Design Optimization of Multiple-Layer PSCs With Minimal Losses for Efficient and Robust Inductive Wireless Power Transfer

Inductive wireless Power Transfer (IPT) is a promising technology for remote powering of a wide variety of applications of electronic devices. To design IPT systems with the highest power transfer efficiency and the maximal robustness to coupling factor variations between transmitter and receiver of printed spiral coils (PSCs), high quality factors (
Q-Factor
) of the utilized PSCs are required. Designing PSCs with high
Q-Factor
is limited by the eddy current, the proximity effect, and parasitic losses. In this paper, PSC parasitic losses are carefully analyzed and specific design solutions are proposed. Genetic algorithm optimizations are developed to accommodate the proposed design solutions in minimizing losses. Single and multiple layer variable width PSCs are optimally designed with eddy current and proximity effect losses minimized. The designed PSCs are fabricated and experimental measurements are performed. The validity of the proposed approach to largely improve both IPT efficiency and robustness are confirmed. Using multiple coil layers, the robustness to axial and lateral coupling variations between coils is highly improved. For a triple-layer PSC design case, up to 3.5-fold improved robustness are obtained in reference to conventional IPT systems. Compared with the previous state of the art IPT topologies, the highest Figure-of-Merit value is obtained using the proposed design solutions.