Analysis and Design of Post-Regulation Stages for Resonant Capacitively-Coupled Wireless Power Systems

This study introduces a power regulation design methodology for power receiving units (PRUs) in capacitively-coupled resonant wireless power transfer (RWPT) systems by using hybrid multi-level (HML) post-regulators. A generic design framework for capacitive RWPT systems with post-regulation stages is developed, followed by a simplified behavioral model for the PRU including the additional regulation stage. It has been demonstrated that by using HML stages for power-regulation, significantly wider impedance matching range can be achieved, which results in better spatial freedom of wireless power systems. This study also covers design tradeoffs between several post-regulators in terms of efficiency, coupling range and conversion range. A 40 W experimental resonant capacitively-coupled WPT system with HML buck (HMLB) post-regulator has been designed and examined up to 150 mm misalignment, at a resonant operation of 3 MHz. A very good agreement is obtained between the theoretical predictions and experimental results.