Vehicle, and battery control method

Abstract

Provided is a vehicle that, in a failure diagnosis of a battery supplying power to an auxiliary machine, avoids initialization of the auxiliary machine by preventing cutoff of the power supplied to the auxiliary machine.　A vehicle (100A) comprises: a first battery (11A) that supplies power to a travel motor (52) of the vehicle; a second battery (21) that supplies power to an auxiliary machine of the vehicle (100A); a switching circuit (23) that switches the second battery (21) to a charging state, in which the second battery (21) is charged by the power output by the first battery (11A), or a discharging state, in which the power stored in the second battery (21) is discharged; a failure diagnosis unit (410) that performs a failure diagnosis of the second battery (21) if the vehicle (100A) is in a prescribed state; and a power supply control unit (413) that controls the switching circuit (23) so that the power of the first battery (11A) is supplied to the auxiliary machine if the failure diagnosis unit (410) performs the failure diagnosis of the second battery.

Description

Vehicle and battery control method

[0001] The present invention relates to a vehicle and a battery control method.

[0002] In recent years, lithium-ion batteries have come into use as auxiliary batteries. Lithium-ion batteries can be equipped with circuits such as relay circuits, and these circuits are used to diagnose faults in lithium-ion batteries.

[0003] For example, Patent Document 1 discloses a power supply system comprising a main battery for storing power supplied to a drive motor, a starting motor for starting an engine, an auxiliary battery for storing power supplied to the starting motor and auxiliary equipment, and a control device. The auxiliary battery is connected to the auxiliary equipment via a switch, and in abnormality diagnosis, the control device diagnoses whether or not there is an abnormality in the auxiliary battery based on the electrical state quantity of the auxiliary battery with the switch open.

[0004] Japanese Patent Publication No. 2020-011529

[0005] However, diagnosing a battery that supplies power to the vehicle's auxiliary equipment required the vehicle to be stationary, as it involved cutting off the power supply from the battery to the auxiliary equipment to determine the battery's fault. Furthermore, because the power supply to the auxiliary equipment was cut off during the diagnostic process, there was a risk that the auxiliary equipment might be reset.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a vehicle and a battery control method that suppress the interruption of power supply to auxiliary equipment in the fault diagnosis of a battery that supplies power to auxiliary equipment, thereby preventing the auxiliary equipment from being initialized.

[0007] The vehicle comprises a first battery that supplies power to the vehicle's drive motor, a second battery that supplies power to the vehicle's auxiliary equipment, a switching circuit that switches the second battery between a charging state, where it is charged by the power output of the first battery, and a discharge state, where it discharges the power stored in the second battery, a fault diagnosis unit that diagnoses a fault in the second battery when the vehicle is in a predetermined state, and a power supply control unit that controls the switching circuit so that power from the first battery is supplied to the auxiliary equipment when the fault diagnosis unit performs a fault diagnosis of the second battery.

[0008] The battery control method causes a computer mounted on a vehicle, which includes a first battery that supplies power to a drive motor and a second battery that supplies power to an auxiliary device, to perform the following steps: to detect whether the vehicle is in a predetermined state; to diagnose a fault in the second battery if the vehicle is in the predetermined state; and to have the first battery supply power to the auxiliary device when performing the fault diagnosis.

[0009] In diagnosing a battery failure that supplies power to an auxiliary device, it is possible to provide a vehicle and a battery control method that suppress the interruption of power supply to the auxiliary device and prevent the auxiliary device from being initialized.

[0010] Figure 1 is a diagram showing the configuration of the vehicle in Embodiment 1. Figure 2 is a flowchart of the processes performed by the vehicle. Figure 3 is a diagram showing the currents flowing through the relay circuit and various parts of the vehicle during charging-side fault diagnosis. Figure 4 is a diagram showing the currents flowing through the relay circuit and various parts of the vehicle during discharge-side fault diagnosis. Figure 5 is a diagram showing the configuration of the vehicle in Embodiment 2. Figure 6A is a diagram showing the configuration of the vehicle ECU in Embodiment 2. Figure 6B is a diagram showing the configuration of the second battery ECU in Embodiment 2. Figure 7 is a diagram for explaining the pre-start state and the start-up extension state.

[0011] Embodiments of the present invention will be described below with reference to the drawings.

[0012] (Embodiment 1) [1-1. Vehicle Configuration] Figure 1 shows the configuration of a vehicle 100A of Embodiment 1 to which the present invention is applied. The vehicle 100A is a BEV (Battery Electric Vehicle) and is equipped with a first battery module 1A, a second battery module 2, a vehicle ECU 6, and the like.

[0013] The first battery module 1A includes a first battery 11A that supplies power to the vehicle 100A's drive motor 52, a first battery control circuit 12A that controls the first battery 11A, and a battery contactor 13A that permits charging and discharging of the first battery 11A. The first battery module 1A also includes a first battery ECU 14A. The first battery ECU 14A is a computer that is responsible for controlling the vehicle 100A, particularly the first battery 11A. The first battery ECU 14A includes a processor and memory.

[0014] Charging of the first battery 11A is mainly performed by an external power supply device. The DC voltage output from the first battery 11A is converted to AC voltage by the inverter 51 and supplied to the traction motor 52. The DC voltage output from the first battery 11A is also reduced in voltage by the DC / DC converter 31 and supplied to the second battery module 2. The DC / DC converter 31 is an example of a voltage conversion unit.

[0015] The second battery module 2 includes a second battery 21 that supplies power to the auxiliary equipment 32, a second battery control circuit 22 that controls the second battery 21, a relay circuit 23, and a second battery ECU 4. For example, a lithium-ion battery is used for the second battery 21.

[0016] The relay circuit 23 includes a charge-cut relay 231 that cuts off charging of the second battery 21, and a discharge-cut relay 233 that cuts off discharging of the second battery 21. When fault diagnosis is performed on the charging side of the second battery 21, the charge-cut relay 231 is turned off. Similarly, when fault diagnosis is performed on the discharging side of the second battery 21, the discharge-cut relay 233 is turned off. The on / off switching of the charge-cut relay 231 and the discharge-cut relay 233 is achieved by the second battery ECU 4 controlling the second battery control circuit 22. The relay circuit 23 is an example of a switching circuit.

[0017] The auxiliary equipment 32 powered by the second battery 21 includes, for example, meters, audio systems, displays, and headlights. The second battery 21 also supplies power to the brake motor 33 and motors that drive the steering and windows.

[0018] When starting a stationary vehicle 100A, the output of the second battery 21 is input to the battery contactor 13A. The battery contactor 13A functions as a switch that allows charging and discharging of the first battery 11A. Specifically, first, a permission signal is sent from the vehicle ECU 6 to the first battery control circuit 12A. Next, a permission signal is sent from the first battery control circuit 12A to the battery contactor 13A. When the permission signal is input from the first battery control circuit 12A, the output of the second battery 21 is input, turning on the battery contactor 13A. This starts the supply of power to the drive motor 52. With power supplied to the drive motor 52, the vehicle 100A becomes ready to drive.

[0019] The vehicle ECU (Engine Control Unit) 6 is a computer for performing various controls on the vehicle 100A, and includes a processor 61 and memory 62. The configuration of the vehicle ECU 6 will be described later.

[0020] The second battery ECU 4 is a computer responsible for controlling the vehicle 100A, particularly the control of the second battery 21. The second battery ECU 4 according to this embodiment includes a processor 41 and a memory 42.

[0021] The memory 42 includes non-volatile semiconductor memory such as ROM (Read Only Memory) and volatile semiconductor memory such as RAM (Random Access Memory). The non-volatile semiconductor memory stores control programs executed by the processor 41 and various setting data. The volatile semiconductor memory is used as the arithmetic area of ​​the processor 41. The memory 42 may also be configured to include only non-volatile semiconductor memory.

[0022] The processor 41 is composed of arithmetic processing units such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). The processor 41 may be composed of a single processor or multiple processors.

[0023] The processor 41 includes a fault diagnosis unit 410, a power supply control unit 413, and a processing unit 414 as functional units. These functional units are realized when the processor 41 executes a control program stored in the memory 42.

[0024] The fault diagnosis unit 410 includes a charging-side fault diagnosis unit 411 that detects faults on the charging side of the second battery 21, and a discharge-side fault diagnosis unit 412 that detects faults on the discharge side of the second battery 21. The charging-side fault diagnosis unit 411, for example, causes the second battery control circuit 22 to execute various charge and discharge controls and determines whether the charge control of the second battery 21 is being performed normally based on the measured values ​​of the voltage and current of the second battery 21. Similarly, the discharge-side fault diagnosis unit 412, for example, causes the second battery control circuit 22 to execute various charge and discharge controls and determines whether the discharge control of the second battery 21 is being performed normally based on the measured values ​​of the voltage and current of the second battery 21.

[0025] The power supply control unit 413 controls the second battery control circuit 22 to switch the relay circuit 23 of the second battery module 2 to an on state or an off state. Specifically, when the charging-side failure diagnosis unit 411 performs failure diagnosis on the charging side of the second battery 21, the power supply control unit 413 controls the second battery control circuit 22 to turn on / off the charging cutoff relay 231 while keeping the discharge cutoff relay 233 of the relay circuit 23 turned on. The charging-side failure diagnosis unit 411 turns on / off the charging cutoff relay 231 and measures the voltage and current of the second battery 21 and the charging switch 231A, thereby detecting whether power can be supplied to the second battery 21 or whether power supply to the second battery 21 is cut off.

[0026] In addition, when performing failure diagnosis on the discharge side of the second battery 21, the vehicle ECU 6 first determines whether the vehicle 100A is in a predetermined state. The predetermined state includes an external power supply state and a supplementary charging state. The external power supply state is a state where the first battery 11A is being charged by a power supply device. The supplementary charging state is a state where the second battery is charged with electric power supplied from the first battery 11A.

[0027] The discharge-side failure diagnosis unit 412 performs failure diagnosis on the discharge side of the second battery 21 when the vehicle 100A is in the predetermined state. When the discharge-side failure diagnosis unit 412 performs failure diagnosis on the discharge side of the second battery 21, the power supply control unit 413 controls the second battery control circuit 22 to turn on / off the discharge cutoff relay 233. The discharge-side failure diagnosis unit 412 turns on / off the discharge cutoff relay 233 and measures the voltage and current of the second battery 21 and the charging switch 231A, thereby detecting whether power can be supplied from the second battery 21 to auxiliary machines 32 and the like, or whether power supply to the auxiliary machines 32 and the like is cut off.

[0028] The processing unit 414 performs general-purpose processing such as, for example, processing for acquiring information transmitted from the vehicle ECU 6, processing for controlling each battery based on instructions from the vehicle ECU 6, and processing for information transmitted from the first battery module 1A and the second battery module 2.

[0029] [1-2. Operation of the Battery Control Device] Figure 2 is a flowchart showing the operation of the second battery ECU 4 and the vehicle ECU 6 during fault diagnosis. The operation of the second battery ECU 4 and the vehicle ECU 6 during fault diagnosis will be explained with reference to the flowchart shown in Figure 2, and with reference to Figures 3 and 4 as appropriate.

[0030] First, the second battery ECU 4 determines whether the fault diagnosis to be performed is a fault diagnosis on the charging side or a fault diagnosis on the discharging side (step S1).

[0031] If the second battery ECU 4 determines that a fault diagnosis on the charging side is to be performed (step S1: charging side), the process proceeds to step S2. In step S2, the charging side fault diagnosis unit 411 of the second battery ECU 4 causes the power supply control unit 413 to control the second battery control circuit 22 to turn the charge interruption relay 231 of the relay circuit 23 on or off (step S2).

[0032] Here, referring to Figure 3, the configuration of the relay circuit 23 and the operation of the relay circuit 23 when performing fault diagnosis on the charging side of the second battery 21 will be explained. Figure 3 shows a charging switch 231A as an example of a charging cutoff relay 231, and a discharge switch 233A as an example of a discharge cutoff relay 233. In addition to these, the relay circuit 23 also includes diode D １ , D ２ It is equipped with an ammeter IM.

[0033] When performing a fault diagnosis on the charging side of the second battery 21, as described above, the second battery control circuit 22 switches the discharge switch 233A and the charge switch 231A so that the charge switch 231A is turned off and the discharge switch 233A is turned on. When the charge switch 231A is turned off, current stops flowing from the relay circuit 23 to the second battery 21, and charging to the second battery 21 is interrupted. With the charging of the second battery 21 thus interrupted, the charging side fault diagnosis unit 411 performs a fault diagnosis on the charging side of the second battery 21 (step S3).

[0034] Troubleshooting the charging side involves, for example, measuring the voltage and current of the second battery 21 and the charging switch 231A to determine whether the various charging controls performed by the second battery control circuit 22 are functioning correctly. Once the processing in step S3 is complete, the processor 41 terminates the processing of this flowchart.

[0035] Next, when the second battery ECU 4 determines that the fault diagnosis to be performed is a fault diagnosis on the discharge side (Step S1: Discharge side), the vehicle ECU 6 determines whether or not the vehicle 100A is in a predetermined state (Step S4).

[0036] The discharge-side fault diagnosis unit 412 obtains information from the vehicle ECU 6 indicating whether or not the vehicle 100A is in an external power supply state. The vehicle ECU 6 obtains information from the first battery control circuit 12A or the first battery 11A indicating whether or not the vehicle 100A is in an external power supply state. In this case, the diagram of the signal lines connecting the first battery ECU 14A and the first battery 11A is omitted. The discharge-side fault diagnosis unit 412 also obtains information from the vehicle ECU 6 indicating whether or not the vehicle 100A is in a supplemental charging state. For example, the discharge-side fault diagnosis unit 412 obtains information from the vehicle ECU 6 indicating whether or not the vehicle 100A is in a supplemental charging state. The diagram of the signal lines connecting the second battery ECU 4 and the second battery 21 is omitted.

[0037] If the discharge-side fault diagnosis unit 412 determines that the vehicle 100A is not in a predetermined state (step S4: NO), it terminates this processing flow. If the discharge-side fault diagnosis unit 412 determines that the vehicle 100A is in a predetermined state (step S4: YES), the power supply control unit 413 of the second battery ECU 4 controls the second battery control circuit 22 to turn off the discharge cutoff relay 233 of the relay circuit 23 (step S5).

[0038] Here, referring to Figure 4, the operation of the relay circuit 23 when diagnosing a fault on the discharge side of the second battery 21 will be explained. When diagnosing a fault on the discharge side of the second battery 21, the second battery control circuit 22 switches the discharge switch 233A and the charge switch 231A so that the discharge switch 233A is turned off and the charge switch 231A is turned on. When the discharge switch 233A is turned off, current does not flow from the second battery 21 to the relay circuit 23, and the discharge of the second battery 21 is suppressed.

[0039] In this way, with the discharge from the second battery 21 shut off, the discharge-side fault diagnosis unit 412 performs fault diagnosis on the discharge side (step S6). Similar to fault diagnosis on the charge side, fault diagnosis on the discharge side is performed by measuring the voltage and current of the second battery 21 and the charge switch 231A to determine whether the various charge and discharge controls executed by the second battery control circuit 22 are being performed normally. Once the processing in step S6 is completed, the processor 41 terminates the processing of this flowchart.

[0040] As described above, when diagnosing a discharge-side fault, a process (step S4) is performed to confirm whether the vehicle 100A is in a predetermined state, but this is not performed when diagnosing a charge-side fault. The reason why this process of confirming whether the vehicle 100A is in a predetermined state is necessary only in the case of the discharge side will be explained below.

[0041] When diagnosing a fault on the discharge side of the second battery 21, the second battery control circuit 22 switches the discharge switch 233A and the charge switch 231A so that the discharge switch 233A is turned off and the charge switch 231A is turned on. As a result, the supply of power from the second battery 21 to the auxiliary equipment 32 is stopped. If power is not supplied to the auxiliary equipment 32, there is a risk that electrical components, which are a type of auxiliary equipment 32, may be reset. Therefore, when diagnosing a fault on the discharge side, it is necessary to continue supplying power to the auxiliary equipment 32.

[0042] To supply power to the auxiliary equipment 32 using a battery other than the second battery 21, the current i from the DC / DC converter 31 is required. ３It is conceivable to use this. That is, it is considered possible to diagnose a discharge-side fault when the battery is in a supplemental charging state. In addition, when the battery is externally powered, the first battery 11A is charged by the power supply device. Since the power from the first battery 11A is supplied to the auxiliary equipment 32 via the DC / DC converter 31, it is also possible to diagnose a discharge-side fault when the battery is externally powered. Thus, even if the discharge cutoff relay is turned off, if the vehicle 100A is in a predetermined state, such as either a supplemental charging state or an external power supply state, power is supplied to the auxiliary equipment 32, so it is possible to diagnose a discharge-side fault.

[0043] On the other hand, the reason why the process of checking whether the vehicle 100A is in a predetermined state can be omitted during charging-side fault diagnosis will be explained with reference to Figure 3. Figure 3(a) shows the case when the vehicle 100A is in a driving state and the first battery 11A is in the ON state, and Figure 3(b) shows the case when the vehicle 100A is in a stopped state and the first battery 11A is in the OFF state. The ON state of the first battery 11A means that the first battery 11A is supplying power, and the OFF state of the first battery 11A means that the first battery 11A has stopped supplying power.

[0044] When the first battery 11A is ON, the power of the first battery 11A is supplied to the DC / DC converter 31, which then supplies current i ２ It is supplied to the auxiliary equipment 32 as power. The power from the second battery 21 is supplied to the current i via the discharge switch 233A of the relay circuit 23. １ This power is supplied to the auxiliary equipment 32. Therefore, when the first battery 11A is ON, power is supplied to the auxiliary equipment 32.

[0045] When the first battery 11A is off, power from the first battery 11A is not supplied to the auxiliary equipment 32 via the DC / DC converter 31. However, power from the second battery 21 is supplied as current i via the discharge switch 233A of the relay circuit 23. １ This power is supplied to the auxiliary equipment 32. Therefore, even when the first battery 11A is off, power is supplied to the auxiliary equipment 32.

[0046] From the above, when diagnosing a charging-side fault, power can be supplied to the auxiliary equipment 32 regardless of whether the vehicle 100A is in a predetermined state or not, so the process of checking whether the vehicle 100A is in a predetermined state or not can be omitted.

[0047] However, if the first battery 11A is off during charging-side fault diagnosis, power can only be supplied to the auxiliary equipment 32 from the second battery 21. Therefore, if the State of Charge (SOC) of the second battery 21 is low, there is a risk that power supply to the auxiliary equipment 32 will be interrupted, and charging-side fault diagnosis should be refrained from. On the other hand, if the first battery 11A is on, power can be supplied from the first battery even if the SOC of the second battery 21 is low, so the above problem does not occur. Therefore, it is preferable for the charging-side fault diagnosis unit 411 to perform fault diagnosis when the first battery 11A is on, that is, while the DC / DC converter 31 is running.

[0048] [1-3. Effects] As described above, the vehicle 100A of Embodiment 1 includes a first battery 11A that supplies power to the vehicle 100A's drive motor 52, a second battery 21 that supplies power to the vehicle 100A's auxiliary equipment 32, a relay circuit 23 that switches the second battery 21 to a charging state in which it is charged by the power output of the first battery 11A, or to a discharge state in which it discharges the power stored in the second battery 21, a discharge-side fault diagnosis unit 412 that detects a fault on the discharge side of the second battery 21 when the vehicle 100A is in a predetermined state, and a power supply control unit 413 that controls the relay circuit 23 so that power from the first battery 11A is supplied to the auxiliary equipment 32 when the discharge-side fault diagnosis unit 412 performs a fault diagnosis. With this configuration, a fault diagnosis on the discharge side is performed when a predetermined state is reached in which power can be supplied from the first battery to the auxiliary equipment, so that the initialization of the auxiliary equipment due to the interruption of power supply during a discharge-side fault diagnosis can be suppressed. On the other hand, fault detection on the charging side is performed regardless of whether the vehicle 100A is in a predetermined state or not, which increases the timing for fault diagnosis and improves the accuracy of fault diagnosis.

[0049] Furthermore, in Embodiment 1, the relay circuit 23 includes a charging switch 231A for interrupting the charging of the second battery 21 and a discharge switch 233A for interrupting the discharge of the second battery 21. The power supply control unit 413 turns the charging switch 231A on or off when the charging-side fault diagnosis unit 411 is performing a fault diagnosis, and turns the discharge switch 233A on or off when the discharge-side fault diagnosis unit 412 is performing a fault diagnosis. With this configuration, charging of the second battery is interrupted when a fault diagnosis is performed on the charging side, and discharge of the second battery is interrupted when a fault diagnosis is performed on the discharge side, so fault diagnosis of the second battery can be performed with high accuracy.

[0050] Furthermore, in Embodiment 1, the vehicle 100A is equipped with a DC / DC converter 31 that transforms the voltage of the power stored in the first battery 11, and the predetermined state of the vehicle 100A includes at least one of an external power supply state in which the first battery 11A is charged by a power supply device, and a supplemental charging state in which the second battery 21 is charged with the power stored in the first battery 11A. With this configuration, power can be supplied from the first battery to the auxiliary equipment when a discharge-side fault diagnosis is performed, so the initialization of the auxiliary equipment due to the interruption of power supply can be suppressed.

[0051] Furthermore, in Embodiment 1, the charging-side fault diagnosis unit 411 performs fault diagnosis when the DC / DC converter 31 is running. With this configuration, since the power supply to the auxiliary equipment is not interrupted, the timing at which charging-side fault diagnosis can be performed can be increased, and the accuracy of fault diagnosis can be improved.

[0052] (Embodiment 2) The vehicle in Embodiment 2 of the present invention will be described below. The differences from Embodiment 1 will be described below, and the same matters as in Embodiment 1 will be omitted.

[0053] [2-1. Vehicle Configuration] Figure 5 shows the configuration of vehicle 100B in Embodiment 2. Vehicle 100B is a hybrid vehicle and differs from vehicle 100A in that it is equipped with an internal combustion engine 71. Vehicle 100B also differs from vehicle 100A in that it is equipped with a generator 72 and an AC / DC converter 73. Furthermore, because vehicle 100B is a hybrid vehicle, the configuration of the first battery module 1B that supplies power to the drive motor 52 differs from the first battery module 1A of vehicle 100A.

[0054] Figure 6A shows the configuration of the vehicle ECU 6 in Embodiment 2. The processor 61 of the vehicle ECU 6 in Embodiment 2 differs from the processor 61 of the vehicle 100A in that it includes a startup control unit 610 as a functional unit.

[0055] Figure 6B shows the configuration of the second battery ECU 4 in Embodiment 2. The processor 41 of the second battery ECU 4 in Embodiment 2 differs from the processor 41 of the vehicle 100A in that it further includes an acquisition unit 415 as a functional unit.

[0056] During startup and low-speed operation, the vehicle 100B is driven by the power supplied from the first battery 11B to power the drive motor 52. During high-speed operation, the vehicle 100B is driven by the power of the internal combustion engine 71 to power the drive motor 52. The power of the internal combustion engine 71 is also used to drive the generator 72, and the AC power generated by the generator 72 is converted to a DC voltage by the AC / DC converter 73 and used to charge the first battery 11B. The AC power generated by the generator 72 is also supplied to the DC / DC converter 31, where it is transformed to a voltage suitable for charging the second battery 21.

[0057] The startup control unit 610 permits either a pre-start state or a delayed start state. The pre-start state is a state in which the DC / DC converter 31 is started in advance, before the drive state of the vehicle 100B is switched on, triggered by the user's approach (key unlock, key approach, remote operation, etc.). The delayed start state is a state in which the startup of the DC / DC converter 31, which is a voltage adjustment unit, is delayed until a first predetermined time after the drive state of the vehicle 100B has been switched off. The first predetermined time will be described later. The acquisition unit 415 acquires the diagnosis result of the discharge-side fault diagnosis from the discharge-side fault diagnosis unit 412.

[0058] [2-2. Operation of the Battery Control Device] The processes performed by the vehicle 100B in Embodiment 2 are carried out in accordance with the flowchart in Figure 2, similar to Embodiment 1. However, the process in step S4, which determines whether the vehicle 100B is in a predetermined state, and the process in step S6, which performs discharge-side fault diagnosis, differ from Embodiment 1.

[0059] First, the process of step S4 in Embodiment 2 will be described. In Embodiment 2, "vehicle in a predetermined state" includes a supplemental charging state, a pre-start state, and a start-up extension state. The supplemental charging state is a state in which the second battery is charged by the power supplied by the first battery 11A. The pre-start state and the start-up extension state are as described above. These will be explained below.

[0060] In hybrid vehicles, it is generally preferable to perform fault diagnosis on the discharge side of the second battery 21 while the engine, which is composed of an internal combustion engine 71, is running. This is because the generator 72 can be driven to supply power to the auxiliary equipment 32. However, even when the engine is stopped, if the state of charge (SOC) of the first battery 11B is sufficiently large, it is thought that there will be no problem in turning on the DC / DC converter 31 to supply power to the auxiliary equipment 32. Therefore, it is thought that fault diagnosis on the discharge side can be performed even when the engine is stopped, such as in the "pre-start state" or "supplementary charging state".

[0061] Further, if the SOC of the first battery 11B is sufficiently high at the time when the engine is stopped, it is considered that no problem will occur even if the DC / DC converter 31 is kept on to continue power supply to the auxiliary machinery 32 after the engine is stopped. Accordingly, it is considered possible to extend the activation of the DC / DC converter 31 even after the engine is stopped, that is, to set it in an "extended activation state" and perform discharge-side failure diagnosis during this period.

[0062] These will be described below with reference to FIG. 7. FIG. 7 is a diagram showing the SOC of the first battery 11B. In this example, at time t １ , it is assumed that the IG switch is turned on and the engine is started. It is assumed that before time t １ , the engine is stopped. Before time t １ when the engine is started, the SOC of the first battery 11B gradually decreases due to natural discharge or the like.

[0063] At time t ０ , it is assumed that the vehicle ECU 6 recognizes that the user has approached the vehicle 100B. At this time, since the SOC of the first battery 11B is higher than the engine start SOC, it is considered that no problem will occur even if the activation of the DC / DC converter 31 is permitted. Therefore, for example, from time t ０ to time t Ａ , it is considered possible to perform discharge-side failure diagnosis in the "preliminary activation state". Time t Ａ is a time before time t １ when the engine is started. The period from time t ０ to time t Ａ can be an example of the "first predetermined time".

[0064] At time t １ , when the IG switch is turned on and the engine is started, the generator 72 is driven by the power of the engine as described above, the first battery 11B is charged by the power generated by the generator 72, and the SOC of the first battery 11B increases.

[0065] At time t ２In this scenario, when the State of Charge (SOC) of the first battery 11B reaches the SOC for EV driving, EV driving, i.e., driving based on the power of the first battery 11B, begins. During this time, charging of the first battery 11B continues, but since the power of the first battery 11B is used for the driving motor 52, the SOC of the first battery 11B decreases.

[0066] Time t ３ In the example shown in Figure 7, when the IG switch is turned off and the engine stops, the first battery SOC is much larger than the engine start SOC. Therefore, power can be supplied to the auxiliary equipment 32 even after the IG switch is turned off, and at time t ３ It is considered that there is no problem in performing a discharge-side fault diagnosis thereafter. In such a case, in this embodiment, the startup control unit 610 of the processor 41 can permit the startup extension of the DC / DC converter 31. In the example of Figure 7, for example, at time t ４ I will allow an extension until [date].

[0067] In the example in Figure 7, time t ３ From time t ４ The time until t is the extended startup state, and time t ３ From time t ４ The time up to that point can also be considered an example of the "first predetermined time." The first predetermined time is, for example, one minute.

[0068] It is considered possible to extend the startup extension state further from the first predetermined time described above. For example, power supply from the first battery 11B to the auxiliary equipment 32 can be continued until the SOC of the first battery 11B drops to the engine starting SOC, and the startup extension state can be extended to time t ５ It is also possible to extend it until this time t. ３ From time t ５ The time up to that point can also be considered another example of the "first prescribed time".

[0069] Similarly, it is possible to extend the pre-start state from the first predetermined time mentioned above. For example, the time t when the IG switch is turned on. １ It is thought that this can be extended to that point. Furthermore, it is thought that the pre-start state can be extended until the time when the SOC of the first battery 11B drops to the engine start SOC.

[0070] Next, the process of step S6 in Embodiment 2 will be described. As in Embodiment 1, fault diagnosis on the discharge side is performed by measuring the voltage and current of the second battery 21 during the execution of the discharge control, for example, to determine whether the various discharge controls performed by the second battery control circuit 22 are being carried out normally.

[0071] Furthermore, in Embodiment 2, if the fault diagnosis performed during the extended startup state is unsuccessful, the startup control unit 610 extends the extended startup state to a second predetermined time. That is, when the acquisition unit 415 acquires information indicating that the fault diagnosis by the discharge-side fault diagnosis unit 412 has failed, the startup control unit 610 extends the extended startup state to a second predetermined time, which is longer than the first predetermined time. The information indicating that the fault diagnosis has failed includes, for example, first information indicating that the fault diagnosis itself failed, or second information indicating that the result of the fault diagnosis is abnormal.

[0072] This will be explained again with reference to Figure 7. Here, time t ３ Therefore, the time t when the SOC of the first battery 11B drops to the engine start SOC. ５ The time until t is defined as the "first predetermined time". ３ If the discharge-side fault diagnosis continues thereafter, then, ５ If the fault diagnosis result is still unsuccessful, the startup control unit 610 will set the startup extension permission SOC time t ６ This allows the startup extension of the DC / DC converter 31 until time t. ６ This allows for an extension of the time, enabling a second fault diagnosis and improving the performance of the fault diagnosis. ３ From the above time t ６ The time until is an example of the "second predetermined time". Also, the startup extension permission SOC is an example of the "threshold".

[0073] Similarly, if the fault diagnosis performed during the pre-startup state is unsuccessful, the startup control unit 610 may extend the pre-startup state for a second predetermined time. For example, at time t ＡIf the fault diagnosis result is still unsuccessful, the startup control unit 610 may permit the advance startup of the DC / DC converter 31 until the time when the first battery SOC becomes the advance startup extension permission SOC. Ａ Therefore, the time until the time when the SOC for granting the extension of the pre-startup is reached is also an example of the "second predetermined time." Furthermore, the SOC for granting the extension of the pre-startup is also an example of the "threshold."

[0074] Furthermore, the discharge-side fault diagnosis unit 412 may diagnose that an abnormality has occurred in the second battery 21 if the fault diagnosis result is negative more than a predetermined number of times, or if the fault diagnosis result is not found to be normal within the second predetermined time.

[0075] [2-3. Effects] As described above, according to Embodiment 2 to which the present invention is applied, the predetermined state of the vehicle 100B includes one of the following: a supplemental charging state in which the DC / DC converter 31, which transforms and outputs the electrical energy stored in the first battery 11B, charges the second battery 21 with the transformed electrical energy; a pre-start state in which the DC / DC converter 31 is started in advance before the power source of the vehicle 100B is turned on; or a start-up extension state in which the start-up of the DC / DC converter 31 is extended for a first predetermined time after the power source of the vehicle 100B is turned off. With this configuration, the discharge-side fault diagnosis unit can perform discharge-side fault diagnosis not only during the supplemental charging state but also during the pre-start state and the start-up extension state, thereby increasing the diagnostic timing and improving diagnostic accuracy.

[0076] Furthermore, in the second embodiment, a startup control unit 610 is provided that determines whether to pre-start or extend the startup of the DC / DC converter 31 if the SOC of the first battery 11B is above a threshold. With this configuration, since the possibility of pre-start or extended startup is determined based on the SOC of the first battery 11B, it is possible to prevent the SOC of the first battery from dropping drastically while suppressing interruptions in power supply to auxiliary equipment during discharge-side fault diagnosis.

[0077] Furthermore, in the second embodiment, the threshold is less than or equal to the State of Charge (SOC) of the first battery 11B when the vehicle 100B switches from being driven by the first battery 11B to being driven by the internal combustion engine 71 inside the vehicle 100B. This configuration also helps to suppress interruptions in power supply to auxiliary equipment during discharge-side fault diagnosis.

[0078] Furthermore, in the second embodiment, an acquisition unit 415 is provided to acquire the fault diagnosis result from the discharge-side fault diagnosis unit 412, and the startup control unit 610 extends the startup of the DC / DC converter 31 for a second predetermined time if the fault diagnosis result from the discharge-side fault diagnosis unit 412 is not possible. With this configuration, if the diagnosis by the discharge-side fault diagnosis unit is not possible, the startup of the DC / DC converter is extended further, which allows power supply to the auxiliary equipment to be continued and the fault diagnosis to be continued, thereby improving the accuracy of the fault diagnosis.

[0079] Furthermore, in the second embodiment, the discharge-side fault diagnosis unit 412 diagnoses that an abnormality has occurred in the second battery 21 if the fault diagnosis result by the discharge-side fault diagnosis unit 412 is unacceptable more than a predetermined number of times, or if it does not become acceptable within a second predetermined time. This configuration also improves the diagnostic accuracy. In addition, the criteria for whether the diagnostic result is acceptable or unacceptable can be clarified.

[0080] [3. Other Embodiments] The embodiments described above are merely one aspect of the present invention and can be modified and applied as needed without departing from the spirit of the present invention.

[0081] In the above embodiment, the case in which the discharge-side fault diagnosis unit 412 performs fault diagnosis on the discharge side of the second battery 21 was described. However, the discharge-side fault diagnosis unit 412 may also perform fault diagnosis during the pre-charge of the second battery 21. Here, the reason why it is preferable to perform processing similar to that performed by the discharge-side fault diagnosis unit 412 rather than the charging-side fault diagnosis unit 411 during fault diagnosis during pre-charge will be explained with reference to Figures 3 and 4.

[0082] Pre-charging is the charging performed when a battery recovers from a low state of charge (SOC) due to a jump start or the like. During fault diagnosis during pre-charging, the charge switch 231A and discharge switch 233A are turned off, and a pre-charge switch (not shown) is turned on / off to detect the fault, which interrupts the power supply to the auxiliary equipment 32. Therefore, it is preferable to perform fault diagnosis during pre-charging of the second battery 21 in the same manner as when performing fault diagnosis on the discharge side. That is, it is preferable to perform this when the vehicle is in a predetermined state (step S4: YES).

[0083] In the above embodiment, the second battery 21 is a lithium-ion battery, but other types of batteries, such as lead-acid batteries, may also be used.

[0084] In the above embodiment, an example was described in which a hybrid vehicle 100B is equipped with a start control unit 610, but an electric vehicle 100A may also be equipped with a start control unit.

[0085] Furthermore, in Embodiment 1, an example was described in which the first battery module 1A is equipped with a first battery ECU 14A and the second battery module 2 is equipped with a second battery ECU 4. In other embodiments, these battery ECUs may be integrated, and one battery ECU may control multiple batteries. Similarly, in Embodiment 2, an example was described in which the first battery module 1B is equipped with a first battery ECU 14B and the second battery module 2 is equipped with a second battery ECU 4, but these battery ECUs may be integrated.

[0086] Furthermore, the functional parts of vehicle 100A shown in Figure 1 represent functional configurations, and their specific implementation forms are not particularly limited. Similarly, the functional parts of vehicle 100B shown in Figures 6A and 6B represent functional configurations, and their specific implementation forms are not particularly limited. In other words, it is not necessarily required that hardware corresponding to each functional part be implemented individually, and it is certainly possible to have a configuration in which a single processor executes a program to realize the functions of multiple functional parts. Also, in the above embodiment, some of the functions realized by software may be realized by hardware, or some of the functions realized by software may be realized by software. In addition, the specific detailed configurations of other parts of vehicle 100A and 100B can also be arbitrarily changed without departing from the spirit of the present invention.

[0087] Furthermore, the processing units in the flowchart shown in Figure 2 are divided according to their main processing content in order to facilitate understanding of the processing of the vehicle ECU 6 and the second battery ECU 4. The present invention is not limited by the way the processing units are divided or named as shown in the flowchart in Figure 2. In addition, the processing of the vehicle ECU 6 and the second battery ECU 4 can be further divided into more processing units depending on the processing content, or each processing unit can be divided to include even more processing. Also, the processing order in the flowchart above is not limited to the example shown.

[0088] [4. Configurations Supported by the Above Embodiments] The above embodiments support the following configurations.

[0089] (Configuration 1) A vehicle comprising: a first battery that supplies power to the vehicle's drive motor; a second battery that supplies power to the vehicle's auxiliary equipment; a switching circuit that switches the second battery to a charging state in which it is charged by the power output of the first battery, or to a discharge state in which it discharges the power stored in the second battery; a fault diagnosis unit that performs fault diagnosis of the second battery when the vehicle is in a predetermined state; and a power supply control unit that controls the switching circuit so that power from the first battery is supplied to the auxiliary equipment when the fault diagnosis unit performs fault diagnosis of the second battery. With this configuration, the fault diagnosis unit performs fault diagnosis when the vehicle is in a predetermined state in which power can be supplied from the first battery to the auxiliary equipment, so that initialization of the auxiliary equipment due to interruption of power supply during fault diagnosis by the fault diagnosis unit can be suppressed.

[0090] (Configuration 2) The vehicle according to Configuration 1, wherein the fault diagnosis unit includes a charging-side fault diagnosis unit that detects faults on the charging side of the second battery and a discharge-side fault diagnosis unit that detects faults on the discharge side of the second battery, and the discharge-side fault diagnosis unit performs fault diagnosis of the second battery when the vehicle is in a predetermined state. With this configuration, fault diagnosis of the discharge side is performed when the vehicle is in a predetermined state in which power can be supplied from the first battery to the auxiliary equipment, so in particular, initialization of the auxiliary equipment due to interruption of power supply during discharge-side fault diagnosis can be suppressed.

[0091] (Configuration 3) The vehicle according to Configuration 2, wherein the switching circuit comprises a charge interruption relay for interrupting the charging of the second battery and a discharge interruption relay for interrupting the discharge of the second battery, and the power supply control unit turns off the charge interruption relay when performing fault diagnosis by the charging side fault diagnosis unit, and turns on or off the discharge interruption relay when performing fault diagnosis by the discharge side fault diagnosis unit. With this configuration, charging of the second battery is interrupted when fault diagnosis is performed on the charging side, and discharge of the second battery is interrupted when fault diagnosis is performed on the discharge side, so fault diagnosis of the second battery can be performed with high accuracy.

[0092] (Configuration 4) The vehicle according to Configuration 1, wherein the vehicle is equipped with a voltage conversion unit that transforms the voltage of the power stored in the first battery, and the predetermined state of the vehicle includes at least one of an external power supply state in which the first battery is charged by a power supply device, a supplemental charging state in which the second battery is charged with the power stored in the first battery, a pre-start state in which the voltage conversion unit is started in advance before the power source of the vehicle is turned on, and a start-up extension state in which the start of the voltage conversion unit is extended for a first predetermined time after the power source of the vehicle is turned off. With this configuration, when fault diagnosis is performed by the discharge side fault diagnosis unit, power can be supplied from the first battery to the auxiliary equipment, so that the initialization of the auxiliary equipment due to the interruption of power supply can be suppressed.

[0093] (Configuration 5) The vehicle according to Configuration 4, wherein the vehicle is equipped with a startup control unit that determines whether or not to permit a pre-start state or a startup extension state, and the startup control unit permits the pre-start state or the startup extension state when the charge level of the first battery is above a threshold. With this configuration, since the possibility of a pre-start state or a startup extension state is determined based on the charge level of the first battery, it is possible to prevent the charge level of the first battery from dropping too low while suppressing interruptions in power supply to auxiliary equipment during discharge-side fault diagnosis.

[0094] (Configuration 6) The vehicle according to Configuration 5, wherein the threshold is set to be less than or equal to the starting threshold used to determine whether or not to drive the internal combustion engine of the vehicle. This configuration also helps to suppress interruptions in power supply to auxiliary equipment during discharge-side fault diagnosis.

[0095] (Configuration 7) A vehicle according to Configuration 5, further comprising an acquisition unit for acquiring the fault diagnosis results of the fault diagnosis unit, wherein the startup control unit extends the startup of the voltage adjustment unit for a second predetermined time when the acquisition unit acquires first information indicating that the fault diagnosis has failed, or second information indicating that the result of the fault diagnosis is abnormal. With this configuration, if the fault diagnosis unit fails to diagnose a fault, or if the result of the fault diagnosis is abnormal, the startup of the voltage conversion unit can be extended further, thereby continuing the power supply to the auxiliary equipment and continuing the fault diagnosis, thus improving the accuracy of the fault diagnosis.

[0096] (Configuration 8) The vehicle according to Configuration 7, wherein the fault diagnosis unit diagnoses that an abnormality has occurred in the second battery if the fault diagnosis result is abnormal for a predetermined number of times or if a diagnosis result of no abnormality is not obtained. With this configuration, since it is determined that an abnormality has occurred in the second battery if the diagnosis result is abnormal for a predetermined number of times or if a diagnosis result of no abnormality is not obtained, the criteria for whether the diagnosis result is acceptable or not can be clarified and the diagnostic accuracy can be improved.

[0097] (Configuration 9) The vehicle is the same as in Configuration 2, comprising a voltage conversion unit that transforms the voltage of the power stored in the first battery, and the charging-side fault diagnosis unit performs fault diagnosis when the voltage conversion unit is running. With this configuration, power can be supplied from the first battery to the auxiliary equipment when the charging-side fault diagnosis unit performs a diagnosis, thus suppressing the initialization of the auxiliary equipment due to the interruption of power supply.

[0098] (Configuration 10) A battery control method that causes a computer mounted on a vehicle, which includes a first battery that supplies power to a drive motor and a second battery that supplies power to an auxiliary device, to perform the following steps: to detect whether the vehicle is in a predetermined state; to diagnose a fault in the second battery if the vehicle is in the predetermined state; and to have the first battery supply power to the auxiliary device when the fault diagnosis is performed. This configuration provides the same effects as the vehicle in Configuration 1.

[0099] 1A...First battery module, 1B...First battery module, 2...Second battery module, 4...Battery ECU, 6...Vehicle ECU, 11A...First battery, 11B...First battery, 12A...First battery control circuit, 13A...Battery contactor, 14A...First battery ECU, 21...Second battery, 22...Second battery control circuit, 23...Relay circuit, 31...DC / DC converter, 32...Auxiliary equipment, 33...Brake motor, 41...Processor, 42...Memo 51...Inverter, 52...Traction motor, 71...Internal combustion engine, 72...Generator, 73...AC / DC converter, 100A...Vehicle, 100B...Vehicle, 231...Charge cutoff relay, 231A...Charge switch, 233...Discharge cutoff relay, 233A...Discharge switch, 410...Fault diagnosis unit, 411...Charge side fault diagnosis unit, 412...Discharge side fault diagnosis unit, 413...Power supply control unit, 414...Processing unit, 415...Acquisition unit, 610...Startup control unit, D1...Diode, D2...Diode.

Claims

1. A vehicle comprising: a first battery that supplies power to the vehicle's drive motor; a second battery that supplies power to the vehicle's auxiliary equipment; a switching circuit that switches the second battery to a charging state in which it is charged by the power output of the first battery, or to a discharge state in which it discharges the power stored in the second battery; a fault diagnosis unit that performs fault diagnosis of the second battery when the vehicle is in a predetermined state; and a power supply control unit that controls the switching circuit so that power from the first battery is supplied to the auxiliary equipment when the fault diagnosis unit performs fault diagnosis of the second battery.

2. The vehicle according to claim 1, wherein the fault diagnosis unit includes a charging-side fault diagnosis unit for detecting faults on the charging side of the second battery, and a discharge-side fault diagnosis unit for detecting faults on the discharge side of the second battery, and the discharge-side fault diagnosis unit performs fault diagnosis of the second battery when the vehicle is in a predetermined state.

3. The vehicle according to claim 2, wherein the switching circuit comprises a charge interruption relay for interrupting the charging of the second battery and a discharge interruption relay for interrupting the discharging of the second battery, and the power supply control unit turns off the charge interruption relay when performing fault diagnosis by the charge side fault diagnosis unit, and turns on or off the discharge interruption relay when performing fault diagnosis by the discharge side fault diagnosis unit.

4. The vehicle according to claim 1, wherein the vehicle comprises a voltage conversion unit that transforms the voltage of the power stored in the first battery, and the predetermined state of the vehicle includes at least one of an external power supply state in which the first battery is charged by a power supply device, a supplemental charging state in which the second battery is charged with the power stored in the first battery, a pre-start state in which the voltage conversion unit is started in advance before the power source of the vehicle is turned on, and a start-up extension state in which the start of the voltage conversion unit is extended for a first predetermined time after the power source of the vehicle is turned off.

5. The vehicle according to claim 4, comprising a startup control unit that determines whether or not to permit the pre-start state or the extended start state, wherein the startup control unit permits the pre-start state or the extended start state when the charge level of the first battery is above a threshold.

6. The vehicle according to claim 5, wherein the threshold is set to be less than or equal to a starting threshold for determining whether or not to drive the internal combustion engine provided in the vehicle.

7. The vehicle according to claim 5, further comprising an acquisition unit for acquiring the fault diagnosis results of the fault diagnosis unit, wherein the startup control unit extends the startup of the voltage conversion unit for a second predetermined time when the acquisition unit acquires first information indicating that the fault diagnosis failed, or second information indicating that the fault diagnosis result is abnormal.

8. The vehicle according to claim 7, wherein the fault diagnosis unit diagnoses that an abnormality has occurred in the second battery if the fault diagnosis result is abnormal for a predetermined number of times or more, or if a diagnosis result of no abnormality is not obtained within a second predetermined time.

9. The vehicle according to claim 2, wherein the vehicle is equipped with a voltage conversion unit that transforms the voltage of the power stored in the first battery, and the charging side fault diagnosis unit performs fault diagnosis when the voltage conversion unit is activated.

10. A battery control method that causes a computer mounted on a vehicle, which includes a first battery that supplies power to a drive motor and a second battery that supplies power to an auxiliary device, to perform the following steps: detect whether the vehicle is in a predetermined state; perform a fault diagnosis of the second battery if the vehicle is in the predetermined state; and, when performing the fault diagnosis, have the first battery supply power to the auxiliary device.

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