Conventionally, a vehicle such as a hybrid vehicle, an electric vehicle and a fuel-cell vehicle using an electric motor as a driving source has been known. Such a vehicle is provided with a power storage mechanism such as a battery for storing electric power supplied to the electric motor. The electric power generated during regenerative braking or generated by a power generator mounted in the vehicle is stored in the battery.
There are also some vehicles in which electric power is supplied from a power supply external to the vehicle such as a household power supply to the battery mounted in the vehicle for charging the battery. The outlet disposed on the house is coupled to the connector provided on the vehicle via a cable to supply electric power from the household power supply to the battery of the vehicle. The vehicle having a battery mounted therein and charged by the power supply provided external to the vehicle is hereinafter also referred to as a plug-in vehicle.
The standards of the plug-in vehicle are defined in “Electric Vehicle Conductive Charging System General Requirements” (Non-Patent Document 1) in Japan and in “SAE Electric Vehicle Conductive Charge Coupler” (Non-Patent Document 2) in the United States.
By way of example, “Electric Vehicle Conductive Charging System General Requirements” and “SAE Electric Vehicle Conductive Charge Coupler” define the standards regarding a control pilot. The control pilot has a function of transmitting a square wave signal (hereinafter also referred to as a pilot signal) from an oscillator to a control pilot line, to thereby indicate to the vehicle that an EVSE (Electric Vehicle Supply Equipment) can supply energy (electric power). The EVSE is an apparatus for connecting an external power supply to the vehicle. For example, when the plug of the EVSE is connected to the power supply external to the vehicle and the connector of the EVSE is connected to the connector provided on the vehicle, a pilot signal is output. In accordance with the pulse width of the pilot signal, the plug-in vehicle is notified of the capacity of the current that can be supplied. When the pilot signal is detected, the plug-in vehicle prepares to start the charging operation (closing the relay, and the like).
The general power supply voltage for household use is 100V in Japan. However, the power supply voltage may be 200V, for example, in industrial facilities. Furthermore, the plug-in vehicle is also used in countries other than Japan. In the countries other than Japan, the power supply voltage for household use may be a voltage other than 100V. Accordingly, it is desirable that power supplies of various standards can be applied for charging of the plug-in vehicle.
Japanese Patent Laying-Open No. 10-285819 (Patent Document 1) discloses a charging apparatus including a voltage converting unit converting the voltage of the input electric power input from the outside to generate a direct-current (DC) electric power of a desired voltage and supplying the generated DC electric power to a battery; a voltage characteristic setting unit setting, for the voltage converting unit, a voltage characteristic in which the DC electric power supplied to the battery is less than or equal to a given maximum value; and a maximum value assigning unit receiving an instruction from the outside and, in response to the instruction, assigning a predetermined maximum value to the voltage characteristic setting unit.
According to the charging apparatus disclosed in this document, the maximum value of the charging electric power supplied to the battery is set to a predetermined value in accordance with the instruction given from the outside. Accordingly, the upper limit of the input electric power that is input for charging can be set to a desired value.    Patent Document 1: Japanese Patent Laying-Open No. 10-285819    Non-Patent Document 1: “Electric Vehicle Conductive Charging System General Requirements”, Japan Electric Vehicle Association Standards (Japan Electric Vehicle Standard), Mar. 29, 2001    Non-Patent Document 2: “SAE Electric Vehicle Conductive Charge Coupler” (the United States), SAE Standards, SAE International, November 2001