A Robust Parity-Time-Symmetric Hybrid Wireless Power Transfer System
with Extended Coupling Range
Abstract
Inductive wireless power transfer (IPT) and capacitive wireless
power transfer (CPT) are currently the two main wireless power transfer
technologies. Combining the coils of the IPT with the plates of the CPT
creates a hybrid wireless power transfer (HPT) system, which can improve
the transmission performance but introduces higher parameter
sensitivity. Therefore, achieving stable output power and constant
transfer efficiency over a wide range of coupling coefficient variations
is still a major challenge for HPT. In this work, the parity-time (PT)
symmetry theory is applied to an SS-type HPT system, and a circuit model
of the PT-based HPT system is developed by using coupling capacitance
and coupling inductance. The effect of connecting the plates to the
homonymous end or heteronymous end of the coupling coils on the
PT-symmetry range of the HPT system is discussed. It is found that the
heteronymous end connection of the coils can effectively increase the
range of constant output power and stable transfer efficiency. Finally,
a prototype is built to verify the feasibility and effectiveness of the
proposed PT-based HPT system. The transfer efficiency remains constant
in the PT-symmetric range, and the inductive and capacitive coupling
coefficients are smaller compared to IPT and CPT systems with the same
parameters.
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