Enhanced Parity-time Symmetric Range in Magnetically Coupled Resonant Wireless Power Transfer Systems Using High-Order S-SPC Topology

In wireless power transfer (WPT) systems, power transfer efficiency is highly sensitive to variations in load resistance and mutual coupling, especially when coils are misaligned. Such variations lead to decreased power transfer efficiency and instability, especially in medium-distance magnetically coupled resonant WPT (MCR-WPT) systems. Parity-time (PT)-symmetric WPT systems are known for their ability to deliver constant efficiency and output power under varying coupling conditions. However, the inherently narrow constant power (CP) region still poses a limitation for many real-world applications. To address these challenges, this paper proposes an innovative high-order series-series-parallel-capacitor (S-SPC) topology that significantly extends the PT-symmetric range with minimal component complexity. The system operates without requiring communication between the primary and secondary sides, ensuring simplified implementation while maintaining robust performance. The proposed topology significantly reduces the critical coupling coefficient by more than 50% compared to the SS topology, enabling a broader PT-symmetric operational range. By tuning resonant capacitor parameters, the PT-symmetric region can be flexibly adjusted to achieve CP output and improved tolerance to misalignment and load variations.