshold value Vref (time t2), the voltage Vc of the capacitor 42 drops, and the current interruption of the power line 13 is not performed. Therefore, false interruption of the current interrupting device 1 can be suppressed. For example, when an instantaneous overcurrent such as a surge current flows through the power line 13, when there is no problem with the battery 11 and the relay 15, the current interrupting device 1 does not interrupt the current in the power line 13 and can suppress unnecessary current interruption.

[0023] Then, as shown in the time t3 - t4 in Figure 2, when the motor 12 is being driven in a steady state, no overcurrent flows through the power line 13, the capacitor 42 is not charged, and the current interruption of the power line 13 is not performed.

[0024] In contrast, at time t4 in FIG. 2, when an overcurrent starts to flow through the power line 13 and continues to flow, the capacitor 42 is charged, and the voltage Vc of the capacitor 42 exceeds the threshold value Vref (time t5). As a result, in FIG. 1, the cutoff signal Vcmp is output as a high-output signal from the cutoff signal output unit 43. For this reason, the ignition unit 31 is activated to ignite the gunpowder, the cutting unit 33 operates, and the cut portion 14 is cut. Then, the power line 13 is cut, the power line 13 is shut off, and the battery 11 and the relay 15 are protected from the overcurrent.

[0025] The time from when the overcurrent flows through the power line 13 until the current is cut off can be set according to the capacitance of the capacitor 42. Therefore, the capacitance of the capacitor 42 may be set according to the allowable current of the battery 11 and the relay 15. Further, the time from when the overcurrent flows through the power line 13 until the current is cut off can be set according to the current value of the constant current circuit 47. Therefore, the current value of the constant current circuit 47 may be set according to the allowable current of the battery 11 and the relay 15.

[0026] As described above, the current cutoff device 1 according to the first embodiment can perform current cutoff while suppressing the consumption of the battery 11 by using the Hall element 2 to detect the current value of the power line 13. Further, the current cutoff device 1 according to the present embodiment charges the capacitor 42 when the current I of the power line 13 becomes equal to or greater than a predetermined current value, and shuts off the power line 13 when the voltage Vc of the capacitor 42 exceeds the threshold value Vref. For this reason, the current cutoff device 1 according to the present embodiment can suppress the power line 13 from being cut off due to an instantaneous overcurrent. Therefore, the current cutoff device 1 according to the present embodiment can appropriately cut off the current I of the power line 13 while suppressing the consumption amount of the battery 11.

[0027] Further, since the current cutoff device 1 according to the present embodiment can perform current cutoff while suppressing the consumption of the battery 11 by using the Hall element 2 to detect the current value of the power line 13, when mounted on a vehicle and used, the cruising range of the vehicle can be extended.

[0028] In addition, the current interruption device 1 according to the present embodiment includes a constant current circuit 47 that discharges a constant current from the capacitor 42, thereby suppressing the capacitor 42 from being instantaneously charged by an instantaneous overcurrent. Therefore, the current interruption device 1 according to the present embodiment can appropriately interrupt the current I in the power line 13 as necessary.

[0029] Next, the current interruption device 1A according to the second embodiment will be described.

[0030] FIG. 3 is a circuit diagram showing a schematic configuration of the current interruption device 1A according to the second embodiment. The current interruption device 1A according to the present embodiment is different from the current interruption device 1 according to the first embodiment in that it additionally includes a second interruption signal output unit 50.

[0031] The second interruption signal output unit 50 is a circuit that outputs a cut-off signal Vcmp2 to the cut-off unit 3 without waiting for the voltage Vc of the capacitor 42 to exceed the threshold value Vref when a large current flows through the power line 13. For example, a comparator is used as the second interruption signal output unit 50, and the output signal of the amplifier circuit 44 and the output signal of the second constant voltage circuit 51 are input thereto. The second constant voltage circuit 51 sets a threshold value Vref2. Therefore, when the detection signal of the Hall element 2 is amplified and exceeds the threshold value Vref2, even if the voltage Vc of the capacitor 42 does not exceed the threshold value Vref, the second interruption signal output unit 50 outputs the cut-off signal Vcmp2 to the switching element 35 of the cut-off unit 3, and the current I in the power line 13 is interrupted. That is, as shown in FIG. 4, when a large current flows through the power line 13 and the output of the amplifier circuit 44 exceeds the threshold value Vref2 (time t7), the current I in the power line 13 is instantaneously interrupted.

[0032] In this way, the current cutoff device 1A according to the present embodiment can quickly cut off the current when a large current that would cause problems to the battery 11 and the relay 15 flows through the power line 13, while suppressing the power line 13 from being cut off due to an instantaneous overcurrent. Therefore, the current cutoff device 1A according to the present embodiment can appropriately cut off the current I of the power line 13 and enhance safety more effectively.

[0033] Next, the current cutoff device 1B according to the third embodiment will be described.

[0034] FIG. 5 is a circuit diagram showing a schematic configuration of the current cutoff device 1B according to the third embodiment. The current cutoff device 1B according to the present embodiment is different from the current cutoff device 1 according to the first embodiment in that it additionally includes a third cutoff signal output unit 52.

[0035] The third cutoff signal output unit 52 is a circuit that outputs a cutoff signal Vcmp3 to the cutoff unit 3 when a large current flows through the power line 13. For example, a comparator is used as the third cutoff signal output unit 52, and the output signal of the amplifier circuit 44 and the output signal of the third constant voltage circuit 53 are input thereto. The third constant voltage circuit 53 sets a threshold value Vref3. The threshold value Vref3 is set to the same current value as the 100% value of the current I in the power line 13 or a current value smaller than the 100% value.

[0036] When the detection signal of the Hall element 2 is amplified and exceeds the threshold value Vref3, the third cutoff signal output unit 52 outputs the cutoff signal Vcmp3 as a low-output signal to the switching element 36 of the cutoff unit 3. The switching element 36 is provided between the ignition unit 31 and the power supply VB, and the ignition unit 31 can be activated when the cutoff signal Vcmp3 is output as a low signal. Then, when the voltage Vc of the capacitor 42 exceeds the threshold value Vref due to an overcurrent in the power line 13 in a state where the ignition unit 31 can be activated, the ignition unit 31 is activated and the current I in the power line 13 is cut off. That is, as shown at time t9 in FIG. 6, when the cutoff signal Vcmp3 is output as a low signal and the voltage Vc of the capacitor 42 exceeds the threshold value Vref, the current I in the power line 13 is instantaneously cut off.

[0037] As described above, when the cutoff signal Vcmp3 is output as a low signal and the voltage Vc of the capacitor 42 exceeds the threshold value Vref, the current cutoff device 1B according to this embodiment instantaneously cuts off the current I in the power supply line 13, so that when the current I in the power supply line 13 is not an overcurrent, the voltage Vc of the capacitor 42 accidentally exceeds the threshold value Vref due to noise or the like. It is possible to suppress the current I from being erroneously cut off.

[0038] Note that the current cutoff device according to the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope described in the claims. The current cutoff device according to each embodiment may be configured by appropriately combining the components of the above-described embodiment and the modified example.

[0039] For example, in the second and third embodiments, the second cutoff signal output unit 50 and the third cutoff signal output unit 52 share the cutoff signal output unit 43, the Hall element 2, and the amplifier circuit 44. However, separately from the Hall element 2 and the amplifier circuit 44, a Hall element and an amplifier circuit for the second cutoff signal output unit 50 and the third cutoff signal output unit 52 may be provided.

[0040] In addition, in each of the above-described embodiments, the cutoff control unit 4 in FIGS. 1, 3, and 5 may be an integrated circuit configured on the same silicon substrate, and the Hall element 2 may be provided on the silicon substrate. Further, the Hall element 2 may be provided with a component such as a magnetic core in order to guide the magnetic field of the current I and to keep away an external magnetic field that causes an error factor.

[0041] In addition, in each of the above-described embodiments, the current cutoff device mounted on the vehicle has been described. However, the current cutoff device according to the present invention may be applied to a device not mounted on the vehicle.

Description of Reference Numerals

[0042] 1: Current cutoff device 2: Hall element 3: Cutoff unit 4: Cut-off control unit 11: Battery 12: Motor (load) 13: Power line 41: Voltage-current conversion unit 42: Capacitor 43: Cut-off signal output unit 47: Constant current circuit Vc: Voltage Vref: Threshold value Vcmp: Cut-off signal

Claims

1. A Hall element that detects the current value of a power line supplying power from a battery to a load, a cutoff section that cuts off the power line, and a cutoff control section that operates the cutoff section based on the detection signal of the Hall element to cut off the power line. The cutoff control section includes a voltage-current conversion section that outputs a current corresponding to the output voltage value of the Hall element, a capacitor that is charged according to the output current of the voltage-current conversion section, and a cutoff signal output section that outputs a cutoff signal to the cutoff section when the voltage of the capacitor exceeds a threshold value. A current cutoff device.

2. The cutoff control section further includes a constant current circuit that discharges a constant current from the capacitor. The current cutoff device according to claim 1.

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