In-vehicle system, distribution system, and control method

Abstract

The present invention provides an in-vehicle system that can reduce the power required for control when the vehicle is in a low-current state. [Solution] An in-vehicle system according to one embodiment of the present disclosure comprises 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 provided in each of the downstream paths, wherein the upstream in-vehicle device comprises a first control unit that controls the on or off of the upstream semiconductor fuse, and the downstream in-vehicle device comprises a second control unit that controls the on or off of the downstream semiconductor fuse, wherein the first control unit sets the interruption characteristics of the upstream semiconductor fuse to lower characteristics than when the vehicle is in a normal current state when the vehicle is in a low current state, and the second control unit fixes the downstream semiconductor fuse to the ON state when the vehicle is in a low current state.

Description

Technical Field

[0001] This technology relates to an in-vehicle system, a power distribution in-vehicle device, and a control method.

Background Art

[0002] Vehicles are 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 the current path of the 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 terminal. For example, when the semiconductor switch is a FET (Field Effect Transistor), the control terminal is the gate. The resistance value between both ends of the semiconductor switch changes according to the voltage of the control terminal. By adjusting the voltage of the control terminal, 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 of the control terminal, the resistance value between both ends of the semiconductor switch is adjusted to a sufficiently large value, and the semiconductor switch is switched off. By adjusting the voltage of the control terminal, 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

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when a vehicle that is in either a normal current state or a low current state is in the low current state, the power available for the processing of the in-vehicle system of the vehicle is limited, and it is necessary to reduce the required power.

[0006] This disclosure is made in view of the above circumstances and aims 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 mounted on a vehicle that 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 loads is normal current and a low current state in which the current consumption of the loads is less than normal current, and comprises an upstream path connected to the power supply device, a downstream path branching from the upstream path and connected to the loads, an upstream in-vehicle device including an upstream semiconductor fuse provided in the upstream path, and a downstream in-vehicle device provided in each of the downstream paths including a downstream semiconductor fuse having a fuse function and a relay function, wherein the upstream in-vehicle device comprises a first control unit that controls the on or off of the upstream semiconductor fuse, and the downstream in-vehicle device comprises a second control unit that controls the on or off of the downstream semiconductor fuse, wherein the first control unit sets the interruption characteristics of the upstream semiconductor fuse to lower characteristics than when the vehicle is in a normal current state when the vehicle is in a low current state, and the second control unit stops the fuse function of the downstream semiconductor fuse when the vehicle is in a low current state.

[0008] A distribution onboard device according to one embodiment of the present disclosure is a distribution onboard device mounted on a vehicle that 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 loads is normal current and a low current state in which the current consumption of the loads is less than normal current, and comprises an upstream path connected to the power supply device, a downstream path branching from the upstream path and connected to the loads, 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, and a control unit that controls the on or off of the upstream semiconductor fuse and the downstream semiconductor fuse, 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 interruption characteristics of the upstream semiconductor fuse to characteristics lower than 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 mounted on a vehicle that 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 loads is normal current and a low current state in which the current consumption of the loads is less than normal current, and the in-vehicle system comprises an upstream path connected to the power supply device, a downstream path branching from the upstream path and connected to the loads, an upstream semiconductor fuse provided in the upstream path, and a downstream semiconductor fuse provided in each of the downstream paths having a fuse function and a relay function, wherein when the state of the vehicle is a low current state, the interruption characteristics of the upstream semiconductor fuse are set to a lower characteristic than when the vehicle is in a normal current state, and the fuse function of the downstream semiconductor fuse is stopped. [Effects of the Invention]

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

[0011] [Figure 1]This is a block diagram showing an example configuration of an in-vehicle system according to Embodiment 1. [Figure 2] This is a block diagram showing an example configuration of the first microcontroller. [Figure 3] This is an explanatory diagram showing the cutoff characteristics table. [Figure 4] This is an explanatory diagram showing characteristic curves. [Figure 5] This is a block diagram showing an example configuration for the second microcontroller. [Figure 6] This is a flowchart showing the processing procedure of the first microcontroller. [Figure 7] This is a flowchart showing the processing procedure of the second microcontroller. [Figure 8] This is a block diagram showing an example configuration of an in-vehicle system according to Embodiment 2. [Figure 9] This is a block diagram showing an example of the microcontroller configuration according to Embodiment 2. [Figure 10] This flowchart shows the processing procedure of the microcontroller according to Embodiment 2. [Modes for carrying out the invention]

[0012] [Description of Embodiments in this Disclosure] The embodiments of this disclosure will be listed and described first. At least some of the embodiments described below may be combined in any way.

[0013] (1) An in-vehicle system according to one aspect of the present disclosure is an in-vehicle system mounted on a vehicle that distributes power supplied from a power supply to a plurality of loads, wherein the state of the vehicle includes a normal current state in which the current consumption of the loads is normal current and a low current state in which the current consumption of the loads is less than normal current, and comprises an upstream path connected to the power supply, a downstream path branching from the upstream path and connected to the loads, an upstream in-vehicle device including an upstream semiconductor fuse provided in the upstream path, and a downstream in-vehicle device provided in each of the downstream paths including a downstream semiconductor fuse having a fuse function and a relay function, wherein the upstream in-vehicle device comprises a first control unit that controls the on or off of the upstream semiconductor fuse, and the downstream in-vehicle device comprises a second control unit that controls the on or off of the downstream semiconductor fuse, wherein the first control unit sets the interruption characteristics of the upstream semiconductor fuse to lower characteristics than when the vehicle is in a normal current state when the vehicle is in a low current state, and the second control unit stops the fuse function of the downstream semiconductor fuse when the vehicle is in a low current state.

[0014] In this embodiment, power supplied from the power supply unit is supplied to multiple loads via an upstream path and multiple downstream paths branching off from the upstream path. Each downstream path is connected to, for example, one load. Onboard devices are provided in both the upstream path and each downstream path. That is, the onboard devices operate as power supply control devices. The onboard devices include an upstream onboard device provided in the upstream path and a downstream onboard device provided in the downstream path. The upstream onboard device controls the power supply to the downstream path by an upstream semiconductor fuse and a first control unit that controls the upstream semiconductor fuse. Each downstream onboard device controls the power supply to the load by a downstream semiconductor fuse and a second control unit that controls the downstream semiconductor fuse. Note that the downstream onboard devices may also be equipped with mechanical switches, and the second control unit may control the power supply to the load by controlling the mechanical switches. When the vehicle is running, a normal current state occurs in which a normal current flows from the power supply unit to the load, and when the vehicle is stopped, a low current state occurs in which a low current (dark current) flows from the power supply unit to the load. Low current values ​​are lower than normal current values, for example, 10mA to 100mA. Low current values ​​are low values, such as about one-hundredth or one-thousandth of the normal current value. When the vehicle is stopped, the current supplied to the vehicle's load is reduced to a low current to reduce the power supply unit's consumption. The vehicle starts when the power switch or ignition switch is on, for example, 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 a lower characteristic than when the vehicle is in a normal current state. In addition, the second control unit of each downstream on-board device stops (disables) the fuse function of the downstream semiconductor fuse and continues to operate (enables) the relay function. As a result, when the vehicle is in a low current state, the second control unit does not need to switch the downstream semiconductor fuse on or off, 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 by fixing the downstream semiconductor fuse on and stopping the fuse function of the downstream semiconductor fuse by the second control unit.Also, by reducing the value of the cutoff characteristic of the upstream semiconductor fuse, overcurrent can be determined based on the current value in the low-current state, and the downstream path can be accurately protected. Note that the downstream semiconductor fuse does 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 in the on state, and the fuse function is stopped while energization is possible.

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

[0016] In this aspect, the first control unit stores, for example, a table in which the cutoff characteristics set for the combination of loads connected to the downstream path are stored, and sets the cutoff characteristic of the upstream semiconductor fuse based on this table. Note that the first control unit may set the cutoff characteristic of the upstream semiconductor fuse based on the combination of loads that need to be activated when the vehicle is in a low-current state among the loads connected to the downstream path. Thereby, it is possible to accurately protect the downstream path while supplying power to the loads that require power in the low-current state.

[0017] (3) In the vehicle-mounted system according to one aspect of the present disclosure, the first control unit sets the cutoff characteristic of the upstream semiconductor fuse such that the time until the upstream semiconductor fuse is turned off with respect to the current value of the overcurrent is shorter than the time until the downstream semiconductor fuse is turned off with respect to the current value of the overcurrent in the cutoff characteristic of the downstream semiconductor fuse when the fuse function is effective, and the rated current value is higher than the total current value in the downstream path when the vehicle is in a low-current state.

[0018] In this embodiment, the tripping characteristics of the upstream semiconductor fuse are set such that, for example, the time it takes for the upstream semiconductor fuse to turn off with respect to the overcurrent is shorter than that of the downstream semiconductor fuse that has the shortest time to turn off with respect to the overcurrent value in the tripping characteristics when the fuse function is active, among the downstream semiconductor fuses that are turned on by the relay function. Furthermore, the tripping characteristics of the upstream semiconductor fuse are set such that the rated current value is higher than the sum of the current values ​​flowing through the downstream semiconductor fuses that are turned on by the relay function (the current values ​​in the downstream path). That is, if there is only one downstream semiconductor fuse that is turned on by the relay function, the tripping characteristics of the upstream semiconductor fuse are set to a lower value than the tripping characteristics of that downstream semiconductor fuse. This makes it possible to protect the downstream path with higher precision.

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

[0020] In this embodiment, if a current exceeding the rated current value flows through the upstream path for a predetermined time, the downstream path can be protected by switching the upstream semiconductor fuse to the OFF position. The first control unit switches the upstream semiconductor fuse to the OFF position in a shorter time as the current value flowing through the upstream path increases. The interruption characteristics are the characteristics of the upstream semiconductor fuse, including the rated current value for interrupting the current and the time it takes to interrupt the current in the event of an overcurrent exceeding the rated current value. When the interruption characteristics of the upstream semiconductor fuse are high, the rated current value is high and the time it takes to interrupt the overcurrent is long. When the interruption characteristics are lowered, the rated current value becomes lower and the time it takes to interrupt the overcurrent becomes shorter. In other words, the product of the current value and the time it takes to interrupt (integrated current value) goes up or down 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 sum of the smoke emission characteristics of the downstream path or the device characteristics of the load connected to the downstream path. This reduces the possibility of smoke emission in the downstream path or load failure by switching off the upstream semiconductor fuse when an overcurrent flows. Furthermore, if the current flowing through the upstream path is less than or equal to the rated current value, the first control unit does not switch the upstream semiconductor fuse 32 to the off position.

[0021] (5) An in-vehicle system according to one aspect of the present disclosure wherein at least some of the plurality of downstream semiconductor fuses are P-channel type FETs.

[0022] In this embodiment, 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 power to process or apply voltage when the second control unit stops the fuse function of the downstream semiconductor fuse, thereby reducing the power required for processing by the second control unit.

[0023] (6) A distribution onboard device according to one embodiment of the present disclosure is a distribution onboard device mounted on a vehicle that 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 loads is normal current and a low current state in which the current consumption of the loads is less than normal current, and comprises an upstream path connected to the power supply device, a downstream path branching from the upstream path and connected to the loads, 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, and a control unit that controls the on or off of the upstream semiconductor fuse and the downstream semiconductor fuse, 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 interruption characteristics of the upstream semiconductor fuse to characteristics lower than when the vehicle is in a normal current state.

[0024] In this embodiment, power supplied from the power supply unit is supplied to multiple 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 unit and downstream paths branching off from the upstream path and connected to each load. The control unit of the on-board device controls the on / off state of an upstream semiconductor fuse provided in the upstream path and a downstream semiconductor fuse provided in each of the downstream paths. When the vehicle is in a low-current state, the control unit can reduce the power required for processing while accurately protecting the downstream paths by deactivating the fuse function of the downstream semiconductor fuses and setting the interruption characteristics of the upstream semiconductor fuses to a low level.

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

[0026] In this embodiment, the control unit stores, for example, a table containing the tripping characteristics to be set for combinations of loads connected to the downstream path, and sets the tripping characteristics of the upstream semiconductor fuse based on the table. The first control unit may also set the tripping characteristics of the upstream semiconductor fuse based on combinations of loads connected to the downstream path that need to be started when the vehicle is in a low-current state. 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 a distribution onboard device according to one aspect of the present disclosure, the control unit acquires the current value of the upstream path, and if the acquired current of the upstream path exceeds the rated current value in the interruption characteristics of the upstream semiconductor fuse for a predetermined period of time or longer, the control unit switches the upstream semiconductor fuse to the OFF state.

[0028] In this embodiment, if a current exceeding the rated current value flows through the upstream path for a predetermined time, the upstream semiconductor fuse can be switched off to protect the downstream path.

[0029] (9) A distribution onboard device according to one aspect of the present disclosure wherein at least some of the plurality of 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 in the ON position without applying voltage to the downstream semiconductor fuse, thereby reducing the power required 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 mounted on a vehicle that 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 loads is normal current and a low current state in which the current consumption of the loads is less than normal current, and the in-vehicle system comprises an upstream path connected to the power supply device, a downstream path branching from the upstream path and connected to the loads, an upstream semiconductor fuse provided in the upstream path, and a downstream semiconductor fuse provided in each of the downstream paths having a fuse function and a relay function, wherein when the state of the vehicle is a low current state, the interruption characteristics of the upstream semiconductor fuse are set to characteristics lower than when the vehicle is in a normal current state, and the fuse function of the downstream semiconductor fuse is stopped.

[0032] In this embodiment, 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 embodiments of this disclosure] Specific examples of in-vehicle systems according to the embodiments of this disclosure will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims as shown in the claims.

[0034] (Embodiment 1) Figure 1 is a block diagram showing an example configuration of an in-vehicle system according to Embodiment 1. The in-vehicle system S is installed in a vehicle C and includes a power supply unit 1, an electrical circuit 2, an upstream in-vehicle device 3, a plurality of downstream in-vehicle devices 4, and a plurality of loads 5. The electrical circuit 2 includes an upstream electrical circuit (upstream path) 21 connected to the power supply unit and a downstream electrical circuit (downstream path) 22 branching off from the upstream electrical circuit and connected to the loads. The power supply unit 1 is a power source that outputs DC current, such as a battery like a lead-acid battery, hydrogen battery, or secondary battery, or an alternator. The upstream in-vehicle device 3 is connected to the positive terminal of the power supply unit 1 and to the plurality of downstream in-vehicle devices 4. Each downstream in-vehicle device 4 is connected to the upstream in-vehicle device 3 and to one end of the load 5. The upstream in-vehicle device 3 and the downstream in-vehicle devices 4 are, for example, ECUs (Electronic Control Units) that control the current from the power supply unit 1 to the load 5. The negative terminal of the power supply unit 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, the current flowing from the upstream path 21 is branched into three downstream paths 22 and 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, power supply unit 1 supplies power (normal current) to operate load 5, and the vehicle enters a normal current state. When the vehicle stops, power supply unit 1 supplies power at a low current value, which is lower than the normal current, and the vehicle enters a low current state. Load 5, to which low current power is supplied, is a load of equipment that needs to operate even when the vehicle is stopped, such as interior lights or security equipment.

[0036] The upstream onboard device 3 is located in the upstream path 21 and transmits power received from the power supply unit 1 to the downstream onboard device 4. The upstream onboard device 3 includes a first microcomputer (MPC) 31, an upstream semiconductor fuse 32, a drive circuit 33, a resistor 34, and a current detection circuit 35. Details of the first MPC 31 will be described 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 located upstream of the source. In other words, the drain of the upstream semiconductor fuse 32 is connected to the power supply unit 1. The upstream semiconductor fuse 32 may be a P-channel type FET, transistor, thyristor, or IPD (Intelligent Power Device). When a voltage is applied to the gate of the upstream semiconductor fuse 32, the upstream semiconductor fuse 32 turns on and current can flow. When no voltage is applied to the gate of the upstream semiconductor fuse 32, the upstream semiconductor fuse 32 turns 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 an electronic device such as an FPGA, ASIC, or ASSP. The drive circuit 33 may also be a software processing unit such as a microcontroller or DSP. When the drive circuit 33 receives a signal (Hi voltage) from the first microcontroller 31 indicating an instruction to turn on the upstream semiconductor fuse 32, it applies a voltage to the gate of the upstream semiconductor fuse 32, turning on the upstream semiconductor fuse 32. When the drive circuit 33 receives a signal (Low voltage) from the first microcontroller 31 indicating an instruction to turn off the upstream semiconductor fuse 32, it does not apply a voltage to the gate of the upstream semiconductor fuse 32, turning off the upstream semiconductor fuse 32.

[0039] One end of resistor 34 is connected to the source of the upstream semiconductor fuse 32. The other end of resistor 34 is connected to the downstream in-vehicle device 4. Note that resistor 34 may also be provided on the upstream side 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 analog upstream current information indicating the detected upstream current value to the first microcontroller 31.

[0041] The downstream onboard device 4 is located in the downstream path 22 and transmits power received from the upstream onboard device 3 to the load 5. The multiple downstream onboard devices 4 provided in the onboard system S have similar configurations. Therefore, one downstream onboard device 4 will be described below. The downstream onboard device 4 includes a second microcontroller 41, a downstream semiconductor fuse 42, a drive circuit 43, a resistor 44, and a current detection circuit 45. Details of the second microcontroller 41 will be described 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 its source is located upstream of the drain. That is, the source of the downstream semiconductor fuse 42 is connected to the upstream in-vehicle device 3. The downstream semiconductor fuse 42 may also be an F-channel type FET, transistor, thyristor, or IPD. Alternatively, 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 turns off and no current flows. When no voltage is applied to the gate of the downstream semiconductor fuse 42, the downstream semiconductor fuse 42 turns 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 an electronic device such as an FPGA, ASIC, or ASSP. The drive circuit 43 may also be a software processing unit such as a microcontroller or DSP. When the drive circuit 43 receives a signal (low voltage) from the second microcontroller 41 indicating an instruction to turn on the downstream semiconductor fuse 42, or when no signal is output, it applies a voltage to the gate of the downstream semiconductor fuse 42 to turn on the downstream semiconductor fuse 42. When the drive circuit 43 receives a signal (high voltage) from the second microcontroller 41 indicating an instruction to turn off the downstream semiconductor fuse 42, it applies a voltage to the gate of the downstream semiconductor fuse 42 to turn off the downstream semiconductor fuse 42.

[0044] One end of resistor 44 is connected to the drain of the downstream semiconductor fuse 42. The other end of resistor 44 is connected to the load 5. Note that resistor 44 may also be provided upstream of the downstream semiconductor fuse 42. Furthermore, a fuse (mechanical fuse) may be provided between 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 analog downstream current information indicating the detected downstream current value to the second microcontroller 41.

[0046] Figure 2 is a block diagram showing an example configuration of the first microcontroller 31. The first microcontroller 31 operates as a first control unit capable of determining the state of vehicle C and controlling the upstream semiconductor fuse 32. The first microcontroller 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] The input unit 310 receives an identification signal that identifies the type of load 5 connected to the downstream path 22. The identification signal input to the input unit 310 is, for example, a signal output by the load 5, but it may also be a signal output by another on-board device capable of determining the type of 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 upstream current information is input to the input unit 311, it outputs the input analog upstream current information to the A / D conversion unit 312. The processing unit 315 obtains the digital upstream current information converted by the A / D conversion unit 312 from the A / D conversion unit 312.

[0049] The output unit 313 outputs a high 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 high voltage and a low voltage according to the instructions of the processing unit 315. The drive circuit 33 switches the upstream semiconductor fuse 32 on or off according to the voltage input from the output unit 313.

[0050] The memory unit 314 is a non-volatile memory. The memory unit 314 stores the computer program P1 and the interruption characteristic table T. The processing unit 315 has a processing element that executes processing, such as a CPU (Central Processing Unit). The processing element of the processing unit 315 executes the process of determining the state of the vehicle C and the process of controlling the upstream semiconductor fuse 32 by executing the computer program P1. 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 also be stored in the storage medium E1 in a manner that allows the processing elements of the processing unit 315 to read it. In this case, the computer program P1 read from the storage medium E1 by a reading device (not shown) is stored in the storage unit 314. The storage medium E1 is an optical disc, a flexible disc, a magnetic disc, a magneto-optical disc, or a semiconductor memory, etc. Optical discs include CD (Compact Disc)-ROM (Read Only Memory), DVD (Digital Versatile Disc)-ROM, or BD (Blu-ray® Disc), etc. A magnetic disc is, for example, 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.

[0052] Furthermore, the number of processing elements in the processing unit 315 is not limited to one, but may be two or more. If the processing unit 315 has multiple processing elements, the multiple processing elements may cooperate to perform processing.

[0053] Figure 3 is an explanatory diagram showing the interruption characteristics table T. Figure 4 is an explanatory diagram showing the characteristic curve. The management items of the interruption characteristics table T include, for example, a connected load field and a characteristic curve field. The connected load field stores combinations of the types of loads 5 connected to the downstream path 22. In this embodiment, a configuration in which there are four types of loads 5, A, B, C, and D, is described. Note that the types of loads 5 may correspond to the types of equipment, such as interior lights, on which the loads 5 are installed. Also, although the example shown in Figure 3 shows a configuration in which different types of loads 5 are connected to all three downstream paths 22, it is not limited to this. Loads 5 may be connected to only 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 characteristic curves that represent the tripping characteristics of the upstream semiconductor fuse 32, selected for combinations of load types 5 connected to the downstream path 22 under low current conditions. 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 two-dimensional array data format. The processing unit 315 sets the tripping characteristics by selecting a characteristic curve stored in the tripping characteristics table T based on the combination of load types 5.

[0055] The interruption characteristic is the characteristic of the upstream semiconductor fuse 32, including the current value at which the processing unit 315 turns off the upstream semiconductor fuse 32 to interrupt the current, and the energizing time until the current is interrupted in the event of a current exceeding the rated current value (overcurrent). When the interruption characteristic of the upstream semiconductor fuse is high, the rated current value is high, and the energizing time until the current is interrupted in the event of an overcurrent is long. When the interruption characteristic is lowered, the rated current value becomes lower, and the energizing time until the current is interrupted in the event of an overcurrent becomes shorter. In other words, the product of the current value and the energizing time until interruption (integrated current value) goes up or down depending on the level of the interruption characteristic. The processing unit 315 switches the upstream semiconductor fuse 32 off when the upstream current value is above the minimum current value defined in the characteristic curve, i.e., when it exceeds the rated current value, and the energizing time exceeds a predetermined time. The rated current value also indicates the maximum current value at which the upstream semiconductor fuse 32 will not be turned off even if current flows for a long time. The rated current value goes up or down depending on the level of the interruption characteristic.

[0056] The characteristic curve represents the interruption characteristics of the upstream semiconductor fuse 32, that is, the energizing time until the processing unit 315 switches the upstream semiconductor fuse 32 off in relation to the current value flowing through the upstream path 21. The graph shown in Figure 4 shows the characteristic curves of the upstream semiconductor fuse 32 in normal current conditions and low current conditions, with the current value flowing through the upstream path 21 (upstream current value) on the vertical axis and the energizing time on the horizontal axis.

[0057] As shown in Figure 4, when the current is low, the processing unit 315 sets the tripping characteristics of the upstream semiconductor fuse 32 to be lower than the tripping characteristics (normal characteristics) when the current is normal. Note that the tripping characteristics of each upstream semiconductor fuse 32 when the current is low are offset to be lower than, for example, the sum of the device characteristics of each load 5 connected to the downstream path 22 and powered by the relay function of the downstream semiconductor fuse 42. In other words, when the vehicle is in a low current state, the tripping characteristics of the upstream semiconductor fuse 32 are set so that the time it takes for the upstream semiconductor fuse 32 to be turned off for an overcurrent is shorter than the time it takes for the upstream semiconductor fuse 32 to be turned off for an overcurrent for an overcurrent for a downstream semiconductor fuse 42 that is turned on by the relay function and has the shortest time to be turned off for an overcurrent for an overcurrent for a given

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

[0059] In this embodiment, the processing unit 315 sets the interruption characteristics of the upstream semiconductor fuse 32 based on an interruption characteristic table T which stores characteristic curves selected for combinations of load types 5 connected to the downstream path 22, but is not limited to this. The storage unit 314 stores a table which stores device characteristics for each type of load 5, 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 this table. The offset value may be a predetermined coefficient less than 1, such as 0.8, which is multiplied by the sum of the device characteristics of the loads 5. Alternatively, the processing unit 315 may set the interruption characteristics of the upstream semiconductor fuse 32 by shifting the sum of the smoke characteristics of the downstream path 22 using an offset value.

[0060] Figure 5 is a block diagram showing an example configuration of the second microcontroller 41. The second microcontroller 41 is used in the vehicle It operates as a second control unit capable of determining the state of both Cs and controlling the fuse function and relay function of the downstream semiconductor fuse 42. The second microcontroller 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 downstream current information is input to the input unit, it outputs the input analog downstream current information to the A / D conversion unit 412. The processing unit 415 obtains the digital downstream current information converted by the A / D conversion unit 412 from the A / D conversion unit 412.

[0062] The output unit 413 outputs a high voltage or a low voltage to the drive circuit 43. The output unit 413 switches the voltage output to the drive circuit 43 between a high voltage and a low voltage according to the instructions of the processing unit 415. The drive circuit 43 switches the downstream semiconductor fuse 42 on or off according to the voltage input from the output unit 413.

[0063] The memory unit 414 is a non-volatile memory. The memory unit 414 stores a computer program P. The processing unit 415 has a processing element, such as a CPU, that executes processing. The processing element of the processing unit 415 executes the processing to determine the state of the vehicle C, and the processing to control the stopping (disabling) or continuing operation (enabling) of the fuse function and relay function of the downstream semiconductor fuse 42 by executing the computer program P. The computer program P is used to cause the processing element (computer) of the processing unit 415 to execute processing. When the fuse function is continuously operating (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 is continuously operating (enabled), the processing unit 415 switches the downstream semiconductor fuse 42 on or off based on whether or not power supply to the load 5 connected to the downstream semiconductor fuse 42 is required.

[0064] The computer program P may be stored in a storage medium E in a manner that allows the processing elements of the processing unit 415 to read it. 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 flexible disc, a magnetic disc, a magneto-optical disc, or a semiconductor memory, etc. Optical discs include CD-ROMs, DVD-ROMs, or BDs. Magnetic discs include, for example, hard disks. 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.

[0065] Figure 6 is a flowchart showing the processing procedure of the first microcontroller 31. Initially, the upstream semiconductor fuse 32 is turned on by the first microcontroller 31. The processing unit 315 of the first microcontroller 31 acquires the upstream current value from the current detection circuit 35 (S1). Based on the acquired upstream current value, the processing unit 315 determines whether vehicle C is in a normal current state (low current state) or not (S2). In S2, if the acquired upstream current value is above a predetermined threshold, the processing unit 315 determines that vehicle C is in a normal current state, and if it is below the predetermined threshold, it determines that vehicle C is in a low current state. If 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 normal characteristics (S3) and returns the process to S1. If vehicle C is in a low current state (S2: NO), the processing unit 315 acquires the load identification signal input to the input unit 310 (S4). The processing unit 315 reads the interruption characteristic table T from the storage unit 314 (S5), and sets the interruption characteristics for controlling the upstream semiconductor fuse 32 based on the load identification signal and the interruption characteristic table (S6).

[0066] The processing unit 315 obtains the upstream current value from the current detection circuit 35 (S7). Based on the interruption characteristics and the upstream current value, the processing unit 315 determines whether or not to interrupt the current in the upstream path 21 (S8). In S8, if the upstream current value exceeds the rated current value, the processing unit 315 interrupts the current when the energizing time 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 integrated current value exceeds a predetermined value. If the upstream current value falls below the rated current value before the predetermined time has elapsed, the processing unit 315 determines not to interrupt the current. Furthermore, if the upstream current value exceeds the maximum current value defined in the characteristic curve, the processing unit 315 determines to interrupt the current instantaneously. If the current in the upstream path 21 is interrupted (S8: YES), the processing unit 315 turns off the upstream semiconductor fuse 32 in the drive circuit 33 (S9) and terminates the process. If the current in the upstream path 21 is not interrupted (S8:NO), the processing unit 315 returns the process to S1.

[0067] Figure 7 is a flowchart showing the processing procedure of the second microcontroller 41. The processing unit 415 of the second microcontroller obtains the downstream current value from the current detection circuit 45 (S11). Based on the downstream current value, the processing unit 415 determines whether or not vehicle C is in a normal current state (S12). If vehicle C is in a normal current state (S12: YES), the processing unit 415 returns the process to S11. If 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 the relay function (S13), and terminates the process.

[0068] With the above configuration and processing, the second microcontroller 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 makes it possible to protect the downstream path 22 while reducing the power required for processing.

[0069] (Embodiment 2) In Embodiment 1, the electrical circuit 2 branches from the upstream path 21 to the downstream path 22 between multiple devices, but it may also branch within a single device. Below, the differences between Embodiment 2 and Embodiment 1 will be described. Except for the configuration described later, all other configurations are common to Embodiment 1. For this reason, components common to Embodiment 1 are given the same reference numerals as in Embodiment 1 and their descriptions are omitted.

[0070] Figure 8 is a block diagram showing an example configuration of an in-vehicle system S according to Embodiment 2. The in-vehicle system S according to Embodiment 2 comprises a power supply unit 1, an electrical circuit 2, a distribution unit 6, and a plurality of loads 5. The distribution unit 6 is connected to the positive terminal of the power supply unit 1 and one end of the plurality of loads 5. The distribution unit 6 is, for example, an ECU that controls the current from the power supply unit 1 to the loads 5. The distribution unit 6 comprises an electrical circuit 2 through which current flows from the power supply unit 1 to the loads 5. The electrical circuit 2 includes an upstream electrical circuit (upstream path) 21 connected to the power supply unit and a downstream electrical circuit (downstream path) 22 that branches off from the upstream path 21 and connects to the loads. In this embodiment, the downstream path 22 is branched into three.

[0071] The distribution device 6 includes a microcontroller 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 microcontroller 61 will be described later.

[0072] The upstream semiconductor fuse 62 is, for example, an N-channel FET, and is provided in the upstream path 21 such that its drain is located upstream of the source. That is, the drain of the upstream semiconductor fuse 62 is connected to the power supply unit 1. The upstream semiconductor fuse 62 may also be a P-channel FET, transistor, thyristor, or IPD. When a voltage is applied to the gate of the upstream semiconductor fuse 62, the fuse turns on and current can flow. When no voltage is applied to the gate of the upstream semiconductor fuse 62, the fuse turns off and no current flows.

[0073] The upstream drive 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 drive circuit 63 is an electronic device such as an FPGA, ASIC, or ASSP. Alternatively, the upstream drive circuit 63 may be a software processing unit such as a microcontroller or DSP. When the upstream drive circuit 63 receives a signal (Hi voltage) from the microcontroller 61 indicating an instruction to turn on the upstream semiconductor fuse 62, it applies a voltage to the gate of the upstream semiconductor fuse 62, turning the upstream semiconductor fuse 62 on. When the upstream drive circuit 63 receives a signal (Low voltage) from the microcontroller 61 indicating an instruction to turn off the upstream semiconductor fuse 62, it does not apply a voltage to the gate of the upstream semiconductor fuse 62, turning the upstream semiconductor fuse 62 off.

[0074] One end of resistor 64 is connected to the source of the upstream semiconductor fuse 62. The other end of resistor 64 is connected to the downstream semiconductor fuse 66. Note that resistor 64 may also 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 analog current information indicating the detected upstream current value to the microcontroller 61.

[0076] A 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 its source is located upstream of the drain. That is, the source of the downstream semiconductor fuse 66 is connected to the resistor 64. The downstream semiconductor fuse 66 may also be an F-channel type FET, transistor, thyristor, or IPD. Alternatively, 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 turns off and no current flows. When no voltage is applied to the gate of the downstream semiconductor fuse 66, the downstream semiconductor fuse 66 turns on and current can flow.

[0077] A 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 the voltage applied to the gate of the downstream semiconductor fuse 66. The downstream drive circuit 67 is an electronic device such as an FPGA, ASIC, or ASSP. Alternatively, the downstream drive circuit 67 may be a software processing unit such as a microcontroller or DSP. When the downstream drive circuit 67 receives a signal (low voltage) from the second microcontroller 41 indicating an instruction to turn on the downstream semiconductor fuse 66, or when no signal is output, it applies a voltage to the gate of the downstream semiconductor fuse 66 to turn on the downstream semiconductor fuse 66. When the downstream drive circuit 67 receives a signal (high voltage) from the microcontroller 61 indicating an instruction to turn off the downstream semiconductor fuse 66, it applies a voltage to the gate of the downstream semiconductor fuse 66 to turn off the downstream semiconductor fuse 66.

[0078] Figure 9 is a block diagram showing an example configuration of a microcontroller 61 according to Embodiment 2. The microcontroller 61 operates as a control unit capable of determining the state of vehicle C, controlling the upstream semiconductor fuse 62, and controlling the fuse function and relay function of the downstream semiconductor fuse 66. It comprises an input unit 610, an input unit 611, an A / D conversion unit 612, an output unit 613, output units 617-619, 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 617-619, 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] The input unit 610 receives an identification signal that identifies the type of load 5 connected to the downstream path 22. The identification signal input to the input unit 610 is, for example, a signal output by the load 5, but it may also be a signal output by another on-board device capable of determining the type of 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 upstream current information is input to the input unit 611, it outputs the input analog current information to the A / D conversion unit 612. The processing unit 615 obtains the digital current information converted by the A / D conversion unit 612 from the A / D conversion unit 612.

[0081] The output unit 613 outputs a high 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 high voltage and a low voltage according to the instructions of the processing unit 615. The upstream drive circuit 63 switches the upstream semiconductor fuse 62 on or off according to the voltage input from the output unit 613.

[0082] Output units 617-619 output either a high voltage or a low voltage to each downstream drive circuit 67. Output units 617-619 switch the voltage output to the downstream drive circuit 67 between a high voltage and a low voltage according to the instructions of the processing unit 615. Each downstream drive circuit 67 switches each downstream semiconductor fuse 66 on or off according to the voltage input from output units 617-619.

[0083] The memory unit 614 is a non-volatile memory. The memory unit 614 stores a computer program P and a circuit breaker characteristic table T. The configuration of the circuit breaker characteristic table T is the same as in Embodiment 1. The processing unit 615 has a processing element, such as a CPU, that performs processing. The processing element of the processing unit 615 executes the following processes by executing the computer program P: a process to determine the state of the vehicle C, a process to control the upstream semiconductor fuse 62, and a process to control the stopping (disabling) or continuing operation (enabling) 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 perform processing. When the fuse function is continuously operating (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. Also, when the relay function is continuously operating (enabled), the processing unit 615 switches the downstream semiconductor fuse 66 on or off based on whether or not power supply to the load 5 connected to the downstream semiconductor fuse 66 is required.

[0084] The computer program P may be stored in a storage medium E in a manner that allows the processing elements of the processing unit 615 to read it. 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, or a semiconductor memory, etc. Optical disks include CD-ROMs, DVD-ROMs, or BDs. Magnetic disks include, for example, hard disks. 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.

[0085] Furthermore, the number of processing elements in the processing unit 615 is not limited to one, but may be two or more. If the processing unit 615 has multiple processing elements, the multiple processing elements may cooperate to perform processing.

[0086] Figure 10 is a flowchart showing the processing procedure of the microcontroller 61 according to Embodiment 2. The processing unit 615 of the microcontroller 61 acquires the upstream current value from the current detection circuit 35 (S21). Based on the acquired upstream current value, the processing unit 615 determines whether or not vehicle C is in a normal current state (low current state) (S22). In S22, if the acquired upstream current value is above a predetermined threshold, the processing unit 615 determines that vehicle C is in a normal current state, and if it is below the predetermined threshold, it determines that vehicle C is in a low current state. If vehicle C is in a normal current state (S22: YES), the processing unit 615 sets the interruption characteristics of the upstream semiconductor fuse 62 to normal characteristics (S23) and returns the process to S21. If vehicle C is in a low current state (S22: NO), the processing unit 315 acquires the load identification signal input to the input unit 610 (S24). The processing unit 315 reads the interruption characteristic table T from the storage unit 314 (S25), and sets the interruption characteristics 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 continues the relay function (S27).

[0087] The processing unit 615 obtains the upstream current value from the current detection circuit 65 (S28). Based on the interruption characteristics and the upstream current value, the processing unit 615 determines whether or not to interrupt the current in the upstream path 21 (S29). In S29, if the upstream current value exceeds the rated current value, the processing unit 615 interrupts the current when the energizing time 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 integrated current value exceeds a predetermined value. If the upstream current value falls below the rated current value before the predetermined time has elapsed, the processing unit 615 determines not to interrupt the current. Furthermore, if the upstream current value exceeds the maximum current value defined in the characteristic curve, the processing unit 615 determines to interrupt the current instantaneously. If the current in the upstream path 21 is interrupted (S29: YES), the processing unit 615 turns off the upstream semiconductor fuse 62 in the upstream drive circuit 63 (S30) and terminates the process. If the current in the upstream path 21 is not interrupted (S29:NO), the processing unit 615 returns the process to S1.

[0088] (modified version) In each of the embodiments described above, the upstream onboard device 3, the downstream onboard device 4, and the distribution onboard device 6 are installed on the electrical circuit, but are not limited to this. The upstream onboard device 3, the downstream onboard device 4, and the distribution onboard device 6 may be configured to remotely control the upstream semiconductor fuses 32, 62 or the downstream semiconductor fuses 42, 66 installed on the electrical circuit 2 from a separate location.

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

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

[0091] The embodiments disclosed herein should be considered in all respects as illustrative 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 claims and scope equivalent to the claims. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. In addition, the claims use a multi-claim format in which claims refer to two or more other claims (multi-claim format), but are not limited to this. They may also be described using a multi-claim format in which at least one multi-claim refers to another multi-claim (multi-multi-claim format). [Explanation of Symbols]

[0092] 1 Power supply 2 electric circuit 21 Upstream power lines (upstream routes) 22 Downstream power lines (downstream routes) 3 Upstream onboard equipment 31. First Microcomputer (Microcomputer) 310 Input section 311 Input Section 312 A / D Conversion Unit 313 Output section 314 Storage section 315 Processing Unit 316 Internal Bus 32 Upstream Semiconductor Fuses 33 Drive Circuit 34 Resistors 35 Current detection circuit 4 Downstream onboard equipment 41 Second Microcontroller 410 Input section 411 Input section 412 A / D Conversion Unit 413 Output section 414 Storage section 415 Processing Unit 416 Internal Bus 42 Downstream Semiconductor Fuses 43 Drive Circuit 44 resistors 45 Current detection circuit 5 load 6 Distribution onboard equipment 61 Microcontroller 610 Input section 611 Input section 612 A / D Conversion Unit 613 Output section 614 Storage section 615 Processing Unit 616 Internal Bus 617 Output section 618 Output section 619 Output section 62 Upstream Semiconductor Fuses 63 Upstream drive circuit 64 resistors 65 Current detection circuit 66 Downstream Semiconductor Fuses 67 Downstream drive circuit C Vehicle E Storage medium P Computer Program S In-vehicle system T Blocking Characteristics Table

Claims

1. An in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply unit to multiple loads, The state of the vehicle includes a normal current state in which the load's current consumption is normal current, and a low current state in which the load's current consumption is less than normal current. The upstream path connected to the aforementioned power supply device, A downstream route that branches off from the upstream route and connects to the load, An upstream in-vehicle device including an upstream semiconductor fuse provided in the upstream path, A downstream on-board device is provided in each of the aforementioned downstream paths, and includes a downstream semiconductor fuse having a fuse function and a relay function. Equipped with, The aforementioned upstream vehicle-mounted device is A first control unit that controls the on or off state of the upstream semiconductor fuse, Equipped with, The downstream onboard device is, A second control unit that controls the on or off state of the downstream semiconductor fuse, Equipped with, The first control unit, when the vehicle is in a low current state, sets the interruption characteristics of the upstream semiconductor fuse to be lower than those when the vehicle is in a normal current state. The second control unit disables the 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 the tripping characteristics of the upstream semiconductor fuse based on the combination of 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 the time it takes to turn off the upstream semiconductor fuse for an overcurrent is shorter than the time it takes to turn off the downstream semiconductor fuse for an overcurrent in the interruption characteristics of the downstream semiconductor fuse when the fuse function is active, 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. The in-vehicle system according to claim 1 or 2.

4. The first control unit is, Obtain the current value of the upstream path, If the acquired current in the upstream path exceeds the rated current value in the interruption characteristics of the upstream semiconductor fuse for a predetermined period of time or longer, the upstream semiconductor fuse is switched off. The in-vehicle system according to claim 1 or 2.

5. At least some of the multiple downstream semiconductor fuses are P-channel type FETs. The in-vehicle system according to claim 1 or 2.

6. A distribution device mounted on a vehicle that distributes power supplied from a power supply unit to multiple loads, The state of the vehicle includes a normal current state in which the load's current consumption is normal current, and a low current state in which the load's current consumption is less than normal current. The upstream path connected to the aforementioned power supply device, A downstream route that branches off from the upstream route and connects to the load, An upstream semiconductor fuse provided in the upstream path, A downstream semiconductor fuse having a fuse function and a relay function is provided in each of the aforementioned downstream paths, A control unit that controls the on or off of the upstream semiconductor fuse and the downstream semiconductor fuse. Equipped with, The control unit, If the vehicle is in a low current state, the fuse function of the downstream semiconductor fuse is deactivated. The interruption characteristics of the upstream semiconductor fuse are set to be lower than those when the vehicle is in a normal current state. Distribution onboard equipment.

7. The control unit sets the tripping characteristics of the upstream semiconductor fuse based on the combination of loads connected to the downstream path. The train distribution device according to claim 6.

8. The control unit, Obtain the current value of the upstream path, If the acquired current in the upstream path exceeds the rated current value in the interruption characteristics of the upstream semiconductor fuse for a predetermined period of time or longer, the upstream semiconductor fuse is switched off. The train distribution device according to claim 6 or 7.

9. At least some of the multiple downstream semiconductor fuses are P-channel type FETs. The train distribution device according to claim 6 or 7.

10. A control method for an in-vehicle system that is mounted on a vehicle and distributes power supplied from a power supply unit to multiple loads, The state of the vehicle includes a normal current state in which the load's current consumption is normal current, and a low current state in which the load's current consumption is less than normal current. The aforementioned in-vehicle system is The upstream path connected to the aforementioned power supply device, A downstream route that branches off from the upstream route and connects to the load, An upstream semiconductor fuse provided in the upstream path, A downstream semiconductor fuse having a fuse function and a relay function is provided in each of the aforementioned downstream paths. Equipped with, When the vehicle is in a low-current state, the interruption characteristics of the upstream semiconductor fuse are set to be lower than those when the vehicle is in a normal current state. The fuse function of the downstream semiconductor fuse is disabled. Control method.

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