Non-contact power feeding device

A non-contact power feeding device comprising a power transmission device and a power reception device to which electric power is transmitted from the power transmission device in a non-contact manner, wherein

• the power transmission device comprises:
• a transmission coil configured to supply electric power to the power reception device;
• a power supply circuit configured to supply alternating current power to the transmission coil, and adjust at least one of a switching frequency or a voltage of alternating current power supplied to the transmission coil:
• a magnetic field detector configured to detect a strength of a magnetic field generated from the transmission coil;
• and
• a control circuit configured to control the at least one of the switching frequency or the voltage of the alternating current power supplied from the power supply circuit to the transmission coil, based on a change over time in the strength of the magnetic field detected by the magnetic field detector,
• the power reception device comprises:
• a resonant circuit comprising a reception coil configured to receive electric power from the power transmission device, and a resonant capacitor connected in series with the reception coil;
• a rectifier circuit configured to rectify electric power received via the resonant circuit;
• a resonance suppression coil arranged to be electromagnetically coupled to the reception coil;
• and
• a second rectifier circuit connected between the resonance suppression coil and the smoothing capacitor, and configured to output electric power according to a voltage generated in the resonance suppression coil to the smoothing capacitor, in response to a voltage obtained by rectifying a voltage generated in the resonance suppression coil being higher than a voltage between both terminals of the smoothing capacitor,
• the rectifier circuit of the power reception device comprises a smoothing capacitor configured to smooth a voltage outputted from the rectifier circuit, and
• the control circuit of the power transmission device controls the voltage of the alternating current power supplied from the power supply circuit to the transmission coil, to lengthen a fluctuation cycle of the strength of the magnetic field.

A non-contact power feeding device comprising a power transmission device and a power reception device to which electric power is transmitted from the power transmission device in a non-contact manner, wherein

• the power transmission device comprises:
• a transmission coil configured to supply electric power to the power reception device;
• a power supply circuit configured to supply alternating current power to the transmission coil, and adjust at least one of a switching frequency or a voltage of alternating current power supplied to the transmission coil:
• a magnetic field detector configured to detect a strength of a magnetic field generated from the transmission coil;
• and
• a control circuit configured to control the at least one of the switching frequency or the voltage of the alternating current power supplied from the power supply circuit to the transmission coil, based on a change over time in the strength of the magnetic field detected by the magnetic field detector,
• the power reception device comprises:
• a resonant circuit comprising a reception coil configured to receive electric power from the power transmission device, and a resonant capacitor connected in series with the reception coil;
• a rectifier circuit configured to rectify electric power received via the resonant circuit;
• a resonance suppression coil arranged to be electromagnetically coupled to the reception coil;
• and
• a second rectifier circuit connected between the resonance suppression coil and the smoothing capacitor, and configured to output electric power according to a voltage generated in the resonance suppression coil to the smoothing capacitor, in response to a voltage obtained by rectifying a voltage generated in the resonance suppression coil being higher than a voltage between both terminals of the smoothing capacitor, the magnetic field detector is provided inside a winding wire of the transmission coil on a plane orthogonal to a winding axis of the winding wire of the transmission coil,
• the rectifier circuit of the power reception device comprises a smoothing capacitor configured to smooth a voltage outputted from the rectifier circuit, and the control circuit of the power transmission device controls the voltage of the alternating current power supplied from the power supply circuit to the transmission coil, to lengthen a fluctuation cycle of the strength of the magnetic field.