Charging device

Abstract

To suppress deterioration of an on-vehicle battery.SOLUTION: A charging device 10 comprises: a charge inlet 40 that is provided at a vehicle 12 and can be connected to a charge connector 32 outside the vehicle; and a charge control part 46 that performs charging of an on-vehicle battery 20 by power supplied from the outside of the vehicle via the charge inlet 40. The charge control part 46 limits a charging current so as to slow down a change amount of a reduction of a charging time with an increase in number of execution times of the charging. Thus, a heat generation amount of the on-vehicle battery 20 can be suppressed, and deterioration of the on-vehicle battery 20 can be suppressed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a charging device for an in-vehicle battery. [Background technology]

[0002] For example, Patent Document 1 discloses an example of a technique for charging an on-board battery with power supplied to a vehicle from outside the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-135148 A Summary of the Invention [Problem to be solved by the invention]

[0004] Lithium-ion batteries, one example of in-vehicle batteries, have the tendency to deteriorate when placed in a high-temperature environment. As this type of in-vehicle battery deteriorates, its internal resistance increases. This can cause the in-vehicle battery itself to become hot due to the increase in heat generated by the internal resistance, accelerating the deterioration of the in-vehicle battery.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a charging device capable of suppressing deterioration of an in-vehicle battery. [Means for solving the problem]

[0006] In order to solve the above problems, the charging device of the present invention is provided in a vehicle, and includes a charging inlet that can be connected to a charging connector outside the vehicle, and charges an on-board battery with power supplied from outside the vehicle through the charging inlet. and limiting the charging current so as to slow down the rate of change in the reduction in charging time with an increase in the number of charging runs. A charging control unit, A full charge time for the SOC of the vehicle battery to reach 100% is calculated using the ultimate charge capacity reached by charging, the full charge capacity calculated from the relationship between the SOC of the vehicle battery and the ultimate charge capacity, and the charging time. When the difference between a first full charge capacity, which is the full charge capacity at the previous charging, and a second full charge capacity, which is the full charge capacity at the current charging, becomes equal to or greater than a predetermined value, it is determined that the deterioration of the vehicle battery has progressed. A limit value of the charging current is calculated according to a reduction rate of the full charge time calculated from the ratio between the first full charge time, which is the full charge time calculated at the previous charging, and the second full charge time, which is the full charge time calculated at the current charging. The charging current is limited to the limit value at the next charging. .

[0007] Furthermore, when charging, the charge control unit may limit the charging current so that the current charging time is equal to the charging time of the previous charging.

[0008] The reached charge capacity indicates the amount of charge when charging is actually completed, based on the amount of charge when the SOC of the vehicle battery is 0%, and the time required to charge the reached charge capacity is the plug-in charge time. The charging control unit may derive the full charge time required to charge the full charge capacity each time charging is performed, and derive the second full charge time by multiplying the result obtained by dividing the second full charge capacity by the current reached charge capacity by the current plug-in charge time. Effect of the Invention

[0009] According to the present invention, it is possible to suppress deterioration of an in-vehicle battery. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a charging system according to this embodiment. [Diagram 2] FIG. 2 is a diagram for explaining an outline of the operation of the charging control unit. FIG. 2A shows the charging capacity of an initial vehicle battery that is hardly degraded. FIG. 2B shows the charging capacity of a vehicle battery that has deteriorated compared to FIG. 2A. FIG. 2C shows an example in which the charging current is limited. FIG. 2D shows another example in which the charging current is limited. [Diagram 3] Fig. 3 is a diagram showing an example of the time transition of SOC during and after charging. Fig. 3A shows an initial vehicle battery with almost no deterioration. Fig. 3B shows an vehicle battery that has deteriorated compared to Fig. 3A. Fig. 3C shows a case where the charging current is limited by the charging control unit. [Figure 4] FIG. 4 is a diagram for explaining the definition of elements related to the derivation of the limit value of the charging current. [Diagram 5] FIG. 5 is a flowchart illustrating the flow of operations of the charging control unit. [Figure 6] FIG. 6 is a flowchart illustrating the flow of the termination process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.

[0012] 1 is a schematic diagram showing the configuration of a charging system 1 according to this embodiment. The charging system 1 includes a vehicle 12 to which a charging device 10 is applied, and a power supply facility 14 outside the vehicle.

[0013] The vehicle 12 is, for example, an electric vehicle or a hybrid vehicle. The vehicle 12 is provided with an on-board battery 20. The on-board battery 20 is, for example, a lithium-ion battery. The on-board battery 20 supplies power to a motor (not shown) that is a drive source of the vehicle 12. The charging device 10, which will be described in detail later, can be electrically connected to a power supply facility 14, and charges the on-board battery 20 with power supplied from the power supply facility 14. That is, the charging device 10 can perform so-called plug-in charging.

[0014] The power supply equipment 14 includes a power supply unit 30, a charging connector 32, and an equipment control unit 34. The power supply unit 30 is connected to a power supply source 36. The power supply source 36 is, for example, a commercial power system. The charging connector 32 is connected to the power supply unit 30 through a cable 38. The charging connector 32 can be electrically connected to the charging device 10 of the vehicle 12. The power supply unit 30 converts AC power supplied from the power supply source 36 into DC power and supplies the DC power to the charging device 10 of the vehicle 12 through the charging connector 32. Note that the power supply unit 30 is not limited to a configuration that supplies DC power to the charging device 10, and may be a configuration that supplies AC power to the charging device 10. In addition, the charging connector 32 has different terminal arrangements or socket shapes at its ends for DC power supply and AC power supply.

[0015] The equipment control unit 34 is a computer configured with semiconductor integrated circuits including a central processing unit, a ROM in which programs and the like are stored, and a RAM as a work area. The equipment control unit 34 controls the entire power supply equipment 14 in cooperation with the program. The equipment control unit 34 can also communicate with the charging device 10 of the vehicle 12 through the charging connector 32 and a cable 38. When instructed to start charging, the equipment control unit 34 causes the power supply unit 30 to start supplying power to the vehicle 12, and when instructed to end charging, causes the power supply unit 30 to end supplying power to the vehicle 12. The equipment control unit 34 can also control the amount of power supplied from the power supply unit 30.

[0016] The charging device 10 includes a charging inlet 40, a charging unit 42, a storage unit 44, and a charging control unit 46. The charging inlet 40 is provided, for example, on a side surface of the body of the vehicle 12. The charging connector 32 is connectable to the charging inlet 40. The charging inlet 40 is capable of receiving power from the power supply equipment 14 through the charging connector 32.

[0017] The charging inlet 40 is electrically connected to the vehicle-mounted battery 20 via a charging unit 42. The charging unit 42 includes a switch that turns on and off the electrical connection between the charging inlet 40 and the vehicle-mounted battery 20. The charging unit 42 also includes a current measuring unit that measures the charging current flowing through the vehicle-mounted battery 20. The charging unit 42 also includes a voltage measuring unit that measures the voltage of the vehicle-mounted battery 20. When the charging unit 42 receives AC power, it converts it to DC power and supplies it to the vehicle-mounted battery 20.

[0018] The storage unit 44 is composed of a non-volatile storage element. A limit value of the charging current is stored in the storage unit 44. The limit value of the charging current corresponds to a target value of the charging current when charging the in-vehicle battery 20, which will be described later, and is used for controlling the charging.

[0019] The charging control unit 46 is a computer configured with semiconductor integrated circuits including a central processing unit, a ROM in which programs and the like are stored, a RAM as a work area, etc. The charging control unit 46 cooperates with the program to charge the in-vehicle battery 20 with power supplied from outside the vehicle through the charging inlet 40.

[0020] FIG. 2 is a diagram for explaining an outline of the operation of the charging control unit 46. FIG. 2A shows the charge capacity of the in-vehicle battery 20 in an initial state with almost no deterioration. FIG. 2B shows the charge capacity of the in-vehicle battery 20 which has deteriorated compared to FIG. 2A. FIG. 2C shows an example in which the charging current is limited. FIG. 2D shows another example in which the charging current is limited. For ease of explanation, in FIGS. 2A to 2D, it is assumed that the in-vehicle battery 20 is charged until the SOC (State Of Charge) of the in-vehicle battery 20 reaches from 0% to 100%.

[0021] In Fig. 2A, it is assumed that the charging current Ia is applied to the in-vehicle battery 20 for the charging time Ta, and the SOC reaches 100%. The charging capacity at this time is the product of the charging current and the charging time, and corresponds to the hatched area Sa in Fig. 2A.

[0022] In FIG. 2B, the degradation of the in-vehicle battery 20 is more advanced than in FIG. 2A. As the degradation progresses, the charge capacity decreases. The charge capacity in FIG. 2B corresponds to the hatched area Sb in FIG. 2B. The area Sb is smaller than the area Sa. In FIG. 2B, as in FIG. 2A, the in-vehicle battery 20 is charged by passing a charging current Ia through it. However, in FIG. 2B, the charge capacity has decreased, so if the charging current Ia is the same, the SOC reaches 100% in a charging time Tb that is shorter than the charging time Ta.

[0023] Here, a lithium ion battery, which is an example of the in-vehicle battery 20, has a tendency to deteriorate when placed in a high-temperature environment. As the deterioration progresses, the internal resistance of the in-vehicle battery 20 increases. Therefore, if charging is performed with the same charging current (e.g., charging current Ia) as before the deterioration progresses after the deterioration progresses, the amount of heat generated by the internal resistance of the in-vehicle battery 20 increases more than before the deterioration progresses. As a result, the temperature of the in-vehicle battery 20 itself after the deterioration progresses becomes higher than before the deterioration progresses, and there is a risk that the deterioration of the in-vehicle battery 20 will be further accelerated.

[0024] If the deterioration of the in-vehicle battery 20 is further accelerated, the charge capacity will further decrease. Then, if charging is repeated with the same charge current (e.g., charge current Ia) as before the deterioration progresses, the charge time will be further shortened as the charge capacity decreases. In this way, the deterioration progresses as the number of charging operations increases, and the charge time will be shortened as the deterioration progresses.

[0025] Therefore, the charging control unit 46 limits the charging current so as to slow down the rate of change in the reduction of the charging time that accompanies an increase in the number of charging executions. At this time, the charging control unit 46 derives a limit value of the charging current and transmits the limit value of the charging current to the equipment control unit 34 through the charging inlet 40. The equipment control unit 34 controls the power supply unit 30 so that the current of the power supplied through the charging connector 32 is equal to or less than the received limit value. As a result, the charging current flowing through the in-vehicle battery 20 is limited to equal to or less than the limit value.

[0026] More specifically, as shown in FIG. 2C, the charging control unit 46 limits the charging current flowing through the in-vehicle battery 20 to a charging current Ib smaller than the charging current Ia so that the charging time is Ta. In other words, the charging control unit 46 limits the charging current so that the charging time of the current charging, which corresponds to the charging after the deterioration has progressed relatively, is equal to the charging time of the previous charging, which corresponds to the charging before the deterioration has progressed relatively (for example, the charging time Ta). The charging current Ib in FIG. 2C corresponds to the limit value of the charging current. The charging capacity when limited to the charging current Ib is a value obtained by multiplying the charging current Ib by the charging time Ta, and corresponds to the area Sc shown by hatching in FIG. 2C. In other words, the charging current Ib is set to a value such that the area Sc is equal to the area Sb when the charging time is Ta.

[0027] Even if the internal resistance increases due to the progression of degradation, as shown in Fig. 2C, by limiting the charging current from the charging current Ia to the charging current Ib, it is possible to suppress an increase in the amount of heat generated due to the internal resistance of the in-vehicle battery 20. In other words, even if degradation progresses, it is possible to suppress an increase in the temperature of the in-vehicle battery 20 itself. As a result, it is possible to suppress further degradation due to an increase in the temperature of the in-vehicle battery 20.

[0028] Furthermore, the charging control unit 46 is not limited to limiting the charging current so that the charging time is equal to the charging time Ta before the deterioration progresses. The charging control unit 46 may limit the charging current so that the charging time is longer than at least the original charging time Tb before the charging current is limited.

[0029] 2D, the charge control unit 46 may limit the charge current to a charge time Tc that is longer than the charge time Tb when charging with the charge current Ia after the deterioration has progressed and is equal to or shorter than the charge time Ta. In other words, the rate of change in the reduction of the charge time is slower when the charge time is reduced from Ta to the charge time Tc than when the charge time is reduced from Ta to the charge time Tb.

[0030] In this case, the charging current is limited to a charging current Ic that is smaller than the charging current Ia and is equal to or greater than the charging current Ib when charging to the charging time Ta after the deterioration has progressed. In this case, the charging current Ic corresponds to the limit value of the charging current. The charging capacity when limited to the charging current Ic is a value obtained by multiplying the charging current Ic by the charging time Tc, and corresponds to the area Sd shown by hatching in FIG. 2D. In other words, the charging current Ic is set to a value such that the area Sd is equal to the area Sb when the charging time is Tc. In this way, a combination of a predetermined charging time (e.g., charging time Tc) and a predetermined limit value of the charging current (e.g., charging current Ic) can be arbitrarily set under the condition that the charging capacity is equal.

[0031] 2D, the charge control unit 46 limits the charge current so as to slow down the rate of change in the reduction of the charge time, thereby making it possible to suppress an increase in the amount of heat generated due to the internal resistance of the in-vehicle battery 20, as compared to a mode in which the charge current is not limited. As a result, it is possible to suppress further deterioration due to a rise in temperature of the in-vehicle battery 20.

[0032] In the example of Fig. 2C, the charging current is limited to a greater extent than in the example of Fig. 2D. Therefore, the example of Fig. 2C makes it possible to suppress the rate of deterioration of the in-vehicle battery 20 more effectively than the example of Fig. 2D.

[0033] 2D, the charging time Tc is set to be equal to or shorter than the charging time Ta. However, the charging control unit 46 may limit the charging current so that the charging time is longer than the charging time Ta before the deterioration progresses. In this embodiment, although there is a risk of a decrease in user convenience due to the charging time being longer than before the deterioration progresses, it is possible to further increase the degree of suppression of deterioration of the in-vehicle battery 20.

[0034] Fig. 3 is a diagram showing an example of the time transition of SOC during and after charging. Fig. 3A shows an initial in-vehicle battery 20 with almost no deterioration. Fig. 3B shows an in-vehicle battery 20 that has deteriorated compared to Fig. 3A. Fig. 3C shows a case where the charging current is limited by the charging control unit 46. Figs. 3A to 3C are shown on a common time axis, and it is assumed that the time from the start of charging to the start of running of the vehicle 12 is the same.

[0035] In Fig. 3A, for example, the charge capacity when the SOC is 100% is 25 Ah. Also, assume that the SOC at the start of charging is 30% and charging is continued until the SOC reaches 100%. During charging, charging is continued until the charge capacity of the in-vehicle battery 20 reaches 25 Ah. Then, the SOC is maintained at 100% for a predetermined post-completion waiting time from the end of charging to the start of driving.

[0036] In contrast, in FIG. 3B, for example, the charging capacity when the SOC is 100% becomes 20 Ah due to the progression of deterioration of the in-vehicle battery 20. In FIG. 3B, similar to FIG. 3A, charging is performed from 30% to 100% SOC. However, in the example of FIG. 3B, the charging capacity itself is reduced even though the SOCs are both 100%, compared to the example of FIG. 3A, so the charging time from the start of charging to the end of charging is shorter. As a result, in the example of FIG. 3B, the waiting time after completion is longer than in the example of FIG. 3A, and as a result, the time for which the SOC is maintained at 100% is longer.

[0037] A lithium ion battery, which is an example of the in-vehicle battery 20, has a tendency to deteriorate easily if the SOC is kept high (for example, the SOC is 100%) for a long time. Therefore, as in the example of FIG. 3B, if the post-completion standby time during which the SOC is 100% becomes long, the deterioration of the in-vehicle battery 20 may be further accelerated.

[0038] However, as described above, the charge control unit 46 limits the charge current so as to slow down the rate of change in the reduction in the charge time that accompanies an increase in the number of times charging is performed. For example, the charge control unit 46 limits the charge current so that the charge time after the deterioration progresses is equal to the charge time before the deterioration progresses (see FIG. 2C).

[0039] Then, for example, as shown in FIG. 3C, even if the charge capacity when the SOC is 100% is lower than that in the example of FIG. 3A, the charge time from the start of charging to the end of charging can be made equal to that in the example of FIG. 3A. Then, in the example of FIG. 3C, the post-completion waiting time from the end of charging to the start of running can be made equal to that in the example of FIG. 3A. This allows the charge control unit 46 to shorten the time during which the SOC after charging is maintained at 100% compared to the example of FIG. 3B. As a result, further deterioration caused by maintaining the SOC at a high state can be suppressed.

[0040] Furthermore, the charging control unit 46 is not limited to the mode of limiting the charging current so that the charging time after the deterioration progresses is equal to the charging time before the deterioration progresses, but may limit the charging current so as to at least slow down the rate of change in the shortening of the charging time, as described above (see FIG. 2D). Even in this mode, the charging time from the start of charging to the end of charging can be lengthened compared to the mode in which the charging current is not limited, and accordingly the time during which the SOC after charging is maintained at 100% can be shortened.

[0041] In addition, in a configuration in which the charging time after deterioration has progressed is made equal to that before deterioration has progressed, the time allowed for charging can be utilized to the maximum extent possible, and deterioration caused by maintaining a high SOC can be more effectively suppressed.

[0042] Fig. 4 is a diagram for explaining the definition of elements related to the derivation of the limit value of the charging current. In Fig. 4, point P0 indicates a state in which the SOC is 0%. Point P1 indicates a state in which the SOC is 100%. Point P2 indicates an example of the start of charging. Point P3 indicates an example of the end of charging. Solid line A10 indicates an example of the change in charging capacity over time from the start of charging to the end of charging.

[0043] As shown in Fig. 4, the full charge capacity indicates the amount of charge when the SOC is 100%, based on the amount of charge when the SOC is 0%. In other words, the full charge capacity indicates the amount of charge that can be supplied when the SOC goes from 100% to 0%. The full charge time indicates the time it takes for the SOC to go from 0% to 100% through charging. In other words, the full charge time indicates the charging time required to charge to the full charge capacity.

[0044] The starting charge capacity indicates the amount of charge when charging actually starts, based on the amount of charge when the SOC is 0%. The reached charge capacity indicates the amount of charge when charging actually ends, based on the amount of charge when the SOC is 0%. In other words, the amount of charge newly stored in the vehicle battery 20 by actual charging corresponds to the value obtained by subtracting the starting charge capacity from the reached charge capacity.

[0045] The actual charging time indicates the time elapsed from the start of charging to the end of charging. The plug-in charging time indicates the time required to charge to the reached charge capacity. If charging is started when the SOC is greater than 0%, the plug-in charging time will be longer than the actual charging time.

[0046] In the example of Figure 4, charging ends before the SOC reaches 100%, i.e., before the battery is fully charged. In this case, the achieved charge capacity is less than the full charge capacity. In contrast, when the battery is charged until the SOC reaches 100%, i.e., when the battery is fully charged, the achieved charge capacity is equal to the full charge capacity.

[0047] A charging map showing the relationship between each parameter, such as the voltage, current, SOC, charging capacity, and charging time of the in-vehicle battery 20, is created in advance and stored in the storage unit 44. The charging map shows, for example, a plurality of lines showing the correlation between the parameters. The charging control unit derives an estimated value of the plug-in charging time, etc., by referring to such a charging map.

[0048] Furthermore, the memory unit 44 stores a limit value of the charging current. Each time charging is completed, the charging control unit 46 judges whether or not a predetermined condition indicating that the degradation of the in-vehicle battery 20 has progressed has been met. When the predetermined condition is met, the charging control unit 46 derives a new limit value of the charging current and updates the limit value of the charging current stored in the memory unit 44. Hereinafter, the flow of the operation of the charging control unit 46 will be explained, and the derivation of the limit value of the charging current will be described in detail.

[0049] Fig. 5 is a flowchart illustrating the flow of operations of the charging control unit 46. The charging control unit 46 executes the series of processes in Fig. 5 when the charging connector 32 is connected to the charging inlet 40 and in response to an instruction to start charging. When the series of processes in Fig. 5 is completed once, one charging has been performed. Note that "the previous time" refers to the process in the charging performed one time before the current charging.

[0050] The charging control unit 46 first reads out the limit value of the charging current from the storage unit 44 (S10). Next, the charging control unit 46 transmits the read-out limit value of the charging current to the equipment control unit 34 (S11). Then, the charging control unit 46 starts to execute charging current limit control to charge with a charging current equal to or less than the limit value (S12). The charging control unit 46 continues the charging current limit control until a charging end condition is satisfied (NO in S13). The charging end condition is, for example, that the SOC of the in-vehicle battery 20 is equal to or greater than a predetermined SOC indicating the end of charging. Note that the charging end condition may be that an end instruction is received through a user operation.

[0051] When the charge end condition is satisfied (YES in S13), the charge control unit 46 performs an end process (S14) and then ends the series of processes. The end process includes a process related to updating the limit value of the charging current. The end process will be described in detail later.

[0052] Fig. 6 is a flowchart explaining the flow of the termination process (S14). First, the charging control unit 46 derives the plug-in charging time for the current charge (S20). For example, the charging control unit 46 derives the plug-in charging time by applying the SOC at the start of charging, the SOC at the end of charging, the actual charging current, and the like to a charging map. Although not shown in Fig. 6, the charging control unit 46 stores the derived plug-in charging time in the storage unit 44.

[0053] Next, the charging control unit 46 derives the reached charge capacity for the current charge (S21). For example, the charging control unit 46 derives the reached charge capacity by applying the voltage of the in-vehicle battery 20 at the end of charging, the SOC at the end of charging, the actual charging current, the current plug-in charging time, and the like to a charging map. Although not shown in FIG. 6, the charging control unit 46 stores the derived reached charge capacity in the storage unit 44.

[0054] Next, the charging control unit 46 derives the full charge capacity for the current charging (S22). For example, the charging control unit 46 derives the full charge capacity by applying the SOC at the end of charging, the current reached charge capacity, and the like to a charging map. Although not shown in FIG. 6, the charging control unit 46 stores the derived full charge capacity in the storage unit 44.

[0055] Next, the charge control unit 46 reads out the previous full charge capacity from the memory unit 44, and subtracts the current full charge capacity from the previous full charge capacity (previous full charge capacity - current full charge capacity) to derive a full charge capacity difference (S23).

[0056] Next, the charging control unit 46 judges whether the full charge capacity difference is equal to or greater than a predetermined value (S24). The process of step S24 corresponds to the process of judging whether a predetermined condition indicating that the deterioration of the in-vehicle battery 20 has progressed is satisfied. If the full charge capacity difference is less than the predetermined value (NO in S24), the charging control unit 46 determines that the deterioration of the in-vehicle battery 20 has not progressed between the previous and current charging, and ends the termination process. In this case, the limit value of the charging current is not updated.

[0057] If the full charge capacity difference is equal to or greater than the predetermined value (YES in S24), the charging control unit 46 determines that the deterioration of the in-vehicle battery 20 has progressed between the previous and current charging, and performs the processes in and after step S25.

[0058] In step S25, the charge control unit 46 derives the current full charge time by the following formula (1) (S25). Although not shown in FIG. 6, the charge control unit 46 stores the derived current full charge time in the storage unit 44. Current full charge time [h] = Current full charge capacity [Ah] ÷ Current achieved charge capacity [Ah] ×Current plug-in charging time [h] (1)

[0059] Next, the charge control unit 46 divides the current full charge time by the previous full charge time (current full charge time ÷ previous full charge time) to derive the reduction rate of the full charge time (S26). This reduction rate of the full charge time indicates the degree of deterioration of the in-vehicle battery 20 from the previous charge to the current charge. For example, if deterioration has progressed from the previous charge to the current charge, the current full charge time will be shorter than the previous full charge time. Therefore, the smaller the reduction rate of the full charge time, the greater the degree of deterioration.

[0060] Next, the charging control unit 46 multiplies the previous limit value of the charging current by the reduction rate of the full charge time as shown in the following formula (2) to derive a new limit value of the charging current (S28). That is, the charging control unit 46 reduces the limit value of the charging current according to the degree of deterioration. Charging current limit value = previous charging current limit value × reduction rate of full charge time (2)

[0061] The charging control unit 46 updates the limit value of the charging current (S28) by storing the limit value of the charging current newly derived in this step S28 in the storage unit 44, and ends the termination process. As a result, the charging current during the next and subsequent charging operations is limited to the updated limit value or less.

[0062] As described above, the charging control unit 46 of the charging device 10 of this embodiment limits the charging current so as to slow down the rate of change in the reduction of the charging time that accompanies an increase in the number of charging executions. As a result, the charging device 10 of this embodiment can suppress the amount of heat generated by the in-vehicle battery 20, and can suppress the accelerated deterioration of the in-vehicle battery 20 due to a rise in temperature.

[0063] Therefore, according to the charging device 10 of this embodiment, deterioration of the in-vehicle battery 20 can be suppressed.

[0064] Furthermore, the charging control unit 46 of the charging device 10 of this embodiment limits the charging current when charging so that the current charging time is equal to the charging time of the previous charging. This limits the charging current to the maximum. Therefore, the charging device 10 of this embodiment can suppress the deterioration of the in-vehicle battery 20 to the maximum extent.

[0065] Furthermore, the charging control unit 46 of the charging device 10 of this embodiment derives the full charge time each time charging is performed, and updates the limit value of the charging current based on the shortening rate of the current full charge time relative to the previous full charge time. This allows the charging device 10 of this embodiment to update the limit value of the charging current to a value according to the degree of deterioration, making it possible to more accurately suppress deterioration of the in-vehicle battery 20.

[0066] Although the embodiment of the present invention has been described above with reference to the attached drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that such examples also naturally belong to the technical scope of the present invention.

[0067] For example, the charging control unit 46 in the above embodiment compares the full charge capacity of the previous charge with the full charge capacity of the current charge to determine whether deterioration has progressed. However, the charging control unit 46 may compare the full charge capacity of the first charge with the full charge capacity of the current charge to determine whether deterioration has progressed. Also, the charging control unit 46 may compare the full charge capacity of the charge when the charging current was updated with the full charge capacity of the current charge to determine whether deterioration has progressed.

[0068] In the above embodiment, the charge control unit 46 determines that deterioration has progressed when the full charge capacity difference is equal to or greater than a predetermined value, and updates the limit value of the charge current. However, the charge control unit 46 may derive and update the limit value of the charge current every time, regardless of whether the full charge capacity difference is equal to or greater than a predetermined value.

[0069] In addition, the charging control unit 46 in the above embodiment derives the limit value of the charging current based on the shortening rate of the full charge time derived by dividing the current full charge time by the previous full charge time. However, the charging control unit 46 may derive the shortening rate of the full charge time by dividing the current full charge time by the initial full charge time, and multiply this shortening rate of the full charge time by the initial limit value to derive a new limit value. The charging control unit 46 may derive the shortening rate of the full charge time by dividing the current full charge time by the full charge time when the limit value was updated, and multiply this shortening rate of the full charge time by the limit value when the limit value was updated to derive a new limit value. In other words, the charging control unit 46 may update the limit value of the charging current based on the shortening rate of the full charge time of the current full charge time relative to the full charge time before this full charge time. [Explanation of symbols]

[0070] 10 Charging device 12 Vehicles 20 Vehicle Battery 32 Charging connector 40 Charging inlet 46 Charging control unit

Claims

1. A charging inlet provided in a vehicle and connectable to a charging connector outside the vehicle; a charging control unit that charges an on-board battery with power supplied from outside the vehicle through the charging inlet, and limits a charging current so as to slow down a rate of change in a reduction in charging time that accompanies an increase in the number of times the charging is performed; The charging control unit is calculating a full charge time required for the SOC of the vehicle-mounted battery to go from 0% to 100% using a final charge capacity reached by the charging, a full charge capacity obtained from a relationship between the SOC of the vehicle-mounted battery and the final charge capacity, and a charging time; a charging current limit value corresponding to a reduction rate of a full charge time calculated from a ratio of the first full charge time calculated during the previous charging to the second full charge time calculated during the current charging, the charging current limit value being calculated based on the reduction rate of the full charge time calculated based on a ratio of the first full charge time calculated during the previous charging to the second full charge time calculated during the current charging, the charging current limit value being calculated based on the reduction rate of the full charge time calculated based on a ratio of the first full charge time calculated during the previous charging to the second full charge time calculated during the current charging, The charging device limits the charging current to the limit value the next time the battery is charged.

2. The charging device according to claim 1 , wherein, when charging, the charge control unit limits a charging current so that a current charging time is equal to a previous charging time.

3. The achieved charge capacity indicates the amount of charge when charging is actually completed, based on the amount of charge when the SOC of the vehicle battery is 0%, The time required for charging to the reached charge capacity is the plug-in charging time, The charging control unit is The time required to fully charge the battery is calculated each time a battery is charged. 3 . The charging device according to claim 1 , wherein the second full charge time is derived by multiplying a result of dividing the second full charge capacity by the current reached charge capacity by the current plug-in charging time.

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