WO2024089800A1 - Power-supply control device - Google Patents

Abstract

A power-supply control device (10) comprises a control unit (11) that controls a system main relay (first SMR (23)) and a pre-charge relay (25A). The control unit (11) starts first control of controlling the system main relay (first SMR (23)) to reach an OFF state and controlling the pre-charge relay (25A) to reach an ON state when a start condition for starting charge/discharge of a battery (20) is satisfied. The control unit (11) switches the first control to second control of controlling the system main relay (first SMR (23)) to reach an ON state and controlling the pre-charge relay (25A) to reach an OFF state when a pre-charge period has elapsed since the start of the first control. The control unit (11) sets, as the pre-charge period, a first period when a first condition is satisfied upon the establishment of the start condition or sets, as the pre-charge period, a second period longer than the first period when a second condition is satisfied upon the establishment of the start condition.

Description

Power Control Unit

This disclosure relates to a power supply control device.

Patent Document 1 discloses a system in which a main relay and an intelligent power switch device are connected in parallel to the power supply line between a battery power source and a motor controller. If the main relay is turned on when the capacitor in the motor controller is not charged, there is a risk that the main relay may be damaged. Therefore, the above system turns on the main relay when the capacitor in the motor controller is sufficiently charged by the action of the intelligent power switch device and there is no potential difference in the main relay.

JP 2000-253570 A

With this type of technology, it takes time for the capacitor to be charged before power can begin to be supplied via the system main relay (main relay). However, in some situations, it may be desirable to prioritize rapid start of power supply over minimizing damage to the system main relay.

The purpose of this disclosure is to provide technology that makes it possible to quickly start supplying power via the system main relay depending on the situation, while easily minimizing damage to the system main relay.

The power supply control device of the present disclosure includes:
A power supply control device for use in a vehicle, the power supply control device comprising: a battery; a power path to which power based on the battery is supplied; a capacitor connected to the power path; a system main relay provided in the power path on the battery side of the capacitor; and a parallel circuit having a configuration in which a pre-charge relay and a resistor unit are connected in series and provided in parallel with the system main relay,
a control unit for controlling the system main relay and the precharge relay,
the control unit starts a first control for controlling the system main relay to an off state and the pre-charge relay to an on state when a start condition for starting charging/discharging of the battery is satisfied, and switches to a second control for controlling the system main relay to an on state and the pre-charge relay to an off state when a pre-charge period has elapsed since starting the first control,
Furthermore, when a first condition is satisfied when the start condition is established, the control unit sets a first period as the precharge period, and when a second condition is satisfied when the start condition is established, sets a second period longer than the first period as the precharge period.

The technology disclosed herein makes it possible to quickly start supplying power via the system main relay depending on the situation, while making it easier to prevent damage to the system main relay.

FIG. 1 is a block diagram of a vehicle equipped with a power supply control device according to a first embodiment. FIG. 2 is an explanatory diagram illustrating a change in the voltage of a capacitor over time. FIG. 3 is a flowchart showing a flow of processing performed by the power supply control device of the first embodiment. FIG. 4 is a flowchart showing the flow of processing performed by the power supply control device of the second embodiment. FIG. 5 is a flowchart showing a flow of processing performed by the power supply control device of the third embodiment.

Below, embodiments of the present disclosure are listed and illustrated.

[1] A power supply control device for use in a vehicle, the power supply control device comprising: a battery; a power path to which power based on the battery is supplied; a capacitor connected to the power path; a system main relay provided in the power path on the battery side of the capacitor; and a parallel circuit having a configuration in which a precharge relay and a resistor are connected in series and provided in parallel with the system main relay,
a control unit for controlling the system main relay and the precharge relay,
the control unit starts a first control for controlling the system main relay to an off state and the pre-charge relay to an on state when a start condition for starting charging/discharging of the battery is satisfied, and switches to a second control for controlling the system main relay to an on state and the pre-charge relay to an off state when a pre-charge period has elapsed since starting the first control,
Furthermore, the control unit sets a first period as the precharge period when a first condition is satisfied when the start condition is satisfied, and sets a second period longer than the first period as the precharge period when a second condition is satisfied when the start condition is satisfied.

The power supply control device sets a shorter first period as the precharge period when the first condition is satisfied when the start condition is met, and therefore can quickly start power supply via the system main relay. Furthermore, the power supply control device sets a longer second period as the precharge period when the second condition is satisfied when the start condition is met, and therefore can prevent damage to the system main relay. Thus, the power supply control device is likely to prevent damage to the system main relay while enabling quick start of power supply via the system main relay depending on the situation.

[2] The first condition is that a starter switch of the vehicle is in an on state,
The power supply control device according to [1], wherein one of the second conditions is that at least the start switch is in an off state.

When the vehicle start switch is in the ON state, the power supply control device sets a relatively short first period as the precharge period, and can quickly start supplying power via the system main relay. Furthermore, the power supply control device sets a relatively long second period as the precharge period at least in some cases when the vehicle start switch is in the OFF state, and can suppress damage to the system main relay.

[3] The first period is a period from when the start condition is satisfied to when a first time has elapsed,
The power supply control device according to claim 1 or 2, wherein the second period is a period from when the start condition is satisfied until a second time longer than the first time has elapsed.

The power supply control device described above makes it easy to simplify the configuration for determining the passage of the first and second periods.

[4] The first period is a period until a value of a current flowing through the parallel circuit or a potential difference across the system main relay becomes equal to or less than a first threshold value,
The power supply control device according to [1] or [2], wherein the second period is a period until a value of a current flowing through the parallel circuit or a potential difference across the system main relay becomes equal to or less than a second threshold value that is smaller than the first threshold value.

The power supply control device described above can reduce the value of the current flowing through the parallel circuit or the potential difference across the system main relay to a predetermined value, regardless of the external environment, such as the degree of battery deterioration, before switching the system main relay to the on state. This makes it possible to more accurately prevent damage to the system main relay that would otherwise occur when the relay is switched to the on state.

[5] The first period is a period until the voltage of the capacitor becomes equal to or greater than a first threshold voltage,
The power supply control device according to claim 1 or 2, wherein the second period is a period until the voltage of the capacitor becomes equal to or higher than a second threshold voltage that is higher than the first threshold voltage.

The power supply control device can switch the system main relay to the on state after reducing the potential difference between the capacitor voltage and the battery voltage to a certain degree without monitoring the potential difference. Therefore, the power supply control device can easily realize a configuration that suppresses damage to the system main relay that occurs when the relay is switched to the on state with a certain degree of accuracy.

First Embodiment
1. Configuration of vehicle 100 Fig. 1 shows a vehicle 100 equipped with a power supply control device 10. The vehicle 100 may be an electric vehicle, a fuel cell vehicle (FCV), or a hybrid vehicle. The vehicle 100 includes a battery 20, a power path 21, a capacitor 22, a first system main relay 23 (hereinafter referred to as "first SMR 23"), a second system main relay 24 (hereinafter referred to as "second SMR 24"), a parallel circuit 25, a branch path 26, and a load 27.

The battery 20 may be a lithium ion battery, a lead battery, or some other type of battery.

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. The positive terminal of the battery 20 is electrically connected to the positive power line 30. The negative terminal of the battery 20 is electrically connected to the negative power line 31. The negative power line 31 is electrically connected to the 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 based on the ground potential and a potential difference based on the negative power line 31.

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.

In this embodiment, the capacitor 22 is configured as part of the drive unit 40 provided in the vehicle 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 provides a rotational force to the wheels of the vehicle 100.

The first SMR 23 corresponds to an example of a "system main relay". The first SMR 23 is provided in the power path 21 on the battery 20 side of the capacitor 22. The first SMR 23 is provided in the positive power line 30. One end of the first SMR 23 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 23 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 23 is a mechanical relay. The mechanical relay includes contacts. The mechanical relay includes a fixed contact, a movable contact, and a coil that operates the movable contact. When a current is applied to the coil, the mechanical relay brings the movable contact into contact with the fixed contact and is in an ON state. When a current is not applied to the coil, the mechanical relay separates the movable contact from the fixed contact and is in an OFF state.

The second SMR 24 is provided in the power path 21 on the battery 20 side of the capacitor 22. The second SMR 24 is provided in the negative power line 31. One end of the second SMR 24 is electrically connected to the negative terminal of the battery 20 and short-circuited to the negative terminal of the battery 20. The other end of the second SMR 24 is electrically connected to the other end of the capacitor 22 and short-circuited to the other end of the capacitor 22. In this embodiment, the second SMR 24 is a mechanical relay and has a configuration similar to that of the first SMR 23, for example.

The above-mentioned positive power line 30 has a first positive power line 32 provided on the battery 20 side of the first SMR 23, and a second positive power line 33 provided on the opposite side of the first SMR 23 from the battery 20 side. The above-mentioned negative power line 31 has a first negative power line 34 provided on the battery 20 side of the second SMR 24, and a second negative power line 35 provided on the opposite side of the second SMR 24 from the battery 20 side.

The parallel circuit 25 is configured by connecting a precharge relay 25A and a resistance section 25B in series. In this embodiment, the precharge relay 25A is a mechanical relay and has a configuration similar to that of, for example, the first SMR 23. The resistance section 25B is configured, for example, by a known resistor. The parallel circuit 25 is provided in parallel with the first SMR 23. One end of the parallel circuit 25 is electrically connected to the first positive side power line 32 and is short-circuited to the first positive side power line 32. The other end of the parallel circuit 25 is electrically connected to the second positive side power line 33 and is short-circuited to the second positive side power line 33.

The branch path 26 is a branch path branching off from the power path 21 on the side opposite the battery 20 side of the first SMR 23 (system main relay). The branch path 26 has a positive branch line 26A and a negative branch line 26B. The positive branch line 26A branches off from the positive power line 30 (more specifically, the second positive power line 33). The negative branch line 26B branches off from the negative power line 31 (more specifically, the second negative power line 35).

The load 27 is electrically connected to the branch path 26. Power based on the battery 20 is supplied to the load 27 via the power path 21 and the branch path 26. The load 27 is a load that can be used when the start switch of the vehicle 100 is in the off state, and is, for example, an air conditioner or a heater. The start switch is a power switch if the vehicle 100 is an electric vehicle or a fuel cell vehicle (FCV), and is an ignition switch if the vehicle 100 is a hybrid vehicle.

2. Configuration of the Power Supply Control Device 10 The power supply control device 10 is used in a vehicle 100. The power supply control device 10 includes a control unit 11. The control unit 11 is configured to include a control circuit such as an integrated circuit. The control unit 11 includes a processing unit such as a CPU, a storage unit such as a memory, an input/output unit, etc. The control unit 11 controls the first SMR 23, the second SMR 24, and the pre-charge relay 25A.

The control unit 11 starts the first control when a start condition for starting charging and discharging of the battery 20 is satisfied. The first control is a control that controls the first SMR 23 to an off state and controls the second SMR 24 and the precharge relay 25A to an on state. When the first control is performed, power based on the battery 20 is supplied to the capacitor 22 via the parallel circuit 25. With this configuration, the current flowing through the power path 21 is suppressed by the resistor portion 25B of the parallel circuit 25. Therefore, the capacitor 22 can be charged while suppressing damage to the first SMR 23, the second SMR 24, and the precharge relay 25A. As the voltage of the capacitor 22 increases, the difference between the voltage of the capacitor 22 and the voltage of the battery 20 becomes smaller. As a result, the potential difference across the first SMR 23 becomes smaller, and the potential difference across the second SMR 24 becomes smaller.

The control unit 11 switches to the second control when the precharge period has elapsed since the start of the first control. The second control is a control that switches the first SMR 23 to the on state and switches the precharge relay 25A to the off state. More specifically, the second control is a control that controls the precharge relay 25A to the off state and controls the first SMR 23 and the second SMR 24 to the on state. When the second control is performed, power based on the battery 20 is supplied to the capacitor 22 via the first SMR 23 (system main relay). When the potential difference between both ends of the first SMR 23 and the second SMR 24 is small, the control unit 11 switches to the second control, thereby suppressing the inrush current to the first SMR 23 and the second SMR 24, and as a result, damage to the first SMR 23 and the second SMR 24 is suppressed.

When the first condition is satisfied when the start condition is satisfied, the control unit 11 sets the first period as the precharge period. In this embodiment, the first condition is that the start switch of the vehicle 100 is in an on state. The control unit 11 is configured to be able to acquire an on/off signal indicating the on/off state of the start switch of the vehicle 100, and determines the on/off state of the start switch of the vehicle 100 based on the acquired on/off signal. The control unit 11 may directly acquire the signal output from the start switch, or may acquire it via a higher-level ECU (Electronic Control Unit). A specific example of "when the first condition is satisfied when the start condition is satisfied" is, for example, "when the start condition is satisfied when the vehicle 100 is started." In this case, the vehicle 100 is started quickly. In this embodiment, the first period is the period from when the start condition is satisfied until the first time T1 has elapsed.

When the second condition is satisfied when the start condition is satisfied, the control unit 11 sets a second period longer than the first period as the precharge period. In this embodiment, the second condition is that the start switch of the vehicle 100 is in the OFF state. A specific example of "when the second condition is satisfied when the start condition is satisfied" is, for example, "when the user performs an operation to drive the load 27 with the start switch in the OFF state." In this embodiment, the second period is the period from when the start condition is satisfied until a second time T2 longer than the first time T1 has elapsed.

Figure 2 shows the change in the voltage of capacitor 22 over time. The example shown in Figure 2 shows how the voltage of capacitor 22 gradually rises from 0V when the start condition is met. When a first time T1 has elapsed since the start condition was met, the voltage of capacitor 22 becomes V1, and the difference with the voltage of battery 20 becomes X1. That is, the potential difference between both ends of the first SMR 23 and the potential difference between both ends of the second SMR 24 becomes X1. When a second time T2 has elapsed since the start condition was met, the voltage of capacitor 22 becomes V2, and the difference with the voltage of battery 20 becomes X2, which is smaller than X1. That is, the potential difference between both ends of the first SMR 23 and the potential difference between both ends of the second SMR 24 becomes X2, which is smaller than X1. When the control unit 11 switches to the second control in a state where the potential difference between both ends of the first SMR 23 and the second SMR 24 is X1, the first SMR 23 and the second SMR 24 may be slightly damaged, but power supply via the first SMR 23 can be quickly started. In contrast, when the control unit 11 switches to the second control in a state where the potential difference between both ends of the first SMR 23 and the second SMR 24 is X2, the inrush current to the first SMR 23 and the second SMR 24 is more reliably suppressed, and as a result, damage to the first SMR 23 and the second SMR 24 is more reliably suppressed.

3. Operation of the Power Supply Control Device 10 The control unit 11 of the power supply control device 10 performs the process shown in Fig. 3. The control unit 11 starts the process shown in Fig. 3, for example, when the integrated circuit constituting the control unit 11 is started. Note that, at the time when the process shown in Fig. 3 is started, the first SMR 23, the second SMR 24, and the precharge relay 25A are in the off state.

In step S101, the control unit 11 determines whether the above-mentioned start condition is met. The control unit 11 determines that the start condition is met, for example, when an instruction to start charging or discharging is received from a higher-level ECU. If the control unit 11 determines that the start condition is not met (No in step S101), the control unit 11 returns to step S101. In other words, the control unit 11 repeats the process of step S101 until the start condition is met.

If the control unit 11 determines that the start condition is met (Yes in step S101), it starts the first control in step S102. That is, the control unit 11 switches the second SMR 24 and the precharge relay 25A to the on state while keeping the first SMR 23 in the off state. This causes the power based on the battery 20 to be charged to the capacitor 22 via the parallel circuit 25.

In step S103, the control unit 11 starts the operation of the timer. This causes the control unit 11 to measure the elapsed time since the start condition was met. Note that step S103 may be performed prior to step S102.

In step S104, the control unit 11 determines whether the start switch is in the ON state. If the control unit 11 determines that the start switch is in the ON state (Yes in step S104), it determines in step S105 whether the first time T1 has elapsed since the start condition was met. If the control unit 11 determines that the first time T1 has not elapsed (No in step S105), it repeats the process of step S105 until the first time T1 has elapsed. If the control unit 11 determines that the first time T1 has elapsed (Yes in step S105), it switches to the second control in step S106. Specifically, the control unit 11 switches the first SMR 23 to the ON state while maintaining the second SMR 24 in the ON state, and switches the precharge relay 25A to the OFF state. Thereafter, the control unit 11 ends the process shown in FIG. 3.

If the control unit 11 determines that the start switch is in the OFF state (No in step S104), it determines in step S107 whether or not the second time T2 has elapsed since the start condition was met. If the control unit 11 determines that the second time T2 has not elapsed (No in step S107), it repeats the process of step S107 until the second time T2 has elapsed. If the control unit 11 determines that the second time T2 has elapsed (Yes in step S107), it switches to the second control in step S106. Specifically, the control unit 11 switches the first SMR 23 to the ON state while maintaining the second SMR 24 in the ON state, and switches the pre-charge relay 25A to the OFF state. Thereafter, the control unit 11 ends the process shown in FIG. 3.

After completing the process shown in FIG. 3, the control unit 11 resumes the process shown in FIG. 3 when the first SMR 23, the second SMR 24, and the pre-charge relay 25A are all turned off. For example, when the control unit 11 receives an instruction to end charging and discharging from a higher-level ECU, the control unit 11 controls the first SMR 23, the second SMR 24, and the pre-charge relay 25A to all turned off. When the control unit 11 controls the first SMR 23, the second SMR 24, and the pre-charge relay 25A to all turned off, the control unit 11 may or may not discharge the capacitor 22.

4. Example of Effects When the start condition is satisfied and the first condition is satisfied, the power supply control device 10 sets a shorter first period as the precharge period, so that the power supply control device 10 can quickly start the power supply via the first SMR 23 (system main relay). Furthermore, when the start condition is satisfied and the second condition is satisfied, the power supply control device 10 sets a longer second period as the precharge period, so that the damage to the first SMR 23 (system main relay) can be suppressed. Therefore, the power supply control device 10 can quickly start the power supply via the first SMR 23 (system main relay) depending on the situation, while easily suppressing damage to the first SMR 23 (system main relay).

When the start switch of the vehicle 100 is in the ON state, the power supply control device 10 sets a relatively short first period as the precharge period, and can quickly start supplying power via the first SMR 23 (system main relay). Furthermore, the power supply control device 10 sets a relatively long second period as the precharge period at least in some cases when the start switch of the vehicle 100 is in the OFF state, and can suppress damage to the first SMR 23 (system main relay).

The power supply control device 10 can easily simplify the configuration for determining the progress of the first and second periods.

Second Embodiment
The first period and the second period are not limited to the examples described in the first embodiment. In the second embodiment, other examples of the first period and the second period will be described. Note that a vehicle equipped with the power supply control device of the second embodiment has the same configuration as that shown in FIG. 1, and therefore will be described with reference to FIG. 1.

In the second embodiment, the first period is the period until the value of the current flowing through the parallel circuit 25 becomes equal to or less than a first threshold. The second period is the period until the value of the current flowing through the parallel circuit 25 becomes equal to or less than a second threshold that is smaller than the first threshold.

The control unit 11 of the power supply control device 10 of the second embodiment performs the process shown in FIG. 4. The control unit 11 starts the process shown in FIG. 4, for example, when the integrated circuit constituting the control unit 11 is started. Note that, at the time when the process shown in FIG. 4 is started, the first SMR 23, the second SMR 24, and the precharge relay 25A are in the off state.

In step S201, the control unit 11 determines whether the start condition is satisfied. If the control unit 11 determines that the start condition is satisfied (Yes in step S201), the control unit 11 starts the first control in step S202. As a result, the power based on the battery 20 is charged to the capacitor 22 via the parallel circuit 25.

In step S204, the control unit 11 determines whether the start switch is on. If the control unit 11 determines that the start switch is on (Yes in step S204), then in step S205, the control unit 11 determines whether the value of the current flowing through the parallel circuit 25 is equal to or less than the first threshold. If the control unit 11 determines that the value of the current flowing through the parallel circuit 25 is not equal to or less than the first threshold (No in step S205), then the control unit 11 repeats the process of step S205 until the value of the current flowing through the parallel circuit 25 is equal to or less than the first threshold. If the control unit 11 determines that the value of the current flowing through the parallel circuit 25 is equal to or less than the first threshold (Yes in step S205), then the control unit 11 switches to the second control in step S206. Thereafter, the control unit 11 ends the process shown in FIG. 4.

If the control unit 11 determines that the start switch is off (No in step S204), it determines in step S207 whether the value of the current flowing through the parallel circuit 25 is equal to or less than a second threshold value that is smaller than the first threshold value. If the control unit 11 determines that the value of the current flowing through the parallel circuit 25 is not equal to or less than the second threshold value (No in step S207), it repeats the process of step S207 until the value of the current flowing through the parallel circuit 25 is equal to or less than the second threshold value. If the control unit 11 determines that the value of the current flowing through the parallel circuit 25 is equal to or less than the second threshold value (Yes in step S207), it switches to the second control in step S206. Thereafter, the control unit 11 ends the process shown in FIG. 4.

As described above, the power supply control device 10 of the second embodiment can reduce the value of the current flowing through the parallel circuit 25 to a predetermined value and then switch the first SMR 23 (system main relay) to the on state, regardless of the external environment, such as the degree of deterioration of the battery 20. This makes it possible to more accurately prevent damage to the first SMR 23 (system main relay) that would occur when the first SMR 23 is switched to the on state.

Third Embodiment
In the third embodiment, a second example of the first period and the second period will be described. Note that a vehicle equipped with a power supply control device of the third embodiment has the same configuration as that shown in Fig. 1, and therefore will be described with reference to Fig. 1.

In the third embodiment, the first period is the period until the voltage of the capacitor 22 becomes equal to or greater than the first threshold voltage. The second period is the period until the voltage of the capacitor 22 becomes equal to or greater than the second threshold voltage, which is greater than the first threshold voltage.

The control unit 11 of the power supply control device 10 of the third embodiment performs the process shown in FIG. 5. The control unit 11 starts the process shown in FIG. 5, for example, when the integrated circuit constituting the control unit 11 is started. Note that, at the time when the process shown in FIG. 5 is started, the first SMR 23, the second SMR 24, and the precharge relay 25A are in the off state.

In step S301, the control unit 11 determines whether the start condition is satisfied. If the control unit 11 determines that the start condition is satisfied (Yes in step S301), the control unit 11 starts the first control in step S302. As a result, the power based on the battery 20 is charged to the capacitor 22 via the parallel circuit 25.

In step S304, the control unit 11 determines whether the start switch is on. If the control unit 11 determines that the start switch is on (Yes in step S304), then in step S305, the control unit 11 determines whether the voltage of the capacitor 22 is equal to or higher than the first threshold voltage. If the control unit 11 determines that the voltage of the capacitor 22 is not equal to or higher than the first threshold voltage (No in step S305), then the control unit 11 repeats the process of step S305 until the voltage of the capacitor 22 is equal to or higher than the first threshold voltage. If the control unit 11 determines that the voltage of the capacitor 22 is equal to or higher than the first threshold voltage (Yes in step S305), then the control unit 11 switches to the second control in step S306. Thereafter, the control unit 11 ends the process shown in FIG. 5.

If the control unit 11 determines that the start switch is off (No in step S304), it determines in step S307 whether the voltage of the capacitor 22 is equal to or higher than a second threshold voltage that is lower than the first threshold voltage. If the control unit 11 determines that the voltage of the capacitor 22 is not equal to or higher than the second threshold voltage (No in step S307), it repeats the process of step S307 until the voltage of the capacitor 22 is equal to or higher than the second threshold voltage. If the control unit 11 determines that the voltage of the capacitor 22 is equal to or higher than the second threshold voltage (Yes in step S307), it switches to the second control in step S306. Thereafter, the control unit 11 ends the process shown in FIG. 5.

As described above, the power supply control device 10 of the third embodiment can switch the first SMR 23 (system main relay) to the on state after reducing the potential difference to a certain degree without monitoring the potential difference between the voltage of the capacitor 22 and the voltage of the battery 20. Therefore, the power supply control device 10 can easily realize a configuration that suppresses damage to the first SMR 23 (system main relay) associated with switching to the on state with a certain degree of accuracy.

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

In each of the above embodiments, the second SMR 24 does not have to be provided.

In each of the above embodiments, the first SMR 23 corresponds to an example of a system main relay, but the second SMR 24 may also be an example of a system main relay. In this case, the parallel circuit 25 is provided in parallel with the second SMR 24. In this case, the first SMR 23 does not need to be provided.

In each of the above embodiments, the start conditions are only the first condition and the second condition, but they may also include a third condition that is different from either of these. The third condition may be a condition that is met when the start switch is in an off state. When the start condition is met and the third condition is satisfied, the control unit 11 may set a period shorter than the second period (for example, the first period) as the precharge period.

In the second embodiment described above, the first period was the period until the value of the current flowing through the parallel circuit becomes equal to or less than the first threshold value, but it may also be the period until the potential difference between both ends of the first SMR 23 (system main relay) becomes equal to or less than the first threshold value. Also, the second period was the period until the value of the current flowing through the parallel circuit becomes equal to or less than the second threshold value, but it may also be the period until the potential difference between both ends of the first SMR 23 (system main relay) becomes equal to or less than the second threshold value.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, but is intended to include all modifications within the scope of the claims or within the scope equivalent to the claims.

10... Power supply control device 11... Control unit 20... Battery 21... Power path 22... Capacitor 23... First system main relay (system main relay)
24...Second system main relay 25...Parallel circuit 25A...Pre-charge relay 25B...Resistance section 26...Branch path 26A...Positive branch line 26B...Negative branch line 27...Load 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 section 41...Inverter 42...Motor 100...Vehicle T1...First time T2...Second time

Claims (5)

A power supply control device for use in a vehicle, the power supply control device comprising: a battery; a power path to which power based on the battery is supplied; a capacitor connected to the power path; a system main relay provided in the power path on the battery side of the capacitor; and a parallel circuit having a configuration in which a pre-charge relay and a resistor unit are connected in series and provided in parallel with the system main relay,
a control unit for controlling the system main relay and the precharge relay,
the control unit starts a first control for controlling the system main relay to an off state and the pre-charge relay to an on state when a start condition for starting charging/discharging of the battery is satisfied, and switches to a second control for controlling the system main relay to an on state and the pre-charge relay to an off state when a pre-charge period has elapsed since starting the first control,
Furthermore, the control unit sets a first period as the precharge period when a first condition is satisfied when the start condition is satisfied, and sets a second period longer than the first period as the precharge period when a second condition is satisfied when the start condition is satisfied. the first condition is that a starter switch of the vehicle is in an on state,
The power supply control device according to claim 1 , wherein one of the second conditions is that the start switch is in an off state. the first period is a period from when the start condition is satisfied until a first time has elapsed,
The power supply control device according to claim 1 or 2, wherein the second period is a period from when the start condition is satisfied until a second time longer than the first time has elapsed. the first period is a period until a value of a current flowing through the parallel circuit or a potential difference across the system main relay becomes equal to or less than a first threshold value,
3 . The power supply control device according to claim 1 , wherein the second period is a period until a value of a current flowing through the parallel circuit or a potential difference across the system main relay becomes equal to or less than a second threshold value that is smaller than the first threshold value. the first period is a period until the voltage of the capacitor becomes equal to or greater than a first threshold voltage,
3 . The power supply control device according to claim 1 , wherein the second period is a period until the voltage of the capacitor becomes equal to or higher than a second threshold voltage that is higher than the first threshold voltage. 4 .

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