Transmission Range Extension of PT-symmetry-based Wireless Power Transfer System
Abstract : The wireless power transfer (WPT) system based on parity-time (PT) symmetry has been proved to be a promising WPT system due to its characteristics of constant efficiency and output power. However, the PT-symmetric range is limited, and it is necessary to widen the PT-symmetric region to extend the distance of constant and efficient transmission. The novel PT-symmetry-based WPT system with an inductor added on the receiving circuit is proposed in this paper. Firstly, the model of the proposed system is established by utilizing the coupled mode theory (CMT), and the performance differences between the proposed system and the original PT-symmetric system are studied, and it is found that the critical coupling coefficient of the proposed system is smaller than that of the original PT-symmetric system. Secondly, to improve the efficiency of the proposed structure, the method of increasing the inductance of the transmitting coil is also put forward. Finally, the experimental results are basically consistent with the theoretical results, and the validity of the proposed approach is verified
? An isolated state (5.62 MHz) exists in the bandgap of the spectrum, which belongs to the TEM shown by red arrow.
? Inspired by the long-range WPT with TEMs in this work, it is expected to use more complex topological structures to achieve energy transmission with more functions, such as the WPT devices whose direction can be selected flexibly in the quasiperiodic or trimer topological chains.
? It can be clearly seen that two LED lamps with 0.5-W at both ends of the structure are lighted up with the aid of TEMs.
? To intuitively show the TEM can be used for WPT, a power signal source is used to excite the TEM.
? While the WPT technology has motivated considerable research and development in the past two decades, there are still several fundamental issues which need further investigation to maximize the potential of this technology.
? Traditional WPT systems are not robust against alteration of distance and misalignment between coils , and variations in the terminating impedance of an electric power grid or battery over time.
? This is because while a positive resistor causes energy dissipations, a negative resistor represents an energy source.
• Photonic topological edge modes (TEMs) can overcome the scattering losses caused by structural defects and disorders, which have been proposed for numerous topologically protected photonic devices, such as unidirectional waveguides , robust delay lines and single-mode lasers.
• As another effective solution, magnetic resonance WPT is proposed to achieve mid-range efficient energy transmission
• we recently proposed that the nontrivial dimer chain will provide a suitable platform for people to study the robust WPT in RF regime.
• On the one hand, similar to the Domino structure composed of the coupled resonators for long-range WPT [64], the topological dimer chain can be used to realize the efficient long-range WPT.
? Besides, the range of inductive power transfer remains a principal challenge. In spite of advances in various coil designs and the capability to create spatial Bessel beams, it remains difficult to overcome the performance deterioration due to the poor tolerance in coil misalignment, especially in the weak-coupling regime.
? In this system, high-efficiency power transfer always takes place at ?0, and the performance is rather insensitive to the offset between the receiver and the transmitting module (i.e., ? variations) and to changes in the receiver’s load impedance.
? To date, several techniques have been proposed to optimize the efficiency of power transfer, which include dynamic adjustment of operating frequency (resonant-frequency tracking), combination of multiple receivers and repeaters for adaptive impedance matching, and adding nonlinear tuning elements in circuits
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