Vehicle-mounted shutoff device and shutoff method

Abstract

To improve the reliability of operation related to breaking.SOLUTION: An in-vehicle breaker 1 includes a first input port 2, a first output port 3, and a first conductive path 4; a second input port 5, a second output port 6, and a second conductive path 7; a first current detector 8 capable of detecting a current flowing through the first conductive path 4 or the second conductive path 7; a second current detector 9 capable of detecting a current flowing through the first conductive path 4 or the second conductive path 7; a pyrotechnic circuit breaker 10 capable of irreversibly blocking the first conductive path 4; and a control unit 11 capable of controlling the blocking operation of the pyrotechnic circuit breaker 10 responding to the detected current. The control unit 11 is configured to cause the pyrotechnic circuit breaker to execute the blocking operation when both a first current value obtained based on a first detection signal and a second current value obtained based on a second detection signal exceed an overcurrent threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an on-board shutoff device and shutoff method for use in various vehicles. [Background technology]

[0002] A conventional circuit breaker is described below. The conventional circuit breaker has a pyrotechnic switch connected between the battery and the load, and a control circuit that controls the pyrotechnic switch. The control circuit detects the current supplied from the battery to the load and the vehicle state, and activates the pyrotechnic switch in response to the current and the vehicle state.

[0003] As prior art document information related to the invention of this application, for example, Patent Document 1 is known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-059202 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional circuit breakers, when a current flowing from a battery to a load is detected as an overcurrent state requiring interruption and it is determined that a pyrotechnic switch needs to be activated, it is not possible to determine whether the overcurrent detection is operating normally or erroneously. As a result, there are cases where an overcurrent is detected and determined to be occurring even when it is not, resulting in the pyrotechnic switch being activated, or where an overcurrent is detected and determined not to be occurring even when it is occurring, resulting in the pyrotechnic switch not being activated. As a result, there is a problem that the operational reliability of the circuit breaker may be reduced.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the reliability of the cutoff operation. [Means for solving the problem]

[0007] To achieve this object, the present invention provides a power supply circuit including a first input terminal to which DC power of a first polarity is supplied, a first output terminal, a first conductive path connecting the first input terminal and the first output terminal, a second input terminal to which DC power of a second polarity opposite to the first polarity is supplied, a second output terminal, a second conductive path connecting the second input terminal and the second output terminal, a first current detector capable of detecting a current flowing in the first conductive path or the second conductive path, and a second current detector capable of detecting a current flowing in the first conductive path or the second conductive path. a pyrotechnic circuit breaker capable of irreversibly interrupting the first conductive path; and a control unit capable of receiving a first detection signal and a second detection signal transmitted from the first current detector and the second current detector in response to the detected currents and capable of controlling the interrupting operation of the pyrotechnic circuit breaker, wherein the control unit causes the pyrotechnic circuit breaker to perform the interrupting operation when both a first current value obtained based on the first detection signal and a second current value obtained based on the second detection signal exceed an overcurrent threshold. [Effects of the Invention]

[0008] According to the present invention, a plurality of current detectors are used to detect an overcurrent, and a breaking operation can be performed based on the detection, thereby improving the operational reliability of the on-board breaker device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a first circuit block diagram showing the configuration of an on-board circuit breaking device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a second circuit block diagram showing the configuration of the vehicle-mounted circuit breaker according to the embodiment of the present invention; [Figure 3] FIG. 3 is a third circuit block diagram showing the configuration of the vehicle-mounted circuit breaker according to the embodiment of the present invention; [Figure 4]FIG. 4 is a fourth circuit block diagram showing the configuration of the vehicle-mounted circuit breaking device according to the embodiment of the present invention. [Figure 5] 5 is a circuit block diagram showing the configuration of the vehicle-mounted circuit breaking device according to the embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] (Embodiment) 1 is a first circuit block diagram showing the configuration of an on-board circuit breaker 1 according to an embodiment of the present invention. The on-board circuit breaker 1 includes a first input terminal 2, a first output terminal 3, a first conductive path 4, a second input terminal 5, a second output terminal 6, a second conductive path 7, a first current detector 8, a second current detector 9, a pyrotechnic circuit breaker 10, and a control unit 11.

[0012] DC power of a first polarity is supplied to a first input terminal 2. A first conductive path 4 connects the first input terminal 2 and a first output terminal 3. DC power of a second polarity, which is opposite to the first polarity, is supplied to a second input terminal 5. A second conductive path 7 connects the second input terminal 5 and a second output terminal 6.

[0013] The first current detector 8 can detect the current flowing in the first conductive path 4 or the second conductive path 7. Furthermore, the second current detector 9 can detect the current flowing in the first conductive path 4 or the second conductive path 7. The pyrotechnic circuit breaker 10 is arranged to be able to irreversibly interrupt the first conductive path 4. The control unit 11 can receive a first detection signal S1 transmitted from the first current detector 8 in response to the detected current, and a second detection signal S2 transmitted from the second current detector 9 in response to the detected current. Furthermore, the control unit 11 can control the interruption operation of the pyrotechnic circuit breaker 10.

[0014] The control unit 11 causes the pyrotechnic circuit breaker 10 to perform a circuit breaking operation when both the first current value I1 obtained based on the first detection signal S1 and the second current value I2 obtained based on the second detection signal S2 exceed the overcurrent threshold Ith.

[0015] With the above configuration and operation, it is possible to detect overcurrent by using multiple current detectors, namely, the first current detector 8 and the second current detector 9, and to perform interruption operation based on the multiple detection results. As a result, it is possible to improve the operational reliability of the vehicle-mounted interrupter 1.

[0016] The following describes in detail the on-board circuit breaker 1. As described above, the on-board circuit breaker 1 includes a first input terminal 2, a first output terminal 3, a first conductive path 4, a second input terminal 5, a second output terminal 6, a second conductive path 7, a first current detector 8, a second current detector 9, a pyrotechnic circuit breaker 10, and a control unit 11.

[0017] The on-board circuit breaker 1 is disposed on a vehicle body 13 of a vehicle 12. A vehicle power supply 14 and a vehicle load 15 are disposed on the vehicle body 13. The vehicle power supply 14 is a power source used mainly to propel and drive the vehicle 12, and a lithium battery or the like is used as a power storage element. The vehicle load 15 is a load mainly used to propel and drive the vehicle 12, and mainly corresponds to an inverter device (not shown) that converts DC power supplied from the vehicle power supply 14 into three-phase AC power, and part or all of a motor (not shown) that is driven by the three-phase AC power supplied from the inverter device (not shown).

[0018] The vehicle-mounted circuit breaking device 1 is connected to a vehicle power supply 14 and a vehicle load 15. A first pole 14A of the vehicle power supply 14 is connected to a first input terminal 2. A second pole 14B of the vehicle power supply 14 is connected to a second input terminal 5. The first pole 14A is a positive electrode and the second pole 14B is a negative electrode. A first pole 15A of the vehicle load 15 is connected to a first output terminal 3. A second pole 15B of the vehicle load 15 is connected to a second output terminal 6.

[0019] The first conductive path 4 connects the first input terminal 2 and the first output terminal 3. The second conductive path 7 connects the second input terminal 5 and the second output terminal 6. The first current detector 8 is provided so as to be able to detect the current flowing in the first conductive path 4. The second current detector 9 is provided so as to be able to detect the current flowing in the first conductive path 4. The pyrotechnic circuit breaker 10 is arranged so as to be able to irreversibly interrupt the first conductive path 4 on the positive potential side.

[0020] The control unit 11 is capable of receiving a first detection signal S1 transmitted from the first current detector 8 in response to the current to be detected flowing through the first conductive path 4, and a second detection signal S2 transmitted from the second current detector 9 in response to the current to be detected. The control unit 11 is also capable of controlling the interruption operation of the pyrotechnic circuit breaker 10.

[0021] Here, the step of obtaining the first detection signal S1 by the first current detector 8 is referred to as a first current detection step, and the step of obtaining the second detection signal S2 by the second current detector 9 is referred to as a second current detection step.

[0022] The control unit 11 may be a functional element including all of the functions such as a calculation function for determining the first current I1 based on the first detection signal S1 and a calculation function for determining the second current I2 based on the second detection signal S2, a memory function for storing the calculation results, and a function for issuing commands to the pyrotechnic circuit breaker 10. The functions of the control unit 11 may be provided as a single element or as multiple distributed elements.

[0023] Here, the step of determining the first current I1 based on the first detection signal S1 and the step of determining the second current I2 based on the second detection signal S2 is referred to as a calculation step.

[0024] Furthermore, the first detection signal S1 and the second detection signal S2 emitted by the first current detector 8 and the second current detector 9 may be analog data signals emitted from a shunt resistor or a Hall element, or may be digital data signals that are obtained by processing and converting the analog signals emitted from the shunt resistor or the Hall element into digital data signals.

[0025] Here, highly accurate current detection is possible when a detection method using shunt resistors in the first current detector 8 and the second current detector 9 is used. A shunt resistor is preferably used for current detection in the linear first conductive path 4 and the second conductive path 7, which are less likely to have parasitic inductance, or for current detection in the first conductive path 4 or the second conductive path 7, which are shorter in shape than the first conductive path 4 and the second conductive path 7.

[0026] Furthermore, current detection with high responsiveness is possible when a detection method using a Hall element for the first current detector 8 or the second current detector 9. Therefore, it is preferable to selectively apply a shunt resistor or a Hall element to the first current detector 8 or the second current detector 9 according to the characteristics required for current detection.

[0027] Furthermore, a first relay 16 is provided in the first conductive path 4 on the positive potential side, and the first relay 16 supplies and cuts off power from the vehicle power supply 14 to the vehicle load 15 in response to commands from the control unit 11. Similarly, a second relay 17 is provided in the second conductive path 7 on the negative potential side, and the second relay 17 supplies and cuts off power from the vehicle power supply 14 to the vehicle load 15 in response to commands from the control unit 11.

[0028] The control unit 11 causes the pyrotechnic circuit breaker 10 to perform a breaking operation when both the first current value I1 obtained based on the first detection signal S1 and the second current value I2 obtained based on the second detection signal S2 exceed the overcurrent threshold Ith. Here, the step of causing the pyrotechnic circuit breaker 10 to perform a breaking operation when both the first current value I1 and the second current value I2 exceed the overcurrent threshold Ith is referred to as a breaking process.

[0029] With the above configuration and operation, the use of multiple current detectors, the first current detector 8 and the second current detector 9, makes it possible to detect overcurrent and perform interruption operation based on the multiple detection results. Furthermore, when an overcurrent is detected by both the first current detector 8 and the second current detector 9, the control unit 11 determines that an overcurrent has occurred. This increases the probability that the current to be detected flowing through the first conductive path 4 is an overcurrent, allowing the control unit 11 to correctly determine that an overcurrent has occurred. As a result, the operational reliability of the vehicle-mounted circuit breaker 1 can be improved.

[0030] 2, which is a second circuit block diagram showing the configuration of the vehicle-mounted circuit breaker 1 according to the embodiment of the present invention, the first current detector 8 is provided so as to be able to detect the current flowing in the second conductive path 7. The second current detector 9 is provided so as to be able to detect the current flowing in the second conductive path 7.

[0031] In particular, here, the first current detector 8 and the second current detector 9 both detect the current flowing in the second conductive path 7, which is a conductive path with a negative potential, and the control unit 11 then makes a determination based on the first current value I1 and the second current value I2. As a result, the first current detector 8, the second current detector 9, and the pyrotechnic circuit breaker 10 are distributed between the second conductive path 7 and the first conductive path 4, making it possible to reduce the conductor lengths of the first conductive path 4 and the second conductive path 7.

[0032] As a result, it is possible to suppress the parasitic inductance and impedance occurring in the first conductive path 4 and the second conductive path 7, improving the accuracy of current detection when a sudden current fluctuation occurs, thereby improving the operational reliability of the vehicle circuit breaker 1 and the pyrotechnic circuit breaker 10. In addition, it is easier to achieve a balance in impedance between the first conductive path 4 and the second conductive path 7, making it possible to suppress common mode noise caused by ripples and noise in the current flowing through the first conductive path 4 and the second conductive path 7. This improves the current detection accuracy of the first current detector 8 and the second current detector 9, improving the operational reliability of the vehicle circuit breaker 1 and the pyrotechnic circuit breaker 10.

[0033] 3, which is a third circuit block diagram showing the configuration of the vehicle-mounted circuit breaker 1 according to the embodiment of the present invention, the first current detector 8 is provided to be able to detect the current flowing through the first conductive path 4. The second current detector 9 is provided to be able to detect the current flowing through the second conductive path 7.

[0034] In particular, here, the first current detector 8 detects the current flowing in the first conductive path 4, which is a conductive path with a positive potential, and the second current detector 9 detects the current flowing in the second conductive path 7, which is a conductive path with a negative potential, and then the control unit 11 makes a determination based on the first current value I1 and the second current value I2. This suppresses the influence of common mode noise from the vehicle load 15, making it possible to improve the reliability of the operation of the on-board circuit breaker 1 and the operation of the pyrotechnic circuit breaker 10.

[0035] Here, the first current detector 8 detects the current flowing in the first conductive path 4, which is a conductive path with a positive potential, and the second current detector 9 detects the current flowing in the second conductive path 7, which is a conductive path with a negative potential. As a result, common-mode noise caused by noise generated in the vehicle load 15, such as an inverter circuit, is canceled out in the first detection signal S1 and the second detection signal S2. This makes it possible to suppress the noise contained in the detected first current value I1 and second current value I2. As a result, the first detection signal S1 and the second detection signal S2 emitted from the first current detector 8 and the second current detector 9 become highly reliable signals, thereby improving the reliability of the operation of the on-board circuit breaker 1 and the operation of the pyrotechnic circuit breaker 10.

[0036] Furthermore, the first current detector 8 and the second current detector 9 may be configured to detect currents based on the potential difference across shunt resistors. The resistance values ​​of the first current detector 8 and the second current detector 9 may be set to different values, and the difference between the values ​​detected by the first current detector 8 and the second current detector 9 may be calculated to suppress the effects of parasitic inductance. As a result, overcurrents, which change significantly per unit time, can be detected with high accuracy, improving the reliability of the operation of the vehicle circuit breaker 1 and the pyrotechnic circuit breaker 10. In the above description, the control unit 11 determines that an overcurrent has occurred when an overcurrent is detected by both the first current detector 8 and the second current detector 9. Alternatively, the control unit 11 may determine that an overcurrent has occurred when an overcurrent is detected by at least one of the first current detector 8 and the second current detector 9. Therefore, when the current to be detected flowing through the first conductive path 4 is an overcurrent, the control unit 11 can determine that an overcurrent has occurred at the time when either the first current detector 8 or the second current detector 9, which has good responsiveness, detects the overcurrent. As a result, the operational reliability of the vehicle circuit breaker 1 can be improved.

[0037] Here, the first current detector 8 can detect the current flowing in the first conductive path 4 or the second conductive path 7. Furthermore, the second current detector 9 can detect the current flowing in the first conductive path 4 or the second conductive path 7. In particular, as shown in FIG. 1, the first current detector 8 and the second current detector 9 both detect the current flowing in the first conductive path 4, which is a conductive path with a positive potential, and then the control unit 11 makes a determination based on the first current value I1 and the second current value I2.

[0038] As a result, even if either the first current detector 8 or the second current detector 9 fails, an overcurrent can be detected by either the first current detector 8 or the second current detector 9 that is capable of normal operation, thereby improving operational safety when a failure occurs in either the first current detector 8 or the second current detector 9. Furthermore, a highly reliable detection function can be achieved without increasing the failure rate of the current detection function of the entire vehicle circuit breaker 1.

[0039] For example, if a current detection function failure occurs such that either the first detection signal S1 or the second detection signal S2 emitted from the first current detector 8 or the second current detector 9 is a fixed-high mode failure that erroneously recognizes an overcurrent detection state that exceeds the overcurrent threshold Ith, then either the first current detector 8 or the second current detector 9 will not be able to correctly detect the overcurrent and will malfunction. However, with the above configuration and operation, the current detection function can be maintained using either the first current detector 8 or the second current detector 9 that is normal.

[0040] As a result, the operational reliability of the vehicle circuit breaker 1, particularly the pyrotechnic circuit breaker 10, is improved. Even if either the first current detector 8 or the second current detector 9 outputs the first detection signal S1 or the second detection signal S2 as a false detection signal due to the influence of noise generated inside or outside the vehicle circuit breaker 1, the influence of the noise can be suppressed as long as the noise does not enter the first current detector 8 and the second current detector 9 simultaneously, thereby preventing false ignition of the pyrotechnic circuit breaker 10. In other words, by applying different current detection methods, such as a shunt resistor and a Hall element, to the first current detector 8 and the second current detector 9, it is possible to make the characteristics against noise different, and it is possible to suppress the influence of noise on the vehicle circuit breaker 1.

[0041] Furthermore, as shown in FIG. 2, the first current detector 8 and the second current detector 9 may both detect the current flowing through the second conductive path 7, which is a conductive path with a negative potential, and the control unit 11 may then make a judgment based on the first current value I1 and the second current value I2.

[0042] Furthermore, as shown in FIG. 3, the first current detector 8 may detect the current flowing in the first conductive path 4, which is a conductive path with a positive potential, and the second current detector 9 may detect the current flowing in the second conductive path 7, which is a conductive path with a negative potential, and the control unit 11 may then make a judgment based on the first current value I1 and the second current value I2.

[0043] In the above, the pyrotechnic circuit breaker 10 has been described as being arranged so as to be able to irreversibly interrupt the first conductive path 4 on the positive potential side. However, as shown in the fourth circuit block diagram of Fig. 4, which shows the configuration of the vehicle-mounted circuit breaker 1 according to the embodiment of the present invention, the pyrotechnic circuit breaker 10 may be arranged so as to be able to irreversibly interrupt the second conductive path 7 on the negative potential side.

[0044] Here, by using multiple current detectors, the first current detector 8 and the second current detector 9, it is possible to detect overcurrent and perform breaking operation based on the multiple detection results. Furthermore, because both the first current detector 8 and the second current detector 9 detect an overcurrent, the control unit 11 determines that an overcurrent has occurred. This increases the probability that the current to be detected flowing through the first conductive path 4 is an overcurrent, allowing the control unit 11 to correctly determine the occurrence of an overcurrent. As a result, the operational reliability of the vehicle-mounted circuit breaker 1 can be improved.

[0045] In particular, the first current detector 8 and the second current detector 9 both detect the current flowing in the first conductive path 4, which is a conductive path with a positive potential, and the control unit 11 then makes a determination based on the first current value I1 and the second current value I2. As a result, the first current detector 8, the second current detector 9, and the pyrotechnic circuit breaker 10 are distributed over the second conductive path 7 and the first conductive path 4, making it possible to reduce the conductor lengths of the first conductive path 4 and the second conductive path 7.

[0046] As a result, it is possible to suppress the parasitic inductance and impedance occurring in the first conductive path 4 and the second conductive path 7, improving the accuracy of current detection when a sudden current fluctuation occurs, thereby improving the operational reliability of the vehicle circuit breaker 1 and the pyrotechnic circuit breaker 10. In addition, it is easier to achieve a balance in impedance between the first conductive path 4 and the second conductive path 7, making it possible to suppress common mode noise caused by ripples and noise in the current flowing through the first conductive path 4 and the second conductive path 7. This improves the current detection accuracy of the first current detector 8 and the second current detector 9, improving the operational reliability of the vehicle circuit breaker 1 and the pyrotechnic circuit breaker 10.

[0047] 5, a fifth circuit block diagram showing the configuration of the vehicle-mounted circuit breaker 1 according to the embodiment of the present invention, pyrotechnic circuit breaker 10 is also arranged to irreversibly interrupt second conductive path 7 on the negative potential side, with first current detector 8 detecting the current flowing through first conductive path 4, which is the positive potential conductive path, and second current detector 9 detecting the current flowing through second conductive path 7, which is the negative potential conductive path. Control unit 11 then makes a determination based on first current value I1 and second current value I2. This suppresses the influence of common-mode noise from vehicle load 15, making it possible to improve the reliability of the operation of vehicle-mounted circuit breaker 1 and pyrotechnic circuit breaker 10.

[0048] Here, the first current detector 8 detects the current flowing in the first conductive path 4, which is a conductive path with a positive potential, and the second current detector 9 detects the current flowing in the second conductive path 7, which is a conductive path with a negative potential. Therefore, common-mode noise generated in the vehicle load 15, such as the inverter circuit, is canceled out and can be suppressed. As a result, the first detection signal S1 and the second detection signal S2 emitted from the first current detector 8 and the second current detector 9 become highly reliable signals, and the reliability of the operation of the on-board circuit breaker 1 and the operation of the pyrotechnic circuit breaker 10 is improved.

[0049] Furthermore, it is preferable that the first current detector 8 and the second current detector 9 perform current detection based on the potential difference across the shunt resistors. The resistance values ​​of the first current detector 8 and the second current detector 9 are set to different values, and the effect of parasitic inductance is suppressed by calculating the difference between the values ​​detected by the first current detector 8 and the second current detector 9. As a result, it is possible to detect with high accuracy overcurrents, which change significantly per unit time, and the reliability of the operation of the on-board circuit breaker 1 and the pyrotechnic circuit breaker 10 is improved. [Industrial Applicability]

[0050] The on-board circuit breaker device of the present invention has the effect of improving the reliability of circuit breaking operation, and is useful in various vehicles. [Explanation of symbols]

[0051] 1. Vehicle-mounted circuit breaker 2 First input terminal 3 First output terminal 4 First Conduction Path 5 Second input terminal 6 Second output terminal 7 Second conductive path 8 First current detector 9 Second current detector 10 Pyrotechnic Circuit Breaker 11 Control section 12 vehicles 13 Body 14 Vehicle power supply 14A 1st pole 14B 2nd pole 15 Vehicle Load 15A 1st pole 15B 2nd pole 16 First Relay 17 Second Relay

Claims

1. a first input terminal to which DC power of a first polarity is supplied; a first output terminal; a first conductive path connecting the first input terminal and the first output terminal; a second input terminal to which DC power of a second polarity opposite to the first polarity is supplied; a second output terminal; a second conductive path connecting the second input terminal and the second output terminal; a first current detector disposed in the second conductive path and capable of detecting a current flowing in the second conductive path; and a second current detector disposed in the second conductive path and capable of detecting a current flowing in the second conductive path. a pyrotechnic circuit breaker disposed in the first conductive path and operable to irreversibly interrupt the first conductive path; a circuit breaker control unit capable of receiving a first detection signal and a second detection signal transmitted from the first current detector and the second current detector in response to the detected currents, and capable of controlling the circuit breaker's circuit breaker operation, shunt resistors are used for the first current detector and the second current detector, and the first current detector and the second current detector have different resistance values; The cutoff control unit is a difference between the values ​​detected by the first current detector and the second current detector is calculated, and when both a first current value obtained based on the first detection signal and a second current value obtained based on the second detection signal exceed an overcurrent threshold, the pyrotechnic circuit breaker is caused to perform a circuit breaker operation. Vehicle-mounted circuit breaker.

2. a first input terminal to which DC power of a first polarity is supplied; a first output terminal; a first conductive path connecting the first input terminal and the first output terminal; a second input terminal to which DC power of a second polarity opposite to the first polarity is supplied; a second output terminal; a second conductive path connecting the second input terminal and the second output terminal; a first current detector capable of detecting a current flowing through the first conductive path; and a second current detector capable of detecting a current flowing through the second conductive path. a pyrotechnic circuit breaker operable to irreversibly interrupt the first conductive path; a circuit breaker control unit capable of receiving a first detection signal and a second detection signal transmitted from the first current detector and the second current detector in response to the detected currents, and capable of controlling the circuit breaker's circuit breaker operation, shunt resistors are used for the first current detector and the second current detector, and the first current detector and the second current detector have different resistance values; The cutoff control unit is a difference between the values ​​detected by the first current detector and the second current detector is calculated, and when both a first current value obtained based on the first detection signal and a second current value obtained based on the second detection signal exceed an overcurrent threshold, the pyrotechnic circuit breaker is caused to perform a circuit breaker operation. Vehicle-mounted circuit breaker.

3. a first input terminal to which DC power of a first polarity is supplied; a first output terminal; a first conductive path connecting the first input terminal and the first output terminal; a second input terminal to which DC power of a second polarity opposite to the first polarity is supplied; a second output terminal; a second conductive path connecting the second input terminal and the second output terminal; a first current detector capable of detecting a current flowing in the first conductive path or the second conductive path; a second current detector capable of detecting a current flowing in the first conductive path or the second conductive path; and a pyrotechnic circuit breaker capable of operating to irreversibly interrupt the first conductive path. a circuit breaker control unit capable of receiving a first detection signal and a second detection signal transmitted from the first current detector and the second current detector in response to the detected currents, and capable of controlling the circuit breaker's circuit breaker operation, shunt resistors are used for the first current detector and the second current detector, and the first current detector and the second current detector have different resistance values; The cutoff control unit is a difference between the values ​​detected by the first current detector and the second current detector is calculated, and when both a first current value obtained based on the first detection signal and a second current value obtained based on the second detection signal exceed an overcurrent threshold, the pyrotechnic circuit breaker is caused to perform a circuit breaker operation. Vehicle-mounted circuit breaker.

4. a first input terminal to which DC power of a first polarity is supplied; a first output terminal; a first conductive path connecting the first input terminal and the first output terminal; a second input terminal to which DC power of a second polarity opposite to the first polarity is supplied; a second output terminal; a second conductive path connecting the second input terminal and the second output terminal; and a disconnection method for disconnecting the first conductive path in an on-board disconnection device, the method comprising: a first current detection step of detecting a current flowing through the first conductive path using a shunt resistor; and a second current detection step of detecting a current flowing through the second conductive path using a shunt resistor having a resistance value different from that of the shunt resistor used in the first current detection step. a calculation step of calculating a difference between the values ​​detected in the first current detection step and the second current detection step, and obtaining a first current value based on the first detection signal and a second current value based on the second detection signal using a first detection signal and a second detection signal obtained by the first current detection step and the second current detection step; a breaking step of irreversibly breaking the first conductive path when both the first current value and the second current value exceed an overcurrent threshold. Blocking method.

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