Analysis and Design of High-Frequency WPT System Using Load-Independent Inverter with Robustness Against Load Variations and Coil Misalignment

This paper presents an analysis and design of the load-independent (LI) high-frequency magnetic resonant wireless power transfer (MR-WPT) system with robustness against load variations and coil misalignments. It is clarified from the analysis that robustness against load variations and coil misalignment can be obtained when LI inverter, series-resonant to series-resonant (S-S) coupling topology, input-reactance invariant rectifier against load variations, and post regulator are adopted. The output reactance of the transmitter does not vary against load variations and coil misalignment. Therefore, the inverter works with the LI mode, achieving soft switching without control. As a result, the system ensures soft switching and output regulation against both load variations and coil misalignment without wireless communication feedback. The design example of the system with LI class-E/F inverter, class-D rectifier, and buck converter is given. The quantitative agreements between the analytical prediction and experiment show the effectiveness and validity of the system and its analysis.