Onboard power supply device

Abstract

An onboard power supply device (20) is included in an onboard system (1). The onboard system (1) comprises: a power line (12) for supplying power from a battery (10) to a load (11); a capacitor (13) electrically connected to the power line (12); and a main relay (for example, a positive electrode-side main relay (14)) provided between the battery (10) and the capacitor (13) on the power line (12). The onboard power supply device (20) has a pre-charge circuit (21) provided in parallel with the main relay. The pre-charge circuit (21) has a configuration in which a pre-charge resistor (22), a pre-charge relay (23), and a semiconductor switching element (for example, a thyristor (24)) are connected in series.

Description

Automotive power supply unit

[0001] The present disclosure relates to an in-vehicle power supply device.

[0002] Patent Document 1 discloses a secondary battery system having a precharge circuit. The precharge circuit is provided in parallel with a main relay. The precharge circuit is composed of a precharge switch and a resistor. A switch control circuit switches the precharge switch to an ON state, and switches the main relay to an ON state when the load circuit voltage reaches a preset voltage.

[0003] Japanese Patent Application Laid-Open No. 2020-174462

[0004] In the configuration of Patent Document 1, the current suppression effect of the resistor reduces damage to the precharge switch when the precharge switch is switched on. However, even small damage to the precharge switch accumulates as the switch is repeatedly turned on and off. For this reason, there is a need to further reduce damage to the precharge switch.

[0005] An object of the present disclosure is to provide a technique that can further reduce damage to precharge relays.

[0006] The automotive power supply device disclosed herein is an automotive power supply device included in an automotive system having a power path that supplies power from a battery to a load, a capacitor electrically connected to the power path, and a main relay that is provided between the battery and the capacitor in the power path, and has a precharge circuit that is provided in parallel with the main relay, and the precharge circuit is configured by connecting a precharge resistor, a precharge relay, and a semiconductor switching element in series.

[0007] The technology according to the present disclosure can further reduce damage to the precharge relay.

[0008] Fig. 1 is a configuration diagram of an in-vehicle system including an in-vehicle power supply device of a first embodiment. Fig. 2 is a timing chart showing the operation timing of the positive main relay, negative main relay, pre-charge relay, and thyristor in the first embodiment. Fig. 3 is a configuration diagram of an in-vehicle system including an in-vehicle power supply device of a second embodiment. Fig. 4 is a configuration diagram of an in-vehicle system including an in-vehicle power supply device of a third embodiment. Fig. 5 is a timing chart showing the operation timing of the positive main relay, negative main relay, pre-charge relay, and MOSFET in the third embodiment.

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

[0010] [1] An in-vehicle power supply device included in an in-vehicle system having a power path that supplies power from a battery to a load, a capacitor electrically connected to the power path, and a main relay provided in the power path between the battery and the capacitor, the in-vehicle power supply device having a precharge circuit provided in parallel with the main relay, the precharge circuit having a configuration in which a precharge resistor, a precharge relay, and a semiconductor switching element are connected in series.

[0011] The precharge circuit of the above-described in-vehicle power supply device has a configuration in which a precharge resistor, a precharge relay, and a semiconductor switching element are connected in series. With this configuration, when the precharge circuit precharges the capacitor, the semiconductor switching element is switched on after the precharge relay is switched on, thereby reducing damage to the precharge relay.

[0012] [2] The in-vehicle power supply device according to [1], further comprising a control unit that controls the precharge relay, wherein the control unit switches the precharge relay to an ON state when a precharge start condition is met, and after the precharge relay is switched to the ON state, the semiconductor switching element is switched to an ON state.

[0013] In the above-described in-vehicle power supply device, when the precharge start condition is met, the control unit switches the precharge relay to the on state, and then the semiconductor switching element switches to the on state, thereby reducing damage to the precharge relay.

[0014] [3] The in-vehicle power supply device according to [1] or [2], further comprising: the main relay; and an electrical junction box that houses the main relay, wherein the precharge circuit is housed in the electrical junction box.

[0015] The above-described on-board power supply device can be easily made smaller in size because the main relay and the precharge circuit are housed together in the electrical junction box.

[0016] [4] The in-vehicle power supply device according to any one of [1] to [3], wherein the semiconductor switching element is provided closer to the load than the precharge relay.

[0017] With this configuration, when the precharge circuit is in the off state, the battery voltage is not applied to the semiconductor switching element, so that a semiconductor switching element with a low withstand voltage can be used.

[0018] [5] The automotive power supply device according to [4], wherein the semiconductor switching element includes an input terminal and switches to an ON state when a drive voltage is input to the input terminal, and further includes a drive circuit that connects a conduction path between the precharge relay and the semiconductor switching element to the input terminal, and the drive circuit generates the drive voltage from a voltage applied to the conduction path when the precharge relay switches to the ON state and inputs the drive voltage to the input terminal.

[0019] In the above-described automotive power supply device, in response to the precharge relay being switched to the ON state, the drive circuit generates a drive voltage and inputs it to the input terminal. As a result, the semiconductor switching element is switched to the ON state. In other words, in the above-described automotive power supply device, simply by switching the precharge relay to the ON state, the drive circuit can automatically switch the semiconductor switching element to the ON state thereafter. Furthermore, in the above-described automotive power supply device, the semiconductor switching element is not switched to the ON state until the precharge relay is switched to the ON state, so that it is possible to more reliably prevent the semiconductor switching element from switching to the ON state before the precharge relay is switched to the ON state.

[0020] [6] The in-vehicle power supply device according to [5], wherein the semiconductor switching element is a thyristor.

[0021] In the above-described automotive power supply device, when the precharge relay is switched to the off state after the precharge relay and the thyristor are switched to the on state, an off signal is input to the gate of the thyristor, and the current flowing to the anode is cut off. As a result, the thyristor is switched to the off state. In other words, in the above-described automotive power supply device, simply by switching the precharge relay to the off state, the semiconductor switching element can be automatically switched to the off state thereafter.

[0022] [7] The in-vehicle power supply device according to [5] or [6], wherein the drive circuit is constituted by a resistor portion, one end of the resistor portion is electrically connected to the conductive path, and the other end of the resistor portion is electrically connected to the input terminal.

[0023] According to this configuration, the drive circuit can be realized with a simple configuration.

[0024] [8] The control unit includes a signal output unit that outputs an on signal when the precharge start condition is met, and a delay circuit that delays the on signal output from the signal output unit and inputs it to the semiconductor switching element, and after the precharge relay is switched to the on state by the on signal output from the signal output unit, the semiconductor switching element is switched to the on state by the on signal input from the delay circuit. The automotive power supply device described in any of [2] to [4].

[0025] According to this configuration, it is possible to realize a configuration in which the semiconductor switching element is switched to the ON state after the precharge relay is switched to the ON state using the delay circuit.

[0026] [9] The automotive power supply device according to any one of [2] to [4], wherein the control unit is capable of controlling the semiconductor switching element, and when the precharge start condition is satisfied, switches the precharge relay to an ON state and then switches the semiconductor switching element to an ON state.

[0027] The above-described in-vehicle power supply device can switch the precharge relay and the semiconductor switching element to the ON state in sequence by the control unit.

[0028]

[10] The in-vehicle power supply device according to [9], wherein when a precharge completion condition is met, the control unit switches the semiconductor switching element to an OFF state, and then switches the precharge relay to an OFF state.

[0029] When the precharge completion condition is met, the control unit switches the semiconductor switching element to the OFF state and then switches the precharge relay to the OFF state. Therefore, the above-mentioned automotive power supply device can reduce damage to the precharge relay not only when the precharge relay is switched to the ON state but also when it is switched to the OFF state.

[0030] [Details of the embodiment of the present disclosure] 1. First embodiment 1-1. Configuration of in-vehicle system 1 The in-vehicle system 1 of the first embodiment shown in Fig. 1 is a system mounted on a vehicle. The in-vehicle system 1 includes a battery 10, a load 11, a power path 12 that supplies power from the battery 10 to the load 11, a capacitor 13, a positive main relay 14, and a negative main relay 15.

[0031] The power path 12 has a positive power line 12A and a negative power line 12B. One end of the positive power line 12A is electrically connected to the positive terminal of the battery 10. The other end of the positive power line 12A is electrically connected to one end of the load 11. One end of the negative power line 12B is electrically connected to the negative terminal of the battery 10. The other end of the negative power line 12B is electrically connected to the other end of the load 11.

[0032] The capacitor 13 is electrically connected to the power path 12. One end of the capacitor 13 is electrically connected to the positive power line 12A. The other end of the capacitor 13 is electrically connected to the negative power line 12B.

[0033] The positive main relay 14 is an example of a main relay. The positive main relay 14 is configured by a mechanical switch having contacts. The positive main relay 14 is provided between the battery 10 and the capacitor 13 on the positive power line 12A.

[0034] The negative main relay 15 is configured by a mechanical switch having contacts and is provided between the battery 10 and the capacitor 13 on the negative power line 12B.

[0035] The in-vehicle system 1 includes an in-vehicle power supply device 20. The in-vehicle power supply device 20 has a precharge circuit 21.

[0036] The precharge circuit 21 is provided in parallel with the positive main relay 14. One end of the precharge circuit 21 is electrically connected to a portion of the positive power line 12A between the battery 10 and the positive main relay 14. The other end of the precharge circuit 21 is electrically connected to a portion of the positive power line 12A between the positive main relay 14 and the capacitor 13.

[0037] The precharge circuit 21 is configured by connecting a precharge resistor 22, a precharge relay 23, and a thyristor 24 in series.

[0038] The precharge relay 23 is configured by a mechanical switch having contacts. The thyristor 24 corresponds to an example of a semiconductor switching element. The precharge relay 23 and the thyristor 24 are provided closer to the load 11 than the precharge resistor 22. The thyristor 24 is provided closer to the load 11 than the precharge relay 23. With this configuration, when the precharge circuit 21 is in the off state, the voltage of the battery 10 is not applied to the thyristor 24. Therefore, a thyristor 24 with a low withstand voltage can be used.

[0039] The gate 24A of the thyristor 24 corresponds to an example of an input terminal. The thyristor 24 is turned on when a drive voltage is input to the gate 24A and a current flows from the anode 24B to the cathode 24C.

[0040] The in-vehicle power supply device 20 has a drive circuit 30. The drive circuit 30 connects a conductive path 25 between the pre-charge relay 23 and the anode 24B of the thyristor 24 to the gate 24A of the thyristor 24. The drive circuit 30 generates a drive voltage from the voltage applied to the conductive path 25 when the pre-charge relay 23 is switched to the on state, and inputs the drive voltage to the gate 24A. The drive circuit 30 is composed of a resistor unit 31. One end of the resistor unit 31 is electrically connected to the conductive path 25. The other end of the resistor unit 31 is electrically connected to the gate 24A. This configuration allows the drive circuit 30 to be implemented with a simple structure.

[0041] The in-vehicle power supply device 20 has a control unit 40. The control unit 40 is configured to include, for example, a microcomputer. The control unit 40 controls the positive main relay 14, the negative main relay 15, and the precharge relay 23.

[0042] The in-vehicle power supply device 20 has the positive main relay 14 and negative main relay 15 described above. The in-vehicle power supply device 20 also has an electrical junction box 41. The electrical junction box 41 is provided between the battery 10 and the load 11 and is electrically connected to the battery 10 and the load 11. The electrical junction box 41 houses the positive main relay 14, the negative main relay 15, the pre-charge circuit 21, and the control unit 40. With this configuration, the positive main relay 14, the negative main relay 15, the pre-charge circuit 21, and the control unit 40 are housed together in the electrical junction box 41, which facilitates miniaturization.

[0043] 1-2. Operation of the In-Vehicle System 1 The following describes the operation of switching the positive main relay 14 and the negative main relay 15 from an OFF state to an ON state. In the initial state, the positive main relay 14, the negative main relay 15, the precharge relay 23, and the thyristor 24 are in an OFF state. In this state, the control unit 40 determines whether a precharge start condition is met. The precharge start condition may be, for example, that the start switch of the vehicle has been switched to an ON state, or may be another condition. The start switch may be, for example, an ignition switch or a power switch.

[0044] 2, when the control unit 40 determines that the precharge start condition is met, it switches the negative main relay 15 to the ON state (timing T1), and then outputs an ON signal to the precharge relay 23 (timing T2). When the ON signal is input, the precharge relay 23 switches to the ON state (timing T3).

[0045] When the precharge relay 23 switches to the ON state, the voltage of the battery 10 is applied to the conductive path 25 between the precharge relay 23 and the thyristor 24. The drive circuit 30 generates a drive voltage from the voltage applied to the conductive path 25 and inputs it to the gate 24A (timing T4). As a result, current flows from the anode 24B to the cathode 24C of the thyristor 24, turning the thyristor 24 ON (timing T5). This causes current to be supplied from the battery 10 to the capacitor 13 via the precharge circuit 21, and charging of the capacitor 13 begins. The voltage of the capacitor 13 gradually increases over time.

[0046] The control unit 40 repeatedly determines whether a precharge completion condition is met after starting to output an ON signal to the precharge relay 23. The precharge completion condition may be, for example, that the voltage of the capacitor 13 is equal to or higher than a threshold voltage, that the difference between the voltage of the capacitor 13 and the voltage of the battery 10 is equal to or lower than a threshold, that the potential difference across the positive main relay 14 is equal to or lower than a threshold, or that the current flowing through the precharge circuit 21 is equal to or lower than a threshold current.

[0047] When the control unit 40 determines that the precharge completion condition is met, it stops outputting the ON signal to the precharge relay 23 and outputs an OFF signal to the precharge relay 23 (timing T6). When the OFF signal is input, the precharge relay 23 switches to the OFF state (timing T7).

[0048] When the precharge relay 23 switches to the ON state, the voltage of the battery 10 is no longer applied to the conductive path 25. As a result, the drive circuit 30 inputs an OFF signal to the gate 24A (timing T8). The current supplied to the anode 24B of the thyristor 24 is also cut off by the precharge relay 23. As a result, the thyristor 24 switches to the OFF state (timing T9).

[0049] The control unit 40 switches the positive main relay 14 to the ON state (timing T10) at the timing after the thyristor 24 has switched to the OFF state, thereby turning the positive main relay 14 and the negative main relay 15 to the ON state.

[0050] 1-3. Effects of the In-Vehicle Power Supply Device 20 In the in-vehicle power supply device 20, when the precharge start condition is met, the control unit 40 switches the precharge relay 23 to the on state, and then the thyristor 24 switches to the on state. Therefore, the in-vehicle power supply device 20 can reduce damage to the precharge relay 23.

[0051] In the in-vehicle power supply device 20, in response to the pre-charge relay 23 being switched to the ON state, the drive circuit 30 generates a drive voltage and inputs it to the gate 24A. As a result, the thyristor 24 is switched to the ON state. In other words, in the in-vehicle power supply device 20, simply by switching the pre-charge relay 23 to the ON state, the drive circuit 30 can automatically perform the operation of switching the thyristor 24 to the ON state thereafter. Furthermore, in the in-vehicle power supply device 20, the thyristor 24 is not switched to the ON state until the pre-charge relay 23 is turned ON, so that it is possible to more reliably prevent the thyristor 24 from switching to the ON state before the pre-charge relay 23 is turned ON.

[0052] In the in-vehicle power supply device 20, when the pre-charge relay 23 is switched to the off state after the pre-charge relay 23 and the thyristor 24 are switched to the on state, an off signal is input to the gate 24A of the thyristor 24, and the current flowing into the anode 24B is cut off. As a result, the thyristor 24 is switched to the off state. In other words, the in-vehicle power supply device 20 can automatically switch the thyristor 24 to the off state by simply switching the pre-charge relay 23 to the off state.

[0053] 2. Second Embodiment In the second embodiment, an example will be described in which the control for sequentially switching on the precharge relay and the semiconductor switching element is achieved using a delay circuit. Note that 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.

[0054] 3 is a system mounted on a vehicle, and includes a battery 10, a load 11, a power path 12, a capacitor 13, a positive main relay 14, and a negative main relay 15.

[0055] The in-vehicle system 201 includes an in-vehicle power supply device 220. The in-vehicle power supply device 220 has a positive main relay 14, a negative main relay 15, a precharge circuit 221, a control unit 240, and an electrical junction box 41.

[0056] The precharge circuit 221 is provided in parallel with the positive main relay 14. The precharge circuit 221 has a configuration in which a precharge resistor 22, a precharge relay 23, and a MOSFET 224 are connected in series. The precharge relay 23 and the MOSFET 224 are provided on the load 11 side of the precharge resistor 22. The MOSFET 224 is provided on the load 11 side of the precharge relay 23.

[0057] The control unit 240 controls the positive main relay 14, the negative main relay 15, the precharge relay 23, and the MOSFET 224 so that the same operations as those shown in the timing chart of Fig. 2 described in the first embodiment are performed. Specifically, the operations are as follows.

[0058] The control unit 240 includes a signal output unit 240A and a delay circuit 240B. The signal output unit 240A includes, for example, a microcomputer. The signal output unit 240A controls the positive main relay 14, the negative main relay 15, and the precharge relay 23.

[0059] When the signal output unit 240A determines that the precharge start condition is met, it switches the negative side main relay 15 to the ON state and then outputs an ON signal to the precharge relay 23 and the delay circuit 240B. When the ON signal is input, the precharge relay 23 switches to the ON state. The delay circuit 240B delays the ON signal output from the signal output unit 240A and inputs it to the MOSFET 224. The delay time provided by the delay circuit 240B is set to a time longer than the time it takes for the precharge relay 23 to switch to the ON state after receiving the ON signal.

[0060] When an ON signal is input to the gate of the MOSFET 224, the MOSFET 224 switches to the ON state. This causes current to be supplied from the battery 10 to the capacitor 13 via the precharge circuit 221, and charging of the capacitor 13 begins. The voltage of the capacitor 13 gradually increases over time.

[0061] The signal output unit 240A repeatedly determines whether or not the precharge completion condition is met after starting to output an ON signal to the MOSFET 224. If it determines that the precharge completion condition is met, the signal output unit 240A stops outputting the ON signal to the precharge relay 23 and the delay circuit 240B, and outputs an OFF signal to the precharge relay 23 and the delay circuit 240B.

[0062] When an OFF signal is input to the precharge relay 23, the precharge relay 23 switches to the OFF state. The delay circuit 240B delays the OFF signal output from the signal output unit 240A and inputs it to the MOSFET 224. The delay time provided by the delay circuit 240B is set to a time longer than the time it takes for the precharge relay 23 to switch to the OFF state after receiving the OFF signal. When an OFF signal is input to the gate of the MOSFET 224, the MOSFET 224 switches to the OFF state.

[0063] The control unit 240 outputs an OFF signal to the MOSFET 224, and then outputs an ON signal to the positive main relay 14 to switch the positive main relay 14 to the ON state. As a result, the positive main relay 14 and the negative main relay 15 are turned ON.

[0064] According to this configuration, the in-vehicle power supply device 220 can be configured to switch the MOSFET 224 to the ON state after switching the precharge relay 23 to the ON state using the delay circuit 240B.

[0065] 3. Third Embodiment In the third embodiment, an example in which a precharge relay and a semiconductor switching element are controlled separately will be described. Note that in the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0066] 4 is a system mounted on a vehicle, and includes a battery 10, a load 11, a power path 12, a capacitor 13, a positive main relay 14, and a negative main relay 15.

[0067] The in-vehicle system 301 includes an in-vehicle power supply device 320. The in-vehicle power supply device 320 has a positive main relay 14, a negative main relay 15, a precharge circuit 321, a control unit 340, and an electrical junction box 41.

[0068] The precharge circuit 321 is provided in parallel with the positive main relay 14. The precharge circuit 321 has a configuration in which a precharge resistor 22, a precharge relay 23, and a MOSFET 324 are connected in series. The precharge relay 23 and the MOSFET 324 are provided on the load 11 side of the precharge resistor 22. The MOSFET 324 is provided on the load 11 side of the precharge relay 23.

[0069] The control unit 340 controls the positive main relay 14, the negative main relay 15, the precharge relay 23, and the MOSFET 324. The control unit 340 includes, for example, a microcomputer.

[0070] 5, when it is determined that the precharge start condition is met, the control unit 340 switches the negative main relay 15 to the ON state (timing T11), and then outputs an ON signal to the precharge relay 23 (timing T12). When the ON signal is input, the precharge relay 23 switches to the ON state (timing T13).

[0071] The control unit 340 outputs an ON signal to the MOSFET 324 (timing T14) after a predetermined time has elapsed since starting to output an ON signal to the precharge relay 23. The predetermined time is set to be longer than the time it takes for the precharge relay 23 to switch to the ON state after receiving the ON signal. When the ON signal is input, the MOSFET 324 switches to the ON state (timing T15).

[0072] This causes current to be supplied from the battery 10 to the capacitor 13 via the precharge circuit 321, starting to charge the capacitor 13. The voltage of the capacitor 13 gradually increases over time.

[0073] After starting to output an ON signal to the MOSFET 324, the control unit 340 repeatedly determines whether the precharge completion condition is met. If the control unit 340 determines that the precharge completion condition is met, it outputs an OFF signal to the MOSFET 324 (timing T16). When the OFF signal is input, the MOSFET 324 switches to the OFF state (timing T17).

[0074] After starting to output an OFF signal to the MOSFET 324, the control unit 340 outputs an OFF signal to the precharge relay 23 (timing T18). When the OFF signal is input, the precharge relay 23 switches to the OFF state (timing T19). Note that the control unit 340 may output an OFF signal to the precharge relay 23 at the same time as starting to output an OFF signal to the MOSFET 324. A semiconductor switching element such as the MOSFET 324 operates to turn OFF faster than a mechanical precharge relay 23. For this reason, even if the output of OFF signals starts at the same time, the MOSFET 324 switches to the OFF state before the precharge relay 23.

[0075] The control unit 340 switches the positive main relay 14 to the ON state (timing T20) at the timing after the precharge relay 23 has been switched to the OFF state, thereby turning the positive main relay 14 and the negative main relay 15 to the ON state.

[0076] As described above, the in-vehicle power supply device 320 can switch the precharge relay 23 and the MOSFET 324 to the on state in sequence by the control unit 340.

[0077] Furthermore, when the precharge completion condition is met, the control unit 340 switches the MOSFET 324 to the OFF state and then switches the precharge relay 23 to the OFF state. Therefore, the in-vehicle power supply device 320 can reduce damage to the precharge relay 23 not only when the precharge relay 23 is switched to the ON state, but also when the precharge relay 23 is switched to the OFF state.

[0078] <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.

[0079] In the above embodiments, the precharge circuit is provided in parallel with the positive main relay 14 , but the precharge circuit may be provided in parallel with the negative main relay 15 .

[0080] In each of the above embodiments, the precharge relay and the semiconductor switching element are configured to be provided on the load side of the precharge resistor, but at least one of the precharge relay and the semiconductor switching element may be configured to be provided on the battery side of the precharge resistor.

[0081] In each of the above embodiments, the semiconductor switching element is provided on the load side of the precharge relay, but the semiconductor switching element may be provided on the battery side of the precharge relay.

[0082] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims.

[0083] DESCRIPTION OF SYMBOLS 1...In-vehicle system 10...Battery 11...Load 12...Power path 12A...Positive power line 12B...Negative power line 13...Capacitor 14...Positive main relay (main relay) 15...Negative main relay 20...In-vehicle power supply device 21...Precharge circuit 22...Precharge resistor 23...Precharge relay 24...Thyristor (semiconductor switching element) 24A...Gate (input terminal) 24B...Anode 24C...Cathode 25...Conductive path 30...Drive circuit 31...Resistance section 40...Control section 41...Electrical connection box 201...In-vehicle system 220...In-vehicle power supply device 221...Precharge circuit 224...MOSFET (semiconductor switching element) 240...Control section 240A...Signal output section 240B...Delay circuit 301...In-vehicle system 320...In-vehicle power supply device 321... Precharge circuit 324... MOSFET (semiconductor switching element) 340... Control unit

Claims

1. An in-vehicle power supply device included in an in-vehicle system having a power path that supplies power from a battery to a load, a capacitor electrically connected to the power path, and a main relay provided in the power path between the battery and the capacitor, the in-vehicle power supply device having a precharge circuit provided in parallel with the main relay, the precharge circuit having a configuration in which a precharge resistor, a precharge relay, and a semiconductor switching element are connected in series.

2. The automotive power supply device according to claim 1, further comprising a control unit that controls the precharge relay, wherein the control unit switches the precharge relay to an ON state when a precharge start condition is met, and after the precharge relay has switched to the ON state, the semiconductor switching element is switched to the ON state.

3. An on-board power supply device according to claim 1 or 2, comprising: the main relay; and an electrical junction box that houses the main relay, wherein the precharge circuit is housed within the electrical junction box.

4. An in-vehicle power supply device according to claim 1 or 2, wherein the semiconductor switching element is provided closer to the load than the precharge relay.

5. The automotive power supply device according to claim 4, wherein the semiconductor switching element includes an input terminal and switches to an ON state when a drive voltage is input to the input terminal, and further includes a drive circuit that connects a conductive path between the precharge relay and the semiconductor switching element to the input terminal, and the drive circuit generates the drive voltage from the voltage applied to the conductive path when the precharge relay switches to the ON state and inputs the drive voltage to the input terminal.

6. The in-vehicle power supply device according to claim 5, wherein the semiconductor switching element is a thyristor.

7. The automotive power supply device according to claim 5, wherein the drive circuit is constituted by a resistor portion, one end of the resistor portion is electrically connected to the conductive path, and the other end of the resistor portion is electrically connected to the input terminal.

8. The automotive power supply device according to claim 2, wherein the control unit includes a signal output unit that outputs an ON signal when the precharge start condition is met, and a delay circuit that delays the ON signal output from the signal output unit and inputs it to the semiconductor switching element, and after the precharge relay is switched to the ON state by the ON signal output from the signal output unit, the semiconductor switching element is switched to the ON state by the ON signal input from the delay circuit.

9. The automotive power supply device according to claim 2, wherein the control unit is capable of controlling the semiconductor switching element, and when the precharge start condition is met, switches the precharge relay to an ON state and then switches the semiconductor switching element to an ON state.

10. The automotive power supply device according to claim 9, wherein, when a precharge completion condition is met, the control unit switches the semiconductor switching element to the OFF state, and then switches the precharge relay to the OFF state.

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