Power supply device

Abstract

To provide a power supply device capable of maintaining power supply to a load.SOLUTION: A power supply device 10 includes a first switch 31 provided in a first conductive path 81, a second switch 32 provided in a second conductive path 82, a storage unit 34 that supplies power to a load 93 via a third conductive path 83, and a backflow prevention unit 35 that prevents the flow of current from the storage unit 34 to the first switch 31 via the third conductive path 83, and the flow of current from the storage unit 34 to the second switch 32 via the third conductive path 83.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an in-vehicle power supply device. This in-vehicle power supply device includes a main power supply unit that supplies the output power of a first in-vehicle power source to the input side of an important load through a main path via a main semiconductor switch, and a sub power supply unit that supplies the output power of a second in-vehicle power source to the input side of the important load through a sub path via a sub semiconductor switch. Further, the in-vehicle power supply device includes a bypass power supply unit that supplies the output power of the second in-vehicle power source to the input side of the important load through a bypass path that bypasses the main semiconductor switch and the sub semiconductor switch.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration of Patent Document 1, two systems are provided as power supply paths for the load to achieve redundancy of the power source, but the measures for suppressing power reduction during power source switching are not sufficient.

[0005] The present disclosure has been made based on the above circumstances, and an object thereof is to provide a power supply device capable of maintaining the power supplied to the load.

Means for Solving the Problems

[0006] The power supply device of the present disclosure is 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 through which power is supplied from the first power supply unit; a second conductive path through which power is supplied from the second power supply unit; and a third conductive path provided between a connection point of the first conductive path and the second conductive path and the load. a first switch provided in the first conductive path; a second switch provided in the second conductive path; a power storage unit that supplies power to the load via the third conductive path; a backflow prevention unit that prevents a current from flowing from the power storage unit to the first switch and from the power storage unit to the second switch via the third conductive path; and comprising the above.

Effect of the Invention

[0007] The technology according to the present disclosure can maintain the power supplied to the load.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be listed and exemplified. 〔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 through which power is supplied from the first power supply unit; a second conductive path through which power is supplied from the second power supply unit; and a third conductive path provided between a connection point of the first conductive path and the second conductive path and the load. a first switch provided in the first conductive path; a second switch provided in the second conductive path; a power storage unit that supplies power to the load via the third conductive path; a backflow prevention unit that prevents the flow of current from the power storage unit to the first switch and from the power storage unit to the second switch via the third conductive path; A power supply device comprising the above.

[0010] In the power supply device of the above [1], when a ground fault or the like occurs on the first power supply unit side of the first switch in the first conductive path and the power supply of the first power supply unit fails, the first switch can cut off the first conductive path. Then, after the power supply of the first power supply unit fails, power can be supplied from the power storage unit to the load via the third conductive path. Similarly, when the power supply of the second power supply unit fails, the second switch can cut off the second conductive path, and power can be supplied from the power storage unit to the load after the power supply fails. Moreover, the backflow prevention unit can prevent the flow of current from the power storage unit to the first switch and from the power storage unit to the second switch via the third conductive path. Therefore, the power supply device can realize a configuration capable of maintaining the power supplied to the load.

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

[0012] In the power supply device of the above [2], by providing the backflow prevention unit in the third conductive path, a configuration for preventing backflow from the power storage unit to the first conductive path and the second conductive path can be realized. Therefore, the power supply device can simplify the configuration as compared with the case where backflow prevention units are provided in both the first conductive path and the second conductive 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 the above [3], by interrupting the third conductive path with the third switch, it is possible to prevent overcurrent from flowing from the first conductive path side and the second conductive path side to the load side when the load is grounded.

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

[0016] In the power supply device of the above [4], components such as the first switch, the second switch, the power storage unit, and the backflow prevention unit can be integrated into a junction box, achieving compactification of the device and simplification of the structure.

[0017] 〔5〕A power supply device according to any one of [1] to [4], comprising a fourth conductive path electrically connected to both ends of the backflow prevention unit, and a resistor provided on the fourth conductive path, wherein the fourth conductive path is connected to the third conductive path at a second connection point, the power storage unit is electrically connected between the second connection point and the resistor in the fourth conductive path, and a second backflow prevention unit is provided between the second connection point and the power storage unit in the fourth conductive path to prevent the flow of current from the third conductive path to the power storage unit through the second connection point.

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

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

[0020] In the power supply device of the above [6], by shutting off the third conductive path with the fourth switch, the flow of current 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 reverse current prevention unit, and the flow of current to the load side via the reverse current prevention unit can be prevented.

[0021] [Details of Embodiments of the Present Disclosure] 1. First Embodiment 1-1. Outline 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 the first power supply unit 91 and the second power supply unit 92. The first power supply unit 91 is electrically connected to one end of the first conductive path 81. The second power supply unit 92 is electrically connected to one end of the second conductive path 82. 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" of the present disclosure. The third conductive path 83 is provided between the first connection point 71 and the load 93. One end of the third conductive path 83 is electrically connected to the first connection point 71. The load 93 is electrically connected to the other end of the third conductive path 83.

[0023] In the present disclosure, "electrically connected" preferably means a configuration in which both connection targets are electrically connected in a conductive state (a state in which current can flow) so that the electric potentials of both connection targets are equal. However, it is not limited to this configuration. For example, "electrically connected" may mean a configuration in which both connection targets are connected in a state where an electrical component is interposed between them and both connection targets can conduct.

[0024] The first conductive path 81 has a first electrical path 81A and a second electrical path 81B. The first electrical path 81A constitutes one end side (the first power supply unit 91 side) of the first conductive path 81. The second electrical path 81B constitutes the other end side (the 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 constituted by a secondary battery such as a lithium-ion battery or a sodium-ion battery, or may be constituted by other types of storage batteries. The high-potential side 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 constituted by a secondary battery such as a lithium-ion battery or a lead battery, or may be constituted by other types of storage batteries. 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. The high-potential side 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 electrical load used in a vehicle. The load 93 is, for example, an electric brake or the like.

[0029] 1-2. Configuration of the power supply device 10 The power supply device 10 is, for example, an electrical connection box, and more specifically, a junction box. The power supply device 10 is electrically connected to the first power supply unit 91, the second power supply unit 92, and the 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 constitutes the 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 the first power supply unit 91 and a first switch 31 (to be described later) (in the middle of the first electrical path 81A). The first power supply unit 91 is electrically connected to the first terminal 21, and power from the first power supply unit 91 is supplied thereto. The second terminal 22 is provided between the second power supply unit 92 and a second switch 32 (to be described later) (in the middle of the third electrical path 82A). The second power supply unit 92 is electrically connected to the second terminal 22, and power from the second power supply unit 92 is supplied thereto. The third terminal 23 is provided between the load 93 and a second connection point 72 (to be described later) (in the middle of the third conductive path 83). The load 93 and a power storage unit 34 (to be described later) are electrically connected to the third terminal 23.

[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 on 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 allowable state that allows a bidirectional current flow therethrough and a first cutoff state that blocks the current flow from the second electrical path 81B to the first electrical path 81A. In the present embodiment, when the first switch 31 is in the first cutoff state, it allows current to flow from the first electrical path 81A to the second electrical path 81B. The first switch 31 includes, for example, a MOSFET. The first switch 31 enters the first allowable state when the MOSFET is in the ON state. The first switch 31 enters the first cutoff state when the MOSFET is in the OFF state. The first switch 31 is, for example, an IPD (Intelligent Power Device) incorporating a protection circuit or 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 allow state that allows a bidirectional current flow therethrough and a second cut-off state that cuts off the current flow from the fourth electrical path 82B to the third electrical path 82A. In the present embodiment, the second switch 32 allows current to flow from the third electrical path 82A to the fourth electrical path 82B when in the second cut-off state. The second switch 32 includes, for example, a MOSFET. The second switch 32 enters the second allow state when the MOSFET is in the ON state. The second switch 32 enters the second cut-off state when the MOSFET is in the OFF state. The second switch 32 is, for example, an IPD (Intelligent Power Device) incorporating a protection circuit or the like.

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

[0035] When the first switch 31 is in the first allow state and the second switch 32 is in the second allow 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 allow state and the second switch 32 is in the second allow state, it is preferable that power is supplied from the first power supply unit 91 to the load 93.

[0036] The power supply device 10 has an abnormality detection unit (not shown). The abnormality detection unit functions to determine whether or not a ground fault has occurred in the first electric path 81A or the third electric path 82A. Hereinafter, a configuration for determining whether or not a ground fault has occurred in the third electric path 82A will be exemplified, but a configuration for determining whether or not a ground fault has occurred in the first electric path 81A can be provided in the same manner.

[0037] The abnormality detection unit has, for example, a current detection unit (current sensor, not shown) provided in the second conductive path 82 (for example, the fourth electric path 82B). The current detection unit detects the magnitude and direction of the current flowing through the second conductive path 82. The current detection unit detects the current flowing from the second power supply unit 92 side to the first connection point 71 side, and also detects the current flowing from the first connection point 71 side to the second power supply unit 92 side. For example, when the third electric path 82A is grounded while the first switch 31 is in the first allowable state and the second switch 32 is in the second allowable state, the current from the first power supply unit 91 and the current from the second power supply unit 92 flow through the third electric path 82A. When the abnormality detection unit detects, by the current detection unit, the current flowing from the first connection point 71 side to the second power supply unit 92 side, it can be determined that a ground fault has occurred in the third electric path 82A. Further, when the abnormality detection unit detects, by the current detection unit, the current flowing from the first connection point 71 side to the second power supply unit 92 side and the value of the current exceeds the threshold current, it may be determined that a ground fault has occurred in the third electric path 82A.

[0038] The abnormality detection unit has, 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 electric path 82A). For example, when the second conductive path 82 is grounded while the first switch 31 is in the first allowable state and the second switch 32 is in the second allowable state, the current from the first power supply unit 91 and the current from the second power supply unit 92 flow through the second conductive path 82. When the voltage of the second conductive path 82 becomes equal to or lower than the threshold voltage, it can be determined that a ground fault has occurred in the third electric 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 houses 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 constituted by, for example, an electric double layer capacitor or the like. The power storage unit 34 may have a configuration in which, for example, a plurality of electric double layer capacitors are connected 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 the conductive path 34A. One end of the conductive path 34A is connected to the second connection point 72 in 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 between the power storage unit 34 and the first connection point 71 in the third conductive path 83. The backflow prevention unit 35 prevents the flow of current from the power storage unit 34 to the first switch 31 and the flow of current from the power storage unit 34 to the second switch 32 via the third conductive path 83. The backflow prevention unit 35 is constituted by a rectifying diode (for example, 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. The voltage based on the power supply voltage of the first power supply unit 91 and the 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. Operating example of the power supply device 10 When the start condition is satisfied, the control unit 33 switches the first switch 31 from the first cut-off state to the first allowable state and switches the second switch 32 from the second cut-off state to the second allowable state. Thereby, the power from the first power supply unit 91 or the second power supply unit 92 is supplied to the load 93. The start condition may be, for example, that the start switch of the vehicle has been 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-mounted vehicle and a power switch in the case of an electric vehicle.

[0043] For example, when the first switch 31 is in the first allowable state and the second switch 32 is in the second allowable state, if the third electrical path 82A is short-circuited, the current from the first power supply unit 91 and the 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 side to the second power supply unit 92 side, a short circuit is detected by the above-mentioned abnormality detection unit, and the control unit 33 switches the second switch 32 from the second allowable state to the second cut-off state. Thereby, the flow of current from the first connection point 71 side to the second power supply unit 92 side is blocked, and the 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 short circuit or the like occurs in the third electrical path 82A and the second power supply unit 92 loses power, the second conductive path can be blocked by the second switch 32. And after the second power supply unit 92 loses power, 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 an abnormality such as a short circuit 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 allowable state to the second cut-off state.

[0045] Furthermore, the reverse current prevention unit 35 can prevent the current from flowing from the power storage unit 34 to the first switch 31 via the third conductive path 83 and the current from flowing from the power storage unit 34 to the second switch 32 via the third conductive path 83. Thereby, the power supply destination from the power storage unit 34 can be limited to only the load 93.

[0046] For example, after the control unit 33 switches the second switch 32 to the second cutoff state, even if the current from the first connection point 71 side to the second power supply unit 92 side stops flowing, the control unit 33 may maintain the second switch 32 in the second cutoff state. After the control unit 33 switches the second switch 32 to the second cutoff state, if the return condition is satisfied, the control unit 33 returns the second switch 32 to the second allowable state. The return condition may be a condition that is established, for example, every time a predetermined time elapses. The return condition may be that the output voltage of the second power supply unit 92 has become equal to or higher than the return voltage. The return condition may be that the temperature of the second switch 32 has become equal to or higher than the return temperature.

[0047] In addition, even when the first electrical path 81A is grounded, the power supply device 10 can perform the same control as when the third electrical path 82A is grounded. For example, when the first switch 31 is in the first allowable state and the second switch 32 is in the second allowable state, if the first electrical path 81A is grounded, the current from the first power supply unit 91 and the 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 side to the first power supply unit 91 side, the ground fault is detected by the above-mentioned abnormality detection unit, and the control unit 33 switches the first switch 31 from the first allowable state to the first cutoff state. Thereby, the flow of current from the first connection point 71 side to the first power supply unit 91 side is blocked, and the power from the second power supply unit 92 is supplied to the load 93.

[0048] And after the power supply of the first power supply unit 91 fails, since power can be supplied from the power storage unit 34 to the load 93 via the third conductive path 83, the power supply to the load 93 can be maintained seamlessly. Specifically, after the 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 allowable state to the first cutoff state. Furthermore, the reverse current prevention unit 35 can prevent the current from flowing from the power storage unit 34 to the first switch 31 via the third conductive path 83 and the current from flowing from the power storage unit 34 to the second switch 32 via the third conductive path 83. Thereby, the power supply destination from the power storage unit 34 can be set to only the load 93.

[0049] 1-4. Examples of the Effects of the Power Supply Device 10 In the power supply device 10, when 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 and the first power supply unit 91 loses power, the first switch 31 can cut off the first conduction path 81. And after the first power supply unit 91 loses power, since power can be supplied from the power storage unit 34 to the load 93 via the third conduction path 83, the power supply to the load 93 can be maintained. Similarly, in the case where the second power supply unit 92 loses power, the second switch 32 can cut off the second conduction path 82, and the power supply from the power storage unit 34 to the load 93 can be maintained after the power loss. Moreover, the reverse current prevention unit 35 can prevent the flow of current from the power storage unit 34 to the first switch 31 via the third conduction path 83 and the flow of current from the power storage unit 34 to the second switch 32 via the third conduction path 83. Therefore, the power supply device 10 can realize a configuration capable of maintaining the power supply to the load 93.

[0050] In the power supply device 10, the reverse current prevention unit 35 is provided between the power storage unit 34 and the first connection point 71 in the third conduction path 83. Thereby, in the power supply device 10, by providing the reverse current prevention unit 35 in the third conduction path 83, a configuration for preventing the reverse flow from the power storage unit 34 to the first conduction path 81 and the second conduction path 82 can be realized. Therefore, the power supply device 10 can simplify the configuration as compared with the case where the reverse current prevention unit 35 is provided in both the first conduction path 81 and the second conduction path 82.

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

[0052] As shown in FIG. 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 houses a first switch 31, a second switch 32, a control unit 33, a power storage unit 34, a backflow prevention unit 35, and the third switch 236.

[0053] The third switch 236 is provided in series with the backflow prevention unit 35 between the first connection point 71 and the backflow prevention unit 35 in the third conductive path 83. 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 allowable state that allows the flow of bidirectional current through itself and a third cutoff state that blocks the flow of current from the first connection point 71 side to the backflow prevention unit 35 side. The third switch 236 includes, for example, a MOSFET. The third switch 236 enters the third allowable state when the MOSFET is in the ON state. The third switch 236 enters the third cutoff state when the MOSFET is in the OFF state. The third switch 236 is, for example, an IPD (Intelligent Power Device) incorporating a protection circuit or the like.

[0054] The control unit 33 transmits a control signal to the third switch 236 to control its operation. The third switch 236 may be configured, for example, as a pair of MOSFETs having parasitic diodes with opposite directions.

[0055] For example, consider a case where the power supply device 10 has its start condition satisfied, the first switch 31 is in the first allowable state, the second switch 32 is in the second allowable state, and power from the first power supply unit 91 or the second power supply unit 92 is being supplied to the load 93, and a ground fault or the like occurs in the load 93. Here, a ground fault in the load 93 can be detected by providing an abnormality detection unit with the same configuration as the above-mentioned abnormality detection unit in the third conductive path 83. 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 side to the load 93 side exceeds the threshold current. Also, for example, when the voltage of the third conductive path 83 becomes equal to or lower than the threshold voltage, it can be determined that a ground fault has occurred in the third conductive path 83.

[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 allowable state to the third cutoff state. As a result, the flow of current from the first connection point 71 side to the load 93 side is blocked. In this way, by blocking the third conductive path 83 with the third switch 236, 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 when a ground fault occurs in the load 93.

[0057] Also, when the configuration allows current to flow from the first electrical path 81A to the second electrical path 81B when the first switch 31 is in the first cutoff state, that is, when it is a MOSFET having a parasitic diode that allows the flow of current from the first electrical path 81A to the second electrical path 81B, setting the third switch 236 to the third cutoff state can prevent the flow of dark current from the first power supply unit 91 or the second power supply unit 92.

[0058] 3. Third Embodiment The power supply device 310 of the third embodiment is different from the first embodiment in that some configurations are 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 are omitted.

[0059] As shown in FIG. 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 houses 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 the fourth connection point 374 on 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 between the second connection point 372 and a resistor 337 (to be described later) on the fourth conductive path 384.

[0062] The resistor 337 is provided between the second connection point 372 and the fourth connection point 374 on the fourth conductive path 384. 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 backflow prevention unit 338 is provided between the second connection point 372 and the power storage unit 34 on the fourth conductive path 384. The second backflow prevention unit 338 prevents the flow of current from the third conductive path 83 to the power storage unit 34 via the second connection point 372. The second backflow prevention unit 338 is constituted by a rectifying diode (for example, an ideal diode) such as a PN junction diode. The anode of the second backflow prevention unit 338 is electrically connected to the fourth connection point 374. The cathode of the second backflow prevention unit 338 is electrically connected to the second connection point 372.

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

[0065] The fourth switch 339 is provided between the second connection point 372 and the load 93 in the third conductive path 83. 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 allowable state that allows a bidirectional current to flow therethrough and a fourth cutoff state that cuts off the current flowing 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 allowable state when the MOSFET is in the ON state. The fourth switch 339 enters the fourth cutoff state when the MOSFET is in the OFF state. The fourth switch 339 is, for example, an IPD (Intelligent Power Device) incorporating a protection circuit or the like.

[0066] The control unit 33 transmits a control signal to the fourth switch 339 to control its operation. The fourth switch 339 may be configured, for example, as a pair of MOSFETs having parasitic diodes with opposite directions.

[0067] In the power supply device 310, by shutting off the third conductive path 83 with the fourth switch 339, the flow of current 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 reverse current prevention unit 338, and the flow of current to the load 93 side via the reverse current prevention unit 35 can be prevented. In this way, by shutting off 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 when the load 93 is grounded.

[0068] <Other Embodiments> The present disclosure is not limited to the embodiments described by the above description and drawings. For example, the features of the above-described or later-described embodiments can be combined in any combination within a non-contradictory range. Also, any feature of the above-described or later-described embodiments can be omitted if it is not explicitly specified as essential. Furthermore, the above-described embodiments may be modified as follows.

[0069] In the first to third embodiments described above, the reverse current prevention unit 35 was provided in the third conductive path 83. In contrast, the reverse current prevention unit 35 may be provided in at least one of the first conductive path 81 and the second conductive path 82 in addition to or instead of the configuration provided in the third conductive path 83. When the reverse current prevention unit 35 is provided in the first conductive path 81, the anode of the reverse current 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 reverse current prevention unit 35 is provided in the second conductive path 82, the anode of the reverse current 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 above-described first to third embodiments, the first power supply unit 91 was configured as a battery. In contrast, the first power supply unit 91 may include a battery and a voltage conversion unit. The voltage conversion unit is constituted by, for example, a DC-DC converter. The voltage conversion unit boosts or steps down the voltage input from the battery side and outputs it to the first conductive path 81 side. Further, the voltage conversion unit performs a conversion operation of boosting or stepping down the voltage input from the first conductive path 81 side and outputting it to the battery side.

[0071] In the above-described first to third embodiments, the first switch 31 was configured to allow current to flow from the first electric path 81A to the second electric path 81B when in the first cutoff state. In contrast, the first switch 31 may be configured to also cut off the flow of current from the second electric path 81B to the first electric path 81A when in the first cutoff state. For example, the first switch 31 may be configured as a pair of MOSFETs arranged in series having parasitic diodes with opposite directions (butting state).

[0072] In the above-described first to third embodiments, the second switch 32 was configured to allow current to flow from the third electric path 82A to the fourth electric path 82B when in the second cutoff state. In contrast, the second switch 32 may be configured to also cut off the flow of current from the fourth electric path 82B to the third electric 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 with opposite directions.

[0073] In the above-described first to third embodiments, the first switch 31 and the second switch 32 were configured as MOSFETs. In contrast, the first switch 31 and the second switch 32 may be configured as mechanical switches.

[0074] In the above-described first to third embodiments, the backflow prevention unit 35 was configured as a diode. In contrast, 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 above-described first to third embodiments, a conductive path branched from the first conductive path 81 or the second conductive path 82 may be provided to supply power to a load different from the load 93.

[0076] In the above-described third embodiment, one end of the fourth conductive path 384 was connected to the second conductive path 82. In contrast, one end of the fourth conductive path 384 may be connected to the first conductive path 81.

Explanation of Reference Numerals

[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: Conductive path 35: Backflow prevention unit 71: First connection point (connection point) 72: Second connection point 81: First conductive path 81A: First electrical path 81B: Second electrical path 82: Second conductive path 82A: Third electrical path 82B: Fourth electrical path 83: Third conductive path 91: First power supply unit 92: Second power supply unit 93: Load 100: Vehicle-mounted system 200: Vehicle-mounted system 210: Power supply device 236: Third switch 300: Vehicle-mounted system 310: Power supply device 334A: Conductive path 337: Resistor 338: Second reverse current prevention unit 339: Fourth switch 372: Second connection point 373: Third connection point 374: Fourth connection point 384: Fourth conductive path

Claims

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

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

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

4. The power supply device according to claim 1 or claim 2, further comprising a case member that houses the first switch, the second switch, the power storage unit, and the backflow prevention unit, and is configured as a junction box.

5. a fourth conductive path electrically connected to both ends of the backflow prevention unit, a resistor provided in the fourth conductive path, Comprising, The fourth conductive path is connected to the third conductive path at a second connection point, The power storage unit is electrically connected between the second connection point and the resistor in the fourth conductive path, The power supply device according to claim 1 or claim 2, further comprising a second backflow prevention unit provided between the second connection point and the power storage unit in the fourth conductive path to prevent the flow of current from the third conductive path to the power storage unit via the second connection point.

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

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