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 and a program. [Background technology]

[0002] Conventionally, there is known a power supply system including a plurality of power sources and an electric load to which electric power can be supplied 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 connecting the plurality of power sources, a switch is provided between a connection point between one of the power sources and the electric load, and whether or not an ON fault occurs in which the switch is stuck in the ON state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-93694 A Summary of the Invention [Problem to be solved by the invention]

[0004] When diagnosing whether or not a switch ON failure has occurred, the switch may be temporarily turned off. When the switch is temporarily turned off, the supply of drive power from a power source connected to an electric load via the switch is temporarily stopped. In this case, there is a concern that the operation of the electric load may be stopped unintentionally.

[0005] The main object of the present invention is to provide a switch control device and program that can prevent the operation of an electrical load from being stopped when diagnosing whether or not a switch-on failure has occurred. [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 electrical 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 for outputting power to the electrical path; The power supply device further includes 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 during the execution of the diagnosis.

[0007] In the above configuration, the switch is turned off to diagnose an on-failure of the switch. In this case, when diagnosing the switch, the power supply from the second power source to the electric load is temporarily stopped, which may cause the operation of the electric load to be stopped unintentionally.

[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 the switch is diagnosed, an off command is temporarily 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, the driving power of the electrical load is secured while the switch is off. This makes it possible to prevent unintentional power failure of the electrical load and to prevent the operation of the electrical load from being stopped. [Brief description of the drawings]

[0009] [Figure 1] 1 is an overall configuration diagram of an on-board power supply system according to a first embodiment. [Diagram 2] 4 is a flowchart showing a control process executed by the control device. [Diagram 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. [Diagram 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 process executed by a control device according to a modified example of the first embodiment. [Figure 7] FIG. 11 is an overall configuration diagram of an on-board power supply system according to a second embodiment. [Figure 8] 4 is a flowchart showing a control process executed by the control device. [Figure 9] FIG. 11 is an overall configuration diagram of an on-board power supply system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 mounted on an electric vehicle that uses a motor as a driving power source.

[0011] 1, the power supply system has a first power supply 11 and a second power supply 12, and these power supplies 11, 12 are connected by an electric 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 single cells, and the rated voltage of the high-voltage battery 21 is, for example, several hundred volts. Each single 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 for regenerating power when 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 DCDC 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 DCDC 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 composed of a low-voltage battery. The low-voltage battery has a rated voltage lower than that of the high-voltage battery 21, for example, 12 V. The low-voltage battery is a rechargeable storage battery, for example, 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. Each of the loads 31 to 33 has a positive electrode connected to the electrical path 13 and a negative electrode connected to a grounded portion of a 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 the ECU, the first to third loads 31 to 33 may be electric 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 a navigation device, an anti-theft device, a lighting device, or the like. Each of the loads 31 to 33 shown in FIG. 1 may be a single electric load or multiple electric loads.

[0016] Each of the loads 31 to 33 may be other electric loads. For example, each of the loads 31 to 33 may be an electric load used for driving assistance control of a vehicle, specifically, an electric power steering device that generates an assist torque to assist the steering of a driver, an electric brake device that applies a braking force to a wheel, a camera for monitoring the situation around the vehicle, a laser radar such as LIDAR (Laser Imaging Detection and Ranging), a millimeter wave radar, a by-wire system, etc. Also, for example, each of the loads 31 to 33 may be a general electric load such as 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 a connection point B of the second load 32 and a 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 with respect to the cutoff switch 40, a voltage sensor 62 and a current sensor 63 provided on the second power supply 12 side with respect to the cutoff switch 40, and a switch current sensor 64. Each of the voltage sensors 60, 62 detects the voltage of the electric 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, by software alone, by hardware alone, or by 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 of 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 grasps the terminal voltage or SOC of the low-voltage battery of the second power source 12 based on the detection values ​​of the sensors 62 and 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 in the electrical path 13 is short-circuited with a grounded part, 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 to diagnose whether or not 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 shutoff switch 40 is diagnosed, if the shutoff 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 the operation of the first and second loads 31 and 32 may be unintentionally stopped.

[0024] Therefore, the control device 50 includes a determination unit 52 and a command unit 53. The determination unit 52 determines whether or not 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 a procedure for the control process 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-type start switch, and is operated by the user of the vehicle.

[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 source 12 is supplying driving power to the loads 31 to 33.

[0027] In step S10, the path voltage of the electric 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 electric path 13 becomes a value corresponding to the output voltage of the second power source 12.

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

[0029] In step S12, the path voltage of the electric path 13 after the output of the power output command is acquired. In this case, the path voltage of the electric path 13 is a value according to the output voltage of the DC-DC converter 23. In the processes 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 electric path 13.

[0030] In step S13, it is determined whether or not the first power source 11 is in a power output state. In this embodiment, it is determined whether or not the path voltage of the electrical path 13 has increased after the output of the power output command. Specifically, it is determined whether or not the voltage increase value obtained by subtracting the path voltage acquired in the process of step S10 (i.e., the voltage stored in memory) from the path voltage acquired in the process of step S12 is higher than a predetermined threshold value. The threshold value is a value higher than 0V. 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 outputted to the cutoff switch 40, a path voltage on the second power source 12 side of the electrical path 13 is acquired. As the path voltage on the second power source 12 side of the electrical path 13, a detection value of the voltage sensor 62 on the second power source 12 side can be used. The diagnosis unit 51 executes the process of step S15 during the period during which the OFF command is being outputted to the cutoff switch 40.

[0033] In step S16, the presence or absence of an on-failure of the cutoff switch 40 is determined 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 an on-failure of the cutoff switch 40 has not occurred, the process proceeds to step S17. On the other hand, if it is determined in step S16 that an on-failure of the cutoff switch 40 has occurred, the process proceeds to step S18.

[0034] For example, if the 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 in the electric path 13 is considered to return to the value before the power output command is output. Therefore, when the absolute value of the difference between the path voltage acquired in step S15 and the path voltage acquired in the process of step S10 is equal to or less than a predetermined judgment value, it is determined that the ON failure of the cutoff switch 40 does not occur. On the other hand, if the 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 in the electric path 13 is considered to remain as it is after the power output command is output. Therefore, the diagnosis unit 51 determines that the ON failure of the cutoff switch 40 occurs when the absolute value of the difference in the above-mentioned path voltage exceeds the judgment value. Here, the judgment value is, for example, a positive value and a value close to 0.

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

[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 automatic driving mode. Specifically, when the flag is off, transition to the automatic driving mode is permitted, and when the flag is on, transition to the automatic 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 a process of notifying the user that an on-failure has occurred in the cutoff switch 40.

[0038] An example of control executed by the control device 50 is shown in Fig. 3. The operation example shown in Fig. 3 is an operation example in the case where no ON failure occurs in the cutoff switch 40. In Fig. 3, (a) shows the transition of the voltage V2 on the second power source 12 side of the cutoff switch 40 in the electrical path 13, (b) shows the transition of the 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 Fig. 3, it is assumed that no power output is generated from the first power source 11 before time t1.

[0039] At time t1, the control device 50 acquires the path voltage of the electric path 13 and stores the acquired voltage value Va in a 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 electric path 13 after the output of the power output command, and determines that the voltage rise value obtained by subtracting the voltage value Va stored in the 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. As a result, the cutoff switch 40 is turned off, 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. The control device 50 determines whether or not the cutoff switch 40 has an ON failure based on the acquired detection value of the voltage sensor 62 on the second power source 12 side, and sets a failure 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 secured while the cutoff switch 40 is turned off. This makes it possible to prevent unintentional power failure 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 source 11 is in a power output state is determined based on the path voltage of the electrical path 13. Specifically, the first power source 11 is determined to be in a power output state when the path voltage of the electrical path 13 increases after the output of a power output command. This makes it possible to accurately determine that the first power source 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 or not the first power source 11 is in a power output state may be changed. Here, a method of determination using the output current of the first power source 11 will be described.

[0045] In step S13, the output current of the first power source 11 is acquired, and if it is determined that the output current of the first power source 11 exceeds a predetermined threshold current Ith1, it is determined that the first power source 11 is in a power output state. As the output current of the first power source 11, the detection value of the current sensor 61 on the first power source 11 side can be used. On the other hand, if it is determined that the output current of the first power source 11 is equal to or less than the threshold current Ith1, it is determined that the first power source 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 source 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 with respect to 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 assuming that the current flowing in the direction in which the low-voltage battery of the second power source 12 is charged is positive, and the current flowing in the direction in which the low-voltage battery of the second power source 12 is discharged is 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 a value, for example, 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 electric 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 source 12. 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 or not 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 grasp, 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 source 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-mentioned diagnosis of the cutoff switch 40 using the current flowing through the second power source 12 is executed. As the current flowing through the cutoff switch 40, the detection value of the switch current sensor 64 can be used. Note that, in the case where the transition of the current flowing through the cutoff switch 40 is shown in FIG. 5(b), an example of the control operation executed by the control device 50 according to this embodiment is the same as that in FIG. 5.

[0054] According to this embodiment, the detection value of the switch current sensor 64 is used to determine whether or not the first power source 11 is in a power output state. The detection value of the switch current sensor 64 is also used to detect an overcurrent abnormality, for example. 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 electric 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 above, a determination as to whether or not the first power source 11 is in a power output state may be made 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 through the second power source 12, and the current flowing through the cutoff switch 40.

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

[0058] In this embodiment, the control device 50 executes the control shown in Fig. 6. This control is executed at a predetermined interval instead of when the start switch is turned on. Here, it is assumed that the vehicle is running and the cutoff switch 40 is diagnosed while the DC-DC converter 23 is in operation. In Fig. 6, the same processes 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, 32 connected to the first power source 11 side of the cutoff switch 40 in the electric path 13. Specifically, the higher the power required by the first and second loads 31, 32, the higher the set value of the output voltage of the DCDC 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 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. This makes it possible to supply drive power from the first power source 11 to the first and second loads 31 and 32 even if the power required by the first and second loads 31 and 32 increases. Therefore, during the diagnosis of the cutoff switch 40, it is possible to appropriately suppress the occurrence of a situation in which the supply of drive power from the first power source 11 to the first and second loads 31 and 32 is insufficient.

[0062] In the process of step S13 in FIG. 2, the condition for determining whether or not the first power source 11 is in a power output state may be changed.

[0063] It is considered that the power requirement 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 a judgment condition for judging the suitability of the power supply from the first power source 11 to the first load 31 and the second load 32, in anticipation of the change in the required power. In addition, if the judgment condition is too narrow, there is a concern that the opportunities for diagnosing the cutoff switch 40 will be unnecessarily reduced.

[0064] Therefore, the judgment unit 52 changes the judgment condition for whether or not 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 is, the higher the output power of the first power source 11 is changed to. 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 is, the higher the threshold value used for the determination is set.

[0066] According to the present 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, 32. This makes it possible to realize appropriate fault diagnosis while assuming that the power requirements of the loads 31, 32 change.

[0067] It is possible to configure the electrical path 13 without providing 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 restricted.

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

[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 electric path connecting a connection point B of the second load 32 and a positive electrode side of the second load 32. The control device 50 limits the current supply to the second load 32 by turning off the load switch 41 before outputting an OFF command of the cutoff switch 40. In FIG. 7, the same reference numerals are used for the configurations that overlap with those in FIG. 1, and some of them are not shown for convenience.

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

[0072] When it is not possible to limit the supply of current to the second load 32, the command unit 53 does not output an OFF command to the cutoff switch 40. For example, the command unit 53 acquires a 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 it is impossible to limit the current supply to the second load 32. 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 current supply to the second load 32 is limited by turning off the load switch 41 before outputting an OFF command 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 it is impossible to limit the current supply to the second load 32, an OFF command for the cutoff switch 40 is not output. The process in step S31 corresponds to the "current supply 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] In the actual diagnosis of the cutoff switch 40, the supply of drive power from the first power source 11 to the first load 31 is prioritized over the supply of drive power to the second load 32 while the cutoff switch 40 is turned off by restricting the supply of current to the second load 32. As a result, it is possible to appropriately 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, a command to turn off 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 above, instead of turning off the load switch 41, the current 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 according to 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 required by 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 is below the predetermined power, the power supply to the second load 32 is not limited. According to this embodiment, in a situation where the possibility of a shortage in the power supply to the first load 31 is low, 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 electric 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 the sake of convenience.

[0080] The command unit 53 outputs a temporary OFF command to the multiple 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 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 the diagnosis of the cutoff switch 40a is performed, 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 cut-off 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 cut-off switch 40b. In this case, when the cut-off switch 40b is turned off, it is considered that there is a high 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 cut-off switch 40a is turned off, due to the fact that there are a 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 condition for whether or not 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 a higher output power of the first power source 11 compared to when the cutoff switch 40a is to be turned off. For example, when the determination unit 52 executes the determination of 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 the threshold value used for the determination higher as the number of electric loads connected to the first power source 11 side of the cutoff switch 40 to be turned off in the electric path 13 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 assuming that the required power of the electrical loads changes as the number of electrical loads changes.

[0085] <Other embodiments> Each of the above 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 one other than that installed in a vehicle, and may be installed in a moving object other than a vehicle. Also, the power supply system may be a stationary type.

[0089] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer.

[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 a connection point of the second power source and the electrical load, and the switch is turned off to diagnose an on-fault of the switch, a determination unit that determines whether the first power source is in a power output state for outputting 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 during the execution of the diagnosis, the switch control device (50). [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 a 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 whether the first power source is in the power output state depending on a required power 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 whether the first power source is in the power output state depending on the number of electrical loads connected in the electrical path on a 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 that is connected to the first power source side of the switch in the electrical path before the command unit outputs an off command to 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 limiting unit is unable to limit the current flow. [Configuration 8] the first power source is configured to be able to adjust a magnitude of 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 changes the magnitude of the power output of the first power source in accordance with the power requirement of the electrical load that is connected on the first power source side of the switch in the electrical path when the diagnosis is performed. [Explanation of symbols]

[0091] 11...first power source, 12...second power source, 31-33...first to third loads, 40...shutdown 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 a connection point of the second power source and 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 in which it outputs power to the electrical path; a command unit that outputs a temporary 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 a determination condition for whether or not the first power source is in the power output state depending on the required power of 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 a connection point of the second power source and 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 in which it outputs power to the electrical path; a command unit that outputs a temporary 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 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 a connection point of the second power source and 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 in which it 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 during the execution of the diagnosis; a current limiting unit that, when performing the diagnosis, limits current flow 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 for 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 a current flowing through 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 limiting unit is unable to limit the current flow.

7. The first power source is configured to be able to adjust a magnitude of 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 in accordance with the required power of the electrical load that is 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 a connection point of the second power source and 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 determination step of determining whether the first power source is in a power output state in which the first power source outputs power to the electrical path; a command step of temporarily outputting an 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, In the determination step, a program changes a determination condition as to whether the first power source is in the power output state in accordance with the required power of the electrical load connected to the first power source side of the electrical path relative to the switch.

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 a connection point of the second power source and 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 determination step of determining whether the first power source is in a power output state in which the first power source outputs power to the electrical path; a command step of temporarily outputting an 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, 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 turn off each of the plurality of switches provided in the electrical path, In the determination step, a program changes a 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 to the first power source side of the switch that is 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 a connection point of the second power source and 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 determination step of determining whether the first power source is in a power output state in which the first power source outputs power to the electrical path; a command step of temporarily outputting an off command to the switch on condition that the first power source is determined to be in the power output state during the execution of 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 performing the diagnosis, the program causing the computer to execute a process including the steps of:

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 a connection point of the second power source and the electrical load, the switch being turned off to diagnose an on-failure of the switch, a determination step of determining whether the first power source is in a power output state in which the first power source 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 execution of the diagnosis, A switch control method, in which in the determination step, a determination condition for whether the first power source is in the power output state is changed depending on the required power of 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 a connection point of the second power source and the electrical load, the switch being turned off to diagnose an on-failure of the switch, a determination step of determining whether the first power source is in a power output state in which the first power source 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 execution of the diagnosis, 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 turn off each of the plurality of switches provided in the electrical path, A switch control method in which, in the determination step, a determination condition for 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 a connection point of the second power source and the electrical load, the switch being turned off to diagnose an on-failure of the switch, a determination step of determining whether the first power source is in a power output state in which the first power source outputs power to the electrical path; a command step of temporarily outputting an off command to the switch on condition that the first power source is determined to be in the power output state during the execution of 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 performing the diagnosis.

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