Power and Distance Enhancement in Parity-Time Symmetric Magnetic Coupling Wireless Power Transfer Systems

The self-selecting frequency Parity-Time magnetic coupling wireless power transfer (MC-WPT) has garnered significant attention due to its strong position robustness. But its extremely low power has restricted its application. In this paper, a novel nonlinear asymmetric PT-symmetric MC-WPT system is proposed, which can self-select frequencies to achieve high power, high efficiency, and a broader range of energy output. Firstly, the key parameters that constrain power are analyzed, and corresponding criteria for enhancing power while ensuring a given efficiency are derived. Then, a novel negative resistance circuit is proposed, which has an output power that is four times that of the traditional circuit. Meanwhile, a new secondary side compensation topology is designed, introducing two new design parameters that can flexibly control the equivalent load and current amplitude ratio. This further enhances systems' power and increases the distance. The proposed system is derived and practically verified in a practical prototype. It confirmed that the proposed system is capable of achieving stable energy output without the need of any tunings. Compared to the PT-symmetric system, the power has been increased from 1W to 30W, achieving a 30-fold improvement, and the transfer distance has been increased from 11 cm to 32 cm.