A Dual-Band Wireless Power Transfer System With Efficiency-Boosting Converter

A dual-band wireless power transfer (WPT) system is proposed to satisfy multiple distinct-band WPT demands. A power amplifier combined with a dual-band output matching coil, which is relatively compact, is adopted to enable asynchronous two-band power transfer for multiple single-band receivers (RXs). The measurement results revealed that the efficiency reached 71% for both 6.78 and 13.56 MHz when the transmitter (TX) coil and RX coil were in alignment. However, the efficiency of a dual-band WPT system decreases when the spacing between the TX coil and RX coil deviates from its optimal distance. To address this concern, boost converters were used in the RX ends to achieve higher efficiency under coil misalignments. Efficiency improvement of 14% was obtained when the deviation of the RX coil from the alignment center of the TX coil was 5 cm.