Efficiency and robustness enhancement techniques for wireless power and data transfer systems

Abstract

Wireless power and data transfer (WPDT) techniques based on LC resonance have found widespread applications in electric vehicles, internet-of-things (IoTs), and implantable medical devices (IMDs). This research focuses on inductive link design and circuit techniques that improve power transfer efficiency and data transfer robustness. First, a theoretical model of the inductive link is discussed, which includes self-inductance, parasitic resistors, capacitors of the coils, and the coupling coefficient between the transmitting and the receiving coils. An optimization procedure is proposed to improve the efficiency of the inductive link. Second, a thin-film spiral inductor with multi-fin structure on a flexible substrate is proposed that can be used in a fully integrated wireless power transfer (WPT) system. A solid coil with the same dimension and copper thickness but without the multi-fin structure is designed for comparison. For the multi-fin coil, the parasitic resistance is reduced from 11.6Ω to 5.6Ω, and the quality factor is increased from 29.9 to 59.6, compared to the solid coil. A novel simulation procedure for the multi-fin coil has been proposed. Compared to the conventional procedure, the simulation time is significantly reduced with high accuracy. Third, the conditions leading to coupling-dependent data flipping (CDDF) problem of the load shift keying (LSK) scheme are analyzed and verified by SPICE simulations. An automatic carrier-frequency modulation scheme is proposed to prevent CDDF and is verified by measurement results. Finally, a 6.78MHz multiple-transmitter WPT system with an integrated coupling coefficient sensor (k-sensor) and a polarity sensor is proposed to relax the alignment requirements of WPDT systems. The multiple transmitters are adaptively controlled based on detecting the respective coupling coefficients and polarities to improve the power transfer efficiency.

Date of Award	2024
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Wing Hung KI (Supervisor) & Chi Ying TSUI (Supervisor)