Switching element and diagnostic device for abnormality detection circuit

Abstract

A diagnostic device (10) is provided with: a microcomputer (11) that outputs analog signals for simulating an abnormal state to an overvoltage detection circuit (12) and a low voltage detection circuit (13); and a detection circuit (18) that detects the ON of the switching elements (61, 62) after the microcomputer (11) outputs the analog signal. When the detection circuit (18) detects that the switching elements (61, 62) are turned on, the microcomputer (11) determines a failure of the switching elements (61, 62) or a failure of the overvoltage detection circuit (12) and the low voltage detection circuit (13).

Description

Technical Field

[0001] The present invention relates to a diagnostic device for a switch element and an abnormality detection circuit. Background Art

[0002] A known fault detection device detects a fault in a switching element while ensuring a conductive state (see Patent Document 1). In the fault detection device described in Patent Document 1, multiple FET circuit units are connected in parallel, and within each FET circuit unit, a pair of FETs are connected in series and arranged in opposite directions. In this fault detection device, when a pair of FETs in the multiple FET circuit units is controlled to be conductive, a fault in another pair of FETs in the multiple FET circuit units is detected based on the on / off control state of the other pair of FETs in the multiple FET circuit units and the voltage of the conductive path between the FETs.

[0003] Reference List

[0004] Patent Literature

[0005] Patent Document 1: JP2022-74827A Summary of the Invention

[0006] Technical issues

[0007] In the fault detection device described in Patent Document 1, fault diagnosis of the FET is performed while ensuring the on state and supplying power to the load, but fault diagnosis of abnormality detection circuits such as an overvoltage detection circuit and an overcurrent detection circuit is not performed.

[0008] The present invention is made in view of the above situation, and an object of the present invention is to provide a diagnostic device for a switching element and an abnormality detection circuit, which is capable of performing fault diagnosis on the switching element and the abnormality detection circuit while supplying power from a backup battery to a backup load in a redundant system including a redundant load and a redundant battery.

[0009] Solutions to the Problem

[0010] According to the present invention, there is provided a diagnostic device for performing fault diagnosis on a first switching element and an abnormality detection circuit in a redundant system, the redundant system comprising a first storage battery that supplies power to a first load; a second storage battery that supplies power to a second load when an abnormality occurs in the first storage battery; a first power line that connects the second load and the first storage battery; a first switching element that is provided on the first power line; a second power line that connects the second storage battery to a connection point between the first switching element and the second load on the first power line; a second switching element that is provided on the second power line; and a detection circuit, which detects an abnormal state of the first power line or the second power line; and a driver, which disconnects the first switching element when the abnormality detection circuit detects the abnormal state, the diagnostic device comprising: a first signal output unit, which is configured to output a pseudo signal for simulating the abnormal state to the abnormality detection circuit; a detection unit, which is configured to detect the connection of the first switching element after the first signal output unit outputs the pseudo signal; and a determination unit, which is configured to determine a fault of the first switching element or a fault of the abnormality detection circuit when the detection unit detects the connection of the first switching element.

[0011] Advantageous Effects of the Invention

[0012] According to the present invention, it is possible to perform fault diagnosis on a switching element and an abnormality detection circuit while supplying power from a backup storage battery to a backup load in a redundant system including a redundant load and a redundant storage battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a circuit diagram showing a diagnostic device according to an embodiment of the present invention.

[0014] Figure 2 This is a flowchart showing a process when fault diagnosis is performed on a switching element, an overvoltage detection circuit, and a low voltage detection circuit.

[0015] Figure 3 This is a timing chart showing waveforms of various signals when fault diagnosis is performed on a switching element, an overvoltage detection circuit, and a low voltage detection circuit.

[0016] Reference Mark List

[0017] 1: ADAS (first load)

[0018] 2: ADAS (second load)

[0019] 3: Main battery (first battery)

[0020] 4: Backup battery (second battery)

[0021] 5: DC / DC converter

[0022] 10: Diagnostic device (diagnostic device for switching elements and abnormality detection circuit)

[0023] 11: Microcomputer (first to third signal output units, determination unit)

[0024] 12: Overvoltage detection circuit (abnormal detection circuit)

[0025] 13: Low voltage detection circuit (abnormal detection circuit)

[0026] 14: Current cut-off switch (first current cut-off switch)

[0027] 15: Current cut-off switch (second current cut-off switch)

[0028] 18: Detection circuit (detection unit)

[0029] 61: Switching element (first switching element)

[0030] 62: Switching element (first switching element)

[0031] 71: Switching element (second switching element)

[0032] 72: Switching element (second switching element)

[0033] D1: FET driver (driver)

[0034] PL1: Power line (first power line)

[0035] PL2: Power line (second power line)

[0036] PL3: Power Line (Third Power Line)

[0037] PL4: Power Line (Fourth Power Line) DETAILED DESCRIPTION

[0038] Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the embodiments to be described below, and the embodiments to be described below can be appropriately modified within the scope of the spirit of the present invention. In the embodiments to be described below, some configurations may not be described or shown in the drawings, and regarding omitted technical details, publicly known or known technologies will be appropriately applied as long as they do not contradict the contents to be described below.

[0039] Figure 11 is a circuit diagram illustrating a diagnostic device 10 according to an embodiment of the present invention. The diagnostic device 10 shown in the figure is installed in a vehicle that redundantly includes advanced driver assistance systems (hereinafter referred to as ADAS) 1 and 2, a main battery 3, and a backup battery 4. In the vehicle, a main ADAS 1, which is driven in normal conditions, and a backup ADAS 2, which is driven when an abnormality occurs in ADAS 1, are connected in parallel to a DC / DC converter 5. The main battery 3 and the backup battery 4 are also connected in parallel to the DC / DC converter 5.

[0040] The main battery 3 is a secondary battery such as a lead storage battery and is charged by electric power supplied by the DC / DC converter 5. The backup battery 4 is a secondary battery such as a lithium ion storage battery and is charged with electric power supplied from the DC / DC converter 5 or the main battery 3. The DC / DC converter 5 steps down the output voltage of a high-voltage power supply (not shown) to the voltage of the main battery 3 and the backup battery 4.

[0041] The first switch 6 is provided on the power line PL1 connecting the backup ADAS 2 and the DC / DC converter 5. The first switch 6 includes a pair of switching elements 61 and 62. The switching elements 61 and 62 are field effect transistors (FETs) such as metal oxide semiconductor field effect transistors (MOSFETs).

[0042] The sources of the switching element 61 and the switching element 62 are connected to each other. The drain of the switching element 61 is connected to the DC / DC converter 5 and the positive electrode of the main battery 3. The drain of the switching element 62 is connected to the backup ADAS 2 and the second switch 7 described later.

[0043] The gates of the switching elements 61 and 62 are connected to a FET driver D1, which applies a high / low voltage between the gate and source of each switching element 61, 62, with the source as a reference. When the FET driver D1 applies a high-level voltage equal to or higher than the operating threshold between the gate and source, the switching elements 61, 62 are turned on. On the other hand, when the FET driver D1 does not apply a high-level voltage equal to or higher than the operating threshold between the gate and source, the switching elements 61, 62 are turned off. Here, with the current from the drain to the source of each switching element 61, 62 cut off, the first switch 6 blocks bidirectional current.

[0044] The second switch 7 is provided on the power line PL2 connecting the backup ADAS 2 and the drain of the switching element 62 to the backup battery 4. The second switch 7 includes a pair of switching elements 71, 72. The switching elements 71, 72 are field effect transistors such as MOSFETs.

[0045] The sources of the switching element 71 and the switching element 72 are connected to each other. The drain of the switching element 71 is connected to the backup ADAS 2 and the drain of the switching element 62. The drain of the switching element 72 is connected to the positive electrode of the backup battery 4.

[0046] The gates of switching elements 71 and 72 are connected to FET driver D2, which applies a high / low voltage between the gate and source of each switching element 71, 72 with the source as a reference. When FET driver D2 applies a high-level voltage equal to or higher than the operating threshold between the gate and source, switching elements 71, 72 are turned on. On the other hand, when FET driver D2 does not apply a high-level voltage equal to or higher than the operating threshold between the gate and source, switching elements 71, 72 are turned off. Here, with the current from the drain to the source of each switching element 71, 72 cut off, second switch 7 cuts off bidirectional current.

[0047] Second switch 7 and charging circuit 8 are connected in parallel to power line PL2. When first switch 6 is on and second switch 7 is off, charging circuit 8 charges backup battery 4 with current supplied from DC / DC converter 5 or main battery 3.

[0048] Main ADAS 1 is connected on power line PL1 between a connection point of main battery 3 and a connection point of switching element 61. Power line PL2 is connected on power line PL1 between a connection point of switching element 62 and a connection point of backup ADAS 2.

[0049] The vehicle redundantly including ADAS 1 and 2, main battery 3, and backup battery 4 further includes an overvoltage detection circuit 12 and a low voltage detection circuit 13. Overvoltage detection circuit 12 detects an overvoltage state on power line PL1 or power line PL2. Low voltage detection circuit 13 detects an abnormally low voltage state on power line PL1 or power line PL2.

[0050] The overvoltage detection circuit 12 includes an input circuit 121, a comparator 122, and a reference voltage unit 123. The input terminal of the input circuit 121 is connected between the connection point of the main battery 3 and the connection point of the switching element 61 on the power line PL1 via the current cutoff switch 14 described later. The output terminal of the input circuit 121 is connected to the input terminal (+IN) of the comparator 122. The input terminal (-IN) of the comparator 122 is connected to the reference voltage unit 123, and its output terminal is connected to the input terminal of the inverter circuit 16 and the input terminal of the delay circuit 17. The positive power supply terminal of the comparator 122 is connected to the main battery 3 and other terminals, and the negative power supply terminal is grounded.

[0051] Input circuit 121 is a voltage divider that divides the voltage of power line PL1 or power line PL2 and outputs the divided voltage to the input terminal (+IN) of comparator 122. When the voltage between main battery 3 and first switch 6 on power line PL1 is overvoltage, the voltage value indicated by the output signal of input circuit 121 is greater than the voltage value indicated by the output signal of reference voltage unit 123. On the other hand, when the voltage of power line PL1 or power line PL2 is normal, the voltage value indicated by the output signal of input circuit 121 is less than the voltage value indicated by the output signal of reference voltage unit 123.

[0052] When the voltage value indicated by the input signal of the input terminal (+IN) is greater than the voltage value indicated by the input signal of the input terminal (-IN), the comparator 122 outputs a high-level signal from the output terminal to the inverter circuit 16 and the delay circuit 17. That is, when the voltage of the power line PL1 or the power line PL2 is an overvoltage, the comparator 122 outputs a high-level signal to the inverter circuit 16 and the delay circuit 17.

[0053] On the other hand, when the voltage value indicated by the input signal of the input terminal (-IN) is greater than the voltage value indicated by the input signal of the input terminal (+IN), the comparator 122 outputs a low-level signal from the output terminal to the inverter circuit 16 and the delay circuit 17. That is, when the voltage of the power line PL1 or the power line PL2 is normal, the comparator 122 outputs a low-level signal to the inverter circuit 16 and the delay circuit 17.

[0054] Low voltage detection circuit 13 includes an input circuit 131, a comparator 132, and a reference voltage unit 133. The input terminal of input circuit 131 is connected between the connection point of main battery 3 and the connection point of switching element 61 on power line PL1 via current cutoff switch 14. The output terminal of input circuit 131 is connected to the input terminal (-IN) of comparator 132. The input terminal (+IN) of comparator 132 is connected to reference voltage unit 133, and its output terminal is connected to the input terminal of inverter circuit 16 and the input terminal of delay circuit 17. The positive power supply terminal of comparator 132 is connected to the main battery 3 and other terminals, and its negative power supply terminal is grounded.

[0055] Input circuit 131 is a voltage divider that divides the voltage of power line PL1 or power line PL2 and outputs the divided voltage to the input terminal (-IN) of comparator 132. When the voltage of power line PL1 or power line PL2 is abnormally low, the voltage value indicated by the output signal of input circuit 131 is lower than the voltage value indicated by the output signal of reference voltage unit 133. On the other hand, when the voltage of power line PL1 or power line PL2 is normal, the voltage value indicated by the output signal of input circuit 131 is higher than the voltage value indicated by the output signal of reference voltage unit 133.

[0056] When the voltage value indicated by the input signal of the input terminal (-IN) is lower than the voltage value indicated by the input signal of the input terminal (+IN), the comparator 132 outputs a high-level signal from the output terminal to the inverter circuit 16 and the delay circuit 17. That is, when the voltage of the power line PL1 or the power line PL2 is abnormally low, the high-level signal is output from the comparator 132 to the inverter circuit 16 and the delay circuit 17.

[0057] On the other hand, when the voltage value indicated by the input signal of the input terminal (-IN) is greater than the voltage value indicated by the input signal of the input terminal (+IN), comparator 132 outputs a low-level signal from the output terminal to inverter circuit 16 and delay circuit 17. That is, when the voltage of power line PL1 or power line PL2 is normal, a low-level signal is output from comparator 132 to inverter circuit 16 and delay circuit 17.

[0058] Inverter circuit 16 inverts the polarity of the output signals from comparators 122 and 132 and outputs the inverted signals to FET driver D1. When the voltage of power line PL1 or power line PL2 is overvoltage, the high-level signal output from comparator 122 is inverted, and a low-level signal is output to FET driver D1. FET driver D1 sets the voltage applied to the gates of switching elements 61 and 62 to a low-level voltage less than the operating threshold, and turns off first switch 6.

[0059] On the other hand, when the voltage of power line PL1 or power line PL2 is normal, inverter circuit 16 inverts the low-level signal output from comparator 122 and outputs a high-level signal to FET driver D1. FET driver D1 sets the voltage applied to the gates of switching elements 61 and 62 to a high-level voltage equal to or higher than the operating threshold, and turns on first switch 6.

[0060] When the voltage of power line PL1 or power line PL2 is abnormally low, inverter circuit 16 inverts the high-level signal output from comparator 132 and outputs a low-level signal to FET driver D1. FET driver D1 sets the voltage applied to the gates of switching elements 61 and 62 to a low-level voltage lower than the operating threshold and turns off first switch 6.

[0061] On the other hand, when the voltage of power line PL1 or power line PL2 is normal, inverter circuit 16 inverts the low-level signal output from comparator 132 and outputs a high-level signal to FET driver D1. FET driver D1 sets the voltage applied to the gates of switching elements 61 and 62 to a high-level voltage equal to or higher than the operating threshold, and turns on first switch 6.

[0062] The delay circuit 17 is a circuit that delays the signal output from the comparators 122 and 132 to the FET driver D2. The delay circuit 17 prevents the first switch 6 and the second switch 7 from being turned on at the same time.

[0063] Diagnostic device 10 includes a microcomputer 11, current cutoff switches 14 and 15, a detection circuit 18, and an inverter circuit 19. Microcomputer 11 is a control device that controls overvoltage detection circuit 12, undervoltage detection circuit 13, current cutoff switches 14 and 15, and FET drivers D1 and D2. The positive terminal of microcomputer 11 is connected to a power source such as main battery 3, and its negative terminal is grounded.

[0064] When performing fault diagnosis on the first switch 6 and the overvoltage detection circuit 12, the microcomputer 11 outputs a false signal to the input terminal (+IN) of the comparator 122. This false signal indicates a voltage value greater than the voltage value indicated by the output signal of the reference voltage unit 123. Therefore, when the overvoltage detection circuit 12 is operating normally, the voltage value indicated by the input signal at the input terminal (+IN) of the comparator 122 is greater than the voltage value indicated by the input signal at the input terminal (-IN) of the comparator 122, and a high-level signal is output from the comparator 122 to the inverter circuit 16 and the delay circuit 17. In this case, the inverter circuit 16 inverts the high-level signal output from the comparator 122 and outputs a low-level signal to the FET driver D1. The FET driver D1 sets the voltage applied to the gates of the switching elements 61 and 62 to a low-level voltage less than the operating threshold, and turns off the first switch 6.

[0065] When performing fault diagnosis on the low voltage detection circuit 13, the microcomputer 11 outputs a false signal to the input terminal (-IN) of the comparator 132. This false signal is a high-level signal indicating a voltage value greater than the voltage value indicated by the output signal of the reference voltage unit 133. This false signal is inverted by the inverter circuit 19 into a low-level signal indicating a voltage value less than the voltage value indicated by the output signal of the reference voltage unit 133, and this false signal is input to the input terminal (-IN) of the comparator 132. Therefore, when the low voltage detection circuit 13 is operating normally, the voltage value indicated by the input signal at the input terminal (-IN) of the comparator 132 is less than the voltage value indicated by the input signal at the input terminal (+IN) of the comparator 122, and a high-level signal is output from the comparator 132 to the inverter circuit 16 and the delay circuit 17. In this case, the inverter circuit 16 inverts the high-level signal output from the comparator 132 and outputs a low-level signal to the FET driver D1. The FET driver D1 sets the voltage applied to the gates of the switching elements 61 and 62 to a low-level voltage that is lower than the operation threshold, and turns off the first switch 6 .

[0066] Current cutoff switch 14 is provided on power line PL3, which connects input circuits 121 and 131 to power line PL1. Current cutoff switch 14 cuts off power line PL3 except when diagnosing a fault of switching elements 61 and 62, overvoltage detection circuit 12, and low-voltage detection circuit 13, or when overvoltage detection circuit 12 and low-current detection circuit 13 are operating, for example, while the vehicle is running. Conversely, except when the vehicle is parked, microcomputer 11 outputs a current cutoff release signal to current cutoff switch 14, releasing the current cutoff switch's effect on power line PL3.

[0067] Current cutoff switch 15 is provided on power line PL4, which connects the common source of detection circuit 18 and first switch 6. While the vehicle is parked, current cutoff switch 15 cuts off power line PL4. Meanwhile, except when the vehicle is parked, microcomputer 11 outputs a current cutoff release signal to current cutoff switch 15, releasing the current cutoff switch 4 from cutting off power line PL4.

[0068] The detection circuit 18 detects whether the first switch 6 is turned on based on the voltage at the common source of the switching elements 61 and 62 of the first switch 6. When the voltage at the common source of the switching elements 61 and 62 is equal to or higher than a threshold value, the detection circuit 18 outputs a high-level detection signal to the microcomputer 11. On the other hand, when the voltage at the common source of the switching elements 61 and 62 is lower than the threshold value, the detection circuit 18 outputs a low-level detection signal to the microcomputer 11. The threshold value is set to a small value greater than 0V but close to 0V to determine whether the switching elements 61 and 62 are turned on.

[0069] When performing fault diagnosis on the switching elements 61, 62 and the overvoltage detection circuit 12, the microcomputer 11 outputs a current cutoff release signal to the current cutoff switches 14, 15 and a false signal to the overvoltage detection circuit 12. When the switching elements 61, 62 and the overvoltage detection circuit 12 are functioning normally, the switching elements 61 and 62 are off, and a low-level detection signal is output from the detection circuit 18. On the other hand, when at least one of the switching elements 61, 62 and the overvoltage detection circuit 12 fails, the switching elements 61 and 62 remain on, and a high-level detection signal is output from the detection circuit 18. When a high-level detection signal is output from the detection circuit 18, the microcomputer 11 determines that either the switching elements 61, 62 are on or the overvoltage detection circuit 12 is faulty.

[0070] When performing fault diagnosis on the switching elements 61, 62 and the low voltage detection circuit 13, the microcomputer 11 outputs a current cutoff release signal to the current cutoff switches 14, 15 and a false signal to the low voltage detection circuit 13. When the switching elements 61, 62 and the low voltage detection circuit 13 are operating normally, the switching elements 61 and 62 are off, and a low-level detection signal is output from the detection circuit 18. On the other hand, when at least one of the switching elements 61, 62 and the low voltage detection circuit 13 fails, the switching elements 61 and 62 remain on, and a high-level detection signal is output from the detection circuit 18. When a high-level detection signal is output from the detection circuit 18, the microcomputer 11 determines that the switching elements 61, 62 are on-failed or that the low voltage detection circuit 13 has failed.

[0071] Figure 2 1 is a flowchart showing a process when a failure diagnosis is performed on the switching elements 61 and 62 , the overvoltage detection circuit 12 , and the low voltage detection circuit 13 . Figure 3 It is a timing chart showing the waveforms of various signals when fault diagnosis is performed.

[0072] When performing fault diagnosis, first, the microcomputer 11 turns on the current cutoff release signal ( Figure 2 Step S1 in Figure 3 Therefore, the interruption of power line PL3 by current cutoff switch 14 and the interruption of power line PL4 by current cutoff switch 15 are released, overvoltage detection circuit 12 and low voltage detection circuit 13 are connected to power line PL1, and detection circuit 18 is connected to the common source of switching elements 61 and 62.

[0073] Next, the microcomputer 11 turns on (sets to a high level) the switch control signal for the second switch 7 output to the FET driver D2 ( Figure 2 Step S2 in Figure 3 Therefore, the second switch 7 is turned on, and the backup battery 4 is connected to the backup ADAS 2.

[0074] Next, the microcomputer 11 turns on the pseudo signal ( ) output to the input terminal (+IN) of the comparator 122 of the overvoltage detection circuit 12. Figure 2 Step S3 in Figure 3 Then, the microcomputer 11 determines whether the detection signal output from the detection circuit 18 is at a low level ( Figure 2 When the detection signal output from the detection circuit 18 is at a high level ( Figure 2 No in step S4), the microcomputer 11 determines that the switching elements 61, 62 are short-circuited (ON) or the overvoltage detection circuit 12 is faulty (ON). Figure 2On the other hand, when the detection signal output from the detection circuit 18 is at a low level ( Figure 2 In step S4, the microcomputer 11 turns off the pseudo signal ( Figure 2 Step S6 in Figure 3 T4 in ).

[0075] Next, the microcomputer 11 turns on the pseudo signal ( ) output to the input terminal (-IN) of the comparator 132 of the low voltage detection circuit 13. Figure 2 Step S7 in Figure 3 Then, the microcomputer 11 determines whether the detection signal output from the detection circuit 18 is at a low level ( Figure 2 When the detection signal output from the detection circuit 18 is at a high level ( Figure 2 (No in step S8), the microcomputer 11 determines that the switching elements 61, 62 are short-circuited or the low voltage detection circuit 13 is faulty ( Figure 2 On the other hand, when the detection signal output from the detection circuit 18 is at a low level ( Figure 2 In step S8, the microcomputer 11 turns off the pseudo signal ( Figure 2 Step S10 in Figure 3 T6 in ).

[0076] Next, the microcomputer 11 turns off (low level) the switch control signal for the second switch 7 output to the FET driver D2 ( Figure 2 Step S11 in Figure 3 Therefore, the second switch 7 is opened, and the backup battery 4 is disconnected from the backup ADAS 2.

[0077] Finally, the microcomputer 11 turns off the current cutoff release signal ( Figure 2 Step S12 in Figure 3 (T8 in FIG). Consequently, current cutoff switch 14 cuts off power line PL3, and current cutoff switch 15 cuts off power line PL4. Consequently, overvoltage detection circuit 12 and undervoltage detection circuit 13 are disconnected from power line PL1, and detection circuit 18 is disconnected from first switch 6. This concludes the fault diagnosis process.

[0078] As described above, diagnostic device 10 according to the present embodiment performs fault diagnosis on switching elements 61 and 62, overvoltage detection circuit 12, and low voltage detection circuit 13 of the redundant system. The redundant system includes main battery 3, backup battery 4, power line PL1, switching elements 61 and 62, power line PL2, switching elements 71 and 72, overvoltage detection circuit 12, low voltage detection circuit 13, and FET driver D1.

[0079] Main battery 3 supplies power to main ADAS 1, and backup battery 4 supplies power to backup ADAS 2. Power line PL1 connects backup ADAS 2 and main battery 3, and a first switch 6 including switching elements 61 and 62 is provided on power line PL1. Power line PL2 connects the connection point between first switch 6 and backup ADAS 2 on power line PL1 and backup battery 4, and a second switch 7 including switching elements 71 and 72 is provided on power line PL2.

[0080] Overvoltage detection circuit 12 detects an overvoltage state generated on power line PL1 or power line PL2, and low voltage detection circuit 13 detects a low voltage state generated on power line PL1 or power line PL2. When overvoltage detection circuit 12 detects an overvoltage state or low voltage detection circuit 13 detects a low voltage state, FET driver D1 turns off first switch 6.

[0081] Diagnostic device 10 includes a microcomputer 11 and a detection circuit 18. Microcomputer 11 outputs a false signal to overvoltage detection circuit 12 and undervoltage detection circuit 13, simulating an abnormal condition, such as an overvoltage or undervoltage, occurring on power line PL1 or PL2. After microcomputer 11 outputs the false signal, detection circuit 18 detects the closing of switching elements 61 and 62 of first switch 6. When detection circuit 18 detects the closing of switching elements 61 and 62 of first switch 6, microcomputer 11 determines that either switching elements 61 and 62 of first switch 6 are faulty, or that overvoltage detection circuit 12 and undervoltage detection circuit 13 are faulty.

[0082] Therefore, in a state where the backup battery 4 is connected to the backup ADAS 2 and redundancy is ensured among the ADASs 1, 2, the main battery 3, and the backup battery 4, fault diagnosis can be performed on the switching elements 61, 62 of the first switch 6 and the abnormality detection circuits such as the overvoltage detection circuit 12 and the low voltage detection circuit 13.

[0083] In diagnostic device 10 according to this embodiment, current cutoff switch 14 is provided on power line PL3, which connects power line PL1 to abnormality detection circuits such as overvoltage detection circuit 12 and low voltage detection circuit 13. Before outputting the dummy signal, microcomputer 11 outputs a current cutoff release signal to current cutoff switch 14, releasing the current cutoff by current cutoff switch 14. Therefore, except when performing fault diagnosis, dark current supplied from main battery 3 to the abnormality detection circuit can be cut off, and power consumption can be reduced.

[0084] In the diagnostic device 10 according to this embodiment, a current cutoff switch 15 is provided on power line PL4, which connects the switching elements 61 and 62 of the first switch 6 and the detection circuit 18. Before outputting the dummy signal, the microcomputer 11 outputs a current cutoff release signal to the current cutoff switch 15, releasing the current cutoff by the current cutoff switch 15. Therefore, except when the overvoltage detection circuit 12 and the low voltage detection circuit 13 are operating, such as when performing fault diagnosis and when the vehicle is running, dark current supplied from the main battery 3 to the detection circuit 18 can be cut off, and power consumption can be reduced.

[0085] The present invention has been described based on the above embodiments, but the present invention is not limited to the above embodiments and the above embodiments may be modified and publicly known or known technologies may be appropriately combined within a scope not departing from the spirit of the present invention.

[0086] For example, in the above embodiment, the redundant loads include ADAS 1 and 2. Alternatively, the redundant loads may include another load such as a power steering system. Furthermore, in the above embodiment, the abnormality detection circuit includes overvoltage detection circuit 12 and low voltage detection circuit 13. Alternatively, the abnormality detection circuit may include another circuit, such as an overcurrent detection circuit that detects overcurrent on power line PL1 or an overheat detection circuit that detects overheating on power line PL1.

[0087] Although the embodiment has been described above, it goes without saying that the present invention is not limited to this example. Obviously, those skilled in the art can propose various modifications or corrections within the scope of the claims, and it should be understood that these modifications or corrections naturally fall within the technical scope of the present invention. In addition, the components described in the above embodiment can be freely combined without departing from the spirit of the present invention.

[0088] This application is based on Japanese patent application (No. 2023-181539A) filed on October 23, 2023, the contents of which are incorporated herein by reference.

Claims

1. A diagnostic device for performing fault diagnosis on a first switching element and an abnormality detection circuit in a redundant system, The redundant system comprises: a first storage battery that supplies power to a first load; a second storage battery configured to supply power to a second load when an abnormality occurs in the first storage battery; a first power line connecting the second load and the first battery; the first switching element, the first switching element being arranged on the first power line; a second power line connecting the second storage battery and a connection point between the first switching element and the second load on the first power line; a second switching element, the second switching element being disposed on the second power line; the abnormality detection circuit, which detects an abnormal state of the first power line or the second power line; as well as a driver, wherein when the abnormality detection circuit detects the abnormal state, the driver turns off the first switching element, The diagnostic device comprises: a first signal output unit, the first signal output unit outputting a pseudo signal for simulating the abnormal state to the abnormality detection circuit; a detection unit configured to detect that the first switching element is turned on after the first signal output unit outputs the false signal; and A determination unit determines that there is a failure in the first switching element or a failure in the abnormality detection circuit when the detection unit detects that the first switching element is turned on.

2. The switching element and abnormality detection circuit diagnostic device according to claim 1, further comprising: a first current cutoff switch, the first current cutoff switch being provided on a third power line, the third power line connecting the first power line and the abnormality detection circuit; as well as A second signal output unit is configured to output a first release signal to the first current cutoff switch before the first signal output unit outputs the false signal. The first release signal is configured to release the current cutoff caused by the first current cutoff switch.

3. The switching element and abnormality detection circuit diagnostic device according to claim 1 or 2, further comprising: a second current cut-off switch, the second current cut-off switch being provided on a fourth power line, the fourth power line connecting the first switching element and the detection unit; as well as A third signal output unit is configured to output a second release signal to the second current cutoff switch before the first signal output unit outputs the false signal. The second release signal is configured to release the current cutoff caused by the second current cutoff switch.

4. The diagnostic device for a switching element and an abnormality detection circuit according to claim 1 or 2, wherein: The abnormality detection circuit includes: an overvoltage detection circuit that detects an overvoltage state as an abnormal state; and a low voltage detection circuit that detects a low voltage state as an abnormal state, and The driver turns off the first switching element in a case where the overvoltage detection circuit detects the overvoltage state and in a case where the low voltage detection circuit detects the low voltage state.

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