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Sağlam Ü, Tekin A. 2020. Resonance-filtering combo system for continuous wireless charging range coverage. Wireless Power Transfer 7(2): 116-125 doi: 10.1017/wpt.2020.12 
Resonance-filtering combo system for continuous wireless charging range coverage
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Author Bio:
Üstün Sağlam received the B.S. degree in electrical and electronics engineering from Hacettepe University, Ankara, Turkey in 2015. Since 2016, he has been the candidate of M.Sc. degree in electrical and electronics engineering at Ozyegin University. He is a senior design engineer at Power Electronics Research Center, Vestel Electronics, Manisa, Turkey. His research interests include the design and the development of switching mode power supplies and wireless power transfer systems. 
Ahmet Tekin has received his EE Ph.D. degree from University of California Santa Cruz, CA, EE MS degree from North Carolina A & T State University, Greensboro, NC and EE BS degree from Bogazici University, Istanbul, Turkey in 2008, 2004, and 2002, respectively. In addition to academic research in microelectronics, he worked for multiple innovative semiconductor design companies such as; Multigig, Inc., Newport Media, Aydeekay LLC, Broadcom corp., Semtech Corp., Nuvoton Technology Corp., Qualcomm and Waveworks Inc., leading designs for communications, consumer and medical markets. His main focus area is analog/ RF/mixed-signal integrated circuit design for communication and biomedical applications. He is currently director of Analog & RF Labs at Özyeğin University and serves as a member of board of directors at Waveworks Inc, Mission Viejo, CA - Corresponding author: Ahmet Tekin, Özyeğin University Analog & RF Research Labs, Istanbul, Turkey E-mail: ahmet.tekin@ozyegin.edu.tr
Abstract: Distribution of wireless power charging field uniformly on a large area pad is critical for power receivers, particularly for wearable devices, wherein small form factor coils are involved. Since the receiver coil size is quite limited in these types of applications, the device is very sensitive to the amount of field it could retain and hence, it needs special placement or snapping mechanism to fix it at an optimum location for reliable wireless charging. In order to overcome this limitation for the end-user, a dual-mode multi-coil power transceiver system is proposed; utilizing resonance filtering to increase the amount of total power delivered with the rather uniform spatial distribution. Two concentric coils; center one driven by 6.78-MHz high-frequency driver (A4WP) and the outer larger one with a 200-KHz low-frequency driver (Qi ) with resonant blocker could transfer up to 50 mW standards compliant flat power to a 13-mm radius 30-turns wearable receiver coil everywhere across an 8-cm radius charging pad area without any alignment requirement or snapping. Two different feedback topologies corresponding to each of the H-Bridge power drivers were also presented as an automatic series resonance coil drive frequency lock mechanism, extracting peak powers for each system individually from a standard 5 V-1A USB wall charger.
