In recent years, wireless power transfer (WPT) leveraging parity-time (PT) symmetry has progressed significantly, enhancing efficiency, transfer distance, and robustness. This paper overviews magnetic resonance WPT systems utilizing ideal, asymmetric, high-order, and anti-PT symmetry.
The first section discusses second-order PT symmetry, evolving from inductive to resonant WPT. Active tuning and nonlinear saturation gain techniques optimize frequency and spontaneously achieve efficient WPT. These methods improve transmission efficiency, especially with dynamic transfer distance changes. The second section covers third-order PT and anti-PT symmetry. Third-order PT systems maintain a fixed eigenfrequency, enabling stable energy transfer. Generalized PT symmetry harnesses bandgaps for further efficiency. BIC in asymmetric systems reveals a pure real mode for stable WPT. Anti-PT symmetry’s ‘level pinning’ maintains stability amidst dynamic changes. The final section summarizes high-order PT symmetry for long-range WPT. Heterojunction coupling and topologically non-trivial chains enhance efficiency and stability. Examples include long-range WPT via relay coils and directional WPT using asymmetric topological edge states.
In conclusion, this review underscores the pivotal role of PT symmetry, in its various forms, in advancing the performance and reliability of magnetic resonance WPT systems. By enhancing transmission efficiency, range, and stability, these symmetries pave the way for broader applications in fields such as smart homes, medical devices, and electric vehicles. The synthesis of current research findings offers valuable insights and serves as a reference for future developments in WPT technology.