Efficiency and Power of the Parity-Time-Symmetric Circuit for Wireless Power Transfer

The Parity-time-symmetric circuit with saturation mechanism has potential applications in robust and dynamic wireless power transfer. Here, we design a series circuit that corresponds to the existing parallel topology, to make the circuit duality complete. Based on the coupled-mode theory, we analyze the physical mechanism of PT-symmetric circuits working in strong and weak coupling states, and propose the linear saturation approximation method to theoretically calculate the transfer efficiency and power with considering the Joule loss of the negative resistance. The theoretical results are verified by simulation. Also, the optimal load, the appropriate voltage gain and other important parameters of the system are determined. Our results show that the parallel circuit transfers the voltage mode, while the series circuit transfers the current mode, exposing different transmission characteristics. The parallel circuit can maintain high transfer efficiency in a wide range of coupling coefficient k, but the transfer power is relatively low. Contrarily, the proposed series circuit can maintain high transfer power in a wide range of k. This investigation provides a basis for the parameter design of the nonlinear saturation PT-symmetric circuit for different transfer efficiency and power applications.