The design of high quality factor bifilar archimedean coil geometries for wireless power transfer applications

Abstract

This thesis explores the optimization of a planar coil's geometry for wireless power transfer applications. Wireless power transfer is a popular field of study today due to its wide range of uses in professional and consumer applications. The transfer of data or power without the need for a wired connection allows for the design of increasingly robust and convenient electronic devices. However, wireless power transfer is still limited by poor power transfer efficiency and skew sensitivity under suboptimal conditions. For planar coils, optimal power transfer occurs when the transmitter and receiver coil are very closely spaced, with minimal misalignment between the two coils. This thesis proposes novel planar coil geometries which reduce the sensitivity of the coils to these attributes. The proposed geometries all have the same spatial footprint as the original planar coil to make the proposed changes practical in cases where the available area for the planar coil is limited, such as consumer smartphones. The best coil design exhibits an improvement in power transfer of up to 20% over separation distance, and up to 13% overall with lateral misalignment. The proposed designs enhance the performance of planar coils for wireless power transfer without requiring more board real estate to be dedicated to the coil geometry, maintaining a compact system design.