Charging device

Abstract

A processor of this charging device executes processes including: assessing whether a current condition is met, the current condition being that an equipment-side current, which is the maximum value of current that can be outputted by power supply equipment, is less than a vehicle-side current, which is the maximum value of current that can be received by a battery from the time point at which charging of the battery by the power supply equipment is started until the battery becomes fully charged; assessing whether a voltage condition is met, the voltage condition being that an equipment-side voltage, which is the maximum value of voltage that can be outputted by the power supply equipment, is greater than a vehicle-side voltage, which is the maximum value of voltage that can be received by the battery from the time point at which charging of the battery by the power supply equipment is started until the battery becomes fully charged; permitting execution of step-down charging when it is assessed that the current condition is met and the voltage condition is met; and assessing that normal charging is to be executed without permitting execution of step-down charging when it is assessed that either or both of the current condition and the voltage condition are not met.

Description

Charging device

[0001] The present invention relates to a charging device.

[0002] For example, Patent Document 1 discloses a vehicle configured to be able to switch between a first state in which the power of a DC charger is directly supplied to a battery and a second state in which the power of the DC charger is stepped down and supplied to the battery. In such Patent Document 1, when the outputable voltage (VS) of the DC charger is greater than the target charging voltage (VB) of the battery, the power of the DC charger is stepped down and supplied to the battery.

[0003] Japanese Unexamined Patent Application Publication No. 2019-140721

[0004] However, the battery has a characteristic that the current that can be received during charging changes depending on the SOC (State Of Charge: charge state) of the battery. Therefore, even when the outputable voltage (VS) of the DC charger is greater than the target charging voltage (VB) of the battery as in Patent Document 1, depending on the SOC of the battery, it is not always appropriate to perform step-down charging in which the power of the DC charger is stepped down and supplied to the battery.

[0005] Therefore, an object of the present invention is to provide a charging device that appropriately determines whether step-down charging is possible.

[0006] To solve the above problems, a charging device according to one embodiment of the present invention includes: a charging port provided in a vehicle and electrically connectable to an external power supply facility; a power converter provided in the current path between a battery mounted in the vehicle and the charging port, capable of stepping down the power supplied from the power supply facility through the charging port and supplying it to the battery; a control device that performs switching control between step-down charging, in which the power supplied from the power supply facility is stepped down by the power converter and supplied to the battery, and normal charging, in which the power supplied from the power supply facility is supplied to the battery as is without stepping down the power; the control device includes one or more processors; and one or more memories connected to the processors; the processor determines whether the equipment-side current, which is the maximum current that the power supply facility can output, is smaller than the vehicle-side current, which is the maximum current that the battery can accept from the time the power supply facility starts charging the battery until the battery is fully charged; The process includes: determining whether the equipment-side voltage, which is the maximum voltage that the power supply equipment can output, is greater than the vehicle-side voltage, which is the maximum voltage that the battery can accept from the time the power supply equipment starts charging the battery until the battery is fully charged; if the current condition is met and the voltage condition is met, permitting the execution of step-down charging; and if either or both of the current condition and the voltage condition are not met, not permitting the execution of step-down charging and deciding to perform normal charging.

[0007] According to the present invention, it becomes possible to appropriately determine whether step-down charging is possible.

[0008] Figure 1 is a block diagram showing an example of the configuration of the charging system according to this embodiment. Figure 2 is a diagram showing an example of the relationship between the battery's SOC, the battery's acceptable voltage, the battery's acceptable current, and the battery's acceptable power. Figure 3 is a flowchart illustrating the operation flow of the charging control unit. Figure 4 is a flowchart illustrating the flow of the verification process.

[0009] Embodiments of the present invention will be described in detail below with reference to the attached drawings. The specific dimensions, materials, numerical values, etc., shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0010] Figure 1 is a block diagram showing an example of the configuration of the charging system 1 according to this embodiment. The charging system 1 includes a vehicle 12 to which the charging device 10 according to this embodiment is applied, and a power supply facility 14.

[0011] Vehicle 12 is, for example, an electric vehicle equipped with a motor-generator as a power source. Vehicle 12 may also be a hybrid electric vehicle equipped with an engine and a motor-generator as power sources.

[0012] The vehicle 12 is equipped with a battery 20. The battery 20 is a rechargeable secondary battery, such as a lithium-ion battery. The battery 20 supplies power to, for example, the motor generator, which is the drive source of the vehicle 12. The charging device 10, which will be described in detail later, can be electrically connected to an external power supply facility 14 of the vehicle 12, and charges the vehicle 12's battery 20 with power supplied from the power supply facility 14.

[0013] The power supply equipment 14 is, for example, an electric vehicle supply device (EVSE), such as a charging station. 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 grid. However, the power supply source 36 is not limited to a power grid; for example, it may be any power source installed independently of a power grid.

[0014] The charging connector 32 is connected to the power supply unit 30 via a cable 38. As will be described later, the charging connector 32 can be electrically connected to the charging device 10 of the vehicle 12. The power supply unit 30 converts the AC power supplied from the power source 36 into DC power and supplies the converted DC power to the vehicle 12 through the charging connector 32. In other words, the power supply equipment 14 of this embodiment is configured to enable DC charging.

[0015] The equipment control unit 34 includes a processor and memory and works with the program to control the entire power supply equipment 14. The equipment control unit 34 can also communicate with the vehicle's charging device 10 through the charging connector 32 and cable 38. The equipment control unit 34 can control the start of charging, the end of charging, and the power supplied from the power supply unit 30 to the vehicle 12.

[0016] The charging device 10 includes a charging port 50, a power converter 52, a first switch 54, a second switch 56, and a control device 60.

[0017] The charging port 50 is provided, for example, in the inlet of the vehicle 12. The inlet is provided, for example, on the side of the vehicle body 12. The charging port 50 is exposed to the outside of the vehicle 12 by opening the door of the inlet and removing a predetermined cover.

[0018] In its exposed state, the charging port 50 is mechanically and electrically connectable to the charging connector 32 of the power supply equipment 14, as shown by the dashed line 62 in Figure 1. The charging port 50 is also electrically connectable to the battery 20.

[0019] The power converter 52 is provided in the current path between the battery 20 and the charging port 50. More specifically, the first end of the power converter 52 is connected to the charging port 50 via a first switch 54, and the second terminal of the power converter 52 is connected to the battery 20. The power converter 52 is, for example, a DC-DC converter. The power converter 52 is configured to at least step down the power supplied from the power supply equipment 14 through the charging port 50 and supply it to the battery 20. Furthermore, the power converter 52 may be configured to step up the power supplied from the power supply equipment 14 through the charging port 50 and supply it to the battery 20.

[0020] The first switch 54 is, for example, a relay, but any switch such as a semiconductor switch may be used. The first switch 54 is provided in the current path between the charging port 50 and the power converter 52. More specifically, the first terminal of the first switch 54 is connected to the charging port 50, and the second terminal of the first switch 54 is connected to the power converter 52. Hereafter, the current path in the order of charging port 50, first switch 54, power converter 52, and battery 20, that is, the current path passing through the power converter 52, may be referred to as the first current path.

[0021] When the first switch 54 is turned ON, it electrically connects the charging port 50 and the power converter 52, and as a result, electrically connects the first current path that passes through the power converter 52. When the first switch 54 is turned OFF, it electrically disconnects the charging port 50 and the power converter 52, and as a result, electrically disconnects the first current path that passes through the power converter 52.

[0022] The second switch 56 is, for example, a relay, but any switch such as a semiconductor switch may be used. The second switch 56 is provided in parallel with the first switch 54 and the power converter 52, which are connected in series. More specifically, the first terminal of the second switch 56 is connected to the connection node between the charging port 50 and the first switch 54. The second terminal of the second switch 56 is connected to the connection node between the power converter 52 and the battery 20. Hereafter, the current path in the order of charging port 50, second switch 56, and battery 20, that is, the current path that bypasses the power converter 52, may be referred to as the second current path.

[0023] When the second switch 56 is turned ON, it electrically connects the second current path that bypasses the power converter 52. When the second switch 56 is turned OFF, it electrically disconnects the second current path that bypasses the power converter 52. Furthermore, when the first switch 54 is turned ON, the second switch 56 is exclusively turned OFF, and when the first switch 54 is turned OFF, the second switch 56 is exclusively turned ON.

[0024] The control device 60 includes one or more processors 70 and one or more memories 72 connected to the processors 70. The memories 72 include ROM for storing programs and RAM as a work area. The processors 70 work in cooperation with the programs contained in the memories 72 to perform various processes. By executing the programs, the processors 70 function as a charge control unit 80 that controls the charging of the battery 20. The charge control unit 80 will be described in detail later.

[0025] Hereafter, for the sake of explanation, the maximum voltage that the power supply equipment 14 can output may be referred to as the equipment-side voltage, and the maximum current that the power supply equipment 14 can output may be referred to as the equipment-side current.

[0026] Here, for example, suppose a vehicle 12 whose battery 20 has a maximum acceptable voltage of "400V" is connected to a power supply facility 14 whose equipment-side voltage is "400V". In this case, since the equipment-side voltage and the maximum acceptable voltage of the battery 20 are the same, the vehicle 12 can supply the voltage output by the power supply facility 14 directly to the battery 20.

[0027] On the other hand, suppose a vehicle 12 whose battery 20 can accept a maximum voltage of "400V" is connected to a power supply facility 14 whose equipment-side voltage is "1000V". In this case, since the equipment-side voltage of "1000V" is greater than the maximum voltage of "400V" that the battery 20 can accept, even if the power supply facility 14 outputs a voltage of "1000V", that voltage cannot be supplied directly to the battery 20.

[0028] In such a case, the vehicle 12 may have the 1000V voltage supplied from the power supply equipment 14 stepped down to 400V, the maximum voltage that the battery 20 can accept, by the power converter 52, and the stepped-down power supplied to the battery 20.

[0029] Hereafter, for the sake of explanation, charging in which the power supplied from the power supply equipment 14 is stepped down by the power converter 52 and supplied to the battery 20 may be referred to as step-down charging. Also, charging in which the power supplied from the power supply equipment 14 is supplied directly to the battery 20 without stepping down the voltage may be referred to as normal charging.

[0030] Furthermore, if the equipment voltage of "1000V" is greater than the maximum voltage that the battery 20 can accept, "400V", the power supply equipment 14 may supply a voltage reduced to "400V" to the vehicle 12 to match the battery 20. In this case, the vehicle 12 will perform normal charging by supplying the "400V" voltage output by the power supply equipment 14 directly to the battery 20 without stepping it down.

[0031] The charging control unit 80 controls the switching between step-down charging and normal charging by controlling the on / off state of the first switch 54 and the second switch 56.

[0032] More specifically, when performing step-down charging, the charging control unit 80 turns on the first switch 54 and turns off the second switch 56. This electrically connects the first current path that goes through the power converter 52, and electrically disconnects the second current path that bypasses the power converter 52. The charging control unit 80 then causes the power converter 52 to perform a step-down operation. As a result, the stepped-down power is supplied to the battery 20 through the first current path, and step-down charging is achieved.

[0033] Furthermore, when performing normal charging, the charging control unit 80 turns off the first switch 54 and turns on the second switch 56. As a result, the first current path that goes through the power converter 52 is electrically interrupted, and the second current path that bypasses the power converter 52 is electrically connected. As a result, the power supplied through the charging port 50 is supplied directly to the battery 20 through the second current path without being stepped down, and normal charging is achieved.

[0034] As described above, if the equipment voltage "1000V" is greater than the maximum acceptable voltage of the battery 20 "400V", then step-down charging or normal charging may be performed, meaning that step-down charging is possible. When either step-down charging or normal charging is possible, step-down charging requires the power supply equipment 14 to output more power than normal charging, so the charging time for step-down charging is shorter than that for normal charging. For this reason, when either step-down charging or normal charging is possible, it is generally presumed that step-down charging offers greater advantages to the passengers of the vehicle 12.

[0035] However, the battery 20 also has the characteristic that the current it can accept during charging changes depending on the State of Charge (SOC) of the battery 20. Therefore, even if it is determined that step-down charging is possible based solely on the relationship between the equipment voltage and the maximum voltage that the battery 20 can accept, this determination may not necessarily be appropriate depending on the SOC of the battery 20.

[0036] Therefore, in the charging device 10 of this embodiment, whether step-down charging is possible is determined by considering not only the relationship between the equipment voltage and the maximum voltage that the battery 20 can accept, but also the relationship between the equipment current and the maximum current that the battery 20 can accept.

[0037] Figure 2 shows an example of the relationship between the State of Charge (SOC) of battery 20, the acceptable voltage of battery 20, the acceptable current of battery 20, and the acceptable power of battery 20. In Figure 2, the solid curve A1 shows an example of the current that battery 20 can accept. The dashed-dotted curve A2 shows an example of the voltage that battery 20 can accept. The double-dotted curve A3 shows an example of the power that battery 20 can accept, specifically the product of the current in curve A1 and the voltage in curve A2. In Figure 2, the numerical values ​​on the left vertical axis represent both the current and the voltage.

[0038] As shown in Figure 2, the current that the battery 20 can accept decreases as the SOC increases. Also, the voltage that the battery 20 can accept increases gradually as the SOC increases.

[0039] Hereafter, for the sake of explanation, the maximum current that the battery 20 can accept from the time charging of the battery 20 by the power supply equipment 14 begins until the battery 20 is fully charged may be referred to as the vehicle-side current. Similarly, the maximum voltage that the battery 20 can accept from the time charging of the battery 20 by the power supply equipment 14 begins until the battery 20 is fully charged may be referred to as the vehicle-side voltage.

[0040] For example, when the charging connector 32 of the power supply equipment 14 is connected to the charging port 50 of the vehicle 12, in other words, when charging begins, suppose the State of Charge (SOC) of the vehicle 12's battery 20 is "30%". In this example, the current that the battery 20 can accept at the start of charging is "300A", as shown in Figure 2. When charging is performed, the SOC of the battery 20 increases, so the current that the battery 20 can accept will decrease from the value at the start of charging. In this example, the vehicle-side current will effectively be "300A", which is the current that the battery 20 can accept at the start of charging.

[0041] Also, for example, if the SOC of the battery 20 at the start of charging is "20%", as shown in FIG. 2, the vehicle-side current is substantially "380 A", which is the current that the battery 20 can accept at the start of charging. That is, the vehicle-side current depends on the SOC of the battery 20 at the start of charging, and the lower the SOC of the battery 20 at the start of charging, the larger the value.

[0042] Also, assume that the SOC of the battery 20 at the start of charging is "30%". In this example, as shown in FIG. 2, the voltage that the battery 20 can accept at the start of charging is "360 V". When charging is executed, since the SOC of the battery 20 increases, the voltage that the battery 20 can accept gradually increases from the value at the start of charging and reaches "400 V" at full charge. In this example, the vehicle-side voltage is substantially "400 V", which is the voltage that the battery 20 can accept at full charge. That is, the vehicle-side voltage corresponds substantially to the voltage that the battery 20 can accept at full charge regardless of the SOC of the battery 20 at the start of charging.

[0043] Also, as shown by the solid line B1 in the horizontal direction in FIG. 2, assume that the equipment-side current, which is the maximum value of the current that the power supply equipment 14 can output, is "200 A". As shown in FIG. 2, the SOC at the intersection of the current "200 A" that the battery 20 can accept and the equipment-side current "200 A" is "55%", as shown by the dashed line C1 in the vertical direction.

[0044] When the SOC of the battery 20 at the start of charging is less than "55%", that is, in the left region of the dashed line C1 in FIG. 2, the equipment-side current "200 A" is less than the vehicle-side current (equipment-side current < vehicle-side current). On the other hand, when the SOC of the battery 20 at the start of charging is "55%" or more, that is, in the right region of the dashed line C1 in FIG. 2, the equipment-side current "200 A" is greater than or equal to the vehicle-side current (equipment-side current ≧ vehicle-side current). That is, the dashed line C1 indicates a dividing line that divides the magnitude relationship between the equipment-side current and the vehicle-side current.

[0045] In the left region of the demarcation line indicated by the dashed line C1, even if the power supply facility 14 outputs a current of "200 A" for step-down charging, the battery 20 can accept such a current. Therefore, when the SOC of the battery 20 at the start of charging belongs to the region to the left of the demarcation line, it means that "step-down charging may be performed".

[0046] Therefore, the charging control unit 80 determines whether or not the current condition that the facility-side current is smaller than the vehicle-side current is satisfied. The charging control unit 80 determines whether or not the voltage condition that the facility-side voltage is larger than the vehicle-side voltage is satisfied. When the charging control unit 80 determines that the current condition is satisfied and the voltage condition is satisfied, it permits the execution of step-down charging.

[0047] Here, "permitting" the execution of step-down charging means that "step-down charging may be performed". After the execution of step-down charging is permitted, step-down charging may actually be executed, or normal charging may be executed without actually performing step-down charging. Specifically, after the execution of step-down charging is permitted, detailed determination described later is performed, and the execution of step-down charging is determined according to the result of the determination.

[0048] Also, in the right region of the demarcation line indicated by the dashed line C1, the power supply facility 14 can output "200 A", but the battery 20 can only accept a current smaller than "200 A". Therefore, in this right region, the current output by the power supply facility 14 should be reduced to match the maximum value of the current that the battery 20 can accept. If the voltage is increased while reducing the current supplied from the power supply facility 14 and step-down is performed on the vehicle 12 side, the power loss in the power conversion device 52 may increase. When the power loss in the power conversion device 52 increases, the efficiency of the power actually contributing to charging with respect to the power output by the power supply facility 14 decreases. Then, the merit of performing step-down charging is low, and in some cases, demerits of step-down charging such as an increase in the charging fee may occur. In this right region, it is not appropriate to execute step-down charging. Therefore, when the SOC of the battery 20 at the start of charging belongs to the region to the right of the demarcation line, it means "do not perform step-down charging", in other words, "perform normal charging".

[0049] Therefore, if the charging control unit 80 determines that either or both of the above-mentioned current conditions and voltage conditions are not met, it will not permit the execution of step-down charging and will decide to perform normal charging.

[0050] Thus, in the charging device 10 of this embodiment, both current conditions and voltage conditions are considered to determine whether to allow step-down charging or to decide to perform normal charging. As a result, the charging device 10 of this embodiment can more appropriately select between step-down charging and normal charging in accordance with a realistic combination of the capacity of the power supply equipment 14 and the state of the battery 20.

[0051] Figure 3 is a flowchart illustrating the operation flow of the charging control unit 80. When the charging control unit 80 detects that the charging connector 32 of the power supply equipment 14 is connected to the charging port 50, it executes the series of processes shown in Figure 3. In other words, the charging control unit 80 executes the series of processes shown in Figure 3 when charging starts.

[0052] First, the charging control unit 80 communicates with the equipment control unit 34 of the power supply equipment 14 and obtains various information from the power supply equipment 14 (S10). For example, the charging control unit 80 obtains the equipment-side current, equipment-side voltage, charging fee plan, etc., but it is not limited to obtaining the information exemplified above, and may obtain any information necessary for charging.

[0053] Next, the charging control unit 80 identifies the vehicle-side current based on the current state of charge (SOC) of the battery 20 and determines whether the equipment-side current is smaller than the vehicle-side current (S11).

[0054] If the equipment-side current is determined to be less than the vehicle-side current (YES in S11), the charging control unit 80 identifies the estimated value of the acceptable voltage when the battery 20 is fully charged as the vehicle-side voltage and determines whether the equipment-side voltage is greater than the vehicle-side voltage (S12).

[0055] If the equipment voltage is determined to be greater than the vehicle voltage (YES in S12), the charging control unit 80 permits the execution of step-down charging (S13).

[0056] In other words, the charging control unit 80 permits the execution of step-down charging if it determines that the current condition, which is that the equipment-side current is less than the vehicle-side current, is met, and the voltage condition, which is that the equipment-side voltage is greater than the vehicle-side voltage, is met. The charging control unit 80 may also reverse the execution order of the current condition determination in step S11 and the voltage condition determination in step S12.

[0057] In step S11, if it is determined that the equipment-side current is greater than or equal to the vehicle-side current (NO in S11), the charging control unit 80 decides to perform normal charging (S14) and terminates the series of processes. Also, in step S12, if it is determined that the equipment-side voltage is less than or equal to the vehicle-side voltage (NO in S12), the charging control unit 80 decides to perform normal charging (S14) and terminates the series of processes.

[0058] In other words, if the charging control unit 80 determines that either or both of the current and voltage conditions are not met, it will not permit step-down charging and will decide to perform normal charging.

[0059] Upon deciding to perform normal charging, the charging control unit 80 turns off the first switch 54 and turns on the second switch 56. As a result, normal charging is performed.

[0060] After authorizing the execution of step-down charging in step S13, the charging control unit 80 derives a step-down charging time, which is an estimated value of the charging time when step-down charging is performed, and a normal charging time, which is an estimated value of the charging time when normal charging is performed (S20). The charging control unit 80 derives a shortened time, which is the normal charging time minus the step-down charging time (S21).

[0061] Next, the charging control unit 80 determines whether the reduction time is equal to or greater than a predetermined time (S22). The predetermined time is set to any time such that the charging time is deemed to have been sufficiently reduced by step-down charging, for example, 5 minutes or more.

[0062] If the charging control unit 80 determines that the time reduction is equal to or greater than a predetermined time (YES in S22), it decides to perform step-down charging (S23) and terminates the series of processes. In other words, the execution of step-down charging, which was determined to be permitted in step S13, is confirmed in step S23. In this case, it is presumed that the charging time can be sufficiently shortened by performing step-down charging, and that the benefits of performing step-down charging are significant, so step-down charging is performed.

[0063] Upon deciding to perform step-down charging, the charging control unit 80 turns on the first switch 54 and turns off the second switch 56. This initiates step-down charging.

[0064] Furthermore, if step S22 determines that the reduction time is less than a predetermined time (NO in S22), the charge control unit 80 derives an estimated loss amount that indicates the power loss estimated to occur in the power converter 52 during step-down charging (S30). For example, the memory 72 of the control device 60 has a loss map pre-stored that shows the relationship between the power input to the power converter 52, the power output from the power converter, and the power loss in the power converter 52. The charge control unit 80 may also derive an estimated loss amount from the input / output power of the power converter 52 and the loss map when step-down charging is performed.

[0065] Next, the charging control unit 80 determines whether the estimated loss amount is greater than or equal to a predetermined threshold (S31). The predetermined threshold is set to an arbitrary value such that the estimated loss amount in the power converter 52 is considered to be larger than the error range.

[0066] If the estimated loss is determined to be less than a predetermined threshold (NO in S31), the charge control unit 80 decides to perform step-down charging (S23) and terminates the series of processes. In other words, the execution of step-down charging, which was determined to be permitted in step S13, is confirmed in step S23. In this case, since it is estimated that the power loss by the power converter 52 will be small even if step-down charging is performed, it is inferred that the benefits of step-down charging outweigh the disadvantages of power loss, and therefore step-down charging is performed.

[0067] If the estimated loss is determined to be above a predetermined threshold (YES in S31), the charging control unit 80 performs a confirmation process (S40) to confirm with the occupant of the vehicle 12 whether or not to allow step-down charging. In this case, it is presumed that the benefits of step-down charging are relatively small because the time shortened by step-down charging is relatively short, and furthermore, the power loss by the power converter 52 is relatively large. For this reason, the occupant of the vehicle 12 is asked whether or not to allow step-down charging.

[0068] Furthermore, the charging control unit 80 may decide to perform normal charging without performing the confirmation process (S40) if it determines that the estimated loss amount is equal to or greater than a predetermined threshold.

[0069] Figure 4 is a flowchart illustrating the flow of the confirmation process (S40). When the confirmation process (S40) is started, the charging control unit 80 derives the step-down charging fee, which is the fee if step-down charging is performed, and the normal charging fee, which is the fee if normal charging is performed (S50).

[0070] For example, the charging control unit 80 derives an estimated value of the amount of electricity supplied from the power supply equipment 14 to the vehicle 12 during normal charging. The charging control unit 80 may also derive the normal charging fee from the estimated amount of electricity and the charging fee plan.

[0071] Furthermore, when step-down charging is performed, power loss occurs in the power converter 52, so the power supply equipment 14 will output extra power equal to the estimated loss consumed by the power converter 52. For this reason, the charging control unit 80 derives an estimated value of the amount of power supplied from the power supply equipment 14 to the vehicle 12 during step-down charging, and corrects the estimated amount of power by adding power equal to the estimated loss to that estimated amount of power. The charging control unit 80 may also derive the step-down charging fee from the corrected estimated amount of power and the charging fee plan.

[0072] The charging control unit 80 presents the step-down charging fee, normal charging fee, step-down charging time, normal charging time, and reduced charging time to the passenger of the vehicle 12 (S51), and prompts the passenger to input a confirmation result of whether or not to permit step-down charging. For example, the charging control unit 80 may present each piece of information by displaying it on the display screen of a navigation device or the like. The presentation method is not limited to the example given, but may be any method that is recognizable to the passenger of the vehicle 12.

[0073] Furthermore, the method of displaying all of the following is not limited to displaying the step-down charging fee, normal charging fee, step-down charging time, normal charging time, and shortened charging time. The charging control unit 80 may prompt the passenger of the vehicle 12 to input the confirmation result by displaying at least the step-down charging fee. When the passenger of the vehicle 12 makes a decision on whether or not to permit step-down charging, it is assumed that the step-down charging fee will have the greatest influence on that decision. Therefore, by displaying at least the step-down charging fee, the passenger of the vehicle 12 can make that decision.

[0074] Passengers of vehicle 12 can confirm the presented information and input the confirmation results, for example, through an input device such as the touch panel of a navigation system.

[0075] The charging control unit 80 determines whether or not it has received the input of the confirmation result (S52). The charging control unit 80 waits until it receives the input of the confirmation result (NO in S52). If the input of the confirmation result is not received even after a predetermined time has elapsed, the charging control unit 80 may consider it a time-up and, for example, cancel the permission for step-down charging and decide to perform normal charging.

[0076] If the charging control unit 80 determines that it has received the confirmation result (YES in S52), it determines whether the received confirmation result permits the execution of step-down charging (S53).

[0077] If a confirmation result is obtained indicating permission to perform step-down charging (YES in S53), the charging control unit 80 decides to perform step-down charging (S54), and terminates the confirmation process (S40) and the series of processes shown in Figure 3. In other words, since a confirmation result indicating permission to perform step-down charging has been obtained from the occupant of the vehicle 12, the execution of step-down charging, which was determined to be permitted in step S13, is confirmed in step S54. In this case, even if the reduction in charging time is relatively short and the power loss in the power converter 52 is relatively large, step-down charging is performed because the occupant of the vehicle 12 desires step-down charging.

[0078] If the confirmation result indicates that step-down charging is not permitted (NO in S53), the charging control unit 80 cancels the permission for step-down charging in step S13 (S55). The charging control unit 80 then decides to perform normal charging (S56) and terminates the confirmation process (S40) and the series of processes shown in Figure 3. In this case, since the occupant of the vehicle 12 has requested that step-down charging not be performed, normal charging is performed instead of step-down charging.

[0079] As described above, in the charging device 10 of this embodiment, if it is determined that the current condition, which is that the equipment-side current is smaller than the vehicle-side current, and the voltage condition, which is that the equipment-side voltage is larger than the vehicle-side voltage, is met, then step-down charging is permitted. Furthermore, in the charging device 10 of this embodiment, if either or both of the current and voltage conditions are not met, step-down charging is not permitted, and normal charging is performed.

[0080] In this embodiment, the vehicle-side current depends on the state of charge (SOC) of the battery 20 at the start of charging. Therefore, the current condition, which states that the equipment-side current is smaller than the vehicle-side current, is a determination condition that reflects the SOC of the battery 20 at the start of charging. Consequently, in the charging device 10 of this embodiment, compared to a method that determines whether step-down charging is possible based solely on voltage conditions, it becomes possible to appropriately determine whether step-down charging is possible according to the SOC of the battery 20 at the start of charging.

[0081] Embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these embodiments. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention.

[0082] For example, in the above embodiment, after permitting the execution of step-down charging, a confirmation process (S40) was performed if the reduction time was not longer than a predetermined time and the estimated loss amount was greater than or equal to a predetermined threshold. However, for example, the charging control unit 80 may perform the confirmation process (S40) after determining that the reduction time is not longer than a predetermined time, and omit the determination regarding the estimated loss amount. Alternatively, for example, the charging control unit 80 may omit both the determination regarding the reduction time and the determination regarding the estimated loss amount, and perform the confirmation process (S40) after deriving the reduction time. Furthermore, after permitting the execution of step-down charging, the charging control unit 80 may omit the determination regarding the reduction time and proceed to the derivation of the estimated loss amount and the determination regarding the estimated loss amount.

[0083] 10 Charging device 12 Vehicle 14 Power supply equipment 20 Battery 50 Charging port 52 Power converter 60 Control device 70 Processor 72 Memory

Claims

1. A charging port provided in the vehicle and electrically connectable to an external power supply facility; a power converter provided in the current path between the battery mounted in the vehicle and the charging port, capable of stepping down the power supplied from the power supply facility through the charging port and supplying it to the battery; a control device that controls switching between step-down charging, in which the power supplied from the power supply facility is stepped down by the power converter and supplied to the battery, and normal charging, in which the power supplied from the power supply facility is supplied to the battery without stepping down the power; the control device comprises one or more processors; and one or more memories connected to the processors; the processor determines whether the equipment-side current, which is the maximum current that the power supply facility can output, is less than the vehicle-side current, which is the maximum current that the battery can accept from the time the power supply facility starts charging the battery until the battery is fully charged; A charging device that performs a process including: determining whether the equipment-side voltage, which is the maximum voltage that the power supply equipment can output, is greater than the vehicle-side voltage, which is the maximum voltage that the battery can accept from the time the power supply equipment starts charging the battery until the battery is fully charged; if it is determined that the current condition and the voltage condition are met, permitting the execution of step-down charging; and if it is determined that either or both of the current condition and the voltage condition are not met, not permitting the execution of step-down charging and deciding to perform normal charging.

2. The charging device according to claim 1, wherein the processor determines that the current condition and the voltage condition are met and permits the execution of the step-down charging, derives a shortened time which is the time obtained by subtracting the step-down charging time, which is the time required for step-down charging, from the normal charging time, which is the time required for normal charging; and determines that the shortened time is equal to or greater than a predetermined time, decides to execute the step-down charging.

3. The charging device according to claim 1, wherein the processor determines that the current condition and the voltage condition are met and permits the execution of the step-down charging, derives a shortened time which is the time obtained by subtracting the step-down charging time, which is the time required for step-down charging, from the normal charging time, which is the time required for normal charging; if it determines that the shortened time is less than a predetermined time, derives an estimated loss amount which is the amount of power loss that is estimated to occur by the power converter during step-down charging; and if it determines that the estimated loss amount is greater than or equal to a predetermined threshold, decides to execute the normal charging.

4. The charging device according to claim 1, wherein the processor determines that the current condition and the voltage condition are met and permits the execution of the step-down charging, derives a shortened time which is the time obtained by subtracting the step-down charging time, which is the time required for step-down charging, from the normal charging time, which is the time required for normal charging; if it determines that the shortened time is less than a predetermined time, derives an estimated loss amount which is the amount of power loss that is estimated to occur by the power converter during step-down charging; and if it determines that the estimated loss amount is greater than or equal to a predetermined threshold, performs a confirmation process which is the process of confirming with the occupant of the vehicle whether or not to permit the execution of step-down charging.

5. The charging device according to claim 4, wherein the processor performs a process that includes, in the confirmation process, deriving a step-down charging fee, which is the fee for performing step-down charging, based on the estimated amount of loss, and prompting the passenger of the vehicle to input the confirmation result by presenting at least the step-down charging fee.

6. The charging device according to claim 4, wherein the processor performs a process that includes: deciding to perform the step-down charge if it obtains a confirmation result in which it permits the step-down charge; and deciding to perform the normal charge if it obtains a confirmation result in which it does not permit the step-down charge.

Images