Adaptive Impedance Matching of Wireless Power Transmission Using Multi-Loop Feed With Single Operating Frequency

In this communication, an adaptive matching method to improve wireless power transmission (WPT) efficiencies using a multi-loop feed with a single operating frequency is described. The proposed method uses various combinations of multi-loop; adaptive matching is realized using switches attached to each loop. The average efficiencies of the simultaneous matching method, frequency tracking method, and the multi-loop feeding method are measured as 86.9%, 72.6%, and 81.8%, respectively, in the power transfer distance range of 10 cm to 50 cm. With only one operating frequency of 13.56 MHz, the proposed method can support high efficiency that is close to the efficiency of the simultaneous matching method and also shows better WPT efficiency than does the frequency tracking method.