Failure detection circuit and failure detection method

Abstract

A failure detection circuit (10) is a circuit for detecting the failure of a current sensor (20) that detects current flowing through a current path (200) connecting an HV battery (1) and a load (3). The failure detection circuit (10) includes a current source (140) and a control circuit (100). The current source (140) causes a current having a predetermined current value to flow to a current detection section (210), of the current path (200), where the current sensor (20) detects the current. The control circuit (100) carries out detection of the failure of the current sensor (20) on the basis of the value of the current of the current detected by the current sensor (20) when the current having the predetermined current value flows to the current detection section (210).

Description

Fault detection circuit and fault detection method

[0001] The present disclosure relates to a fault detection circuit and a fault detection method for detecting a fault in a current sensor.

[0002] Patent Document 1 describes a system that causes a fuse to break a current path based on the current value detected by a current sensor.

[0003] JP 2015-91199 A

[0004] However, in the system described in Patent Document 1, if the current sensor fails, the system may be erroneously shut off even when no overcurrent is flowing due to erroneous current detection, or may not be shut off even when an overcurrent is flowing. For example, it is possible to provide multiple current sensors for redundancy in order to detect a current sensor failure, but this increases costs.

[0005] Therefore, the present disclosure provides a failure detection circuit and the like that can detect a failure in a current sensor without providing multiple current sensors.

[0006] The fault detection circuit of the present disclosure is a fault detection circuit that detects a fault in a current sensor that detects a current flowing in a current path connecting a power supply and a load, and includes a current source and a control circuit, wherein the current source flows a current of a predetermined current value to a current detection portion in the current path where the current sensor detects a current, and the control circuit detects a fault in the current sensor based on the current value of the current detected by the current sensor when the current of the predetermined current value flows to the current detection portion.

[0007] The fault detection method disclosed herein is a fault detection method executed by a fault detection circuit that detects a fault in a current sensor that detects a current flowing in a current path connecting a power supply and a load, wherein the fault detection circuit includes a current source, and the fault detection method includes the steps of: flowing a current of a predetermined current value from the current source to a current detection portion in the current path where the current sensor detects the current; and detecting a fault in the current sensor based on the current value of the current detected by the current sensor when the current of the predetermined current value is flowed to the current detection portion.

[0008] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0009] According to the failure detection circuit and the like according to one aspect of the present disclosure, a failure of a current sensor can be detected without providing multiple current sensors.

[0010] FIG. 1 is a configuration diagram showing an example of a battery cutoff system according to a first embodiment. FIG. 2 is a flowchart showing an example of the operation of a failure detection circuit according to the first embodiment. FIG. 3 is a diagram for explaining predetermined conditions. FIG. 4 is a flowchart showing an example of a method for detecting a failure of a current sensor. FIG. 5 is a flowchart showing another example of a method for detecting a failure of a current sensor. FIG. 6 is a configuration diagram showing an example of a battery cutoff system according to a second embodiment. FIG. 7 is a configuration diagram showing a specific example of a battery cutoff system according to a third embodiment. FIG. 8 is a flowchart showing an example of the operation of a failure detection circuit and a host ECU according to the third embodiment. FIG. 9 is a flowchart showing an example of a failure detection method according to another embodiment.

[0011] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0012] The embodiments described below are all comprehensive or specific examples, and the numerical values, shapes, materials, components, arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0013] First Embodiment A failure detection circuit according to a first embodiment will be described below.

[0014] FIG. 1 is a configuration diagram showing an example of a battery cutoff system 2 according to the first embodiment. For example, the battery cutoff system 2 is used in a transport device that includes an HV battery (high voltage battery) 1, a load 3, and the like. In addition to the battery cutoff system 2, FIG. 1 also shows the HV battery 1 and the load 3 that are provided in the transport device. As shown in FIG. 1, the HV battery 1 and the load 3 are provided outside the battery cutoff system 2. The battery cutoff system 2 is used in the transport device, for example, an electric vehicle.

[0015] The HV battery 1 is, for example, a power source capable of applying a high voltage (for example, several hundred volts) to the load 3. For example, the HV battery 1 is a main battery (for example, a lithium-ion battery) in an electric vehicle.

[0016] The load 3 is, for example, a motor and inverter of an electric vehicle. The electric vehicle is propelled by power supplied from the HV battery 1 to the load 3. In the event of an accident or the like, a large current due to a short circuit may flow in the current path 200 connecting the HV battery 1 and the load 3, which may cause the HV battery 1 to smoke or catch fire. Therefore, the battery cutoff system 2 is used in transportation equipment.

[0017] The battery shutoff system 2 is a system for shutting off a current path 200 connecting the HV battery 1 and the load 3. The current path 200 may be a path connecting the positive terminal of the HV battery 1 and the positive terminal of the load 3, or may be a path connecting the negative terminal of the HV battery 1 and the negative terminal of the load 3. Note that the current path 200 can be shut off by cutting a wiring (e.g., a bus bar) through which a current flows, or by turning off a relay that is inserted in the current path 200 and forms part of the current path 200.

[0018] The battery cutoff system 2 includes a fault detection circuit 10 , a current sensor 20 , a cutoff device 30 , a main relay 40 , a sub-relay 41 , a pre-charge relay 42 and a pre-charge resistor 43 .

[0019] The current sensor 20 is a sensor that detects the current flowing in a current path 200 that connects the HV battery 1 and the load 3. For example, the current sensor 20 is a shunt-type sensor that detects the current using a shunt resistor (e.g., several tens of μΩ). The current sensor 20 outputs information corresponding to the current value of the detected current (e.g., a voltage generated when the current flows through the shunt resistor) to the fault detection circuit 10. Note that the current sensor 20 may be a non-contact current sensor, or may detect the current using a Hall element or the like.

[0020] The current sensor 20 detects the current flowing in the current path 200 at a current detection portion 210 of the current path 200. For example, when the current sensor 20 detects the current using a shunt resistor, the shunt resistor is inserted into the current detection portion 210 of the current path 200 to form part of the current path 200. For example, when the current sensor 20 detects the current using a Hall element or the like, the Hall element detects a magnetism generated by the current flowing in the current detection portion 210 of the current path 200.

[0021] The interrupting device 30 is a device for interrupting the current path 200 when a large current flows through the current path 200 due to a short circuit abnormality. For example, the interrupting device 30 is a pyrotechnic interrupting device (irreversible interrupting device, irreversible pyrotechnic interrupting device), and interrupts the current path 200 by irreversibly cutting the current path 200 in the event of an abnormality. Note that the interrupting device 30 may be a mechanical relay inserted in the current path 200, and may interrupt the current path 200 by turning off the mechanical relay in the event of an abnormality. For example, the interrupting device 30 is provided in the current path 200 connecting the positive terminal of the HV battery 1 and the positive terminal of the load 3, and interrupts the current path 200 in response to a drive signal from the fault detection circuit 10.

[0022] The main relay 40 and the sub-relay 41 are provided on a current path 200 connecting the HV battery 1 and the load 3, and when the main relay 40 and the sub-relay 41 are turned on, power can be supplied from the HV battery 1 to the load 3. Note that when a relay is turned on, it means that the relay is in a conductive state, and when a relay is turned off, it means that the relay is in a non-conductive state. For example, the main relay 40 is provided on the current path 200 connecting the positive terminal of the HV battery 1 and the positive terminal of the load 3, and the sub-relay 41 is provided on the current path 200 connecting the negative terminal of the HV battery 1 and the negative terminal of the load 3.

[0023] If both the main relay 40 and the sub-relay 41 are turned on when starting up the transport equipment, an inrush current will flow. Therefore, the battery cutoff system 2 is provided with a pre-charge relay 42 and a pre-charge resistor 43 as a countermeasure against the inrush current.

[0024] The precharge relay 42 and the precharge resistor 43 are connected in series, and the circuit in which the precharge relay 42 and the precharge resistor 43 are connected in series is connected in parallel with the main relay 40. For example, when starting up the transportation equipment, the main relay 40 is turned off, the sub-relay 41 is turned on, and the precharge relay 42 is turned on. This allows current to flow to the load 3 via the precharge resistor 43, thereby suppressing the occurrence of inrush current. For example, after the voltage of a smoothing capacitor (not shown) connected to the load 3 becomes approximately the same as the voltage of the HV battery 1 in about 0.1 s, the precharge relay 42 is turned off and the main relay 40 is turned on, starting operation of the load 3. For example, the main relay 40, the sub-relay 41, and the precharge relay 42 are controlled by a host ECU (Electronic Control Unit) or the like provided outside the battery cutoff system 2.

[0025] Although not shown, the battery cutoff system 2 may include a voltage detection circuit that detects the voltage of the load 3 and the voltage of the HV battery 1.

[0026] As shown in FIG. 1 , a fault detection circuit 10 is provided in a battery shutoff system 2 used in, for example, transportation equipment. The fault detection circuit 10 includes a control circuit 100, a shutoff control circuit 110, and a current source 140. The control circuit 100 and the shutoff control circuit 110 are realized, for example, by a microcontroller unit (MCU). Note that the control circuit 100 and the shutoff control circuit 110 may also be realized, for example, by an application specific integrated circuit (ASIC). For example, the control circuit 100, the shutoff control circuit 110, and the current source 140 are mounted on a single board to form the fault detection circuit 10.

[0027] The current source 140 passes a current of a predetermined current value to a current detection portion 210 in the current path 200 where the current sensor 20 detects the current. The predetermined current value is not particularly limited, but is, for example, about several amperes. The current source 140 is connected in parallel with the current detection portion 210. Specifically, one end of the current source 140 is connected to one end 211 of the current detection portion 210 (e.g., one end of a shunt resistor included in the current sensor 20), and the other end of the current source 140 is connected to the other end 212 of the current detection portion 210 (e.g., the other end of the shunt resistor included in the current sensor 20). Because the resistance component of the current detection portion 210 is very small, the current of the predetermined current value from the current source 140 easily flows directly through the current detection portion 210.

[0028] The control circuit 100 acquires the current value of the current flowing through the current path 200, detected by the current sensor 20. For example, the control circuit 100 has an AD conversion function and converts the acquired current value (analog value) of the current into a digital value. The control circuit 100 determines whether to drive the interrupter 30 (i.e., whether to interrupt the current path 200) based on whether the current detected by the current sensor 20 is an overcurrent.

[0029] The interruption control circuit 110 controls the interruption of the interrupting device 30, which interrupts the current flowing through the current path 200. When the control circuit 100 determines that the current flowing through the current path 200 is an overcurrent (that is, when it determines that the interrupting device 30 should be driven), the interruption control circuit 110 outputs a drive signal to the interrupting device 30 to drive the interrupting device 30. This makes it possible to interrupt the current path 200.

[0030] The method by which the control circuit 100 determines whether the current flowing through the current path 200 is an overcurrent is not particularly limited. However, it is necessary to distinguish whether the current flowing through the current path 200 is noise or an overcurrent. Therefore, for example, the control circuit 100 may have a filtering function that removes noise. Furthermore, for example, the control circuit 100 may average the current value detected by the current sensor 20 over a certain period and determine whether the current flowing through the current path 200 is an overcurrent depending on whether the average value is equal to or greater than a predetermined value.

[0031] In this way, the control circuit 100 can determine whether the overcurrent is not a temporary one caused by noise but is flowing continuously through the current path 200, and if an overcurrent is flowing continuously, the current path 200 can be cut off by driving the cutoff device 30 via the cutoff control circuit 110.

[0032] In addition, if the interrupting device 30 is a pyroelectric fuse, once the pyroelectric fuse is activated, the transportation equipment cannot be restored unless the pyroelectric fuse is replaced, so it is very important to prevent the pyroelectric fuse from being erroneously activated. Therefore, the fault detection circuit 10 has a function of detecting a fault in the current sensor 20, which detects a current flowing through the current path 200 connecting the HV battery 1 and the load 3. The fault detection circuit 10 includes a current source 140, which enables the control circuit 100 to detect a fault in the current sensor 20. Specifically, the control circuit 100 detects a fault in the current sensor 20 based on the current value detected by the current sensor 20 when a current of a predetermined current value is passed from the current source 140 to the current detection section 210. More specifically, the control circuit 100 detects a fault in the current sensor 20 by comparing the current value detected by the current sensor 20 when a current of the predetermined current value is passed from the current source 140 to the current detection section 210 with the predetermined current value. That is, the control circuit 100 determines whether the current sensor 20 is correctly detecting a predetermined current value, thereby detecting a failure of the current sensor 20. The operation of the failure detection circuit 10 when detecting a failure of the current sensor 20 will be described with reference to FIG.

[0033] FIG. 2 is a flowchart showing an example of the operation of the failure detection circuit 10 according to the first embodiment.

[0034] First, the control circuit 100 is started (step S11). For example, when a transportation device is started, power is supplied to the failure detection circuit 10, and the control circuit 100 is started.

[0035] Next, after the control circuit 100 starts up, the control circuit 100 determines whether a predetermined condition is satisfied (step S12). If the predetermined condition is satisfied (Yes in step S12), the control circuit 100 detects a fault in the current sensor 20 (step S13). For example, the control circuit 100 detects a fault in the current sensor 20 based on the current value detected by the current sensor 20 when a current of a predetermined current value is flowing through the current detection section 210 and the current value detected by the current sensor 20 when a current of the predetermined current value is not flowing through the current detection section 210. This will be described in detail later. If the predetermined condition is not satisfied (No in step S12), the control circuit 100 repeats the process of step S12 until the predetermined condition is satisfied. Here, the predetermined condition for the control circuit 100 to start detecting a fault in the current sensor 20 will be described with reference to FIG. 3.

[0036] Fig. 3 is a diagram for explaining the predetermined conditions, showing the voltage of the HV battery 1, the voltage of the load 3, and the current flowing from the HV battery 1 through the current path 200, with the horizontal axis of the graph shown in Fig. 3 representing time and the vertical axis representing voltage and current.

[0037] As described above, in order to prevent an inrush current from flowing when both the main relay 40 and the sub-relay 41 are turned on at the start of the transportation equipment (when the control circuit 100 is started), the sub-relay 41 and the pre-charge relay 42 are turned on with the main relay 40 turned off. As a result, a current flows to the load 3 via the pre-charge resistor 43, and as shown in FIG. 3 , the voltage of the load 3 (the voltage of the smoothing capacitor connected to the load 3) gradually increases, and accordingly, the current from the HV battery 1 gradually decreases. When the voltage of the HV battery 1 and the voltage of the load 3 are approximately the same, an inrush current is unlikely to flow. Therefore, in this state, the main relay 40 can be turned on (and the sub-relay 41 turned off) to start the operation of the load 3.

[0038] For example, the case where a predetermined condition is satisfied may be a case where a predetermined time has elapsed after the control circuit 100 is activated. For example, the predetermined time is a time shorter than the time (e.g., about 0.1 seconds) until the main relay 40 is turned on after the control circuit 100 is activated, and specifically, the time it takes for the current from the HV battery 1 to become approximately 0 A, in other words, the time it takes for the voltage of the HV battery 1 and the voltage of the load 3 to become approximately the same. For example, the predetermined time is set in advance depending on the size of the smoothing capacitance connected to the load 3, etc. In this way, the control circuit 100 may detect a failure of the current sensor 20 when a predetermined time has elapsed after the control circuit 100 is activated, as a case where a predetermined condition is satisfied.

[0039] When a predetermined time has elapsed after the control circuit 100 has started up, the smoothing capacitance connected to the load 3 is charged, and the current from the HV battery 1 flowing through the current path 200 is reduced. Therefore, when detecting a fault in the current sensor 20, the influence of currents other than the current of the predetermined current value from the current source 140, i.e., the influence of the current from the HV battery 1, can be suppressed, and the fault in the current sensor 20 can be detected with high accuracy.

[0040] Furthermore, for example, the case where a predetermined condition is satisfied may be the case where the voltage of the load 3 becomes equal to or greater than a predetermined value after the control circuit 100 is started. For example, the predetermined value is a voltage that is approximately the same as the voltage of the HV battery 1. For example, the predetermined value is set in advance depending on the magnitude of the voltage of the HV battery 1. In this way, the control circuit 100 may detect a failure of the current sensor 20 when the voltage of the load 3 becomes equal to or greater than a predetermined value after the control circuit 100 is started, as the case where a predetermined condition is satisfied.

[0041] After the control circuit 100 is started, if the voltage of the load 3 becomes equal to or higher than a predetermined value (for example, approximately the voltage of the HV battery 1), the smoothing capacitor connected to the load 3 is charged, and the current from the HV battery 1 flowing through the current path 200 becomes small. Therefore, when detecting a fault in the current sensor 20, the influence of current other than the current of the predetermined current value from the current source 140, i.e., the influence of the current from the HV battery 1, can be suppressed, and fault detection in the current sensor 20 can be performed with high accuracy.

[0042] Furthermore, for example, the case where a predetermined condition is satisfied may be a case where the difference between the voltage of the HV battery 1 and the voltage of the load 3 is equal to or less than a predetermined value after the control circuit 100 is started. For example, the predetermined value is approximately 0 V. In this way, the control circuit 100 may detect a failure of the current sensor 20 when the difference between the voltage of the HV battery 1 and the voltage of the load 3 is equal to or less than a predetermined value after the control circuit 100 is started.

[0043] After the control circuit 100 is started, if the difference between the voltage of the HV battery 1 and the voltage of the load 3 becomes equal to or less than a predetermined value (for example, approximately 0 V), the smoothing capacitor connected to the load 3 is charged, and the current from the HV battery 1 flowing through the current path 200 becomes small. Therefore, when detecting a fault in the current sensor 20, the influence of currents other than the current of the predetermined current value from the current source 140, i.e., the influence of the current from the HV battery 1, can be suppressed, and fault detection in the current sensor 20 can be performed with high accuracy.

[0044] Furthermore, for example, the case where a predetermined condition is satisfied may be the case where the current value detected by the current sensor 20 becomes equal to or less than a predetermined value after the control circuit 100 is started. For example, the predetermined value is approximately 0 A. In this way, the control circuit 100 may detect a failure of the current sensor 20 when the current value detected by the current sensor 20 becomes equal to or less than the predetermined value after the control circuit 100 is started.

[0045] After control circuit 100 is started, if the current value detected by current sensor 20 becomes equal to or less than a predetermined value (for example, approximately 0 A), the smoothing capacitor connected to load 3 is charged, and the current from HV battery 1 flowing through current path 200 is small. Therefore, when detecting a fault in current sensor 20, the influence of current other than the current of the predetermined current value from current source 140, i.e., the influence of the current from HV battery 1, can be suppressed, and fault detection in current sensor 20 can be performed with high accuracy.

[0046] Since the detection of a fault in the current sensor 20 is performed when the control circuit 100 is started, it is not necessary to send a signal from an external circuit to the control circuit 100 to cause the control circuit 100 to detect a fault. In other words, an external circuit that sends a signal to the control circuit 100 to cause the control circuit 100 to detect a fault is not required, which enables cost reduction and miniaturization. Furthermore, when the control circuit 100 is started, for example, the main relay 40 in the current path 200 is in a state before it is turned on, and the current source 140 and the interrupting device 30, such as a pyroelectric fuse, provided in the current path 200 are electrically separated. This prevents the interrupting device 30 from being erroneously activated by the current flowing from the current source 140 to detect a fault in the current sensor 20.

[0047] Next, a method of detecting a failure in the current sensor 20 executed by the control circuit 100 will be described with reference to FIG.

[0048] 4 is a flowchart showing an example of a method for detecting a failure of the current sensor 20. The flowchart shown in FIG. 4 shows details of the process in step S13 in FIG.

[0049] First, the control circuit 100 acquires the current value (Ioff) of the current detected by the current sensor 20 when a current of a predetermined current value is not flowing to the current detection section 210 (i.e., when the current source 140 is off) (step S21).

[0050] Next, the control circuit 100 turns on the current source 140 (step S22), and acquires the current value (Ion) of the current detected by the current sensor 20 when a current of a predetermined current value is flowing to the current detection portion 210 (i.e., when the current source 140 is on) (step S23). After acquiring the current value (Ion), the control circuit 100 turns off the current source 140 (step S24).

[0051] Next, the control circuit 100 calculates the difference (Imeas = Ion - Ioff) between the current value detected by the current sensor 20 when a current of a predetermined current value is flowing to the current detection portion 210 and the current value detected by the current sensor 20 when a current of the predetermined current value is not flowing to the current detection portion 210 (step S25).

[0052] Next, the control circuit 100 determines whether the difference is within a predetermined range (whether Ithl<Imeas<Ithh) (step S26). The predetermined range is determined according to the predetermined current value, and Ithl, which is the lower limit of the predetermined range, is set according to the minimum value that the predetermined current value can take, and Ithh, which is the upper limit of the predetermined range, is set according to the maximum value that the predetermined current value can take.

[0053] If the difference is within the predetermined range (Yes in step S26), the control circuit 100 detects that the current sensor 20 is not malfunctioning, that is, makes an OK determination (step S27).

[0054] If the difference is not within the predetermined range (No in step S26), the control circuit 100 detects that the current sensor 20 is malfunctioning, that is, makes an NG determination (step S28).

[0055] Note that step S24 may be performed after any of the processes from step S25 to step S28, or may be performed in parallel with any of the processes from step S25 to step S28.

[0056] For example, the current detected by current sensor 20 when a current of a predetermined current value is flowing to current detection section 210 may include not only the current of the predetermined current value from current source 140 but also the current from HV battery 1. In this case, the current from HV battery 1 may cause current sensor 20 to detect a current greater than the predetermined current value (e.g., a current equal to or greater than Ithh), which may result in erroneous detection of a failure of current sensor 20. Therefore, by also using the current detected by current sensor 20 when a current of the predetermined current value is not flowing to current detection section 210, it is possible to accurately detect a failure of current sensor 20 by taking into account currents other than the current of the predetermined current value from current source 140.

[0057] Specifically, by calculating the difference between the current value detected by current sensor 20 when a current of a predetermined current value is passed through current detection section 210 and the current value detected by current sensor 20 when a current of the predetermined current value is not passed through current detection section 210, it is possible to accurately compare the current value detected by current sensor 20 when a current of a predetermined current value is passed through current detection section 210 with the predetermined current value, thereby enabling highly accurate detection of a malfunction of current sensor 20.

[0058] In order to detect a failure of the current sensor 20 with higher accuracy, the detection of a failure of the current sensor 20 described with reference to FIG. 5 may be performed.

[0059] 5 is a flowchart showing another example of a method for detecting a failure of the current sensor 20. The flowchart shown in FIG. 5 shows details of the process in step S13 in FIG.

[0060] First, the control circuit 100 acquires the current value (Ioff1) of the current detected by the current sensor 20 when a current of a predetermined current value is not flowing to the current detection section 210 (i.e., when the current source 140 is off) (step S31).

[0061] Next, the control circuit 100 turns on the current source 140 (step S32), and acquires the current value (Ion) of the current detected by the current sensor 20 when a current of a predetermined current value is flowing to the current detection portion 210 (i.e., when the current source 140 is on) (step S33). After acquiring the current value (Ion), the control circuit 100 turns off the current source 140 (step S34).

[0062] Next, the control circuit 100 acquires the current value (Ioff2) of the current detected by the current sensor 20 when the current of the predetermined current value is not flowing to the current detection part 210 (i.e., when the current source 140 is off) (step S35). That is, the control circuit 100 acquires the current values ​​of the current detected by the current sensor 20 before and after the current of the predetermined current value is flowing to the current detection part 210.

[0063] Next, the control circuit 100 calculates the difference between Ion and the average of Ioff1 and Ioff2 (Imeas=Ion-(Ioff1+Ioff2) / 2) (step S36).

[0064] Next, the control circuit 100 determines whether the difference is within a predetermined range (whether Ithl<Imeas<Ithh) (step S37). The predetermined range is determined according to the predetermined current value, and Ithl, which is the lower limit of the predetermined range, is set according to the minimum value that the predetermined current value can take, and Ithh, which is the upper limit of the predetermined range, is set according to the maximum value that the predetermined current value can take.

[0065] If the difference is within a predetermined range (Yes in step S37), the control circuit 100 determines that the current sensor is not malfunctioning, that is, makes an OK determination (step S38).

[0066] If the difference is not within the predetermined range (No in step S37), the control circuit 100 detects that the current sensor 20 is broken, that is, makes an NG determination (step S39).

[0067] In this way, if the current value detected by current sensor 20 when a current of a predetermined current value is passed through current detection portion 210 is defined as Ion, the current value detected by current sensor 20 before a current of the predetermined current value is passed through current detection portion 210 and when the current of the predetermined current value is not passed through current detection portion 210 is defined as Ioff1, and the current value detected by current sensor 20 after a current of the predetermined current value is passed through current detection portion 210 and when the current of the predetermined current value is not passed through current detection portion 210 is defined as Ioff2, control circuit 100 may detect that current sensor 20 is faulty if the difference between Ion and the average of Ioff1 and Ioff2 is not included within a predetermined range determined according to the predetermined current value.

[0068] The current value of the current from the HV battery 1 may change over time. Therefore, by using the average of the current values ​​detected by the current sensor 20 before and after a current of a predetermined current value is passed to the current detection unit 210, the influence of changes in the current value of the current from the HV battery 1 can be suppressed, and a failure of the current sensor 20 can be detected with high accuracy.

[0069] As described above, the failure detection circuit 10 includes the current source 140 for detecting a failure of the current sensor 20, and can detect that the current sensor 20 is faulty if the current sensor 20 is not correctly detecting a current of a predetermined current value flowing from the current source 140 to the current detection section 210. In other words, by providing the current source 140 for detecting a failure of the current sensor 20, it is possible to detect a failure of the current sensor 20 without providing multiple current sensors 20.

[0070] Second Embodiment Next, a failure detection circuit according to a second embodiment will be described.

[0071] Fig. 6 is a configuration diagram showing an example of a battery cutoff system 2a according to the second embodiment. For example, the battery cutoff system 2a is used in a transport device that includes an HV battery 1, an LV battery (Low Voltage battery) 4, a load 3, and the like. In addition to the battery cutoff system 2a, Fig. 6 also shows the HV battery 1, the LV battery 4, and the load 3 that are provided in the transport device. As shown in Fig. 6, the HV battery 1, the LV battery 4, and the load 3 are provided outside the battery cutoff system 2a. The battery cutoff system 2a is used in the transport device, for example, an electric vehicle.

[0072] The LV battery 4 can apply a lower voltage (for example, about 10 V) to the failure detection circuit 10a than the HV battery 1. For example, the LV battery 4 is a sub-battery such as a lead storage battery.

[0073] The HV battery 1 and the load 3 are the same as those described in the first embodiment, and therefore a description thereof will be omitted.

[0074] The battery cutoff system 2a differs from the battery cutoff system 2 according to the first embodiment in that it includes a fault detection circuit 10a instead of the fault detection circuit 10. The fault detection circuit 10a also differs from the fault detection circuit 10 according to the first embodiment in that it further includes a charge storage capacitor 120 and a charging circuit 130. As the other points are basically the same as those in the first embodiment, a description thereof will be omitted, and the following description will focus on the differences.

[0075] The charging circuit 130 is connected between the LV battery 4 and the charge storage capacitor 120 and stores charge from the LV battery 4 in the charge storage capacitor 120 .

[0076] The charge storage capacitor 120 is connected between the charging circuit 130 and the shutoff control circuit 110 and the current source 140 , and supplies power to the shutoff control circuit 110 and the current source 140 .

[0077] The interruption control circuit 110 uses the power stored in the charge storage capacitor 120 to control the interruption of the interruption device 30, which interrupts the current flowing through the current path 200. For example, if the interruption device 30 is a pyrofuse, a relatively large current needs to be passed through the ignition resistor in the pyrofuse to ignite the explosive in the pyrofuse. The interruption control circuit 110 uses the power stored in the charge storage capacitor 120 to pass a relatively large current through the interruption device 30.

[0078] The current source 140 uses the power stored in the charge storage capacitor 120 to pass a current of a predetermined current value to the current detection section 210 .

[0079] By providing the charge storage capacitor 120 and the charging circuit 130 for flowing a current of a predetermined current value from the current source 140 to the current detection part 210, it is possible to flow a large current of the predetermined current value from the current source 140. When the predetermined current value is large, even if the detection accuracy of the current sensor 20 is low, the current of the large predetermined current value allows for highly accurate detection of a failure of the current sensor 20.

[0080] Furthermore, by sharing the charge storage capacitor 120 and the charging circuit 130 between the shutoff control circuit 110 and the current source 140, it is possible to reduce costs and size.

[0081] Next, a specific example of the current source 140 and the current sensor 20 will be described with reference to FIG.

[0082] FIG. 7 is a configuration diagram showing a specific example of a battery cutoff system 2a according to the second embodiment.

[0083] As shown in FIG. 7, for example, the current source 140 includes a step-down regulator 141 and a resistor 142 .

[0084] The step-down regulator 141 is an example of a voltage conversion circuit that converts the charging voltage of the charge storage capacitor 120 to a constant voltage. The predetermined current value is a value that corresponds to the constant voltage converted by the step-down regulator 141 and the resistance value of the resistor 142. For example, if the output voltage of the step-down regulator 141 is 1 V and the resistance value of the resistor 142 is 0.33 Ω, the predetermined current value is 3 A. For example, if the capacitance of the charge storage capacitor 120 is 300 μF and the output voltage of the charging circuit 130 is 33 V, the amount of charge stored in the charge storage capacitor 120 is 300 μF × 33 V = approximately 10 mC, and the current source 140 can pass a current of the predetermined current value to the current detection unit 210 for 10 mC / 3 A = approximately 3 ms.

[0085] Note that a series regulator, a switching regulator, or the like can be used as the step-down regulator 141. Furthermore, when a switching regulator is used, loss due to the voltage difference between the input voltage and the output voltage can be significantly reduced, and the amount of charge stored in the charge storage capacitor 120 can be used to extend the period during which a predetermined current flows from the current source 140 to the current detection section 210. For this reason, it is more preferable that the step-down regulator 141 be a switching regulator.

[0086] 7 , for example, the current sensor 20 includes a shunt resistor 21 provided in a current detection portion 210 and an amplifier circuit 150 that amplifies the voltage generated across the shunt resistor 21. The amplifier circuit 150 is an example of a first amplifier circuit. For example, the amplifier circuit 150 is mounted on a substrate that constitutes the fault detection circuit 10a.

[0087] The current sensor 20 detects, as a current, the voltage amplified by the amplifier circuit 150. Specifically, the control circuit 100 acquires the voltage amplified by the amplifier circuit 150, and calculates the current value of the current detected by the current sensor 20 from the voltage, the amplification factor of the amplifier circuit 150, and the resistance value of the shunt resistor 21.

[0088] By using the shunt resistor 21 to detect the current, it is possible to detect an overcurrent (for example, 2000 A to 3000 A or more). In addition, since the voltage generated when a current flows through the shunt resistor 21 is very small, the provision of an amplifier circuit 150 that amplifies the voltage generated in the shunt resistor 21 allows for highly accurate current detection.

[0089] Third Embodiment Next, a failure detection circuit according to a third embodiment will be described.

[0090] Fig. 8 is a configuration diagram showing a specific example of a battery cutoff system 2b according to the third embodiment. For example, the battery cutoff system 2b is used in a transport device including an HV battery 1, an LV battery 4, a load 3, and a host ECU (Electronic Control Unit) 5. In addition to the battery cutoff system 2b, Fig. 8 also shows the HV battery 1, the LV battery 4, the load 3, and the host ECU 5 provided in the transport device. As shown in Fig. 8, the HV battery 1, the LV battery 4, the load 3, and the host ECU 5 are provided outside the battery cutoff system 2b. The battery cutoff system 2b is used in a transport device such as an electric vehicle.

[0091] The host ECU 5 is a device for controlling the HV battery 1, the LV battery 4, the load 3, and various other components of the transportation equipment (such as steering, various sensors, communication devices, and IVI (In Vehicle Infotainment)). While one host ECU 5 is shown here, the host ECU 5 may be composed of multiple ECUs. For example, the host ECU 5 is connected to the HV battery 1 and the LV battery 4, can exchange signals with the HV battery 1 and the LV battery 4, and can monitor the states of the HV battery 1 and the LV battery 4. For example, the host ECU 5 is connected to the load 3, can exchange signals with the load 3, and can monitor the state of the load 3. Furthermore, for example, the host ECU 5 is connected to the main relay 40 via a relay control line 50, to the sub-relay 41 via a relay control line 51, and to the pre-charge relay 42 via a relay control line 52, and controls the main relay 40, the sub-relay 41, and the pre-charge relay 42.

[0092] The HV battery 1, LV battery 4, and load 3 are the same as those described in the first and second embodiments, and therefore description thereof will be omitted.

[0093] Battery shutoff system 2b differs from battery shutoff system 2a according to embodiment 2 in that it includes a fault detection circuit 10b instead of fault detection circuit 10a and a current sensor 20a instead of current sensor 20. Fault detection circuit 10b also differs from fault detection circuit 10a according to embodiment 2 in that it includes a control circuit 100a instead of control circuit 100. As other points are basically the same as those in embodiment 2, a description thereof will be omitted, and the following description will focus on the differences.

[0094] The current sensor 20a differs from the current sensor 20 in that it further includes an amplifier circuit 151 that amplifies the voltage generated across the shunt resistor 21 and detects the voltage amplified by the amplifier circuit 151 as a current. Other aspects of the current sensor 20a are basically the same as those of the current sensor 20, and therefore a description thereof will be omitted. The amplifier circuit 151 is an example of a second amplifier circuit. For example, the amplifier circuit 151 is mounted on a board that constitutes the fault detection circuit 10b. The amplifier circuits 150 and 151 have the same performance.

[0095] The control circuit 100a detects a fault in at least one of the amplifier circuits 150 and 151 by comparing the current value of the current detected via the amplifier circuit 150 with the current value of the current detected via the amplifier circuit 151. Because the amplifier circuits 150 and 151 have the same performance, if the current value of the current detected via the amplifier circuit 150 and the current value of the current detected via the amplifier circuit 151 are different values, it can be determined that one of the amplifier circuits 150 and 151 is faulty.

[0096] In this way, by providing redundancy to the amplifier circuit that amplifies the voltage generated in the shunt resistor 21, it is possible to detect a failure in the amplifier circuit 150 or 151. For example, detection of a failure in the amplifier circuit 150 or 151 through the redundant amplifier circuit can be performed at all times, such as during normal operation of the load 3, not just when detecting a failure in the current sensor 20a using a current of a predetermined current value from the current source 140. This is because, as long as any current, not just a current of a predetermined current value from the current source 140, flows through the current detection portion 210, the current value of the current detected via the amplifier circuit 150 can be compared with the current value of the current detected via the amplifier circuit 151.

[0097] For example, as shown in FIG. 8, the path connecting the output terminal of the current source 140 and the current detection section 210 and the path connecting the input terminal of the amplifier circuit 151 and the current detection section 210 may be a common path.

[0098] If these paths were not shared, a cable (e.g., a wire harness) would be required to connect the output terminal of current source 140 to current detection section 210, and another cable would be required to connect the input terminal of amplifier circuit 151 to current detection section 210, resulting in a large number of cables. In contrast, by sharing these paths, the number of cables can be reduced.

[0099] The control circuit 100a also has a communication interface 160 for communicating with the host ECU 5, and detects a failure of the current sensor 20a when instructed to do so by the host ECU 5. The host ECU 5 is an example of a circuit external to the failure detection circuit 10b.

[0100] In the first and second embodiments, examples were described in which a failure of the current sensor 20 was detected when the control circuit 100 was started up, but in the third embodiment, a failure of the current sensor 20a can be detected at any timing based on instructions from the upper ECU 5.

[0101] For example, when the control circuit 100a is instructed by the host ECU 5 to detect a failure of the current sensor 20a, the control circuit 100a detects a failure of the current sensor 20a while the host ECU 5 is controlling the current path 200 so that no current flows from the HV battery 1. This will be described with reference to FIG.

[0102] FIG. 9 is a flowchart showing an example of the operation of the failure detection circuit 10b and the host ECU 5 according to the third embodiment.

[0103] First, the host ECU 5 turns off the main relay 40 (step S41). The host ECU 5 may also turn off the sub-relay 41. This prevents current from flowing from the HV battery 1 to the current path 200.

[0104] Next, the host ECU 5 instructs the control circuit 100a to detect a fault in the current sensor 20a, i.e., to perform a fault diagnosis (step S42). When the control circuit 100a is instructed by the host ECU 5 to detect a fault in the current sensor 20a, the control circuit 100a can thereby detect a fault in the current sensor 20a while the host ECU 5 is controlling the current path 200 so that no current flows from the HV battery 1. The details of the process in step S43 are the same as those described in FIG. 4 or 5, and therefore will not be described here.

[0105] In this way, the host ECU 5 controls the flow of current from the HV battery 1 to the current path 200, thereby enabling highly accurate detection of a failure in the current sensor 20a without being affected by the current from the HV battery 1.

[0106] Next, the control circuit 100a notifies the host ECU 5 of the detection result of the failure of the current sensor 20a (step S44), thereby allowing the host ECU 5 to perform processing according to the detection result of the failure of the current sensor 20a.

[0107] (Other Embodiments) As described above, the embodiments have been described as examples of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. For example, the following modifications are also included in one embodiment of the present disclosure.

[0108] For example, in the above embodiment, an example has been described in which the fault detection circuit includes the shutoff control circuit 110, but the fault detection circuit does not have to include the shutoff control circuit 110. In other words, the fault detection circuit does not have to be used in a battery shutoff system in which the shutoff device 30 shuts off the current path 200 through which current flows from the HV battery 1. For example, the fault detection circuit is not limited to a current sensor that detects the current flowing in the current path 200 in which the shutoff device 30 is provided, but may be a circuit that detects a fault in a current sensor that detects the current flowing in any current path.

[0109] For example, in the third embodiment, the control circuit 100a detects a failure of the current sensor 20a when instructed to do so by a circuit external to the failure detection circuit 10b (e.g., the upper ECU 5), but this is not limiting. For example, as in the first and second embodiments, the control circuit 100a may detect a failure of the current sensor 20a when a predetermined condition is satisfied after the control circuit 100a is started.

[0110] For example, in the above-described first and second embodiments, the control circuit 100 detects a failure of the current sensor 20 when a predetermined condition is satisfied after the control circuit 100 is started up, but this is not limiting. For example, as in the third embodiment, the control circuit 100 may detect a failure of the current sensor 20 when instructed to do so by a circuit external to the failure detection circuit (e.g., the upper ECU 5).

[0111] For example, in the first and second embodiments, the current sensor 20 may include the amplifier circuits 150 and 151, and the amplifier circuits may be made redundant, as in the third embodiment.

[0112] For example, the present disclosure can be realized not only as a failure detection circuit, but also as a failure detection method including steps (processing) performed by components that make up the failure detection circuit.

[0113] FIG. 10 is a flowchart showing an example of a failure detection method according to another embodiment.

[0114] The fault detection method is a method executed by a fault detection circuit that detects a fault in a current sensor that detects a current flowing in a current path connecting a power supply and a load, and the fault detection circuit includes a current source, and the fault detection method includes, as shown in Figure 10, a step (step S1) of flowing a current of a predetermined current value from the current source to a current detection portion in the current path where the current sensor detects the current, and a step (step S2) of detecting a fault in the current sensor based on the current value of the current detected by the current sensor when the current of the predetermined current value is flowed to the current detection portion.

[0115] For example, the present disclosure can be realized as a program for causing a computer (processor) to execute steps included in the fault detection method. Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

[0116] For example, when the present disclosure is realized as a program (software), each step is performed by running the program using hardware resources such as a computer's CPU, memory, input / output circuits, etc. In other words, each step is performed by the CPU acquiring data from memory or input / output circuits, etc., performing calculations, and outputting the calculation results to memory or input / output circuits, etc.

[0117] In the above-described embodiments, each component included in the failure detection circuit may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0118] Some or all of the functions of the fault detection circuits according to the above embodiments are typically realized as an LSI, which is an integrated circuit. These may be individually integrated into single chips, or some or all of them may be integrated into a single chip. Furthermore, the integrated circuit is not limited to an LSI, and may be realized using a dedicated circuit or a general-purpose processor. It is also possible to use an FPGA (Field Programmable Gate Array) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI.

[0119] Furthermore, if an integrated circuit technology that can replace LSIs emerges due to advances in semiconductor technology or other derivative technologies, it is natural that each component included in the failure detection circuit can be integrated using that technology.

[0120] In addition, this disclosure also includes forms obtained by making various modifications to the embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in each embodiment within the scope of the present disclosure.

[0121] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0122] (Technology 1) A fault detection circuit that detects a fault in a current sensor that detects a current flowing in a current path connecting a power source and a load, the fault detection circuit comprising a current source and a control circuit, wherein the current source flows a current of a predetermined current value to a current detection portion in the current path where the current sensor detects a current, and the control circuit detects a fault in the current sensor based on the current value of the current detected by the current sensor when the current of the predetermined current value flows to the current detection portion.

[0123] According to this, the failure detection circuit is provided with a current source for detecting a failure of the current sensor, and if the current sensor cannot correctly detect a current of a predetermined current value flowing from the current source to the current detection part, it can detect that the current sensor is faulty. In other words, by providing a current source for detecting a failure of the current sensor, it is possible to detect a failure of the current sensor without providing multiple current sensors.

[0124] (Technology 2) The fault detection circuit according to Technology 1, further comprising a charge storage capacitance and a charging circuit that stores charge in the charge storage capacitance, and the current source uses the power stored in the charge storage capacitance to pass a current of the predetermined current value to the current detection portion.

[0125] According to this, by providing a charge storage capacitor and a charging circuit for flowing a current of a predetermined current value from the current source to the current detection part, it is possible to flow a large current of the predetermined current value from the current source. When the predetermined current value is large, even if the detection accuracy of the current sensor is low, the current of the large predetermined current value can be used to detect a failure of the current sensor with high accuracy.

[0126] (Technology 3) A fault detection circuit according to Technology 2, wherein the current source includes a voltage conversion circuit that converts the charging voltage of the charge storage capacitance into a constant voltage, and a resistor, and the predetermined current value is a value that corresponds to the constant voltage and the resistance value of the resistor.

[0127] In this way, the current source can be realized by a voltage conversion circuit and a resistor.

[0128] (Technology 4) The fault detection circuit according to Technology 2 or 3, further comprising a shutoff control circuit that controls shutoff of a shutoff device that cuts off the current flowing through the current path using the power stored in the charge storage capacitance.

[0129] According to this, the charge storage capacitor and the charging circuit are shared by the cutoff control circuit and the current source, thereby making it possible to reduce costs and size.

[0130] (Technology 5) The fault detection circuit according to Technology 4, wherein the cutoff device is a pyro-fuse.

[0131] This makes it possible to interrupt a large current.

[0132] (Technology 6) A fault detection circuit according to any one of technologies 1 to 5, wherein the current sensor comprises a shunt resistor provided in the current detection portion and a first amplifier circuit that amplifies the voltage generated in the shunt resistor, and detects the voltage amplified by the first amplifier circuit as a current.

[0133] According to this, by using a shunt resistor to detect current, it is possible to detect overcurrent (for example, 2000 A to 3000 A or more). In addition, because the voltage generated when current flows through the shunt resistor is very small, an amplifier circuit that amplifies the voltage generated in the shunt resistor is provided, making it possible to detect current with high accuracy.

[0134] (Technology 7) A fault detection circuit according to Technology 6, wherein the current sensor further includes a second amplifier circuit that amplifies the voltage generated in the shunt resistor, and detects the voltage amplified by the second amplifier circuit as a current, and the control circuit detects a fault in at least one of the first amplifier circuit and the second amplifier circuit by comparing the current value of the current detected via the first amplifier circuit with the current value of the current detected via the second amplifier circuit.

[0135] According to this, the amplifier circuit that amplifies the voltage generated in the shunt resistor is made redundant, so that a failure in the amplifier circuit can be detected.

[0136] (Technology 8) A fault detection circuit according to Technology 7, in which a path connecting the output terminal of the current source and the current detection part and a path connecting the input terminal of the second amplifier circuit and the current detection part are common.

[0137] By sharing these paths, the number of cables (for example, wire harnesses) can be reduced, which leads to lower costs and a smaller size.

[0138] (Technology 9) A fault detection circuit described in any one of Technologies 1 to 8, wherein the control circuit detects a fault in the current sensor based on the current value of the current detected by the current sensor when a current of the predetermined current value is flowing to the current detection part, and the current value of the current detected by the current sensor when a current of the predetermined current value is not flowing to the current detection part.

[0139] For example, when a current of a predetermined current value is flowing to the current detection part, the current detected by the current sensor may include not only the current of the predetermined current value from the current source but also the current from the power supply. In this case, the current from the power supply may cause the current sensor to detect a current greater than the predetermined current value, which may result in a false detection of a current sensor failure. Therefore, by also using the current detected by the current sensor when a current of the predetermined current value is not flowing to the current detection part, it is possible to take into account currents other than the current of the predetermined current value from the current source, thereby enabling highly accurate detection of a current sensor failure.

[0140] (Technology 10) The fault detection circuit described in Technology 9, wherein the control circuit detects that the current sensor is faulty when the difference between the current value detected by the current sensor when a current of the predetermined current value is flowing to the current detection part and the current value detected by the current sensor when a current of the predetermined current value is not flowing to the current detection part is not included within a predetermined range determined according to the predetermined current value.

[0141] In this way, by calculating the difference between the current value detected by the current sensor when a current of a predetermined current value is passed through the current detection portion and the current value detected by the current sensor when a current of a predetermined current value is not passed through the current detection portion, it is possible to accurately compare the current value detected by the current sensor when a current of a predetermined current value is passed through the current detection portion with the predetermined current value, thereby enabling highly accurate detection of current sensor failure.

[0142] (Technology 11) The failure detection circuit according to Technology 9, wherein the current value detected by the current sensor when the current of the predetermined current value is flowed to the current detection portion is Ion, the current value detected by the current sensor before the current of the predetermined current value is flowed to the current detection portion and when the current of the predetermined current value is not flowing to the current detection portion is Ioff1, and the current value detected by the current sensor after the current of the predetermined current value has flowed to the current detection portion and when the current of the predetermined current value is not flowing to the current detection portion is Ioff2, the control circuit detects that the current sensor is faulty when a difference between Ion and an average of Ioff1 and Ioff2 is not included in a predetermined range determined according to the predetermined current value.

[0143] The current value of the current from the power supply may change over time. Therefore, by using the average of the current values ​​detected by the current sensor before and after a current of a predetermined current value is passed to the current detection part, the influence of changes in the current value from the power supply can be suppressed, and current sensor failure can be detected with high accuracy.

[0144] (Technology 12) A fault detection circuit according to any one of technologies 1 to 11, wherein the control circuit detects a fault in the current sensor when a predetermined condition is met after the control circuit is started.

[0145] According to this, since the fault detection of the current sensor is performed when the control circuit is started, it is not necessary to send a signal from an external circuit to the control circuit to cause the fault detection. In other words, an external circuit that sends a signal to the control circuit to cause the fault detection is not required, which enables cost reduction and miniaturization. Furthermore, when the control circuit is started, for example, the state is before the main relay in the current path is turned on, and it is possible to prevent a breaker device such as a pyroelectric fuse provided in the current path from being erroneously activated by the current flowing from the current source to detect the fault of the current sensor.

[0146] (Technology 13) A fault detection circuit according to Technology 12, wherein the control circuit detects a fault in the current sensor when a predetermined time has elapsed after the control circuit is started and the predetermined condition is satisfied.

[0147] According to this, when a predetermined time has elapsed after the control circuit is started, the smoothing capacitor connected to the load is charged, and the current from the power supply flowing through the current path is reduced. Therefore, when detecting a fault in the current sensor, the influence of current other than the current of the predetermined current value from the current source, i.e., the influence of current from the power supply, can be suppressed, and fault detection of the current sensor can be performed with high accuracy.

[0148] (Technology 14) A fault detection circuit as described in Technology 12, wherein the control circuit detects a fault in the current sensor when the predetermined condition is met after the control circuit is started, i.e., when the voltage of the load becomes equal to or greater than a predetermined value.

[0149] According to this, when the voltage of the load becomes equal to or greater than a predetermined value (for example, the voltage of the power supply) after the control circuit is started, the smoothing capacitor connected to the load is charged, and the current from the power supply flowing through the current path becomes small. Therefore, when detecting a fault in the current sensor, the influence of current other than the current of the predetermined current value from the current source, i.e., the influence of current from the power supply, can be suppressed, and fault detection of the current sensor can be performed with high accuracy.

[0150] (Technology 15) A fault detection circuit as described in Technology 12, wherein the control circuit detects a fault in the current sensor when the predetermined condition is met after the control circuit is started, i.e., when the difference between the voltage of the power supply and the voltage of the load becomes less than a predetermined value.

[0151] According to this, when the difference between the voltage of the power supply and the voltage of the load becomes equal to or less than a predetermined value (for example, approximately 0 V) ​​after the control circuit starts up, the smoothing capacitor connected to the load is charged, and the current from the power supply flowing through the current path becomes small. Therefore, when detecting a fault in the current sensor, the influence of current other than the current of the predetermined current value from the current source, i.e., the influence of the current from the power supply, can be suppressed, and fault detection of the current sensor can be performed with high accuracy.

[0152] (Technology 16) A fault detection circuit as described in Technology 12, wherein the control circuit detects a fault in the current sensor when the current value detected by the current sensor becomes equal to or less than a predetermined value after the control circuit is started and the predetermined condition is satisfied.

[0153] According to this, when the current value detected by the current sensor becomes equal to or less than a predetermined value after the control circuit is started, the smoothing capacitor connected to the load is charged, and the current from the power supply flowing through the current path becomes small. Therefore, when detecting a fault in the current sensor, the influence of currents other than the current of the predetermined current value from the current source, i.e., the influence of current from the power supply, can be suppressed, and fault detection of the current sensor can be performed with high accuracy.

[0154] (Technology 17) A fault detection circuit described in any of Technologies 1 to 11, wherein the control circuit detects a fault in the current sensor when instructed to do so by a circuit external to the fault detection circuit.

[0155] This allows current sensor failure detection to be performed at any timing in response to an instruction from an external circuit.

[0156] (Technology 18) A fault detection circuit as described in Technology 17, in which, when instructed by the external circuit to detect a fault in the current sensor, the control circuit detects a fault in the current sensor while the external circuit controls the current path so that no current flows from the power supply.

[0157] With this, an external circuit controls the current path so that no current flows from the power supply, thereby enabling highly accurate detection of a fault in the current sensor without the influence of current from the power supply.

[0158] (Technology 19) A failure detection circuit according to Technology 17 or 18, wherein the control circuit notifies the external circuit of the detection result of a failure of the current sensor.

[0159] This allows an external circuit to perform processing according to the detection result of a failure in the current sensor.

[0160] (Technology 20) A failure detection method executed by a failure detection circuit that detects a failure of a current sensor that detects a current flowing in a current path connecting a power supply and a load, the failure detection circuit including a current source, the failure detection method including the steps of: flowing a current of a predetermined current value from the current source to a current detection portion in the current path where the current sensor detects the current; and detecting a failure of the current sensor based on the current value of the current detected by the current sensor when the current of the predetermined current value is flowed to the current detection portion.

[0161] This makes it possible to provide a failure detection method that can detect a failure in a current sensor without providing multiple current sensors.

[0162] The present disclosure can be applied to a system for interrupting a current flowing in a current path.

[0163] REFERENCE SIGNS LIST 1 HV battery 2, 2a, 2b Battery cutoff system 3 Load 4 LV battery 5 Host ECU 10, 10a, 10b Fault detection circuit 20, 20a Current sensor 21 Shunt resistor 30 Cutoff device 40 Main relay 41 Sub-relay 42 Pre-charge relay 43 Pre-charge resistor 50, 51, 52 Relay control line 100, 100a Control circuit 110 Cutoff control circuit 120 Charge storage capacitor 130 Charging circuit 140 Current source 141 Step-down regulator 142 Resistor 150, 151 Amplification circuit 160 Communication interface 200 Current path 210 Current detection portion 211 One end 212 Other end

Claims

1. A fault detection circuit that detects a fault in a current sensor that detects a current flowing through a current path connecting a power supply and a load, a current source; a control circuit; the current source causes a current of a predetermined current value to flow to a current detection portion of the current path where the current sensor detects a current; the control circuit detects a failure of the current sensor based on a current value detected by the current sensor when a current of the predetermined current value is passed through the current detection portion. Fault detection circuit.

2. The failure detection circuit further a charge storage capacitance; a charging circuit that stores charge in the charge storage capacitor; the current source uses the power charged in the charge storage capacitor to cause a current of the predetermined current value to flow to the current detection portion; 2. The fault detection circuit according to claim 1.

3. The current source is a voltage conversion circuit that converts the charging voltage of the charge storage capacitor into a constant voltage; a resistor; the predetermined current value is a value according to the constant voltage and the resistance value of the resistor; 3. The fault detection circuit according to claim 2.

4. The fault detection circuit further includes a cutoff control circuit that controls cutoff of a cutoff device that cuts off a current flowing through the current path by using the power stored in the charge storage capacitor.

3. The fault detection circuit according to claim 2.

5. The interrupting device is a pyro-fuse.

5. The fault detection circuit according to claim 4.

6. The current sensor a shunt resistor provided in the current detection portion; a first amplifier circuit that amplifies a voltage generated across the shunt resistor; detecting the voltage amplified by the first amplifier circuit as a current; 2. The fault detection circuit according to claim 1.

7. The current sensor further includes a second amplifier circuit that amplifies a voltage generated across the shunt resistor, and detects the voltage amplified by the second amplifier circuit as a current; the control circuit detects a failure in at least one of the first amplifier circuit and the second amplifier circuit by comparing a current value detected via the first amplifier circuit with a current value detected via the second amplifier circuit.

7. The fault detection circuit according to claim 6.

8. a path connecting the output terminal of the current source and the current detection part and a path connecting the input terminal of the second amplifier circuit and the current detection part are common to each other; 8. The fault detection circuit according to claim 7.

9. the control circuit detects a failure of the current sensor based on a current value detected by the current sensor when a current of the predetermined current value is flowing to the current detection portion and a current value detected by the current sensor when a current of the predetermined current value is not flowing to the current detection portion.

2. The fault detection circuit according to claim 1.

10. The control circuit detects that the current sensor is faulty when a difference between a current value detected by the current sensor when a current of the predetermined current value is flowing to the current detection portion and a current value detected by the current sensor when a current of the predetermined current value is not flowing to the current detection portion is not included within a predetermined range determined according to the predetermined current value.

10. The fault detection circuit according to claim 9.

11. a current value detected by the current sensor when the current of the predetermined current value is passed through the current detection portion is defined as Ion; a current value detected by the current sensor before the current of the predetermined current value is passed through the current detection portion and when the current of the predetermined current value is not passed through the current detection portion is defined as Ioff1; After the current of the predetermined current value has been passed through the current detection portion, when the current value detected by the current sensor is not passed through the current detection portion, the current value is set to Ioff2. The control circuit detects that the current sensor is faulty when a difference between the Ion and an average of the Ioff1 and Ioff2 is not included within a predetermined range determined according to the predetermined current value.

10. The fault detection circuit according to claim 9.

12. the control circuit detects a failure of the current sensor when a predetermined condition is satisfied after the control circuit is started. The fault detection circuit according to any one of claims 1 to 11.

13. the control circuit detects a failure of the current sensor when a predetermined time has elapsed after the control circuit is started and the predetermined condition is satisfied; 13. The fault detection circuit of claim 12.

14. the control circuit detects a failure of the current sensor when the voltage of the load becomes equal to or greater than a predetermined value after the control circuit is started and the predetermined condition is satisfied; 13. The fault detection circuit of claim 12.

15. the control circuit detects a failure of the current sensor when the predetermined condition is satisfied after the control circuit is started, i.e., when a difference between a voltage of the power supply and a voltage of the load becomes equal to or smaller than a predetermined value; 13. The fault detection circuit of claim 12.

16. the control circuit detects a failure of the current sensor when the current value detected by the current sensor becomes equal to or less than a predetermined value, assuming that the predetermined condition is satisfied after the control circuit is started up; 13. The fault detection circuit of claim 12.

17. the control circuit detects a failure of the current sensor when instructed to do so by a circuit external to the failure detection circuit; The fault detection circuit according to any one of claims 1 to 11.

18. When instructed by the external circuit to detect a failure of the current sensor, the control circuit detects a failure of the current sensor in a state in which the external circuit controls so that no current flows from the power source to the current path.

18. The fault detection circuit of claim 17.

19. The control circuit notifies the external circuit of the detection result of the failure of the current sensor.

18. The fault detection circuit of claim 17.

20. A fault detection method executed by a fault detection circuit that detects a fault in a current sensor that detects a current flowing through a current path connecting a power supply and a load, comprising: the fault detection circuit comprises a current source; The failure detection method includes: A step of flowing a current of a predetermined current value from the current source to a current detection portion of the current path where the current sensor detects the current; and detecting a failure of the current sensor based on a current value detected by the current sensor when the current of the predetermined current value is passed through the current detection portion. Fault detection methods.