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.

中文翻译：

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具有效率提升转换器的双频无线电力传输系统

提出了一种双频带无线电力传输 (WPT) 系统来满足多个不同频带的 WPT 需求。采用功率放大器结合双频输出匹配线圈，体积相对较小，可实现多个单频接收器（RX）的异步双频功率传输。测量结果显示，当发射器 (TX) 线圈和 RX 线圈对齐时，6.78 和 13.56 MHz 的效率均达到 71%。然而，当 TX 线圈和 RX 线圈之间的间距偏离其最佳距离时，双频 WPT 系统的效率会降低。为了解决这个问题，在 RX 端使用升压转换器以在线圈未对准情况下实现更高的效率。当 RX 线圈与 TX 线圈对准中心的偏差为 5 cm 时，效率提高了 14%。