Analysis and Comparison of Resonant Compensation Topologies in Wireless Power Transfer Systems with Rectangular Planar Coils

Abstract

Wireless power transfer (WPT) based on resonant magnetic coupling is a promising technology for electric vehicle (EV) charging. This paper presents an analytical and comparative study of four fundamental compensation topologies—Series–Series (SS), Series–Parallel (SP), Parallel–Series (PS), and Parallel–Parallel (PP)—using rectangular planar transmitter and receiver coils. The rectangular geometry was selected for its suitability for ground-mounted EV charging pads and efficient use of installation space. Unlike previous studies that mainly focused on circular coils or limited topologies, this work provides a unified comparison of the four topologies under identical operating conditions. MATLAB simulations were conducted to evaluate the effects of air-gap distance on magnetic coupling, transferred power, and system efficiency. The coupling coefficient decreased from 0.4259 at 100 mm to 0.3337 at 200 mm, while mutual inductance decreased from 5.568 µH to 4.365 µH. At 100 mm, the SP topology achieved the highest load power of 14.64 W, whereas the PS topology achieved the lowest value of 4.26 W. The PP topology exhibited the highest efficiency of approximately 63%, while the SS topology remained below 40%. These results indicate that SP and PP are promising compensation topologies for medium-coupling WPT systems, particularly for EV wireless charging applications.