Power source control device and diagnosis program

Abstract

To provide a power source control device capable of diagnosing whether or not a circuit which causes an interruption mechanism to perform interruption normally operates when a power supply failure occurs without exerting adverse influences upon a load, and a diagnosis program.SOLUTION: A power source control device comprises an interruption mechanism, an abnormality detector, and a controller. The interruption mechanism interrupts a connection of a first system which supplies power from a main power source to a load and a second system which supplies power from a backup power source to the load. The abnormality detector compares a system voltage, which is a voltage of the first system or the second system, with an abnormality threshold in a normal mode, outputs an abnormality detection signal when the system voltage becomes lower than the abnormality threshold, and causes the interruption mechanism to interrupt the connection of the first system and the second system. The controller adjusts the abnormality threshold to be equal to or higher than a value of the system voltage in a diagnosis mode and diagnoses whether or not the interruption mechanism interrupts the connection of the first system and the second system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosed embodiments relate to a power supply control device and a diagnostic program. [Background technology]

[0002] There is a power supply control device that is equipped with a cutoff mechanism that cuts off the connection between a first system that supplies power from a first power source to a load and a second system that supplies power from a second power source to a load, and that cuts off the cutoff mechanism when the first power source fails and performs backup control using the second power source (see, for example, Patent Document 1).It is desirable for such a power supply control device to diagnose whether the circuit that cuts off the cutoff mechanism operates normally when a power failure actually occurs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-043533 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the power supply control device actually causes the first power supply to fail in order to diagnose the operation of the circuit, the power supply to the load will be cut off, which will have an adverse effect on the load.

[0005] One aspect of the embodiment has been made in consideration of the above, and aims to provide a power supply control device and a diagnostic program that can diagnose whether a circuit that shuts off a shut-off mechanism operates normally in the event of a power failure, without adversely affecting the load. [Means for solving the problem]

[0006] A power supply control device according to an embodiment includes a cutoff mechanism, an abnormality detector, and a controller. The cutoff mechanism cuts off a connection between a first system that supplies power from a main power source to a load and a second system that supplies power from a backup power source to the load. In a normal mode, the abnormality detector compares a system voltage, which is the voltage of the first system or the second system, with an abnormality threshold, and outputs an abnormality detection signal when the system voltage falls below the abnormality threshold, causing the cutoff mechanism to cut off the connection between the first system and the second system. In a diagnostic mode, the controller adjusts the abnormality threshold to be equal to or greater than the system voltage, and diagnoses whether the cutoff mechanism should cut off the connection between the first system and the second system. [Effects of the Invention]

[0007] The power supply control device according to the embodiment reproduces the state of a power supply failure by adjusting the abnormality threshold without manipulating the system voltage in the diagnostic mode and diagnoses whether to shut off the cutoff mechanism, thereby preventing the power supply to the load from being interrupted during the diagnosis. Therefore, the power supply control device can diagnose whether the circuit that shuts off the cutoff mechanism operates normally in the event of a power supply failure without adversely affecting the load. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of a power supply control device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating the operation of the power supply control device according to the embodiment. [Figure 3] FIG. 3 is a diagram illustrating the operation of the power supply control device according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating the operation of the power supply control device according to the embodiment. [Figure 5] FIG. 5 is an explanatory diagram showing the relationship between the duty ratio of the PWM signal and the abnormality threshold value according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating the operation of the power supply control device according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating the operation of the power supply control device according to the embodiment. [Figure 8] FIG. 8 is an explanatory diagram showing an example of adjustment of the duty ratio in the diagnosis mode according to the embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing an example of adjustment of the abnormality threshold in the diagnosis mode according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of processing executed by the controller according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a power supply control device and a power supply control program will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below. The following description will be given taking as an example a power supply control device that is installed in a vehicle with an automatic driving function and supplies power to a load.

[0010] In the following, a case will be described in which the vehicle in which the power supply control device is installed is an electric vehicle or a hybrid vehicle, but the vehicle in which the power supply control device is installed may also be an engine vehicle that runs on an internal combustion engine.

[0011] [1. Configuration of the power supply control device according to the embodiment] Fig. 1 is an explanatory diagram showing the configuration of a power supply control device according to an embodiment. As shown in Fig. 1, the power supply control device 1 according to the embodiment is connected to a main power supply 10, a first load 101, and a second load 102. The power supply control device 1 is also connected to an automatic operation control device (not shown).

[0012] The power supply control device 1 includes a first system 110 and a second system 120. The first system 110 is a power supply system that supplies power from a main power supply 10 to a first load 101. The second system 120 is a power supply system that supplies power from a backup power supply 20 to a second load 102.

[0013] The first load 101 includes a load for autonomous driving. The first load 101 includes a steering motor, an electric brake device, an in-vehicle camera, etc. that operate during autonomous driving. The first load 101 may also include a display, an air conditioner, an audio device, a video device, various lights, etc.

[0014] The second load 102 has some of the functions for automatic driving that the first load 101 has. The second load 102 includes the minimum devices required for FOP (fail-safe control), such as a steering motor, an electric brake device, and a radar. The second load 102 may also include a display, an air conditioner, an audio device, a video device, various lights, and the like.

[0015] The first load 101 and the second load 102 may be the same load. The first load 101 and the second load 102 operate using power supplied from at least one of the main power supply 10 and the backup power supply 20 via the power supply control device 1.

[0016] The automatic driving control device is a device that controls automatic driving of a vehicle by operating a first load 101 and a second load 102. If a power supply failure such as a ground fault occurs in the first system 110 during automatic driving, the automatic driving control device can implement FOP (fail-safe control) using the second load 102. Furthermore, if a power supply failure such as a ground fault occurs in the second system 120, the automatic driving control device can implement FOP using the first load 101.

[0017] The main power supply 10 is, for example, a lead battery. The battery of the main power supply 10 may be any secondary battery other than a lead battery. The backup power supply 20 is a backup power supply in case the main power supply 10 is unable to supply power. The backup power supply 20 is, for example, a lithium ion battery. The battery of the backup power supply 20 may be any secondary battery other than a lithium ion battery. The backup power supply 20 may also be included in the power supply control device 1.

[0018] The power supply control device 1 includes a shutdown mechanism 2, an abnormality detector 3, an AND circuit 4, a controller 5, and a backup power supply 20. The shutdown mechanism 2 includes a switch that shuts off the connection between the first system 110 and the second system 120. Specifically, the shutdown mechanism 2 includes a first switch 21, a second switch 22, and a voltage sensor 6.

[0019] The first switch 21 and the second switch 22 are normally-off switches, and are, for example, a pair of FETs (Field Effect Transistors) having body diodes with anodes facing each other. The first switch 21 and the second switch 22 are connected in series between the first system 110 and the second system 120.

[0020] The first switch 21 and the second switch 22 are controlled to be turned on and off by the controller 5. When the first switch 21 and the second switch 22 are turned on, they electrically connect both terminals, and when they are turned off, they cut off the electrical connection between both terminals. The first switch 21 and the second switch 22 are in the off state while the ignition switch is off, and are turned on by the controller 5 when the ignition switch is turned on.

[0021] The cutoff mechanism 2 electrically connects the first system 110 and the second system 120 by turning on both the first switch 21 and the second switch 22. The cutoff mechanism 2 also cuts off the electrical connection between the first system 110 and the second system 120 by turning off at least one of the first switch 21 and the second switch 22.

[0022] The voltage sensor 6 is provided on a connection line connecting the first switch 21 and the second switch 22. The voltage sensor 6 detects a system voltage V1 which is the voltage of the first system 110 or the second system 120, and outputs the detection result to the controller 5.

[0023] The power supply control device 1 also includes a bypass switch 23 and a battery switch 24. The bypass switch 23 and the battery switch 24 are, for example, FETs. The bypass switch 23 and the battery switch 24 are controlled to be turned on and off by the controller 5. The bypass switch 23 and the battery switch 24 electrically connect both terminals when turned on, and cut off the electrical connection between both terminals when turned off.

[0024] The bypass switch 23 is a normally-on switch that bypasses the cutoff mechanism 2. In other words, the bypass switch 23 is a switch that connects the first system 110 and the second system 120 while bypassing the first switch 21 and the second switch 22 while the ignition switch is off. This allows power to be supplied from the main power supply 10 to a second load 102 (for example, an anti-theft device, a door control device, etc.) that operates when the ignition switch is off.

[0025] When the cutoff mechanism 2 is in a cutoff state, the power supply control device 1 can supply power to the first load 101 and the second load 102 from at least one of the main power supply 10 and the backup power supply 20 without going through the cutoff mechanism 2 by turning on the bypass switch 23.

[0026] The battery switch 24 is a normally-off switch, and is connected between the backup power supply 20 and the second system 120. When the battery switch 24 is turned on, it electrically connects the backup power supply 20 and the second system 120, and when it is turned off, it cuts off the electrical connection between the backup power supply 20 and the second system 120.

[0027] The abnormality detector 3 is a circuit that compares the system voltage V1 with the abnormality threshold Vth in normal mode, and when the system voltage V1 falls below the abnormality threshold Vth, outputs an abnormality detection signal S1 and causes the cut-off mechanism 2 to cut off the connection between the first system 110 and the second system 120.

[0028] Specifically, the abnormality detector 3 includes a comparator 31 and a latch circuit 32. The comparator 31 compares the system voltage V1 output from the voltage sensor 6 with an abnormality threshold Vth. The abnormality threshold Vth is the lower limit of the system voltage V1 in a normal state where no failure occurs in the first system 110 or the second system 120. When the system voltage V1 drops below the abnormality threshold Vth, the comparator 31 outputs an abnormality detection signal S1 to the latch circuit 32.

[0029] The latch circuit 32 is a monostable multivibrator. When the abnormality detection signal S1 is input from the comparator 31, the latch circuit 32 outputs a one-shot pulse signal with a predetermined pulse width as the abnormality detection signal S2 to the AND circuit 4 and the controller 5. The predetermined pulse width is, for example, 50 ms. However, the predetermined pulse width is not limited to 50 ms.

[0030] Specifically, the predetermined pulse width may be a pulse width other than 50 ms as long as it is longer than the oscillation period of the system voltage V1 that is expected to occur due to noise. This allows the cutoff mechanism 2 to maintain the cutoff state while the abnormality detection signal S2 is high, even if the system voltage V1 temporarily exceeds the abnormality threshold Vth due to noise or the like. This allows the power supply control device 1 to suppress the occurrence of chattering, in which the cutoff mechanism 2 repeatedly turns on and off.

[0031] The AND circuit 4 is provided between the abnormality detector 3 and the cutoff mechanism 2. The AND circuit 4 is a gate circuit that enables or disables the abnormality detection signal S2 input from the abnormality detector 3 in accordance with a control signal S3 input from the controller 5.

[0032] The AND circuit 4 outputs an abnormality detection signal S4 to the cutoff mechanism 2 and the battery switch 24 when the abnormality detection signal S2 is High and the control signal S3 is High (shutoff activation signal). The AND circuit 4 does not output the abnormality detection signal S4 except when the abnormality detection signal S1 is High and the control signal S3 is High (shutoff activation signal). During normal operation when no power supply failure has occurred, the controller 5 inputs a shutdown activation signal to the AND circuit 4.

[0033] When the ignition is in an on state, in normal operation when the abnormality detection signal S4 is not input, the cutoff mechanism 2 turns on the first switch 21 and the second switch 22 by the controller 5, connecting the first system 110 and the second system 120. In addition, in the event of a power failure when the abnormality detection signal S4 is input, the cutoff mechanism 2 turns off the first switch 21 and the second switch 22 by the controller 5, cutting off the connection between the first system 110 and the second system 120.

[0034] On the other hand, during normal operation when the abnormality detection signal S1 is not input, the battery switch 24 is turned off to disconnect the backup power supply 20 and the second system 120. Furthermore, during a power failure when the abnormality detection signal S4 is input, the battery switch 24 is turned on by the controller 5 to connect the backup power supply 20 and the second system 120.

[0035] The abnormality detector 3 and the AND circuit 4 are configured by hardware circuits. Therefore, the abnormality detector 3 and the AND circuit 4 can instantly switch the shutoff mechanism 2 to the shutoff state when the system voltage V1 falls below the abnormality threshold Vth.

[0036] The controller 5 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various other circuits. The controller 5 may also be configured with hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0037] The controller 5 controls the operation of the power supply control device 1 by having the CPU execute a power supply control program stored in the ROM using the RAM as a work area. The power supply control program may be stored in a storage device from the outside via a communication line or the like.

[0038] For example, during normal operation when no ground fault occurs, the controller 5 outputs a cutoff activation signal to the AND circuit 4. Furthermore, when a ground fault occurs and an abnormality detection signal S2 is input from the latch circuit 32, the controller 5 determines whether a power supply failure has occurred in the first system 110 or the second system 120. Then, the controller 5 performs fail-safe control to supply power to the load using the system in which no ground fault has occurred.

[0039] Furthermore, the controller 5 diagnoses at a predetermined timing, for example, when the power is turned on, whether or not the breaking mechanism 2 can normally break the connection between the first system 110 and the second system 120 when a ground fault occurs. Hereinafter, the operation of the power supply control device 1 controlled by the controller 5 will be described with reference to Figures 2 to 7.

[0040] [2. Normal operation of the power supply control device] 2, during normal operation when no ground fault occurs in the first system 110 or the second system 120, the controller 5 turns on the first switch 21 and the second switch 22 and turns off the bypass switch 23 and the battery switch 24. This causes power to be supplied from the main power supply 10 to the first load 101 and the second load 102.

[0041] [3. Operation of power supply control device when a ground fault occurs] 3, for example, when a ground fault 200 occurs in the first system 110, the system voltage V1 drops below the abnormality threshold Vth. Therefore, the power supply control device 1 outputs an abnormality detection signal S4 from the abnormality detector 3 to the cutoff mechanism 2 and the battery switch 24 via the AND circuit 4, and immediately turns off the first switch 21 and the second switch 22 and turns on the battery switch 24.

[0042] In this way, the power supply control device 1 cuts off the connection between the first system 110 and the second system 120 (hereinafter, this may be referred to as "pre-cutoff"), and connects the backup power supply 20 to the second load 102. Thereafter, the controller 5 makes a final determination as to whether the ground fault 200 has occurred in the first system 110 or the second system 120.

[0043] At this time, the controller 5 turns on the first switch 21 from the pre-shutdown state, for example. In this case, since the ground fault 200 has occurred in the first system 110, the system voltage V1 detected by the voltage sensor 6 does not return to or exceed the abnormality threshold Vth.

[0044] Thereafter, the controller 5 turns off the first switch 21, returns to the pre-shutdown state, and then turns on the second switch 22. This causes a voltage to be applied from the backup power supply 20 to the voltage sensor 6. As a result, the system voltage V1 detected by the voltage sensor 6 returns to above the abnormality threshold Vth.

[0045] In this way, the controller 5 alternately turns on the first switch 21 and the second switch 22 from the pre-shutdown state, and if the system voltage V1 returns to above the abnormal threshold Vth only when the second switch 22 is turned on, it makes a final judgment that there is a ground fault 200 in the first system 110.

[0046] The controller 5 continues the pre-shutdown state when it has finally determined that there is a ground fault 200 in the first system 110. Specifically, as shown in Fig. 4, the controller 5 controls the shutoff mechanism 2 and the battery switch 24 to maintain the shutoff mechanism 2 in the shutoff state and to keep the battery switch 24 on.

[0047] As a result, even if the one-shot pulse signal output from the latch circuit 32 switches from High to Low, the controller 5 can continue to supply power from the backup power supply 20 to the second load 102 and perform fail-safe control.

[0048] In addition, the controller 5 alternately turns on the first switch 21 and the second switch 22 from the pre-shutdown state, and if the system voltage V1 returns to or exceeds the abnormal threshold value Vth only when the first switch 21 is turned on, it makes a final determination that there is a ground fault in the second system 120.

[0049] In this case, the controller 5 controls the cutoff mechanism 2 and the battery switch 24 to maintain the cutoff mechanism 2 in the cutoff state and turn off the battery switch 24. This allows the controller 5 to perform fail-safe control by continuing to supply power from the main power supply 10 to the first load 101 while preventing the backup power supply 20 from discharging.

[0050] The controller 5 alternately turns on the first switch 21 and the second switch 22 from the pre-shutdown state, and if the system voltage V1 returns to or exceeds the abnormal threshold Vth in both cases, it determines that this is a temporary voltage drop and that no ground fault has occurred. In this case, the controller 5 returns the first switch 21, the second switch 22, and the battery switch 24 to the normal states shown in FIG. 2.

[0051] In the above description, the pre-shutdown and the final determination are performed using a single voltage sensor 6, but this is not limiting. For example, in addition to the voltage sensor 6, a voltage sensor may be provided for each of the first system 110 and the second system 120. The comparator 31 performs pre-shutdown by comparing the first system voltage detected by the voltage sensor of the first system 110 or the second system voltage detected by the voltage sensor of the second system 120 with a ground fault threshold. When the controller 5 receives the abnormality detection signal S4 from the AND circuit 4, it maintains the first switch 21 and the second switch 22 in a cut-off state and maintains the battery switch 24 in a conductive state. Thereafter, the controller 5 determines whether the first system voltage and the second system voltage remain below the ground fault threshold or have recovered to above the ground fault threshold. The controller 5 determines whether a system that has recovered to above the ground fault threshold is a normal system, and determines whether a system that remains below the ground fault threshold is a ground fault system.

[0052] When the voltage sensor 6 is used to perform the pre-shutdown and the main determination, only one voltage sensor is required, which leads to cost reduction, but the main determination process requires alternately turning on and off the first switch 21 and the second switch 22 to determine whether the system has a ground fault, which takes some time. In contrast, when the main determination is performed using the first system voltage and the second system voltage, although the additional voltage sensors increase costs, the time required for the main determination can be reduced because the ground fault states of the first system 110 and the second system 120 can be determined in parallel. Which determination method to use can be determined based on the required specifications.

[0053] In the following description, the explanation will be continued by taking as an example a configuration in which the voltage sensor 6 is used to perform the pre-shutdown and the main determination.

[0054] [4. Power supply control device diagnostic operation] When the system voltage V1 falls below the lower limit (ground fault threshold) of the system voltage V1 under normal conditions when no ground fault has occurred, the power supply control device 1 must immediately pre-shut off the interrupting mechanism 2 to prevent discharge from the main power supply 10 or the backup power supply 20 to the ground fault point. For this reason, the controller 5 diagnoses whether the circuit that shuts off the interrupting mechanism 2 will operate normally in the event of a power supply failure. The controller 5 performs this diagnosis at a predetermined timing while the vehicle is not running, for example, immediately after the ignition is turned on or immediately after the ignition is turned off.

[0055] In normal mode where no ground fault occurs, the controller 5 outputs a PWM (Pulse Width Modulation) signal as the abnormality threshold Vth to the comparator 31. As shown in Fig. 5, the abnormality threshold Vth (the normal value indicated by the solid line) increases as the duty ratio of the PWM signal increases, and decreases as the duty ratio decreases.

[0056] For this reason, the controller 5 diagnoses whether the relationship between the duty ratio of the PWM signal output to the comparator 31 and the abnormal threshold Vth has shifted upward or downward due to, for example, aging of the comparator 31. An upward shift refers to a state in which the abnormal threshold Vth is higher than the normal value, and a downward shift refers to a state in which the abnormal threshold Vth is lower than the normal value. If an upward or downward shift is detected, the controller 5 corrects the shift.

[0057] For example, if the relationship between the duty ratio and the abnormality threshold Vth is shifted upward, the controller 5 sets a higher abnormality threshold Vth than the normal value in the comparator 31. In this case, the controller 5 performs a correction to reduce the duty ratio of the PWM signal so that the comparator 31 does not output the abnormality detection signal S1 even when no ground fault has occurred.

[0058] Furthermore, when the relationship between the duty ratio and the abnormality threshold Vth deviates downward, the controller 5 sets a lower abnormality threshold Vth than the normal value in the comparator 31. In this case, the controller 5 performs a correction to increase the duty ratio of the PWM signal so that the comparator 31 does not fail to output the abnormality detection signal S1 even when a ground fault has occurred.

[0059] 6, in the diagnosis mode, the controller 5 turns on the bypass switch 23 from the normal state. After that, the controller 5 adjusts the abnormality threshold Vth to be equal to or greater than the value of the system voltage V1, and diagnoses whether the disconnecting mechanism 2 should disconnect the connection between the first system 110 and the second system 120.

[0060] For example, instead of intentionally lowering the system voltage V1 until it becomes less than the abnormal threshold Vth to recreate a ground fault state, the controller 5 raises the abnormal threshold Vth to a value equal to or greater than the system voltage V1 to recreate a ground fault state and diagnoses whether the circuit breaker 2 will break.

[0061] That is, in the diagnosis mode, the controller 5 reproduces a ground fault state by adjusting the abnormality threshold Vth without manipulating the system voltage V1, and diagnoses whether or not the breaking mechanism 2 will break. This allows the controller 5 to prevent the power supply to the first load 101 and the second load 102 from being interrupted in the diagnosis mode, and therefore allows diagnosis to be performed without adversely affecting the first load 101 and the second load 102.

[0062] When the abnormality threshold Vth becomes equal to or greater than the system voltage V1, the comparator 31 outputs an abnormality detection signal S1, and the power supply control device 1 then shuts off the cutoff mechanism 2 and turns on the battery switch 24 in response to an abnormality detection signal S4 output from the AND circuit 4, as shown in FIG. 7.

[0063] When the first switch 21 and the second switch 22 are turned off, the voltage sensor 6 stops detecting voltage, that is, the detected voltage becomes 0 [V]. Therefore, the controller 5 can obtain, for example, the timing when the voltage input from the voltage sensor 6 becomes equal to or lower than the abnormal threshold value Vth as the timing when the cutoff mechanism 2 has cut off. Note that the bypass switch 23 is maintained in the on state.

[0064] That is, the controller 5 keeps the bypass switch 23 in the OFF state in the normal mode, and keeps the bypass switch 23 in the ON state in the diagnosis mode. This allows the controller 5 to continue supplying power from the main power supply 10 to the first load 101 and the second load 102 via the bypass switch 23, even if the timing at which the cutting mechanism 2 is cut off is earlier than the timing at which the battery switch 24 is turned on. Therefore, the controller 5 can perform diagnosis without interrupting the power supply from the main power supply 10 to the second system 120.

[0065] Then, in the diagnostic mode, the controller 5 determines whether the system voltage V1 when the cutoff mechanism 2 cuts off differs from the abnormality threshold Vth corresponding to the duty ratio of the PWM signal output to the comparator 31 at that time.

[0066] When the controller 5 determines that the system voltage V1 at this time is different from the abnormality threshold Vth, the controller 5 corrects the abnormality threshold Vth used in the normal mode based on the abnormality threshold Vth when the breaking mechanism 2 broke the connection.

[0067] As a result, even if the controller 5 outputs a PWM signal with a duty ratio corresponding to the normal abnormal threshold value Vth to the comparator 31, if the normal abnormal threshold value Vth is not set in the comparator 31 due to changes over time, the controller 5 can correct the abnormal threshold value Vth to a normal value.

[0068] [5. Specific examples of diagnostic methods using controllers] Next, a specific example of a diagnostic method by the controller 5 will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is an explanatory diagram showing an example of adjusting the duty ratio in the diagnostic mode according to the embodiment. Fig. 9 is an explanatory diagram showing an example of adjusting the abnormality threshold Vth in the diagnostic mode according to the embodiment.

[0069] Here, an example will be described in which the normal abnormality threshold Vth is 11.5 V and the system voltage V1 in the diagnosis mode is 13.5 V. Also, here, if the performance of the comparator 31 has not deteriorated over time, the abnormality threshold Vth is set to 11.5 V when the duty ratio of the PWM signal is 40%, and the abnormality threshold Vth is set to 13.5 V when the duty ratio is 50.0%.

[0070] In this case, in the diagnosis mode, the controller 5 adjusts the abnormality threshold Vth so that it varies within the range of the system voltage V1±0.5 [V]. That is, the controller 5 adjusts the abnormality threshold Vth so that it varies between 49.5 [V] and 50.5 [V].

[0071] Specifically, the controller 5 increases the duty ratio of the PWM signal from 40% to 49.5% at time t1 when the normal mode is switched to the diagnosis mode, as shown in Fig. 8. As a result, the abnormality threshold Vth increases to 13.0 V at time t2, as shown by the solid line in Fig. 9.

[0072] Thereafter, the controller 5 gradually increases the duty ratio of the PWM signal in increments of 0.1% between time t1 and time t3. As a result, if the performance of the comparator 31 has not deteriorated over time, the comparator 31 should set the abnormality threshold Vth that exceeds the grid voltage V1 after time t3, and output the abnormality detection signal S1.

[0073] In this case, the system voltage V1 becomes less than the abnormality threshold Vth after time t3, so the comparator 31 outputs the abnormality detection signal S1. As a result, the shutoff mechanism 2 shuts off after time t3. Therefore, if the shutoff mechanism 2 shuts off after time t3, the controller 5 determines that the abnormality threshold Vth is set to the normal value of 11.5 [V], that is, the comparator 31 is normal.

[0074] In contrast to this, for example, as shown by the dotted line in Figure 9, if the abnormal threshold value Vth set in the comparator 31 has shifted downward, the comparator 31 may set the abnormal threshold value Vth to 13.4 [V] even if a PWM signal with a duty ratio of 50.0 [%] is input at time t3.

[0075] In this case, the comparator 31 does not output the abnormality detection signal S1 because the abnormality threshold Vth does not exceed the system voltage V1. Therefore, the shutoff mechanism 2 does not shut off at time t3. After that, the controller 5 outputs the PWM signal to the comparator 31 in increments of 0.1% from time t3 onwards until the duty ratio reaches 50.5%.

[0076] 9, when the abnormality threshold Vth is set to 13.5 V at time t4 when the duty ratio becomes 50.1%, the comparator 31 outputs the abnormality detection signal S1 because the system voltage V1 becomes less than the abnormality threshold Vth after time t4. As a result, the shutoff mechanism 2 shuts off after time t4. When the controller 5 detects the abnormality detection signal S4 output in response to the abnormality detection signal S1, it stops increasing the duty ratio of the PWM signal.

[0077] At this time, the controller 5 determines that the abnormal threshold Vth has shifted downward, and that the initial duty ratio of 40% is insufficient by 0.1% in order to set the normal abnormal threshold Vth.

[0078] In this case, the controller 5 corrects the duty ratio of the PWM signal output to set the abnormality threshold Vth used in the normal mode by increasing it from 40% to 40.1%. As a result, even if the performance of the comparator 31 has deteriorated over time, the controller 5 can set the abnormality threshold Vth to the normal value of 11.5V by outputting a PWM signal with a duty ratio of 40.1% to the comparator 31.

[0079] If the abnormality threshold Vth is shifted upward, the duty ratio of the PWM signal is similarly corrected. For example, if the blocking mechanism 2 is blocked when the duty ratio of the PWM signal is 49.9%, the controller 5 corrects the duty ratio of the PWM signal output to set the abnormality threshold Vth used in the normal mode by reducing it from 40% to 39.9%.

[0080] As a result, even if the performance of the comparator 31 has deteriorated over time, the controller 5 can set the abnormal threshold Vth to the normal value of 11.5 [V] by outputting a PWM signal with a duty ratio of 39.9 [%] to the comparator 31.

[0081] In this way, when the controller 5 sets the abnormality threshold Vth in the normal mode using a PWM signal with a first duty ratio, in the diagnostic mode, the controller 5 changes the duty ratio of the PWM signal to a value equal to or greater than the second duty ratio corresponding to the system voltage V1 to adjust the abnormality threshold Vth.

[0082] Then, the controller 5 sets the corrected abnormality threshold Vth using a fourth duty ratio obtained by correcting the first duty ratio based on the difference between the third duty ratio of the PWM signal when the connection between the first system 110 and the second system 120 is cut off and the second duty ratio.

[0083] As a result, when the abnormality threshold Vth set in the comparator 31 deviates upward or downward, the controller 5 can correct the deviated abnormality threshold Vth to the normal abnormality threshold Vth.

[0084] [6. Processes performed by the controller] Next, the processing executed by the controller 5 will be described with reference to Fig. 10. Fig. 10 is a flowchart showing an example of the processing executed by the controller 5 according to the embodiment. When the vehicle is started, the controller 5 enters a diagnostic mode and executes the processing shown in Fig. 10. First, the controller 5 sends a control signal (shutdown enable signal) to the AND circuit 4 (step S101). Next, the controller 5 turns on the cutoff mechanism 2, turns off the battery switch 24 (step S102), and turns on the bypass switch 23 (step S103).

[0085] Next, the controller 5 acquires the system voltage V1 (step S104). After that, the controller 5 adjusts the duty ratio of the PWM signal (step S105), and determines whether the cutoff mechanism 2 has cut off (step S106).

[0086] At this time, the controller 5 changes the duty ratio of the PWM signal in steps of 0.1% so that the abnormality threshold Vth varies within the range of the system voltage V1±0.5V, and each time, repeats the process of determining whether the cut-off mechanism 2 has cut off.

[0087] Then, the controller 5 determines whether the cutoff mechanism 2 has cut off (step S106). If the controller 5 determines that the cutoff mechanism 2 has not cut off despite raising the abnormality threshold Vth to the grid voltage V1+0.5 [V] (step S106, No), the deviation of the abnormality threshold Vth exceeds +0.5 [V], and therefore the controller 5 determines that the comparator 31 has failed (step S107), and ends the processing. This allows the controller 5 to accurately determine that the comparator 31 has failed. In this case, the controller 5 may be configured to, for example, display a message in the vehicle cabin, such as "The automatic driving function cannot be used due to a failure of the power supply device."

[0088] Furthermore, when it is determined that the shutoff mechanism 2 has shut off (Yes in step S106), the controller 5 determines whether the shutoff process of the shutoff mechanism 2 was as expected (step S108). If the shutoff mechanism 2 has shut off by outputting a PWM signal adjusted to a duty ratio that would set the abnormality threshold value Vth that coincides with the system voltage V1 if there is no aging change in the performance of the comparator 31, the controller 5 determines that the shutoff process was as expected.

[0089] Furthermore, if the controller 5 outputs a PWM signal adjusted to a duty ratio that would set the abnormal threshold value Vth that matches the system voltage V1 if there were no change over time in the performance of the comparator 31, but the cut-off mechanism 2 does not cut off, the controller 5 determines that the cut-off process was not as expected.

[0090] When the controller 5 determines that the shutdown process is as expected (Yes at step S108), the controller 5 transmits a control signal (shutdown invalidation signal) to the AND circuit 4 (step S109).

[0091] Next, the controller 5 returns each of the first switch 21, the second switch 22, the bypass switch 23, and the battery switch 24 to the normal state (see FIG. 2) (step S110). After that, the controller 5 sets the initial abnormality threshold Vth by outputting a PWM signal whose duty ratio has been returned to the value before adjustment to the comparator 31 (step S111), and proceeds to step S112.

[0092] Furthermore, if the controller 5 determines that the cutoff process was not as expected (step S108, No), it sends a control signal (cutoff invalidation signal) to the AND circuit 4 (step S113). Subsequently, the controller 5 returns each of the first switch 21, the second switch 22, the bypass switch 23, and the battery switch 24 to their normal states (see FIG. 2) (step S114). Thereafter, the controller 5 corrects and resets the abnormality threshold Vth based on the duty ratio when the cutoff mechanism 2 cut off (step S115), and proceeds to step S112.

[0093] In step S112, after a certain time has elapsed, the controller 5 sends a control signal (shutdown enable signal) to the AND circuit 4 and ends the process. The certain time here is the time from when the duty ratio of the PWM signal is returned to or reset to its original value until the abnormal threshold Vth reaches a voltage corresponding to the duty ratio.

[0094] In this way, in the diagnostic mode, the controller 5 sends a control signal (disconnection enabling signal) to the AND circuit 4 to enable the abnormality detection signal S1 until it confirms that the connection between the first system 110 and the second system 120 is disconnected.

[0095] Thereafter, the controller 5 sends a control signal (shutdown disabling signal) to the AND circuit 4 to disable the abnormality detection signal S1 until the abnormality threshold Vth is returned to the value before adjustment or corrected and reset.

[0096] This allows the power supply control device 1 to prevent the cut-off mechanism 2 from being cut off even if the system voltage V1 fluctuates and drops slightly while returning or resetting the adjusted abnormality threshold Vth to its original value.

[0097] [7. Notes] As an appendix, the features of the present invention are as follows. (1) a cutoff mechanism that cuts off a connection between a first system that supplies power from the main power source to the load and a second system that supplies power from the backup power source to the load; an abnormality detector that compares a system voltage, which is a voltage of the first system or the second system, with an abnormality threshold in a normal mode, and outputs an abnormality detection signal when the system voltage falls below the abnormality threshold, thereby causing the cutoff mechanism to cut off the connection between the first system and the second system; a controller that adjusts the abnormality threshold value to be equal to or greater than the value of the system voltage in a diagnostic mode and diagnoses whether the cutoff mechanism will cut off the connection between the first system and the second system; A power supply control device comprising: (2) a gate circuit that enables or disables the abnormality detection signal input from the abnormality detector in response to a control signal input from the controller; The controller In the diagnostic mode, the abnormality detection signal is enabled until disconnection of the first system and the second system is confirmed, and thereafter, the abnormality detection signal is disabled until the abnormality threshold is returned to a value before adjustment or is reset. The power supply control device according to (1) above. (3) a bypass switch that bypasses the cutoff mechanism; The controller The bypass switch is maintained in an off state in the normal mode, and the bypass switch is maintained in an on state in the diagnostic mode. The power supply control device according to (1) or (2). (4) The controller If the abnormality threshold value and the value of the system voltage when the connection between the first system and the second system is interrupted in the diagnostic mode are different, the abnormality threshold value used in the normal mode is corrected based on the abnormality threshold value when the connection between the first system and the second system is interrupted. The power supply control device according to any one of (1) to (3). (5) The controller When the abnormality threshold value used in the normal mode is set by a PWM signal having a first duty ratio, the duty ratio of the PWM signal is changed in the diagnostic mode to a second duty ratio or higher corresponding to the system voltage, thereby adjusting the abnormality threshold value; The abnormality threshold value after correction is set by a fourth duty ratio obtained by correcting the first duty ratio based on a difference between a third duty ratio of the PWM signal when the connection between the first system and the second system is interrupted and the second duty ratio. The power supply control device according to any one of (1) to (4). (6) The controller When the duty ratio of the PWM signal is changed to a second duty ratio or more to adjust the abnormality threshold, if the connection between the first system and the second system is not interrupted, it is determined that an abnormality has occurred. The power supply control device according to claim 5. (7) a cutoff mechanism that cuts off a connection between a first system that supplies power from the main power source to the load and a second system that supplies power from the backup power source to the load; an abnormality detector that compares a system voltage, which is the voltage of the first system or the second system, with an abnormality threshold in a normal mode, and outputs an abnormality detection signal to the cutoff mechanism to cut off the connection between the first system and the second system when the system voltage falls below the abnormality threshold; A controller of a power supply control device comprising: In a diagnostic mode, the abnormality threshold is adjusted to be equal to or greater than the value of the system voltage, and a diagnosis is made as to whether or not the cutoff mechanism will cut off the connection between the first system and the second system. Diagnostic program.

[0098] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0099] 1 Power supply control device 2. Shut-off mechanism 3 Anomaly Detector 4 AND Circuit 5 Controller 6 Voltage Sensor 10 Main power supply 20 Backup power supply 21 First Switch 22 Second Switch 23 Bypass switch 24 Battery switch 31 Comparator 32 Latch circuit 101 1st load 102 2nd load 110 1st system 120 2nd system 200 Earth fault S1 Abnormality detection signal V1 System voltage Vth Abnormal threshold

Claims

1. a disconnection mechanism that disconnects a first system that supplies power from the main power supply to the load and a second system that supplies power from the backup power supply to the load; an abnormality detector that compares a system voltage, which is a voltage of the first system or the second system, with an abnormality threshold in a normal mode, and outputs an abnormality detection signal when the system voltage falls below the abnormality threshold, thereby causing the cutoff mechanism to cut off the connection between the first system and the second system; a controller that adjusts the abnormality threshold value to be equal to or greater than the value of the system voltage in a diagnostic mode and diagnoses whether the cutoff mechanism will cut off the connection between the first system and the second system; A power supply control device comprising:

2. a gate circuit that enables or disables the abnormality detection signal input from the abnormality detector in response to a control signal input from the controller; The controller In the diagnostic mode, the abnormality detection signal is enabled until disconnection of the first system and the second system is confirmed, and thereafter, the abnormality detection signal is disabled until the abnormality threshold is returned to a value before adjustment or is reset. The power supply control device according to claim 1 .

3. a bypass switch that bypasses the cutoff mechanism; The controller The bypass switch is maintained in an off state in the normal mode, and the bypass switch is maintained in an on state in the diagnostic mode. The power supply control device according to claim 1 .

4. The controller If the abnormality threshold value and the value of the system voltage when the connection between the first system and the second system is interrupted in the diagnostic mode are different, the abnormality threshold value used in the normal mode is corrected based on the abnormality threshold value when the connection between the first system and the second system is interrupted. The power supply control device according to claim 1 .

5. The controller When the abnormality threshold value used in the normal mode is set by a PWM signal having a first duty ratio, the duty ratio of the PWM signal is changed in the diagnostic mode to a second duty ratio or higher corresponding to the system voltage, thereby adjusting the abnormality threshold value; The abnormality threshold value after correction is set by a fourth duty ratio obtained by correcting the first duty ratio based on a difference between a third duty ratio of the PWM signal when the connection between the first system and the second system is interrupted and the second duty ratio. The power supply control device according to claim 1 .

6. The controller When the duty ratio of the PWM signal is changed to a second duty ratio or more to adjust the abnormality threshold, if the connection between the first system and the second system is not interrupted, it is determined that an abnormality has occurred. The power supply control device according to claim 5 .

7. a disconnection mechanism that disconnects a first system that supplies power from the main power supply to the load and a second system that supplies power from the backup power supply to the load; an abnormality detector that compares a system voltage, which is a voltage of the first system or the second system, with an abnormality threshold in a normal mode, and outputs an abnormality detection signal to the cutoff mechanism to cut off the connection between the first system and the second system when the system voltage falls below the abnormality threshold; A controller of a power supply control device comprising: In a diagnostic mode, the abnormality threshold is adjusted to be equal to or greater than the value of the system voltage, and a diagnosis is made as to whether or not the cutoff mechanism will cut off the connection between the first system and the second system. Diagnostic program.

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