Power supply system for vehicle and control method

1 . A power supply system for a vehicle, comprising:

a low voltage circuit provided with a low voltage electric storage;

a high voltage circuit provided with a high voltage electric storage that is higher in voltage than the low voltage electric storage;

a charging circuit that couples the low voltage circuit and the high voltage circuit to each other;

an on-vehicle charger that supplies, when coupled to an external power supply, direct current electric power to at least either of the high voltage circuit or the low voltage circuit;

a coupling state detector that is able to detect that there is coupling between the external power supply and the on-vehicle charger;

an operation receiver that receives an on operation or an off operation performed by a user for starting or stopping the vehicle; and

a charging controller that causes the charging circuit to operate to execute auxiliary charging control for charging the low voltage electric storage with electricity,

wherein, when a soak time representing a period of time elapsed after the off operation has been received is shorter than a first period of time that is determined beforehand, the coupling state detector has detected that there is coupling between the external power supply and the on-vehicle charger, and a remaining amount in the low voltage electric storage is equal to or below a predetermined remaining amount, the charging controller causes the low voltage electric storage to be charged with electricity,

wherein the coupling state detector detects, based on mechanical coupling between a coupling terminal of the external power supply and the on-vehicle charger or based on an operation state at the coupling terminal of the external power supply, whether or not there is coupling between the external power supply and the on-vehicle charger, and

wherein, when the soak time is shorter than the first period of time and the coupling state detector has detected that there is coupling between the external power supply and the on-vehicle charger, the charging controller causes the low voltage electric storage to be charged with electricity in such a manner that a charging speed for the low voltage electric storage is faster than a charging speed for the low voltage electric storage when the external power supply is not coupled to the on-vehicle charger.

2 . The power supply system for the vehicle, according to claim 1 , wherein, when the soak time is shorter than the first period of time, the charging controller uses an amount of electric power equal to or below a value acquired by subtracting an amount of electric power for charging the high voltage electric storage with electricity from an amount of electric power supplied from the external power supply to charge the low voltage electric storage with electricity.

3 . The power supply system for the vehicle, according to claim 1 , wherein, when the soak time is shorter than the first period of time, and the high voltage electric storage is undergoing charging with electricity, the charging controller does not cause the low voltage electric storage to be charged with electricity.

4 . The power supply system for the vehicle, according to claim 1 , wherein, when the soak time is shorter than the first period of time, the low voltage electric storage is undergoing charging with electricity, and the coupling state detector detects that there is release of the coupling between the external power supply and the on-vehicle charger, the charging controller stops charging of the low voltage electric storage with electricity.

5 . The power supply system for the vehicle, according to claim 1 , wherein, after charging of the high voltage electric storage with electricity is completed, the charging controller causes the on-vehicle charger to directly charge the low voltage electric storage with electricity.

6 . The power supply system for the vehicle, according to claim 1 , wherein, after charging of the high voltage electric storage with electricity is completed, and the coupling state detector has detected that there is coupling between the external power supply and the on-vehicle charger, the charging controller causes the low voltage electric storage to be charged with electricity at a voltage for the low voltage electric storage higher than a charging voltage when the high voltage electric storage undergoes charging with electricity.

7 . A control method performed in a power supply system for a vehicle, the control method comprising

causing, when a soak time representing a period of time elapsed after an off operation performed by a user for stopping the vehicle has been received is shorter than a first period of time that is determined beforehand, a coupling state detector in the power supply system has detected that there is coupling between an external power supply and an on-vehicle charger, and a remaining amount in a low voltage electric storage is equal to or below a predetermined remaining amount, a charging controller in the power supply system to charge the low voltage electric storage with electricity,

detecting, by a coupling state detector in the power supply system, based on mechanical coupling between a coupling terminal of the external power supply and the on-vehicle charger or based on an operation state at the coupling terminal of the external power supply, whether or not there is coupling between the external power supply and the on-vehicle charger, and

when the soak time is shorter than the first period of time, and the coupling state detector has detected that there is coupling between the external power supply and the on-vehicle charger, causing, by the charging controller, the low voltage electric storage to be charged with electricity in such a manner that a charging speed for the low voltage electric storage is faster than a charging speed for the low voltage electric storage when the external power supply is not coupled to the on-vehicle charger.