| 摘要 |
A wireless energy transmitter 100 comprises a resonance transformer 105 with transmitting coil 120, a controller 165 which changes the quality (Q) factor of the transformer 105 between a lower value for energy transmission and a higher value for foreign object detection. A determiner 185 detects a foreign object dependent on an electrical parameter (e.g. current, voltage, resonant frequency or Q factor) of the transformer 105. A second transmitting coil 135 may be provided, connected either in series or in parallel with the first coil 125 for low or high Q factor transmission respectively. The coils 125, 135 may transmit at low power with high Q factor, or high power with low Q factor. The coils 125, 135 may transmit at high frequency with high Q factor, or low frequency with low Q factor. The high Q factor mode may be enabled periodically, for a period much shorter than that of the low Q factor mode. The transmitter 100 may transmit power by magnetic induction.
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