Enhancing the quality factor of thin film printed coils for efficient wireless power transfer

Abstract

We introduce a technique to improve thin film printed coils for magnetically coupled resonance wireless power transfer (MCR-WPT). Thin film coils have a much higher resistance and lower quality factor Q than common copper wire because its very flat cross-section causes severe skin effect. We propose the divide-and-merge structure to successfully mitigate skin effect and improve the Q factor of thin film printed coils. With our method, a single-turn square coil with 10 cm sides achieved a higher Q at the high frequency used for MCR-WPT compared to other methods. Our method produced a 21% improvement in Q compared to double-sided parallel structure at 10 MHz despite using smaller copper volume.