A 6.78 MHz and 90% Efficiency Resonant Wireless Power Supply Technique With the Dual Voltage/Current Tuning Inductance to Supply 30 cm Short-Distance Base Stations for 5G Communications

This article proposes a dual voltage/current (V/C) inductance controller, which has good impedance tracking capability without any high-voltage stress problems. Besides, the proposed dual-mode phase-locked loop (D-PLL) technique can detect the phase difference between voltage and current of the antenna by fast tracking PLL and the accuracy-improved PLL for inductive and capacitive loads, thereby improving efficiency. Therefore, the 5G small base station on the receiver side (RX) can receive 27.8 W of power with 50% efficiency when the wall thickness to the transmitter side (TX) is 25.2 cm. In the case where the distance between TX and RX is close to zero, 50 W higher power with 90% efficiency can be achieved. Accordingly, the efficiency of resistive and inductive loads can be increased by 13% and 41%, respectively.