PT-Symmetric Wireless Power Transfer With Nonidentical Receivers

A self-oscillating source can adaptively track the eigenfrequency of a wireless power transfer (WPT) system, eliminating the drop in power delivered to the load (PDL) that arises from frequency splitting in the over-coupled region. Such systems exhibit parity-time (PT) symmetry. In multiload configurations, however, existing works traditionally required identical receivers. Here, we show that, when the detuning between the operating frequency and the intrinsic resonant frequency is much larger than the loss rate, multiple nonidentical receivers can be effectively synthesized into a single equivalent resonator. The overall system then approximately satisfies PT symmetry. The distribution of power among individual loads in this nonidentical-receiver case behaves identically to the special case of identical loads. Moreover, if the ratio of the coupling rates is held constant, both the total PDLs and the power-transfer efficiency remain unchanged as the distance varies. Our approach removes the identical-load restriction inherent to PT-symmetric multiload WPT and thus significantly broadens its practical applicability.