Charging control method and charging control device

Abstract

Provided is a charging control method for charging a battery in accordance with a charging command and using power output from a charger, wherein: a battery temperature increase amount during traveling to a destination after completion of charging is estimated; whether the battery is to receive an output restriction during traveling to the destination after completion of charging is determined on the basis of the battery temperature increase amount; and if it is determined that the output restriction is to be received, the charging power is restricted, and the battery temperature at the end of charging is thereby controlled to be a temperature equal to or lower than the temperature at which the output restriction is received even if the battery temperature has increased by the battery temperature increase amount.

Description

Charging control method and charging control device

[0001] The present invention relates to a charge control method and a charge control device.

[0002] JP 5994859B discloses a battery charging control method in which charging is performed at the maximum output of the charger until the battery temperature reaches an upper limit temperature, and thereafter the output of the charger is reduced to charge the battery within a charging time that does not cause discomfort to the user.

[0003] However, in the charging control described in the above document, the battery temperature may reach the upper limit temperature when charging is completed. Therefore, for example, when rapid charging is performed at a service area while driving to a destination, output restrictions due to the battery temperature may be imposed during driving after charging is completed, and the driving performance desired by the user may not be achieved.

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide charging control that enables a vehicle to travel to a destination after charging is completed without being subject to output limitations caused by battery temperature.

[0005] According to one aspect of the present invention, there is provided a charge control method for charging a battery with output power from a charger in response to a charge command. This method estimates the amount of battery temperature rise during driving to a destination after charging is completed, and determines whether the battery will be subject to output limitation during driving to the destination after charging is completed based on the amount of battery temperature rise. If it is determined that the battery will be subject to output limitation, the charging power is limited so that the battery temperature at the end of charging is controlled to a temperature that will be below the temperature at which the battery temperature rises by the amount of battery temperature rise and will not be subject to output limitation.

[0006] FIG. 1 is a block diagram of a charging system. FIG. 2 is a time chart of battery output and battery temperature when rapid charging using upper limit output charge control is performed and driving is started immediately after charging is completed. FIG. 3 is a time chart of vehicle speed after driving is started after charging is completed. FIG. 4 is a flowchart showing a control routine for charge control according to this embodiment. FIG. 5 is an example of a time chart of battery output when driving to a destination after charging is completed. FIG. 6 is an example of a time chart of battery temperature when driving to a destination after charging is completed. FIG. 7 is a diagram showing the relationship between battery temperature and battery output. FIG. 8 is a time chart of charging power when charge control according to this embodiment is executed. FIG. 9 is a time chart of battery temperature when charge control according to this embodiment is executed. FIG. 10 is a diagram showing the relationship between battery temperature and battery output. FIG. 11 is a time chart of battery output for explaining the effects of this embodiment. FIG. 12 is a time chart of vehicle speed for explaining the effects of this embodiment. FIG. 13 is a flowchart showing a control routine for generating a charge start command.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] 1 is a block diagram of a charging system that executes charging control according to an embodiment of the present invention. This charging system is used, for example, to charge a battery mounted on an electric vehicle.

[0009] The charging system includes a charger 10, a battery 20, and a controller 50. Of these, the battery 20 and the controller 50 are mounted on a vehicle. In addition to the battery 20, the vehicle also includes a navigation system 30, a motor (not shown), and other components.

[0010] The charger 10 is a charger that charges the battery 20 and is provided outside the vehicle. The charger 10 is a so-called quick charger and has a charging circuit that converts power input from an AC power source 100 into DC and outputs the DC power to the battery 20. The charger 10 has an inverter, a DC / DC converter, a controller, etc. The charger 10 is connected to the battery 20 by a cable, etc.

[0011] The battery 20 is a power source for the vehicle, and is configured by connecting multiple secondary batteries such as lithium ion batteries. The battery 20 is connected to a motor (not shown) via an inverter (not shown). The battery 20 is charged by regeneration from the motor and also by a charger 10 external to the vehicle.

[0012] The controller 50 measures the SOC and the like of the battery 20 based on the detected values ​​of voltage and current sensors connected to the battery 20 and a sensor that detects the temperature of the battery 20, and manages the state of the battery 20, such as the battery capacity charged in the battery 20. The controller 50 also transmits and receives control signals to and from the charger 10, and controls the charger 10 to control the charging of the battery 20. Furthermore, the controller 50 receives information from the navigation system 30, such as a destination point set by the driver, a driving route to the destination point, and the speed limit and road gradient of the driving route, and performs charging control, which will be described later.

[0013] The controller 50 has a current detection unit 51, a voltage detection unit 52, a temperature detection unit 53, an SOC calculation unit 54, a chargeable power calculation unit 55, a charge time calculation unit 56, an allowable charge time calculation unit 57, a limited generated power calculation unit 58, and a command value calculation unit 59. The controller 50 also has a required power estimation unit 60, a temperature rise estimation unit 61, an upper limit temperature reach determination unit 62, and an reachability determination unit 63, which will be described later.

[0014] The current detection unit 51 is a sensor connected to the battery 20 and detects the current of the battery 20. The detection value of the current detection unit 51 is output to the SOC calculation unit 54, the chargeable power calculation unit 55, and the charging time calculation unit 56.

[0015] The voltage detection unit 52 is a sensor connected to the battery 20 and detects the voltage of the battery 20. The voltage detection unit 52 detects the voltage of each of the plurality of cells included in the battery 20 and the total voltage of the plurality of cells. The detection value of the voltage detection unit 52 is output to the chargeable power calculation unit 55 and the charging time calculation unit 56.

[0016] The temperature detection unit 53 is a sensor provided in the battery 20 and detects the temperature of the battery 20. The detected value of the temperature detection unit 53 is output to the chargeable power calculation unit 55, the charging time calculation unit 56, and the allowable charging time calculation unit 57.

[0017] The SOC calculation unit 54 integrates the charging current by accumulating the detection value detected by the current detection unit 51, and calculates the SOC of the battery 20. The SOC calculation unit 54 outputs the calculated SOC to the charging time calculation unit 56 and the allowable charging time calculation unit 57.

[0018] Note that SOC calculation unit 54 may calculate the SOC of battery 20 from the voltage detected by voltage detection unit 52. Because there is a correlation between the voltage and SOC of battery 20, a map showing this correlation is recorded in memory (not shown), and SOC calculation unit 54 refers to the map in the memory and calculates the SOC corresponding to the voltage detected by voltage detection unit 52 as the SOC of battery 20.

[0019] Note that the correlation between the voltage and SOC of battery 20 changes depending on the degree of deterioration of battery 20, and therefore the map may be a map according to the degree of deterioration of battery 20. The degree of deterioration of battery 20 may be calculated, for example, from the internal resistance of battery 20. Furthermore, the internal resistance of battery 20 may be calculated using, for example, a change in the current value detected by current detection unit 51 and a change in the voltage detected by voltage detection unit 52.

[0020] The chargeable power calculation unit 55 calculates the chargeable power of the battery 20 from the detected current of the current detection unit 51, the detected voltage of the voltage detection unit 52, and the detected temperature of the temperature detection unit 53. The chargeable power is the maximum power that can be charged while suppressing the acceleration of deterioration of the battery 20 when charging the battery 20, and is the maximum input power that can be input from the charger 10 to the battery 20. Note that the chargeable power is generally also referred to as the inputtable power, maximum chargeable power, or maximum inputtable power, and will be referred to as the chargeable power in this embodiment. The chargeable power calculation unit 55 calculates the chargeable power in the following manner.

[0021] An upper charge voltage limit is set for each cell of the battery 20 according to the performance of the battery 20. The upper charge voltage limit is the upper limit voltage when charging the battery 20 in order to prevent deterioration of the battery 20. The upper charge voltage limit is set to the voltage at which lithium deposition starts inside the cells (cells) that make up the battery 20, or to a voltage lower than the voltage at which lithium deposition starts.

[0022] The upper limit charging voltage is calculated according to the charging current input to the battery 20, the battery temperature, and the internal resistance of the battery 20. For example, the upper limit charging voltage is calculated to be lower as the charging current of the battery 20 increases, and higher as the charging current of the battery 20 decreases.

[0023] If the battery 20 is made up of multiple cells, the voltage of the cell with the highest voltage among the multiple cells must be limited to the upper charging voltage limit. The chargeable power calculation unit 55 identifies the cell with the highest voltage from the voltages of each cell detected by the voltage detection unit 52.

[0024] The chargeable power calculation unit 55 calculates the current that can be input to the battery 20 based on the voltage of the identified cell, the internal resistance of the cell, the charging current of the cell, and the upper limit charging voltage.

[0025] The allowable input current is calculated from the internal resistance of the cell with the highest terminal voltage and the upper limit charging voltage of that cell. The internal resistance of a cell is calculated from the terminal voltage of that cell detected by the voltage detection unit 52 and the charging current of that cell. Known methods can be used to calculate the allowable input current and the internal resistance of the cell.

[0026] The charging time calculation unit 56 calculates the charging time based on a map showing the correspondence between the state of the battery 20, the charging time of the battery 20, and the charging power of the battery 20. The charging time calculation unit 56 also uses the map to calculate the characteristics of the charging power of the battery relative to the charging time of the battery 20, and outputs the results to the limited charging power calculation unit 58. The charging time calculation unit 56 calculates the charging time based on the temperature of the battery 20 as an index showing the state of the battery 20. The charging power of the battery 20 indicates the power actually supplied to the battery 20 during charging, and is a value calculated from the detected current of the current detection unit 51 and the detected voltage of the voltage detection unit 52.

[0027] The allowable charging time calculation unit 57 calculates the allowable charging time for the battery and outputs it to the limited charging power calculation unit 58. The allowable charging time is a charging time that is allowable by the user and is set in advance. If the charging time is extremely long, it is inconvenient for the user to have to wait until the charging time has elapsed. Therefore, in this example, in consideration of user convenience, the charging time allowable by the user is determined in advance through experiments, etc., and set, and is recorded in the allowable charging time calculation unit 57. In this example, the user can also set the charging time via an interface in the vehicle cabin.

[0028] The limited charging power calculation unit 58 calculates the charging power for charging the battery 20 in the allowable charging time as limited charging power based on the characteristics of the charging power of the battery relative to the charging time of the battery 20 calculated by the charging time calculation unit 56 and the allowable charging time calculated by the allowable charging time calculation unit 58, and outputs the limited charging power to the command value calculation unit 59. The limited charging power indicates the limit power of the charging power actually supplied to the battery 20 when charging the battery 20 in the allowable charging time.

[0029] The command value calculation unit 59 calculates a command value for the power output from the charger 10 based on the chargeable power of the battery 20 calculated by the chargeable power calculation unit 55 and the outputtable power of the charger 10. The command value calculation unit 59 also calculates a command value for the power output from the charger 10 so that the charging power of the battery 20 becomes the limited charging power calculated by the limited charging power calculation unit 58.

[0030] The output power of the charger 10 indicates the maximum output power that can be output from the charger 10 and corresponds to the rated power of the charger 10. In other words, the output power is a value that is preset according to the capacity of the charger 10, and the output power of the charger 10 is limited to or below this output power. There are two types of chargers 10: quick chargers, which have a high output power capacity, and normal chargers, which have a lower output power capacity than quick chargers. When the controller 50 confirms the connection between the charger 10 and the battery 20 via a cable or the like, it receives a signal transmitted from the charger 10 and obtains the output power capacity of the charger 10.

[0031] The command value calculation unit 59 transmits the calculated command value for output power to the charger 10 and a reachability determination unit 63, which will be described later. The charger 10 converts the power of the AC power supply 100 into DC so as to output the power of the command value transmitted by the command value calculation unit 59, and supplies it to the battery 20. As a result, the charger 10 is controlled based on the command value of the command value calculation unit 59, and the battery 20 is charged.

[0032] In order to increase the battery capacity of the battery 20 as quickly as possible, it is desirable to charge the battery at the rated power of the charger 10 until the battery temperature reaches the upper limit temperature, and then charge at the chargeable power after the upper limit temperature is reached, thereby suppressing the increase in battery temperature. Hereinafter, this control is also referred to as upper limit output charge control. Note that the upper limit temperature (hereinafter also referred to as the battery upper limit temperature) here refers to the temperature at which the output of the battery 20 is limited.

[0033] However, if upper limit output charge control is performed when the vehicle resumes driving after charging is completed, such as during rapid charging at a service area, the output of the battery 20 is limited by the upper limit temperature, which may prevent the vehicle from driving at the desired speed. This will be explained with reference to Figures 2 and 3.

[0034] Figure 2 shows a time chart of battery output and battery temperature when rapid charging is performed using upper limit output charge control and driving is started immediately after charging is completed. In the figure, the solid line indicates the target battery output, the dashed line indicates the actual battery output, and the dashed line indicates the battery temperature.

[0035] 2 shows a case where rapid charging is performed from time 0 to time T2, rapid charging ends at time T2, driving begins, and the vehicle arrives at the destination at time T4. Note that the destination here refers to the final destination set by the user in the navigation system.

[0036] The target output during charging is set to the maximum value, but when the battery temperature reaches the upper limit at time T1, it is restricted and reduced. This prevents the battery temperature from rising. When the vehicle starts to travel at time T2, it can travel at the target output until time T3, but when the battery temperature reaches the upper limit again at time T3, the output is restricted and becomes lower than the target output.

[0037] 3 is a time chart of the vehicle speed after starting to travel. The solid line in the figure represents the target vehicle speed, and the dashed line represents the actual vehicle speed. Timings T2 to T4 in the figure correspond to those in FIG. 2.

[0038] From time T2 to time T3, the vehicle travels at the target vehicle speed. This is because the battery output is not limited as described above. However, after time T3, the battery output is limited, so the vehicle speed becomes slower than the target vehicle speed. As a result, the vehicle reaches the destination later than time T4.

[0039] In order to solve the above problem of not being able to travel at the target vehicle speed due to limitations on battery output, in this embodiment, the following charge control is performed.

[0040] In the charging control of this embodiment, first, the amount of battery temperature rise during driving to the destination after charging is completed is estimated, and based on the amount of battery temperature rise, it is determined whether the battery temperature will rise to the battery upper limit temperature, which is the temperature at which the battery is subject to output restrictions during driving to the destination. In this determination, the battery temperature after charging is considered to be the temperature at the end of charging if upper limit output charging control is performed. Then, if it is determined that the battery temperature will rise to the battery upper limit temperature, the charging power is limited so that the battery temperature at the end of charging is controlled to a temperature below the temperature at which the battery is subject to output restrictions even if the battery temperature rises by the amount of battery temperature rise. If it is determined that the battery temperature will not rise to the battery upper limit temperature, upper limit output charging control is performed.

[0041] 4 is a flowchart showing a control routine for charge control according to this embodiment. This control routine is executed when a charge start command, which will be described later, is received.

[0042] In step S100, the controller 50 performs a calculation to predict the amount of heat energy generated in the battery 20 while driving after charging. Specifically, information about the driving route to the destination, such as the driving distance, speed limit, and road gradient, is obtained from the navigation system 30, and based on this information, the power required for driving is estimated, and the heat energy generated by outputting this power is predicted. This prediction calculation is performed by the required power estimation unit 60. Figure 5 is an example of a time chart of the battery output when driving to the destination. The power required to drive to the destination is calculated by integrating this battery output over the time from the start of driving to arriving at the destination.

[0043] In step S110, the controller 50 predicts the amount of battery temperature rise during driving, assuming that upper limit output charge control has been performed. Specifically, the temperature rise estimation unit 61 predicts the amount of temperature rise of the battery 20 based on the thermal energy. This prediction is performed by the temperature rise estimation unit 61. Note that the prediction may take into account factors such as the outside air temperature. Figure 6 is a time chart of the battery temperature when driving with the output pattern shown in Figure 5 after the end of upper limit output charge control. The battery temperature gradually rises from the start of driving.

[0044] In step S120, the controller 50 determines whether the battery 20 is subject to output limitation. If so, the process of step S130 is executed, and if not, the process of step S160 is executed. This determination is made by the rising temperature reaching determination unit 62. Figure 7 is a diagram showing the relationship between battery temperature and battery output. The solid line in the diagram is a limit line indicating the maximum output after output limitation. In the diagram, P1 indicates the maximum output of the battery 2, and BT1 indicates the battery upper limit temperature.

[0045] As shown in Figure 7, when the battery temperature is below BT1, the limit line is P1, which is the maximum output. In other words, there is no output limit. When the battery temperature is above BT1, the higher the battery temperature, the lower the battery output limit becomes. The rising temperature reach determination unit 62 determines that the output limit will be applied if the battery output exceeds the limit line during driving after the end of quick charging.

[0046] In step S130, the controller 50 resets the upper limit of the battery temperature at the end of charging. Here, the upper limit is reset to a temperature calculated backward from the battery temperature at which output is not limited. In other words, the "temperature during driving" in FIG. 7 is shifted parallel to the limit line, and the amount of battery temperature rise is subtracted from this to determine the reset upper limit temperature. Note that the temperature may be shifted parallel to a lower temperature than the limit line to more reliably avoid output limitations.

[0047] In step S140, the controller 50 calculates the limited charging power based on the battery temperature set in step S130.

[0048] After setting the limited charging power, the controller 50 detects the current and voltage of the battery 20 (step S150) and controls the charging power (step S170). On the other hand, if the output is not limited, the controller 50 starts upper limit output charging control (step S160).

[0049] The controller 50 repeats the processing of steps S150-S170 until it determines in step S180 that charging has ended, and when charging has ended, it outputs a charge end command in step S 190. The processing of steps S130-S190 is performed by the limited charging power calculation unit 58.

[0050] 8 is a time chart of the charging power when the above control routine is executed. If it is estimated that there will be no output limitation during driving after charging is completed, upper limit output charging control is performed, as indicated by the thick arrow in the figure. On the other hand, if it is estimated that there will be output limitation during driving after charging is completed, charging is performed using the limited charging power calculated in step S140, i.e., charging power that is lower than the rated output of the charger 10, as indicated by the dashed line in the figure. As a result, the battery temperature at the end of charging is lower than when upper limit output charging control is performed, and it is possible to avoid the battery 20 being subject to output limitation even if the battery temperature rises during driving after charging is completed.

[0051] 9 is a time chart of the battery temperature when the above control is executed. The solid line in the figure shows the case where the upper limit temperature is reset according to this embodiment, and the dashed line shows the case where the upper limit output charge control is executed.

[0052] As shown in the figure, when the upper limit temperature is reset, the battery temperature rises more slowly than when upper limit output charge control is performed, and the battery temperature at the end of charging (time T2) is lower. Therefore, after time T2, i.e., while driving, the battery temperature is also lower than when upper limit output charge control is performed.

[0053] 10 is a diagram showing the relationship between battery temperature and battery output, similar to FIG. 7. The solid line in the diagram is a limit line showing the maximum output after output limiting. The white circles in the diagram indicate the case where the upper limit temperature is reset according to this embodiment, and the black circles indicate the case where upper limit output charging control is performed.

[0054] When upper limit output charge control is performed, the battery temperature at the end of charging is BT1, and if the vehicle is driven from that state, the battery temperature will exceed the limit line while driving. In contrast, if the battery temperature at the time of charging is lowered to BT2 by resetting the upper limit temperature, the battery temperature will not exceed the limit line while driving, even if the battery temperature rises by the same amount. The effect of this will be explained with reference to Figures 11 and 12.

[0055] Figure 11 is a time chart of battery output. Figure 12 is a time chart of vehicle speed. In both figures, the solid lines indicate the case where the upper limit temperature is reset using the charging control according to this embodiment, and the dashed lines indicate the case where upper limit output charging control is performed as a comparative example. The timings T1-T4 are the same as those in Figures 2 and 3.

[0056] According to the charging control of this embodiment, the battery output is lower up to time T1 than under upper-limit output charging control, but a constant battery output is maintained after time T1. In contrast, under upper-limit output charging control, the battery output decreases due to output limitations after time T1. Under upper-limit output charging control, the battery output decreases due to output limitations from time T3, and the vehicle speed also decreases accordingly. However, under the charging control of this embodiment, the battery output can be kept at the target battery output described in FIG. 2 without being subject to output limitations, and as a result, the vehicle speed can also be kept at the target vehicle speed.

[0057] 11 and 12 show the results of a simulation assuming that the route after charging ends includes a steep uphill road, with the steep gradient section occurring after time T3. This simulation shows that the average vehicle speed Vave1 in the case of charging control according to this embodiment in the section from time T3 until deceleration begins near the destination is about 20% higher than the average vehicle speed Vave2 in the case of upper limit output charging control in the same section.

[0058] However, there may be cases where the battery capacity cannot be charged within the specified charging time to reach the destination. For example, this may occur when the user sets a short charging time (e.g., about 15 minutes) even though the destination is several hundred kilometers away. In such a case, if charging is completed within the set charging time, the user may realize that the battery capacity is insufficient while driving after charging is completed, and then have to search for a charging facility. Therefore, in this embodiment, before starting charging, the controller 50 determines whether the destination can be reached with the battery capacity to be charged. If it is determined that the destination can be reached, charging is performed for the set or specified charging time. On the other hand, if it is determined that the destination cannot be reached, the controller 50 identifies the nearest charging facility between the current location and the destination, calculates the battery capacity required to reach the destination, and sets the charging time required to charge the battery capacity. A specific example of this control will be described with reference to FIG. 9.

[0059] FIG. 13 is a flowchart showing a control routine for generating a charge start command that serves as a trigger for starting the control routine of FIG.

[0060] In step S200, the controller 50 predicts and calculates the drive load to the destination. Specifically, the controller 50 obtains information about the driving route to the destination, such as the remaining distance, the estimated vehicle speed, and the road gradient, from the navigation system 30, and calculates the drive load to reach the destination based on this information. The estimated vehicle speed can be the vehicle speed limit. However, if data such as the past average vehicle speed on the driving route to the destination is available, the average vehicle speed may be used instead of the vehicle speed limit.

[0061] In step S210, the controller 50 calculates the battery capacity required to reach the destination based on the driving load.

[0062] In step S220, the controller 50 calculates the charging time. Basically, the calculation is the same as that of the charging time calculation unit 56 described above, but if the user has set the charging time, that time is read.

[0063] In step S230, controller 50 determines whether the destination can be reached with the battery capacity calculated in step S210, and if it can be reached, executes the process of step S250, and if it cannot be reached, executes the process of step S240. The determination of whether the destination can be reached is made, for example, by comparing the battery capacity required to reach the destination calculated in step S210 with the battery capacity that can be charged in the charging time calculated in step S220, and determining that the destination cannot be reached if the former is greater, and that the destination can be reached if the latter is greater.

[0064] The processes from step S200 to step S230 are performed by the reachability determination unit 63.

[0065] In step S240, the controller 50 identifies the nearest charging facility between the current location and the destination, and calculates the battery capacity and charging time required to reach the nearest charging facility. This process is performed by the limited charging power calculation unit 58.

[0066] In step S250, controller 50 outputs a command to start charging according to the determination result in step S230. Specifically, if the destination can be reached, controller 50 outputs a command to control charging using the upper limit output from limited charging power calculation unit 58 to command value calculation unit 59. If the destination cannot be reached, controller 50 outputs a command to charge the battery capacity calculated in step S240.

[0067] As described above, if the battery capacity required to reach the destination can be charged by charging within the allowable charging time or the charging time set by the user, charging control is performed according to the control routine described in FIG. 4 . On the other hand, if the battery capacity required to reach the destination cannot be charged by the charging, the battery capacity required to reach the nearest charging facility between the current location and the destination is calculated, and the battery capacity is charged. The charging time required to charge the battery capacity may be longer than the charging time set by the user. In this case, the battery capacity can be charged to a level sufficient to travel at least to the nearest charging facility. In this case, it is desirable to notify the user that the time remaining until charging will be longer than the set charging time. For example, a system is known that notifies the user of the charging completion time and the remaining time until charging is completed via a mobile device (e.g., a smartphone) linked to the charging system. This system can be used to notify the user that the charging time will be longer than the time set by the user.

[0068] As described above, this embodiment provides a charge control method for charging a battery with output power from a charger in response to a charge command. In this charge control method, the controller 50 estimates the amount of battery temperature rise during driving to the destination after charging is completed, and determines whether the battery will be subject to output limitations during driving to the destination after charging is completed based on the amount of battery temperature rise. If it determines that output limitations will be applied, the controller 50 limits the charging power so that the battery temperature at the end of charging is below the temperature at which output limitations will be applied even if the battery temperature rises by the amount of battery temperature rise. This allows the vehicle to drive to the destination after charging is completed without being subject to output limitations due to battery temperature.

[0069] In this embodiment, battery cooling may be started at the same time as the start of charging. This can suppress the rise in battery temperature during charging, so the limited charging power when the battery temperature at the end of charging is reset can be made larger than when battery cooling is not performed. In other words, the chargeable battery capacity can be made larger when the battery temperature at the end of charging is reset.

[0070] In this embodiment, the controller 50 estimates the amount of battery temperature rise based on at least the expected vehicle speed and road gradient information to the destination obtained from the navigation system, thereby enabling the amount of battery temperature rise to be estimated with high accuracy.

[0071] In this embodiment, the controller 50 estimates the charge capacity required to travel to the destination based on the expected vehicle speed to the destination and road gradient information obtained from the navigation system, and determines whether the vehicle can travel to the destination in a fully charged state or, if the user has specified a charging time, in a charged state after the specified time has elapsed. If the controller 50 determines that the vehicle cannot travel to the destination, it estimates the charge capacity required to travel to the nearest charging facility on the travel route to the destination and generates a charge command to charge the vehicle until the charge capacity reaches that estimated capacity. This makes it possible to travel at least to the nearest charging facility.

[0072] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A charge control method for charging a battery using output power from a charger in response to a charge command, comprising: estimating the amount of battery temperature rise during driving to the destination after charging is completed; determining based on said amount of battery temperature rise whether or not the battery will be subject to output restriction during driving to the destination after charging is completed; and if it is determined that the battery will be subject to output restriction, limiting the charging power so that the battery temperature at the end of charging will be below the temperature at which the battery will be subject to output restriction even if the battery temperature rises by said amount of battery temperature rise.

2. A charging control method according to claim 1, wherein battery cooling is initiated simultaneously with the start of charging.

3. A charge control method according to claim 1, wherein the amount of battery temperature rise is estimated based on at least information on the expected vehicle speed and road gradient to the destination obtained from a navigation system.

4. A charge control method as claimed in claim 1, which estimates the charge capacity required for travel to the destination based on the expected vehicle speed and road gradient information to the destination obtained from a navigation system, determines whether or not it is possible to travel to the destination in a fully charged state, or in a charged state after the specified time has elapsed if the user has specified a charging time, and if it is determined that it is not possible to travel to the destination, estimates the charge capacity available for travel to the nearest charging facility on the travel route to the destination, and generates the charge command to charge until the charge capacity is reached.

5. A charge control device that charges a battery with output power from a charger in response to a charge command, comprising: a temperature rise estimation unit that estimates the amount of battery temperature rise during driving to a destination after charging is completed; an upper limit temperature arrival determination unit that determines, based on the amount of battery temperature rise, whether the battery temperature will rise to an upper limit battery temperature, which is the temperature at which the battery is subject to output restriction during driving to the destination; and a charge power limiting unit that, if it is determined that the battery temperature will rise to the upper limit battery temperature, limits the charging power to an amount that will keep the battery temperature at the end of charging below the temperature at which the battery is subject to output restriction even if the battery temperature rises by the amount of battery temperature rise.

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