Power control device and power control program

Abstract

To provide a power control device and a power control program that are capable of reducing damages at the time of disconnection of a switch.SOLUTION: A power control device includes an inter-system switch and a controller. The inter-system switch is provided to connect between a first system that supplies power from a first power supply to a first load and a second system that supplies power from a second power supply to a second load. When the remaining amount of the second power supply is less than a threshold, the controller supplies a current for charging from the first power supply to the second power supply via the inter-system switch; and when detecting a power supply failure during charging, disconnects the inter-system switch. When detecting a sign of the power supply failure based on failure factor information indicating a factor causing the power failure, the controller restricts the current to be supplied to the second power supply.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, a system has been known in which, when a first power supply that supplies power to a load fails, a second power supply supplies power in place of the first power supply. In this system, a technology has been disclosed in which, when the remaining charge of the second power supply becomes low, the first power supply supplies power via a DC-DC converter to charge the second power supply (see, for example, Patent Document 1).

[0003] Furthermore, Patent Document 1 discloses a technology in which, if a power supply abnormality such as a ground fault occurs while the second power supply is being charged, charging is forcibly terminated by shutting off a switch provided in the path connecting the first power supply and the second power supply. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-184690 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the prior art, the greater the current flowing through the switch during charging, the greater the damage to the switch when it is turned off in the event of a power supply abnormality, which may shorten the life of the switch.

[0006] The present application has been made in view of the above, and aims to provide a power supply control device and a power supply control program that can reduce damage when a switch is turned off. [Means for solving the problem]

[0007] A power supply control device according to the present application includes an inter-system switch and a controller. The inter-system switch is configured to connect a first system that supplies power from a first power source to a first load and a second system that supplies power from a second power source to a second load. When the remaining charge of the second power source falls below a threshold, the controller supplies current from the first power source to the second power source via the inter-system switch to charge the second power source, and shuts off the inter-system switch if a power supply abnormality is detected during charging. When the controller detects a sign of a power supply abnormality based on abnormality cause information that may cause the power supply abnormality, it limits the current supplied to the second power source. [Effects of the Invention]

[0008] According to one aspect of the embodiment, by limiting the charging current when a sign of a power supply abnormality is detected before it occurs, the current flowing through the inter-system switch can be reduced, thereby achieving the effect of reducing damage when the inter-system switch is shut off due to a power supply abnormality. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of the configuration and operation of a power supply control device according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram of the configuration and operation of the power supply control device according to the embodiment. [Figure 3] FIG. 3 is an explanatory diagram of the configuration and operation of the power supply control device according to the embodiment. [Figure 4] FIG. 4 is an explanatory diagram of the configuration and operation of the power supply control device according to the embodiment. [Figure 5] FIG. 5 is an explanatory diagram showing an example of operation of the power supply control device during normal charging of the backup power supply. [Figure 6] FIG. 6 is an explanatory diagram showing an example of operation of the power supply control device during limited charging of the backup power supply. [Figure 7] FIG. 7 is an explanatory diagram for explaining a method for detecting a symptom of a power supply abnormality. [Figure 8]FIG. 8 is a flowchart showing the procedure of the charging process executed by the controller. [Figure 9] FIG. 9 is a flowchart showing the procedure of the power supply abnormality detection process executed by the controller. [Figure 10] FIG. 10 is an explanatory diagram of the configuration and operation of a power supply control device according to another example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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. In the following, a case will be described in which a vehicle equipped with a power supply control device according to the embodiment is an electric vehicle or a hybrid vehicle.

[0011] The vehicle on which the power supply control device according to the embodiment is mounted may be an engine automobile that runs on an internal combustion engine. The power supply control device according to the embodiment is a device that is mounted on a vehicle with an automatic driving function and supplies power to a load.

[0012] [Configuration of power control device] The configuration and operation of a power supply control device 1 according to an embodiment will be described with reference to Figures 1 to 4. Figures 1 to 4 are explanatory diagrams of the configuration and operation of the power supply control device 1 according to an embodiment. As shown in Figure 1, the power supply control device 1 according to an embodiment is connected to a main power supply 10, a first load 101, a general load 102, and a second load 103. The first load 101 and the general load 102 correspond to the first load. The second load 103 corresponds to the second load.

[0013] 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, a general load 102, and a second load 103. The second system 120 is a power supply system that supplies power from a backup power supply 20 (described later) to the second load 103.

[0014] The first load 101 includes loads for automatic driving. The first load 101 includes, for example, a steering motor, an electric brake device, and an in-vehicle camera that operate during automatic driving. The general load 102 is a load that is not directly involved in automatic driving, and includes a display, an air conditioner, an audio, a video, and various lights.

[0015] The second load 103 includes a part of the functions for automatic driving provided by the first load 101. The second load 103 includes, for example, devices that are minimally required for FOP (Fail Operation, evacuation driving control) such as a steering motor, an electric brake device, and a radar. The first load 101, the general load 102, and the second load 103 operate by the electric power supplied from the power control device 1.

[0016] The first load 101 and the second load 103 perform automatic driving control of the vehicle by operating according to the control of an automatic driving control device (not shown). When a power failure such as a ground fault occurs in the first system 110 during the automatic driving of the vehicle, the automatic driving control device can perform FOP by the second load 103. Also, when a power failure such as a ground fault occurs in the second system 120, the automatic driving control device can perform FOP by the first load 101.

[0017] The main power source 10 includes a DC / DC converter (hereinafter referred to as "DC / DC11") and a lead battery (hereinafter referred to as "PbB12"). Note that the battery of the main power source 10 may be any secondary battery other than PbB12. Note that the main power source 10 is an example of the first power source.

[0018] DC / DC11 is connected to a generator and a high-voltage battery having a voltage higher than that of PbB12. DC / DC11 steps down the voltages of the generator and the high-voltage battery and outputs them to the first system 110. The generator is an alternator that generates electricity by converting the kinetic energy of the traveling vehicle into electricity. The high-voltage battery is a vehicle drive battery mounted on an electric vehicle or a hybrid vehicle.

[0019] When the main power supply 10 is installed in an engine vehicle, an alternator (generator) is provided instead of the DC / DC 11. The DC / DC 11 charges the PbB 12, supplies power to the first load 101 and the general load 102, supplies power to the second load 103, and charges the backup power supply 20 described later.

[0020] The power supply control device 1 includes a backup power supply 20, an inter-system switch 41, a battery switch 42, a bypass switch 43, a controller 3, a first voltage sensor 51, a second voltage sensor 52, and a DCDC converter (DC / DC) 23. The backup power supply 20 is a backup power supply when the power supply by the main power supply 10 becomes unavailable. The backup power supply 20 includes a lithium-ion battery (hereinafter referred to as "LiB 21"). The battery of the backup power supply 20 may be any secondary battery other than the LiB 21. Note that the backup power supply 20 is an example of a second power supply.

[0021] The inter-system switch 41 is provided on an inter-system line 130 that connects the first system 110 and the second system 120. The inter-system switch 41 is an example of a connection part that can connect and disconnect the first system 110 and the second system 120.

[0022] In the present embodiment, electrically connecting the first system 110 and the second system 120 by the inter-system switch 41 is referred to as conducting the inter-system switch 41 or turning on the inter-system switch 41.

[0023] Also, in the present embodiment, disconnecting the electrical connection between the first system 110 and the second system 120 by the inter-system switch 41 is referred to as interrupting the inter-system switch 41 or turning off the inter-system switch 41.

[0024] The battery switch 42 is a switch that connects the backup power supply 20 to the second system 120. In the embodiment, electrically connecting the backup power supply 20 and the second system 120 by the battery switch 42 is referred to as making the battery switch 42 conductive or turning on the battery switch 42.

[0025] In this embodiment, the disconnection of the electrical connection between the backup power supply 20 and the second system 120 by the battery switch 42 is referred to as shutting off the battery switch 42 or turning off the battery switch 42.

[0026] The bypass switch 43 is a switch that connects the battery switch 42 and the second system 120. The DC / DC 23 is connected in parallel with the bypass switch 43 and adjusts the voltage input to the LiB 21 during charging. In addition, in the present disclosure, if a sign of a power supply abnormality such as a ground fault is detected while the backup power supply 20 is being charged, the DC / DC 23 limits the current output to the backup power supply 20; this point will be described in detail later.

[0027] The first voltage sensor 51 is provided in the first system 110. The first voltage sensor 51 detects the voltage of the first system 110 and outputs the detection result to the controller 3. The second voltage sensor 52 is provided in the second system 120. The second voltage sensor 52 detects the voltage of the second system 120 and outputs the detection result to the controller 3.

[0028] The controller 3 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various other circuits. The controller 3 may also be configured with hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0029] The controller 3 controls the operation of the power supply control device 1 by having the CPU execute a program stored in the ROM using the RAM as a work area. The controller 3 controls the inter-system switch 41, the battery switch 42, the bypass switch 43, and the DC / DC converters 11 and 23.

[0030] The controller 3 also acquires a state value indicating the charging state of the backup power supply 20 from the backup power supply 20 via a state monitoring line 22. The state value indicating the charging state of the backup power supply 20 is, for example, a State Of Charge (SOC) indicating the remaining amount of the LiB 21.

[0031] When the SOC of the LiB 21 is 100%, the remaining charge of the LiB 21 is at its maximum. When the SOC of the LiB 21 is 0%, the remaining charge of the LiB 21 is zero. The controller 3 acquires, for example, the SOC of the LiB 21 as a state value indicating the charge state of the backup power supply 20. The controller 3 monitors the remaining charge of the backup power supply 20 based on the SOC of the LiB 21.

[0032] Furthermore, the controller 3 detects a power supply abnormality, such as a failure of the main power supply 10 or the backup power supply 20, based on the detection results input from the first voltage sensor 51 and the second voltage sensor 52. For example, the controller 3 detects a failure of the first system 110 or the second system 120. A failure of the main power supply 10 includes a ground fault in the first system 110 and a break in the first system 110. A failure of the backup power supply 20 includes a ground fault in the second system 120. When the controller 3 detects a failure of the first system 110 or the second system 120, it notifies the automatic operation control device of that fact.

[0033] Specifically, when the controller 3 detects a failure of the main power supply 10 or the backup power supply 20, it outputs an automatic operation prohibition signal indicating that automatic operation is not possible to the automatic operation control device. Furthermore, when the controller 3 does not detect a failure of the main power supply 10 or the backup power supply 20, it outputs an automatic operation permission signal indicating that automatic operation is possible to the automatic operation control device.

[0034] Further, when the controller 3 detects a failure in the main power supply 10 or the backup power supply 20, it stores diagnostic information indicating the same in the non-volatile memory. Then, if the diagnostic information is stored in the non-volatile memory at the next startup, the controller 3 prohibits the automatic driving by the automatic driving control device.

[0035] Specifically, the controller 3 prohibits the automatic driving by the automatic driving control device by outputting an automatic driving prohibition signal indicating that the automatic driving is impossible to the automatic driving control device. Thereby, after the evacuation driving is completed, the power supply control device 1 can prevent the automatic driving from being erroneously performed by the automatic driving control device at the next startup even though the failure in the main power supply 10 or the backup power supply 20 has not been eliminated.

[0036] [Normal Operation of Power Supply Control Device] During normal times when no failure occurs in the main power supply 10 and the backup power supply 20, the controller 3 controls the inter-system switch 41, the battery switch 42, and the bypass switch 43 as shown in FIG. 1. Specifically, the controller 3 shuts off the battery switch 42 and the bypass switch 43 and conducts the inter-system switch 41. Thereby, power is supplied from the main power supply 10 to the first load 101, the general load 102, and the second load 103. During normal times when no failure occurs in the main power supply 10 and the backup power supply 20, the controller 3 outputs an automatic driving permission signal to the automatic driving control device.

[0037] [Operation of Power Supply Control Device When Power Failure Occurs] Next, with reference to FIGS. 2 to 4, the operation of the power supply control device 1 when a power failure occurs will be described. The controller 3 compares the parameters related to the failure of the first system 110 or the second system 120 with the threshold value to detect the occurrence of a power failure.

[0038] Here, a case will be described where the parameter related to the failure of the main power supply 10 is the voltage of the first system 110, and the parameter related to the failure of the backup power supply 20 is the voltage of the second system 120. Hereinafter, the voltage of the first system 110 detected by the first voltage sensor 51 is referred to as the first system voltage V1. Also, the voltage of the second system 120 detected by the second voltage sensor 52 is referred to as the second system voltage V2.

[0039] Note that the parameter related to the failure of the main power supply 10 may be the current flowing through the first system 110 or the current flowing through the second system 120. In this case, the power supply control device 1 includes a current sensor that detects the current flowing through the first system 110 and a current sensor that detects the current flowing through the second system 120. Then, when the current flowing through the first system 110 or the current flowing through the second system 120 exceeds the overcurrent threshold, the controller 3 detects the occurrence of a ground fault.

[0040] As shown in FIG. 2, in the power supply control device 1, for example, when a ground fault 200 (see FIG. 3) occurs in the first system 110 or a ground fault 201 (see FIG. 4) occurs in the second system 120, an overcurrent flows toward the ground fault point. For this reason, the first system voltage V1 and the second system voltage V2 become equal to or lower than the ground fault threshold.

[0041] When the first system voltage V1 and the second system voltage V2 become equal to or lower than the ground fault threshold, the controller 3 tentatively determines that a ground fault 200 or a ground fault 201 has occurred in the first system 110 or the second system 120. Thereafter, the controller 3 outputs an automatic operation prohibition signal to the automatic operation control device.

[0042] Then, when the controller 3 tentatively determines that a ground fault 200 or a ground fault 201 has occurred, it turns off the inter-system switch 41 and turns on the battery switch 42 and the bypass switch 43. As a result, the connection between the first system 110 and the second system 120 is disconnected, so that power is supplied from the main power supply 10 to the first system 110 and power is supplied from the backup power supply 20 to the second system 120. Hereinafter, the interruption of the inter-system switch 41 based on the result of the tentative determination is also referred to as pre-interruption.

[0043] Further, when at least one of the first system voltage V1 and the second system voltage V2 becomes equal to or lower than the ground fault threshold value, the controller 3 can also tentatively determine that a ground fault has occurred in the first system 110 or the second system 120.

[0044] Note that this tentative determination may be made by a hardware circuit having a comparator. In that case, the comparator compares the second system voltage V2 (or the first system voltage V1) with the ground fault threshold value. When the detected voltage becomes equal to or lower than the ground fault threshold value, the comparator outputs a fault detection signal indicating the tentative determination, turns off the inter-system switch 41, and turns on the battery switch 42 and the bypass switch 43. After tentatively determining that a ground fault has occurred in the first system 110 or the second system 120, the controller 3 makes a final determination of the ground fault.

[0045] By turning off the inter-system switch 41 and turning on the battery switch 42 and the bypass switch 43, the controller 3 causes the system voltage of the system where no ground fault has occurred to return to the normal state, and the system voltage of the grounded system continues to decrease.

[0046] After pre-shutdown, when the first system voltage V1 continues to be equal to or lower than the ground fault threshold value for a predetermined period or longer and the second system voltage V2 returns to a value equal to or higher than the normal threshold value, which is higher than the ground fault threshold value, for a predetermined period or longer, the controller 3 makes a final determination that a ground fault 200 has occurred in the first system 110. The predetermined period here is, for example, 100 ms. Note that the predetermined period is not limited to 100 ms.

[0047] When the controller 3 determines that a ground fault 200 has occurred in the first system 110, as shown in FIG. 3, it performs fail-safe control to supply power from the backup power supply 20 to the second load 103, and notifies the automatic driving control device to that effect. As a result, the automatic driving control device can operate the second load 103 with the power supplied from the backup power supply 20, and can drive the vehicle to a safe place and stop it. Note that the fail-safe control may include interruption of the inter-system switch 41 by a provisional determination, conduction of the battery switch 42, and notification to the automatic driving control device at the time of this determination.

[0048] Further, after pre-interruption, when the first system voltage V1 returns until it continues to be equal to or higher than the normal threshold value for a predetermined period or more, and the second system voltage V2 continues to be equal to or lower than the ground fault threshold value for a predetermined period or more, the controller 3 determines that the first system 110 is normal and a ground fault 201 has occurred in the second system 120.

[0049] When the controller 3 determines that a ground fault 201 has occurred in the second system 120, as shown in FIG. 4, it turns off the battery switch 42 and performs fail-safe control to supply power from the main power supply 10 to the first load 101 and the general load 102. Then, the controller 3 notifies the automatic driving control device to that effect. As a result, the automatic driving control device can operate the first load 101 with the power supplied from the main power supply 10, and can drive the vehicle to a safe place and stop it.

[0050] Further, after pre-interruption, when both the first system voltage V1 and the second system voltage V2 return until they continue to be equal to or higher than the normal threshold value for a predetermined period or more, the controller 3 determines that it is a transient voltage drop and no ground faults 200 and 201 have occurred. That is, the controller 3 determines that both the first system 110 and the second system 120 are normal.

[0051] In this case, the controller 3 turns off the battery switch 42 and the bypass switch 43 from the pre-shutdown state shown in FIG. 2, turns on the inter-system switch 41, and returns to the normal operation state of FIG. 1. Thereby, the controller 3 can suppress the decrease in the stored power of the backup power supply 20.

[0052] [Operation during Backup Power Supply Charging] Next, with reference to FIGS. 5 and 6, the charging operation of the controller 3 of the power control device 1 for charging the backup power supply 20 will be described. FIG. 5 is an explanatory diagram showing an operation example during normal charging of the backup power supply 20 of the power control device 1. FIG. 6 is an explanatory diagram showing an operation example during limited charging of the backup power supply 20 of the power control device 1.

[0053] When the remaining stored power (SOC) of the backup power supply 20 is less than the threshold value, the controller 3 conducts the inter-system switch 41 and the battery switch 42, and shuts off the bypass switch 43. Thereby, the controller 3 supplies power from the main power supply 10 to the backup power supply 20 via the DC / DC 23 to charge the backup power supply 20. Note that when no sign of power supply abnormality described later is detected, the controller 3 charges the backup power supply 20 with a constant current (no current limit or maximum limit current value) which is a predetermined current amount.

[0054] On the other hand, as shown in FIG. 6, when the controller 3 detects a sign of power supply abnormality, it charges with a limited current that limits the constant current. Specifically, the controller 3 detects a sign of power supply abnormality based on the abnormal factor information that causes the power supply abnormality. The power supply abnormality is a ground fault, overvoltage, etc. The abnormal factor information is, for example, the voltage applied to the inter-system switch 41, the weather information described later in FIG. 10, etc. The voltage applied to the inter-system switch 41 is, for example, the detected value of the first voltage sensor 51 or the second voltage sensor 52. Details of the detection method of the sign of power supply abnormality will be described later with reference to FIG. 7.

[0055] When the controller 3 detects a sign of power supply abnormality, it controls the DC / DC 23 to reduce (limit) the current output to the backup power supply 20. As a result, since the current input from the main power supply 10 to the DC / DC 23 decreases, the current flowing through the inter-system switch 41 also decreases. Consequently, even if the controller 3 detects a power supply abnormality after detecting a sign of power supply abnormality and shuts off the inter-system switch 41, the damage received by the inter-system switch 41 can be reduced because the current flowing through the inter-system switch 41 is decreased.

[0056] Next, a method for detecting a sign of power supply abnormality will be described with reference to FIG. 7. FIG. 7 is an explanatory diagram for explaining a method for detecting a sign of power supply abnormality. In FIG. 7, a time-series graph of the voltage applied to the inter-system switch 41 is shown. In FIG. 7, the first range R1 is a range sandwiched between two first threshold values TH1+ and TH1-. Also, the second range R2 is a range narrower than the first range R1 and is a range sandwiched between two second threshold values TH2+ and TH2-.

[0057] When the voltage applied to the inter-system switch 41 is outside the first range R1, the controller 3 detects a power supply abnormality. Specifically, when the voltage is equal to or higher than the first threshold value TH1+ or equal to or lower than the first threshold value TH1-, the controller 3 detects a power supply abnormality and shuts off the inter-system switch 41.

[0058] Such a power supply abnormality includes, for example, a ground fault caused by moisture adhering to the terminals of the power supply control device 1 (the main power supply 10, the backup power supply 20, and the connection terminals to the load). On the other hand, as a pre-stage of this ground fault, when the vehicle is affected by driving vibrations or the like with moisture adhering to the vicinity of the terminals, slight voltage fluctuations may repeatedly occur in the first system 110 or the second system 120. In the present disclosure, such slight voltage fluctuations are detected as signs of power supply abnormality.

[0059] Specifically, the controller 3 detects a sign of a power supply abnormality when the voltage is outside the second range R2 (and inside the first range R1). Specifically, the controller 3 detects a sign of a power supply abnormality when the voltage is equal to or higher than the second threshold TH2+ (and lower than the first threshold TH1+) or equal to or lower than the second threshold TH2- (and higher than the first threshold TH1-), and limits the charging current of the backup power supply 20.

[0060] Furthermore, it is expected that if moisture adhering near the terminals approaches the terminals due to vibrations during driving, the frequency of voltage fluctuations will increase or the duration of voltage fluctuations will become longer. Therefore, the controller 3 increases the degree of limitation on the charging current the more times the voltage falls outside the second range R2 within a certain period of time (e.g., 12 hours) or the longer the duration of the state outside the second range R2. In other words, the controller 3 determines that the greater the number of times or the longer the duration, the higher the likelihood of a power supply abnormality (the higher the likelihood of a power supply abnormality), and increases the amount of reduction in the charging current. In the example shown in FIG. 7, the controller 3 increases the degree of limitation on the charging current the longer the duration of the state outside the second range R2 is equal to or longer than the threshold time and the greater the number of times that state occurs.

[0061] Specifically, if the duration from time t1 to time t2 during which the battery voltage remains below the second threshold TH2- is equal to or longer than the threshold time, the controller 3 limits the charging current from the steady-state current to a first limited current from time t2 onwards and performs charging. The first limited current can be set to a current amount reduced from the steady-state current by a predetermined current amount or a current amount reduced from the steady-state current by a predetermined percentage.

[0062] Thereafter, if the current again falls below the second threshold TH2- at time t3 and continues to fall below the threshold time until time t4, the controller 3 limits the charging current from the first limited current to the second limited current and performs charging after time t4. The second limited current can be set to a current amount reduced by a predetermined current amount from the first limited current, or a current amount reduced by a predetermined percentage from the steady current.

[0063] That is, the controller 3 charges with the first limited current if the duration of the state of being equal to or less than the second threshold TH2- is equal to or greater than the threshold time and the number of times that state has occurred is equal to or greater than the first threshold number of times (one or more in FIG. 7).Furthermore, the controller 3 charges with the second limited current that is less than the first limited current if the duration of the state of being equal to or less than the second threshold TH2- is equal to or greater than the threshold time and the number of times that state has occurred is equal to or greater than the second threshold number of times (two or more in FIG. 7).

[0064] In this way, the controller 3 increases the limit amount of the charging current as the number of times the duration is equal to or greater than the threshold time increases, thereby gradually reducing the current flowing through the inter-system switch 41 as the possibility of a power supply abnormality increases. As a result, the controller 3 can increase the limit amount of the charging current by reducing the limit amount while the possibility of a power supply abnormality is low, and can increase the limit amount in consideration of reducing damage when the inter-system switch 41 is turned off when the possibility of a power supply abnormality increases. In other words, the controller 3 can reduce damage when the inter-system switch 41 is turned off while suppressing a decrease in charging efficiency. Note that, hereinafter, the number of times the duration is equal to or greater than the threshold time may be referred to as the "number of crossings," which means the number of times the voltage crosses the second thresholds TH2+, TH2-.

[0065] After that, at time t5, the controller 3 again enters a state below the second threshold TH2-. If it continues until time t6 when the duration is equal to or longer than the threshold time, charging is stopped after time t6. Specifically, the controller 3 stops charging the backup power supply 20 by stopping the DC / DC 23. That is, when the duration of the state below the second threshold TH2- is equal to or longer than the threshold time and the number of times of that state is equal to or more than the third threshold number (3 times or more in FIG. 7) which is more than the second threshold number, the controller 3 stops charging the backup power supply 20. At this time, the controller 3 keeps the inter-system switch 41 on, so power supply from the main power supply 10 to the second load 103 continues.

[0066] Thereby, when it is highly likely that a power supply abnormality will occur from the sign of the power supply abnormality, the controller 3 stops charging and can direct the current flowing through the inter-system switch 41 only to the power supply of the second load 103, so that the damage when the inter-system switch 41 is cut off can be minimized.

[0067] Note that after time t6, when the remaining amount of the backup power supply 20 is such that the main power supply 10 cannot be backed up, the controller 3 may charge with a third limit current that is less than the second limit current.

[0068] Specifically, charging with the third limit current means charging by intermittently flowing the second limit current. For example, the controller 3 charges the backup power supply 20 by flowing the second limit current every few seconds. That is, when charging after time t6, the controller 3 makes the amount of charge per unit time less than the amount of charge during the period from time t4 to time t6. Alternatively, as another charging method with the third limit current, instead of intermittently flowing the current, charging may be performed by continuously flowing a current more restricted than the second limit current.

[0069] In this way, when the backup power supply 20 cannot back up the main power supply 10 due to insufficient remaining amount, the controller 3 charges little by little with the third limiting current until the remaining amount that can be backed up is reached. As a result, the controller 3 can charge the backup power supply 20 up to the remaining amount that can be backed up while suppressing the damage when the inter-system switch 41 is cut off. Also, by performing charging with the third limiting current that intermittently flows the second limiting current, a period in which the charging current becomes zero can be generated, so that while charging the backup power supply 20, the damage when the inter-system switch 41 is cut off can be minimized.

[0070] In FIG. 7, the controller 3 limits the charging current in consideration of the duration and the number of times in the state of equal to or less than the second threshold TH2-. However, the charging current may be limited only by the duration or only by the number of times. That is, the controller 3 may limit to the first limiting current when the duration becomes equal to or more than the first threshold time, and limit to the second limiting current when the duration becomes equal to or more than the second threshold time that is longer than the first threshold time. Alternatively, the controller 3 may limit to the first limiting current when the number of times of becoming equal to or less than the second threshold TH2- is equal to or more than the first threshold number of times regardless of the duration, and limit to the second limiting current when the number of times is equal to or more than the second threshold number of times that is larger than the first threshold number of times.

[0071] Also, in FIG. 7, an example of performing current limiting only by the number of times in the state of equal to or less than the second threshold TH2- is shown. However, current limiting may be performed by the total number of times of the state of equal to or more than the second threshold TH2+ and the state of equal to or less than the second threshold TH2-. Also, in FIG. 7, an example of performing current limiting by the duration of equal to or less than the second threshold TH2- is shown. However, current limiting may be performed by the cumulative time of becoming equal to or less than the second threshold TH2-.

[0072] Next, with reference to FIGS. 8 and 9, the processing procedure of the processing executed by the controller 3 will be described. FIG. 8 is a flowchart showing the processing procedure of the charging process executed by the controller 3. FIG. 9 is a flowchart showing the processing procedure of the power supply abnormality detection process executed by the controller 3. The processes shown in FIGS. 8 and 9 are repeatedly executed from when the vehicle's IG (ignition switch) is turned on until it is turned off.

[0073] As shown in FIG. 8, the controller 3 first determines whether the remaining charge amount of the LiB21 is less than the threshold value (step S101).

[0074] When the remaining charge amount of the LiB21 is less than the threshold value (step S101: Yes), the controller 3 starts charging control (step S102). Specifically, the controller 3 starts charging control by operating the DC / DC 23 with the battery switch 42 turned on and the bypass switch 43 turned off. When the remaining charge amount of the LiB21 is equal to or greater than the threshold value (step S101: No), the controller 3 proceeds to step S103.

[0075] Subsequently, the controller 3 performs a power supply abnormality detection process (step S103). The power supply abnormality detection process will be described later with reference to FIG. 9.

[0076] Subsequently, the controller 3 determines whether a power supply abnormality has been detected as a result of the power supply abnormality detection process (step S104). Specifically, the controller 3 determines whether a power supply abnormality has been detected in step S203 in the power supply abnormality detection process shown in FIG. 9.

[0077] When the controller 3 detects a power supply abnormality as a result of the power supply abnormality detection process (step S104: Yes), it shuts off the inter-system switch 41 and forcibly terminates the charging of the backup power supply 20 (step S105), and ends the process.

[0078] On the other hand, in step S104, if the controller 3 does not detect a power supply abnormality as a result of the power supply abnormality detection process (step S104: No), it determines whether a sign of a power supply abnormality has been detected (step S106). Specifically, the controller 3 determines whether it has detected a sign with a degree of sign corresponding to any of steps S209, S210, S212, and S214 shown in FIG. 9.

[0079] If the controller 3 detects a sign of a power supply abnormality (step S106: Yes), it limits the current to a limit current corresponding to the degree of sign and charges the backup power supply 20 (step S107), and ends the process.

[0080] Also, if the controller 3 does not detect a sign of a power supply abnormality (step S106: No), it charges with a constant current (step S108) and ends the process.

[0081] Next, the power supply abnormality detection process will be described with reference to FIG. 9.

[0082] As shown in FIG. 9, first, the controller 3 acquires the voltage detected by the first voltage sensor 51 or the second voltage sensor 52 (step S201).

[0083] Subsequently, the controller 3 determines whether the acquired voltage has crossed the first threshold values TH1 +, TH1- (step S202). That is, the controller 3 determines whether the voltage is outside the first range R1.

[0084] If the acquired voltage of the controller 3 has crossed the first threshold values TH1 +, TH1- (step S202: Yes), that is, if the voltage is outside the first range R1, it detects a power supply abnormality (step S203) and ends the process. In this case, the controller 3 will cut off the inter-system switch 41 shown in step S105 of FIG. 8.

[0085] On the other hand, when the acquired voltage does not cross the first threshold values TH1+ and TH1- (step S202: No), that is, when the voltage is within the first range R1, the controller 3 determines whether the voltage crosses the second threshold values TH2+ and TH2- (step S204). That is, the controller 3 determines whether the voltage is outside the second range R2.

[0086] When the acquired voltage crosses the second threshold values TH2+ and TH2- (step S204: Yes), that is, when the voltage is outside the second range R2, the controller 3 determines whether the duration of the state of being outside the second range R2 is equal to or greater than the threshold value (step S205). When the acquired voltage does not cross the second threshold values TH2+ and TH2- (step S204: No), that is, when the voltage is within the second range R2, the process proceeds to step S207.

[0087] When the duration of the state of being outside the second range R2 is equal to or greater than the threshold value (step S205: Yes), the controller 3 increments the number of crossings, which is the number of times the second threshold values TH2+ and TH2- are crossed (step S206). When the duration of the state of being outside the second range R2 is less than the threshold value (step S205: No), the process proceeds to step S207.

[0088] Subsequently, the controller 3 determines whether the number of crossings within a certain time (for example, 12 hours) is equal to or greater than the third threshold number of times (step S207). When the number of crossings is equal to or greater than the third threshold number of times (step S207: Yes), the controller 3 determines whether the remaining amount of the backup power supply 20, which is the second power supply, is equal to or greater than the backup - possible remaining amount (step S208).

[0089] When the remaining amount of the backup power supply 20 is equal to or greater than the backup - possible remaining amount (step S208: Yes), the controller 3 sets the degree of sign of power - supply abnormality to "High (Stop)" (step S209) and ends the process. In this case, the controller 3 stops charging by stopping the DC / DC 23 in step S107 shown in FIG. 8.

[0090] Also, when the remaining amount of the backup power supply 20 is less than the backup - possible remaining amount (step S208: No), the controller 3 sets the degree of sign of power - supply abnormality to "High (Intermittent)" (step S210) and ends the process. In this case, the controller 3 charges at the third limit current, that is, charges intermittently at the second limit current, in step S107 shown in FIG. 8.

[0091] Also, in step S207, when the number of crossovers is less than the third threshold number of times (step S207: No), the controller 3 determines whether it is equal to or greater than the second threshold number of times (step S211). When the number of crossovers is equal to or greater than the second threshold number of times (step S211: Yes), the controller 3 sets the degree of sign of power - supply abnormality to "Medium" (step S212) and ends the process. In this case, the controller 3 charges at the second limit current in step S107 shown in FIG. 8.

[0092] Also, when the number of crossovers is less than the second threshold number of times (step S211: No), the controller 3 determines whether it is equal to or greater than the first threshold number of times (step S213). When the number of crossovers is equal to or greater than the first threshold number of times (step S213: Yes), the controller 3 sets the degree of sign of power - supply abnormality to "Low" (step S214) and ends the process. In this case, the controller 3 charges at the first limit current in step S107 shown in FIG. 8.

[0093] If the number of crossings is less than the first threshold number of times (step S213: No), the controller 3 determines that there is no sign of a power supply abnormality (step S215) and ends the process. In this case, the controller 3 performs charging with a steady current in step S108 shown in FIG.

[0094] In the above-described embodiment, the controller 3 limits the charging current using the voltage applied to the inter-system switch 41 as abnormality factor information, but weather information may be used as abnormality factor information. This point will be described with reference to FIG. 10.

[0095] 10 is an explanatory diagram of the configuration and operation of a power supply control device 1 according to another example of the embodiment. As shown in FIG.

[0096] The external device 100 is a device that acquires weather information that serves as abnormality factor information. The external device 100 may be, for example, a camera, a hygrometer, or a server device that distributes weather information.

[0097] When the power supply control device 1 receives weather information indicating rain from the external device 100, it detects the rain in the weather information as a sign of a power supply abnormality and limits the charging current of the backup power supply 20 to the first limited current described above. Note that the weather information detected as a sign of a power supply abnormality may be any weather information other than rain that is likely to cause moisture to adhere to the surroundings of the power supply control device 1, such as snow or high humidity.

[0098] As explained in the above embodiment, this is because moisture adhering to the vicinity of the terminals can be caused by weather such as rain, snow, or a high humidity environment. Therefore, when the weather is such that there is a high possibility of moisture being produced, the controller 3 detects the weather as a sign of a power supply abnormality. This allows for earlier detection of signs of a power supply abnormality.

[0099] The reason for limiting the charging current to the first limit current is that the signs of a power supply abnormality based on weather information simply indicate conditions where moisture is likely to adhere, and do not indicate that moisture that could lead to a power supply abnormality is actually adhering near the terminals. In other words, the power supply control device 1 does not excessively limit the charging current because moisture that could cause a power supply abnormality is not adhering. This makes it possible to minimize the decrease in charging efficiency while preparing for the shutoff of the inter-system switch 41 due to a power supply abnormality.

[0100] As described above, the power supply control device 1 according to the embodiment includes an inter-system switch 41 and a controller 3. The inter-system switch 41 is provided so as to be connectable to a first system 110 that supplies power from a first power source (main power source 10) to a first load (first load 101, general load 102) and a second system 120 that supplies power from a second power source (backup power source 20) to a second load (second load 103). When the remaining charge of the second power source falls below a threshold, the controller 3 supplies current from the first power source to the second power source via the inter-system switch 41 to charge the second power source, and if a power supply abnormality is detected during charging, the controller 3 shuts off the inter-system switch 41. When the controller 3 detects a sign of a power supply abnormality based on abnormality cause information that may cause the power supply abnormality, the controller 3 limits the current supplied to the second power source.

[0101] This allows the current flowing through the inter-system switch 41 to be reduced by limiting the charging current when a sign of a power supply abnormality is detected, thereby reducing damage when the inter-system switch 41 is shut off due to a power supply abnormality.

[0102] 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]

[0103] 1 Power supply control device 3 Controller 10 Main power supply 11, 23 DC / DC 20 Backup power supply 22 Condition Monitoring Line 41 Intersystem switch 42 Battery switch 43 Bypass switch 51 First voltage sensor 52 Second voltage sensor 100 External device 101 1st load 102 General load 103 2nd load 110 1st system 120 2nd system 130 Intersystem Line R1 First range R2 Second range

Claims

1. An inter-system switch provided so as to be connectable between a first system that supplies power from a first power source to a first load and a second system that supplies power from a second power source to a second load, a controller that, when the remaining amount of the second power source becomes less than a threshold value, supplies a current from the first power source to the second power source via the inter-system switch to perform charging, and shuts off the inter-system switch when a power source abnormality is detected during charging, comprising: the controller limits the current supplied to the second power source when detecting a sign of the power source abnormality based on abnormality factor information that is a factor causing the power source abnormality a power source control device.

2. the abnormality factor information is a voltage applied to the inter-system switch, the controller detects the power source abnormality when the voltage is outside a first range, and detects a sign of the power source abnormality when the voltage is outside a second range that is narrower than the first range The power source control device according to claim 1.

3. the controller strengthens the degree of current limitation as the number of times the voltage is outside the second range increases, or as the duration of the state outside the second range continues to increase The power source control device according to claim 2.

4. the controller charges with a first limited current when the duration is equal to or greater than a threshold time and the number of times is equal to or greater than a first threshold number of times, and charges with a second limited current less than the first limited current when the duration is equal to or greater than a threshold time and the number of times is equal to or greater than a second threshold number of times that is greater than the first threshold number of times The power source control device according to claim 3.

5. the controller stops charging the second power source when the duration is equal to or greater than a threshold time and the number of times is equal to or greater than a third threshold number of times that is greater than the second threshold number of times The power source control device according to claim 4.

6. the controller charges with a third limited current less than the second limited current when the duration is equal to or greater than a threshold time and the number of times is equal to or greater than a third threshold number of times, and when the remaining amount of the second power source is an amount that cannot be backed up by the first power source The power source control device according to claim 5.

7. charging with the third limited current is to intermittently supply the second limited current for charging The power source control device according to claim 6.

8. the abnormality factor information further includes weather information, the controller When detecting a sign of the power supply abnormality based on the weather information, charge the second power supply while limiting the current to the first limiting current The power supply control device according to claim 4

9. A power supply control program for causing a power supply control device having an inter-system switch provided so as to be connectable between a first system that supplies power from a first power supply to a first load and a second system that supplies power from a second power supply to a second load, wherein When the remaining amount of the second power supply becomes less than a threshold value, supply a current from the first power supply to the second power supply via the inter-system switch to perform charging, and when a power supply abnormality is detected during charging, cut off the inter-system switch When detecting a sign of the power supply abnormality based on the abnormal factor information that is a factor causing the power supply abnormality, limit the current supplied to the second power supply Power supply control program

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