Vehicle-mounted system, power distribution vehicle-mounted device, and control method

Abstract

An in-vehicle system according to one embodiment of the present disclosure is provided with: an upstream line connected to a power supply device; a downstream line branched from the upstream line and connected to the load; the upstream vehicle-mounted device comprises an upstream semiconductor fuse arranged on the upstream line; and a downstream in-vehicle device including downstream semiconductor fuses provided in the downstream lines, the upstream in-vehicle device including a first control unit for controlling the on / off of the upstream semiconductor fuses, and the downstream in-vehicle device including a second control unit for controlling the on / off of the downstream semiconductor fuses. When the vehicle is in a low-current state, the first control unit sets the cutoff characteristic of the upstream semiconductor fuse to a lower characteristic than when the vehicle is in a normal-current state, and when the vehicle is in a low-current state, the second control unit fixes the downstream semiconductor fuse to be on.

Description

Technical Field

[0001] The present disclosure relates to a vehicle-mounted system, a power distribution vehicle-mounted device, and a control method.

[0002] This application claims the benefit of priority based on Japanese Patent Application No. 2023-026640, filed on February 22, 2023, and incorporates by reference all the contents described in the aforementioned Japanese Application. Background Art

[0003] Vehicles are equipped with a power supply control device that controls the supply of power from a battery to a load (see, for example, Patent Document 1). The power supply control device described in Patent Document 1 provides a semiconductor switch on a current path for current flowing from the battery to the load, and controls the supply of power from the battery to the load by switching the semiconductor switch on or off.

[0004] A semiconductor switch has a control terminal. For example, in the case of a FET (Field Effect Transistor), the control terminal is the gate. The resistance between the two terminals of the semiconductor switch changes depending on the voltage applied to the control terminal. By adjusting the voltage at the control terminal, the resistance between the two terminals of the semiconductor switch is adjusted to a sufficiently low value, turning the semiconductor switch on. By adjusting the voltage at the control terminal, the resistance between the two terminals of the semiconductor switch is adjusted to a sufficiently high value, turning the semiconductor switch off.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-143905 Summary of the Invention

[0008] An in-vehicle system according to one embodiment of the present disclosure is mounted on a vehicle and distributes electric power supplied from a power supply device to a plurality of loads. The vehicle state includes a normal current state, in which the loads consume a normal current, and a low current state, in which the loads consume a current less than the normal current. The in-vehicle system includes an upstream line connected to the power supply device; a downstream line branching from the upstream line and connected to the loads; an upstream in-vehicle device including an upstream semiconductor fuse provided on the upstream line; and a downstream in-vehicle device including downstream semiconductor fuses each provided on the downstream line and having a fuse function and a relay function. The upstream in-vehicle device includes a first control unit that controls the connection or disconnection of the upstream semiconductor fuse, and the downstream in-vehicle device includes a second control unit that controls the connection or disconnection of the downstream semiconductor fuse. When the vehicle is in the low current state, the first control unit sets the disconnection characteristics of the upstream semiconductor fuse to a lower characteristic than when the vehicle is in the normal current state, and the second control unit disables the fuse function of the downstream semiconductor fuse when the vehicle is in the low current state.

[0009] An on-board device according to one embodiment of the present disclosure is a on-board device that is mounted on a vehicle and distributes the power supplied from a power supply device to multiple loads, the vehicle states 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. The on-board device comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream semiconductor fuse provided on the upstream line; downstream semiconductor fuses, each provided on the downstream line, having a fuse function and a relay function; and a control unit that controls the connection or disconnection of the upstream semiconductor fuse and the downstream semiconductor fuse, wherein the control unit stops the fuse function of the downstream semiconductor fuse when the vehicle is in the low current state and sets the disconnection characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in the normal current state.

[0010] A control method according to one embodiment of the present disclosure is a control method for a vehicle-mounted system that is mounted on a vehicle and distributes electric power supplied from a power supply device to a plurality of loads, wherein the vehicle states include: a normal current state, in which the current consumption of the load is the normal current; and a low current state, in which the current consumption of the load is less than the normal current. The vehicle-mounted system comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream semiconductor fuse provided on the upstream line; and downstream semiconductor fuses provided on the downstream lines, each having a fuse function and a relay function. When the vehicle state is the low current state, the control method sets the cutting characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in the normal current state, thereby stopping the fuse function of the downstream semiconductor fuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a block diagram showing a configuration example of the in-vehicle system according to the first embodiment.

[0012] Figure 2 This is a block diagram showing an example of the configuration of a first microcomputer.

[0013] Figure 3 This is an explanatory diagram showing a cutting characteristic table.

[0014] Figure 4 It is an explanatory diagram showing a characteristic curve.

[0015] Figure 5 This is a block diagram showing an example of the configuration of a second microcomputer.

[0016] Figure 6 This is a flowchart showing the processing steps of the first microcomputer.

[0017] Figure 7 This is a flowchart showing the processing steps of the second microcomputer.

[0018] Figure 8 This is a block diagram showing a configuration example of an in-vehicle system according to the second embodiment.

[0019] Figure 9 This is a block diagram showing a configuration example of a microcomputer according to the second embodiment.

[0020] Figure 10 This is a flowchart showing the processing procedure of the microcomputer according to the second embodiment. DETAILED DESCRIPTION

[0021] [Problems to be Solved by the Present Disclosure]

[0022] However, when a vehicle in either the normal current state or the low current state is in the low current state, the power available for processing by the vehicle's onboard system is limited, and the required power needs to be reduced.

[0023] The present disclosure has been made in view of such circumstances, and an object thereof is to provide an in-vehicle system or the like that can reduce the electric power required for control when the vehicle is in a low current state.

[0024] [Effects of the Present Disclosure]

[0025] In the in-vehicle system according to one embodiment of the present disclosure, when the vehicle is in a low current state, the electric power required for control can be reduced.

[0026] [Description of Embodiments of the Present Disclosure]

[0027] First, the embodiments of the present disclosure will be described by way of example. At least some of the embodiments described below may be arbitrarily combined.

[0028] (1) An in-vehicle system according to one embodiment of the present disclosure is mounted on a vehicle and distributes electric power supplied from a power supply device to a plurality of loads, wherein the vehicle state includes: a normal current state, in which the loads consume a normal current; and a low current state, in which the loads consume a current less than the normal current. The in-vehicle system includes: an upstream line connected to the power supply device; a downstream line branching from the upstream line and connected to the loads; an upstream in-vehicle device including an upstream semiconductor fuse provided on the upstream line; and a downstream in-vehicle device including downstream semiconductor fuses each provided on the downstream line and having a fuse function and a relay function, the upstream in-vehicle device including a first control unit for controlling the connection or disconnection of the upstream semiconductor fuse, and the downstream in-vehicle device including a second control unit for controlling the connection or disconnection of the downstream semiconductor fuse, wherein the first control unit sets the disconnection characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in the normal current state when the vehicle is in the low current state, and the second control unit disables the fuse function of the downstream semiconductor fuse when the vehicle is in the low current state.

[0029] In this embodiment, the power supplied from the power supply device is supplied to multiple loads via an upstream line and multiple downstream lines branching from the upstream line. For example, each downstream line is connected to a load. An on-board device is provided on the upstream line and each downstream line. In other words, the on-board device operates as a power supply control device. The on-board device includes an upstream on-board device provided on the upstream line and a downstream on-board device provided on the downstream line. The upstream on-board device controls the power supply to the downstream line via an upstream semiconductor fuse and a first control unit that controls the upstream semiconductor fuse. Each downstream on-board device controls the power supply to the load via a downstream semiconductor fuse and a second control unit that controls the downstream semiconductor fuse. Alternatively, the downstream on-board device may include a mechanical switch, and the second control unit may control the power supply to the load by controlling the mechanical switch. When the vehicle is started, a normal current state is achieved in which a normal current flows from the power supply device to the load. When the vehicle is stopped, a low current state is achieved in which a low current (dark current) flows from the power supply device to the load. The low current has a lower current value than the normal current value, for example, 10mA to 100mA. The low current value is, for example, approximately one hundredth or one thousandth of the normal current value. When the vehicle is stopped, the current supplied to the vehicle's loads is set to a low current, thereby reducing power consumption in the power supply device. For example, the vehicle starts when the power switch or 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 tripping characteristics of the upstream semiconductor fuse to a lower characteristic than when the vehicle is in a normal current state. Furthermore, the second control unit of each downstream on-board device disables (disables) the fuse function of the downstream semiconductor fuse and continues to operate (enables) the relay function. Thus, when in a low current state, the second control unit does not need to switch the downstream semiconductor fuse on or off based on the fuse function. By reducing the driving frequency of the second control unit or fixing the downstream semiconductor fuse in an on-state to disable the second control unit's fuse function for the downstream semiconductor fuse, the power required for processing by the second control unit can be reduced. Furthermore, by lowering the tripping characteristic of the upstream semiconductor fuse, overcurrent detection can be based on the current value in low-current conditions, enabling highly accurate protection of downstream lines. Alternatively, the downstream semiconductor fuse can be configured without a relay function, with a separate relay installed in the downstream line. In this case, the downstream semiconductor fuse is locked in during low-current conditions, and the fuse function is disabled when power is available.

[0030] (2) In the in-vehicle system according to one aspect of the present disclosure, the first control unit sets the cutting characteristics of the upstream semiconductor fuse based on a combination of the loads connected to the downstream line.

[0031] In this embodiment, the first control unit stores, for example, a table containing tripping characteristics set for combinations of loads connected to the downstream line, and sets the tripping characteristics of the upstream semiconductor fuse based on this table. Furthermore, the first control unit may set the tripping characteristics of the upstream semiconductor fuse based on the combination of loads connected to the downstream line that need to be activated when the vehicle is in a low-current state. This allows power to be supplied to loads requiring power during low-current conditions while also accurately protecting the downstream line.

[0032] (3) In an in-vehicle system of one embodiment of the present disclosure, the first control unit sets the cutting characteristics of the upstream semiconductor fuse to a shorter time before the upstream semiconductor fuse is disconnected relative to the current value of the overcurrent than the time before the downstream semiconductor fuse is disconnected relative to the current value of the overcurrent in the cutting characteristics of the downstream semiconductor fuse when the fuse function is valid, and the rated current value is higher than the total value of the current values ​​in the downstream line when the vehicle is in a low current state.

[0033] In this embodiment, the tripping characteristics of the upstream semiconductor fuse are set, for example, so that the time until the upstream semiconductor fuse is tripped is shorter relative to the overcurrent value, compared to the downstream semiconductor fuse whose tripping characteristics, when the fuse function is enabled, are shortest relative to the overcurrent value. Furthermore, the tripping characteristics of the upstream semiconductor fuse are set, for example, so that the rated current value is higher than the sum of the current values ​​flowing through the downstream semiconductor fuses turned on by the relay function (the current values ​​in the downstream line). In other words, if only one downstream semiconductor fuse is turned on by the relay function, the tripping characteristics of the upstream semiconductor fuse are set to a value lower than the tripping characteristics of that downstream semiconductor fuse. This allows for more accurate protection of the downstream line.

[0034] (4) In an in-vehicle system according to one embodiment of the present disclosure, the first control unit obtains a current value of the upstream line, and switches the upstream semiconductor fuse to open when the obtained current of the upstream line flows for a period of time exceeding a rated current value in the disconnection characteristics of the upstream semiconductor fuse.

[0035] In this embodiment, when a current exceeding the rated current value flows through the upstream line for a predetermined period of time, the upstream semiconductor fuse is switched open, thereby protecting the downstream line. Furthermore, the higher the current value flowing through the upstream line, the shorter the time it takes for the first control unit to switch the upstream semiconductor fuse open. The tripping characteristic is a characteristic of the upstream semiconductor fuse, comprising the rated current value for current interruption and the time it takes to interrupt current in response to a current exceeding the rated current value (overcurrent). When the tripping characteristic of the upstream semiconductor fuse is high, the rated current value is high, and the time it takes to interrupt current in response to an overcurrent is long. When the tripping characteristic is reduced, the rated current value decreases, and the time it takes to interrupt current in response to an overcurrent is shortened. In other words, the product of the current value and the time until interruption (the accumulated current value) fluctuates depending on the level of the tripping characteristic. The tripping characteristic of the upstream semiconductor fuse is set, for example, to be lower than the smoke characteristic of the downstream line or the sum of the device characteristics of the loads connected to the downstream line. Thus, by opening the upstream semiconductor fuse in the event of an overcurrent, the possibility of smoke generation in the downstream line or load failure can be reduced. Furthermore, when the current value flowing through the upstream line is equal to or less than the rated current value, the first control unit does not switch the upstream semiconductor fuse 32 to open.

[0036] (5) In the in-vehicle system according to one aspect of the present disclosure, at least some of the plurality of downstream semiconductor fuses are P-channel FETs.

[0037] In this method, when the vehicle is in a low-current state, the downstream semiconductor fuse can be fixed in the on position without applying voltage to the downstream semiconductor fuse. This eliminates the need for the second control unit to process or apply voltage to disable the fuse function of the downstream semiconductor fuse, thereby reducing the power required for the second control unit's processing.

[0038] (6) A power distribution vehicle-mounted device according to one embodiment of the present disclosure is a power distribution vehicle-mounted device that is mounted on a vehicle and distributes the 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 current consumption of the load is the normal current; and a low current state, in which the current consumption of the load is less than the normal current. The power distribution vehicle-mounted device comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream semiconductor fuse provided on the upstream line; downstream semiconductor fuses provided on the downstream line, each having a fuse function and a relay function; and a control unit that controls the connection or disconnection of the upstream semiconductor fuse and the downstream semiconductor fuse, wherein the control unit stops the fuse function of the downstream semiconductor fuse when the vehicle is in the low current state and sets the disconnection characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in the normal current state.

[0039] In this method, power supplied from a power supply device is supplied to multiple loads via an onboard device. In other words, the onboard device functions as a power supply control device. The onboard device includes an upstream line connected to the power supply device and a downstream line branching from the upstream line and connected to each load. A control unit in the onboard device controls the connection and disconnection of upstream semiconductor fuses provided on the upstream line and downstream semiconductor fuses provided on the downstream line. When the vehicle is in a low-current state, the control unit disables the fuse function of the downstream semiconductor fuse and sets the upstream semiconductor fuse's disconnection characteristics to a lower value. This reduces the power required for processing and accurately protects the downstream line.

[0040] (7) In the power distribution vehicle-mounted device according to one aspect of the present disclosure, the control unit sets the disconnection characteristics of the upstream semiconductor fuse based on a combination of the loads connected to the downstream line.

[0041] In this embodiment, the control unit stores, for example, a table containing tripping characteristics set for combinations of loads connected to the downstream line and sets the tripping characteristics of the upstream semiconductor fuse based on this table. Furthermore, the first control unit may set the tripping characteristics of the upstream semiconductor fuse based on the combination of loads connected to the downstream line that need to be activated when the vehicle is in a low-current state. This allows power to be supplied to loads requiring power during low-current conditions while accurately protecting the downstream line.

[0042] (8) In one embodiment of the present disclosure, in a power distribution vehicle-mounted device, the control unit obtains a current value of the upstream line, and switches the upstream semiconductor fuse to be disconnected when the obtained current of the upstream line flows for a predetermined time or longer in a state exceeding a rated current value in the disconnection characteristics of the upstream semiconductor fuse.

[0043] In this method, when a current exceeding a rated current value flows through an upstream line for a predetermined period of time, the upstream semiconductor fuse is switched off, thereby protecting the downstream line.

[0044] (9) In the power distribution vehicle-mounted device according to one aspect of the present disclosure, at least some of the plurality of downstream semiconductor fuses are P-channel FETs.

[0045] In this method, when the vehicle is in a low current state, the downstream semiconductor fuse can be fixed to be connected without applying voltage to the downstream semiconductor fuse, thereby reducing the power required for the control unit to process when stopping the fuse function of the downstream semiconductor fuse.

[0046] (10) A control method according to one embodiment of the present disclosure is a control method for a vehicle-mounted system that is mounted on a vehicle and distributes electric power supplied from a power supply device to a plurality of loads, wherein the vehicle states include: a normal current state, in which the current consumption of the load is the normal current; and a low current state, in which the current consumption of the load is less than the normal current. The vehicle-mounted system comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream semiconductor fuse provided on the upstream line; and downstream semiconductor fuses provided on the downstream lines, each having a fuse function and a relay function. When the vehicle state is the low current state, the control method sets the cutting characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in the normal current state, thereby stopping the fuse function of the downstream semiconductor fuse.

[0047] In this embodiment, it is possible to protect downstream lines with high accuracy while reducing the power required for processing in the vehicle-mounted system.

[0048] [Details of the embodiment of the present disclosure]

[0049] Hereinafter, specific examples of the power supply control device according to the embodiment of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to these examples, but is defined by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0050] (Implementation Method 1)

[0051] Figure 1This is a block diagram showing an example configuration of an in-vehicle system according to a first embodiment. The in-vehicle system S is installed in a vehicle C and includes a power supply device 1, an electric circuit 2, an upstream in-vehicle device 3, multiple downstream in-vehicle devices 4, and multiple loads 5. The electric circuit 2 includes an upstream circuit (upstream line) 21 connected to the power supply device and downstream circuits (downstream lines) 22 branching from the upstream circuit and connected to the loads. The power supply device 1 is a power source that outputs direct current, such as a battery, such as a lead-acid battery, a hydrogen battery, or a secondary battery, or an AC generator. The upstream in-vehicle device 3 is connected to the positive terminal of the power supply device 1 and multiple downstream in-vehicle devices 4. Each downstream in-vehicle device 4 is connected to one end of the upstream in-vehicle device 3 and the loads 5. The upstream in-vehicle device 3 and the downstream in-vehicle device 4 are, for example, electronic control units (ECUs) that control the current from the power supply device 1 to the loads 5. The negative terminal of the power supply device 1 and the other end of the loads 5 are grounded. Each downstream line 22 is connected to, for example, one load 5. In this embodiment, a method is described in which the current flowing from the upstream line 21 branches into three downstream lines 22 to supply power to three loads 5. Furthermore, the number of downstream lines 22 and the number of loads 5 are not limited to three.

[0052] When the vehicle is started, power supply device 1 supplies power at a current (normal current) sufficient to operate load 5, placing the vehicle in a normal current state. When the vehicle is stopped, power supply device 1 supplies power at a low current value lower than the normal current, placing the vehicle in a low current state. Loads 5 supplied with low current power include, for example, interior lights and safety-related devices that must operate even when the vehicle is stopped.

[0053] The upstream onboard device 3 is installed on the upstream line 21 and transmits the power received from the power supply device 1 to the downstream onboard device 4. The upstream onboard device 3 includes a first microcomputer 31, an upstream semiconductor fuse 32, a drive circuit 33, a resistor 34, and a current detection circuit 35. The details of the first microcomputer 31 will be described later.

[0054] The upstream semiconductor fuse 32 is, for example, an N-channel FET (Field Effect Transistor) and is provided on the upstream line 21 with its drain positioned upstream relative to its source. Specifically, the drain of the upstream semiconductor fuse 32 is connected to the power supply device 1. Alternatively, a P-channel FET, transistor, thyristor, or IPD (Intelligent Power Device) may be used for the upstream semiconductor fuse 32. When a voltage is applied to the gate of the upstream semiconductor fuse 32, the upstream semiconductor fuse 32 is closed, allowing current to flow. When no voltage is applied to the gate of the upstream semiconductor fuse 32, the upstream semiconductor fuse 32 is open, preventing current from flowing.

[0055] The driver 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 driver circuit 33 is, for example, an electronic device such as an FPGA, ASIC, or ASSP. Alternatively, the driver circuit 33 may be a software processing unit such as a microcomputer or DSP. When a signal (high voltage) indicating that the upstream semiconductor fuse 32 is to be turned on is input from the first microcomputer 31, the driver circuit 33 applies a voltage to the gate of the upstream semiconductor fuse 32, thereby turning the upstream semiconductor fuse 32 on. When a signal (low voltage) indicating that the upstream semiconductor fuse 32 is to be turned off is input from the first microcomputer 31, the driver circuit 33 does not apply a voltage to the gate of the upstream semiconductor fuse 32, thereby turning the upstream semiconductor fuse 32 off.

[0056] 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 vehicle-mounted device 4 . Alternatively, the resistor 34 may be provided on the upstream side of the upstream semiconductor fuse 32 .

[0057] 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 analog upstream current information indicating the detected upstream current value to the first microcomputer 31 .

[0058] The downstream onboard device 4 is provided on the downstream line 22 and transmits power received from the upstream onboard device 3 to the load 5. The multiple downstream onboard devices 4 included in the onboard system S have the same structure. Therefore, the following description focuses on a single downstream onboard device 4. The downstream onboard 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 details of the second microcomputer 41 will be described later.

[0059] The downstream semiconductor fuse 42 is, for example, a P-channel FET, and is provided on the downstream line 22 with its source positioned upstream relative to its drain. That is, the source of the downstream semiconductor fuse 42 is connected to the upstream onboard device 3. Alternatively, an F-channel FET, transistor, thyristor, or IPD may be used as the downstream semiconductor fuse 42. Furthermore, a mechanical switch may be provided in place 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 disconnected, and no current flows. When no voltage is applied to the gate of the downstream semiconductor fuse 42, the downstream semiconductor fuse 42 is disconnected, allowing current to flow.

[0060] The driver 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 driver circuit 43 is, for example, an electronic device such as an FPGA, ASIC, or ASSP. Alternatively, the driver circuit 43 may be a software processing unit such as a microcomputer or DSP. When the second microcomputer 41 inputs a signal (low voltage) indicating that the downstream semiconductor fuse 42 should be turned on, or when no signal is output, the driver circuit 43 applies a voltage to the gate of the downstream semiconductor fuse 42, turning the downstream semiconductor fuse 42 on. When the second microcomputer 41 inputs a signal (high voltage) indicating that the downstream semiconductor fuse 42 should be turned off, the driver circuit 43 applies a voltage to the gate of the downstream semiconductor fuse 42, turning the downstream semiconductor fuse 42 off.

[0061] One end of resistor 44 is connected to the drain of downstream semiconductor fuse 42. The other end of resistor 44 is connected to load 5. Resistor 44 may also be provided upstream of downstream semiconductor fuse 42. Furthermore, a fuse element (mechanical fuse) may be provided between resistor 44 and load 5.

[0062] 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 analog downstream current information indicating the detected downstream current value to the second microcomputer 41 .

[0063] Figure 2 This is a block diagram showing an example 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 converter 312, an output unit 313, a storage unit 314, and a processing unit 315. The input unit 310, A / D converter 312, output unit 313, storage unit 314, and processing unit 315 are connected to an internal bus 316. The A / D converter 312 is connected to the input unit 311.

[0064] An identification signal for identifying the type of the load 5 connected to the downstream line 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 onboard device capable of determining the type of the load 5 connected to the downstream line 22.

[0065] Upstream current information (upstream current value) is input from current detection circuit 35 to input unit 311. Upon receiving the upstream current information, input unit 311 outputs the input analog upstream current information to A / D converter 312. Processing unit 315 obtains the digital upstream current information converted by A / D converter 312 from A / D converter 312.

[0066] The output unit 313 outputs a high voltage or a low voltage to the driver circuit 33. The output unit 313 switches the voltage output to the driver circuit 33 to a high voltage or a low voltage according to the instruction of the processing unit 315. The driver circuit 33 switches the upstream semiconductor fuse 32 on or off according to the voltage input from the output unit 313.

[0067] Storage unit 314 is a nonvolatile memory. A computer program P1 and a disconnection characteristic table T are stored in storage unit 314. Processing unit 315 includes a processing element, such as a CPU (Central Processing Unit), for executing processing. The processing element in processing unit 315 executes computer program P1 to determine the state of vehicle C and control upstream semiconductor fuse 32. Computer program P1 causes the processing element (computer) in processing unit 315 to execute processing.

[0068] Alternatively, the computer program P1 may be stored in a storage medium E in a manner readable by the processing elements of the processing unit 315. 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 disc, a floppy disk, a magnetic disk, a magneto-optical disc, or a semiconductor memory. An optical disc is a CD (Compact Disc)-ROM (Read Only Memory), a DVD (Digital Versatile Disc)-ROM, or a BD (Blu-ray Disc). An example of a magnetic disk is a hard disk. Alternatively, 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.

[0069] Furthermore, the number of processing elements included in the processing unit 315 is not limited to one, and may be two or more. When the processing unit 315 includes a plurality of processing elements, the plurality of processing elements may execute processing in collaboration.

[0070] Figure 3 It is an explanatory diagram showing the cutting characteristic table T. Figure 4 : is an explanatory diagram showing a characteristic curve. The management items of the cut-off characteristic table T include, for example, a connected load field and a characteristic curve field. The connected load field stores a combination of the types of loads 5 connected to the downstream line 22. In this embodiment, the description is made of a method in which the types of loads 5 include four types: A, B, C, and D. In addition, the types of loads 5 may correspond to the types of devices such as interior lights equipped with the loads 5. In addition, Figure 3In the example shown, different types of loads 5 are connected to all three downstream lines 22 , but the present invention is not limited thereto. A load 5 may be connected to only some of the downstream lines 22 , or the same type of load 5 may be connected to multiple downstream lines 22 .

[0071] The characteristic curve field stores a characteristic curve representing the tripping characteristics of the upstream semiconductor fuse 32 selected for the combination of load types 5 connected to the downstream line 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 the form of quadratic array data. The processing unit 315 selects a characteristic curve stored in the tripping characteristic table T based on the combination of load types 5 to set the tripping characteristics.

[0072] The tripping characteristic is a characteristic of the upstream semiconductor fuse 32. It includes the current value at which the processing unit 315 causes the upstream semiconductor fuse 32 to open and interrupt the current, and the energized time until the current is interrupted for currents exceeding the rated current value (overcurrent). When the upstream semiconductor fuse has a high tripping characteristic, the rated current value is high, and the energized time until the fuse is interrupted for overcurrents is long. When the tripping characteristic is reduced, the rated current value decreases, and the energized time until the fuse is interrupted for overcurrents is shortened. In other words, the product of the current value and the energized time until the fuse is interrupted (the accumulated current value) fluctuates depending on the level of the tripping characteristic. When the upstream current value is greater than the minimum current value defined in the characteristic curve, that is, when the upstream current value exceeds the rated current value, and the energized time exceeds a predetermined time, the processing unit 315 switches the upstream semiconductor fuse 32 open. The rated current value indicates the maximum current value at which the upstream semiconductor fuse 32 will not open even if the current flows for a long time. The rated current value fluctuates depending on the level of the tripping characteristic.

[0073] The characteristic curve is a curve representing the cutting characteristic of the upstream semiconductor fuse 32 , that is, the energization time until the processing unit 315 switches the upstream semiconductor fuse 32 to open with respect to the current value flowing in the upstream line 21 . Figure 4 The graph shown shows characteristic curves of the upstream semiconductor fuse 32 in a normal current state and a low current state, where the vertical axis represents the current value flowing through the upstream line 21 (upstream current value) and the horizontal axis represents the energization time.

[0074] like Figure 4As shown, the processing unit 315 sets the tripping characteristics of the upstream semiconductor fuse 32 to be lower during a low current state than the tripping characteristics during a normal current state (normal characteristics). Furthermore, the tripping characteristics of the upstream semiconductor fuse 32 during a low current state are offset, for example, to be lower than the sum of the device characteristics of the loads 5 connected to the downstream line 22 and powered by the relay function of the downstream semiconductor fuse 42. In other words, the tripping characteristics of the upstream semiconductor fuse 32 during a low vehicle current state are set to shorten the time it takes for the upstream semiconductor fuse 32 to trip relative to the overcurrent value, compared to the downstream semiconductor fuse 42 that has the shortest time before tripping relative to the overcurrent value among the downstream semiconductor fuses 42 that are closed by the relay function and have the shortest tripping characteristics when the fuse function is enabled.

[0075] In this embodiment, the power consumed by the load 5 in the low-current state increases in the order of type A, B, C, and D. In this case, the characteristic curve representing the tripping characteristics increases in the order of W, X, Y, and Z. Specifically, the processing unit 315 sets the tripping characteristics of the upstream semiconductor fuse 32 to a higher value as the power consumption of the load 5 connected to the downstream line 22 increases. Specifically, the tripping characteristics of the upstream semiconductor fuse 32 are set so that the rated current value is higher than the sum of the current flowing through the downstream semiconductor fuse 42 (which is closed by the relay function) and the load 5 connected to it (the current value in the downstream line).

[0076] In this embodiment, the processing unit 315 sets the tripping characteristics of the upstream semiconductor fuse 32 based on a tripping characteristic table T that stores characteristic curves selected for combinations of load types 5 connected to the downstream line 22. However, the present invention is not limited to this. The storage unit 314 may also store a table storing device characteristics for each type of load 5. Based on this table, the processing unit 315 uses an offset value to shift (lower) the sum of the device characteristics of the loads 5 connected to the downstream line 22 downward, thereby setting the tripping characteristics of the upstream semiconductor fuse 32. The offset value may be a predetermined coefficient less than 1, such as 0.8, that is multiplied by the sum of the device characteristics of the loads 5. Alternatively, the processing unit 315 may set the tripping characteristics of the upstream semiconductor fuse 32 by shifting the sum of the smoke emission characteristics of the downstream line 22 using the offset value.

[0077] Figure 5This is a block diagram showing an example configuration of the second microcomputer 41. The second microcomputer 41 functions 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 converter 412, an output unit 413, a storage unit 414, and a processing unit 415. The input unit 410, A / D converter 412, output unit 413, storage unit 414, and processing unit 415 are connected to an internal bus 416. The A / D converter 412 is connected to the input unit 411.

[0078] The downstream current information is input from the current detection circuit 45 to the input unit 411. Upon receiving the downstream current information, the input unit outputs the input analog downstream current information to the A / D converter 412. The processing unit 415 obtains the digital downstream current information converted by the A / D converter 412 from the A / D converter 412.

[0079] The output unit 413 outputs a high voltage or a low voltage to the driver circuit 43. The output unit 413 switches the voltage output to the driver circuit 43 to a high voltage or a low voltage according to the instruction of the processing unit 415. The driver circuit 43 switches the downstream semiconductor fuse 42 on or off according to the voltage input from the output unit 413.

[0080] The storage unit 414 is a non-volatile memory. A computer program P is stored in the storage unit 414. The processing unit 415 includes a processing element, such as a CPU, for executing processing. By executing the computer program P, the processing element in the processing unit 415 determines the state of the vehicle C and controls whether the fuse function and relay function of the downstream semiconductor fuse 42 should be deactivated (disabled) or continued (enabled). The computer program P causes the processing element (computer) in the processing unit 415 to execute the processing. If the current flowing through the downstream semiconductor fuse 42 exceeds the rated current value of the downstream semiconductor fuse 42 while the fuse function is still active (enabled), the processing unit 415 opens the downstream semiconductor fuse 42. Furthermore, if the relay function is still active (enabled), the processing unit 415 switches the downstream semiconductor fuse 42 on or off based on whether power needs to be supplied to the load 5 connected to the downstream semiconductor fuse 42.

[0081] Alternatively, the computer program P may be stored in a storage medium E in a manner readable by the processing elements 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 disc, a floppy disk, a magnetic disk, a magneto-optical disc, or a semiconductor memory. An optical disc is a CD-ROM, a DVD-ROM, or a BD. A magnetic disk is, for example, a hard disk. Alternatively, 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.

[0082] Figure 6 This is a flowchart showing the processing steps of the first microcomputer 31. In the initial state, the upstream semiconductor fuse 32 is closed by the first microcomputer 31. The processing unit 315 of the first microcomputer 31 obtains the upstream current value from the current detection circuit 35 (S1). Based on the obtained upstream current value, the processing unit 315 determines whether the vehicle C is in a normal current state (or a low current state) (S2). In S2, the processing unit 315 determines that the vehicle C is in a normal current state if the obtained upstream current value is greater than a predetermined threshold value, and determines that the vehicle C is in a low current state if the obtained upstream current value is less than the predetermined threshold value. If the vehicle C is in a normal current state (S2: Yes), the processing unit 315 sets the tripping characteristics of the upstream semiconductor fuse 32 to the normal characteristics (S3) and returns to S1. If the vehicle C is in a low current state (S2: No), the processing unit 315 obtains the load identification signal input to the input unit 310 (S4). The processing unit 315 reads the cutting characteristic table T from the storage unit 314 ( S5 ), and sets the cutting characteristic for controlling the upstream semiconductor fuse 32 based on the load identification signal and the cutting characteristic table ( S6 ).

[0083] The processing unit 315 obtains the upstream current value from the current detection circuit 35 (S7). Based on the cutoff characteristic and the upstream current value, the processing unit 315 determines whether to cut off the current in the upstream line 21 (S8). In S8, if the upstream current value exceeds the rated current value, the processing unit 315 cuts off the current if the energized time exceeds a predetermined time corresponding to the current value in the characteristic curve. Alternatively, the processing unit 315 may determine to cut off the current if the integrated current value exceeds a predetermined value. Furthermore, if the upstream current value falls below the rated current value before a predetermined time has elapsed, the processing unit 315 determines not to cut off the current. Furthermore, if the upstream current value exceeds the maximum current value defined in the characteristic curve, the processing unit 315 determines to cut off the current instantaneously. If the current in the upstream line 21 is cut off (S8: Yes), the processing unit 315 causes the drive circuit 33 to open the upstream semiconductor fuse 32 (S9), terminating the process. If the current in the upstream line 21 is not cut off (S8: No), the processing unit 315 returns the process to S1.

[0084] Figure 7 This is a flowchart showing the processing steps of the second microcomputer 41. The processing unit 415 of the second microcomputer obtains the downstream current value from the current detection circuit 45 (S11). Based on the downstream current value, the processing unit 415 determines whether the vehicle C is in a normal current state (S12). If the vehicle C is in a normal current state (S12: Yes), the processing unit 415 returns the process to S11. If the vehicle C is in a low current state (S12: No), the processing unit 415 disables the fuse function of the downstream semiconductor fuse 42 while continuing to operate the relay function (S13), ending the process.

[0085] With the above configuration and processing, the second microcomputer 41 does not need to control the fuse function of the downstream semiconductor fuse 42 when the vehicle C is in a dark current state. This reduces the power required for processing while protecting the downstream line 22.

[0086] (Implementation Method 2)

[0087] In Embodiment 1, circuit 2 branches from upstream line 21 to downstream line 22 between multiple devices. However, branching may also be performed within a single device. Below, Embodiment 2 will describe the differences from Embodiment 1. The remaining configuration, except for the configuration described below, is the same as that of Embodiment 1. Therefore, components common to Embodiment 1 are denoted by the same reference numerals as those of Embodiment 1, and their description will be omitted.

[0088] Figure 8 This is a block diagram illustrating an example configuration of an in-vehicle system S according to a second embodiment. The in-vehicle system S according to the second embodiment includes a power supply device 1, a circuit 2, a power distribution on-board device 6, and multiple loads 5. The power distribution on-board device 6 is connected to the positive terminal of the power supply device 1 and one end of the multiple loads 5. The power distribution on-board device 6 is, for example, an ECU that controls the current from the power supply device 1 to the loads 5. The power distribution on-board device 6 includes a circuit 2 that allows current to flow from the power supply device 1 to the loads 5. The circuit 2 includes an upstream circuit (upstream line) 21 connected to the power supply device and a downstream circuit (downstream line) 22 that branches from the upstream line 21 and is connected to the loads. In this embodiment, the downstream line 22 branches into three lines.

[0089] The power distribution vehicle-mounted 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. Details of the microcomputer 61 will be described later.

[0090] The upstream semiconductor fuse 62 is, for example, an N-channel FET and is provided on the upstream line 21 with its drain positioned upstream relative to its source. That is, the drain of the upstream semiconductor fuse 62 is connected to the power supply device 1. Alternatively, a P-channel FET, transistor, thyristor, or IPD may be used for the upstream semiconductor fuse 62. When a voltage is applied to the gate of the upstream semiconductor fuse 62, the upstream semiconductor fuse 62 is closed, allowing current to flow. When no voltage is applied to the gate of the upstream semiconductor fuse 62, the upstream semiconductor fuse 62 is open, preventing current from flowing.

[0091] The upstream driver 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 driver circuit 63 is, for example, an electronic device such as an FPGA, ASIC, or ASSP. Alternatively, the upstream driver circuit 63 may be a software processing unit such as a microcomputer or DSP. When a signal (high voltage) indicating that the upstream semiconductor fuse 62 is to be turned on is input from the microcomputer 61, the upstream driver circuit 63 applies a voltage to the gate of the upstream semiconductor fuse 62, thereby turning the upstream semiconductor fuse 62 on. When a signal (low voltage) indicating that the upstream semiconductor fuse 62 is to be turned off is input from the microcomputer 61, the upstream driver circuit 63 does not apply a voltage to the gate of the upstream semiconductor fuse 62, thereby turning the upstream semiconductor fuse 62 off.

[0092] 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. Alternatively, the resistor 64 may be provided on the upstream side of the upstream semiconductor fuse 62.

[0093] 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 analog current information indicating the detected upstream current value to the microcomputer 61 .

[0094] One downstream semiconductor fuse 66 is provided in each downstream line 22. The downstream semiconductor fuse 66 is, for example, a P-channel FET, and is provided in the downstream line 22 with the source positioned upstream relative to the drain. That is, the source of the downstream semiconductor fuse 66 is connected to the resistor 64. Alternatively, an F-channel FET, transistor, thyristor, or IPD may be used as the downstream semiconductor fuse 66. Furthermore, a mechanical switch may be provided in place 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 disconnected, and no current flows. When no voltage is applied to the gate of the downstream semiconductor fuse 66, the downstream semiconductor fuse 66 is connected, and current can flow.

[0095] A downstream driver circuit 67 is provided for each downstream semiconductor fuse 66. The downstream driver circuit 67 switches the downstream semiconductor fuse 66 between on and off by controlling the voltage applied to the gate of the downstream semiconductor fuse 66. The downstream driver circuit 67 is, for example, an electronic device such as an FPGA, ASIC, or ASSP. Alternatively, the downstream driver circuit 67 may be a software processing unit such as a microcomputer or DSP. When a signal (low voltage) indicating that the downstream semiconductor fuse 66 is to be closed is input from the second microcomputer 41, or when no signal is output, the downstream driver circuit 67 applies a voltage to the gate of the downstream semiconductor fuse 66 to close the downstream semiconductor fuse 66. When a signal (high voltage) indicating that the downstream semiconductor fuse 66 is to be opened is input from the microcomputer 61, the downstream driver circuit 67 applies a voltage to the gate of the downstream semiconductor fuse 66 to open the downstream semiconductor fuse 66.

[0096] Figure 9 This is a block diagram showing an example configuration of microcomputer 61 in Embodiment 2. Microcomputer 61 functions as a control unit capable of determining the state of vehicle C, controlling upstream semiconductor fuse 62, and controlling the fuse function and relay function of downstream semiconductor fuse 66. Microcomputer 61 includes an input unit 610, an input unit 611, an A / D converter 612, an output unit 613, output units 617-619, a storage unit 614, and a processing unit 615. Input unit 610, A / D converter 612, output unit 613, output units 617-619, storage unit 614, and processing unit 615 are connected to an internal bus 616. A / D converter 612 is connected to input unit 611.

[0097] An identification signal for identifying the type of the load 5 connected to the downstream line 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 onboard device capable of determining the type of the load 5 connected to the downstream line 22.

[0098] Upstream current information (upstream current value) is input from current detection circuit 65 to input unit 611. Upon receiving the upstream current information, input unit 611 outputs the input analog current information to A / D converter 612. Processing unit 615 obtains the digital current information converted by A / D converter 612.

[0099] The output unit 613 outputs a high voltage or a low voltage to the upstream driver circuit 63. The output unit 613 switches the voltage output to the upstream driver circuit 63 to a high voltage or a low voltage according to the instruction of the processing unit 615. The upstream driver circuit 63 switches the upstream semiconductor fuse 62 on or off according to the voltage input from the output unit 613.

[0100] The output units 617 to 619 output a high voltage or a low voltage to each downstream driver circuit 67. The output units 617 to 619 switch the voltage output to the downstream driver circuit 67 to a high voltage or a low voltage according to the instruction of the processing unit 615. Each downstream driver circuit 67 switches each downstream semiconductor fuse 66 on or off according to the voltage input from the output units 617 to 619.

[0101] Storage unit 614 is a non-volatile memory. Storage unit 614 stores a computer program P and a disconnection characteristic table T. The structure of disconnection characteristic table T is the same as that of Embodiment 1. Processing unit 615 includes a processing element, such as a CPU, for executing processing. The processing element of processing unit 615 executes computer program P to determine the state of vehicle C, control upstream semiconductor fuse 62, and control whether to stop (disable) or continue (enable) the fuse and relay functions of downstream semiconductor fuse 66. Computer program P causes the processing element (computer) of processing unit 615 to execute processing. If the current flowing through downstream semiconductor fuse 66 exceeds the rated current value of downstream semiconductor fuse 66 while the fuse function continues to operate (when enabled), processing unit 615 opens downstream semiconductor fuse 42. Furthermore, when the relay function continues to operate (when enabled), the processing unit 615 switches the downstream semiconductor fuse 66 on or off based on whether power needs to be supplied to the load 5 connected to the downstream semiconductor fuse 66 .

[0102] Alternatively, the computer program P may be stored in a storage medium E in a manner readable by the processing elements 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 floppy disk, a magnetic disk, a magneto-optical disk, or a semiconductor memory. An optical disk is a CD-ROM, a DVD-ROM, or a BD. A magnetic disk is, for example, a hard disk. Alternatively, 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.

[0103] Furthermore, the number of processing elements included in the processing unit 615 is not limited to one, and may be two or more. When the processing unit 615 includes a plurality of processing elements, the plurality of processing elements may execute processing in collaboration.

[0104] Figure 10This is a flowchart showing the processing steps of the microcomputer 61 in Embodiment 2. The processing unit 615 of the microcomputer 61 obtains the upstream current value from the current detection circuit 35 (S21). Based on the obtained upstream current value, the processing unit 615 determines whether the vehicle C is in a normal current state (or a low current state) (S22). In S22, the processing unit 615 determines that the vehicle C is in a normal current state if the obtained upstream current value is greater than a predetermined threshold value, and determines that the vehicle C is in a low current state if the obtained upstream current value is less than the predetermined threshold value. If the vehicle C is in a normal current state (S22: Yes), the processing unit 615 sets the tripping characteristics of the upstream semiconductor fuse 62 to the normal characteristics (S23) and returns the process to S21. If the vehicle C is in a low current state (S22: No), the processing unit 315 obtains the load identification signal input to the input unit 610 (S24). Processing unit 315 reads the tripping characteristics table T from storage unit 314 ( S25 ) and sets the tripping characteristics for controlling upstream semiconductor fuse 62 based on the load identification signal and the tripping characteristics table ( S26 ). Processing unit 615 disables the fuse function of downstream semiconductor fuse 66 while continuing to operate the relay function ( S27 ).

[0105] The processing unit 615 obtains the upstream current value from the current detection circuit 65 (S28). Based on the cutoff characteristics and the upstream current value, the processing unit 615 determines whether to cut off the current in the upstream line 21 (S29). In S29, if the upstream current value exceeds the rated current value, the processing unit 615 cuts off the current when the energized time exceeds a predetermined time corresponding to the current value in the characteristic curve. Alternatively, the processing unit 615 may cut off the current when the integrated current value exceeds a predetermined value. Furthermore, if the upstream current value falls below the rated current value before a predetermined time has elapsed, the processing unit 615 determines not to cut off the current. Furthermore, if the upstream current value exceeds the maximum current value defined in the characteristic curve, the processing unit 615 determines to cut off the current instantaneously. If the current in the upstream line 21 is cut off (S29: Yes), the processing unit 615 causes the upstream driver circuit 63 to open the upstream semiconductor fuse 62 (S30), terminating the process. If the current in the upstream line 21 is not cut off (S29: No), the processing unit 615 returns the process to S1.

[0106] (Variation)

[0107] In each of the above embodiments, upstream on-board device 3, downstream on-board device 4, and power distribution on-board device 6 are disposed on the circuit, but the present invention is not limited thereto. Upstream on-board device 3, downstream on-board device 4, and power distribution on-board device 6 may also remotely control upstream semiconductor fuses 32, 62 or downstream semiconductor fuses 42, 66 disposed on circuit 2 from different locations.

[0108] In each of the above-described embodiments, the upstream on-board device 3, the downstream on-board device 4, and the power distribution on-board device 6 determine whether the vehicle C is in the normal current state or the low current state, but the present invention is not limited thereto. The upstream on-board device 3, the downstream on-board device 4, or the power distribution on-board device 6 may also obtain information on the state of the vehicle C determined by another on-board 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.

[0109] In each of the above-described embodiments, the first microcomputer 31 or microcomputer 61 sets the tripping characteristics of the upstream semiconductor fuses 32 or 62 based on the type of load 5 connected to the downstream line 22, referring to the tripping characteristics table T. However, the present invention is not limited thereto. The first microcomputer 31 or microcomputer 61 may also set the tripping characteristics of the upstream semiconductor fuses 32 or 62 to a certain tripping characteristic when the vehicle C is in a low-current state. Furthermore, the first microcomputer 31 or microcomputer 61 may also set the tripping characteristics of the upstream semiconductor fuses 32 or 62 based on the type of load 5 connected to the downstream line 22 that requires power supply during a low-current state when the vehicle C is in a low-current state.

[0110] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The technical features described in the various embodiments can be combined with each other, and the scope of the present invention is intended to include all changes in the claims and the scope equivalent to 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 form. Furthermore, the form of recording claims that reference two or more other claims (multiple dependent claim form) is used in the claims, but it is not limited to this. It is also possible to record multiple dependent claims (multiple reference multiple claims) that reference at least one multiple dependent claim.

[0111] Description of Reference Numerals

[0112] 1 Power supply unit

[0113] 2 Circuits

[0114] 21 Upstream circuit (upstream line)

[0115] 22 Downstream circuit (downstream line)

[0116] 3 Upstream vehicle-mounted devices

[0117] 31 First Microcomputer (Microcomputer)

[0118] 310 Input unit

[0119] 311 Input

[0120] 312 A / D conversion unit

[0121] 313 Output

[0122] 314 Storage Department

[0123] 315 Processing Department

[0124] 316 internal bus

[0125] 32 Upstream semiconductor fuse

[0126] 33 drive circuit

[0127] 34 resistors

[0128] 35 Current detection circuit

[0129] 4 Downstream vehicle-mounted devices

[0130] 41 Second Microcomputer

[0131] 410 Input

[0132] 411 Input

[0133] 412 A / D conversion unit

[0134] 413 Output

[0135] 414 Storage Department

[0136] 415 Processing Department

[0137] 416 Internal Bus

[0138] 42 Downstream semiconductor fuse

[0139] 43 drive circuit

[0140] 44 resistors

[0141] 45 Current detection circuit

[0142] 5 Load

[0143] 6 Power distribution vehicle-mounted device

[0144] 61 Microcomputer

[0145] 610 Input unit

[0146] 611 Input Unit

[0147] 612 A / D conversion unit

[0148] 613 Output

[0149] 614 Storage Department

[0150] 615 Processing Department

[0151] 616 internal bus

[0152] 617 Output

[0153] 618 Output

[0154] 619 Output

[0155] 62 Upstream semiconductor fuse

[0156] 63 Upstream drive circuit

[0157] 64 resistors

[0158] 65 Current detection circuit

[0159] 66 Downstream semiconductor fuse

[0160] 67 Downstream drive circuit

[0161] C Vehicle

[0162] E Storage Media

[0163] P Computer Program

[0164] S Car System

[0165] T Cut-off Characteristics Table

Claims

1. A vehicle-mounted system, mounted on a vehicle, which distributes power supplied from a power supply device to a plurality of loads, wherein: The vehicle state 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 lower than the normal current. The vehicle-mounted system comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream on-board device, comprising an upstream semiconductor fuse disposed on the upstream line; and The downstream vehicle-mounted device includes a downstream semiconductor fuse, which is respectively arranged on the downstream line and has a fuse function and a relay function. The upstream vehicle-mounted device includes a first control unit that controls the connection or disconnection of the upstream semiconductor fuse. The downstream vehicle-mounted device includes a second control unit that controls the connection or disconnection of the downstream semiconductor fuse. When the vehicle is in a low current state, the first control unit sets the cutting characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in a normal current state. The second control unit disables a fuse function of the downstream semiconductor fuse when the vehicle is in a low current state.

2. The vehicle-mounted system according to claim 1, wherein: The first control section sets a cutting characteristic of the upstream semiconductor fuse based on a combination of the loads connected to the downstream line.

3. The vehicle-mounted system according to claim 1 or 2, wherein: The first control unit sets the cutting characteristics of the upstream semiconductor fuse to be shorter than the time before the downstream semiconductor fuse is disconnected due to the current value of the overcurrent in the cutting characteristics of the downstream semiconductor fuse when the fuse function is valid, and the rated current value is higher than the total value of the current values ​​in the downstream line when the vehicle is in a low current state.

4. The vehicle-mounted system according to claim 1 or 2, wherein: The first control unit obtains the current value of the upstream line, When the acquired current of the upstream line flows for a predetermined time or longer in a state exceeding a rated current value in the cutting characteristics of the upstream semiconductor fuse, the upstream semiconductor fuse is switched to be opened.

5. The vehicle-mounted system according to claim 1 or 2, wherein: At least a portion of the plurality of downstream semiconductor fuses are P-channel FETs.

6. A power distribution vehicle-mounted device mounted on a vehicle, which distributes power supplied from a power supply device to a plurality of loads, wherein: The vehicle state 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 lower than the normal current. The power distribution vehicle-mounted device comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream semiconductor fuse, disposed on the upstream line; Downstream semiconductor fuses, respectively provided in the downstream lines, having fuse functions and relay functions; and a control unit that controls the connection or disconnection of the upstream semiconductor fuse and the downstream semiconductor fuse, The control unit stops the fuse function of the downstream semiconductor fuse when the vehicle is in a low current state. The control unit sets the cutting characteristic of the upstream semiconductor fuse to a characteristic lower than that when the vehicle is in a normal current state.

7. The power distribution vehicle-mounted device according to claim 6, wherein: The control section sets a cutting characteristic of the upstream semiconductor fuse based on a combination of the loads connected to the downstream line.

8. The power distribution vehicle-mounted device according to claim 6 or 7, wherein: The control unit obtains the current value of the upstream line, When the acquired current of the upstream line flows for a predetermined time or longer in a state exceeding a rated current value in the cutting characteristics of the upstream semiconductor fuse, the upstream semiconductor fuse is switched to be opened.

9. The power distribution vehicle-mounted device according to claim 6 or 7, wherein: At least a portion of the plurality of downstream semiconductor fuses are P-channel FETs.

10. A control method for a vehicle-mounted system, the vehicle-mounted system being mounted on a vehicle and distributing power supplied from a power supply device to a plurality of loads, wherein: The vehicle state 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 lower than the normal current. The vehicle-mounted system comprises: an upstream line connected to the power supply device; a downstream line branched from the upstream line and connected to the load; an upstream semiconductor fuse, disposed on the upstream line; and Downstream semiconductor fuses are respectively arranged in the downstream lines and have fuse functions and relay functions. The control method sets the cutting characteristic of the upstream semiconductor fuse to a lower characteristic than that when the vehicle is in a normal current state when the vehicle is in a low current state, The control method disables a fuse function of the downstream semiconductor fuse.

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