We provided parity-time symmetry (PT symmetry) for a magnetic resonance wireless power transfer (WPT) system designed to operate below 20 kHz. A lightweight coil having a mass of 39.1 g and consisting of a Mn–Zn ferrite core and 0.6-mm-diameter copper wire is considered herein. The coil had a Q factor of 111.5 at 16.5 kHz. The proposed system oscillated at 16.5 kHz for a transmission distance of 15 mm. A transmission power of 7.6 W was achieved when the DC power supply voltage was 100 V. Under these conditions, the power efficiency between the two coils was 92.1%. The oscillation frequency was automatically tuned to the optimal frequency for obtaining the maximum efficiency for a changing transmission distance. The relationship between the transmission power and the transmission distance was very different from that of a conventional WPT system, and an effect of PT symmetry clearly appeared.

中文翻译：

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为低于 20 kHz 的低频无线电力传输提供奇偶时间对称性的方案

我们为设计为在 20 kHz 以下运行的磁共振无线电力传输 (WPT) 系统提供奇偶时间对称性 (PT 对称性)。此处考虑了质量为 39.1 g 且由 Mn-Zn 铁氧体磁芯和直径为 0.6 mm 的铜线组成的轻型线圈。线圈在 16.5 kHz 时的 Q 因数为 111.5。建议的系统以 16.5 kHz 的频率振荡，传输距离为 15 毫米。当直流电源电压为 100 V 时，传输功率为 7.6 W。在此条件下，两个线圈之间的功率效率为 92.1%。振荡频率自动调谐到最佳频率，以便在传输距离变化时获得最大效率。传输功率和传输距离之间的关系与传统的WPT系统有很大的不同，