Diagnostic device for switching element and abnormality detection circuit

Abstract

To perform fault diagnosis of switching elements and abnormality detection circuits in a redundant system with redundant loads and storage batteries, while supplying power to backup loads from backup storage batteries.SOLUTION: Diagnostic equipment 10 comprises a microcomputer 11 that outputs pseudo-signals to an overvoltage detection circuit 12 and an undervoltage detection circuit 13 to simulate abnormal conditions and a detection circuit 18 that detects that switching elements 61 and 62 are ON after the pseudo-signal is output by the microcomputer 11, and the microcomputer 11 judges a failure of switching elements 61 and 62 or a failure of the overvoltage detection circuit 12 and undervoltage detection circuit 13 when switching elements 61 and 62 are detected to be ON by the detection circuit 18.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A fault detection device that detects a fault in a switching element while maintaining a conductive state is known (see, for example, Patent Document 1). In the fault detection device described in Patent Document 1, a plurality of FET circuit units are connected in parallel, and in each FET circuit unit, a pair of FETs are connected in series and arranged in opposite directions. In this fault detection device, while one pair of FETs in the plurality of FET circuit units is controlled to be ON, a fault in the FETs in the other pair of FET circuit units is detected based on the ON / OFF control state of the other pair of FETs in the plurality of FET circuit units and the voltage of the conductive path between the FETs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-74827 Summary of the Invention [Problem to be solved by the invention]

[0004] In the fault detection device described in Patent Document 1, fault diagnosis of the FET is performed while maintaining a conductive state and supplying power to the load, but fault diagnosis of abnormality detection circuits such as an overvoltage detection circuit or an overcurrent detection circuit is not performed.

[0005] In view of the above circumstances, an object of the present invention is to provide a diagnostic device for a switching element and an abnormality detection circuit that can perform fault diagnosis of a switching element and an abnormality detection circuit while supplying power from a backup storage battery to a backup load in a redundant system in which the load and storage battery are redundant. [Means for solving the problem]

[0006] The diagnostic device for a switching element and an abnormality detection circuit of the present invention includes 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 on the first storage battery side, a first power line that connects the second load and the first storage battery, a first switching element provided on the first power line, a second power line that connects a portion of the first power line between the first switching element and the second load and the second storage battery, a second switching element provided on the second power line, an abnormality detection circuit that detects an abnormal state occurring on the first power line or the second power line, and a power supply that supplies power to a first storage battery that supplies power to a second load when an abnormality occurs on the first storage battery side. a driver that turns off the first switching element when the abnormal state is detected by a detection circuit, the diagnostic device performing a fault diagnosis on the first switching element and the abnormality detection circuit in a redundant system, the diagnostic device including: a first signal output unit that outputs a pseudo signal to the abnormality detection circuit to simulate the abnormal state; a detection unit that detects that the first switching element is ON after the pseudo signal is output by the first signal output unit; and a determination unit that determines that there is a fault in the first switching element or a fault in the abnormality detection circuit when it is detected by the detection unit that the first switching element is ON. a first current cut switch provided on a third power line connecting the first power line and the abnormality detection circuit; and a second signal output unit that outputs a first release signal to the first current cut switch before the pseudo signal is output by the first signal output unit, the first release signal releasing the current cut by the first current cut switch. Equipped with. The diagnostic device for a switching element and an abnormality detection circuit of the present invention is a redundant system including: 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 on the first storage battery side; a first power line that connects the second load and the first storage battery; a first switching element provided on the first power line; a second power line that connects a portion of the first power line between the first switching element and the second load and the second storage battery; a second switching element provided on the second power line; an abnormality detection circuit that detects an abnormal state occurring on the first power line or the second power line; and a driver that turns off the first switching element when the abnormality state is detected by the abnormality detection circuit. a first signal output unit that outputs a pseudo signal to the abnormality detection circuit to simulate the abnormal state; a detection unit that detects that the first switching element is ON after the pseudo signal is output by the first signal output unit; a determination unit that determines that there is a failure of the first switching element or a failure of the abnormality detection circuit when the detection unit detects that the first switching element is ON; a second current cut switch provided on a fourth power line connecting the first switching element and the detection unit; and a third signal output unit that outputs a second release signal to the second current cut switch to release the current cut by the second current cut switch before the pseudo signal is output by the first signal output unit. The diagnostic device for a switching element and an abnormality detection circuit of the present invention is a diagnostic device for a switching element and an abnormality detection circuit in a redundant system including: 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 on the first storage battery side; a first power line that connects the second load and the first storage battery; a first switching element provided on the first power line; a second power line that connects a point on the first power line between the first switching element and the second load and the second storage battery; a second switching element provided on the second power line; an abnormality detection circuit that detects an abnormal state occurring on the first power line or the second power line; and a driver that turns off the first switching element when the abnormality state is detected by the abnormality detection circuit. a first signal output unit that outputs a pseudo signal to the abnormality detection circuit to simulate the abnormal state; a detection unit that detects that the first switching element is ON after the pseudo signal is output by the first signal output unit; and a determination unit that determines that there is a failure of the first switching element or a failure of the abnormality detection circuit when the detection unit detects that the first switching element is ON, wherein the abnormality detection circuit includes an overvoltage detection circuit that detects an overvoltage state as the abnormal state and a low voltage detection circuit that detects an low voltage state as the abnormal state, and the driver turns OFF the first switching element when the overvoltage detection circuit detects the overvoltage state and when the low voltage detection circuit detects the low voltage state. [Effects of the Invention]

[0007] According to the present invention, in a redundant system in which the load and the storage battery are redundant, it is possible to perform fault diagnosis on the switching elements and the abnormality detection circuit while supplying power from the backup storage battery to the backup load. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram showing a diagnostic device according to one embodiment of the present invention. [Figure 2]FIG. 2 is a flowchart showing the process of performing failure diagnosis on the switching elements, the overvoltage detection circuit, and the undervoltage detection circuit. [Figure 3] FIG. 3 is a timing chart showing waveforms of various signals when fault diagnosis is performed on the switching elements, the overvoltage detection circuit, and the undervoltage detection circuit. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments described below, and the embodiments described below can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments described below, some components are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of not causing any contradictions with the content described below.

[0010] Fig. 1 is a circuit diagram showing a diagnostic device 10 according to one embodiment of the present invention. The diagnostic device 10 shown in this figure is mounted on a vehicle having a redundant configuration of advanced driver assistance systems (hereinafter referred to as ADAS (Advanced Driver Assistance Systems)) 1, 2, a main battery 3, and a backup battery 4. In this vehicle, a main ADAS 1 that is driven under normal conditions and a backup ADAS 2 that is driven when an abnormality occurs in the ADAS 1 are connected in parallel to a DC / DC converter 5. In addition, the main battery 3 and the backup battery 4 are connected in parallel to the DC / DC converter 5.

[0011] The main battery 3 is a secondary battery such as a lead storage battery, and is charged with power supplied from the DC / DC converter 5. The backup battery 4 is a secondary battery such as a lithium ion storage battery, and is charged with 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.

[0012] A first switch 6 is provided on a 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).

[0013] The source of the switching element 61 and the source of the switching element 62 are connected to each other. The drain of the switching element 61 is connected to the positive electrode of the main battery 3 and the DC / DC converter 5. In addition, the drain of the switching element 62 is connected to the backup ADAS 2 and a second switch 7, which will be described later.

[0014] The FET driver D1 is connected to the gate of the switching element 61 and the gate of the switching element 62, and applies a high / low voltage between the gate and source of each of the switching elements 61 and 62, with the source as the reference. When the FET driver D1 applies a high-level voltage equal to or greater than the operating threshold between the gate and source of the switching elements 61 and 62, the switching elements 61 and 62 turn on. On the other hand, when the FET driver D1 does not apply a high-level voltage equal to or greater than the operating threshold between the gate and source of the switching elements 61 and 62, the switching elements 61 and 62 turn off. Here, with the current from the drain to the source of the switching elements 61 and 62 blocked, the first switch 6 blocks current in both directions.

[0015] A second switch 7 is provided on a power line PL2 that connects 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 and 72. The switching elements 71 and 72 are field-effect transistors such as MOSFETs.

[0016] The source of the switching element 71 and the source of 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. In addition, the drain of the switching element 72 is connected to the positive electrode of the backup battery 4.

[0017] The FET driver D2 is connected to the gate of the switching element 71 and the gate of the switching element 72, and applies a high / low voltage between the gate and source of each of the switching elements 71 and 72, with the source as the reference. When the FET driver D2 applies a high-level voltage equal to or greater than the operating threshold between the gate and source of the switching elements 71 and 72, the switching elements 71 and 72 turn on. On the other hand, when the FET driver D2 does not apply a high-level voltage equal to or greater than the operating threshold between the gate and source of the switching elements 71 and 72, the switching elements 71 and 72 turn off. Here, with the current from the drain to the source of the switching elements 71 and 72 blocked, the second switch 7 blocks current in both directions.

[0018] The second switch 7 and the charging circuit 8 are connected in parallel to the power line PL2. While the first switch 6 is ON and the second switch 7 is OFF, the charging circuit 8 charges the backup battery 4 with a current supplied from the DC / DC converter 5 or the main battery 3.

[0019] The main ADAS1 is connected to the power line PL1 between the connection point of the main battery 3 and the connection point of the switching element 61. The power line PL2 is connected to the power line PL1 between the connection point of the switching element 62 and the connection point of the backup ADAS2.

[0020] A vehicle having a redundant configuration of ADASs 1 and 2, a main battery 3, and a backup battery 4 is equipped with an overvoltage detection circuit 12 and a low voltage detection circuit 13. The overvoltage detection circuit 12 detects an overvoltage state of the power line PL1 or the power line PL2. The low voltage detection circuit 13 detects an abnormally low voltage state of the power line PL1 or the power line PL2.

[0021] The overvoltage detection circuit 12 includes an input circuit 121, a comparator 122, and a reference voltage unit 123. An input terminal of the input circuit 121 is connected between a connection point of the power line PL1 to the main battery 3 and a connection point of the switching element 61 via a current cut switch 14 (described later). An output terminal of the input circuit 121 is connected to an input terminal (+IN) of the comparator 122. An input terminal (-IN) of the comparator 122 is connected to the reference voltage unit 123, and an output terminal of the comparator 122 is connected to an input terminal of the inverting circuit 16 and an input terminal of the delay circuit 17. A positive power supply terminal of the comparator 122 is connected to the main battery 3, etc., and a negative power supply terminal of the comparator 122 is grounded.

[0022] Input circuit 121 is a voltage divider circuit 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 an overvoltage, the voltage value indicated by the output signal of input circuit 121 is higher 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 lower than the voltage value indicated by the output signal of reference voltage unit 123.

[0023] When the voltage value indicated by the input signal at the input terminal (+IN) is higher than the voltage value indicated by the input signal at 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. In other words, 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.

[0024] On the other hand, when the voltage value indicated by the input signal at the input terminal (-IN) is higher than the voltage value indicated by the input signal at 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. In other words, 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.

[0025] The low voltage detection circuit 13 includes an input circuit 131, a comparator 132, and a reference voltage unit 133. An input terminal of the input circuit 131 is connected via the current cut switch 14 between a connection point of the power line PL1 with the main battery 3 and a connection point of the switching element 61. An output terminal of the input circuit 131 is connected to an input terminal (-IN) of the comparator 132. An input terminal (+IN) of the comparator 132 is connected to the reference voltage unit 133, and an output terminal of the comparator 132 is connected to an input terminal of the inverting circuit 16 and an input terminal of the delay circuit 17. A positive power supply terminal of the comparator 132 is connected to the main battery 3, etc., and a negative power supply terminal of the comparator 132 is grounded.

[0026] Input circuit 131 is a voltage divider circuit that divides the voltage of power line PL1 or PL2 and outputs the divided voltage to input terminal (-IN) of comparator 132. When the voltage of power line PL1 or 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 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.

[0027] When the voltage value indicated by the input signal at the input terminal (-IN) is lower than the voltage value indicated by the input signal at 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. In other words, when the voltage of the power line PL1 or the power line PL2 is abnormally low, the comparator 132 outputs a high-level signal to the inverter circuit 16 and the delay circuit 17.

[0028] On the other hand, when the voltage value indicated by the input signal at the input terminal (-IN) is higher than the voltage value indicated by the input signal at the input terminal (+IN), the comparator 132 outputs a low-level signal from the output terminal to the inverting circuit 16 and the delay circuit 17. In other words, when the voltage of the power line PL1 or the power line PL2 is normal, the comparator 132 outputs a low-level signal to the inverting circuit 16 and the delay circuit 17.

[0029] The inverting circuit 16 inverts the polarity of the output signals of the comparators 122 and 132 and outputs the inverted signal to the FET driver D1. When the voltage of the power line PL1 or PL2 is an overvoltage, the inverting 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 below the operating threshold, and turns off the first switch 6.

[0030] On the other hand, when the voltage of the power line PL1 or PL2 is normal, the inverting circuit 16 inverts the low-level signal output from the comparator 122 and outputs a high-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 high-level voltage equal to or higher than the operating threshold, and turns on the first switch 6.

[0031] Furthermore, when the voltage of the power line PL1 or PL2 is abnormally low, the inverting 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 below the operating threshold, and turns off the first switch 6.

[0032] On the other hand, when the voltage of the power line PL1 or PL2 is normal, the inverting circuit 16 inverts the low-level signal output from the comparator 132 and outputs a high-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 high-level voltage equal to or higher than the operating threshold, and turns on the first switch 6.

[0033] The delay circuit 17 is a circuit that delays the signals output to the FET driver D2 from the comparators 122 and 132. The delay circuit 17 prevents the first switch 6 and the second switch 7 from being turned on at the same time.

[0034] The diagnostic device 10 includes a microcomputer 11, current cutoff switches 14 and 15, a detection circuit 18, and an inversion circuit 19. The microcomputer 11 is a control device that controls the overvoltage detection circuit 12, the low-voltage detection circuit 13, the current cutoff switches 14 and 15, and the FET drivers D1 and D2. The positive terminal of the microcomputer 11 is connected to a power source such as the main battery 3, and the negative terminal of the microcomputer 11 is grounded.

[0035] When the microcomputer 11 performs a fault diagnosis of the first switch 6 and the overvoltage detection circuit 12, it outputs a pseudo signal to the input terminal (+IN) of the comparator 122. The pseudo signal is a signal indicating a voltage value higher than the voltage value indicated by the output signal of the reference voltage unit 123. Therefore, when the overvoltage detection circuit 12 operates normally, the voltage value indicated by the input signal of the input terminal (+IN) of the comparator 122 becomes higher than the voltage value indicated by the input signal of the input terminal (-IN) of the comparator 122, and the comparator 122 outputs a high-level signal 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 applies a low-level voltage lower than the operating threshold to the gates of the switching elements 61 and 62, turning off the first switch 6.

[0036] When the microcomputer 11 performs a fault diagnosis on the low-voltage detection circuit 13, it outputs a pseudo signal to the input terminal (-IN) of the comparator 132. The pseudo signal is a high-level signal indicating a voltage value higher than the voltage value indicated by the output signal of the reference voltage unit 133. The pseudo signal is inverted by the inverter circuit 19 into a low-level signal indicating a voltage value lower than the voltage value indicated by the output signal of the reference voltage unit 133, and is input to the input terminal (-IN) of the comparator 132. Therefore, when the low-voltage detection circuit 13 operates normally, the voltage value indicated by the input signal of the input terminal (-IN) of the comparator 132 becomes lower than the voltage value indicated by the input signal of the input terminal (+IN) of the comparator 122, and the comparator 132 outputs a high-level signal 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 applies a low-level voltage below the operating threshold to the gates of the switching elements 61 and 62, thereby turning the first switch 6 OFF.

[0037] Current cut switch 14 is provided on power line PL3 that connects input circuits 121, 131 to power line PL1. Current cut switch 14 cuts off power line PL3 except when overvoltage detection circuit 12 and low voltage detection circuit 13 are operating, such as when performing failure diagnosis on switching elements 61, 62, overvoltage detection circuit 12, and low voltage detection circuit 13, or when the vehicle is running. In contrast, except when the vehicle is parked, microcomputer 11 outputs a current cut release signal to current cut switch 14, which releases the cut-off of power line PL3 by current cut switch 14.

[0038] Current cut switch 15 is provided on power line PL4 that connects detection circuit 18 and the common source of first switch 6. When the vehicle is parked, current cut switch 15 cuts off power line PL4. When the vehicle is not parked, microcomputer 11 outputs a current cut release signal to current cut switch 15, which releases the cut-off of power line PL4 by current cut switch 15.

[0039] The detection circuit 18 is a circuit that detects whether the first switch 6 is ON in accordance with the voltage of the common source of the switching elements 61, 62 of the first switch 6. This detection circuit 18 outputs a high-level detection signal to the microcomputer 11 when the voltage of the common source of the switching elements 61, 62 is equal to or higher than a threshold. On the other hand, the detection circuit 18 outputs a low-level detection signal to the microcomputer 11 when the voltage of the common source of the switching elements 61, 62 is lower than the threshold. The threshold is set to a low value higher than but close to 0 V in order to determine whether the switching elements 61, 62 are ON.

[0040] When performing a fault diagnosis of the switching elements 61, 62 and the overvoltage detection circuit 12, the microcomputer 11 outputs a current cut release signal to the current cut switches 14, 15 and outputs a pseudo signal to the overvoltage detection circuit 12. When the switching elements 61, 62 and the overvoltage detection circuit 12 are operating normally, the switching elements 61, 62 are turned OFF, and a low-level detection signal is output from the detection circuit 18. On the other hand, when a fault occurs in at least one of the switching elements 61, 62 or the overvoltage detection circuit 12, the switching elements 61, 62 are maintained 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 an ON fault has occurred in the switching elements 61, 62 or that the overvoltage detection circuit 12 has failed.

[0041] When performing a fault diagnosis on the switching elements 61, 62 and the low-voltage detection circuit 13, the microcomputer 11 outputs a current cut-off release signal to the current cut-off switches 14, 15 and outputs a pseudo signal to the low-voltage detection circuit 13. If the switching elements 61, 62 and the low-voltage detection circuit 13 are operating normally, the switching elements 61, 62 are turned OFF, and a low-level detection signal is output from the detection circuit 18. On the other hand, if a fault has occurred in at least one of the switching elements 61, 62 or the low-voltage detection circuit 13, the switching elements 61, 62 are maintained ON, and a high-level detection signal is output from the detection circuit 18. If a high-level detection signal is output from the detection circuit 18, the microcomputer 11 determines that an ON fault has occurred in the switching elements 61, 62 or that the low-voltage detection circuit 13 has failed.

[0042] Fig. 2 is a flowchart showing the process of performing fault diagnosis (hereinafter referred to as fault diagnosis) of the switching elements 61 and 62, the overvoltage detection circuit 12, and the undervoltage detection circuit 13. Fig. 3 is a timing chart showing the waveforms of various signals when the fault diagnosis is performed.

[0043] When performing a fault diagnosis, first, microcomputer 11 turns ON the current cut release signal output to current cut switches 14 and 15 (step S1 in FIG. 2, T1 in FIG. 3). This releases the cut-off of power line PL3 by current cut switch 14 and the cut-off of power line PL4 by current cut switch 15, connects overvoltage detection circuit 12 and low voltage detection circuit 13 to power line PL1, and connects detection circuit 18 to the common source of switching elements 61 and 62.

[0044] Next, the microcomputer 11 turns on (high level) the switch control signal of the second switch 7 output to the FET driver D2 (step S2 in FIG. 2, T2 in FIG. 3), thereby turning on the second switch 7 and connecting the backup battery 4 to the backup ADAS 2.

[0045] Next, the microcomputer 11 turns on the pseudo signal to be output to the input terminal (+IN) of the comparator 122 of the overvoltage detection circuit 12 (step S3 in FIG. 2, T3 in FIG. 3). Next, the microcomputer 11 determines whether the detection signal output from the detection circuit 18 is at a low level (step S4 in FIG. 2). If the detection signal output from the detection circuit 18 is at a high level (NO in step S4 in FIG. 2), the microcomputer 11 determines that there is a short-circuit failure (ON failure) in the switching elements 61 and 62 or a failure in the overvoltage detection circuit 12 (step S5 in FIG. 2). On the other hand, if the detection signal output from the detection circuit 18 is at a low level (YES in step S4 in FIG. 2), the microcomputer 11 turns off the pseudo signal (step S6 in FIG. 2, T4 in FIG. 3).

[0046] Next, the microcomputer 11 turns on the pseudo signal to be output to the input terminal (-IN) of the comparator 132 of the low-voltage detection circuit 13 (step S7 in FIG. 2, T5 in FIG. 3). Next, the microcomputer 11 determines whether the detection signal output from the detection circuit 18 is at a low level (step S8 in FIG. 2). If the detection signal output from the detection circuit 18 is at a high level (NO in step S8 in FIG. 2), the microcomputer 11 determines that there is a short-circuit failure in the switching elements 61 and 62 or a failure in the low-voltage detection circuit 13 (step S9 in FIG. 2). On the other hand, if the detection signal output from the detection circuit 18 is at a low level (YES in step S8 in FIG. 2), the microcomputer 11 turns off the pseudo signal (step S10 in FIG. 2, T6 in FIG. 3).

[0047] Next, the microcomputer 11 turns OFF (low level) the switch control signal of the second switch 7 output to the FET driver D2 (step S11 in FIG. 2, T7 in FIG. 3), thereby turning OFF the second switch 7 and disconnecting the backup battery 4 from the backup ADAS 2.

[0048] Finally, microcomputer 11 turns OFF the current cut release signal output to current cut switches 14 and 15 (step S12 in FIG. 2, T8 in FIG. 3). As a result, current cut switch 14 cuts off power line PL3, and current cut switch 15 cuts off power line PL4. Therefore, overvoltage detection circuit 12 and low voltage detection circuit 13 are cut off from power line PL1, and detection circuit 18 is cut off from first switch 6. This completes the fault diagnosis process.

[0049] As described above, the diagnostic device 10 of this embodiment performs fault diagnosis on the switching elements 61 and 62, the overvoltage detection circuit 12, and the low voltage detection circuit 13 of the redundant system. This redundant system includes the main battery 3, the backup battery 4, the power line PL1, the switching elements 61 and 62, the power line PL2, the switching elements 71 and 72, the overvoltage detection circuit 12, the low voltage detection circuit 13, and the FET driver D1.

[0050] A main battery 3 supplies power to a main ADAS 1, and a backup battery 4 supplies power to a backup ADAS 2. A power line PL1 connects the backup ADAS 2 and the main battery 3, and a first switch 6 composed of switching elements 61 and 62 is provided on the power line PL1. A power line PL2 connects the first switch 6 and the backup ADAS 2 on the power line PL1 with the backup battery 4, and a second switch 7 composed of switching elements 71 and 72 is provided on the power line PL2.

[0051] The overvoltage detection circuit 12 detects an overvoltage state occurring on the power line PL1 or the power line PL2, and the low voltage detection circuit 13 detects an undervoltage state occurring on the power line PL1 or the power line PL2. Furthermore, the FET driver D1 turns off the first switch 6 when the overvoltage detection circuit 12 detects an overvoltage state or the low voltage detection circuit 13 detects an undervoltage state.

[0052] The diagnostic device 10 includes a microcomputer 11 and a detection circuit 18. The microcomputer 11 outputs a pseudo signal to the overvoltage detection circuit 12 and the low voltage detection circuit 13 to simulate an abnormal state such as an overvoltage or low voltage occurring on the power line PL1 or the power line PL2. The detection circuit 18 detects that the switching elements 61, 62 of the first switch 6 are ON after the pseudo signal is output by the microcomputer 11. When the detection circuit 18 detects that the switching elements 61, 62 of the first switch 6 are ON, the microcomputer 11 determines that the switching elements 61, 62 of the first switch 6 are faulty, or that the overvoltage detection circuit 12 and the low voltage detection circuit 13 are faulty.

[0053] This allows the backup battery 4 to be connected to the backup ADAS 2, ensuring redundancy between the ADAS 1, 2 and the main battery 3 and backup battery 4, and then performing fault diagnosis on the switching elements 61, 62 of the first switch 6 and abnormality detection circuits such as the overvoltage detection circuit 12 and the low voltage detection circuit 13.

[0054] Furthermore, in the diagnostic device 10 of this embodiment, a current cut switch 14 is provided on a power line PL3 that connects the power line PL1 with abnormality detection circuits such as an overvoltage detection circuit 12 and an undervoltage detection circuit 13. The microcomputer 11 outputs a current cut release signal to the current cut switch 14 to release the current cut off by the current cut switch 14 before the pseudo signal is output. This makes it possible to cut off the dark current supplied from the main battery 3 to the abnormality detection circuits except when a fault diagnosis is being performed, thereby reducing power consumption.

[0055] Furthermore, in the diagnostic device 10 of this embodiment, a current cut switch 15 is provided on the power line PL4 connecting the switching elements 61, 62 of the first switch 6 and the detection circuit 18. The microcomputer 11 outputs a current cut release signal to the current cut switch 15 to release the current cut off by the current cut switch 15 before the pseudo signal is output. This makes it possible to cut off the dark current supplied from the main battery 3 to the detection circuit 18, except when the overvoltage detection circuit 12 and the low voltage detection circuit 13 are operating, such as when a fault diagnosis is being performed or while the vehicle is running, thereby reducing power consumption.

[0056] The present invention has been described above based on the above embodiment, but the present invention is not limited to the above embodiment, and modifications may be made to the above embodiment within the scope of the spirit of the present invention, or publicly known or well-known technologies may be combined as appropriate.

[0057] For example, in the above embodiment, the loads to be provided with redundancy are ADAS1 and ADAS2, but the loads to be provided with redundancy may be other loads such as power steering, etc. Also, in the above embodiment, the abnormality detection circuits are the overvoltage detection circuit 12 and the low voltage detection circuit 13, but the abnormality detection circuit may be other circuits such as an overcurrent detection circuit that detects an overcurrent in the power line PL1 or an overheat detection circuit that detects overheating of the power line PL1. [Explanation of symbols]

[0058] 1: ADAS (first load) 2: ADAS (second load) 3: Main battery (first storage battery) 4: Backup battery (second storage battery) 5: DC / DC converter 10: Diagnostic device (diagnostic device for switching elements and abnormality detection circuits) 11: Microcomputer (first to third signal output units, judgment unit) 12: Overvoltage detection circuit (abnormality detection circuit) 13: Low voltage detection circuit (abnormality detection circuit) 14: Current cut switch (first current cut switch) 15: Current cut switch (second current cut switch) 18: Detection circuit (detection section) 61: Switching element (first switching element) 62: Switching element (first switching element) 71: Switching element (second switching element) 72: Switching element (second switching element) D1: FET driver (driver) PL1: Power line (first power line) PL2: Power line (second power line) PL3: Power line (third power line) PL4: Power line (fourth power line)

Claims

1. a first power line connecting the second load and the first storage battery; a first switching element provided on the first power line; a second power line connecting the second storage battery and a point on the first power line between the first switching element and the second load; a second switching element provided on the second power line; an abnormality detection circuit detecting an abnormal state occurring on the first power line or the second power line; and a driver turning off the first switching element when the abnormal state is detected by the abnormality detection circuit, the diagnostic device performing a fault diagnosis on the first switching element and the abnormality detection circuit in a redundant system, a first signal output unit that outputs a pseudo signal for simulating the abnormal state to the abnormality detection circuit; a detection unit that detects that the first switching element is ON after the first signal output unit outputs the pseudo signal; a determination unit that determines, when the detection unit detects that the first switching element is ON, that the first switching element or the abnormality detection circuit has failed; a first current cut switch provided on a third power line connecting the first power line and the abnormality detection circuit; a second signal output unit that outputs a first release signal for releasing the current cutoff by the first current cutoff switch to the first current cutoff switch before the first signal output unit outputs the pseudo signal; A diagnostic device for a switching element and an abnormality detection circuit comprising:

2. A diagnostic device for performing fault diagnosis of the first switching element and the abnormality detection circuit in a 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 on the first storage battery side; a first power line that connects the second load and the first storage battery; a first switching element provided on the first power line; a second power line that connects the first switching element and the second load on the first power line to the second storage battery; a second switching element provided on the second power line; an abnormality detection circuit that detects an abnormal state occurring on the first power line or the second power line; and a driver that turns off the first switching element when the abnormality detection circuit detects the abnormal state, a first signal output unit that outputs a pseudo signal for simulating the abnormal state to the abnormality detection circuit; a detection unit that detects that the first switching element is ON after the first signal output unit outputs the pseudo signal; a determination unit that determines, when the detection unit detects that the first switching element is ON, that the first switching element or the abnormality detection circuit has failed; a second current cut switch provided on a fourth power line connecting the first switching element and the detection unit; a third signal output unit that outputs a second release signal for releasing the current cutoff by the second current cutoff switch to the second current cutoff switch before the first signal output unit outputs the pseudo signal; A diagnostic device for a switching element and an abnormality detection circuit comprising:

3. A diagnostic device for performing fault diagnosis of the first switching element and the abnormality detection circuit in a 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 on the first storage battery side; a first power line that connects the second load and the first storage battery; a first switching element provided on the first power line; a second power line that connects the first switching element and the second load on the first power line to the second storage battery; a second switching element provided on the second power line; an abnormality detection circuit that detects an abnormal state occurring on the first power line or the second power line; and a driver that turns off the first switching element when the abnormality detection circuit detects the abnormal state, a first signal output unit that outputs a pseudo signal for simulating the abnormal state to the abnormality detection circuit; a detection unit that detects that the first switching element is ON after the first signal output unit outputs the pseudo signal; a determination unit that determines, when the detection unit detects that the first switching element is ON, that the first switching element or the abnormality detection circuit has failed; Equipped with The abnormality detection circuit an overvoltage detection circuit that detects an overvoltage state as the abnormal state; a low voltage detection circuit that detects a low voltage state as the abnormal state; Equipped with The driver is a diagnostic device for a switching element and an abnormality detection circuit that turns off the first switching element when the overvoltage state is detected by the overvoltage detection circuit and when the low voltage state is detected by the low voltage detection circuit.

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