Earth fault detection device

Abstract

To suppress stop of power supply to an important load when any of a plurality of loads which are loads with importance lower than that of the important load and include an electric power steering device is grounded, and to suppress stop of power supply to the electric power steering device when the grounded load is not the electric power steering device.SOLUTION: A ground fault detection device 10 is used for an on-vehicle system 100. The on-vehicle system comprises a power supply unit 90, a power storage unit 91, a conducting path 80, and a cut-off unit 74. The conducting path has a first conducting path 81, a second conducting path 82, and a third conducting path 83. The cut-off unit has a first cut-off unit 75, and a second cut-off unit 76. A second load 72 is connected with one of the second conducting path and the third conducting path, and a third load 73 is connected with the other. The ground fault detection device has detection units 11 to 14 which detect a ground fault of at least either of the second conducting path or the third conducting path.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a ground fault detection device. [Background technology]

[0002] The in-vehicle power supply system disclosed in Patent Document 1 includes a first power supply unit (electricity storage device), a second power supply unit (battery unit), a first switch provided between the two power supply units, and a second switch provided closer to the second power supply unit than the first switch. A driving load is connected to a path between the two switches. A general load such as a room lamp is connected to a path between the first switch and the first power supply unit. A VS load such as an audio system is connected to a path between the second switch and the second power supply unit. With this configuration, even if the general load has a ground fault, power can be supplied to the driving load by turning off the first switch and turning on the second switch, and even if the VS load has a ground fault, power can be supplied to the driving load by turning on the first switch and turning off the second switch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-24288 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if both the general load and the VS load have a ground fault, power cannot be supplied to the driving load. The driving load includes not only important loads such as the electric brake device, but also the electric power steering device. Therefore, if the electric power steering device has a ground fault, power cannot be supplied to important loads such as the electric brake device.

[0005] The present disclosure provides a technology that can prevent the power supply to an important load from being stopped when a ground fault occurs in any of a plurality of loads, including an electric power steering device, that is less important than the important load, and can also prevent the power supply to the electric power steering device from being stopped if the load that has a ground fault is not the electric power steering device. [Means for solving the problem]

[0006] The ground fault detection device of the present disclosure comprises: A ground fault detection device for use in an in-vehicle system including a power supply unit, a power storage unit different from the power supply unit, a conductive path provided between the power supply unit and the power storage unit, a load connected to the conductive path, and a breaker provided in the conductive path, the cutoff unit has a first cutoff unit provided between the power supply unit and the power storage unit, and a second cutoff unit provided closer to the power supply unit than the first cutoff unit, the conductive path includes a first conductive path provided between the storage unit and the first cutoff unit, a second conductive path provided between the first cutoff unit and the second cutoff unit, and a third conductive path provided between the second cutoff unit and the power supply unit, The loads include a first load including an important load, a second load including an electric power steering device, and a third load having a lower importance than the important load, the first load is connected to the first conductive path; the second load is connected to one of the second conductive path and the third conductive path; the third load is connected to the other of the second conductive path and the third conductive path; the first interrupter is switched between a first permissive state in which a current is permitted to flow from the first conductive path side to the second conductive path side and a first interruption state in which a current is interrupted; The second cutoff unit is switched between a second permissive state in which a current flows from the second conductive path side to the third conductive path side and from the third conductive path side to the second conductive path side, and a second cutoff state in which a current flows. The power supply circuit further includes a detection unit that detects a ground fault in at least one of the second conductive path and the third conductive path. Effect of the Invention

[0007] According to the present disclosure, when a ground fault occurs in any of a plurality of loads, including an electric power steering device, that is less important than the important load, it is possible to prevent the power supply to the important load from being stopped, and if the load that has a ground fault is not the electric power steering device, it is possible to prevent the power supply to the electric power steering device from being stopped. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram illustrating a schematic configuration of an in-vehicle system according to the first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram conceptually showing the operation of the in-vehicle system when it is determined that the ground fault location is on the third conduction path side. [Diagram 3] FIG. 3 is an explanatory diagram conceptually showing the operation of the in-vehicle system when it is determined that the ground fault location is on the second conductive path side. [Figure 4] FIG. 4 is a circuit diagram illustrating a schematic configuration of an in-vehicle system according to the second embodiment. [Diagram 5] FIG. 5 is an explanatory diagram conceptually showing the operation of the in-vehicle system when it is determined that the ground fault location is on the third conduction path side. [Figure 6] FIG. 6 is an explanatory diagram conceptually showing the operation of the in-vehicle system when it is determined that the ground fault location is on the second conductive path side. [Figure 7] FIG. 7 is a circuit diagram illustrating a schematic configuration of an in-vehicle system according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] [1] A ground fault detection device for use in an in-vehicle system including a power supply unit, a storage unit different from the power supply unit, a conductive path provided between the power supply unit and the storage unit, a load connected to the conductive path, and a breaker provided in the conductive path, the cutoff unit has a first cutoff unit provided between the power supply unit and the power storage unit, and a second cutoff unit provided closer to the power supply unit than the first cutoff unit, the conductive path includes a first conductive path provided between the storage unit and the first cutoff unit, a second conductive path provided between the first cutoff unit and the second cutoff unit, and a third conductive path provided between the second cutoff unit and the power supply unit, The loads include a first load including an important load, a second load including an electric power steering device, and a third load having a lower importance than the important load, the first load is connected to the first conductive path; the second load is connected to one of the second conductive path and the third conductive path; the third load is connected to the other of the second conductive path and the third conductive path; the first interrupter is switched between a first permissive state in which a current is permitted to flow from the first conductive path side to the second conductive path side and a first interruption state in which a current is interrupted; The second cutoff unit is switched between a second permissive state in which a current flows from the second conductive path side to the third conductive path side and from the third conductive path side to the second conductive path side, and a second cutoff state in which a current flows. a detection unit for detecting a ground fault in at least one of the second conductive path and the third conductive path; Earth fault detection device.

[0011] The above-mentioned ground fault detection device can detect a ground fault in at least one of the second conductive path and the third conductive path. Therefore, in a configuration in which a second load is connected to the third conductive path, the above-mentioned vehicle system can be configured, for example, so that when a ground fault is detected by the detection unit, the first interrupting unit switches to the first interrupting state and the second interrupting unit switches to the second interrupting state, thereby preventing the power supply to the first load from being stopped when a ground fault is detected by the detection unit, and also preventing the power supply to the second load from being stopped if the ground fault is located in the second conductive path. In addition, in a configuration in which a second load is connected to the second conductive path, the above-mentioned in-vehicle system can be configured to, for example, determine whether the ground fault location is on the second conductive path side or the third conductive path side, and if it is determined that the ground fault location is on the second conductive path side, set the first interrupting unit to the first interrupting state, and if it is determined that the ground fault location is on the third conductive path side, set the first interrupting unit to the first permissive state and the second interrupting unit to the second interrupting state.This can prevent the power supply to the first load from being stopped when a ground fault is detected by the detection unit, and can also prevent the power supply to the second load from being stopped if the ground fault location is on the third conductive path side. In other words, the above-mentioned ground fault detection device can prevent the power supply to the important loads from being stopped when a ground fault occurs in a path connected to a load (second load and third load) that is less important than the important load, and can also prevent the power supply to the electric power steering device from being stopped if there is no ground fault in the path connected to the electric power steering device.

[0012] [2] The ground fault detection device described in [1] may have a judgment unit that determines whether the ground fault location is on the second conductive path side or the third conductive path side when the detection unit detects a ground fault in at least one of the second conductive path and the third conductive path.

[0013] The above-mentioned ground fault detection device can determine by itself whether the ground fault location is on the second conduction path side or the third conduction path side.

[0014] [3] In the ground fault detection device described in [2], the judgment unit may determine whether the ground fault location is on the second conductive path side or the third conductive path side based on a voltage of at least one of the second conductive path and the third conductive path when the first interrupting unit is in the first interrupting state and the second interrupting unit is in the second interrupting state.

[0015] The above-mentioned ground fault detection device can determine whether the ground fault location is on the second conductive path side or the third conductive path side based on the voltage of at least one of the second conductive path and the third conductive path when the first interrupter is in the first interrupting state and the second interrupter is in the second interrupting state.

[0016] [4] The ground fault detection device described in [3] may have a control unit that controls the first interrupting unit to the first interrupting state and the second interrupting unit to the second interrupting state when a ground fault in at least one of the second conductive path and the third conductive path is detected by the detection unit. The determination unit may determine whether a ground fault location is on the second conductive path side or the third conductive path side based on a voltage of at least one of the second conductive path and the third conductive path in a state in which the first interrupting unit is controlled to the first interrupting state and the second interrupting unit is controlled to the second interrupting state by the control unit.

[0017] The above-mentioned ground fault detection device, when a ground fault is detected in either the second conductive path or the third conductive path by the detection unit, controls the first interrupting unit to a first interrupting state and the second interrupting unit to a second interrupting state, and can determine whether the ground fault location is on the second conductive path side or the third conductive path side based on the voltage of at least one of the second conductive path and the third conductive path.

[0018] [5] In the ground fault detection device described in [2], the judgment unit may have a current detection unit that detects a current flowing through at least one of the second conductive path and the third conductive path, and may determine whether the ground fault location is on the second conductive path side or the third conductive path side based on the direction of the current flowing through at least one of the second conductive path and the third conductive path.

[0019] The above-mentioned ground fault detection device can determine whether the location of the ground fault is on the second conductive path side or the third conductive path side based on the direction of the current flowing through at least one of the second conductive path and the third conductive path.

[0020] [6] In the ground fault detection device according to any one of [2] to [5], the second load may be connected to the third conductive path. The ground fault detection device may have a control unit that performs at least one of an operation of controlling the first interrupting unit to the first interruption state and an operation of controlling the second interrupting unit to the second interruption state when the determination unit determines that the ground fault location is on the third conductive path side, and controls the first interrupting unit to the first interruption state and the second interrupting unit to the second interruption state when the determination unit determines that the ground fault location is on the second conductive path side.

[0021] The above-mentioned ground fault detection device can prevent the power supply to the first load from being stopped regardless of whether the ground fault location is determined to be on the second conductive path side or the third conductive path side, and can prevent the power supply to the second load from being stopped when the ground fault location is determined to be on the second conductive path side.

[0022] [7] In the ground fault detection device according to any one of [2] to [5], the second load may be connected to the second conductive path. The ground fault detection device may have a control unit that controls the first interrupter to the first permissive state and the second interrupter to the second interrupted state when the determination unit determines that the ground fault location is on the third conductive path side, and controls the first interrupter to the first interrupted state when the determination unit determines that the ground fault location is on the second conductive path side.

[0023] The above-mentioned ground fault detection device can prevent the power supplied to the first load from being stopped regardless of whether the ground fault location is determined to be on the second conductive path side or the third conductive path side, and can prevent the power supplied to the second load from being stopped if the ground fault location is determined to be on the third conductive path side.

[0024] [8] In the ground fault detection device described in [4] above, the second load may be connected to the third conductive path.

[0025] When the second interrupter is switched to the second interruption state to determine the location of the ground fault, it is possible to prevent the power supply to the second load from being interrupted.

[0026] [9] In the ground fault detection device described in any one of [1] to [5], the second load may be connected to the second conductive path.

[0027] According to the above configuration, even if a ground fault occurs in the power supply unit, power can be supplied from the power storage unit to the second load.

[0028] First Embodiment 1 is a system mounted on a vehicle. The in-vehicle system 100 includes a power supply unit 90, a power storage unit 91, a conductive path 80, and a load 70. The in-vehicle system 100 can supply power based on the power supply unit 90 and the power storage unit 91 to the load 70 via the conductive path 80.

[0029] The power supply unit 90 is a DC power supply, and is configured, for example, as a battery such as a lithium ion battery, a DCDC converter, etc. The power storage unit 91 is a power supply different from the power supply unit 90, and is configured, for example, as a battery such as a lead battery. The conductive path 80 is provided between the power supply unit 90 and the power storage unit 91. One end of the conductive path 80 is connected to the power storage unit 91, and the other end of the conductive path 80 is connected to the power supply unit 90. The load 70 is connected to the conductive path 80.

[0030] The load 70 includes a first load 71, a second load 72, and a third load 73. The first load 71 is a load including an important load. A plurality of first loads 71 ​​are provided. An important load is a load having a higher importance than the second load 72 and the third load 73. The importance is determined based on the functional safety level defined in ISO26262, for example. The functional safety level is classified into five levels, from the lowest to the highest, namely, QM (Quality Management), ASIL (Automotive Safety Integrity Level)-A, ASIL-B, ASIL-C, and ASIL-D. The higher the functional safety level is assigned to the load, the higher the importance of the load. In this embodiment, a load assigned with an ASIL (i.e., ASIL-A to D) is referred to as an "important load". The important loads are, 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.

[0031] The second load 72 and the third load 73 are loads less important than the important load, and in this embodiment, are loads with a functional safety level of QM. The second load 72 is only an electric power steering device. The third load 73 is a load other than the second load 72 that is less important than the important load. A plurality of third loads 73 are provided. The third load 73 is, for example, a headlight, an audio output device, etc.

[0032] The in-vehicle system 100 includes a cutoff unit 74 provided in the conductive path 80. The cutoff unit 74 has a first cutoff unit 75 provided between the power supply unit 90 and the power storage unit 91, and a second cutoff unit 76 provided closer to the power supply unit 90 than the first cutoff unit 75.

[0033] The conductive path 80 described above includes a first conductive path 81, a second conductive path 82, and a third conductive path 83. The first conductive path 81 is provided between the power storage unit 91 and the first interrupter unit 75. The first conductive path 81 includes a first main path 81A connected to an output end of the power storage unit 91 and one end of the first interrupter unit 75, and a first branch path 81B branched from the first main path 81A. A plurality of first branch paths 81B are provided. The first load 71 is connected to the first branch path 81B. The second conductive path 82 is provided between the first interrupter unit 75 and the second interrupter unit 76. The second conductive path 82 includes a second main path 82A connected to the other end of the first interrupter unit 75 and one end of the second interrupter unit 76, and a second branch path 82B branched from the second main path 82A. The second branch path 82B is connected to the second load 72. The third conductive path 83 is provided between the second breaker 76 and the power supply unit 90. The third conductive path 83 has a third main path 83A connected to the other end of the second breaker 76 and the output end of the power supply unit 90, and a third branch path 83B branched off from the third main path 83A. A plurality of third branch paths 83B are provided. The third load 73 is connected to the third branch path 83B.

[0034] The above-mentioned first cutoff unit 75 switches between a first permissive state in which a current is permitted to flow from the first conductive path 81 side to the second conductive path 82 side, and a cutoff state in which a current is cut off. In the first permissive state, the first cutoff unit 75 also permits a current to flow from the second conductive path 82 side to the first conductive path 81 side. In the first cutoff state, the first cutoff unit 75 also cuts off a current from the second conductive path 82 side to the first conductive path 81 side. The first cutoff unit 75 has switching elements 75A and 75B, and is in the first permissive state when the switching elements 75A and 75B are turned on, and is in the first cutoff state when the switching elements 75A and 75B are turned off. In this embodiment, the switching elements 75A and 75B are FETs (Field Effect Transistors), and are arranged in series and in opposite directions to each other.

[0035] The above-mentioned second cutoff unit 76 switches between a second permissive state in which it allows current to flow from the third conductive path 83 side to the second conductive path 82 side and current to flow from the second conductive path 82 side to the third conductive path 83 side, and a second cutoff state in which it cuts off the current. The second cutoff unit 76 has switching elements 76A and 76B, and is in the second permissive state when the switching elements 76A and 76B are in the on state, and in the second cutoff state when the switching elements 76A and 76B are in the off state. In this embodiment, the switching elements 76A and 76B are FETs, and are arranged in series with each other and in opposite directions.

[0036] The vehicle-mounted system 100 includes a ground fault detection device 10. The ground fault detection device 10 is used in the vehicle-mounted system 100. The ground fault detection device 10 can detect a ground fault in at least one of the second conductive path 82 and the third conductive path 83. The ground fault detection device 10 includes a first voltage detection unit 11, a second voltage detection unit 12, a current detection unit 13, a control circuit 14, and a power supply control ECU 15. The power supply control ECU 15 includes a determination unit 15A and a control unit 15B. The determination unit 15A and the control unit 15B are configured by an MCU (Micro Controller Unit). The current detection unit 13 and the control circuit 14 correspond to an example of a "detection unit".

[0037] The in-vehicle system 100 is configured so that the first conductive path 81 connected to the first load 71 is particularly unlikely to cause a ground fault. The in-vehicle system 100 has a first power supply box 93 and a second power supply box 94. A part of the first conductive path 81 is disposed inside the first power supply box 93. The second power supply box 94 is disposed outside the first power supply box 93. A part of the first conductive path 81, a part of the second conductive path 82, a part of the third conductive path 83, the first interrupter 75, the second interrupter 76, the first voltage detector 11, the second voltage detector 12, the current detector 13, and the control circuit 14 are disposed inside the second power supply box 94. The power supply unit 90, the power storage unit 91, the first load 71, the second load 72, the third load 73, and the power supply control ECU 15 are disposed outside the first power supply box 93 and the second power supply box 94. Between the power storage unit 91 and the first load 71 connected to the first conductive path 81, and the first power supply box 93 or the second power supply box 94, a configuration in which a bus bar is used for connection, a configuration in which a protector is attached, or the like is adopted. Alternatively, a fuse is provided in the first branch path 81B. Also, between the first power supply box 93 and the second power supply box 94, a configuration in which a bus bar is used for connection, a configuration in which a protector is attached, or the like is adopted. As a result, the in-vehicle system 100 is configured such that the first conductive path 81 is particularly unlikely to cause a ground fault. In such an in-vehicle system 100, when a ground fault is detected in the second conductive path 82 or the third conductive path 83 while the first interrupter 75 is in the first permissive state and the second interrupter 76 is in the second interrupted state, the ground fault detection device 10 determines that a ground fault has been detected in at least one of the second conductive path 82 and the third conductive path 83. When a ground fault is detected in at least one of second conductive path 82 and third conductive path 83, ground fault detection device 10 is configured to determine whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side, and to control first breaking unit 75 and second breaking unit 76 based on the determination result. The following description relates to the specific operation.

[0038] The first voltage detection unit 11 can detect the voltage of the second conductive path 82. In this specification, the term "voltage" refers to a voltage with respect to the ground. The first voltage detection unit 11 is configured as, for example, a known voltage detection circuit. The first voltage detection unit 11 outputs a signal capable of identifying the detected voltage.

[0039] The second voltage detection unit 12 can detect the voltage of the third conductive path 83. The second voltage detection unit 12 is configured as, for example, a known voltage detection circuit. The second voltage detection unit 12 outputs a signal capable of identifying the detected voltage.

[0040] The current detection unit 13 can detect a current flowing through the third conductive path 83. The current detection unit 13 is configured as a known current detection circuit using, for example, a current transformer or a shunt resistor. The current detection unit 13 outputs a signal capable of identifying the detected current.

[0041] The control circuit 14 includes an MCU, an AD converter, a drive circuit, a communication unit, and the like. Signals output from the first voltage detection unit 11, the second voltage detection unit 12, and the current detection unit 13 are input to the control circuit 14. The control circuit 14 can identify the voltage of the second conductive path 82, the voltage of the third conductive path 83, and the value of the current flowing through the third conductive path 83 based on the input signals. The control circuit 14 can detect a ground fault in at least one of the second conductive path 82 and the third conductive path 83. The control circuit 14 determines whether or not the value of the current flowing through the third conductive path 83 exceeds a predetermined threshold current in a state in which power is supplied to the load 70 from at least one of the power supply unit 90 and the power storage unit 91. When the control circuit 14 determines that the value of the current flowing through the third conductive path 83 is equal to or less than the threshold current, it determines that neither the second conductive path 82 nor the third conductive path 83 has a ground fault, and when it determines that the value of the current flowing through the third conductive path 83 exceeds the threshold current, it determines that at least one of the second conductive path 82 and the third conductive path 83 has a ground fault.

[0042] The power supply control ECU 15 can obtain the voltage of the second conductive path 82, the voltage of the third conductive path 83, and the value of the current flowing through the third conductive path 83 from the control circuit 14. Furthermore, the power supply control ECU 15 can determine, based on a signal input from the control circuit 14, that a ground fault has been detected in at least one of the second conductive path 82 and the third conductive path 83.

[0043] The control unit 15B of the power supply control ECU 15 can control the first interrupting unit 75 and the second interrupting unit 76 via the control circuit 14. When the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the control unit 15B controls the first interrupting unit 75 to the first interrupted state and controls the second interrupting unit 76 to the second interrupted state.

[0044] When the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the determination unit 15A of the power supply control ECU 15 determines whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side. The determination unit 15A determines whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side based on the voltage of at least one of the second conductive path 82 and the third conductive path 83 when the first interrupter 75 is in the first interruption state and the second interrupter 76 is in the second interruption state. The determination unit 15A determines whether the voltage of the second conductive path 82 is equal to or lower than a predetermined threshold voltage, and when it is determined that the voltage is equal to or lower than the threshold, it determines that the ground fault location is on the second conductive path 82 side. The determination unit 15A also determines whether the voltage of the third conductive path 83 is equal to or lower than the threshold voltage, and when it is determined that the voltage is equal to or lower than the threshold, it determines that the ground fault location is on the third conductive path 83 side. The threshold voltage is a value of 0V or higher.

[0045] When the control unit 15B determines that the ground fault location is on the third conductive path 83 side, the control unit 15B switches the first interrupting unit 75 to the first permissive state and maintains the second interrupting unit 76 in the second interrupted state. This allows the ground fault detection device 10 to supply power from the power storage unit 91 to the first load 71 and the third load 73 as shown in FIG. 2. When the control unit 15B determines that the ground fault location is on the second conductive path 82 side, the control unit 15B maintains the first interrupting unit 75 in the first interrupted state and maintains the second interrupting unit 76 in the second interrupted state. This allows the ground fault detection device 10 to supply power from the power storage unit 91 to the first load 71 and to supply power from the power supply unit 90 to the second load 72 as shown in FIG. 3.

[0046] As described above, when the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the ground fault detection device 10 temporarily switches the first interrupter 75 to the first interruption state and switches the second interrupter 76 to the second interruption state. This allows the ground fault detection device 10 to prevent a large current from flowing to a path where no ground fault occurs. Moreover, since the first load 71 is connected to the first conductive path 81 and the second load 72 is connected to the third conductive path 83, the in-vehicle system 100 can prevent interruption of the power supply to the first load 71 while also preventing interruption of the power supply to the second load 72 if there is no ground fault on the third conductive path 83 side.

[0047] Furthermore, in a state in which first interrupting unit 75 is switched to the first interrupting state and second interrupting unit 76 is switched to the second interrupting state, ground fault detection device 10 determines whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side based on the voltage of second conductive path 82 or the voltage of third conductive path 83. When ground fault detection device 10 determines that the ground fault location is on the third conductive path 83 side, it switches first interrupting unit 75 to the first permissive state and maintains second interrupting unit 76 in the second interrupting state. When ground fault detection device 10 determines that the ground fault location is on the second conductive path 82 side, it maintains first interrupting unit 75 in the first interrupting state and second interrupting unit 76 in the second interrupting state. As a result, the ground fault detection device 10 can prevent the power supply to the first load 71 from being stopped regardless of whether the ground fault is located on the second conductive path 82 side or the third conductive path 83 side, and can prevent the power supply to the second load 72 from being stopped if the ground fault is not located on the third conductive path 83 side.

[0048] <Second embodiment> 4 differs from the in-vehicle system 100 of the first embodiment in that a second load 72 is connected to the second conductive path 82 and a third load 73 is connected to the third conductive path 83, but is otherwise common to the in-vehicle system 100 of the first embodiment. 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.

[0049] Control circuit 14 determines whether the value of the current flowing through third conductive path 83 exceeds a predetermined threshold current while power is being supplied to load 70 from at least one of power supply unit 90 and power storage unit 91. When control circuit 14 determines that the value of the current flowing through third conductive path 83 is equal to or less than the threshold current, control circuit 14 determines that neither second conductive path 82 nor third conductive path 83 has a ground fault, and when control circuit 14 determines that the value of the current flowing through third conductive path 83 exceeds the threshold current, control circuit 14 determines that at least one of second conductive path 82 and third conductive path 83 has a ground fault.

[0050] When the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the control unit 15B of the power supply control ECU 15 controls the first interrupting unit 75 to a first interrupting state and controls the second interrupting unit 76 to a second interrupting state.

[0051] When the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the determination unit 15A of the power supply control ECU 15 determines whether the ground fault is located on the second conductive path 82 side or the third conductive path 83 side. The determination method is the same as in the first embodiment, and therefore a detailed description thereof will be omitted.

[0052] When it is determined that the ground fault location is on the third conductive path 83 side, the control unit 15B switches the first interrupting unit 75 to the first permissive state and maintains the second interrupting unit 76 in the second interrupted state. This allows the ground fault detection device 10 to supply power from the power storage unit 91 to the first load 71 and the second load 72, as shown in FIG. 5. When it is determined that the ground fault location is on the second conductive path 82 side, the control unit 15B maintains the first interrupting unit 75 in the first interrupted state and maintains the second interrupting unit 76 in the second interrupted state. This allows the ground fault detection device 10 to supply power from the power storage unit 91 to the first load 71 and to supply power from the power supply unit 90 to the third load 73, as shown in FIG. 6.

[0053] As described above, when the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the ground fault detection device 10 temporarily switches the first interrupter 75 to the first interruption state and switches the second interrupter 76 to the second interruption state. This enables the ground fault detection device 10 to suppress a large current from flowing to a path where no ground fault occurs.

[0054] Furthermore, in a state in which first interrupting unit 75 is switched to the first interrupting state and second interrupting unit 76 is switched to the second interrupting state, ground fault detection device 10 determines whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side based on the voltage of second conductive path 82 and the voltage of third conductive path 83. When ground fault detection device 10 determines that the ground fault location is on the third conductive path 83 side, it switches first interrupting unit 75 to the first permissive state and maintains second interrupting unit 76 in the second interrupting state. When ground fault detection device 10 determines that the ground fault location is on the second conductive path 82 side, it maintains first interrupting unit 75 in the first interrupting state and second interrupting unit 76 in the second interrupting state. As a result, the ground fault detection device 10 can prevent the power supply to the first load 71 from being stopped regardless of whether the ground fault is located on the second conductive path 82 side or the third conductive path 83 side, and can prevent the power supply to the second load 72 from being stopped if the ground fault is not located on the second conductive path 82 side.

[0055] Furthermore, since the second load 72 is connected to the second conductive path 82, even if the power supply unit 90 has a ground fault, power can be supplied from the power storage unit 91.

[0056] <Third embodiment> 7, the in-vehicle system 300 of the third embodiment shown in Fig. 7 is different from the in-vehicle system 100 of the first embodiment in the determination method by the determination unit, 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.

[0057] The current detection unit 13 can detect a current flowing through the third conductive path 83. More specifically, the current detection unit 13 can detect a current flowing through a path between a branch point where the third branch path 83B branches off from the third main path 83A and the second interrupter 76. The current detection unit 13 is configured as a known current detection circuit using, for example, a current transformer or a shunt resistor. The current detection unit 13 outputs a signal capable of identifying the detected current.

[0058] The control circuit 14 includes an MCU, an AD converter, a drive circuit, a communication unit, and the like. The control circuit 14 receives a signal output from the current detection unit 13. The control circuit 14 can identify the value of the current flowing through the third conductive path 83 based on the input signal. The control circuit 14 can detect a ground fault in the second conductive path 82 and the third conductive path 83. The control circuit 14 determines whether or not the value of the current flowing through the third conductive path 83 exceeds a predetermined threshold current when power is supplied to the load 70 from at least one of the power supply unit 90 and the power storage unit 91. When the control circuit 14 determines that the value of the current flowing through the third conductive path 83 is equal to or less than the threshold current, the control circuit 14 determines that neither the second conductive path 82 nor the third conductive path 83 has a ground fault, and when the control circuit 14 determines that the value of the current flowing through the third conductive path 83 has exceeded the threshold current, the control circuit 14 determines that at least one of the second conductive path 82 and the third conductive path 83 has a ground fault.

[0059] The power supply control ECU 15 can obtain values ​​of currents flowing through the second conductive path 82 and the third conductive path 83 from the control circuit 14. Furthermore, the power supply control ECU 15 can determine, based on a signal input from the control circuit 14, that a ground fault has been detected in at least one of the second conductive path 82 and the third conductive path 83.

[0060] When the control circuit 14 detects a ground fault in at least one of the second conductive path 82 and the third conductive path 83, the determination unit 15A determines whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side. The determination unit 15A determines whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side based on the direction of the current flowing through the third conductive path 83. When the ground fault location is on the second conductive path 82 side, the current direction is from the third conductive path 83 side to the second conductive path 82 side, and when the ground fault location is on the third conductive path 83 side, the current direction is from the second conductive path 82 side to the third conductive path 83 side. Thus, the determination unit 15A can specify the direction of the current based on the value of the current flowing through the third conductive path 83, and determine whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side based on the direction of the current.

[0061] The control unit 15B can control the first interrupting unit 75 and the second interrupting unit 76 through the control circuit 14. When the control unit 15B determines that the ground fault location is on the third conductive path 83 side, the control unit 15B switches the second interrupting unit 76 to the second interrupting state while maintaining the first interrupting unit 75 in the first permissive state. This allows the ground fault detection device 10 to supply power from the power storage unit 91 to the first load 71 and the third load 73, similar to the example shown in FIG. 2. When the control unit 15B determines that the ground fault location is on the second conductive path 82 side, the control unit 15B switches the first interrupting unit 75 to the first interrupting state and switches the second interrupting unit 76 to the second interrupting state. This allows the ground fault detection device 10 to supply power from the power storage unit 91 to the first load 71 and supply power from the power supply unit 90 to the second load 72, similar to the example shown in FIG. 3.

[0062] As described above, according to the third embodiment of the ground fault detection device 310, it is possible to determine whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side without detecting the voltages of the second conductive path 82 and the third conductive path 83.

[0063] Furthermore, when the ground fault detection device 310 determines that the ground fault location is on the third conductive path 83 side, it switches the second interrupting unit 76 to the second interrupting state while maintaining the first interrupting unit 75 in the first permissive state. When the ground fault detection device 10 determines that the ground fault location is on the second conductive path 82 side, it switches the first interrupting unit 75 to the first interrupting state and switches the second interrupting unit 76 to the second interrupting state. In this way, the ground fault detection device 10 can prevent the power supply to the first load 71 from being stopped regardless of whether the ground fault location is on the second conductive path 82 side or the third conductive path 83 side, and can prevent the power supply to the second load 72 from being stopped when the ground fault location is on the second conductive path 82 side.

[0064] <Other embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, the features of the above or later described embodiments can be combined in any combination within a range that does not contradict. In addition, any feature of the above or later described embodiments can be omitted unless it is clearly stated as essential. Furthermore, the above-mentioned embodiment may be modified as follows.

[0065] In each of the above embodiments, the importance of a load is determined based on the functional safety level defined by ISO26262, but a different configuration may be used. For example, the importance of a load may be determined based on another regulation. In addition, in the above embodiments, the important load is a load to which ASIL-A to D is assigned, but a different configuration may be used. For example, the important load may be a load to which ASIL-B to D is assigned, a load to which ASIL-C to D is assigned, or only a load to which ASIL-D is assigned.

[0066] In each of the above embodiments, the first load includes only the important load, but the first load may include a load other than the important load. In each of the above embodiments, the second load includes only the electric power steering device, but the second load may include a load other than the electric power steering device.

[0067] In the first and second embodiments, the control circuit is configured to determine that a ground fault has occurred in at least one of the second and third conductive paths when the current flowing through the third conductive path exceeds a threshold current, but may be configured differently. For example, the control circuit may be configured to determine that a ground fault has occurred in at least one of the second and third conductive paths when the current flowing through the second conductive path exceeds a threshold current. Alternatively, the control circuit may determine that a ground fault has occurred in at least one of the second and third conductive paths when the voltage of the second conductive path becomes equal to or lower than a threshold voltage, or may determine that a ground fault has occurred in at least one of the second and third conductive paths when the voltage of the third conductive path becomes equal to or lower than a threshold voltage.

[0068] In the first and second embodiments, the ground fault location is determined to be the second conductive path when it is determined that the voltage of the second conductive path is equal to or lower than the threshold voltage, and the ground fault location is determined to be the third conductive path when it is determined that the voltage of the third conductive path is equal to or lower than the threshold voltage. However, the ground fault location may be determined to be the second conductive path when it is determined that the voltage of the second conductive path is equal to or lower than the threshold voltage, and the ground fault location may be determined to be the third conductive path when it is determined that the voltage of the second conductive path is not equal to or lower than the threshold voltage. Alternatively, the ground fault location may be determined to be the third conductive path when it is determined that the voltage of the third conductive path is equal to or lower than the threshold voltage, and the ground fault location may be determined to be the second conductive path when it is determined that the voltage of the third conductive path is not equal to or lower than the threshold voltage.

[0069] In the second embodiment, whether the ground fault location is the second conductive path or the third conductive path may be determined by the same determination method as in the third embodiment.

[0070] In the third embodiment, the current detection unit detects the current in the third conductive path, but the current detection unit may detect the current in the second conductive path. In this case, it is preferable that the current detection unit detects the current flowing through a path between the second interrupter and a branch point that is closest to the second interrupter among branch points at which the second branch path branches off from the second main path.

[0071] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims. [Explanation of symbols]

[0072] 10...Earth fault detection device 11...First voltage detection unit 12...Second voltage detection section 13...Current detection unit (detection unit) 14...Control circuit (detection section) 15…Power control ECU 15A...judgment section 15B…Control section 70…Load 71...1st load 72…Second load 73…Third load 74…Cutting section 75…First cutoff section 75A…Switching element 75B…Switching element 76…Second cutoff section 76A…Switching element 76B…Switching element 80…Conductive path 81…First conductive path 81A…First main route 81B…First turnoff 82...Second conductive path 82A…Second main route 82B…Second fork 83…Third conductive path 83A…Third main route 83B…Third fork 90...Power supply section 91…Electricity storage unit 93…First power supply box 94…Second power supply box 100…In-vehicle systems 200…In-vehicle system 300…In-vehicle system 310...Earth fault detection device

Claims

1. A ground fault detection device for use in an in-vehicle system including a power supply unit, a power storage unit different from the power supply unit, a conductive path provided between the power supply unit and the power storage unit, a load connected to the conductive path, and a breaker provided in the conductive path, the cutoff unit has a first cutoff unit provided between the power supply unit and the power storage unit, and a second cutoff unit provided closer to the power supply unit than the first cutoff unit, the conductive path includes a first conductive path provided between the storage unit and the first cutoff unit, a second conductive path provided between the first cutoff unit and the second cutoff unit, and a third conductive path provided between the second cutoff unit and the power supply unit, The loads include a first load including an important load, a second load including an electric power steering device, and a third load having a lower importance than the important load, The first load is connected to the first conductive path, the second load is connected to one of the second conductive path and the third conductive path; the third load is connected to the other of the second conductive path and the third conductive path; the first interrupter is switched between a first permissive state in which a current is permitted to flow from the first conductive path side to the second conductive path side and a first interruption state in which a current is interrupted; The second cutoff unit is switched between a second permissive state in which a current flows from the second conductive path side to the third conductive path side and from the third conductive path side to the second conductive path side, and a second cutoff state in which a current flows. a detection unit that detects a ground fault in at least one of the second conductive path and the third conductive path, a determination unit that, when a ground fault is detected in at least one of the second conductive path and the third conductive path by the detection unit, determines whether a ground fault location is on the second conductive path side or the third conductive path side, The determination unit determines whether a ground fault location is on the second conduction path side or the third conduction path side based on a voltage of at least one of the second conduction path and the third conduction path when the first interrupter unit is in the first interruption state and the second interrupter unit is in the second interruption state. Earth fault detection device.

2. a control unit that controls the first interrupting unit to the first interrupting state and the second interrupting unit to the second interrupting state when a ground fault is detected in at least one of the second conductive path and the third conductive path by the detection unit, The determination unit, in a state in which the first interrupting unit is controlled to the first interrupting state and the second interrupting unit is controlled to the second interrupting state by the control unit, determines whether a ground fault location is on the second conductive path side or the third conductive path side based on a voltage of at least one of the second conductive path and the third conductive path. The ground fault detection device according to claim 1 .

3. A ground fault detection device for use in an in-vehicle system including a power supply unit, a power storage unit different from the power supply unit, a conductive path provided between the power supply unit and the power storage unit, a load connected to the conductive path, and a breaker provided in the conductive path, the cutoff unit has a first cutoff unit provided between the power supply unit and the power storage unit, and a second cutoff unit provided closer to the power supply unit than the first cutoff unit, the conductive path includes a first conductive path provided between the storage unit and the first cutoff unit, a second conductive path provided between the first cutoff unit and the second cutoff unit, and a third conductive path provided between the second cutoff unit and the power supply unit, The loads include a first load including an important load, a second load including an electric power steering device, and a third load having a lower importance than the important load, The first load is connected to the first conductive path, the second load is connected to one of the second conductive path and the third conductive path; the third load is connected to the other of the second conductive path and the third conductive path; the first interrupter is switched between a first permissive state in which a current is permitted to flow from the first conductive path side to the second conductive path side and a first interruption state in which a current is interrupted; The second cutoff unit is switched between a second permissive state in which a current flows from the second conductive path side to the third conductive path side and from the third conductive path side to the second conductive path side, and a second cutoff state in which a current flows. a detection unit that detects a ground fault in at least one of the second conductive path and the third conductive path, a determination unit that, when a ground fault is detected in at least one of the second conductive path and the third conductive path by the detection unit, determines whether a ground fault location is on the second conductive path side or the third conductive path side, The determination unit has a current detection unit that detects a current flowing through at least one of the second conductive path and the third conductive path, and determines whether a ground fault location is on the second conductive path side or the third conductive path side based on a direction of a current flowing through at least one of the second conductive path and the third conductive path. Earth fault detection device.

4. A ground fault detection device for use in an in-vehicle system including a power supply unit, a power storage unit different from the power supply unit, a conductive path provided between the power supply unit and the power storage unit, a load connected to the conductive path, and a breaker provided in the conductive path, the cutoff unit has a first cutoff unit provided between the power supply unit and the power storage unit, and a second cutoff unit provided closer to the power supply unit than the first cutoff unit, the conductive path includes a first conductive path provided between the storage unit and the first cutoff unit, a second conductive path provided between the first cutoff unit and the second cutoff unit, and a third conductive path provided between the second cutoff unit and the power supply unit, The loads include a first load including an important load, a second load including an electric power steering device, and a third load having a lower importance than the important load, The first load is connected to the first conductive path, the second load is connected to one of the second conductive path and the third conductive path; the third load is connected to the other of the second conductive path and the third conductive path; the first interrupter is switched between a first permissive state in which a current is permitted to flow from the first conductive path side to the second conductive path side and a first interruption state in which a current is interrupted; The second cutoff unit is switched between a second permissive state in which a current flows from the second conductive path side to the third conductive path side and from the third conductive path side to the second conductive path side, and a second cutoff state in which a current flows. a detection unit that detects a ground fault in at least one of the second conductive path and the third conductive path, a determination unit that, when a ground fault is detected in at least one of the second conductive path and the third conductive path by the detection unit, determines whether a ground fault location is on the second conductive path side or the third conductive path side, The second load is connected to the second conductive path, a control unit that controls the first interrupting unit to the first permissive state and the second interrupting unit to the second interrupted state when the determination unit determines that the ground fault location is on the third conductive path side, and controls the first interrupting unit to the first interrupted state when the determination unit determines that the ground fault location is on the second conductive path side Earth fault detection device.

5. The second load is connected to the third conductive path. The ground fault detection device according to claim 2 .

6. The second load is connected to the second conductive path. The ground fault detection device according to any one of claims 1 to 3.

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