Power supply controller and power supply control system

Abstract

To provide a power supply controller and a power supply control system, capable of securing power enough for completing evacuation travel even when a failure of a first power supply is caused during equalization of an SOC of a second power supply.SOLUTION: A power supply controller comprises a controller. The controller is mounted on a vehicle comprising: a first power supply; and a second power supply including redundant cells and cells each having capacity capable of supplying power to a load during a backup time previously assumed in the case of a failure of the first power supply. The controller performs power supply control to the load and cell voltage equalization of the second power supply. Upon determining that the cell voltage equalization is necessary, the controller performs the cell voltage equalization by making cells whose cell voltage is higher than that of a cell having the lowest cell voltage of the cells included in the second power supply discharge toward a target voltage and, at the same time, causes the residual cells to supply the power to the load.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Electric vehicles, hybrid vehicles, and plug-in hybrid vehicles are equipped with batteries in which multiple cells are connected in series. Repeated charging and discharging of the battery causes differences in the SOC (State Of Charge) of each cell, resulting in cell imbalance.

[0003] In this case, if the cell with the lowest SOC at the start of charging is fully charged, the cell with the highest SOC at the start of charging will be overcharged. For this reason, the power supply control device will stop charging when the cell with the highest SOC is fully charged during charging.

[0004] This allows the power supply control device to prevent overcharging of the cells, but it cannot fully charge the cells that had a low SOC at the start of charging, which reduces the amount of stored power. For this reason, batteries with unbalanced cells need to have their SOCs equalized.

[0005] As a method for increasing the opportunities for equalizing the SOC, for example, a method is known in which the SOC is equalized while power is supplied from the battery to the load while the vehicle is running (see, for example, Patent Documents 1 and 2).

[0006] On the other hand, when the power supply control device is installed in a vehicle having a first power supply and a second power supply, the power supply is made redundant, so the SOC of the second power supply can be equalized while the vehicle is running by supplying power from the first power supply to the load.

[0007] The power supply control device equalizes the SOC of each cell by, for example, discharging a cell of the second power supply that has a higher SOC than the other cells. If a failure occurs in the first power supply while equalizing the SOC of the second power supplies, the power supply control device supplies power from the second power supply, which is a backup power supply, to the load, allowing the vehicle to evacuate. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-041513 [Patent Document 2] Patent Publication No. 2021-023011 Summary of the Invention [Problem to be solved by the invention]

[0009] However, if a failure occurs in the first power source while the power source control device is equalizing the SOC of the second power source, the SOC of the second power source will have decreased due to the equalization, and the power source control device may not be able to secure enough power to complete the evacuation driving.

[0010] One aspect of the embodiment has been made in consideration of the above, and aims to provide a power supply control device and a power supply control system that can secure enough power to complete evacuation driving even if a failure occurs in the first power supply while equalizing the SOC of the second power supply. [Means for solving the problem]

[0011] A power supply control device according to one aspect of the embodiment includes a controller. The controller is mounted on a vehicle equipped with a first power supply and a second power supply including cells and redundant cells having a capacity sufficient to supply power to a load for a predetermined backup time in the event of a failure of the first power supply. The controller controls power supply to the load and equalizes cell voltages of the second power supply. When the controller determines that cell voltage equalization is necessary, it discharges cells included in the second power supply that have a higher cell voltage than a cell with the lowest cell voltage toward a target voltage to equalize the cell voltages, while supplying power to the load from the remaining cells. [Effects of the Invention]

[0012] In one aspect of the embodiment, even if a failure occurs in the first power source while equalizing the SOC of the second power source, the second power source has redundant cells, so that the remaining cells excluding the cell being equalized can ensure enough power to complete the evacuation driving. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of the configuration of a power supply control device according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating the operation of the power supply control device according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating the operation of the power supply control device according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of processing executed by the controller of the power supply control device according to the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating the operation of the power supply control device according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating the operation of the power supply control device according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating the operation of the power supply control device according to the second embodiment. [Figure 8]FIG. 8 is a flowchart showing an example of processing executed by the controller of the power supply control device according to the second embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of processing executed by the controller of the power supply control device according to the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating the operation of the power supply control device according to the third embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of processing executed by the controller 4 of the power supply control device according to the third embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of processing executed by the controller 4 of the power supply control device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply control device and a power supply control system according to an embodiment will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0015] [1. First embodiment] [1-1. Configuration of the power supply control device according to the first embodiment] 1 is an explanatory diagram showing an example of the configuration of a power supply control device 1 according to the first embodiment. The power supply control device 1 according to the embodiment is installed in an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle equipped with an autonomous driving function.

[0016] 1, the power supply control device 1 is connected to a first power supply 10 via a DC-DC converter (hereinafter referred to as "DCDC") 11. The power supply control device 1 is also connected to an automatic driving control device 12, a second power supply 20, a first load 101, a second load 102, and a third load 103.

[0017] The first power supply 10 is, for example, a lead battery. However, the first power supply 10 may be, for example, another secondary battery such as a lithium ion battery. The DCDC 11 is a device that boosts or lowers the voltage of the first power supply 10 to a predetermined voltage and outputs it to the power supply control device 1.

[0018] Although not shown here, the first power source 10 is connected to a high-voltage battery. The high-voltage battery is a secondary battery that supplies power to a motor that drives the vehicle. The first power source 10 is charged with power supplied from the high-voltage battery. In this case, the first power source 10 is charged with power from the high-voltage battery that has been stepped down by a DC / DC converter (not shown).

[0019] Furthermore, if the vehicle in which first power supply 10 is installed is a hybrid vehicle or a plug-in hybrid vehicle, first power supply 10 is connected to an alternator. In this case, first power supply 10 is also charged by power input from the alternator.

[0020] The first load 101, the second load 102, and the third load 103 are, for example, an engine control device, a steering control device, a brake control device, an audio device, a video display device, various sensors, etc. The automatic driving control device 12 is a device that controls, for example, the engine control device, the steering control device, the brake control device, etc. to cause the vehicle to automatically drive.

[0021] The second power source 20 is, for example, a lithium ion battery. However, the second power source 20 may be any secondary battery other than a lithium ion battery. The second power source 20 is configured by connecting a plurality of battery cells (hereinafter referred to as "cells") in series.

[0022] For example, when the voltage of the first power supply 10 becomes lower than the voltage of the second power supply 20, the second power supply 20 supplies power to the first load 101, the second load 102, the third load 103, etc. in place of the first power supply 10. In addition, the second power supply 20 is a backup power supply that supplies power to the first load 101, the second load 102, the third load 103, etc. in place of the first power supply 10 in the event of a failure of the first power supply 10.

[0023] In this case, the automatic driving control device 12 controls the first load 101, the second load 102, the third load 103, etc., which are powered by the second power source 20, to cause the vehicle to evacuate and stop in a safe place.

[0024] For this reason, a typical backup second power source is provided with a number of cells that can supply power to the first load 101, the second load 102, the third load 103, etc. for the backup time required for a pre-estimated evacuation run in the event of a failure of the first power source 10.

[0025] Here, as an example, we will explain that a typical second power source has three cells connected in series, and if the SOC (State Of Charge) of each cell is 75% or higher, it can supply power to the load for the backup time required for the pre-estimated evacuation driving.

[0026] In contrast to the general second power supplies described above, the second power supply 20 according to this embodiment includes four cells 21, 22, 23, and 24. That is, the second power supply 20 includes one redundant cell in addition to three cells that can supply power to the load during the backup time required for a pre-estimated evacuation run when the first power supply 10 fails.

[0027] When equalization of the cell voltages is required, the power supply control device 1 is configured to discharge cells included in the second power supply 20 having a cell voltage higher than the cell with the lowest cell voltage toward a target voltage to equalize the cell voltages, while supplying power to the load from the remaining cells.

[0028] As a result, even if a failure occurs in the first power source 10 while the power source control device 1 is equalizing the SOC of the second power source 20, the second power source 20 has redundant cells, so the power source control device 1 can ensure enough power to complete the evacuation driving using the remaining cells excluding the cells being equalized.

[0029] The power supply control device 1 includes a power supply circuit 2, a balancing circuit 3, and a controller 4. The power supply circuit 2 includes a voltage sensor 70 and a plurality of switches (hereinafter referred to as "SWs"). In the example shown in Fig. 1, the power supply circuit 2 includes a first power supply SW41, a second power supply SW42, a first load SW43, a second load SW44, and a third load SW45.

[0030] The voltage sensor 70 detects the voltage of the common power supply line L1 connecting the first power supply SW 41, the second power supply SW 42, the first load SW 43, the second load SW 44, and the third load SW 45, and outputs the detection result to the controller 4.

[0031] The first power supply SW41 connects the DCDC11 and the power supply control device 1 when turned on, and disconnects the DCDC11 and the power supply control device 1 when turned off. The second power supply SW42 connects the second power supply 20 and the power supply control device 1 when turned on, and disconnects the second power supply 20 and the power supply control device 1 when turned off.

[0032] The first load SW43 connects the first load 101 to the power supply control device 1 when turned on, and disconnects the first load 101 from the power supply control device 1 when turned off. The second load SW44 connects the second load 102 to the power supply control device 1 when turned on, and disconnects the second load 102 from the power supply control device 1 when turned off.

[0033] When the third load SW45 is turned on, it connects the third load 103 to the power supply control device 1, and when it is turned off, it cuts off the connection between the third load 103 and the power supply control device 1. The first power supply SW41, the second power supply SW42, the first load SW43, the second load SW44, and the third load SW45 are controlled by the controller 4 to be switched on and off.

[0034] The balancing circuit 3 is a circuit for equalizing the voltages of the first cell 21, the second cell 22, the third cell 23, and the fourth cell 24 (hereinafter referred to as "cell voltages") when variations occur in the voltages.

[0035] The balancing circuit 3 includes a first equalization SW 51, a second equalization SW 52, a third equalization SW 53, and a fourth equalization SW 54. When the first equalization SW 51 is turned on, it forms a closed circuit that connects in series the positive electrode of the first cell 21, the first equalization SW 51, the first resistor 61, and the negative electrode of the first cell 21. When the first equalization SW 51 is turned off, it interrupts the closed circuit.

[0036] When the second equalization SW 52 is turned on, it forms a closed circuit that connects in series the positive electrode of the second cell 22, the second equalization SW 52, the second resistor 62, and the negative electrode of the second cell 22. When the second equalization SW 52 is turned off, it breaks the closed circuit.

[0037] When the third equalization SW 53 is turned on, it forms a closed circuit that connects in series the positive electrode of the third cell 23, the third equalization SW 53, the third resistor 63, and the negative electrode of the third cell 23. When the third equalization SW 53 is turned off, it breaks the closed circuit.

[0038] When the fourth equalization SW 54 is turned on, it forms a closed circuit that connects in series the positive electrode of the fourth cell 24, the fourth equalization SW 54, the fourth resistor 64, and the negative electrode of the fourth cell 24. When the fourth equalization SW 54 is turned off, it breaks the closed circuit.

[0039] The first equalization SW 51, the second equalization SW 52, the third equalization SW 53, and the fourth equalization SW 54 are controlled by the controller 4 to be switched on and off.

[0040] Furthermore, the balancing circuit 3 includes a first voltage sensor 71, a second voltage sensor 72, a third voltage sensor 73, and a fourth voltage sensor 74. The first voltage sensor 71 detects the cell voltage of the first cell 21 and outputs it to the controller 4.

[0041] The second voltage sensor 72 detects the cell voltage of the second cell 22 and outputs it to the controller 4. The third voltage sensor 73 detects the cell voltage of the third cell 23 and outputs it to the controller 4. The fourth voltage sensor 74 detects the cell voltage of the fourth cell 24 and outputs it to the controller 4.

[0042] The controller 4 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various other circuits. The controller 4 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 working area.

[0043] For example, the controller 4 executes a power supply control program to control each switch of the power supply circuit 2 and control the power supply from at least one of the first power source 10 and the second power source 20 to the first load 101, the second load 102, and the third load 103.

[0044] Furthermore, the controller 4 executes a power supply control program to control the first equalization SW 51, the second equalization SW 52, the third equalization SW 53, and the fourth equalization SW 54, thereby equalizing the cell voltages.

[0045] The power supply control program may be stored in a storage device from the outside via a communication line, etc. Also, the controller 4 may be configured partially or entirely with hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0046] [1-2. Operation of the power supply control device according to the first embodiment] Next, the operation of the power supply control device 1 according to the embodiment will be described with reference to Figures 2 and 3. Figures 2 and 3 are explanatory diagrams of the operation of the power supply control device 1 according to the embodiment.

[0047] When the vehicle ignition switch (hereinafter referred to as "IG") is turned on, the controller 4 turns on the first power feed SW 41, the second power feed SW 42, the first load SW 43, the second load SW 44, and the third load SW 45, as shown in FIG.

[0048] At this time, the controller 4 keeps the first equalization SW 51, the second equalization SW 52, the third equalization SW 53, and the fourth equalization SW 54 in the off state. As a result, the output voltage of the second power source 20 becomes a voltage equivalent to four cells. In this way, the power supply control device 1 controls the power supply from at least one of the first power source 10 and the second power source 20 to the first load 101, the second load 102, and the third load 103.

[0049] At this time, if the output voltage of the DCDC 11 is higher than the output voltage of the second power supply 20, power is supplied from the first power supply 10 to the first load 101, the second load 102, and the third load 103. Furthermore, power is supplied from the first power supply 10 to the second power supply 20, and the second power supply 20 is charged. Furthermore, if the output voltage of the DCDC 11 is lower than the output voltage of the second power supply 20, power is supplied from the second power supply 20 to the first load 101, the second load 102, and the third load 103.

[0050] If the controller 4 determines that the cell voltages need to be equalized, it equalizes the cell voltages. Specifically, the controller 4 acquires the cell voltages from the first voltage sensor 71, the second voltage sensor 72, the third voltage sensor 73, and the fourth voltage sensor 74.

[0051] Then, when the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage is equal to or greater than a predetermined threshold, the controller 4 determines that cell voltage equalization is necessary. For example, when the controller 4 determines that cell voltage equalization is necessary and the cell voltage of the third cell 23 is the highest and the cell voltage of the fourth cell 24 is the lowest, the controller 4 turns on the third equalization SW 53 (see FIG. 3).

[0052] This forms a closed circuit connecting the positive electrode of the third cell 23, the third equalization SW 53, the third resistor 63, and the negative electrode of the third cell 23 in series, causing the third cell 23 to discharge. The target discharge voltage is the cell voltage of the fourth cell 24, which has the lowest cell voltage. When the cell voltage of the third cell 23 drops to the target discharge voltage, the controller 4 turns off the third equalization SW 53, thereby terminating the discharge of the third cell 23. As a result, the cell voltage of the third cell 23 drops, and the cell voltage of the third cell 23 becomes equal to the cell voltage of the fourth cell 24, thereby equalizing the cell voltages.

[0053] In addition, when there are multiple cells that need to be equalized, i.e., when there are multiple cells that have cell voltages that are higher than the cell voltage of the cell with the lowest cell voltage by a predetermined threshold or more, the controller 4 may discharge the cells to be discharged sequentially to the discharge target voltage, or may discharge them simultaneously to the discharge target voltage.

[0054] At this time, if a failure occurs in the first power source 10, the automatic driving control device 12 uses the power of the second power source 20 to drive the vehicle to safety, but the power source control device 1 can supply power from the first cell 21, the second cell 22, and the fourth cell 24, although the third cell 23 is discharged for equalization.

[0055] In other words, even if the first power source 10 fails during equalization, the power supply control device 1 can use the three cells capable of supplying power to the first to third loads 101, 102, and 103 for the backup time required for evacuation driving, thereby ensuring sufficient power to complete evacuation driving.

[0056] Furthermore, if a failure occurs in the first power source 10 while the controller 4 is equalizing the cell voltages of the second power source 20, the controller 4 may be configured to stop equalizing the cell voltages and supply power to the load from all the cells included in the second power source 20.

[0057] As a result, even if the SOC of the first cell 21, the second cell 22, and the fourth cell 24, excluding the third cell 23 that is discharging for equalization, is less than 75% of the level required to complete the evacuation driving, the power supply control device 1 can more reliably complete the evacuation driving by further using the third cell 23 for power supply.

[0058] When the controller 4 determines that the second power source 20 needs to be charged, it supplies power from the first power source 10 to the second power source 20 to charge the second power source 20. For example, when the average value of the cell voltages of the second power source 20 falls below a predetermined charge threshold, the controller 4 determines that the second power source 20 needs to be charged. The charge threshold here is, for example, the cell voltage value when the SOC of the cell is 75%.

[0059] [1-3. Processing Executed by the Controller According to the First Embodiment] Next, processing executed by the controller 4 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of processing executed by the controller 4 of the power supply control device 1 according to the first embodiment.

[0060] When the IG is turned on, the controller 4 turns on the first power supply SW 41, the second power supply SW 42, the first load SW 43, the second load SW 44, and the third load SW 45 (step S101), as shown in Fig. 4. Furthermore, the controller 4 turns off the first equalization SW 51, the second equalization SW 52, the third equalization SW 53, and the fourth equalization SW 54 (step S102).

[0061] Next, the controller 4 determines whether or not cell voltage equalization is in progress (step S103). If cell voltage equalization is not being performed (step S103, No), the controller 4 determines whether or not cell voltage equalization is necessary (step S104). If cell voltage equalization is in progress (step S103, Yes), the controller 4 proceeds to step S107.

[0062] In step S104, the controller 4 determines that cell voltage equalization is necessary when the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage (hereinafter referred to as the maximum-minimum voltage difference) is equal to or greater than a predetermined threshold.

[0063] Specifically, the controller 4 detects the cell voltage of each cell, and sets an equalization flag (sets it to 1) when the maximum / minimum voltage difference is equal to or greater than a predetermined threshold. If the equalization flag is set in step S104, the controller 4 determines that cell voltage equalization is necessary. If the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage is less than a predetermined threshold, specifically if the equalization flag is not set (0), the controller 4 determines that cell voltage equalization is not necessary.

[0064] If the controller 4 determines that cell voltage equalization is not necessary (step S104, No), the process proceeds to step S109. If the controller 4 determines that cell voltage equalization is necessary (step S104, Yes), the controller 4 calculates a discharge target voltage for the cell to be discharged (step S105).

[0065] Here, the cell with the highest cell voltage is set as the discharge target cell, and the cell voltage of the cell with the lowest cell voltage is set as the discharge target voltage.Then, the controller 4 turns on the equalization SW of the discharge target cell (step S106).

[0066] For example, when the third cell 23 is the cell to be discharged, the controller 4 turns on the third equalization SW 53. As a result, the third cell 23, which is the cell to be discharged, is connected in series with the third equalization SW 53 and the third resistor 63 and discharges, and the cell voltage decreases toward the discharge target voltage.

[0067] Thereafter, the controller 4 determines whether the cell voltage of the cell to be discharged has reached the discharge target voltage (step S107). The controller 4 determines whether the discharge target voltage has been reached based on the cell voltage obtained from a voltage sensor that detects the voltage of the cell to be discharged. For example, when the cell to be discharged is the third cell 23, the controller 4 determines whether the discharge target voltage has been reached based on the cell voltage obtained from the third voltage sensor 73.

[0068] If the controller 4 determines that the cell voltage of the discharge target cell has not reached the discharge target voltage (step S107, No), it proceeds to step S109. If the controller 4 determines that the cell voltage of the discharge target cell has reached the discharge target voltage (step S107, Yes), it turns off the equalization switch corresponding to the discharge target cell and sets the equalization flag to 0 (step S108). This ends the equalization.

[0069] For example, when the discharge target cell is the third cell 23, the controller 4 turns off the third equalization SW 53. This stops the equalization of the cell voltages. Thereafter, the controller 4 determines whether or not a ground fault (fault) has occurred (step S109).

[0070] If the controller 4 determines that no ground fault has occurred (step S109, No), it moves the process to step S103. Therefore, once the controller 4 determines that equalization is necessary in step S104 and starts discharging the discharge target cell in step S106, the controller 4 repeats step S103, Yes, and then step S107, thereby equalizing the cell voltages, unless a ground fault has occurred.

[0071] Furthermore, when the controller 4 determines that a ground fault has occurred (Yes in step S109), if the second power source 20 is currently being charged, the controller 4 stops the charging (step S110). At this time, if the second power source 20 is not currently being charged, the controller 4 skips the process of step S110 and moves the process to step S111.

[0072] In step S111, if the cell voltages are being equalized, i.e., if the equalization flag is set, the controller 4 turns off the equalization SW of the cell to be discharged and proceeds to step S112. For example, if the cell to be discharged is the third cell 23, the controller 4 turns off the third equalization SW 53 to stop equalizing the cell voltages. At this time, the controller 4 sets the equalization flag to 0.

[0073] If the cell voltages are not being equalized in step S111, the controller 4 does not execute the process of step S111 and identifies the location of the ground fault (step S112). Specifically, the controller 4 sequentially turns off the first power feed SW 41, the second power feed SW 42, the first load SW 43, the second load SW 44, and the third load SW 45, and identifies the location of the ground fault from the voltage of the common power feed line L1 acquired from the voltage sensor 70 at that time.

[0074] At this time, if the voltage of the common power feed line L1 when only the first power feed SW41 is turned off recovers to or exceeds the ground fault threshold, the controller 4 identifies a location on the first power supply 10 side of the first power feed SW41 as the ground fault location. Also, if the voltage of the common power feed line L1 when only the second power feed SW42 is turned off recovers to or exceeds the ground fault threshold, the controller 4 identifies a location on the second power supply 20 side of the second power feed SW42 as the ground fault location.

[0075] Furthermore, if the voltage of the common power feed line L1 when only the first load SW43 is turned off recovers to or exceeds the ground fault threshold, the controller 4 identifies a location on the first load 101 side of the first load SW43 as the ground fault location. Furthermore, if the voltage of the common power feed line L1 when only the second load SW44 is turned off recovers to or exceeds the ground fault threshold, the controller 4 identifies a location on the second load 102 side of the second load SW44 as the ground fault location.

[0076] Furthermore, if the voltage of the common power feed line L1 recovers to or exceeds the ground fault threshold when only the third load SW45 is turned off, the controller 4 identifies a location on the third load 103 side of the third load SW45 as the ground fault location. Furthermore, the controller 4 sequentially turns off the first power feed SW41, the second power feed SW42, the first load SW43, the second load SW44, and the third load SW45, and if the voltages of the common power feed line L1 are all equal to or exceed the normal threshold, it determines that no ground fault has occurred.

[0077] In this way, the controller 4 sequentially turns off the first power supply SW41, the second power supply SW42, the first load SW43, the second load SW44, and the third load SW45, and determines whether the voltage of the common power supply line L1 recovers, thereby identifying the location of the ground fault.

[0078] Thereafter, the controller 4 performs fail-safe control (step S113) and ends the process. Specifically, the controller 4 disconnects the ground-fault location from the power supply circuit 2 by turning off the SW closest to the ground-fault location among the first power supply SW 41, the second power supply SW 42, the first load SW 43, the second load SW 44, and the third load SW 45, and performs fail-safe control by supplying power to the normal load from the normal first power supply 10 or the second power supply 20, and ends the process.

[0079] [2. Second Embodiment] [2-1. Configuration and Operation of the Power Supply Control Device According to the Second Embodiment] Next, the operation of the power supply control device 1A according to the second embodiment will be described with reference to Figures 5 to 7. Figures 5 to 7 are explanatory diagrams of the operation of the power supply control device 1A according to the second embodiment. The power supply control device 1A according to the second embodiment differs from the power supply control device 1 according to the first embodiment in that it has a parallel circuit of DCDC13 and SW14 instead of the second power feed SW42 shown in Figure 1 and the like, and in the configuration of the balancing circuit 3A.

[0080] 5 to 7 selectively illustrate parts of the configuration of the power supply control device 1A that are different from the configuration of the power supply control device 1. Furthermore, here, among the configuration of the balancing circuit 3A according to the second embodiment, components that perform the same functions as the configuration of the balancing circuit 3 according to the first embodiment are assigned the same reference numerals as in the first embodiment, and redundant explanations will be omitted.

[0081] 5, the balancing circuit 3A according to the second embodiment includes a switching circuit 3B in addition to the components included in the balancing circuit 3 according to the first embodiment. The switching circuit 3B is a circuit that can switch between a first state in which the cells of the second power supply 20 are connected in series to supply power to a load, and a second state in which one cell included in the second power supply 20 is disconnected from the other cells and the other cells are connected in series to supply power to the load.

[0082] Specifically, the switching circuit 3B includes a first BP (bypass) SW 81, a second BP SW 82, a third BP SW 83, and a fourth BP SW 84. Furthermore, the switching circuit 3B includes a first SP (separation) SW 91, a second SP SW 92, a third SP SW 93, a fourth SP SW 94, a fifth SP SW 95, a sixth SP SW 96, and a seventh SP SW 97.

[0083] The first SPSW 91 has one end connected to the positive electrode of the first cell 21 and the other end connected to one end of the second SPSW 92. The other end of the second SPSW 92 is connected to the negative electrode of the second cell 22. The third SPSW 93 has one end connected to the positive electrode of the second cell 22 and the other end connected to one end of the fourth SPSW 94. The other end of the fourth SPSW 94 is connected to the negative electrode of the third cell 23.

[0084] One end of the fifth SPSW 95 is connected to the positive electrode of the third cell 23, and the other end is connected to one end of the sixth SPSW 96. The other end of the sixth SPSW 96 is connected to the negative electrode of the fourth cell 24. One end of the seventh SPSW 97 is connected to the positive electrode of the fourth cell 24, and the other end is connected to the DC / DC converter 13.

[0085] The first BPSW 81, the second BPSW 82, the third BPSW 83, and the fourth BPSW 84 are on / off controlled by the controller 4. The first SPSW 91, the second SPSW 92, the third SPSW 93, the fourth SPSW 94, the fifth SPSW 95, the sixth SPSW 96, and the seventh SPSW 97 are on / off controlled by the controller 4. The controller 4 according to the second embodiment also controls the operation of the DCDC 13 and SW14.

[0086] When the controller 4 determines that cell voltage equalization is not necessary, it turns off all of the first BPSW 81, second BPSW 82, third BPSW 83, and fourth BPSW 84, as shown in Fig. 5. Then, the controller 4 turns on all of the first SPSW 91, second SPSW 92, third SPSW 93, fourth SPSW 94, fifth SPSW 95, sixth SPSW 96, and seventh SPSW 97.

[0087] The controller 4 determines whether or not cell voltage equalization is necessary using the same method as in the first embodiment. If charging of the second power supply 20 is not necessary, the controller 4 deactivates the DCDC 13 and turns on SW14. In this way, when the controller 4 determines that cell voltage equalization is not necessary and that charging of the second power supply 20 is not necessary, it connects all of the cells of the second power supply 20 in series, sets the switching circuit 3B to the first state, and enables power supply from all of the cells via SW14.

[0088] In this state, when the controller 4 determines that the voltage of the second power supply 20 has dropped and that charging of the second power supply 20 is necessary, it turns off SW14, activates DCDC 13, and boosts the voltage of the first power supply 10 with the DCDC 13 to charge the second power supply 20. The controller 4 determines whether charging of the second power supply 20 is necessary using the same method as in the first embodiment.

[0089] Furthermore, when the controller 4 determines that cell voltage equalization is necessary, it switches the state of the switching circuit 3B from the first state to the second state, thereby discharging one cell and equalizing the cell voltages. The controller 4 determines which cell needs to be discharged for equalization in the same manner as in the first embodiment.

[0090] For example, when the cell to be discharged is the third cell 23, the controller 4 turns off the first BPSW 81, the second BPSW 82, and the fourth BPSW 84 and turns on the third BPSW 83, as shown in Fig. 6. Then, the controller 4 turns on the first SPSW 91, the second SPSW 92, the third SPSW 93, the sixth SPSW 96, and the seventh SPSW 97, and turns off the fourth SPSW 94 and the fifth SPSW 95.

[0091] In this way, the controller 4 disconnects the third cell 23, which is the cell to be discharged, from the power supply path and forms a closed circuit that connects the positive electrode of the third cell 23, the third equalization SW 53, the third resistor 63, and the negative electrode of the third cell 23.

[0092] As a result, the controller 4 can equalize the cell voltages by discharging the cells to be discharged, while bringing the remaining cells, which have the capacity to complete the evacuation traveling, into a state where they can supply power.

[0093] In the example shown in FIG. 6, the controller 4 can make the first cell 21, the second cell 22, and the fourth cell 24 available for power supply while continuing to equalize the cell voltages by disconnecting the third cell 23 from the power supply path and discharging it.

[0094] At this time, if the voltage of the first power source 10 is lower than the voltage of the second power source 20, power is supplied from the second power source 20 to the first load 101, the second load 102, and the third load 103, which further reduces the cell voltage of the cell having the lowest cell voltage. Therefore, it is desirable for the controller 4 to also reduce the discharge target voltage of the cell to be discharged in accordance with the reduction in the lowest cell voltage.

[0095] Furthermore, if the controller 4 determines that charging of the second power source 20 is necessary while equalizing the cell voltages of the second power source 20, it keeps the state of the switching circuit 3B in the second state and supplies power from the first power source 10 to the second power source 20 to charge the second power source 20. The controller 4 determines whether charging of the second power source 20 is necessary using the same method as in the first embodiment.

[0096] For example, when the cell to be discharged is the third cell 23, the controller 4 turns off SW14 as shown in FIG. 7, boosts the voltage supplied from the first power supply 10 to a predetermined charging voltage using the DCDC13, and supplies it to the second power supply 20, thereby charging the second power supply 20.

[0097] At this time, the third cell 23, which is the cell to be discharged, is disconnected from the charge path because the fourth SPSW 94 and the fifth SPSW 95 are off. Then, because the third equalization SW 53 is on, the third cell 23 is discharged by passing a current through a closed circuit that connects the positive electrode of the third cell 23, the third equalization SW 53, the third resistor 63, and the negative electrode of the third cell 23, and the cell voltages are equalized.

[0098] Meanwhile, the first cell 21, the second cell 22, and the fourth cell 24 are connected in series and are in a chargeable state because the first to third SPSWs 91 to 93, the sixth to seventh SPSWs 96 to 97, and the third BPSW 83 are on.

[0099] In this way, when it is necessary to charge the second power source 20 during cell voltage equalization, the controller 4 can equalize the cell voltages by discharging the cells to be discharged, while charging the remaining cells.

[0100] In this case, the cell with the lowest cell voltage is charged, which increases the lowest cell voltage. The controller 4 also increases the discharge target voltage of the cell to be discharged in accordance with the increase in the lowest cell voltage. This allows the voltage of the cell to be discharged to reach the discharge target voltage more quickly, thereby shortening the equalization time.

[0101] In the example shown in FIG. 7, the controller 4 can charge the first cell 21, the second cell 22, and the fourth cell 24 while continuing to equalize the cell voltages by disconnecting the third cell 23 from the charging path and discharging it.

[0102] In the above description, the controller 4 has been described as determining that charging of the second power supply 20 is necessary when equalizing the cell voltages. As a modification, the controller 4 may forcibly charge the second power supply 20 when equalizing the cell voltages. Specifically, when the controller 4 determines that equalization of the cell voltages is necessary, the controller 4 switches the state of the switching circuit 3B from the first state to the second state to discharge one cell. At the same time, the controller 4 turns off SW14 to operate the DCDC 13 and forcibly charge cells other than the cell to be discharged.

[0103] As a result, the lowest cell voltage increases as the cell with the lowest cell voltage is charged, so the controller 4 also increases the discharge target voltage of the cell to be discharged in accordance with the increase in the lowest cell voltage. Therefore, when equalizing the cell voltages, by simultaneously discharging and charging, the voltage of the cell to be discharged reaches the discharge target voltage more quickly, and the equalization time can be shortened.

[0104] [2-2. Processing Executed by the Controller According to the Second Embodiment] Next, processing executed by the controller 4 according to the second embodiment will be described with reference to Fig. 8 and Fig. 9. Fig. 8 and Fig. 9 are flowcharts showing an example of processing executed by the controller 4 of the power supply control device 1A according to the second embodiment.

[0105] 4, when the IG is turned on, the controller 4 turns on the first power supply SW 41, the second power supply SW 42, the first load SW 43, the second load SW 44, and the third load SW 45 (step S201).The controller 4 also turns off the first equalization SW 51, the second equalization SW 52, the third equalization SW 53, and the fourth equalization SW 54 (step S202).

[0106] Furthermore, the controller 4 turns on the first SPSW 91, the second SPSW 92, the third SPSW 93, the fourth SPSW 94, the fifth SPSW 95, the sixth SPSW 96, and the seventh SPSW 97, and turns on SW 14 (step S203).Then, the controller 4 turns off the first BPSW 81, the second BPSW 82, the third BPSW 83, and the fourth BPSW 84 (step S204).

[0107] In this way, the controller 4 connects each cell of the second power source 20 in series, sets the switching circuit 3B to the first state, and uses all of the first cell 21, the second cell 22, the third cell 23, and the fourth cell 24 to supply power to the first load 101, the second load 102, and the third load 103.

[0108] Next, the controller 4 determines whether or not it is necessary to charge the second power source 20 (step S205). At this time, the controller 4 determines whether or not it is necessary to charge the second power source 20 by the same method as in the first embodiment.

[0109] If the controller 4 determines that charging of the second power supply 20 is not necessary (step S205, No), the process proceeds to step S209 shown in Fig. 9. On the other hand, if the controller 4 determines that charging of the second power supply 20 is necessary (step S205, Yes), the controller 4 turns off SW14, operates the DCDC 13 included in the power supply circuit 2 (step S206), and charges the second power supply 20 by boosting the voltage supplied from the first power supply 10 to a predetermined charging voltage.

[0110] Thereafter, the controller 4 determines whether the voltage of the second power source 20 has reached the charging target voltage (step S207). If the controller 4 determines that the voltage of the second power source 20 has not reached the charging target voltage (step S207, No), the controller 4 proceeds to step S209 shown in FIG.

[0111] Furthermore, when the controller 4 determines that the voltage of the second power supply 20 has reached the charging target voltage (Yes at step S207), the controller 4 turns on the SW14 to stop the operation of the DCDC 13 (step S208).

[0112] 9, the controller 4 determines whether or not cell voltage equalization is in progress (step S209). If cell voltage equalization is not being performed (step S209, No), the controller 4 determines whether cell voltage equalization is necessary (step S210). If cell voltage equalization is in progress (step S209, Yes), the controller 4 proceeds to step S213.

[0113] In step S210, the controller 4 determines that cell voltage equalization is necessary when the maximum-minimum voltage difference, which is the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage, is equal to or greater than a predetermined threshold.

[0114] Specifically, the controller 4 detects the cell voltage of each cell, and sets an equalization flag (sets it to 1) when the maximum / minimum voltage difference is equal to or greater than a predetermined threshold. If the equalization flag is set in step S210, the controller 4 determines that cell voltage equalization is necessary. If the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage is less than a predetermined threshold, specifically if the equalization flag is not set (0), the controller 4 determines that cell voltage equalization is not necessary.

[0115] If the controller 4 determines that cell voltage equalization is not necessary (step S210, No), the process proceeds to step S215. If the controller 4 determines that cell voltage equalization is necessary (step S210, Yes), the controller 4 calculates a discharge target voltage for the cell to be discharged (step S211).

[0116] Here, the cell with the highest cell voltage is set as the cell to be discharged, and the cell voltage of the cell with the lowest cell voltage is set as the target discharge voltage.Then, the controller 4 disconnects the cell to be discharged from the power supply path (step S212).

[0117] At this time, the controller 4 turns on the BPSWs that bypass the cell to be discharged, among the first to fourth BPSWs 81 to 84. The controller 4 also turns off the SPSWs connected to both ends of the cell to be discharged, among the first to seventh SPSWs 91 to 97. Furthermore, the controller 4 turns on the equalization SWs connected to the cell to be discharged, among the first to fourth equalization SWs 51 to 54.

[0118] In this way, the controller 4 disconnects one cell from the other cells among the cells included in the second power source 20, connects the other cells in series, sets the switching circuit 3B to the second state, disconnects the cell to be discharged from the power supply path and discharges it, and sets the remaining cells to a state where they can be powered.

[0119] Thereafter, the controller 4 determines whether the cell voltage of the cell to be discharged has reached the discharge target voltage (step S213). The controller 4 determines whether the discharge target voltage has been reached based on the cell voltage obtained from a voltage sensor that detects the voltage of the cell to be discharged. For example, when the cell to be discharged is the third cell 23, the controller 4 determines whether the discharge target voltage has been reached based on the cell voltage obtained from the third voltage sensor 73.

[0120] If the controller 4 determines that the cell voltage of the discharge target cell has not reached the discharge target voltage (step S213, No), it proceeds to step S215. If the controller 4 determines that the cell voltage of the discharge target cell has reached the discharge target voltage (step S213, Yes), it releases the discharge target cell from being disconnected from the power supply path (step S214). That is, the controller 4 connects the cells of the second power supply 20 in series and sets the switching circuit 3B to the first state.

[0121] Thereafter, the controller 4 determines whether or not a ground fault (fault) has occurred (step S215). At this time, the controller 4 determines whether or not a ground fault has occurred by the same method as in the first embodiment.

[0122] If the controller 4 determines that no ground fault has occurred (step S215, No), it proceeds to step S205 shown in Fig. 8. Therefore, once the controller 4 determines in step S210 that equalization is necessary and starts discharging the discharge target cell in step S212, the controller 4 equalizes the cell voltages by repeatedly executing step S209, Yes, and then step S213, unless a ground fault has occurred.

[0123] Furthermore, when the controller 4 determines that a ground fault has occurred (Yes in step S215), if the second power source 20 is currently being charged, it stops the charging (step S216). At this time, if the second power source 20 is not currently being charged, the controller 4 skips the process of step S216 and moves the process to step S217.

[0124] In step S217, if the cell voltages are being equalized, that is, if the equalization flag is set, the controller 4 performs the same control as in step S214 to release the discharge target cell from the power supply path (step S217). In this way, the controller 4 stops, for example, the cell voltage equalization. At this time, the controller 4 sets the equalization flag to 0.

[0125] If the cell voltages are not being equalized in step S217, the controller 4 does not execute the process of step S217 and identifies the location of the ground fault (step S218). Specifically, the controller 4 sequentially turns off the first power feed SW 41, the second power feed SW 42, the first load SW 43, the second load SW 44, and the third load SW 45, and identifies the location of the ground fault from the voltage of the common power feed line L1 acquired from the voltage sensor 70 at that time. The method of identifying the location of the ground fault is the same as in the first embodiment, and therefore description thereof will be omitted. Thereafter, the controller 4 performs fail-safe control similar to that in the first embodiment (step S219) and ends the process.

[0126] 3. Third Embodiment [3-1. Operation of the power supply control device according to the third embodiment] Next, the operation of the power supply control device 1A according to the third embodiment will be described with reference to Fig. 10. Fig. 10 is an explanatory diagram of the operation of the power supply control device 1A according to the third embodiment. The configuration of the power supply control device 1A according to the third embodiment is the same as that of the power supply control device 1A according to the second embodiment. Therefore, redundant explanations of the configuration of the power supply control device 1A according to the third embodiment will be omitted here, and only the operation will be described.

[0127] In the second embodiment, four cells are connected in series to supply power to the first to third loads 101 to 103 during normal operation, and the cell to be discharged is disconnected from the power supply path during equalization, and power is supplied by the remaining three cells.

[0128] In contrast, in the power supply control device 1A according to the third embodiment, during normal operation, one specific cell is disconnected from the power supply path, and the remaining three cells are connected in series to supply power to the first to third loads 101 to 103.

[0129] For example, when the power supply control device 1A determines the fourth cell 24 as the specified cell, it turns off the sixth SPSW 96 and the seventh SPSW 97 to disconnect the fourth cell 24 from the power supply path, as shown in Figure 10. Then, the power supply control device 1A turns on the first to fifth SPSWs 91 to 95 and the fourth BPSW 84, and turns off the first to third BPSWs 81 to 83 and the first to fourth equalization SWs 51 to 54.

[0130] In this way, the power supply control device 1A disconnects the specified cell from the power supply path. Note that the power supply control device 1A determines the specified cell from among the cells included in the second power supply 20 every time the IG is turned on (every trip). For example, the power supply control device 1A determines the specified cell in the order of the first cell 21, the second cell 22, the third cell 23, and the fourth cell 24. In this case, the first cell 21 becomes the specified cell after the fourth cell 24. This makes it easier for the power supply control device 1A to switch the specified cell.

[0131] The power supply control device 1A may also be configured to periodically determine a specific cell from among the cells included in the second power supply 20. In this way, the power supply control device 1A can extend the life of each cell by sequentially selecting specific cells from among the cells included in the second power supply 20 and disconnecting the selected cells from the power supply path.

[0132] Furthermore, during equalization, the power supply control device 1A disconnects the cell to be discharged and connects the remaining two cells in series with the specified cell to supply power using three cells. For example, when the cell to be discharged is the third cell 23, the power supply control device 1A supplies power to the first to third loads 101 to 103 with each SW in the same state as shown in Fig. 6. In other words, the power supply control device 1A supplies power to the first to third loads 101 to 103 using three cells both during normal operation and during equalization.

[0133] According to the power supply control device 1A of the third embodiment, specific cells are normally disconnected from the power supply path and do not discharge, but are connected to the power supply path during equalization, thereby ensuring sufficient power to complete evacuation driving while extending the life of the cells.

[0134] The power supply control device 1A according to the third embodiment may be configured to cancel the isolation of a specific cell and supply power to the load from all cells included in the second power supply 20 if a failure occurs in the first power supply 10 while equalizing the cell voltages. In this way, the power supply control device 1A can more reliably complete evacuation travel by supplying power to the load from all cells when a failure occurs in the first power supply 10.

[0135] Furthermore, the power supply control device 1A according to the third embodiment may be configured to cancel the isolation of a specific cell and supply power to the load from all cells included in the second power supply 20 if a failure occurs in the first power supply 10 when cell voltage equalization is not being performed. In this way, the power supply control device 1A can supply power to the load from all cells when a failure occurs in the first power supply 10, thereby more reliably completing evacuation travel.

[0136] [3-2. Processing Executed by the Controller According to the Third Embodiment] Next, processing executed by the controller 4 according to the third embodiment will be described with reference to Fig. 11 and Fig. 12. Fig. 11 and Fig. 12 are flowcharts showing an example of processing executed by the controller 4 of the power supply control device 1A according to the third embodiment.

[0137] The controller 4 starts the process shown in Fig. 11 at the start of a trip (when the IG is turned on). Specifically, when the IG is turned on, the controller 4 determines the specific cell as shown in Fig. 11 (step S301). At this time, the controller 4 slides the cell number (1 to 4) by one to determine the specific cell. For example, if the first cell 21 was selected the last time the IG was turned on, the controller 4 determines the second cell 22 when the IG is turned on this time. Note that the specific cell may be determined at regular intervals rather than at the start of a trip.

[0138] Next, the controller 4 turns on SW14, the first power supply SW 41, the second power supply SW 42, the first load SW 43, the second load SW 44, and the third load SW 45 (step S302).The controller 4 also turns off the first equalization SW 51, the second equalization SW 52, the third equalization SW 53, and the fourth equalization SW 54 (step S303).

[0139] Furthermore, the controller 4 turns off the SWs corresponding to the specific cell among the first to seventh SPSWs 91 to 97, and turns on the remaining SWs (step S304). In this way, the controller 4 disconnects the specific cell from the power supply path.

[0140] Next, the controller 4 turns on the SW corresponding to the specified cell among the first to fourth BPSWs 81 to 84 and turns off the remaining SWs (step S305). In this way, the controller 4 forms a power supply path that bypasses the specified cell. As a result, the specified cell is disconnected from the power supply path, and the remaining three cells are connected in series to supply power to the first to third loads 101 to 103.

[0141] Thereafter, the controller 4 determines whether or not it is necessary to charge the second power source 20 (step S306). At this time, the controller 4 determines whether or not it is necessary to charge the second power source 20 by the same method as in the first embodiment.

[0142] If the controller 4 determines that charging of the second power supply 20 is not necessary (step S306, No), the process proceeds to step S310 shown in Fig. 12. On the other hand, if the controller 4 determines that charging of the second power supply 20 is necessary (step S306, Yes), the controller 4 turns off SW14, operates the DCDC 13 included in the power supply circuit 2 (step S307), and boosts the voltage supplied from the first power supply 10 to a predetermined charging voltage to charge the second power supply 20.

[0143] Thereafter, the controller 4 determines whether the voltage of the second power source 20 has reached the charging target voltage (step S308). If the controller 4 determines that the voltage of the second power source 20 has not reached the charging target voltage (step S308, No), the controller 4 proceeds to step S310 shown in FIG.

[0144] Furthermore, when the controller 4 determines that the voltage of the second power supply 20 has reached the charging target voltage (Yes at step S308), the controller 4 turns on the SW14 to stop the operation of the DCDC 13 (step S309).

[0145] 12, the controller 4 determines whether or not cell voltage equalization is in progress (step S310). If cell voltage equalization is not in progress (step S310, No), the controller 4 determines whether or not cell voltage equalization is necessary (step S311). If cell voltage equalization is in progress (step S310, Yes), the controller 4 proceeds to step S315.

[0146] In step S311, the controller 4 determines that cell voltage equalization is necessary when the maximum-minimum voltage difference, which is the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage, is equal to or greater than a predetermined threshold.

[0147] Specifically, the controller 4 detects the cell voltage of each cell, and sets an equalization flag (sets it to 1) when the maximum / minimum voltage difference is equal to or greater than a predetermined threshold. If the equalization flag is set in step S311, the controller 4 determines that cell voltage equalization is necessary. If the difference between the cell voltage of the cell with the lowest cell voltage and the cell voltage of the cell with the highest cell voltage is less than a predetermined threshold, specifically if the equalization flag is not set (0), the controller 4 determines that cell voltage equalization is not necessary.

[0148] If the controller 4 determines that cell voltage equalization is not necessary (step S311, No), the process proceeds to step S318. If the controller 4 determines that cell voltage equalization is necessary (step S311, Yes), the controller 4 calculates a discharge target voltage for the cell to be discharged (step S312).

[0149] Here, the cell with the highest cell voltage is set as the cell to be discharged, and the cell voltage of the cell with the lowest cell voltage is set as the target discharge voltage.Then, the controller 4 disconnects the cell to be discharged from the power supply path (step S313).

[0150] At this time, the controller 4 turns on the BPSWs among the first to fourth BPSWs 81 to 84 that bypass the cell to be discharged. Also, the controller 4 turns off the SPSWs among the first to seventh SPSWs 91 to 97 that are connected to both ends of the cell to be discharged. Furthermore, the controller 4 turns on the equalization SWs among the first to fourth equalization SWs 51 to 54 that are connected to the cell to be discharged. Next, the controller 4 releases the separation of the specific cell from the power supply path (step S314).

[0151] In this way, the controller 4 disconnects one cell to be discharged from the other cells included in the second power source 20 and connects a specific cell to the power supply path instead, thereby connecting the other cells other than the one cell to be discharged in series and setting the switching circuit 3B to the second state, disconnecting the cell to be discharged from the power supply path and discharging it, while setting the remaining cells to a state where they can be powered.

[0152] Thereafter, the controller 4 determines whether the cell voltage of the cell to be discharged has reached the discharge target voltage (step S315). The controller 4 determines whether the discharge target voltage has been reached based on the cell voltage obtained from a voltage sensor that detects the voltage of the cell to be discharged. For example, when the cell to be discharged is the third cell 23, the controller 4 determines whether the discharge target voltage has been reached based on the cell voltage obtained from the third voltage sensor 73.

[0153] If the controller 4 determines that the cell voltage of the cell to be discharged has not reached the discharge target voltage (step S315, No), it proceeds to step S318. If the controller 4 determines that the cell voltage of the cell to be discharged has reached the discharge target voltage (step S315, Yes), it releases the disconnection of the cell to be discharged from the power supply path (step S316). That is, the controller 4 connects the cells of the second power supply 20 in series and sets the switching circuit 3B to the first state. Furthermore, the controller 4 disconnects the specified cell from the power supply path (step S317). As a result, when cell balancing is completed, the cells other than the specified cell are again connected in series.

[0154] Thereafter, the controller 4 determines whether or not a ground fault (fault) has occurred (step S318). At this time, the controller 4 determines whether or not a ground fault has occurred by the same method as in the first embodiment.

[0155] If the controller 4 determines that no ground fault has occurred (step S318, No), it proceeds to step S306 shown in Fig. 11. Therefore, once the controller 4 determines in step S210 that equalization is necessary and starts discharging the discharge target cell in step S305, the controller 4 equalizes the cell voltages by repeatedly executing step S310, Yes, and then step S315, unless a ground fault has occurred.

[0156] Furthermore, when the controller 4 determines that a ground fault has occurred (step S318, Yes), if the second power source 20 is currently being charged, the controller 4 stops the charging (step S319). At this time, if the second power source 20 is not currently being charged, the controller 4 skips the process of step S319 and moves the process to step S320.

[0157] In step S320, if the cell voltages are being equalized, i.e., if the equalization flag is set, the controller 4 performs the same control as in step S316 to release the disconnection of the discharge target cell from the power supply path (step S320). In this way, the controller 4, for example, stops the cell voltage equalization. At this time, the controller 4 sets the equalization flag to 0.

[0158] Thereafter, the controller 4 releases the separation of the specific cell from the power supply path (step S321). Note that the controller 4 may execute the process of step S321 after executing step S322 (described later) and before executing step S323. In this case, the controller 4 releases the separation of the characteristic cell when the ground fault location is not on the second power source 20 side, that is, when the second power source 20 is normal.

[0159] If the cell voltages are not being equalized in step S321, the controller 4 does not execute the process of step S321 and identifies the location of the ground fault (step S322). Specifically, the controller 4 sequentially turns off the first power feed SW 41, the second power feed SW 42, the first load SW 43, the second load SW 44, and the third load SW 45, and identifies the location of the ground fault from the voltage of the common power feed line L1 acquired from the voltage sensor 70 at that time. The method of identifying the location of the ground fault is the same as in the first embodiment, and therefore description thereof will be omitted. Thereafter, the controller 4 performs fail-safe control similar to that in the first embodiment (step S323) and ends the process.

[0160] In the first, second, and third embodiments described above, the switch control in the event of a power failure and the switch control for equalizing the cell voltages are performed by a single controller 4 (microcomputer), but the above two controls may each be performed by separate microcomputers.

[0161] In the above embodiment, the second power source 20 is exemplified as having one redundant cell in addition to three cells capable of supplying power to the load during the backup time required for a pre-estimated evacuation run in the event of a failure of the first power source 10, but the number of redundant cells may be two or more.

[0162] [4. Notes] As an appendix, the features of the present invention are as follows. (1) a controller mounted on a vehicle including a first power supply and a second power supply including a cell having a capacity capable of supplying power to a load for a backup time estimated in advance in the event of a failure of the first power supply and a redundant cell, the controller controlling power supply to the load and equalizing cell voltages of the second power supply; The controller When it is determined that the cell voltages need to be equalized, among the cells included in the second power supply, cells having a cell voltage higher than the cell having the lowest cell voltage are discharged toward a target voltage to equalize the cell voltages, while supplying power from the remaining cells to the load. Power control device. (2) The controller If a failure occurs in the first power source while the cell voltages are being equalized, the equalization of the cell voltages is stopped, and power is supplied to the load from all of the cells included in the second power source. The power supply control device according to (1) above. (3) a switching circuit that can switch between a first state in which the cells of the second power supply are connected in series to supply power to the load and a second state in which one of the cells included in the second power supply is disconnected from the other cells and the other cells are connected in series to supply power to the load; Equipped with The controller When it is determined that the cell voltages need to be equalized, the state of the switching circuit is switched from the first state to the second state, thereby discharging the one cell and equalizing the cell voltages. The power supply control device according to (1) or (2). (4) The controller when it is determined that charging of the second power source is necessary during equalization of the cell voltages of the second power source, power is supplied from the first power source to the second power source while maintaining the state of the switching circuit in the second state, thereby charging the second power source; The power supply control device according to (3) above. (5) The controller When equalizing the cell voltages of the second power source, power is supplied from the first power source to the second power source while maintaining the state of the switching circuit in the second state, to charge the second power source. The power supply control device according to (3) above. (6) a switching circuit that can switch one of the cells included in the second power supply to a state in which it can supply power to the load by disconnecting one of the cells from the other cells and connecting the other cells in series; Equipped with The controller In normal times, the state of the switching circuit is switched so that a specific cell among the cells included in the second power supply is separated from the other cells and the other cells are connected in series to supply power to the load; When it is determined that the cell voltages need to be equalized, the state of the switching circuit is switched so that the cell to be discharged among the other cells is disconnected and the remaining cells including the specific cell are connected in series to supply power to the load. The power supply control device according to (1) above. (7) The controller The specific cell is switched from among the cells included in the second power source for each trip. The power supply control device according to (6) above. (8) The controller The specific cell is switched at regular intervals from among the cells included in the second power source. The power supply control device according to (6) or (7). (9) The controller If a failure occurs in the first power source while the cell voltages are being equalized, the equalization of the cell voltages is stopped, and power is supplied to the load from all of the cells included in the second power source. The power supply control device according to any one of (6) to (8). (10) The controller When the equalization is not performed and a failure occurs in the first power source, the isolation of the specific cell is canceled and power is supplied to the load from all of the cells included in the second power source. The power supply control device according to any one of (6) to (9). (11) a first power source; a second power source including a cell and a redundant cell having a capacity capable of supplying power to a load for a predetermined backup time when the first power source fails; a controller that controls power supply to the load and equalizes the cell voltages of the second power source; Includes The controller When it is determined that the cell voltages need to be equalized, the cell having the highest cell voltage among the cells included in the second power supply is discharged to equalize the cell voltages, and power is supplied to the load from the remaining cells. Power control system.

[0163] 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]

[0164] 1.1A Power Supply Control Device 2 Power supply circuit 3,3A balancing circuit 3B Switching Circuit 4 Controller 10 1st power supply 11,13 DCDC 12 Automatic driving control device 20 2nd power supply 21 Cell 1 22 Cell 2 23 Cell 3 24 Cell 4 41 First power supply switch 42 Second power supply switch 43 1st load SW 44 2nd load SW 45 3rd load SW 51 First Equalization SW 52 Second equalization switch 53 Third Equalization SW 54 4th Equalization SW 61 1st resistance 62 2nd resistor 63 3rd resistor 64 4th resistor 70 Voltage Sensor 71 First voltage sensor 72 Second voltage sensor 73 Third voltage sensor 74 4th voltage sensor 81 1st BPSW 82 2nd BPSW 83 3rd BPSW 84 4th BPSW 91 1st SPSW 92 2nd SPSW 93 3rd SPSW 94 4th SPSW 95 5th SPSW 96 6th SPSW 97 7th SPSW 101 1st load 102 2nd load 103 Third load

Claims

1. a controller mounted on a vehicle including a first power supply and a second power supply including a cell having a capacity capable of supplying power to a load for a backup time estimated in advance in the event of a failure of the first power supply and a redundant cell, the controller controlling power supply to the load and equalizing cell voltages of the second power supply; The controller When it is determined that the cell voltages need to be equalized, among the cells included in the second power supply, cells having a cell voltage higher than the lowest cell voltage are discharged toward a target voltage to equalize the cell voltages, while supplying power from the remaining cells to the load. Power control device.

2. The controller If a failure occurs in the first power source while the cell voltages are being equalized, the equalization of the cell voltages is stopped, and power is supplied to the load from all of the cells included in the second power source. The power supply control device according to claim 1 .

3. a switching circuit that can switch between a first state in which the cells of the second power supply are connected in series to supply power to the load and a second state in which one of the cells included in the second power supply is disconnected from the other cells and the other cells are connected in series to supply power to the load; Equipped with The controller When it is determined that the cell voltages need to be equalized, the state of the switching circuit is switched from the first state to the second state, thereby discharging the one cell and equalizing the cell voltages. The power supply control device according to claim 1 .

4. The controller when it is determined that charging of the second power source is necessary during equalization of the cell voltages of the second power source, power is supplied from the first power source to the second power source while maintaining the state of the switching circuit in the second state, thereby charging the second power source; The power supply control device according to claim 3 .

5. The controller When equalizing the cell voltages of the second power source, the second power source is charged by supplying power from the first power source to the second power source while maintaining the state of the switching circuit in the second state. The power supply control device according to claim 3 .

6. a switching circuit that can switch one of the cells included in the second power supply to a state in which it can supply power to the load by disconnecting one of the cells from the other cells and connecting the other cells in series; Equipped with The controller In a normal state, the state of the switching circuit is switched so that a specific cell among the cells included in the second power supply is separated from the other cells and the other cells are connected in series to supply power to the load; When it is determined that the cell voltages need to be equalized, the state of the switching circuit is switched so that the cell to be discharged among the other cells is disconnected and the remaining cells including the specific cell are connected in series to supply power to the load. The power supply control device according to claim 1 .

7. The controller The specific cell is switched from among the cells included in the second power source for each trip. The power supply control device according to claim 6.

8. The controller The specific cell is switched at regular intervals from among the cells included in the second power source. The power supply control device according to claim 6.

9. The controller If a failure occurs in the first power source while the cell voltages are being equalized, the equalization of the cell voltages is stopped, and power is supplied to the load from all of the cells included in the second power source. The power supply control device according to claim 6.

10. The controller When the equalization is not performed and a failure occurs in the first power source, the isolation of the specific cell is canceled and power is supplied to the load from all the cells included in the second power source. The power supply control device according to claim 6.

11. a first power source; a second power supply including a cell and a redundant cell having a capacity capable of supplying power to a load for a predetermined backup time when the first power supply fails; a controller that controls power supply to the load and equalizes cell voltages of the second power source; Includes The controller When it is determined that the cell voltages need to be equalized, the cell having the highest cell voltage among the cells included in the second power supply is discharged to equalize the cell voltages, while the remaining cells supply power to the load. Power control system.

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