Switch-off device and program

Abstract

To appropriately perform switch shut-off when an overcurrent abnormality occurs in an electric path.SOLUTION: A switch shut-off device 80 is applied to a power supply system comprising: a first power source 11 and a second power source 12 which are connected via an electric path 50; and first to seventh switches 61 to 67 which are provided in the electric path 50. The switch shut-off device 80 comprises: a calculation section for acquiring electrification currents each flowing to a pair of switches, which are two switches adjacent to each other in the electric path 50, and calculating a total current which is a total of currents flowing to an intermediate point of the pair of switches; and a shut-off section which shuts off the pair of switches in a case where the total current exceeds a threshold current.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a switch shutoff device for a power supply system and a program therefor. [Background technology]

[0002] Conventionally, power supply systems have been known that include multiple power sources and are capable of supplying power from each of these multiple power sources to an electrical load. For example, Patent Document 1 describes a switch tripping device applied to a power supply system that determines whether an abnormality has occurred in which the output current of a power source becomes excessively large, and trips a switch based on the determination result. Specifically, the switch tripping device acquires the current flowing through the switch, and determines that an abnormality has occurred if the acquired current flowing through the switch exceeds a threshold current. Then, by tripping a switch through which a current flowing that exceeds the threshold current flows, the switch prevents an overcurrent from flowing in the power supply system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-62727 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrical path of a power supply system, if a ground fault occurs between a first power source and a second power source, or if an overcurrent abnormality occurs due to a runaway electrical load, the current flowing in the electrical path increases. In such cases, existing technologies trip the switch based on the magnitude of the current flowing from one of the power sources, which raises concerns about its low reliability. For example, if a ground fault occurs in the electrical path of a power supply system, the supply current from one of the power sources increases due to the ground fault, but if the increase in current is small, there is a concern that the switch may not trip appropriately in response to the ground fault abnormality.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a switch tripping device that can appropriately trip a switch when an overcurrent abnormality occurs in an electrical path. [Means for solving the problem]

[0006] The present invention provides a first power source and a second power source connected via an electrical path; a plurality of switches provided in the electrical path and connected in series to one another, a calculation unit that acquires currents flowing through a pair of switches that are two adjacent switches in the electrical path, and calculates a total current that is the sum of currents flowing to a midpoint of the pair of switches based on the currents; and a cutoff unit that cuts off the pair of switches when the total current exceeds a threshold current.

[0007] In the power supply system having the above configuration, a plurality of switches are provided in an electrical path between the first power supply and the second power supply, and are connected in series with each other. In this power supply system, if an overcurrent abnormality occurs between the first power supply and the second power supply due to a ground fault or the like, for example, the increase in current due to the ground fault or the like cannot be correctly determined from the current flowing through only one of the switches, and there is a concern that the appropriate switch shutoff in response to the overcurrent abnormality cannot be performed.

[0008] Therefore, according to the present invention, the currents flowing through a pair of adjacent switches in an electrical path are acquired, and a total current, which is the sum of the currents flowing to a midpoint between the pair of switches, is calculated based on the currents. The pair of switches are then shut off when the total current exceeds a threshold current. In this case, if an overcurrent abnormality such as a ground fault occurs between the pair of switches, the currents flowing from both power sources to the midpoint increase through the pair of switches. That is, the total current reflects changes in the current flowing from the first power source to the midpoint through the switch on the first power source side of the switch on both sides of the midpoint, and changes in the current flowing from the second power source to the midpoint through the switch on the second power source side of the switch on both sides of the midpoint. Therefore, the total current can accurately grasp the current increase during an abnormality. As a result, the reliability of abnormality determination is improved, and the switches can be appropriately shut off when an overcurrent abnormality occurs in the electrical path. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the overall configuration of an in-vehicle power supply system according to a first embodiment. [Figure 2] FIG. 1 is a diagram for explaining problems with existing technology. [Figure 3] FIG. 1 is a diagram for explaining problems with existing technology. [Figure 4] FIG. [Figure 5] FIG. 2 is a diagram showing the configuration of an interrupter circuit. [Figure 6] A diagram showing the current detection function of a switch. [Figure 7] 6 is a flowchart showing a switch-off sequence executed by the interruption circuit. [Figure 8] FIG. 10 is a diagram showing the overall configuration of an in-vehicle power supply system according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing an example of switch interruption performed by an interruption circuit and a path separation circuit. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment A first embodiment of a switch cutoff device according to the present invention will be described below with reference to the drawings. In this embodiment, the switch cutoff device is applied to an on-board power supply system. The power supply system is mounted on an electric vehicle that uses a motor as a driving power source.

[0011] As shown in Fig. 1, the power supply system has a first power supply 11 and a second power supply 12, which are connected by an electrical path 50. The first power supply 11 includes a high-voltage battery 21, a rotating electric machine 22, and a DC-DC converter 23. The high-voltage battery 21 is configured as a series connection of a plurality of unit cells, and the rated voltage of the high-voltage battery 21 is, for example, several hundred volts. Each unit cell is a rechargeable storage battery, specifically a lithium-ion storage battery.

[0012] The rotating electric machine 22 is a power source for driving the vehicle, and receives power from the high-voltage battery 21 to transmit power to the drive wheels of the vehicle. The rotating electric machine 22 also functions as a generator that performs regenerative power generation while the vehicle is running. The rotating electric machine 22 has an inverter that controls the current of each phase, and the high-voltage battery 21 is connected to the inverter. This enables current to flow between the high-voltage battery 21 and the rotating electric machine 22. The DC-DC converter 23 is connected to the high-voltage battery 21 and reduces the high voltage on the high-voltage battery 21 side.

[0013] The second power source 12 has a low-voltage battery, which is a rechargeable storage battery. The low-voltage battery is a lead-acid battery or a lithium-ion storage battery. The rated voltage of the low-voltage battery is lower than the rated voltage of the high-voltage battery 21, for example, 12 V. The output voltage of the first power source 11 and the output voltage of the second power source 12 are substantially the same. However, in this embodiment, the output voltage of the first power source 11 is set to be slightly higher than the terminal voltage of the second power source 12.

[0014] The electrical path 50 includes a first path 51 and a second path 52 as parallel paths that are parallel to each other. The electrical path 50 branches into two paths between a branch point P on the first power source 11 side and a branch point Q on the second power source 12 side, whereby the first path 51 and the second path 52 are connected in parallel.

[0015] The power supply system includes, as electrical loads, first to fourth normal loads 31 to 34 and first and second redundant loads 41 and 42. Each of the loads 31 to 34, 41 and 42 can be supplied with power from the first power source 11 and the second power source 12. Each of the normal loads 31 to 34 is, for example, an electrical load that is not used for vehicle driving assistance control, and specifically includes an air conditioner, audio equipment, power windows, an electric fan in a radiator that cools engine coolant, stop lamps, interior lights, a USB power socket, and a motor that drives a mirror provided outside the vehicle cabin.

[0016] Each of the redundant loads 41, 42 can realize a specific function either as both redundant loads or as one redundant load. This prevents the loss of all of the functions even if an abnormality occurs in one of the redundant loads 41, 42. Each of the redundant loads 41, 42 is, for example, an electric load used for vehicle driving assistance control, and more specifically, is an electric power steering device that generates an assist torque to assist the driver in steering, an electric brake device that applies braking force to the wheels, a camera for monitoring the conditions around the vehicle, a laser radar such as LIDAR (Laser Imaging Detection and Ranging), a millimeter-wave radar, or a by-wire system.

[0017] Note that a specific function may be realized by combining different types of devices as the redundant loads 41 and 42. For example, the first redundant load 41 may be a LIDAR and the second redundant load 42 may be a camera, both of which are intended to monitor the area ahead of the vehicle.

[0018] The first path 51 is connected to first and second normal loads 31 and 32 and first and second redundant loads 41 and 42. The first and second normal loads 31 and 32 and the first and second redundant loads 41 and 42 are connected to connection points A, B, C, and D of the first path 51, respectively. The second path 52 is connected to third and fourth normal loads 33 and 34. The third and fourth normal loads 33 and 34 are connected to connection points E and F of the second path 52, respectively. The positive poles of the loads 31 to 34, 41, and 42 are connected to the respective paths 51 and 52, and the negative poles are connected to a grounded portion of the vehicle body or the like. Note that the loads 31 to 34, 41, and 42 shown in FIG. 1 may each be a single electric load or multiple electric loads.

[0019] The power supply system includes first to seventh switches 61 to 67. Each of the switches 61 to 67 is configured by, for example, a semiconductor switch such as a relay or a MOSFET. The first switch 61 is provided in the first path 51 between a branch point P and a connection point A of the first normal load 31. The second switch 62 is provided in the first path 51 between a connection point B of the first redundant load 41 and a connection point C of the second normal load 32. The third switch 63 is provided in the first path 51 between a connection point D of the second redundant load 42 and a branch point Q.

[0020] The fourth switch 64 is provided in the second path 52 between the branch point P and the connection point E of the third normal load 33. The fifth and sixth switches 65 and 66 are provided in the second path 52 between the connection point E of the third normal load 33 and the connection point F of the fourth normal load 34. The seventh switch 67 is provided in the second path 52 between the connection point F of the fourth normal load 34 and the branch point Q.

[0021] The power supply system includes a control device 70 that controls the on / off of each of the switches 61 to 67. The control device 70 is mainly configured with a microcomputer having a CPU and various memories. The control device 70 turns on each of the switches 61 to 67 in response to an on-operation of a vehicle start switch, for example, and turns off each of the switches 61 to 67 in response to an off-operation of the start switch.

[0022] The power supply system also includes a switch tripping device 80 that, when an overcurrent abnormality occurs in which excessive current flows through the first and second paths 51 and 52, trips one of the switches 61 to 67 corresponding to the location of the abnormality. This prevents overcurrent from flowing through the power supply system. Note that overcurrent abnormalities occur due to a ground fault in which any location on the electrical path is short-circuited to the ground, or due to a runaway electrical load.

[0023] Incidentally, when an overcurrent abnormality occurs in the electrical path 50 of a power supply system having two power sources 11 and 12, the current flowing in the electrical path 50 increases. However, with existing technology, a switch is turned off based on the magnitude of the current flowing from one of the power sources, and there are concerns about its low reliability.

[0024] Here, problems with the existing technology will be explained using the configuration shown in Fig. 2 as an example. The power supply system includes a first power supply 101 and a second power supply 102, an electrical load 104 connected to an electrical path 103 connecting the first power supply 101 and the second power supply 102, and switches 105 and 106 provided on the first power supply 101 side and the second power supply 102 side, respectively, of the electrical path 103 with respect to the connection point of the electrical load 104. Current is supplied to the electrical load 104 from both the first power supply 101 and the second power supply 102. In Fig. 2, the output current of the first power supply 101 is indicated by i1, the output current of the second power supply 102 is indicated by i2, and the supply current supplied from each of the power supplies 101 and 102 to the electrical load 104 is indicated by ia.

[0025] FIG. 3 shows the transitions of the output currents i1 and i2 and the supply current i1 when a ground fault occurs in the electrical load 104. When a ground fault occurs at time t1, the current flowing through the electrical load 104 increases. This causes the supply current i1 to rise and exceed the upper limit im of the current flowing through the electrical load 104 when no ground fault occurs. However, if the leakage current due to the ground fault is relatively small, i.e., if a relatively minor ground fault occurs, the supply current i1 exceeds the upper limit im, but the increase amounts Δi1 and Δi2 of the output currents i1 and i2 may be too small to determine whether a ground fault has occurred. In this case, there is a concern that the reliability of switch tripping may be reduced in existing technologies that determine the presence or absence of a ground fault based on either the conduction current flowing through the switches 105 and 106.

[0026] In view of the above, the power supply system includes a switch tripping device 80. The switch tripping device 80 includes a calculation unit that acquires the current flowing through each of a pair of switches, which are two adjacent switches in the electrical path 50, and calculates a total current that is the sum of the currents flowing to a midpoint of the pair of switches based on the current flowing through each of the pair of switches, and a tripping unit that trips the pair of switches when the total current exceeds a threshold current.

[0027] In this embodiment, two adjacent switches in each of the paths 51 and 52 form a pair of switches. A plurality of combinations of pairs of switches are defined for each electrical load connected therebetween. Specifically, in the first path 51, the first and second switches 61 and 62 on both sides of each of the connection points A and B, and the second and third switches 62 and 63 on both sides of each of the connection points C and D, form a pair of switches. In this case, the first and second switches 61 and 62 on the first path 51, which are positioned between only the first connection point B (first connection point) to which the first redundant load 41 is connected and the connection point D (second connection point) to which the second redundant load 42 is connected, form a pair of switches, and the second and third switches 62 and 63 on the second connection point B and D, which are positioned between only the second connection point B and D, form a pair of switches. In addition, the second path 52 is provided with fourth and fifth switches 64, 65 on both sides of each connection point E, and sixth and seventh switches 66, 67 on both sides of each connection point F.

[0028] As shown in Fig. 4, the switch interruption device 80 includes an interruption circuit 81 for each combination of a pair of switches. A pair of switches consisting of a combination of first and second switches 61 and 62; A pair of switches consisting of a combination of second and third switches 62, 63; A pair of switches consisting of a combination of fourth and fifth switches 64, 65; A pair of switches consisting of a combination of sixth and seventh switches 66 and 67; Each of these interrupting circuits 81 has the function of calculating the total current of the corresponding pair of switches when a ground fault occurs, and performing an interrupting operation on the pair of switches based on the total current.

[0029] 4, a breaker circuit 81 is also provided for the pair of switches formed by the combination of the fifth and sixth switches 65 and 66, in anticipation of a possibility of a ground fault occurring in the wiring portion between the fifth and sixth switches 65 and 66.

[0030] 5, the configuration of interrupter circuits 81 provided in first path 51 for a pair of switches consisting of a combination of first and second switches 61, 62 and a pair of switches consisting of a combination of second and third switches 62, 63 will be described. Note that here, interrupter circuit 81 for first and second switches 61, 62 will be referred to as "interrupter circuit 81A," and interrupter circuit 81 for second and third switches 62, 63 will be referred to as "interrupter circuit 81B."

[0031] The first and second switches 61 to 63 are each provided with a current sensor 85. It is preferable that each switch and current sensor 85 have the following configuration. As shown in FIG. 6, the first switch 61 is two N-channel MOSFETs whose sources are connected to each other. A current sensor 85 is provided between the sources of the two N-channel MOSFETs. The current sensor 85 detects current using, for example, a shunt resistor or a Hall element. The second to seventh switches 62 to 67 have a similar configuration.

[0032] 5, interrupter circuit 81A includes an adder 82, a determiner 83, and an interrupter driver 84. Adder 82 acquires the conduction current flowing through each of first and second switches 61, 62. Specifically, adder 82 acquires the detection value of current sensor 85 of first switch 61 as the conduction current flowing through first switch 61, and acquires the detection value of current sensor 85 of second switch 62 as the conduction current flowing through second switch 62.

[0033] The adder 82 calculates a total current Is, which is the sum of the currents flowing to the midpoint (connection points A and B) between the first and second switches 61 and 62, based on the currents flowing through the first and second switches 61 and 62. In this case, the adder 82 calculates the total current Is by considering the direction of the current flowing through the first switch 61 in which a discharge current flows from the first power source 11 as positive, and the direction of the current flowing through the second switch 62 in which a discharge current flows from the second power source 12 as positive. The total current Is calculated by the adder 82 is input to the determination unit 83. The adder 82 is configured using, for example, an operational amplifier.

[0034] The determination unit 83 determines whether the total current Is calculated by the adder 82 exceeds the threshold current. If the determination unit 83 determines that the total current Is calculated by the adder 82 exceeds the threshold current, it determines that an overcurrent abnormality has occurred between the first and second switches 61, 62 in the first path 51, and switches the logic of the shutdown signal Sg from LOW to HI. The shutdown signal Sg is a signal that informs the shutdown driver 84 to maintain the conductive state of the first and second switches 61, 62 by a logic LOW, and informs the shutdown driver 84 to shut off the first and second switches 61, 62 by a logic HI. The determination unit 83 is configured using, for example, an operational amplifier.

[0035] When a logic LOW shutdown signal Sg is input, the shutdown driver 84 maintains the conductive state of the first and second switches 61, 62. On the other hand, when a logic HI shutdown signal Sg is input, the shutdown driver 84 shuts off the first and second switches 61, 62. This electrically disconnects the overcurrent abnormality location from the first power source 11 and the second power source 12. The adder 82 corresponds to the "calculator," and the determination unit 83 and the shutdown driver 84 correspond to the "shutdown unit." The shutdown circuit 81B has a configuration similar to that of the shutdown circuit 81A.

[0036] 7 illustrates the order of switching off performed by each shutoff circuit 81. Here, the switching off performed by the shutoff circuit 81A shown in FIG. 5 will be described as an example.

[0037] In the interruption circuit 81A, the adder 82 acquires the current flowing through each of the first and second switches 61 and 62, and calculates the total current Is, which is the sum of the currents flowing to the midpoints (connection points A and B) between the first and second switches 61 and 62, based on the current flowing through each of the first and second switches 61 and 62 (steps S10 and S11).

[0038] The determination unit 83 determines whether the total current Is of the first and second switches 61, 62 exceeds the threshold current Ith (step S12). The threshold current Ith is set to a value greater than the upper limit current when driving an electrical load connected between the first and second switches 61, 62. In a configuration in which the first normal load 31 and the first redundant load 41 are connected between the first and second switches 61, 62, the threshold current Ith is preferably equal to or greater than the sum of the upper limit values ​​of the drive currents of the loads 31, 41. Note that when only one of the first and second switches 61, 62 is in a driven state, the threshold current Ith may be set to a value greater than the upper limit value of the drive current of the driven load.

[0039] If the determination unit 83 determines that the total current Is of the first and second switches 61, 62 is equal to or less than the threshold current Ith, it keeps the shutdown signal Sg at logic LOW. In this case, the shutdown driver 84 keeps the on / off states of the first and second switches 61, 62 unchanged. On the other hand, if the determination unit 83 determines that the total current Is of the first and second switches 61, 62 exceeds the threshold current Ith, it outputs a logic HI shutdown signal Sg. In this case, the shutdown driver 84 shuts off the first and second switches 61, 62 (step S13).

[0040] The processing of the above-mentioned interrupting circuit 81A is performed in parallel in the same manner in the other interrupting circuits 81 in the switch interrupting device 80. As a result, even if an overcurrent abnormality due to a ground fault or the like occurs in any electrical load in the electrical path 50, appropriate switch interruption can be performed depending on the location of the abnormality.

[0041] According to the present embodiment described above in detail, the following effects can be obtained.

[0042] The currents flowing through a pair of adjacent switches in the electrical path 50 are acquired, and a total current Is, which is the sum of the currents flowing to the midpoint between the pair of switches, is calculated based on the acquired currents. The pair of switches are then shut off when the total current Is exceeds a threshold current Ith. In this case, if an overcurrent abnormality such as a ground fault occurs between the pair of switches, the currents flowing from the first power source 11 and the second power source 12 to the midpoint increase via the pair of switches. That is, the total current reflects changes in the current flowing from the first power source 11 to the midpoint via the switch on the first power source 11 side of the pair of switches and changes in the current flowing from the second power source 12 to the midpoint via the switch on the second power source 12 side of the pair of switches. Therefore, the total current Is can accurately determine the current increase during an abnormality. As a result, the reliability of abnormality determination is improved, and the switches can be appropriately shut off when an overcurrent abnormality occurs in the electrical path.

[0043] For each pair of adjacent switches in the electrical path 50, the total current is calculated, and the pair of switches on both sides of the midpoint is turned off based on the total current. This makes it possible to identify the location of the abnormality by determining an abnormality using the total current, and to disconnect only the identified abnormality location from the first power source 11 and the second power source 12. As a result, it is possible to continue supplying power from the first power source 11 and the second power source 12 to electrical loads connected to locations other than the location where the abnormality has occurred.

[0044] The threshold current Ith is set to a value greater than the upper limit current when driving an electrical load connected between a pair of switches, thereby preventing the total current Is from exceeding the threshold current Ith due to use of the electrical load, thereby preventing erroneous determination that an abnormality has occurred.

[0045] In the first path 51, the first and second switches 61 and 62 located between the connection point B of the first redundant load 41 and the connection point D of the second redundant load 42 are configured as a pair of switches, and the second and third switches 62 and 63 located between the connection point D are configured as a pair of switches. This allows the functions realized by the redundant loads 41 and 42 to continue even if one of the pair of switches is shut off.

[0046] In the above configuration, first to third switches 61 to 63 are provided in the first path 51, and fourth to seventh switches 64 to 67 are provided in the second path 52. The first path 51 and the second path 52 are provided in parallel with each other. In this case, when an overcurrent abnormality occurs in either the first path 51 or the second path 52 and the abnormal part is disconnected from the first power source 11 and the second power source 12, power supply from both the first power source 11 and the second power source 12 can be continued in the path where the overcurrent abnormality is not occurring.

[0047] Second Embodiment In this embodiment, the configuration of the switch interrupter 80 is modified. In a power supply system, if an overcurrent abnormality occurs somewhere on the electrical path 50 due to a ground fault or the like, a voltage drop occurs on the electrical path 50, causing a disruption in both the power supply from the first power source 11 to each electrical load and the power supply from the second power source 12 to each electrical load. Therefore, in this embodiment, the voltage of the electrical path 50 is acquired as a path voltage, and when the path voltage falls below a threshold voltage, the electrical path 50 is divided into the first power source 11 side and the second power source 12 side.

[0048] Figure 8 is a schematic diagram showing the configuration of a power supply system in this embodiment. Similar to Figure 4, switch interruption device 80 includes an interruption circuit 81 for each combination of a pair of switches in electrical path 50. Here, the four interruption circuits 81 are designated as interruption circuits 81A, 81B, 81C, and 81D, respectively. In this embodiment, each of interruption circuits 81A to 81D corresponds to a "first interruption section."

[0049] 8 differs from FIG. 4 in that voltage sensors 53 and 54 are provided on the first path 51 and the second path 52, respectively. The voltage sensor 53 is provided, for example, near the second switch 62 on the first path 51, and detects the voltage on the first path 51. The voltage sensor 54 is provided, for example, near the sixth switch 66 on the second path 52, and detects the voltage on the second path 52.

[0050] The switch interruption device 80 includes a path interruption circuit 91 that interrupts the first path 51 and the second path 52 into the first power source 11 side and the second power source 12 side, respectively, based on the detected voltages of the voltage sensors 53 and 54. In this embodiment, the second switch 62 provided between two adjacent connection points B and C in the first path 51 and the sixth switch 66 provided between two adjacent connection points E and F in the second path 52 serve as the inter-load switch. In the first path 51, the second switch 62 between the two redundant loads 41 and 42 that achieve the same function serves as the inter-load switch.

[0051] The path separation circuit 91 acquires the detected voltages of the voltage sensors 53 and 54 as path voltages, and when at least one of the path voltages falls below a threshold voltage, it interrupts the inter-load switches (switches 62 and 66), thereby separating the first path 51 and the second path 52 into the first power source 11 side and the second power source 12 side, respectively. The threshold voltage is set to, for example, the highest voltage at which the loads 31 to 34, 41, and 42 can operate. Like the interruption circuit 81, the path separation circuit 91 is configured by an electronic circuit, which is hardware.

[0052] In the first path 51, the first redundant load 41 and the second normal load 32 connected to the connection points B and C correspond to the "first electrical load" and the "second electrical load", respectively, and in the second path 52, the third normal load 33 and the fourth normal load 34 connected to the connection points E and F correspond to the "first electrical load" and the "second electrical load", respectively. In the second path 52, the fifth switch 65 can be used as an inter-load switch instead of the sixth switch 66. In this embodiment, the path separation circuit 91 corresponds to the "second interrupter".

[0053] When an overcurrent abnormality occurs in the power supply system due to the occurrence of a ground fault or the like, the second and sixth switches 62, 66 are turned off, dividing the electrical path 50 into two. One of the divided electrical paths 50 uses the first power source 11 as a power supply source to supply power to the first and third normal loads 31, 33 and the first redundant load 41. The other uses the second power source 12 as a power supply source to supply power to the second and fourth normal loads 32, 34 and the second redundant load 42. Therefore, when a voltage drop occurs in the electrical path 50 due to a ground fault, power supply failure is suppressed for all electrical loads, and it is possible for some electrical loads to continue operating.

[0054] The process of shutting off a pair of switches by each shutoff circuit 81 and the process of shutting off the inter-load switches (second and sixth switches 62, 66) by the path separation circuit 91 are executed in parallel. When an overcurrent abnormality occurs, a voltage change in the electrical path 50 may occur before a current change in the current flowing through each of the switches 61 to 67 due to the inductance component of the electrical path. Furthermore, for detecting a change in the current flowing through the electrical path 50, the voltage sensors 53, 54 may be more suitable than the current sensors of the switches 61 to 67. In this regard, in this embodiment, the path separation circuit 91 shuts off the second and sixth switches 62, 66 in response to a voltage change in the electrical path 50, so that the switches can be shut off quickly when an overcurrent abnormality occurs.

[0055] Furthermore, if an overcurrent abnormality occurs and the electrical path 50 is divided into the first power source 11 side and the second power source 12 side, an overcurrent continues to flow through the electrical path 50 on the side where the overcurrent abnormality occurred, either the first power source 11 side or the second power source 12 side of the electrical path 50. Therefore, in each interruption circuit 81, when the total current flowing through a pair of switches to be interrupted exceeds a threshold current, the pair of switches are interrupted.

[0056] Here, if the path separation circuit 91 cuts off the load switch due to a voltage drop in the electrical path 50 caused by a ground fault or the like, and then each cutoff circuit 81 further cuts off the pair of switches in accordance with the total current flowing through the pair of switches, the path separation circuit 91 may unnecessarily cut off the second and sixth switches 62, 66.

[0057] For example, if a ground fault occurs in the third normal load 33 on the second path 52 side, the path dividing circuit 91 cuts off the inter-load switches (the second and sixth switches 62 and 66), and then the interrupting circuit 81C cuts off the fourth and fifth switches 64 and 65. In this case, if the inter-load switches (the second and sixth switches 62 and 66) remain cut off, the power supply from the first power source 11 and the second power source 12 to the loads 31, 32, 41, and 42 on the first path 51 on the side where no short circuit has occurred is unnecessarily restricted.

[0058] Therefore, in this embodiment, when the inter-load switches (second and sixth switches 62, 66) are cut off by the path separation circuit 91 and a pair of switches are cut off by the cut-off circuit 81, the switches that are the target of cutting off by the path separation circuit 91 but are not the target of cutting off by the cut-off circuit 81 are configured to return to a conductive state.

[0059] Specifically, when the second and sixth switches 62 and 66 are cut off as inter-load switches, the path dividing circuit 91 restores at least one of the second switch 62 and the sixth switch 66 to a conductive state in accordance with the logic of the cutoff signal Sg input from each cutoff circuit 81. In this embodiment, the path dividing circuit 91 corresponds to the "restore operation unit."

[0060] When a logic HI shutoff signal Sg (i.e., a signal indicating that the switch is to be shut off) is input from the shutoff circuit 81 after the inter-load switches (second and sixth switches 62 and 66) have been shut off, the path disconnection circuit 91 restores conduction to the inter-load switches of the paths 51 and 52 opposite to the shutoff signal input. Furthermore, when a logic HI shutoff signal Sg is input from the shutoff circuit 81 after the inter-load switches (second and sixth switches 62 and 66) have been shut off, the path disconnection circuit 91 restores conduction to the inter-load switches of the paths 51 and 52 that are the same as the paths that received the shutoff signal input, provided that the inter-load switches are not the ones targeted for shutoff by the shutoff circuit 81.

[0061] In detail, the path disconnection circuit 91 selectively restores the conduction of each of the inter-load switches (the second and sixth switches 62 and 66) as follows. When a logic high interruption signal Sg is received from the interruption circuit 81A, the sixth switch 66 is returned to the conductive state. When a logic HI shutoff signal Sg is received from the shutoff circuit 81B, the sixth switch 66 is returned to the conductive state. When a logic HI shutoff signal Sg is received from the shutoff circuit 81C, the second and sixth switches 62 and 66 are returned to the conductive state. When a logic HI shutoff signal Sg is received from the shutoff circuit 81D, the second switch 62 is returned to the conductive state.

[0062] 9 shows an example of switch shutdown performed by each shutdown circuit 81 and the path separation circuit 91. Here, we will explain the case where a ground fault occurs in the third normal load 33 when all of the switches 61 and 67 are on, as shown in FIG. 9(a).

[0063] After a ground fault occurs in the third normal load 33, the path voltage in the second path 52 decreases, and when the path voltage of the second path 52 decreases below the threshold voltage, the second and sixth switches 62 and 66, which are inter-load switches, are turned off, as shown in Fig. 9(b). As a result, the first path 51 and the second path 52 are separated into the first power source 11 side and the second power source 12 side, respectively.

[0064] Furthermore, when a ground fault occurs in the third normal load 33, the total current of the fourth and fifth switches 64, 65, which are a pair of switches corresponding to the third normal load 33, increases. Therefore, when the total current of the fourth and fifth switches 64, 65 rises above the threshold current, the fourth and fifth switches 64, 65 are turned off, as shown in FIG. 9(c).

[0065] In Fig. 9(c), the second and sixth switches 62 and 66, which are inter-load switches, are shut off, and the second and sixth switches 62 and 66 are not targets for shutoff by the shutoff circuit 81. Therefore, as shown in Fig. 9(d), the second and sixth switches 62 and 66 are restored to the conductive state.

[0066] 9(c), the second and sixth switches 62 and 66 are redundantly in the off state even though the location where the abnormality actually occurs in the second path 52, where the ground fault is occurring, is isolated by the off state of the fourth and fifth switches 64 and 65. In this state, the power supply from the first power source 11 and the second power source 12 to the loads 31, 32, 41, and 42 on the first path 51 on the side where the short circuit does not occur is unnecessarily restricted, but as shown in FIG. 9(d), the second switch 62 is restored to conduction, thereby releasing the unnecessary power restriction on the first path 51.

[0067] 9(c), in addition to the fourth and fifth switches 64 and 65, the sixth switch 66 is in the cut-off state in the second path 52, so if an electrical load 35 is connected to the connection point X between the fifth and sixth switches 65 and 66, power is unnecessarily cut off to the electrical load 35. In this regard, by restoring conductivity to the sixth switch 66 as shown in FIG. 9(d), the number of paths for power cut-off is reduced to the necessary minimum, and the unnecessary power cut-off is canceled.

[0068] In the present embodiment described above in detail, when the path voltage of the electrical path 50 falls below the threshold voltage, the inter-load switch is turned off, and the electrical path 50 is separated into the first power source 11 side and the second power source 12 side. As a result, when an overcurrent abnormality occurs at any point on the electrical path 50 due to a ground fault or the like, the first power source 11 side and the second power source 12 side are separated, and it is possible to prevent a power failure from occurring in the entire electrical path 50.

[0069] The inter-load switch is provided at a position in the electrical path 50 between the first redundant load 41 and the second redundant load 42. This allows the functions realized by the redundant loads 41 and 42 to continue immediately after the inter-load switch is turned off due to a drop in the path voltage.

[0070] When the inter-load switch is cut off by the path separation circuit 91 and the pair of switches is cut off by the interruption circuit 81, the switches among the multiple switches that are the target of interruption by the path separation circuit 91 (i.e., the inter-load switch) but are not the target of interruption by the interruption circuit 81 are configured to return to a conductive state. This makes it possible to prevent the switches 61 to 67 provided in the electrical path 50 from remaining in the interrupted state unnecessarily.

[0071] <Other embodiments> The above-described embodiments may be modified as follows.

[0072] The interruption circuit 81 of the switch interruption device 80 may realize various functions at least in part by software, i.e., by processing executed on a computer, instead of by electronic circuits, which are hardware. Specifically, the control device 70 shown in FIG. 1 may realize the functions of the interruption circuit 81. The control device 70 executes programs stored in a non-transitory tangible storage medium serving as a storage unit provided therein. The programs include, for example, programs for the processing shown in FIG. 7, etc. Execution of the programs results in the execution of a method corresponding to the programs. The storage unit is, for example, a non-volatile memory. Note that the programs stored in the storage unit can be updated via a network, such as the Internet. Note that in this embodiment, the processing of steps S10 and S11 corresponds to a "calculation unit," and the processing of steps S12 and S14 corresponds to a "interruption unit."

[0073] If the shutoff unit (function of the shutoff circuit 81) that shuts off a pair of switches based on the total current of the pair of switches is implemented by computer software processing, the switch shutoff process becomes a discrete process, and there is a concern that the switch shutoff process may be delayed. In this regard, by combining the path disconnection circuit 91 described in the second embodiment, it is possible to shut off the inter-load switch according to the path voltage, thereby enabling immediate response to a ground fault or the like and enabling appropriate switch shutoff by identifying the location of the abnormality.

[0074] 7, a value set independently of the upper limit current when driving an electrical load connected between a pair of switches may be used. For example, in the interruption process executed by interruption circuit 81 that targets fifth and sixth switches 65, 66 as a pair of switches to be interrupted, a value equal to or greater than 0 may be used as threshold current Ith.

[0075] The configuration of the first power source 11 and the second power source 12 can be changed. For example, both the first power source 11 and the second power source 12 may be low-voltage batteries. Alternatively, both the first power source 11 and the second power source 12 may be low-voltage batteries, and a generator may be connected to one of the power sources.

[0076] Each of the switches 61 to 67 may be a normally closed switch, and may be configured to be turned off by a switch shutoff device 80 only when an overcurrent abnormality occurs.

[0077] The power supply system may be installed in a vehicle other than a vehicle, or may be installed in a moving object other than a vehicle. The power supply system may also be stationary.

[0078] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0079] The technical ideas extracted from the above-described embodiments will be described below. [Configuration 1] a first power source (11) and a second power source (12) connected via an electrical path (50); The present invention is applied to a power supply system including a plurality of switches (61 to 67) provided in the electrical path and connected in series with each other, a calculation unit that acquires currents flowing through a pair of switches that are two adjacent switches in the electrical path, and calculates a total current that is the sum of currents flowing to a midpoint of the pair of switches based on the currents; and a disconnecting unit that disconnects the pair of switches when the total current exceeds a threshold current. [Configuration 2] The present invention is applied to a power supply system in which a plurality of electric loads (31 to 34, 41, 42) are connected to the electric path, and one switch and the other switch of the pair of switches are provided on both sides of connection points of different electric loads among the electric loads, A plurality of combinations of the pair of switches are determined for each of the electric loads connected therebetween, the calculation unit calculates, for each combination of the pair of switches, the total current flowing to a midpoint of the pair of switches; The switch interruption device according to configuration 1, wherein the interruption unit interrupts the pair of switches when the total current exceeds the threshold current for each combination of the pair of switches. [Configuration 3] 3. The switch interruption device according to claim 2, wherein the threshold current is a current value greater than an upper limit current when driving the electrical load connected between the pair of switches. [Configuration 4] the plurality of electrical loads include a first redundant load (41) and a second redundant load (42), and each of the redundant loads is capable of realizing a specific function either as both redundant loads or as one of the redundant loads; The switch interruption device according to configuration 2 or 3, wherein the interruption unit is configured to consider two of the switches located in a position sandwiching only the first connection point between the first connection point to which the first redundant load is connected and the second connection point to which the second redundant load is connected as the pair of switches, and to consider two of the switches located in a position sandwiching only the second connection point as the pair of switches, and to interrupt the pair of switches when the total current exceeds the threshold current for each combination of the pair of switches. [Configuration 5] the plurality of electrical loads include a first electrical load and a second electrical load connected to the plurality of connection points in the electrical path; Among the plurality of switches, a switch provided between each connection point of the first electric load and the second electric load is an inter-load switch, The interrupter is a first interrupter (81), The switch interruption device according to any one of configurations 2 to 4, further comprising a second interruption unit (91) that acquires the voltage of the electrical path as a path voltage, and when the path voltage falls below a threshold voltage, interrupts the inter-load switch and separates the electrical path into the first power supply side and the second power supply side. [Configuration 6] the plurality of electrical loads include a first redundant load (41) and a second redundant load (42), and each of the redundant loads is capable of realizing a specific function either as both redundant loads or as one of the redundant loads; The switch interruption device according to configuration 5, wherein the inter-load switch is provided at a position in the electrical path between the first redundant load and the second redundant load. [Configuration 7] The switch interruption device according to configuration 5 or 6, further comprising a reset operation unit that, when the inter-load switch is cut off by the second interruption unit and the pair of switches are cut off by the first interruption unit, resets to a conductive state those switches among the plurality of switches that are targeted for interruption by the second interruption unit but are not targeted for interruption by the first interruption unit. [Configuration 8] The electrical path includes a plurality of parallel paths (51, 52) that are parallel to each other, the calculation unit calculates the total current by treating two adjacent switches as a pair of switches in each of the parallel paths; 8. The switch interruption device according to any one of configurations 1 to 7, wherein the interruption unit interrupts the pair of switches when the total current exceeds a threshold current. [Explanation of symbols]

[0080] 11...first power source, 12...second power source, 50...electrical path, 61-67...first to seventh switches, 80...switch breaker.

Claims

1. a first power source (11) and a second power source (12) connected via an electrical path (50); The present invention is applied to a power supply system including a plurality of switches (61 to 67) provided in the electrical path and connected in series with each other, a calculation unit that acquires currents flowing through a pair of switches that are two adjacent switches in the electrical path, and calculates a total current that is a sum of currents flowing to a midpoint of the pair of switches based on the currents; and a disconnecting unit that disconnects the pair of switches when the total current exceeds a threshold current.

2. The present invention is applied to a power supply system in which a plurality of electrical loads (31 to 34, 41, 42) are connected in the electrical path, and one switch and the other switch of the pair of switches are provided on both sides of a connection point of different electrical loads among the electrical loads, The pair of switches is determined in a plurality of combinations for each of the electric loads connected therebetween, the calculation unit calculates, for each combination of the pair of switches, the total current flowing to a midpoint of the pair of switches; The switch interruption device according to claim 1 , wherein the interruption unit interrupts the pair of switches when the total current exceeds the threshold current for each combination of the pair of switches.

3. 3. The switch interrupter according to claim 2, wherein the threshold current is a current value greater than an upper limit current when driving the electrical load connected between the pair of switches.

4. The plurality of electrical loads include a first redundant load (41) and a second redundant load (42), and each of the redundant loads can realize a specific function either as both redundant loads or as one redundant load; 3. The switch interruption device according to claim 2, wherein the interruption unit defines two switches located between a first connection point to which the first redundant load is connected and a second connection point to which the second redundant load is connected in the electrical path, as the pair of switches, and defines two switches located between which the second connection point is connected, as the pair of switches, and interrupts the pair of switches for each combination of the pair of switches when the total current exceeds the threshold current.

5. the plurality of electrical loads include a first electrical load and a second electrical load connected to the plurality of connection points in the electrical path; Among the plurality of switches, a switch provided between each connection point of the first electric load and the second electric load is an inter-load switch, The interrupting portion is a first interrupting portion (81), 3. The switch interruption device according to claim 2, further comprising: a second interruption unit (91) that acquires a voltage of the electrical path as a path voltage, and when the path voltage falls below a threshold voltage, interrupts the inter-load switch and separates the electrical path into the first power supply side and the second power supply side.

6. The plurality of electrical loads include a first redundant load (41) and a second redundant load (42), and each of the redundant loads can realize a specific function either as both redundant loads or as one redundant load; The switch interruption device according to claim 5 , wherein the inter-load switch is provided at a position in the electrical path between the first redundant load and the second redundant load.

7. 6. The switch interruption device according to claim 5, further comprising a reset operation unit that, when the inter-load switch is interrupted by the second interruption unit and the pair of switches are interrupted by the first interruption unit, resets to a conductive state those switches among the plurality of switches that are to be interrupted by the second interruption unit but are not to be interrupted by the first interruption unit.

8. The electrical path includes a plurality of parallel paths (51, 52) that are parallel to each other, the calculation unit calculates the total current by treating two adjacent switches as a pair of switches in each of the parallel paths; The switch interruption device according to any one of claims 1 to 7, wherein the interruption unit interrupts the pair of switches when the total current exceeds a threshold current.

9. a first power source (11) and a second power source (12) connected via an electrical path (50); A program applicable to a power supply system including a plurality of switches (61 to 67) provided in the electrical path and connected in series with each other, the program being executable by a computer (70), a calculation step of acquiring currents flowing through a pair of switches, which are two adjacent switches in the electrical path, and calculating a total current, which is the sum of currents flowing to a midpoint of the pair of switches, based on the currents; and a shut-off step of shutting off the pair of switches when the total current exceeds a threshold current.

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