Position-Independent Constant Current or Constant Voltage Wireless Electric Vehicles Charging System Without Dual-Side Communication and DC–DC Converter

In this article, a robust wireless power transfer (WPT) system considering a wide variation in load resistance and coupling coefficient is proposed for electric vehicles charging. Here, a new implementation of the parity-time (PT)-symmetric circuit using a phase synchronization method is presented, in which a power-adjustable negative resistor is constructed only by a single-stage inverter. Moreover, based on the PT-symmetric circuit, a control strategy that does not require dual-side communication and extra dc–dc converters is developed for battery charging. Theoretical analysis shows that constant current (CC) and constant voltage (CV) outputs independent of load and position can be achieved, and the charging mode can be switched automatically. A scaled-down prototype with an 8-A charging current and a 120-V charging voltage is built to verify the feasibility of the proposed method. Experimental results demonstrate that within the transfer distance of 10–25 cm, the CC/CV outputs can be maintained during the charging process.