Patent Publication Number: US-2021178931-A1

Title: Charging system and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2019-224146 filed on Dec. 12, 2019, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The disclosure relates to a charging system capable of charging a battery of a vehicle with electric power supplied from an external power supply. The disclosure relates also to a vehicle. 
     In vehicles such as an electric vehicle and a plug-in hybrid vehicle, a battery mounted on the vehicle is chargeable via a charger coupled to an external power supply (for example, Japanese Unexamined Patent Application Publication No. 2016-86550). 
     SUMMARY 
     An aspect of the disclosure provides a charging system including a charging controller and an estimated completion time deriver. The charging controller is configured to adjust a temperature of an on-board battery with a heater so that the temperature of the battery is kept equal to or higher than a predetermined temperature. The battery is chargeable with electric power supplied from a power supply outside a vehicle. The charging controller is configured to charge the battery with charging power excluding temperature adjustment power from permitted suppliable power. The temperature adjustment power is electric power consumed by the heater. The permitted suppliable power is permitted electric power supplied from the power supply to the vehicle. The estimated completion time deriver is configured to derive an estimated completion time on a basis of an estimated value of the permitted suppliable power in a future and an estimated value of the temperature adjustment power that is derived on a basis of an estimated value of an outside air temperature in the future. The estimated completion time is a time when charging is predicted to complete. 
     An aspect of the disclosure provides a vehicle including a charging controller and an estimated completion time deriver. The charging controller is configured to adjust a temperature of a battery with a heater so that the temperature of the battery is kept equal to or higher than a predetermined temperature. The battery is chargeable with electric power supplied from a power supply outside the vehicle. The charging controller is configured to charge the battery with charging power excluding temperature adjustment power from permitted suppliable power. The temperature adjustment power is electric power consumed by the heater. The permitted suppliable power is permitted electric power supplied from the power supply. The estimated completion time deriver is configured to derive an estimated completion time on a basis of an estimated value of the permitted suppliable power in a future and an estimated value of the temperature adjustment power that is derived on a basis of an estimated value of an outside air temperature in the future. The estimated completion time is a time when charging is predicted to complete. 
     An aspect of the disclosure provides a charging system including circuitry. The circuitry is configured to adjust a temperature of an on-board battery with a heater so that the temperature of the battery is kept equal to or higher than a predetermined temperature. The battery is chargeable with electric power supplied from a power supply outside a vehicle. The circuitry is configured to charge the battery with charging power excluding temperature adjustment power from permitted suppliable power. The temperature adjustment power is electric power consumed by the heater. The permitted suppliable power is permitted electric power supplied from the power supply to the vehicle. The circuitry is configured to derive an estimated completion time on a basis of an estimated value of the permitted suppliable power in a future and an estimated value of the temperature adjustment power that is derived on a basis of an estimated value of an outside air temperature in the future. The estimated completion time is a time when charging is predicted to complete. 
     A fourth aspect of the disclosure provides a vehicle including circuitry. The circuitry is configured to adjust a temperature of a battery with a heater so that the temperature of the battery is kept equal to or higher than a predetermined temperature. The battery is chargeable with electric power supplied from a power supply outside the vehicle. The circuitry is configured to charge the battery with charging power excluding temperature adjustment power from permitted suppliable power. The temperature adjustment power is electric power consumed by the heater. The permitted suppliable power is permitted electric power supplied from the power supply. The circuitry is configured to derive an estimated completion time on a basis of an estimated value of the permitted suppliable power in a future and an estimated value of the temperature adjustment power that is derived on a basis of an estimated value of an outside air temperature in the future. The estimated completion time is a time when charging is predicted to complete. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate an embodiment and, together with the specification, serve to explain the principles of the disclosure. 
         FIG. 1  is a schematic diagram illustrating the configuration of a charging system according to an embodiment of the disclosure; 
         FIG. 2A  to  FIG. 2D  are diagrams illustrating derivation of an estimated completion time, in which  FIG. 2A  illustrates a temporal change in an estimated value of permitted suppliable power and a temporal change in an estimated value of temperature adjustment power,  FIG. 2B  illustrates a temporal change in an estimated outside air temperature,  FIG. 2C  illustrates a temporal change in an estimated value of a battery temperature, and  FIG. 2D  illustrates a temporal change in an estimated value of an SOC; 
         FIG. 3  is a flowchart illustrating a flow of an operation of an estimated completion time deriver; 
         FIG. 4  is a flowchart illustrating a flow of a pre-process; 
         FIG. 5  is a flowchart illustrating a flow of an estimated completion time deriving process; 
         FIG. 6A  and  FIG. 6B  are diagrams illustrating an operation of an estimated completion time corrector, in which  FIG. 6A  illustrates an example of a temporal change in the estimated outside air temperature and a temporal change in an actual value of an outside air temperature (actual outside air temperature), and  FIG. 6B  illustrates an example of a temporal change in the estimated value of the permitted suppliable power and a temporal change in the estimated value of the temperature adjustment power; and 
         FIG. 7  is a flowchart illustrating a flow of the operation of the estimated completion time corrector. 
     
    
    
     DETAILED DESCRIPTION 
     Depending on an outside air temperature during charging, electric power is consumed to adjust the temperature of a battery of a vehicle and electric power for use in the charging fluctuates. Therefore, the accuracy of derivation of an estimated completion time is low. The estimated completion time is a time when the charging is predicted to complete. 
     It is desirable to provide a charging system and a vehicle in which the accuracy of derivation of an estimated charging completion time can be improved. 
     In the following, an embodiment of the disclosure is described in detail with reference to the accompanying drawings. Note that the following description is directed to an illustrative example of the disclosure and not to be construed as limiting to the disclosure. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting to the disclosure. Further, elements in the following embodiment which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Throughout the present specification and the drawings, elements having substantially the same function and configuration are denoted with the same numerals to avoid any redundant description. 
       FIG. 1  is a schematic diagram illustrating the configuration of a charging system  1  according to the embodiment. Components and processes relating to the embodiment are described below in detail and description is omitted for components and processes that do not relate to the embodiment. 
     The charging system  1  includes a vehicle  10 , a power manager  12 , a charger  14 , a charging cable  16 , a terminal  18 , and an outside air temperature estimator  20 . Examples of the vehicle  10  include an electric vehicle and a plug-in hybrid vehicle. The vehicle  10  includes a battery  30  that supplies electric power to a motor (not illustrated) serving as a drive source. The vehicle  10  has a charging inlet  32  coupled to the battery  30 . For example, the charging inlet  32  is provided on the side of a body of the vehicle  10 . 
     The power manager  12  includes a power supply  40  such as a power generation facility. Examples of the power manager  12  include an electric-power company. Examples of the power supply  40  include a power plant. The charger  14  is electrically coupled to the power supply  40  via, for example, a power grid (not illustrated) and an electric switchboard (not illustrated). The charger  14  can receive electric power supplied from the power supply  40 . 
     A charging connector  50  is provided at one end of the charging cable  16 . The charging connector  50  can be coupled to the charging inlet  32  of the vehicle  10 . A power plug  52  is provided at the other end of the charging cable  16 . The power plug  52  can be coupled to the charger  14 . The charger  14  can supply electric power of the power supply  40  to the charging inlet  32  of the vehicle  10  through the charging cable  16 . The battery  30  of the vehicle  10  is chargeable with the electric power supplied to the charging inlet  32  from the external power supply  40 . The charging cable  16  has a control box  54 . The control box  54  detects the occurrence of electric leakage, overcurrent, and overheat during charging and stops the charging when any one of those phenomena is detected. 
     Examples of the charger  14  include a household charger provided at a general house, and a service charger provided at a charging station. The charger  14  includes a charging unit  60  and a charging outlet  62 . The charging unit  60  is coupled to the power grid. The charging outlet  62  is coupled to the charging unit  60 . The power plug  52  of the charging cable  16  is coupled to the charging outlet  62 . The charging unit  60  supplies electric power of the power supply  40  to the vehicle  10  through the charging outlet  62  and the charging cable  16 . 
     Examples of the terminal  18  include a smartphone of an owner of the vehicle  10 . The terminal  18  is communicable with the vehicle  10  and the charger  14  via either one of a cellular network and a wireless communication network such as a wireless LAN. Although detailed description is given later, the charging system  1  derives an estimated completion time when the charging of the battery  30  is predicted to complete. The charging system  1  reports the derived estimated completion time to the owner of the vehicle  10  via, for example, a display of the terminal  18 . 
     The outside air temperature estimator  20  derives a temporal change in an estimated value of an outside air temperature in the future. Examples of the outside air temperature estimator  20  include a meteorological bureau. The estimated value of the outside air temperature may hereinafter be referred to as “estimated outside air temperature”. The outside air temperature estimator  20  can transmit the temporal change in the estimated outside air temperature in the future via a communication network such as the Internet. The vehicle  10  can receive the temporal change in the estimated outside air temperature in the future from the outside air temperature estimator  20 . 
     The power manager  12  derives a regional base profile showing a temporal change in typical power consumption in a predetermined region. The region is a region managed by the power manager  12 , such as New York State, but is not limited to this example. The region is at least set to an area in the same time zone. For example, the power manager  12  derives a regional base profile of a region including a building having the charger  14 . 
     The regional base profile shows a temporal change in power consumption on a 24-hour (1-day) basis. The regional base profile is derived based on a record of power consumption within a predetermined period such as one month. That is, the regional base profile roughly shows a temporal change in daily power consumption in a target region (for example, New York State) and a target period (for example, February). 
     For example, the power manager  12  derives regional base profiles of individual regions every month. The power manager  12  can transmit the regional base profiles of individual regions via a communication network such as the Internet. The vehicle  10  can receive the regional base profile (target regional base profile) of the region including the building having the charger  14 . The target regional base profile corresponds to an estimated temporal change in power consumption in the building having the charger  14 . The vehicle  10  may receive the regional base profile via the charger  14 . 
     A predetermined contract amperage is set in the building having the charger  14 . The contract amperage is an upper limit value of a current agreed in a contract between the power manager  12  and the building (demander). Electric power obtained by multiplying the contract amperage by a nominal value of a received voltage may hereinafter be referred to as “contract demand power”. The contract demand power is an upper limit value of electric power consumable in the building. 
     In the building having the charger  14 , electric power is also supplied to loads (for example, household appliances and other electric devices) other than the charger  14 . Therefore, permitted electric power to be supplied from the charger  14  to the vehicle  10  corresponds to electric power obtained by subtracting power consumption of the loads other than the charger  14  in the building from the contract demand power. The permitted electric power to be supplied from the charger  14  to the vehicle  10  may hereinafter be referred to as “permitted suppliable power”. For example, the permitted suppliable power is derived by subtracting power consumption in the target regional base profile from the contract demand power. That is, the charger  14  (charging unit  60 ) can supply such permitted suppliable power to the vehicle  10 . 
     In addition to the battery  30  and the charging inlet  32 , the vehicle  10  includes a heater  70 , a battery temperature sensor  72 , an outside air temperature sensor  74 , a communicator  76 , and a battery controller  78 . 
     The heater  70  is coupled to the charging inlet  32 . The heater  70  warms the battery  30  with electric power (electric power of the external power supply  40 ) supplied from the charger  14  to the charging inlet  32 . The temperature of the battery  30  may hereinafter be referred to as “battery temperature”. Adjustment of the battery temperature may be referred to as “temperature adjustment”. The electric power consumed by the heater  70  may be referred to as “temperature adjustment power”. 
     The battery temperature sensor  72  detects the battery temperature. The outside air temperature sensor  74  detects the outside air temperature. The communicator  76  is communicable with, for example, the terminal  18 , the power manager  12 , and the outside air temperature estimator  20 . 
     The battery controller  78  is a semiconductor integrated circuit including a central processing unit (CPU), a ROM that stores programs and other data, and a RAM serving as a working area. The battery controller  78  executes the programs to function as a charging controller  80 , an SOC deriver  82 , an estimated completion time deriver  84 , and an estimated completion time corrector  86 . That is, the battery controller  78  is a computer that functions as the charging controller  80 , the SOC deriver  82 , the estimated completion time deriver  84 , and the estimated completion time corrector  86  by cooperation between hardware and software. 
     The charging controller  80  controls the battery  30  and the heater  70 . To charge the battery  30 , the power plug  52  of the charging cable  16  is first coupled to the charging outlet  62  of the charger  14  and the charging connector  50  is coupled to the charging inlet  32  of the vehicle  10 . When the vehicle  10  and the charger  14  receive operation for an instruction to start charging, a charging start instruction is transmitted to the battery controller  78 . In response to the charging start instruction, the charging controller  80  starts to charge the battery  30 . 
     The battery  30  is not appropriately charged unless the battery temperature is equal to or higher than a predetermined temperature. After the reception of the charging start instruction, the charging controller  80  adjusts the battery temperature by using the heater  70  so that the battery temperature is kept equal to or higher than the predetermined temperature. That is, the predetermined temperature corresponds to a charging permission temperature at which the charging of the battery  30  is permitted. 
     The charging controller  80  charges the battery  30  with electric power excluding the temperature adjustment power from the permitted suppliable power of the charger  14 . The electric power for use in the charging of the battery  30  (electric power to be transferred to the battery  30 ) may hereinafter be referred to as “charging power”. 
     When the battery temperature is lower than the predetermined temperature at the time of reception of the charging start instruction, the charging controller  80  performs temperature adjustment in such a manner that the permitted suppliable power to the charging inlet  32  is not transferred to the battery  30  but is transferred to the heater  70  alone until the battery temperature reaches the predetermined temperature. Such temperature adjustment may hereinafter be referred to as “initial temperature adjustment”. After the initial temperature adjustment is finished, the charging controller  80  starts to transfer the permitted suppliable power to the battery  30  (charge the battery  30 ). 
     When the battery temperature is equal to or higher than the predetermined temperature at the time of reception of the charging start instruction, the charging controller  80  promptly starts to transfer the permitted suppliable power to the battery  30  without performing the initial temperature adjustment. 
     While the battery  30  is being actually charged (during charging), the battery temperature may decrease depending on the outside air temperature due to heat dissipation from the battery  30 . In this case, the charging controller  80  charges the battery  30  while performing temperature adjustment by transferring part of the permitted suppliable power to the heater  70  so that the battery temperature is kept equal to or higher than the predetermined temperature. To distinguish this temperature adjustment from the initial temperature adjustment, the temperature adjustment during actual charging may hereinafter be referred to as “intermediate temperature adjustment” for convenience. 
     The SOC deriver  82  derives a state of charge (SOC) of the battery  30 . The SOC is a level of charging of the battery  30  and is represented in units of percentage (100% indicates a fully charged state). 
     The estimated completion time deriver  84  derives an estimated completion time of the charging of the battery  30 . The estimated completion time deriver  84  derives the estimated completion time when the supply of electric power from the power supply  40  to the vehicle  10  has become ready. For example, the estimated completion time deriver  84  derives the estimated completion time in response to reception of the charging start instruction. 
     The estimated completion time deriver  84  derives the estimated completion time based on an estimated value of the permitted suppliable power in the future and an estimated value of the temperature adjustment power in the future. The estimated completion time deriver  84  is described later in detail. 
     In response to an increase in the possibility that the charging completion time may deviate from the estimated completion time, the estimated completion time corrector  86  derives and reports an estimated completion time at a current time again. The estimated completion time corrector  86  is described later in detail. 
       FIG. 2A  to  FIG. 2D  are diagrams illustrating the derivation of the estimated completion time.  FIG. 2A  illustrates a temporal change in the estimated value of the permitted suppliable power and a temporal change in the estimated value of the temperature adjustment power.  FIG. 2B  illustrates a temporal change in the estimated outside air temperature.  FIG. 2C  illustrates a temporal change in an estimated value of the battery temperature.  FIG. 2D  illustrates a temporal change in an estimated value of the SOC. In  FIG. 2A  to  FIG. 2D , a time T 10  is a current time when a charging start instruction is received. In  FIG. 2A , a solid line A 10  indicates the temporal change in the estimated value of the permitted suppliable power. A two-dot chain line A 12  indicates the temporal change in the estimated value of the temperature adjustment power. A chain line A 14  indicates the contract demand power. An arrow A 16  indicates an example of power consumption in the regional base profile. 
     As illustrated in  FIG. 2A , the estimated completion time deriver  84  acquires, from the power manager  12 , a regional base profile corresponding to a temporal change in an estimated value of future power consumption of the loads other than the charger  14  in the building. The estimated completion time deriver  84  derives a temporal change in the estimated value of the permitted suppliable power in the future (solid line A 10 ) by subtracting power consumption at each time in the regional base profile (arrow A 16 ) from the contract demand power of the building having the charger  14  (chain line A 14 ). 
     As illustrated in  FIG. 2C , the battery temperature is lower than the predetermined temperature (charging permission temperature) at the current time when the charging start instruction is received (time T 10 ). In this case, the initial temperature adjustment is performed as illustrated in  FIG. 2A . The estimated completion time deriver  84  derives a power amount related to the initial temperature adjustment (initial temperature adjustment power amount). For example, the estimated completion time deriver  84  derives a battery temperature difference by subtracting a current battery temperature from the predetermined temperature as indicated by an arrow A 20  in  FIG. 2C . The estimated completion time deriver  84  derives the initial temperature adjustment power amount by multiplying the battery temperature difference by parameters of the battery  30  (specific heat, volume, and specific gravity of the battery  30 ) and by setting a unit. 
     The estimated completion time deriver  84  derives an estimated initial temperature adjustment completion time when the initial temperature adjustment is predicted to complete. For example, the estimated completion time deriver  84  sets the estimated initial temperature adjustment completion time to a time (for example, a time T 11 ) when a power amount obtained by accumulating the estimated value of the permitted suppliable power from the current time T 10  becomes larger than the initial temperature adjustment power amount. At the estimated initial temperature adjustment completion time, the battery temperature is predicted to become equal to or higher than the predetermined temperature. 
     As illustrated in  FIG. 2B , the estimated completion time deriver  84  acquires a temporal change in the estimated outside air temperature in the future from the outside air temperature estimator  20 . As illustrated in  FIG. 2A , the estimated completion time deriver  84  derives a temporal change (two-dot chain line A 12 ) in temperature adjustment power in the future after the initial temperature adjustment (that is, intermediate temperature adjustment power in the future) based on the temporal change in the estimated outside air temperature in the future in  FIG. 2B . For example, the estimated completion time deriver  84  derives a heat dissipation temperature by subtracting the estimated outside air temperature from the predetermined temperature (charging permission temperature) at each time after the initial temperature adjustment. The heat dissipation temperature indicates a battery temperature that may decrease due to heat dissipation caused by the outside air temperature. The estimated completion time deriver  84  derives a power amount related to the intermediate temperature adjustment by multiplying the heat dissipation temperature at each time after the initial temperature adjustment by the parameters of the battery  30  (specific heat, volume, and specific gravity of the battery  30 ) and a predetermined heat insulation coefficient and by setting a unit. The estimated completion time deriver  84  converts the power amount into intermediate temperature adjustment power as indicated by an arrow A 22  in  FIG. 2A . 
     As illustrated in  FIG. 2D , the estimated completion time deriver  84  acquires a current SOC from the SOC deriver  82 . As indicated by an arrow A 24  in  FIG. 2D , the estimated completion time deriver  84  derives an expected charging amount by subtracting the current SOC from a target SOC. For example, the target SOC is set to 90% or higher. The expected charging amount indicates a lack of the power amount in the battery  30 . 
     As illustrated in  FIG. 2A , the estimated completion time deriver  84  derives an estimated value of the charging power indicated by an arrow A 26  in  FIG. 2A  by subtracting the estimated value of the temperature adjustment power from the estimated value of the permitted suppliable power at each time after the initial temperature adjustment. The estimated completion time deriver  84  accumulates the derived estimated value of the charging power from the estimated initial temperature adjustment completion time (time T 11 ) to the future. The power amount obtained by accumulating the estimated value of the charging power to the future may hereinafter be referred to as “cumulative power amount”. 
     As illustrated in  FIG. 2A  and  FIG. 2D , the estimated completion time deriver  84  sets an estimated completion time to a time when the cumulative power amount is larger than the expected charging amount (time T 12 ). 
       FIG. 2A  to  FIG. 2D  illustrate the case where the battery temperature is lower than the predetermined temperature at the current time T 10  (the initial temperature adjustment is performed). When the battery temperature is equal to or higher than the predetermined temperature at the current time T 10 , the estimated completion time deriver  84  may skip the initial temperature adjustment. In this case, the estimated completion time deriver  84  may derive the estimated completion time (time T 12 ) under the assumption that the estimated initial temperature adjustment completion time (time T 11 ) is the current time in  FIG. 2A  to  FIG. 2D . 
       FIG. 3  is a flowchart illustrating a flow of the operation of the estimated completion time deriver  84 . The estimated completion time deriver  84  performs a series of processes in  FIG. 3  when the supply of electric power from the power supply  40  to the vehicle  10  has become ready. For example, the estimated completion time deriver  84  performs the series of processes in  FIG. 3  in response to reception of a charging start instruction. 
     The estimated completion time deriver  84  first performs a pre-process prior to deriving an estimated completion time (S 100 ). In the pre-process, various pieces of information are acquired for the derivation of the estimated completion time. A flow of the pre-process is described later in detail. 
     Next, the estimated completion time deriver  84  performs an estimated completion time deriving process for deriving the estimated completion time by using various pieces of information acquired in the pre-process (S 110 ). A flow of the estimated completion time deriving process is described later in detail. 
     Next, the estimated completion time deriver  84  transmits the estimated completion time derived in the estimated completion time deriving process to the terminal  18  to report the estimated completion time to the owner of the vehicle  10  (S 120 ). Then, the estimated completion time deriver  84  terminates the series of processes. 
       FIG. 4  is a flowchart illustrating the flow of the pre-process (S 100 ). The estimated completion time deriver  84  first acquires a regional base profile from the power manager  12  (S 200 ). Next, the estimated completion time deriver  84  derives a temporal change in the estimated value of the permitted suppliable power based on the regional base profile (S 210 ). For example, the estimated completion time deriver  84  acquires the contract demand power from the charger  14 . The estimated completion time deriver  84  derives the temporal change in the estimated value of the permitted suppliable power by subtracting power consumption in the regional base profile from the contract demand power. 
     Next, the estimated completion time deriver  84  acquires a current SOC derived by the SOC deriver  82  (S 220 ). Next, the estimated completion time deriver  84  derives an expected charging amount by subtracting the current SOC from a target SOC (for example, 90%) (S 230 ). 
     Next, the estimated completion time deriver  84  acquires a temporal change in the estimated outside air temperature from the outside air temperature estimator  20  (S 240 ). Next, the estimated completion time deriver  84  acquires a current time (S 250 ). Next, the estimated completion time deriver  84  acquires a current battery temperature from the battery temperature sensor  72  (S 260 ) and terminates the series of processes. 
       FIG. 5  is a flowchart illustrating the flow of the estimated completion time deriving process (S 110 ). The estimated completion time deriver  84  first determines whether the current battery temperature is equal to or higher than the predetermined temperature (charging permission temperature) (S 300 ). 
     When the current battery temperature is lower than the predetermined temperature (NO in S 300 ), the estimated completion time deriver  84  derives a battery temperature difference by subtracting the current battery temperature from the predetermined temperature (S 310 ). Next, the estimated completion time deriver  84  derives an initial temperature adjustment power amount based on the battery temperature difference (S 320 ). Next, the estimated completion time deriver  84  derives an estimated initial temperature adjustment completion time based on the initial temperature adjustment power amount (S 330 ). Next, the estimated completion time deriver  84  assumes the estimated initial temperature adjustment completion time as a time Tk (S 340 ) and proceeds to a process of Step S 360 . 
     When the current battery temperature is equal to or higher than the predetermined temperature (YES in S 300 ), the estimated completion time deriver  84  assumes the current time as the time Tk (S 350 ) and proceeds to the process of Step S 360 . 
     In Step S 360 , the estimated completion time deriver  84  extracts an estimated outside air temperature at the time Tk from the temporal change in the estimated outside air temperature (S 360 ). Next, the estimated completion time deriver  84  derives an estimated value of the intermediate temperature adjustment power at the time Tk based on the estimated outside air temperature at the time Tk (S 370 ). 
     Next, the estimated completion time deriver  84  extracts an estimated value of the permitted suppliable power at the time Tk from the temporal change in the estimated value of the permitted suppliable power (S 380 ). 
     Next, the estimated completion time deriver  84  derives an estimated value of the charging power at the time Tk by subtracting the estimated value of the intermediate temperature adjustment power at the time Tk from the estimated value of the permitted suppliable power at the time Tk (S 390 ). 
     Next, the estimated completion time deriver  84  derives a charging power amount from the time Tk to a time Tk+α (S 400 ). For example, α is 1 minute but is not limited to this example. That is, the estimated completion time deriver  84  derives a charging power amount within a predetermined period (1 minute) from the time Tk. 
     Next, the estimated completion time deriver  84  derives a cumulative power amount based on the charging power amount in Step S 400  (S 410 ). For example, the estimated completion time deriver  84  obtains a cumulative power amount at the current time by adding the charging power amount within the predetermined period in Step S 400  to a previous cumulative power amount derived in Step S 410 . When the process of Step S 410  is performed for the first time, the estimated completion time deriver  84  sets the charging power amount within the predetermined period in Step S 400  as the cumulative power amount at the current time. 
     Next, the estimated completion time deriver  84  determines whether the cumulative power amount derived in Step S 410  is larger than the expected charging amount (S 420 ). When the cumulative power amount is larger than the expected charging amount (YES in S 420 ), the estimated completion time deriver  84  sets the time Tk+α as the estimated completion time (S 430 ) and terminates the series of processes. 
     When the cumulative power amount is not larger than the expected charging amount (NO in S 420 ), the estimated completion time deriver  84  sets the time Tk+α as the time Tk (S 440 ) and repeats the process of Step S 360  and the subsequent processes. That is, the estimated completion time deriver  84  accumulates the charging power to the future until the cumulative power amount becomes larger than the expected charging amount, and sets the estimated completion time to a time when the cumulative power amount is larger than the expected charging amount. 
       FIG. 6A  and  FIG. 6B  are diagrams illustrating an operation of the estimated completion time corrector  86 .  FIG. 6A  illustrates an example of a temporal change in the estimated outside air temperature and a temporal change in an actual value of the outside air temperature (actual outside air temperature).  FIG. 6B  illustrates an example of a temporal change in the estimated value of the permitted suppliable power and a temporal change in the estimated value of the temperature adjustment power. In  FIG. 6A  and  FIG. 6B , a time T 21  during charging is a current time. In  FIG. 6A , a chain line A 30  indicates a temporal change in the estimated outside air temperature that has been used for the derivation of the estimated completion time in response to the reception of the charging start instruction. A solid line A 32  indicates the temporal change in the actual value of the outside air temperature. A two-dot chain line A 34  indicates a temporal change in the estimated outside air temperature that is acquired at the current time T 21 . In  FIG. 6B , a solid line A 40  indicates the temporal change in the estimated value of the permitted suppliable power. A solid line A 42  indicates a temporal change in the estimated value of the temperature adjustment power that has been used for the derivation of the estimated completion time in response to the reception of the charging start instruction. A solid line A 44  indicates a temporal change in the estimated value of the temperature adjustment power that is derived at the current time T 21 . The time when the estimated completion time is derived in response to the reception of the charging start instruction may hereinafter be referred to as “originally”. 
     As illustrated in  FIG. 6A , the actual outside air temperature (solid line A 32 ) may deviate from the temporal change in the originally estimated outside air temperature (chain line A 30 ) along with an elapse of time. In the example of  FIG. 6A , a current outside air temperature (outside air temperature B 2 ) is lower than an estimated outside air temperature (outside air temperature B 1 ) at the current time T 21  within the temporal change in the originally estimated outside air temperature. When the actual outside air temperature deviates from the originally estimated outside air temperature, the charging completion time may deviate from the originally estimated completion time. 
     The estimated completion time corrector  86  acquires an actual value of the current outside air temperature from the outside air temperature sensor  74 . As indicated by an arrow A 36  in  FIG. 6A , the estimated completion time corrector  86  derives, as an outside air temperature difference, an absolute value of a difference between the actual value of the current outside air temperature and an estimated outside air temperature at the current time within the temporal change in the estimated outside air temperature that has been used for the derivation of the estimated completion time. 
     When the outside air temperature difference is equal to or larger than a predetermined value, the estimated completion time corrector  86  acquires a temporal change (two-dot chain line A 34 ) in a future outside air temperature estimated at the current time. As indicated by the solid line A 44  in  FIG. 6B , the estimated completion time corrector  86  derives again a temporal change in the estimated value of the temperature adjustment power based on the temporal change in the future outside air temperature estimated at the current time. 
     In  FIG. 6B , the cumulative power amount of the charging power based on the temporal change in the originally estimated value of the temperature adjustment power is hatched obliquely. In  FIG. 6B , the originally estimated completion time is a time T 22 . 
     As indicated by vertical hatching in  FIG. 6B , the estimated completion time corrector  86  derives a cumulative power amount of the charging power based on the temporal change in the estimated value of the temperature adjustment power at the current time (time T 21 ). Further, the estimated completion time corrector  86  derives a current expected charging amount based on a current SOC. The estimated completion time corrector  86  derives, as an estimated completion time at the current time, a time when the cumulative power amount is larger than the current expected charging amount (time T 23 ). The estimated completion time corrector  86  reports the derived estimated completion time again. For example, the estimated completion time corrector  86  reports the estimated completion time at the current time to the owner of the vehicle  10  again by displaying the estimated completion time on the display of the terminal  18 . 
     After the estimated completion time is reported again during the charging, the estimated completion time corrector  86  derives an outside air temperature difference based on the temporal change in the estimated outside air temperature at the time of derivation of the estimated completion time reported again. When the outside air temperature difference is equal to or larger than the predetermined value, the estimated completion time corrector  86  derives and reports the estimated completion time again. That is, until the charging is completed, the estimated completion time corrector  86  repeats the determination as to whether the outside air temperature difference is equal to or larger than the predetermined value. 
       FIG. 7  is a flowchart illustrating a flow of the operation of the estimated completion time corrector  86 . After the estimated completion time is reported (S 120 ) (in other words, after the series of processes in  FIG. 3  is terminated), the estimated completion time corrector  86  repeats a series of processes in  FIG. 7  by interrupt control of every predetermined control period. For example, the predetermined control period is 1 minute but is not limited to this example. 
     The estimated completion time corrector  86  first acquires a current time (S 500 ). Next, the estimated completion time corrector  86  extracts an estimated outside air temperature at the current time based on the temporal change in the estimated outside air temperature that has been used for the derivation of the estimated completion time (S 510 ). 
     Next, the estimated completion time corrector  86  acquires an actual value of a current outside air temperature from the outside air temperature sensor  74  (S 520 ). Next, the estimated completion time corrector  86  derives, as the outside air temperature difference, an absolute value of a difference between the estimated outside air temperature at the current time and the actual value of the current outside air temperature (S 530 ). 
     Next, the estimated completion time corrector  86  determines whether the outside air temperature difference is equal to or larger than the predetermined value (S 540 ). When the outside air temperature difference is smaller than the predetermined value (NO in S 540 ), the estimated completion time corrector  86  terminates the series of processes. 
     When the outside air temperature difference is equal to or larger than the predetermined value (YES in S 540 ), the estimated completion time corrector  86  performs a process similar to the pre-process in  FIG. 4  (S 100 ). Next, the estimated completion time corrector  86  performs a process similar to the estimated completion time deriving process in  FIG. 5  (S 110 ). Thus, an estimated completion time at the current time is derived based on the estimated outside air temperature derived at the current time. 
     Next, the estimated completion time corrector  86  transmits the derived estimated completion time to the terminal  18  to report the estimated completion time to the owner of the vehicle  10  again (S 570 ). That is, when the outside air temperature difference is equal to or larger than the predetermined value, there is a strong possibility that the estimated completion time may deviate from the already reported estimated completion time. Therefore, the estimated completion time corrector  86  derives and reports the estimated completion time at the current time again. 
     As described above, in the charging system  1  of the embodiment, the estimated completion time deriver  84  of the vehicle  10  derives the estimated completion time based on the estimated value of the permitted suppliable power in the future and the estimated value of the temperature adjustment power that is derived based on the estimated value of the outside air temperature in the future. For example, the estimated completion time deriver  84  sets the estimated completion time to the time when the cumulative power amount is larger than the expected charging amount. The cumulative power amount is obtained by accumulating the estimated value of the charging power to the future. The estimated value of the charging power is obtained by subtracting the estimated value of the temperature adjustment power from the estimated value of the permitted suppliable power. 
     According to the charging system  1  of the embodiment, the estimated value of the temperature adjustment power in the future and the estimated value of the charging power in the future can be derived accurately. Thus, the accuracy of the derivation of the estimated charging completion time can be improved. 
     The estimated completion time deriver  84  of the charging system  1  of the embodiment derives the estimated completion time and reports the derived estimated completion time when the supply of electric power from the power supply  40  to the vehicle  10  has become ready. In the charging system  1  of the embodiment, the owner of the vehicle  10  can recognize the estimated completion time at the time of operation for an instruction to start charging. 
     When the absolute value of the difference between the actual value of the current outside air temperature and the estimated value of the outside air temperature at the current time within the temporal change in the estimated value of the outside air temperature that has been used for the derivation of the estimated completion time is equal to or larger than the predetermined value, the estimated completion time corrector  86  of the charging system  1  of the embodiment derives the estimated completion time at the current time again and reports the derived estimated completion time. In the charging system  1  of the embodiment, when the outside air temperature deviates from the estimated value, the owner of the vehicle  10  can recognize that the estimated completion time has been changed. Further, the owner can recognize a more accurate estimated completion time. 
     Although the embodiment of the disclosure has been described above with reference to the accompanying drawings, the embodiment of the disclosure is not limited to the embodiment described above. It is understood that a person having ordinary skill in the art may conceive various modifications or revisions within the scope of claims and those modifications or revisions also belong to the technical scope of the embodiment of the disclosure. 
     In the embodiment described above, the battery controller  78  in the vehicle  10  functions as the estimated completion time deriver  84  and the estimated completion time corrector  86 . The computer that functions as the estimated completion time deriver  84  and the estimated completion time corrector  86  may be provided in either one of the charger  14  and the control box  54  of the charging cable  16 . In this case, the estimated completion time deriver  84  and the estimated completion time corrector  86  may execute the processes by acquiring various pieces of information such as the battery temperature, the actual value of the outside air temperature, and the current SOC from the vehicle  10  through communication. 
     In the embodiment described above, the temporal change in the estimated outside air temperature is acquired from the outside air temperature estimator  20 . The temporal change in the estimated outside air temperature may be acquired from, for example, a different weather forecasting organization instead of being acquired from the outside air temperature estimator  20 . 
     In the embodiment described above, the estimated completion time is reported to the terminal  18  such as a smartphone. The estimated completion time may be reported to, for example, a television set in a house instead of being reported to the terminal  18 . 
     In the charger  14  of the embodiment described above, the power plug  52  of the charging cable  16  is coupled to the charging outlet  62 . The charger  14  may include the charging cable  16 . 
     The battery controller  78  illustrated in  FIG. 1  can be implemented by circuitry including at least one semiconductor integrated circuit such as at least one processor (e.g., a central processing unit (CPU)), at least one application specific integrated circuit (ASIC), and/or at least one field programmable gate array (FPGA). At least one processor can be configured, by reading instructions from at least one machine readable tangible medium, to perform all or a part of functions of the battery controller  78  including the charging controller  80 , the SOC deriver  82 , the estimated completion time deriver  84 , and the estimated completion time corrector  86 . Such a medium may take many forms, including, but not limited to, any type of magnetic medium such as a hard disk, any type of optical medium such as a CD and a DVD, any type of semiconductor memory (i.e., semiconductor circuit) such as a volatile memory and a non-volatile memory. The volatile memory may include a DRAM and a SRAM, and the non-volatile memory may include a ROM and a NVRAM. The ASIC is an integrated circuit (IC) customized to perform, and the FPGA is an integrated circuit designed to be configured after manufacturing in order to perform, all or a part of the functions of the modules illustrated in  FIG. 1 .