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1. (WO2017174380) OBJECT DETECTION IN WIRELESS POWER TRANSFER SYSTEM

Pub. No.:    WO/2017/174380    International Application No.:    PCT/EP2017/057142
Publication Date: Fri Oct 13 01:59:59 CEST 2017 International Filing Date: Tue Mar 28 01:59:59 CEST 2017
IPC: H04B 5/00
H02J 50/60
Applicants: KONINKLIJKE PHILIPS N.V.
Inventors: MILLS, John Brean
Title: OBJECT DETECTION IN WIRELESS POWER TRANSFER SYSTEM
Abstract:
A power transmitter (22) for a wireless power transfer system comprises an output circuit comprising a transmit power inductor (25) generating a wireless power transfer signal. An object detector (43) for detection of an object extracting power from the power transfer signal includes a signal generator (501) generating first and second carrier signals. A first signal path (503) receives the first carrier signal and comprises a circulator (513) having a port coupled to the output circuit and a port providing a reflected signal from the output circuit. A second signal path (505) receives the second carrier signal and has a signal path equalizer (515) with a transfer function corresponding to a transfer function of the circulator (513). A mixer (507) mixes signals from the two signal paths (503) and a first detector (509) determines a reflection parameter for the output circuit in response to the mixed signal. A second detector (511) detects a presence of the object in response to the reflection parameter.