Non-contact power supply device capable of performing constant voltage output operation

A non-contact power supply device comprising a power transmission device and a power reception device to which power is transmitted from the power transmission device without contact,

• wherein the power reception device comprises:
• a resonance circuit that includes a reception coil that receives power from the power transmission device and a resonance capacitor that, in conjunction with the reception coil, resonates with power from the power transmission device;
• and
• a rectification circuit that rectifies power output from the resonance circuit;
• a second coil that is connected in series with the reception coil between the resonance circuit and the rectification circuit;
• and
• wherein the reception coil and the resonance capacitor of the resonance circuit are connected in parallel with each other;
• and
• wherein the power transmission device comprises:
• a transmission coil that supplies power to the power reception device;
• a first coil that is connected in series with the transmission coil and is not coupled with the reception coil even while power is transmitted from the power transmission device to the power reception device;
• a first short-circuiting circuit that switches between short-circuiting and open-circuiting both ends of the first coil;
• a power supply circuit that supplies AC power having an adjustable switching frequency and having an adjustable voltage to the transmission coil;
• a control circuit that controls the adjustable switching frequency and voltage of the AC power supplied from the power supply circuit to the transmission coil and controls whether short-circuiting or open-circuiting both ends of the first coil via the first short-circuiting circuit;
• a current detection circuit that measures current flowing through the transmission coil and obtains a measured value of the current, and
• wherein the control circuit controls, depending on the measured value of the current, the adjustable switching frequency of the AC power supplied from the power supply circuit to the transmission coil and controls whether short-circuiting or open-circuiting both ends of the first coil via the first short-circuiting circuit.

A non-contact power supply device comprising a power transmission device and a power reception device to which power is transmitted from the power transmission device without contact,

• wherein the power reception device comprises:
• a resonance circuit that includes a reception coil that receives power from the power transmission device and a resonance capacitor that, in conjunction with the reception coil, resonates with power from the power transmission device;
• and
• a rectification circuit that rectifies power output from the resonance circuit;
• a determination circuit that determines, on the basis of the measured value of the output voltage, whether or not the non-contact power supply device is performing a constant voltage output operation and whether or not the measured value of the output voltage falls within a predetermined allowance range of voltage;
• a voltage detection circuit that measures output voltage of power output from the resonance circuit and obtains a measured value of the output voltage;
• and
• a second short-circuiting circuit that is capable of switching whether or not short-circuiting the resonance circuit;
• wherein the power transmission device comprises:
• a transmission coil that supplies power to the power reception device;
• a first coil that is connected in series with the transmission coil and is not coupled with the reception coil even while power is transmitted from the power transmission device to the power reception device;
• a first short-circuiting circuit that switches between short-circuiting and open-circuiting both ends of the first coil;
• a power supply circuit that supplies AC power having an adjustable switching frequency and having an adjustable voltage to the transmission coil;
• and
• a control circuit that controls the adjustable switching frequency and voltage of the AC power supplied from the power supply circuit to the transmission coil and controls whether short-circuiting or open-circuiting both ends of the first coil via the first short-circuiting circuit;
• a current detection circuit that measures current flowing through the transmission coil and obtains a measured value of the current;
• wherein the reception coil and the resonance capacitor of the resonance circuit of the power reception device are connected in series with each other,
• wherein when the measured value of the output voltage is out of the predetermined allowance range of voltage, the determination circuit makes the second short-circuiting circuit short-circuit the resonance circuit;
• and
• wherein the control circuit controls, depending on the measured value of the current, the adjustable switching frequency of the AC power supplied from the power supply circuit to the transmission coil and controls whether short-circuiting or open-circuiting both ends of the first coil via the first short-circuiting circuit.