Switch control device, program, and switch control method

Abstract

To prevent operation of an electric load from being stopped when diagnosing whether or not an ON failure of a switch occurs.SOLUTION: A power supply system comprises: a first power source 11 and a second power source 12 which are connected via an electric path 13; first to third loads 31 to 33 which are connected to the electric path 13 and to which power from the first power source 11 and the second power source 12 can be supplied; and a shut-off switch 40 which is provided between the second power source 12 and a node B of a second load 32 in the electric path 13. A control device 50 diagnoses an ON-on failure of the shut-off switch 40 in a state where the shut-off switch 40 is turned off. The control device 50 comprises: a determination section 52 which determines whether or not the first power source 11 is in a power output state where power is output to the electric path 13; and a command section 53 which temporarily outputs an OFF command to the shut-off switch 40 on a condition that it is determined that the first power source 11 is in the power output state when implementing the diagnosis of the shut-off switch 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a switch control device for a power supply system. , pu Program and switch control method Regarding. [Background technology]

[0002] Conventionally, there has been known a power supply system that includes a plurality of power sources and an electric load that can receive electric power from each of the power sources. For example, Patent Document 1 describes a technology in which an electric load is connected to an electric path that connects the plurality of power sources, and a switch is provided between a connection point between one of the power sources and the electric load, and a diagnosis is made as to whether an ON fault has occurred in which the switch is stuck in the ON state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-93694 Summary of the Invention [Problem to be solved by the invention]

[0004] When diagnosing whether a switch has an on-failure, the switch may be temporarily turned off. When the switch is temporarily turned off, the supply of drive power from the power supply connected to the electrical load via the switch is temporarily stopped. In this case, there is a concern that the operation of the electrical load may be stopped unintentionally.

[0005] The present invention provides a switch control device that can prevent the operation of an electric load from being stopped when diagnosing whether or not a switch ON failure has occurred. , pu Program and switch control method The main purpose is to provide. [Means for solving the problem]

[0006] The switch control device of the present invention comprises: a first power source and a second power source connected via an electrical path; an electrical load connected to the electrical path and capable of receiving power from the first power source and the second power source; a switch provided in the electrical path between the second power source and the connection point of the electrical load, and the switch is turned off to diagnose an on-failure of the switch, a determination unit that determines whether the first power source is in a power output state that outputs power to the electrical path; The power supply includes a command unit that outputs a temporary OFF command to the switch on condition that the first power supply is determined to be in the power output state when the diagnosis is performed.

[0007] In the above configuration, the switch is turned off and an on-failure of the switch is diagnosed. In this case, when the switch diagnosis is performed, the power supply from the second power source to the electric load is temporarily stopped, which may unintentionally stop the operation of the electric load.

[0008] According to the present invention, it is determined whether the first power source is in a power output state in which it outputs power to the electrical path, and when diagnosing the switch, a temporary OFF command is output to the switch on the condition that it is determined that the first power source is in a power output state. In this case, drive power for the electrical load is ensured while the switch is OFF. This makes it possible to prevent unintended power failure of the electrical load and to prevent the operation of the electrical load from being stopped. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the overall configuration of an in-vehicle power supply system according to a first embodiment. [Figure 2] 4 is a flowchart showing a control processing procedure executed by the control device. [Figure 3] 4 is a time chart showing an example of a control operation executed by the control device. [Figure 4] 6 is a time chart showing an example of a control operation according to a modified example of the first embodiment. [Figure 5] 6 is a time chart showing an example of a control operation according to a modified example of the first embodiment. [Figure 6] 6 is a flowchart showing a control procedure executed by a control device according to a modified example of the first embodiment. [Figure 7] FIG. 10 is a diagram showing the overall configuration of an in-vehicle power supply system according to a second embodiment. [Figure 8] 4 is a flowchart showing a control processing procedure executed by the control device. [Figure 9] FIG. 10 is a diagram showing the overall configuration of an in-vehicle power supply system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment A first embodiment of a switch control device according to the present invention will be described below with reference to the drawings. In this embodiment, the switch control device is applied to an on-board power supply system. The power supply system is installed in an electric vehicle that uses a motor as a driving power source.

[0011] As shown in Fig. 1, the power supply system has a first power supply 11 and a second power supply 12, which are connected to each other by an electrical path 13. The first power supply 11 includes a high-voltage battery 21, a rotating electric machine 22, and a DC-DC converter 23. The high-voltage battery 21 is configured as a series connection of a plurality of unit cells, and the rated voltage of the high-voltage battery 21 is, for example, several hundred volts. Each unit cell is a rechargeable storage battery, specifically a lithium-ion storage battery.

[0012] The rotating electric machine 22 is a power source for driving the vehicle, and receives power from the high-voltage battery 21 to transmit power to the drive wheels of the vehicle. The rotating electric machine 22 also functions as a generator that performs regenerative power generation while the vehicle is running. The rotating electric machine 22 has an inverter that controls the current of each phase, and the high-voltage battery 21 is connected to the inverter. This allows current to flow between the high-voltage battery 21 and the rotating electric machine 22. The DC-DC converter 23 is connected to the high-voltage battery 21 and reduces the high voltage on the high-voltage battery 21 side. For example, the DC-DC converter 23 reduces the high voltage on the high-voltage battery 21 side to a voltage of 12V to 14V.

[0013] The second power supply 12 is configured by a low-voltage battery. The low-voltage battery has a rated voltage of, for example, 12 V, lower than that of the high-voltage battery 21. The low-voltage battery is a rechargeable storage battery, such as a lead storage battery or a lithium-ion storage battery.

[0014] The power supply system includes a first load 31, a second load 32, and a third load 33. Each of the loads 31 to 33 can be supplied with power from the first power source 11 and the second power source 12. Each of the loads 31 to 33 is connected to connection points A, B, and C of an electrical path 13. The positive electrode side of each of the loads 31 to 33 is connected to the electrical path 13, and the negative electrode side is connected to a grounded portion of the vehicle body or the like.

[0015] The first to third loads 31 to 33 include, for example, various ECUs. The ECU has a built-in memory for storing processed information, and the memory holds information processed in the previous trip of the vehicle. Therefore, the first to third loads 31 to 33 require the supply of dark current to hold the stored information for a long period of time. In addition to ECUs, the first to third loads 31 to 33 may be electrical loads that require the supply of dark current to continue at least some of their functions for a long period of time, and specifically may be navigation devices, anti-theft devices, lighting equipment, etc. Note that each of the loads 31 to 33 shown in FIG. 1 may be a single electrical load or multiple electrical loads.

[0016] Note that the loads 31 to 33 may be other electrical loads. For example, the loads 31 to 33 may be electrical loads used for vehicle driving assistance control, specifically, an electric power steering device that generates an assist torque to assist the driver's steering, an electric brake device that applies braking force to the wheels, a camera for monitoring the conditions around the vehicle, a laser radar such as LIDAR (Laser Imaging Detection and Ranging), a millimeter-wave radar, a by-wire system, or the like. Furthermore, for example, the loads 31 to 33 may be general electrical loads, specifically, an air conditioner, an audio device, a power window, an electric fan of a radiator that cools the engine coolant, a stop lamp, an interior light, a USB power socket, and a motor that drives a mirror provided outside the vehicle compartment.

[0017] The power supply system includes a cutoff switch 40. The cutoff switch 40 is a normally closed switch, and is configured, for example, by a relay or a semiconductor switch such as a MOSFET. The cutoff switch 40 is provided in the electrical path 13 between the connection point B of the second load 32 and the connection point C of the third load 33.

[0018] The power supply system includes a control device 50, a voltage sensor 60 and a current sensor 61 provided on the first power supply 11 side of the cutoff switch 40, a voltage sensor 62 and a current sensor 63 provided on the second power supply 12 side of the cutoff switch 40, and a switch current sensor 64. Each of the voltage sensors 60, 62 detects the voltage of the electrical path 13. The current sensor 61 on the first power supply 11 side detects the output current of the first power supply 11. The current sensor 63 on the second power supply 12 side detects the output current of the second power supply 12. The switch current sensor 64 detects the current flowing through the cutoff switch 40. Each of the current sensors 61, 63, 64 detects the current using, for example, a shunt resistor or a Hall element. The control device 50 acquires the detection values of each of the sensors 60 to 64.

[0019] The control device 50 is mainly composed of a microcomputer having a CPU and various memories. The functions provided by the control device 50 can be provided by software recorded in a physical memory device and a computer that executes the software, software only, hardware only, or a combination of these.

[0020] For example, the control device 50 controls the output voltage of the DCDC converter 23 so that the terminal voltage or SOC of the low-voltage battery included in the second power source 12 falls within a predetermined range. When charging the low-voltage battery, the control device 50 controls the output voltage of the DCDC converter 23 to be higher than the rated voltage of the low-voltage battery, and when discharging the low-voltage battery, the control device 50 controls the output voltage of the DCDC converter 23 to be lower than the rated voltage of the low-voltage battery. For example, the control device 50 determines the terminal voltage or SOC of the low-voltage battery included in the second power source 12 based on the detection values of the sensors 62, 63 on the second power source 12 side.

[0021] For example, the control device 50 determines whether an overcurrent abnormality, in which an excessive current flows, has occurred in the electrical path 13, based on the current flowing through the cutoff switch 40, and turns off the cutoff switch 40 if it determines that an overcurrent abnormality has occurred. This prevents an overcurrent from flowing through the electrical path 13. Note that an overcurrent abnormality occurs due to a ground fault in which any point on the electrical path 13 is short-circuited to a grounded location, or due to a runaway electrical load. For example, the control device 50 uses the detection value of the switch current sensor 64 as the current flowing through the cutoff switch 40.

[0022] The control device 50 includes a diagnostic unit 51. The diagnostic unit 51 turns off the cutoff switch 40 and diagnoses whether an on-failure has occurred, in which the cutoff switch 40 is stuck in the on state. For example, the diagnostic unit 51 diagnoses the cutoff switch 40 based on the detection value of the switch current sensor 64 and the detection value of the voltage sensor 62 on the second power source 12 side.

[0023] Incidentally, when the cutoff switch 40 is diagnosed, if the cutoff switch 40 is temporarily turned off, the supply of drive power from the second power source 12 to the first and second loads 31 and 32 is temporarily stopped. In this case, for example, if the power output of the DC-DC converter 23 is stopped, the power supply from the first power source 11 to the first and second loads 31 and 32 may become insufficient, and there is a concern that the operation of the first and second loads 31 and 32 may be stopped unintentionally.

[0024] Therefore, the control device 50 includes a determination unit 52 and a command unit 53. The determination unit 52 determines whether the first power source 11 is in a power output state in which it outputs power to the electrical path 13. When diagnosing the cutoff switch 40, the command unit 53 outputs a temporary OFF command to the cutoff switch 40 on the condition that it is determined that the first power source 11 is in a power output state.

[0025] 2 shows the procedure of the control executed by the control device 50. This control is triggered by the activation of a start switch. The start switch is, for example, an ignition switch or a push-button start switch, and is operated by the vehicle user.

[0026] Here, it is assumed that immediately after the start switch is turned on, the operation of the DC-DC converter 23 is stopped and the second power supply 12 is supplying drive power to the loads 31 to 33.

[0027] In step S10, the path voltage of the electrical path 13 is acquired. Then, the acquired path voltage is stored in a memory included in the control device 50. In this case, since the operation of the DC-DC converter 23 is stopped immediately after the start switch is turned on, the path voltage of the electrical path 13 has a value corresponding to the output voltage of the second power supply 12.

[0028] In step S11, a power output command for the DC-DC converter 23 is output so that the output voltage of the DC-DC converter 23 becomes higher than the output voltage of the second power supply 12. Specifically, the power output command for the DC-DC converter 23 is a drive command for a switch included in the DC-DC converter 23.

[0029] In step S12, the path voltage of the electrical path 13 after the output of the power output command is acquired. In this case, the path voltage of the electrical path 13 is a value corresponding to the output voltage of the DC-DC converter 23. In the processing of steps S10 and S12, at least one of the detection value of the voltage sensor 60 on the first power source 11 side and the detection value of the voltage sensor 62 on the second power source 12 side can be used as the path voltage of the electrical path 13.

[0030] In step S13, it is determined whether the first power source 11 is in a power output state. In this embodiment, it is determined whether the path voltage of the electrical path 13 has increased after the output of the power output command. Specifically, it is determined whether the voltage increase value obtained by subtracting the path voltage acquired in the processing of step S10 (i.e., the voltage stored in memory) from the path voltage acquired in the processing of step S12 is higher than a predetermined threshold value. The threshold value is a value higher than 0 V. If the determination in step S13 is positive, the process proceeds to step S14. If the determination in step S13 is negative, the process proceeds to step S18.

[0031] In step S14, an OFF command is output to turn off the cutoff switch 40 for a predetermined period of time.

[0032] In step S15, while an OFF command is being output to the cutoff switch 40, the path voltage on the second power source 12 side of the electrical path 13 is acquired. The path voltage on the second power source 12 side of the electrical path 13 can be the detected value of the voltage sensor 62 on the second power source 12 side. The diagnosis unit 51 executes the process of step S15 while the OFF command is being output to the cutoff switch 40.

[0033] In step S16, it is determined whether or not there is an on-failure of the cutoff switch 40 based on the path voltage on the second power source 12 side of the electrical path 13. If it is determined in step S16 that there is no on-failure of the cutoff switch 40, the process proceeds to step S17. On the other hand, if it is determined in step S16 that there is an on-failure of the cutoff switch 40, the process proceeds to step S18.

[0034] For example, if an on-failure of the cutoff switch 40 does not occur, when an off command for the cutoff switch 40 is output, the cutoff switch 40 is actually turned off, and the path voltage on the second power source 12 side of the electrical path 13 is considered to return to the value before the power output command was output. Therefore, if the absolute value of the difference between the path voltage acquired in step S15 and the path voltage acquired in the processing of step S10 is equal to or less than a predetermined judgment value, it is determined that an on-failure of the cutoff switch 40 does not occur. On the other hand, if an on-failure of the cutoff switch 40 occurs, even if an off command for the cutoff switch 40 is output, the cutoff switch 40 is not actually turned off, and the path voltage on the second power source 12 side of the electrical path 13 is considered to remain the same as after the power output command was output. Therefore, the diagnosing unit 51 determines that an on-failure of the cutoff switch 40 occurs when the absolute value of the difference in the path voltages described above exceeds the judgment value. Here, the judgment value is, for example, a positive value close to 0.

[0035] The method of determining whether or not an on-fault has occurred in the shutoff switch 40 is not limited to the above. For example, the current flowing through the shutoff switch 40 may be acquired, and the presence or absence of an on-fault of the shutoff switch 40 may be determined based on the acquired value. In this case, if the current flowing through the shutoff switch 40 in the off state is smaller than the determination value, it is determined that an on-fault of the shutoff switch 40 has not occurred. On the other hand, if the current flowing through the shutoff switch 40 in the off state is equal to or greater than the determination value, it is determined that an on-fault of the shutoff switch 40 has occurred. Here, the determination value is, for example, a value greater than 0. The current flowing through the shutoff switch 40 can be determined using the detection value of the switch current sensor 64.

[0036] In steps S17 and S18, a flag is set. For example, the flag is transmitted to a higher-level control device for the control device 50 and is used to set whether or not to transition to the autonomous driving mode. Specifically, when the flag is off, transition to the autonomous driving mode is permitted, and when the flag is on, transition to the autonomous driving mode is prohibited. In step S17, the flag is set to off. On the other hand, in step S18, the flag is set to on.

[0037] If the flag is on, the higher-level control device may perform processing to notify the user that an on-failure has occurred in the cutoff switch 40.

[0038] Figure 3 shows an example of control executed by the control device 50. The operation example shown in Figure 3 is an operation example when no on-failure occurs in the cutoff switch 40. In Figure 3, (a) shows the transition of voltage V2 on the second power source 12 side of the cutoff switch 40 in the electrical path 13, (b) shows the transition of voltage V1 on the first power source 11 side of the cutoff switch 40 in the electrical path 13, and (c) shows the on / off of the cutoff switch 40. In Figure 3, it is assumed that no power output is occurring from the first power source 11 before time t1.

[0039] At time t1, the control device 50 acquires the path voltage of the electrical path 13 and stores the acquired voltage value Va in memory. At time t2, the control device 50 outputs a power output command for the DC-DC converter 23. This causes the voltage V1 on the first power source 11 side and the voltage V2 on the second power source 12 side to increase.

[0040] At time t3, the control device 50 acquires the path voltage of the electrical path 13 after the output of the power output command, and determines that the voltage increase value obtained by subtracting the voltage value Va stored in memory from the acquired voltage value is higher than the threshold value. In response to this, the control device 50 outputs an OFF command for the cutoff switch 40. This turns off the cutoff switch 40, and the voltage V2 on the second power source 12 side returns to the value before the output of the power output command. While the OFF command for the cutoff switch 40 is being output, the control device 50 acquires the detection value of the voltage sensor 62 on the second power source 12 side. Based on the acquired detection value of the voltage sensor 62 on the second power source 12 side, the control device 50 determines whether or not there is an ON fault in the cutoff switch 40, and sets a fault flag according to the determination result.

[0041] According to the present embodiment described above in detail, the following effects can be obtained.

[0042] It is determined whether the first power source 11 is in a power output state in which it outputs power to the electrical path 13, and when diagnosing the cutoff switch 40, on the condition that it is determined that the first power source 11 is in a power output state, an OFF command is temporarily output to the cutoff switch 40. In this case, drive power for the first load 31 and the second load 32 is ensured while the cutoff switch 40 is turned off. This makes it possible to prevent unintended power failures of the first load 31 and the second load 32, and to prevent the operation of the first load 31 and the second load 32 from being stopped.

[0043] Whether or not the first power supply 11 is in a power output state is determined based on the path voltage of the electrical path 13. Specifically, if the path voltage of the electrical path 13 increases after the output of a power output command, it is determined that the first power supply 11 is in a power output state. This makes it possible to accurately determine that the first power supply 11 is in a power output state.

[0044] <Modification of the first embodiment> In the process of step S13 in Fig. 2, the method of determining whether the first power source 11 is in a power output state may be changed. Here, a determination method using the output current of the first power source 11 will be described.

[0045] In step S13, the output current of the first power supply 11 is acquired, and if it is determined that the output current of the first power supply 11 exceeds a predetermined threshold current Ith1, it is determined that the first power supply 11 is in a power output state. The output current of the first power supply 11 can be the detection value of the current sensor 61 on the first power supply 11 side. On the other hand, if it is determined that the output current of the first power supply 11 is equal to or less than the threshold current Ith1, it is determined that the first power supply 11 is not in a power output state. For example, the threshold current Ith1 is a value greater than 0.

[0046] Fig. 4 shows an example of the control operation executed by the control device 50 according to this embodiment. Fig. 4(b) shows the transition of the output current I1 of the first power supply 11. Note that Figs. 4(a) and (c) correspond to Figs. 3(b) and (c) above.

[0047] At time t1, the control device 50 outputs a power output command for the DC-DC converter 23. As a result, the voltage V1 on the first power source 11 side of the cutoff switch 40 in the electrical path 13 and the output current I1 of the first power source 11 increase. At time t2, the control device 50 determines that the output current of the first power source 11 exceeds the threshold current Ith1. Accordingly, the control device 50 outputs an OFF command for the cutoff switch 40. As a result, the cutoff switch 40 is turned OFF.

[0048] The current flowing through the second power supply 12 may be used to diagnose the cutoff switch 40 .

[0049] In step S13, the current flowing through the second power source 12 is acquired. Here, the current flowing through the second power source 12 is acquired by defining a current flowing in a direction in which the low-voltage battery of the second power source 12 is charged as positive and a current flowing in a direction in which the low-voltage battery of the second power source 12 is discharged as negative. If it is determined that the current flowing through the second power source 12 exceeds a predetermined threshold current Ith2, it is determined that the first power source 11 is in a power output state. The threshold current Ith2 is set to, for example, a value equal to or greater than 0. In other words, the threshold current Ith2 is set to a value that allows determination that a current is flowing through the electrical path 13 from the first power source 11 to the second power source 12. The detection value of the current sensor 63 on the second power source 12 side is used as the current flowing through the second power source 12.

[0050] Fig. 5 shows an example of the control operation executed by the control device 50 according to this embodiment. Fig. 5(b) shows the transition of the current I2 flowing through the second power supply 12. Note that Figs. 5(a) and (c) correspond to Figs. 4(a) and (c) above.

[0051] At time t1, the control device 50 outputs a power output command for the DC-DC converter 23. As a result, the voltage V1 on the first power source 11 side of the cutoff switch 40 in the electrical path 13 and the current I2 flowing through the second power source 12 increase. At time t2, the control device 50 determines that the current flowing through the second power source 12 exceeds the threshold current Ith2. Accordingly, the control device 50 outputs an OFF command for the cutoff switch 40. As a result, the cutoff switch 40 is turned off.

[0052] According to this embodiment, the detection value of the current sensor 63 on the second power source 12 side is used to determine whether the first power source 11 is in a power output state. The detection value of the current sensor 63 on the second power source 12 side is also used to determine, for example, the SOC of a low-voltage battery included in the second power source 12. In this case, it is possible to perform diagnosis of the cutoff switch 40 while suppressing an increase in the number of sensors provided in the power supply system.

[0053] The current flowing through the cutoff switch 40 may be used to diagnose the cutoff switch 40. In this case, in step S13, the same process as the above-described diagnosis of the cutoff switch 40 using the current flowing through the second power source 12 is executed. The value detected by the switch current sensor 64 can be used as the current flowing through the cutoff switch 40. Note that, if the previous FIG. 5(b) shows the transition of the current flowing through the cutoff switch 40, an example of the control operation executed by the control device 50 according to this embodiment is the same as that shown in FIG. 5.

[0054] According to this embodiment, the detection value of the switch current sensor 64 is used to determine whether the first power supply 11 is in a power output state. The detection value of the switch current sensor 64 is also used to detect, for example, an overcurrent abnormality. In this case, it is possible to perform diagnosis of the cutoff switch 40 while suppressing an increase in the number of sensors provided in the power supply system.

[0055] In the process of step S13 in Fig. 2, if the path voltage of the electrical path 13 exceeds a predetermined threshold voltage, it may be determined that the first power source 11 is in a power output state. In this case, the process of step S10 does not need to be executed. Note that the threshold voltage is, for example, a value higher than the rated voltage of the low-voltage battery of the second power source 12.

[0056] In the process of step S13 in FIG. 2, it may be possible to determine whether the first power source 11 is in a power output state using at least two of the path voltage of the electrical path 13, the output current of the first power source 11, the current flowing in the second power source 12, and the current flowing in the cutoff switch 40.

[0057] 2, if it is determined that a power output command for the DC-DC converter 23 is being output, it may be determined that the first power source 11 is in a power output state. In this case, the processes of steps S10 and S12 may not be executed.

[0058] In this embodiment, the control device 50 executes the control shown in Fig. 6. This control is executed at predetermined intervals instead of when the start switch is turned on. Here, it is assumed that the vehicle is running and the shut-off switch 40 is diagnosed while the DC-DC converter 23 is operating. In Fig. 6, the same steps as those shown in Fig. 2 are denoted by the same step numbers for convenience.

[0059] In this embodiment, instead of executing the processes of steps S10 to S12 in Fig. 2, the process of step S20 is executed as shown in Fig. 6. In step S20, the magnitude of the power output of the first power source 11 is changed according to the power required by the first and second loads 31 and 32 connected to the first power source 11 side of the cutoff switch 40 in the electrical path 13. Specifically, the higher the power required by the first and second loads 31 and 32, the higher the set value of the output voltage of the DC-DC converter 23 is set. The process of step S20 corresponds to a "power adjustment unit."

[0060] In step S13, at least one of the output current of the first power source 11, the current flowing through the second power source 12, and the current flowing through the cutoff switch 40 is used to determine whether the first power source 11 is in a power output state.

[0061] According to this embodiment, the greater the power required by the first and second loads 31, 32, the higher the set value of the output voltage of the DC-DC converter 23. This makes it possible to supply drive power from the first power source 11 to the first and second loads 31, 32 even if the power required by the first and second loads 31, 32 increases. Therefore, during the diagnosis of the cutoff switch 40, it is possible to reliably prevent the supply of drive power from the first power source 11 to the first and second loads 31, 32 from being insufficient.

[0062] In the process of step S13 in FIG. 2, the determination condition for determining whether the first power source 11 is in a power output state may be changed.

[0063] It is conceivable that the power requirements of at least one of the first load 31 and the second load 32 may change on the first power source 11 side of the cutoff switch 40 in the electrical path 13, and in order to ensure the operation of the first load 31 and the second load 32, it is desirable to set judgment conditions that take into account changes in the power requirements and determine whether or not to supply power from the first power source 11 to the first load 31 and the second load 32. Furthermore, if the judgment conditions are too narrow, there is a concern that the number of opportunities to diagnose the cutoff switch 40 may be unnecessarily reduced.

[0064] Therefore, the judgment unit 52 changes the judgment conditions for determining whether the first power source 11 is in a power output state depending on the required power of the first load 31 and the second load 32, which are connected on the electrical path 13 closer to the first power source 11 than the cut-off switch 40.

[0065] 2, the higher the required power of at least one of the first load 31 and the second load 32, the higher the output power of the first power source 11. For example, when the power output state is determined using the voltage increase value before and after the power output command of the DC-DC converter 23 is output, the higher the total required power of the loads 31 and 32, the higher the threshold value used for the determination is set.

[0066] According to this embodiment, the condition for determining whether the first power source 11 is in a power output state is changed in accordance with at least one of the power requirements of the loads 31 and 32. This makes it possible to realize appropriate fault diagnosis while taking into account changes in the power requirements of the loads 31 and 32.

[0067] The electrical path 13 may be configured without the third load 33 .

[0068] Second Embodiment In this embodiment, when the diagnosis of the cutoff switch 40 is performed, the supply of current to the second load 32 is limited.

[0069] In the present embodiment, the first load 31 is a load for which continued operation is prioritized over the second load 32 in diagnosing the cutoff switch 40. For example, the first load 31 is an electrical load that requires at least some functions, such as an ECU, to continue for a long period of time, and the second load 32 is a general electrical load. In this case, there is a concern that the power supply to the first load 31 may be insufficient due to the second load 32 being in operation when diagnosing the cutoff switch 40. In view of this, in the present embodiment, the supply of current to the second load 32 is limited when diagnosing the cutoff switch 40.

[0070] As shown in FIG. 7, the power supply system includes a load switch 41. The load switch 41 is a normally closed switch, and is configured, for example, by a semiconductor switch such as a relay or a MOSFET. The load switch 41 is provided in an electrical path connecting a connection point B of the second load 32 and the positive electrode side of the second load 32. The control device 50 limits the supply of current to the second load 32 by turning off the load switch 41 before outputting an OFF command to the cutoff switch 40. Note that in FIG. 7, components that overlap with those in FIG. 1 are denoted by the same reference numerals and some are not shown for convenience.

[0071] The power supply system includes a load current sensor 65 that detects the current flowing through the load switch 41. The load current sensor 65 detects the current using, for example, a shunt resistor or a Hall element.

[0072] The command unit 53 does not output an OFF command to the cutoff switch 40 when it is not possible to limit the supply of current to the second load 32. For example, the command unit 53 acquires the current flowing through the load switch 41 in the OFF state, and when the acquired current value is equal to or greater than a predetermined value, it determines that it is not possible to limit the supply of current to the second load 32 and does not output an OFF command to the cutoff switch 40. The detection value of the load current sensor 65 can be used as the current flowing through the load switch 41. Note that a situation in which it is not possible to limit the supply of current to the second load 32 may be a situation in which an ON fault occurs in the load switch 41.

[0073] As shown in FIG. 8, in step S30, it is determined whether or not limiting the supply of current to the second load 32 is possible. If a negative determination is made in step S30, the process proceeds to step S31. In step S31, when diagnosing the cutoff switch 40, the load switch 41 is turned off to limit the supply of current to the second load 32 before an OFF command is output for the cutoff switch 40. On the other hand, if a positive determination is made in step S30, the process proceeds to step S18. In other words, if it is determined that limiting the supply of current to the second load 32 is not possible, an OFF command for the cutoff switch 40 is not output. The process of step S31 corresponds to the "current limiting unit." In FIG. 8, the same processes as those shown in FIG. 2 above are denoted by the same step numbers for convenience.

[0074] When actually diagnosing the cutoff switch 40, the supply of current to the second load 32 is limited, so that while the cutoff switch 40 is turned off, the supply of drive power from the first power source 11 to the first load 31 takes priority over the supply of drive power to the second load 32. As a result, it is possible to reliably prevent the supply of drive power to the first load 31 from becoming insufficient.

[0075] When diagnosing the cutoff switch 40, if it is determined that it is not possible to limit the power supply to the second load 32, an OFF command for the cutoff switch 40 is not output. This makes it possible to avoid diagnosing the cutoff switch 40 in a situation where there is a concern that the supply of drive power to the first load 31 may be insufficient.

[0076] <Modification of the second embodiment> In step S31 of FIG. 8, instead of turning off the load switch 41, the power supply to the second load 32 may be limited by stopping the operation of the second load 32 or reducing the power required by the second load 32.

[0077] 8, the power supply to the second load 32 is limited in accordance with the power requirements of the loads 31, 32 connected on the electrical path 13 closer to the first power source 11 than the cutoff switch 40. For example, when the total power requirement of the loads 31, 32 is equal to or greater than a predetermined power, the power supply to the second load 32 is limited, and when the total power requirement is less than the predetermined power, the power supply to the second load 32 is not limited. According to this embodiment, in a situation where there is little possibility of a shortage of power supply to the first load 31, it is possible to prevent the function of the second load 32 from being unnecessarily limited.

[0078] The process of step S30 in FIG. 8 does not need to be performed.

[0079] Third Embodiment In this embodiment, the configuration of the power supply system is changed from that of the first embodiment. In this embodiment, as shown in Fig. 9, cutoff switches 40 are provided at a plurality of positions on the electrical path 13 between the connection points of the loads 31 to 33. That is, a position in the electrical path 13 between the connection points A and B of the loads 31 and 32; a position in the electrical path 13 between the connection points B and C of the loads 32 and 33; 9, the cutoff switch 40 provided between connection points A and B in the electrical path 13 is referred to as the "cutoff switch 40a," and the cutoff switch 40 provided between connection points B and C in the electrical path 13 is referred to as the "cutoff switch 40b." Note that in FIG. 9, configurations that overlap with those in FIG. 1 are denoted by the same reference numerals and some are not shown for convenience.

[0080] The command unit 53 temporarily outputs an OFF command to the plurality of cutoff switches 40a, 40b provided in the electrical path 13. In this embodiment, when diagnosing each of the cutoff switches 40a, 40b, the command unit 53 outputs an OFF command to each of the cutoff switches 40a, 40b provided in the electrical path 13, one by one, as a target to be turned off. For example, the command unit 53 outputs an OFF command to the cutoff switch 40a as a target to be turned off, and after diagnosing the cutoff switch 40a, outputs an OFF command to the cutoff switch 40b as a target to be turned off.

[0081] In the above configuration, the first load 31 is connected to the first power source 11 side of the electrical path 13 relative to the cutoff switch 40a, and the first and second loads 31, 32 are connected to the first power source 11 side of the electrical path 13 relative to the cutoff switch 40b. In this case, when the cutoff switch 40b is turned off, it is considered that there is a higher possibility that the supply of drive power from the first power source 11 to the first and second loads 31, 32 will be insufficient compared to when the cutoff switch 40a is turned off, due to the greater number of electrical loads connected to the first power source 11 side of the electrical path 13.

[0082] Therefore, the judgment unit 52 changes the judgment conditions for whether the first power source 11 is in a power output state depending on the number of electrical loads connected in the electrical path 13 to the side of the first power source 11 relative to the shut-off switch 40 that is to be turned off by the command unit 53.

[0083] Specifically, when the cutoff switch 40b is to be turned off, the determination unit 52 changes the determination condition to one that results in a higher output power from the first power source 11 compared to when the cutoff switch 40a is to be turned off. For example, when determining the power output state using the voltage increase value before and after the power output command of the DC-DC converter 23 is output, the determination unit 52 sets a higher threshold value to be used for determination as the number of electrical loads connected on the electrical path 13 to the first power source 11 side of the cutoff switch 40 to be turned off increases.

[0084] According to this embodiment, the condition for determining whether the first power source 11 is in a power output state is changed according to the number of electrical loads connected to the first power source 11 side of the cutoff switches 40a, 40b in the electrical path 13. This makes it possible to realize appropriate fault diagnosis while taking into account that the power required by the electrical loads changes as the number of electrical loads changes.

[0085] <Other embodiments> The above-described embodiments may be modified as follows.

[0086] The configuration of the first power source 11 may be changed. For example, the first power source 11 may be a rechargeable storage battery.

[0087] The cutoff switch 40 and the load switch 41 do not have to be normally closed switches.

[0088] The power supply system may be installed in a vehicle other than a vehicle, or may be installed in a moving object other than a vehicle. The power supply system may also be stationary.

[0089] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0090] The technical ideas extracted from the above-described embodiments will be described below. [Configuration 1] a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, and the switch is turned off to diagnose an on-failure of the switch, a determination unit that determines whether the first power source is in a power output state that outputs power to the electrical path; a command unit that outputs a temporary OFF command to the switch on condition that the first power source is determined to be in the power output state when the diagnosis is performed, and [Configuration 2] The switch control device according to configuration 1, wherein the determination unit determines whether the first power source is in the power output state based on at least one of a path voltage of the electrical path, an output current of the first power source, and a direction of the current flowing through the electrical path. [Configuration 3] The switch control device according to configuration 1 or 2, wherein the determination unit changes a determination condition for determining whether the first power source is in the power output state in accordance with a power requirement of the electrical load connected to the first power source side of the switch in the electrical path. [Configuration 4] a plurality of the electric loads are connected to the electric path, and the switches (40a, 40b) are provided at a plurality of positions between connection points of the electric loads, the command unit outputs an OFF command to turn off each of the plurality of switches provided in the electrical path when the diagnosis is performed, The switch control device according to any one of configurations 1 to 3, wherein the determination unit changes a determination condition for determining whether the first power source is in the power output state depending on the number of electrical loads connected in the electrical path on the side of the first power source relative to the switch to be turned off by the command unit. [Configuration 5] The switch control device according to any one of configurations 1 to 4, further comprising a current limiting unit that limits current flow to the electrical load connected to the first power source side of the switch in the electrical path before the command unit outputs an OFF command to turn off the switch when the diagnosis is performed. [Configuration 6] 6. The switch control device according to claim 5, wherein the current limiting unit limits current flow to the electrical load in accordance with a power requirement of the electrical load connected to a side of the first power source relative to the switch in the electrical path. [Configuration 7] 7. The switch control device according to configuration 5 or 6, wherein the command unit does not output an OFF command to the switch when the current flow limiting unit is unable to limit the current flow. [Configuration 8] the first power source is configured to be able to adjust the magnitude of the power output to the electrical path; The switch control device according to any one of configurations 1 to 7, further comprising a power adjustment unit that, when the diagnosis is performed, changes the magnitude of the power output of the first power source in accordance with the power required by the electrical load that is connected on the first power source side of the switch in the electrical path. [Explanation of symbols]

[0091] 11...first power source, 12...second power source, 31-33...first to third loads, 40...shutoff switch, 50...control device.

Claims

1. a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, and the switch is turned off to diagnose an on-failure of the switch, a determination unit that determines whether the first power source is in a power output state that outputs power to the electrical path; a command unit that temporarily outputs an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed, The determination unit changes the determination condition for determining whether the first power source is in the power output state according to the power required by the electrical load connected to the first power source side of the switch in the electrical path.

2. a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, and the switch is turned off to diagnose an on-failure of the switch, a determination unit that determines whether the first power source is in a power output state that outputs power to the electrical path; a command unit that temporarily outputs an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed, a plurality of the electric loads are connected to the electric path, and the switches (40 a, 40 b) are provided at a plurality of positions between connection points of the electric loads, the command unit outputs an OFF command to turn off each of the plurality of switches provided in the electrical path when the diagnosis is performed, The determination unit changes the determination condition for determining whether the first power source is in the power output state depending on the number of electrical loads connected in the electrical path on the side of the first power source relative to the switch to be turned off by the command unit.

3. a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, and the switch is turned off to diagnose an on-failure of the switch, a determination unit that determines whether the first power source is in a power output state that outputs power to the electrical path; a command unit that temporarily outputs an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed; a current limiting unit that, when performing the diagnosis, limits the flow of current to the electrical load that is connected on the first power source side of the switch in the electrical path before the command unit outputs an off command to the switch.

4. The switch control device according to any one of claims 1 to 3, wherein the determination unit determines whether the first power source is in the power output state based on at least one of a path voltage of the electrical path, an output current of the first power source, and a direction of the current flowing in the electrical path.

5. The switch control device according to claim 3 , wherein the current limiting unit limits current flow to the electrical load in accordance with a power requirement of the electrical load connected to a side of the first power source relative to the switch in the electrical path.

6. The switch control device according to claim 3 , wherein the command unit does not output an OFF command for the switch when the current flow limiting unit is unable to limit the current flow.

7. the first power source is configured to be able to adjust the magnitude of the power output to the electrical path; The switch control device according to any one of claims 1 to 3, further comprising a power adjustment unit that changes the magnitude of the power output of the first power source according to the power required by the electrical load connected to the first power source side of the switch in the electrical path when the diagnosis is performed.

8. a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, the switch being turned off to diagnose an on-failure of the switch, the program being executed by a computer (50), a determining step of determining whether the first power source is in a power output state in which it outputs power to the electrical path; a command step of temporarily outputting an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed; In the determination step, the program changes the determination condition for whether the first power source is in the power output state in accordance with the power required by the electrical load connected to the first power source side of the switch in the electrical path.

9. a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, the switch being turned off to diagnose an on-failure of the switch, the program being executed by a computer (50), a determining step of determining whether the first power source is in a power output state in which it outputs power to the electrical path; a command step of temporarily outputting an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed; a plurality of the electric loads are connected to the electric path, and the switches (40 a, 40 b) are provided at a plurality of positions between connection points of the electric loads, In the command step, when the diagnosis is performed, an OFF command is output to each of the plurality of switches provided in the electrical path as an OFF target, In the determination step, the program changes the determination condition for whether the first power source is in the power output state depending on the number of electrical loads connected in the electrical path on the side of the first power source relative to the switch to be turned off in the command step.

10. a first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, the switch being turned off to diagnose an on-failure of the switch, the program being executed by a computer (50), a determining step of determining whether the first power source is in a power output state in which it outputs power to the electrical path; a command step of temporarily outputting an OFF command to the switch on condition that it is determined that the first power source is in the power output state during the diagnosis; a current limiting step of limiting current flow to the electrical load connected on the first power source side of the switch in the electrical path before outputting an OFF command for the switch in the command step when the diagnosis is performed.

11. A first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, the switch being turned off to diagnose an on-failure of the switch, a determining step of determining whether the first power source is in a power output state in which it outputs power to the electrical path; a command step of temporarily outputting an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed, In the determination step, a condition for determining whether the first power source is in the power output state is changed according to the power required by the electrical load connected to the first power source side of the switch in the electrical path.

12. A first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, the switch being turned off to diagnose an on-failure of the switch, a determining step of determining whether the first power source is in a power output state in which it outputs power to the electrical path; a command step of temporarily outputting an OFF command to the switch on condition that it is determined that the first power source is in the power output state when the diagnosis is performed, a plurality of the electric loads are connected to the electric path, and the switches (40 a, 40 b) are provided at a plurality of positions between connection points of the electric loads, In the command step, when the diagnosis is performed, an OFF command is output to each of the plurality of switches provided in the electrical path as an OFF target, In the determination step, a condition for determining whether the first power source is in the power output state is changed depending on the number of electrical loads connected in the electrical path on the side of the first power source relative to the switch to be turned off in the command step.

13. A first power source (11) and a second power source (12) connected via an electrical path (13); an electric load (31 to 33) connected to the electric path and capable of receiving electric power from the first power source and the second power source; a switch (40) provided in the electrical path between the second power source and the connection point of the electrical load, the switch being turned off to diagnose an on-failure of the switch, a determining step of determining whether the first power source is in a power output state in which it outputs power to the electrical path; a command step of temporarily outputting an OFF command to the switch on condition that it is determined that the first power source is in the power output state during the diagnosis; a current limiting step of limiting current flow to the electrical load connected on the first power source side of the switch in the electrical path before outputting an OFF command for the switch in the command step when the diagnosis is performed.

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