Performance Enhancement of Wireless Power Transfer Systems Through Coil Configuration and Class-E Power Amplifier Integration

Wireless Power Transfer (WPT) has emerged as a transformative technology for applications ranging from consumer electronics to biomedical devices and electric vehicles. However, achieving efficient power transfer over mid-range distances remains a significant challenge due to coupling variations and impedance mismatches. This study presents a comprehensive investigation into the integration of a modified Class-E power amplifier (PA) with optimized multi-coil configurations to enhance WPT efficiency. A comparative analysis between 3-coil and 4-coil resonant coupling systems focuses on power transfer efficiency (PTE), impedance matching, and adaptive tuning mechanisms. The proposed method leverages an optimized coupling strategy to mitigate power loss and ensure stable transmission. Experimental results demonstrate that the integrated Class-E PA improves PTE by over 20% at mid-range distances, achieving 80% efficiency within 5–30 cm while maintaining low insertion loss. Furthermore, the study highlights the advantages of 3-coil configurations for consumer electronics applications, offering simplified tuning and reduced system complexity compared to traditional 4-coil systems. The findings contribute to advancing high-efficiency WPT systems and their practical implementation in emerging wireless power applications. Unlike previous works that mainly relied on simulation, this study experimentally validates Class-E-driven 3- and 4-coil WPT systems, providing measured ZVS and switch-stress characteristics that demonstrate improved mid-range transfer efficiency.