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;
• and
• a power supply circuit configured to supply alternating current power to the transmission coil, and
• 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 first rectifier circuit configured to rectify electric power received via the resonant circuit;
• a smoothing capacitor connected to the first rectifier circuit and configured to smooth a voltage outputted from the first rectifier circuit;
• a sub-coil arranged to be electromagnetically coupled to the reception coil;
• a second rectifier circuit connected between the sub-coil and the smoothing capacitor, and configured to output electric power according to a voltage generated in the sub-coil to the smoothing capacitor, in response to a first voltage obtained by rectifying a voltage generated in the sub-coil being higher than a voltage between both terminals of the smoothing capacitor;
• a first switch circuit connected to the sub-coil and configured to switch between short-circuiting and opening of both ends of the sub-coil;
• a voltage detection circuit configured to measure an output voltage from the smoothing capacitor to obtain a measured value of the output voltage;
• and
• a determination circuit configured to control the first switch circuit to short-circuit the both ends of the sub-coil in response to a measured value of the output voltage being equal to or larger than a first upper-limit threshold value, and wherein
• the power reception device further comprises a second switch circuit comprising a first end connected between the resonant capacitor and the first rectifier circuit, and a second end connected to a terminal of the reception coil on a side where the resonant capacitor is not connected, the second switch circuit being configured to switch between short-circuiting and opening of the resonant circuit, and
• the determination circuit controls the second switch circuit to short-circuit the resonance circuit in response to a measured value of the output voltage being equal to or greater than a second upper-limit threshold value that is greater than the first upper-limit threshold value.