In-vehicle charging device and in-vehicle charging method

An in-vehicle charging method in which a DC power supply of a vehicle drive device is charged through an in-vehicle charging device to which power is supplied from an external AC power supply, the vehicle drive device including:

• a rotary electric machine including coils of a plurality of phases connected at a neutral point, the rotary electric machine serving as a driving power source for a wheel;
• an inverter configured to convert power between direct current and alternating current of a plurality of phases;
• and the DC power supply connected to the inverter,
• wherein
• the in-vehicle charging device includes:
• an AC-DC converter configured to convert AC power from the external AC power supply into DC power;
• a DC-DC converter configured to convert a voltage of the DC power converted by the AC-DC converter;
• a smoothing capacitor disposed between the AC-DC converter and the DC-DC converter, the smoothing capacitor being configured to smooth the voltage of the DC power converted by the AC-DC converter;
• and
• a control device configured to control the AC-DC converter and the DC-DC converter,
• either one of the AC-DC converter and the DC-DC converter being configured using the inverter and the coils of a plurality of phases,
• an AC-side terminal of the AC-DC converter being connected to the external AC power supply,
• a DC-side terminal of the AC-DC converter being connected to a first terminal of the DC-DC converter,
• a second terminal of the DC-DC converter being connected to the DC power supply, the second terminal of the DC-DC converter being different from the first terminal of the DC-DC converter,
• the in-vehicle charging method comprising:
• by the control device,
• setting a terminal voltage of the DC power supply exhibited when the DC power supply is in a fully charged state, as a first voltage, and setting a voltage that is lower than the first voltage and that is preset, as a second voltage,
• performing, as charging control, constant power charging control such that charging power based on a current flowing through the DC power supply and the terminal voltage of the DC power supply is constant, until the terminal voltage of the DC power supply reaches the second voltage from a state lower than the second voltage, and
• performing, in the constant power charging control, variable DC voltage control such that a terminal voltage of the smoothing capacitor increases in accordance with an increase in the terminal voltage of the DC power supply.