On-vehicle power supply device

Abstract

An on-vehicle power supply device (10) is used for an on-vehicle power supply system (100). The on-vehicle power supply system (100) comprises a battery (20), an electric power path (21) to which electric power based on the battery (20) is to be supplied, and a capacitor (22) which is connected to the electric power path (21). The on-vehicle power supply device (10) comprises a mechanical system main relay (first SMR (51)), a parallel circuit (53), and a second relay (56). The system main relay (first SMR (51)) is provided to the electric power path (21) on the battery (20) side with respect to the capacitor (22). The parallel circuit (53) has a configuration in which a first relay (54) and a resistor part (55) are connected in series, and is provided in parallel to the system main relay (first SMR (51)). The second relay (56) is provided in parallel to the resistor part (55).

Description

Automotive power supply

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

[0002] Patent Document 1 discloses a power supply device for a vehicle. This power supply device includes a contactor and a precharge circuit. The contactor switches on and off the power supply from the driving battery to the load. The precharge circuit is connected in parallel with the contactor and precharges a capacitor. The precharge circuit includes a precharge resistor that limits the precharge current and a precharge switch connected in series with the precharge resistor.

[0003] JP 2009-89535 A

[0004] With this type of technology, when precharging the capacitor, it takes time for the capacitor voltage to reach the target voltage because the current is limited by the precharge resistor, but in some situations it may be desirable to complete the precharging of the capacitor more quickly.

[0005] The present disclosure aims to provide a technology that enables precharging via a resistor portion and enables precharging of a capacitor to be completed more quickly while minimizing damage to a system main relay.

[0006] The automotive power supply device disclosed herein is an automotive power supply device used in an automotive power supply system including a battery, a power path to which power based on the battery is supplied, and a capacitor connected to the power path, and includes: a mechanical system main relay provided in the power path on the battery side of the capacitor; a parallel circuit configured by connecting a first relay and a resistor unit in series and provided in parallel to the system main relay; and a second relay provided in parallel to the resistor unit.

[0007] The technology disclosed herein allows precharging via a resistor portion, and can complete precharging of the capacitor more quickly while minimizing damage to the system main relay.

[0008] Fig. 1 is a block diagram of an in-vehicle power supply system including an in-vehicle power supply device according to a first embodiment. Fig. 2 is a flowchart showing the flow of processing performed by the in-vehicle power supply device according to the first embodiment. Fig. 3 is an explanatory diagram illustrating the change in capacitor voltage over time.

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

[0010] [1] An on-board power supply device used in an on-board power supply system including a battery, a power path to which power based on the battery is supplied, and a capacitor connected to the power path, the on-board power supply device comprising: a mechanical system main relay provided in the power path on the battery side of the capacitor; a parallel circuit configured by connecting a first relay and a resistor unit in series and provided in parallel to the system main relay; and a second relay provided in parallel to the resistor unit.

[0011] The above-mentioned automotive power supply device can precharge the capacitor via the resistor unit when the system main relay and the second relay are in an OFF state and the first relay is in an ON state. Furthermore, the above-mentioned automotive power supply device can precharge the capacitor more quickly by bypassing the resistor unit when the system main relay is in an OFF state and the first relay and the second relay are in an ON state. Therefore, the above-mentioned automotive power supply device is capable of precharging via the resistor unit and can complete precharging of the capacitor more quickly while suppressing damage to the system main relay.

[0012] [2] The automotive power supply device according to [1], further comprising a control unit that controls the system main relay, the first relay, and the second relay, wherein the control unit: when a start condition for starting charging / discharging of the battery is satisfied, executes a first control that controls the system main relay and the second relay to an off state and controls the first relay to an on state; when a first switching condition is satisfied while the first control is being executed, executes a second control that controls the system main relay to an off state and controls the first relay and the second relay to an on state; and when a second switching condition is satisfied while the second control is being executed, executes a third control that controls the first relay and the second relay to an off state and controls the system main relay to an on state.

[0013] The above-mentioned automotive power supply device can switch to the second control mode after increasing the capacitor voltage to a certain level under the first control mode, thereby switching to a more rapid precharge mode while avoiding an inrush current from flowing through the first relay, thereby enabling the above-mentioned automotive power supply device to more quickly complete the precharge of the capacitor while minimizing damage to the system main relay.

[0014] [3] The in-vehicle power supply device according to [2], wherein the second relay is a semiconductor relay.

[0015] In the above-described in-vehicle power supply device, the second relay is a contactless semiconductor relay, so that it is possible to avoid damage to the second relay when switching from the first control to the second control.

[0016] [4] The in-vehicle power supply device according to [2] or [3], wherein the first switching condition is that the potential difference across the system main relay or the value of the current flowing through the parallel circuit is equal to or less than a threshold value.

[0017] The above-mentioned automotive power supply device switches to the second control mode after the potential difference across the system main relay or the value of the current flowing through the parallel circuit is reduced to or below a threshold value. This allows the above-mentioned automotive power supply device to accurately determine the upper limit of the current flowing through the second relay in the second control mode. Therefore, the above-mentioned automotive power supply device can easily use components with a rated current suitable for the second relay as components of the second relay.

[0018] [5] The in-vehicle power supply device according to [2] or [3], wherein the first switching condition is that a first time has elapsed since the start of the first control.

[0019] The automotive power supply device switches to the second control after a first time has elapsed since the start of the first control. That is, the automotive power supply device increases the capacitor voltage to a certain degree using the first control before switching to the second control. This allows the automotive power supply device to set, with a certain degree of accuracy, the upper limit of the current flowing through the second relay under the second control using a simple configuration. Therefore, the automotive power supply device can easily use components with a rated current suitable for the second relay as components of the second relay.

[0020] [6] The in-vehicle power supply device according to [5], wherein the second switching condition is that a second time period shorter than the first time period has elapsed since the start of the second control.

[0021] In the above-described in-vehicle power supply device, since it is easy to secure a long first time period, it is easy to increase the voltage of the capacitor when switching to the second control, and therefore it is easy to use a component with a low rated current as a component of the second relay in the above-described in-vehicle power supply device.

[0022] [7] The in-vehicle power supply device according to [2] or [3], wherein the first switching condition is that the voltage of the capacitor is equal to or greater than a threshold voltage.

[0023] The above-mentioned automotive power supply device switches to the second control mode after the capacitor voltage reaches or exceeds the threshold voltage. In other words, the above-mentioned automotive power supply device switches to the second control mode after the difference between the battery voltage and the capacitor voltage has become small to a certain extent. This allows the above-mentioned automotive power supply device to set, with a certain degree of accuracy, the upper limit of the current flowing through the second relay in the second control mode. Therefore, the above-mentioned automotive power supply device makes it easy to use components with a rated current suitable for the second relay as components of the second relay.

[0024] <First Embodiment> 1. Configuration of an In-Vehicle Power Supply System 100 Fig. 1 shows an in-vehicle power supply system 100 equipped with an in-vehicle power supply device 10. The vehicle in which the in-vehicle power supply system 100 is installed may be an electric vehicle, a fuel cell vehicle (FCV), or a hybrid vehicle. In addition to the in-vehicle power supply device 10, the in-vehicle power supply system 100 also includes a battery 20, a power path 21, and a capacitor 22.

[0025] The battery 20 may be a lithium ion battery, a lead battery, or any other battery.

[0026] The power path 21 is an electrical path through which power is supplied from the battery 20. The power path 21 has a positive power line 30 and a negative power line 31. A positive terminal of the battery 20 is electrically connected to the positive power line 30. A negative terminal of the battery 20 is electrically connected to the negative power line 31. The negative power line 31 is electrically connected to ground. The output voltage of the battery 20 is applied to the power path 21 (more specifically, the positive power line 30). In this specification, voltage refers to a potential difference with respect to the ground potential and a potential difference with respect to the negative power line 31.

[0027] The capacitor 22 is electrically connected to the power path 21. The capacitor 22 is provided between the positive power line 30 and the negative power line 31. One end of the capacitor 22 is electrically connected to the positive power line 30. The other end of the capacitor 22 is electrically connected to the negative power line 31. Power based on the battery 20 is supplied to the capacitor 22 via the power path 21. The capacitor 22 smoothes the voltage based on the battery 20.

[0028] In this embodiment, the capacitor 22 is configured as part of a drive unit 40 provided in the in-vehicle power supply system 100. In addition to the capacitor 22, the drive unit 40 includes an inverter 41 and a motor 42. The capacitor 22 is provided closer to the battery 20 than the inverter 41. The capacitor 22 smoothes the voltage based on the battery 20 and supplies it to the inverter 41. The inverter 41 is electrically connected to the power path 21. The inverter 41 generates an AC voltage (e.g., three-phase AC) from a DC voltage based on the voltage supplied from the battery 20 and supplies it to the motor 42. The motor 42 is, for example, a main motor. The motor 42 is a device that rotates based on the power supplied from the battery 20 and applies rotational force to the wheels of the vehicle.

[0029] The in-vehicle power supply device 10 is used in an in-vehicle power supply system 100. The in-vehicle power supply device 10 includes a first system main relay 51 (hereinafter referred to as the "first SMR 51") and a second system main relay 52 (hereinafter referred to as the "second SMR 52").

[0030] The first SMR 51 corresponds to an example of a "system main relay." The first SMR 51 is provided in the power path 21 on the battery 20 side of the capacitor 22. The first SMR 51 is provided in the positive power line 30. One end of the first SMR 51 is electrically connected to the positive terminal of the battery 20 and short-circuited to the positive terminal of the battery 20. The other end of the first SMR 51 is electrically connected to one end of the capacitor 22 and short-circuited to the one end of the capacitor 22. In this embodiment, the first SMR 51 is a mechanical relay. The first SMR 51 includes contacts 51A, 51B, and 51C. The first SMR 51 includes fixed contacts 51A and 51B, a movable contact 51C, and a coil 51D that operates the movable contact 51C. When the coil 51D is energized, the first SMR 51 brings the movable contact 51C into contact with the fixed contacts 51A and 51B, thereby entering an ON state. When the coil 51D is not energized, the first SMR 51 separates the movable contact 51C from the fixed contacts 51A and 51B, thereby entering an OFF state.

[0031] The second SMR 52 is provided in the power path 21 closer to the battery 20 than the capacitor 22. The second SMR 52 is provided in the negative power line 31. One end of the second SMR 52 is electrically connected to the negative terminal of the battery 20 and shorted to the negative terminal of the battery 20. The other end of the second SMR 52 is electrically connected to the other end of the capacitor 22 and shorted to the other end of the capacitor 22. In this embodiment, the second SMR 52 is a mechanical relay. The second SMR 52 includes contacts 52A, 52B, and 52C. The second SMR 52 includes fixed contacts 52A and 52B, a movable contact 52C, and a coil 52D that operates the movable contact 52C. When the coil 52D is energized, the second SMR 52 brings the movable contact 52C into contact with the fixed contacts 52A and 52B, thereby entering an ON state. When the coil 52D is not energized, the second SMR 52 separates the movable contact 52C from the fixed contacts 52A and 52B, and is in an OFF state.

[0032] The positive power line 30 described above includes a first positive power line 32 provided on the battery 20 side of the first SMR 51, and a second positive power line 33 provided on the opposite side of the first SMR 51 from the battery 20. The negative power line 31 described above includes a first negative power line 34 provided on the battery 20 side of the second SMR 52, and a second negative power line 35 provided on the opposite side of the second SMR 52 from the battery 20.

[0033] The in-vehicle power supply device 10 includes a parallel circuit 53. The parallel circuit 53 is provided in parallel with the first SMR 51. One end of the parallel circuit 53 is electrically connected to the first positive power line 32 and short-circuited to the first positive power line 32. The other end of the parallel circuit 53 is electrically connected to the second positive power line 33 and short-circuited to the second positive power line 33. The parallel circuit 53 has a configuration in which a first relay 54 and a resistor 55 are connected in series.

[0034] In this embodiment, the first relay 54 is a mechanical relay. The first relay 54 includes contacts 54A, 54B, and 54C. The first relay 54 includes fixed contacts 54A and 54B, a movable contact 54C, and a coil 54D that operates the movable contact 54C. When the coil 54D is energized, the first relay 54 brings the movable contact 54C into contact with the fixed contacts 54A and 54B, thereby entering an ON state. When the coil 54D is not energized, the first relay 54 separates the movable contact 54C from the fixed contacts 54A and 54B, thereby entering an OFF state.

[0035] The resistance section 55 is formed of, for example, a known resistor.

[0036] The in-vehicle power supply device 10 includes a second relay 56. The second relay 56 is provided in parallel with the resistor 55. In this embodiment, the second relay 56 is a semiconductor relay. In this embodiment, the second relay 56 is an N-channel MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). The second relay 56 has an input 56A (a gate in this embodiment). The second relay 56 is turned on when an on signal (a high-level signal in this embodiment) is applied to the input 56A, and is turned off when an off signal (a low-level signal in this embodiment) is applied to the input 56A. A drain 56B of the second relay 56 is electrically connected to an end of the resistor 55 on the first positive power line 32 side and is short-circuited to the end of the resistor 55 on the first positive power line 32 side. The source 56C of the second relay 56 is electrically connected to the end of the resistor 55 on the second positive power line 33 side, and is short-circuited to the end of the resistor 55 on the second positive power line 33 side.

[0037] 2. Configuration of the Control Unit 57 of the In-Vehicle Power Supply Device 10 The in-vehicle power supply device 10 includes a control unit 57. The control unit 57 is configured to include a control circuit such as an integrated circuit. The control unit 57 includes a processing unit such as a CPU, a storage unit such as a memory, an input / output unit, etc. The control unit 57 controls the first SMR 51, the second SMR 52, the first relay 54, and the second relay 56.

[0038] The control unit 57 executes the first control when a start condition for starting charging / discharging of the battery 20 is met. The start condition is met when the first SMR 51, the second SMR 52, the first relay 54, and the second relay 56 are in the off state. The first control is control for controlling the first SMR 51 and the second relay 56 to the off state and controlling the second SMR 52 and the first relay 54 to the on state. The first control is also control for switching the second SMR 52 and the first relay 54 to the on state while maintaining the first SMR 51 and the second relay 56 in the off state. When the first control is executed, power from the battery 20 is supplied to the capacitor 22 via the parallel circuit 53. With this configuration, the current flowing through the power path 21 is suppressed by the resistor unit 55 of the parallel circuit 53. Therefore, the capacitor 22 can be charged while suppressing damage to the first SMR 51, the second SMR 52, and the first relay 54. As the voltage of the capacitor 22 increases, the difference between the voltage of the capacitor 22 and the voltage of the battery 20 decreases. As a result, the potential difference across the first SMR 51 decreases, and the potential difference across the second SMR 52 decreases.

[0039] The control unit 57 executes the second control when the first switching condition is met during execution of the first control. The second control is a control that controls the first SMR 51 to an OFF state and controls the second SMR 52, the first relay 54, and the second relay 56 to an ON state. The second control is a control that switches the second relay 56 to an ON state while maintaining the first SMR 51 in an OFF state and maintaining the second SMR 52 and the first relay 54 in an ON state.

[0040] The first switching condition is, for example, a condition that is met when the current flowing through the parallel circuit 53 is equal to or less than the rated current of the second relay 56. The first switching condition is, for example, a condition that is set to be met when the current flowing through the parallel circuit 53 is equal to or less than the rated current of the second relay 56.

[0041] A first example of the first switching condition is when the potential difference across the first SMR 51 becomes equal to or less than a first threshold. The control unit 57 acquires the potential difference across the first SMR 51 and determines whether the acquired potential difference becomes equal to or less than the first threshold. The method by which the control unit 57 acquires the potential difference across the first SMR 51 is not limited. For example, the control unit 57 may acquire the potential difference across the first SMR 51 by receiving a signal obtained by amplifying the potential difference across the first SMR 51 using a differential amplifier. Alternatively, the control unit 57 may acquire the potential difference across the first SMR 51 by separately acquiring the voltage of the battery 20 and the voltage of the capacitor 22 and calculating the difference between them. When the first switching condition is the first example, the in-vehicle power supply device 10 switches to the second control after the potential difference across the first SMR 51 becomes equal to or less than the first threshold. Therefore, the in-vehicle power supply device 10 can accurately determine the upper limit of the current flowing through the second relay 56 in the second control. Therefore, the in-vehicle power supply device 10 can easily use components with a rated current suitable for the second relay 56 as components of the second relay 56 .

[0042] A second example of the first switching condition is when the value of the current flowing through the parallel circuit 53 becomes equal to or less than the first threshold. The control unit 57 acquires the value of the current flowing through the parallel circuit 53 and determines whether the acquired value of the current becomes equal to or less than the first threshold. The method by which the control unit 57 acquires the value of the current flowing through the parallel circuit 53 is not limited. For example, the automotive power supply system 100 may be provided with a current sensor that detects the current flowing through the parallel circuit 53, and the control unit 57 may acquire the detected value of the current sensor. When the first switching condition is the second example, the automotive power supply device 10 switches to the second control mode after the value of the current flowing through the parallel circuit 53 becomes equal to or less than the first threshold. This allows the automotive power supply device 10 to accurately determine the upper limit of the current flowing through the second relay 56 in the second control mode. This makes it easy for the automotive power supply device 10 to use components with rated currents suitable for the second relay 56 as components of the second relay 56.

[0043] A third example of the first switching condition is when a first time has elapsed since the start of the first control. When the first switching condition is the third example, the in-vehicle power supply device 10 switches to the second control after the first time has elapsed since the start of the first control. In other words, the in-vehicle power supply device 10 uses the first control to increase the voltage of the capacitor 22 to a certain extent before switching to the second control. This allows the in-vehicle power supply device 10 to set, with a certain degree of accuracy, the upper limit of the current flowing through the second relay 56 during the second control, with a simple configuration. Therefore, the in-vehicle power supply device 10 can easily use components with a rated current suitable for the second relay 56 as components of the second relay 56.

[0044] A fourth example of the first switching condition is when the voltage of the capacitor 22 becomes equal to or greater than the first threshold voltage. The control unit 57 acquires the voltage of the capacitor 22 and determines whether the acquired voltage becomes equal to or greater than the first threshold voltage. The method by which the control unit 57 acquires the voltage of the capacitor 22 is not limited. For example, the control unit 57 may acquire the voltage of the capacitor 22 detected by a known voltage detection circuit. When the first switching condition is the fourth example, the in-vehicle power supply device 10 switches to the second control after the voltage of the capacitor 22 becomes equal to or greater than the first threshold voltage. In other words, the in-vehicle power supply device 10 switches to the second control after the difference between the voltage of the battery 20 and the voltage of the capacitor 22 becomes small to a certain extent. Therefore, the in-vehicle power supply device 10 can accurately determine the upper limit of the current flowing through the second relay 56 in the second control. Therefore, the in-vehicle power supply device 10 can easily use components with a rated current suitable for the second relay 56 as components of the second relay 56.

[0045] The control unit 57 executes the third control when the second switching condition is met during execution of the second control. The third control is a control for controlling the first relay 54 and the second relay 56 to an OFF state and controlling the first SMR 51 and the second SMR 52 to an ON state. The third control is a control for switching the first relay 54 and the second relay 56 to an OFF state and switching the first SMR 51 to an ON state while maintaining the second SMR 52 in an ON state.

[0046] The second switching condition is, for example, a condition that is met when the potential difference across the first SMR 51 is equal to or less than a target value. The second switching condition is, for example, a condition that is set to be met when the potential difference across the first SMR 51 is equal to or less than a target value. The target value is, for example, 0.

[0047] A first example of the second switching condition is that the potential difference across the first SMR 51 becomes equal to or less than the second threshold. When the first switching condition is the first example, the second threshold is a value smaller than the first threshold. The control unit 57 acquires the potential difference across the first SMR 51 and determines whether the acquired potential difference becomes equal to or less than the second threshold. The method by which the control unit 57 acquires the potential difference across the first SMR 51 is not limited, and may be the same as the first example of the first switching condition, for example. When the second switching condition is the first example, the automotive power supply device 10 reduces the potential difference across the first SMR 51 to equal to or less than the second threshold before switching to the third control. This allows the automotive power supply device 10 to more reliably suppress inrush current from flowing through the first SMR 51.

[0048] A second example of the second switching condition is that the value of the current flowing through the parallel circuit 53 becomes equal to or less than the second threshold. When the first switching condition is the second example, the second threshold is a value smaller than the first threshold. The control unit 57 acquires the value of the current flowing through the parallel circuit 53 and determines whether the acquired value of the current becomes equal to or less than the second threshold. The method by which the control unit 57 acquires the value of the current flowing through the parallel circuit 53 is not limited, and may be the same as the second example of the first switching condition, for example. When the second switching condition is the second example, the automotive power supply device 10 reduces the value of the current flowing through the parallel circuit 53 to equal to or less than the second threshold before switching to the third control. This allows the automotive power supply device 10 to more reliably suppress inrush current from flowing through the first SMR 51.

[0049] A third example of the second switching condition is that a second time has elapsed since the start of the second control. When the first switching condition is the third example, the second time is, for example, a time shorter than the first time. In this case, the in-vehicle power supply device 10 can easily ensure a long first time, and therefore can easily increase the voltage of the capacitor 22 when switching to the second control. Therefore, the in-vehicle power supply device 10 is likely to use components with a low rated current as components of the second relay 56. When the second switching condition is the third example, the in-vehicle power supply device 10 can easily simplify the determination of whether the second switching condition is met.

[0050] A fourth example of the second switching condition is that the voltage of the capacitor 22 becomes equal to or greater than the second threshold voltage. When the first switching condition is the fourth example, the second threshold voltage is a value greater than the first threshold voltage. The control unit 57 acquires the voltage of the capacitor 22 and determines whether the acquired voltage becomes equal to or greater than the first threshold voltage. The method by which the control unit 57 acquires the voltage of the capacitor 22 is not limited, and may be the same as that of the fourth example of the first switching condition, for example. When the second switching condition is the fourth example, the in-vehicle power supply device 10 can switch the first SMR 51 to the on state after reducing the potential difference between the voltage of the capacitor 22 and the voltage of the battery 20 to a certain extent, without monitoring the potential difference. Therefore, the in-vehicle power supply device 10 can, with a simple configuration, to some extent suppress damage to the first SMR 51 that occurs when the first SMR 51 is switched to the on state.

[0051] 3. Operation of In-Vehicle Power Supply Apparatus 10 The control unit 57 of the in-vehicle power supply apparatus 10 performs the processing shown in Fig. 2. The control unit 57 starts the processing shown in Fig. 2 when, for example, the first SMR 51, the second SMR 52, the first relay 54, and the second relay 56 are in the OFF state.

[0052] In step S101, the control unit 57 determines whether the above-mentioned start condition is met. The control unit 57 determines that the start condition is met when, for example, it receives an instruction to start charging or discharging from a host ECU. If the control unit 57 determines that the start condition is not met (No in step S101), it repeats the process of step S101 until the start condition is met.

[0053] If the control unit 57 determines that the start condition is met (Yes in step S101), it starts the first control in step S102. That is, the control unit 57 switches the second SMR 52 and the first relay 54 to the ON state while keeping the first SMR 51 and the second relay 56 in the OFF state. This causes power from the battery 20 to charge the capacitor 22 via the parallel circuit 53. That is, the current limited by the resistor unit 55 flows through the power path 21 and charges the capacitor 22.

[0054] The control unit 57 performs the process of step S103 while the first control is being executed. In step S103, the control unit 57 determines whether the first switching condition described above is met. If the control unit 57 determines that the first switching condition is not met (No in step S103), it repeats the process of step S103 until the first switching condition is met. During this time, the voltage of the capacitor 22 gradually increases, and the potential difference across the first SMR 51 gradually decreases.

[0055] If the control unit 57 determines that the first switching condition is met (Yes in step S103), it switches to the second control in step S104. That is, the control unit 57 switches the second relay 56 to the on state while maintaining the first SMR 51 in the off state and the second SMR 52 in the on state. This causes power from the battery 20 to bypass the resistor unit 55 and charge the capacitor 22. That is, the current from the battery 20 is supplied to the capacitor 22 without being limited by the resistor unit 55.

[0056] The control unit 57 performs the process of step S105 while the second control is being executed. In step S105, the control unit 57 determines whether the second switching condition described above is met. If the control unit 57 determines that the second switching condition is not met (No in step S105), it repeats the process of step S105 until the second switching condition is met. During this time, the voltage of the capacitor 22 further increases, and the potential difference across the first SMR 51 further decreases.

[0057] If the control unit 57 determines that the second switching condition is met (Yes in step S105), it switches to the third control in step S106. That is, the control unit 57 switches the first relay 54 and the second relay 56 to the OFF state and switches the first SMR 51 to the ON state while maintaining the second SMR 52 in the ON state. By switching the first SMR 51 to the ON state when the potential difference between both ends of the first SMR 51 is reduced, damage to the first SMR 51 is suppressed. By executing the third control, power from the battery 20 is supplied to the power path 21 via the first SMR 51 and then to the drive unit 40 via the power path 21.

[0058] After switching to the third control, the control unit 57 ends the process shown in FIG.

[0059] In FIG. 3 , the change in the voltage of the capacitor 22 over time is shown by a solid line. When the start condition is met and the first control is initiated, the voltage of the capacitor 22 gradually increases from 0 V. The rate of increase in the voltage of the capacitor 22 slows as the voltage of the capacitor 22 approaches the voltage of the battery 20. The control unit 57 switches to the second control at time t1, when the rate of increase in the voltage of the capacitor 22 slows. This accelerates the rate of increase in the voltage of the capacitor 22, and the voltage of the capacitor 22 reaches the target voltage at time t2. If the control unit 57 did not switch to the second control at time t1, it would take a considerable amount of time for the voltage of the capacitor 22 to reach the target voltage, as shown by the dashed curve. In contrast, by switching to the second control at time t1, the automotive power supply device 10 can significantly reduce the time required for the voltage of the capacitor 22 to reach the target voltage.

[0060] 4. Example of Effects The in-vehicle power supply device 10 can precharge the capacitor 22 via the resistor unit 55 when the first SMR 51 and the second relay 56 are in the OFF state and the first relay 54 is in the ON state. Furthermore, the in-vehicle power supply device 10 can precharge the capacitor 22 more quickly, bypassing the resistor unit 55, when the first SMR 51 is in the OFF state and the first relay 54 and the second relay 56 are in the ON state. Therefore, the in-vehicle power supply device 10 is capable of precharging via the resistor unit 55 and can complete precharging of the capacitor 22 more quickly while minimizing damage to the first SMR 51.

[0061] By switching to the second control after the voltage of the capacitor 22 has been increased to a certain extent under the first control, the in-vehicle power supply device 10 can switch to a more rapid precharge while avoiding an inrush current from flowing to the first relay 54. This allows the in-vehicle power supply device 10 to more quickly complete the precharge of the capacitor 22 while minimizing damage to the first SMR 51.

[0062] In the in-vehicle power supply device 10, the second relay 56 is a contactless semiconductor relay, and therefore damage to the second relay 56 can be avoided when switching from the first control to the second control.

[0063] <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.

[0064] In each of the above embodiments, the second SMR 52 does not necessarily have to be provided.

[0065] In each of the above embodiments, the first SMR 51 is configured to be an example of a system main relay, but the second SMR 52 may be an example of a system main relay. In this case, the parallel circuit 53 is provided in parallel with the second SMR 52. In this case, the first SMR 51 may not be provided.

[0066] In the above embodiments, the first relay 54 is a mechanical relay, but may be a semiconductor relay. In the above embodiments, the second relay 56 is a semiconductor relay, but may be a mechanical relay.

[0067] 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.

[0068] DESCRIPTION OF SYMBOLS 10...In-vehicle power supply device 20...Battery 21...Power path 22...Capacitor 30...Positive power line 31...Negative power line 32...First positive power line 33...Second positive power line 34...First negative power line 35...Second negative power line 40...Drive unit 41...Inverter 42...Motor 51...First system main relay (system main relay) 51A...Contact, fixed contact 51B...Contact, fixed contact 51C...Contact, moving contact 51D...Coil 52...Second system main relay 52A...Contact, fixed contact 52B...Contact, fixed contact 52C...Contact, moving contact 52D...Coil 53...Parallel circuit 54...First relay 54A...Contact, fixed contact 54B...Contact, fixed contact 54C...Contact, moving contact 54D...Coil 55...Resistance unit 56... Second relay 56A... Input section 56B... Drain 56C... Source 57... Control section 100... In-vehicle power supply system

Claims

1. An on-board power supply device for use in an on-board power supply system including a battery, a power path to which power based on the battery is supplied, and a capacitor connected to the power path, a mechanical system main relay provided in the power path on the battery side relative to the capacitor; a parallel circuit including a first relay and a resistor connected in series and disposed in parallel with the system main relay; A second relay provided in parallel with the resistor portion; Equipped Automotive power supply device.

2. a control unit for controlling the system main relay, the first relay, and the second relay; The control unit is a first control is executed to control the system main relay and the second relay to an off state and to control the first relay to an on state when a start condition for starting charging / discharging of the battery is satisfied; When a first switching condition is satisfied during execution of the first control, a second control is executed to control the system main relay to an off state and to control the first relay and the second relay to an on state; When a second switching condition is satisfied during execution of the second control, a third control is executed in which the first relay and the second relay are controlled to be in an off state and the system main relay is controlled to be in an on state.

2. The vehicle-mounted power supply device according to claim 1.

3. The second relay is a semiconductor relay.

3. The vehicle-mounted power supply device according to claim 2.

4. The first switching condition is that a potential difference across the system main relay or a value of a current flowing through the parallel circuit is equal to or less than a threshold value.

4. The vehicle-mounted power supply device according to claim 2 or 3.

5. The first switching condition is that a first time has elapsed since the start of the first control.

4. The vehicle-mounted power supply device according to claim 2 or 3.

6. The second switching condition is that a second time period shorter than the first time period has elapsed since the start of the second control.

6. The vehicle-mounted power supply device according to claim 5.

7. The second switching condition is that the voltage of the capacitor is equal to or greater than a threshold voltage.

4. The vehicle-mounted power supply device according to claim 2 or 3.