A 6.78MHz Wireless Power Transfer System With 3-Mode Global Power Control

초록

This paper proposes wireless power transfer system(WPT) with 3-mode global power control loop to maintain high efficiency in the high-power range of watt-level systems. To enhance receiver efficiency, a single-stage 3- Mode regulating rectifier was employed. For the transmitter, Tx 3- Mode global power control was implemented using load-shift keying (LSK) signals to improve light-load and overall efficiency. The proposed Class-D Power Amplifier operates in 3 modes: 1X, 1×10.25X, and 0.25X. To reduce PCB area, the Tx sensing coil was replaced with an on-chip current sensor. A negative feedback loop was added to the stacked ramp generator in the receiver to compensate for delay caused by PVT (Process, Voltage, Temperature) variations. The proposed WPT system was designed using a O.13tLm BCD process and regulates a 5V output voltage. The RX peak efficiency is 95.5%, and the Rx and end-to-end (E2E) efficiency under light-load conditions improved by 11 % and 21.66%, respectively. © 2025 IEEE.

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