An analytical framework to design planar transmitting array antennas to mitigate lateral misalignment in wireless power transfer systems

Abstract

This paper presents a unique mathematical analysis of the magnetic field (H-field) forming using coil antennas to mitigate the lateral misalignment problem in the wireless power transfer (WPT) system. State of the art emphasizes generating uniform H-field distribution as a solution to the stated problem and for that large-sized transmitters are designed to enhance receiver working region. In this paper, by optimizing the field forming technique based on derived closed-form analytical expressions, a general non-uniform H-field distribution is proposed as an optimal solution to the misalignment problem. Through rigorous analysis, this work proposes a step-wise procedure for designing the transmitter coil array antenna to generate the non-uniform H-field distribution. To validate the model, two planar antenna arrays are designed by following the proposed procedure. This results in a uniform induced voltage profile under the misaligned Rx condition, hence, resolves the problem. The antenna designs are simulated, fabricated, and measured. The analytical results are found in agreement with the simulated results and further verified experimentally. The results indicate that the antennas designed using the proposed method are able to mitigate the lateral misalignment problem in a wider area of the receiver region with a smaller transmitter size.