Power supply control device, power supply control program, and power supply control system

Abstract

To provide a power supply control device, a power supply control program, and a power supply control system capable of determining welding of a switch with high accuracy.SOLUTION: The power supply control device according to the embodiment determines that the first positive electrode switch is not welded when a first voltage detected at a first node between the second positive electrode switch and the load is equal to or higher than a threshold value and a second voltage detected at a second node between the first positive electrode switch and the second positive electrode switch is lower than the threshold value in a case where an off-instruction is output to the first positive electrode switch, the second positive electrode switch, and the negative electrode switch.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply control device, a power supply control program, and a power supply control system. [Background technology]

[0002] Conventionally, there is known a power supply control device that can diagnose whether a switch that connects a power supply to a circuit is welded without providing a precharge circuit (see, for example, Patent Document 1). Patent Document 1 discloses a circuit in which a capacitor and a DC-DC converter are connected in parallel to a DC power supply. Patent Document 1 also determines that the switch is normal (not welded) if the capacitor voltage drops below a threshold value by driving the DC-DC converter after the switch is turned off. Patent Document 1 also determines that the switch is welded if the capacitor voltage remains above the threshold value even after driving the DC-DC converter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-295699 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, if the charge in the capacitor cannot be discharged due to a failure of the DC-DC converter or the like, the voltage of the capacitor does not drop, and there is a risk that the switch may be erroneously determined to be welded even though it is normal. As such, there was room for improvement in the past in terms of accurately determining whether the switch is welded.

[0005] The present invention has been made in view of the above, and has an object to provide a power supply control device, a power supply control program, and a power supply control system that can determine whether a switch is welded with high accuracy. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the object, a power supply control device according to the present invention includes a controller. The controller controls a power supply circuit including: a power supply that supplies power to a load; a first positive switch and a second positive switch connected in series to the positive terminal of the power supply; a negative switch connected to the negative terminal of the power supply; a capacitor having one end connected to the positive terminal of the power supply via the first positive switch and the second positive switch and the other end connected to the negative terminal of the power supply via the negative switch; and a discharge circuit connected in parallel to the capacitor. When the controller outputs an OFF command to the first positive switch, the second positive switch, and the negative switch, if a first voltage detected at a first node between the second positive switch and the load is equal to or greater than a threshold and a second voltage detected at a second node between the first positive switch and the second positive switch is less than a threshold, the controller determines that the first positive switch is not welded. [Effects of the Invention]

[0007] According to the present invention, when the first voltage is equal to or greater than the threshold value and the second voltage is less than the threshold value, it is determined that the first positive switch is not welded. As a result, for example, when the capacitor voltage does not drop due to an abnormality in the DC-DC converter, that is, when the first voltage is equal to or greater than the threshold value but the second voltage is less than the threshold value, it is possible to determine that the first positive switch is normal. Therefore, according to the present invention, even when the capacitor voltage is equal to or greater than the threshold value despite the first positive switch being normal, by monitoring the second voltage, it is possible to reduce the possibility of incorrectly determining that the first positive switch is welded. In other words, according to the present invention, it is possible to perform a highly accurate determination of whether the switch is welded. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a power supply control system according to an embodiment. [Figure 2] FIG. 2 is a table summarizing examples of operations for each welding pattern. [Figure 3] FIG. 3 is a diagram showing a loop formed in the power supply circuit after an OFF instruction is sent to the first FET 111 to the fourth FET. [Figure 4] FIG. 4 is a diagram showing a current path when the discharge circuit operates normally. [Figure 5] FIG. 5 is a diagram showing a current path when the discharge circuit is inoperable due to an abnormality. [Figure 6] FIG. 6 is a diagram showing a loop formed in the power supply circuit after an OFF instruction is sent to the first FET 111 to the fourth FET. [Figure 7] FIG. 7 is a diagram showing a loop formed in the power supply circuit after an OFF instruction is sent to the first FET 111 to the fourth FET. [Figure 8] FIG. 8 is a diagram showing a current path when the discharge circuit operates normally. [Figure 9] FIG. 9 is a diagram showing a current path when the discharge circuit is inoperable due to an abnormality. [Figure 10] FIG. 10 is a diagram showing a loop formed in the power supply circuit after an OFF instruction is sent to the first FET 111 to the fourth FET. [Figure 11] FIG. 11 is a flowchart showing the procedure of the welding determination process of the power supply control device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply control device, a power supply control program, and a power supply control system according to embodiments will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments.

[0010] First, an example of the configuration of a power supply control system according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of a power supply control system according to an embodiment. The power supply control system S shown in Fig. 1 is a system that is mounted on a vehicle and supplies power from a DC power supply 110 to a load (not shown). The load is various electronic devices mounted on the vehicle.

[0011] 1, the power supply control system S includes a power supply control device 1 and a power supply circuit 10. The power supply control device 1 includes a controller 2 and a storage unit 3. The load described above is connected to the power supply circuit 10. Specifically, the load is connected across a first voltage sensor 14 of the power supply circuit 10.

[0012] The controller 2 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various other circuits. The controller 2 controls the power supply circuit 10 by the CPU executing programs stored in the ROM and storage unit 3, using the RAM as a working area. Note that the controller 2 may be partially or entirely configured with hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array).

[0013] The storage unit 3 is, for example, a RAM or a data flash. The storage unit 3 can store information about various programs, etc. The power supply control device 1 may acquire the above-mentioned programs and various information via another computer or portable recording medium connected via a wired or wireless network, and store the information in the storage unit 3.

[0014] The power supply circuit 10 includes a battery device 11, a capacitor 12, a discharge circuit 13, and a first voltage sensor 14. The capacitor 12, the discharge circuit 13, and the first voltage sensor 14 are connected in parallel to a DC power supply 110 included in the battery device 11. The capacitor 12, the discharge circuit 13, and the first voltage sensor 14 are connected to ground G2. The ground G2 is connected to the vehicle body. The capacitor 12, the discharge circuit 13, and the first voltage sensor 14 are disposed on the opposite side of the DC power supply 110, with the first FET 111 to the fourth FET 114 sandwiched between them. Similarly, a load (not shown) is disposed on the opposite side of the DC power supply 110, with the first FET 111 to the fourth FET 114 sandwiched between them.

[0015] The discharge circuit 13 is a DC-DC converter. The discharge circuit 13 performs a step-down operation to step down the voltage to a target voltage under the control of the controller 2, thereby discharging the charge accumulated in the capacitor 12 to the ground G2.

[0016] The first voltage sensor 14 detects the voltage of the positive electrode (first node) of the capacitor 12. Specifically, the first voltage sensor 14 detects the potential difference between the electrodes of the capacitor 12. The first voltage sensor 14 may be disposed midway between voltage-dividing resistors connected in parallel to the capacitor 12. For example, the voltage-dividing resistors are two resistors connected in series, and the first voltage sensor 14 is disposed between the two resistors. When voltage-dividing resistors are used, a threshold value used for welding determination, which will be described later, is set according to the values ​​of the two resistors.

[0017] The battery device 11 includes a DC power supply 110, a first FET (Field Effect Transistor) 111, a second FET 112, a third FET 113, a fourth FET 114, and a second voltage sensor 115. In the present disclosure, the first FET 111 corresponds to a first positive switch, the second FET 112 corresponds to a second positive switch, and the fourth FET 114 corresponds to a negative switch.

[0018] The DC power supply 110 is, for example, a lithium ion battery. The negative electrode of the DC power supply 110 is connected to a ground G1. The ground G1 is connected to the housing (case) of the DC power supply 110.

[0019] The first FET 111 and the second FET 112 are a pair of switches connected back-to-back. The first FET 111 includes a parasitic diode 111d. The second FET 112 includes a parasitic diode 112d. The cathode of the parasitic diode 111d is connected to the positive electrode of the DC power supply 110. The anode of the parasitic diode 111d is connected to the anode of the parasitic diode 112d. The cathode of the parasitic diode 112d is connected to the capacitor 12, the discharge circuit 13, and the first voltage sensor 14.

[0020] The third FET 113 and the fourth FET 114 are a pair of switches connected back-to-back. The third FET 113 includes a parasitic diode 113d. The fourth FET 114 includes a parasitic diode 114d. The cathode of the parasitic diode 113d is connected to the negative electrode of the DC power supply 110. The anode of the parasitic diode 113d is connected to the anode of the parasitic diode 114d. The cathode of the parasitic diode 114d is connected to the capacitor 12, the discharge circuit 13, and the first voltage sensor 14.

[0021] The second voltage sensor 115 has one end connected between the first FET 111 and the second FET 112 and the other end connected to the negative electrode of the DC power supply 110. The second voltage sensor 115 detects the voltage between the first FET 111 and the second FET 112 (second node). Specifically, the second voltage sensor 115 detects the potential difference between the potential between the first FET 111 and the second FET 112 and the negative electrode of the DC power supply 110. The second voltage sensor 115 may be disposed midway between voltage-dividing resistors connected in parallel to the DC power supply 110. For example, the voltage-dividing resistor is two resistors connected in series, and the second voltage sensor 115 is disposed between the two resistors. When voltage-dividing resistors are used, a threshold value used for welding determination (described later) is set according to the values ​​of the two resistors. Furthermore, if a current flows through the voltage-dividing resistors disposed before and after the second voltage sensor 115, a short circuit may occur. Therefore, it is preferable to use a high resistance value so that virtually no current flows through the voltage-dividing resistors.

[0022] The power supply control system S shown in FIG. 1 controls the first FET 111 to the fourth FET 114 to supply power from the DC power supply 110 to a load and charge the DC power supply 110. Charging the DC power supply 110 is often performed by supplying power from a lead battery, for example. The lead battery is provided, for example, on the opposite side of the DC power supply 110, sandwiching the first FET 111 to the fourth FET 114 between the DC power supply 110 and the lead battery. During discharge of the DC power supply 110, a current flows from the DC power supply 110 to the load. Therefore, the power supply control device 1 supplies a current from the DC power supply 110 to the load by turning on the first FET 111 and the fourth FET 114 and turning off the second FET 112 and the third FET 113. Keeping the second FET 112 and the third FET 113 off also prevents a current from flowing back into the DC power supply 110. Furthermore, the power supply control device 1 supplies current to and charges the DC power supply 110 by turning off the first FET 111 and the fourth FET 114 and turning on the second FET 112 and the third FET 113. Furthermore, by turning off the first FET 111 and the fourth FET 114, it is possible to prevent current from flowing back from the DC power supply 110 to the load side.

[0023] This disclosure will describe in detail a method for the power supply control device 1 to determine whether or not the first FET 111 and the fourth FET 114 involved in discharging to a load are welded (stuck on). To determine whether or not they are welded, the power supply control device 1 turns off the first FET 111 to the fourth FET 114. Thereafter, the power supply control device 1 determines whether or not the first FET 111 and the fourth FET 114 are welded (stuck on) based on the voltages detected by the first voltage sensor 14 and the second voltage sensor 115. A specific method for determining whether or not they are welded will be described below with reference to FIGS. 2 to 10.

[0024] 2 to 10 show examples of operation of the power supply control system S. Fig. 2 is a table summarizing examples of operation for each welding pattern. Figs. 3 to 10 are diagrams showing current flows in each welding pattern.

[0025] As shown in FIG. 2, welding patterns are broadly classified into four types, Patterns 1 to 4. Specifically, Pattern 1 is a pattern in which the first FET 111 and the fourth FET 114 are welded. Pattern 2 is a pattern in which the first FET 111 is normal and the fourth FET 114 is welded. Pattern 3 is a pattern in which the first FET 111 is welded and the fourth FET 114 is normal. Pattern 4 is a pattern in which the first FET 111 and the fourth FET 114 are normal. FIG. 2 shows a first voltage V1 and a second voltage V2 that are detected during a period in which the first FET 111 to the fourth FET 114 are off and while the discharge circuit 13 is operating. The first voltage V1 is a voltage detected by the first voltage sensor 14, and the second voltage V2 is a voltage detected by the second voltage sensor 115. In FIG. 2, "High" indicates a voltage equal to or greater than a threshold, and "Low" indicates a voltage below the threshold.

[0026] The controller 2 determines patterns 1 to 4 based on the first voltage V1 and the second voltage V2. Specifically, if the first voltage V1 and the second voltage V2 detected after issuing an OFF instruction to the first FET 111 to the fourth FET 114 are equal to or greater than a threshold, the controller 2 determines that the situation corresponds to pattern 1 or 3. That is, the controller 2 determines that at least the first FET 111 is welded. On the other hand, if the first voltage V1 is equal to or greater than the threshold and the second voltage V2 is less than the threshold, the controller 2 determines that the situation corresponds to pattern 2 or 4. That is, the controller 2 determines that at least the first FET 111 is not welded.

[0027] As a result, for example, even if the first voltage V1 is equal to or higher than the threshold because the voltage of capacitor 12 does not drop due to an abnormality in discharge circuit 13, controller 2 can determine whether first FET 111 is welded by using second voltage V2. Therefore, according to the present disclosure, even if the voltage of capacitor 12 is equal to or higher than the threshold even though first FET 111 is normal, it is possible to prevent erroneous determination that first FET 111 is welded.

[0028] Furthermore, if the controller 2 determines that the pattern is pattern 1 or 3, it further drives the discharge circuit 13 and determines whether or not there is an abnormality in the discharge circuit 13 based on the first voltage V1 and the second voltage V2 after driving. Specifically, the controller 2 determines that the discharge circuit 13 is abnormal if the first voltage V1 and the second voltage V2 after issuing a drive instruction to the discharge circuit 13 are equal to or greater than a threshold value. Furthermore, if the first voltage V1 is less than the threshold value and the second voltage V2 is equal to or greater than a threshold value, the controller 2 determines that the discharge circuit 13 is normal and that only the first FET 111 is welded. Furthermore, if the first voltage V1 and the second voltage V2 are a value (High-α) that has dropped by the voltage drop amount α associated with the internal resistance component of the DC power supply 110, the controller 2 determines that the discharge circuit 13 is normal and that the first FET 111 and the fourth FET 114 are welded.

[0029] In this way, by monitoring the first voltage V1 and the second voltage V2 after driving the discharge circuit 13, the controller 2 can determine with high accuracy whether there is an abnormality in the discharge circuit 13 and the location of the fusion (whether it is only the first FET 111 or both the first FET 111 and the fourth FET 114).

[0030] The current flow during each welding pattern will be described in detail below.

[0031] (Pattern 1) First, welding pattern 1 shown in Fig. 2 will be described in detail with reference to Figs. 3 to 5. Fig. 3 is a diagram showing a loop formed in power supply circuit 10 after an OFF command is sent to first FET 111 to fourth FET 114. Fig. 4 is a diagram showing a current path when discharge circuit 13 operates normally. Fig. 5 is a diagram showing a current path when discharge circuit 13 cannot operate due to an abnormality. Furthermore, in Figs. 3 to 10, before an OFF command is sent from controller 2 to first FET 111 to fourth FET 114, first FET 111 to fourth FET 114 are in an ON state.

[0032] 3, when it is time to perform the welding determination process, the controller 2 issues an OFF instruction to the first FET 111 to the fourth FET 114. The timing for the welding determination process is, for example, immediately after the IG is turned on or at the time of the end process when the IG is turned off.

[0033] At this time, the first FET 111 and the fourth FET 114 are welded together and therefore remain on without being turned off. The second FET 112 and the third FET 113 are normal and therefore are turned off in response to the off command.

[0034] As a result, a loop including capacitor 12 and first voltage sensor 14 is formed. As a result, first voltage sensor 14 detects a High first voltage V1. Because DC power supply 110, first FET 111, and voltage sensor 115 form a loop, second voltage sensor 14 detects a High second voltage V2. As will be described in detail later, the combination of a High first voltage V1 and a High second voltage V2 is similar in pattern 3 (only first FET 111 is welded) as shown in FIGS. 2 and 7. That is, if the first voltage V1 and the second voltage V2 detected after issuing an OFF instruction to first FET 111 to fourth FET 114 are equal to or greater than a threshold, controller 2 determines that pattern 1 or 3 applies. That is, controller 2 determines that at least first FET 111 is welded.

[0035] When the first voltage V1 and the second voltage V2 are equal to or greater than the threshold value, the controller 2 controls the discharge circuit 13 to drive the discharge circuit 13. Here, the current flow when the discharge circuit 13 is normal and when it is abnormal will be described with reference to FIGS.

[0036] 4 shows the path of the current when the discharge circuit 13 is normal. As shown in FIG. 4, when the discharge circuit 13 is operating normally, the current passes through the DC power supply 110, the first FET 111, the second FET 112 (parasitic diode 112d), the discharge circuit 13, and reaches ground G2. Similarly, the charge stored in the capacitor 12 is also discharged to ground G2 via the discharge circuit 13. As the current flows in this manner, the second voltage V2 drops by the voltage of the internal resistance component (ESR: Equivalent Series Resistance) of the DC power supply 110. That is, the second voltage V2 is detected as High-α (the amount of voltage drop of the internal resistance component). Furthermore, because the positive terminal of the voltage sensor 14 has the same potential as the positive terminal of the DC power supply 110, the first voltage V1 drops from High to High-α. That is, when High-α is detected in the first voltage V1 and the second voltage V2, the controller 2 determines that the discharge circuit 13 is normal and that both the first FET 111 and the fourth FET 114 are welded.

[0037] Next, FIG. 5 shows a current path when the discharge circuit 13 is abnormal. As shown in FIG. 5, when the discharge circuit 13 is abnormal, the discharge circuit 13 cannot discharge the DC power supply 110, and therefore no current flows through the discharge circuit 13. In this case, a loop is formed that passes through the first FET 111, the second FET 112 (parasitic diode 112d), the capacitor 12, the fourth FET 114, and the third FET 113 (parasitic diode 113d). Because no discharge occurs by the discharge circuit 13, no voltage drop occurs according to the internal resistance component of the DC power supply 110. In other words, the first voltage V1 and the second voltage V2 remain high. In other words, when the first voltage V1 and the second voltage V2 are detected to be high, the controller 2 determines that the discharge circuit 13 is abnormal and that at least the first FET 111 is welded.

[0038] (Pattern 2) Next, welding pattern 2 shown in Fig. 2 will be described in detail with reference to Fig. 6. Fig. 6 is a diagram showing a loop formed in power supply circuit 10 after first FET 111 to fourth FET 114 are notified of an OFF instruction.

[0039] 6, when it is time to perform the welding determination process, the controller 2 issues an OFF instruction to the first FET 111 to the fourth FET 114. The timing for the welding determination process is, for example, immediately after the IG is turned on or at the time of the end process when the IG is turned off.

[0040] At this time, the fourth FET 114 is welded and therefore remains on without being turned off. The first FET 111, the second FET 112, and the third FET 113 are normal and therefore turned off in response to the off command.

[0041] As a result, the charge accumulated in capacitor 12 is discharged, and a current flows through a path passing through first voltage sensor 14. That is, a loop of the current path passing through capacitor 12 and first voltage sensor 14 is formed. As a result, first voltage sensor 14 detects a high first voltage V1. Furthermore, first FET 111 and second FET 112 are turned off, and the potential of voltage sensor 115 drops to the potential of ground G1. As a result, second voltage V2 becomes low. As will be described in detail later, as shown in FIGS. 2 and 10, the combination of a high first voltage V1 and a low second voltage V2 is similar in pattern 4 (no welding). That is, if the first voltage V1 detected immediately after issuing an OFF command to the first FET 111 to the fourth FET 114 is equal to or greater than the threshold value and the second voltage V2 is less than the threshold value, controller 2 determines that pattern 2 or 4 applies. That is, controller 2 determines that at least first FET 111 is not welded (normal).

[0042] In this case, the controller 2 does not drive the discharge circuit 13. This is because current can be supplied from the DC power supply 110 to the load as long as the first FET 111 is at least normal. In this embodiment, the controller 2 permits the operation of the load and performs evacuation running to stop the vehicle equipped with the power supply control system S at a safe position.

[0043] (Pattern 3) Next, welding pattern 3 shown in Fig. 2 will be described in detail with reference to Fig. 7 to Fig. 9. Fig. 7 to Fig. 9 are diagrams showing loops formed in power supply circuit 10 after first FET 111 to fourth FET 114 are notified of an OFF instruction.

[0044] 7, when it is time to perform the welding determination process, the controller 2 issues an OFF instruction to the first FET 111 to the fourth FET 114. The timing for the welding determination process is, for example, immediately after the IG is turned on or at the time of the end process when the IG is turned off.

[0045] At this time, the first FET 111 is welded and therefore remains on without being turned off. The second FET 112, the third FET 113 and the fourth FET 114 are normal and therefore turned off in response to the off command.

[0046] As a result, the charge accumulated in the capacitor 12 is discharged via the first voltage sensor 14. That is, a loop passing through the capacitor 12 and the first voltage sensor 14 is formed. As a result, the first voltage sensor 14 detects a high level as the first voltage V1. Furthermore, the second voltage sensor 115 detects a high level as the second voltage V2 because it detects the potential of the positive electrode of the DC power supply 110. Specifically, a loop passing through the DC power supply 110, the first FET 111, and the second voltage sensor 115 is formed. As described above, the combination in which the first voltage V1 is high and the second voltage V2 is high is also the same in pattern 1. That is, the controller 2 determines that the pattern is 1 or 3 when the first voltage V1 and the second voltage V2 detected immediately after issuing an OFF instruction to the first FET 111 to the fourth FET 114 are equal to or higher than the threshold value. That is, the controller 2 determines that at least the first FET 111 is welded.

[0047] When the first voltage V1 and the second voltage V2 are equal to or greater than the threshold value, the controller 2 issues a drive instruction to the discharge circuit 13 to drive the discharge circuit 13. Here, the current flow when the discharge circuit 13 is normal and when it is abnormal will be described with reference to FIGS.

[0048] 8 shows a current path when the discharge circuit 13 operates normally. As shown in FIG. 8, when the discharge circuit 13 operates normally, the charge accumulated in the capacitor 12 is discharged to ground G2 via the discharge circuit 13. As a result, the voltage sensor 14 detects a low level as the first voltage V1. Furthermore, because a loop is formed that passes through the DC power supply 110, the first FET 111, and the second voltage sensor 115, the voltage sensor 115 detects a high level as the second voltage V2. In other words, when the controller 2 detects a low level as the first voltage V1 and a high level as the second voltage V2, it determines that the discharge circuit 13 is normal and that only the first FET 111 is welded.

[0049] FIG. 9 shows a current path when the discharge circuit 13 is unable to operate due to an abnormality. As shown in FIG. 9, when the discharge circuit 13 is abnormal, the discharge circuit 13 does not discharge the charge accumulated in the capacitor 12. Because the capacitor 12 and the voltage sensor 14 form a loop, the charge accumulated in the capacitor 12 is discharged via a path passing through the first voltage sensor 14. As a result, the first voltage sensor 14 detects a high first voltage V1. Furthermore, because the DC power supply 110, the first FET 111, and the second voltage sensor 115 form a loop, the second voltage sensor detects a high second voltage V2. In other words, when a high is detected for both the first voltage V1 and the second voltage V2, the controller 2 determines that the discharge circuit 13 is abnormal and that at least the first FET 111 is welded.

[0050] (Pattern 4) Next, welding pattern 4 shown in Fig. 2 will be described in detail with reference to Fig. 10. Fig. 10 is a diagram showing a loop formed in power supply circuit 10 after first FET 111 to fourth FET 114 are notified of an OFF instruction.

[0051] 10, when it is time to perform the welding determination process, the controller 2 issues an OFF instruction to the first FET 111 to the fourth FET 114. The timing for the welding determination process is, for example, immediately after the IG is turned on or at the time of the end process when the IG is turned off.

[0052] At this time, all of the FETs, the first FET 111 to the fourth FET 114, are normal and are therefore turned off in response to the off instruction.

[0053] As a result, a loop passing through capacitor 12 and first voltage sensor 14 is formed. The charge accumulated in capacitor 12 is discharged through a path passing through first voltage sensor 14. That is, as a result, first voltage sensor 14 detects the first voltage V1 as High. The potential of second voltage sensor 115 becomes the same as the potential of ground G1. This is because first FET 111 and second FET 112 are turned off. As a result, second voltage sensor 115 detects the second voltage V2 as Low. Note that, as described above, the combination of the first voltage V1 being High and the second voltage V2 being Low is also the same in pattern 2. That is, if the first voltage V1 detected immediately after issuing an OFF instruction to the first FET 111 to the fourth FET 114 is equal to or higher than the threshold and the second voltage V2 is lower than the threshold, the controller 2 determines that the pattern is 2 or 4. That is, the controller 2 determines that at least the first FET 111 is not welded (normal).

[0054] In this case, the controller 2 does not drive the discharge circuit 13. This is because current can be supplied from the DC power supply 110 to the load as long as the first FET 111 is at least normal. In this embodiment, the controller 2 permits the operation of the load and performs evacuation running to stop the vehicle equipped with the power supply control system S at a safe position.

[0055] Next, the procedure for determining whether a power supply control device 1 according to the embodiment has welded will be described with reference to FIG. 11. FIG. 11 is a flowchart showing the procedure for determining whether a power supply control device 1 according to the embodiment has welded. The flowchart shown in FIG. 11 is executed when the timing for the process of determining whether a power supply control device 1 has welded is reached. In FIG. 11, the first FET 111 to the fourth FET 114 start out in an on state. That is, since the first FET 111 to the fourth FET 114 are in an on state, the capacitor 12 is in a state in which electric charge is accumulated due to the power supply from the DC power supply 110.

[0056] When the timing for the welding determination process arrives, the controller 2 issues an OFF instruction to the first FET 111 to the fourth FET 114 (step S101).

[0057] Next, after the OFF command, the controller 2 acquires the first voltage V1 from the first voltage sensor 14 and the second voltage V2 from the second voltage sensor 115 (step S102).

[0058] Next, the controller 2 determines whether (A) both the first voltage V1 and the second voltage V2 are equal to or greater than the threshold value (TH), or whether (B) the first voltage V1 is equal to or greater than the threshold value and the second voltage V2 is less than the threshold value (TH) (step S103).

[0059] If the first voltage V1 and the second voltage V2 are both equal to or greater than the threshold value (step S103: A), the controller 2 determines that the welding pattern is pattern 1 or pattern 3 (step S104). That is, the controller 2 determines that at least the first FET 111 is welded. On the other hand, if the first voltage V1 is equal to or greater than the threshold value and the second voltage V2 is less than the threshold value (step S103: B), the controller 2 determines that the welding pattern is pattern 2 or pattern 4 (step S105) and ends the process. That is, the controller 2 determines that at least the first FET 111 is not welded.

[0060] After step S104, the controller 2 drives the discharge circuit 13 (step S106), and detects the first voltage V1 and the second voltage V2 after driving (step S107).

[0061] Next, the controller 2 determines whether both the first voltage V1 and the second voltage V2 are equal to or greater than the threshold value (step S108). If both the first voltage V1 and the second voltage V2 are equal to or greater than the threshold value (step S108: Yes), the controller 2 determines that an abnormality has occurred in the discharge circuit 13 (step S109) and ends the process.

[0062] On the other hand, if both the first voltage V1 and the second voltage V2 are not equal to or greater than the threshold value (step S108: No), the controller 2 determines whether the second voltage V2 is less than the threshold value (A) or whether the first voltage V1 and the second voltage V2 have dropped by the voltage drop amount α associated with the internal resistance component of the DC power supply 110 (B) (step S110).

[0063] If the second voltage V2 is less than the threshold value (step S110: A), the controller 2 determines that the discharge circuit 13 is normal and that only the first FET 111 is welded (step S111), and ends the process.

[0064] On the other hand, if the first voltage V1 and the second voltage V2 have dropped by the voltage drop amount α associated with the internal resistance component of the DC power supply 110 (step S110: B), the controller 2 determines that the discharge circuit 13 is normal and that the first FET 111 and the fourth FET 114 are welded (step S112), and terminates the processing.

[0065] As described above, the power supply control device 1 according to the embodiment includes a controller 2. The controller 2 controls a power supply circuit 10 including a power supply (DC power supply 110) that supplies power to a load, a first positive switch (first FET 111) and a second positive switch (second FET 112) connected in series to the positive electrode of the power supply, a negative switch (fourth FET 114) connected to the negative electrode of the power supply, a capacitor 12 having one end connected to the positive electrode of the power supply via the first positive switch and the second positive switch and the other end connected to the negative electrode of the power supply via the negative switch, and a discharge circuit 13 connected in parallel to the capacitor 12. When the controller 2 outputs an OFF command to the first positive switch, the second positive switch, and the negative switch, the controller 2 determines that the first positive switch is not welded if a first voltage V1 detected at a first node between the second positive switch and the load is equal to or greater than a threshold and a second voltage V2 detected at a second node between the first positive switch and the second positive switch is less than a threshold.

[0066] According to the present disclosure, when the first voltage V1 is equal to or greater than a threshold value and the second voltage V2 is less than a threshold value, it is determined that the first positive switch is not welded. As a result, for example, when the capacitor voltage does not decrease due to an abnormality in the discharge circuit 13, that is, when the first voltage V1 is equal to or greater than the threshold value but the second voltage V2 is less than the threshold value, it is possible to determine that the first positive switch is normal. Therefore, according to the present disclosure, even when the voltage of the capacitor 12 is equal to or greater than a threshold value despite the first positive switch being normal, by monitoring the second voltage, it is possible to reduce the likelihood of erroneously determining that the first positive switch is welded.

[0067] In the above-described embodiment, an example is shown in which the discharge circuit 13 is driven in the cases of welding pattern 1 and pattern 3, but the discharge circuit 13 does not have to be driven in the cases of welding pattern 1 and pattern 3. Even in this case, the controller 2 can determine whether the first FET 111 is welded or not from the first voltage V1 and the second voltage V2.

[0068] 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]

[0069] 1 Power supply control device 2 Controller 3 Storage section 10 Power circuit 11 Battery device 12 Capacitors 13 Discharge circuit 14 First voltage sensor 110 DC power supply 111 1st FET 112 2nd FET 113 3rd FET 114 4th FET 115 Second voltage sensor S Power Control System

Claims

1. A power supply control device including a controller for controlling a power supply circuit having: a power supply that supplies power to a load; a first positive switch and a second positive switch connected in series to a positive electrode of the power supply; a negative switch connected to a negative electrode of the power supply; a capacitor having one end connected to the positive electrode of the power supply via the first positive switch and the second positive switch and the other end connected to the negative electrode of the power supply via the negative switch; and a discharge circuit connected in parallel to the capacitor, The controller When an OFF command is output to the first positive switch, the second positive switch, and the negative switch, if a first voltage detected at a first node between the second positive switch and the load is equal to or greater than a threshold value and a second voltage detected at a second node between the first positive switch and the second positive switch is less than a threshold value, it is determined that the first positive switch is not welded. Power control device.

2. The controller If the first voltage and the second voltage detected after the output of the OFF command are each equal to or greater than a threshold, it is determined that at least the first positive switch is welded, and the discharge circuit is driven. If the first voltage detected after the driving is equal to or greater than a threshold and the second voltage is less than a threshold, it is determined that the first positive switch is welded. The power supply control device according to claim 1 .

3. The controller When the first voltage and the second voltage detected after the discharge circuit is driven are equal to or greater than a threshold, the discharge circuit is determined to be abnormal. The power supply control device according to claim 2 .

4. The controller If the first voltage and the second voltage detected after the output of the OFF command are each equal to or greater than a threshold value, the discharge circuit is driven, and if the first voltage and the second voltage detected after the driving are values ​​that have dropped by an amount of voltage drop associated with an internal resistance component of the power supply, it is determined that the first positive electrode switch and the negative electrode switch are welded. The power supply control device according to claim 1 .

5. A power supply control program executed by a power supply control device that controls a power supply circuit having: a power supply that supplies power to a load; a first positive switch and a second positive switch connected in series to a positive electrode of the power supply; a negative switch connected to a negative electrode of the power supply; a capacitor having one end connected to the positive electrode of the power supply via the first positive switch and the second positive switch and the other end connected to the negative electrode of the power supply via the negative switch; and a discharge circuit connected in parallel to the capacitor, When an OFF command is output to the first positive switch, the second positive switch, and the negative switch, if a first voltage detected at a first node between the second positive switch and the load is equal to or greater than a threshold value and a second voltage detected at a second node between the first positive switch and the second positive switch is less than a threshold value, it is determined that the first positive switch is not welded. Power control program.

6. a power supply circuit including: a power supply that supplies power to a load; a first positive switch and a second positive switch connected in series to a positive electrode of the power supply; a negative switch connected to a negative electrode of the power supply; a capacitor having one end connected to the positive electrode of the power supply via the first positive switch and the second positive switch and the other end connected to the negative electrode of the power supply via the negative switch; and a discharge circuit connected in parallel to the capacitor; a power supply control device including a controller that controls the power supply circuit; Equipped with The controller When an OFF command is output to the first positive switch, the second positive switch, and the negative switch, if a first voltage detected at a first node between the second positive switch and the load is equal to or greater than a threshold value and a second voltage detected at a second node between the first positive switch and the second positive switch is less than a threshold value, it is determined that the first positive switch is not welded. Power control system.

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