6.78‐MHz Double‐Transmitting Coils Class‐E ² Wireless Power Transfer System Based on Parity–Time Symmetry

ABSTRACT The parity–time (PT) symmetry principle has been widely used in the field of wireless power transfer (WPT) system, but the transmission frequency has not been a new breakthrough. In this paper, a design method of 6.78 MHz WPT system based on PT symmetry is proposed. The Class‐E power amplifier (PA) and Class‐E rectifier are adopted. The resonant tank adopts the scheme of double‐transmitting coils, which improves the transmission efficiency. Because the frequency is greatly improved, the critical coupling coefficient is also significantly reduced. We manufactured a 40‐W experimental prototype. Through experiments, we found that the transmission efficiency of the proposed design scheme reached 94.7%. In the exact PT‐symmetric region, the output voltage remains constant, which means that the system can transmit power stably and efficiently.