Power supply device

Abstract

The present invention provides a power supply device capable of maintaining power supply to a load.　The power supply device (10) is provided with: a first switch (31) provided to a first conductive path (81); a second switch (32) provided to a second conductive path (82); a power storage unit (34) for supplying power to a load (93) via a third conductive path (83); and a backflow prevention unit (35) for preventing the flow of current from the power storage unit (34) to the first switch (31) via the third conductive path (83) and the flow of current from the power storage unit (34) to the second switch (32) via the third conductive path (83).

Description

power supply device

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

[0002] Patent Document 1 discloses an on-board power supply device. This on-board power supply device includes a main power supply unit that supplies output power from a first on-board power supply to the input side of an important load via a main path via a main semiconductor switch, and a sub-power supply unit that supplies output power from a second on-board power supply to the input side of the important load via a sub-path via a sub-semiconductor switch. The on-board power supply device also includes a bypass power supply unit that supplies output power from the second on-board power supply to the input side of the important load via a bypass path that bypasses the main semiconductor switch and the sub-semiconductor switch.

[0003] Japanese Patent Application Laid-Open No. 2023-15871

[0004] In the configuration of Patent Document 1, two systems are provided as power supply paths to the load to achieve power supply redundancy, but measures to suppress power drops when switching power sources are insufficient.

[0005] The present disclosure has been made in light of the above-mentioned circumstances, and aims to provide a power supply device that can maintain power supplied to a load.

[0006] The power supply device of the present disclosure is a power supply device included in an in-vehicle system that includes a first power supply unit, a second power supply unit, a load, a first conduction path to which power is supplied from the first power supply unit, a second conduction path to which power is supplied from the second power supply unit, and a third conduction path provided between the load and a connection point between the first conduction path and the second conduction path, and includes: a first switch provided in the first conduction path; a second switch provided in the second conduction path; a storage unit that supplies power to the load via the third conduction path; and a backflow prevention unit that prevents current from flowing from the storage unit to the first switch via the third conduction path and from flowing from the storage unit to the second switch via the third conduction path.

[0007] The techniques disclosed herein may maintain power supplied to the load.

[0008] Fig. 1 is a block diagram illustrating an example of an in-vehicle system including a power supply device according to a first embodiment, Fig. 2 is a block diagram illustrating an example of an in-vehicle system including a power supply device according to a second embodiment, and Fig. 3 is a block diagram illustrating an example of an in-vehicle system including a power supply device according to a third embodiment.

[0009]

[0013] The following describes exemplary embodiments of the present disclosure: [1] A power supply device included in an in-vehicle system including a first power supply unit, a second power supply unit, a load, a first conduction path to which power is supplied from the first power supply unit, a second conduction path to which power is supplied from the second power supply unit, and a third conduction path provided between the load and a connection point between the first conduction path and the second conduction path, the power supply device including: a first switch provided in the first conduction path, a second switch provided in the second conduction path, a power storage unit that supplies power to the load via the third conduction path, and a backflow prevention unit that prevents a current from flowing from the power storage unit to the first switch via the third conduction path and a current from the power storage unit to the second switch via the third conduction path.

[0010] In the power supply device of [1] above, if a ground fault or the like occurs on the first power supply unit side of the first switch in the first conduction path, causing a power failure of the first power supply unit, the first switch can interrupt the first conduction path. Then, after a power failure of the first power supply unit, power can be supplied from the power storage unit to the load via the third conduction path. Similarly, in the event of a power failure of the second power supply unit, the second switch can interrupt the second conduction path, allowing power to be supplied from the power storage unit to the load after a power failure. Furthermore, the backflow prevention unit can prevent current from flowing from the power storage unit to the first switch via the third conduction path and from the power storage unit to the second switch via the third conduction path. Therefore, the power supply device can be configured to maintain power supplied to the load.

[0011] [2] The power supply device according to [1], wherein the backflow prevention unit is provided in the third conduction path between the storage unit and the connection point.

[0012] In the power supply device of [2] above, by providing a backflow prevention unit in the third conduction path, a configuration can be realized that prevents backflow from the storage unit to the first conduction path and the second conduction path, and therefore the configuration of the power supply device can be simplified compared to when backflow prevention units are provided in both the first conduction path and the second conduction path.

[0013] [3] The power supply device according to [1] or [2], wherein a third switch is provided in series with the backflow prevention unit in the third conductive path.

[0014] In the power supply device of [3] above, by cutting off the third conduction path using the third switch, it is possible to prevent overcurrent from flowing from the first conduction path side and the second conduction path side to the load side in the event of a ground fault in the load.

[0015] [4] A power supply device described in any one of [1] to [3], which is configured as a junction box and includes a case member that houses the first switch, the second switch, the storage unit, and the backflow prevention unit.

[0016] In the power supply device of [4] above, components such as the first switch, the second switch, the power storage unit, and the backflow prevention unit can be consolidated into a junction box, making the device more compact and simplifying its structure.

[0017] [5] A power supply device described in any of [1] to [4], comprising: a fourth conductive path electrically connected to both ends of the backflow prevention unit; and a resistor provided in the fourth conductive path, wherein the fourth conductive path is connected to the third conductive path at a second connection point; the storage unit is electrically connected in the fourth conductive path between the second connection point and the resistor; and a second backflow prevention unit provided in the fourth conductive path between the second connection point and the storage unit, which prevents current from flowing from the third conductive path to the storage unit via the second connection point.

[0018] In the power supply device of [5] above, since a resistor is provided in the fourth conduction path electrically connected to both ends of the backflow prevention unit, it is possible to prevent an inrush current from flowing from the side opposite to the second connection point in the fourth conduction path to the power storage unit when power supply from at least one of the first power supply unit and the second power supply unit starts. Also, since a second backflow prevention unit is provided in the fourth conduction path between the second connection point and the power storage unit, it is possible to prevent an inrush current from flowing from the second connection point side in the fourth conduction path to the power storage unit.

[0019] [6] The power supply device according to [5], further comprising a fourth switch provided in the third conductive path between the second connection point and the load.

[0020] In the power supply device of [6] above, by interrupting the third conduction path with the fourth switch, it is possible to prevent current from flowing from at least one of the first power supply unit and the second power supply unit to the load side via the resistor and the second backflow prevention unit, and to prevent current from flowing to the load side via the backflow prevention unit.

[0021] [Details of the embodiments of the present disclosure] 1. First embodiment 1-1. Overview of in-vehicle system 100 Fig. 1 shows an in-vehicle system 100 including a power supply device 10. The in-vehicle system 100 is a system mounted on a vehicle. The in-vehicle system 100 includes a first power supply unit 91, a second power supply unit 92, and a load 93. The in-vehicle system 100 can supply power from the first power supply unit 91 to the load 93, and can also supply power from the second power supply unit 92 to the load 93.

[0022] The in-vehicle system 100 includes a first conductive path 81, a second conductive path 82, and a third conductive path 83. The first conductive path 81 and the second conductive path 82 are provided between a first power supply unit 91 and a second power supply unit 92. One end of the first conductive path 81 is electrically connected to the first power supply unit 91. One end of the second conductive path 82 is electrically connected to the second power supply unit 92. The other end of the first conductive path 81 and the other end of the second conductive path 82 are electrically connected at a first connection point 71. The first connection point 71 corresponds to the "connection point" in this disclosure. The third conductive path 83 is provided between the first connection point 71 and a load 93. One end of the third conductive path 83 is electrically connected to the first connection point 71. The other end of the third conductive path 83 is electrically connected to the load 93.

[0023] 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.

[0024] The first conductive path 81 has a first electrical path 81A and a second electrical path 81B. The first electrical path 81A forms one end side (first power supply unit 91 side) of the first conductive path 81. The second electrical path 81B forms the other end side (first connection point 71 side) of the first conductive path 81.

[0025] The second conductive path 82 has a third electrical path 82A and a fourth electrical path 82B. The third electrical path 82A constitutes one end side (the second power supply unit 92 side) of the second conductive path 82. The fourth electrical path 82B constitutes the other end side (the first connection point 71 side) of the second conductive path 82.

[0026] The first power supply unit 91 supplies power to the first conductive path 81. The first power supply unit 91 is, for example, a high-voltage battery. The first power supply unit 91 may be, for example, a secondary battery such as a lithium-ion battery or a sodium-ion battery, or may be another type of storage battery. A high-potential terminal of the first power supply unit 91 is electrically connected to one end of the first conductive path 81.

[0027] The second power supply unit 92 supplies power to the second conductive path 82. The second power supply unit 92 is, for example, a low-voltage battery. The second power supply unit 92 may be, for example, a secondary battery such as a lithium-ion battery or a lead battery, or may be another type of storage battery. For example, the output voltage of the second power supply unit 92 is lower than the output voltage of the first power supply unit 91. A high-potential terminal of the second power supply unit 92 is electrically connected to one end of the second conductive path 82.

[0028] The load 93 is, for example, an electric load used in a vehicle, such as an electric brake.

[0029] 1-2. Configuration of the Power Supply Device 10 The power supply device 10 is, for example, an electrical connection box, more specifically, a junction box. The power supply device 10 is electrically connected to a first power supply unit 91, a second power supply unit 92, and a load 93.

[0030] The power supply device 10 includes a case member 20, a first terminal 21, a second terminal 22, and a third terminal 23. The case member 20 forms an outer shell of the power supply device 10. The first terminal 21, the second terminal 22, and the third terminal 23 are provided on the case member 20. The first terminal 21 is provided between a first power supply unit 91 and a first switch 31 (described later) (in the middle of a first electrical path 81A). The first terminal 21 is electrically connected to the first power supply unit 91 and receives power from the first power supply unit 91. The second terminal 22 is provided between a second power supply unit 92 and a second switch 32 (described later) (in the middle of a third electrical path 82A). The second terminal 22 is electrically connected to the second power supply unit 92 and receives power from the second power supply unit 92. The third terminal 23 is provided between a load 93 and a second connection point 72 (described later) (in the middle of a third conductive path 83). The third terminal 23 is electrically connected to a load 93 and a power storage unit 34 (described later).

[0031] The power supply device 10 includes a first switch 31 , a second switch 32 , and a control unit 33 .

[0032] The first switch 31 is provided in the first conductive path 81. The first switch 31 is provided between the first electrical path 81A and the second electrical path 81B. One end of the first switch 31 is electrically connected to the first electrical path 81A. The other end of the first switch 31 is electrically connected to the second electrical path 81B. The first switch 31 switches between a first permissive state in which it allows bidirectional current flow through itself and a first blocking state in which it blocks current flow from the second electrical path 81B to the first electrical path 81A. In this embodiment, the first switch 31 allows current to flow from the first electrical path 81A to the second electrical path 81B when in the first blocking state. The first switch 31 includes, for example, a MOSFET. The first switch 31 enters the first permissive state when the MOSFET is turned on. The first switch 31 enters the first blocking state when the MOSFET is turned off. The first switch 31 is, for example, an IPD (Intelligent Power Device) that includes a protection circuit and the like.

[0033] The second switch 32 is provided in the second conductive path 82. The second switch 32 is provided between the third electrical path 82A and the fourth electrical path 82B. One end of the second switch 32 is electrically connected to the third electrical path 82A. The other end of the second switch 32 is electrically connected to the fourth electrical path 82B. The second switch 32 switches between a second permissive state in which it allows bidirectional current flow through itself and a second blocked state in which it blocks current flow from the fourth electrical path 82B to the third electrical path 82A. In this embodiment, when the second switch 32 is in the second blocked state, it allows current to flow from the third electrical path 82A to the fourth electrical path 82B. The second switch 32 includes, for example, a MOSFET. The second switch 32 enters the second permissive state when the MOSFET is turned on. The second switch 32 enters the second blocked state when the MOSFET is turned off. The second switch 32 is, for example, an IPD (Intelligent Power Device) that includes a protection circuit and the like.

[0034] The control unit 33 is an information processing device having information processing functions, calculation functions, control functions, etc. The control unit 33 is mainly configured with, for example, a microcomputer, and has a calculation device such as a CPU (Central Processing Unit), memories such as a ROM (Read Only Memory) or a RAM (Random Access Memory), etc. The control unit 33 has a function of transmitting control signals to the first switch 31, the second switch 32, etc. to control their operations.

[0035] When the first switch 31 is in the first permissive state and the second switch 32 is in the second permissive state, the control unit 33 can supply power to the load 93 from both the first power supply unit 91 and the second power supply unit 92. When the first switch 31 is in the first permissive state and the second switch 32 is in the second permissive state, it is preferable that power be supplied to the load 93 from the first power supply unit 91.

[0036] The power supply device 10 includes an abnormality detection unit (not shown). The abnormality detection unit functions to determine whether a ground fault has occurred in the first electrical path 81A or the third electrical path 82A. While the following describes an example of a configuration for determining whether a ground fault has occurred in the third electrical path 82A, a configuration for determining whether a ground fault has occurred in the first electrical path 81A may also be provided.

[0037] The abnormality detection unit includes, for example, a current detection unit (current sensor) (not shown) provided in the second conductive path 82 (e.g., the fourth electrical path 82B). The current detection unit detects the magnitude and direction of a current flowing through the second conductive path 82. The current detection unit detects a current flowing from the second power supply unit 92 side to the first connection point 71 side, and also detects a current flowing from the first connection point 71 side to the second power supply unit 92 side. For example, if a ground fault occurs in the third electrical path 82A when the first switch 31 is in the first permissive state and the second switch 32 is in the second permissive state, currents from the first power supply unit 91 and the second power supply unit 92 flow through the third electrical path 82A. When the current detection unit detects a current flowing from the first connection point 71 side to the second power supply unit 92 side, the abnormality detection unit can determine that a ground fault has occurred in the third electrical path 82A. In addition, the abnormality detection unit may use the current detection unit to detect the current flowing from the first connection point 71 side to the second power supply unit 92 side, and if the current value exceeds a threshold current, determine that a ground fault has occurred in the third electrical path 82A.

[0038] The abnormality detection unit includes, for example, a voltage detection unit (voltage detection circuit) (not shown) provided in the second conductive path 82. The voltage detection unit detects the voltage of the second conductive path 82 (more specifically, the third electrical path 82A). For example, if a ground fault occurs in the second conductive path 82 when the first switch 31 is in the first permissive state and the second switch 32 is in the second permissive state, current from the first power supply unit 91 and current from the second power supply unit 92 flow through the second conductive path 82. If the voltage of the second conductive path 82 becomes equal to or lower than a threshold voltage, it can be determined that a ground fault has occurred in the third electrical path 82A.

[0039] The power supply device 10 further includes a power storage unit 34 and a backflow prevention unit 35. The case member 20 accommodates the first switch 31, the second switch 32, the control unit 33, the power storage unit 34, and the backflow prevention unit 35.

[0040] The power storage unit 34 supplies power to the load 93 via the third conductive path 83. The power storage unit 34 is configured, for example, by an electric double layer capacitor or the like. The power storage unit 34 may be configured, for example, by connecting a plurality of electric double layer capacitors in series. One end of the power storage unit 34 is electrically connected to the third conductive path 83. The power storage unit 34 is connected to the third conductive path 83 via a conductive path 34A. One end of the conductive path 34A is connected to the second connection point 72 of the third conductive path 83. The other end of the conductive path 34A is connected to one end of the power storage unit 34.

[0041] The backflow prevention unit 35 is provided in the third conductive path 83 between the power storage unit 34 and the first connection point 71. The backflow prevention unit 35 prevents current from flowing from the power storage unit 34 to the first switch 31 via the third conductive path 83 and from flowing from the power storage unit 34 to the second switch 32 via the third conductive path 83. The backflow prevention unit 35 is configured by a rectifier diode (e.g., an ideal diode) such as a PN junction diode. The anode of the backflow prevention unit 35 is electrically connected to the first connection point 71. A voltage based on the power supply voltage of the first power supply unit 91 and a voltage based on the power supply voltage of the second power supply unit 92 are applied to the anode of the backflow prevention unit 35. The cathode of the backflow prevention unit 35 is electrically connected to the second connection point 72.

[0042] 1-3. Example of Operation of Power Supply Device 10 When a start condition is met, the control unit 33 switches the first switch 31 from the first cut-off state to the first permissive state, and switches the second switch 32 from the second cut-off state to the second permissive state. As a result, power is supplied from the first power supply unit 91 or the second power supply unit 92 to the load 93. The start condition may be, for example, that the start switch of the vehicle is switched from the OFF state to the ON state, or may be another condition. The start switch is an ignition switch in the case of an engine-equipped vehicle, and a power switch in the case of an electric vehicle.

[0043] For example, if a ground fault occurs in the third electrical path 82A when the first switch 31 is in the first permissive state and the second switch 32 is in the second permissive state, current from the first power supply unit 91 and current from the second power supply unit 92 flow through the third electrical path 82A. As a result, current flows from the first connection point 71 to the second power supply unit 92, the ground fault is detected by the abnormality detection unit, and the control unit 33 switches the second switch 32 from the second permissive state to the second cut-off state. As a result, the flow of current from the first connection point 71 to the second power supply unit 92 is cut off, and power from the first power supply unit 91 is supplied to the load 93.

[0044] As described above, in the power supply device 10, when a ground fault or the like occurs in the third electrical path 82A, causing a power failure of the second power supply unit 92, the second conductive path can be interrupted by the second switch 32. After a power failure of the second power supply unit 92, power can be supplied from the power storage unit 34 to the load 93 via the third conductive path 83, so that the power supply to the load 93 can be maintained seamlessly. Specifically, after a ground fault or the like is detected by the abnormality detection unit, power can be supplied from the power storage unit 34 to the load 93 until the second switch 32 is switched from the second permissive state to the second cut-off state.

[0045] Furthermore, the backflow prevention unit 35 can prevent a current from flowing from the power storage unit 34 to the first switch 31 via the third conductive path 83, and a current from the power storage unit 34 to the second switch 32 via the third conductive path 83. This allows the power storage unit 34 to supply power only to the load 93.

[0046] For example, after switching the second switch 32 to the second cut-off state, the control unit 33 may maintain the second switch 32 in the second cut-off state even if current no longer flows from the first connection point 71 to the second power supply unit 92. After switching the second switch 32 to the second cut-off state, the control unit 33 returns the second switch 32 to the second permissive state if a recovery condition is satisfied. The recovery condition may be, for example, a condition that is met every time a predetermined time period elapses. The recovery condition may be that the output voltage of the second power supply unit 92 becomes equal to or greater than a recovery voltage. The recovery condition may be that the temperature of the second switch 32 becomes equal to or greater than a recovery temperature.

[0047] Furthermore, when a ground fault occurs in the first electrical path 81A, the power supply device 10 can perform the same control as when a ground fault occurs in the third electrical path 82A. For example, if a ground fault occurs in the first electrical path 81A while the first switch 31 is in the first permissive state and the second switch 32 is in the second permissive state, current from the first power supply unit 91 and current from the second power supply unit 92 flow through the first electrical path 81A. As a result, current flows from the first connection point 71 to the first power supply unit 91, the ground fault is detected by the abnormality detection unit, and the control unit 33 switches the first switch 31 from the first permissive state to the first cut-off state. As a result, the flow of current from the first connection point 71 to the first power supply unit 91 is cut off, and power from the second power supply unit 92 is supplied to the load 93.

[0048] After a power failure of the first power supply unit 91, power can be supplied from the power storage unit 34 to the load 93 via the third conductive path 83, thereby seamlessly maintaining power supply to the load 93. Specifically, after a ground fault or the like is detected by the abnormality detection unit, power can be supplied from the power storage unit 34 to the load 93 until the first switch 31 is switched from the first permissive state to the first blocked state. Furthermore, the backflow prevention unit 35 can prevent current from flowing from the power storage unit 34 to the first switch 31 via the third conductive path 83 and from the power storage unit 34 to the second switch 32 via the third conductive path 83. This allows power to be supplied from the power storage unit 34 only to the load 93.

[0049] 1-4. Example of Effects of the Power Supply Device 10 In the power supply device 10, in the case where a ground fault or the like occurs on the first power supply unit 91 side of the first switch 31 in the first conduction path 81, causing a power failure of the first power supply unit 91, the first switch 31 can interrupt the first conduction path 81. After a power failure of the first power supply unit 91, power can be supplied from the power storage unit 34 to the load 93 via the third conduction path 83, thereby maintaining the power supply to the load 93. Similarly, in the case where a power failure occurs in the second power supply unit 92, the second switch 32 can interrupt the second conduction path 82, thereby maintaining the power supply from the power storage unit 34 to the load 93 after a power failure. Furthermore, the backflow prevention unit 35 can prevent current from flowing from the power storage unit 34 to the first switch 31 via the third conduction path 83 and from the power storage unit 34 to the second switch 32 via the third conduction path 83. Therefore, the power supply device 10 can achieve a configuration that can maintain the power supply to the load 93.

[0050] In the power supply device 10, the backflow prevention unit 35 is provided in the third conductive path 83 between the power storage unit 34 and the first connection point 71. Thus, in the power supply device 10, by providing the backflow prevention unit 35 in the third conductive path 83, a configuration can be realized that prevents backflow from the power storage unit 34 to the first conductive path 81 and the second conductive path 82. Therefore, the power supply device 10 can have a simpler configuration than when the backflow prevention unit 35 is provided in both the first conductive path 81 and the second conductive path 82.

[0051] 2. Second Embodiment A power supply device 210 of the second embodiment differs from the first embodiment in that a third switch 236 is provided in the third conductive path 83. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0052] 2 , the in-vehicle system 200 includes a power supply device 210. The power supply device 210 further includes a third switch 236. The case member 20 accommodates the first switch 31, the second switch 32, the control unit 33, the power storage unit 34, the backflow prevention unit 35, and the third switch 236.

[0053] The third switch 236 is provided in series with the backflow prevention unit 35 in the third conductive path 83, between the first connection point 71 and the backflow prevention unit 35. One end of the third switch 236 is electrically connected to the first connection point 71. The other end of the third switch 236 is electrically connected to the anode of the backflow prevention unit 35. The third switch 236 switches between a third permissive state in which bidirectional current flow is permitted through the third switch 236 and a third blocked state in which current flow from the first connection point 71 to the backflow prevention unit 35 is blocked. The third switch 236 includes, for example, a MOSFET. The third switch 236 enters the third permissive state when the MOSFET is turned on. The third switch 236 enters the third blocked state when the MOSFET is turned off. The third switch 236 is, for example, an IPD (Intelligent Power Device) incorporating a protection circuit, etc.

[0054] The control unit 33 controls the operation by transmitting a control signal to the third switch 236. The third switch 236 may be configured as, for example, a pair of MOSFETs having parasitic diodes oriented in opposite directions.

[0055] For example, consider a case in which a ground fault or the like occurs in the load 93 while the power supply device 210 is in a state in which the start condition is satisfied, the first switch 31 is in the first permissive state, the second switch 32 is in the second permissive state, and power is being supplied to the load 93 from the first power supply unit 91 or the second power supply unit 92. A ground fault in the load 93 can be detected by providing an abnormality detection unit in the third conduction path 83 that has a configuration similar to the abnormality detection unit described above. For example, the abnormality detection unit can determine that a ground fault has occurred in the load 93 when the current flowing from the second connection point 72 to the load 93 exceeds a threshold current. Furthermore, for example, it can determine that a ground fault has occurred in the third conduction path 83 when the voltage of the third conduction path 83 becomes equal to or lower than a threshold voltage.

[0056] When the abnormality detection unit detects a ground fault in the load 93, the control unit 33 switches the third switch 236 from the third permissive state to the third cut-off state, thereby cutting off the flow of current from the first connection point 71 side to the load 93 side. By cutting off the third conductive path 83 with the third switch 236 in this way, it is possible to prevent overcurrent from flowing from the first conductive path 81 side and the second conductive path 82 side to the load 93 side in the event of a ground fault in the load 93.

[0057] Furthermore, if the first switch 31 is configured to allow current to flow from the first electrical path 81A to the second electrical path 81B when it is in the first cut-off state, i.e., if it is a MOSFET having a parasitic diode that allows current to flow from the first electrical path 81A to the second electrical path 81B, then by setting the third switch 236 to the third cut-off state, it is possible to prevent dark current from flowing from the first power supply unit 91 or the second power supply unit 92.

[0058] 3. Third Embodiment A power supply device 310 of the third embodiment differs from the first embodiment in that some components have been added. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0059] 3 , the in-vehicle system 300 further includes a fourth conductive path 384. The fourth conductive path 384 is electrically connected to both ends of the backflow prevention unit 35. One end of the fourth conductive path 384 is connected to the second conductive path (fourth electrical path 82B) at the third connection point 373. The other end of the fourth conductive path 384 is connected to the third conductive path 83 at the second connection point 372.

[0060] The power supply device 310 further includes a resistor 337, a second backflow prevention unit 338, and a fourth switch 339. The case member 20 accommodates the first switch 31, the second switch 32, the control unit 33, the power storage unit 34, the backflow prevention unit 35, the resistor 337, the second backflow prevention unit 338, and the fourth switch 339.

[0061] The power storage unit 34 is connected to the fourth conductive path 384 via a conductive path 334A. One end of the conductive path 334A is connected to a fourth connection point 374 in the fourth conductive path 384. The other end of the conductive path 334A is connected to one end of the power storage unit 34. The power storage unit 34 is electrically connected in the fourth conductive path 384 between the second connection point 372 and a resistor 337 (described later).

[0062] The resistor 337 is provided in the fourth conductive path 384 between the second connection point 372 and the fourth connection point 374. One end of the resistor 337 is electrically connected to the second connection point 372. The other end of the resistor 337 is electrically connected to the fourth connection point 374.

[0063] The second reverse current prevention unit 338 is provided in the fourth conductive path 384 between the second connection point 372 and the power storage unit 34. The second reverse current prevention unit 338 prevents current from flowing from the third conductive path 83 to the power storage unit 34 via the second connection point 372. The second reverse current prevention unit 338 is configured by a rectifier diode (e.g., an ideal diode) such as a PN junction diode. The anode of the second reverse current prevention unit 338 is electrically connected to the fourth connection point 374. The cathode of the second reverse current prevention unit 338 is electrically connected to the second connection point 372.

[0064] In the power supply device 310, the resistor 337 is provided in the fourth conductive path 384 electrically connected to both ends of the backflow prevention unit 35, so that it is possible to prevent an inrush current from flowing from the side of the fourth conductive path 384 opposite the second connection point 372 to the power storage unit 34 when power supply from at least one of the first power supply unit 91 and the second power supply unit 92 starts. Furthermore, the second backflow prevention unit 338 is provided in the fourth conductive path 384 between the second connection point 372 and the power storage unit 34, so that it is possible to prevent an inrush current from flowing from the second connection point 372 side to the power storage unit 34 in the fourth conductive path 384.

[0065] The fourth switch 339 is provided in the third conductive path 83 between the second connection point 372 and the load 93. One end of the fourth switch 339 is electrically connected to the second connection point 372. The other end of the fourth switch 339 is electrically connected to the load 93. The fourth switch 339 switches between a fourth permissive state in which it allows bidirectional current flow through itself and a fourth blocked state in which it blocks current flow from the load 93 side to the first connection point 71 side. The fourth switch 339 includes, for example, a MOSFET. The fourth switch 339 enters the fourth permissive state when the MOSFET is turned on. The fourth switch 339 enters the fourth blocked state when the MOSFET is turned off. The fourth switch 339 is, for example, an intelligent power device (IPD) incorporating a protection circuit and the like.

[0066] The control unit 33 controls the operation by transmitting a control signal to the fourth switch 339. The fourth switch 339 may be configured as, for example, a pair of MOSFETs having parasitic diodes oriented in opposite directions.

[0067] In the power supply device 310, by interrupting the third conductive path 83 with the fourth switch 339, it is possible to prevent a current from flowing from at least one of the first power supply unit 91 and the second power supply unit 92 to the load 93 side via the resistor 337 and the second backflow prevention unit 338, and a current from flowing to the load 93 side via the backflow prevention unit 35. In this way, by interrupting the third conductive path 83 with the fourth switch 339, it is possible to prevent an overcurrent from flowing from the first conductive path 81 side and the second conductive path 82 side to the load 93 side in the event of a ground fault in the load 93.

[0068] <Other Embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or below-described embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or below-described embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiments may be modified as follows.

[0069] In the first to third embodiments, the backflow prevention unit 35 is provided in the third conductive path 83. However, in addition to or instead of being provided in the third conductive path 83, the backflow prevention unit 35 may be provided in at least one of the first conductive path 81 and the second conductive path 82. When the backflow prevention unit 35 is provided in the first conductive path 81, the anode of the backflow prevention unit 35 is electrically connected to the first power supply unit 91, and the cathode is electrically connected to the first connection point 71. Similarly, when the backflow prevention unit 35 is provided in the second conductive path 82, the anode of the backflow prevention unit 35 is electrically connected to the second power supply unit 92, and the cathode is electrically connected to the first connection point 71.

[0070] In the first to third embodiments, the first power supply unit 91 is configured as a battery. However, the first power supply unit 91 may include a battery and a voltage conversion unit. The voltage conversion unit is configured, for example, by a DC-DC converter. The voltage conversion unit increases or decreases the voltage input from the battery side and outputs it to the first conduction path 81 side. The voltage conversion unit also performs a conversion operation of increasing or decreasing the voltage input from the first conduction path 81 side and outputting it to the battery side.

[0071] In the first to third embodiments, the first switch 31 is configured to allow current to flow from the first electrical path 81A to the second electrical path 81B when in the first interruption state. However, the first switch 31 may also be configured to interrupt current flow from the second electrical path 81B to the first electrical path 81A when in the first interruption state. For example, the first switch 31 may be configured as a pair of MOSFETs arranged in series and having parasitic diodes oriented in opposite directions (butted together).

[0072] In the first to third embodiments, the second switch 32 is configured to allow current to flow from the third electrical path 82A to the fourth electrical path 82B when in the second cutoff state. However, the second switch 32 may also be configured to cut off current flow from the fourth electrical path 82B to the third electrical path 82A when in the second cutoff state. For example, the second switch 32 may be configured as a pair of MOSFETs having parasitic diodes oriented in opposite directions.

[0073] In the first to third embodiments, the first switch 31 and the second switch 32 are configured as MOSFETs. However, the first switch 31 and the second switch 32 may be configured as mechanical switches.

[0074] In the first to third embodiments, the backflow prevention unit 35 is configured as a diode. However, the backflow prevention unit 35 may be configured as a parasitic diode of a MOSFET provided between the first connection point 71 and the second connection point 72 in the third conductive path 83.

[0075] In the first to third embodiments, a conductive path may be provided that branches off from the first conductive path 81 or the second conductive path 82 to supply power to a load other than the load 93 .

[0076] In the third embodiment, one end of the fourth conductive path 384 is connected to the second conductive path 82. However, one end of the fourth conductive path 384 may be connected to the first conductive path 81.

[0077] 10: Power supply device 20: Case member 21: First terminal 22: Second terminal 23: Third terminal 31: First switch 32: Second switch 33: Control unit 34: Power storage unit 34A: Conduction path 35: Backflow prevention unit 71: First connection point (connection point) 72: Second connection point 81: First conduction path 81A: First electrical path 81B: Second electrical path 82: Second conduction path 82A: Third electrical path 82B: Fourth electrical path 83: Third conduction path 91: First power supply unit 92: Second power supply unit 93: Load 100: In-vehicle system 200: In-vehicle system 210: Power supply device 236: Third switch 300: In-vehicle system 310: Power supply device 334A: Conduction path 337: Resistor 338: Second backflow prevention unit 339: Fourth switch 372: Second connection point 373: Third connection point 374: Fourth connection point 384: Fourth conductive path

Claims

1. A power supply device included in an in-vehicle system comprising a first power supply unit, a second power supply unit, a load, a first conductive path to which power is supplied from the first power supply unit, a second conductive path to which power is supplied from the second power supply unit, and a third conductive path provided between the load and a connection point between the first conductive path and the second conductive path, the power supply device comprising: a first switch provided on the first conductive path; a second switch provided on the second conductive path; a power storage unit that supplies power to the load via the third conductive path; and a backflow prevention unit that prevents current flow from the power storage unit to the first switch via the third conductive path and current flow from the power storage unit to the second switch via the third conductive path.

2. The power supply device according to claim 1, wherein the reverse flow prevention section is provided in the third conductive path, between the power storage section and the connection point.

3. A power supply device according to claim 1 or 2, wherein a third switch is provided in series with the reverse current prevention section in the third conductive path.

4. A power supply device as described in claim 1 or claim 2, comprising a case member that houses the first switch, the second switch, the power storage unit, and the backflow prevention unit, and configured as a junction box.

5. A power supply device as described in claim 1 or claim 2, comprising: a fourth conductive path electrically connected to both ends of the reverse flow prevention unit; and a resistor provided in the fourth conductive path, wherein the fourth conductive path is connected to the third conductive path at a second connection point, the storage unit is electrically connected in the fourth conductive path between the second connection point and the resistor, and a second reverse flow prevention unit provided in the fourth conductive path between the second connection point and the storage unit, for preventing a flow of current from the third conductive path to the storage unit via the second connection point.

6. The power supply device according to claim 5, further comprising a fourth switch provided in the third conductive path between the second connection point and the load.

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