Power distribution device and disconnection determination method

Abstract

A power distribution device that supplies power to a vehicle load through two or more paths of a power line, the power distribution device being provided with: a current detection element that detects the current of the power line; and an inspection current control unit that controls the amount of current flowing through a path other than the vehicle load in accordance with the operating state of the vehicle load.

Description

Reference-based import

[0001] This application claims the benefit of Japanese Patent Application No. 2023-35724, filed on March 8, 2023, and incorporates the content of that application into this application by reference. Technical Field

[0002] The present invention relates to a power distribution device mounted on a vehicle, and more particularly to fault detection of a power supply path. Background Art

[0003] In recent years, the advancement of electrification and autonomous driving in vehicles has led to a demand for high reliability (redundancy) in onboard power networks. This, in turn, requires a reduction in the number of wires used to supply power and improve efficiency. Conventional onboard power networks often employ a relay box or fuse box located near the battery, with power cables radially routed to each sensor and actuator in the vehicle. In these onboard power networks, the increasing number of sensors and actuators required to achieve redundancy in power supply has necessitated an increase in the number of wires.

[0004] As background technology in this technical field, there is the following prior art. Patent document 1 (Japanese Patent Publication No. 2016-54617) describes a power supply system comprising: one or more monitoring devices that are supplied with power from a ring power line connected in a power line loop and monitor the state of a storage unit; and a control device that controls the monitoring device, the control device comprising: a first power wiring that constitutes a portion of the ring power line; a second power wiring that is connected to a power supply source and the first power wiring; a switching unit that switches the supply and cutoff of power supplied from the power supply source; and a control unit that controls the switching unit to detect an abnormality in the ring power line or an abnormality in the monitoring device, the monitoring device comprising: a third power wiring that constitutes a portion of the ring power line; and a fourth power wiring that supplies power to a load provided by the monitoring device connected to the third power wiring. Summary of the Invention Problems to be solved by the invention

[0005] Patent Document 1, mentioned above, describes a power supply system based on a ring-shaped power grid with monitoring devices connected in a ring pattern. However, with the ring connection temporarily disconnected, a switching unit is included to switch power supply and disconnection. The system collects power supply status information from each monitoring device connected to the ring-shaped power grid to determine whether a power outage has occurred in the ring-shaped power grid. In Patent Document 1, the ring connection is temporarily disconnected during power outage diagnosis, potentially causing power outages in a portion of the ring-shaped power grid. Consequently, power outage detection in the power supply grid described in Patent Document 1 is limited to when the vehicle is stationary.

[0006] If a portion of the ring power network is disconnected while a vehicle is in motion, the current path becomes concentrated in a specific section of the path where power can be supplied, potentially exceeding the ring power network's permissible current. Therefore, in vehicle-mounted power networks, which require high reliability, it is necessary to quickly detect disconnections while the vehicle is in motion. Based on the disconnected section, the operation of onboard equipment and the power supply to the equipment can be restricted within a safe range.

[0007] Therefore, a technology is provided for detecting a disconnection of an in-vehicle power network in a short time without interrupting the power supply even while the vehicle is running. Technical means to solve the problem

[0008] A representative example of the invention disclosed in this application is as follows: a power distribution device that supplies power to vehicle loads via two or more paths along a power main line. The power distribution device is characterized by comprising: a current detection element that detects the current in the power main line; and a detection current control unit that controls the amount of current flowing through paths other than the vehicle loads based on the operating state of the vehicle loads. Effects of the Invention

[0009] According to one embodiment of the present invention, power supply is not cut off even when the vehicle is running, and a disconnection of the vehicle power network can be detected in a short time. Other problems, configurations, and effects than those described above will become clear from the description of the embodiments for carrying out the invention below. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A This is a diagram showing an example of an on-vehicle power network according to an embodiment of the present invention. Figure 1B This is a diagram showing an example of an on-vehicle power network according to an embodiment of the present invention. Figure 1C This is a diagram showing an example of an on-vehicle power network according to an embodiment of the present invention. Figure 2 This is a diagram showing the configuration of a power distribution device 1 a according to the first embodiment. Figure 3AThis is a diagram showing changes in the current path within the power distribution device and the current in the power main line due to the operation of the determination unit in the first embodiment. Figure 3B This is a diagram showing changes in the current path within the power distribution device and the current in the power main line due to the operation of the determination unit in the first embodiment. Figure 4 This is a timing chart of the load current IL, the inspection current ID, and the main current IM in the first embodiment. Figure 5 This is a timing chart of the load current IL, the inspection current ID, and the main current IM in the second embodiment. Figure 6 This is a diagram showing a fault diagnosis method according to the third embodiment. Figure 7 This is a diagram showing a configuration example of a power distribution device 1 a according to a fourth embodiment. Figure 8 This is a graph showing the minimum current of loads A to E. DETAILED DESCRIPTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] (First embodiment) Figure 1A 、 Figure 1B 、 Figure 1C This is a diagram showing an example of an on-vehicle power network according to this embodiment.

[0013] Figure 1AThe illustrated on-board power network includes multiple power distribution devices 1a through 1d. Power distribution devices 1a through 1d are located in various areas of the vehicle, such as the front, right, left, and rear, and serve as power hubs that supply power to vehicle loads 2a through 2d located in each area. Power distribution devices 1a through 1d are connected in a ring shape via power trunks 3a, 3b, 3c, 3d, 3e, and 3f, with power supplied from each of the multiple power trunks to power distribution devices 1a through 1d. A 12V battery 4, serving as a first power source, is connected to the ring-shaped power trunks 3a and 3b. Battery 4 can be a lead-acid battery, a nickel-metal hydride battery, a lithium-ion battery, or the like. Furthermore, a DC / DC converter 5, serving as a second power source, is connected to power trunks 3e and 3f. The DC / DC converter 5 steps down the voltage of a high-voltage battery (e.g., a 400V battery, not shown) to 12V and supplies the voltage to power trunks 3e and 3f. High-voltage batteries supply power to the traction motors used to drive the wheels of electric or hybrid vehicles. Alternatively, instead of DC / DC converter 5, an AC generator that generates electricity using the driving force of the vehicle's engine can be connected to power mains 3e and 3f. In other words, the first and second power sources can be selected as appropriate, as long as they are supplied from different energy sources.

[0014] Figure 1A The vehicle-mounted power network shown is connected in a ring shape by the power trunk line. Therefore, all the power distribution devices 1a to 1d receive power supply from two systems. Even if one of the power trunk lines is disconnected, power can continue to be supplied to the power distribution devices 1a to 1d from other paths. Figure 1A If the power main line 3a is disconnected, power can be supplied from the battery 4 to the power distribution device 1a via the power main lines 3b, 3d, 3f, 3e, and 3c. Furthermore, if the remaining power in the battery 4 is low, power can be supplied from the DC / DC converter 5 to the power distribution device 1a via the power main lines 3e and 3c.

[0015] In addition, Figure 1BIn the on-vehicle power network shown, the power system based on the power trunks 3a and 3c from the battery 4 is connected to the power distribution devices 1a and 1c, and the power system based on the power trunks 3b and 3d from the DC / DC converter 5 is connected to the power distribution devices 1b and 1d. The power distribution device 1a and the power distribution device 1d are connected via the power trunk 3g, and the power distribution device 1c and the power distribution device 1b are connected via the power trunk 3h. In this way, since the power system from the battery 4 and the power system from the DC / DC converter 5 are connected in a cross-wise manner via the power trunk 3g and the power trunk 3h, all the power distribution devices 1a to 1d receive power supply from two systems, and even if one of the power trunks is disconnected, power can continue to be supplied to the power distribution devices 1a to 1d from other paths. For example, in Figure 1B If the power main line 3c is disconnected, the power supply from the battery 4 to the power distribution device 1c is interrupted, but power can be supplied from the DC / DC converter 5 via the power main lines 3b and 3h.

[0016] In addition, Figure 1C In the vehicle power network shown, the power system from the battery 4 based on the power main line 3a is connected to the power distribution device 1a, and the power system from the DC / DC converter 5 based on the power main line 3e is connected to the power distribution device 1c. The power distribution device 1a and the power distribution device 1c are connected via the power main line 3c. In this way, since the power system from the battery 4 and the power system from the DC / DC converter 5 are connected via the power main line 3c, all the power distribution devices 1a and 1c receive power supply from two systems. Even if one of the power main lines is disconnected, power can continue to be supplied to the power distribution devices 1a and 1c through other paths. For example, in Figure 1C If the power main line 3c is disconnected, the power supply from the DC / DC converter 5 to the power distribution device 1a is interrupted, but power can be supplied from the battery 4 via the power main line 3a. Furthermore, the power supply from the battery 4 to the power distribution device 1c is interrupted, but power can be supplied from the DC / DC converter 5 via the power main line 3e.

[0017] Figure 2 1 is a diagram showing the configuration of a power distribution device 1a according to this embodiment. Figure 2 Although the configuration example of the power distribution device 1 a is described, the other power distribution devices 1 b , 1 c , and 1 d may also have the same configuration.

[0018] Power distribution device 1a is connected to power mains 3a and 3c. Power distribution device 1a includes a current detection element 6a that detects the current flowing through power mains 3a, and a current detection element 6b that detects the current flowing through power mains 3c. Current detection elements 6a and 6b can use shunt resistors or Hall effect elements, for example. Power mains 3a and 3c are connected via disconnection elements 7a and 7b. Disconnection element 7a has one end connected to power mains 3a and the other end connected to disconnection element 7b. Disconnection element 7b has one end connected to disconnection element 7a and the other end connected to power mains 3c. A protection circuit 8 is connected to the connection point between disconnection elements 7a and 7b, and power is supplied to vehicle loads 2a via protection circuit 8. In addition to controlling the current flowing to each vehicle load 2a to switch on and off, protection circuit 8 also has a protective function that shuts off power supply to each vehicle load 2a if it detects overcurrent or overvoltage. Disconnection elements 7a and 7b are preferably power MOSFETs, but can also be mechanical switches such as relays.

[0019] In the above configuration, a test current load 9a and a test current switch 10a, serving as a test current control unit, are connected between the current detection element 6a and the cutoff element 7b. Test current load 9a can be an element capable of adjusting the amount of current flowing to ground using a resistor or other similar device. Test current switch 10a can be an element that switches on and off current flowing through a circuit, such as a semiconductor switch (e.g., a MOS-FET).

[0020] When a shunt resistor is used as the current detection element 6a, the power distribution device 1a includes a current detection unit 11a and a determination unit 12a. The current detection unit 11a detects the current flowing from the voltage across the current detection element 6a to the power main line 3a. The determination unit 12a controls the opening and closing of the test current switch 10a and the disconnection element 7a based on the current value detected by the current detection unit 11a. The determination unit 12a can use a method that compares the current value with a predetermined threshold using a comparator or a method that uses a microcomputer to determine the current value digitally converted by the current detection unit 11a.

[0021] The power main line 3c also has the same configuration as described above. The power distribution device 1a includes a test current load 9b, a test current switch 10b, a current detection unit 11b, and a determination unit 12b. The determination unit 12b controls the opening and closing of the disconnection element 7b and the test current switch 10b based on the current flowing through the power main line 3c.

[0022] Figure 3A 、 Figure 3B This is a diagram showing changes in the current path within the power distribution device 1 a and the current in the power trunk line 3 a due to the operation of the determination unit 12 a .

[0023] Figure 3A This figure shows the current path when power is supplied from the power main line 3a to the vehicle load 2a connected to the power distribution device 1a. When the vehicle load 2a is operating and consuming current, a load current IL flows through the vehicle load 2a. When power is supplied from the power main line 3a, the main current IM of the power main line 3a and the load current IL are substantially equal. At this time, if a break occurs in the power main line 3a, the current detected by the current detection element 6a becomes zero, the determination unit 12a detects a break in the power main line 3a, opens the disconnection element 7a, and disconnects the power main line 3a.

[0024] However, as described above, when the vehicle load 2a consumes current, a disconnection can be determined based on the current flowing through the power main line 3a. However, if the vehicle load 2a is not operating, or if the vehicle load 2a is in a standby state and the load current IL is very low, an erroneous determination may occur. In other words, when the main line current IM is very low, it is difficult to determine whether the vehicle load 2a is stopped or the power main line 3a is disconnected.

[0025] Therefore, if Figure 3B As shown, when main current IM falls below a specified current value, check current switch 10a is turned on, allowing check current ID to flow, increasing main current IM. Specifically, check current ID can flow based on the operating state of vehicle load 2a, as determined by monitoring the state of main current IM. Consequently, if power main 3a is normal, main current IM exceeding check current ID will flow. In this state, if power main 3a is disconnected, the current detected by current detection element 6a will be zero. Determination unit 12a determines a disconnection in power main 3a, opens disconnection element 7a, disconnects power main 3a, and turns on disconnection element 7b, switching power supply to main 3c.

[0026] Furthermore, the above-described configuration enables notification of disconnection information detected by the power distribution device 1a to the higher-level system, limiting the operation of the vehicle loads 2a to the minimum required for safety, or limiting the order of operation and the number of loads that can be operated simultaneously based on the priority and current capacity of the vehicle loads 2a. This prevents excessive current from flowing through unfaulted power trunks within the ring-connected power trunks, and prevents damage to the cables that constitute the power trunks due to heating. Furthermore, this limiting function suppresses current flowing through the power trunks even during a fault, eliminating the need for worst-case scenario power cable design, thereby reducing the cost and weight of the power cables.

[0027] Figure 4 It is a timing diagram of the load current IL, the inspection current ID, and the main current IM.

[0028] When the load current IL decreases and the main current IM becomes less than the first threshold value Ith1 (= I1), the determination unit 12a turns on the inspection current switch 10a, allowing the inspection current ID to flow. The main current IM is the sum of the load current IL and the inspection current ID. When the inspection current switch 10a is turned on, the determination unit 12a updates the first threshold value Ith1 to the value obtained by adding ID to I1 (I1+ID). That is, when the inspection current ID flows through the inspection current load 9a, the first threshold value Ith1 is set to be higher than the inspection current ID. This suppresses the oscillation caused by the repeated opening and closing of the inspection current switch 10a due to the ON / OFF switching of the inspection current. Then, when the load current IL increases and the main current IM exceeds the reset first threshold value Ith1 (= I1+ID), the inspection current switch 10a is turned off, stopping the inspection current. In this case, a second threshold value Ith2 is set, which is lower than the first threshold value Ith1 and lower than the test current ID. When the main line current IM falls below the second threshold value Ith2, a line break is determined, and the disconnection element 7a is opened, disconnecting the power main line 3a. In other words, the test current ID is set to a value greater than the second threshold value Ith2, which serves as the threshold for line break determination. This threshold setting enables accurate line break determination. Furthermore, the determination units 12a and 12b adjust the timing of closing the test current switches 10a and 10b so that they close at different times.

[0029] According to the above embodiment, the interruption of power supply caused by the switching operation for disconnecting the ring connection state, as in the conventional method, can be avoided. In addition, in the disconnection detection method that monitors the current of the power main line, the disconnection state can be detected quickly and accurately without being affected by the on / off state or high / low load state of the vehicle load 2a.

[0030] Furthermore, according to this embodiment, it is not necessary to always flow the test current, and the vehicle load 2a can be reduced. Since the test current flows only when the mains current decreases, the power consumption for disconnection detection can be suppressed.

[0031] Furthermore, it is possible to determine not only whether the vehicle's power network is disconnected, but also where the disconnection is occurring.

[0032] In this embodiment, a test current control unit is provided, which is composed of a test current load 9a and a test current switch 10a. However, the test current control unit is not limited to this configuration. For example, the test current control unit may be configured by switching a semiconductor element or by current control using a constant current circuit. Alternatively, the test current control unit may be configured by connecting a computing element such as a microcomputer or an integrated circuit as a load, and controlling the current amount through processing executed by the computing element.

[0033] (Second embodiment) In the second embodiment, a control method of the inspection current which is more suitable for suppressing the current consumption is shown.

[0034] Figure 5 It is a timing diagram of the load current IL, the inspection current ID, and the main current IM.

[0035] When the load current IL decreases and the main current IM is less than the first threshold value Ith1 (= I1), the determination unit 12a repeatedly switches the inspection current switch 10a ON / OFF, and a pulsed inspection current ID flows. The main current IM is the value obtained by adding the load current IL and the pulsed inspection current ID. When the inspection current switch 10a is on, the determination unit 12a determines that the main current IM is less than the second threshold value Ith2, which is a broken wire. Then, when the load current IL increases and the main current IM is greater than the first threshold value Ith1, the ON / OFF action of the inspection current switch 10a is stopped. In this configuration, a second threshold value Ith2 that is less than the inspection current ID is also set, and a broken wire is determined when the main current IM is less than the second threshold value Ith2. That is, the inspection current ID is set to a value greater than the second threshold value Ith2, which is the threshold for determining a broken wire. This threshold setting enables accurate determination of a broken wire.

[0036] In the second embodiment, the timing of wire breakage diagnosis when load current IL decreases depends on the ON / OFF cycle of the detection current switch 10a. In other words, there is a possibility that the timing of wire breakage detection may be delayed by half the ON / OFF cycle of the detection current switch 10a. Therefore, in vehicle conditions where the timing of wire breakage detection is relaxed, such as when the vehicle is parked, such as when the ignition key is off, power consumption for charging battery 4 can be effectively reduced.

[0037] According to the second embodiment, since the test current is applied in a pulsed manner, the power consumption for the disconnection diagnosis can be suppressed.

[0038] (Third embodiment) The third embodiment shows a configuration for improving the reliability of disconnection detection. The disconnection detection function in the third embodiment is composed of a test current load 9a, a test current switch 10a, and a determination unit 12a.

[0039] Figure 6 This is a diagram showing a fault diagnosis method according to the third embodiment.

[0040] When vehicle load 2a is operating and main current IM is equal to or greater than first threshold value Ith1 (=I1), test current switch 10a is opened and closed, repeatedly (e.g., at predetermined time intervals) flowing a predetermined test current ID through test current load 9a, and a determination is made as to whether current detection element 6a detects a change in main current IM. This allows diagnosis of faults in test current load 9a and test current switch 10a.

[0041] According to the configuration of the third embodiment, if a change in main line current IM cannot be detected even after opening and closing the inspection current switch 10a, it is determined that a failure has occurred in a component of the disconnection detection function, and power supply from the power main line 3a is prohibited. This prevents a non-detection state caused by a failure of the disconnection detection function and prevents interruption of power supply.

[0042] Furthermore, the diagnosis of the failure of the inspection current load 9a and the inspection current switch 10a in the third embodiment is applicable not only to the first embodiment but also to the second embodiment.

[0043] (Fourth embodiment) Figure 7 1 is a diagram showing a configuration example of a power distribution device 1a according to a fourth embodiment. The fourth embodiment differs from the above embodiments in that the opening and closing of the test current switch 10a is controlled based on the operating information of the vehicle load 2a and the states of the disconnection elements 7a and 7b.

[0044] The protection circuit 8 obtains operation information indicating whether each load A to E of the vehicle load 2a is in operation by controlling the switch for ON / OFF operation of the vehicle load 2a or by detecting the current flowing through each load by a current sensor. By using the operation information obtained by the protection circuit 8, the load current can be estimated. For example, Figure 8 The minimum currents of loads A through E in the vehicle's front region are stored in the switch control device 13 of the power distribution device 1a. The check current switch 10a is opened and closed based on whether the total minimum load current of the operating vehicle loads is below a first threshold value Ith1. Furthermore, the disconnect element 7a is turned on to determine that the load current is being supplied from the power mains 3a. The switch control device 13 can be comprised of a microcomputer or the like.

[0045] For example, if the current threshold for disconnection determination is set to 100 mA, when only the drive recorder is operating, disconnection is determined if no test current flows. Therefore, the test current switch 10a is closed to allow the test current to flow through the test current load 9a.

[0046] According to the fourth embodiment, if the power main line 3a is normal, a main line current IM exceeding a predetermined value will always flow through it, and a line break can be detected by monitoring the current detected by the current detection element 6a. Specifically, since the inspection current is controlled based on the operating state of the vehicle load 2a, a line break can be detected simply by monitoring the current detected by the current detection elements 6a and 6b, regardless of the load's operating state.

[0047] As described above, the power distribution device of this embodiment can determine a disconnection if the current flowing through the connected power main line is zero or below a specified threshold. Therefore, even during driving, a disconnection in the vehicle's onboard power network can be detected quickly without interrupting the power supply, and the location of the disconnection can be determined.

[0048] Furthermore, since the test current switches 10 a and 10 b are controlled according to the operating state of the vehicle load 2 a , current consumption due to the test current can be suppressed.

[0049] Furthermore, the present invention is not limited to the above-described embodiments, but includes various variations within the spirit of the appended claims and equivalent configurations. For example, the above-described embodiments are detailed examples for easily understanding the present invention, and the present invention is not necessarily limited to embodiments having all of the described configurations. Furthermore, a portion of the configuration of a particular embodiment may be replaced with a configuration of another embodiment. Furthermore, a configuration of another embodiment may be added to a configuration of a particular embodiment. Furthermore, a portion of the configuration of each embodiment may be supplemented with, deleted from, or replaced with another configuration.

[0050] Furthermore, the above-mentioned components, functions, processing units, and processing means may be partially or entirely implemented in hardware by designing with integrated circuits, or may be implemented in software by interpreting and executing programs that implement the respective functions on a processor.

[0051] Information such as programs, tables, and files that implement various functions can be stored in storage devices such as memories, hard disks, and SSDs (Solid State Drives), or recording media such as IC cards, SD cards, and DVDs.

[0052] In addition, the control lines and information lines are those considered necessary for the purpose of explanation, and do not necessarily represent all the control lines and information lines required for implementation. In practice, it can be considered that almost all components are connected to each other.

Claims

1. A power distribution device that supplies power to vehicle loads via two or more paths of a power main line. The power distribution device is characterized by comprising: a current sensing element for sensing the current of the power mains; and The inspection current control unit controls the amount of current flowing through a path other than the vehicle load according to an operating state of the vehicle load.

2. The power distribution device according to claim 1, wherein: The test current control unit includes a test current load provided on a path other than the vehicle load. The amount of the inspection current flowing through the inspection current load is controlled according to the operating state of the vehicle load.

3. The power distribution device according to claim 2, characterized in that: The test current control unit includes a switch that opens and closes a current path to the test current load.

4. The power distribution device according to claim 1, wherein: When the current flowing through the vehicle load is smaller than a predetermined threshold value, the test current control unit controls so that the current flows through a path other than the vehicle load.

5. The power distribution device according to claim 1, wherein: When the current of the power main line becomes equal to or less than a first threshold value, a predetermined test current flows through a path other than the vehicle load. Furthermore, when the current of the power main line is less than a second threshold value, it is determined that the power main line is disconnected. The second threshold is smaller than the first threshold.

6. The power distribution device according to claim 5, characterized in that: When the predetermined test current flows through a path other than the vehicle load, the test current control unit sets the first threshold value to a value higher than the test current value. The value of the inspection current is set to be higher than the value of the second threshold.

7. The power distribution device according to claim 5, characterized in that: The inspection current is a pulsed current. When the current of the power main line is smaller than the second threshold value when the pulsed test current flows, the test current control unit determines that the power main line is disconnected.

8. The power distribution device according to claim 7, characterized in that: The inspection current control unit switches the inspection current to a pulsed current when the vehicle is stopped.

9. The power distribution device according to claim 5, characterized in that: The test current control unit flows a current of a predetermined value into a path other than the vehicle load when the current of the power main line is greater than the first threshold value. A failure of the test current control unit is diagnosed based on a change in the main current flowing through the current detection element at the time when the current of the predetermined value flows.

10. A line disconnection determination method in a power distribution device. The disconnection determination method is characterized in that: The power distribution device supplies power through two or more paths of the power trunk line and supplies the supplied power to the vehicle load. The power distribution device comprises: a current sensing element for sensing the current of the power mains; and an inspection current control unit that controls the amount of current flowing through a path other than the vehicle load according to an operating state of the vehicle load, The disconnection determination method is as follows: when the current of the power main line becomes less than or equal to a first threshold value, the inspection current control unit flows a predetermined inspection current to a path other than the vehicle load; The test current control unit determines that the power main line is disconnected when the current of the power main line is less than a second threshold value while the predetermined test current is flowing.

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