Abnormality detection device

Abstract

An abnormality detection device (10) is for use in a supply system which comprises a power supply unit (90), and a first power line (92) and a second power line (93) that are provided between the power supply unit (90) and a pyrotechnic disconnect (91). The abnormality detection device comprises: a first switch (10A) for the first power line (92); a second switch (10B) for the second power line (93); a first resistor unit (10C) and a second resistor unit (10D); and a detection unit (10E). The first resistor unit (10C) is electrically connected to a first site (B1) between the power supply unit (90) and the first switch (10A) and to a second site (B2) between the second switch (10B) and the pyrotechnic disconnect (91). The second resistor unit (10D) is electrically connected to the second site (B2) and to a third site (B3) between the second switch (10B) and the power supply unit (90). The detection unit (10E) detects a voltage state at the second site (B2) at a time when the first switch (10A) and / or the second switch (10B) is in an off-state.

Description

Anomaly detection device

[0001] The present disclosure relates to an anomaly detection device.

[0002] Patent Document 1 discloses a technique for passing a test current through a squib in an airbag ignition device to detect fluctuations in resistance value due to poor connection or deterioration of the squib.

[0003] Japanese Patent Application Publication No. 6-72281

[0004] However, to ensure that the airbag is operating normally, it is preferable to check not only the squib but also the switch that passes the ignition current, that there is no break in the path from the power supply to the squib, and that the power supply voltage is normal.The same can be said for the operation of the pyrofuse initiator that cuts off the power path.

[0005] The present disclosure has been made based on the above-mentioned circumstances, and aims to provide an abnormality detection device that can detect an abnormality that occurs in a path from a power supply unit to an object to which power is supplied.

[0006] The abnormality detection device disclosed herein is used in a supply system including a power supply unit that supplies electric power, a first electric power path provided between a high potential side terminal of the power supply unit and an object to be supplied with electric power, and a second electric power path provided between a low potential side terminal of the power supply unit and the object to be supplied with electric power, and includes: a first switch provided on the first electric power path; a second switch provided on the second electric power path; a first resistor unit and a second resistor unit that form a current path; and a detection unit that detects a voltage state, wherein when the first switch is in an on state, current is allowed to flow through the first switch, and when the first switch is in an off state, current is cut off through the first switch; when the second switch is in an on state, current is allowed to flow through the second switch, and when the second switch is in an off state, current is cut off through the second switch; One end of the first resistor is electrically connected to a first portion between the power supply unit and the first switch on the first power path, and the other end of the first resistor is electrically connected to a second portion between the second switch and the power supply target on the second power path, one end of the second resistor is electrically connected to the second portion, and the other end of the second resistor is electrically connected to a third portion between the second switch and the power supply unit on the second power path, and the detection unit detects the voltage state of the second portion when control is being performed to turn off at least one of the first switch and the second switch.

[0007] According to the present disclosure, it is possible to detect an abnormality occurring in a path from a power supply unit to an object to which power is supplied.

[0008] Fig. 1 is a circuit diagram illustrating an anomaly detection device according to a first embodiment. Fig. 2 is a schematic diagram illustrating the configuration of a pyrotechnic circuit breaker. Fig. 3 is a flowchart illustrating an example of a determination operation in a detection unit of the anomaly detection device according to the first embodiment. Fig. 4 is a circuit diagram illustrating an anomaly detection device according to a second embodiment. Fig. 5 is a flowchart illustrating an example of a determination operation in a detection unit of the anomaly detection device according to the second embodiment.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] [1] The anomaly detection device disclosed herein is used in a power supply system including a power supply unit that supplies electric power, a first power path provided between a high-potential terminal of the power supply unit and an object to be powered, and a second power path provided between a low-potential terminal of the power supply unit and the object to be powered. The anomaly detection device disclosed herein includes a first switch provided in the first power path, a second switch provided in the second power path, a first resistor and a second resistor that form a current path, and a detector that detects a voltage state. When the first switch is in an on state, current is allowed through the first switch, and when the first switch is in an off state, current is cut off through the first switch. When the second switch is in an on state, current is allowed through the second switch, and when the second switch is in an off state, current is cut off through the second switch. One end of the first resistor is electrically connected to a first portion of the first power path between the power supply unit and the first switch, and the other end of the first resistor is electrically connected to a second portion of the second power path between the second switch and the object to be powered. The second resistor has one end electrically connected to the second portion, and the other end electrically connected to a third portion on the second power path between the second switch and the power supply. The detector detects the voltage state of the second portion when control is exercised to turn off at least one of the first switch and the second switch.

[0011] The abnormality detection device of [1] above is capable of operating in such a way that when power is not supplied from the power supply unit to the power supply target, the detection unit detects the voltage state of the second part and determines whether there is an abnormality in the supply system based on the detected voltage state.

[0012] [2] In the anomaly detection device of [1] above, the power supply target may have a pyrotechnic circuit breaker provided in a predetermined conductive path. The pyrotechnic circuit breaker has a conductor part that short-circuits a first conductive path and a second conductive path of the conductive path, and can cause an explosion to cut the conductor part when a predetermined current flows between the first power path and the second power path.

[0013] In the abnormality detection device of the above [2], the pyrotechnic circuit breaker cuts off the conductive path when it is driven, so by detecting the voltage at the second portion when at least one of the first switch and the second switch is turned off to prevent the pyrotechnic circuit breaker from being driven, it is possible to determine an abnormality in the supply system.

[0014] [3] In the anomaly detection device of [1] or [2] above, when an OFF instruction is given to the first switch and the second switch, the detection unit may determine whether the voltage of the second part is in an abnormal range. The abnormal range may include at least one of a voltage range equal to or less than a first threshold value that is lower than a first normal voltage, which is the voltage of the second part when the first switch and the second switch are normally in an OFF state, and a voltage range equal to or greater than a second threshold value that is higher than the first normal voltage.

[0015] In the anomaly detection device of the above [3], when the first switch and the second switch are normally turned on, the magnitude of the voltage at the second part is equal to the value obtained by dividing the output voltage of the high-potential side of the power supply unit by the first resistor unit and the second resistor unit. By comparing the first threshold value and the second threshold value based on this value with the actual voltage value at the second part, it is possible to detect a drop or rise in the power supply voltage, a break in the first power path and the second power path, and a short circuit fault in the first switch and the second switch.

[0016] [4] In the anomaly detection device of [1] or [2] above, the detection unit may determine whether the voltage of the second part is in an abnormal range when an ON instruction is given to the first switch and an OFF instruction is given to the second switch. The abnormal range may include at least one of a voltage range equal to or less than a third threshold value lower than the second normal voltage and a voltage range equal to or greater than a fourth threshold value higher than the second normal voltage. The second normal voltage may be the voltage of the second part when the first switch is normally ON and the second switch is normally OFF.

[0017] In the anomaly detection device of [4] above, when the first switch is normally on, the second switch is normally off, and the resistance value of the power supply target is normal, the voltage of the second part is a value obtained by dividing the output voltage on the high-potential side of the power supply unit by the second resistor unit and a combined resistance of the power supply target and the first resistor unit in parallel. By comparing the actual voltage value of the second part with a third threshold value and a fourth threshold value based on this value, it is possible to detect an open fault of the first switch, a poor connection of the power supply target, and a change in the resistance value of the power supply target.

[0018] [5] In the anomaly detection device of [1] or [2] above, when an OFF instruction is given to the first switch and an ON instruction is given to the second switch, the detection unit can determine whether the voltage of the second part is in an abnormal range. The abnormal range can include a voltage range equal to or greater than a fifth threshold value that is higher than a third normal voltage, which is the voltage of the second part when the first switch is normally OFF and the second switch is normally ON.

[0019] In the anomaly detection device of [5] above, when the first switch is normally turned off and the second switch is normally turned on, the voltage at the second part is the same as the voltage on the low potential side of the power supply unit. By comparing this value with a fifth threshold value based on the reference voltage, the actual voltage value at the second part can be detected as an open fault of the second switch.

[0020] [6] The abnormality detection device of [1] or [2] above may include a series component in which a third switch and a third resistor are connected in series, and one end of the series component may be electrically connected to the third portion, and the other end of the series component may be electrically connected to the second portion.

[0021] The abnormality detection device of [6] above can detect abnormalities in the supply system more precisely by adding a series component in which the third switch and the third resistor are connected in series.

[0022] [7] In the anomaly detection device of [6] above, the detection unit may determine whether the voltage of the second part is in an abnormal range when an OFF instruction is given to the first switch, the second switch, and the third switch. The abnormal range may include at least one of a voltage range equal to or less than a first threshold value that is lower than the first normal voltage, and a voltage range equal to or greater than a second threshold value that is higher than the first normal voltage. The first normal voltage may be the voltage of the second part when the first switch, the second switch, and the third switch are normally turned off.

[0023] In the anomaly detection device of [7] above, when the first switch, the second switch, and the third switch are normally in the off state, the voltage at the second part is a value obtained by dividing the output voltage of the high-potential side of the power supply part by the first resistor part and the second resistor part. By comparing the first threshold value and the second threshold value based on this value with the actual voltage value at the second part, it is possible to detect a drop or rise in the power supply voltage, a break in the first power path and the second power path, and a short circuit fault in the first switch and the second switch.

[0024] [8] In the anomaly detection device of [6] above, the detection unit may determine whether the voltage of the second part is in an abnormal range when an ON instruction is given to the first switch and the third switch and an OFF instruction is given to the second switch. The abnormal range may include at least one of a voltage range equal to or less than a third threshold value lower than the second normal voltage and a voltage range equal to or greater than a fourth threshold value higher than the second normal voltage. The second normal voltage may be the voltage of the second part when the first switch and the third switch are normally ON and the second switch is normally OFF.

[0025] In the anomaly detection device of [8] above, when the first switch and the third switch are normally in the on state, the second switch is normally in the off state, and the resistance value of the power supply target is normal, the voltage of the second part is a value obtained by dividing the output voltage on the high potential side of the power supply unit by a combined resistance of the power supply target and the first resistor unit in parallel and a combined resistance of the second resistor unit and the third resistor unit in parallel. By comparing the actual voltage value of the second part with a third threshold value and a fourth threshold value based on this value, it is possible to detect an open fault of the first switch, a poor connection of the power supply target, and a change in the resistance value of the power supply target.

[0026] [9] In the anomaly detection device of [6] above, when an OFF instruction is given to the first switch and the third switch and an ON instruction is given to the second switch, the detection unit may determine whether the voltage of the second part is in an abnormal range. The abnormal range may include a voltage range equal to or greater than a fifth threshold value that is higher than a third normal voltage, which is the voltage of the second part when the first switch and the third switch are normally OFF and the second switch is normally ON.

[0027] In the anomaly detection device of [9], when the first switch and the third switch are normally in the OFF state and the second switch is normally in the ON state, the voltage of the second part is the same as the voltage on the low potential side of the power supply unit. By comparing the actual voltage value of the second part with a fifth threshold value based on this value, it is possible to detect an open fault of the second switch.

[0028]

[10] In the abnormality detection device of [6] above, the value obtained by dividing the voltage on the high potential side of the power supply unit by the first resistor unit and the second resistor unit may be the same as the value obtained by dividing the voltage on the high potential side of the power supply unit by the third resistor unit and the power supply target.

[0029] In the abnormality detection device of

[10] above, the first normal voltage that serves as the basis for the first threshold and the second threshold can be the same as the second normal voltage that serves as the basis for the third threshold and the fourth threshold, so when the detection unit is configured with comparators, the number of comparators to be provided can be reduced.

[0030] [Details of the Embodiments of the Present Disclosure] <First Embodiment> [Summary of the Supply System] The supply system 100 shown in FIG. 1 is a system mounted on a vehicle. The supply system 100 includes a power supply unit 90, a pyrotechnic circuit breaker 91 to which power is supplied, and an abnormality detection device 10. The power supply unit 90 may be, for example, a lead battery or a lithium-ion battery. The power supply unit 90 has a high-potential terminal and a low-potential terminal. The output voltage of the power supply unit 90 (the potential difference between the high-potential terminal and the low-potential terminal) is Vo. The voltage of the low-potential terminal of the power supply unit 90 is a reference potential, which is maintained at, for example, a ground potential of 0 V. One end of a first power path 92 is electrically connected to the high-potential terminal of the power supply unit 90. One end of a second power path 93 is electrically connected to the low-potential terminal of the power supply unit 90. The first power path 92 and the second power path 93 are paths through which power is transmitted.

[0031] For example, a pyrotechnic circuit breaker 91 is used, which is a PYROFUSE (registered trademark). The pyrotechnic circuit breaker 91 is provided between a first power path 92 and a second power path 93. As shown in FIG. 2 , the pyrotechnic circuit breaker 91 has an initiator 91C, an explosive 91F, a displacement portion 91D, and a conductor portion 91E.

[0032] The initiator 91C is electrically connected to the other end of the first power path 92 and the other end of the second power path 93. The first power path 92 and the second power path 93 are provided between the power supply unit 90 and the initiator 91C. The initiator 91C is configured to generate heat when a predetermined current flows between the first power path 92 and the second power path 93 when a first switch 10A and a second switch 10B (described later) are switched from an OFF state to an ON state. The initiator 91C has a resistance value Ri. The explosive 91F is provided adjacent to the initiator 91C. The explosive 91F explodes upon receiving heat generated by the initiator 91C, generating explosive power. In other words, the initiator 91C performs an explosive operation to ignite the explosive 91F in response to the supply of power from the power supply unit 90. The explosive 91F generates explosive power when ignited. The displacement portion 91D is provided adjacent to the explosive 91F. The displacement portion 91D is suddenly displaced when subjected to the explosive force generated by the exploded explosive 91F.

[0033] The conductor portion 91E is formed, for example, of a strip-shaped conductive metal. The conductor portion 91E is electrically connected in a manner that short-circuits the first conductive path W1 and the second conductive path W2 of a predetermined conductive path W. The conductor portion 91E is disposed on the opposite side of the explosive 91F across the displacement portion 91D. The conductor portion 91E is physically cut in an extremely short time by the displacement portion 91D, which is rapidly displaced by the explosive force generated by the explosive action. As a result, the conductor portion 91E interrupts the conductive path W when it is cut. The cut conductor portion 91E will not be reconnected. In other words, the pyrotechnic circuit breaker 91 is a fuse device that cuts the conductor portion 91E by the displacement of the displacement portion 91D in response to the explosive action.

[0034] In the present disclosure, "electrically connected" preferably refers to a configuration in which the connection targets are connected in a mutually conductive state (a state in which a current can flow) so that the potentials of both connection targets are equal. However, this configuration is not limited to this. For example, "electrically connected" may also refer to a configuration in which the connection targets are connected in a mutually conductive state (a state in which a current can flow) with an electrical component interposed between them. In the present disclosure, "short-circuited" refers to a configuration in which the connection targets are "electrically connected" in a mutually conductive state (a state in which a current can flow) so that the potentials of both connection targets are equal.

[0035] As shown in FIG. 1 , the anomaly detection device 10 includes a first switch 10A, a second switch 10B, a first resistor 10C, a second resistor 10D, and a detection unit 10E. The first switch 10A is disposed on a first power path 92. The second switch 10B is disposed on a second power path 93. The first switch 10A and the second switch 10B have the function of switching between an ON state and an OFF state. When the first switch 10A and the second switch 10B are switched to the ON state, current is allowed to flow through the first switch 10A and the second switch 10B. Then, current is allowed to flow through each of the first power path 92 and the second power path 93 between the power supply unit 90 and the pyrotechnic circuit breaker 91.

[0036] When the first switch 10A and the second switch 10B are switched to the OFF state, the current flow through the first switch 10A and the second switch 10B is cut off. Then, the current flow through each of the first power path 92 and the second power path 93 is cut off between the power supply unit 90 and the pyrotechnic circuit breaker 91. For example, a relay switch such as a semiconductor relay or a mechanical relay is used as the first switch 10A and the second switch 10B.

[0037] The first resistor 10C and the second resistor 10D are electrical resistors having two terminals. The first resistor 10C has a resistance value R1, and the second resistor 10D has a resistance value R2. One end of the first resistor 10C is electrically connected to a first point B1 in a first power path 92 between the power supply 90 and the first switch 10A. The other end of the first resistor 10C is electrically connected to a second point B2 in a second power path 93 between the second switch 10B and the pyrotechnic circuit breaker 91. The first resistor 10C forms a current path between the first point B1 and the second point B2. One end of the second resistor 10D is electrically connected to a second point B2 in a second power path 93 between the second switch 10B and the pyrotechnic circuit breaker 91. The other end of the second resistor 10D is electrically connected to a third point B3 in the second power path 93 between the second switch 10B and the power supply 90. The second resistor 10D forms a current path between the second portion B2 and the third portion B3. In order to suppress dark current, it is preferable that the resistance values ​​R1 and R2 are set to sufficiently large values.

[0038] The detection unit 10E is mainly composed of, for example, a microcomputer and includes an arithmetic unit such as a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), an A / D converter, etc. The detection unit 10E is electrically connected to the second part B2 of the second power path 93 to which the other end of the second resistor 10D is electrically connected. The detection unit 10E is configured to receive the voltage value V applied to the second part B2 and detect the voltage state at the second part B2.

[0039] A first threshold value Th1, a second threshold value Th2, a third threshold value Th3, a fourth threshold value Th4, and a fifth threshold value Th5 are stored in the ROM or the like of the detection unit 10E. The detection unit 10E has a function of comparing the voltage value V of the second portion B2 with the first threshold value Th1, the second threshold value Th2, the third threshold value Th3, the fourth threshold value Th4, and the fifth threshold value Th5 to determine whether the voltage of the second portion B2 is in an abnormal state.

[0040] The first threshold value Th1 and the second threshold value Th2 are based on a first normal voltage Vd1, which is the voltage at the second part B2 when the first switch 10A and the second switch 10B are normally off. Here, the first normal voltage Vd1 is a value obtained by dividing the output voltage Vo of the power supply unit 90 by the first resistor unit 10C (resistance value R1) and the second resistor unit 10D (resistance value R2), and is expressed by the following equation 1. For example, the output voltage Vo of the power supply unit 90 is the potential difference between the high-potential terminal and the low-potential terminal of the power supply unit 90 when the power supply unit 90 is fully charged. The first normal voltage Vd1 is the voltage value obtained when the power supply unit 90 is fully charged.

[0041]

[0042] The first threshold value Th1 is smaller than the first normal voltage Vd1 by a predetermined value, and the second threshold value Th2 is larger than the first normal voltage Vd1 by a predetermined value. The values ​​of the first threshold value Th1 and the second threshold value Th2 can be changed to desired values ​​according to desired specifications.

[0043] The third threshold value Th3 and the fourth threshold value Th4 are based on a second normal voltage Vd2, which is the voltage at the second part B2 when the first switch 10A is normally ON and the second switch 10B is normally OFF. The second normal voltage Vd2 is a voltage value obtained when the power supply unit 90 is fully charged. Here, the second normal voltage Vd2 is a voltage divided by the first resistor unit 10C (resistance value R1) and the initiator 91C (resistance value Ri) connected in parallel with the second resistor unit 10D (resistance value R2), and is expressed by the following equation 2:

[0044]

[0045] The third threshold value Th3 is smaller than the second normal voltage Vd2 by a predetermined value. The fourth threshold value Th4 is larger than the second normal voltage Vd2 by a predetermined value. The values ​​of the third threshold value Th3 and the fourth threshold value Th4 can be changed to desired values ​​depending on the desired specifications.

[0046] The fifth threshold value Th5 is based on a third normal voltage Vd3, which is the voltage at the second part B2 when the first switch 10A is normally OFF and the second switch 10B is normally ON. The third normal voltage Vd3 is the same voltage (ground potential) as the low-potential terminal of the power supply unit 90. The fifth threshold value Th5 is greater than the third normal voltage Vd3 (ground potential) by a predetermined value. The value of the fifth threshold value Th5 can be changed to a desired value depending on the desired specifications.

[0047] Furthermore, the detection unit 10E can execute control to switch the first switch 10A and the second switch 10B between an OFF state and an ON state individually. Specifically, the detection unit 10E can execute first switching control, second switching control, and third switching control. The first switching control, second switching control, and third switching control are executed after the vehicle ignition switch is switched from an OFF state to an ON state. The first switching control is control to issue an OFF instruction to the first switch 10A and the second switch 10B and maintain the first switch 10A and the second switch 10B in the OFF state. The second switching control is control to issue an ON instruction to the first switch 10A and maintain the first switch 10A in the ON state, and to issue an OFF instruction to the second switch 10B and maintain the second switch 10B in the OFF state. The third switching control is a control in which an OFF instruction is given to the first switch 10A to maintain the first switch 10A in the OFF state, and an ON instruction is given to the second switch 10B to maintain the second switch 10B in the ON state.

[0048] [Example of Operation of the Anomaly Detection Device] Next, an example of operation of the anomaly detection device 10 will be described. In a vehicle equipped with the supply system 100, when the ignition switch is in the OFF state, the first switch 10A and the second switch 10B are in the OFF state. In this case, the answer is No in step S1 of FIG. 3, and the processing in FIG. 3 is terminated. In step S1, when the ignition switch is switched from the OFF state to the ON state (Yes in step S1), the processing proceeds to step S2. In step S2, the detection unit 10E issues an OFF instruction to the first switch 10A and the second switch 10B, and executes first switching control to maintain the first switch 10A and the second switch 10B in the OFF state.

[0049] The detection unit 10E acquires the voltage value V of the second portion B2. In step S2, the detection unit 10E compares the magnitude of the voltage value V with the first threshold value Th1 and the second threshold value Th2, and determines whether the voltage of the second portion B2 is within the abnormal range.

[0050] If the voltage value V is smaller than the first threshold value Th1, it is estimated that the voltage at the second location B2 is dropping due to a disconnection in the first power path 92 between the first resistor 10C and the power supply 90 or a short-circuit fault in the second switch 10B. If the voltage value V is larger than the second threshold value Th2, it is estimated that the voltage at the second location B2 is rising due to a disconnection in the second power path 93 between the second location B2 and the power supply 90 or a short-circuit fault in the first switch 10A. Therefore, if the detection unit 10E determines that the voltage value V is smaller than the first threshold value Th1 or greater than the second threshold value Th2 (No in step S2), the process proceeds to step S6. When the process proceeds to step S6, the detection unit 10E determines that the power supply system 100 is in an abnormal state and ends the process in FIG. 3 . The abnormal range of the voltage at the second part B2 in step S2 includes at least one of a voltage range equal to or less than a first threshold value Th1 that is lower than the first normal voltage Vd1, and a voltage range equal to or greater than a second threshold value Th2 that is higher than the first normal voltage Vd1. The first normal voltage Vd1 is the voltage at the second part B2 when the first switch 10A and the second switch 10B are normally in the off state. If the voltage value V is equal to or less than the second threshold value Th2 and equal to or greater than the first threshold value Th1 (Yes in step S2), the process proceeds to step S3.

[0051] In step S3, the detection unit 10E executes second switching control, which provides an ON instruction to the first switch 10A to maintain the first switch 10A in the ON state and an OFF instruction to the second switch 10B to maintain the second switch 10B in the OFF state. The detection unit 10E then determines whether the voltage at the second part B2 is within the abnormal range. In step S3, the detection unit 10E compares the magnitude of the voltage value V at the second part B2 with the third threshold value Th3 and the fourth threshold value Th4.

[0052] If the voltage value V is smaller than the third threshold value Th3, it is estimated that the voltage at the second location B2 is dropping due to an open circuit failure of the first switch 10A or an open circuit caused by poor connection between the initiator 91C and the first power path 92. If the voltage value V is larger than the fourth threshold value Th4, it is estimated that the voltage at the second location B2 is rising due to a change in the resistance value Ri caused by deterioration of the initiator 91C or a short circuit of the initiator 91C caused by poor connection between the initiator 91C and the first power path 92. Therefore, if the detection unit 10E determines that the voltage value V is smaller than the third threshold value Th3 or greater than the fourth threshold value Th4 (No in step S3), the process proceeds to step S6. When the detection unit 10E proceeds to step S6, it determines that the power supply system 100 is in an abnormal state and ends the process shown in FIG. 3 . The abnormal range of the voltage at the second part B2 in step S3 includes at least one of a voltage range equal to or less than a third threshold value Th3 that is lower than the second normal voltage Vd2, and a voltage range equal to or greater than a fourth threshold value Th4 that is higher than the second normal voltage Vd2. The second normal voltage Vd2 is the voltage at the second part B2 when the first switch 10A is normally ON and the second switch 10B is normally OFF. If the voltage value V is equal to or less than the fourth threshold value Th4 and equal to or greater than the third threshold value Th3 (Yes in step S3), the process proceeds to step S4.

[0053] In step S4, the detection unit 10E executes third switching control, which involves issuing an OFF instruction to the first switch 10A to maintain the first switch 10A in the OFF state, and issuing an ON instruction to the second switch 10B to maintain the second switch 10B in the ON state. The detection unit 10E then determines whether the voltage at the second part B2 is within the abnormal range. In step S4, the detection unit 10E compares the magnitude of the voltage value V at the second part B2 with the fifth threshold value Th5.

[0054] If the voltage value V is greater than the fifth threshold Th5, it is estimated that the voltage at the second location B2 is rising due to an open circuit failure of the second switch 10B. Therefore, if the detection unit 10E determines that the voltage value V is greater than the fifth threshold Th5 (No in step S4), the process proceeds to step S6, where the detection unit 10E determines that the power supply system 100 is in an abnormal state and terminates the process in FIG. 3 . If the voltage value V is equal to or less than the fifth threshold Th5 (Yes in step S4), the process proceeds to step S5. If the detection unit 10E transitions to step S5, it determines that the power supply system 100 is in a normal state and terminates the process in FIG. 3 . The abnormal range of the voltage at the second location B2 in step S4 includes a voltage range equal to or greater than the fifth threshold Th5, which is greater than the third normal voltage Vd3, which is the voltage at the second location B2 when the first switch 10A is normally OFF and the second switch 10B is normally ON. In this way, the detection unit 10E detects the voltage state of the second part B2 when control is being exercised to turn off at least one of the first switch 10A and the second switch 10B.

[0055] Next, the effects of this configuration will be illustrated. The abnormality detection device 10 is used in a power supply system 100 including a power supply unit 90 that supplies electric power, a first power path 92 provided between a high-potential terminal of the power supply unit 90 and a pyrotechnic circuit breaker 91, and a second power path 93 provided between a low-potential terminal of the power supply unit 90 and the pyrotechnic circuit breaker 91. The abnormality detection device 10 includes a first switch 10A provided on the first power path 92, a second switch 10B provided on the second power path 93, a first resistor 10C and a second resistor 10D that form a current path, and a detector 10E that detects a voltage state. When the first switch 10A is in an on state, current is allowed to flow through the first switch 10A, and when the first switch 10A is in an off state, current is cut off through the first switch 10A. When the second switch 10B is in the on state, current is allowed to flow through the second switch 10B, and when the second switch 10B is in the off state, current is cut off through the second switch 10B. One end of the first resistor 10C is electrically connected to a first portion B1 on the first power path 92 between the power supply 90 and the first switch 10A. The other end of the first resistor 10C is electrically connected to a second portion B2 on the second power path 93 between the second switch 10B and the pyrotechnic circuit breaker 91. One end of the second resistor 10D is electrically connected to the second portion B2, and the other end of the second resistor 10D is electrically connected to a third portion B3 on the second power path 93 between the second switch 10B and the power supply 90. The detector 10E detects the voltage state at the second portion B2 when at least one of the first switch 10A and the second switch 10B is controlled to be in the off state.

[0056] According to this configuration, when power is not supplied from the power supply unit 90 to the pyrotechnic circuit breaker 91, the detection unit 10E detects the voltage state of the second part B2, and based on the detected voltage state, it becomes possible to determine whether there is an abnormality in the supply system 100.

[0057] In the abnormality detection device 10, the pyrotechnic circuit breaker 91 is provided in a predetermined conductive path W. The pyrotechnic circuit breaker 91 has a conductor portion 91E that short-circuits a first conductive path W1 and a second conductive path W2 of the conductive path W, and explodes to cut off the conductor portion 91E when a predetermined current flows between a first power path 92 and a second power path 93. With this configuration, the pyrotechnic circuit breaker 91 cuts off the conductive path W when activated. Therefore, an abnormality in the power supply system 100 can be determined by detecting the voltage at the second portion B2 when at least one of the first switch 10A and the second switch 10B is turned off to prevent the pyrotechnic circuit breaker from being activated.

[0058] In the abnormality detection device 10, the detection unit 10E determines whether the voltage at the second node B2 is in the abnormal range when an OFF instruction is given to the first switch 10A and the second switch 10B. The abnormal range includes at least one of a voltage range equal to or less than a first threshold value Th1 that is lower than a first normal voltage Vd1 and a voltage range equal to or greater than a second threshold value Th2 that is higher than the first normal voltage Vd1. The first normal voltage Vd1 is the voltage at the second node B2 when the first switch 10A and the second switch 10B are normally OFF. With this configuration, when the first switch 10A and the second switch 10B are normally ON, the voltage at the second node B2 becomes the first normal voltage Vd1, which is obtained by dividing the output voltage Vo on the high-potential side of the power supply unit 90 by the first resistor unit 10C and the second resistor unit 10D. By comparing the first threshold value Th1 and the second threshold value Th2 based on this value with the actual voltage value V of the second part B2, it is possible to detect a drop or rise in the power supply voltage, a break in the first power path 92 and the second power path 93, and a short circuit failure in the first switch 10A and the second switch 10B.

[0059] In the abnormality detection device 10, the detection unit 10E determines whether the voltage at the second part B2 is in the abnormal range when an ON instruction is given to the first switch 10A and an OFF instruction is given to the second switch 10B. The abnormal range includes at least one of a voltage range equal to or less than a third threshold value Th3 that is lower than the second normal voltage Vd2 and a voltage range equal to or greater than a fourth threshold value Th4 that is higher than the second normal voltage Vd2. The second normal voltage Vd2 is the voltage at the second part B2 when the first switch 10A is normally ON and the second switch 10B is normally OFF. According to this configuration, when the first switch 10A is normally in the on state, the second switch 10B is normally in the off state, and the resistance value Ri of the initiator 91C of the pyrotechnic circuit breaker 91 is normal, the voltage at the second part B2 is a value obtained by dividing the output voltage Vo on the high potential side of the power supply part 90 by the combined resistance of the initiator 91C and the first resistor part 10C connected in parallel, and the second resistor part 10D. By comparing the third threshold value Th3 and the fourth threshold value Th4 based on this value with the actual voltage value V at the second part B2, it is possible to detect an open fault of the first switch 10A, a poor connection of the pyrotechnic circuit breaker 91, and a change in the resistance value Ri of the initiator 91C of the pyrotechnic circuit breaker 91.

[0060] In the anomaly detection device 10, the detection unit 10E determines whether the voltage at the second node B2 is in the abnormal range when an OFF instruction is given to the first switch 10A and an ON instruction is given to the second switch 10B. The abnormal range includes a voltage range equal to or greater than a fifth threshold value Th5, which is higher than a third normal voltage Vd3, which is the voltage at the second node B2 when the first switch 10A is normally OFF and the second switch 10B is normally ON. With this configuration, when the first switch 10A is normally OFF and the second switch 10B is normally ON, the voltage at the second node B2 is the same as the voltage on the low-potential side of the power supply unit 90. By comparing the fifth threshold value Th5, which is based on this value, with the actual voltage value V at the second node B2, an open circuit failure of the second switch 10B can be detected. <Embodiment 2> Next, an anomaly detection device 110 according to a second embodiment will be described with reference to FIGS. 4 and 5. The second embodiment differs from the first embodiment in that it includes a third switch 10H and a third resistor 10J, and in the operation of the detector 10E. The same components as those in the first embodiment are denoted by the same reference numerals, and the same functions and effects as those in the first embodiment will not be described.

[0061] The third switch 10H is, for example, a relay switch such as a semiconductor relay or a mechanical relay. The third resistor unit 10J is, for example, an electrical resistor having two terminals. The resistance value of the third resistor unit 10J is R3. The third switch 10H and the third resistor unit 10J are electrically connected in series to form a series-component unit 10K. As shown in FIG. 4 , one end of the third switch 10H, which is one end of the series-component unit 10K, is electrically connected to the third part B3. The other end of the third resistor unit 10J, which is the other end of the series-component unit 10K, is electrically connected to the second part B2. The series-component unit 10K, the second resistor unit 10D, and the second switch 10B are electrically connected in parallel.

[0062] A first threshold value Th11, a second threshold value Th22, a third threshold value Th33, a fourth threshold value Th44, and a fifth threshold value Th55 are stored in the ROM or the like of the detection unit 10E. The detection unit 10E has a function of comparing the voltage value V of the second portion B2 with the first threshold value Th11, the second threshold value Th22, the third threshold value Th33, the fourth threshold value Th44, and the fifth threshold value Th55 to determine whether the voltage of the second portion B2 is in an abnormal state.

[0063] The first threshold value Th11 and the second threshold value Th22 are based on a first normal voltage Vd1, which is the voltage at the second part B2 when the first switch 10A, the second switch 10B, and the third switch 10H are normally in the off state. The first normal voltage Vd1 is a value obtained by dividing the output voltage Vo of the power supply unit 90 by the first resistor unit 10C (resistance value R1) and the second resistor unit 10D (resistance value R2), and is expressed by Equation 1 in the first embodiment.

[0064] The first threshold value Th11 is smaller than the first normal voltage Vd1 by a predetermined value. The second threshold value Th22 is larger than the first normal voltage Vd1 by a predetermined value. The values ​​of the first threshold value Th11 and the second threshold value Th22 can be changed to desired values ​​according to desired specifications.

[0065] The third threshold value Th33 and the fourth threshold value Th44 are based on a second normal voltage Vd2, which is the voltage at the second part B2 when the first switch 10A and the third switch 10H are normally on and the second switch 10B is normally off. Here, the second normal voltage Vd2 is a voltage divided by the first resistor 10C (resistance value R1) and the initiator 91C (resistance value Ri) connected in parallel and the second resistor 10D (resistance value R2) and the third resistor 10J (resistance value R3) connected in parallel, and is expressed by the following equation 3.

[0066]

[0067] The third threshold value Th33 is smaller than the second normal voltage Vd2 by a predetermined value. The fourth threshold value Th44 is larger than the second normal voltage Vd2 by a predetermined value. The values ​​of the third threshold value Th33 and the fourth threshold value Th44 can be changed to desired values ​​depending on the desired specifications.

[0068] The fifth threshold value Th55 is based on a third normal voltage Vd3, which is the voltage at the second part B2 when the first switch 10A and the third switch 10H are normally OFF and the second switch 10B is normally ON. The third normal voltage Vd3 is the same voltage (ground potential) as the low-potential terminal of the power supply unit 90. The fifth threshold value Th55 is greater than the third normal voltage Vd3 by a predetermined value. The value of the fifth threshold value Th55 can be changed to a desired value depending on the desired specifications.

[0069] The first switching control in the detection unit 10E is control to maintain the first switch 10A, the second switch 10B, and the third switch 10H in the OFF state. The second switching control in the detection unit 10E is control to maintain the first switch 10A and the third switch 10H in the ON state and the second switch 10B in the OFF state. The third switching control in the detection unit 10E is control to maintain the first switch 10A and the third switch 10H in the OFF state and the second switch 10B in the ON state.

[0070] [Example of Operation of the Anomaly Detection Device] Next, an example of operation of the anomaly detection device 110 will be described. In a vehicle equipped with the supply system 200, when the ignition switch is in the OFF state, the first switch 10A, the second switch 10B, and the third switch 10H are in the OFF state. For example, in step S11 in Fig. 5, when the ignition switch is switched from the OFF state to the ON state (Yes in step S1), the process proceeds to step S12. In step S12, the detection unit 10E executes first switching control to maintain the first switch 10A, the second switch 10B, and the third switch 10H in the OFF state.

[0071] The detection unit 10E acquires the voltage value V of the second part B2. In step S12, the detection unit 10E compares the magnitude of the voltage value V with the first threshold value Th11 and the second threshold value Th22, and determines whether the voltage of the second part B2 is within the abnormal range.

[0072] If the voltage value V is smaller than the first threshold value Th11, it is estimated that the voltage at the second location B2 is dropping due to a disconnection in the first power path 92 between the first resistor 10C and the power supply 90 or a short-circuit fault in the second switch 10B. If the voltage value V is larger than the second threshold value Th22, it is estimated that the voltage at the second location B2 is rising due to a disconnection in the second power path 93 between the second location B2 and the power supply 90 or a short-circuit fault in the first switch 10A. Therefore, if the detection unit 10E determines that the voltage value V is smaller than the first threshold value Th11 or greater than the second threshold value Th22 (No in step S12), the process proceeds to step S16. When the process proceeds to step S16, the detection unit 10E determines that the power supply system 200 is in an abnormal state and terminates the process in FIG. 5 . The abnormal range of the voltage at the second part B2 in step S12 includes at least one of a voltage range equal to or less than a first threshold value Th11 that is lower than the first normal voltage Vd1 and a voltage range equal to or greater than a second threshold value Th22 that is higher than the first normal voltage Vd1. The first normal voltage Vd1 is the voltage at the second part B2 when the first switch 10A, the second switch 10B, and the third switch 10H are normally in the off state. If the voltage value V is equal to or less than the second threshold value Th22 and equal to or greater than the first threshold value Th11 (Yes in step S12), the process proceeds to step S13.

[0073] In step S13, the detection unit 10E executes second switching control to maintain the first switch 10A and the third switch 10H in the ON state and the second switch 10B in the OFF state. The detection unit 10E then determines whether the voltage at the second part B2 is within the abnormal range. In step S13, the detection unit 10E compares the magnitude of the voltage value V at the second part B2 with the third threshold value Th33 and the fourth threshold value Th44.

[0074] If the voltage value V is smaller than the third threshold value Th33, it is estimated that the voltage at the second portion B2 is dropping due to an open failure of the first switch 10A, an increase in the resistance value Ri due to deterioration of the initiator 91C, or an open circuit due to poor connection between the initiator 91C and the first power path 92. If the voltage value V is larger than the fourth threshold value Th44, it is estimated that the voltage at the second portion B2 is rising due to a decrease in the resistance value Ri due to deterioration of the initiator 91C, or a short circuit of the initiator 91C due to poor connection between the initiator 91C and the first power path 92. Therefore, if the detection unit 10E determines that the voltage value V is smaller than the third threshold value Th33 or greater than the fourth threshold value Th44 (No in step S13), the process proceeds to step S16. When the process proceeds to step S16, the detection unit 10E determines that the supply system 200 is in an abnormal state, and the process in Fig. 5 ends. The abnormal range of the voltage at the second location B2 in step S13 includes at least one of a voltage range equal to or less than a third threshold value Th33, which is lower than the second normal voltage Vd2, and a voltage range equal to or greater than a fourth threshold value Th44, which is higher than the second normal voltage Vd2. The second normal voltage Vd2 is the voltage at the second location B2 when the first switch 10A and the third switch 10H are normally on and the second switch 10B is normally off. If the voltage value V is equal to or less than the third threshold value Th33 and equal to or greater than the fourth threshold value Th44 (Yes in step S13), the process proceeds to step S14.

[0075] In step S14, the detection unit 10E executes third switching control to maintain the first switch 10A and the third switch 10H in the OFF state and the second switch 10B in the ON state. Then, the detection unit 10E determines whether the voltage at the second part B2 is within the abnormal range. In step S14, the detection unit 10E compares the magnitude of the voltage value V at the second part B2 with the fifth threshold value Th55.

[0076] If the voltage value V is greater than the fifth threshold value Th55, it is estimated that the voltage at the second location B2 is rising due to an open circuit failure of the second switch 10B. Therefore, if the detection unit 10E determines that the voltage value V is greater than the fifth threshold value Th55 (No in step S14), the process proceeds to step S16, where the detection unit 10E determines that the supply system 200 is in an abnormal state and terminates the process in FIG. 5 . If the voltage value V is equal to or less than the fifth threshold value Th55 (Yes in step S14), the process proceeds to step S15. If the detection unit 10E proceeds to step S15, it determines that the supply system 200 is in a normal state and terminates the process in FIG. 5 . The abnormal range of the voltage at the second location B2 in step S14 includes a voltage range equal to or greater than the fifth threshold value Th55, which is greater than the third normal voltage Vd3. The third normal voltage Vd3 is the voltage at the second portion B2 when the first switch 10A and the third switch 10H are normally in the OFF state and the second switch 10B is normally in the ON state.

[0077] In addition, when the configuration is such that the voltage value V is compared with each threshold value using a comparator, it is preferable to set the resistance values ​​of the first resistor unit 10C, the second resistor unit 10D, the third resistor unit 10J, and the initiator 91C so that the value obtained by dividing the voltage on the high potential side of the power supply unit 90 by the first resistor unit 10C and the second resistor unit 10D is the same as the value obtained by dividing the voltage on the high potential side of the power supply unit 90 by the third resistor unit 10J and the initiator 91C.

[0078] The abnormality detection device 110 includes a series-connected unit 10K in which a third switch 10H and a third resistor 10J are connected in series, with one end of the series-connected unit 10K electrically connected to the third part B3 and the other end of the series-connected unit 10K electrically connected to the second part B2. With this configuration, by adding another series-connected unit 10K in which the third switch 10H and the third resistor 10J are connected in series, abnormalities in the supply system 200 can be detected more precisely.

[0079] In the abnormality detection device 110, the detection unit 10E determines whether the voltage at the second part B2 is in the abnormal range when an OFF instruction is given to the first switch 10A, the second switch 10B, and the third switch 10H. The abnormal range includes at least one of a voltage range equal to or less than a first threshold value Th11, which is lower than the first normal voltage Vd1, and a voltage range equal to or greater than a second threshold value Th22, which is higher than the first normal voltage Vd1. The first normal voltage Vd1 is the voltage at the second part B2 when the first switch 10A, the second switch 10B, and the third switch 10H are normally OFF. With this configuration, when the first switch 10A, the second switch 10B, and the third switch 10H are normally OFF, the voltage at the second part B2 becomes the first normal voltage Vd1, which is obtained by dividing the output voltage Vo on the high-potential side of the power supply unit 90 by the first resistor unit 10C and the second resistor unit 10D. By comparing the first threshold value Th11 and the second threshold value Th22 based on this value with the actual voltage value V of the second part B2, it is possible to detect a drop or rise in the power supply voltage, a break in the first power path 92 and the second power path 93, and a short circuit failure in the first switch 10A and the second switch 10B.

[0080] In the abnormality detection device 110, the detection unit 10E determines whether the voltage at the second part B2 is in the abnormal range when an ON instruction is given to the first switch 10A and the third switch 10H and an OFF instruction is given to the second switch 10B. The abnormal range includes at least one of a voltage range equal to or less than a third threshold value Th33 that is lower than the second normal voltage Vd2 and a voltage range equal to or greater than a fourth threshold value Th44 that is higher than the second normal voltage Vd2. The second normal voltage Vd2 is the voltage at the second part B2 when the first switch 10A and the third switch 10H are normally ON and the second switch 10B is normally OFF. According to this configuration, when the first switch 10A and the third switch 10H are normally in the on state, the second switch 10B is normally in the off state, and the resistance value Ri of the initiator 91C of the pyrotechnic circuit breaker 91 is normal, the voltage at the second part B2 is a value obtained by dividing the output voltage Vo on the high potential side of the power supply part 90 by the combined resistance of the initiator 91C and the first resistor part 10C connected in parallel and the combined resistance of the second resistor part 10D and the third resistor part 10J connected in parallel. By comparing the third threshold value Th33 and the fourth threshold value Th44, which are based on this value, with the actual voltage value V at the second part B2, it is possible to detect an open fault of the first switch 10A, a poor connection of the pyrotechnic circuit breaker 91, and a change in the resistance value Ri of the initiator 91C of the pyrotechnic circuit breaker 91.

[0081] In the abnormality detection device 110, the detection unit 10E determines whether the voltage at the second part B2 is in the abnormal range when an OFF instruction is given to the first switch 10A and the third switch 10H and an ON instruction is given to the second switch 10B. The abnormal range includes a voltage range equal to or greater than a fifth threshold value Th55, which is higher than a third normal voltage Vd3, which is the voltage at the second part B2 when the first switch 10A and the third switch 10H are normally OFF and the second switch 10B is normally ON. With this configuration, when the first switch 10A and the third switch 10H are normally OFF and the second switch 10B is normally ON, the voltage at the second part B2 is the same as the voltage on the low-potential side of the power supply unit 90. By comparing the fifth threshold value Th55, which is based on this value, with the actual voltage value V at the second part B2, an open circuit fault in the second switch 10B can be detected.

[0082] In the abnormality detection device 110, the value obtained by dividing the output voltage Vo on the high potential side of the power supply unit 90 by the first resistor unit 10C and the second resistor unit 10D is the same as the value obtained by dividing the output voltage Vo on the high potential side of the power supply unit 90 by the third resistor unit 10J and the initiator 91C of the pyrotechnic circuit breaker 91. With this configuration, the first normal voltage Vd1, which is the reference for the first threshold value Th11 and the second threshold value Th22, and the second normal voltage Vd2, which is the reference for the third threshold value Th33 and the fourth threshold value Th44, can be made the same. Therefore, when the detection unit 10E is configured with comparators, the number of comparators to be provided can be reduced.

[0083] <Other Embodiments> The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0084] Unlike the first and second embodiments, the first switching control, the second switching control, and the third switching control may be executed in a different order.

[0085] This abnormality detection device may be applied to a system that supplies current to a squib of an airbag.

[0086] Unlike the second embodiment, one end of the third switch, which is one end of the series configuration part, may be electrically connected to the second part, and the other end of the third resistor part, which is the other end of the series configuration part, may be electrically connected to the third part.

[0087] The first resistance section, the second resistance section, and the third resistance section may each be composed of a plurality of elements such as an inductor and a capacitor in addition to the resistance element.

[0088] DESCRIPTION OF SYMBOLS 10, 110... Abnormality detection device 10A... First switch 10B... Second switch 10C... First resistor section 10D... Second resistor section 10E... Detection section 10H... Third switch 10J... Third resistor section 10K... Series configuration section 90... Power supply section 91... Pyrotechnic circuit breaker 91C... Initiator 91D... Displacement section 91E... Conductor section 91F... Explosive 92... First power path 93... Second power path 100, 200... Supply system B1... First section B2... Second section B3... Third section R1... Resistance value of first resistor section R2... Resistance value of second resistor section R3... Resistance value of third resistor section Ri... Resistance value of initiator Th1, Th11... First threshold value Th2, Th22... Second threshold value Th3, Th33...Third threshold value Th4, Th44...Fourth threshold value Th5, Th55...Fifth threshold value V...Voltage value of second portion Vd1...First normal voltage Vd2...Second normal voltage Vd3...Third normal voltage Vo...Output voltage of power supply unit W...Conductive path W1...First conductive path W2...Second conductive path

Claims

1. A power supply system including a power supply unit that supplies power, a first power path provided between a high-potential terminal of the power supply unit and an object to be supplied with power, and a second power path provided between a low-potential terminal of the power supply unit and the object to be supplied with power, the power supply system including a first switch provided on the first power path, a second switch provided on the second power path, a first resistor and a second resistor that form a current path, and a detector that detects a voltage state, wherein when the first switch is in an on state, current is allowed to flow through the first switch, and when the first switch is in an off state, current is allowed to flow through the second switch, and when the second switch is in an on state, current is allowed to flow through the second switch, and when the second switch is in an off state, current is cut off through the second switch, one end of the first resistor is electrically connected to a first portion of the first power path between the power supply unit and the first switch, and the other end of the first resistor is electrically connected to a second portion of the second power path between the second switch and the object to be supplied with power, an anomaly detection device, wherein one end of the second resistor is electrically connected to the second portion, and the other end of the second resistor is electrically connected to a third portion between the second switch and the power supply portion in the second power path, and the detection portion detects the voltage state of the second portion when control is being performed to turn off at least one of the first switch and the second switch.

2. The abnormality detection device according to claim 1, wherein the power supply target has a pyrotechnic circuit breaker provided in a predetermined conductive path, the pyrotechnic circuit breaker having a conductor part that short-circuits a first conductive path and a second conductive path of the conductive path, and when a predetermined current flows between the first power path and the second power path, an explosion occurs, cutting off the conductor part.

3. The abnormality detection device according to claim 1 or 2, wherein the detection unit determines whether the voltage of the second part is in an abnormal range when an OFF instruction is given to the first switch and the second switch, and the abnormal range includes at least one of a voltage range equal to or less than a first threshold value that is smaller than a first normal voltage, which is the voltage of the second part when the first switch and the second switch are normally in an OFF state, and a voltage range equal to or greater than a second threshold value that is larger than the first normal voltage.

4. The abnormality detection device of claim 1 or 2, wherein the detection unit determines whether the voltage of the second part is in an abnormal range when an ON instruction is given to the first switch and an OFF instruction is given to the second switch, and the abnormal range includes at least one of a voltage range equal to or less than a third threshold value that is smaller than a second normal voltage, which is the voltage of the second part when the first switch is normally ON and the second switch is normally OFF, and a voltage range equal to or greater than a fourth threshold value that is larger than the second normal voltage.

5. The abnormality detection device according to claim 1 or claim 2, wherein the detection unit determines whether the voltage of the second part is in an abnormal range when an OFF instruction is given to the first switch and an ON instruction is given to the second switch, and the abnormal range includes a voltage range equal to or greater than a fifth threshold value that is greater than a third normal voltage, which is the voltage of the second part when the first switch is normally OFF and the second switch is normally ON.

6. An anomaly detection device as described in claim 1 or claim 2, further comprising a series component in which a third switch and a third resistor are connected in series, one end of the series component being electrically connected to the third part and the other end of the series component being electrically connected to the second part.

7. The abnormality detection device described in claim 6, wherein the detection unit determines whether the voltage of the second part is in an abnormal range when an OFF instruction is given to the first switch, the second switch, and the third switch, and the abnormal range includes at least one of a voltage range equal to or less than a first threshold value that is smaller than a first normal voltage, which is the voltage of the second part when the first switch, the second switch, and the third switch are normally in an OFF state, and a voltage range equal to or greater than a second threshold value that is larger than the first normal voltage.

8. The abnormality detection device described in claim 6, wherein the detection unit determines whether the voltage of the second part is within an abnormal range when an ON instruction is given to the first switch and the third switch and an OFF instruction is given to the second switch, and the abnormal range includes at least one of a voltage range equal to or less than a third threshold value that is smaller than a second normal voltage, which is the voltage of the second part when the first switch and the third switch are normally ON and the second switch is normally OFF, and a voltage range equal to or greater than a fourth threshold value that is larger than the second normal voltage.

9. The abnormality detection device described in claim 6, wherein the detection unit determines whether the voltage of the second part is within an abnormal range when an OFF instruction is given to the first switch and the third switch and an ON instruction is given to the second switch, and the abnormal range includes a voltage range equal to or greater than a fifth threshold value that is greater than a third normal voltage, which is the voltage of the second part when the first switch and the third switch are normally OFF and the second switch is normally ON.

10. An abnormality detection device as described in claim 6, wherein the value obtained by dividing the voltage on the high potential side of the power supply unit by the first resistor unit and the second resistor unit is the same as the value obtained by dividing the voltage on the high potential side of the power supply unit by the third resistor unit and the power supply target.

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