Wireless power transmitter
AssigneeRohm Co., Ltd.
InventorsMasatoshi WATANABE, Tomoya MORINAGA
Life of this patent
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Abstract
A transmission antenna includes a resonance capacitor and a transmission coil coupled in series. A driver includes a bridge circuit that applies a driving voltage to the transmission antenna. A current sensor detects a current IS that flows through the bridge circuit. A foreign object detector detects the current IS that flows through the bridge circuit while changing the switching frequency applied to the bridge circuit. The foreign object detector judges the presence or absence of a foreign object based on the detection result.
Claims14
A wireless power transmitter structured to transmit an electric power signal to a wireless power receiver, the wireless power transmitter comprising:
- a transmission antenna comprising a resonance capacitor and a transmission coil coupled in series;
- a driver comprising a bridge circuit structured to apply a driving voltage to the transmission antenna;
- a current sensor structured to detect a current that flows trough the bridge circuit;
- and
- a foreign object detector structured to detect the current that flows through the bridge circuit while changing a switching frequency applied to the bridge circuit, and to judge a presence or absence of a foreign object based on detection results.
A foreign object detection method employed in a wireless power transmitter, wherein the wireless power transmitter comprises:
- a transmission antenna comprising a resonance capacitor and a transmission coil coupled in series;
- and
- a bridge circuit structured to apply a driving voltage to the transmission antenna,
- and wherein the foreign object detection method comprises:
- detecting a current that flows through the bridge circuit while changing a switching frequency of the bridge circuit;
- and
- judging the presence or absence of a foreign object based on a frequency f0 at which a peak of the current occurs, and a frequency f1 at which the current is smaller than the peak by a predetermined ratio between them.
Dependencies are inferred from the claim text.