Wireless electrical power supply apparatus

A wireless electrical power supply apparatus comprising:

• a first electrical power supply unit including:
• a first transmission coil;
• a first switching device connected in series to the first transmission coil;
• and
• a first resonant capacitor connected in parallel to either the first transmission coil or the first switching device, or both;
• a second electrical power supply unit including:
• a second transmission coil;
• a diode connected in series to the second transmission coil;
• and
• a second resonant capacitor connected in parallel to the second transmission coil;
• a first switching control circuit configured to control turn-off of the first switching device and also control turn-on of the first switching device in synchronization with a resonant voltage in the first electrical power supply unit such that the first switching device performs a zero-voltage switching operation;
• and
• a voltage control circuit configured to control a voltage difference between an input voltage to the first electrical power supply unit and an output voltage from the second electrical power supply unit during power transmission from the first electrical power supply unit to the second electrical power supply unit.

A wireless electrical power supply apparatus comprising:

• a first electrical power supply unit connected to a first DC power source;
• a second electrical power supply unit connected to a second DC power source;
• and
• a control portion configured to control the first electrical power supply unit and the second electrical power supply unit, wherein,
• the first electrical power supply unit and the second electrical power supply unit transmit power to each other,
• the first electrical power supply unit includes:
• a first transmission coil;
• a first switching device connected in series to the first transmission coil;
• and
• a first resonant capacitor connected in parallel to either the first transmission coil or the first switching device, or both,
• the second electrical power supply unit includes:
• a second transmission coil;
• a second switching device connected in series to the second transmission coil;
• and
• a second resonant capacitor connected in parallel to either the second transmission coil or the second switching device, or both, and
• the control portion includes:
• a first turn-on control circuit configured to control turn-on of the first switching device in synchronization with a resonant voltage induced by the first transmission coil and the first resonant capacitor such that the first switching device performs a zero-voltage switching operation;
• a second turn-on control circuit configured to control turn-on of the second switching device in synchronization with a resonant voltage induced by the second transmission coil and the second resonant capacitor such that the second switching device performs a zero-voltage switching operation;
• and
• a cross-phase shift control circuit configured to perform control to cause a predetermined phase difference between switching of the first switching device and switching of the second switching device.