In-vehicle system, in-vehicle power distribution device, and control method

Abstract

To provide an in-vehicle system and the like, capable of reducing electric power required for control when a vehicle is in a low current state.SOLUTION: An in-vehicle system comprises: an upstream route connected to a power supply device; downstream routes branching from the upstream route and connect to a load; an upstream in-vehicle device provided in the upstream route and including an upstream semiconductor fuse; and downstream in-vehicle devices provided in the downstream routes, respectively, and including a downstream semiconductor fuse. The upstream in-vehicle device comprises a first control unit for controlling turning on / off the upstream semiconductor fuse. The downstream in-vehicle devices each comprise a second control unit for controlling turning on / off the downstream semiconductor fuse. When a vehicle is in a low current state, the first control unit sets cutoff characteristics of the upstream semiconductor fuse to be lower than when the vehicle is in a normal current state. When the vehicle is in a low current state, the second control unit fixes the downstream semiconductor fuse to be on.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present technology relates to an in-vehicle system, an in-vehicle device, and a control method. [Background technology]

[0002] A vehicle is equipped with a power supply control device (see, for example, Patent Document 1) that controls power supply from a battery to a load. In the power supply control device described in Patent Document 1, a semiconductor switch is provided in a current path of a current flowing from the battery to the load, and the power supply from the battery to the load is controlled by switching the semiconductor switch on or off.

[0003] The semiconductor switch has a control end. For example, when the semiconductor switch is a FET (Field Effect Transistor), the control end is a gate. The resistance value between both ends of the semiconductor switch changes according to the voltage at the control end. By adjusting the voltage at the control end, the resistance value between both ends of the semiconductor switch is adjusted to a sufficiently small value, and the semiconductor switch is switched on. By adjusting the voltage at the control end, the resistance value between both ends of the semiconductor switch is adjusted to a sufficiently large value, and the semiconductor switch is switched off. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-143905 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a vehicle, which may be in either a normal current state or a low current state, is in a low current state, the power available for processing the vehicle's on-board systems is limited, and it is necessary to reduce the required power.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide an in-vehicle system etc. that can reduce the power required for control when the vehicle is in a low current state. [Means for solving the problem]

[0007] An in-vehicle system according to one embodiment of the present disclosure is an in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, wherein a state of the vehicle includes a normal current state in which the load consumes a normal current and a low current state in which the load consumes a current smaller than the normal current, and the system includes an upstream path connected to the power supply device, a downstream path branching from the upstream path and connected to the load, an upstream in-vehicle device including an upstream semiconductor fuse provided in the upstream path, and a downstream in-vehicle device including a downstream semiconductor fuse having a fuse function and a relay function, the upstream in-vehicle device includes a first control unit that controls the upstream semiconductor fuse to be turned on or off, and the downstream in-vehicle device includes a second control unit that controls the downstream semiconductor fuse to be turned on or off, and when the vehicle is in a low current state, the first control unit sets the interrupting characteristics of the upstream semiconductor fuse to lower characteristics compared to when the vehicle is in a normal current state, and when the vehicle is in a low current state, the second control unit stops the fuse function of the downstream semiconductor fuse.

[0008] A distribution train onboard device according to one embodiment of the present disclosure is a distribution train onboard device that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, the state of the vehicle including a normal current state in which the current consumption of the load is normal current, and a low current state in which the current consumption of the load is smaller than the normal current, and the device includes an upstream path connecting to the power supply device, a downstream path branching from the upstream path and connecting to the load, an upstream semiconductor fuse provided in the upstream path, downstream semiconductor fuses having a fuse function and a relay function provided in each of the downstream paths, and a control unit that controls the on / off of the upstream semiconductor fuse and the downstream semiconductor fuse, and when the vehicle is in a low current state, the control unit stops the fuse function of the downstream semiconductor fuse and sets the interruption characteristics of the upstream semiconductor fuse to lower characteristics compared to when the vehicle is in a normal current state.

[0009] A control method according to one embodiment of the present disclosure is a control method for an in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, wherein the state of the vehicle includes a normal current state in which the current consumption of the load is normal current, and a low current state in which the current consumption of the load is smaller than the normal current, and the in-vehicle system includes an upstream path connecting to the power supply device, a downstream path branching from the upstream path and connecting to the load, an upstream semiconductor fuse provided in the upstream path, and downstream semiconductor fuses having a fuse function and a relay function that are provided in each of the downstream paths, and when the state of the vehicle is in the low current state, the interruption characteristics of the upstream semiconductor fuse are set to lower characteristics compared to when the vehicle is in the normal current state, and the fuse function of the downstream semiconductor fuse is stopped. Effect of the Invention

[0010] In the in-vehicle system according to an embodiment of the present disclosure, when the vehicle is in a low current state, the power required for control can be reduced. [Brief description of the drawings]

[0011] [Figure 1]1 is a block diagram showing an example of the configuration of an in-vehicle system according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing a configuration example of a first microcomputer. [Diagram 3] FIG. 13 is an explanatory diagram showing a cutoff characteristic table. [Figure 4] FIG. 4 is an explanatory diagram showing a characteristic curve. [Diagram 5] FIG. 4 is a block diagram showing a configuration example of a second microcomputer. [Figure 6] 6 is a flowchart showing a processing procedure of a first microcomputer. [Figure 7] 10 is a flowchart showing a processing procedure of a second microcomputer. [Figure 8] FIG. 11 is a block diagram showing an example of the configuration of an in-vehicle system according to a second embodiment. [Figure 9] FIG. 11 is a block diagram showing an example of the configuration of a microcomputer according to a second embodiment. [Figure 10] 10 is a flowchart showing a processing procedure of a microcomputer according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. At least a part of the embodiments described below may be arbitrarily combined.

[0013] (1) An in-vehicle system according to one embodiment of the present disclosure is an in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, wherein a state of the vehicle includes a normal current state in which the load consumes a normal current and a low current state in which the load consumes a current smaller than the normal current, and the system includes an upstream path connecting to the power supply device, a downstream path branching from the upstream path and connecting to the load, an upstream in-vehicle device including an upstream semiconductor fuse provided in the upstream path, and a downstream in-vehicle device including a downstream semiconductor fuse having a fuse function and a relay function, the upstream in-vehicle device includes a first control unit that controls the upstream semiconductor fuse to be turned on or off, the downstream in-vehicle device includes a second control unit that controls the downstream semiconductor fuse to be turned on or off, when the vehicle is in a low current state, the first control unit sets an interruption characteristic of the upstream semiconductor fuse to a lower characteristic compared to when the vehicle is in a normal current state, and the second control unit stops the fuse function of the downstream semiconductor fuse when the vehicle is in the low current state.

[0014] In this embodiment, the power supplied from the power supply device is supplied to a plurality of loads via an upstream path and a plurality of downstream paths branching from the upstream path. For example, one load is connected to each downstream path. An in-vehicle device is provided on each of the upstream path and each downstream path. That is, the in-vehicle device operates as a power supply control device. The in-vehicle device includes an upstream in-vehicle device provided on the upstream path and a downstream in-vehicle device provided on the downstream path. The upstream in-vehicle device controls power supply to the downstream path by an upstream semiconductor fuse and a first control unit that controls the upstream semiconductor fuse. Each downstream in-vehicle device controls power supply to the load by a downstream semiconductor fuse and a second control unit that controls the downstream semiconductor fuse. The downstream in-vehicle device may include a mechanical switch, and the second control unit may control power supply to the load by controlling the mechanical switch. When the vehicle is started, a normal current state is established in which a normal current flows from the power supply device to the load, and when the vehicle is stopped, a low current state is established in which a low current (dark current) flows from the power supply device to the load. The current value of the low current is lower than the current value of the normal current, for example, 10 mA to 100 mA. The current value of the low current is a low value, for example, about one hundredth or one thousandth of the current value of the normal current. When the vehicle is stopped, the current supplied to the load of the vehicle is reduced to reduce the consumption of the power supply device. For example, the vehicle starts when the power switch or the ignition switch is on, and stops when it is off. When the vehicle is in a low current state, the first control unit sets the interruption characteristics of the upstream semiconductor fuse to lower characteristics compared to when the vehicle is in a normal current state. In addition, the second control unit of each downstream in-vehicle device stops (disables) the fuse function of the downstream semiconductor fuse and continues to operate (enable) the relay function. As a result, when in a low current state, the second control unit does not need to switch on or off the fuse function of the downstream semiconductor fuse, and it is possible to reduce the power required for processing by the second control unit by reducing the drive frequency of the second control unit or fixing the downstream semiconductor fuse on to stop the fuse function of the downstream semiconductor fuse by the second control unit.In addition, by lowering the value of the interruption characteristic of the upstream semiconductor fuse, it is possible to determine an overcurrent based on the current value in a low current state, and it is possible to protect the downstream path with high accuracy. Note that the downstream semiconductor fuse may not have a relay function, and a separate relay may be provided in the downstream path. In this case, when the vehicle is in a low current state, the downstream semiconductor fuse is fixed to ON, and the fuse function is stopped while current is still flowing.

[0015] (2) In an in-vehicle system according to one aspect of the present disclosure, the first control unit sets an interruption characteristic of the upstream semiconductor fuse based on a combination of the loads connected to the downstream path.

[0016] In this embodiment, the first control unit stores a table in which cutoff characteristics are set for combinations of loads connected to the downstream path, and sets the cutoff characteristics of the upstream semiconductor fuse based on the table. The first control unit may set the cutoff characteristics of the upstream semiconductor fuse based on a combination of loads that need to be started when the vehicle is in a low current state, among the loads connected to the downstream path. This makes it possible to accurately protect the downstream path while supplying power to loads that require power in a low current state.

[0017] (3) In an in-vehicle system according to one embodiment of the present disclosure, the first control unit sets the interruption characteristics of the upstream semiconductor fuse so that the time it takes to turn off the upstream semiconductor fuse for a current value of an overcurrent is shorter than the time it takes to turn off the downstream semiconductor fuse for a current value of an overcurrent in the interruption characteristics of the downstream semiconductor fuse when a fuse function is enabled, and so that the rated current value is higher than the sum of the current values ​​in the downstream path when the vehicle is in a low current state.

[0018] In this embodiment, the interruption characteristics of the upstream semiconductor fuse are set so that the time until the upstream semiconductor fuse is turned off for a current value of an overcurrent is shorter than that of the downstream semiconductor fuse having the shortest time until it is turned off for a current value of an overcurrent in the interruption characteristics when the fuse function is active, among the downstream semiconductor fuses turned on by the relay function. Also, the interruption characteristics of the upstream semiconductor fuse are set so that the rated current value is higher than the total of the current values ​​(current values ​​in the downstream path) flowing through the downstream semiconductor fuses turned on by the relay function. That is, when there is one downstream semiconductor fuse turned on by the relay function, the interruption characteristics of the upstream semiconductor fuse are set to a value lower than the interruption characteristics of the downstream semiconductor fuse. This makes it possible to protect the downstream path with higher accuracy.

[0019] (4) In an in-vehicle system according to one embodiment of the present disclosure, the first control unit acquires a current value of the upstream path, and when the acquired current of the upstream path flows for a predetermined period of time or longer in a state where the current exceeds a rated current value in the interruption characteristics of the upstream semiconductor fuse, the first control unit switches off the upstream semiconductor fuse.

[0020] In this embodiment, when a current exceeding a rated current value flows in the upstream path for a predetermined time, the upstream semiconductor fuse is switched off to protect the downstream path. The first control unit switches off the upstream semiconductor fuse in a shorter time as the current value flowing in the upstream path increases. The interruption characteristics are characteristics of the upstream semiconductor fuse including a rated current value for interrupting a current and a time required to interrupt the current for a current exceeding the rated current value (overcurrent). When the interruption characteristics of the upstream semiconductor fuse are high, the rated current value is high and the time required to interrupt for an overcurrent is long. When the interruption characteristics are lowered, the rated current value is low and the time required to interrupt for an overcurrent is short. That is, the product of the current value and the time required to interrupt (current integrated value) rises and falls depending on the level of the interruption characteristics. The interruption characteristics of the upstream semiconductor fuse are set, for example, to be lower than the smoke generation characteristics of the downstream path or the sum of the device characteristics of the load connected to the downstream path. In this way, when an overcurrent flows, the possibility of smoke generation in the downstream path or failure of the load can be reduced by turning off the upstream semiconductor fuse. When the value of the current flowing through the upstream path is equal to or less than the rated current value, the first control unit does not switch the upstream semiconductor fuse 32 off.

[0021] (5) In the in-vehicle system according to one embodiment of the present disclosure, at least a portion of the downstream semiconductor fuses are P-channel FETs.

[0022] In this aspect, when the vehicle is in a low current state, the downstream semiconductor fuse can be fixed on without applying a voltage to the downstream semiconductor fuse, which eliminates the need for power for processing or voltage application when the second control unit stops the fuse function of the downstream semiconductor fuse, thereby making it possible to reduce the power required for processing by the second control unit.

[0023] (6) A distribution train onboard device according to one embodiment of the present disclosure is a distribution train onboard device that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, wherein the states of the vehicle include a normal current state in which the loads consume a normal current and a low current state in which the loads consume a current smaller than the normal current, and the device comprises an upstream path connecting to the power supply device, a downstream path branching from the upstream path and connecting to the loads, an upstream semiconductor fuse provided in the upstream path, downstream semiconductor fuses having a fuse function and a relay function provided in each of the downstream paths, and a control unit that controls the upstream semiconductor fuse and the downstream semiconductor fuse to be turned on or off, wherein when the vehicle is in a low current state, the control unit stops the fuse function of the downstream semiconductor fuse and sets the interrupting characteristics of the upstream semiconductor fuse to lower characteristics compared to when the vehicle is in a normal current state.

[0024] In this aspect, power supplied from a power supply device is supplied to a plurality of loads via an on-board device. That is, the on-board device operates as a power supply control device. The on-board device includes an upstream path connected to the power supply device, and downstream paths branching from the upstream path and connected to each load. A control unit of the on-board device controls the on / off of an upstream semiconductor fuse provided in the upstream path and a downstream semiconductor fuse provided in each downstream path. When the vehicle is in a low current state, the control unit stops the fuse function of the downstream semiconductor fuse and sets the interruption characteristic of the upstream semiconductor fuse low, thereby making it possible to accurately protect the downstream path while reducing the power required for processing.

[0025] (7) In a distribution train onboard device according to one embodiment of the present disclosure, the control unit sets the interruption characteristics of the upstream semiconductor fuse based on a combination of the loads connected to the downstream path.

[0026] In this embodiment, the control unit stores, for example, a table in which cutoff characteristics to be set for combinations of loads connected to the downstream path are stored, and sets the cutoff characteristics of the upstream semiconductor fuse based on the table. The first control unit may set the cutoff characteristics of the upstream semiconductor fuse based on a combination of loads that need to be started when the vehicle is in a low current state, among the loads connected to the downstream path. This makes it possible to accurately protect the downstream path while supplying power to loads that require power in a low current state.

[0027] (8) In one embodiment of the onboard device of the present disclosure, the control unit acquires a current value of the upstream path, and when the acquired current of the upstream path flows for a predetermined period of time or longer in a state where the current exceeds a rated current value in the interruption characteristics of the upstream semiconductor fuse, the control unit switches off the upstream semiconductor fuse.

[0028] In this aspect, when a current exceeding a rated current value flows in the upstream path for a predetermined period of time, the downstream path can be protected by switching off the upstream semiconductor fuse.

[0029] (9) In one embodiment of the onboard device of the present disclosure, at least a portion of the downstream semiconductor fuses are P-channel type FETs.

[0030] In this embodiment, when the vehicle is in a low current state, the downstream semiconductor fuse can be fixed on without applying voltage to the downstream semiconductor fuse, thereby making it possible to reduce the power required for processing by the control unit when stopping the fuse function of the downstream semiconductor fuse.

[0031] (10) A control method according to one embodiment of the present disclosure is a control method for an in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, wherein the state of the vehicle includes a normal current state in which the load consumes a normal current, and a low current state in which the load consumes a current smaller than the normal current, and the in-vehicle system includes an upstream path connecting to the power supply device, a downstream path branching from the upstream path and connecting to the load, an upstream semiconductor fuse provided in the upstream path, and downstream semiconductor fuses having a fuse function and a relay function that are provided in each of the downstream paths, and when the vehicle is in a low current state, the interruption characteristics of the upstream semiconductor fuse are set to lower characteristics compared to when the vehicle is in a normal current state, and the fuse function of the downstream semiconductor fuse is stopped.

[0032] In this aspect, it is possible to accurately protect the downstream path while reducing the power required for processing in the in-vehicle system.

[0033] [Details of the embodiment of the present disclosure] Specific examples of power supply control devices according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0034] (Embodiment 1) FIG. 1 is a block diagram showing a configuration example of an in-vehicle system according to a first embodiment. The in-vehicle system S is provided in a vehicle C, and includes a power supply device 1, an electric circuit 2, an upstream in-vehicle device 3, a plurality of downstream in-vehicle devices 4, and a plurality of loads 5. The electric circuit 2 includes an upstream electric circuit (upstream path) 21 that connects to the power supply device, and a downstream electric circuit (downstream path) 22 that branches from the upstream electric circuit and connects to the load. The power supply device 1 is a power supply that outputs a direct current, such as a battery, such as a lead storage battery, a hydrogen battery, or a secondary battery, or an alternator. The upstream in-vehicle device 3 is connected to a positive electrode of the power supply device 1 and a plurality of downstream in-vehicle devices 4. Each downstream in-vehicle device 4 is connected to the upstream in-vehicle device 3 and one end of the load 5. The upstream in-vehicle device 3 and the downstream in-vehicle device 4 are, for example, ECUs (Electronic Control Units) that control the current from the power supply device 1 to the load 5. The negative electrode of the power supply device 1 and the other end of the load 5 are grounded. Each downstream path 22 is connected to, for example, one load 5. In this embodiment, a case will be described in which a current flowing from the upstream path 21 branches into three downstream paths 22 and is supplied to three loads 5. Note that the number of downstream paths 22 and the number of loads 5 are not limited to three.

[0035] When the vehicle starts, the power supply device 1 supplies electric power of a current (normal current) for operating the load 5, and the vehicle is in a normal current state. When the vehicle stops, the power supply device 1 supplies electric power of a low current whose current value is lower than the normal current, and the vehicle is in a low current state. The load 5 to which low current electric power is supplied is, for example, a load of a device that needs to operate even when the vehicle is stopped, such as an interior light or a security device.

[0036] The upstream vehicle-mounted device 3 is provided on the upstream path 21, and transmits power received from the power supply device 1 to the downstream vehicle-mounted device 4. The upstream vehicle-mounted device 3 includes a first microcomputer (microcomputer) 31, an upstream semiconductor fuse 32, a drive circuit 33, a resistor 34, and a current detection circuit 35. The first microcomputer 31 will be described in detail later.

[0037] The upstream semiconductor fuse 32 is, for example, an N-channel type FET (Field Effect Transistor), and is provided in the upstream path 21 such that the drain is disposed upstream of the source. That is, the drain of the upstream semiconductor fuse 32 is connected to the power supply device 1. Note that the upstream semiconductor fuse 32 may be a P-channel type FET, transistor, thyristor, or an IPD (Intelligent Power Device). When a voltage is applied to the gate of the upstream semiconductor fuse 32, the upstream semiconductor fuse 32 is turned on, and a current can flow. When a voltage is not applied to the gate of the upstream semiconductor fuse 32, the upstream semiconductor fuse 32 is turned off, and no current flows.

[0038] The drive circuit 33 switches the upstream semiconductor fuse 32 on or off by controlling the voltage applied to the gate of the upstream semiconductor fuse 32. The drive circuit 33 is, for example, an electronic device such as an FPGA, an ASIC, or an ASSP. The drive circuit 33 may be a software processing unit such as a microcomputer or a DSP. When a signal (Hi voltage) indicating an instruction to turn on the upstream semiconductor fuse 32 is input from the first microcomputer 31, the drive circuit 33 applies a voltage to the gate of the upstream semiconductor fuse 32 to turn on the upstream semiconductor fuse 32. When a signal (Low voltage) indicating an instruction to turn off the upstream semiconductor fuse 32 is input from the first microcomputer 31, the drive circuit 33 does not apply a voltage to the gate of the upstream semiconductor fuse 32 to turn off the upstream semiconductor fuse 32.

[0039] One end of the resistor 34 is connected to the source of the upstream semiconductor fuse 32. The other end of the resistor 34 is connected to the downstream in-vehicle device 4. The resistor 34 may be provided upstream of the upstream semiconductor fuse 32.

[0040] The current detection circuit 35 detects the current value (upstream current value) of the current flowing through the resistor 34. The current detection circuit 35 outputs, to the first microcomputer 31, analog upstream current information indicating the detected upstream current value.

[0041] The downstream in-vehicle device 4 is provided on the downstream path 22, and transmits the power received from the upstream in-vehicle device 3 to the load 5. The downstream in-vehicle devices 4 included in the in-vehicle system S have the same configuration. Therefore, the following will explain one downstream in-vehicle device 4. The downstream in-vehicle device 4 includes a second microcomputer 41, a downstream semiconductor fuse 42, a drive circuit 43, a resistor 44, and a current detection circuit 45. The second microcomputer 41 will be described in detail later.

[0042] The downstream semiconductor fuse 42 is, for example, a P-channel type FET, and is provided in the downstream path 22 such that the source is disposed upstream of the drain. That is, the source of the downstream semiconductor fuse 42 is connected to the upstream in-vehicle device 3. Note that the downstream semiconductor fuse 42 may be an F-channel type FET, transistor, thyristor, IPD, or the like. Also, a mechanical switch may be provided instead of the downstream semiconductor fuse 42. When a voltage is applied to the gate of the downstream semiconductor fuse 42, the downstream semiconductor fuse 42 is turned off and no current flows. When a voltage is not applied to the gate of the downstream semiconductor fuse 42, the downstream semiconductor fuse 42 is turned on and current can flow.

[0043] The drive circuit 43 switches the downstream semiconductor fuse 42 on or off by controlling the voltage applied to the gate of the downstream semiconductor fuse 42. The drive circuit 43 is, for example, an electronic device such as an FPGA, an ASIC, or an ASSP. The drive circuit 43 may be a software processing unit such as a microcomputer or a DSP. When a signal (Low voltage) indicating an instruction to turn on the downstream semiconductor fuse 42 is input from the second microcomputer 41, or when no signal is output, the drive circuit 43 applies a voltage to the gate of the downstream semiconductor fuse 42 to turn on the downstream semiconductor fuse 42. When a signal (Hi voltage) indicating an instruction to turn off the downstream semiconductor fuse 42 is input from the second microcomputer 41, the drive circuit 43 applies a voltage to the gate of the downstream semiconductor fuse 42 to turn off the downstream semiconductor fuse 42.

[0044] One end of the resistor 44 is connected to the drain of the downstream semiconductor fuse 42. The other end of the resistor 44 is connected to the load 5. The resistor 44 may be provided upstream of the downstream semiconductor fuse 42. A fusing element (mechanical fuse) may be provided between the resistor 44 and the load 5.

[0045] The current detection circuit 45 detects the current value (downstream current value) of the current flowing through the resistor 44. The current detection circuit 45 outputs, to the second microcomputer 41, analog downstream current information indicating the detected downstream current value.

[0046] 2 is a block diagram showing an example of the configuration of the first microcomputer 31. The first microcomputer 31 operates as a first control unit capable of determining the state of the vehicle C and controlling the upstream semiconductor fuse 32. The first microcomputer 31 includes an input unit 310, an input unit 311, an A / D conversion unit 312, an output unit 313, a storage unit 314, and a processing unit 315. The input unit 310, the A / D conversion unit 312, the output unit 313, the storage unit 314, and the processing unit 315 are connected to an internal bus 316. The A / D conversion unit 312 is connected to the input unit 311.

[0047] An identification signal for identifying the type of the load 5 connected to the downstream path 22 is input to the input unit 310. The identification signal input to the input unit 310 is, for example, a signal output by the load 5, but may also be a signal output by another in-vehicle device capable of determining the type of the load 5 connected to the downstream path 22.

[0048] The input unit 311 receives upstream current information (upstream current value) from the current detection circuit 35. When the input unit 311 receives the upstream current information, the input unit 311 outputs the input analog upstream current information to the A / D conversion unit 312. The processing unit 315 acquires, from the A / D conversion unit 312, the digital upstream current information converted by the A / D conversion unit 312.

[0049] The output unit 313 outputs a Hi voltage or a Low voltage to the drive circuit 33. The output unit 313 switches the voltage output to the drive circuit 33 between a Hi voltage and a Low voltage in accordance with an instruction from the processing unit 315. The drive circuit 33 switches the upstream semiconductor fuse 32 on or off depending on the voltage input from the output unit 313.

[0050] The storage unit 314 is a non-volatile memory. A computer program P1 and a cutoff characteristic table T are stored in the storage unit 314. The processing unit 315 has a processing element that executes processing, for example, a CPU (Central Processing Unit). The processing element of the processing unit 315 executes the computer program P1 to execute processing for determining the state of the vehicle C and processing for controlling the upstream semiconductor fuse 32. The computer program P1 is used to cause the processing element (computer) of the processing unit 315 to execute processing.

[0051] The computer program P1 may be stored in a storage medium E so that the processing element of the processing unit 315 can read it. In this case, the computer program P1 read from the storage medium E by a reading device (not shown) is stored in the storage unit 314. The storage medium E is an optical disk, a flexible disk, a magnetic disk, a magneto-optical disk, a semiconductor memory, or the like. The optical disk is a CD (Compact Disc)-ROM (Read Only Memory), a DVD (Digital Versatile Disc)-ROM, or a BD (Blu-ray (registered trademark) Disc). The magnetic disk is, for example, a hard disk. The computer program P1 may be downloaded from an external device (not shown) connected to a communication network (not shown), and the downloaded computer program P1 may be stored in the storage unit 314.

[0052] Furthermore, the number of processing elements included in processing unit 315 is not limited to 1, and may be 2 or more. When processing unit 315 has multiple processing elements, the multiple processing elements may cooperate to execute processing.

[0053] FIG. 3 is an explanatory diagram showing a cutoff characteristic table T. FIG. 4 is an explanatory diagram showing a characteristic curve. The management items of the cutoff characteristic table T include, for example, a connected load field and a characteristic curve field. The connected load field stores a combination of types of loads 5 connected to the downstream path 22. In this embodiment, a form in which the types of loads 5 include four types, A, B, C, and D, will be described. The type of load 5 may correspond to the type of equipment, such as an interior light, to which the load 5 is provided. In addition, the example shown in FIG. 3 shows a form in which different types of loads 5 are connected to all three downstream paths 22, but this is not limited to this. The load 5 may be connected only to some of the downstream paths 22, or the same type of load 5 may be connected to multiple downstream paths 22.

[0054] The characteristic curve field stores a characteristic curve indicating the interruption characteristics of the upstream semiconductor fuse 32 selected for a combination of types of loads 5 connected to the downstream path 22 in a low current state. In this embodiment, the characteristic curves include four types: W, X, Y, and Z. The characteristic curves stored in the characteristic curve field are stored, for example, in a data format of a secondary array. The processing unit 315 sets the interruption characteristics by selecting a characteristic curve stored in the interruption characteristics table T based on the combination of types of loads 5.

[0055] The interruption characteristics are characteristics of the upstream semiconductor fuse 32, including the current value at which the processing unit 315 turns off the upstream semiconductor fuse 32 and interrupts the current, and the current flow time until the current is interrupted for a current that exceeds the rated current value (overcurrent). When the interruption characteristics of the upstream semiconductor fuse are high, the rated current value is high and the current flow time until the current is interrupted for an overcurrent is long. When the interruption characteristics are lowered, the rated current value is lower and the current flow time until the current is interrupted for an overcurrent is shortened. In other words, the product of the current value and the current flow time until interruption (integrated current value) rises or falls depending on the level of the interruption characteristics. The processing unit 315 determines whether the upstream current value is the minimum current value defined in the characteristic curve. When the current flow time exceeds a predetermined time while the current is equal to or greater than the rated current value, the upstream semiconductor fuse 32 is switched off. The rated current value indicates the maximum current value at which the upstream semiconductor fuse 32 is not turned off even if a current flows for a long time. The rated current value increases or decreases depending on the level of the interruption characteristics.

[0056] The characteristic curve is a curve showing the interruption characteristic of the upstream semiconductor fuse 32, i.e., the energization time until the processing unit 315 switches off the upstream semiconductor fuse 32 relative to the current value flowing through the upstream path 21. The graph shown in Fig. 4 shows the characteristic curve of the upstream semiconductor fuse 32 in a normal current state and a low current state, with the vertical axis showing the current value flowing through the upstream path 21 (upstream current value) and the horizontal axis showing the energization time.

[0057] 4, in the low current state, the processing unit 315 sets the cutoff characteristic of the upstream semiconductor fuse 32 to a lower characteristic than the cutoff characteristic (normal characteristic) in the normal current state. Note that the cutoff characteristic of each of the upstream semiconductor fuses 32 in the low current state is, for example, a characteristic offset so as to be lower than the sum of the device characteristics of each of the loads 5 connected to the downstream path 22 and supplied with power by the relay function of the downstream semiconductor fuse 42. In other words, the cutoff characteristic of the upstream semiconductor fuse 32 in the low current state is set so that the time until the upstream semiconductor fuse 32 is turned off for the current value of the overcurrent is shorter than the downstream semiconductor fuse 42 that has the shortest time until it is turned off for the current value of the overcurrent in the cutoff characteristic when the fuse function is active, among the downstream semiconductor fuses 42 that are turned on by the relay function.

[0058] In this embodiment, the power consumed by the load 5 in a low current state is greatest for types A, B, C, and D in that order. In this case, the characteristic curves showing the interruption characteristics are greatest for types W, X, Y, and Z in that order. That is, the greater the power consumption of the load 5 connected to the downstream path 22, the higher the value set by the processing unit 315 for the interruption characteristics of the upstream semiconductor fuse 32. That is, the interruption characteristics of the upstream semiconductor fuse 32 are set so that the rated current value is higher than the sum of the current value (current value in the downstream path) flowing through the downstream semiconductor fuse 42 that is turned on by the relay function and the load 5 connected to the downstream semiconductor fuse 42.

[0059] In this embodiment, the processing unit 315 sets the interruption characteristics of the upstream semiconductor fuse 32 based on the interruption characteristics table T in which a characteristic curve selected for a combination of types of the loads 5 connected to the downstream path 22 is stored, but is not limited to this. The storage unit 314 stores a table in which device characteristics for each type of load 5 are stored, and the processing unit 315 may set the interruption characteristics of the upstream semiconductor fuse 32 by shifting (reducing) the sum of the device characteristics of the loads 5 connected to the downstream path 22 downward using an offset value based on the table. The offset value may be a predetermined coefficient that is multiplied by the sum of the device characteristics of the loads 5 and is less than 1, for example, 0.8. The processing unit 315 may also set the interruption characteristics of the upstream semiconductor fuse 32 by shifting the sum of the smoke generation characteristics of the downstream path 22 using an offset value.

[0060] 5 is a block diagram showing an example of the configuration of the second microcomputer 41. The second microcomputer 41 operates as a second control unit capable of determining the state of the vehicle C and controlling the fuse function and relay function of the downstream semiconductor fuse 42. The second microcomputer 41 includes an input unit 411, an A / D conversion unit 412, an output unit 413, a storage unit 414, and a processing unit 415. The input unit 410, the A / D conversion unit 412, the output unit 413, the storage unit 414, and the processing unit 415 are connected to an internal bus 416. The A / D conversion unit 412 is connected to the input unit 411.

[0061] The input unit 411 receives downstream current information from the current detection circuit 45. When the input unit receives the downstream current information, the input unit outputs the input analog downstream current information to the A / D conversion unit 412. The processing unit 415 acquires, from the A / D conversion unit 412, the digital downstream current information converted by the A / D conversion unit 412.

[0062] The output unit 413 outputs a Hi voltage or a Low voltage to the drive circuit 43. The output unit 413 switches the voltage to be output to the drive circuit 43 between a Hi voltage and a Low voltage in accordance with an instruction from the processing unit 415. The drive circuit 43 switches the downstream semiconductor fuse 42 on or off depending on the voltage input from the output unit 413.

[0063] The storage unit 414 is a non-volatile memory. The storage unit 414 stores a computer program P. The processing unit 415 has a processing element, for example, a CPU, that executes processing. The processing element of the processing unit 415 executes the computer program P to execute a process of determining the state of the vehicle C and a process of controlling the stop (disable) or continued operation (enable) of the fuse function and relay function of the downstream semiconductor fuse 42. The computer program P is used to cause the processing element (computer) of the processing unit 415 to execute processing. When the fuse function continues to operate (when enabled), the processing unit 415 turns off the downstream semiconductor fuse 42 when the current value flowing through the downstream semiconductor fuse 42 exceeds the rated current value of the downstream semiconductor fuse 42. Also, when the relay function continues to operate (when enabled), the processing unit 415 switches the downstream semiconductor fuse 42 on or off based on the necessity of power supply to the load 5 connected to the downstream semiconductor fuse 42.

[0064] The computer program P may be stored in a storage medium E so as to be readable by a processing element of the processing unit 415. In this case, the computer program P read from the storage medium E by a reading device (not shown) is stored in the storage unit 414. The storage medium E is an optical disk, a flexible disk, a magnetic disk, a magneto-optical disk, a semiconductor memory, or the like. The optical disk is a CD-ROM, a DVD-ROM, a BD, or the like. The magnetic disk is, for example, a hard disk. The computer program P may be downloaded from an external device (not shown) connected to a communication network (not shown), and the downloaded computer program P may be stored in the storage unit 414.

[0065] FIG. 6 is a flowchart showing a processing procedure of the first microcomputer 31. In the initial state, the upstream semiconductor fuse 32 is turned on by the first microcomputer 31. The processing unit 315 of the first microcomputer 31 acquires an upstream current value from the current detection circuit 35 (S1). The processing unit 315 judges whether the vehicle C is in a normal current state (low current state) based on the acquired upstream current value (S2). In S2, if the acquired upstream current value is equal to or greater than a predetermined threshold, the processing unit 315 judges that the vehicle C is in a normal current state, and if the acquired upstream current value is less than the predetermined threshold, the processing unit 315 judges that the vehicle C is in a low current state. If the vehicle C is in a normal current state (S2: YES), the processing unit 315 sets the interruption characteristic of the upstream semiconductor fuse 32 to a normal characteristic (S3) and returns the processing to S1. If the vehicle C is in a low current state (S2: NO), the processing unit 315 acquires a load identification signal input to the input unit 310 (S4). The processing unit 315 reads out the interruption characteristic table T from the storage unit 314 (S5), and sets the interruption characteristic for controlling the upstream semiconductor fuse 32 based on the load identification signal and the interruption characteristic table (S6).

[0066] The processing unit 315 acquires the upstream current value from the current detection circuit 35 (S7). The processing unit 315 determines whether or not to interrupt the current in the upstream path 21 based on the interruption characteristics and the upstream current value (S8). In S8, when the upstream current value exceeds the rated current value, the processing unit 315 interrupts the current when the current flow time reaches or exceeds a predetermined time corresponding to the current value in the characteristic curve. Alternatively, the processing unit 315 may determine to interrupt the current when the current integration value reaches or exceeds a predetermined value. Note that, when the upstream current value becomes equal to or less than the rated current value before the predetermined time has elapsed, the processing unit 315 determines not to interrupt the current. Also, when the upstream current value exceeds the maximum current value defined in the characteristic curve, the processing unit 315 determines to interrupt the current instantly. When the current in the upstream path 21 is interrupted (S8: YES), the processing unit 315 causes the driving circuit 33 to turn off the upstream semiconductor fuse 32 (S9) and ends the process. If the current in the upstream path 21 is not to be interrupted (S8: NO), the processing unit 315 returns the process to S1.

[0067] 7 is a flowchart showing the processing procedure of the second microcomputer 41. The processing unit 415 of the second microcomputer acquires a downstream current value from the current detection circuit 45 (S11). The processing unit 415 determines whether the vehicle C is in a normal current state based on the downstream current value (S12). If the vehicle C is in a normal current state (S12: YES), the processing unit 415 returns the processing to S11. If the vehicle C is in a low current state (S12: NO), the processing unit 415 stops the fuse function of the downstream semiconductor fuse 42 and continues to operate the relay function (S13), and ends the processing.

[0068] According to the above configuration and processing, when the vehicle C is in a dark current state, the second microcomputer 41 does not need to control the fuse function of the downstream semiconductor fuse 42. This makes it possible to protect the downstream path 22 while reducing the power required for processing.

[0069] (Embodiment 2) In the first embodiment, the electric circuit 2 branches from the upstream path 21 to the downstream path 22 between a plurality of devices, but may branch within one device. The following describes the differences between the second embodiment and the first embodiment. Except for the configuration described below, the other configurations are common to the first embodiment. For this reason, the components common to the first embodiment are given the same reference symbols as the first embodiment, and the description thereof will be omitted.

[0070] FIG. 8 is a block diagram showing a configuration example of an on-vehicle system S according to the second embodiment. The on-vehicle system S according to the second embodiment includes a power supply device 1, an electric circuit 2, a distribution train on-board device 6, and a plurality of loads 5. The distribution train on-board device 6 is connected to the positive electrode of the power supply device 1 and one end of the plurality of loads 5. The distribution train on-board device 6 is, for example, an ECU that controls the current from the power supply device 1 to the load 5. The distribution train on-board device 6 includes an electric circuit 2 through which a current flows from the power supply device 1 to the load 5. The electric circuit 2 includes an upstream electric circuit (upstream path) 21 that connects to the power supply device, and a downstream electric circuit (downstream path) 22 that branches off from the upstream path 21 and connects to the load. In this embodiment, the downstream path 22 branches off into three paths.

[0071] The distribution train onboard device 6 includes a microcomputer 61, an upstream semiconductor fuse 62, an upstream drive circuit 63, a resistor 64, a current detection circuit 65, a plurality of downstream semiconductor fuses 66, and a plurality of downstream drive circuits 67. The microcomputer 61 will be described in detail later.

[0072] The upstream semiconductor fuse 62 is, for example, an N-channel type FET, and is provided in the upstream path 21 such that the drain is disposed upstream of the source. That is, the drain of the upstream semiconductor fuse 62 is connected to the power supply device 1. Note that the upstream semiconductor fuse 62 may be a P-channel type FET, transistor, thyristor, IPD, or the like. When a voltage is applied to the gate of the upstream semiconductor fuse 62, the upstream semiconductor fuse 62 is turned on and a current can flow. When a voltage is not applied to the gate of the upstream semiconductor fuse 62, the upstream semiconductor fuse 62 is turned off and no current flows.

[0073] The upstream driving circuit 63 switches the upstream semiconductor fuse 62 on or off by controlling the voltage applied to the gate of the upstream semiconductor fuse 62. The upstream driving circuit 63 is, for example, an electronic device such as an FPGA, an ASIC, or an ASSP. The upstream driving circuit 63 may be a software processing unit such as a microcomputer or a DSP. When a signal (Hi voltage) indicating an instruction to turn on the upstream semiconductor fuse 62 is input from the microcomputer 61, the upstream driving circuit 63 applies a voltage to the gate of the upstream semiconductor fuse 62 to turn on the upstream semiconductor fuse 62. When a signal (Low voltage) indicating an instruction to turn off the upstream semiconductor fuse 62 is input from the microcomputer 61, the upstream driving circuit 63 does not apply a voltage to the gate of the upstream semiconductor fuse 62 to turn off the upstream semiconductor fuse 62.

[0074] One end of the resistor 64 is connected to the source of the upstream semiconductor fuse 62. The other end of the resistor 64 is connected to the downstream semiconductor fuse 66. The resistor 64 may be provided upstream of the upstream semiconductor fuse 62.

[0075] The current detection circuit 65 detects the current value (upstream current value) of the current flowing through the resistor 64. The current detection circuit 65 outputs to the microcomputer 61 analog current information indicating the detected upstream current value.

[0076] The downstream semiconductor fuse 66 is provided in each downstream path 22. The downstream semiconductor fuse 66 is, for example, a P-channel type FET, and is provided in the downstream path 22 such that the source is disposed upstream of the drain. That is, the source of the downstream semiconductor fuse 66 is connected to the resistor 64. Note that the downstream semiconductor fuse 66 may be an F-channel type FET, transistor, thyristor, IPD, or the like. Also, a mechanical switch may be provided instead of the downstream semiconductor fuse 66. When a voltage is applied to the gate of the downstream semiconductor fuse 66, the downstream semiconductor fuse 66 is turned off and no current flows. When a voltage is not applied to the gate of the downstream semiconductor fuse 66, the downstream semiconductor fuse 66 is turned on and a current can flow.

[0077] The downstream drive circuit 67 is provided for each downstream semiconductor fuse 66. The downstream drive circuit 67 switches the downstream semiconductor fuse 66 on or off by controlling a voltage applied to the gate of the downstream semiconductor fuse 66. The downstream drive circuit 67 is, for example, an electronic device such as an FPGA, an ASIC, or an ASSP. The downstream drive circuit 67 may be a software processing unit such as a microcomputer or a DSP. When a signal (Low voltage) indicating an instruction to turn on the downstream semiconductor fuse 66 is input from the second microcomputer 41, or when no signal is output, the downstream drive circuit 67 applies a voltage to the gate of the downstream semiconductor fuse 66 to turn on the downstream semiconductor fuse 66. When a signal (Hi voltage) indicating an instruction to turn off the downstream semiconductor fuse 66 is input from the microcomputer 61, the downstream drive circuit 67 applies a voltage to the gate of the downstream semiconductor fuse 66 to turn off the downstream semiconductor fuse 66.

[0078] 9 is a block diagram showing an example of the configuration of the microcomputer 61 according to the second embodiment. The microcomputer 61 operates as a control unit capable of determining the state of the vehicle C, controlling the upstream semiconductor fuse 62, and controlling the fuse function and relay function of the downstream semiconductor fuse 66. The microcomputer 61 includes an input unit 610, an input unit 611, an A / D conversion unit 612, an output unit 613, output units 617 to 619, a storage unit 614, and a processing unit 615. The input unit 610, the A / D conversion unit 612, the output unit 613, output units 617 to 619, the storage unit 614, and the processing unit 615 are connected to an internal bus 616. The A / D conversion unit 612 is connected to the input unit 611.

[0079] An identification signal for identifying the type of the load 5 connected to the downstream path 22 is input to the input unit 610. The identification signal input to the input unit 610 is, for example, a signal output by the load 5, but may also be a signal output by another in-vehicle device capable of determining the type of the load 5 connected to the downstream path 22.

[0080] The input unit 611 receives upstream current information (upstream current value) from the current detection circuit 65. When the input unit 611 receives the upstream current information, the input unit 611 outputs the input analog current information to the A / D conversion unit 612. The processing unit 615 acquires, from the A / D conversion unit 612, the digital current information converted by the A / D conversion unit 612.

[0081] The output unit 613 outputs a Hi voltage or a Low voltage to the upstream drive circuit 63. The output unit 613 switches the voltage output to the upstream drive circuit 63 between a Hi voltage and a Low voltage in accordance with an instruction from the processing unit 615. The upstream drive circuit 63 switches the upstream semiconductor fuse 62 on or off depending on the voltage input from the output unit 613.

[0082] The output units 617-619 output a Hi voltage or a Low voltage to each downstream driving circuit 67. The output units 617-619 switch the voltage output to the downstream driving circuit 67 between a Hi voltage and a Low voltage in accordance with an instruction from the processing unit 615. Each downstream driving circuit 67 switches each downstream semiconductor fuse 66 on or off according to the voltage input from the output units 617-619.

[0083] The storage unit 614 is a non-volatile memory. The storage unit 614 stores a computer program P and a cutoff characteristic table T. The configuration of the cutoff characteristic table T is the same as that of the first embodiment. The processing unit 615 has a processing element, for example, a CPU, that executes processing. The processing element of the processing unit 615 executes the computer program P to execute a process of determining the state of the vehicle C, a process of controlling the upstream semiconductor fuse 62, and a process of controlling the stop (disable) or continued operation (enable) of the fuse function and relay function of the downstream semiconductor fuse 66. The computer program P is used to cause the processing element (computer) of the processing unit 615 to execute processing. When the fuse function continues to operate (when enabled), the processing unit 615 turns off the downstream semiconductor fuse 42 when the current value flowing through the downstream semiconductor fuse 66 exceeds the rated current value of the downstream semiconductor fuse 66. When the relay function continues to operate (when enabled), the processing unit 615 switches the downstream semiconductor fuse 66 on or off based on the necessity of power supply to the load 5 connected to the downstream semiconductor fuse 66.

[0084] The computer program P may be stored in a storage medium E so as to be readable by a processing element of the processing unit 615. In this case, the computer program P read from the storage medium E by a reading device (not shown) is stored in the storage unit 614. The storage medium E is an optical disk, a flexible disk, a magnetic disk, a magneto-optical disk, a semiconductor memory, or the like. The optical disk is a CD-ROM, a DVD-ROM, a BD, or the like. The magnetic disk is, for example, a hard disk. The computer program P may be downloaded from an external device (not shown) connected to a communication network (not shown), and the downloaded computer program P may be stored in the storage unit 614.

[0085] Furthermore, the number of processing elements included in the processing unit 615 is not limited to 1, and may be 2 or more. When the processing unit 615 has multiple processing elements, the multiple processing elements may cooperate to execute processing.

[0086] 10 is a flowchart showing a processing procedure of the microcomputer 61 according to the second embodiment. The processing unit 615 of the microcomputer 61 acquires an upstream current value from the current detection circuit 35 (S21). The processing unit 615 determines whether the vehicle C is in a normal current state (low current state) based on the acquired upstream current value (S22). In S22, if the acquired upstream current value is equal to or greater than a predetermined threshold, the processing unit 615 determines that the vehicle C is in a normal current state, and if the acquired upstream current value is less than the predetermined threshold, the processing unit 615 determines that the vehicle C is in a low current state. If the vehicle C is in a normal current state (S22: YES), the processing unit 615 sets the interruption characteristic of the upstream semiconductor fuse 62 to a normal characteristic (S23) and returns the process to S21. If the vehicle C is in a low current state (S22: NO), the processing unit 315 acquires a load identification signal input to the input unit 610 (S24). The processing unit 315 reads out the interruption characteristic table T from the storage unit 314 (S25), and sets the interruption characteristic for controlling the upstream semiconductor fuse 62 based on the load identification signal and the interruption characteristic table (S26). The processing unit 615 stops the fuse function of the downstream semiconductor fuse 66 and allows the relay function to continue to operate (S27).

[0087] The processing unit 615 acquires the upstream current value from the current detection circuit 65 (S28). The processing unit 615 determines whether or not to interrupt the current in the upstream path 21 based on the interruption characteristics and the upstream current value (S29). In S29, when the upstream current value exceeds the rated current value, the processing unit 615 interrupts the current when the current flow time reaches or exceeds a predetermined time corresponding to the current value in the characteristic curve. Alternatively, the processing unit 615 may determine to interrupt the current when the current integration value reaches or exceeds a predetermined value. Note that, when the upstream current value becomes equal to or less than the rated current value before the predetermined time has elapsed, the processing unit 615 determines not to interrupt the current. Also, when the upstream current value exceeds the maximum current value defined in the characteristic curve, the processing unit 615 determines to interrupt the current instantly. When the current in the upstream path 21 is interrupted (S29: YES), the processing unit 615 causes the upstream driving circuit 63 to turn off the upstream semiconductor fuse 62 (S30) and ends the process. If the current in the upstream path 21 is not to be cut off (S29: NO), the processing unit 615 returns the process to S1.

[0088] (Modification) In each of the above-described embodiments, the upstream vehicle-mounted device 3, the downstream vehicle-mounted device 4, and the distribution train-mounted device 6 are provided on the electric circuit, but this is not limited thereto. The upstream vehicle-mounted device 3, the downstream vehicle-mounted device 4, and the distribution train-mounted device 6 may remotely control the upstream semiconductor fuses 32, 62 or the downstream semiconductor fuses 42, 66 provided on the electric circuit 2 from another location.

[0089] In each of the above-described embodiments, the upstream in-vehicle device 3, the downstream in-vehicle device 4, and the distribution train in-vehicle device 6 determine whether the vehicle C is in a normal current state or a low current state, but this is not limited to the above. The upstream in-vehicle device 3, the downstream in-vehicle device 4, or the distribution train in-vehicle device 6 may obtain information on the state of the vehicle C determined by the other in-vehicle device, and control the upstream semiconductor fuses 32, 62 or the downstream semiconductor fuses 42, 66 based on the obtained information on the state of the vehicle C.

[0090] In each of the above-described embodiments, the first microcomputer 31 or the microcomputer 61 refers to the interruption characteristic table T and sets the interruption characteristics of the upstream semiconductor fuses 32, 62 based on the type of the load 5 connected to the downstream path 22, but is not limited to this. When the vehicle C is in a low current state, the first microcomputer 31 or the microcomputer 61 may set the interruption characteristics of the upstream semiconductor fuses 32, 62 to constant interruption characteristics. Furthermore, when the vehicle C is in a low current state, the first microcomputer 31 or the microcomputer 61 may set the interruption characteristics of the upstream semiconductor fuses 32, 62 based on the type of the load 5 that requires power supply in a low current state, among the loads 5 connected to the downstream path 22.

[0091] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents to the scope of the claims. In addition, the independent claims and dependent claims described in the claims can be combined with each other in all combinations regardless of the reference format. Furthermore, the claims use a format in which a claim references two or more other claims (multiple claim format), but this is not limited to this. A format in which a multiple claim (multi-multi claim) that references at least one multiple claim may be used. [Explanation of symbols]

[0092] 1 Power supply 2 electric circuit 21 Upstream electric route (upstream route) 22 Downstream electric route (downstream route) 3 Upstream onboard equipment 31 First microcomputer (microcomputer) 310 Input section 311 Input section 312 A / D conversion section 313 Output section 314 Storage section 315 Processing section 316 Internal Bus 32 Upstream Semiconductor Fuse 33 Drive circuit 34 Resistance 35 Current detection circuit 4 Downstream onboard equipment 41 Second microcomputer 410 Input section 411 Input section 412 A / D conversion section 413 Output section 414 Storage section 415 Processing section 416 Internal Bus 42 Downstream Semiconductor Fuse 43 Drive circuit 44 Resistance 45 Current detection circuit 5. Load 6 Distribution onboard equipment 61 Microcomputer 610 Input section 611 Input section 612 A / D conversion section 613 Output section 614 Storage section 615 Processing section 616 Internal Bus 617 Output section 618 Output section 619 Output section 62 Upstream Semiconductor Fuse 63 Upstream drive circuit 64 Resistance 65 Current detection circuit 66 Downstream Semiconductor Fuse 67 Downstream drive circuit C Vehicle E Storage medium P Computer Program S In-vehicle system T Cut-off characteristics table

Claims

1. An in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, the state of the vehicle includes a normal current state in which the current consumption of the load is a normal current, and a low current state in which the current consumption of the load is smaller than the normal current; An upstream path connected to the power supply; a downstream path branching off from the upstream path and connected to the load; an upstream vehicle-mounted device including an upstream semiconductor fuse provided in the upstream path; a downstream in-vehicle device including a downstream semiconductor fuse having a fuse function and a relay function, the downstream semiconductor fuse being provided in each of the downstream paths; Equipped with The upstream vehicle-mounted device is a first control unit that controls the on / off of the upstream semiconductor fuse; Equipped with The downstream in-vehicle device is A second control unit that controls the on / off of the downstream semiconductor fuse; Equipped with the first control unit sets a cutoff characteristic of the upstream semiconductor fuse to a lower characteristic when the vehicle is in a low current state compared to a cutoff characteristic when the vehicle is in a normal current state, The second control unit stops a fuse function of the downstream semiconductor fuse when the vehicle is in a low current state. In-vehicle systems.

2. The first control unit sets a cutoff characteristic of the upstream semiconductor fuse based on a combination of the loads connected to the downstream path. The in-vehicle system according to claim 1 .

3. The first control unit sets the interruption characteristics of the upstream semiconductor fuse so that a time until the upstream semiconductor fuse is turned off for a current value of an overcurrent is shorter than a time until the downstream semiconductor fuse is turned off for a current value of an overcurrent in the interruption characteristics of the downstream semiconductor fuse when a fuse function is active, and a rated current value is set to be higher than a sum of current values ​​in the downstream path when the vehicle is in a low current state.

3. The in-vehicle system according to claim 1 or 2.

4. The first control unit is A current value of the upstream path is obtained; When the current of the upstream path obtained flows for a predetermined period of time or longer in a state in which the current exceeds a rated current value in the interruption characteristics of the upstream semiconductor fuse, the upstream semiconductor fuse is switched off.

3. The in-vehicle system according to claim 1 or 2.

5. At least a portion of the downstream semiconductor fuses are P-channel FETs.

3. The in-vehicle system according to claim 1 or 2.

6. A distribution train-mounted device that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, the state of the vehicle includes a normal current state in which the current consumption of the load is a normal current, and a low current state in which the current consumption of the load is smaller than the normal current; An upstream path connected to the power supply; a downstream path branching off from the upstream path and connected to the load; an upstream semiconductor fuse provided in the upstream path; a downstream semiconductor fuse provided in each of the downstream paths and having a fuse function and a relay function; a control unit for controlling the on / off of the upstream semiconductor fuse and the downstream semiconductor fuse; Equipped with The control unit is deactivating the fuse function of the downstream semiconductor fuse when the vehicle is in a low current state; The interruption characteristic of the upstream semiconductor fuse is set to a lower characteristic compared to when the vehicle is in a normal current state. Distribution onboard equipment.

7. The control unit sets a cutoff characteristic of the upstream semiconductor fuse based on a combination of the loads connected to the downstream path. The on-board device for distribution trains according to claim 6.

8. The control unit is A current value of the upstream path is obtained; When the current of the upstream path obtained flows for a predetermined period of time or longer in a state in which the current exceeds a rated current value in the interruption characteristics of the upstream semiconductor fuse, the upstream semiconductor fuse is switched off. The on-board device for distribution trains according to claim 6 or 7.

9. At least a portion of the downstream semiconductor fuses are P-channel FETs. The on-board device for distribution trains according to claim 6 or 7.

10. A method for controlling an in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply device to a plurality of loads, comprising the steps of: the state of the vehicle includes a normal current state in which the current consumption of the load is a normal current, and a low current state in which the current consumption of the load is smaller than the normal current; The in-vehicle system includes: An upstream path connected to the power supply; a downstream path branching off from the upstream path and connected to the load; an upstream semiconductor fuse provided in the upstream path; a downstream semiconductor fuse provided in each of the downstream paths and having a fuse function and a relay function; Equipped with When the vehicle is in a low current state, the interruption characteristic of the upstream semiconductor fuse is set to a lower characteristic compared to when the vehicle is in a normal current state; Disabling the fuse function of the downstream semiconductor fuse Control methods.

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