Charge control device for vehicle

Abstract

This charge control device for a vehicle comprises: one or more processors; and a storage medium on which a program executed by the one or more processors is stored. The program includes one or more instructions. The one or more instructions cause the one or more processors to perform: a process for supplying power from a battery for travel to a battery for auxiliary machinery such that the remaining amount of charge of the battery for auxiliary machinery and a control target value do not deviate from each other during a ready ON state in which the vehicle can travel; and a process for supplying power from the battery for travel to the battery for auxiliary machinery until the remaining amount of charge of the battery for auxiliary machinery reaches an upper-limit threshold during transition from the ready ON state to a ready OFF state in which the vehicle cannot travel. The upper-limit threshold is set at a value that is higher than the control target value.

Description

Vehicle charging control device

[0001] The present invention relates to the technical field of a vehicle charge control device that controls charging of an on-board battery mounted in a vehicle.

[0002] Electric vehicles that can run without using fuel such as gasoline are becoming more common. Electric vehicles are equipped with a large-capacity traction battery used to propel the vehicle in addition to an auxiliary battery. Because the auxiliary battery is used to start the vehicle system, if the remaining charge of the auxiliary battery becomes too low when the vehicle is in the ready-off state, the vehicle may not be able to start and may become unable to run.

[0003] The following Patent Document 1 discloses an invention in which, when the remaining charge of an auxiliary battery becomes low, the remaining charge of the driving battery is used to charge the auxiliary battery. This prevents an excessive decrease in the remaining charge of the auxiliary battery when the vehicle is in the ready-off state, and makes it possible to avoid a state in which the vehicle cannot be driven.

[0004] Japanese Patent Application Laid-Open No. 2006-174619

[0005] However, charging the auxiliary battery while the vehicle is in the ready-off state requires the activation of various components involved in the charging. As the number of times the auxiliary battery is charged increases, the number of times each component must be activated also increases, which can accelerate the deterioration of electronic components to which high voltage is applied.

[0006] The present invention has been made in view of the above circumstances, and has an object to avoid a state in which a vehicle cannot run and to suppress deterioration of each part related to charging.

[0007] A vehicle charging control device according to one embodiment of the present invention comprises one or more processors and a storage medium storing a program executed by the one or more processors, the program including one or more instructions that cause the one or more processors to execute the following processes: a process of supplying power from a driving battery to an auxiliary battery in a ready ON state in which the vehicle can be driven so that there is no discrepancy between the remaining charge of the auxiliary battery and a control target value; and a process of supplying power from the driving battery to the auxiliary battery until the remaining charge of the auxiliary battery reaches an upper limit threshold when transitioning from the ready ON state to a ready OFF state in which the vehicle cannot be driven, the upper limit threshold being a value higher than the control target value.

[0008] According to the present invention, it is possible to avoid a state in which the vehicle cannot run and to suppress deterioration of each part related to charging.

[0009] Fig. 1 is a block diagram showing an example of the configuration of a vehicle; Fig. 2 is a block diagram showing an example of the configuration of a control unit; Fig. 3 is a functional block diagram of a control unit; Fig. 4 is a diagram showing an example of charge control according to the passage of time; and Fig. 5 is a flowchart showing an example of processing executed by the control unit.

[0010] 1 shows an example of the configuration of a vehicle 100. The vehicle 100 includes a control unit 1, an on-board battery 2, a PCU (Power Control Unit) 3, a motor 4, a generator 5, and a connector unit 6.

[0011] 3 shows only a portion of the configuration of the vehicle 100, and the vehicle 100 is appropriately equipped with a map locator, various sensors for driving, communication devices, etc., which are not shown.

[0012] The control unit 1 performs overall control of the vehicle 100. The control unit 1 may be provided as a single unit, or may be configured with multiple ECUs (Electronic Control Units). The multiple ECUs may include, for example, a central ECU 1A that performs overall management and control of the vehicle 100, a high-voltage battery ECU 1B that performs charging control of the high-voltage battery, a display control ECU that performs display control of display devices (including meters, etc.) provided in the vehicle 100, an airbag control ECU, an air conditioning control ECU, and so forth.

[0013] As shown in Fig. 2, the control unit 1 or each of the above-mentioned ECUs includes a CPU (Central Processing Unit) 31, a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a bus 34, an input / output interface 35, an input unit 36, an output unit 37, a storage unit 38, a communication unit 39, and a media drive 40. Note that some of these components may be selectively provided for each ECU as appropriate. In other words, it is not necessary for all ECUs to include all of the components shown in Fig. 2.

[0014] The CPU 31 executes various processes in accordance with programs stored in the ROM 32 or programs loaded from the storage unit 38 into the RAM 33. The RAM 33 also stores data and the like necessary for the CPU 31 to execute various processes.

[0015] The CPU 31, ROM 32, and RAM 33 are interconnected via a bus 34. An input / output interface 35 is also connected to the bus 34.

[0016] The input / output interface 35 is connected to an input unit 36, an output unit 37, a storage unit 38, a communication unit 39, and a media drive 40. Signals are input from the input unit 36 ​​from various sensors connected to the control unit 1, etc. The output unit 37 outputs control information for actuators that drive various parts of the vehicle 100 and are connected to the ECU. Note that the output unit 37 may be configured as a display such as an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence) panel, a speaker, or the like, making it possible to present various types of information to the user.

[0017] The storage unit 38 is configured by a hard disk drive (HDD), a flash memory device, or the like.

[0018] The communication unit 39 performs communication processing for communicating with other ECUs via a Controller Area Network (CAN). The communication unit 39 may also be capable of communicating with a server device or the like via a communication network external to the vehicle 100. Removable media 41 such as a semiconductor memory, a magnetic disk, an optical disk, or a magneto-optical disk is attached to the media drive 40 as needed, and information is written to and read from the removable media 41.

[0019] The central ECU 1A is a control unit that realizes various functions by cooperating with various ECUs and other components. For example, the central ECU 1A issues display instructions to the display control ECU at appropriate times to display desired information to the occupants. The central ECU 1A also cooperates with the airbag control ECU to activate the airbag when a predetermined condition is met, thereby improving the safety of the occupants.

[0020] The control unit 1 controls charging of an in-vehicle battery 2 mounted on the vehicle 100 and manages the state of charge (SOC).

[0021] The vehicle 100 may be equipped with multiple batteries as the on-board battery 2, specifically, a driving battery 2A and an auxiliary battery 2B. The driving battery 2A is the on-board battery 2 with a higher voltage than the auxiliary battery 2B.

[0022] The traction battery 2A is a high-voltage battery of several hundred volts used to drive the vehicle 100. The traction battery 2A supplies power used to drive the wheels and to operate the air conditioning equipment of the vehicle 100. Fig. 1 shows the power supply from the traction battery 2A used to drive the wheels, and does not illustrate the power supply used to operate the other components.

[0023] The high-voltage battery ECU 1B is responsible for managing the driving battery 2A, which has a relatively high voltage, of the in-vehicle battery 2.

[0024] The high-voltage battery ECU 1B is connected to sensors for managing the driving battery 2A, and controls the charging and discharging and temperature of the driving battery 2A based on the detected values ​​from the sensors. Examples of these sensors include a voltage sensor, a current sensor, and a temperature sensor.

[0025] The driving battery 2A is charged based on the DC voltage supplied from the PCU 3. The driving battery 2A supplies the PCU 3 with a power supply voltage for driving the motor 4.

[0026] The PCU 3 is configured to include an inverter, a DC / DC converter, and the like for driving the motor 4. The PCU 3 generates an AC current for driving the motor 4 based on the supplied power supply voltage, and supplies the AC current to the motor 4. The PCU 3 controls the torque of the motor 4 by controlling the AC current. The PCU 3 may also be provided with a regenerative braking function to optimize energy efficiency by utilizing regenerative energy.

[0027] The motor 4 is configured as a motor generator having a power generating function, and drives the wheels based on the supplied AC current.

[0028] The connector unit 6 has a structure that allows insertion of a charging plug provided in charging equipment installed in homes or charging stations. The connector unit 6 outputs AC voltage supplied via the inserted charging plug to the PCU 3. The PCU 3 is equipped with an AC / DC converter and supplies converted DC voltage to the driving battery 2A, thereby charging the driving battery 2A.

[0029] On the other hand, the auxiliary battery 2B is, for example, a 12-volt lithium-ion battery. The auxiliary battery 2B supplies drive power to various auxiliary devices mounted on the vehicle 100. The various auxiliary devices include, for example, various lights, a navigation system, audio equipment, windshield wipers, etc.

[0030] The central ECU 1A is responsible for managing the auxiliary battery 2B, which has a relatively low voltage among the in-vehicle batteries 2, and the like.

[0031] In this embodiment, the central ECU 1A receives information on the SOC from the auxiliary battery 2B, and when the SOC falls below a threshold, starts up various components and controls charging of the auxiliary battery 2B. A generator 5 is used to charge the auxiliary battery 2B.

[0032] The generator 5 includes, for example, a DC / DC converter, and steps down the high voltage supplied from the driving battery 2A and supplies the stepped-down voltage to the auxiliary battery 2B, thereby charging the auxiliary battery 2B. Charging of the auxiliary battery 2B by the generator 5 is performed based on instructions from, for example, the central ECU 1A.

[0033] 2. Functional Configuration The functional configuration of the central ECU 1A is shown in Fig. 3. The central ECU 1A has an SOC monitoring function F1, a charge control function F2, and a startup control function F3.

[0034] The SOC monitoring function F1 receives and manages the SOC from the auxiliary battery 2B, and supplies the SOC of the auxiliary battery 2B to the charge control function F2.

[0035] The charging control function F2 starts or stops charging of the auxiliary battery 2B based on the SOC of the auxiliary battery 2B received from the SOC monitoring function F1. Charging of the auxiliary battery 2B by the charging control function F2 is performed not only in a ready-on state in which the powertrain is activated and the vehicle 100 is ready to run, but also in a ready-off state.

[0036] In the ready-on state, the charge control function F2 controls the charge so that the state of charge (SOC) of the auxiliary battery 2B reaches a control target value Ctv.

[0037] When the charging control function F2 starts charging the auxiliary battery 2B in the ready-off state, the charging control function F2 issues instructions to the start-up control function F3 to start up each unit.

[0038] The start-up control function F3 starts up the high-voltage battery ECU 1B and the driving battery 2A via the high-voltage battery ECU 1B, and also starts up the generator 5, based on instructions from the charge control function F2.

[0039] In response to the start-up control function F3 starting up each part, the charging control function F2 controls the charging of the auxiliary battery 2B using the appropriate voltage obtained by reducing the high voltage from the driving battery 2A using the generator 5.

[0040] The charging control function F2 also stops charging of the auxiliary battery 2B by the driving battery 2A when the remaining charge of the auxiliary battery 2B becomes equal to or greater than a threshold value.

[0041] 3. Example of Charging Control An example of charging control by the central ECU 1A is shown in Figure 4. Figure 4 also shows the change in the SOC of the auxiliary battery 2B over time and the change in the startup state of the powertrain. Specifically, the state shown in Figure 4 is an example in which the state changes over time from a ready-off state in which the vehicle 100 is parked to a ready-on state in which the vehicle 100 is running, and then changes again to the ready-off state after the vehicle 100 is parked.

[0042] The period from time t0 to time t1 is a non-charging period in which the auxiliary battery 2B is not charged, and the period from time t1 to time t2, when the SOC of the auxiliary battery 2B reaches the lower limit threshold Th1, is a charging period in which the auxiliary battery 2B is charged.

[0043] The lower limit threshold Th1 is set to, for example, 30%. That is, when the SOC of the auxiliary battery 2B drops to 30%, charging control by the charging control function F2 is initiated. This makes it possible to avoid a state in which the vehicle 100 becomes unable to run due to an excessive drop in the SOC of the auxiliary battery 2B making it impossible to restart the system of the vehicle 100.

[0044] Time t2 is the timing when the SOC of the auxiliary battery 2B reaches the upper limit threshold value Th2. That is, charging of the auxiliary battery 2B continues until the SOC reaches the upper limit threshold value Th2.

[0045] The upper limit threshold Th2 is set to, for example, 60%. That is, when the SOC of the auxiliary battery 2B increases to 60%, charging by the driving battery 2A is stopped by the charging control function F2.

[0046] The period from time t3 when the SOC reaches the upper limit threshold Th2 to time t4 when the SOC decreases to the lower limit threshold Th1 is again a non-charging period.

[0047] Then, the period from time t3 to time t4 is again a charging period.

[0048] In the example shown in FIG. 4, vehicle 100 starts traveling in a non-charging period that begins at time t4.

[0049] That is, at time t5, the start button of the vehicle 100 is operated or a start operation using a key is performed, and the charging control function F2 controls the SOC to a control target value Ctv that is different from the lower limit threshold Th1 or the upper limit threshold Th2. For example, when the SOC of the auxiliary battery 2B is higher than the control target value Ctv, charging of the auxiliary battery 2B is stopped. Then, when the SOC becomes lower than the control target value Ctv by a certain amount or more due to the supply of power from the auxiliary battery 2B to the accessories, charging is started.

[0050] If the auxiliary battery 2B is configured as a lithium ion battery, managing the SOC at the intermediate SOC while the vehicle 100 is running can delay deterioration of the auxiliary battery 2B. That is, it is desirable that the control target value Ctv be greater than the lower threshold value Th1 and smaller than the upper threshold value Th2. For example, when the lower threshold value Th1 is set to 30% and the upper threshold value Th2 is set to 60%, the control target value Ctv is set to 50%.

[0051] While the vehicle 100 is in the ready ON state, that is, between time t5 and time t6, charging control is performed so that the SOC of the auxiliary battery 2B is maintained near the control target value Ctv.

[0052] Then, charging of the auxiliary battery 2B is not stopped immediately after the vehicle 100 is switched to the ready OFF state at time t6, but is continued up to the upper limit threshold Th2 and then charging of the auxiliary battery 2B is stopped. In other words, the period from time t6 to time t7 is the charging period for the auxiliary battery 2B.

[0053] This allows the SOC of the auxiliary battery 2B to be maintained higher than the lower limit threshold value Th1 until time t9, which is later than time t8 at which the remaining charge drops to the lower limit threshold value Th1 if charging of the auxiliary battery 2B is stopped immediately after the ready OFF state is reached.

[0054] The charging period of auxiliary battery 2B from time t6 to time t7 is a charging period following charge control while vehicle 100 is running, and the components used to charge auxiliary battery 2B remain activated. Therefore, during the charging period from time t6 to time t7, there is no need to control the activation of the components related to charging, and there is no need to switch the high-voltage relay.

[0055] On the other hand, the charging period of the auxiliary battery 2B, which begins at time t9, begins in the ready-off state, with the components used to charge the auxiliary battery 2B not activated. That is, to charge the auxiliary battery 2B, it is necessary to activate the high-voltage battery ECU 1B, the driving battery 2A, and the generator 5. It is also necessary to switch the high-voltage relay.

[0056] It is desirable to reduce the number of times the driving battery 2A is started, as this accelerates the deterioration of electronic components such as the high-voltage relay and capacitor provided in the driving battery 2A.

[0057] As shown in Figure 4, by extending the time from when the vehicle 100 is placed in the ready OFF state until the SOC of the auxiliary battery 2B drops to the lower threshold value Th1, the number of times the driving battery 2A and the like are started can be reduced, thereby extending the lifespan of each part.

[0058] 5 shows an example of processing executed by the central ECU 1A. In step S101, the central ECU 1A determines whether the vehicle 100 is in a ready-on state. If it is determined that the vehicle 100 is in a ready-on state, the central ECU 1A proceeds to step S102, where it controls the charging of the auxiliary battery 2B so that the SOC of the auxiliary battery 2B approaches the control target value Ctv.

[0059] After completing the process of step S102, the central ECU 1A executes the process of step S101 again. That is, while the vehicle 100 is in the ready ON state, the central ECU 1A detects a change in state to ready OFF and controls the charging of the auxiliary battery 2B so that the SOC of the auxiliary battery 2B does not deviate from the control target value Ctv.

[0060] If the ready OFF state is detected in step S101 (step S101: No), for example, if the vehicle 100 transitions to a parked state, the central ECU 1A proceeds to step S103, compares the SOC of the auxiliary battery 2B with the upper threshold value Th2, and performs branching processing according to the result.

[0061] Specifically, if it is determined in step S103 that the SOC of the auxiliary battery 2B is less than the upper limit threshold Th2, the central ECU 1A continues charging the auxiliary battery 2B to increase the SOC. After step S104, the central ECU 1A performs the branching process of step S103 again.

[0062] That is, the central ECU 1A continues charging until the SOC of the auxiliary battery 2B reaches the upper threshold Th2 even immediately after the vehicle 100 has changed from the ready-ON state to the ready-OFF state (steps S103 and S104).

[0063] Then, if it is determined that the SOC of the auxiliary battery 2B has reached the upper threshold value Th2 due to the continued charging control even after the vehicle 100 has entered the ready OFF state (step S103: No), the central ECU 1A proceeds to step S105 and stops charging the auxiliary battery 2B.

[0064] Thereafter, in step S106, the central ECU 1A compares the SOC of the auxiliary battery 2B with the lower threshold value Th1 and performs branching processing depending on the result of the comparison.

[0065] Specifically, the central ECU 1A repeatedly executes step S106 to maintain the charging stopped state until the SOC of the auxiliary battery 2B becomes less than the lower limit threshold value Th1.

[0066] If it is determined in step S106 that the SOC of the auxiliary battery 2B is less than the lower limit threshold Th1 (step S106: Yes), the central ECU 1A proceeds to step S107 and starts charging the auxiliary battery 2B. At this time, the central ECU 1A activates each unit to charge the auxiliary battery 2B using the driving battery 2A as described above.

[0067] After completing the process of step S107, the central ECU 1A returns to step S101 to determine whether the vehicle 100 has transitioned to the ready-ON state. Then, until the vehicle 100 transitions to the ready-ON state, the processes of steps S103 to S107 are repeatedly executed, thereby repeating a charging period and a non-charging period, such as the period from time t0 to time t5 shown in FIG. 4 or the period after time t7.

[0068] 5. Summary The vehicle 100 described above includes the control unit 1 as a vehicle charge control device, specifically, the central ECU 1A and the high-voltage battery ECU 1B.

[0069] The control unit 1 includes one or more processors (CPU 31) and a storage medium (ROM 32, RAM 33, or storage unit 38) storing a program executed by the one or more processors. The program includes one or more instructions that cause the one or more processors to execute at least the following two processes: a process (step S102) for supplying power from the driving battery 2A to the auxiliary battery 2B so that the remaining charge (SOC) of the auxiliary battery 2B does not deviate from the control target value Ctv when the vehicle 100 is in a ready-on state in which the vehicle 100 can travel; and a process (steps S103 and S104) for supplying power from the driving battery 2A to the auxiliary battery 2B until the remaining charge of the auxiliary battery 2B reaches an upper limit threshold Th2 when the vehicle 100 transitions from the ready-on state to a ready-off state in which the vehicle 100 cannot travel. The upper limit threshold Th2 is set to a value higher than the control target value Ctv. As a result, when the vehicle 100 transitions from the ready-on state to the ready-off state, the vehicle 100 can transition to a parked state with the auxiliary battery 2B charged with more power than the power charged to the auxiliary battery 2B through SOC management during driving. Therefore, the time until the power charged to the auxiliary battery 2B is depleted in the parked state can be extended, preventing the vehicle 100 from becoming unable to drive due to an insufficient remaining charge of the auxiliary battery 2B. Furthermore, for example, if the auxiliary battery 2B is an on-board battery 2 that can be extended in life by being used at an intermediate SOC, such as a lithium-ion battery, setting the control target value Ctv to a value lower than the upper threshold value Th2 can extend the time during which the auxiliary battery 2B is used at the intermediate SOC, thereby extending the life of the auxiliary battery 2B. In the above-described configuration, the generator 5 used to charge the auxiliary battery 2B using power from the driving battery 2A is provided external to the PCU 3, but the generator 5 may also be provided inside the PCU 3.

[0070] Furthermore, in the control unit 1 as the vehicle charging control device, specifically, in the central ECU 1A or the high-voltage battery ECU 1B, one or more instructions may cause one or more processors (CPU 31) to execute a process (step S107) of supplying power from the driving battery 2A to the auxiliary battery 2B when the remaining charge (SOC) of the auxiliary battery 2B falls below a lower threshold value Th1 while the vehicle 100 is in the ready-off state. The lower threshold value Th1 may be set to a value lower than the control target value Ctv. By charging the auxiliary battery 2B using power from the driving battery 2A when the SOC of the auxiliary battery 2B falls below the lower threshold value Th1 while the vehicle 100 is in the ready-off state, it is possible to prevent the vehicle 100 from becoming unable to run due to an insufficient remaining charge of the auxiliary battery 2B even in the ready-off state. Furthermore, by setting the control target value Ctv to a value higher than the lower threshold value Th1, that is, by setting the control target value Ctv to a value between the lower threshold value Th1 and the upper threshold value Th2, the auxiliary battery 2B is managed at a more intermediate SOC while the vehicle 100 is running, thereby suppressing deterioration of the auxiliary battery 2B and achieving a longer lifespan.

[0071] Furthermore, it is desirable that the auxiliary battery 2B be a lithium ion battery. By adopting a lithium battery as the auxiliary battery 2B, which is managed at an intermediate SOC compared to a lead-acid battery and thus suppresses deterioration, it is possible to preferably obtain the above-mentioned effects.

[0072] REFERENCE SIGNS LIST 1 Control unit (vehicle charging control device) 1A Central ECU (vehicle charging control device) 1B High-voltage battery ECU (vehicle charging control device) 2A Driving battery 2B Auxiliary battery 31 CPU (processor) 32 ROM (storage medium) 33 RAM (storage medium) 38 Storage unit (storage medium) 100 Vehicle Ctv Control target value Th1 Lower limit threshold Th2 Upper limit threshold

Claims

1. A charging control device for a vehicle, comprising: one or more processors; and a storage medium storing a program executed by the one or more processors, the program including one or more instructions that cause the one or more processors to execute the following processes: a process of supplying power from a driving battery to an auxiliary battery in a ready-on state in which the vehicle can be driven so that there is no discrepancy between the remaining charge of the auxiliary battery and a control target value; and a process of supplying power from the driving battery to the auxiliary battery until the remaining charge of the auxiliary battery reaches an upper limit threshold when the vehicle transitions from the ready-on state to a ready-off state in which the vehicle cannot be driven, wherein the upper limit threshold is set to a value higher than the control target value.

2. The vehicle charging control device according to claim 1, wherein the one or more instructions cause the one or more processors to execute a process of supplying power from the driving battery to the auxiliary battery when the remaining charge of the auxiliary battery falls below a lower limit threshold in the ready-off state, and the lower limit threshold is set to a value lower than the control target value.

3. A vehicle charging control device according to claim 1 or claim 2, wherein the auxiliary battery is a lithium ion battery.

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