Analysis and Design of High-Frequency CC/CV ZVS WPT System Without Any Feedback From Receiver to Transmitter

This paper proposes a high-frequency wireless power transfer (WPT) system. This system achieves zero-voltage switching (ZVS) and the constant current (CC) and constant voltage (CV) outputs regardless of load variations and coil misalignment. Furthermore, this system does not require feedback wireless communication from the receiver to the transmitter. Analytical expressions of the class-E inverter for achieving the ZVS against load variations without any control are given. By using the class-E ZVS inverter as a transmitter and complete resonance of the compensation circuits of the receiver in combination, the ZVS and CC/CV achievements become independent problems. Additionally, the proposed WPT system does not need wireless communication for information feedback. As a result, the proposed system achieves ZVS and CC/CV output switching against load variations and coil misalignments without any feedback. Experimental results agreed with the analytical predictions. Namely, the ZVS and the specified output current or voltage could be achieved against load variations and coil misalignments, which demonstrated the validity and effectiveness of the proposed system and its analysis. In the experiment, the maximum value of the power delivery efficiency was 87.2 % with the transmission frequency of 6.78 MHz and the output power of 50.7 W.