On-vehicle power distribution device

Abstract

To provide on-vehicle power distribution devices capable of continuing power supply at the time of a power main line failure and improving recovery speed in an on-vehicle power net system in which the on-vehicle power distribution devices are mutually connected.SOLUTION: An on-vehicle power distribution device 1 comprises: a first power distribution device 1a for distributing power from a first power source main line 3a to loads; a second power distribution device 1b for distributing power from a second power source main line 3b to loads; and a connection main line 5 that connects the first power distribution device 1a and the second power distribution device 1b. The first power distribution device 1a includes a semiconductor switch where a MOSFET (M1) and a MOSFET (M2) are serially connected in mutually opposed directions. The semiconductor switch is provided between the first power source main line 3a and the connection main line 5, makes the MOSFET (M1) become into an ON state and makes the MOSFET (M2) into an OFF state, waits in a state of applying voltage to the connection main line 5 via a body diode of the MOSFET (M2), and turns on the MOSFET (M2) depending on a current rise of the connection main line 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an on-board power distribution device in a vehicle power supply system. [Background technology]

[0002] In recent years, advances in the electrification and autonomous driving of automobiles have led to an increase in the number of onboard devices, such as sensors and actuators. This has led to demands for a reduction in the number of wire harnesses used to supply power to each device, as well as for higher reliability and lower loss in onboard power net systems. However, conventional 12V onboard power net systems often use a method in which a relay box or fuse box is installed near the battery, from which power cables are individually connected to onboard devices installed in various locations throughout the vehicle. This conventional method of supplying power to onboard devices poses the problem of requiring a huge number of wire harnesses as the number of onboard devices to be powered increases and the need for redundant power supply paths for higher reliability increases.

[0003] To address this issue, a system has been proposed in which a vehicle is divided into multiple zones and a power distribution device that distributes power to onboard devices is installed in each zone. By installing a power distribution device in each zone, power is distributed near each onboard device, thereby shortening the length of each individual wiring harness. In addition, by interconnecting the power distribution devices installed in each zone with a power trunk line, if a power trunk line fails, other power trunk lines can be used as an alternative route to continue power supply.

[0004] The following prior art is included as background art in this technical field. In Patent Document 1, the output of an onboard battery is branched into multiple power lines at a fuse unit or other location. A first power line branching from the fuse unit is connected to onboard equipment via a front-stage power distribution device installed downstream. A second power line branching from the fuse unit is connected to onboard equipment via the front-stage power distribution device and a rear-stage power distribution device. The front-stage power distribution device includes an inter-path connection switch that connects the first power line and the second power line, and a central processing unit as a control unit that controls the opening and closing of the switch. If the first power line or the second power line is disconnected, the circuit of the inter-path switch is closed, transmitting power via multiple paths. By using multiple paths simultaneously, the required power can be supplied even if the diameter of each power line is reduced. This enables the weight of the wiring material that constitutes the power supply paths to be reduced, and ensures redundant paths that can respond to disconnections and other issues without providing multiple power supply sources. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-019095 Summary of the Invention [Problem to be solved by the invention]

[0006] In the aforementioned Patent Document 1, power MOSFETs are used as switches for connecting and disconnecting power paths. These switches are controlled by a communication network based on a CAN (Control Area Network). However, when communication is used to issue instructions to open or close the switches, a delay occurs due to communication delays between the detection of a power line fault and the switching of the switch, resulting in a problem of power supply being cut off during that time.

[0007] Furthermore, Patent Document 1 discloses a device equipped with a reverse current prevention diode to control the direction of current flow in the power line. The diode generates a voltage drop due to the forward voltage, which reduces the power supply voltage. In particular, in a power supply mains line through which a large current flows, the power loss increases due to the product of this voltage drop and the current. This requires the heat generated by the power loss of the diode to be dissipated, which poses the problem of increasing the size of heat dissipation components such as heat sinks.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an on-board power distribution device that can instantly supply current when a demand for power arises from on-board equipment connected to the power main line when switching paths due to a failure in the power main line, can reduce voltage drop and power loss due to diodes, can reduce power loss due to switches in the power main line through which a large current flows, and can miniaturize heat dissipation components. [Means for solving the problem]

[0009] In order to solve the above problems, one aspect of the present invention provides an on-board power distribution device configured as follows: The on-board power distribution device includes a first power distribution device that distributes power from a first power supply trunk to a load, a second power distribution device that distributes power from a second power supply trunk to the load, and a connection trunk that connects the first power distribution device and the second power distribution device, wherein the first power distribution device includes a semiconductor switch having a first semiconductor transistor and a second semiconductor transistor connected in series in opposite directions, the semiconductor switch is provided between the first power supply trunk and the connection trunk, and stands by with the first semiconductor transistor in an ON state and the second semiconductor transistor in an OFF state, with a voltage applied to the connection trunk via the body diode of the second semiconductor transistor, and turns on the second semiconductor transistor in response to a rise in current in the connection trunk. [Effects of the Invention]

[0010] According to one aspect of the present invention, when switching paths due to a power trunk line failure, a semiconductor switch composed of a semiconductor transistor such as a MOSFET is set in a diode state and placed on standby, thereby enabling current to be supplied immediately when a power demand arises from a load connected to the connection trunk line. Furthermore, by detecting the occurrence of a current demand from a load connected to the connection trunk line and turning on the semiconductor transistor such as the MOSFET, voltage drop and power loss due to the semiconductor transistor can be reduced. Furthermore, these effects can reduce power loss due to switches in the power trunk line through which a large current flows, and allow for the miniaturization of heat dissipation components.

[0011] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an example of the configuration of an in-vehicle power distribution device according to a first embodiment of the present invention. [Figure 2] 3 is a diagram illustrating an example of normal operation of the in-vehicle power distribution device according to the first embodiment of the present invention. FIG. [Figure 3] 3 is a diagram illustrating an example of operation of the in-vehicle power distribution device according to the first embodiment of the present invention when a line is broken. FIG. [Figure 4] 3 is a diagram illustrating an example of an operation at the time of restoration of the in-vehicle power distribution device according to the first embodiment of the present invention. FIG. [Figure 5] 4 is a time chart showing an example of operation of the in-vehicle power distribution device according to the first embodiment of the present invention during normal operation, during disconnection, and during recovery. [Figure 6] FIG. 10 is a diagram illustrating an example of the configuration of an in-vehicle power distribution device according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a diagram illustrating an example of the configuration of an in-vehicle power distribution device according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a diagram illustrating an example of the configuration of an in-vehicle power distribution device according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing a modified example of an on-board power distribution device according to the fourth embodiment of the present invention. [Figure 10]FIG. 10 is a diagram illustrating an example of the configuration of an in-vehicle power distribution device according to a fifth embodiment of the present invention. [Figure 11] FIG. 10 is a diagram illustrating an example of the configuration of an in-vehicle power distribution device according to a sixth embodiment of the present invention. [Figure 12A] FIG. 10 is a diagram showing a first modified example of the configuration of MOSFETs (M1, M2). [Figure 12B] FIG. 10 is a diagram showing a second modified example of the configuration of MOSFETs (M1, M2). [Figure 12C] FIG. 10 is a diagram showing a third modified example of the configuration of MOSFETs (M1, M2). [Figure 13A] FIG. 10 is a diagram illustrating a first modified example of a system configuration. [Figure 13B] FIG. 10 is a diagram illustrating a second modified example of the system configuration. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification and drawings, identical components or components having substantially the same functions will be designated by the same reference numerals, and redundant description will be omitted. Furthermore, when there are multiple components having the same or similar functions, they may be designated by the same reference numerals but with different suffixes (alphabetical letters).

[0014] (First Example) 1 is a diagram showing a configuration example of a first embodiment of an on-board power distribution device suitable for applying the present invention. The on-board power distribution device 1 of this embodiment is composed of multiple power distribution devices (first power distribution device 1a, second power distribution device 1b) mounted on a vehicle and a power supply trunk line (hereinafter referred to as connection trunk line 5) connecting them to each other. Each power distribution device (first power distribution device 1a, second power distribution device 1b) distributes power from a power source (hereinafter referred to as power source 2a, 2b) mounted on the vehicle to one or more on-board devices (hereinafter referred to as loads 7a, 7b) such as sensors and actuators mounted on the vehicle.

[0015] A first power distribution device 1a mounted on a vehicle receives power from a power source 2a mounted on the vehicle via a power supply trunk 3a. The power source 2a may be an in-vehicle lead battery or a DC / DC converter. The first power distribution device 1a includes a semiconductor switch in which two MOSFETs (M1, M2) are connected in series with their sources and drains reversed. In this embodiment, the cathode terminal of the body diode of the MOSFET (M1) is connected to the power supply trunk 3a, and the anode terminal of the body diode of the MOSFET (M2) is connected to the anode terminal of the MOSFET (M1). The cathode terminal of the MOSFET (M2) is connected to a connection trunk 5 provided outside the first power distribution device 1a via a current sensor 4a. The current sensor 4a is a current detector that detects the current flowing through the connection trunk 5 and can obtain a signal corresponding to the current value of the connection trunk 5 by detecting the voltage across a shunt resistor.

[0016] In the first power distribution device 1a, a semiconductor switch S1 is provided branching off the current path between the power supply trunk 3a and the MOSFET (M1). Furthermore, a semiconductor switch S2 is provided branching off the current path between the MOSFET (M2) and the current sensor 4a. The semiconductor switches S1 and S2 are connected to a load power line 6a. The load power line 6a is connected to a plurality of loads 7a, such as sensors and actuators mounted on the vehicle. In other words, the switch configuration on the load 7a side of the first power distribution device 1a is such that the load power line 6a is connected via the semiconductor switch S1 branching off from between the power supply trunk 3a and the MOSFET (M1), and the load power line 6a is connected via the semiconductor switch S2 branching off from between the MOSFET (M2) and the current sensor 4a (connection trunk 5). The load 7a connected to the first power distribution device 1a is connected to the load power line 6a and is supplied with power via the load power line 6a.

[0017] The MOSFETs (M1, M2) of the first power distribution device 1a are driven by a gate driver (GD) that generates a gate voltage. The device also includes a voltage sensor 8a that monitors the voltage of the power supply trunk line 3a. The voltage sensor 8a is used to detect faults such as disconnections in the power supply trunk line 3a. For example, if the output value of the voltage sensor 8a falls below a predetermined value, it is determined that the power supply from the power supply trunk line 3a has been cut off. The device also includes a controller 9a that controls the ON / OFF states of the MOSFETs (M1, M2) and the semiconductor switches S1, S2. The controller 9a acquires current information from the current sensor 4a and controls the ON / OFF states of the MOSFETs (M1, M2). The controller 9a also controls the ON / OFF states of the semiconductor switches S1, S2 based on the voltage information from the voltage sensor 8a. The controller 9a can be a microcomputer, a DSP, an FPGA, or the like.

[0018] In this embodiment, the second power distribution device 1b also has the same configuration as the first power distribution device 1a (MOSFETs (M3, M4), a current sensor 4b, semiconductor switches S3, S4, a load power line 6b, a load 7b, a voltage sensor 8b, and a controller 9b). The second power distribution device 1b is supplied with power from a power source 2b mounted on a vehicle via a power supply trunk line 3b. An in-vehicle lead battery or a DC / DC converter can be used as the power source 2b. The first power distribution device 1a and the second power distribution device 1b are connected by a connection trunk line 5. The connection trunk line 5 allows the first power distribution device 1a and the second power distribution device 1b to supply power to each other. This makes it possible to select the power path to be supplied to the first power distribution device 1a and the second power distribution device 1b. In other words, by switching the MOSFETs (M1, M2) and semiconductor switches S1 and S2 provided in the first power distribution device 1a, and the MOSFETs (M3, M4) and semiconductor switches S3 and S4 provided in the second power distribution device 1b, the current paths of the power supply trunk lines 3a, 3b and the connecting trunk line 5 can be switched to select the power path to supply to the loads 7a, 7b connected to each power distribution device.

[0019] In this embodiment, a central controller 10 is provided to control the power paths. The central controller 10 determines the power paths based on the current capacities and charge states of the power sources 2a and 2b, and transmits power main line switching commands to the controllers 9a and 9b via communication. A control area network (CAN) can be used as a communication means, for example. Based on the received switching command, the controller 9a switches the ON / OFF states of the MOSFETs (M1, M2), semiconductor switch S1, and semiconductor switch S2 provided in the first power distribution device 1a. Based on the received switching command, the controller 9b switches the ON / OFF states of the MOSFETs (M3, M4), semiconductor switch S3, and semiconductor switch S4 provided in the second power distribution device 1b.

[0020] In the above-described in-vehicle power supply system, for example, if the power supply main line 3b is disconnected, the power supply to the second power distribution device 1b can be switched to the power path from the connection main line 5, thereby enabling the power supply to continue. However, when the controller 9b detects the disconnection of the power supply main line 3b, issues a switching command to the controller 9a via the central controller 10, and switches the MOSFETs (M1, M2) to an ON state where power can be supplied, a delay (communication delay) occurs due to the communication speed, and during that time, the power supply to the second power distribution device 1b is cut off, which is a problem. To solve this problem, the first and second power distribution devices 1a, 1b in this embodiment operate as follows.

[0021] 2 to 4 show the switching operation of the power path by the first and second power distribution devices 1a and 1b in the on-board power distribution device 1 of this embodiment when a power main line fails. To explain the switching operation, Figs. 2 to 4 show the ON / OFF states of the semiconductor switches and the current paths, and the configuration shown in Fig. 1 is omitted.

[0022] FIG. 2 shows a normal operating state in which there are no faults in the power supply trunk 3a, the power supply trunk 3b, or the connection trunk 5, and power can be supplied via any path. In this embodiment, power is supplied from the power source 2a to the first power distribution device 1a via the power supply trunk 3a. In the first power distribution device 1a, the semiconductor switch S1 is ON and the semiconductor switch S2 is OFF, so that power from the power source 2a is supplied to the load 7a. The MOSFET (M1) is ON and the MOSFET (M2) is OFF. As a result, the MOSFET (M1) is ON and conductive, and the MOSFET (M2) is conductive via its body diode, allowing voltage to be applied to the connection trunk 5. Due to the rectification action of the body diode of the MOSFET (M2), current from the connection trunk 5 is blocked even if the voltage on the connection trunk 5 rises. Therefore, the load 7a is limited to power supply from the power source 2a, and the desired current path can be set.

[0023] In this embodiment, power is supplied from power source 2b to second power distribution device 1b via power supply trunk 3b. In second power distribution device 1b, semiconductor switch S3 is ON and semiconductor switch S4 is OFF, so that power from power source 2b is supplied to load 7b. MOSFET (M3) is ON and MOSFET (M4) is OFF. As a result, MOSFET (M3) is ON and conductive, and MOSFET (M4) is conductive via its body diode, allowing voltage to be applied to connection trunk 5. Due to the rectification action of the body diode of MOSFET (M4), current from connection trunk 5 is blocked even if the voltage on connection trunk 5 rises. Therefore, power supply to load 7b is limited to power source 2b, allowing the desired current path to be established. This switch configuration allows selection of the power source to supply to loads 7a and 7b even when voltage variations occur between power sources 2a and 2b, and allows voltage to be applied to connection trunk 5.

[0024] FIG. 3 shows the operating state when a disconnection occurs in the power supply trunk 3b in the above configuration. When the second power distribution device 1b detects a disconnection from a voltage drop in the power supply trunk 3b, it turns off semiconductor switch S3 and turns on semiconductor switch S4. As a result, power is supplied to the load 7b from the connection trunk 5. A current is temporarily supplied to the connection trunk 5 via a path that passes through the MOSFET (M1) and the body diode of the MOSFET (M2) of the first power distribution device 1a. In the second power distribution device 1b, the disconnection detection and switching of the semiconductor switches S3 and S4 are performed within the same unit, so that switching can be performed immediately when the voltage of the power supply trunk 3b falls below a predetermined value. Furthermore, the first power distribution device 1a is in standby mode with a voltage applied to the connection trunk 5 by the body diode of the MOSFET (M2), so current can be supplied immediately.

[0025] 4 shows an operating state at the time of restoration after the power supply to the second power distribution device 1b is switched to the power supply from the connection trunk line 5. In the first power distribution device 1a, the current sensor 4a detects an increase or rise in the current flowing through the connection trunk line 5, and switches the MOSFET (M2) to the ON state. In other words, the current supply via the body diode of the MOSFET (M2) is switched to the current supply via the channel of the MOSFET. This eliminates the voltage drop due to the forward voltage of the body diode, and makes it possible to suppress power loss due to the MOSFET (M2).

[0026] Figure 5 shows time charts of the switching operation and voltage and current at each point during normal operation, when a line is broken, and when the line is restored. The vertical axis of each time chart represents the voltage and current at the location shown in Figure 1. Voltage Va is the voltage of power supply trunk 3a, Vb is the voltage of power supply trunk 3b, current Is is the current of connection trunk 5, Vs is the voltage of connection trunk 5, VLa is the voltage of load power line 6a, and VLb is the voltage of load power line 6b. At time t0, power is being supplied to loads 7a and 7b via the power path shown in Figure 2. At this time, MOSFET (M1) is ON, MOSFET (M2) is OFF, MOSFET (M3) is ON, and MOSFET (M4) is OFF. Because voltage is applied through the body diode of MOSFET (M2), voltage Vs of connection trunk 5 at time t0 is a value obtained by subtracting the forward voltage Vf of the diode from voltage Va of power supply trunk 3a.

[0027] At time t1, as shown in FIG. 3, a disconnection occurs in the power supply trunk 3b. When the power supply trunk 3b is disconnected, the voltage Vb of the power supply trunk 3b drops. When this voltage drop reaches a predetermined threshold Vth (time t2), the controller 9b of the second power distribution device 1b determines that a disconnection has occurred and turns off the semiconductor switch S3 and turns on the semiconductor switch S4. As a result, the voltage VLb of the load power supply line 6b is switched to the supply from the connection trunk 5, and a voltage that is lower than the voltage Va of the power supply trunk 3a by the forward voltage Vf of the body diode of the MOSFET (M2) is applied. Vf is approximately 0.7 V, so that the voltage required to drive the load can be maintained. As a current is supplied to the load 7b via the connection trunk 5, the current Is of the connection trunk 5 increases.

[0028] Time t2 indicates the restoration operation shown in FIG. 4. When the current Is in the connection trunk 5 exceeds a predetermined threshold Ith (time t3), the controller 9a of the first power distribution device 1a turns on the MOSFET (M2). When the MOSFET (M2) turns on, the voltage drop due to the forward voltage of the body diode is eliminated, and the voltage Vs in the connection trunk 5 rises and becomes approximately equal to the voltage Va in the power supply trunk 3a. Similarly, the voltage VLb in the load power supply line 6b also becomes approximately equal to the voltage Va in the power supply trunk 3a. This completely switches the power supply path to the load 7b, allowing power supply to continue.

[0029] In this embodiment, the case where the power supply main line 3b is disconnected is shown, but even if the power supply main line 3a is disconnected, since the first power distribution device 1a and the second power distribution device 1b have the same configuration, it is possible to continue supplying power to the first power distribution device 1a by switching the power supply path in the same way.

[0030] In this embodiment, silicon-based power MOSFETs (M1 to M4) are used as switching elements (semiconductor transistors) for switching the power supply mains. However, this is not limiting, and power semiconductors such as GaN transistors and SiC-MOSFETs can also be used. IGBTs (Insulated Gate Bipolar Transistors) can also be used. In this case, since IGBTs do not have a body diode, similar actions and effects can be obtained by connecting a separate diode between the collector and emitter.

[0031] In this embodiment, an example has been shown in which a shunt resistor is used as a current sensor for the connection trunk 5, but the present invention is not limited to this method, and it is also possible to detect the current (amount) of the connection trunk 5 based on the source-drain voltage of the MOSFET (M2) or the temperature rise of the MOSFET (M2). Any configuration that can detect a current rise in the connection trunk 5 can achieve the functions and effects of this embodiment.

[0032] (Second Example) A configuration example of a suitable second embodiment of an on-board power distribution device to which the present invention is applied is shown in Fig. 6. In the first embodiment shown above, current sensors 4a and 4b are provided to detect a current increase in the connection trunk line 5, but in this embodiment, a configuration is shown in which no current sensors are used but communication provided between the power distribution devices is used.

[0033] A first power distribution device 1a mounted on a vehicle is supplied with power from a power source 2a mounted on the vehicle via a power supply trunk line 3a. The first power distribution device 1a is equipped with a semiconductor switch in which two MOSFETs (M1, M2) are connected in series with their sources and drains facing in opposite directions. In this embodiment, the MOSFET (M1) has a cathode terminal of its body diode connected to the power supply trunk line 3a, and the MOSFET (M2) has an anode terminal of its body diode connected to the anode terminal of the MOSFET (M1). The cathode terminal of the MOSFET (M2) is connected to a connection trunk line 5 provided outside the first power distribution device 1a.

[0034] The first power distribution device 1a is also provided with a controller 9a that controls the ON / OFF states of the MOSFETs (M1, M2) and the ON / OFF states of the semiconductor switches S1, S2. The controller 9a controls the ON / OFF states of the MOSFETs (M1, M2). The controller 9a also controls the ON / OFF states of the semiconductor switches S1, S2 based on voltage information from a voltage sensor 8a. The controller 9a also includes a CAN interface (communication interface) and controls the ON / OFF states of the MOSFETs (M1, M2) through communication from the outside.

[0035] The second power distribution device 1b of this embodiment has the same configuration as the first power distribution device 1a (MOSFETs (M3, M4), semiconductor switches S3, S4, voltage sensor 8b, controller 9b, etc.). Power is supplied to the second power distribution device 1b from a power source 2b mounted on the vehicle via a power supply trunk line 3b. The first power distribution device 1a and the second power distribution device 1b are connected by a connection trunk line 5. The connection trunk line 5 allows power to be supplied to each other between the first power distribution device 1a and the second power distribution device 1b. This also makes it possible to select the power path to be supplied to the first power distribution device 1a and the second power distribution device 1b. That is, by switching the MOSFETs (M1, M2) and semiconductor switches S1 and S2 provided in the first power distribution device 1a, and the MOSFETs (M3, M4) and semiconductor switches S3 and S4 provided in the second power distribution device, it is possible to switch the current paths of the power supply trunks 3a, 3b and the connection trunk 5 and select the power path to supply to the loads 7a, 7b connected to each power distribution device. In addition, the first power distribution device 1a and the second power distribution device 1b are provided with communication interfaces and are connected by a communication line 11.

[0036] In the above configuration, the operation when a disconnection occurs in the power supply trunk 3b will be described. First, a normal operating state will be described in which there are no faults in the power supply trunk 3a, the power supply trunk 3b, or the connection trunk 5, and power can be supplied via any path. In this embodiment, power is supplied from the power source 2a to the first power distribution device 1a via the power supply trunk 3a. In the first power distribution device 1a, the semiconductor switch S1 is ON and the semiconductor switch S2 is OFF, and power from the power source 2a is supplied to the load 7a. The MOSFET (M1) is ON, and the MOSFET (M2) is OFF. As a result, the MOSFET (M1) is ON and conductive, and the MOSFET (M2) is conductive via its body diode, allowing voltage to be applied to the connection trunk 5. Due to the rectification action of the body diode of the MOSFET (M2), current from the connection trunk 5 is blocked even if the voltage on the connection trunk 5 rises. Therefore, the load 7a is limited to power supply from the power source 2a, and the desired current path can be set.

[0037] In this embodiment, power is supplied to the second power distribution device 1b from the power source 2b via the power supply trunk 3b. In the second power distribution device 1b, the semiconductor switch S3 is ON and the semiconductor switch S4 is OFF, so that power from the power source 2b is supplied to the load 7b. The MOSFET (M3) is ON and the MOSFET (M4) is OFF. As a result, the MOSFET (M3) is ON and conductive, and the MOSFET (M4) is conductive via its body diode, so that a voltage can be applied to the connection trunk 5. Due to the rectification action of the body diode of the MOSFET (M4), even if the voltage on the connection trunk 5 rises, the current from the connection trunk 5 is blocked, and the load 7b is limited to the power supply from the power source 2b, so that the desired current path can be set.

[0038] In the second power distribution device 1b, when the controller 9b detects a disconnection from a voltage drop in the power supply trunk 3b due to the disconnection, it turns off the semiconductor switch S3 and turns on the semiconductor switch S4. As a result, power is supplied to the load 7b from the connection trunk 5. A current is temporarily supplied to the connection trunk 5 through a path that passes through the MOSFET (M1) and the body diode of the MOSFET (M2) of the first power distribution device 1a. In the second power distribution device 1b, the disconnection detection and the switching of the semiconductor switches S3 and S4 are performed within the same unit, so that the switching can be performed immediately if the voltage of the power supply trunk 3b falls below a predetermined value. Furthermore, the first power distribution device 1a is in standby mode with a voltage applied to the connection trunk 5 by the body diode of the MOSFET (M2), so that it can immediately supply current.

[0039] At the same time, when the controller 9b detects a disconnection in the power supply trunk line 3b, it transmits disconnection information to the controller 9a of the first power distribution device 1a via the communication line 11. The disconnection information is information for requesting power supply via the connection trunk line 5, and in this embodiment, it is composed of a switching command for requesting ON switching of the MOSFET (M2). When the controller 9a receives the disconnection information (switching command) from the controller 9b, it switches the MOSFET (M2) to the ON state based on the disconnection information (switching command). In other words, it switches the current supply via the body diode of the MOSFET (M2) to the current supply via the channel of the MOSFET. This eliminates the voltage drop due to the forward voltage of the body diode, and it is possible to suppress power loss due to the MOSFET (M2).

[0040] In this embodiment, a switching command is sent via the communication line 11 to turn on the MOSFET (M2), so recovery takes longer than in the first embodiment, and the voltage of the connection trunk line 5 remains lowered for a longer period due to the forward voltage of the body diode of the MOSFET (M2). However, power supply can be continued, and a current sensor can be omitted, resulting in a simple configuration. The temperature of the MOSFET (M2) rises due to power loss in the body diode of the MOSFET (M2), but if the MOSFET (M2) can be turned on before the allowable temperature of the MOSFET (M2) is reached, element failure will not occur.

[0041] (Third Example) 7 shows a configuration example of a preferred third embodiment of an on-board power distribution device to which the present invention is applied. In this embodiment, diodes 12a and 12b are connected in parallel to the MOSFETs (M2) and (M4) of the first embodiment shown above. Diode 12a is connected in the same direction as the body diode of MOSFET (M2), more specifically, to the source-drain terminal of MOSFET (M2) in the same direction as the forward direction of the body diode, and diode 12b is connected in the same direction as the body diode of MOSFET (M4), more specifically, to the source-drain terminal of MOSFET (M4) in the same direction as the forward direction of the body diode.

[0042] In the above configuration, as shown in FIG. 2, when there is no break in the power supply trunk line 3a, the power supply trunk line 3b, or the connection trunk line 5, the controller 9a is on standby with the MOSFET (M1) in the ON state and the MOSFET (M2) in the OFF state. When there is a current demand from the connection destination of the connection trunk line 5, the current is temporarily supplied via the body diode of the MOSFET (M2). At this time, if a diode 12a is connected in parallel to the MOSFET (M2), the current Is flowing through the connection trunk line 5 can also be supplied from the diode 12a. This increases the current capacity that can be supplied to the load connected to the connection trunk line 5. In addition, because the current flowing through the body diode of the MOSFET (M2) is distributed to the diode 12a, the temperature rise due to power loss in the body diode of the MOSFET (M2) is reduced, preventing damage due to heat generation.

[0043] Similarly, even when current is supplied from the second power distribution device 1b to the first power distribution device 1a via the connecting trunk line 5, the current is dispersed to the diode 12b connected in parallel to the MOSFET (M4), thereby reducing the temperature rise due to power loss in the body diode of the MOSFET (M4) and preventing damage due to heat generation.

[0044] In this embodiment, the diodes 12a and 12b are added to the MOSFETs (M2 and M4), but the diodes may be connected to the other MOSFETs (M1 and M3) in a similar configuration. Alternatively, the diode may be connected to one of the MOSFETs (M1 to M4). The MOSFET to which the external diode is connected can be determined appropriately depending on the current capacity of the MOSFET and the current required for the load.

[0045] (Fourth Example) FIG. 8 shows a configuration example of a fourth embodiment including an example of semiconductor switches S1 and S2 in the first power distribution device 1a. The semiconductor switch S1 has a configuration in which MOSFETs (Ma) and (Mb) are connected back-to-back. A gate driver (GD) that applies a voltage to the gate electrodes is connected to the MOSFETs (Ma) and (Mb). The gate driver (GD) generates a voltage to be applied to the gate electrodes in response to a voltage signal from the controller 9a. The semiconductor switch S2 has a configuration in which MOSFETs (Mc) and (Md) are connected back-to-back. A gate driver (GD) that applies a voltage to the gate electrodes is connected to the MOSFETs (Ma) and (Mb). The gate driver (GD) generates a voltage to be applied to the gate electrodes in response to a voltage signal from the controller 9a. Back-to-back connection means that two MOSFETs are connected in series with their source-drain directions facing in opposite directions. In other words, the semiconductor switches S1 and S2 are configured as two semiconductor switches connected in series with their source-drain directions facing in opposite directions. These semiconductor switches S1 and S2 allow selection of the current path to be supplied to the load 7a. For example, when supplying current from the power supply main line 3a to the load 7a, the semiconductor switch S1 is set to the conducting state and the semiconductor switch S2 is set to the cut-off state.

[0046] Furthermore, the above-described delta-connection of the MOSFETs (M1, M2), semiconductor switch S1, and semiconductor switch S2 has the following effects. First, if the semiconductor switch S1 fails due to an open circuit while current is being supplied from the power supply trunk 3a to the load 7a via the semiconductor switch S1, power supply from the power supply trunk 3a can be continued by switching to a path via the MOSFETs (M1, M2) and semiconductor switch S2. Also, if the semiconductor switch S2 fails due to an open circuit while current is being supplied from the connection trunk 5 to the load 7a via the semiconductor switch S2, power supply from the connection trunk 5 can be continued by switching to a path via the MOSFETs (M1, M2) and semiconductor switch S1.

[0047] In this embodiment, the semiconductor switches S1 and S2 are configured with two MOSFETs connected back-to-back, but as shown in FIG. 9, they may also be configured with one MOSFET.

[0048] When semiconductor switches S1 and S2 are configured with a single MOSFET as shown in FIG. 9, the forward current of the MOSFET's body diode cannot be blocked. For example, assume that semiconductor switch S1 is turned ON and semiconductor switch S2 is turned OFF to supply power from power supply trunk line 3a to load 7a. In this case, if the voltage of power supply trunk line 3a is higher than the voltage of connection trunk line 5 by more than the forward voltage of the diode, current flows from power supply trunk line 3a to connection trunk line 5 via the body diode of semiconductor switch S2. Therefore, the embodiment of FIG. 9 can be used when the difference between the voltage of power supply trunk line 3a and the voltage of connection trunk line 5 is less than the forward voltage of the diode. The configuration of semiconductor switches S1 and S2 shown in FIG. 9 has a single MOSFET, which has the advantage of reducing the on-resistance compared to the configuration of FIG. 8.

[0049] (Fifth Example) 10 is a diagram showing a configuration example of a preferred fifth embodiment of an on-board power distribution device to which the present invention is applied. In the first embodiment shown above, the first and second power distribution devices that distribute power to loads have the same configuration, but in this embodiment, a configuration in which they have different configurations is shown.

[0050] The first power distribution device 1a shown in FIG. 10 has a configuration similar to the first power distribution device 1a shown in FIG. 1 of the first embodiment, but a load 7f is connected to the connection trunk 5. Power is supplied to the load 7f through a power path from the power source 2b via the power line 3f and a power path from the connection trunk 5. The load 7f is disposed between the power line 3f and the connection trunk 5. A diode 13a is provided between the power line 3f and the load 7f. The anode side of the diode 13a is connected to the power line 3f, and the cathode side of the diode 13a is connected to the load 7f. A diode 13b is also provided between the connection trunk 5 and the load 7f. Similarly, the anode side of the diode 13b is connected to the connection trunk 5, and the cathode side of the diode 13b is connected to the load 7f. These diodes 13a and 13b configure the load 7f as a diode-OR circuit. These diodes 13a and 13b constitute a second power distribution device that distributes power to the load 7f.

[0051] Loads 7f are selected from those that are important to vehicle safety, such as electric steering, electric brakes, and autonomous driving controllers, which may be at risk of being affected by a power failure.

[0052] In the power supply circuit configuration of the load 7f using the diode OR circuit described above, power is supplied to the load 7f from either the connection trunk 5 or the power line 3f, whichever has the higher voltage. Because the connection trunk 5 receives power from the first power distribution device 1a, the voltage fluctuates depending on the operating state of the load 7a connected to the first power distribution device 1a. For example, when the current consumption of the load 7a increases, the voltage of the connection trunk 5 decreases due to a voltage drop caused by the electrical resistance of the power trunk 3a or the internal resistance of the power source 2a. When the voltage of the connection trunk 5 becomes lower than the voltage of the power line 3f, the power supply path to the load 7f switches to supply power from the power line 3f. Frequent switching of the power supply path depending on the operating state of the load 7a causes fluctuations in the power supply voltage of the load 7f, resulting in power noise. Furthermore, when the current flowing through the connection trunk 5 or the power line 3f fluctuates significantly in a short period of time, surge voltages occur due to the reactance components of the power trunks. This can cause the voltage of the power supply mains to become unstable, which may lead to malfunction. If the load 7f is an actuator or a computing device that consumes a lot of power, the current fluctuation caused by switching the power supply path will become larger, further increasing the impact of these factors.

[0053] By applying this embodiment, the power supply is not interrupted when a power supply trunk fails, and frequent switching of the power supply path can be reduced. First, the MOSFET (M1) provided in the first power distribution device 1a is set to the ON state, and the MOSFET (M2) is set to the OFF state. At this time, the voltage value of the connection trunk 5 becomes a value reduced by the forward voltage of the body diode of the MOSFET (M2). The voltage of the power supply line 3f is the voltage value of the power source 2b. If the voltage values ​​of the power sources 2a and 2b are approximately the same, the voltage value of the power supply line 3f becomes higher than the voltage value of the connection trunk 5, and power can be supplied to the load 7f from the power supply line 3f. In other words, by setting the MOSFET (M2) to the OFF state and applying voltage to the connection trunk 5 via the body diode, a voltage difference can be generated between the power supply line 3f and the connection trunk 5. This reduces frequent switching of the power supply path to the load 7f.

[0054] In the above state, if the power line 3f is disconnected and the voltage value of the power line 3f drops below the voltage value of the connection trunk 5, the power supply to the load 7f switches to a path via the connection trunk 5. A current is temporarily supplied to the connection trunk 5 via a path that passes through the MOSFET (M1) of the first power distribution device 1a and the body diode of the MOSFET (M2). The first power distribution device 1a is in standby mode with a voltage applied to the connection trunk 5 by the body diode of the MOSFET (M2), so it can immediately supply current. In the first power distribution device 1a, the current sensor 4a detects an increase or rise in the current flowing to the connection trunk 5 and switches the MOSFET (M2) to the ON state. In other words, the current supply via the body diode of the MOSFET (M2) is switched to a current supply via the channel of the MOSFET (M2). This eliminates the voltage drop due to the forward voltage of the body diode, thereby suppressing power loss and voltage drop due to the MOSFET (M2).

[0055] (Sixth Example) 11 is a diagram showing a configuration example of a preferred sixth embodiment of an on-board power distribution device to which the present invention is applied. In the first embodiment shown above, semiconductor switches S1, S2, S3, and S4 are provided to switch the power supply paths to the loads 7a and 7b, but this embodiment shows a configuration in which loads are connected to a connection trunk line without using semiconductor switches.

[0056] The first power distribution device 1g receives power from a power source 2a mounted on the vehicle via a power supply trunk 3a. The first power distribution device 1g distributes power from the power supply trunk 3a to a load 7a via a load power line 6a branched from between the power supply trunk 3a and a MOSFET (M1). That is, the load 7a is connected to the load power line 6a branched from between the power supply trunk 3a and the MOSFET (M1) and receives power from the load. The first power distribution device 1g also includes a semiconductor switch in which the source and drain of two MOSFETs (M1, M2) are connected in series in reverse orientation. In this embodiment, the MOSFET (M1) has a cathode terminal of its body diode connected to the power supply trunk 3a, and the MOSFET (M2) has an anode terminal of its body diode connected to the anode terminal of the MOSFET (M1). The cathode terminal of the MOSFET (M2) is connected to a connection trunk 5a provided outside the first power distribution device 1g via a current sensor 4a.

[0057] The first power distribution device 1g is also provided with a controller 9g that controls the ON / OFF states of the MOSFETs (M1, M2). The controller 9g acquires current information from the current sensor 4a and controls the ON / OFF states of the MOSFETs (M1, M2).

[0058] The second power distribution device 1h receives power from a power source 2b mounted on the vehicle via a power supply trunk 3b. The second power distribution device 1h distributes power from the power supply trunk 3b to a load 7b via a load power line 6b branched from between the power supply trunk 3b and a MOSFET (M3). That is, the load 7b is connected to the load power line 6b branched from between the power supply trunk 3b and the MOSFET (M3) and receives power from the load. The second power distribution device 1h also includes a semiconductor switch in which the source and drain of two MOSFETs (M3, M4) are connected in series in reverse orientation. In this embodiment, the cathode terminal of the body diode of the MOSFET (M3) is connected to the power supply trunk 3b, and the anode terminal of the body diode of the MOSFET (M4) is connected to the anode terminal of the MOSFET (M3). The cathode terminal of the MOSFET (M4) is connected to a connection trunk 5b provided outside the second power distribution device 1h via a current sensor 4b.

[0059] The second power distribution device 1h is also provided with a controller 9h that controls the ON / OFF states of the MOSFETs (M3, M4). The controller 9h acquires current information from the current sensor 4b and controls the ON / OFF states of the MOSFETs (M3, M4).

[0060] Load 7f mounted on the vehicle is supplied with power through two paths, connection trunk line 5a and connection trunk line 5b. Load 7f is arranged between connection trunk line 5a and connection trunk line 5b. Diode 13a is provided between connection trunk line 5a and load 7f. The anode side of diode 13a is connected to connection trunk line 5a, and the cathode side of diode 13a is connected to load 7f. Diode 13b is also provided between connection trunk line 5b and load 7f. Similarly, the anode side of diode 13b is connected to connection trunk line 5b, and the cathode side of diode 13b is connected to load 7f. These diodes 13a and 13b configure load 7f as a power supply for a diode OR circuit.

[0061] Loads 7f are selected from those that are important to vehicle safety, such as electric steering, electric brakes, and autonomous driving controllers, which may be at risk of being affected by a power failure.

[0062] In the power supply circuit configuration of the load 7f using the diode OR circuit described above, the power supply path to the load 7f is supplied from the connection trunk 5a or the connection trunk 5b, whichever has the higher voltage. Because the connection trunk 5a receives power from the first power distribution device 1g, the voltage fluctuates depending on the operating state of the load 7a connected to the first power distribution device 1g. For example, when the current consumption of the load 7a increases, the voltage value of the connection trunk 5a decreases due to a voltage drop caused by the electrical resistance of the power supply trunk 3a and a voltage drop caused by the internal resistance of the power source 2a. When the voltage of the connection trunk 5a becomes lower than the voltage of the connection trunk 5b, the power supply path to the load 7f switches to supply from the connection trunk 5b. Similarly, the voltage fluctuates depending on the operating state of the load 7b connected to the second power distribution device 1h. Frequent switching of the power supply path depending on the operating state of the load 7a or the load 7b in this manner causes frequent fluctuations in the power supply voltage of the load 7f, resulting in power supply noise. Furthermore, if the current flowing through the connection trunks 5a and 5b fluctuates significantly in a short period of time, surge voltages will occur due to the reactance components of the power supply trunks. This will cause the voltage of the power supply trunks to become unstable, which may lead to malfunctions. If the load 7f is an actuator or computing device that consumes a lot of power, the current fluctuations caused by switching the power supply path will be large, further exacerbating these effects.

[0063] By applying this embodiment, the power supply is not interrupted when a power supply trunk fails, and frequent switching of the power supply path can be reduced. First, the MOSFET (M1) provided in the first power distribution device 1g is set to the ON state, and the MOSFET (M2) is set to the OFF state. At this time, the voltage value of the connection trunk 5a is reduced by the forward voltage of the body diode of the MOSFET (M2). The MOSFET (M3) provided in the second power distribution device 1h is set to the ON state, and the MOSFET (M4) is set to the ON state. At this time, the voltage value of the connection trunk 5b is not reduced by the body diode because current flows through the channels of the MOSFETs (M3, M4). Therefore, the voltage value of the connection trunk 5b is higher than the voltage value of the connection trunk 5a, and power can be maintained supplied to the load 7f from the connection trunk 5b. In other words, by turning the MOSFET (M2) to the OFF state and applying voltage to the connection trunk 5a via the body diode, a voltage difference can be generated between the connection trunk 5a and the connection trunk 5b, making it possible to select the power supply path to the load 7f.

[0064] In the above state, if the connection trunk 5b is disconnected and the voltage value of the connection trunk 5b drops below the voltage value of the connection trunk 5a, the power supply to the load 7f switches to a path via the connection trunk 5a. The connection trunk 5a temporarily supplies current via a path that passes through the MOSFET (M1) of the first power distribution device 1g and the body diode of the MOSFET (M2). The first power distribution device 1g is in standby mode with a voltage applied to the connection trunk 5a via the body diode of the MOSFET (M2), allowing it to immediately supply current. The first power distribution device 1g detects an increase or rise in the current flowing through the connection trunk 5a using the current sensor 4a and switches the MOSFET (M2) to the ON state. That is, the current supply via the body diode of the MOSFET (M2) switches to a current supply via the channel of the MOSFET. This eliminates the voltage drop due to the forward voltage of the body diode, thereby suppressing power loss due to the MOSFET (M2).

[0065] In this embodiment, in the MOSFETs (M1 to M4), the MOSFET (M1) is turned ON, the MOSFET (M2) is turned OFF, the MOSFET (M3) is turned ON, and the MOSFET (M4) is turned ON, so that power is supplied to the load 7f with priority given to the connection trunk 5b. However, a similar method can also be used to supply power to the load 7f with priority given to the connection trunk 5a.

[0066] (First to third modified examples of MOSFET (M1, M2) configuration) In the embodiment of FIG. 1, the MOSFETs M1 and M2 are configured with the anodes of their body diodes connected in series. However, as shown in FIG. 12A, their cathodes may be connected in series. That is, the anode terminal of the body diode of the MOSFET M1 may be connected toward the connection trunk line 5, the anode terminal of the body diode of the MOSFET M2 may be connected toward the power supply trunk line 3a, and the cathode terminal of the body diode of the MOSFET M2 may be connected to the cathode terminal of the MOSFET M1 (first modification). Alternatively, as shown in FIG. 12B, multiple MOSFETs M2a and M2b may be connected in series (second modification), or as shown in FIG. 12C, multiple MOSFETs M2a and M2b may be connected in parallel (third modification).

[0067] (First modified example of system configuration) In the above-described embodiment, a configuration using two first and second power distribution apparatuses 1a and 1b (hereinafter simply referred to as power distribution apparatuses 1a and 1b) as shown in FIG. 1 has been described. However, the system configuration for applying this embodiment is not limited to this. For example, as shown in FIG. 13A, power distribution apparatus 1a may be connected to another power distribution apparatus 1c via a power supply trunk line 3a and supplied with power. Also, power distribution apparatus 1b may be connected to another power distribution apparatus 1d via a power supply trunk line 3b and supplied with power. In this case, power distribution apparatuses 1c and 1d may also have a configuration similar to that of power distribution apparatuses 1a and 1b. Power distribution apparatuses 1c and 1d are connected to power sources 2a and 2b via power supply trunk lines 3c and 3d, respectively. Power is supplied from power sources 2a and 2b via power supply trunk lines 3c and 3d, and power from power supply trunk lines 3c and 3d is distributed to loads 7c and 7d. In this case, the connection trunk 5 is not limited to the portion shown in Fig. 13A, and the power supply trunk 3a or the power supply trunk 3b can be used as the connection trunk. In other words, the connection trunk changes depending on the setting of the current path. In addition to this, this embodiment can be applied to any system configuration as long as it is a vehicle power supply system in which multiple power distribution devices and multiple power supply devices mounted on a vehicle are connected to each other by power supply trunks.

[0068] (Second modified example of system configuration) In the above-described embodiment, a configuration in which two power sources 2a and 2b are connected to different power supply trunks 3a and 3b as shown in FIG. 1 has been described. However, when applying this embodiment, the system configuration is not limited to this, and may be, for example, the configuration shown in FIG. 13B. In FIG. 13B, power sources 2a and 2b are connected to a (common) power supply trunk 3e, which is branched into power supply trunks 3c and 3d by power distribution device 1e. Power supply trunk 3c is connected to power distribution device 1c, and power supply trunk 3d is connected to power distribution device 1d. Power distribution device 1a is connected to power distribution device 1c by power supply trunk 3a. Power distribution device 1b is connected to power distribution device 1d by power supply trunk 3b. Power distribution devices 1a and 1b are connected by a connection trunk 5.

[0069] (summary) As described above, the on-board power distribution device 1 of this embodiment includes a first power distribution device 1a that distributes power from a first power supply trunk 3a to a load, a second power distribution device 1b that distributes power from a second power supply trunk 3b to a load, and a connection trunk 5 that connects the first power distribution device 1a and the second power distribution device 1b, and the first power distribution device 1a is provided with a semiconductor switch in which a first semiconductor transistor (MOSFET (M1)) and a second semiconductor transistor (MOSFET (M2)) are connected in series in opposite directions, and the semiconductor switch is provided between the first power supply trunk 3a and the connection trunk 5, and stands by with the first semiconductor transistor (MOSFET (M1)) in an ON state and the second semiconductor transistor (MOSFET (M2)) in an OFF state, with a voltage applied to the connection trunk 5 via the body diode of the second semiconductor transistor (MOSFET (M2)), and turns on the second semiconductor transistor (MOSFET (M2)) in response to a rise in current in the connection trunk 5.

[0070] According to this embodiment, when switching paths due to a power trunk line failure, semiconductor switches composed of semiconductor transistors such as MOSFETs are set in a diode state and placed on standby, allowing current to be supplied immediately when a power demand arises from a load connected to the connection trunk line. Furthermore, by detecting the occurrence of a current demand from a load connected to the connection trunk line and turning on the semiconductor transistors such as the MOSFETs, voltage drops and power losses caused by the semiconductor transistors can be reduced. Furthermore, these effects reduce power losses caused by switches in the power trunk line through which a large current flows, allowing for the miniaturization of heat dissipation components.

[0071] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0072] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely realized by hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be realized by software, in which a processor interprets and executes a program that realizes each function. Information such as the program, tape, and file that realizes each function can be stored in a memory, a recording device such as a hard disk or solid state drive (SSD), or a recording medium such as an IC card, SD card, or DVD.

[0073] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. [Explanation of symbols]

[0074] 1...In-vehicle power distribution device 1a~1h...Power distribution device 2a, 2b...Power source 3a, 3b...power main line 4a, 4b Current sensor 5. Connecting trunk line 6a, 6b...Load power line 7a, 7b...Load 8a, 8b: Voltage sensors 9a, 9d... Controller 10. Central Controller 11. Communication line 12a, 12b...Diode 13a, 13b...Diode M1 to M4 MOSFETs Ma~Md MOSFET S1 to S4: Semiconductor switches GD···Gate driver

Claims

1. An on-vehicle power distribution device including a first power distribution device that distributes power from a first power supply trunk line to a load, a second power distribution device that distributes power from a second power supply trunk line to the load, and a connection trunk line that connects the first power distribution device and the second power distribution device, the first power distribution device includes a semiconductor switch in which a first semiconductor transistor and a second semiconductor transistor are connected in series in opposite directions, the semiconductor switch being provided between the first power supply trunk line and the connection trunk line; an on-board power distribution device that sets the first semiconductor transistor in an ON state, the second semiconductor transistor in an OFF state, waits in a state in which a voltage is applied to the connection trunk line via a body diode of the second semiconductor transistor, and turns on the second semiconductor transistor in response to a rise in current in the connection trunk line.

2. 2. The in-vehicle power distribution device according to claim 1, The first semiconductor transistor is a MOSFET (M1) and has a cathode terminal of its body diode connected toward the first power supply main line, and the second semiconductor transistor is a MOSFET (M2) and has a cathode terminal of its body diode connected toward the connection main line, or the first semiconductor transistor is a MOSFET (M1) and an anode terminal of its body diode is connected toward the connection trunk line, the second semiconductor transistor is a MOSFET (M2) and an anode terminal of its body diode is connected toward the first power supply trunk line, An on-board power distribution device characterized by keeping the MOSFET (M1) in an ON state and the MOSFET (M2) in an OFF state, waiting with a voltage applied to the connection trunk line via a body diode of the MOSFET (M2), and turning the MOSFET (M2) ON in response to a rise in current in the connection trunk line.

3. 3. The in-vehicle power distribution device according to claim 2, An in-vehicle power distribution device comprising a current detector for detecting a current flowing through the connection trunk line, and turning on the MOSFET (M2) when the amount of current detected by the current detector exceeds a predetermined threshold.

4. 3. The in-vehicle power distribution device according to claim 2, an on-board power distribution device, characterized in that the first power distribution device and the second power distribution device are connected by a communication line, the second power distribution device transmits a switching command to the first power distribution device via the communication line, and the first power distribution device turns on the MOSFET (M2) based on the switching command.

5. 3. The in-vehicle power distribution device according to claim 2, An on-vehicle power distribution device characterized in that a diode is connected in parallel to the source-drain terminal of the MOSFET (M1) or the MOSFET (M2) in the same direction as the forward direction of the body diode.

6. 2. The in-vehicle power distribution device according to claim 1, an on-board power distribution device, characterized in that a load power supply line is connected via a first semiconductor switch branched off from between the first semiconductor transistor and the first power supply trunk line, and the load power supply line is connected via a second semiconductor switch branched off from between the connection trunk line and the second semiconductor transistor, and a load connected to the first power distribution device is connected to the load power supply line and supplied with power.

7. 7. The in-vehicle power distribution device according to claim 6, The in-vehicle power distribution device is characterized in that the first semiconductor switch or the second semiconductor switch is a semiconductor switch in which two MOSFETs are connected in series so that the source-drain directions of the two MOSFETs are opposite to each other.

8. 2. The in-vehicle power distribution device according to claim 1, a load connected to the first power distribution device is connected to a load power line branched from between the first semiconductor transistor and the first power supply trunk line and is supplied with power;

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