Power distribution device

Abstract

This power distribution device (10) comprises: a first terminal (81A) to which power is supplied from a voltage conversion unit (92); a second terminal (81B) to which a significant load (71) is connected; a third terminal (81C) to which a general load (72) is connected; a fourth terminal (81D) to which power is supplied from a low-voltage battery (91); a first conductive path (80A) connected to the first terminal (81A); a second conductive path (80B) connected to the second terminal (81B); and a third conductive path (80C) connected to the third terminal (81C); a fourth conductive path (80D) connected to the fourth terminal (81D); an intermediate conductive path (80E); a first switch unit (82A) between the first conductive path (80A) and the intermediate conductive path (80E); a second switch unit (82B) between the second conductive path (80B) and the intermediate conductive path (80E); and a third switch unit (82C) between the third conductive path (80C) and the intermediate conductive path (80E). The fourth conductive path (80D) transmits power from the fourth terminal (81D) to the intermediate conductive path (80E).

Description

power distribution equipment

[0001] The present disclosure relates to a power distribution device.

[0002] Patent Document 1 discloses a power supply system that includes a first battery and a second battery and is capable of supplying power to a first load and a second load. A connection switching unit having a DC-DC converter (voltage conversion unit) is provided between the first battery and the second battery.

[0003] Japanese Patent Application Laid-Open No. 2021-114869

[0004] For example, if a fault such as a ground fault or an open circuit occurs in the DC-DC converter, the first power path to which the first load is connected and the second power path to which the second battery is connected are affected by the fault. For the second load, the first switch and the second switch of the connection switching unit can be controlled to the off state to disconnect the DC-DC converter in which the fault has occurred, but in this case there is no room to supply power to the second load.

[0005] The present disclosure has been made based on the above-mentioned circumstances, and aims to provide a power distribution device that can flexibly supply power to a load when a voltage conversion unit experiences a ground fault or an open state.

[0006] The power distribution device disclosed herein is a power distribution device included in an in-vehicle system having a high-voltage battery, a voltage conversion unit that converts and outputs a voltage input from the high-voltage battery, a low-voltage battery, an important load, and a general load that is less important than the important load, and comprises: a first terminal to which power from the voltage conversion unit is supplied, a second terminal to which the important load is connected, a third terminal to which the general load is connected, a fourth terminal to which power from the low-voltage battery is supplied, a first conduction path connected to the first terminal, a second conduction path connected to the second terminal, a third conduction path connected to the third terminal, a fourth conduction path connected to the fourth terminal, an intermediate conduction path, a first switch unit provided between the first conduction path and the intermediate conduction path, a second switch unit provided between the second conduction path and the intermediate conduction path, and a third switch unit provided between the third conduction path and the intermediate conduction path, and the fourth conduction path transmits power supplied from the fourth terminal to the intermediate conduction path side.

[0007] According to the present disclosure, when the voltage conversion unit is in an abnormal state such as a ground fault or an open state, the power supply to the general loads is restricted and power is supplied to the important loads, and when the voltage conversion unit is not in an abnormal state such as a ground fault or an open state, power can be supplied to the important loads and the general loads.

[0008] FIG. 1 is a circuit diagram schematically illustrating a configuration of an in-vehicle system according to a first embodiment. FIG. 2 is a flowchart illustrating control for setting a potential drop flag to 1 based on potentials in a first conduction path, an intermediate conduction path, and a fourth conduction path of the power distribution device according to the first embodiment. FIG. 3 is a flowchart illustrating control for setting a current stop flag to 1 based on a current in the first conduction path of the power distribution device according to the first embodiment. FIG. 4 is a flowchart illustrating control for determining that a voltage conversion unit is in an open state based on a potential drop flag and a current stop flag. FIG. 5 is a time chart illustrating an example of operation timing of each component of the power distribution device. FIG. 6 is a circuit diagram schematically illustrating a configuration of an in-vehicle system according to a second embodiment. FIG. 7 is a flowchart illustrating an example of control of the power distribution device according to the second embodiment. FIG. 8 is a circuit diagram schematically illustrating a configuration of an in-vehicle system according to a third embodiment. FIG. 9 is a flowchart illustrating an example of control of the power distribution device according to the third embodiment.

[0009] [Description of Embodiments of the Present Disclosure] In the following, embodiments of the present disclosure are listed and illustrated.

[0010] (1) A power distribution device included in an in-vehicle system having a high-voltage battery, a voltage conversion unit that converts and outputs a voltage input from the high-voltage battery, a low-voltage battery, an important load, and a general load that is less important than the important load, the power distribution device comprising: a first terminal to which power from the voltage conversion unit is supplied; a second terminal to which the important load is connected; a third terminal to which the general load is connected; a fourth terminal to which power from the low-voltage battery is supplied; a first conduction path connected to the first terminal; a second conduction path connected to the second terminal; a third conduction path connected to the third terminal; a fourth conduction path connected to the fourth terminal; an intermediate conduction path; a first switch unit provided between the first conduction path and the intermediate conduction path; a second switch unit provided between the second conduction path and the intermediate conduction path; and a third switch unit provided between the third conduction path and the intermediate conduction path, wherein the fourth conduction path transmits power supplied from the fourth terminal to the intermediate conduction path side.

[0011] The power distribution device (1) can supply power from the voltage conversion unit to the important loads and the general loads when the first switch unit, the second switch unit, and the third switch unit are in the on state. When the first switch unit is in the off state, power supply from the voltage conversion unit is stopped and power can be supplied from the low-voltage battery to the important loads and the general loads. Then, by turning off the third switch unit in addition to the first switch unit, a configuration can be realized in which power from the low-voltage battery is supplied only to the important loads while saving power from the low-voltage battery.

[0012] (2) The power distribution device described in (1), comprising: a low potential detection unit that detects a low potential state based on at least one of the potential of the first conductive path and the potential of the intermediate conductive path; a control unit that controls the first switch unit to an off state when the low potential state is detected by the low potential detection unit; and an abnormality determination unit that determines whether the voltage conversion unit side of the intermediate conductive path is in an abnormal state based on the potential difference between the potential of the first conductive path and the potential of the intermediate conductive path.

[0013] The power distribution device (2) can determine by the abnormality determination unit whether or not the voltage conversion unit side of the intermediate conduction path is in an abnormal state.

[0014] (3) The power distribution device according to (2), further comprising a low current detection unit that detects a low current state based on the current flowing through the first conductive path, and the abnormality determination unit determines that the abnormal state exists when the low current detection unit detects the low current state and the potential difference becomes equal to or greater than a potential difference threshold.

[0015] (3) The abnormality determination unit of the power distribution device can increase the reliability of determining whether or not the voltage conversion unit side of the intermediate conductive path is in an abnormal state by detecting the current flowing through the first conductive path and the potential difference between the first conductive path and the intermediate conductive path.

[0016] (4) The power distribution device according to (2), further comprising: a low potential detection unit that detects a low potential state based on at least one of the potential of the first conductive path, the potential of the fourth conductive path, and the potential of the intermediate conductive path; and an overcurrent detection unit that detects an overcurrent state based on a current flowing from the intermediate conductive path side to the first conductive path side, wherein the abnormality determination unit determines that the abnormal state exists when the low potential detection unit detects the low potential state and the overcurrent detection unit detects the overcurrent state.

[0017] (4) The abnormality determination unit of the power distribution device can increase the reliability of determining whether an abnormality exists on the voltage conversion unit side of the intermediate conductive path by detecting the current flowing through the first conductive path and either the potential of the first conductive path, the potential of the fourth conductive path, or the potential of the intermediate conductive path.

[0018] (5) The power distribution device according to (1), further comprising a fourth switch section provided between the fourth conductive path and the intermediate conductive path.

[0019] (5) The power distribution device can be configured so that when an abnormality occurs on the low-voltage battery side of the intermediate conduction path, the fourth switch unit is switched to the off state, thereby preventing the abnormality from propagating to important loads, etc.

[0020] (6) The power distribution device according to (5), comprising: a low potential detection unit that detects a low potential state based on at least one of the potential of the first conductive path, the potential of the fourth conductive path, and the potential of the intermediate conductive path; an overcurrent detection unit that detects an overcurrent state based on a current flowing from the intermediate conductive path side to the fourth conductive path side; an abnormality determination unit that determines that an abnormal state exists on the low-voltage battery side relative to the intermediate conductive path when the low potential detection unit detects the low potential state and the overcurrent detection unit detects the overcurrent state; and a control unit that controls the fourth switch unit to an off state when the abnormality determination unit determines that an abnormal state exists.

[0021] The power distribution device of (6) can prevent the influence of an abnormal state on the low-voltage battery side of the intermediate conduction path from being propagated to important loads, etc.

[0022] (7) The power distribution device according to (5), comprising: a first low potential detection unit that detects a first low potential state based on at least one of the potential of the first conductive path, the potential of the fourth conductive path, and the potential of the intermediate conductive path; a control unit that controls the first switch unit and the fourth switch unit to an off state simultaneously or sequentially when the first low potential state is detected by the first low potential detection unit; a second low potential detection unit that detects a second low potential state based on the potential of the first conductive path; a third low potential detection unit that detects a third low potential state based on the potential of the fourth conductive path; and an abnormality determination unit that determines, when the second low potential state is detected by the second low potential detection unit, that an abnormal state exists on the voltage conversion unit side relative to the intermediate conductive path, and determines, when the third low potential state is detected by the third low potential detection unit, that the abnormal state exists on the low-voltage battery side relative to the intermediate conductive path.

[0023] The power distribution device of (7) can determine by the abnormality determination unit whether or not the voltage conversion unit side of the intermediate conduction path and the low-voltage battery side of the intermediate conduction path are in an abnormal state.

[0024] (8) The power distribution device according to (7), comprising: a first overcurrent detection unit that detects a first overcurrent state based on a current flowing from the intermediate conductive path side to the first conductive path side; and a second overcurrent detection unit that detects a second overcurrent state based on a current flowing from the intermediate conductive path side to the fourth conductive path side; wherein, when the first low potential detection unit does not detect the first low potential state, the abnormality determination unit determines that the abnormal state is on the voltage conversion unit side of the intermediate conductive path when the first overcurrent detection unit detects the first overcurrent state, and determines that the abnormal state is on the low-voltage battery side of the intermediate conductive path when the second overcurrent detection unit detects the second overcurrent state.

[0025] (8) The power distribution device can thoroughly determine abnormal conditions on the voltage conversion unit side of the intermediate conduction path and on the low-voltage battery side of the intermediate conduction path using the first overcurrent detection unit and the second overcurrent detection unit, even if a low-voltage state is not detected.

[0026] (9) The control unit controls the first switch unit and the fourth switch unit, and when the abnormality determination unit determines that the voltage conversion unit side of the intermediate conduction path is in the abnormal state, controls the first switch unit to an off state and controls the fourth switch unit to an on state, and when the abnormality determination unit determines that the low-voltage battery side of the intermediate conduction path is in the abnormal state, controls the fourth switch unit to an off state and controls the first switch unit to an on state. This is the power distribution device described in (7) or (8).

[0027] The power distribution device (9) can continue to supply power to the load while suppressing the effects of the abnormal state.

[0028] (10) The power distribution device according to (5), wherein the first switch unit and the fourth switch unit are semiconductor switches having parasitic diodes, the first switch unit allows current to flow from the voltage conversion unit to the intermediate conduction path via at least the parasitic diode, and the fourth switch unit allows current to flow from the low-voltage battery to the intermediate conduction path via at least the parasitic diode.

[0029] The power distribution device of (10) can be configured to supply power to the important load via a parasitic diode even if the first switch unit and the fourth switch unit are switched to the off state at the same time.

[0030] (11) The control unit controls the third switch unit and the fourth switch unit, and when the abnormality determination unit determines that the abnormal state exists, controls the third switch unit to an off state. This is a power distribution device described in (6).

[0031] The power distribution device (11) can be used while saving power from the low-voltage battery by stopping the power supply to the general load when an abnormal state occurs.

[0032] (12) The power distribution device according to (6), comprising: a first overheat detection unit that detects a first overheat state based on the temperature of the first switch unit; a second overheat detection unit that detects a second overheat state based on the temperature of the fourth switch unit; and a control unit that controls the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit, wherein the control unit, when the first overheat state is detected by the first overheat detection unit, controls the first switch unit to an off state and controls the second switch unit, the third switch unit, and the fourth switch unit to an on state, and when the second overheat state is detected by the second overheat detection unit, controls the fourth switch unit to an off state and controls the first switch unit, the second switch unit, and the third switch unit to an on state.

[0033] The power distribution device of (12) controls either the first switch unit or the fourth switch unit to the off state based on whether the first switch unit or the fourth switch unit is in an overheated state even if the voltage conversion unit side of the intermediate conduction path and the low-voltage battery side of the intermediate conduction path are not in an abnormal state, making it easier to supply power to important loads more stably.

[0034] (13) The power distribution device according to (12), further comprising: a drop detection unit that detects that the potential of the fourth conductive path is in a drop state; and a notification unit that notifies the outside of the drop state, wherein when the first overheat detection unit does not detect the first overheat state and the second overheat detection unit does not detect the second overheat state, the control unit controls the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit to an on state when the potential is in the drop state, and the notification unit notifies the outside of the drop state when the potential is in the drop state.

[0035] The power distribution device of (13) supplies power to important loads and general loads when no abnormal condition or overheating occurs, but the notification unit notifies in advance that the potential of the fourth conduction path has decreased, making it easy to take measures such as maintenance before an abnormal condition or overheating occurs.

[0036] 1 is a system mounted on a vehicle. The vehicle system 100 includes a high-voltage battery 90, a voltage conversion unit 92, a low-voltage battery 91, a load 70, and a power distribution device 10. The vehicle system 100 supplies power based on the high-voltage battery 90 and the low-voltage battery 91 to the load 70 via the power distribution device 10.

[0037] The high-voltage battery 90 is, for example, a battery pack formed by connecting a plurality of unit cells, such as lithium-ion batteries or nickel-metal hydride batteries, in series, and outputs an output voltage of, for example, about 400 V. The voltage conversion unit 92 is a known DC-DC converter capable of stepping down and converting the voltage of the high-voltage battery 90. The low-voltage battery 91 can be, for example, a lead-acid battery, or a configuration using the same type of unit cells as the high-voltage battery 90 but with fewer cells connected in series than the high-voltage battery 90. For example, the low-voltage battery 91 can output an output voltage of about 12 V.

[0038] The load 70 includes an important load 71 and a general load 72. The important load 71 is a load with a higher level of importance than the general load 72. The level of importance is determined based on the functional safety level specified in ISO 26262, for example. The functional safety levels are classified into five levels, from lowest to highest: QM (Quality Management), ASIL (Automotive Safety Integrity Level)-A, ASIL-B, ASIL-C, and ASIL-D. The higher the functional safety level assigned to a load, the higher the level of importance. In this embodiment, the load to which an ASIL (i.e., ASIL-A to ASIL-D) is assigned is the important load 71. The important load 71 is, for example, an ECU (Electronic Control Unit) of an electric brake device, an ECU of a shift-by-wire device, an ECU of a door lock device, a display device, an ECU of an airbag device, a DCM (Data Communication Module), and the like.

[0039] The general load 72 is a load that is less important than the important load 71. The general load 72 is a load that does not affect the safety of the vehicle even if it does not operate while the vehicle is running, and corresponds to, for example, a seat heater or a USB power supply.

[0040] [Configuration of the Power Distribution Device] The power distribution device 10 includes a housing 97, a terminal 81, a conductive path 80, a switch 82, a potential detection unit 87, a current detection unit 88, a low potential detection unit 83, a low current detection unit 84, an abnormality determination unit 85, a control unit 86, and a notification unit 89. The housing 97 is formed as a box with an internal storage space. The terminal 81 includes a first terminal 81A, a second terminal 81B, a third terminal 81C, and a fourth terminal 81D. These terminals 81 are provided on a wall portion forming the housing 97 so as to face both the inside and outside of the housing 97. The first terminal 81A is electrically connected to a voltage conversion unit 92, and power is supplied from the voltage conversion unit 92. The second terminal 81B is electrically connected to an important load 71. The third terminal 81C is electrically connected to a general load 72. The fourth terminal 81D is electrically connected to a positive terminal of a low-voltage battery 91. That is, the fourth terminal 81D is configured to receive power from the low-voltage battery 91.

[0041] In the present disclosure, "electrically connected" preferably refers to a configuration in which the connection targets are connected in a mutually conductive state (a state in which a current can flow) so that the potentials of both connection targets are equal. However, this configuration is not limited to this. For example, "electrically connected" may also refer to a configuration in which the connection targets are connected in a state in which the two connection targets can be electrically connected with an electrical component interposed between them.

[0042] The conductive path 80 includes a first conductive path 80A, a second conductive path 80B, a third conductive path 80C, a fourth conductive path 80D, and an intermediate conductive path 80E. The conductive path 80 is housed in a housing 97. The first conductive path 80A is electrically connected to a first terminal 81A. The second conductive path 80B is electrically connected to a second terminal 81B. The third conductive path 80C is electrically connected to a third terminal 81C. The fourth conductive path 80D is electrically connected to a fourth terminal 81D. The intermediate conductive path 80E is electrically connected to the first conductive path 80A, the second conductive path 80B, the third conductive path 80C, and the fourth conductive path 80D via a switch 82 (described later).

[0043] The switch 82 has a first switch section 82A, a second switch section 82B, a third switch section 82C, and a fourth switch section 82D. Each of the first switch section 82A, the second switch section 82B, the third switch section 82C, and the fourth switch section 82D is configured with a semiconductor switch such as a field effect transistor (FET). Each switch 82 has a parasitic diode.

[0044] The first switch unit 82A is provided between the first conductive path 80A and the intermediate conductive path 80E. The first switch unit 82A has a parasitic diode 82E. The anode of the parasitic diode 82E is connected to the first conductive path 80A on the voltage conversion unit 92 side, and the cathode is connected to the intermediate conductive path 80E. The first switch unit 82A switches between an ON state, which allows current to flow in both directions between the voltage conversion unit 92 side and the intermediate conductive path 80E, and an OFF state, which blocks current flowing from the intermediate conductive path 80E to the voltage conversion unit 92. The first switch unit 82A allows current to flow from the voltage conversion unit 92 to the intermediate conductive path 80E at least via the parasitic diode 82E.

[0045] The second switch unit 82B is provided between the second conductive path 80B and the intermediate conductive path 80E. The second switch unit 82B switches between an ON state that allows conduction between the second conductive path 80B and the intermediate conductive path 80E and an OFF state that blocks conduction between them.

[0046] The third switch unit 82C is provided between the third conductive path 80C and the intermediate conductive path 80E. The third switch unit 82C switches between an ON state that allows conduction between the intermediate conductive path 80E and the third conductive path 80C, and an OFF state that blocks conduction between them.

[0047] The fourth switch unit 82D is provided between the fourth conduction path 80D and the intermediate conduction path 80E. The fourth switch unit 82D has a parasitic diode 82F. The anode of the parasitic diode 82F is connected to the fourth conduction path 80D on the low-voltage battery 91 side, and the cathode of the parasitic diode 82F is connected to the intermediate conduction path 80E. The fourth switch unit 82D switches between an ON state, which allows current to flow in both directions between the intermediate conduction path 80E and the low-voltage battery 91, and an OFF state, which blocks current from flowing from the intermediate conduction path 80E to the low-voltage battery 91. The fourth switch unit 82D allows current to flow from the low-voltage battery 91 to the intermediate conduction path 80E at least via the parasitic diode 82F. The fourth conduction path 80D transmits power from the low-voltage battery 91, supplied from the fourth terminal 81D, to the intermediate conduction path 80E.

[0048] The potential detection unit 87 has a first potential detection unit 87A and a second potential detection unit 87B. The first potential detection unit 87A is provided on the intermediate conductive path 80E. The first potential detection unit 87A can detect the potential of the intermediate conductive path 80E. The first potential detection unit 87A is configured as, for example, a known potential detection circuit. The first potential detection unit 87A outputs a signal V1 (hereinafter also simply referred to as signal V1) that can identify the detected potential of the intermediate conductive path 80E.

[0049] The second potential detector 87B is provided on the first conductive path 80A. The second potential detector 87B can detect the potential of the first conductive path 80A. The second potential detector 87B is configured as a known potential detection circuit similar to the first potential detector 87A. The second potential detector 87B outputs a signal V2 (hereinafter simply referred to as signal V2) that can identify the detected potential of the first conductive path 80A.

[0050] The current detection unit 88 has a first current detection unit 88A. The first current detection unit 88A is provided in the first conductive path 80A. The first current detection unit 88A can detect the current flowing through the first conductive path 80A and the direction of the current flow in the first conductive path 80A. The first current detection unit 88A is configured as a known current detection circuit using, for example, a current transformer and a shunt resistor. The first current detection unit 88A outputs a signal A1 (hereinafter simply referred to as signal A1) that can identify the magnitude and direction of the detected current.

[0051] The low potential detection unit 83 includes a first low potential detection unit 83A. The first low potential detection unit 83A receives a signal V1 from the first potential detection unit 87A. The first low potential detection unit 83A compares the signal V1 with a first potential threshold and, when the signal V1 is smaller than the first potential threshold, outputs a low potential signal Lv1 indicating a low potential state, i.e., a first low potential state. The first low potential detection unit 83A detects the first low potential state based on the potential of the intermediate conductive path 80E. For example, the first potential threshold is set to a value smaller than the output voltage (12 V) of the low-voltage battery 91. The first low potential detection unit 83A may be implemented, for example, by a comparator.

[0052] The low current detection unit 84 includes a first low current detection unit 84A. The first low current detection unit 84A receives a signal A1 from the first current detection unit 88A. The first low current detection unit 84A compares the signal A1 with a first current threshold, and when the signal A1 is smaller than the first current threshold, outputs a low current signal Lc1 indicating a low current state. The low current signal Lc1 includes a signal indicating the direction of current flowing through the first conductive path 80A. For example, the first current threshold is set to a value slightly greater than the value indicating 0 A (amperes). The first low current detection unit 84A may be implemented, for example, by a comparator.

[0053] The abnormality determination unit 85 is configured by, for example, an MCU (Micro Controller Unit). The abnormality determination unit 85 receives a signal V1 from a first potential detection unit 87A, a signal V2 from a second potential detection unit 87B, a low potential signal Lv1 from a first low potential detection unit 83A, and a low current signal Lc1 from a first low current detection unit 84A. The abnormality determination unit 85 determines whether the voltage conversion unit 92 side of the intermediate conductive path 80E is in an abnormal state (open state) based on the potential difference between the potential of the first conductive path 80A (signal V2) and the potential of the intermediate conductive path 80E (signal V1) and the input of the low current signal Lc1. Here, the open state on the voltage conversion unit 92 side relative to the intermediate conductive path 80E corresponds to a state in which a switch element constituting the voltage conversion unit 92 remains off and does not switch on, making it impossible to convert power from the high-voltage battery 90 and provide it to the first conductive path 80A side, a state in which the first conductive path 80A is disconnected, or a state in which there is a disconnection between the high-voltage battery 90 and the voltage conversion unit 92. When the abnormality determination unit 85 determines that an abnormal state exists on the voltage conversion unit 92 side relative to the intermediate conductive path 80E, it is configured to output an abnormality signal Sg1 indicating that an abnormal state exists on the voltage conversion unit 92 side relative to the intermediate conductive path 80E. Furthermore, when the low potential signal Lv1 is input, the abnormality determination unit 85 is configured to output the low potential signal Lv1 as is.

[0054] The control unit 86 is configured by, for example, an MCU (Micro Controller Unit). The control unit 86 is configured to receive an abnormality signal Sg1 and a low potential signal Lv1 from the abnormality determination unit 85. Based on these signals (Sg1, Lv1), the control unit 86 can control the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to switch between an ON state and an OFF state.

[0055] The notification unit 89 is configured, for example, as a part of the control unit 86. When an abnormality signal Sg1 is input from the abnormality determination unit 85 to the control unit 86, the notification unit 89 is configured to output an abnormality notification signal Sg2 to an external device such as an external ECU (not shown) and notify the user of the vehicle or the like that the voltage conversion unit 92 is in an open state.

[0056] [Example of Operation of Power Distribution Device] Next, an example of operation of the power distribution device 10 will be described with reference to Figures 2, 3, and 4. For example, when a vehicle equipped with the in-vehicle system 100 is traveling, the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D are each controlled by the control unit 86 to be maintained in an on state. While the vehicle is traveling, the power distribution device 10 periodically monitors the potential (signal V1) of the intermediate conductive path 80E, the potential (signal V2) of the first conductive path 80A, and the current (signal A1) flowing through the first conductive path 80A. "Periodic monitoring" corresponds to repeatedly executing the flowcharts of Figures 2, 3, and 4 at predetermined intervals.

[0057] First, in step S1, the abnormality determination unit 85 determines whether the potential of the intermediate conductive path 80E has been continuously dropped for a predetermined time or more. Specifically, the first low potential detection unit 83A outputs a low potential signal Lv1 to the abnormality determination unit 85 when the signal V1 is equal to or lower than the first potential threshold. The abnormality determination unit 85 determines that the potential of the intermediate conductive path 80E has been dropped while the low potential signal Lv1 is being input. For example, the abnormality determination unit 85 uses its own timer function to determine whether the low potential signal Lv1 has been continuously input for the predetermined time (i.e., whether the dropped potential of the intermediate conductive path 80E has been continuously present for the predetermined time).

[0058] In step S1, if the abnormality determination unit 85 determines that the low potential signal Lv1 has continued for a predetermined time (Yes in step S1), the process proceeds to step S2. In step S2, the low potential signal Lv1 is output from the abnormality determination unit 85 to the control unit 86. Based on the input of the low potential signal Lv1, the control unit 86 switches the first switch unit 82A to the OFF state. In this way, based on the input of the low potential signal Lv1 (i.e., the detection of a low potential state by the first low potential detection unit 83A), the control unit 86 controls the first switch unit 82A to the OFF state. In step S1, if the abnormality determination unit 85 determines that the low potential signal Lv1 has not continued for a predetermined time (No in step S1), the process shown in FIG. 2 is terminated and the process shown in FIG. 2 is executed again.

[0059] In step S3, the abnormality determination unit 85 determines whether a predetermined potential difference exists between the potential of the first conductive path 80A (signal V2) and the potential of the intermediate conductive path 80E (signal V1). For example, the abnormality determination unit 85 calculates the potential difference between the first conductive path 80A and the intermediate conductive path 80E from the input signals V1 and V2, and compares the calculated potential difference with a potential difference threshold stored in its own ROM. In step S3, if the abnormality determination unit 85 determines that a predetermined potential difference exists between the potential of the first conductive path 80A (signal V2) and the potential of the intermediate conductive path 80E (signal V1) (Yes in step S3), the abnormality determination unit 85 proceeds to step S4.

[0060] When the process proceeds to step S4, the abnormality determination unit 85 sets the potential drop flag to 1. For example, the potential drop flag is configured as part of a RAM included in the abnormality determination unit 85. The potential drop flag is set to 0 in advance. In step S3, the abnormality determination unit 85 determines that a predetermined potential difference does not occur between the potential of the first conductive path 80A (signal V2) and the potential of the middle conductive path 80E (signal V1) (No in step S3). Then, the process shown in FIG. 2 is terminated, and the process shown in FIG. 2 is executed again.

[0061] The abnormality determination unit 85 executes the process shown in FIG. 3 in parallel with the process shown in FIG. 2 . In step S11, the abnormality determination unit 85 determines whether a current has been continuously flowing through the first electrical conduction path 80A for a predetermined period of time. For example, the abnormality determination unit 85 uses its own timer function to determine whether a low current signal Lc1 has been continuously input from the first low current detection unit 84A for a predetermined period of time. If the abnormality determination unit 85 determines in step S11 that no current has been continuously flowing through the first electrical conduction path 80A for a predetermined period of time (No in step S11) (i.e., the low current signal Lc1 has been continuously input for a predetermined period of time), the process proceeds to step S12, where a current stop flag is set to 1. For example, the current stop flag is configured as part of a RAM included in the abnormality determination unit 85. The current stop flag is preset to 0. In step S11, if the abnormality determination unit 85 determines that a current has been flowing continuously through the first conductive path 80A for a predetermined time (Yes in step S11) (i.e., the low current signal Lc1 has not been input continuously for a predetermined time), the process shown in FIG. 3 is terminated and the process shown in FIG. 3 is executed again.

[0062] 2 and 3, the abnormality determination unit 85 executes the process shown in Fig. 4. In step S21 shown in Fig. 4, the abnormality determination unit 85 determines whether the potential drop flag and the current stop flag are both set to 1. In step S21, the abnormality determination unit 85 determines that the potential drop flag and the current stop flag are both set to 1 (Yes in step S21). Then, the process proceeds to step S22, where the abnormality determination unit 85 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state, and outputs an abnormality signal Sg1 to the control unit 86.

[0063] In step S23, the control unit 86 switches the third switch unit 82C to the OFF state based on the abnormality signal Sg1, which indicates that the voltage conversion unit 92 is in an abnormal state, input from the abnormality determination unit 85. Then, in step S24, the notification unit 89 outputs the abnormality notification signal Sg2 to the external device. Thus, when the first low current detection unit 84A detects a low current state and the potential difference between the first conductive path 80A and the intermediate conductive path 80E is equal to or greater than the potential difference threshold, the abnormality determination unit 85 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state. This completes the process shown in FIG. 4 .

[0064] 5 , the vehicle equipped with the in-vehicle system 100 is traveling, and the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D are each maintained in an on state by the control unit 86. At time T0, a current (signal A1) of a predetermined magnitude is supplied from the voltage conversion unit 92 to the first conductive path 80A, and the potential (signal V2) of the first conductive path 80A and the potential (signal V1) of the intermediate conductive path 80E are the same value of a predetermined magnitude.

[0065] At time T1, when the voltage converter 92 side of the intermediate conductive path 80E becomes open, the supply of current from the voltage converter 92 to the first conductive path 80A stops, and the signal A1 changes to a value indicating 0. At time T1, the abnormality determination unit 85 starts its timer function and begins measuring the time during which no current flows through the first conductive path 80A (step S11 in FIG. 3 ). Specifically, when the signal A1 from the first current detection unit 88A changes to a value indicating 0 and becomes equal to or less than the first current threshold, the first low current detection unit 84A begins outputting the low current signal Lc1 to the abnormality determination unit 85. The abnormality determination unit 85 begins measuring the time when the low current signal Lc1 is input. When a predetermined time has elapsed since no current flows through the first conductive path 80A, the abnormality determination unit 85 sets the current stop flag to 1 (step S12 in FIG. 3 ).

[0066] The power distribution device 10 is configured to immediately begin supplying power from the low-voltage battery 91 when the voltage conversion unit 92 side of the intermediate conductive path 80E enters an open state. After time T1, the potentials of the first conductive path 80A and the intermediate conductive path 80E gradually decrease. In other words, when the voltage conversion unit 92 side of the intermediate conductive path 80E enters an open state, the signals V1 and V2 gradually decrease after time T1. At time T1, the abnormality determination unit 85 begins measuring the time during which the potential of the intermediate conductive path 80E remains decreased (step S1 in FIG. 2 ). Specifically, when the signal V1 from the first potential detection unit 87A becomes equal to or lower than the first potential threshold, the first low potential detection unit 83A outputs a low potential signal Lv1 to the abnormality determination unit 85. When the abnormality determination unit 85 determines that the low potential signal Lv1 has been continuously input for a predetermined time or more (i.e., the potential of the intermediate conductive path 80E has been continuously dropping for a predetermined time), it outputs the low potential signal Lv1 to the control unit 86. Then, based on the input of the low potential signal Lv1, the control unit 86 controls the first switch unit 82A to the OFF state at time T2 (step S2 in FIG. 2).

[0067] When the first switch unit 82A is controlled to the off state, conduction between the first conductive path 80A and the intermediate conductive path 80E is interrupted. As a result, from time T2 onward, the potential of the intermediate conductive path 80E (signal V1) gradually increases, and the potential of the first conductive path 80A (signal V2) suddenly decreases. When the potential difference between the potential of the first conductive path 80A (signal V2) and the potential of the intermediate conductive path 80E (signal V1) becomes greater than the potential difference threshold (step S3 in FIG. 2 ), the abnormality determination unit 85 sets the potential decrease flag to 1 (step S4 in FIG. 2 ).

[0068] If the abnormality determination unit 85 determines that both the potential drop flag and the current stop flag are set to 1 after time T2 has elapsed (step S21 in FIG. 4), it determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state (step S22 in FIG. 4). The abnormality determination unit 85 then outputs an abnormality signal Sg1 to the control unit 86. Thereafter, at time T3, the control unit 86 switches the third switch unit 82C to the OFF state (step S23 in FIG. 4). At the same time, the notification unit 89 outputs an abnormality notification signal Sg2 to the external device (step S24 in FIG. 4).

[0069] Next, the effects of this configuration will be illustrated. The power distribution device 10 is included in an in-vehicle system 100 that includes a high-voltage battery 90, a voltage conversion unit 92 that converts and outputs a voltage input from the high-voltage battery 90, a low-voltage battery 91, an important load 71, and a general load 72 that is less important than the important load 71. The power distribution device 10 includes a first terminal 81A, a second terminal 81B, a third terminal 81C, a fourth terminal 81D, a first conductive path 80A, a second conductive path 80B, a third conductive path 80C, a fourth conductive path 80D, an intermediate conductive path 80E, a first switch unit 82A, a second switch unit 82B, and a third switch unit 82C. The first terminal 81A receives power from the voltage conversion unit 92. The important load 71 is connected to the second terminal 81B. The general load 72 is connected to the third terminal 81C. The fourth terminal 81D is supplied with power from the low-voltage battery 91. The first conductive path 80A is connected to the first terminal 81A. The second conductive path 80B is connected to the second terminal 81B. The third conductive path 80C is connected to the third terminal 81C. The fourth conductive path 80D is connected to the fourth terminal 81D. The first switch unit 82A is provided between the first conductive path 80A and the intermediate conductive path 80E. The second switch unit 82B is provided between the second conductive path 80B and the intermediate conductive path 80E. The third switch unit 82C is provided between the third conductive path 80C and the intermediate conductive path 80E. The fourth conductive path 80D transmits power supplied from the fourth terminal 81D to the intermediate conductive path 80E.

[0070] When the first switch unit 82A, the second switch unit 82B, and the third switch unit 82C are in the on state, the power distribution device 10 can supply power from the voltage conversion unit 92 to the important load 71 and the general load 72. When the first switch unit 82A is in the off state, power supply from the voltage conversion unit 92 can be stopped and power can be supplied from the low-voltage battery 91 to the important load 71 and the general load 72. Then, by turning off the third switch unit 82C in addition to the first switch unit 82A, a configuration can be realized in which power from the low-voltage battery 91 is supplied only to the important load 71 while saving power from the low-voltage battery 91.

[0071] The power distribution device 10 includes a first low potential detection unit 83A, a control unit 86, and an abnormality determination unit 85. The first low potential detection unit 83A detects a low potential state based on the potential of the intermediate conductive path 80E. The control unit 86 controls the first switch unit 82A to an off state when the first low potential detection unit 83A detects a low potential state. The abnormality determination unit 85 determines whether the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state (abnormal state) based on the potential difference between the first conductive path 80A and the potential of the intermediate conductive path 80E. With this configuration, the abnormality determination unit 85 can determine whether the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state.

[0072] The power distribution device 10 includes a first low-current detection unit 84A that detects a low-current state based on a current flowing through the first conductive path 80A. The abnormality determination unit 85 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state when the first low-current detection unit 84A detects a low-current state and the potential difference between the first conductive path 80A and the intermediate conductive path 80E is equal to or greater than a potential difference threshold. With this configuration, the abnormality determination unit 85 can increase the reliability of determining whether the voltage conversion unit 92 is in an open state by detecting the current flowing through the first conductive path 80A and the potential difference between the first conductive path 80A and the intermediate conductive path 80E.

[0073] In the power distribution device 10, the first switch unit 82A and the fourth switch unit 82D are semiconductor switches having parasitic diodes 82E and 82F. The first switch unit 82A allows current to flow from the voltage conversion unit 92 to the intermediate conduction path 80E via at least the parasitic diode 82E. The fourth switch unit 82D allows current to flow from the low-voltage battery 91 to the intermediate conduction path 80E via at least the parasitic diode 82F. This configuration makes it possible to supply power to the important load 71 via the parasitic diodes 82E and 82F even if the first switch unit 82A and the fourth switch unit 82D are switched to the off state simultaneously.

[0074] The control unit 86 controls the third switch unit 82C and the fourth switch unit 82D, and when the abnormality determination unit 85 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in an open state (abnormal state), the control unit 86 controls the third switch unit 82C to the off state. With this configuration, when an abnormal state occurs, the power supply to the general load 72 is stopped, and the power of the low-voltage battery 91 can be used while conserving it.

[0075] 6 differs from the first embodiment in that the power distribution device 20 includes a third potential detection unit 87C in addition to a first potential detection unit 87A and a second potential detection unit 87B, a second current detection unit 88B in addition to a first current detection unit 88A, a second low potential detection unit 83B and a third low potential detection unit 83C in addition to a first low potential detection unit 83A, a drop detection unit 96, an overcurrent detection unit 184 instead of a low current detection unit 84, a temperature detection unit 93, and an overheat detection unit 94, but is otherwise common. In the following description, the same components as those in the in-vehicle system 100 of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0076] The power distribution device 20 has a housing 97, a terminal 81, a conductive path 80, a switch 82, a potential detection unit 87, a current detection unit 88, a low potential detection unit 83, an overcurrent detection unit 184, an abnormality determination unit 185, a control unit 86, and a notification unit 89.

[0077] The potential detection unit 87 has a first potential detection unit 87A, a second potential detection unit 87B, and a third potential detection unit 87C. The third potential detection unit 87C is provided on the fourth conductive path 80D. The third potential detection unit 87C can detect the potential of the fourth conductive path 80D. The third potential detection unit 87C is configured as a known potential detection circuit similar to the first potential detection unit 87A. The third potential detection unit 87C outputs a signal V3 (hereinafter simply referred to as signal V3) that can identify the detected potential of the fourth conductive path 80D.

[0078] The current detection unit 88 has a first current detection unit 88A and a second current detection unit 88B. The second current detection unit 88B is provided in the fourth conductive path 80D. The second current detection unit 88B can detect the current flowing through the fourth conductive path 80D and the direction of the current flow in the fourth conductive path 80D. The second current detection unit 88B is configured as a known current detection circuit similar to the first current detection unit 88A. The second current detection unit 88B outputs a signal A2 (hereinafter simply referred to as signal A2) that can identify the magnitude and direction of the detected current.

[0079] The low potential detection unit 83 includes a first low potential detection unit 83A, a second low potential detection unit 83B, and a third low potential detection unit 83C. The second low potential detection unit 83B receives a signal V2 from the second potential detection unit 87B. The second low potential detection unit 83B compares the signal V2 with a first potential threshold, and when the signal V2 is smaller than the first potential threshold, outputs a low potential signal Lv2 indicating a low potential state and a second low potential state. The second low potential detection unit 83B detects the second low potential state based on the potential of the first conductive path 80A. A comparator, for example, is used as the second low potential detection unit 83B.

[0080] The third low potential detector 83C receives the signal V3 from the third potential detector 87C. The third low potential detector 83C compares the signal V3 with a first potential threshold and, when the signal V3 is smaller than the first potential threshold, outputs a low potential signal Lv3 indicating a low potential state, i.e., a third low potential state. The third low potential detector 83C detects the third low potential state based on the potential of the fourth conductive path 80D. For example, a comparator is used as the third low potential detector 83C. In this way, the low potential detector 83C detects the low potential state based on at least one of the potential of the first conductive path 80A (signal V2), the potential of the fourth conductive path 80D (signal V3), and the potential of the intermediate conductive path 80E (signal V1).

[0081] The drop detector 96 receives the signal V3 from the third potential detector 87C. The drop detector 96 compares the signal V3 with a second potential threshold and outputs a drop signal Ds indicating a drop state when the signal V3 is smaller than the second potential threshold. For example, the second potential threshold is set to be smaller than the output voltage of the low-voltage battery 91 and larger than the first potential threshold. The drop detector 96 detects a drop state in which the potential (signal V3) of the fourth conductive path 80D is larger than the first potential threshold but smaller than the second potential threshold. The drop detector 96 may be, for example, a comparator. The drop detector 96 detects the drop state based on the potential (signal V3) of the fourth conductive path 80D.

[0082] The overcurrent detection unit 184 includes a first overcurrent detection unit 184A and a second overcurrent detection unit 184B. The first overcurrent detection unit 184A receives a signal A1 from the first current detection unit 88A. When the signal A1 indicates that a current is flowing from the intermediate conductive path 80E to the first conductive path 80A, the first overcurrent detection unit 184A compares the signal A1 with a second current threshold. When the signal A1 is greater than the second current threshold, the first overcurrent detection unit 184A outputs an overcurrent signal Oc1 indicating a first overcurrent state. The overcurrent signal Oc1 indicates that a current is flowing from the intermediate conductive path 80E to the first conductive path 80A. For example, the second current threshold is set to a value greater than the maximum current value flowing through the intermediate conductive path 80E while the vehicle is traveling. The first overcurrent detection unit 184A includes, for example, a comparator.

[0083] The second overcurrent detection unit 184B receives a signal A2 from the second current detection unit 88B. When the signal A2 indicates that a current is flowing from the intermediate conductive path 80E to the fourth conductive path 80D, the second overcurrent detection unit 184B compares the signal A2 with a second current threshold. When the signal A2 is greater than the second current threshold, the second overcurrent detection unit 184B is configured to output an overcurrent signal Oc2 indicating an overcurrent state, which is a second overcurrent state. The overcurrent signal Oc2 indicates that a current is flowing from the intermediate conductive path 80E to the fourth conductive path 80D. The second overcurrent detection unit 184B may be implemented, for example, by a comparator.

[0084] The temperature detection unit 93 includes a first temperature detection unit 93A and a second temperature detection unit 93B. The first temperature detection unit 93A and the second temperature detection unit 93B are each configured to output a temperature signal indicating the temperature at the location where the temperature detection unit 93 is installed. The first temperature detection unit 93A is located near the first switch unit 82A. The first temperature detection unit 93A outputs a signal T1 (hereinafter simply referred to as signal T1) that can identify the temperature of the first switch unit 82A. The second temperature detection unit 93B is located near the fourth switch unit 82D. The second temperature detection unit 93B outputs a signal T2 (hereinafter simply referred to as signal T2) that can identify the temperature of the fourth switch unit 82D.

[0085] The overheat detection unit 94 includes a first overheat detection unit 94A and a second overheat detection unit 94B. The first overheat detection unit 94A receives a signal T1 from the first temperature detection unit 93A. The first overheat detection unit 94A compares the signal T1 with a temperature threshold, and when the signal T1 is greater than the temperature threshold, outputs an overheat signal Oh1 indicating an overheat state, or a first overheat state. In other words, the first overheat detection unit 94A detects the first overheat state based on the temperature of the first switch unit 82A. For example, a comparator is used as the first overheat detection unit 94A.

[0086] The second overheat detection unit 94B receives the signal T2 from the second temperature detection unit 93B. The second overheat detection unit 94B compares the signal T2 with a temperature threshold value, and when the signal T2 is greater than the temperature threshold value, outputs an overheat signal Oh2 indicating an overheat state, or a second overheat state. In other words, the second overheat detection unit 94B detects the second overheat state based on the temperature of the fourth switch unit 82D. The second overheat detection unit 94B may be, for example, a comparator.

[0087] The abnormality determination unit 185 is configured to be, for example, an MCU (Micro Controller Unit). The abnormality determination unit 185 is configured to receive a low potential signal Lv1 from the first low potential detection unit 83A, a low potential signal Lv2 from the second low potential detection unit 83B, and a low potential signal Lv3 from the third low potential detection unit 83C. Furthermore, the abnormality determination unit 185 is configured to receive an overcurrent signal Oc1 from the first overcurrent detection unit 184A and an overcurrent signal Oc2 from the second overcurrent detection unit 184B.

[0088] When the low potential detection unit 83 detects a low potential state and the first overcurrent detection unit 184A detects a first overcurrent state, the abnormality determination unit 185 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in a second abnormal state (i.e., an abnormal state). Here, the second abnormal state on the voltage conversion unit 92 side of the intermediate conductive path 80E corresponds to a ground fault in a switch element constituting the voltage conversion unit 92, a ground fault in the first conductive path 80A, a ground fault between the high-voltage battery 90 and the voltage conversion unit 92, or a ground fault in the high-voltage battery 90. Furthermore, when the low potential detection unit 83 detects a low potential state and the second overcurrent detection unit 184B detects a second overcurrent state, the abnormality determination unit 185 determines that the low-voltage battery 91 side of the intermediate conductive path 80E is in the second abnormal state. Here, the second abnormal state on the low-voltage battery 91 side of the intermediate conductive path 80E corresponds to a state in which a ground fault occurs in the fourth conductive path 80D or a state in which a ground fault occurs in the low-voltage battery 91. In other words, the second abnormal state is a ground fault state.

[0089] When the abnormality determination unit 185 determines that the second abnormal state is occurring on the voltage conversion unit 92 side of the intermediate conductive path 80E, it can output a second abnormality signal Sg3 indicating that the second abnormal state is occurring on the voltage conversion unit 92 side of the intermediate conductive path 80E. Furthermore, when the abnormality determination unit 185 determines that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E, it can output a second abnormality signal Sg4 indicating that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E.

[0090] The control unit 86 is configured to receive the second abnormality signals Sg3 and Sg4 from the abnormality determination unit 185, the overheat signal Oh1 from the first overheat detection unit 94A, the overheat signal Oh2 from the second overheat detection unit 94B, and the drop signal Ds from the drop detection unit 96. The control unit 86 can control each of the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to switch between an ON state and an OFF state based on the second abnormality signals Sg3 and Sg4, the overheat signals Oh1 ​​and Oh2, and the drop signal Ds.

[0091] When the second abnormality signals Sg3, Sg4, the overheat signals Oh1, Oh2, and the drop signal Ds are input to the control unit 86, the notification unit 89 outputs second abnormality notification signals Sg5, Sg6, overheat notification signals Sg7, Sg8, and drop notification signal Sg9 to an external device such as an external ECU (not shown). In this way, the notification unit 89 is configured to notify the user of the vehicle that the second abnormality state is occurring on the voltage conversion unit 92 side of the intermediate conductive path 80E or the low-voltage battery 91 side of the intermediate conductive path 80E, that the first switch unit 82A or the fourth switch unit 82D is in an overheated state, or that the potential of the fourth conductive path 80D is in a drop state.

[0092] [Example of Operation of Power Distribution Device] Next, an example of operation of the power distribution device 20 will be described with reference to FIG. 7 . For example, when a vehicle equipped with the in-vehicle system 200 is traveling, the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D are each controlled by the control unit 86 to be maintained in an on state. While the vehicle is traveling, the power distribution device 20 periodically monitors the potential (signal V1) of the intermediate conductive path 80E, the potential (signal V2) of the first conductive path 80A, the potential (signals V3 and Ds) of the fourth conductive path 80D, the current (signal A1) flowing through the first conductive path 80A, the current (signal A2) flowing through the fourth conductive path 80D, the temperature (signal T1) of the first switch unit 82A, and the temperature (signal T2) of the fourth switch unit 82D. Periodic monitoring corresponds to repeatedly executing the flowchart of FIG. 7 at predetermined intervals.

[0093] First, in step S31, the abnormality determination unit 185 determines whether the potential (signal V1) of the intermediate conductive path 80E, the potential (signal V2) of the first conductive path 80A, and the potential (signal V3) of the fourth conductive path 80D are equal to or lower than a first potential threshold, and whether the current (signal A1) flowing through the first conductive path 80A and the current (signal A2) flowing through the fourth conductive path 80D are equal to or higher than a second current threshold. Specifically, the abnormality determination unit 185 determines whether low potential signals Lv1, Lv2, and Lv3 are input from the first low potential detection unit 83A, the second low potential detection unit 83B, and the third low potential detection unit 83C, and whether overcurrent signals Oc1 and Oc2 are input from the first overcurrent detection unit 184A and the second overcurrent detection unit 184B.

[0094] In step S31, if the abnormality determination unit 185 determines that none of the low potential signals Lv1, Lv2, Lv3 and the overcurrent signals Oc1, Oc2 have been input (No in step S31), the process proceeds to step S40. In step S31, if the abnormality determination unit 185 determines that any one of the low potential signals Lv1, Lv2, Lv3 and the overcurrent signals Oc1, Oc2 has been input (Yes in step S31), the process proceeds to step S32.

[0095] In step S32, the abnormality determination unit 185 determines whether at least one of the potentials of the intermediate conductive path 80E (signal V1), the first conductive path 80A (signal V2), and the fourth conductive path 80D (signal V3) is equal to or lower than the first potential threshold. The first conductive path 80A, the intermediate conductive path 80E, and the fourth conductive path 80D are at the same potential because they are conductive due to the first switch 82A being in the ON state and the fourth switch 82D being in the ON state. Therefore, the abnormality determination unit 185 determines whether at least one of the low potential signals Lv1, Lv2, and Lv3 is being input.

[0096] In step S32, the abnormality determination unit 185 determines that the potential of the intermediate conductive path 80E (signal V1), the potential of the first conductive path 80A (signal V2), and the potential of the fourth conductive path 80D (signal V3) are not equal to or less than the first potential threshold (No in step S32). Then, the process shown in FIG. 7 is terminated, and the process shown in FIG. 7 is executed again. In step S32, the abnormality determination unit 185 determines that at least one of the potential of the intermediate conductive path 80E (signal V1), the potential of the first conductive path 80A (signal V2), and the potential of the fourth conductive path 80D (signal V3) is equal to or less than the first potential threshold (Yes in step S32). Then, the process proceeds to step S33.

[0097] In step S33, the abnormality determination unit 185 determines whether or not an overcurrent is flowing toward the voltage conversion unit 92 (i.e., whether or not the first overcurrent state is occurring). Specifically, the abnormality determination unit 185 determines whether or not the overcurrent signal Oc1 is being input from the first overcurrent detection unit 184A. In step S33, if the abnormality determination unit 185 determines that the overcurrent signal Oc1 is not being input from the first overcurrent detection unit 184A (No in step S33), the abnormality determination unit 185 proceeds to step S37.

[0098] If the abnormality determination unit 185 determines in step S33 that the overcurrent signal Oc1 has been input from the first overcurrent detection unit 184A (i.e., the first overcurrent state exists), the process proceeds to step S34, where the abnormality determination unit 185 determines that the second abnormal state exists on the voltage conversion unit 92 side relative to the intermediate conductive path 80E. At the same time, the abnormality determination unit 185 outputs a second abnormality signal Sg3 to the control unit 86, indicating that the second abnormal state exists on the voltage conversion unit 92 side relative to the intermediate conductive path 80E.

[0099] In step S35, the control unit 86 switches the first switch unit 82A and the third switch unit 82C to the OFF state based on the input of the second abnormality signal Sg3 from the abnormality determination unit 185. At this time, the control unit 86 maintains the second switch unit 82B and the fourth switch unit 82D in the ON state. Then, in step S36, the notification unit 89 outputs a second abnormality notification signal Sg5 to the external device, indicating that the second abnormality state is occurring on the voltage conversion unit 92 side relative to the intermediate conductive path 80E. This completes the processing shown in FIG. 7.

[0100] In step S37, the abnormality determination unit 185 determines whether or not an overcurrent is flowing toward the low-voltage battery 91. Specifically, it determines whether or not the overcurrent signal Oc2 is being input from the second overcurrent detection unit 184B (i.e., whether or not the second overcurrent state is being present). In step S37, if the abnormality determination unit 185 determines that the overcurrent signal Oc2 is not being input from the second overcurrent detection unit 184B (No in step S37), the process shown in FIG. 7 is terminated, and the process shown in FIG. 7 is executed again.

[0101] If the abnormality determination unit 185 determines in step S37 that the overcurrent signal Oc2 has been input from the second overcurrent detection unit 184B (i.e., the second overcurrent state exists), the process proceeds to step S38, where the abnormality determination unit 185 determines that the second abnormal state exists on the low-voltage battery 91 side of the intermediate conductive path 80E. At the same time, the abnormality determination unit 185 outputs a second abnormality signal Sg4 to the control unit 86, indicating that the second abnormal state exists on the low-voltage battery 91 side of the intermediate conductive path 80E.

[0102] In step S39, the control unit 86 switches the fourth switch unit 82D and the third switch unit 82C to the OFF state based on the second abnormality signal Sg4 input from the abnormality determination unit 185. At this time, the control unit 86 maintains the second switch unit 82B and the first switch unit 82A in the ON state. Then, in step S36, the control unit 86 outputs a second abnormality notification signal Sg6 from the notification unit 89 to the external device, indicating that the second abnormality state exists on the side of the low-voltage battery 91 relative to the intermediate conductive path 80E. This ends the processing shown in FIG. 7.

[0103] In step S40, the control unit 86 determines whether the first switch unit 82A is in the first overheat state. Specifically, the control unit 86 determines whether the overheat signal Oh1 is input from the first overheat detection unit 94A. If the control unit 86 determines in step S40 that the overheat signal Oh1 is not input (No in step S40), the control unit 86 proceeds to step S42. If the control unit 86 determines in step S40 that the overheat signal Oh1 is input (Yes in step S40), the control unit 86 proceeds to step S41, where the first switch unit 82A is switched to the OFF state. At this time, the control unit 86 controls the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to maintain the ON state. Then, in step S36, the control unit 89 outputs an overheat notification signal Sg7 to the external device, indicating that the first switch unit 82A is in the overheat state. This completes the process shown in FIG. 7.

[0104] The first overheat state is a state immediately before the voltage conversion unit 92 side of the intermediate conduction path 80E falls into the second abnormal state, and it is estimated that a large current is flowing through the first switch unit 82A. For this reason, steps S40 and S41 are controls to prevent the voltage conversion unit 92 side of the intermediate conduction path 80E from falling into the second abnormal state.

[0105] When the process proceeds to step S42, the control unit 86 determines whether the fourth switch unit 82D is in the second overheat state. Specifically, the control unit 86 determines whether the overheat signal Oh2 is input from the second overheat detection unit 94B. If the control unit 86 determines in step S42 that the overheat signal Oh2 is not input (No in step S42), the process proceeds to step S44. Step S44 is performed when the first overheat detection unit 94A does not detect the first overheat state and the second overheat detection unit 94B does not detect the second overheat state.

[0106] If the control unit 86 determines in step S42 that the overheat signal Oh2 has been input (Yes in step S42), the process proceeds to step S43, where the fourth switch unit 82D is switched to the OFF state. At this time, the control unit 86 controls the first switch unit 82A, the second switch unit 82B, and the third switch unit 82C to maintain their ON states. Then, the process proceeds to step S36, where the notification unit 89 outputs an overheat notification signal Sg8 to the external device, indicating that the fourth switch unit 82D is in an overheat state. This completes the process shown in FIG. 7.

[0107] The second overheat state is a state immediately before the second abnormal state occurs on the low-voltage battery 91 side of the intermediate conduction path 80E, and it is estimated that a large current is flowing through the fourth switch unit 82D. For this reason, steps S42 and S43 are controls to prevent the second abnormal state from occurring on the low-voltage battery 91 side of the intermediate conduction path 80E.

[0108] In step S44, the control unit 86 determines whether the potential of the fourth conductive path 80D is in a decreased state. Specifically, the control unit 86 determines whether a decrease signal Ds has been input from the decrease detection unit 96. In step S44, the control unit 86 determines that a decrease signal Ds has been input from the decrease detection unit 96 (Yes in step S44). The control unit 86 then controls the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to maintain their ON states. The control unit 86 then proceeds to step S36, where the notification unit 89 outputs a decrease notification signal Sg9 indicating that the potential of the fourth conductive path 80D is in a decreased state to the external device. This completes the process shown in FIG. 7 . In step S44, if the control unit 86 determines that a decrease signal Ds has not been input from the decrease detection unit 96 (No in step S44), the process shown in FIG. 7 is completed and the process shown in FIG. 7 is executed again.

[0109] If the low voltage battery 91 has been degraded, it is estimated that the output voltage of the low voltage battery 91 has decreased. Therefore, step S44 is a control for notifying the user of the degradation of the low voltage battery 91 at an early stage.

[0110] The power distribution device 20 includes a low potential detection unit 83, a first overcurrent detection unit 184A, and an abnormality determination unit 185. The low potential detection unit 83 detects a low potential state based on at least one of the potential of the first conductive path 80A, the potential of the fourth conductive path 80D, and the potential of the intermediate conductive path 80E. The first overcurrent detection unit 184A detects a first overcurrent state based on a current flowing from the intermediate conductive path 80E to the first conductive path 80A. When the low potential detection unit 83 detects a low potential state and the first overcurrent detection unit 184A detects the first overcurrent state, the abnormality determination unit 185 determines that a second abnormal state exists on the voltage conversion unit 92 side relative to the intermediate conductive path 80E. According to this configuration, the abnormality determination unit 185 can improve the reliability of determining whether the second abnormal state is occurring on the voltage conversion unit 92 side relative to the intermediate conductive path 80E by detecting the current flowing through the first conductive path 80A and either the potential of the first conductive path 80A, the potential of the fourth conductive path 80D, or the potential of the intermediate conductive path 80E.

[0111] The power distribution device 20 includes a fourth switch unit 82D provided between the fourth conduction path 80D and the intermediate conduction path 80E. With this configuration, when an abnormality occurs on the low-voltage battery 91 side of the intermediate conduction path 80E, the fourth switch unit 82D is switched to the OFF state, making it possible to construct a configuration that prevents the abnormality from propagating to the important load 71, etc.

[0112] The power distribution device 20 includes a low potential detection unit 83, a second overcurrent detection unit 184B, an abnormality determination unit 185, and a control unit 86. The low potential detection unit 83 detects a low potential state based on at least one of the potential of the first conductive path 80A, the potential of the fourth conductive path 80D, and the potential of the intermediate conductive path 80E. The second overcurrent detection unit 184B detects a second overcurrent state based on a current flowing from the intermediate conductive path 80E to the fourth conductive path 80D. The abnormality determination unit 185 determines that a second abnormal state exists on the low-voltage battery 91 side of the intermediate conductive path 80E when the low potential detection unit 83 detects a low potential state and the second overcurrent detection unit 184B detects a second overcurrent state. The control unit 86 controls the fourth switch unit 82D to an off state when the abnormality determination unit 185 determines that a second abnormal state exists. This configuration can prevent the influence of the second abnormal state on the low-voltage battery 91 side of the intermediate conductive path 80E from being transmitted to the important load 71.

[0113] The power distribution device 20 includes a first overheat detection unit 94A, a second overheat detection unit 94B, and a control unit 86. The first overheat detection unit 94A detects a first overheat state based on the temperature of the first switch unit 82A. The second overheat detection unit 94B detects a second overheat state based on the temperature of the fourth switch unit 82D. The control unit 86 controls the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D. When the first overheat state is detected by the first overheat detection unit 94A, the control unit 86 controls the first switch unit 82A to an OFF state and the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to an ON state. When the second overheating state is detected by the second overheating detection unit 94B, the control unit 86 controls the fourth switch unit 82D to the off state and controls the first switch unit 82A, the second switch unit 82B, and the third switch unit 82C to the on state.

[0114] According to this configuration, even if the voltage conversion unit 92 side of the intermediate conduction path 80E and the low-voltage battery 91 side of the intermediate conduction path 80E are not in the second abnormal state, either the first switch unit 82A or the fourth switch unit 82D is controlled to the off state based on whether the first switch unit 82A or the fourth switch unit 82D is in an overheated state, making it easier to supply power to the important load 71 more stably.

[0115] The power distribution device 20 includes a drop detection unit 96 that detects a drop in the potential of the fourth conduction path 80D and a notification unit 89 that notifies the outside of the drop. When the first overheat detection unit 94A does not detect the first overheat state and the second overheat detection unit 94B does not detect the second overheat state, the control unit 86 controls the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to an on state when the drop occurs. The notification unit 89 notifies the outside of the drop in the potential of the fourth conduction path 80D when the drop occurs. With this configuration, when the second abnormal state or overheating does not occur, power is supplied to the important load 71 and the general load 72 while the notification unit 89 preliminarily notifies the outside of the drop in the potential of the fourth conduction path 80D. This makes it easy to take measures, such as maintenance, before the second abnormal state or overheating occurs.

[0116] 8 differs from the second embodiment in that a low potential signal Lv1 is output from the abnormality determination unit 185 to the control unit 86 in the power distribution device 30, and in the operation of the power distribution device 30, but is otherwise common to the second embodiment. In the following description, detailed description of the same configuration as the in-vehicle system 200 of the second embodiment will be omitted.

[0117] The control unit 86 is configured to receive the second abnormality signals Sg3 and Sg4 and the low potential signal Lv1 from the abnormality determination unit 185, the overheat signal Oh1 from the first overheat detection unit 94A, the overheat signal Oh2 from the second overheat detection unit 94B, and the drop signal Ds from the drop detection unit 96. Based on these signals (Sg3, Sg4, Oh1, Oh2, Ds, Lv1), the control unit 86 can control each of the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D to switch between an ON state and an OFF state.

[0118] [Example of Operation of Power Distribution Device] An example of operation of the power distribution device 30 will be described with reference to FIG. 9 . For example, when a vehicle equipped with the in-vehicle system 300 is traveling, the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D are each controlled by the control unit 86 to be maintained in an on state. While the vehicle is traveling, the power distribution device 30 periodically monitors the potential (signal V1) of the intermediate conductive path 80E, the potential (signal V2) of the first conductive path 80A, the potential (signal V3, Ds) of the fourth conductive path 80D, the current (signal A1) flowing through the first conductive path 80A, the current (signal A2) flowing through the fourth conductive path 80D, the temperature (signal T1) of the first switch unit 82A, and the temperature (signal T2) of the fourth switch unit 82D. Periodic monitoring corresponds to repeatedly executing the flowchart of FIG. 9 at predetermined intervals.

[0119] First, in step S51, the abnormality determination unit 185 determines whether the potential (signal V1) of the intermediate conductive path 80E is in the first low potential state. Specifically, the abnormality determination unit 185 determines whether the low potential signal Lv1 is being input from the first low potential detection unit 83A. If the abnormality determination unit 185 determines in step S51 that the low potential signal Lv1 is not being input (No in step S51), the process proceeds to step S60. Step S60 is performed when the first low potential detection unit 83A has not detected the first low potential state. If the abnormality determination unit 185 determines in step S51 that the low potential signal Lv1 is being input (Yes in step S51), the process outputs the low potential signal Lv1 to the control unit 86 and proceeds to step S52.

[0120] In step S52, the control unit 86 switches the first switch unit 82A and the fourth switch unit 82D to the OFF state simultaneously or sequentially based on the input of the low potential signal Lv1.

[0121] In step S53, the abnormality determination unit 185 determines whether the potential (signal V2) of the first conductive path 80A is in the second low potential state. Specifically, the abnormality determination unit 185 determines whether the low potential signal Lv2 is input from the second low potential detection unit 83B. If the abnormality determination unit 185 determines in step S53 that the low potential signal Lv2 is not input (No in step S53), the process proceeds to step S57. If the abnormality determination unit 185 determines in step S53 that the low potential signal Lv2 is input (Yes in step S53), the process proceeds to step S54.

[0122] In step S54, the abnormality determination unit 185 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in the second abnormal state (i.e., an abnormal state). That is, when the second low potential detection unit 83B detects the second low potential state, the abnormality determination unit 185 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in the second abnormal state. At the same time, the abnormality determination unit 185 outputs a second abnormality signal Sg3 to the control unit 86, indicating that the voltage conversion unit 92 side of the intermediate conductive path 80E is in the second abnormal state.

[0123] In step S55, the control unit 86 controls the first switch unit 82A and the third switch unit 82C to the OFF state and switches the fourth switch unit 82D from the OFF state to the ON state based on the input of the second abnormality signal Sg3 from the abnormality determination unit 185. Furthermore, the control unit 86 controls the second switch unit 82B to maintain the ON state. Then, in step S56, the notification unit 89 outputs a second abnormality notification signal Sg5 to the external device. This completes the processing shown in FIG. 9.

[0124] In step S57, the abnormality determination unit 185 determines whether the potential (signal V3) of the fourth conductive path 80D is in the third low potential state. Specifically, the abnormality determination unit 185 determines whether the low potential signal Lv3 has been input from the third low potential detection unit 83C. If the abnormality determination unit 185 determines in step S57 that the low potential signal Lv3 has not been input (No in step S57), the process shown in FIG. 9 ends. If the abnormality determination unit 185 determines in step S57 that the low potential signal Lv3 has been input (Yes in step S57), the process proceeds to step S58.

[0125] In step S58, the abnormality determination unit 185 determines that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E. That is, when the third low potential detection unit 83C detects the third low potential state, the abnormality determination unit 185 determines that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E. At the same time, the abnormality determination unit 185 outputs a second abnormality signal Sg4 to the control unit 86, indicating that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E.

[0126] In step S59, the control unit 86 controls the fourth switch unit 82D and the third switch unit 82C to the OFF state and switches the first switch unit 82A from the OFF state to the ON state based on the input of the second abnormality signal Sg4 from the abnormality determination unit 185. Furthermore, the control unit 86 controls the second switch unit 82B to maintain the ON state. Then, in step S56, the control unit 86 outputs the second abnormality notification signal Sg6 from the notification unit 89 to the external device. In this way, the processing shown in FIG. 9 ends.

[0127] In step S60, the abnormality determination unit 185 determines whether or not an overcurrent is flowing toward the voltage conversion unit 92. Specifically, the abnormality determination unit 185 determines whether or not the overcurrent signal Oc1 is being input from the first overcurrent detection unit 184A. In step S60, if the abnormality determination unit 185 determines that the overcurrent signal Oc1 is not being input from the first overcurrent detection unit 184A (No in step S60), the process proceeds to step S63.

[0128] If the abnormality determination unit 185 determines in step S60 that the overcurrent signal Oc1 has been input from the first overcurrent detection unit 184A, the process proceeds to step S61, where the abnormality determination unit 185 determines that the second abnormal state is occurring on the voltage conversion unit 92 side of the intermediate conductive path 80E. In other words, when the first overcurrent detection unit 184A detects the first overcurrent state, the abnormality determination unit 185 determines that the second abnormal state is occurring on the voltage conversion unit 92 side of the intermediate conductive path 80E. At the same time, the abnormality determination unit 185 outputs a second abnormality signal Sg3 to the control unit 86, indicating that the second abnormal state is occurring on the voltage conversion unit 92 side of the intermediate conductive path 80E.

[0129] In step S62, the control unit 86 switches the first switch unit 82A and the third switch unit 82C to the OFF state based on the input of the second abnormality signal Sg3 from the abnormality determination unit 185. At the same time, the control unit 86 controls the second switch unit 82B and the fourth switch unit 82D to maintain the ON state. Then, in step S56, the control unit 86 outputs the second abnormality notification signal Sg5 from the notification unit 89 to the external device. In this way, the processing shown in FIG. 9 ends.

[0130] In step S63, the abnormality determination unit 185 determines whether or not an overcurrent is flowing toward the low-voltage battery 91. Specifically, the abnormality determination unit 185 determines whether or not the overcurrent signal Oc2 is input from the second overcurrent detection unit 184B. In step S63, if the abnormality determination unit 185 determines that the overcurrent signal Oc2 is not input from the second overcurrent detection unit 184B (No in step S63), the process proceeds to step S40.

[0131] If the abnormality determination unit 185 determines in step S63 that the overcurrent signal Oc2 has been input from the second overcurrent detection unit 184B, the process proceeds to step S64, where the abnormality determination unit 185 determines that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E. In other words, when the second overcurrent detection unit 184B detects the second overcurrent state, the abnormality determination unit 185 determines that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E. At the same time, the abnormality determination unit 185 outputs a second abnormality signal Sg4 to the control unit 86, indicating that the second abnormal state is occurring on the low-voltage battery 91 side of the intermediate conductive path 80E.

[0132] In step S65, the control unit 86 switches the fourth switch unit 82D and the third switch unit 82C to the OFF state based on the second abnormality signal Sg4 input from the abnormality determination unit 185. At the same time, the control unit 86 controls the first switch unit 82A and the second switch unit 82B to maintain the ON state. In step S56, the control unit 86 outputs a second abnormality notification signal Sg6 from the notification unit 89 to the external device, indicating that the second abnormality state exists on the side of the low-voltage battery 91 relative to the intermediate conductive path 80E. This completes the process shown in FIG. 9 .

[0133] Steps S40, S41, S42, S43, and S44 are the same as those in embodiment 2, and therefore will not be described again. When the process moves from step S41 to step S56, the notification unit 89 outputs an overheat notification signal Sg7 indicating that the first switch unit 82A is in an overheated state to the external device. When the process moves from step S43 to step S56, the notification unit 89 outputs an overheat notification signal Sg8 indicating that the fourth switch unit 82D is in an overheated state to the external device. When the process moves from step S44 to step S56, the notification unit 89 outputs a drop notification signal Sg9 indicating that the potential of the fourth conductive path 80D is in a drop state to the external device.

[0134] The power distribution device 30 includes a first low potential detection unit 83A, a control unit 86, a second low potential detection unit 83B, a third low potential detection unit 83C, and an abnormality determination unit 185. The first low potential detection unit 83A detects a first low potential state based on the potential of the intermediate conductive path 80E. The control unit 86 controls the first switch unit 82A and the fourth switch unit 82D to an off state simultaneously or sequentially when the first low potential detection unit 83A detects the first low potential state. The second low potential detection unit 83B detects a second low potential state based on the potential of the first conductive path 80A. The third low potential detection unit 83C detects a third low potential state based on the potential of the fourth conductive path 80D. When the second low potential detection unit 83B detects the second low potential state, the abnormality determination unit 185 determines that the voltage conversion unit 92 side of the intermediate conductive path 80E is in the second abnormal state, and when the third low potential detection unit 83C detects the third low potential state, the abnormality determination unit 185 determines that the low-voltage battery 91 side of the intermediate conductive path 80E is in the second abnormal state. With this configuration, the abnormality determination unit 185 can determine whether the voltage conversion unit 92 side of the intermediate conductive path 80E and the low-voltage battery 91 side of the intermediate conductive path 80E are in the second abnormal state.

[0135] The power distribution device 30 includes a first overcurrent detection unit 184A and a second overcurrent detection unit 184B. The first overcurrent detection unit 184A detects a first overcurrent state based on a current flowing from the intermediate conductive path 80E to the first conductive path 80A. The second overcurrent detection unit 184B detects a second overcurrent state based on a current flowing from the intermediate conductive path 80E to the fourth conductive path 80D. If the first low potential detection unit 83A does not detect the first low potential state, the abnormality determination unit 185 determines that a second abnormal state exists on the voltage conversion unit 92 side of the intermediate conductive path 80E when the first overcurrent detection unit 184A detects the first overcurrent state. Furthermore, when the first low potential detection unit 83A does not detect the first low potential state, the abnormality determination unit 185 determines that the second abnormal state exists on the low-voltage battery 91 side of the intermediate conductive path 80E when the second overcurrent detection unit 184B detects the second overcurrent state. With this configuration, even when a low potential state is not detected, the abnormality determination unit 185 can determine without exception that the second abnormal state exists on the voltage conversion unit 92 side of the intermediate conductive path 80E and the low-voltage battery 91 side of the intermediate conductive path 80E using the first overcurrent detection unit 184A and the second overcurrent detection unit 184B.

[0136] In the power distribution device 30, the control unit 86 controls the first switch unit 82A, the second switch unit 82B, the third switch unit 82C, and the fourth switch unit 82D. When the abnormality determination unit 185 determines that the second abnormal state exists on the voltage conversion unit 92 side relative to the intermediate conduction path 80E, the control unit 86 controls the first switch unit 82A and the third switch unit 82C to an OFF state and the second switch unit 82B and the fourth switch unit 82D to an ON state. When the abnormality determination unit 185 determines that the second abnormal state exists on the low-voltage battery 91 side relative to the intermediate conduction path 80E, the control unit 86 controls the third switch unit 82C and the fourth switch unit 82D to an OFF state and controls the first switch unit 82A and the second switch unit 82B to an ON state. This configuration makes it possible to continue power supply to the important load 71 while suppressing the effects of the second abnormal state.

[0137] <Other Embodiments> The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0138] In each of the above embodiments, the importance of a load is determined based on the functional safety level specified in ISO 26262, but a different configuration may be used. For example, the importance of a load may be determined based on another standard. Furthermore, in the above embodiments, the critical loads are loads assigned ASIL-A to ASIL-D, but a different configuration may be used. For example, the critical loads may be loads assigned ASIL-B to ASIL-D, or loads assigned ASIL-C to ASIL-D, or only loads assigned ASIL-D.

[0139] Unlike the above embodiments, the control unit and the abnormality determination unit may be configured as a single MCU. The low potential detection unit, low current detection unit, overheat detection unit, and drop detection unit may also be configured as a single MCU together with the control unit and the abnormality determination unit. The control unit and the abnormality determination unit may also be configured as multiple hardware circuits other than the MCU.

[0140] Unlike the above-described embodiments, the switch may have a configuration in which a pair of butted FETs and a single FET are used together.

[0141] Unlike the second embodiment, the magnitude of the first potential threshold to be compared with the signal may be different in each low potential detection unit.

[0142] In step S31 of FIG. 7 in the second embodiment, it may be configured to determine only whether an overcurrent is flowing through the first and fourth conductive paths.

[0143] 7 in the second embodiment may not be performed. In other words, a temperature detection unit and an overheat detection unit may not be provided. In this case, steps S41 and S43 are not executed. After a negative determination is made in step S31, the process proceeds to step S44.

[0144] Unlike the second embodiment, the first overcurrent detection unit may perform overcurrent detection using either the first current detection unit or the second current detection unit, and the second overcurrent detection unit may perform overcurrent detection using either the first current detection unit or the second current detection unit.

[0145] Unlike embodiment 1, the low potential detection unit may detect a low potential state based on the potential of the first conductive path, or may be configured to detect a low potential state based on both the potential of the first conductive path and the potential of the intermediate conductive path.

[0146] Unlike the third embodiment, the first low potential detector may detect the first low potential state based on either the potential of the first conductive path or the potential of the fourth conductive path, or may detect the first low potential state based on all of the potentials of the first conductive path, the fourth conductive path, and the intermediate conductive path. Furthermore, the first low potential detector may detect the first low potential state based on both the potentials of the first conductive path and the fourth conductive path, or may detect the first low potential state based on both the potentials of the fourth conductive path and the intermediate conductive path, or may detect the first low potential state based on both the potentials of the first conductive path and the intermediate conductive path.

[0147] The configuration of embodiment 2 may be configured to include a low-current detection unit that detects a low-current state based on the current flowing through the fourth conduction path, and the abnormality determination unit may determine that the low-voltage battery side of the intermediate conduction path is in an open state (abnormal state) when the low-current detection unit detects a low-current state and the potential difference between the fourth conduction path and the intermediate conduction path is equal to or greater than a potential difference threshold. Here, the open state on the low-voltage battery side of the intermediate conduction path corresponds to a state in which the fourth conduction path is disconnected, a state in which there is a disconnection between the low-voltage battery and the fourth conduction path, etc.

[0148] 10, 20, 30... Power distribution device 70... Load 71... Important load 72... General load 80... Conduction path 80A... First conduction path 80B... Second conduction path 80C... Third conduction path 80D... Fourth conduction path 80E... Intermediate conduction path 81... Terminal 81A... First terminal 81B... Second terminal 81C... Third terminal 81D... Fourth terminal 82... Switch 82A... First switch unit 82B... Second switch unit 82C... Third switch unit 82D... Fourth switch unit 83... Low potential detection unit 83A... First low potential detection unit 83B... Second low potential detection unit 83C... Third low potential detection unit 84... Low current detection unit 84A... First low current detection unit 85, 185... Abnormality determination unit 86... Control unit 87... Potential detection unit 87A...First potential detection unit 87B...Second potential detection unit 87C...Third potential detection unit 88...Current detection unit 88A...First current detection unit 88B...Second current detection unit 89...Notification unit 90...High voltage battery 91...Low voltage battery 92...Voltage conversion unit 93...Temperature detection unit 93A...First temperature detection unit 93B...Second temperature detection unit 94...Overheat detection unit 94A...First overheat detection unit 94B...Second overheat detection unit 96...Droppage detection unit 97...Housing 100, 200, 300...In-vehicle system 184...Overcurrent detection unit 184A...First overcurrent detection unit 184B...Second overcurrent detection unit A1, A2, T1, T2, V1, V2, V3...Signal Ds...Droppage signal Lc1...Low current signal Lv1, Lv2, Lv3...Low potential signal Oc1, Oc2...Overcurrent signal Oh1, Oh2...Overheating signal Sg1...Abnormal signal Sg2...Abnormality notification signal Sg3, Sg4...Second abnormality signal Sg5, Sg6...Second abnormality notification signal Sg7, Sg8...Overheating notification signal Sg9...Lowering notification signal

Claims

1. A power distribution device included in an in-vehicle system including a high-voltage battery, a voltage conversion unit that converts and outputs a voltage input from the high-voltage battery, a low-voltage battery, an important load, and a general load that is less important than the important load, a first terminal to which power is supplied from the voltage conversion unit; a second terminal to which the critical load is connected; a third terminal to which the general load is connected; a fourth terminal to which power from the low-voltage battery is supplied; a first conductive path connected to the first terminal; a second conductive path connected to the second terminal; a third conductive path connected to the third terminal; a fourth conductive path connected to the fourth terminal; an intermediate conductive path; a first switch unit provided between the first conductive path and the intermediate conductive path; a second switch unit provided between the second conductive path and the intermediate conductive path; a third switch unit provided between the third conductive path and the intermediate conductive path, The fourth conductive path transmits the power supplied from the fourth terminal to the intermediate conductive path.

2. a low potential detection unit that detects a low potential state based on at least one of the potential of the first conductive path and the potential of the intermediate conductive path; a control unit that controls the first switch unit to an off state when the low potential state is detected by the low potential detection unit; 2. The power distribution device according to claim 1, further comprising: an abnormality determination unit that determines whether an abnormal state exists on the voltage conversion unit side of the intermediate conduction path based on a potential difference between the potential of the first conduction path and the potential of the intermediate conduction path.

3. a low current detection unit that detects a low current state based on a current flowing through the first conductive path; The power distribution device according to claim 2 , wherein the abnormality determination unit determines that the abnormality occurs when the low current state is detected by the low current detection unit and the potential difference is equal to or greater than a potential difference threshold value.

4. a low potential detection unit that detects a low potential state based on at least one of a potential of the first conductive path, a potential of the fourth conductive path, and a potential of the intermediate conductive path; an overcurrent detection unit that detects an overcurrent state based on a current flowing from the intermediate conductive path to the first conductive path; Equipped with 3. The power distribution device according to claim 2, wherein the abnormality determination unit determines that the abnormal state exists when the low potential state is detected by the low potential detection unit and the overcurrent state is detected by the overcurrent detection unit.

5. The power distribution device according to claim 1 , further comprising a fourth switch section provided between the fourth conductive path and the intermediate conductive path.

6. a low potential detection unit that detects a low potential state based on at least one of a potential of the first conductive path, a potential of the fourth conductive path, and a potential of the intermediate conductive path; an overcurrent detection unit that detects an overcurrent state based on a current flowing from the intermediate conductive path side to the fourth conductive path side; an abnormality determination unit that determines that an abnormality exists on the low-voltage battery side relative to the intermediate conduction path when the low-potential state is detected by the low-potential detection unit and the overcurrent state is detected by the overcurrent detection unit; and a control unit that controls the fourth switch unit to an off state when the abnormality determination unit determines that the abnormal state exists; The power distribution device of claim 5 , comprising:

7. a first low potential detection unit that detects a first low potential state based on at least one of a potential of the first conductive path, a potential of the fourth conductive path, and a potential of the intermediate conductive path; a control unit that controls the first switch unit and the fourth switch unit to an off state simultaneously or sequentially when the first low potential state is detected by the first low potential detection unit; a second low potential detection unit that detects a second low potential state based on the potential of the first conductive path; a third low potential detection unit that detects a third low potential state based on the potential of the fourth conductive path; an abnormality determination unit that determines, when the second low potential state is detected by the second low potential detection unit, that the voltage conversion unit side of the intermediate conduction path is in an abnormal state, and that, when the third low potential detection unit detects the third low potential state, that the low voltage battery side of the intermediate conduction path is in the abnormal state; The power distribution device of claim 5 , comprising:

8. a first overcurrent detection unit that detects a first overcurrent state based on a current flowing from the intermediate conductive path side to the first conductive path side; a second overcurrent detection unit that detects a second overcurrent state based on a current flowing from the intermediate conductive path side to the fourth conductive path side, When the first low potential detection unit does not detect the first low potential state, 8. The power distribution device according to claim 7, wherein the abnormality determination unit determines that the voltage conversion unit side of the intermediate conduction path is in the abnormal state when the first overcurrent detection unit detects the first overcurrent state, and determines that the low-voltage battery side of the intermediate conduction path is in the abnormal state when the second overcurrent detection unit detects the second overcurrent state.

9. the control unit controls the first switch unit and the fourth switch unit, 9. The power distribution device according to claim 7, wherein when the abnormality determination unit determines that the abnormal state is on the voltage conversion unit side of the intermediate conduction path, the first switch unit is controlled to an off state and the fourth switch unit is controlled to an on state, and when the abnormality determination unit determines that the abnormal state is on the low-voltage battery side of the intermediate conduction path, the fourth switch unit is controlled to an off state and the first switch unit is controlled to an on state.

10. the first switch unit and the fourth switch unit are semiconductor switches having parasitic diodes, the first switch unit allows a current to flow from the voltage conversion unit to the intermediate conduction path via at least the parasitic diode; The power distribution device according to claim 5 , wherein the fourth switch unit allows a current to flow from the low-voltage battery to the intermediate conductive path via at least the parasitic diode.

11. 7. The power distribution device according to claim 6, wherein the control unit controls the third switch unit and the fourth switch unit, and when the abnormality determination unit determines that the abnormal state exists, controls the third switch unit to an off state.

12. a first overheat detection unit that detects a first overheat state based on the temperature of the first switch unit; a second overheat detection unit that detects a second overheat state based on the temperature of the fourth switch unit; Equipped with the control unit controls the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit; The control unit When the first overheat state is detected by the first overheat detection unit, the first switch unit is controlled to an off state, and the second switch unit, the third switch unit, and the fourth switch unit are controlled to an on state; 7. The power distribution device according to claim 6, wherein when the second overheat state is detected by the second overheat detection unit, the fourth switch unit is controlled to an off state and the first switch unit, the second switch unit, and the third switch unit are controlled to an on state.

13. a drop detection unit that detects that the potential of the fourth conductive path is in a drop state; a notification unit that notifies an external device of the degradation state, When the first overheat detection unit does not detect the first overheat state and the second overheat detection unit does not detect the second overheat state, the control unit controls the first switch unit, the second switch unit, the third switch unit, and the fourth switch unit to an on state when the power supply is in the decreased state; The power distribution device according to claim 12 , wherein the notification unit notifies the outside of the degraded state when the degraded state occurs.