Robust Maximum Power Point Tracking for Parity–Time-Symmetric Wireless Power Transfer Systems in Broken/Exact Phases

This letter investigates a unified approach to achieve robust maximum power point tracking (MPPT) for the series–series parity–time (PT)-symmetric wireless power transfer system, considering both broken and exact PT phases. In the broken phase, MPPT is accomplished through load resistance tracking, while the operating frequency is fixed at the natural resonant frequency. In the exact phase, MPPT is realized via bifurcated frequency tracking, while the load resistance is kept untuned. Both theoretical and experimental analyses show that MPPT can be readily achieved and robustly maintained across a wide range of coupling coefficients in both PT phases. These findings are particularly applicable to wireless charging scenarios that simultaneously demand high power and robustness against misalignment.